A grease containing hydrophobically modified nano-SiO2 and its preparation method
Hydrophobically modified nano-SiO2 was prepared by reacting nano-SiO2 with hexamethyldisilazane in situ, which can be used as a grease thickener. This solved the problem of easy oxidation and agglomeration of nano-silica at high temperatures, and achieved efficient thickening and a stable three-dimensional network structure, thus improving the high temperature resistance and dispersibility of the grease.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- APLENE TECHNOLOGY CO LTD (HANGZHOU)
- Filing Date
- 2026-02-10
- Publication Date
- 2026-06-05
AI Technical Summary
Existing greases are prone to oxidation and acid value increase at high temperatures, making it difficult to meet food-grade or high stability requirements. Nano-silica has a wide particle size distribution, many surface defects, and strong hydrophilicity, which leads to agglomeration, low thickening efficiency, and insufficient surface hydroxyl control, making it difficult to form a uniform and stable three-dimensional network structure.
In situ synthesized nano-SiO2 reacts with hexamethyldisilazane, controlling the particle size to 10-50 nm, while retaining some ≡Si-OH, forming hydrophobically modified nano-SiO2, which is used as a thickener in lubricating grease. By combining a moderate balance of hydrophobicity and hydroxyl density, a uniform and stable hydrogen bond network is formed.
It achieves uniform dispersion of nano-SiO2 in non-polar base oil, forming a high-strength three-dimensional network, which improves thickening ability and colloidal stability, and provides excellent extreme pressure anti-wear performance.
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Figure CN122146379A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lubricating grease technology, and more specifically, to a lubricating grease containing hydrophobically modified nano-SiO2 and its preparation method. Background Technology
[0002] Traditional greases often use lithium-based, calcium-based, or complex soaps as thickeners. Although the technology is mature, they have limited high-temperature resistance (dropping point is usually below 200°C), poor biodegradability, and contain metal ions, making it difficult to meet the requirements of high-end applications such as food machinery and high-temperature bearings for environmental protection (such as NSF H1 certification) and thermal stability.
[0003] In recent years, nano-silica has been regarded as an ideal candidate material for non-soap-based thickeners due to its high specific surface area, absence of metal components, excellent high-temperature resistance, and good thixotropic properties. However, its practical application still faces the following key technical obstacles: 1) Raw material and purity issues: Some existing methods use sodium silicate (water glass) as a precursor. Although the cost is low, it inevitably introduces metallic impurities such as sodium ions, which makes the grease easy to oxidize and increase the acid value at high temperatures, failing to meet the requirements of food grade or high stability.
[0004] 2) Difficulty in controlling particle size and dispersibility: If physical pulverization methods (such as ball milling of quartz sand) are used to prepare nano-silica, the resulting particles have a wide particle size distribution (often greater than 100nm), many surface defects, and are prone to severe agglomeration in non-polar base oils due to strong hydrophilicity, making it impossible to form a uniform and stable three-dimensional network structure, resulting in low thickening efficiency.
[0005] 3) Insufficient regulation of surface hydroxyl groups: The thickening ability of nano-silica depends on the hydrogen bonding association between surface silanol groups (≡Si-OH). However, unmodified nano-silica aggregates in base oil due to its strong hydrophilicity, preventing effective hydroxyl groups from participating in network construction. On the other hand, excessive hydrophobic modification significantly reduces the number of hydroxyl groups that can participate in hydrogen bonding, thus weakening the thickening effect. Existing technologies lack a strategy for synergistic optimization of surface hydroxyl density and hydrophobicity.
[0006] While existing Chinese patents (such as CN101240211A and CN116554943A) mention the use of nano-silica in lubricating greases, they do not employ in-situ synthesis processes, making it difficult to control the particle size of silica and consequently, the proportion of modified molecules. Therefore, there is an urgent need for a high-purity, controllable-particle-size nano-silica thickener with moderate surface hydroxyl density and excellent dispersibility, along with a scalable and parameter-defined preparation method, to achieve stable production of high-performance, environmentally friendly lubricating greases. Summary of the Invention
[0007] This invention addresses the shortcomings of existing technologies by providing a grease containing hydrophobically modified nano-SiO2 and its preparation method. The hydrophobically modified nano-SiO2, with a balanced surface hydroxyl density and hydrophobicity, possesses higher thickening ability and can be used as a thickener in greases.
[0008] To achieve the above objectives, the present invention adopts the following technical solution: A grease containing hydrophobically modified nano-SiO2, wherein the grease comprises the following components by mass percentage: Base oil 75-90%, Thickener 8-20%, Additives 0-5%; The thickener includes hydrophobically modified nano-SiO2, and the mass percentage of hydrophobically modified nano-SiO2 in the thickener is ≤100%. The preparation method of the hydrophobic modified nano-SiO2 includes the following steps: mixing dried in-situ synthesized nano-SiO2 with hexamethyldisilazane (HMDS), wherein the weight ratio of in-situ synthesized nano-SiO2 to hexamethyldisilazane is 100:(0.1-1.5); reacting in an oil bath at 60-90℃ to obtain a crude product; washing the crude product with anhydrous ethanol and drying to obtain hydrophobic modified nano-SiO2; The in-situ synthesized nano-SiO2 particles have a size between 10-50 nm. (Oil bath reaction formula: ≡Si-OH + (CH3)3Si-N(Si(CH3)3)2 → ≡Si–O-Si(CH3)3+ H2N(Si(CH3)3)2) Preferably, the base oil is polyalphaolefin synthetic oil (PAO).
