A toluene triisocyanate-based polyurethane antifouling coating and a method for preparing the same

Abstract

The present invention provides a polyurethane antifouling coating containing toluene triisocyanate and its preparation method. First, a hydroxyl-terminated polysiloxane, or a mixture of hydroxyl-terminated polysiloxane, hydroxyl-terminated polyether, and hydroxyl-terminated polyester, is selected as a hydroxyl-terminated prepolymer. This prepolymer is mixed with an excess of isocyanate containing toluene triisocyanate, and the mixture is heated under an inert atmosphere until it melts and fuses. A catalyst catalyzes a capping reaction between the isocyanate and the hydroxyl-terminated prepolymer, generating an isocyanate-capped hydroxyl prepolymer. Next, the isocyanate-capped hydroxyl prepolymer undergoes a chain extension reaction with a fluorinated chain extender, thereby forming a fluorosilicone-containing polymeric polyurethane. This invention uses a small amount of toluene triisocyanate as a raw material component of the isocyanate, added to a formulation containing a high content of silicon-containing prepolymer and a fluorinated chain extender, to form a polyurethane antifouling coating. This significantly improves the adhesion between the polyurethane coating and the substrate, and increases the tensile strength and elongation at break of the polyurethane coating.

Description

Technical Field

[0001] This invention relates to the field of chemical and polymer materials technology, and in particular to a polyurethane antifouling coating based on toluene triisocyanate and its preparation method. Background Technology

[0002] Marine organisms adhering to the surface of ships can lead to decreased speed and increased fuel costs. Furthermore, the hull below the waterline can be corroded by acidic substances secreted by these organisms. Antifouling coatings are the most effective way to solve the problem of marine biofouling. Low surface energy antifouling coatings rely on their low surface energy to make it difficult for marine organisms to penetrate and adhere, thus achieving the purpose of antifouling. This is a green, environmentally friendly, and long-lasting antifouling method with broad prospects and application value.

[0003] However, existing low surface energy antifouling coatings still suffer from poor adhesion to the substrate and require further improvement. Summary of the Invention

[0004] In view of the above-mentioned problems in the prior art, the present invention designs and develops a polyurethane antifouling coating containing toluene triisocyanate and its preparation method, so as to maintain the low surface energy of the coating and improve the adhesion between the coating and the substrate.

[0005] The specific details of the invention are as follows:

[0006] In a first aspect, the present invention provides a method for preparing a polyurethane antifouling coating based on toluene triisocyanate, the method comprising:

[0007] Step 1: Under an inert atmosphere, the hydroxyl-terminated prepolymer is mixed with excess isocyanate and catalyst to form a mixed system, and heated to 50-90°C for 1-8 hours for end-capping reaction to form an isocyanate-terminated hydroxyl prepolymer system.

[0008] Step 2: Add a small molecule chain extender to the isocyanate-terminated hydroxyl prepolymer system, stir quickly and evenly, then coat it onto the substrate surface, and then transfer the substrate to an oven. The coating on the substrate surface undergoes a chain extension reaction at 60-120°C for 12-144 hours, and finally an anti-fouling coating is formed on the substrate surface.

[0009] The hydroxyl-terminated prepolymer is a hydroxyl-terminated polysiloxane, or a mixture of hydroxyl-terminated polysiloxane and hydroxyl-terminated polyether, or a mixture of hydroxyl-terminated polysiloxane and hydroxyl-terminated polyester.

[0010] The isocyanate is a mixture of toluene triisocyanate and diisocyanate;

[0011] The small molecule chain extender is a fluorinated diol, or a mixture of a fluorinated diol and an aliphatic diol.

[0012] The catalyst is dibutyltin dilaurate or triphenylbismuth.

[0013] Optionally, the amount of catalyst added accounts for 0.001% to 0.1% of the mass fraction of the mixed system.

[0014] Optionally, the R value of the chain extension reaction is 0.9 to 1.2.

