Dihydroxy anthraquinone-based copolyester and application of corrosion-resistant and wear-resistant coating

Abstract

The invention discloses a preparation method and application of novel copolyester, and belongs to the field of polymer composite coatings. The copolyester synthesized by the invention has good corrosion resistance, can be used for preparing a corrosion-resistant and wear-resistant polymer composite coating, can be used for protecting a ship body and preventing the corrosion of saline water and marine organisms, and can also be used for protecting offshore wind power equipment and other equipment and preventing the corrosion caused by seawater and tides; and the paint can also be used for corrosion prevention of mechanical equipment and parts in a highly corrosive working environment.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite coatings, specifically relating to the preparation and use of corrosion-resistant and wear-resistant polymer composite coatings. A copolyester based on 2,6-dihydroxyanthraquinone is synthesized by melt polymerization, which can be used to prepare corrosion-resistant and mechanically wear-resistant polymer composite coatings. Background Technology

[0002] Faced with the severe challenges of the intertwined global energy, resources and environment, the traditional petroleum-based polymer industry is under multiple pressures. Utilizing renewable resources to synthesize polymers provides a feasible solution to address the depletion of fossil fuels and increasingly serious environmental problems.

[0003] With the continuous development and utilization of marine resources by human beings, equipment working in the ocean faces a variety of corrosion challenges. Salt spray, humidity and corrosive media in the marine environment can trigger chemical reactions on the metal surface, resulting in severe corrosion of metal materials. In addition, waves, particles and marine organisms in the ocean can cause wear and fatigue damage to the surface of equipment ([1] Liu P, Zhang H, Fan Y, Xu D. Microbially influenced corrosion of steel in marine environments: a review from mechanisms to prevention. Microorganisms 2023; 11:2299). The salt and moisture in the ocean accelerate the damage of materials and the corrosion of metals, reduce the strength and durability of materials, and thus increase the risk of accidents. To address these issues, anti-corrosion and wear-resistant coatings are considered a promising type of coating due to their simple preparation process, strong adhesion, and high durability. Coatings can effectively protect the substrate from corrosion, extend its service life, reduce maintenance costs, and decrease the frequency of repairs and replacements, thereby saving money and resources ([2] Wood RJK, Lu P. Coatings and surface modification of alloys for tribo-corrosion applications. Coatings 2024; 14:99.). Therefore, anti-corrosion and wear-resistant coatings are crucial in marine engineering, marine vessels, and marine equipment.

[0004] Due to the strong corrosiveness of seawater and the significant differences in temperature, salinity, and marine organisms in different sea areas, high requirements are placed on the coating's resistance to salt spray, seawater immersion, and biofouling. Currently, existing composite coatings exhibit certain limitations in these aspects. For example, the h-BN / PVA coating reported in ([3]Wu Y,Wu Y,Sun Y,et al.2D NanomaterialsReinforced Organic Coatings for Marine Corrosion Protection:State of the Art,Challenges,and Future Prospectives[J].Advanced Materials,2024:2312460-2312491.) showed a corrosion rate of 1.19×10⁻⁶ after immersion in 3.5wt% NaCl solution for 30 days. -3 mm / year, with poor corrosion resistance. Furthermore, these coatings are ill-suited to all marine environments and are prone to localized failure.

[0005] Meanwhile, ships are subjected to mechanical forces such as wave impact, hull deformation, and cargo friction during navigation, which places high demands on the toughness and wear resistance of the coating. Existing coatings also have shortcomings in this regard. For example, the Ni-Cr oxide nanocomposite coating reported in ([4] Mohammadzadeh H, Jafari R, Azargoon A. Mechanical, morphological, and corrosion features of Ni–Cr oxide nanocomposite coating deposited on SS304 by EPD[J]. International Journal of Applied Ceramic Technology, 2024, 35(38): 5231-5269.) still needs to be improved in terms of mechanical properties. The coefficient of friction is 0.76, the hardness is 180.3Hv, and it is prone to cracking and peeling, which affects its service life. This shows that current coatings still face significant technical challenges in meeting the harsh requirements of the marine environment.

[0006] Currently, the most common method to deal with metal corrosion in the ocean is to coat the metal surface with a coating. The most common coating types include anodizing, zinc plating, electroplating, and paint coating ([5] Bhat SI, Mobin M, Islam S, et al. Recent advances in anticorrosive coatings based on sustainable polymers: Challenges and perspectives[J]. Surface and Coatings Technology, 2024, 480.). These coatings provide metals with high corrosion resistance.

