An agricultural straw based lignocellulosic-polymer based lubricating material, its method of manufacture and use and a lubricant product

Abstract

The application discloses a kind of lignocellulose-polymer based lubricating material based on agricultural straw and its preparation method and application and lubricant product, belong to biomass high-value utilization and lubricating material technical field.The method includes: after agricultural straw powder is pretreated by lye, bleaching, using the deep eutectic solvent formed by citric acid-choline chloride-water system is handled, then obtains lignocellulose slurry by mechanical crushing;Subsequently continue to add anhydrous ethanol, polytetrafluoroethylene wax and cetyltrimethylammonium bromide and carry out collaborative modification reaction, after drying and grinding, obtain final product.The present application uses waste agricultural straw as raw material, and successfully prepares lubricating additive with good dispersion stability in oily medium and excellent friction and wear resistance by green process, realizes the high-value utilization of agricultural waste.It can be used as high-performance additive in lubricating oil or grease, the friction coefficient can be greatly reduced, and good application prospect is shown.

Description

Technical Field

[0001] This invention relates to the field of biomass high-value utilization and lubricating materials technology, and in particular to a lignocellulose-polymer-based lubricating material based on agricultural straw, its preparation method and application, as well as lubricant products. Background Technology

[0002] Agricultural straw, as a renewable lignocellulose resource with a huge yield and wide distribution, has an annual global production of billions of tons. However, current methods for treating and utilizing this type of agricultural waste mainly rely on open burning, simple landfilling, or low-value return to the field. These extensive treatment methods not only result in a huge waste of valuable components such as cellulose, hemicellulose, and lignin in biomass resources, but also release large amounts of particulate matter and harmful gases from open burning, exacerbating air pollution; while long-term single-use return to the field may disrupt the soil microbial balance, bringing significant ecological and environmental pressure. Therefore, developing new efficient, green, and high-value utilization pathways for agricultural straw, transforming it from an environmental burden into a precursor for functional materials, has become a core issue of common concern in the fields of materials science, environmental engineering, and circular economy. Nano-lignocellulose, due to its unique nanoscale structure, excellent renewability, complete biodegradability, high specific surface area, and superior mechanical properties, has gained widespread favor in the field of functional materials design in recent years. However, when attempting to extend nano-lignocellulose to the important industrial field of lubrication engineering, its inherent chemical properties become a major obstacle. The surface of nanocellulose is rich in active hydroxyl groups, giving it extremely strong hydrophilicity. This characteristic leads to severe self-agglomeration and sedimentation of cellulose in non-polar or weakly polar media, especially in typical lubricating oil base oils such as mineral oils and synthetic oils, resulting in extremely poor dispersion stability. This inherent hydrophilic-hydrophobic contradiction severely limits the practical application of nanocellulose as a high-performance additive in lubrication systems, preventing it from fully realizing its potential contribution to friction reduction and anti-wear properties due to its high mechanical strength.

[0003] Existing technologies have explored various modification strategies. Common physical blending methods struggle to break the strong hydrogen bond network between nanocellulose cells, resulting in limited effectiveness. Traditional chemical modifications such as esterification, etherification, or silanization, while partially reducing surface polarity, often involve toxic organic solvents, complex multi-step reactions, and lengthy purification processes, leading to high costs and non-compliance with green chemistry principles. More importantly, there are few reported complete technical solutions for preparing high-performance additives directly usable in lubricants using low-cost agricultural waste (such as corn stalks) as the sole raw material through an integrated green process. Most research remains at the laboratory-scale modification level of high-purity cellulose or commercial microcrystalline cellulose, lacking a cost-effective and integrated technology across the entire chain from "waste" to "functional material," failing to meet the dual demands of cost control and environmental friendliness for large-scale industrial applications. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a lignocellulose-polymer-based lubricating material based on agricultural straw, its preparation method, and its application. This invention uses agricultural straw as raw material and employs a green and efficient process to prepare a high-performance lignocellulose-polymer-based lubricating material. The resulting lignocellulose-polymer-based lubricating material based on agricultural straw exhibits excellent friction-reducing and wear-resistant properties, achieving high-value utilization of agricultural waste.

[0005] A further technical problem to be solved by the present invention is to provide a lubricant product using the above-mentioned lignocellulose-polymer-based lubricating material based on agricultural straw.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a lignocellulose-polymer-based lubricating material based on agricultural straw, comprising the following steps:

[0008] Step 1: Pre-treat the dried and pulverized agricultural straw with alkaline solution to obtain solid material A;

[0009] Step 2: Bleaching solid material A to obtain bleached lignocellulose solid material B;

[0010] Step 3: Mix 72-108 parts of citric acid, 24-36 parts of choline chloride and 24-36 parts of water at 75-85℃ to prepare H-DES (deep eutectic solvent); use the prepared H-DES to treat the bleached lignocellulose solid material B obtained in Step 2 to obtain lignocellulose pulp rich in micro- and nano-sized lignocellulose;

[0011] Step 4: Add 60-90 parts anhydrous ethanol, 0.8-1.2 parts polytetrafluoroethylene wax, and 1.2-1.8 parts hexadecyltrimethylammonium bromide to the lignocellulose slurry obtained in Step 3, and then mechanically crush it for 8-12 minutes to obtain a mixed system; then react the mixed system in a sealed container at 75-85℃ for 2.5-3.5 hours; after the reaction is completed, filter and wash the mixed slurry obtained from the reaction, and then dry it at 55-65℃; process the dried product into powder to obtain a lignocellulose-polymer-based lubricating material based on agricultural straw.

