Wear-resistant anti-fingerprint coating and preparation method thereof

Abstract

The invention discloses a wear-resistant anti-fingerprint coating and a preparation method thereof, and relates to the technical field of coatings, the preparation method comprises the following steps: adding a composite lignin lubricant into absolute ethyl alcohol, and uniformly stirring to obtain a lignin stock solution; in a stirring state, adding the modified cellulose nanocrystal suspension into the lignin stock solution, and carrying out vacuum distillation to obtain a lignin-cellulose composite filler; the preparation method comprises the following steps: adding lignin into N, N-dimethylformamide, uniformly stirring, adding hexamethylene diisocyanate and dibutyltin dilaurate, heating to 90-95 DEG C, reacting for 3-3.5 hours, adding polycarbonate polyol, and carrying out heat preservation reaction for 6-6.5 hours to obtain lignin modified polyurethane; and adding the lignin-cellulose composite filler into the lignin modified polyurethane, and uniformly stirring to obtain the wear-resistant anti-fingerprint coating.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, in particular to a wear-resistant and anti-fingerprint coating and a preparation method thereof. Background Art

[0002] In today's coating application field, with the continuous advancement of science and technology and the improvement of people's quality of life, the requirements for coating performance are becoming more diversified and high-end, especially in terms of wear resistance and anti-fingerprint.

[0003] In the field of electronic devices, such as mobile phones, tablet computers, smart watches, etc., their shells and screen surfaces frequently come into contact with the user's fingers. Fingerprint residue not only affects the aesthetics of the product, but also reduces the clarity and touch sensitivity of the screen, seriously affecting the user experience. Moreover, in daily use, the surface of the device is constantly subjected to various frictions, such as friction with the desktop, clothing, etc., which can easily lead to coating wear, and then cause scratches and paint peeling on the appearance of the device, which not only affects the service life of the product, but also increases the replacement cost of consumers.

[0004] In the field of automotive interiors, components such as dashboards, steering wheels, and door interior panels are often stained with fingerprints, affecting the overall appearance and cleanliness of the interior. At the same time, during the driving process of the car, the interior components will be subjected to certain mechanical stresses due to vibration, friction, etc., which requires the coating to have good wear resistance to maintain the texture and quality of the interior.

[0005] At present, some wear-resistant coatings available on the market can resist friction to a certain extent, but their anti-fingerprint effect is poor; and the wear resistance of some anti-fingerprint coatings is difficult to meet the actual use requirements. Traditional coating preparation technology mostly achieves the improvement of certain performances through simple physical mixing or single chemical modification, which has many limitations. For example, during the preparation process, the interface compatibility between the filler and the matrix is ​​poor, resulting in the overall unstable performance of the coating. When subjected to external forces, the filler is easy to fall off from the matrix, thereby reducing the wear resistance. Moreover, it is difficult for traditional coatings to take into account the coordinated optimization of multiple properties, and cannot meet the requirements of modern industry and life for high performance and multi-functional coatings.

[0006] In this context, developing a coating with excellent wear resistance and high anti-fingerprint performance and a preparation method thereof has become an important issue to be solved in the field of coating technology. The present invention is based on such a demand and aims to overcome the shortcomings of the prior art and provide a wear-resistant anti-fingerprint coating with better comprehensive performance and a preparation method thereof. Summary of the invention

[0007] The purpose of the present invention is to provide a wear-resistant and anti-fingerprint coating and a preparation method thereof, so as to solve the problems raised in the prior art.

[0008] To achieve the above object, the present invention provides the following technical solutions: A preparation method of a wear-resistant and fingerprint-resistant coating, comprising the following steps: S1: Add composite lignin lubricant to absolute ethanol, stir evenly to obtain a lignin stock solution; under stirring, add a modified cellulose nanocrystal suspension to the lignin stock solution, and perform vacuum distillation to obtain a lignin-cellulose composite filler; S2: Add lignin to N,N-dimethylformamide, stir evenly, add hexamethylene diisocyanate and dibutyltin dilaurate, heat to 90-95°C and react for 3-3.5 h, add polycarbonate polyol, and keep the temperature for reaction for 6-6.5 h to obtain lignin-modified polyurethane; add the lignin-cellulose composite filler to the lignin-modified polyurethane, stir evenly to obtain a wear-resistant and fingerprint-resistant coating; Further, the composite lignin lubricant is prepared from benzotriazole, tetrabutylphosphonium hydroxide and lignin; the modified cellulose nanocrystals are prepared from oxidized cellulose nanocrystals and octadecylamine.