[0007] Compared to land, offshore wind power equipment is located in a more complex environment. Offshore wind power has advantages such as small footprint, high power density, high wind speed, low turbulence, stable wind direction, high development rate, close proximity to load center, high conversion rate and zero dust emission. In the implementation of offshore wind power projects, wind turbine equipment needs to be assembled and installed by bolts, which has become a hot area of ​​wind power development. Compared with onshore wind power, offshore wind power requires higher R&D costs, and the anti-corrosion technology of wind power equipment has become an urgent task ([6] Duan Xinsheng, Mai Nannan, Sun Xiaobo, et al. Anti-corrosion spraying process and coating performance analysis of offshore wind power bearings [J]. Bearings, 2023, 15(06): 84-88.).

[0008] Meanwhile, these harsh environments have caused severe corrosion of outdoor GIS (Gas-insulated sunstation) in coastal substations. A survey of the corrosion of outdoor GIS in Fujian Province found that 122 outdoor GIS were involved in corrosion, mainly manifested as shell corrosion in 68 units, flange corrosion in 31 units, and transmission connecting rod corrosion in 23 units ([7] Xia Xiaojian, Cai Jianbin, Lin Deyuan, et al. Corrosion status of equipment in coastal substations and its corrosion mechanism and protection [J]. Journal of Corrosion and Protection, 2021, 41(05): 697-704.).

[0009] Therefore, corrosion prevention is a crucial issue that must be considered for offshore equipment. Developing corrosion-resistant coatings to protect ship hulls and offshore wind power infrastructure, and to prevent corrosion caused by seawater and tides, is of great significance.

[0010] In addition, highly corrosive working environments, such as those in the chemical, metallurgical, water treatment, and environmental protection industries, often involve harsh conditions with high levels of acid mist and strong corrosiveness. This makes the electromechanical equipment and components in such environments susceptible to corrosion, and they are often protected by spraying high-performance anti-corrosion coatings on the equipment surface. Summary of the Invention

[0011] To address these issues, this invention uses 2,6-dihydroxyanthraquinone as a raw material, and prepares monomer M through further reaction. Then, it is melt-polymerized into a copolyester. The copolyester synthesized in this invention exhibits better mechanical properties compared to existing polyesters. After the synthesized copolyester solution is thoroughly mixed with rutile titanium dioxide and E-12 (604) epoxy resin, a polymeric composite coating with copolyester P as the key component and good corrosion resistance and mechanical wear resistance is obtained. The copolyester melamine-formaldehyde resin exhibits excellent resistance to acid, alkali, and seawater corrosion, while the rutile titanium dioxide has antibacterial and deodorizing effects and a certain degree of hardness, enhancing the corrosion and wear resistance of the polymeric coating. The resulting polymeric composite coating possesses good impact resistance and corrosion resistance. To achieve the objectives of this invention, the following technical solution is adopted:

[0012] To better realize the technical solution of the present invention, the present invention discloses the preparation and use of a polymeric composite coating based on 2,6-dihydroxyanthraquinone copolyester that is corrosion-resistant and mechanically wear-resistant.

[0013] The preparation method of this corrosion-resistant and mechanically wear-resistant polymer composite coating includes the following steps:

[0014] 1. A coating for corrosion resistance and wear resistance based on copolyester P as the main component, characterized in that the coating is prepared by: firstly, preparing a mixed solvent of ethyl acetate and dichloromethane in a mass ratio of 1:2; then preparing a saturated solution of copolyester P and the above mixed solvent at room temperature; mixing the above saturated solution with 30nm rutile titanium dioxide and E-12 (604) epoxy resin in a mass ratio of 70:(5~10):(20~25); finally heating and stirring at 80°C for 1 hour in a sealed container to obtain the desired viscous coating. Its application is as follows: using a spray gun, the coating is uniformly sprayed onto the surface requiring protection. After the solvent evaporates, a 10~30μm corrosion-resistant and wear-resistant coating is formed. The key component of the coating is a copolyester P based on 2,6-dihydroxyanthraquinone, the structure of which is shown in Formula I.

[0015]

[0016] In the above structural formula, m is 61-73 and n is 46-55.

[0017] 2. Preparation and application of a corrosion-resistant and wear-resistant coating based on copolyester P as the main component, characterized in that the preparation of copolyester P based on 2,6-dihydroxyanthraquinone includes the following steps:

[0018] 1) Synthesis of monomer M: 2,6-dihydroxyanthraquinone, potassium carbonate, and methyl chloroacetate were added to a closed reactor in a molar ratio of 1:0.50–0.60:2–2.05. Dimethyl sulfoxide was added to dissolve the mixture, and the reaction mixture was heated to 100°C and stirred continuously for 2–3 hours. After the reaction was completed, the mixture was cooled to room temperature, and then 0.10 mol / L sodium hydroxide solution was slowly added under stirring until no more precipitate formed. The mixture was then filtered, and the filter cake was washed with distilled water until neutral. The solid product was dried in an oven at 60°C for 1–2 hours to obtain monomer M of structural formula I.

