A waterborne polyurethane abrasion-resistant coating and a method of making the same

Abstract

The application belongs to the technical field of paint, and particularly relates to a water-based polyurethane wear-resistant paint and a preparation method thereof. The water-based polyurethane wear-resistant paint is composed of the following raw materials in parts by weight: 65-75 parts of water-based polyurethane, 5-10 parts of polytetrafluoroethylene, 3-6 parts of fluorinated modified nano-silicon dioxide, 2-5 parts of aminated graphene, 2-3 parts of hexamethylene diisocyanate, 0.5-1 part of an emulsifier and 1-3 parts of nano-cellulose. The application uses the water-based polyurethane to construct a stable main frame under the cross-linking action of HDI, polytetrafluoroethylene and fluorinated modified nano-silicon dioxide to form a persistent super-hydrophobic and anti-fouling outer layer on the surface, and aminated graphene and nano-cellulose to provide strong and tough mechanical support inside. The organic combination of the components makes the paint have good impact resistance, chemical resistance and wear resistance.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a water-based polyurethane wear-resistant coating and its preparation method. Background Technology

[0002] Coatings are among the most widely used materials in modern industry and daily life, with primary functions including decoration, beautification, and protection, providing physical and chemical barriers for various substrates. However, traditional solvent-based coatings release large amounts of volatile organic compounds (VOCs) and other harmful substances during use, causing serious environmental pollution and posing a significant threat to human health. With increasingly stringent environmental regulations and growing public awareness of environmental protection, the global coatings industry is at a critical juncture in its transformation from high-pollution, high-energy-consumption to low-pollution, low-energy-consumption. In response to increasingly stringent environmental requirements, the coatings industry is accelerating the application of water-based technologies. Water-based coatings use water as the primary solvent or dispersion medium, significantly reducing VOC emissions compared to traditional solvent-based coatings, while also offering higher safety and easier application, making them a crucial technological pathway for the green transformation of the coatings industry.

[0003] Waterborne polyurethane coatings, as an environmentally friendly coating based on polyurethane dispersions, have garnered significant attention in the market due to their low VOC emissions, excellent mechanical properties, and chemical stability. Compared to traditional solvent-based coatings, waterborne polyurethane coatings use water as the dispersion medium, significantly reducing environmental pollution and harm to human health, fully complying with global sustainable development goals and stringent environmental regulations. In terms of performance characteristics, the molecular structure of waterborne polyurethane coatings consists of soft and hard segments, possessing highly tunable physical properties. The soft segments impart good flexibility to the coating film, while the hard segments provide excellent mechanical strength and abrasion resistance, resulting in outstanding performance under external friction and impact conditions. This characteristic makes waterborne polyurethane coatings widely applicable in demanding industrial, domestic, and construction fields. Furthermore, their low flammability significantly improves the safety of the coating during production, transportation, and application. Application methods are flexible, allowing for spraying, brushing, and other processes, and they are suitable for various substrates. Despite the numerous advantages of waterborne polyurethane coatings, the hydrophilic groups in their waterborne system may lead to a decrease in the mechanical properties of the coating film. Meanwhile, waterborne polyurethane coatings are prone to swelling or degradation in acidic, alkaline, or solvent-based chemical environments, limiting their application in harsh environments. These issues have become major technical bottlenecks for the further development of waterborne polyurethane coatings. Therefore, based on the above problems, it is extremely necessary to develop a waterborne polyurethane coating that is chemically resistant, impact-resistant, and abrasion-resistant. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a water-based polyurethane wear-resistant coating and its preparation method.

[0005] The technical effects described in this invention are achieved through the following technical solution: a waterborne polyurethane wear-resistant coating, comprising the following raw materials in parts by weight: 65-75 parts waterborne polyurethane, 5-10 parts polytetrafluoroethylene, 3-6 parts fluorinated modified nano silica, 2-5 parts aminated graphene, 2-3 parts hexamethylene diisocyanate, 0.5-1 parts emulsifier and 1-3 parts nanocellulose.

[0006] Preferably, the emulsifier is any one of Tween-20, sodium dodecylbenzenesulfonate, and PEG-40.

[0007] Preferably, the specific preparation steps of the fluorinated modified nano-silica are as follows:

[0008] A1: Disperse nano-silica in anhydrous ethanol, sonicate to disperse evenly, and obtain nano-silica dispersion; add trifluoropropyltriethoxysilane to anhydrous ethanol, stir to mix evenly, adjust pH to 4-5 with 0.1M hydrochloric acid, let stand for 30 min, and obtain silane solution.

