Preparation method of green bio-based polyurethane wear-resistant anticorrosive paint

Abstract

The invention relates to a preparation method of a green bio-based polyurethane wear-resistant anticorrosive coating, and belongs to the technical field of high-performance coatings and renewable resource utilization. According to the coating, hydroxypropyl tea polyphenol (HTP) and castor oil polyol (COP) are used as main bio-based raw materials, hexamethylene diisocyanate (HMDI) is introduced to form a polyurethane skeleton, and aminated graphene oxide (NH2-GO) is compounded to enhance the mechanical property and corrosion resistance of a coating film. The method comprises the following steps: firstly preparing three key raw materials, namely HTP, COP and NH2-GO, then synthesizing a polyurethane prepolymer through a one-step prepolymerization method, carrying out synergistic reaction on the polyurethane prepolymer and NH2-GO, and finally regulating the viscosity of the coating by adding a flatting agent, an anti-ultraviolet aging agent and a solvent, thereby obtaining the finished coating. The obtained coating has excellent adhesive force, wear resistance, corrosion resistance and aging resistance, is suitable for the fields of metal corrosion prevention, marine ship coating, mechanical component surface protection and the like, and has remarkable environmental protection property and application and popularization value.

Description

Technical Field

[0001] The invention relates to a green bio-based polyurethane wear-resistant and anti-corrosion coating and a preparation method thereof, belonging to the technical field of functional polymer materials and coating materials. Background Art

[0002] As the requirements for material service life and environmental adaptability continue to increase in industrial equipment, transportation facilities, marine engineering and other fields, functional coatings with excellent wear resistance and corrosion resistance have become the focus of research and industry attention. Especially in complex service environments such as high humidity, high salt, wind and sand erosion, and mechanical friction, traditional coating materials have been unable to meet the long-term protection needs. In recent years, a large amount of research at home and abroad has been devoted to the development of wear-resistant and anti-corrosion composite coating systems, and relatively significant results have been achieved. However, most existing materials are still mainly petroleum-based synthetics, facing problems such as high resource consumption and insufficient environmental performance.

[0003] Polyurethane materials have become a type of polymer material widely used in wear-resistant and anti-corrosion coatings due to their excellent film-forming properties, flexibility, and adhesion. Polyurethane coatings can form dense structures on a variety of metal and non-metal surfaces, and have good barrier properties against corrosive media. At the same time, their good mechanical properties and wear resistance give them wide application potential in mechanical equipment housings, anti-corrosion primers, composite intermediate layers, etc. However, most traditional polyurethane systems are derived from petrochemical resources, and their molecular structure contains a high content of flexible segments, resulting in slightly inferior weather resistance, thermal stability, and chemical stability compared to epoxy coatings. In addition, in complex stress or long-term medium immersion environments, the coating is prone to blistering, peeling, aging, and other phenomena, which limits its service life in extreme environments.

[0004] Therefore, in order to further expand the application boundaries of polyurethane coatings, current research focuses on two aspects: first, the introduction of bio-based raw materials, such as castor oil, tea polyphenols, and natural polyphenol molecules, to replace some petrochemical raw materials and improve the green environmental protection performance and structural stability of the coating; second, the introduction of functional nanomaterials, such as graphene oxide, modified graphene, inorganic corrosion inhibitors, etc., to improve the wear resistance, corrosion resistance and aging stability of the coating. However, how to achieve effective synergy and uniform dispersion of bio-based structures and high-performance nanomaterials is still an important technical problem facing the current polyurethane wear-resistant and anti-corrosion coating system. Solving this problem is of great significance for the development of the next generation of polyurethane protective coatings that are both high-performance and green and sustainable. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a green bio-based polyurethane wear-resistant and anti-corrosion coating.