[0019]

[0020] 2) Synthesis of copolyester P: Using the synthesized monomer M, the diol 2,5-furandiethanol (CAS No. 1883-75-6), and the diacid 2,2'-bipyridine-4,4'-dicarboxylic acid (CAS No. 610-92-4) as the three monomer raw materials, a suitable catalyst was added and nitrogen gas was introduced for protection. The temperature was controlled at 160-190℃ and the reaction was stirred for 2-4 hours. Then, a polycondensation reaction was carried out at a pressure of 5-10 kPa and a temperature of 210-240℃ for 2-3 hours to obtain the structure shown in Formula I, with a molecular weight of 5*10. 4 ~7*10 4 Copolyester P in the range of g / mol.

[0021] 3. Preparation and application of a corrosion-resistant and mechanically abrasion-resistant coating based on copolyester as the main component, characterized in that the molar ratio of monomer M, 2,2'-bipyridine-4,4'-dicarboxylic acid, and 2,5-furandimethyl alcohol in the preparation step of a copolyester P based on 2,6-dihydroxyanthraquinone is (1.0-1.10):

[0022] (0.90~1.0):2.00.

[0023] 4. Preparation and use of a corrosion-resistant and mechanically wear-resistant coating based on copolyester as the main component, characterized in that the catalyst used in the preparation of the copolyester P based on 2,6-dihydroxyanthraquinone is one of titanium acetylacetone oxide, titanium tetraisopropoxide, and dibutyldiphenyltin, and the amount of the catalyst is 0.1% to 0.5% of the mass of the reactant monomer M.

[0024] Beneficial effects

[0025] 1. Traditional inorganic coatings usually contain heavy metals, while the copolyester coating raw materials synthesized in this invention are mainly derived from organic compounds, which can be obtained from biomass or renewable resources, making them relatively more environmentally friendly.

[0026] 2. The copolyester synthesized in this invention uses 2,6-dihydroxyanthraquinone and 2,5-furandimethylethanol. The three rings of anthraquinone can increase the rigidity of the molecular chain and reduce its degree of freedom. Moreover, this macrocyclic structure can enhance the strength and durability of the copolyester. At the same time, the furan ring structure of 2,5-furandimethylethanol has high rigidity, which can improve the mechanical properties and wear resistance of the copolyester.

[0027] 3. In the preparation of copolyester coatings, E-12 (604) epoxy resin was added. Epoxy resin has good chemical resistance, especially resistance to acids, alkalis and solvents. Adding it to copolyester coatings can significantly improve the corrosion resistance of the coating and prevent the coating from being corroded in harsh chemical environments. ([3] Wu Y, Wu Y, Sun Y, et al. 2D Nanomaterials Reinforced Organic Coatings for Marine Corrosion Protection: State of the Art, Challenges, and Future Prospectives[J].

[0028] The corrosion rate of the composite coating h-BN / PVA reported in Advanced Materials (2024) is 1.19 × 10⁻⁶. -3 The corrosion rate of the coatings and coatings prepared by this invention is 0.95 × 10 mm / year. -6 The corrosion resistance is approximately mm / year. In comparison, the corrosion-resistant and wear-resistant polymer composite coating prepared by this invention exhibits significantly improved corrosion resistance.

[0029] 4. Mohammadzadeh H et al ([4] Mohammadzadeh H, Jafari R, Azargoon A.

[0030] The mechanical, morphological, and corrosion features of Ni–Cr oxide nanocomposite coating deposited on SS304 by EPD[J]. International Journal of Applied Ceramic Technology, 2024, 35(38): 5231-5269.) reported that the Ni-Cr oxide nanocomposite coating still needs improvement in terms of mechanical properties, with a friction coefficient of 0.76 and a hardness of 180.3 Hv. The corrosion-resistant and mechanically wear-resistant polymeric composite coating based on 2,6-dihydroxyanthraquinone prepared in this invention has a hardness of 203.8 Hv and a friction coefficient of 0.31. In comparison, the corrosion-resistant and wear-resistant polymeric composite coating prepared in this invention exhibits significantly enhanced hardness and better wear resistance. Detailed Implementation

[0031] The present invention will be further illustrated by the following embodiments, but the present invention is not limited to the embodiments. All raw materials used in the present invention are commercially available.

[0032] To determine the properties of the copolyester prepared in this embodiment,

[0033] Molecular weight: determined using a Waters 2412 gel permeation chromatograph with tetrahydrofuran as the mobile phase;

[0034] Mechanical property tests in the examples: tensile tests on the sample test strips were conducted according to the requirements of GB / T1040.2-2006, with a tensile rate of 20 mm / min; elongation at break tests were conducted according to the requirements of GB / T1040.3-2006; hardness tests were conducted according to the requirements of GB / T 6739-2022; adhesion tests were conducted according to the requirements of GB / T 1720-2020; and coefficient of friction tests were conducted according to the requirements of GB / T 9757-2017.

