Environment-friendly organic tungsten additive and lubricating oil containing additive

Abstract

The invention belongs to the technical field of environment-friendly lubricating materials, and particularly relates to an environment-friendly organic tungsten additive and lubricating oil containing the additive. 25%-40% of a nano tungsten source; 55%-70% of a composite organic ligand, which accounts for the total mass percentage of the organic tungsten additive; 30% to 40% of C14-C16 hydroxy oleic acid, 15% to 20% of N-methylglycine and 10% to 15% of N-methyldiethanolamine; the green solvent is a mixed solution of propylene glycol and deionized water, and the mass ratio of the propylene glycol to the deionized water is 2: 1. The lubricating oil comprises the following components in percentage by weight; 80%-90% of composite base oil; 1%-6% of an organic tungsten additive; and 5%-15% of a synergistic function additive. The additive does not contain sulfur, phosphorus and heavy metal elements, and the biodegradation rate is high; the composite base oil is compounded by bio-based poly-alpha-olefin and sunflower seed oil methyl ester to replace traditional mineral oil, so that the risk of environmental pollution is reduced from the source.

Description

Technical Field

[0001] This invention belongs to the field of environmentally friendly lubricating materials technology, specifically relating to an environmentally friendly organic tungsten additive and a lubricating oil containing the additive. Background Technology

[0002] As a key auxiliary material in the industrial field, the performance of lubricating materials directly affects the operating efficiency, service life, and environmental safety of equipment. Currently, most mainstream lubricating oil additives on the market are mainly composed of sulfur and phosphorus compounds. Although they can improve anti-wear and extreme pressure performance to a certain extent, they have significant drawbacks: sulfur and phosphorus components easily react with metal surfaces to form corrosive products, which aggravates equipment wear. Moreover, they are difficult to biodegrade after disposal, which can easily cause soil and water pollution, failing to meet the current environmental protection regulations for low-toxicity and easily degradable materials.

[0003] In response to environmental protection requirements, bio-based lubricants have gradually gained attention. However, they suffer from insufficient anti-wear properties and poor high-temperature stability, making them unsuitable for use alone to meet the lubrication requirements of heavy-duty equipment. Meanwhile, nano-additives have been extensively studied due to their excellent anti-wear potential, but their dispersion stability in base oils remains a major technical bottleneck—unmodified nanoparticles are prone to agglomeration, leading to uneven lubrication effects and poor compatibility with base oils, affecting low-temperature fluidity (e.g., a high pour point, making them unsuitable for cold-climate operating environments).

[0004] Furthermore, traditional additive preparation processes often employ high-temperature oil bath heating, resulting in long reaction times (typically 3-5 hours), high energy consumption, and a tendency to decompose organic ligands, thus reducing product activity. Achieving high environmental friendliness, good low-temperature fluidity, and efficient preparation of lubricating materials while ensuring anti-wear and extreme pressure properties has become a pressing technical challenge in this field.

[0005] Based on the above situation, developing a sulfur- and phosphorus-free, highly biodegradable, wear-resistant, and low-temperature-resistant environmentally friendly lubricating additive and lubricating oil that can be prepared efficiently is of great practical significance and application value. Summary of the Invention

[0006] In view of the above-mentioned shortcomings in the prior art, the present invention provides an environmentally friendly organic tungsten additive and a lubricating oil containing the additive to solve the problems in the background art.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: An environmentally friendly organic tungsten additive is prepared from the following components in weight percentages; Nano-tungsten source: 25%-40%, wherein the nano-tungsten source is tungstic anhydride modified with γ-mercaptopropyltrimethoxysilane; Complex organic ligands: 55%-70%, including a percentage of the total mass of the organic tungsten additives; C14-C16 hydroxyoleic acid 30%-40%, N-methylglycine 15%-20% and N-methyldiethanolamine 10%-15%; Green solvent: 5%-10%, wherein the green solvent is a mixture of propylene glycol and deionized water in a mass ratio of 2:1.

[0008] Furthermore, the surface modification step of the tungstate anhydride includes; Nano-sized tungstate anhydride was dispersed in propylene glycol to form a uniform suspension; γ-Mercaptopropyltrimethoxysilane was added to the suspension in an amount of 1%-3% of the mass of the nano-tungsten source. The mixture was transferred to an ultrasonic reactor and ultrasonically treated at 300W power for 30 minutes at 65°C. After ultrasonic treatment, the system was centrifuged at 8000 r / min for 10 minutes to separate solid particles; then the solid particles were placed in a vacuum drying oven at 60℃ for 2 hours to remove residual propylene glycol and obtain modified nano-tungsten source.

[0009] Furthermore, the preparation method of the organic tungsten additive is as follows: the modified nano-tungsten source and the composite organic ligand are added to the reaction vessel at a tungsten:ligand molar ratio of 1:2-1:3, and propylene glycol is added as a dispersion medium. The concentration of tungstate anhydride in the system is controlled at a mass fraction of 10%-15%. React for 15-20 minutes in a microwave reactor with a microwave power of 300-500W and a temperature of 80-100℃; After the reaction was completed, the solid product was separated by centrifugation at 8000 r / min for 15 minutes, and then washed with ethanol 2-3 times to remove unreacted ligands. Finally, it was vacuum dried at 60℃ to constant weight to obtain the organic tungsten additive.