[0009] Further, the preparation process of the modified cellulose nanocrystal suspension comprises the following steps: Add oxidized cellulose nanocrystals to deionized water, perform ultrasonic dispersion, add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir for 30-45 min, add N-hydroxysuccinimide, oscillate at room temperature for 1-1.5 h, add octadecylamine, perform ultrasonic treatment for 2-2.5 h, stir and react for 2-2.5 h, and wash the suspension by centrifugation with 0.1 M hydrochloric acid solution and absolute ethanol to obtain a modified cellulose nanocrystal suspension.

[0010] Further, in the preparation process of the modified cellulose nanocrystal suspension, the molar ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide:N-hydroxysuccinimide:octadecylamine is 1:1:1.

[0011] Further, the preparation process of the oxidized cellulose nanocrystals comprises the following steps: Step (1): Degum sisal fibers to obtain degummed sisal fibers; Step (2): Alkalize the degummed sisal fibers to obtain alkalized sisal fibers; Step (3): adding the alkali-treated sisal fiber to deionized water, ultrasonically dispersing, adding sodium bromide and 2,2,6,6-tetramethylpiperidinyl oxide, stirring at room temperature for 30-45 minutes, adding 12 wt% sodium hypochlorite aqueous solution under stirring, using a pH meter to detect the reaction system, and maintaining the pH of the reaction system at 10-10.5 by adding 1 wt% sodium hydroxide aqueous solution. When the reaction no longer consumes sodium hydroxide, adding anhydrous ethanol to terminate the reaction, centrifuging, collecting the precipitate, washing with deionized water until neutral, adding the precipitate to deionized water, ultrasonically treating, collecting the supernatant, centrifuging, collecting the precipitate, and freeze-drying to obtain oxidized cellulose nanocrystals.

[0012] Furthermore, in the preparation process of the oxidized cellulose nanocrystals, the mass ratio of alkali-treated sisal fiber: sodium bromide: 2,2,6,6-tetramethylpiperidinyl oxide is 1:0.2:0.02.

[0013] Furthermore, the preparation method of the composite lignin lubricant comprises the following steps: adding benzotriazole and tetrabutyl phosphine hydroxide into a reaction container, reacting at room temperature for 8-9 hours, extracting the aqueous phase, vacuum distilling, adding anhydrous magnesium sulfate to dry the organic phase, filtering, and obtaining an ionic liquid; heating the ionic liquid to 90-95° C., adding lignin, and stirring evenly to obtain a composite lignin lubricant.

[0014] Furthermore, in the preparation process of the composite lignin lubricant, the molar ratio of benzotriazole:tetrabutylphosphonium hydroxide is 1:1, and the amount of lignin added is 1-5wt% of the mass of the ionic liquid.

[0015] Furthermore, during the preparation of the lignin-cellulose composite filler, the concentration of the lignin stock solution was 8 mg / mL, the concentration of the modified cellulose nanocrystal suspension was 4-16 mg / mL, and the volume ratio of the modified cellulose nanocrystal suspension: lignin stock solution was 7:3.

[0016] Furthermore, in the preparation process of the lignin-modified polyurethane, the proportions of each component, calculated by mass, include: 4-6.3 parts of hexamethylene diisocyanate, 0.01-0.02 parts of dibutyltin dilaurate, 1.4-16.1 parts of polycarbonate polyol, and 1-2 parts of lignin; in the preparation process of the wear-resistant and anti-fingerprint coating, the mass ratio of lignin-cellulose composite filler: lignin-modified polyurethane is 3:(2-4).

