Antifouling waterborne polyurethane material for ships and preparation method of antifouling waterborne polyurethane material

Abstract

The invention discloses an antifouling waterborne polyurethane material for ships and a preparation method thereof.The preparation method comprises the steps that polyester polyol and polyether polyol which are subjected to vacuum dehydration, diisocyanate, a catalyst and a chain extender are heated to 65-85 DEG C, a prepolymerization reaction is conducted, and a polyurethane prepolymer is obtained; adding sulphobetaine into the polyurethane prepolymer, and reacting at the temperature of 50 DEG C to obtain a modified polyurethane prepolymer; adding a butenolide emulsion, a stabilizer, a blocking agent and a defoaming agent into the modified polyurethane prepolymer, adjusting the pH value to 6-7, and stirring and mixing to obtain a butenolide-modified polyurethane prepolymer composite material; and adding a plasticizer and a reinforcing agent into the butenolide-modified polyurethane prepolymer composite material, and stirring for reaction to obtain the antifouling waterborne polyurethane material. Therefore, the waterborne polyurethane material has the functions of resisting bacteria and expelling marine attaching organisms, and the antifouling property of the waterborne polyurethane material is improved.

Description

Technical Field

[0001] The present invention relates to the field of waterborne polyurethane materials, in particular to an antifouling waterborne polyurethane material for ships and a preparation method thereof. Background Art

[0002] The ocean covers approximately 70% of the Earth's surface, and over 90% of global trade is carried by sea. Ships are crucial vehicles for this transport, but the vast oceans are home to millions of species of microorganisms, marine plants, and marine animals. During their service in the marine environment, marine organisms and microorganisms can attach to the bottoms of ships, fouling their hulls and other marine infrastructure. Biofouling can increase navigational resistance, corrode the hull metal, and damage marine instruments. Submarines and ships, whether submerged or on the surface, must be constructed from high-strength, rust-resistant materials and protected with antifouling coatings.

[0003] Waterborne polyurethane (PU) is a water-dispersible polyurethane dispersion. It is an environmentally friendly polymer material with zero VOC emissions and has been widely used in printing, coatings, adhesives, leather coatings, textile finishing, and other fields. The polyurethane structure can be engineered to produce a microphase separation structure, resulting in excellent resistance to protein adsorption and the inhibition of fouling organisms. This is currently a key development direction for antifouling materials for ships.

[0004] Although waterborne polyurethanes possess excellent properties such as outstanding mechanical strength, wear resistance, and flexibility, the introduction of hydrophilic groups into their structures results in a decrease in their water resistance, limiting their application. Prior art methods typically address this shortcoming by introducing highly hydrophobic segments into the polyurethane structure. Fluorine atoms are typically introduced to form C—F bonds, resulting in fluorinated waterborne polyurethanes with excellent water resistance, oil resistance, and antifouling properties. However, the use of excessive fluorine can negatively impact the aquatic environment and cause water pollution. Therefore, developing a novel antifouling waterborne polyurethane material for ships that optimizes its various properties to meet the specific environmental requirements of ships while reducing or eliminating environmental pollution is a pressing technical issue for those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides an antifouling waterborne polyurethane material for ships and a preparation method thereof. The waterborne polyurethane material can effectively combine the advantageous properties of sulfobetaine, butenolide and polyurethane, and utilizes a siloxane coupling agent as a reinforcing system to introduce siloxane hybrid atoms, thereby significantly enhancing the chemical resistance, water resistance and high temperature resistance of the waterborne polyurethane material, improving its antibacterial and anti-protein adsorption properties, effectively inhibiting the attachment of fouling organisms, and increasing the service life of the waterborne polyurethane material. In order to achieve the above object, the present invention proposes a method for preparing an antifouling waterborne polyurethane material for ships, comprising the following steps: S1. Heating the vacuum-dehydrated polyester polyol, polyether polyol, diisocyanate, catalyst, and chain extender to 65-85° C. for prepolymerization to obtain a polyurethane prepolymer; S2, dissolving sulfobetaine in an anhydrous solvent and adding the solvent to the polyurethane prepolymer, controlling the temperature at about 50° C., and reacting to obtain a modified polyurethane prepolymer; S3, adding the butenolide emulsion, stabilizer, blocker, and defoamer to the modified polyurethane prepolymer, adjusting the pH to 6-7, and stirring and mixing to obtain a butenolide-modified polyurethane prepolymer composite material; S4. Adding a plasticizer and a reinforcing agent to the butenolide-modified polyurethane prepolymer composite material, stirring and reacting for 1 to 2 hours to obtain an antifouling waterborne polyurethane material.

[0006] In some embodiments of the present invention, in step S1, the polyester polyol is one or more of polycaprolactone diol, polycarbonate diol and adipic acid polyester diol, the polyether polyol is one or more of polytetramethylene glycol, polyethylene glycol and polyethylene oxide glycol, the diisocyanate is one or more of toluene diisocyanate, 1,6-hexamethylene diisocyanate, cyclohexane dimethylene diisocyanate and xylene dimethylene diisocyanate, the catalyst is dibutyltin dilaurate, and the chain extender is one or more of 1,4-butanediol, 1,5-pentanediol, 1,2-propylene glycol and neopentyl glycol.