[0012] Specifically, step 1 involves dispersing 8-12 parts of dried and pulverized agricultural straw in 240-360 parts of a NaOH aqueous solution with a mass fraction of 4.0%-6.0%, reacting at 75-85°C for 3.5-4.5 hours, filtering and washing with water until neutral to obtain solid material A.

[0013] Specifically, step 2 involves dispersing the solid material A obtained in step 1 in 200-300 parts of water, adding 16-24 parts of sodium chlorite and 4-6 parts of acetic acid, reacting at 90-100℃ for 3.5-4.5 hours, filtering and washing with water until neutral to obtain bleached lignocellulose solid material B.

[0014] In step 3, the specific operation of treating the bleached lignocellulose solid material B obtained in step 2 with the prepared H-DES to obtain lignocellulose pulp is as follows:

[0015] H-DES and bleached lignocellulose solid material B were mixed and reacted at 125~135℃ for 2.5~3.5 hours to obtain a viscous liquid;

[0016] Dilute the viscous liquid with 160-240 parts water;

[0017] The diluted viscous liquid was filtered and washed with water to obtain solid material C;

[0018] Disperse all solid material C in 120-180 parts of water and mechanically crush for 50-70 minutes to obtain lignocellulose pulp.

[0019] In step 1, the agricultural straw is one or more of the following: corn straw, rice straw, wheat straw, barley straw, and sorghum straw.

[0020] The preparation method of the lignocellulose-polymer-based lubricating material based on agricultural straw further includes the following steps:

[0021] Step 5: Modify the lignocellulose-polymer-based lubricant material based on agricultural straw; specifically, disperse 0.8-1.2 parts of the lignocellulose-polymer-based lubricant material obtained in Step 4 and 0.8-1.2 parts of dopamine hydrochloride in 160-240 parts of Tris buffer solution, stir continuously at room temperature for 22-26 hours, and obtain the PDA-modified lignocellulose-polymer-based lubricant material after centrifugation, washing, drying, crushing and grinding.

[0022] Preferably, the Tris buffer solution in step 5 is prepared as follows: weigh 1.2 to 1.3 parts of Tris base and dissolve it in about 800 to 900 parts of water, adjust the pH to 8.5 with 1M hydrochloric acid, and finally bring the volume to 1.0L.

[0023] A lignocellulose-polymer-based lubricating material based on agricultural straw is prepared using the aforementioned method for preparing lignocellulose-polymer-based lubricating materials based on agricultural straw. In the lignocellulose-polymer-based lubricating material based on agricultural straw, nano-sized polytetrafluoroethylene wax particles or thin-layer coatings are uniformly attached to the fiber surface. At the same time, the anchoring effect of hexadecyltrimethylammonium bromide effectively shields the interhydroxyl hydrogen bonds, reduces fiber agglomeration, and forms a hybrid structure of fiber skeleton and lubricating component embellishment.

[0024] A lignocellulose-polymer-based lubricating material based on agricultural straw is prepared by the above-mentioned preparation method of lignocellulose-polymer-based lubricating material based on agricultural straw; the surface of the lignocellulose-polymer-based lubricating material based on agricultural straw is coated with a continuous and uniform polydopamine film.

[0025] The above-mentioned lignocellulose-polymer-based lubricating materials based on agricultural straw are used as additives in lubricating oils or greases.

[0026] A lubricant product comprising a lubricating phase and the aforementioned lignocellulose-polymer-based lubricating material based on agricultural straw, wherein the amount of the lignocellulose-polymer-based lubricating material based on agricultural straw added is 0.25% to 1.5% of the mass of the lubricating phase.

[0027] The beneficial effects of this invention are as follows:

[0028] (1) Green raw materials and low cost: This invention uses waste agricultural straw as raw material, realizing "turning waste into treasure", which is in line with the sustainable development strategy. The raw materials are widely available and the cost is extremely low.

[0029] (2) High efficiency and environmentally friendly: The present invention adopts deep eutectic solvent pretreatment, which is mild, green and efficient, avoiding the environmental pollution problems of traditional strong acid and strong alkali treatment.

[0030] (3) Excellent product performance: This invention further solves the problem of dispersion stability of nanocellulose in the oil phase through synergistic surface modification of hexadecyltrimethylammonium bromide, polytetrafluoroethylene wax and PDA. The prepared lubricating additive can be stably dispersed in aqueous and oily media and exhibits excellent friction reduction and anti-wear properties, with a significant reduction in the coefficient of friction.