[0009] A2: Slowly add the nano-silica dispersion prepared in step A1 into the silane solution, control the temperature at 40-60℃, stir the reaction for 4-6 hours, centrifuge, filter, wash three times alternately with anhydrous ethanol and deionized water, and dry at 60-80℃ for 12-24 hours to obtain fluorinated modified nano-silica.

[0010] Preferably, in step A1, the ratio of the amount of nano-silica to anhydrous ethanol is 20 mg: 1-2 mL; and the ratio of the amount of trifluoropropyltriethoxysilane to anhydrous ethanol is 1 g: 20-30 mL.

[0011] Preferably, in step A2, the volume ratio of the nano-silica dispersion to the silane solution is 100:3 to 5.

[0012] Preferably, the specific preparation steps of the amino-based graphene are as follows:

[0013] B1: Graphene oxide was dispersed in deionized water, ultrasonically dispersed until uniform, and then anhydrous ethanol was added. After stirring for 10 minutes, a graphene oxide dispersion was obtained.

[0014] B2: Add ethylenediamine to the graphene oxide dispersion prepared in step B1, adjust the pH to 10-11 with ammonia, heat in a water bath to 80°C, stir for 6-8 hours, cool naturally to room temperature after the reaction is complete, centrifuge, wash three times alternately with deionized water and anhydrous ethanol, and dry at 60°C for 12-24 hours to obtain amino-based graphene.

[0015] Preferably, in step B1, the ratio of the amount of graphene oxide, deionized water and anhydrous ethanol is 1g:100-150mL:8-10mL.

[0016] Preferably, in step B2, the volume ratio of the graphene oxide dispersion to ethylenediamine is 10-15:2.

[0017] Preferably, another aspect of the present invention provides a method for preparing a waterborne polyurethane wear-resistant coating, the specific preparation steps of which are as follows:

[0018] Step 1: Disperse nanocellulose in deionized water and sonicate for 20-30 min to obtain a 3-5 wt% nanocellulose dispersion; disperse polytetrafluoroethylene in deionized water and sonicate for 10-20 min to obtain a 30-40 wt% polytetrafluoroethylene dispersion; add aminated graphene to a 90 wt% ethanol solution and sonicate for 20-30 min to obtain a 1.5-2 wt% aminated graphene aqueous dispersion.

[0019] Step 2: Add waterborne polyurethane to deionized water and dilute to 30-40 wt% solid content. Add 0.5-2 wt% emulsifier and stir for 10 min to obtain the waterborne polyurethane system. Slowly add the polytetrafluoroethylene dispersion prepared in Step 1 to the waterborne polyurethane system and stir at 300-500 rpm for 20 min.

[0020] Step 3: After completing the operation in Step 2, add fluorinated modified nano-silica, continue stirring at 300-500 rpm for 20 min, add the aminated graphene aqueous dispersion prepared in Step 1, continue stirring for 20-30 min, add the nano-cellulose dispersion prepared in Step 1, continue stirring for 20 min, and obtain a mixed solution.

[0021] Step 4: Add hexamethylene diisocyanate to anhydrous ethanol and stir to mix evenly to obtain a 50-70 wt% crosslinking agent solution; slowly add the crosslinking agent solution to the mixed solution prepared in step 3. After the addition is complete, stir at 300 rpm for 30-40 min, evaporate under reduced pressure to concentrate to a solid content of 45-55%, and let stand at room temperature for 1-2 h to obtain a waterborne polyurethane wear-resistant coating.

[0022] Preferably, in step four, the reduced pressure evaporation parameters are: vacuum degree -0.08MPa to -0.09MPa, temperature 40 to 50℃, and stirring speed 300 to 500rpm.

[0023] The beneficial effects of this invention are as follows:

[0024] This coating uses waterborne polyurethane as the main matrix. By introducing components such as polytetrafluoroethylene (PTFE), fluorinated modified nano-silica, amino graphene, nano-cellulose, and hexamethylene diisocyanate (HDI) into the formulation, a composite coating with ultra-wear resistance, superhydrophobicity, and high mechanical stability is synergistically constructed. This invention utilizes PTFE and fluorinated modified silica to synergistically construct a highly hydrophobic outer layer structure on the coating surface, significantly reducing the contact between moisture and the coating interior, providing crucial protection for the moisture-sensitive nano-cellulose (CNF). Due to its ultra-low surface energy and low coefficient of friction, PTFE effectively reduces the adhesion of moisture and oil, while also enhancing the coating's wear resistance and scratch resistance. Fluorination modification of nano-silica effectively improves the surface's hydrophobicity and anti-fouling ability, and also imparts better surface hardness and chemical inertness to the coating film; the fluoroalkyl groups on the nano-silica surface provide extremely low surface energy characteristics, enhancing the synergistic effect with PTFE, resulting in a stable superhydrophobic coating surface. Fluorinated modified silica further enhances the surface hardness and antifouling ability of the coating by forming a dense hydrophobic network with polytetrafluoroethylene. The constructed multi-layered hydrophobic barrier prevents moisture erosion of nanocellulose, effectively avoiding mechanical property degradation caused by nanocellulose's moisture absorption, and utilizes hydrophobic interactions to prevent fiber agglomeration, ensuring uniform dispersion within the coating. Inside the coating, aminated graphene and nanocellulose jointly form a highly efficient mechanical reinforcement network. The amino groups on the surface of aminated graphene can form hydrogen bonds and covalent bonds with the waterborne polyurethane molecular chains, making the interfaces within the coating more tightly bonded, thus significantly improving overall toughness and stability. Simultaneously, the chemical reaction between aminated graphene and nanocellulose through the amino groups and hydroxyl groups on the fiber surface constructs a multi-dimensional reinforcement network, which disperses stress and effectively prevents stress concentration when the coating is subjected to external impact or bending, reducing crack initiation and propagation. Hexamethylene diisocyanate (HDI), acting as a crosslinking agent, reacts with the hydroxyl groups in waterborne polyurethane to form a highly crosslinked three-dimensional network structure. This effectively enhances the coating's hardness and chemical resistance. Furthermore, it strengthens the interactions between components through interfacial reactions with residual amino groups on the surface of aminated graphene and potential active sites in fluorinated modified silica. This molecular-level crosslinking mechanism allows the coating to maintain stable performance even in harsh environments such as high humidity, acid and alkali conditions, or organic solvents. In addition, nanocellulose, utilizing its high specific surface area and certain functional groups, provides additional crosslinking points, synergistically constructing a multi-layered mechanical support structure with aminated graphene. This significantly improves the coating's overall performance, including crack resistance, impact resistance, and abrasion resistance, while maintaining its flexibility.The abundant amino groups on the surface of aminated graphene form hydrogen bonds and covalent bonds with the molecular chains of waterborne polyurethane, significantly strengthening the interfacial adhesion between the matrix and graphene sheets. Furthermore, it can chemically react with the hydroxyl groups on the surface of nanocellulose, achieving more effective stress transfer and dispersion, thereby improving toughness and impact resistance. Nanocellulose, with its high specific surface area and excellent fiber network structure, forms a synergistic reinforcing effect with aminated graphene, not only dispersing stress and reducing crack formation under external forces but also maintaining the flexibility and stability of the coating.

[0025] In summary, this invention utilizes waterborne polyurethane to construct a stable main framework under the crosslinking effect of HDI, polytetrafluoroethylene and fluorinated modified nano-silica to form a durable superhydrophobic and antifouling outer layer on the surface, and aminated graphene and nanocellulose to provide strong mechanical support inside. The organic combination of the components enables this coating to achieve good impact resistance, chemical resistance and wear resistance. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in this 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 for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 These are graphs showing the abrasion resistance test results of the waterborne polyurethane coatings prepared in Example 2 and Comparative Examples 1-5 of the present invention.

[0028] Figure 2 The graph shows the mechanical strength test results of the waterborne polyurethane coatings prepared in Example 2 and Comparative Examples 1-5 of this invention. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the raw materials involved in the present invention are all purchased through conventional commercial channels.

[0030] Example 1: A waterborne polyurethane wear-resistant coating, comprising the following raw materials in parts by weight: 65 parts waterborne polyurethane, 5 parts polytetrafluoroethylene, 3 parts fluorinated modified nano silica, 2 parts aminated graphene, 2 parts hexamethylene diisocyanate, 0.5 parts emulsifier and 1 part nanocellulose.

[0031] The specific preparation steps for fluorinated modified nano-silica are as follows:

[0032] A1: Disperse 2g of nano-silica in 100mL of anhydrous ethanol, and sonicate to disperse evenly to obtain a nano-silica dispersion; add 0.5g of trifluoropropyltriethoxysilane to 20mL of anhydrous ethanol, stir and mix evenly, adjust the pH to 5 with 0.1M hydrochloric acid, and let stand for 30min to obtain a silane solution.

[0033] A2: Slowly add 100 mL of nano silica dispersion prepared in step A1 to 3 mL of silane solution, control the temperature at 40 °C, stir the reaction for 6 h, centrifuge, filter, wash three times alternately with anhydrous ethanol and deionized water, and dry at 60 °C for 24 h to obtain fluorinated modified nano silica.