[0035] Melting point test in the example: DSC test was conducted using a TA Q2000 instrument. The test method was as follows: under a nitrogen atmosphere, the temperature was increased from 30°C to 300°C at a rate of 10°C / min, maintained at 300°C for 10 min, then decreased to 30°C at a rate of 10°C / min, and then increased to 300°C again at the same rate.

[0036] The result is the average of 5 test samples.

[0037] Yield = 100% × Actual amount of target product produced / Theoretical amount of target product produced.

[0038] In this example, the coating corrosion current density was tested according to GB / T 19292.2-2018; the corrosion resistance test was conducted according to GB / T10125-2021, using a normal neutral salt spray test with a 50 g / L NaCl solution. The pH of the salt water was between 6.5 and 7.2. Continuous spraying was carried out at a test temperature of 25±2℃, and the surface condition of the coating was observed periodically. The corrosion resistance was measured by the weight change after 48 hours of testing. The corrosion rate was calculated according to the following formula:

[0039]

[0040] Example 1: Synthesis of monomer M: 12.011 g (0.05 mol) of 2,6-dihydroxyanthraquinone and 3.455 g (0.025 mol) of potassium carbonate were added to a reactor. An appropriate amount of dimethyl sulfoxide was added to ensure complete dissolution. Then, 10.852 g (0.1 mol) of methyl chloroacetate was added dropwise. The reaction mixture was heated to 100 °C and stirred continuously for 2.5 hours. After the reaction was completed, it was cooled to room temperature. Then, 0.5 mol / L sodium hydroxide solution was slowly added under stirring until no more precipitate was formed. The mixture was then filtered, and the filter cake was washed three times with distilled water. Finally, it was dried in an oven at 60 °C for 1.5 hours to obtain monomer M: 14.47 g, with a yield of 81.24%.

[0041] Example 2: 3.843 g (0.01 mol) of monomer M, 2.563 g (0.02 mol) of 2,5-furandiethanol and 2.442 g (0.01 mol) of 2,2'-bipyridine-4,4'-dicarboxylic acid were added to a 50 ml single-necked flask. 0.006 g of tetraisopropoxide titanium was added, and nitrogen gas was introduced for protection. The reaction was carried out at 160 °C for 3 hours. Then, a polycondensation reaction was carried out at 220 °C for 2.5 hours under a pressure of 8 kPa to obtain copolyester P1: 7.11 g, with a yield of 85.62%. The test results of copolyester P1 are shown in Table 1.

[0042] Preparation of coating: First, a mixed solvent of ethyl acetate and dichloromethane with a mass ratio of 1:2 is prepared; then, copolyester P1 and the above mixed solvent are used to prepare a saturated solution at room temperature; the above saturated solution is mixed with 30nm rutile titanium dioxide and E-12 (604) epoxy resin at a mass ratio of 70:5:25, and heated and stirred at 80°C for 1 hour in a sealed container to obtain the required viscous coating. The coating is then evenly sprayed onto the surface of the substrate to be protected using a spray gun. After the solvent evaporates, a 25μm corrosion-resistant and wear-resistant coating T1 is formed.

[0043] The coating has a hardness of 199.5 Hv, a coefficient of friction of 0.39, and an adhesion of 8.34 MPa. After immersion in a 3.5 wt% NaCl solution for 30 days, its corrosion rate is 1.76 × 10⁻⁶. -4 mm / year, with high corrosion resistance, a significant improvement over existing coatings; can provide effective protection under various environmental conditions.

[0044] Equipment operating in the ocean, such as ocean-going cargo ships, faces severe environmental challenges. High humidity, high salt spray, alternating wet and dry conditions, seawater immersion, and biological adhesion increase the cost of ship operation and maintenance.

[0045] The corrosion-resistant coating T1 developed in this embodiment can be used to protect the hull from corrosion caused by seawater and other environmental factors, and has an important protective function.

[0046] Example 3: 3.843 g (0.01 mol) of monomer M, 2.563 g (0.02 mol) of 2,5-furandiethanol and 2.442 g (0.01 mol) of 2,2'-bipyridine-4,4'-dicarboxylic acid were added to a 50 ml single-necked flask. 0.006 g of titanium dioxide acetylacetone was added, and nitrogen gas was introduced for protection. The reaction was carried out at 165 °C for 3 hours. Then, a polycondensation reaction was carried out at 210 °C for 2.5 hours under a pressure of 6 kPa to obtain copolyester P2: 7.18 g, with a yield of 86.45%. The test results of copolyester P2 are shown in Table 1.

[0047] Preparation of coating: First, a mixed solvent of ethyl acetate and dichloromethane with a mass ratio of 1:2 is prepared; then, copolyester P2 and the above mixed solvent are used to make a saturated solution at room temperature; the above saturated solution is mixed with 30nm rutile titanium dioxide and E-12 (604) epoxy resin at a mass ratio of 70:6:24, and heated and stirred at 80°C for 1 hour in a sealed container to obtain the required viscous coating. The coating is then evenly sprayed onto the surface of the substrate to be protected using a spray gun. After the solvent evaporates, a 22μm corrosion-resistant and wear-resistant coating T2 is formed.