[0006] The purpose of the present invention is achieved through the following technical solutions: A method for preparing a green bio-based polyurethane wear-resistant and anti-corrosion coating, characterized by comprising the following components in parts by weight: Hydroxypropyl tea polyphenols (HTP) 20-40 parts; Castor oil polyol (COP) 25-50 parts; Hexamethylene diisocyanate (HMDI) 15-25 parts; Aminated graphene oxide (NH2–GO) 0.3–0.6 phr; Dibutyltin dilaurate (DBTDL) 0.2-0.5 parts; Leveling agent (BYK-306) 0.3-0.5 parts; 0.2-0.3 parts of anti-ultraviolet aging agent; 30-100 parts of ethyl acetate / DMF mixed solvent; The preparation method of the green bio-based polyurethane wear-resistant and anti-corrosion coating is as follows: (1) NH2–GO was ultrasonically dispersed in ethyl acetate to obtain NH2–GO dispersion; HTP was dissolved in DMF, HMDI was added, and the mixture was stirred at 90 °C for 3 h to obtain a polyurethane prepolymer; (2) The polyurethane prepolymer was added to the NH2–GO dispersion and magnetically stirred to fully mix the NH2–GO and the polyurethane prepolymer; DBTDL was added and reacted at 75 °C for 3 h, and then COP was added to the reaction solution and the reaction was continued for 6 h to obtain a bio-based polyurethane mixture; (3) Add a leveling agent and an anti-ultraviolet aging agent to the mixed solution in sequence, add an ethyl acetate / DMF mixed solvent (volume ratio of 1:1) to adjust the viscosity, and stir evenly to obtain a bio-based polyurethane coating.

[0007] As a preferred embodiment, the preparation method of hydroxypropyl tea polyphenol (HTP) is as follows: Tea polyphenols were dissolved in anhydrous ethanol, and NaOH was added. Under nitrogen protection, propylene oxide was added dropwise, and the reaction was carried out at 60°C for 6 hours. The pH was adjusted to neutral with dilute hydrochloric acid. The product was placed in a dialysis bag with a molecular weight cutoff of 1000 Da and dialyzed in deionized water for 48 hours. The sample was freeze-dried to obtain hydroxypropyl tea polyphenols (HTP).

[0008] As a preferred embodiment, the mass ratio of tea polyphenols to propylene oxide is (1-3): (2-6).

[0009] As a preferred embodiment, the preparation method of castor oil polyol (COP) is as follows: Castor oil and glacial acetic acid were added to a three-necked flask, and a 30% hydrogen peroxide solution was slowly added dropwise. Concentrated sulfuric acid was added as a catalyst. The mixture was stirred at 55°C for 3 h. After the reaction was completed, the excess acid was neutralized with a saturated NaHCO3 solution. The stratification was allowed to stand and the oil phase was repeatedly washed with distilled water until neutral. The water was removed by rotary evaporation to obtain epoxy castor oil. Epoxidized castor oil and ethylene glycol were added to a three-necked flask, and boron trifluoride ether (BF3·Et2O) was added. The mixture was reacted at 90°C under nitrogen for 5 h. After the reaction was completed, the residual acid was neutralized with a saturated NaHCO3 solution, extracted with ethyl acetate, and the organic solvent was removed by rotary evaporation. The mixture was then dried in vacuo to obtain castor oil polyol (COP).

[0010] As a preferred embodiment, the mass ratio of the epoxy castor oil to ethylene glycol is (2-5): (1-3).

[0011] As a preferred embodiment, the preparation method of the amino-modified graphene oxide (NH2-GO) is as follows: Graphene oxide (GO) was added to N, N-dimethylformamide (DMF) and ultrasonically dispersed to obtain a black GO dispersion. 1, 6-Hexanediamine (HDA) was slowly added dropwise to the dispersion and magnetically stirred for 6 h. After the reaction, the mixture was centrifuged, washed, and dried to obtain amino-modified graphene oxide (NH2–GO).

[0012] As a preferred embodiment, the mass ratio of GO to hexamethylenediamine is (1-2): (5-10).

[0013] As a preferred solution, the wear-resistant and anti-corrosion coating is used in the fields of metal anti-corrosion coatings, marine and ship coatings, mechanical equipment and wear-resistant component surfaces.