[0034] The specific preparation steps for amino-based graphene are as follows:

[0035] B1: Disperse 1g of graphene oxide in 100mL of deionized water, sonicate to disperse evenly, then add 8mL of anhydrous ethanol, and continue stirring for 10min to obtain a graphene oxide dispersion.

[0036] B2: Add 2 mL of ethylenediamine to 100 mL of graphene oxide dispersion prepared in step B1, adjust the pH to 11 with ammonia, heat in a water bath to 80 °C, stir and react for 6 h. After the reaction is complete, cool naturally to room temperature, centrifuge, wash three times alternately with deionized water and anhydrous ethanol, and dry at 60 °C for 12 h to obtain amino-based graphene.

[0037] The specific preparation steps for waterborne polyurethane wear-resistant coatings are as follows:

[0038] Step 1: Disperse nanocellulose in deionized water and sonicate for 20 min to obtain a 3 wt% nanocellulose dispersion; disperse polytetrafluoroethylene in deionized water and sonicate for 10 min to obtain a 30 wt% polytetrafluoroethylene dispersion; add aminated graphene to a 90 wt% ethanol solution and sonicate for 20 min to obtain a 1.5 wt% aminated graphene aqueous dispersion.

[0039] Step 2: Add waterborne polyurethane to deionized water and dilute to 30 wt% solid content. Add 0.5 wt% of PEG-40 by weight of waterborne polyurethane and stir for 10 min to obtain the waterborne polyurethane system. Slowly add the polytetrafluoroethylene dispersion prepared in Step 1 to the waterborne polyurethane system and stir at 300 rpm for 20 min.

[0040] Step 3: After completing the operation in Step 2, add fluorinated modified nano-silica, continue stirring at 300 rpm for 20 min, add the amino graphene aqueous dispersion prepared in Step 1, continue stirring for 20 min, add the nano-cellulose dispersion prepared in Step 1, continue stirring for 20 min, and obtain a mixed solution.

[0041] Step 4: Add hexamethylene diisocyanate to anhydrous ethanol and stir to mix evenly to obtain a 50wt% crosslinking agent solution; slowly add the crosslinking agent solution to the mixed solution prepared in Step 3. After the addition is complete, stir at 300 rpm for 30 min, and evaporate under reduced pressure with the following parameters: vacuum degree -0.08 MPa, temperature 40℃, stirring speed 300 rpm, concentrate to a solid content of 45%, and let stand at room temperature for 1 h to obtain a waterborne polyurethane wear-resistant coating.

[0042] Example 2: A waterborne polyurethane wear-resistant coating, comprising the following raw materials in parts by weight: 70 parts waterborne polyurethane, 8 parts polytetrafluoroethylene, 5 parts fluorinated modified nano silica, 4 parts amino graphene, 2.5 parts hexamethylene diisocyanate, 0.8 parts emulsifier and 2.5 parts nano cellulose.

[0043] The specific preparation steps for fluorinated modified nano-silica are as follows:

[0044] A1: Disperse 2g of nano-silica in 180mL of anhydrous ethanol, and sonicate to disperse evenly to obtain a nano-silica dispersion; add 0.5g of trifluoropropyltriethoxysilane to 25mL of anhydrous ethanol, stir and mix evenly, adjust the pH to 4.5 with 0.1M hydrochloric acid, and let stand for 30min to obtain a silane solution.

[0045] A2: Slowly add 180 mL of nano silica dispersion prepared in step A1 to 8 mL of silane solution, control the temperature at 50 °C, stir for 5 h, centrifuge, filter, wash three times alternately with anhydrous ethanol and deionized water, and dry at 70 °C for 20 h to obtain fluorinated modified nano silica.

[0046] The specific preparation steps for amino-based graphene are as follows:

[0047] B1: Disperse 1g of graphene oxide in 150mL of deionized water, sonicate to disperse evenly, then add 10mL of anhydrous ethanol, and continue stirring for 10min to obtain a graphene oxide dispersion.

[0048] B2: Add 2 mL of ethylenediamine to 150 mL of graphene oxide dispersion prepared in step B1, adjust the pH to 10.5 with ammonia, heat in a water bath to 80 °C, stir and react for 7 h. After the reaction is complete, cool naturally to room temperature, centrifuge, wash three times alternately with deionized water and anhydrous ethanol, and dry at 60 °C for 20 h to obtain amino-based graphene.

[0049] The specific preparation steps for waterborne polyurethane wear-resistant coatings are as follows:

[0050] Step 1: Disperse nanocellulose in deionized water and sonicate for 25 min to obtain a 4 wt% nanocellulose dispersion; disperse polytetrafluoroethylene in deionized water and sonicate for 15 min to obtain a 35 wt% polytetrafluoroethylene dispersion; add aminated graphene to a 90 wt% ethanol solution and sonicate for 25 min to obtain a 2 wt% aminated graphene aqueous dispersion.