[0048] The coating has a hardness of 200.2 Hv, a coefficient of friction of 0.37, and an adhesion of 8.46 MPa. After immersion in a 3.5 wt% NaCl solution for 30 days, its corrosion rate is 1.10 × 10⁻⁶. -4 mm / year, with high corrosion resistance, a significant improvement over existing coatings; can provide effective protection under various environmental conditions.

[0049] Wind power equipment operating in the ocean faces severe environmental challenges, including high humidity, high salt spray, alternating wet and dry conditions, seawater immersion, and biological adhesion. These harsh conditions significantly shorten the operational life of offshore wind turbines and increase the construction investment and operation and maintenance costs of the equipment.

[0050] The corrosion-resistant and wear-resistant coating T2 developed in this embodiment is used to protect offshore wind power equipment and facilities, preventing corrosion caused by seawater and tides, and plays an important protective role.

[0051] Example 4: 3.843 g (0.01 mol) of monomer M, 2.563 g (0.02 mol) of 2,5-furandiethanol and 2.442 g (0.01 mol) of 2,2'-bipyridine-4,4'-dicarboxylic acid were added to a 50 ml single-necked flask. 0.006 g of dibutyldiphenyltin was added, and nitrogen gas was introduced for protection. The temperature was controlled at 170 °C for 3 hours. Then, a polycondensation reaction was carried out at a pressure of 8 kPa and a temperature of 230 °C for 2.5 hours to obtain copolyester P3: 7.33 g, with a yield of 88.26%. The test results of copolyester P3 are shown in Table 1.

[0052] Preparation of coating: First, a mixed solvent of ethyl acetate and dichloromethane with a mass ratio of 1:2 is prepared; then, copolyester P3 and the above mixed solvent are used to make a saturated solution at room temperature; the above saturated solution is mixed with 30nm rutile titanium dioxide and E-12 (604) epoxy resin at a mass ratio of 70:7:23, and heated and stirred at 80°C for 1 hour in a sealed container to obtain the required viscous coating. The coating is then evenly sprayed onto the surface of the substrate to be protected using a spray gun. After the solvent evaporates, a 20μm corrosion-resistant and wear-resistant coating T3 is formed.

[0053] The coating has a hardness of 202.6 Hv, a coefficient of friction of 0.35, and an adhesion of 8.47 MPa. After immersion in a 3.5 wt% NaCl solution for 30 days, its corrosion rate is 0.95 × 10⁻⁶. -4 mm / year, with high corrosion resistance, a significant improvement over existing coatings; can provide effective protection under various environmental conditions.

[0054] Equipment operating in the ocean, such as offshore platforms, faces severe environmental challenges. High humidity, high salt spray, alternating wet and dry conditions, seawater immersion, and biological adhesion increase the construction investment and operation and maintenance costs of offshore platform equipment.

[0055] The corrosion-resistant and wear-resistant coating T3 developed in this embodiment is used to protect offshore operating platforms and other facilities, preventing corrosion caused by seawater and tides, and plays an important protective role.

[0056] Example 5: 4.228 g (0.011 mol) of monomer M, 2.819 g (0.022 mol) of 2,5-furandiethanol and 2.198 g (0.009 mol) of 2,2'-bipyridine-4,4'-dicarboxylic acid were added to a 50 ml single-necked flask. 0.016 g of tetraisopropoxide titanium was added, and nitrogen gas was introduced for protection. The reaction was carried out at 175 °C for 3 hours. Then, a polycondensation reaction was carried out at 7 kPa and 240 °C for 2.5 hours to obtain copolyester P4: 6.48 g, with a yield of 86.73%. The test results of copolyester P4 are shown in Table 1.

[0057] Preparation of coating: First, a mixed solvent of ethyl acetate and dichloromethane with a mass ratio of 1:2 is prepared; then, copolyester P4 and the above mixed solvent are used to prepare a saturated solution at room temperature; the above saturated solution is mixed with 30nm rutile titanium dioxide and E-12 (604) epoxy resin at a mass ratio of 70:8:22, and heated and stirred at 80°C for 1 hour in a sealed container to obtain the required viscous coating. The coating is then evenly sprayed onto the surface of the substrate to be protected using a spray gun. After the solvent evaporates, an 18μm corrosion-resistant and wear-resistant coating T4 is formed.

[0058] The coating has a hardness of 199.3 Hv, a coefficient of friction of 0.37, and an adhesion of 8.38 MPa. After immersion in a 3.5 wt% NaCl solution for 30 days, its corrosion rate is 1.27 × 10⁻⁶. -4 mm / year, with high corrosion resistance, a significant improvement over existing coatings; can provide effective protection under various environmental conditions.