[0015] Optionally, in the mixture formed by the hydroxyl-terminated polysiloxane and the hydroxyl-terminated polyether, the mass ratio of the hydroxyl-terminated polysiloxane to the hydroxyl-terminated polyether is 100:0 to 20:80.

[0016] In the mixture formed by the hydroxyl-terminated polysiloxane and the hydroxyl-terminated polyester, the mass ratio of the hydroxyl-terminated polysiloxane to the hydroxyl-terminated polyester is 100:0 to 20:80.

[0017] In the mixture formed by toluene triisocyanate and diisocyanate, the mass ratio of toluene triisocyanate to diisocyanate is 1:99 to 10:90;

[0018] In the mixture formed by the fluorinated diol and the aliphatic diol, the mass ratio of the fluorinated diol to the aliphatic diol is 100:0 to 20:80.

[0019] Optionally, the hydroxyl-terminated polysiloxane is hydroxypropyl polysiloxane;

[0020] The hydroxyl-terminated polyether is polytetrahydrofuran or tetrahydrofuran-ethylene oxide coether;

[0021] The hydroxyl-terminated polyester is polycaprolactone.

[0022] Optionally, the diisocyanate is toluene diisocyanate, hexamethylene diisocyanate, isoflurane diisocyanate, or dicyclohexylmethane diisocyanate.

[0023] Optionally, the fluorinated diol is 2,2,3,3-tetrafluoro-1,4-butanediol, 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, or 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol.

[0024] The aliphatic diol is ethylene glycol, 1,4-butanediol, 1,6-hexanediol, or diethylene glycol.

[0025] Optionally, the coating process includes brushing, pouring, scraping, or spraying.

[0026] Optionally, the substrate is an aluminum plate, a stainless steel plate, a cast iron plate, a PP plate, or a glass slide.

[0027] In a second aspect, the present invention provides a polyurethane antifouling coating based on toluene triisocyanate obtained by the preparation method described in the first aspect above.

[0028] The polyurethane antifouling coating based on toluene triisocyanate and its preparation method provided by the present invention have at least the following advantages:

[0029] The present invention provides a method for preparing a polyurethane antifouling coating based on toluene triisocyanate. First, under an inert atmosphere, a hydroxyl-terminated prepolymer is mixed with excess isocyanate and a catalyst to form a mixed system. This mixture is then heated to 50–90°C for 1–8 hours for a capping reaction, forming an isocyanate-capped hydroxyl prepolymer system. Next, a small-molecule chain extender is added to the isocyanate-capped hydroxyl prepolymer system, and after rapid stirring, it is coated onto a substrate surface. The substrate is then transferred to an oven, where the coating on the substrate surface undergoes a chain extension reaction at 60–120°C for 12–144 hours, ultimately forming an antifouling coating on the substrate surface. The preparation process uses a small amount of toluene triisocyanate as the isocyanate preparation raw material, which polymerizes with a silicon-containing prepolymer and a fluorinated chain extender to form a polyurethane network structure. This significantly improves the adhesion between the polyurethane coating and the substrate, and increases the tensile strength and elongation at break of the polyurethane coating. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A flowchart illustrating the preparation method of a polyurethane antifouling coating based on toluene triisocyanate provided in an embodiment of the present invention is shown. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0033] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0034] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0035] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0036] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] Existing low surface energy antifouling coatings are mainly divided into organosilicon series, organofluorine series and fluorosilicone series low surface energy antifouling coatings.