[0010] Furthermore, it also includes 2%-8% by weight of a functional auxiliary ligand, said functional auxiliary ligand being selected from at least one of C12 hydroxystearic acid or proline.

[0011] This invention also provides a lubricating oil, wherein the sulfate ash content of the lubricating oil is ≤0.3%, and under extreme pressure testing at 1200 r / min and 392 N using a four-ball machine, its wear scar diameter is ≤0.3 mm, and its pour point is ≤-35℃. The lubricating oil is characterized by comprising the following components by weight percentage: Complex base oil: 80%-90%; Organic tungsten additive: 1%-6%; Synergistic functional additives: 5%-15%.

[0012] Furthermore, the composite base oil is composed of bio-based polyalphaolefin and sunflower seed oil methyl ester in a mass ratio of 7:3.

[0013] Furthermore, the synergistic functional additive comprises the following components by weight percentage (as a percentage of the total weight of the lubricating oil): Stigmasterol oleate 1%-3%; Polypropylene glycol monostearate 2%-5%; Alkyl glycoside modified attapulgite 2%-7%.

[0014] Furthermore, the preparation steps of the alkyl glycoside modified attapulgite include: Natural attapulgite is added to deionized water to prepare a slurry with a mass concentration of 5%-20%. The slurry is stirred at 500-800 r / min for 30-60 minutes at room temperature. Then, 1%-3% inorganic acid by mass of attapulgite is added to adjust the pH to 2-4. The slurry is activated at 60-80℃ for 2-4 hours. The activated slurry is separated by centrifugation or filtration, washed with deionized water until neutral, and dried at 80-100℃ for 12-24 hours to obtain pretreated attapulgite. Pretreated attapulgite was dispersed in a mixed solvent of propylene glycol and deionized water to form a suspension with a solid content of 10%-15%. Alkyl glycosides were added, with an amount of 10%-15% of the attapulgite mass. The mixture was stirred at 300-500 r / min for 2-3 hours at 50-70℃. The resulting suspension was washed 2-3 times with ethanol, centrifuged, and then vacuum dried at 60-80℃ for 8-12 hours to obtain alkyl glycoside-modified attapulgite.

[0015] Furthermore, the method for preparing the lubricating oil includes the following steps: (1) Preparation of composite base oil: Bio-based PAO and sunflower seed oil methyl ester were added to a stirring vessel at a mass ratio of 7:3 and stirred for 30 minutes at 40±5℃ and 300r / min to form a homogeneous composite base oil; (2) Dispersion of nano-additives: Add alkyl glycoside modified attapulgite to the composite base oil in step (1) and ultrasonically disperse for 30 minutes. (3) Microwave-assisted mixing: Environmentally friendly organic tungsten additive, stigmasterol oleate and polypropylene glycol monostearate are added to the system in step (2) in sequence and stirred for 1 hour under microwave assistance; Post-processing: The mixed system was naturally cooled to room temperature and filtered through a polytetrafluoroethylene filter membrane with a pore size of 0.22 μm to obtain lubricating oil.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The organic tungsten additive and lubricating oil of this invention use green and environmentally friendly raw materials and processes throughout: the additive is free of sulfur, phosphorus, and heavy metals, and has a biodegradability rate of ≥95%; the composite base oil is a blend of bio-based polyalphaolefin and sunflower seed oil methyl ester, replacing traditional mineral oil and reducing environmental pollution risks from the source. Simultaneously, the preparation process uses green solvents such as propylene glycol and ethanol, with no volatile harmful emissions; 2. A nano-tungsten source modified with γ-mercaptopropyltrimethoxysilane forms a stable structure through multidentate coordination with composite organic ligands (C14-C16 hydroxyoleic acid, N-methylglycine, and N-methyldiethanolamine), creating a high-strength lubricating film on the metal surface. Combined with the synergistic effect of alkyl glycoside-modified attapulgite, the lubricating oil exhibits a wear scar diameter ≤0.3mm in a four-ball extreme pressure test at 1200 r / min and 392 N, significantly superior to traditional additive systems, effectively extending equipment lifespan. Attached Figure Description

[0017] Figure 1 A flowchart illustrating the preparation method of the organic tungsten additive provided by this invention; Figure 2 A flowchart of the surface modification method of tungstate anhydride provided by the present invention; Figure 3 A flowchart illustrating the method for preparing lubricating oil provided by the present invention; Figure 4 A flowchart of the method for preparing alkyl glycoside modified attapulgite provided by the present invention; Detailed Implementation To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0018] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0019] This invention provides an environmentally friendly organic tungsten additive, which is prepared from the following components in weight percentage; Nano-tungsten source: 25%-40%, wherein the nano-tungsten source is tungstic anhydride modified with γ-mercaptopropyltrimethoxysilane; Complex organic ligand: 55%-70%, wherein the complex organic ligand comprises the following components in weight percentage: C14-C16 hydroxyoleic acid 30%-40%, N-methylglycine 15%-20%, and N-methyldiethanolamine 10%-15%; Green solvent: 5%-10%, wherein the green solvent is a mixture of propylene glycol and deionized water in a mass ratio of 2:1.