[0017] Further, the degumming treatment of the sisal fiber includes the following steps: adding the sisal fiber into a 3wt% sodium hydroxide solution containing 2wt% sodium silicate, heating to 90 - 95°C and soaking for 3 - 3.5h, washing the fiber with deionized water until neutral, vacuum drying, adding the fiber into a 3wt% ethylenediaminetetraacetic acid solution, with a material - liquid ratio of 1:40, heating to 30 - 35°C and reacting for 1 - 1.5h, washing the fiber with deionized water until neutral, vacuum drying, adding the fiber into a mixed solution of 20g / L sodium hydroxide and 22.5mL / L hydrogen peroxide, heating to 95 - 96°C and reacting for 3.5 - 4h, with a material - liquid ratio of 1:50, washing, and vacuum drying to obtain degummed sisal fiber.

[0018] Further, the alkali treatment of the degummed sisal fiber includes the following steps: grinding the degummed sisal fiber and adding it into a 15% sodium hydroxide solution, heating to 60 - 65°C and reacting for 4 - 4.5h, with a material - liquid ratio of 1:50, washing, drying, placing the fiber in a dimethyl sulfoxide solution, heating to 70 - 75°C and reacting for 3 - 3.5h, with a material - liquid ratio of 1:20, washing, and drying to obtain alkali - treated sisal fiber.

[0019] Further, the preparation method of the lignin includes the following steps: adding poplar wood chips into an ethanol - water solution, stirring evenly, adding a 2wt% sulfuric acid solution, heating to 180 - 185°C and reacting for 2 - 2.5h, cooling to room temperature, filtering, vacuum concentrating, adding water for precipitation separation, and vacuum drying to obtain lignin.

[0020] Further, in the preparation process of the lignin, the volume ratio of ethanol to water in the ethanol - water solution is 7:3.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Through TEMPO oxidation and octadecylamine amidation, the present invention introduces long - chain alkyl groups on the surface of cellulose nanocrystals to enhance the interfacial compatibility with the hydrophobic polyurethane matrix, and prepares modified cellulose nanocrystals, which significantly improve the mechanical strength and hardness of the coatings prepared from the coatings. The high specific surface area and rigid structure of the modified cellulose nanocrystals form a reinforcing network in the polyurethane matrix, effectively dispersing external stress and reducing wear during the friction process. The ionic liquid formed by benzotriazole and tetrabutylphosphonium hydroxide in the synergistic composite lignin lubricant can form a lubricating layer on the surface of the coating, reduce the friction coefficient, further reduce wear, and enhance the wear - resistant performance of the coating.

[0022] 2. The present invention prepares a lignin - cellulose composite filler by co - assembling the modified cellulose nanocrystals and the composite lignin lubricant. The hydrophobic layer formed on the surface of the octadecylamine - modified cellulose nanocrystals reduces the adhesion of grease and moisture in fingerprints. The nano - scale rough surface of the composite filler repels pollutants through the "lotus effect", realizing the self - cleaning function and achieving high - efficiency anti - fingerprint performance.

[0023] 3. The present invention further modifies polyurethane with lignin, greatly improving the dispersion performance of lignin-cellulose composite fillers in lignin-modified polyurethane. The lignin-modified polyurethane prepared by the reaction of the hydroxyl group of lignin with isocyanate is different from the physical blending modification of traditional lignin and polyurethane. The cross-linked network of the lignin-modified polyurethane is denser at a higher level, making the finally prepared coating have excellent wear resistance and anti-fingerprint performance. Detailed implementation manners

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0025] In the following embodiments, the specifications of polycarbonate polyol are: Mn = 2000; the specifications of polyurethane are: Mn = 2000; and the rest of the raw materials are commercially available.

[0026] The preparation method of oxidized cellulose nanocrystals includes the following steps: Step (1): Add 2 g of sisal fibers to a 3 wt% sodium hydroxide solution containing 2 wt% sodium silicate, heat to 90 °C and soak for 3 h, wash the fibers with deionized water until neutral, and dry them under vacuum. Add the fibers to a 3 wt% ethylenediaminetetraacetic acid solution with a material-liquid ratio of 1:40, heat to 30 - 35 °C and react for 1 h, wash the fibers with deionized water until neutral, and dry them under vacuum. Add the fibers to a mixed solution of 20 g / L sodium hydroxide and 22.5 mL / L hydrogen peroxide, heat to 95 - 96 °C and react for 3.5 h with a material-liquid ratio of 1:50, wash, and dry under vacuum to obtain degummed sisal fibers.