[0038] Low surface energy silicone antifouling coatings: Silicone compounds possess excellent elasticity, low surface energy, and low elastic modulus, and are chemically stable, making them suitable for the development of low surface energy antifouling coatings that prevent marine organisms from adhering. The development of low surface energy silicone antifouling coatings has been exceptionally rapid in recent years. AkzoNobel launched the Intersleek series of low surface energy silicone antifouling coatings, which exhibit excellent drag reduction and antifouling properties. Sakamoto et al. synthesized silicone oils with different molar masses containing polyether chains and long-chain alkyl (aryl) groups, and added them to silicone resins in different proportions to prepare corresponding antifouling coatings. During application, the silicone oil in the coating slowly migrates and seeps to the surface, reducing the surface energy of the coating and making it difficult for marine organisms to adhere, thus achieving an antifouling effect. The antifouling effect of this coating can last for more than two years. However, silicone resins have relatively poor mechanical properties.

[0039] Organofluorine low surface energy antifouling coatings: Fluorine has high electronegativity and a small atomic radius, resulting in compounds with high bond energy and stability. The mutual repulsion between fluorine atoms reduces the polarity of fluorine-containing compounds, thus giving them very low surface energy, making them suitable for preparing organofluorine low surface energy antifouling coatings. Sun et al. used azobisisobutyronitrile (AIB) as an initiator and, through free radical polymerization, blended different proportions of N-(3,4-dihydroxyphenyl)ethanedimethylacrylamide and 2,2,2-trifluoroethyl methacrylate to obtain a methacrylic acid resin copolymer with fluorinated side groups. This copolymer was then used to prepare an antifouling coating, exhibiting excellent antifouling performance and potential for the development and application of environmentally friendly marine antifouling coatings. Oldani et al. prepared α,ω-triethoxysilane-terminated perfluoropolyethers and α,ω-ammonium phosphate-terminated perfluoropolyethers, and then added nano-TiO2 or ZrO2 powder to prepare organofluorine low surface energy antifouling coatings and tested their performance. The results showed that this antifouling coating was superior to simple perfluoropolymers.

[0040] Fluorosilicone low surface energy antifouling coatings: Fluorosilicone coatings combine the advantages of both organosilicon and organofluorine antifouling coatings, making them superior low surface energy antifouling coatings. Huang Fangfang et al. synthesized fluorosilicone-modified acrylic resin, using it as a base material and adding functional fillers and additives such as nano-SiO2 to prepare a superhydrophobic antifouling coating with excellent antifouling performance. Martinelli et al. synthesized a copolymer with polydimethylsiloxane and polyethylene glycol-modified fluoroalkyl polystyrene blocks via atom transfer radical synthesis. This copolymer was then blended with polydimethylsiloxane to prepare a fluorosilicone low surface energy antifouling coating. Test results showed that this coating exhibited excellent antifouling performance against large algae. However, fluorosilicone resins still suffer from poor adhesion to the substrate, requiring further improvement.

[0041] Addressing the aforementioned issue of poor adhesion between fluorosilicone resins and substrates, this invention leverages the excellent bonding and mechanical properties of toluene triisocyanate (TTI) as a raw material for preparing fluorosilicone low surface energy antifouling coatings, thereby improving the adhesion of these coatings to the substrate. Specific implementation details are as follows:

[0042] In a first aspect, the present invention provides a method for preparing a polyurethane antifouling coating based on toluene triisocyanate. Figure 1 A flowchart illustrating the preparation method of a polyurethane antifouling coating based on toluene triisocyanate provided in an embodiment of the present invention is shown, as follows: Figure 1 As shown, the preparation method includes:

[0043] S1. Under an inert atmosphere, the hydroxyl-terminated prepolymer is mixed with excess isocyanate and catalyst to form a mixed system, and heated to 50-90°C for 1-8 hours for end-capping reaction to form an isocyanate-terminated hydroxyl prepolymer system.

[0044] S2. Add a small molecule chain extender to the isocyanate-terminated hydroxyl prepolymer system, stir quickly and evenly, then coat it onto the substrate surface, and then transfer the substrate to an oven. The coating on the substrate surface undergoes a chain extension reaction at 60-120°C for 12-144 hours, and finally an anti-fouling coating is formed on the substrate surface.