[0020] The additive has a biodegradability rate of ≥95% (as determined by GB / T 19981-2005), contains no sulfur, phosphorus, or heavy metal elements, and exhibits no crystallization within the temperature range of -30℃ to 150℃.

[0021] The surface modification step of the nano-tungsten source specifically includes the following operations: dispersing nano-tungstate anhydride: dispersing nano-tungstate anhydride (particle size 50-100nm, D50=70±5nm) in propylene glycol to form a uniform suspension (the solid-liquid ratio can be adjusted according to the dispersion effect, usually 1:3-1:5).

[0022] Add modifier: Add γ-mercaptopropyltrimethoxysilane (KH-590) to the above suspension. The amount added is 1%-3% of the mass of the nano-tungsten source (for example, 1-3g of silane needs to be added for 100g of nano-tungstic anhydride).

[0023] Ultrasonic treatment: The mixture is transferred to an ultrasonic reactor and ultrasonically treated at 300W at 65°C for 30 minutes to allow silane molecules to fully react with the hydroxyl groups (-OH) on the surface of nano-tungstate anhydride through the mercapto (-SH) groups to form covalent bonds.

[0024] Centrifugal drying: After ultrasonic treatment, the system was centrifuged at 8000 r / min for 10 minutes to separate solid particles; then the solid was placed in a vacuum drying oven at 60℃ for 2 hours to remove residual propylene glycol and obtain modified nano-tungsten source.

[0025] After the above steps, the surface hydroxyl content of the nano-tungsten source increased by 30%-40% compared to before modification, and its dispersibility was significantly improved, effectively avoiding aggregation problems in subsequent coordination reactions and improving coordination efficiency with organic ligands. This modification step achieves surface functionalization of the nano-tungsten source through chemical bonding, laying the foundation for the formation of a stable coordination structure with composite organic ligands, while also enhancing the compatibility of the additive with bio-based base oils.

[0026] The preparation method of this environmentally friendly organic tungsten additive uses nano-tungstate anhydride as the core raw material and achieves the process through surface modification and microwave-assisted coordination reaction of composite organic ligands. The specific steps are as follows: I. Surface Modification of Nano-Tungsten Sources Dispersion pretreatment: Nanoparticles of tungstate anhydride with a particle size of 50-100 nm (D50=70±5 nm) are dispersed in propylene glycol at a solid-liquid ratio of 1:3-1:5 to form a uniform suspension. This step reduces the surface energy of the nanoparticles and prevents initial agglomeration by utilizing the polar solvent effect of propylene glycol.

[0027] Silane coupling agent modification: γ-mercaptopropyltrimethoxysilane (KH-590) is added, with an amount of 1%-3% of the mass of nano-tungstate anhydride. The trimethoxy group (-OCH3) of the silane molecule is hydrolyzed in propylene glycol to form a silanol group (-Si-OH), which forms a Si-OW covalent bond with the hydroxyl group (-OH) on the surface of the tungstate anhydride through a condensation reaction. At the same time, the mercapto group (-SH) is retained on the particle surface as an active site.

[0028] Ultrasonic enhancement reaction: Ultrasonic treatment at 65℃ and 300W for 30 minutes utilizes the cavitation effect of ultrasound to accelerate the uniform distribution of silane molecules on the particle surface, ensuring uniform modified layer thickness. This step increases the surface hydroxyl content of nano-tungstate anhydride by 30%-40%, significantly enhancing its coordination activity with organic ligands.

[0029] Centrifuge and dry; after the reaction, centrifuge at 8000 r / min for 10 minutes to separate the solid, and then vacuum dry at 60℃ for 2 hours to remove residual solvent, to obtain the modified nano-tungsten source with surface grafted silane.

[0030] II. Synthesis of Complex Organic Ligands The components are mixed; C14-C16 hydroxyoleic acid (30%-40%), sarcosine, and N-methyldiethanolamine are mixed in a specific ratio. C14-C16 hydroxyoleic acid introduces a dihydroxyl group through ring-opening with an olive oil epoxide derivative, forming a bidentate coordination structure; sarcosine provides an amino group (-NH2), and N-methyldiethanolamine provides a secondary amino group (-N(CH2CH2OH)2), the three synergistically constructing a multidentate coordination system.

[0031] Pre-reaction treatment: Under nitrogen protection, the mixed ligands are heated to 50-60°C and stirred for 1 hour to promote hydrogen bonding between components and form a preliminary associated structure. This step can optimize the kinetic pathway of subsequent coordination reactions and improve reaction efficiency.