[0031] (4) Broad application prospects: The lignocellulose-polymer-based lubricating material based on agricultural straw of the present invention can be widely used as a high-performance additive in various lubricating oils and greases, providing a new technical path for the development of environmentally friendly bio-based lubricating products. Attached Figure Description

[0032] Figure 1These are SEM images of the lignocellulose (CLC) prepared in step 3 of Examples 1 to 4 of the present invention; wherein CLC-1 is the lignocellulose prepared in Example 1, CLC-2 is the lignocellulose prepared in Example 2, CLC-3 is the lignocellulose prepared in Example 3, and CLC-4 is the lignocellulose prepared in Example 4.

[0033] Figure 2 These are SEM images of the lignocellulose-polymer-based lubricating materials (CLC / PFW-CTAB) prepared in step 4 of Examples 1 to 4 of the present invention; wherein CLC / PFW-CTAB-1 is the lignocellulose-polymer-based lubricating material prepared in Example 1, CLC / PFW-CTAB-2 is the lignocellulose-polymer-based lubricating material prepared in Example 2, CLC / PFW-CTAB-3 is the lignocellulose-polymer-based lubricating material prepared in Example 3, and CLC / PFW-CTAB-4 is the lignocellulose-polymer-based lubricating material prepared in Example 4.

[0034] Figure 3 These are SEM images of the PDA-modified lignocellulose-polymer-based lubricating materials (CLC / PFW-CTAB-PDA) prepared in step 5 of Examples 1 to 4 of the present invention; wherein PDA modification-1 is the CLC / PFW-CTAB-PDA prepared in Example 1, PDA modification-2 is the CLC / PFW-CTAB-PDA prepared in Example 2, PDA modification-3 is the CLC / PFW-CTAB-PDA prepared in Example 3, and PDA modification-4 is the CLC / PFW-CTAB-PDA prepared in Example 4.

[0035] Figure 4 This is a graph showing the friction coefficient data of the lignocellulose (CLC) prepared in step 3 of Examples 1 to 4 of the present invention, directly dispersed in sunflower oil.

[0036] Figure 5 This is a graph showing the friction coefficient data of commercially purchased cellulose directly dispersed in sunflower oil in Comparative Example 1.

[0037] Figure 6 This is a graph showing the friction coefficient data of the lignocellulose-polymer-based lubricating material (CLC / PFW-CTAB) prepared in step 4 of Examples 1 to 4 of the present invention, directly dispersed in sunflower oil.

[0038] Figure 7This is a graph showing the friction coefficient data of the PDA-modified lignocellulose-polymer-based lubricating material (CLC / PFW-CTAB-PDA) prepared in step 5 of Examples 1 to 4 of the present invention, directly dispersed in sunflower oil.

[0039] Figure 8 This is a graph showing the friction coefficient of the lignocellulose-polymer-based lubricant (CLC / PFW-CTAB) prepared in step 4 of Example 1 of the present invention, directly dispersed in a PEG aqueous solution.

[0040] Figure 9 This is a graph showing the average friction coefficient of the lignocellulose-polymer-based lubricant (CLC / PFW-CTAB) prepared in step 4 of Example 1 of the present invention, directly dispersed in a PEG aqueous solution.

[0041] Figure 10 The images show the wear morphology of the lignocellulose (CLC) prepared in step 3 of Example 1 of this invention, the lignocellulose-polymer-based lubricant (CLC / PFW-CTAB) prepared in step 4, the PDA-modified lignocellulose-polymer-based lubricant (CLC / PFW-CTAB-PDA) prepared in step 5, and commercially available cellulose purchased directly on the surface of a steel disc.

[0042] Figure 11 This is a summary chart of the general friction coefficient ranges for various commonly used lubricating materials. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0044] Unless otherwise specified, the raw materials and equipment used in the following examples are all commercially available.

[0045] All parts in the following examples are by weight.

[0046] Example 1

[0047] Part One:

[0048] A method for preparing a lignocellulose-polymer-based lubricating material based on agricultural straw includes the following steps:

[0049] Step 1: Disperse 10 parts of dried and pulverized corn stalks in 300 parts of 5.0% NaOH aqueous solution, react at 80℃ for 4 hours, filter and wash with water until neutral to obtain solid material A;

[0050] Step 2: Disperse solid material A in 250 parts of water, add 20 parts of sodium chlorite and 5 parts of acetic acid, react at 95°C for 4 hours, filter and wash to obtain bleached lignocellulose solid material B;

[0051] Step 3: Prepare H-DES by mixing 90 parts citric acid, 30 parts choline chloride, and 30 parts water at 80°C; use this H-DES to treat all solid materials B; specifically, first mix H-DES and bleached lignocellulose solid material B, then react at 130°C for 3 hours, dilute the resulting viscous liquid with 200 parts water, filter after dilution, and wash the filter residue three times with water to obtain solid material C; disperse solid material C in 150 parts water and mechanically crush for 60 minutes to obtain CLC (lignocellulose) pulp;

[0052] Step 4: Add 75 parts anhydrous ethanol, 1.0 part polytetrafluoroethylene wax (PFW), and 1.5 parts cetyltrimethylammonium bromide (CTAB) to the CLC slurry obtained in Step 3, and mechanically crush it for 10 minutes to obtain a mixed system; then react the mixed system in a sealed container at 80°C for 3 hours; after the reaction is completed, filter and wash the mixed slurry (CLC / PFW-CTAB) obtained by the reaction 4 times, dry it thoroughly at 60°C, and crush and grind it into powder to obtain the lignocellulose-polymer-based lubricating material (CLC / PFW-CTAB lubricating material) based on agricultural straw.