[0045] The hydroxyl-terminated prepolymer is a hydroxyl-terminated polysiloxane, or a mixture of hydroxyl-terminated polysiloxane and hydroxyl-terminated polyether, or a mixture of hydroxyl-terminated polysiloxane and hydroxyl-terminated polyester.

[0046] Isocyanates are mixtures formed from toluene triisocyanate and diisocyanate;

[0047] Small molecule chain extenders are fluorinated diols, or mixtures of fluorinated diols and aliphatic diols.

[0048] The catalyst is dibutyltin dilaurate or triphenylbismuth.

[0049] This invention takes advantage of the excellent adhesion and mechanical properties of toluene triisocyanate (TTI) and uses it in the preparation of antifouling coatings to improve the adhesion of the antifouling coating to the substrate. Specifically, this invention uses a two-step melt-melt method to prepare the antifouling coating. First, a hydroxyl-terminated polysiloxane, or a mixture of hydroxyl-terminated polysiloxane, hydroxyl-terminated polyether, and hydroxyl-terminated polyester, is selected as the hydroxyl-terminated prepolymer. This prepolymer is mixed with an excess of isocyanate containing toluene triisocyanate (TTI), and the mixture is heated to melt and fuse under an inert atmosphere. A catalyst catalyzes a capping reaction between the isocyanate and the hydroxyl-terminated prepolymer, generating an isocyanate-capped hydroxyl prepolymer. Next, the isocyanate-capped hydroxyl prepolymer undergoes a chain extension reaction with a fluorinated chain extender (small molecule chain extender) at 60–120°C. The R value (molar ratio of isocyanate groups to hydroxyl groups) of the chain extension reaction is 0.9–1.2, thereby forming a fluorosilicone-containing polymer polyurethane.

[0050] This invention uses a small amount of toluene triisocyanate as a raw material component of isocyanate, which is added to a formulation containing high-content silicon-containing prepolymer and fluorine-containing chain extender to form a polyurethane antifouling coating. This significantly improves the adhesion between the polyurethane coating and the substrate, and increases the tensile strength and elongation at break of the polyurethane coating.

[0051] In some embodiments, when the selected hydroxyl-terminated prepolymer is a mixture of hydroxyl-terminated polysiloxane and hydroxyl-terminated polyether or hydroxyl-terminated polyester, the hydroxyl-terminated polysiloxane may be selected from hydroxypropyl polysiloxane, the hydroxyl-terminated polyether may be selected from polytetrahydrofuran or tetrahydrofuran-ethylene oxide coether, and the hydroxyl-terminated polyester may be selected from polycaprolactone; the mass ratio of hydroxyl-terminated polysiloxane to hydroxyl-terminated polyether, or hydroxyl-terminated polysiloxane to hydroxyl-terminated polyester, is controlled within 100:0 to 20:80.

[0052] In some embodiments, the isocyanate that undergoes the end-capping reaction with the hydroxyl-terminated prepolymer is selected from a mixed isocyanate formed by toluene triisocyanate and diisocyanate in a mass ratio of 1:99 to 10:90, wherein the diisocyanate may be selected from toluene diisocyanate, hexamethylene diisocyanate, isoflurane diisocyanate or dicyclohexylmethane diisocyanate.

[0053] In some embodiments, the small molecule chain extender is selected from a mixture of a fluorinated diol and an aliphatic diol in a mass ratio of 100:0 to 20:80. The fluorinated diol may be selected from 2,2,3,3-tetrafluoro-1,4-butanediol, 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, or 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol; the aliphatic diol may be selected from ethylene glycol, 1,4-butanediol, 1,6-hexanediol, or diethylene glycol.

[0054] In practice, the isocyanate-terminated hydroxyl prepolymer is rapidly and uniformly mixed with a fluorinated chain extender. The mixture is then evacuated to remove air, preventing air bubbles from forming during coating and affecting the antifouling coating's performance. Coating processes include brushing, pouring, scraping, or spraying.