[0007] In some embodiments of the present invention, the mass ratio of the diisocyanate to the polyol is 1-5:4-14, the mass ratio of the polyester polyol to the polyether polyol is 4-7:1-3, the amount of the catalyst is 0.01-0.1% by mass of the polyurethane prepolymer, and the amount of the chain extender is 3-5% by mass of the polyurethane prepolymer.

[0008] In some embodiments of the present invention, step S1 includes: S1.1. Add polyester polyol and polyether polyol into a reaction vessel, heat to 100-120°C, and dehydrate under a vacuum of -0.095 MPa for 1-2 hours. S1.2. Cool to 60-70°C, slowly add diisocyanate and catalyst dropwise, raise the temperature to 75-85°C, react for 2-3 hours under nitrogen protection and stirring, cool to 65-75°C, add chain extender preheated to a molten state at 60°C, react rapidly with stirring for 45-60 minutes, and cool to 50°C to obtain a polyurethane prepolymer.

[0009] In some embodiments of the present invention, in step S2, the amount of sulfobetaine is 5-15% of the mass of the polyurethane prepolymer, the anhydrous solvent is N,N-dimethylformamide, and the amount of the anhydrous solvent is 50-80% of the mass of the polyurethane prepolymer.

[0010] In some embodiments of the present invention, step S2 includes: dissolving the polyurethane prepolymer in an anhydrous solvent, adding sulfobetaine, adjusting the pH to 7-7.5 with PBS buffer, reacting at 40-50° C. for 4-6 hours under nitrogen protection, and freeze-drying to obtain the modified polyurethane prepolymer.

[0011] In some embodiments of the present invention, in step S3, the mass ratio of the butenolide emulsion to the polyurethane prepolymer is 1~4:1~10, the stabilizer is nano-SiO2, and the amount of the stabilizer is 0.5~1.0% of the mass of the modified polyurethane prepolymer; the blocker is hydroxylamine hydrochloride, and the amount of the blocker is 0.1~0.3% of the mass of the modified polyurethane prepolymer; the defoamer is polyether-modified siloxane, and the amount of the defoamer is 0.05~0.1% of the mass of the modified polyurethane prepolymer; and the amount of trehalose is 2~5% of the mass of the modified polyurethane prepolymer.

[0012] In some embodiments of the present invention, step S3 includes: S3.1. Mix butenolide and Tween 80 in a mass ratio of 5:2, gently heat to 40°C to melt, slowly add 100 mL of deionized water preheated at 40°C, and shear using a high-speed homogenizer at a stirring speed of 10,000-12,000 rpm for 15 minutes to obtain a butenolide emulsion. S3.2. Place the modified polyurethane prepolymer in a reactor, place in a 25°C water bath, and stir at 200 rpm for 5 minutes. Then add trehalose and stir until completely dissolved. Then slowly add the butenolide emulsion dropwise at a control rate of 2 mL / min. Simultaneously adjust the stirring speed to 300-500 rpm, adjust the pH to 6-7 with PBS buffer, add stabilizer, blocker, and defoamer, and continue stirring at 300-500 rpm for 30 minutes until the system is unified. After filtering through a 200-mesh sieve, stand at 25°C in the dark for 2 hours to defoam, and obtain the final butenolide-modified polyurethane prepolymer composite material.

[0013] In some embodiments of the present invention, in step S4, the plasticizer is diisononyl phthalate, and the reinforcing agent is silane coupling agent KH550.

[0014] The present invention provides an antifouling waterborne polyurethane material for ships, which is prepared by the above-mentioned method. The antifouling waterborne polyurethane material comprises polyester polyol, polyether polyol, diisocyanate, catalyst, chain extender, sulfobetaine, anhydrous solvent, butenolide emulsion, stabilizer, blocker, defoamer, plasticizer, and reinforcing agent; wherein, The polyester polyol and polyether polyol are used to provide polyurethane flexible segments to improve the physical and mechanical properties of the anti-fouling waterborne polyurethane material; The diisocyanate is used to provide polyurethane hard segments and rigid structures, thereby enhancing the chemical stability of the antifouling waterborne polyurethane material; The sulfobetaine is used to provide a polyurethane zwitterionic structure, thereby imparting anti-protein adsorption and anti-fouling properties to the anti-fouling waterborne polyurethane material. The chain extender is used to connect the soft and hard segments of the polyurethane and regulate the microphase separation structure of the antifouling waterborne polyurethane material; The butenolide emulsion is used to provide an antifouling layer on the surface of the polyurethane, thereby improving the antibacterial and antifouling properties of the antifouling waterborne polyurethane material.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses polyester polyol, polyether polyol and diisocyanate to react to form a polyurethane prepolymer, and uses sulfobetaine to modify the polyurethane prepolymer. The secondary amine in the polyurethane prepolymer and the acrylate double bond in the sulfobetaine undergo Michael addition reaction, and the sulfobetaine is precisely grafted onto the polyurethane prepolymer. At the same time, the zwitterionic structure of the sulfobetaine is retained, so that the negatively charged sulfonic acid group and the positively charged quaternary ammonium group can play their roles independently, and the bactericidal property of the quaternary ammonium group and the anti-adhesion property of the sulfonic acid group can be combined with the advantages of the polyurethane resin, thereby effectively improving the antibacterial and anti-protein adsorption properties of the water-based polyurethane material, and achieving the purpose of high-efficiency anti-fouling.