[0053] Part 2: Preparation of modified lignocellulose-polymer-based lubricating materials.

[0054] Step 5: Disperse 1.0 part of the CLC / PFW-CTAB lubricating material obtained in Step 4 and 1.0 part of dopamine hydrochloride in 200 parts of Tris buffer solution, and stir continuously at room temperature for 24 hours. After centrifugation, washing, drying, crushing and grinding, the product is obtained as polydopamine (PDA) modified lignocellulose-polymer-based lubricating material (CLC / PFW-CTAB-PDA).

[0055] Part Three: Lubricant Products.

[0056] Step 6: Disperse the CLC / PFW-CTAB lubricating material obtained in Step 4 evenly in sunflower oil (the mass concentration of CLC / PFW-CTAB lubricating material in sunflower oil is 1.0%) to obtain lubricant product 1-1;

[0057] The CLC / PFW-CTAB-PDA lubricating material powder obtained in step 5 was uniformly dispersed in sunflower oil (the mass concentration of CLC / PFW-CTAB-PDA lubricating material in sunflower oil was 1.0%) to obtain lubricant product 2-1;

[0058] The CLC / PFW-CTAB lubricating material powder obtained in step 4 was uniformly dispersed in a PEG aqueous solution (the mass concentration of CLC / PFW-CTAB lubricating material in the PEG aqueous solution was 0.5%) to obtain lubricant product 3-1.

[0059] Example 2

[0060] A method for preparing a lignocellulose-polymer-based lubricating material based on agricultural straw includes the following steps:

[0061] Step 1: Disperse 8 parts of dried and pulverized corn stalks in 240 parts of 5.0% NaOH aqueous solution, react at 75°C for 3.5 hours, filter and wash with water until neutral to obtain solid material A;

[0062] Step 2: Disperse solid material A in 200 parts of water, add 16 parts of sodium chlorite and 4 parts of acetic acid, react at 90°C for 3.5 hours, filter and wash to obtain bleached lignocellulose solid material B;

[0063] Step 3: Prepare H-DES by mixing 72 parts citric acid, 24 parts choline chloride, and 24 parts water at 75°C; use this H-DES to treat all solid materials B; specifically, first mix H-DES and bleached lignocellulose solid material B and react at 125°C for 2.5 hours; dilute the viscous liquid obtained after the reaction with 200 parts water, filter after dilution, and wash the filter residue three times with water to obtain solid material C; disperse solid material C in 120 parts water and mechanically crush it for 50 minutes to obtain CLC slurry;

[0064] Step 4: Add 60 parts anhydrous ethanol, 0.8 parts polytetrafluoroethylene wax and 1.2 parts hexadecyltrimethylammonium bromide to the CLC slurry obtained in Step 3, and mechanically crush it for 8 minutes to obtain a mixed system; then react the mixed system in a sealed container at 75°C for 2.5 hours; after the reaction is completed, filter and wash the mixed slurry (CLC / PFW-CTAB) obtained by the reaction three times, dry it thoroughly at 55°C, and crush and grind it into powder to obtain CLC / PFW-CTAB lubricating material.

[0065] Part 2: Preparation of modified lignocellulose-polymer-based lubricating materials.

[0066] Step 5: Disperse 0.8 parts of the CLC / PFW-CTAB lubricating material obtained in Step 4 and 0.8 parts of dopamine hydrochloride in 160 parts of Tris buffer solution, and stir continuously at room temperature for 22 hours. After centrifugation, washing, drying, crushing and grinding, the product is CLC / PFW-CTAB-PDA.

[0067] Part Three is the same as Example 1.

[0068] Example 3

[0069] A method for preparing a lignocellulose-polymer-based lubricating material based on agricultural straw includes the following steps:

[0070] Step 1: Disperse 12 parts of dried and pulverized corn stalks in 360 parts of a 6.0% NaOH aqueous solution, react at 85°C for 4.5 hours, filter and wash with water until neutral to obtain solid material A;

[0071] Step 2: Disperse solid material A in 300 parts of water, add 24 parts of sodium chlorite and 6 parts of acetic acid, react at 100°C for 4.5 hours, filter and wash to obtain bleached lignocellulose solid material B;

[0072] Step 3: Prepare H-DES by mixing 108 parts citric acid, 36 parts choline chloride, and 36 parts water at 85°C; use this H-DES to treat all solid materials B; specifically, first mix H-DES and bleached lignocellulose solid material B and react at 135°C for 3.5 hours; dilute the viscous liquid obtained after the reaction with 240 parts water, filter after dilution, and wash the filter residue with water 5 times to obtain solid material C; disperse solid material C in 180 parts water and mechanically crush it for 70 minutes to obtain CLC slurry;

[0073] Step 4: Add 90 parts anhydrous ethanol, 1.2 parts polytetrafluoroethylene wax and 1.8 parts hexadecyltrimethylammonium bromide to the CLC slurry obtained in Step 3, and mechanically crush it for 8 minutes to obtain a mixed system; then react the mixed system in a sealed container at 85°C for 3.5 hours; after the reaction is completed, filter and wash the mixed slurry (CLC / PFW-CTAB) obtained by the reaction 5 times, dry it thoroughly at 65°C, and crush and grind it into powder to obtain CLC / PFW-CTAB lubricating material.