[0055] The polyurethane antifouling coating based on toluene triisocyanate proposed in this invention has a wide range of coating objects, including aluminum plates, stainless steel plates, cast iron plates, PP plates, or glass slides.

[0056] In a second aspect, the present invention provides a polyurethane antifouling coating based on toluene triisocyanate obtained by the preparation method of the first aspect described above.

[0057] To enable those skilled in the art to more clearly understand the present invention, the following embodiments are provided to illustrate in detail the polyurethane antifouling coating based on toluene triisocyanate and its preparation method.

[0058] Example 1

[0059] Weigh 7.1g of hydroxypropyl polysiloxane, 7.1g of tetrahydrofuran-ethylene oxide coether, 4.4015g of toluene diisocyanate (TDI), and 1 drop of dibutyltin dilaurate (1wt%) into a three-necked flask. Vacuum the flask, purge with argon three times, and react at 75°C for 1 hour. Then add 45mg of toluene triisocyanate (TTI) and continue reacting for 2 hours. Vacuum the flask again until no bubbles are generated. Under an argon atmosphere, rapidly add 779mg of 1,4-butanediol (BDO) and 2.268g of 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol. Stir vigorously for 1 minute, then stop stirring (to ensure even mixing). Vacuum the flask again until no bubbles are generated (pour into a mold to prevent bubble formation). Quickly pour into a preheated PTFE mold and cure in a vacuum drying oven (nitrogen atmosphere, 80°C for 4 days). After 7 days at room temperature in the drying oven, perform mechanical property testing.

[0060] Coating Preparation: Before applying the antifouling coating, the substrate is pretreated. Dust and solid residue on the substrate surface are removed with a dry, clean cloth. Then, the substrate surface is wiped with a small amount of anhydrous ethanol to remove oil stains. The substrate must be dry before use. The mixture obtained from the above reaction, after vigorous stirring, is poured onto the treated aluminum plate, stainless steel plate, cast iron plate, PP plate, and glass slide surface, respectively. The coating is applied to the substrate using an automatic coating machine, ensuring a smooth and uniform coating. The coated substrate is then cured in a vacuum drying oven at 80 degrees Celsius for 7 days under nitrogen protection before being placed in a desiccator. After being placed in the drying oven at room temperature for 7 days, adhesion and contact angle tests are performed.

[0061] Example 2

[0062] Weigh 14g of hydroxypropyl polysiloxane and 4.3855g of toluene diisocyanate (TDI) into a three-necked flask. Vacuum and argon gas are repeatedly applied three times, and the reaction is carried out at 90°C for 2 hours. Then, 43mg of TTI is added to the reaction system, and the reaction continues for another 2 hours. Afterward, mechanical stirring is stopped, and vacuum is applied until no bubbles are generated. Under an argon gas flow, 3.74g of 2,2,3,3,4,4-hexafluoro-1,5-pentanediol and 1 drop of dibutyltin dilaurate (1wt%) are rapidly added. Stirring is performed vigorously for 1 minute, then stirring is stopped, and vacuum is applied until no bubbles are generated. The mixture is quickly poured into a preheated PTFE mold and placed in a vacuum drying oven for curing (nitrogen atmosphere, 90°C for 3 days). Mechanical properties are tested after placing the mold in a drying oven at room temperature for 7 days.

[0063] Coating Preparation: Before applying the antifouling coating, the substrate is pretreated. Dust and solid residue on the substrate surface are removed with a dry, clean cloth. Then, the substrate surface is wiped with a small amount of anhydrous ethanol to remove oil stains. The substrate must be dry before use. The mixture obtained from the above reaction, after vigorous stirring, is poured onto the treated aluminum plate, stainless steel plate, cast iron plate, PP plate, and glass slide surface, respectively. The coating is dissolved in anhydrous ethyl acetate and evenly applied to the substrate using a spraying device. The ethyl acetate is removed in an 80°C oven; this process is repeated three times. The coated substrate is then cured in a vacuum drying oven at 90°C for 3 days under nitrogen protection before being placed in a desiccator. After being placed in a drying oven at room temperature for 7 days, adhesion and contact angle tests are performed.