[0027] Step (2): Grind the degummed sisal fibers and add them to a 15% sodium hydroxide solution, heat to 60 °C and react for 4 h with a material-liquid ratio of 1:50, wash, and dry. Place the fibers in a dimethyl sulfoxide solution, heat to 70 °C and react for 3 h with a material-liquid ratio of 1:20, wash, and dry to obtain alkali-treated sisal fibers; Step (3): Add 1 g of alkali-treated sisal fiber into deionized water, ultrasonically disperse it, add 0.2 g of sodium bromide and 0.02 g of 2,2,6,6-tetramethylpiperidine oxide, stir at room temperature for 30 min, add 12 wt% sodium hypochlorite aqueous solution under stirring, detect the reaction system with a pH meter, maintain the pH of the reaction system at 10 by adding 1 wt% sodium hydroxide aqueous solution, when the reaction no longer consumes sodium hydroxide, add anhydrous ethanol to terminate the reaction, centrifuge, collect the precipitate, wash it with deionized water until neutral, add the precipitate into deionized water, ultrasonically treat it, collect the supernatant, centrifuge, collect the precipitate, and freeze-dry to obtain oxidized cellulose nanocrystals.

[0028] The preparation method of lignin comprises the following steps: Add 2 g of poplar wood chips into an ethanol aqueous solution (volume ratio of ethanol to water is 7:3), stir evenly, add 2 wt% sulfuric acid solution, heat to 180 °C and react for 2 h, cool to room temperature, filter, vacuum concentrate, add water for precipitation separation, and vacuum dry to obtain lignin.

[0029] Example 1: The preparation method of a wear-resistant and fingerprint-resistant coating comprises the following steps: S1: Add 1 mol of benzotriazole and 1 mol of tetrabutylphosphonium hydroxide into a reaction vessel, react at room temperature for 8 h, extract the aqueous phase, vacuum distill, add anhydrous magnesium sulfate to dry the organic phase, filter to obtain an ionic liquid; Heat the ionic liquid to 90 °C, add 1 wt% lignin, and stir evenly to obtain a composite lignin lubricant; S2: Add oxidized cellulose nanocrystals into deionized water, ultrasonically disperse them, add 1 mol of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir for 30 min, add 1 mol of N-hydroxysuccinimide, oscillate at room temperature for 1 h, add 1 mol of octadecylamine, ultrasonically treat for 2 h, stir and react for 2 h, wash the suspension by centrifugation with 0.1 M hydrochloric acid solution and anhydrous ethanol to obtain a modified cellulose nanocrystal suspension; S3: Add the composite lignin lubricant into anhydrous ethanol, stir evenly to obtain a 8 mg / mL lignin stock solution; Under stirring, add the 4 mg / mL modified cellulose nanocrystal suspension into the lignin stock solution, and vacuum distill to obtain a lignin-cellulose composite filler; The volume ratio of the modified cellulose nanocrystal suspension to the lignin stock solution is 7:3; S4: Add 1 part of lignin into N,N-dimethylformamide, stir evenly, add 6.3 parts of hexamethylene diisocyanate and 0.01 part of dibutyltin dilaurate, heat to 90 °C and react for 3 h, add 16.1 parts of polycarbonate polyol, keep warm and react for 6 h to obtain lignin-modified polyurethane; Add 3 g of the lignin-cellulose composite filler into 4 g of the lignin-modified polyurethane, stir evenly to obtain a wear-resistant and fingerprint-resistant coating.