[0074] Part 2: Preparation of modified lignocellulose-polymer-based lubricating materials.

[0075] Step 5: Disperse 1.2 parts of the CLC / PFW-CTAB lubricating material obtained in Step 4 and 1.2 parts of dopamine hydrochloride in 240 parts of Tris buffer solution, and stir continuously at room temperature for 26 hours. After centrifugation, washing, drying, crushing and grinding, the product is CLC / PFW-CTAB-PDA.

[0076] Example 4

[0077] A method for preparing a lignocellulose-polymer-based lubricating material based on agricultural straw includes the following steps:

[0078] Step 1: Disperse 10 parts of dried and pulverized corn stalks in 360 parts of a 6.0% NaOH aqueous solution, react at 80°C for 4.0 hours, filter and wash with water until neutral to obtain solid material A;

[0079] Step 2: Disperse solid material A in 250 parts of water, add 20 parts of sodium chlorite and 5 parts of acetic acid, react at 95°C for 4.0 hours, filter and wash to obtain bleached lignocellulose solid material B;

[0080] Step 3: Prepare H-DES by mixing 95 parts citric acid, 36 parts choline chloride, and 36 parts water at 85°C; use this H-DES to treat all solid materials B; specifically, first mix H-DES and bleached lignocellulose solid material B and react at 130°C for 3.5 hours; dilute the viscous liquid obtained after the reaction with 240 parts water, filter after dilution, and wash the filter residue with water 5 times to obtain solid material C; disperse solid material C in 150 parts water and mechanically crush it for 70 minutes to obtain CLC slurry;

[0081] Step 4: Add 90 parts anhydrous ethanol, 1.2 parts polytetrafluoroethylene wax and 1.8 parts hexadecyltrimethylammonium bromide to the CLC slurry obtained in Step 3, and mechanically crush it for 8 minutes to obtain a mixed system; then react the mixed system in a sealed container at 85°C for 3.5 hours; after the reaction is completed, filter and wash the obtained mixed slurry (CLC / PFW-CTAB) with water 5 times, dry it thoroughly at 65°C, and crush and grind it into powder to obtain CLC / PFW-CTAB lubricating material.

[0082] Part 2: Preparation of modified lignocellulose-polymer-based lubricating materials.

[0083] Step 5: Disperse 1.0 part of the CLC / PFW-CTAB lubricating material obtained in Step 4 and 1.0 part of dopamine hydrochloride in 200 parts of Tris buffer solution, and stir continuously at room temperature for 24 hours. After centrifugation, washing, drying, crushing and grinding, the product is CLC / PFW-CTAB-PDA.

[0084] Comparative Example 1

[0085] A cellulose-sunflower oil-based lubricant can be obtained by uniformly dispersing commercially available nanocellulose (CNF) in sunflower oil (1.0% concentration).

[0086] Figure 1 These are SEM images of the lignocellulose (CLC) prepared in step 3 of Examples 1 to 4 of the present invention; wherein CLC-1 is the lignocellulose prepared in Example 1, CLC-2 is the lignocellulose prepared in Example 2, CLC-3 is the lignocellulose prepared in Example 3, and CLC-4 is the lignocellulose prepared in Example 4. Figure 1 As shown, the original coarse fiber bundles in the lignin obtained by the method of this invention swell under the mild acidity and swelling effect of H-DES, the hydrogen bond network loosens and partially hydrolyzes, and combined with the subsequent high-intensity mechanical shearing and exfoliation, finally generate nanocellulose fibers with diameters ranging from tens to hundreds of nanometers and lengths reaching several micrometers. These filaments have a flexible or semi-rigid interwoven network structure, intertwined with each other to form a loose and porous three-dimensional skeleton, while having a slightly rough texture due to the small amount of lignin remaining on the surface.

[0087] Figure 2 These are SEM images of the lignocellulose-polymer-based lubricating materials (CLC / PFW-CTAB) prepared in step 4 of Examples 1 to 4 of this invention; wherein CLC / PFW-CTAB-1 is the lignocellulose-polymer-based lubricating material prepared in Example 1, CLC / PFW-CTAB-2 is the lignocellulose-polymer-based lubricating material prepared in Example 2, CLC / PFW-CTAB-3 is the lignocellulose-polymer-based lubricating material prepared in Example 3, and CLC / PFW-CTAB-4 is the lignocellulose-polymer-based lubricating material prepared in Example 4. Figure 2 It can be seen that the SEM morphology of CLC / PFW-CTAB, obtained after synergistic modification with polytetrafluoroethylene wax (PFW) and hexadecyltrimethylammonium bromide (CTAB), transforms into a uniformly deposited nano-sized PFW particles or thin-layer coating on the fiber surface. Simultaneously, the anchoring effect of CTAB effectively shields the interhydroxyl hydrogen bonds, reducing fiber aggregation and forming a hybrid structure of fiber skeleton and lubricating component embellishment. The morphological change from CLC to CLC / PFW-CTAB demonstrates that CTAB promotes the uniform loading of PFW on the cellulose surface, and the combination of the two components significantly improves the surface hydrophobic / oleophobic balance and dispersion stability of lignocellulose, laying the foundation for its use as a high-performance lubricant additive.