[0014] Basic principles of the present invention: (1) Hydroxypropyl tea polyphenols (HTP) and castor oil polyols (COP) are used as the main polyhydroxy components to react with hexamethylene diisocyanate (HMDI) to construct a bio-based polyurethane backbone with high cross-linking density, achieving an organic combination of green source raw materials and flexible structure.

[0015] (2) By introducing amino-modified graphene oxide (NH2–GO) with active amino groups on its surface, it is covalently grafted with the polyurethane chain segments to improve the dispersion stability and interfacial bonding strength of graphene in the composite material, thereby enhancing the mechanical properties of the coating and its ability to shield corrosive media.

[0016] (3) Introducing leveling agents and anti-UV aging additives into the coating to synergistically regulate the surface uniformity and weather resistance of the coating film, thereby improving its service stability and service life in outdoor or harsh environments.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses HTP and COP made from renewable resources as the polyurethane matrix, so that the resulting coating not only has good adhesion and wear resistance, but also significantly improves environmental protection and sustainability.

[0018] (2) NH2–GO is introduced into the coating to construct a nano-shielding network structure, which effectively blocks the diffusion of moisture and corrosive ions and significantly extends the protection life. After the salt spray resistance time exceeds 500 h, there is no blistering or rust on the surface.

[0019] (3) The prepared coating system has good fluidity and is suitable for various construction methods such as spraying, brushing or scraping. It can be cured at room temperature or low temperature and is suitable for various substrates such as metal, plastic, composite board, etc. It has good practicality and industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings: Figure 1 This is a flow chart for preparing the green bio-based polyurethane wear-resistant and anti-corrosion coating prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention. Example 1

[0022] This embodiment relates to a method for preparing a green bio-based polyurethane wear-resistant and anti-corrosion coating, which specifically includes the following steps: (1) Preparation of amino-modified graphene oxide (NH2–GO) 0.50 g of graphene oxide (GO) was weighed and added to 100 mL of N, N-dimethylformamide (DMF). Ultrasonic dispersion was performed to obtain a black GO dispersion. 2.00 g of 1, 6-hexanediamine (HDA) was slowly added dropwise to the dispersion and the mixture was stirred magnetically for 6 h. After the reaction, the mixture was centrifuged, washed, and dried to obtain amino-modified graphene oxide (NH2–GO).

[0023] (2) Preparation of Hydroxypropyl Tea Polyphenols (HTP) 5.00 g of tea polyphenols were dissolved in 100 mL of anhydrous ethanol, and 0.50 g of NaOH was added as a catalyst. Under nitrogen protection, 8.00 g of propylene oxide was slowly added dropwise. The reaction was carried out at 60 °C for 6 h. After the reaction, the pH was adjusted to neutral with dilute hydrochloric acid. The product was placed in a dialysis bag with a molecular weight cutoff of 1000 Da and dialyzed in deionized water for 48 h to remove small molecular impurities. The sample was freeze-dried to obtain hydroxypropyl tea polyphenols (HTP).

[0024] (3) Preparation of castor oil polyol (COP) 50 g of castor oil and 40 mL of glacial acetic acid were added to a three-necked flask, and 50 mL of 30% hydrogen peroxide solution was slowly added dropwise. 1 mL of concentrated sulfuric acid was added as a catalyst. The mixture was stirred at 55°C for 3 h. After the reaction was completed, the excess acid was neutralized with saturated NaHCO3 solution. The mixture was allowed to stand for stratification and the oil phase was repeatedly washed with distilled water until neutral. The water was removed by rotary evaporation to obtain epoxy castor oil. 40 g of epoxy castor oil and 30 g of ethylene glycol were added to a three-necked flask, and 0.5 g of boron trifluoride ether (BF3·Et2O) was added. The mixture was reacted at 90°C under nitrogen for 5 h. After the reaction was completed, the residual acid was neutralized with saturated NaHCO3 solution, extracted with ethyl acetate, and the organic solvent was removed by rotary evaporation. The mixture was then dried in vacuo to obtain castor oil polyol (COP).