[0051] Step 2: Add waterborne polyurethane to deionized water and dilute to 35 wt% solid content. Add 1.5 wt% of Tween-20 by weight of waterborne polyurethane and stir for 10 min to obtain the waterborne polyurethane system. Slowly add the polytetrafluoroethylene dispersion prepared in Step 1 to the waterborne polyurethane system and stir at 400 rpm for 20 min.

[0052] Step 3: After completing the operation in Step 2, add fluorinated modified nano silica, continue stirring at 400 rpm for 20 min, add the amino graphene aqueous dispersion prepared in Step 1, continue stirring for 25 min, add the nano cellulose dispersion prepared in Step 1, continue stirring for 20 min, and obtain a mixed solution.

[0053] Step 4: Add hexamethylene diisocyanate to anhydrous ethanol and stir to mix evenly to obtain a 60wt% crosslinking agent solution; slowly add the crosslinking agent solution to the mixed solution prepared in step 3. After the addition is complete, stir at 300 rpm for 35 min, and evaporate under reduced pressure with the following parameters: vacuum degree -0.08 MPa, temperature 45℃, stirring speed 400 rpm, concentrate to 50% solid content, and let stand at room temperature for 2 h to obtain waterborne polyurethane wear-resistant coating.

[0054] Example 3: A waterborne polyurethane wear-resistant coating, comprising the following raw materials in parts by weight: 75 parts waterborne polyurethane, 10 parts polytetrafluoroethylene, 6 parts fluorinated modified nano silica, 5 parts aminated graphene, 3 parts hexamethylene diisocyanate, 1 part emulsifier and 3 parts nanocellulose.

[0055] The specific preparation steps for fluorinated modified nano-silica are as follows:

[0056] A1: Disperse 2g of nano-silica in 200mL of anhydrous ethanol, sonicate to disperse evenly, and obtain nano-silica dispersion; add 0.5g of trifluoropropyltriethoxysilane to 30mL of anhydrous ethanol, stir to mix evenly, adjust pH to 4 with 0.1M hydrochloric acid, let stand for 30min, and obtain silane solution.

[0057] A2: Slowly add 200 mL of nano silica dispersion prepared in step A1 to 10 mL of silane solution, control the temperature at 60 °C, stir the reaction for 4 h, centrifuge, filter, wash three times alternately with anhydrous ethanol and deionized water, and dry at 80 °C for 12 h to obtain fluorinated modified nano silica.

[0058] The specific preparation steps for amino-based graphene are as follows:

[0059] B1: Disperse 1g of graphene oxide in 120mL of deionized water, sonicate to disperse evenly, then add 9mL of anhydrous ethanol, and continue stirring for 10min to obtain a graphene oxide dispersion.

[0060] B2: Add 2 mL of ethylenediamine to 120 mL of graphene oxide dispersion prepared in step B1, adjust the pH to 11 with ammonia, heat in a water bath to 80 °C, stir and react for 8 h. After the reaction is complete, cool naturally to room temperature, centrifuge, wash three times alternately with deionized water and anhydrous ethanol, and dry at 60 °C for 24 h to obtain amino-based graphene.

[0061] The specific preparation steps for waterborne polyurethane wear-resistant coatings are as follows:

[0062] Step 1: Disperse nanocellulose in deionized water and sonicate for 30 min to obtain a 5 wt% nanocellulose dispersion; disperse polytetrafluoroethylene in deionized water and sonicate for 20 min to obtain a 40 wt% polytetrafluoroethylene dispersion; add aminated graphene to a 90 wt% ethanol solution and sonicate for 30 min to obtain a 1.8 wt% aminated graphene aqueous dispersion.

[0063] Step 2: Add waterborne polyurethane to deionized water and dilute to 40wt% solid content. Add 2wt% sodium dodecylbenzenesulfonate and stir for 10 min to obtain the waterborne polyurethane system. Slowly add the polytetrafluoroethylene dispersion prepared in Step 1 to the waterborne polyurethane system and stir at 500 rpm for 20 min.

[0064] Step 3: After completing the operation in Step 2, add fluorinated modified nano-silica, continue stirring at 500 rpm for 20 min, add the amino graphene aqueous dispersion prepared in Step 1, continue stirring for 30 min, add the nano-cellulose dispersion prepared in Step 1, continue stirring for 20 min, and obtain a mixed solution.