[0016] (2) The present invention uses butenolide, Tween 80, and deionized water at 40°C and a stirring speed of 10,000-12,000 rpm for 15 minutes to prepare a butenolide emulsion. Tween 80 is a non-ionic surfactant (HLB=15). Its hydrophilic end (polyoxyethylene chain) will combine with deionized water, and the hydrophobic end (oleic acid chain) can wrap the butenolide molecules, thereby forming a uniform O / W emulsion. A reaction temperature of 40°C ensures complete melting of butenolide and prevents its high-temperature decomposition. A stirring speed of 10,000-12,000 rpm provides sufficient shear force to the emulsion, controlling the particle size of butenolide and dispersing the butenolide in the oil phase into tiny droplets with a particle size of <1 μm, thereby reducing its interfacial energy and achieving stable emulsification. This avoids stratification due to particle size mismatch between the emulsion droplets and the polyurethane dispersion when the butenolide emulsion is subsequently compounded with the modified polyurethane prepolymer.

[0017] (3) The present invention utilizes butenolide, trehalose, and modified polyurethane prepolymer to form a butenolide-modified polyurethane prepolymer composite material. The multiple hydroxyl groups (-OH) of trehalose and the ester groups (-COOR) of butenolide form an intermolecular hydrogen bond network, which can fix the molecular structure of butenolide through hydrogen bonds, protect the activity of butenolide, and prevent butenolide from hydrolysis. At the same time, trehalose forms an amorphous glassy matrix during the dehydration process, which wraps the butenolide molecules, improves its thermal stability, and prevents butenolide from thermal decomposition. By compounding butenolide, trehalose, and modified polyurethane prepolymer, the hydrophobic segments of the polyurethane prepolymer (such as polyester / polyether) and the oil phase of butenolide (Tween 80 micelles) will undergo hydrophobic interactions, achieving molecular-level dispersion and obtaining a uniform and stable butenolide-modified polyurethane prepolymer composite material. This can combine the bactericidal properties and marine biosorption removal functions of butenolide with the advantages of polyurethane resin, further improving the antibacterial and anti-biological adsorption properties of water-based polyurethane materials and enhancing the anti-fouling properties of water-based polyurethane materials.

[0018] (4) The present invention utilizes a siloxane coupling agent to form a reinforcing system, which acts as a surfactant and can effectively optimize the fluidity of the waterborne polyurethane material. The introduction of siloxane hybrid atoms also greatly improves the solvent resistance, water resistance and high temperature resistance of the waterborne polyurethane material, so that the waterborne polyurethane material can be highly effective in preventing fouling while having excellent performance, can cope with the special navigation environment of ships, and extend the service life of the waterborne polyurethane material. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] The present invention provides an antifouling waterborne polyurethane material for ships and a preparation method thereof, comprising the following steps: S1. Heating the vacuum-dehydrated polyester polyol, polyether polyol, diisocyanate, catalyst, and chain extender to 65-85° C. to carry out a prepolymerization reaction to obtain a polyurethane prepolymer.

[0021] In step S1, the polyester polyol is one or more of polycaprolactone diol, polycarbonate diol and adipic acid polyester diol, the polyether polyol is one or more of polytetramethylene ether diol, polyethylene glycol and polyethylene oxide diol, the diisocyanate is one or more of toluene diisocyanate, 1,6-hexamethylene diisocyanate, cyclohexane dimethylene diisocyanate and xylene diisocyanate, the catalyst is dibutyltin dilaurate, the chain extender is one or more of 1,4-butanediol, 1,5-pentanediol, 1,2-propylene glycol and neopentyl glycol, the mass ratio of diisocyanate to polyol is 1-5:4-14, the mass ratio of polyester polyol to polyether polyol is 4-7:1-3, the amount of the catalyst is 0.01-0.1% of the mass of the polyurethane prepolymer, and the amount of the chain extender is 3-5% of the mass of the polyurethane prepolymer.

[0022] Step S1 includes: S1.1. Add polyester polyol and polyether polyol into reaction vessels respectively, heat to 100-120°C and dehydrate under vacuum at -0.095 MPa for 1-2 hours.