[0064] Example 3

[0065] Weigh 8.4 g of PTMG, 5.6 g of hydroxypropyl polysiloxane, and 4.3232 g of TDI into a three-necked flask. Vacuum the flask, purge with argon three times, and react at 60°C for 2 hours. Add 111 mg of TTI to the reaction system and continue reacting for 6 hours. Stop mechanical stirring and evacuate until no bubbles are generated. Under an argon atmosphere, rapidly add 922 mg of diethylene glycol, 1.41 g of 2,2,3,3-tetrafluoro-1,4-butanediol, and 1 drop of triphenylbismuth (1 wt%). Stir vigorously for 1 minute, then stop stirring and evacuate until no bubbles are generated. Quickly pour the mixture into a preheated PTFE mold and place it in a vacuum drying oven for curing (nitrogen atmosphere, 60°C for 6 days).

[0066] Coating Preparation: Before applying the antifouling coating, the substrate is pretreated. Dust and solid residue on the substrate surface are removed with a dry, clean cloth. Then, the substrate surface is wiped with a small amount of anhydrous ethanol to remove oil stains. The substrate must be dry before use. The mixture obtained by vigorous stirring is poured onto the treated aluminum plate, stainless steel plate, cast iron plate, PP plate, and glass slide, respectively. The coating is evenly brushed onto the substrate. The coated substrate is then cured in a vacuum drying oven at 60 degrees Celsius for 6 days under nitrogen protection before being placed in a desiccator. After being placed in the drying oven at room temperature for 7 days, adhesion and contact angle tests are performed.

[0067] Example 4

[0068] Weigh 7.15g of hydroxypropyl polysiloxane, 7.15g of polycaprolactone, and 4.4651g of TDI into a three-necked flask. Vacuum the flask, purge with argon three times, and react at 70°C for 3 hours. Add 235mg of TTI to the reaction system and continue reacting for another 3 hours. Stop mechanical stirring and evacuate until no more bubbles are generated. Under an argon atmosphere, rapidly add 1.062g of 1,6-hexanediol, 1.458g of 2,2,3,3-tetrafluoro-1,4-butanediol, and 1 drop of dibutyltin dilaurate (1wt%). Stir vigorously for 1 minute, then stop stirring and evacuate until no more bubbles are generated. Quickly pour the mixture into a preheated PTFE mold and place it in a vacuum drying oven for curing (nitrogen atmosphere, 70°C for 5 days).

[0069] Coating Preparation: Before applying the antifouling coating, the substrate is pretreated. Dust and solid residue on the substrate surface are removed with a dry, clean cloth. Then, the substrate surface is wiped with a small amount of anhydrous ethanol to remove oil stains. The substrate must be dry before use. The mixture obtained from the above reaction, after vigorous stirring, is poured onto the treated aluminum plate, stainless steel plate, cast iron plate, PP plate, and glass slide surface, respectively. The coating is applied to the substrate using an automatic coating machine, ensuring a smooth and uniform coating. The coated substrate is then cured in a vacuum drying oven at 70 degrees Celsius for 5 days under nitrogen protection before being placed in a desiccator. After being placed in the drying oven at room temperature for 7 days, adhesion and contact angle tests are performed.

[0070] The performance test results are shown in Table 1. The results show that the adhesion of the coatings obtained in Examples 1-4 is greater than 2 MPa, demonstrating the excellent adhesive properties of toluene triisocyanate. When a mixture of hydroxyl-terminated polysiloxane and hydroxyl-terminated polyether or hydroxyl-terminated polyester is used as the prepolymer, the adhesion, tensile strength and elongation at break are all significantly improved.