[0025] Prepare the ingredients according to the following ratio: Hydroxypropyl Tea Polyphenols (HTP) 30 parts Castor Oil Polyol (COP) 25 parts Hexamethylene diisocyanate (HMDI) 20 parts Aminated graphene oxide (NH2–GO) 0.4 parts Dibutyltin dilaurate (DBTDL) 0.2 parts Leveling agent (BYK-306) 0.3 parts 0.2 parts of anti-UV aging agent 50 parts of ethyl acetate / DMF (volume ratio 1:1) mixed solvent 0.50% NH2–GO was ultrasonically dispersed in 80 mL of ethyl acetate to obtain an NH2–GO dispersion. HTP was dissolved in DMF, and hexamethylene diisocyanate (HMDI) was added. The mixture was stirred at 90°C for 3 h to obtain a polyurethane prepolymer. The polyurethane prepolymer was added to the NH2–GO dispersion and magnetically stirred to thoroughly mix the NH2–GO and polyurethane prepolymer. Dibutyltin dilaurate (DBTDL) was added, and the mixture was reacted at 75°C for 3 h. COP was then added to the reaction mixture, and the reaction was continued for 6 h to obtain a bio-based polyurethane mixture. A leveling agent (such as BYK-306) and an anti-UV aging agent were sequentially added to the mixture to adjust the final viscosity (mixed solvent can be added as appropriate). The mixture was stirred evenly to obtain a bio-based polyurethane coating.

[0026] The bio-based polyurethane coating prepared in Example 1 had adhesion test results that met the GB / T 9286 standard, with a cross-hatch grade of 0 to 1. Under the ASTM D4060 standard, the abrasion resistance tested by a Taber abrader showed a mass loss of 25 mg after 500 revolutions. According to the ASTM B117 neutral salt spray test standard, the coating exhibited salt spray corrosion resistance in a 5% NaCl solution for more than 500 h, with no obvious blistering, shedding, or rusting observed on the coating surface. Example 2

[0027] This embodiment relates to a method for preparing a green bio-based polyurethane wear-resistant and anti-corrosion coating, which specifically includes the following steps: (1) Preparation of amino-modified graphene oxide (NH2–GO) 0.60 g of graphene oxide (GO) was weighed and added to 100 mL of N, N-dimethylformamide (DMF). Ultrasonic dispersion was performed to obtain a black GO dispersion. 2.5 g of 1, 6-hexanediamine (HDA) was slowly added dropwise to the dispersion and the mixture was stirred magnetically for 6 h. After the reaction, the mixture was centrifuged, washed, and dried to obtain amino-modified graphene oxide (NH2–GO).

[0028] (2) Preparation of Hydroxypropyl Tea Polyphenols (HTP) 6.00 g of tea polyphenols were dissolved in 100 mL of anhydrous ethanol, and 0.50 g of NaOH was added as a catalyst. Under nitrogen protection, 9.00 g of propylene oxide was slowly added dropwise. The reaction was carried out at 60 °C for 6 h. After the reaction, the pH was adjusted to neutral with dilute hydrochloric acid. The product was placed in a dialysis bag with a molecular weight cutoff of 1000 Da and dialyzed in deionized water for 48 h to remove small molecular impurities. The sample was freeze-dried to obtain hydroxypropyl tea polyphenols (HTP).

[0029] (3) Preparation of castor oil polyol (COP) 45 g of castor oil and 40 mL of glacial acetic acid were added to a three-necked flask, and 50 mL of 30% hydrogen peroxide solution was slowly added dropwise. 1 mL of concentrated sulfuric acid was added as a catalyst. The mixture was stirred at 55°C for 3 h. After the reaction was completed, the excess acid was neutralized with saturated NaHCO3 solution. The mixture was allowed to stand for stratification and the oil phase was repeatedly washed with distilled water until neutral. The water was removed by rotary evaporation to obtain epoxy castor oil. 45 g of epoxy castor oil and 35 g of ethylene glycol were added to a three-necked flask, and 0.5 g of boron trifluoride ether (BF3·Et2O) was added. The mixture was reacted at 90°C under nitrogen for 5 h. After the reaction was completed, the residual acid was neutralized with saturated NaHCO3 solution, extracted with ethyl acetate, and the organic solvent was removed by rotary evaporation. The mixture was then dried in vacuo to obtain castor oil polyol (COP).