[0023] High-temperature vacuum dehydration effectively removes trace moisture from polyester polyols and polyether polyols, ensuring a strictly dry reaction system and effectively preventing side reactions between isocyanate groups and water, producing urea bonds and CO₂, which can lead to bubbles or uncontrolled crosslinking. Controlling the system temperature between 100°C and 120°C ensures water evaporation while remaining below the polyol decomposition temperature (typically >150°C) to minimize polyol decomposition losses. A vacuum of -0.095 MPa reduces the system pressure to 5 kPa (absolute), lowering the boiling point of water to approximately 38°C and accelerating water removal. Dehydration at this temperature and vacuum for 1-2 hours effectively removes the majority of the water from the polyol raw materials, reducing the system moisture content to less than 0.05%, minimizing side reactions and raw material decomposition losses, and laying the foundation for efficient subsequent prepolymerization.

[0024] S1.2. Cool to 60-70°C, slowly add diisocyanate and catalyst dropwise, raise the temperature to 75-85°C, react for 2-3 hours under nitrogen protection and stirring, cool to 65-75°C, add chain extender preheated to a molten state at 60°C, react rapidly with stirring for 45-60 minutes, and cool to 50°C to obtain a polyurethane prepolymer.

[0025] Adding the diisocyanate dropwise at low temperatures avoids local overheating that can lead to side reactions (such as biuret and allophanate formation) and ensures uniform mixing. The catalyst's moderate activity at low temperatures ensures a controlled reaction. Furthermore, the temperature is controlled between 60 and 70°C, which is both above the melting point of the polyol, ensuring fluidity in the reaction system, and below the isocyanate's intense reaction temperature (>80°C), preventing premature reaction and reduced polyurethane prepolymer synthesis efficiency. Heating the temperature to 75 to 85°C accelerates the reaction rate, allowing -NCO and -OH to fully react to form urethane bonds, forming the backbone structure of the polyurethane material. This effectively balances the reaction rate with the risk of side reactions (gelation is likely to occur at temperatures above 85°C). The addition of nitrogen shielding isolates moisture, preventing the side reaction of airborne moisture with -NCO to form CO2 and urea bonds, thereby improving prepolymerization efficiency and product purity. Controlling the chain extension reaction temperature between 65°C and 75°C allows the chain extender to fully react with the prepolymer terminal -NCO group, extending the molecular chain and improving mechanical strength. This temperature is also lower than the main reaction temperature, reducing chain extender volatilization. Preheating the chain extender to a molten state (60°C) effectively prevents a sudden drop in temperature that can cause a sharp increase in system viscosity. Lowering the system temperature to 50°C can terminate the reaction promptly, prevent excessive cross-linking, and facilitate prepolymer storage.

[0026] Tracking the extent of NCO group consumption using titration allows researchers / producers to determine the remaining isocyanate concentration in the system during the reaction, allowing precise control of the reaction endpoint. Once monitoring indicates that the NCO group concentration has reached the target (preset concentration), nitrogen flow is immediately stopped and the next step can be performed, avoiding overreaction or continued side reactions (such as excessive cross-linking and uncontrolled molecular weight). Precise control of the prepolymer's chemical structure ensures that the final polyurethane prepolymer has a predictable NCO content and molecular weight distribution.

[0027] Take a polyurethane prepolymer sample from the middle of the reaction vessel, accurately weigh 1.000±0.005 g, add the sample to 50 mL of toluene, and stir magnetically at 300 rpm for 5 minutes until completely dissolved. Add 10.00 mL of di-n-butylamine-toluene solution, react in a 25°C water bath for 15 minutes, add 3 drops of bromocresol green, and titrate with 0.1 mol / L hydrochloric acid to the yellow end point. The volume of hydrochloric acid consumed is recorded as V1, and a blank control group is set up. The di-n-butylamine solution without sample is titrated in the same way, and the volume of hydrochloric acid consumed is V0. Calculate the concentration of the NCO group based on the volume of hydrochloric acid consumed to determine whether the reaction is complete. When the concentration of the NCO group reaches the set value, stop the reaction. The calculation formula is: in, V 0 is the volume of hydrochloric acid consumed by the blank control group, in mL; V 1 is the volume of hydrochloric acid consumed when titrating the sample, in mL; C HCl is the concentration of hydrochloric acid, 0.1 mol / L; m The sample is the mass of the polyurethane prepolymer sample, 1.000±0.005 g.

[0028] In the above detection process, the preset concentration of isocyanate groups is 0.02%~0.1%.

[0029] S2. Dissolve sulfobetaine in an anhydrous solvent and add the solvent to the polyurethane prepolymer. The temperature is controlled at about 50° C. to react to obtain a modified polyurethane prepolymer. In step S2, the sulfobetaine is used in an amount of 5 to 15% by weight of the polyurethane prepolymer, and the anhydrous solvent is N,N-dimethylformamide, and the amount of the anhydrous solvent is used in an amount of 50 to 80% by weight of the polyurethane prepolymer.

[0030] Step S2 includes: The polyurethane prepolymer is dissolved in an anhydrous solvent, and sulfobetaine is added, and the pH is adjusted to 7-7.5 with PBS buffer. The mixture is reacted at 40-50° C. for 4-6 hours under nitrogen protection, and the modified polyurethane prepolymer is obtained after freeze-drying.