[0032] III. Microwave-assisted coordination reaction Construction of the hybrid system: Modified nano-tungsten source and composite organic ligand were added to the reactor at a tungsten:ligand molar ratio of 1:2-1:3, with propylene glycol added as a dispersion medium. The concentration of tungstate anhydride in the system was controlled at 10%-15% (mass fraction) to balance the reaction rate and product dispersibility.

[0033] Microwave irradiation conditions: React at a microwave power of 300-500W and a temperature of 80-100℃ for 15-20 minutes. The dielectric heating effect of microwaves rapidly raises the temperature of the reaction system, and the energy acts directly on polar molecules (such as hydroxyl and amino groups in ligands), significantly shortening the induction period of the coordination reaction. Compared with traditional heating, microwave-assisted reaction can reduce the reaction time by more than 50%, while avoiding side reactions caused by local overheating.

[0034] Post-processing: After the reaction, the system was centrifuged at 8000 r / min for 15 minutes to separate the solid product. Unreacted ligands were then washed 2-3 times with ethanol. Finally, the product was vacuum dried at 60℃ to constant weight to obtain a uniformly sized organic tungsten additive. After silane modification, the surface hydroxyl content of the nano-tungstate anhydride increased, leading to more coordination sites with ligands. The bidentate coordination structure of C14-C16 hydroxyoleic acid complemented the polydentate coordination of sarcosine and N-methyldiethanolamine, constructing a three-dimensional network coordination cage, significantly improving the thermal stability of the tungsten complex (decomposition temperature > 300℃).

[0035] Microwave process optimization: Microwave irradiation rapidly polarizes ligand molecules, accelerating their migration to the surface of tungstate anhydride and increasing coordination efficiency by more than 30%; the dielectric constant of the reaction system is dynamically adjusted in the microwave field, promoting the uniform binding of ligands and tungstate anhydride, and the tungsten content in the product can reach 18%-22% (mass fraction), far exceeding the 12%-15% of the traditional method.

[0036] The entire process uses green solvents such as propylene glycol and ethanol, with no harmful volatile emissions; the product does not contain sulfur or phosphorus, avoiding the corrosion and environmental toxicity of traditional additives, and complies with EU REACH regulations.

[0037] This preparation method combines nanomaterial surface engineering with microwave synthesis technology to achieve the green production of high-performance organic tungsten additives. Adding 0.5%-1% of the product to lubricating oil can reduce the coefficient of friction to below 0.03 and significantly extend the oil change cycle (by more than 50%).

[0038] The specific steps for preparing alkyl glycoside-modified attapulgite are as follows: 1. Attapulgite pretreatment Dispersion and activation: Add natural attapulgite (particle size ≤200nm) to deionized water to prepare a slurry with a mass concentration of 5%-20%. Stir at 500-800 rpm for 30-60 minutes at room temperature to fully disperse the particles. Then add 1%-3% of the attapulgite mass of an inorganic acid (such as hydrochloric acid) to adjust the pH to 2-4. Activate at 60-80℃ for 2-4 hours to remove surface impurities and expose silanol groups (-SiOH).

[0039] Washing and drying: The activated slurry is separated by centrifugation or filtration, washed with deionized water until neutral, and dried at 80-100℃ for 12-24 hours to obtain pretreated attapulgite.

[0040] 2. Surface modification of alkyl glycosides Dispersion and reaction: The pretreated attapulgite was dispersed in a mixed solvent of propylene glycol and deionized water (mass ratio 2:1) to form a suspension with a solid content of 10%-15%. Alkyl glycosides (10%-15% of the mass of the attapulgite) were added, and the mixture was stirred at 300-500 r / min for 2-3 hours at 50-70℃.

[0041] Reaction mechanism: The hydroxyl groups (-OH) in the alkyl glycoside molecule combine with the silanol groups on the surface of attapulgite through hydrogen bonding or condensation reaction, and the alkyl chains (C8-C16) are oriented to form a hydrophobic layer, which changes the hydrophilicity of attapulgite to lipophilicity and enhances its dispersibility in lubricating oil.

[0042] Optimization parameters: If further improvement of dispersion stability is required, a small amount of γ-mercaptopropyltrimethoxysilane (KH-590, the amount is 1%-2% of the mass of attapulgite) can be added as a coupling agent and reacted synergistically at 60-80℃ for 1-2 hours.

[0043] 3. Post-treatment and drying Washing and separation: The suspension after reaction is washed with ethanol 2-3 times to remove unreacted alkyl glycosides and byproducts. After centrifugation, it is vacuum dried at 60-80℃ for 8-12 hours to obtain alkyl glycoside modified attapulgite.

[0044] Crushing and Classification: The dried product is subjected to air jet milling or ball milling to make the particle size ≤200nm, and then classified by cyclone grading or vibrating screen to ensure that the particle size distribution meets the patent requirements.

[0045] 4. Performance Verification and Application The grafting of alkyl glycosides was detected by Fourier transform infrared spectroscopy (FT-IR), crystal structure changes were analyzed by X-ray diffraction (XRD), and surface hydrophobicity was evaluated by contact angle testing (target contact angle ≥90°). The modified attapulgite clay can form a synergistic anti-wear system with organotungsten additives in lubricating oil. Its layered structure, together with the hydrophobic layer of the alkyl glycosides, enhances oil film strength and reduces the coefficient of friction.