[0030] Prepare the ingredients according to the following ratio: Hydroxypropyl Tea Polyphenols (HTP) 35 parts Castor Oil Polyol (COP) 30 parts Hexamethylene diisocyanate (HMDI) 25 parts Aminated graphene oxide (NH2–GO) 0.3 parts Dibutyltin dilaurate (DBTDL) 0.25 parts Leveling agent (BYK-306) 0.35 parts 0.25 parts of anti-UV aging agent 60 parts of ethyl acetate / DMF (volume ratio 1:1) mixed solvent 0.50% NH2–GO was ultrasonically dispersed in 80 mL of ethyl acetate to obtain an NH2–GO dispersion. HTP was dissolved in DMF, and hexamethylene diisocyanate (HMDI) was added. The mixture was stirred at 90°C for 3 h to obtain a polyurethane prepolymer. The polyurethane prepolymer was added to the NH2–GO dispersion and magnetically stirred to thoroughly mix the NH2–GO and polyurethane prepolymer. Dibutyltin dilaurate (DBTDL) was added, and the mixture was reacted at 75°C for 3 h. COP was then added to the reaction mixture, and the reaction was continued for 6 h to obtain a bio-based polyurethane mixture. A leveling agent (such as BYK-306) and an anti-UV aging agent were sequentially added to the mixture to adjust the final viscosity (mixed solvent can be added as appropriate). The mixture was stirred evenly to obtain a bio-based polyurethane coating.

[0031] The bio-based polyurethane coating prepared in Example 2 had adhesion test results that met the GB / T 9286 standard, with a cross-hatch grade of 0 to 1. Under the ASTM D4060 standard, the abrasion resistance was tested by a Taber abrader, with a mass loss of 26 mg after 500 revolutions. According to the ASTM B117 neutral salt spray test standard, the coating exhibited salt spray corrosion resistance in a 5% NaCl solution for more than 500 h, with no obvious blistering, shedding, or rusting observed on the coating surface. Example 3

[0032] This embodiment relates to a method for preparing a green bio-based polyurethane wear-resistant and anti-corrosion coating, which specifically includes the following steps: (1) Preparation of amino-modified graphene oxide (NH2–GO) 0.50 g of graphene oxide (GO) was weighed and added to 100 mL of N, N-dimethylformamide (DMF). Ultrasonic dispersion was performed to obtain a black GO dispersion. 3.0 g of 1, 6-hexanediamine (HDA) was slowly added dropwise to the dispersion and the mixture was stirred magnetically for 6 h. After the reaction, the mixture was centrifuged, washed, and dried to obtain amino-modified graphene oxide (NH2–GO).

[0033] (2) Preparation of Hydroxypropyl Tea Polyphenols (HTP) 5.50 g of tea polyphenols were dissolved in 100 mL of anhydrous ethanol, and 0.50 g of NaOH was added as a catalyst. Under nitrogen protection, 9.50 g of propylene oxide was slowly added dropwise. The reaction was carried out at 60 °C for 6 h. After the reaction, the pH was adjusted to neutral with dilute hydrochloric acid. The product was placed in a dialysis bag with a molecular weight cutoff of 1000 Da and dialyzed in deionized water for 48 h to remove small molecular impurities. The sample was freeze-dried to obtain hydroxypropyl tea polyphenols (HTP).