[0065] Step 4: Add hexamethylene diisocyanate to anhydrous ethanol and stir to mix evenly to obtain a 70wt% crosslinking agent solution; slowly add the crosslinking agent solution to the mixed solution prepared in step 3. After the addition is complete, stir at 300 rpm for 40 min, and evaporate under reduced pressure with the following parameters: vacuum degree -0.08 MPa, temperature 50℃, stirring speed 500 rpm, concentrate to a solid content of 55%, and let stand at room temperature for 1 h to obtain a waterborne polyurethane wear-resistant coating.

[0066] Comparative Example 1: The operation of Comparative Example 1 is basically the same as that of Example 2, except that polytetrafluoroethylene is not added in Comparative Example 1.

[0067] Comparative Example 2: The operation of Comparative Example 2 is basically the same as that of Example 2, except that no fluorinated modified nano-silica was added in Comparative Example 2.

[0068] Comparative Example 3: The operation of Comparative Example 3 is basically the same as that of Example 2, except that no amino graphene is added in Comparative Example 3.

[0069] Comparative Example 4: The operation of Comparative Example 4 is basically the same as that of Example 2, except that no nanocellulose is added in Comparative Example 4.

[0070] Comparative Example 5: The operation of Comparative Example 5 is basically the same as that of Example 2, except that polytetrafluoroethylene and fluorinated modified silica were not added in Comparative Example 5.

[0071] Performance testing:

[0072] Hydrophobicity test: The waterborne polyurethane coatings prepared in Examples 1-3 and Comparative Examples 1-5 were tested for contact angle. The waterborne polyurethane coatings were applied to a glass plate with a thickness of 80 μm. After curing, they were cut into circular samples with a diameter of 100 mm for testing. A contact angle greater than 140° was recorded as A, a contact angle between 130° and 140° was recorded as B, and a contact angle less than 130° was recorded as C. All samples were tested at room temperature and 50% humidity. 5 μL of water droplets were used for each test. To ensure data reliability, the contact angle of each sample was measured 5 times, and the average value was taken as the final result. The test results are shown in Table 1.

[0073] Hydrophobic stability test: The test procedure is basically the same as above, and the test conditions are divided into four types. The first type is immersion in 3.5% NaCl solution at room temperature; the second type is testing at a high temperature of 85°C and a humidity of 70%; the third type is testing at 95% humidity and room temperature; the fourth type is testing at room temperature, 70% humidity, and ultraviolet irradiation with a UV intensity of 0.5 W / m. 2 The test duration was 168 hours, and the test results are shown in Table 1.

[0074] Table 1. Test results of hydrophobicity and stability of waterborne polyurethane

[0075]

[0076]

[0077] As shown in Table 1, the waterborne polyurethane coating prepared by this invention exhibits excellent hydrophobicity through the synergistic effect of multiple substances. The results of Example 2 and Comparative Examples 1, 2, and 5 demonstrate that polytetrafluoroethylene (PTFE) and fluorinated modified nano-silica can effectively construct a superhydrophobic surface, achieving the superhydrophobic properties of the coating. The results of Comparative Example 1 and Example 2 show that the absence of PTFE significantly reduces the overall hydrophobicity of the coating. Under high-salt and high-humidity conditions, the lack of PTFE protection leads to a significant decrease in the hydrophobic properties of the coating. The results of Comparative Example 2 and Example 2 further illustrate this point. It is known that the absence of fluorinated modified nano-silica reduces the hydrophobicity of the coating. Although polytetrafluoroethylene is still present, the lack of synergistic effect of fluorinated silica prevents the formation of a dense hydrophobic network, thus affecting the hydrophobicity. In high-salt and high-humidity environments, polytetrafluoroethylene alone cannot fully maintain its superhydrophobicity, resulting in impaired hydrophobicity. The results of Comparative Example 1, Comparative Example 2, and Example 2 show that nanocellulose may agglomerate due to the lack of hydrophobicity, which in turn leads to an increase in coating roughness and may cause the agglomerated areas to become weak points in chemical corrosion, thereby reducing chemical stability.

[0078] Abrasion resistance test: The waterborne polyurethane coatings prepared in Example 2 and Comparative Examples 1-5 were applied to a glass plate with a thickness controlled at 80 μm. After curing, the plates were cut into circular samples with a diameter of 100 mm. The samples were then abraded with a 500 g weight at 60 rpm for 500 and 1000 revolutions. The mass change before and after the test was measured. Abrasion loss = (mass before test - mass after test) / mass before test × 100%. The results are as follows: Figure 1 As shown.