[0046] Conventional modification of attapulgite often employs quaternary ammonium salts or silane coupling agents, while alkyl glycosides are biodegradable (≥95%), meeting the patent's positioning as an "environmentally friendly" additive. The hydrophilic group of alkyl glycosides binds to attapulgite, while the hydrophobic group is compatible with lubricating oil base oil, forming a "bridging" effect that significantly improves the additive's dispersibility and long-lasting effect in oil.

[0047] In summary, this preparation method achieves efficient surface modification of attapulgite through pretreatment activation, alkyl glycoside grafting, and post-treatment optimization, enabling it to perform multiple functions such as synergistic anti-wear, thickening, and low-temperature flow improvement in lubricating oil, which meets the performance requirements of the patent for "synergistic functional additives".

[0048] This invention also provides a method for preparing lubricating oil. The preparation of the lubricating oil requires a three-step process: base oil compounding, additive stepwise dispersion, and synergistic modification, taking into account both the compatibility and performance synergy of the components. The specific steps are as follows: I. Preparation of Complex Base Oils Raw material pretreatment: Take bio-based polyalphaolefin (PAO, kinematic viscosity of 15-25 mm² / s at 40℃) and sunflower seed oil methyl ester at a mass ratio of 7:3, add 0.1% food-grade antioxidant (tea polyphenols), stir at 60℃ for 30 minutes (300 r / min) under nitrogen protection to remove trace amounts of water from the base oil (moisture content must be ≤0.05%, determined according to GB / T 260-2016). Homogenization treatment: The mixed oil is transferred to a high-pressure homogenizer and circulated three times under a pressure of 20 MPa to fully fuse the molecules of the two base oils (no obvious phase separation was observed under a polarizing microscope) to obtain a composite base oil for later use. II. Stepwise Dispersion of Functional Additives Dispersion of alkyl glycoside modified attapulgite: Add 2%-7% by weight of alkyl glycoside modified attapulgite (particle size ≤200nm) to the composite base oil in step 1, turn on the ultrasonic dispersion equipment (power 500W, frequency 25kHz), and treat at ≤50℃ for 30 minutes (temperature controlled by water bath to avoid oxidation of base oil). Dispersion endpoint determination: Take a small amount of sample and test it with a laser particle size analyzer. More than 90% of the particles have a particle size ≤200nm and no sedimentation after standing for 24 hours (centrifugation acceleration test: centrifuge at 3000r / min for 30 minutes, the transmittance of the supernatant is ≥95%).

[0049] The introduction of environmentally friendly organic tungsten additives: While stirring (500 r / min), add 1%-6% of environmentally friendly organic tungsten additives to the system, heat to 60℃ and continue stirring for 60 minutes to make the organic tungsten molecules uniformly adsorbed on the surface of attapulgite (by X-ray photoelectron spectroscopy analysis, the uniformity of W element distribution on the particle surface is ≥90%). Synergistic functional additives were compounded by adding 1%-3% stigmasterol oleate (antioxidant) and 2%-5% polypropylene glycol monostearate (low-temperature flow improver) sequentially, and stirring at 800 r / min for 45 minutes at 50°C to form a stable multiphase dispersion system. III. Post-processing and performance tuning Degassing and filtration: The mixture is transferred to a vacuum degasser and treated at -0.09MPa vacuum and 60℃ for 40 minutes to remove bubbles; then filtered through a 0.22μm polytetrafluoroethylene filter membrane to remove mechanical impurities (impurity content ≤0.005%). Performance calibration: Determine the extreme pressure performance of the four-ball mill according to GB / T 3142-2009. If the wear scar diameter is >0.3mm, add 0.5% organic tungsten additive and stir again for 30 minutes. Determine the pour point according to GB / T 3535-2006. If the pour point is -40℃ > -35℃, add 1% polypropylene glycol monostearate and sonicate for 15 minutes until the standard is met. IV. Key Process Parameters and Principles Temperature control logic: Ultrasonic dispersion stage ≤50℃: prevents oxidation of unsaturated bonds in sunflower seed oil methyl ester (acid value increase ≤0.1mgKOH / g); Additive mixing stage 50-60℃: promotes interfacial adsorption between organotungsten and attapulgite, while avoiding decomposition of stigmasterol oleate (thermal weight loss temperature >200℃, good stability at 60℃).

[0050] Dispersion mechanism: The hydrophobic chains of alkyl glycoside-modified attapulgite are compatible with the base oil, and the hydrophilic groups combine with the hydroxyl groups of organotungsten through hydrogen bonds to form a "three-dimensional network dispersion structure". This not only solves the problem of nanoparticle aggregation, but also enhances the oil film strength through the coordination bonds of organotungsten (the friction coefficient can be reduced to 0.028).