[0031] The system pH was adjusted using PBS buffer, maintaining it between 7 and 7.5. The weak alkalinity of the system facilitates the reaction between -NCO and -OH / NH, while avoiding side reactions such as hydrolysis of the sulfonic acid group or excessive hydrolysis of -NCO that could occur under strong alkaline conditions. A nitrogen atmosphere minimizes solvent evaporation, effectively isolates moisture, prevents side reactions between airborne moisture and -NCO, and prevents the formation of CO2 bubbles. Maintaining the system temperature between 40 and 50°C balances the reaction rate with the thermal stability of the sulfobetaine, preventing high temperatures from damaging the heat-sensitive groups (e.g., quaternary ammonium salts typically decompose at temperatures >80°C) while ensuring a slow reaction of the -NCO group and minimizing the risk of gelation. The reaction of the polyurethane prepolymer with the sulfobetaine under mild conditions preserves the sulfonic acid (-SO⁻) and quaternary ammonium (-N⁺(CH⁃)⁃) groups, imparting zwitterionic antimicrobial and hydrophilic properties to the polyurethane material.

[0032] Sulfobetaine is a zwitterionic compound whose molecular structure contains a strongly acidic sulfonic acid functional group and a strongly basic quaternary ammonium ion. The quaternary ammonium group not only provides a positive charge and strong hydration capacity, but also disrupts microbial cell membranes, providing contact sterilization. The sulfonic acid group imparts a negative charge and chemical stability to the system. Simultaneously, it lowers surface energy, blocks the accumulation of quorum sensing signal molecules, inhibits bacterial adhesion, and acts as an anti-biofilm agent. Both sulfonic acid and quaternary ammonium groups bind water molecules to form a dense hydration layer, creating a barrier on the surface of the polyurethane prepolymer, effectively preventing surface contamination by proteins, bacteria, and biofilms, thereby significantly extending the material's service life. The coexistence of sulfonic acid and quaternary ammonium groups neutralizes charge, reducing the surface zeta potential of the polyurethane prepolymer system to approximately 0 mV. This eliminates the driving force for protein electrostatic adsorption and disrupts the interaction between the hydrophobic core of biological proteins and the surface of the waterborne polyurethane material, thus achieving protein adsorption resistance in the waterborne polyurethane material. Freeze-drying involves freezing the wet raw materials in the polyurethane prepolymer below freezing, converting the water content into solid ice. The ice is then removed by converting it directly into steam under a suitable vacuum environment. The water vapor is then condensed using a water vapor condenser in the vacuum system, drying the material. This vacuum freezing method involves the physical state change and movement of water, a process that occurs at low temperatures and pressures. This low temperature and pressure preserve the zwitterionic structure of sulfobetaine, preventing molecular chain rearrangement caused by high-temperature drying, which could result in the loss of the modified polyurethane prepolymer's anti-protein adsorption properties.

[0033] S3. Adding the butenolide emulsion, stabilizer, blocker, and defoamer to the modified polyurethane prepolymer, adjusting the pH to 6-7, and stirring and mixing to obtain a butenolide-modified polyurethane prepolymer composite material.

[0034] In step S3, the mass ratio of butenolide emulsion to polyurethane prepolymer is 1~4:1~10, the stabilizer is nano-SiO2, and the amount of the stabilizer is 0.5~1.0% of the mass of the modified polyurethane prepolymer; the blocker is hydroxylamine hydrochloride, and the amount of the blocker is 0.1~0.3% of the mass of the modified polyurethane prepolymer; the defoamer is polyether-modified siloxane, and the amount of the defoamer is 0.05~0.1% of the mass of the modified polyurethane prepolymer; and the amount of trehalose is 2~5% of the mass of the modified polyurethane prepolymer.

[0035] Step S3 includes: S3.1. Mix butenolide and Tween 80 in a mass ratio of 5:2, gently heat to 40°C to melt, slowly add 100 mL of deionized water preheated at 40°C, and shear using a high-speed homogenizer at a stirring speed of 10,000-12,000 rpm for 15 minutes to obtain a butenolide emulsion.

[0036] A butenolide emulsion was prepared using Tween 80. As a nonionic surfactant (HLB = 15), its hydrophilic end (polyoxyethylene chain) binds to deionized water, while its hydrophobic end (oleic acid chain) encapsulates butenolide molecules, forming an O / W emulsion. The system temperature was controlled at around 40°C. Since butenolide has a melting point of approximately 35–38°C and a thermal stability typically below 60°C, a 40°C reaction temperature ensures complete melting of butenolide and prevents its pyrolysis. Preheating the deionized water to 40°C prevents a sudden drop in temperature that could cause precipitation of Tween 80 or butenolide. The homogenizer speed was controlled at 10,000–12,000 rpm to provide sufficient shear force, dispersing the butenolide in the oil phase into tiny droplets with a size of less than 1 μm. This reduces interfacial energy and achieves stable emulsification. Shearing for 15 minutes at this temperature and stirring speed can effectively balance the emulsification efficiency, control the particle size of butenolide, and avoid stratification caused by the mismatch between the emulsion droplets and the polyurethane dispersion particle size.