[0034] (3) Preparation of castor oil polyol (COP) 50 g of castor oil and 40 mL of glacial acetic acid were added to a three-necked flask, and 50 mL of 30% hydrogen peroxide solution was slowly added dropwise. 1 mL of concentrated sulfuric acid was added as a catalyst. The mixture was stirred at 55°C for 3 h. After the reaction was completed, the excess acid was neutralized with saturated NaHCO3 solution. The mixture was allowed to stand for stratification and the oil phase was repeatedly washed with distilled water until neutral. The water was removed by rotary evaporation to obtain epoxy castor oil. 50 g of epoxy castor oil and 40 g of ethylene glycol were added to a three-necked flask, and 0.5 g of boron trifluoride ether (BF3·Et2O) was added. The mixture was reacted at 90°C under nitrogen for 5 h. After the reaction was completed, the residual acid was neutralized with saturated NaHCO3 solution, extracted with ethyl acetate, and the organic solvent was removed by rotary evaporation. The mixture was then dried in vacuo to obtain castor oil polyol (COP).

[0035] Prepare the ingredients according to the following ratio: Hydroxypropyl Tea Polyphenols (HTP) 40 parts Castor Oil Polyol (COP) 40 parts Hexamethylene diisocyanate (HMDI) 20 parts Aminated graphene oxide (NH2–GO) 0.4 parts Dibutyltin dilaurate (DBTDL) 0.3 parts Leveling agent (BYK-306) 0.3 parts 0.3 parts of anti-UV aging agent 70 parts of ethyl acetate / DMF (volume ratio 1:1) mixed solvent 0.50% NH2–GO was ultrasonically dispersed in 80 mL of ethyl acetate to obtain an NH2–GO dispersion. HTP was dissolved in DMF, and hexamethylene diisocyanate (HMDI) was added. The mixture was stirred at 90°C for 3 h to obtain a polyurethane prepolymer. The polyurethane prepolymer was added to the NH2–GO dispersion and magnetically stirred to thoroughly mix the NH2–GO and polyurethane prepolymer. Dibutyltin dilaurate (DBTDL) was added, and the mixture was reacted at 75°C for 3 h. COP was then added to the reaction mixture, and the reaction was continued for 6 h to obtain a bio-based polyurethane mixture. A leveling agent (such as BYK-306) and an anti-UV aging agent were sequentially added to the mixture to adjust the final viscosity (mixed solvent can be added as appropriate). The mixture was stirred evenly to obtain a bio-based polyurethane coating.

[0036] The bio-based polyurethane coating prepared in Example 3 had adhesion test results that met the GB / T 9286 standard, with a cross-cut grade of 0 to 1. Under the ASTM D4060 standard, the abrasion resistance tested by the Taber abrader showed a mass loss of 25 mg after 500 revolutions. According to the ASTM B117 neutral salt spray test standard, the coating exhibited salt spray corrosion resistance in a 5% NaCl solution for more than 500 h, with no obvious blistering, shedding, or rusting observed on the coating surface. Comparative Example 1

[0037] The difference from Example 1 is that the amount of amino-modified graphene oxide added during the preparation method was zero, resulting in a bio-based polyurethane coating. Adhesion test results met the GB / T 9286 standard, with a cross-hatch grade of 1-2. Abrasion resistance tested using a Taber abraser under ASTM D4060 showed a mass loss of 30 mg after 500 revolutions. Furthermore, according to the ASTM B117 neutral salt spray test standard, the coating demonstrated salt spray corrosion resistance in a 5% NaCl solution for over 500 hours, with no apparent blistering, shedding, or rusting observed on the coating surface. Comparative Example 2

[0038] The difference from Example 1 lies in that "tea polyphenols" was used instead of "hydroxypropyl tea polyphenols" in the preparation method, resulting in a bio-based polyurethane coating. Adhesion test results met the GB / T 9286 standard, with a cross-cut grade of 1-2. Abrasion resistance tested using a Taber abrader under ASTM D4060 showed a mass loss of 31 mg after 500 revolutions. According to the ASTM B117 neutral salt spray test standard, the coating demonstrated salt spray corrosion resistance in a 5% NaCl solution for over 500 hours, with no apparent blistering, shedding, or rusting observed on the coating surface.