[0059] The working environment of equipment in the chemical industry is often harsh, with large amounts of acid mist and strong corrosiveness, resulting in high operating and maintenance costs for related machinery, equipment, pipelines and components.

[0060] The corrosion-resistant and wear-resistant coating T4 developed in this embodiment is used to protect the machinery, pipelines and mechanical parts of enterprises producing sulfuric acid, phosphoric acid, nitric acid and hydrochloric acid, as well as ammonia and liquid ammonia and liquid alkali chemical enterprises in harsh working environments with large amounts of acid mist and strong corrosiveness, from corrosion of metal equipment by acidic or alkaline corrosive media, and plays an important protective role.

[0061] Example 6: 4.228 g (0.011 mol) of monomer M, 2.819 g (0.022 mol) of 2,5-furandiethanol and 2.198 g (0.009 mol) of 2,2'-bipyridine-4,4'-dicarboxylic acid were added to a 50 ml single-necked flask. 0.016 g of titanium dioxide acetylacetone was added, and nitrogen gas was introduced for protection. The reaction was carried out at 180 °C for 3 hours. Then, a polycondensation reaction was carried out at 220 °C for 2.5 hours under a pressure of 9 kPa to obtain copolyester P5: 6.56 g, with a yield of 87.68%. The test results of copolyester P5 are shown in Table 1.

[0062] Preparation of coating: First, a mixed solvent of ethyl acetate and dichloromethane with a mass ratio of 1:2 is prepared; then, copolyester P5 and the above mixed solvent are used to make a saturated solution at room temperature; the above saturated solution is mixed with 30nm rutile titanium dioxide and E-12 (604) epoxy resin at a mass ratio of 70:9:21, and heated and stirred at 80°C for 1 hour in a sealed container to obtain the required viscous coating. The coating is then evenly sprayed onto the surface of the substrate to be protected using a spray gun. After the solvent evaporates, a 20μm corrosion-resistant and wear-resistant coating T5 is formed.

[0063] The coating has a hardness of 200.4 Hv, a coefficient of friction of 0.36, and an adhesion of 8.45 MPa. After immersion in a 3.5 wt% NaCl solution for 30 days, its corrosion rate is 1.24 × 10⁻⁶. -4 mm / year, with high corrosion resistance, a significant improvement over existing coatings; can provide effective protection under various environmental conditions.

[0064] In humid and heavily polluted urban environments, steel structure buildings are susceptible to corrosion and damage from atmospheric moisture and pollutants. This corrosion not only affects the building's aesthetics but may also weaken its strength, increase safety hazards, shorten its lifespan, and consequently increase maintenance and replacement costs.

[0065] The corrosion-resistant and wear-resistant coating T5 developed in this embodiment is used to effectively protect steel structure buildings, prevent atmospheric corrosion, maintain the building's aesthetics and structural strength, and extend the building's service life, thus playing an important protective role.

[0066] Example 7: 4.228 g (0.011 mol) of monomer M, 2.819 g (0.022 mol) of 2,5-furandimethylethanol, and 2.198 g (0.009 mol) of 2,2'-bipyridine-4,4'-dicarboxylic acid were added to a 50 ml single-necked flask. 0.016 g of dibutyldiphenyltin was added, and nitrogen gas was introduced for protection. The reaction was carried out at 185 °C for 3 hours. Then, a polycondensation reaction was carried out at 230 °C for 2.5 hours under a pressure of 8 kPa to obtain copolyester P6: 6.64 g, with a yield of 88.79%. The test results of copolyester P6 are shown in Table 1.

[0067] Preparation of coating: First, a mixed solvent of ethyl acetate and dichloromethane with a mass ratio of 1:2 is prepared; then, copolyester P6 and the above mixed solvent are used to make a saturated solution at room temperature; the above saturated solution is mixed with 30nm rutile titanium dioxide and E-12 (604) epoxy resin at a mass ratio of 70:10:20, and heated and stirred at 80°C for 1 hour in a sealed container to obtain the required viscous coating. The coating is then evenly sprayed onto the surface of the substrate to be protected using a spray gun. After the solvent evaporates, a 25μm corrosion-resistant and wear-resistant coating T6 is formed.

[0068] The coating has a hardness of 201.9 Hv, a coefficient of friction of 0.32, and an adhesion of 8.79 MPa. After immersion in a 3.5 wt% NaCl solution for 30 days, its corrosion rate is 1.18 × 10⁻⁶. -4 mm / year, with high corrosion resistance, a significant improvement over existing coatings; can provide effective protection under various environmental conditions.

[0069] Coastal protection facilities, such as breakwaters and revetments, are subject to long-term erosion by seawater and tidal abrasion, making them prone to corrosion and structural damage. This affects their protective effectiveness and durability. These facilities play a crucial role in protecting coastal areas from waves and storms, maintaining shoreline stability, and preventing land erosion. However, the harsh marine environment accelerates the aging and damage of these facilities, increasing the frequency and cost of maintenance and replacement.