[0037] Butenolide is a natural bioactive product extracted and isolated from a strain of Streptomyces found in deep-sea sediments. It possesses antibacterial and antifouling properties, making it non-toxic compared to chemical antifouling agents. It is a secondary metabolite produced by marine organisms with antifouling activity. Its natural compounds rapidly degrade without endangering biological life, contributing to the maintenance of ecological balance. Butenolide emulsion is compounded with modified polyurethane prepolymers to form a composite material. The butenolide emulsion forms small butenolide active particles that are evenly dispersed on the surface of the modified prepolymer. When encountering marine biofouling, it can quickly block the attachment signals of fouling organisms, preventing the attachment of plant and animal fouling organisms.

[0038] S3.2. Place the modified polyurethane prepolymer in a reactor, place in a 25°C water bath, and stir at 200 rpm for 5 minutes. Then add trehalose and stir until completely dissolved. Then slowly add the butenolide emulsion dropwise at a control rate of 2 mL / min. Simultaneously adjust the stirring speed to 300-500 rpm, adjust the pH to 6-7 with PBS buffer, add stabilizer, blocker, and defoamer, and continue stirring at 300-500 rpm for 30 minutes until the system is unified. After filtering through a 200-mesh sieve, stand at 25°C in the dark for 2 hours to defoam, and obtain the final butenolide-modified polyurethane prepolymer composite material.

[0039] The temperature was maintained at 25°C using a water bath. This precise control prevents excessive temperatures from causing thermal decomposition of butenolide and gelation of the polyurethane prepolymer, which could lead to a sudden increase in viscosity and affect the yield of the butenolide-modified polyurethane prepolymer composite. An initial low stirring speed of 200 rpm prevents splashing of the modified polyurethane prepolymer and resulting in material loss. Increasing the speed to 300-500 rpm during the addition of the butenolide emulsion ensures a Weber number of 4.2±0.5, effectively balancing dispersion efficiency with shear demulsification, ensuring the homogeneity and stability of the composite. PBS buffer was used to adjust the pH of the system to a range of 6-7, preventing protonation of the sulfonic acid groups or degradation of the quaternary ammonium groups caused by strong acid / alkaline environments. This ensures that the sulfonic acid groups (-SO⁻) and quaternary ammonium groups (-N⁺) remain ionized, thus ensuring the composite's resistance to protein adsorption. The composite was filtered through a 200-mesh sieve to remove aggregates ≥50 μm and ensure the composite's homogeneity. At this temperature, pH and stirring speed, the hydrophobic segments of the urethane prepolymer (such as polyester / polyether) will undergo hydrophobic interactions with the oil phase of butenolide (Tween 80 micelles), achieving molecular-level dispersion and obtaining a uniform and stable butenolide-modified polyurethane prepolymer composite material.

[0040] When trehalose is added to a butenolide-modified polyurethane prepolymer composite, the multiple hydroxyl groups (-OH) of trehalose form an intermolecular hydrogen bond network with the ester groups (-COOR) of butenolide. This hydrogen bond stabilizes the molecular structure of butenolide, protecting its activity and preventing its hydrolysis. Furthermore, during the dehydration process, trehalose forms an amorphous glassy matrix that encapsulates the butenolide molecules, improving their thermal stability and raising their decomposition temperature from 40°C to 60°C.

[0041] Nano-SiO2 acts as a stabilizer. The silanol group (-SiOH) on the surface of nano-SiO2 forms hydrogen bonds with the -NCO of the polyurethane prepolymer, constructing a physical barrier on the surface of the emulsion droplets, forming a steric hindrance to prevent Ostwald ripening. Moreover, at pH 6~7, the surface ζ potential of SiO2 is ≈-25 mV, which produces electrostatic repulsion with the sulfonic acid group (-SO3⁻), inhibiting particle aggregation and effectively ensuring the uniformity and stability of the composite system.

[0042] Hydroxylamine hydrochloride acts as a blocker. The -NH2 and -OH groups of hydroxylamine hydrochloride form a five-membered ring complex with metal ions such as Fe³⁺ / Cu²⁺, blocking their catalytic effect on polyurethane oxidation. At the same time, it can also quench the ·OH free radicals in the system and prevent the oxidation of the olefin bond of butenolide.

[0043] Polyether-modified silicone is used as a defoaming agent. The polyether hydrophilic segments and siloxane hydrophobic segments in the polyether-modified silicone will be arranged in a direction at the gas-liquid interface, destroying the elasticity of the foam film. In addition, the low viscosity of the polyether-modified silicone enables it to diffuse quickly to the foam surface, promoting the drainage and rupture of the liquid film.

[0044] S4, adding a plasticizer and a reinforcing agent to the butenolide-modified polyurethane prepolymer composite material, stirring and reacting for 1 to 2 hours to obtain an antifouling waterborne polyurethane material. In step S4, the plasticizer is diisononyl phthalate, and the reinforcing agent is silane coupling agent KH550.