[0079] Depend on Figure 1The results show that the waterborne polyurethane prepared by this invention has excellent wear resistance. The results of Comparative Example 1 and Example 2 show that the absence of polytetrafluoroethylene (PTFE) directly leads to an increase in the coefficient of friction and intensified surface wear. Although fluorinated modified nano-silica can provide a certain degree of hardness, its synergistic effect is significantly affected. The results of Comparative Example 2 and Example 2 show that without fluorinated modified nano-silica, the surface hardness of the coating decreases, and scratch damage increases. PTFE alone cannot provide sufficient hardness, which leads to a decrease in wear resistance. The results of Comparative Example 3 and Example 2 show that the absence of amino-modified graphene... The mechanical reinforcement effect is weakened, but the surface properties are maintained by polytetrafluoroethylene and fluorinated nano-silica. The short-term wear resistance is slightly lower, and the performance deteriorates significantly after long-term wear. As can be seen from the results of Comparative Example 4 and Example 2, the wear resistance is maintained by the surface components polytetrafluoroethylene and fluorinated nano-silica in the short term, and the impact is relatively small. However, under long-term high-load wear, crack propagation increases and durability is significantly affected. As can be seen from the results of Comparative Example 5 and Example 2, the lack of wear-resistant core components severely damages the surface hardness and coefficient of friction, resulting in significant wear loss. This makes the coating more susceptible to mechanical grinding, leading to significant quality damage.

[0080] Mechanical strength test: The waterborne polyurethane coatings prepared in Example 2 and Comparative Examples 1-5 were applied to a polyester film with a thickness controlled at 100 μm. The film was then cut into pieces 150 mm long and 20 mm wide. Tensile strength and elongation at break were tested using a universal testing machine. The results are as follows: Figure 2 As shown.

[0081] Depend on Figure 2 The results show that the waterborne polyurethane coating prepared by this invention has extremely high tensile strength and excellent elongation at break, exhibiting excellent mechanical properties. The results of Comparative Example 1 and Example 2 show that the absence of polytetrafluoroethylene increases surface friction, making cracks more likely to propagate under high strain conditions, and slightly reducing the elongation at break. The results of Comparative Example 2 and Example 2 show that the absence of fluorinated modified nano-silica slightly reduces the coating hardness, but has little impact on mechanical strength. The results of Comparative Example 3 and Example 2 show that the absence of aminated graphene leads to insufficient interfacial bonding, an increase in crack initiation points, and a significant decrease in coating tensile strength. The lack of sheet support from aminated graphene causes cracks to propagate faster under strain conditions, resulting in a significant decrease in elongation. The results of Comparative Example 4 and Example 2 show that the absence of nanocellulose weakens the coating's stress dispersion ability, increases crack propagation, and significantly reduces the elongation at break. The results of Comparative Example 5 and Example 2 show that the coating lacks an effective multidimensional reinforcing structure, causing rapid crack propagation during stretching and a significant reduction in toughness.

[0082] Adhesion test: The waterborne polyurethane coatings prepared in Example 2 and Comparative Examples 1-5 were applied to a glass plate and cured to form a coating. A 10×10 grid was drawn on the surface of the coating using a 2mm cross-cutting tool. After being placed at 85°C and 90% humidity for 72 hours, the coating was tested. Adhesive tape was applied to the grid surface, pressed firmly, and then quickly peeled off. The amount of coating peeling off the grid was recorded and divided into grades 0 to 5 (Grade 0: no peeling; Grade 1: peeling less than 5%; Grade 2: peeling 5-15%; Grade 3: peeling 15-35%; Grade 4: peeling 35-65%; Grade 5: peeling greater than 65%). The results are shown in Table 2 below.

[0083] Table 2. Adhesion test results of waterborne polyurethane

[0084] sample Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Adhesion Level 0 Level 2 Level 2 Level 3 Level 2 Level 4

[0085] As shown in Table 2, the hydrophobic outer layer of waterborne polyurethane prepared in this invention effectively blocks the influence of moisture on the internal material and exhibits excellent adhesion performance. However, the results of Comparative Examples 1, 2, and 2 indicate that the lack of an ultra-dense hydrophobic structure layer synergistically constructed from polytetrafluoroethylene and fluorinated modified nano-silica may have increased the likelihood of moisture intrusion, decreased the interfacial bonding strength of the coating, and consequently led to an expansion of the localized peeling area. Furthermore, the absence of fluorinated modified nano-silica may have resulted in decreased surface hardness, accelerated crack formation due to moisture, and the intrusion of moisture caused the agglomeration of nanofibers, leading to increased surface roughness and affecting adhesion. The results of Comparative Example 3 and Example 2 show that the lack of amino graphene significantly reduces interfacial bonding, exacerbates crack propagation under high humidity conditions, weakens the mechanical support of nanocellulose due to insufficient interfacial bonding, significantly reduces synergy, and noticeably decreases adhesion. The results of Comparative Example 3 and Example 2 also show that the lack of nanocellulose results in an incomplete internal reinforcing network, affecting adhesion to some extent. Furthermore, the results of Comparative Example 5 and Example 2 indicate that the absence of the outer hydrophobic coating completely destroys the coating's protection against moisture, intensifies the agglomeration of nanocellulose due to moisture absorption, leads to uncontrolled local crack propagation, and significantly reduces adhesion.