[0030] Example 2: A preparation method of a wear-resistant and fingerprint-resistant coating, comprising the following steps: S1: Add 1 mol of benzotriazole and 1 mol of tetrabutylphosphonium hydroxide to a reaction vessel, react at room temperature for 8 h, extract the aqueous phase, perform vacuum distillation, add anhydrous magnesium sulfate to dry the organic phase, filter to obtain an ionic liquid; heat the ionic liquid to 90 °C, add 3 wt% lignin, and stir evenly to obtain a composite lignin lubricant; S2: Add oxidized cellulose nanocrystals to deionized water, ultrasonically disperse, add 1 mol of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir for 30 min, add 1 mol of N-hydroxysuccinimide, oscillate at room temperature for 1 h, add 1 mol of octadecylamine, ultrasonically treat for 2 h, stir and react for 2 h, and wash the suspension by centrifugation using 0.1 M hydrochloric acid solution and absolute ethanol to obtain a modified cellulose nanocrystal suspension; S3: Add the composite lignin lubricant to absolute ethanol, stir evenly to obtain an 8 mg / mL lignin stock solution; under stirring, add the 8 mg / mL modified cellulose nanocrystal suspension to the lignin stock solution, perform vacuum distillation to obtain a lignin-cellulose composite filler; the volume ratio of the modified cellulose nanocrystal suspension to the lignin stock solution is 7:3; S4: Add 1 part of lignin to N,N-dimethylformamide, stir evenly, add 5.7 parts of hexamethylene diisocyanate and 0.01 part of dibutyltin dilaurate, heat to 90 °C and react for 3 h, add 13.2 parts of polycarbonate polyol, keep the temperature and react for 6 h to obtain lignin-modified polyurethane; add 3 g of the lignin-cellulose composite filler to 4 g of the lignin-modified polyurethane, stir evenly to obtain a wear-resistant and fingerprint-resistant coating.

[0031] Example 3: A preparation method of a wear-resistant and fingerprint-resistant coating, comprising the following steps: S1: Add 1 mol of benzotriazole and 1 mol of tetrabutylphosphonium hydroxide to a reaction vessel, react at room temperature for 8 h, extract the aqueous phase, perform vacuum distillation, add anhydrous magnesium sulfate to dry the organic phase, filter to obtain an ionic liquid; heat the ionic liquid to 90 °C, add 5 wt% lignin, and stir evenly to obtain a composite lignin lubricant; S2: Add oxidized cellulose nanocrystals to deionized water, ultrasonically disperse, add 1 mol of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir for 30 min, add 1 mol of N-hydroxysuccinimide, oscillate at room temperature for 1 h, add 1 mol of octadecylamine, ultrasonically treat for 2 h, stir and react for 2 h, and wash the suspension by centrifugation using 0.1 M hydrochloric acid solution and absolute ethanol to obtain a modified cellulose nanocrystal suspension; S3: Add the composite lignin lubricant into absolute ethanol, stir evenly to obtain a lignin stock solution with a concentration of 8 mg / mL; under stirring, add the 8 mg / mL modified cellulose nanocrystal suspension into the lignin stock solution, and perform vacuum distillation to obtain a lignin-cellulose composite filler; the volume ratio of the modified cellulose nanocrystal suspension to the lignin stock solution is 7:3; S4: Add 1 part of lignin into N,N-dimethylformamide, stir evenly, add 4.6 parts of hexamethylene diisocyanate and 0.01 part of dibutyltin dilaurate, heat to 90 °C and react for 3 h, then add 4.3 parts of polycarbonate polyol, keep the temperature and react for 6 h to obtain lignin-modified polyurethane; add 3 g of the lignin-cellulose composite filler into 4 g of the lignin-modified polyurethane, stir evenly to obtain the wear-resistant and fingerprint-resistant coating.