[0051] Environmental protection is guaranteed; green solvents such as propylene glycol and ethanol are used throughout the process, with no emissions of volatile organic compounds (VOCs); the biodegradability rate of the final product is ≥95% (determined according to GB / T 19981-2005), and the sulfate ash content is ≤0.3%, which meets the environmental protection requirements of EU EC 1272 / 2008. The lubricating oil prepared by this method performs excellently in cold-region engineering machinery, food-grade gearboxes and other applications. It can work stably in the temperature range of -40℃ to 150℃, and the oil change interval is extended by more than 50% compared with traditional mineral oil lubricating oil. Example 1 Prepare the organic tungsten additive and lubricating oil according to the following steps; The raw materials were weighed according to the following weight percentages: 30% nano-tungsten source (tungstic anhydride modified with γ-mercaptopropyltrimethoxysilane, particle size 70 nm), 60% composite organic ligand (35% C14-C16 hydroxyoleic acid, 18% N-methylglycine, and 7% N-methyldiethanolamine), and 10% green solvent (propylene glycol:deionized water = 2:1). The modified nano-tungsten source and composite organic ligand were added to the reactor at a tungsten:ligand molar ratio of 1:2.5, using propylene glycol as the dispersion medium (tungstic anhydride concentration 12%), and reacted at 400 W microwave power and 90 °C for 18 minutes. After the reaction, the mixture was centrifuged at 8000 r / min for 15 minutes, washed three times with ethanol, and vacuum dried at 60 °C to constant weight to obtain the organic tungsten additive.

[0052] The components were weighed by weight percentage as follows: 85% composite base oil (bio-based polyalphaolefin: sunflower seed oil methyl ester = 7:3), 4% of the above-mentioned organic tungsten additive, and 11% of synergistic functional additive (including 2% stigmasterol oleate, 4% polypropylene glycol monostearate, and 5% alkyl glycoside modified attapulgite). The composite base oil was stirred at 40℃ and 300r / min for 30 minutes until homogeneous; the alkyl glycoside modified attapulgite was added and ultrasonically dispersed at 500W and 25kHz for 30 minutes (temperature controlled ≤50℃); the organic tungsten additive, stigmasterol oleate, and polypropylene glycol monostearate were added sequentially, and the mixture was microwave-assisted stirred for 1 hour; after cooling to room temperature, the mixture was filtered through a 0.22μm polytetrafluoroethylene filter membrane to obtain the finished lubricating oil.

[0053] Example 2 Preparation of environmentally friendly organic tungsten additives Raw material ratio: 40% nano-tungsten source, 50% composite organic ligand (30% C14-C16 hydroxyoleic acid, 15% N-methylglycine, 5% N-methyldiethanolamine), and 10% green solvent. Preparation process: Tungsten:ligand molar ratio 1:2, microwave power 500W, reaction at 100℃ for 15 minutes, the remaining steps are the same as in Example 1.

[0054] Lubricating oil preparation Component ratio: 84% composite base oil, 6% organic tungsten additive, and 10% synergistic functional additive (1% stigmasterol oleate, 5% polypropylene glycol monostearate, and 4% alkyl glycoside modified attapulgite). Preparation steps are the same as in Example 1.

[0055] Example 3 Preparation of environmentally friendly organic tungsten additives Raw material ratio: 25% nano-tungsten source, 70% composite organic ligand (40% C14-C16 hydroxyoleic acid, 20% N-methylglycine, 10% N-methyldiethanolamine), and 5% green solvent. Preparation process: Tungsten:ligand molar ratio 1:3, microwave power 300W, reaction at 80℃ for 20 minutes, the remaining steps are the same as in Example 1.

[0056] Lubricating oil preparation Component ratio: 86% complex base oil, 3% organic tungsten additive, 11% synergistic functional additive (3% stigmasterol oleate, 2% polypropylene glycol monostearate, and 6% alkyl glycoside modified attapulgite).

[0057] The preparation steps are the same as in Example 1.

[0058] Comparative Example 1 The difference from Example 1: The nano-tungsten source was not modified with γ-mercaptopropyltrimethoxysilane, and the original tungstate anhydride was used directly. The proportions of the remaining raw materials and the preparation process were completely the same.

[0059] Comparative Example 2 The difference from Example 1 is that the complex organic ligand is replaced with a single C14-C16 hydroxyoleic acid (60%), while the proportions of the remaining raw materials and the preparation process are completely the same.

[0060] Comparative Example 3 The difference from Example 1: the attapulgite in the synergistic additive was not modified with alkyl glycosides, and the original attapulgite was used. The proportions of the remaining raw materials and the preparation process were completely the same.

[0061] Comparative Example 4 The difference from Example 1 is that the complex base oil is replaced with API Group III mineral oil, while the proportions of other raw materials and the preparation process are completely the same.

[0062] The lubricating oils prepared above were subjected to the following experiments; I. Biodegradation rate test (based on GB / T 19981-2005) 1. Experimental objective: To verify the environmental friendliness of the additives and lubricants, ensuring a biodegradability rate of ≥95%.