[0088] Figure 3These are SEM images of the PDA-modified lignocellulose-polymer-based lubricating materials (CLC / PFW-CTAB-PDA) prepared in step 5 of Examples 1 to 4 of this invention; wherein PDA modification-1 is the CLC / PFW-CTAB-PDA prepared in Example 1, PDA modification-2 is the CLC / PFW-CTAB-PDA prepared in Example 2, PDA modification-3 is the CLC / PFW-CTAB-PDA prepared in Example 3, and PDA modification-4 is the CLC / PFW-CTAB-PDA prepared in Example 4. Figure 3 It can be seen that after PDA modification, the surface of the CLC / PFW-CTAB-PDA composite material is theoretically coated with a continuous and uniform PDA film. Therefore, the original PFW particle outlines tend to become blurred or covered, and the fibers exhibit a tighter interwoven network due to the strong adhesion of PDA. The morphology changes from particle dotting to coating coverage from CLC / PFW-CTAB to CLC / PFW-CTAB-PDA, indicating that PDA has successfully deposited and effectively integrated the original lubricating components, providing a multifunctional surface layer for the material. This helps to further regulate its interfacial behavior and tribological properties in other lubricating media.

[0089] Figure 4 This is a graph showing the friction coefficient data of the lignocellulose (CLC) prepared in step 3 of Examples 1 to 4 of the present invention, directly dispersed in sunflower oil. Figure 5 This is a graph showing the coefficient of friction data for commercially purchased cellulose directly dispersed in sunflower oil in Comparative Example 1. From... Figure 4 and Figure 5 As can be seen, when the CLC prepared in step 3 is directly dispersed in sunflower oil (1.0% concentration), its friction coefficient data shows superior friction reduction performance compared to commercial cellulose. Although the unmodified CLC exhibits some aggregation in sunflower oil due to its strong hydrophilicity, its steady-state average friction coefficient is still significantly lower than that of the commercial cellulose control sample. This is mainly attributed to the fact that the CLC obtained by the present invention through H-DES green treatment combined with mechanical crushing has a higher aspect ratio and surface reactivity. Even without hydrophobic modification, its nanofiber structure can form a partial physical barrier in the gap between friction pairs, thus exhibiting superior friction reduction properties compared to traditional commercial cellulose.

[0090] Figure 6 This is a graph showing the friction coefficient data of the lignocellulose-polymer-based lubricating material (CLC / PFW-CTAB) prepared in step 4 of Examples 1 to 4 of this invention, directly dispersed in sunflower oil. Figure 6It can be seen that when CLC / PFW-CTAB is directly dispersed in sunflower oil, its average friction coefficient is basically the same as that of the unmodified CLC sample from step 3, and it does not show the expected significant friction-reducing advantage. This phenomenon indicates that although the introduction of polytetrafluoroethylene wax and hexadecyltrimethylammonium bromide successfully improved the dispersion stability of cellulose in oil and endowed it with oleophobic properties, under the test conditions of this embodiment, the lubrication performance of the composite material is still mainly dominated by the physical barrier effect of the fiber skeleton. The low friction characteristics of PFW may not have been fully released due to factors such as incomplete coating, test load, or interface conditions of the friction pair, resulting in its friction-reducing efficiency failing to surpass that of pure lignocellulose. Therefore, there is no statistically significant difference in the average friction coefficient between the two. However, the functionalization modification process significantly improved the load-bearing capacity of the lubricant, and only slight scratches were produced on the corresponding friction pair surface (see details). Figure 10 ).

[0091] Figure 7 This is a graph showing the friction coefficient data of the PDA-modified lignocellulose-polymer-based lubricant (CLC / PFW-CTAB-PDA) prepared in step 5 of Examples 1 to 4 of this invention, directly dispersed in sunflower oil. Figure 7 It can be seen that the friction coefficient of CLC / PFW-CTAB-PDA is slightly lower than that of CLC in step 3 and CLC / PFW-CTAB in step 4. This indicates that the PDA layer not only integrates PFW and CTAB components as a multifunctional adhesive coating, but also enhances the adsorption capacity of the material and the friction pair surface through its abundant catechol and amino groups, promoting the formation of a stable tribochemical reaction film. At the same time, the moderate hydrophilicity of PDA helps to form an ordered adsorption layer at the oil-metal interface, which has a synergistic effect with the low surface energy characteristics of PFW. This overcomes the friction reduction bottleneck of CLC / PFW-CTAB caused by the compatibility limitation between PFW and base oil, resulting in almost no severe scratches on the corresponding friction pair surface. Figure 10 (Further detailed analysis to follow).