[0086] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A water-based polyurethane wear-resistant coating, characterized in that, Its composition includes the following raw materials in parts by weight: 65-75 parts waterborne polyurethane, 5-10 parts polytetrafluoroethylene, 3-6 parts fluorinated modified nano silica, 2-5 parts amino graphene, 2-3 parts hexamethylene diisocyanate, 0.5-1 parts emulsifier and 1-3 parts nano cellulose. The fluorinated modified nano-silica is prepared by the following method: A1: Disperse nano-silica in anhydrous ethanol, sonicate to disperse evenly, and obtain nano-silica dispersion; add trifluoropropyltriethoxysilane to anhydrous ethanol, stir to mix evenly, adjust pH with hydrochloric acid, let stand, and obtain silane solution. A2: Slowly add the nano-silica dispersion prepared in step A1 into the silane solution, control the temperature at 40-60℃, stir the reaction, centrifuge, filter, wash alternately with anhydrous ethanol and deionized water, and dry to obtain fluorinated modified nano-silica.

2. The waterborne polyurethane wear-resistant coating according to claim 1, characterized in that, The emulsifier is any one of Tween-20, sodium dodecylbenzenesulfonate, and PEG-40.

3. The waterborne polyurethane wear-resistant coating according to claim 2, characterized in that, In step A1, the ratio of the amount of nano-silica to anhydrous ethanol is 20 mg: 1-2 mL; the ratio of the amount of trifluoropropyltriethoxysilane to anhydrous ethanol is 1 g: 20-30 mL; in step A2, the volume ratio of the nano-silica dispersion to the silane solution is 100: 3-5.

4. The waterborne polyurethane wear-resistant coating according to claim 3, characterized in that, The specific preparation steps for the amino-based graphene are as follows: B1: Graphene oxide is dispersed in deionized water, ultrasonically dispersed until uniform, then anhydrous ethanol is added, and stirring is continued to obtain a graphene oxide dispersion. B2: Add ethylenediamine to the graphene oxide dispersion prepared in step B1, adjust the pH with ammonia, heat in a water bath, stir and react. After the reaction is complete, cool naturally to room temperature, centrifuge, wash alternately with deionized water and anhydrous ethanol, and dry to obtain amino-based graphene.

5. The waterborne polyurethane wear-resistant coating according to claim 4, characterized in that, In step B1, the ratio of the amount of graphene oxide, deionized water and anhydrous ethanol is 1g:100-150mL:8-10mL; in step B2, the volume ratio of the graphene oxide dispersion and ethylenediamine is 10-15:

2.

6. A method for preparing a waterborne polyurethane wear-resistant coating according to any one of claims 1-5, characterized in that, The specific preparation steps are as follows: Step 1: Disperse nanocellulose in deionized water and ultrasonically disperse to obtain nanocellulose dispersion; disperse polytetrafluoroethylene in deionized water and ultrasonically disperse to obtain polytetrafluoroethylene dispersion; add amino-graphene to ethanol solution and ultrasonically disperse to obtain amino-graphene aqueous dispersion. Step 2: Add waterborne polyurethane to deionized water, dilute, add emulsifier, and stir to obtain waterborne polyurethane system; slowly add the polytetrafluoroethylene dispersion prepared in Step 1 to the waterborne polyurethane system and stir. Step 3: After completing the operation in Step 2, add fluorinated modified nano-silica and continue stirring. Add the amino graphene aqueous dispersion prepared in Step 1 and continue stirring. Add the nano-cellulose dispersion prepared in Step 1 and continue stirring to obtain a mixed solution. Step 4: Add hexamethylene diisocyanate to anhydrous ethanol and stir to mix evenly to obtain a crosslinking agent solution; The crosslinking agent solution is slowly added to the mixed solution prepared in step three. After the addition is complete, the mixture is stirred, concentrated by vacuum evaporation, and allowed to stand at room temperature to obtain a water-based polyurethane wear-resistant coating.

7. The method for preparing a waterborne polyurethane wear-resistant coating according to claim 6, characterized in that, In step four, the vacuum evaporation parameters are: vacuum degree -0.08MPa to -0.09MPa, temperature 40 to 50℃, and stirring speed 300 to 500rpm.

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