[0039] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a green bio-based polyurethane wear-resistant and anti-corrosion coating, characterized in that: It comprises the following components in parts by weight: Hydroxypropyl tea polyphenol HTP 20-40 parts; Castor oil polyol COP 25-50 parts; 15-25 parts of hexamethylene diisocyanate HMDI; Amination-modified graphene oxide NH2–GO 0.3–0.6 parts; Dibutyltin dilaurate DBTDL 0.2-0.5 parts; Leveling agent BYK-306 0.3-0.5 parts; 0.2-0.3 parts of anti-ultraviolet aging agent; 30-100 parts of ethyl acetate / DMF mixed solvent; The preparation method of the green bio-based polyurethane wear-resistant and anti-corrosion coating is as follows: (1) NH2–GO was ultrasonically dispersed in ethyl acetate to obtain NH2–GO dispersion; HTP was dissolved in DMF, HMDI was added, and the mixture was stirred at 90 °C for 3 h to obtain a polyurethane prepolymer; (2) The polyurethane prepolymer was added to the NH2–GO dispersion, and the NH2–GO and the polyurethane prepolymer were fully mixed by magnetic stirring. DBTDL was added and the reaction was carried out at 75 °C for 3 h. COP was then added to the reaction solution and the reaction was continued for 6 h to obtain a bio-based polyurethane mixture. (3) Adding a leveling agent and an anti-ultraviolet aging agent to the mixed solution in sequence, adding an ethyl acetate / DMF mixed solvent with a volume ratio of 1:1 to adjust the viscosity, and stirring evenly to obtain a bio-based polyurethane coating; The preparation method of the hydroxypropyl tea polyphenol HTP is as follows: Tea polyphenols were dissolved in anhydrous ethanol, and NaOH was added. Under nitrogen protection, propylene oxide was added dropwise, and the reaction was carried out at 60°C for 6 hours. The pH was adjusted to neutral with dilute hydrochloric acid. The product was placed in a dialysis bag with a molecular weight cutoff of 1000 Da and dialyzed in deionized water for 48 hours. The sample was freeze-dried to obtain hydroxypropyl tea polyphenol HTP. The mass ratio of the tea polyphenols to propylene oxide is (1-3): (2-6); The preparation method of the castor oil polyol COP is as follows: Castor oil and glacial acetic acid were added to a three-necked flask, and a 30% hydrogen peroxide solution was slowly added dropwise. Concentrated sulfuric acid was added as a catalyst. The mixture was stirred at 55°C for 3 h. After the reaction was completed, the excess acid was neutralized with a saturated NaHCO3 solution. The mixture was allowed to stand for stratification and the oil phase was repeatedly washed with distilled water until neutral. The water was removed by rotary evaporation to obtain epoxy castor oil. Epoxidized castor oil and ethylene glycol were added to a three-necked flask, and boron trifluoride ether (BF3·Et2O) was added. The mixture was reacted at 90°C under nitrogen for 5 h. After the reaction was completed, the residual acid was neutralized with a saturated NaHCO3 solution, extracted with ethyl acetate, and the organic solvent was removed by rotary evaporation. The mixture was then dried in vacuo to obtain castor oil polyol (COP). The mass ratio of the epoxy castor oil to ethylene glycol is (2-5): (1-3); The preparation method of the amino-modified graphene oxide NH2-GO is as follows: Graphene oxide (GO) was added to DMF and ultrasonically dispersed to obtain a black GO dispersion. 1,6-hexanediamine (HDA) was slowly added dropwise to the dispersion and stirred magnetically for 6 h. After the reaction, the mixture was centrifuged, washed, and dried to obtain amino-modified graphene oxide (NH2–GO). The mass ratio of GO to hexamethylenediamine is (1-2): (5-10).

2. The method for preparing a green bio-based polyurethane wear-resistant and anti-corrosion coating according to claim 1, characterized in that: The wear-resistant and anti-corrosion coating is used in the fields of metal anti-corrosion coating, marine and ship coating, mechanical equipment and wear-resistant component surfaces.

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