[0070] The corrosion-resistant and wear-resistant coating T6 developed in this embodiment can effectively protect coastal protection facilities, prevent seawater erosion and tidal wear, improve the durability and protective effect of the facilities, and reduce maintenance frequency and cost, which is of great significance.

[0071] Example 8: 4.228 g (0.011 mol) of monomer M, 2.819 g (0.022 mol) of 2,5-furandiethanol and 2.198 g (0.009 mol) of 2,2'-bipyridine-4,4'-dicarboxylic acid were added to a 50 ml single-necked flask. 0.016 g of dibutyldiphenyltin was added, and nitrogen gas was introduced for protection. The reaction was carried out at 190 °C for 3 hours. Then, a polycondensation reaction was carried out at 10 kPa and 240 °C for 2.5 hours to obtain copolyester P7: 6.34 g, with a yield of 84.76%. The test results of copolyester P7 are shown in Table 1.

[0072] Preparation of coating: First, a mixed solvent of ethyl acetate and dichloromethane with a mass ratio of 1:2 is prepared; then, copolyester P8 and the above mixed solvent are used to prepare a saturated solution at room temperature; the above saturated solution is mixed with 30nm rutile titanium dioxide and E-12 (604) epoxy resin at a mass ratio of 70:7.5:22.5, and heated and stirred at 80°C for 1 hour in a sealed container to obtain the required viscous coating. The coating is then evenly sprayed onto the surface of the substrate to be protected using a spray gun. After the solvent evaporates, a 30μm corrosion-resistant and wear-resistant coating T7 is formed.

[0073] The coating has a hardness of 203.8 Hv, a coefficient of friction of 0.32, and an adhesion of 8.52 MPa. After immersion in a 3.5 wt% NaCl solution for 30 days, its corrosion rate is 1.73 × 10⁻⁶. -4 mm / year, with high corrosion resistance, a significant improvement over existing coatings; can provide effective protection under various environmental conditions.

[0074] Water treatment facilities, including water purification plants and wastewater treatment plants, have equipment and pipelines that are in constant contact with water and chemicals, making them susceptible to corrosion and wear. The proper functioning of these facilities is crucial for ensuring water quality safety and environmental protection. However, corrosion and wear not only lead to decreased equipment performance but also increase maintenance and replacement costs, and may even cause safety and environmental problems.

[0075] The corrosion-resistant and wear-resistant coating T7 developed in this embodiment can effectively protect these facilities, prevent corrosion and wear, improve the durability and operating efficiency of the equipment, and reduce maintenance and replacement costs, thus playing an important protective role.

[0076] The performance of the copolyesters from Examples 2 to 8 was tested, and the relevant data are listed in Table 1 below. Table 1: Copolyester P from Examples 2 to 8 1～ Performance data comparison between P7 and the control sample

[0077]

[0078] [8] Djouonkep L D W, Tamo A K, Doench I, et al. Synthesis of High - Performance Thiophene - Aromatic Polyesters from Bio - Sourced Organic Acids and Polysaccharide - Derived Diol: Characterization and Degradability Studies[J]. Molecules, 2022, 27(1).

[0079] Comparison of the anti - corrosion performance of the coatings

[0080]

[0081] [3] Wu Y, Wu Y, Sun Y, et al. 2D Nanomaterials Reinforced Organic Coatings for Marine Corrosion Protection: State of the Art, Challenges, and Future Prospectives[J]. Advanced Materials, 2024.

[0082] Coating performance testing

[0083]

[0084] [4] Mohammadzadeh H, Jafari R, Azargoon A. Mechanical, morphological, and corrosion features of Ni–Cr oxide nanocomposite coating deposited on SS304 by EPD[J]. International Journal of Applied Ceramic Technology, 2024, 35(38): 5231 - 5269.

[0085] As shown in Table 1, the number-average molecular weights of the copolyesters P1 to P7 synthesized in this invention using 2,6-dihydroxyanthraquinone, 2,5-furandimethylethanol, and 2,2'-bipyridine-4,4'-dicarboxylic acid as reactants are all higher than those of thiophene-aromatic polyester (PHS50). The tensile strength of thiophene-aromatic polyester (PHS50) is 80 MPa, while the tensile strength of the copolyesters synthesized in this invention ranges from 180.2 to 187.9 MPa. Furthermore, the elongation at break of thiophene-aromatic polyester (PHS50) is 370%, while the elongation at break of the copolyesters P1 to P7 synthesized in this invention ranges from 431.2% to 457.7%. As shown in Table 2, the corrosion rate of the h-BN / PVA coating is 1.19 × 10⁻⁶. -3 The corrosion rate of the corrosion-resistant and wear-resistant coating prepared by this invention can reach 0.95 × 10 mm / year, while the corrosion rate of the coating is 0.95 × 10 mm / year. -6 mm / year, and from the data comparison in Table 3, it can be seen that the adhesion of the corrosion-resistant and wear-resistant coating prepared in this invention can reach 8.79 MPa compared with that of graphene-reinforced epoxy powder coating ([9] Ou Z, Kong G, Zhang J, et al. Preparation and anticorrosion performance of graphene-reinforced epoxy powder coating[J]. Journal of Materials Research and Technology, 2024, 28: 4626-38.) (adhesion 3.88 MPa), and the hardness of the coating prepared in this invention can reach 203.8 Hv, the coefficient of friction can reach 0.31, and the corrosion current density can reach 5.1×10 –6 A.cm -2 about.