[0045] As a plasticizer, diisononyl phthalate (DIHP) can form dipole-dipole interactions with polar groups (such as carbamate bonds and sulfonic acid groups) in the polyurethane molecular chain through its ester group. This allows it to intercalate between polymer chains, increasing the intersegment spacing, lowering the glass transition temperature, and improving the flexibility of waterborne polyurethane materials. Furthermore, at a processing temperature of 25°C, the plasticizer's benzene rings form a π-π stacking with the polyurethane hard segments, while the long-chain alkyl groups are compatible with the polyether / polyester soft segments, thereby achieving controllable regulation of the microphase separation structure.

[0046] Silane coupling agent KH550 is used as a reinforcing agent. Its ethoxy group (-OEt) will hydrolyze to form silanol (-SiOH), which will condense with nano-SiO2 or -OH / -NHCOO- in polyurethane to form Si-OC / Si-O-Si covalent bonds, while the amino group (-NH2) will react with the residual -NCO of the polyurethane prepolymer to build a "molecular bridge" at the organic-inorganic phase interface, thereby improving the tensile strength of the waterborne polyurethane material.

[0047] The prepared antifouling waterborne polyurethane material was poured into a mold and placed in a constant temperature and humidity chamber at 25°C and 50% relative humidity for 24 hours. It was then placed in a forced air drying oven at 80°C for curing for 2 hours. The sample was then cut into dumbbell-shaped specimens according to ISO 527-2, with a width of 4 mm and a thickness of 2 mm. The specimen was placed in a pneumatic horizontal push fixture, and the clamping distance was adjusted to 50.0 mm using an electronic gauge. A pre-tension of 0.1 N was applied. The specimen was subjected to a tensile test at a speed of 50 mm / min using a universal material testing machine at 25°C and 50% relative humidity. Specifically, The calculation formula for tensile strength is: in, F max is the maximum load, in N; oh is the width of the specimen, in mm; t is the thickness in mm.

[0048] The calculation formula for elongation at break is: in, L is the gauge length at fracture, in mm; L 0 is the original gauge length, 50 mm.

[0049] The prepared waterborne polyurethane material has a tensile strength of ≥15 MPa and an elongation at break of ≥300%. It has excellent impact resistance and can cope well with the special navigation environment of ships.

[0050] The present invention provides an antifouling waterborne polyurethane material for ships, which is prepared by a method for preparing the antifouling waterborne polyurethane material for ships. The antifouling waterborne polyurethane material comprises polyester polyol, polyether polyol, diisocyanate, catalyst, chain extender, sulfobetaine, anhydrous solvent, butenolide emulsion, stabilizer, blocker, defoamer, plasticizer, and enhancer; wherein, Polyester polyols and polyether polyols are used to provide polyurethane flexible segments to improve the physical and mechanical properties of the antifouling waterborne polyurethane material; The diisocyanate is used to provide polyurethane hard segments and rigid structures, thereby enhancing the chemical stability of the antifouling waterborne polyurethane material; The chain extender is used to connect the soft and hard segments of the polyurethane and regulate the microphase separation structure of the antifouling waterborne polyurethane material; Sulfobetaine is used to provide a zwitterionic structure of polyurethane, thereby imparting anti-protein adsorption and anti-fouling properties to the anti-fouling waterborne polyurethane material. The butenolide emulsion is used to provide an antifouling layer on the surface of the polyurethane, thereby improving the antibacterial and antifouling properties of the antifouling waterborne polyurethane material.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing an antifouling waterborne polyurethane material for ships, characterized in that the steps include: S1. Heating the vacuum-dehydrated polyester polyol, polyether polyol, diisocyanate, catalyst, and chain extender to 65-85° C. for prepolymerization to obtain a polyurethane prepolymer; S2, dissolving sulfobetaine in an anhydrous solvent and adding the solvent to the polyurethane prepolymer, controlling the temperature at about 50° C., and reacting to obtain a modified polyurethane prepolymer; S3, adding the butenolide emulsion, stabilizer, blocker, and defoamer to the modified polyurethane prepolymer, adjusting the pH to 6-7, and stirring and mixing to obtain a butenolide-modified polyurethane prepolymer composite material; S4. Adding a plasticizer and a reinforcing agent to the butenolide-modified polyurethane prepolymer composite material, stirring and reacting for 1 to 2 hours to obtain an antifouling waterborne polyurethane material.

2. The method for preparing an antifouling waterborne polyurethane material for ships according to claim 1, characterized in that: In step S1, the polyester polyol is one or more of polycaprolactone diol, polycarbonate diol and adipic acid polyester diol; the polyether polyol is one or more of polytetramethylene glycol, polyethylene glycol and polyethylene oxide glycol; the diisocyanate is one or more of toluene diisocyanate, 1,6-hexamethylene diisocyanate, cyclohexane dimethylene diisocyanate and xylene dimethylene diisocyanate; the catalyst is dibutyltin dilaurate; and the chain extender is one or more of 1,4-butanediol, 1,5-pentanediol, 1,2-propylene glycol and neopentyl glycol.