[0032] Example 4: A preparation method of a wear-resistant and fingerprint-resistant coating, comprising the following steps: S1: Add 1 mol of benzotriazole and 1 mol of tetrabutylphosphonium hydroxide into a reaction vessel, react at room temperature for 8 h, extract the aqueous phase, perform vacuum distillation, add anhydrous magnesium sulfate to dry the organic phase, filter to obtain an ionic liquid; heat the ionic liquid to 90 °C, add 5 wt% of lignin, stir evenly to obtain a composite lignin lubricant; S2: Add oxidized cellulose nanocrystals into deionized water, perform ultrasonic dispersion, add 1 mol of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir for 30 min, add 1 mol of N-hydroxysuccinimide, oscillate at room temperature for 1 h, add 1 mol of octadecylamine, perform ultrasonic treatment for 2 h, stir and react for 2 h, and use 0.1 M hydrochloric acid solution and absolute ethanol to wash the suspension by centrifugation to obtain a modified cellulose nanocrystal suspension; S3: Add the composite lignin lubricant into absolute ethanol, stir evenly to obtain a lignin stock solution with a concentration of 8 mg / mL; under stirring, add the 16 mg / mL modified cellulose nanocrystal suspension into the lignin stock solution, and perform vacuum distillation to obtain a lignin-cellulose composite filler; the volume ratio of the modified cellulose nanocrystal suspension to the lignin stock solution is 7:3; S4: Add 1 part of lignin into N,N-dimethylformamide, stir evenly, add 1.4 parts of hexamethylene diisocyanate and 0.01 part of dibutyltin dilaurate, heat to 90 °C and react for 3 h, then add 4.2 parts of polycarbonate polyol, keep the temperature and react for 6 h to obtain lignin-modified polyurethane; add 3 g of the lignin-cellulose composite filler into 2 g of the lignin-modified polyurethane, stir evenly to obtain the wear-resistant and fingerprint-resistant coating.

[0033] Comparative Example 1: A preparation method of a wear-resistant and fingerprint-resistant coating, comprising the following steps: S1: Add cellulose nanocrystals oxide to deionized water, disperse ultrasonically, add 1 mol of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir for 30 min, add 1 mol of N-hydroxysuccinimide, oscillate at room temperature for 1 h, add 1 mol of octadecylamine, perform ultrasonic treatment for 2 h, stir and react for 2 h, use 0.1 M hydrochloric acid solution and absolute ethanol to wash the suspension by centrifugation to obtain a modified cellulose nanocrystal suspension; S2: Add 1 part of lignin to N,N-dimethylformamide, stir evenly, add 6.3 parts of hexamethylene diisocyanate and 0.01 part of dibutyltin dilaurate, heat to 90 °C and react for 3 h, add 16.1 parts of polycarbonate polyol, keep warm and react for 6 h to obtain lignin-modified polyurethane; add 3 g of the modified cellulose nanocrystal suspension to 4 g of lignin-modified polyurethane, stir evenly to obtain a wear-resistant and fingerprint-resistant coating.

[0034] Comparative Example 2: A preparation method of a wear-resistant and fingerprint-resistant coating, comprising the following steps: S1: Add 1 mol of benzotriazole and 1 mol of tetrabutylphosphonium hydroxide to a reaction vessel, react at room temperature for 8 h, extract the aqueous phase, perform vacuum distillation, add anhydrous magnesium sulfate to dry the organic phase, filter to obtain an ionic liquid; heat the ionic liquid to 90 °C, add 1 wt% of lignin, stir evenly to obtain a composite lignin lubricant; S2: Add the composite lignin lubricant to absolute ethanol, stir evenly to obtain a 8 mg / mL lignin stock solution; under stirring, add a 4 mg / mL aqueous suspension of cellulose nanocrystals oxide to the lignin stock solution, perform vacuum distillation to obtain a lignin-cellulose composite filler; wherein the volume ratio of the aqueous suspension of cellulose nanocrystals oxide to the lignin stock solution is 7:3; S3: Add 1 part of lignin to N,N-dimethylformamide, stir evenly, add 6.3 parts of hexamethylene diisocyanate and 0.01 part of dibutyltin dilaurate, heat to 90 °C and react for 3 h, add 16.1 parts of polycarbonate polyol, keep warm and react for 6 h to obtain lignin-modified polyurethane; add 3 g of the lignin-cellulose composite filler to 4 g of lignin-modified polyurethane, stir evenly to obtain a wear-resistant and fingerprint-resistant coating.