[0086] In summary, this invention uses 2,6-dihydroxyanthraquinone, 2,5-furandimethylethanol, and 2,2'-bipyridine-4,4'-dicarboxylic acid as reactants, and titanium acetylacetone oxide, titanium tetraisopropoxide, and dibutyldiphenyltin as catalysts to prepare a copolyester. Compared to traditional polyesters, this copolyester exhibits superior mechanical properties, and the mechanical properties and corrosion resistance of coil coatings prepared from it are also relatively improved. Therefore, this invention, applying for a patent for "Copolyester Based on Dihydroxyanthraquinone and its Application in Corrosion-Resistant and Wear-Resistant Coatings," has promising market prospects.

[0087] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. The preparation and application of a corrosion-resistant and wear-resistant coating based on copolyester P as the main component, characterized in that, The coating preparation method is as follows: First, a mixed solvent of ethyl acetate and dichloromethane with a mass ratio of 1:2 is prepared; then, a copolyester P and the above mixed solvent are mixed to form a saturated solution at room temperature; the above saturated solution is then mixed with 30nm rutile titanium dioxide and E-12 (604) epoxy resin at a mass ratio of 70: Mix (5~10):(20~25) and heat and stir at 80℃ for 1 hour in a sealed container to obtain the desired viscous coating. Its purpose is to uniformly spray this coating onto the surface requiring protection using a spray gun. After the solvent evaporates, a 10~30μm corrosion-resistant and wear-resistant coating is formed. The key component of the coating is a copolyester P based on 2,6-dihydroxyanthraquinone, whose structure is shown in Formula I. In the above structural formula, m is 61-73 and n is 46-55.

2. Preparation and application of a corrosion-resistant and wear-resistant coating based on copolyester P as the main component, characterized in that... The preparation of a copolyester P based on 2,6-dihydroxyanthraquinone as described in claim 1 comprises the following steps: 1) Synthesis of monomer M: 2,6-dihydroxyanthraquinone, potassium carbonate, and methyl chloroacetate were added to a closed reactor in a molar ratio of 1:0.50–0.60:2–2.

05. Dimethyl sulfoxide was added to dissolve the mixture, and the reaction mixture was heated to 100°C and stirred continuously for 2–3 hours. After the reaction was completed, the mixture was cooled to room temperature, and then 0.10 mol / L sodium hydroxide solution was slowly added under stirring until no more precipitate formed. The mixture was then filtered, and the filter cake was washed with distilled water until neutral. The solid product was dried in an oven at 60°C for 1–2 hours to obtain monomer M of structural formula I. 2) Synthesis of copolyester P: Using the synthesized monomer M, the diol 2,5-furandiethanol (CAS No. 1883-75-6), and the diacid 2,2'-bipyridine-4,4'-dicarboxylic acid (CAS No. 610-92-4) as the three monomer raw materials, a suitable catalyst was added and nitrogen gas was introduced for protection. The temperature was controlled at 160-190℃ and the reaction was stirred for 2-4 hours. Then, a polycondensation reaction was carried out at a pressure of 5-10 kPa and a temperature of 210-240℃ for 2-3 hours to obtain the structure shown in Formula I, with a molecular weight of 5*10. 4 ~7*10 4 Copolyester P in the range of g / mol.

3. The preparation and application of a corrosion-resistant and mechanically abrasion-resistant coating based on copolyester as the main component, characterized in that... In the preparation step of the 2,6-dihydroxyanthraquinone-based copolyester P according to claim 2, the molar ratio of monomer M, 2,2'-bipyridine-4,4'-dicarboxylic acid, and 2,5-furandimethyl alcohol is (1.0-1.10):(0.90-1.0):2.

00.

4. Preparation and application of a corrosion-resistant and mechanically abrasion-resistant coating based on copolyester as the main component, characterized in that... The catalyst used in the preparation of the 2,6-dihydroxyanthraquinone-based copolyester P according to claim 2 is one of titanium acetylacetone oxide, titanium tetraisopropoxide, and dibutyldiphenyltin, and the amount of the catalyst is 0.1% to 0.5% of the mass of the reactant monomer M.

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