3. The method for preparing an antifouling waterborne polyurethane material for ships according to claim 1 or 2, characterized in that: The mass ratio of the diisocyanate to the polyol is 1-5:4-14; the mass ratio of the polyester polyol to the polyether polyol is 4-7:1-3; the amount of the catalyst is 0.01-0.1% of the mass of the polyurethane prepolymer; and the amount of the chain extender is 3-5% of the mass of the polyurethane prepolymer.

4. The method for preparing an antifouling waterborne polyurethane material for ships according to claim 1, characterized in that: Step S1 includes: S1.

1. Add polyester polyol and polyether polyol into a reaction vessel, heat to 100-120°C, and dehydrate under a vacuum of -0.095 MPa for 1-2 hours. S1.

2. Cool to 60-70°C, slowly add diisocyanate and catalyst dropwise, raise the temperature to 75-85°C, react for 2-3 hours under nitrogen protection and stirring, cool to 65-75°C, add chain extender preheated to a molten state at 60°C, react rapidly with stirring for 45-60 minutes, and cool to 50°C to obtain a polyurethane prepolymer.

5. The method for preparing an antifouling waterborne polyurethane material for ships according to claim 1, characterized in that: The amount of the sulfobetaine is 5-15% of the mass of the polyurethane prepolymer; the anhydrous solvent is N,N-dimethylformamide; and the amount of the anhydrous solvent is 50-80% of the mass of the polyurethane prepolymer.

6. The method for preparing an antifouling waterborne polyurethane material for ships according to claim 1, characterized in that: Step S2 comprises: dissolving the polyurethane prepolymer in an anhydrous solvent, adding sulfobetaine, adjusting the pH to 7-7.5 with PBS buffer, reacting at 40-50° C. for 4-6 hours under nitrogen protection, and freeze-drying to obtain the modified polyurethane prepolymer.

7. The method for preparing an antifouling waterborne polyurethane material for ships according to claim 1, characterized in that: The mass ratio of the butenolide emulsion to the polyurethane prepolymer is 1-4:1-10; the stabilizer is nano-SiO2; the amount of the stabilizer is 0.5-1.0% of the mass of the modified polyurethane prepolymer; the blocking agent is hydroxylamine hydrochloride; the amount of the blocking agent is 0.1-0.3% of the mass of the modified polyurethane prepolymer; the defoaming agent is polyether-modified siloxane; the amount of the defoaming agent is 0.05-0.1% of the mass of the modified polyurethane prepolymer; and the amount of trehalose is 2-5% of the mass of the modified polyurethane prepolymer.

8. The method for preparing a thermally conductive polyurethane adhesive according to claim 1, wherein: Step S3 includes: S3.

1. Mix butenolide and Tween 80 in a mass ratio of 5:2, gently heat to 40°C to melt, slowly add 100 mL of deionized water preheated at 40°C, and shear using a high-speed homogenizer at a stirring speed of 10,000-12,000 rpm for 15 minutes to obtain a butenolide emulsion. S3.

2. Place the modified polyurethane prepolymer in a reactor, place in a 25°C water bath, and stir at 200 rpm for 5 minutes. Then add trehalose and stir until completely dissolved. Then slowly add the butenolide emulsion dropwise at a control rate of 2 mL / min. Simultaneously adjust the stirring speed to 300-500 rpm, adjust the pH to 6-7 with PBS buffer, add stabilizer, blocker, and defoamer, and continue stirring at 300-500 rpm for 30 minutes until the system is unified. After filtering through a 200-mesh sieve, stand at 25°C in the dark for 2 hours to defoam, and obtain the final butenolide-modified polyurethane prepolymer composite material.

9. The method for preparing an antifouling waterborne polyurethane material for ships according to claim 1, characterized in that: The plasticizer is diisononyl phthalate; and the reinforcing agent is silane coupling agent KH550.

10. An antifouling waterborne polyurethane material for ships, characterized in that: The method for preparing an antifouling waterborne polyurethane material for ships according to any one of claims 1 to 9, wherein the antifouling waterborne polyurethane material comprises polyester polyol, polyether polyol, diisocyanate, catalyst, chain extender, sulfobetaine, anhydrous solvent, butenolide emulsion, stabilizer, blocker, defoamer, plasticizer, and enhancer; wherein, The polyester polyol and polyether polyol are used to provide polyurethane flexible segments to improve the physical and mechanical properties of the anti-fouling waterborne polyurethane material; The diisocyanate is used to provide polyurethane hard segments and rigid structures, thereby enhancing the chemical stability of the antifouling waterborne polyurethane material; The chain extender is used to connect the soft and hard segments of the polyurethane and regulate the microphase separation structure of the antifouling waterborne polyurethane material; The sulfobetaine is used to provide a polyurethane zwitterionic structure, thereby imparting anti-protein adsorption and anti-fouling properties to the anti-fouling waterborne polyurethane material. The butenolide emulsion is used to provide an antifouling layer on the surface of the polyurethane, thereby improving the antibacterial and antifouling properties of the antifouling waterborne polyurethane material.

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