[0035] Comparative Example 3: A preparation method of a wear-resistant and fingerprint-resistant coating, comprising the following steps: S1: Add 1 mol of benzotriazole and 1 mol of tetrabutylphosphonium hydroxide to a reaction vessel, react at room temperature for 8 h, extract the aqueous phase, perform vacuum distillation, add anhydrous magnesium sulfate to dry the organic phase, filter to obtain an ionic liquid; heat the ionic liquid to 90 °C, add 1 wt% of lignin, stir evenly to obtain a composite lignin lubricant; S2: Add cellulose nanocrystals oxide into deionized water, disperse it by ultrasonic wave, add 1 mol of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, stir for 30 min, add 1 mol of N-hydroxysuccinimide, oscillate at room temperature for 1 h, add 1 mol of octadecylamine, treat it by ultrasonic wave for 2 h, stir and react for 2 h, use 0.1 M hydrochloric acid solution and absolute ethanol to wash the suspension by centrifugation to obtain a modified cellulose nanocrystal suspension; S3: Add the composite lignin lubricant into absolute ethanol, stir evenly to obtain a lignin stock solution with a concentration of 8 mg / mL; under stirring, add the 4 mg / mL modified cellulose nanocrystal suspension into the lignin stock solution, and perform vacuum distillation to obtain a lignin-cellulose composite filler; the volume ratio of the modified cellulose nanocrystal suspension to the lignin stock solution is 7:3; S4: Add 1 part of lignin into 4 g of polyurethane, stir evenly to obtain lignin-modified polyurethane; add 3 g of the lignin-cellulose composite filler into 4 g of the lignin-modified polyurethane, stir evenly to obtain a wear-resistant and fingerprint-resistant coating.

[0036] Experiment: Spin-coat the wear-resistant and fingerprint-resistant coatings prepared in the above examples and comparative examples on the surface of a 304 stainless steel plate with a coating thickness of 20 μm, and perform tests after drying and curing.

[0037] Fingerprint resistance performance test: Press the fingerprint on the coating surface for 5 s to simulate fingerprint contamination, sprinkle an excessive amount of zinc oxide powder on the surface to cover it, gently brush to remove the excess powder, observe the distribution of the residual powder under a microscope, and quantify the proportion of the fingerprint area.

[0038] Wear resistance performance test: Use a diamond indenter to scratch on the coating surface with a load of 50 N, sweep the cross-section of the wear track, and calculate the volume loss. Use a friction and wear testing machine to test the friction coefficient with a load of 2 N, a frequency of 2 Hz, a friction time of 20 min, and the friction ball is a φ6 mm tungsten carbide ball.

[0039] The experimental results are shown in Table 1 below.

[0040] Table 1 Performance test data table of wear-resistant and fingerprint-resistant coatings Conclusion: The wear-resistant and fingerprint-resistant coating prepared by the present invention has excellent fingerprint resistance and wear resistance.

[0041] In Comparative Example 1, the composite lignin lubricant was not added, resulting in a decrease in fingerprint resistance and wear resistance.

[0042] In Comparative Example 2, oxidized cellulose nanocrystals were used, resulting in a decrease in fingerprint resistance and wear resistance.

[0043] In Comparative Example 3, physical blending of lignin was used to modify polyurethane, resulting in a decrease in fingerprint resistance and wear resistance.

[0044] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention.

Claims

1. A method for preparing a wear-resistant and anti-fingerprint coating, characterized in that: The following steps are involved: S1: adding the composite lignin lubricant to anhydrous ethanol and stirring evenly to obtain a lignin stock solution; under stirring, adding the modified cellulose nanocrystal suspension to the lignin stock solution, and vacuum distilling to obtain a lignin-cellulose composite filler; S2: adding lignin to N,N-dimethylformamide, stirring evenly, adding hexamethylene diisocyanate and dibutyltin dilaurate, heating to 90-95°C for reaction for 3-3.5h, adding polycarbonate polyol, keeping the temperature for reaction for 6-6.5h, and obtaining lignin-modified polyurethane; adding lignin-cellulose composite filler to lignin-modified polyurethane, stirring evenly, and obtaining wear-resistant and anti-fingerprint coating; The composite lignin lubricant is prepared from benzotriazole, tetrabutyl phosphine hydroxide and wood; and the modified cellulose nanocrystal is prepared from oxidized cellulose nanocrystal and octadecylamine.