[0092] Figure 8 This is a graph showing the friction coefficient of the lignocellulose-polymer-based lubricant (CLC / PFW-CTAB) prepared in step 4 of Example 1 of the present invention, directly dispersed in a PEG aqueous solution. Figure 9 This is a graph showing the average coefficient of friction (repeated three times) of the lignocellulose-polymer-based lubricant (CLC / PFW-CTAB) prepared in step 4 of Example 1 of this invention, directly dispersed in a PEG aqueous solution. Figure 8 and Figure 9As can be seen, the friction coefficient curve exhibits good stability, with no significant fluctuations or increases throughout the test, and an average friction coefficient of 0.231~0.241. This result indicates that in the polar PEG aqueous solution system, CTAB, as a cationic surfactant, significantly improves the compatibility between hydrophilic lignocellulose and PEG aqueous solution. Simultaneously, the low surface energy of PFW effectively reduces the interfacial shear resistance between friction pairs. The synergistic effect of both allows CLC / PFW-CTAB to be stably dispersed in the water-based lubrication system and form a continuous lubricating film, thus achieving a stable and low friction coefficient, demonstrating its application potential in green water-based lubricants.

[0093] Figure 10 These are wear morphology images of the lignocellulose (CLC) prepared in step 3 of Example 1 of the present invention, the lignocellulose-polymer-based lubricant (CLC / PFW-CTAB) prepared in step 4, the PDA-modified lignocellulose-polymer-based lubricant (CLC / PFW-CTAB-PDA) prepared in step 5, and commercially available cellulose, on the surface of a steel disc. Figure 10 It can be seen that the unmodified CLC caused the most severe wear on the steel disc surface, with a large number of deep and wide plough-like scratches, indicating that its agglomerated particles played an abrasive role during friction. The commercially available CNF, purchased directly, showed the second most severe damage, with obvious but fewer plough-like scratches on the surface, indicating that its dispersibility and lubricity were better than the original CLC, but still insufficient to effectively protect the friction pair. The CLC / PFW-CTAB composite material prepared in step 4 showed a significantly improved anti-wear effect, with only slight scratches on the steel disc surface and no typical plough-like morphology, proving that the introduction of PFW and CTAB effectively suppressed the abrasive behavior of the fibers and formed a protective lubricating film. The CLC / PFW-CTAB-PDA modified by PDA in step 5 had the best performance, with almost no scratches on the steel disc surface, leaving only very slight friction marks, exhibiting a highly smooth wear morphology, confirming that the PDA coating layer further enhanced the adsorption capacity between the material and the metal surface and promoted the formation of a uniform and tough tribochemical reaction film, thus achieving the best protection for the friction pair.

[0094] Figure 11 This is a summary chart of the general friction coefficient ranges for various commonly used lubricating materials. Combined with... Figure 7The results show that the CLC / PFW-CTAB-PDA prepared in this invention exhibits superior frictional performance in sunflower oil. The friction coefficients of traditional mineral base oils and pure vegetable oils are typically at a moderate level. While commonly available commercial lubricant additives can further reduce friction, the reduction is limited. In contrast, the average friction coefficient of the CLC / PFW-CTAB-PDA in sunflower oil is significantly lower than that of pure sunflower oil and most traditional additive-modified oils, comparable to that of some high-end synthetic lubricants or advanced nano-additives, and the friction curve is stable without drastic fluctuations. Furthermore, in water-based lubrication systems, the material of this invention also demonstrates superior friction-reducing effects compared to conventional water-based lubricants.

[0095] This invention uses waste agricultural straw as the sole raw material. After alkaline pretreatment and sodium chlorite bleaching to remove hemicellulose and most of the lignin, high-purity natural lignocellulose fibers are obtained. A green, deep eutectic solvent system composed of citric acid, choline chloride, and water is innovatively introduced for swelling and activation, combined with mechanical crushing to obtain a nanocellulose slurry with high aspect ratio and high surface activity. The key step is the simultaneous addition of anhydrous ethanol, polytetrafluoroethylene wax (a low surface energy lubricating component), and hexadecyltrimethylammonium bromide (a cationic surfactant) to the slurry. Through synergistic chemical modification and physical coating in a closed system, the surface oleophobic / hydrophobic balance and oil phase dispersion stability of the nanocellulose are significantly improved. Finally, the mixture is dried and ground to obtain a powdered lubricating additive. This additive can be directly dispersed in various lubricating oil base oils, forming a stable physical adsorption film or tribochemical reaction film on the surface of friction pairs, exhibiting excellent friction-reducing and anti-wear properties. The technical approach of this invention from low-value agricultural waste to high-performance lubricating materials has the advantages of renewable raw materials, green process, low reagent consumption, and simple operation. It achieves the dual goals of "turning waste into treasure" and "high performance", and provides a practical technical example for the high-value utilization of agricultural straw and the development of green lubricating materials.

[0096] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention. The above embodiments are provided only for the purpose of describing the present invention and are not intended to limit the present invention. Parts not described in detail in this specification are well-known in the art and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be covered within the scope of the present invention.