[0063] 2. Test Method: The CO2 release method was used. 10g of sample was mixed with activated sludge (concentration 30g / L) and placed in a 500mL closed reactor, and cultured at a constant temperature of 25℃ for 28 days. The total amount of CO2 released was monitored by an infrared gas analyzer, and the biodegradation rate (the ratio of degraded CO2 to the theoretical maximum release amount) was calculated.

[0064] II. Four-ball extreme pressure test (according to GB / T 3142-2009) 1. Experimental objective: To evaluate the anti-wear performance of lubricating oil, requiring a wear scar diameter ≤ 0.3 mm.

[0065] 2. Testing equipment: MQ-800 four-ball friction and wear testing machine, equipped with a 40x metallographic microscope.

[0066] 3. Experimental conditions: Steel ball specifications: φ12.7mm GCr15 bearing steel ball (hardness HRC 62-64, surface roughness Ra≤0.02μm); Operating parameters: speed 1200 r / min, load 392 N (40 kgf), room temperature (25 ± 2 ℃), duration 60 minutes; Oil sample volume: 10 mL, completely submerging the steel ball (depth 5 mm).

[0067] 3. Result Measurement: After the experiment, the steel balls were cleaned with anhydrous ethanol, and the maximum diameter of the wear scars on the test balls was measured. The average value of three parallel tests was taken (allowable deviation ±0.02 mm). The wear scar diameter of Example 1 was 0.25 mm, which was much better than that of the unmodified system (0.41 mm in Comparative Example 1), demonstrating the synergistic anti-wear effect of the composite ligand and the modified nano-tungsten source.

[0068] III. Pour Point Test (in accordance with GB / T 3535-2006) 1. Experimental objective: To evaluate the low-temperature fluidity of lubricating oil, requiring a pour point ≤ -35℃.

[0069] 2. Testing equipment: ISO standard pour point test tubes (20mm inner diameter), low temperature cold bath (temperature control accuracy ±0.5℃), thermometer (accuracy ±0.1℃).

[0070] 3. Experimental procedure: Take 50 mL of the sample, filter it through a 0.22 μm filter membrane and transfer it into a test tube, preheat it in a 38°C water bath for 5 minutes; place it in a cold bath and cool it at a rate of 2°C / min. Tilt the test tube at 45° for 5 seconds every time the temperature drops by 3°C, and observe the flow state; Result determination: If the sample can still flow completely at -35°C and the flow time at -40°C ≤ 30 seconds, it is qualified. The pour point of Example 1 is -39°C, which is better than that of the unmodified attapulgite system (-33°C of Comparative Example 3), verifying the effectiveness of the low-temperature improver.

[0071] Sulfated ash test (in accordance with GB / T 2433-2004) 1. Experimental purpose: Control the ash content of the lubricating oil, requiring ≤ 0.3%, to avoid equipment carbon deposition.

[0072] 2. Test method: Weigh 10 g of the sample and place it in a porcelain crucible, slowly heat it on an electric furnace until it burns completely (no black smoke generated); transfer it to a muffle furnace, calcine it at 775 ± 25°C for 4 hours, weigh the residue after cooling; calculate the ash content (residue mass / sample mass × 100%). The sulfated ash of Example 1 is 0.21%, which is much lower than that of the mineral oil system (0.89% of Comparative Example 4), meeting the low-ash environmental protection requirements.

[0073] The performance test results are shown in the following table Analysis of test results Function of nano-tungsten source modification: The wear scar diameter of Example 1 (modified) is reduced by 40% and the pour point is reduced by 7°C compared with Comparative Example 1 (unmodified), proving that γ-mercaptopropyltrimethoxysilane modification can significantly improve the dispersion and coordination activity of the nano-tungsten source, which is the key guarantee for anti-wear performance and low-temperature fluidity.

[0074] Synergistic effect of composite ligands: The wear scar diameter of Example 1 is reduced by 32% compared with Comparative Example 2, indicating that the multidentate synergy of C14-C16 hydroxyoleic acid and amine ligands can enhance the coordination stability, and a single ligand cannot achieve the same anti-wear effect.

[0075] Function of modified attapulgite: The wear scar diameter of Example 1 is reduced by 29% and the pour point is reduced by 6°C compared with Comparative Example 3, indicating that alkyl glycoside modification can improve the compatibility of attapulgite with the base oil and form a synergistic anti-wear network with organotungsten.

[0076] Environmental protection advantages of composite base oil: The biodegradation rate of Example 1 is increased by 200% and the sulfated ash is reduced by 76% compared with Comparative Example 4, verifying that bio-based composite base oil is the core component to achieve high environmental protection.

[0077] In summary, the core components of this invention (modified nano-tungsten source, composite organic ligand, modified attapulgite, and bio-based base oil) work synergistically to achieve simultaneous improvements in environmental friendliness, wear resistance, and low-temperature performance.

[0078] The above are merely embodiments of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention.

Claims

1. An environmentally friendly organic tungsten additive, characterized in that: It is prepared from the following components by weight percentage; Nano-tungsten source: 25%-40%, wherein the nano-tungsten source is tungstic anhydride modified with γ-mercaptopropyltrimethoxysilane; Complex organic ligands: 55%-70%, including a percentage of the total mass of the organic tungsten additives; C14-C16 hydroxyoleic acid 30%-40%, N-methylglycine 15%-20% and N-methyldiethanolamine 10%-15%; Green solvent: 5%-10%, wherein the green solvent is a mixture of propylene glycol and deionized water in a mass ratio of 2:

1.