2. The method for preparing a wear-resistant and anti-fingerprint coating according to claim 1, characterized in that: The preparation process of the modified cellulose nanocrystal suspension comprises the following steps: adding oxidized cellulose nanocrystals into deionized water, ultrasonically dispersing, adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stirring for 30-45 minutes, adding N-hydroxysuccinimide, oscillating at room temperature for 1-1.5 hours, adding octadecylamine, ultrasonically treating for 2-2.5 hours, stirring for reaction for 2-2.5 hours, and washing the suspension by centrifugation using a 0.1M hydrochloric acid solution and anhydrous ethanol to obtain a modified cellulose nanocrystal suspension.

3. The method for preparing a wear-resistant and anti-fingerprint coating according to claim 2, characterized in that: In the preparation process of the modified cellulose nanocrystal suspension, the molar ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide:N-hydroxysuccinimide:octadecylamine is 1:1:

1.

4. The method for preparing a wear-resistant and anti-fingerprint coating according to claim 2, characterized in that: The preparation process of the oxidized cellulose nanocrystals comprises the following steps: step (1): degumming sisal fibers to obtain degummed sisal fibers; Step (2): treating the degummed sisal fiber with alkali to obtain alkali-treated sisal fiber; Step (3): adding the alkali-treated sisal fiber to deionized water, ultrasonically dispersing, adding sodium bromide and 2,2,6,6-tetramethylpiperidinyl oxide, stirring at room temperature for 30-45 minutes, adding 12 wt% sodium hypochlorite aqueous solution under stirring, using a pH meter to detect the reaction system, and maintaining the pH of the reaction system at 10-10.5 by adding 1 wt% sodium hydroxide aqueous solution. When the reaction no longer consumes sodium hydroxide, adding anhydrous ethanol to terminate the reaction, centrifuging, collecting the precipitate, washing with deionized water until neutral, adding the precipitate to deionized water, ultrasonically treating, collecting the supernatant, centrifuging, collecting the precipitate, and freeze-drying to obtain oxidized cellulose nanocrystals.

5. The method for preparing a wear-resistant and anti-fingerprint coating according to claim 4, characterized in that: During the preparation of oxidized cellulose nanocrystals, the mass ratio of alkali-treated sisal fiber: sodium bromide: 2,2,6,6-tetramethylpiperidinyl oxide was 1:0.2:0.

02.

6. The method for preparing a wear-resistant and anti-fingerprint coating according to claim 1, characterized in that: The preparation method of the composite lignin lubricant comprises the following steps: adding benzotriazole and tetrabutyl phosphine hydroxide into a reaction container, reacting at room temperature for 8-9 hours, extracting a water phase, vacuum distilling, adding anhydrous magnesium sulfate to dry an organic phase, filtering to obtain an ionic liquid; heating the ionic liquid to 90-95° C., adding lignin, stirring evenly to obtain a composite lignin lubricant.

7. The method for preparing a wear-resistant and anti-fingerprint coating according to claim 6, characterized in that: During the preparation of the composite lignin lubricant, the molar ratio of benzotriazole to tetrabutylphosphonium hydroxide is 1:1, and the amount of lignin added is 1-5wt% of the mass of the ionic liquid.

8. The method for preparing a wear-resistant and anti-fingerprint coating according to claim 1, characterized in that: During the preparation of the lignin-cellulose composite filler, the concentration of the lignin stock solution was 8 mg / mL, the concentration of the modified cellulose nanocrystal suspension was 4-16 mg / mL, and the volume ratio of the modified cellulose nanocrystal suspension: lignin stock solution was 7:

3.

9. The method for preparing a wear-resistant and anti-fingerprint coating according to claim 1, characterized in that: The proportions of various components in the preparation process of lignin-modified polyurethane are calculated by mass, including: 4-6.3 parts of hexamethylene diisocyanate, 0.01-0.02 parts of dibutyltin dilaurate, 1.4-16.1 parts of polycarbonate polyol, and 1-2 parts of lignin; in the preparation process of wear-resistant and anti-fingerprint coating, the mass ratio of lignin-cellulose composite filler: lignin-modified polyurethane is 3:(2-4).

10. The wear-resistant and anti-fingerprint coating prepared according to the method for preparing the wear-resistant and anti-fingerprint coating according to any one of claims 1 to 9.

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