Claims

1. A method for preparing a lignocellulose-polymer-based lubricating material based on agricultural straw, characterized in that, Includes the following steps: Step 1: Pre-treat the dried and pulverized agricultural straw with alkaline solution to obtain solid material A; Step 2: Bleaching solid material A to obtain bleached lignocellulose solid material B; Step 3: Mix 72-108 parts of citric acid, 24-36 parts of choline chloride and 24-36 parts of water at 75-85℃ to prepare H-DES; use the prepared H-DES to treat the bleached lignocellulose solid material B obtained in step 2 to obtain lignocellulose pulp; Step 4: Add 60-90 parts anhydrous ethanol, 0.8-1.2 parts polytetrafluoroethylene wax, and 1.2-1.8 parts hexadecyltrimethylammonium bromide to the lignocellulose slurry obtained in Step 3, and then mechanically crush it for 8-12 minutes to obtain a mixed system; then react the mixed system in a sealed container at 75-85℃ for 2.5-3.5 hours; after the reaction is completed, filter and wash the mixed slurry obtained from the reaction, and then dry it at 55-65℃; process the dried product into powder to obtain a lignocellulose-polymer-based lubricating material based on agricultural straw.

2. The method for preparing the lignocellulose-polymer-based lubricating material based on agricultural straw according to claim 1, characterized in that, Step 1 involves dispersing 8-12 parts of dried and pulverized agricultural straw in 240-360 parts of a 4.0%-6.0% NaOH aqueous solution, reacting at 75-85°C for 3.5-4.5 hours, filtering and washing with water until neutral to obtain solid material A.

3. The method for preparing the lignocellulose-polymer-based lubricating material based on agricultural straw according to claim 1, characterized in that, Step 2 specifically involves dispersing the solid material A obtained in Step 1 in 200-300 parts of water, adding 16-24 parts of sodium chlorite and 4-6 parts of acetic acid, reacting at 90-100℃ for 3.5-4.5 hours, filtering and washing with water until neutral to obtain bleached lignocellulose solid material B.

4. The method for preparing the lignocellulose-polymer-based lubricating material based on agricultural straw according to claim 1, characterized in that, The specific steps in step 3, where the prepared H-DES is used to treat the bleached lignocellulose solid material B obtained in step 2 to obtain lignocellulose pulp, are as follows: H-DES and bleached lignocellulose solid material B were mixed and reacted at 125~135℃ for 2.5~3.5 hours to obtain a viscous liquid; Dilute the viscous liquid with 160-240 parts water; The diluted viscous liquid was filtered and washed with water to obtain solid material C; Disperse all solid material C in 120-180 parts of water and mechanically crush for 50-70 minutes to obtain lignocellulose pulp.

5. The method for preparing the lignocellulose-polymer-based lubricating material based on agricultural straw according to claim 1, characterized in that, The agricultural straw in step 1 is one or more of the following: corn straw, rice straw, wheat straw, barley straw, and sorghum straw.

6. The method for preparing the lignocellulose-polymer-based lubricating material based on agricultural straw according to claim 1, characterized in that, The preparation method of the lignocellulose-polymer-based lubricating material based on agricultural straw further includes the following steps: Step 5: Modify the lignocellulose-polymer-based lubricant material based on agricultural straw; specifically, disperse 0.8-1.2 parts of the lignocellulose-polymer-based lubricant material obtained in Step 4 and 0.8-1.2 parts of dopamine hydrochloride in 160-240 parts of Tris buffer solution, stir continuously at room temperature for 22-26 hours, and obtain the PDA-modified lignocellulose-polymer-based lubricant material after centrifugation, washing, drying, crushing and grinding.

7. A lignocellulose-polymer based lubricating material based on agricultural straw, characterized in that, The lubricant is prepared by the method of any one of claims 1 to 5 based on lignocellulose-polymer based lubricant from agricultural straw. In the lubricant based on lignocellulose-polymer based lubricant from agricultural straw, nano-sized polytetrafluoroethylene wax particles or thin-layer coatings are uniformly attached to the fiber surface. At the same time, the anchoring effect of hexadecyltrimethylammonium bromide effectively shields the interhydroxyl hydrogen bonds, reduces fiber agglomeration, and forms a hybrid structure of fiber skeleton and lubricant component embellishment.

8. A lignocellulose-polymer based lubricating material based on agricultural straw, characterized in that, The lubricating material is prepared by the method described in claim 6 for preparing lignocellulose-polymer-based lubricating material based on agricultural straw; the surface of the lignocellulose-polymer-based lubricating material based on agricultural straw is coated with a continuous and uniform polydopamine film.

9. The use of the lignocellulose-polymer-based lubricating material based on agricultural straw as described in claim 7 or 8 as an additive in lubricating oils or greases.

10. A lubricant product, characterized in that, The lubricating phase includes the lignocellulose-polymer-based lubricating material based on agricultural straw as described in claim 7 or 8, wherein the amount of the lignocellulose-polymer-based lubricating material based on agricultural straw added is 0.25% to 1.5% of the mass of the lubricating phase.

Images