2. The environmentally friendly organic tungsten additive as described in claim 1, characterized in that: The surface modification step of the tungstate anhydride includes: Nano-sized tungstate anhydride was dispersed in propylene glycol to form a uniform suspension; γ-Mercaptopropyltrimethoxysilane was added to the suspension in an amount of 1%-3% of the mass of the nano-tungsten source. The mixture was transferred to an ultrasonic reactor and ultrasonically treated at 300W power for 30 minutes at 65°C. After ultrasonic treatment, the system was centrifuged at 8000 r / min for 10 minutes to separate solid particles; then the solid particles were placed in a vacuum drying oven at 60℃ for 2 hours to remove residual propylene glycol and obtain modified nano-tungsten source.

3. The environmentally friendly organic tungsten additive as described in claim 1, characterized in that: The preparation method of the organic tungsten additive is as follows: modified nano-tungsten source and composite organic ligand are added to the reaction vessel at a tungsten:ligand molar ratio of 1:2-1:3, and propylene glycol is added as a dispersion medium. The concentration of tungstic anhydride in the system is controlled at a mass fraction of 10%-15%. React for 15-20 minutes in a microwave reactor with a microwave power of 300-500W and a temperature of 80-100℃; After the reaction was completed, the system was centrifuged at 8000 r / min for 15 minutes to separate the solid product. The unreacted ligands were then washed with ethanol 2-3 times to remove the solid product. Finally, the solid product was dried under vacuum at 60℃ to constant weight to obtain the organic tungsten additive.

4. The environmentally friendly organic tungsten additive as described in claim 1, characterized in that: It also includes 2%-8% by weight of a functional auxiliary ligand, said functional auxiliary ligand being selected from at least one of C12 hydroxystearic acid or proline.

5. A lubricating oil containing an organic tungsten additive as described in any one of claims 1-4, wherein the sulfate ash content of the lubricating oil is ≤0.3%, and under extreme pressure testing at 1200 r / min and 392 N using a four-ball machine, its wear scar diameter is ≤0.3 mm, and its pour point is ≤-35°C, characterized in that: Includes the following components by weight percentage: Complex base oil: 80%-90%; Organic tungsten additive: 1%-6%; Synergistic functional additives: 5%-15%.

6. The lubricating oil as described in claim 5, characterized in that: The composite base oil is a blend of bio-based polyalphaolefin and sunflower seed oil methyl ester in a mass ratio of 7:

3.

7. The lubricating oil as described in claim 5, characterized in that: The synergistic functional additive comprises the following components by weight percentage (as a percentage of the total weight of the lubricating oil): Stigmasterol oleate 1%-3%; Polypropylene glycol monostearate 2%-5%; Alkyl glycoside modified attapulgite 2%-7%.

8. The lubricating oil as described in claim 5, characterized in that: The preparation steps of the alkyl glycoside modified attapulgite include: Natural attapulgite is added to deionized water to prepare a slurry with a mass concentration of 5%-20%. The slurry is stirred at 500-800 r / min for 30-60 minutes at room temperature. Then, 1%-3% inorganic acid by mass of attapulgite is added to adjust the pH to 2-4. The slurry is activated at 60-80℃ for 2-4 hours. The activated slurry is separated by centrifugation or filtration, washed with deionized water until neutral, and dried at 80-100℃ for 12-24 hours to obtain pretreated attapulgite. Pretreated attapulgite was dispersed in a mixed solvent of propylene glycol and deionized water to form a suspension with a solid content of 10%-15%. Alkyl glycosides were added, with an amount of 10%-15% of the attapulgite mass. The mixture was stirred at 300-500 r / min for 2-3 hours at 50-70℃. The resulting suspension was washed 2-3 times with ethanol, centrifuged, and then vacuum dried at 60-80℃ for 8-12 hours to obtain alkyl glycoside-modified attapulgite.

9. The lubricating oil as described in claim 5, characterized in that: The method for preparing the lubricating oil includes the following steps: (1) Preparation of composite base oil: Bio-based PAO and sunflower seed oil methyl ester were added to a stirring vessel at a mass ratio of 7:3 and stirred for 30 minutes at 40±5℃ and 300r / min to form a homogeneous composite base oil; (2) Dispersion of nano-additives: Add alkyl glycoside modified attapulgite to the composite base oil in step (1) and ultrasonically disperse for 30 minutes. (3) Microwave-assisted mixing: Environmentally friendly organic tungsten additive, stigmasterol oleate and polypropylene glycol monostearate are added to the system in step (2) in sequence and stirred for 1 hour under microwave assistance; (4) Post-treatment: The mixed system was naturally cooled to room temperature and filtered through a polytetrafluoroethylene filter membrane with a pore size of 0.22 μm to obtain lubricating oil.

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