[0071] Table 1 Performance test data of polyurethane antifouling coating

[0072] Example Adhesion Tensile strength (MPa) Elongation at break (%) 1 4.33 9.46 520 2 2.20 3.86 91 3 7.15 11.82 987 4 3.74 10.44 545

[0073] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0074] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0075] The present invention provides a detailed description of a polyurethane antifouling coating based on toluene triisocyanate and its preparation method. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a polyurethane antifouling coating based on toluene triisocyanate, characterized in that, The preparation method includes: Step 1: Under an inert atmosphere, the hydroxyl-terminated prepolymer is mixed with excess isocyanate and catalyst to form a mixed system, and heated to 50-90 °C for 1-8 h for end-capping reaction to form an isocyanate-terminated hydroxyl prepolymer system. Step 2: Add a small molecule chain extender to the isocyanate-terminated hydroxyl prepolymer system, stir quickly and evenly, then coat it onto the substrate surface, and then transfer the substrate to an oven. The coating on the substrate surface undergoes a chain extension reaction at 60-120 °C for 12-144 h, and finally an anti-fouling coating is formed on the substrate surface. The hydroxyl-terminated prepolymer is a hydroxyl-terminated polysiloxane, or a mixture of hydroxyl-terminated polysiloxane and hydroxyl-terminated polyether, or a mixture of hydroxyl-terminated polysiloxane and hydroxyl-terminated polyester. The isocyanate is a mixture of toluene triisocyanate and diisocyanate, wherein the mass ratio of toluene triisocyanate to diisocyanate is 1:99 to 10:

90. The small molecule chain extender is a fluorinated diol, or a mixture of a fluorinated diol and an aliphatic diol. The catalyst is dibutyltin dilaurate or triphenylbismuth; The R value for the chain extension reaction is 0.9 to 1.

2.

2. The method for preparing a polyurethane antifouling coating based on toluene triisocyanate according to claim 1, characterized in that, The amount of catalyst added accounts for 0.001% to 0.1% of the mass fraction of the mixed system.

3. The method for preparing a polyurethane antifouling coating based on toluene triisocyanate according to claim 1, characterized in that, The mass ratio of the hydroxyl-terminated polysiloxane to the hydroxyl-terminated polyether is 100:0~20:80; The mass ratio of the hydroxyl-terminated polysiloxane to the hydroxyl-terminated polyester is 100:0~20:80; The mass ratio of the fluorinated diol to the aliphatic diol is 100:0 to 20:

80.

4. The method for preparing a polyurethane antifouling coating based on toluene triisocyanate according to claim 1 or 3, characterized in that, The hydroxyl-terminated polysiloxane is hydroxypropyl polysiloxane; The hydroxyl-terminated polyether is polytetrahydrofuran or tetrahydrofuran-ethylene oxide coether; The hydroxyl-terminated polyester is polycaprolactone.

5. The method for preparing a polyurethane antifouling coating based on toluene triisocyanate according to claim 1 or 3, characterized in that, The diisocyanate is toluene diisocyanate, hexamethylene diisocyanate, isoflurone diisocyanate, or dicyclohexylmethane diisocyanate.

6. The method for preparing a polyurethane antifouling coating based on toluene triisocyanate according to claim 1 or 3, characterized in that, The fluorinated diol is 2,2,3,3-tetrafluoro-1,4-butanediol, 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, or 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol. The aliphatic diol is ethylene glycol, 1,4-butanediol, 1,6-hexanediol, or diethylene glycol.

7. The method for preparing a polyurethane antifouling coating based on toluene triisocyanate according to claim 1, characterized in that, The coating process includes brushing, pouring, scraping, or spraying.

8. The method for preparing a polyurethane antifouling coating based on toluene triisocyanate according to claim 1, characterized in that, The substrate is an aluminum plate, stainless steel plate, cast iron plate, PP plate, or glass slide.

9. A polyurethane antifouling coating based on toluene triisocyanate obtained by the preparation method according to any one of claims 1-8.

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