[0009] By scientifically controlling the weight ratio of nano-SiO2 to hexamethyldisilazane in in-situ synthesis, 10-40% of the hydroxyl groups on the surface of nano-SiO2 can be replaced to retain most of the ≡Si-OH, thereby achieving a balance between hydrophobicity (contact angle > 120°) and thickening ability.
[0010] Preferably, the oil bath reaction is carried out for 1-3 hours.
[0011] Preferably, the in-situ synthesis method for nano-SiO2 includes the following steps: 1) Premixing: Dissolve alkoxysilane in ethanol, stir, add deionized water and HCl to form a transparent mixture; 2) Hydrolysis-condensation: Stirring, pH maintenance, forming a transparent viscous sol; 3) Purification: Centrifuge and discard the supernatant; wash with deionized water, with the washing solution at pH 7.0; 4) Drying: Vacuum drying yields a white powder, which is nano-silica.
[0012] Preferably, the alkoxysilane is selected from one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate, with ethyl orthosilicate being preferred. Choosing an alkoxysilane as a molecular-level precursor avoids the introduction of metallic impurities, such as sodium silicate.
[0013] Preferably, the pH during the hydrolysis-condensation process is 1-5, more preferably 3-4. Under these pH conditions, the particle size of the synthesized nano-silica can be controlled to be between 10-50 nm.
[0014] Preferably, the additive is selected from at least one of antioxidants, rust inhibitors, dispersants, lubrication improvers, thickeners, detergents and dispersants, preservatives, and extreme pressure agents.
[0015] Preferably, the antioxidant is selected from at least one of phenolic antioxidants, naphthylamine antioxidants, and diphenylamine antioxidants.
[0016] Preferably, the rust inhibitor is selected from at least one of fatty acid soaps, carboxylic acid rust inhibitors, carboxylate rust inhibitors, sulfonic acid metal salts, organic phosphites, organic phosphate esters, amine salts of organic phosphate esters, organophosphate metal salts, alkenyl succinic anhydride, alkenyl succinic acid polyol esters, amine rust inhibitors, fatty acid amines, thiadiazoles and their derivatives, and benzotriazoles and their derivatives.
[0017] Preferably, the dispersant is selected from at least one of aprotic polar solvents, alcohols, and ester surfactants.
[0018] Preferably, the lubricant improver is selected from at least one of thiophosphates, thiocarbamates, thioterpenes, dialkyl thiodipropionates, phosphate esters, and phosphites.
[0019] Preferably, the thickener is selected from at least one of polymethacrylate, olefin copolymer, polyalkylstyrene, and styrene-diene copolymer.
[0020] Preferably, the cleaning and dispersing agent is selected from at least one of succinimide and boron-based succinimide.
[0021] Preferably, the preservative is selected from at least one of benzotriazole compounds and thiazole compounds.
[0022] Preferably, the extreme pressure agent is selected from at least one of phosphorus compounds, zinc dithiophosphate, and organomolybdenum.
[0023] Furthermore, the present invention also provides a method for preparing the aforementioned grease, comprising the following steps: adding hydrophobically modified nano-SiO2 to preheated base oil, stirring, adding additives, stirring evenly, and naturally cooling to obtain thickened grease.
[0024] As a preferred option, after adding hydrophobically modified nano-SiO2 to the preheated base oil, the temperature is controlled at 40-80℃.
[0025] The present invention adopts the above solution, which brings the following beneficial effects: 1) Dispersibility: Moderate hydrophobicity allows hydrophobically modified nano-SiO2 to be uniformly dispersed in non-polar base oil, while the retained hydroxyl groups provide a basis for the subsequent network construction.
[0026] 2) Thickening efficiency: Well-dispersed particles associate through residual hydrogen bonds to form a uniform and strong three-dimensional network with small cone penetration and strong thickening ability.
[0027] 3) Colloidal stability: The hydrogen bond network has moderate reversibility, can resist certain shear and self-repair, and has good colloidal stability.
[0028] 4) Extreme pressure anti-wear properties: The uniformly dispersed nanoparticles and stable network can effectively bear the load and form a stable protective film on the friction surface. Attached Figure Description
[0029] Figure 1 The infrared spectrum of the nano-silica prepared in step S1 of Examples 1-3 is shown.
[0030] Figure 2 The infrared spectrum is that of the modified nano-silica prepared in step S2 of Example 1.
[0031] Figure 3 The infrared spectrum is that of the modified nano-silica prepared in step S2 of Example 2.
[0032] Figure 4 The infrared spectrum is that of the modified nano-silica prepared in step S2 of Example 3. Detailed Implementation
[0033] 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, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention. Example
[0034] S1. Preparation of in-situ synthesized nano-SiO2 (1) Premixing: Dissolve tetraethyl orthosilicate (1.0 mol) in ethanol (4.0 mol) and stir for 10 minutes; add deionized water (4.0 mol) and HCl (0.1 mol) to form a transparent mixture.
[0035] (2) Hydrolysis-condensation: Stir at 25°C for 24 hours (300 rpm), maintain pH between 1 and 5 (pH test paper monitoring), and form a transparent viscous sol (particle size 10-50 nm).
[0036] (3) Purification: Centrifuge at 10,000 rpm for 30 minutes and discard the supernatant; wash 3 times with deionized water (centrifuge at 5,000 rpm), and the pH of the washing solution is 7.0.
[0037] (4) Drying: Vacuum drying at 60℃ for 12 hours to obtain white powder (nano SiO2).
[0038] S2, Preparation of hydrophobically modified nano-SiO2 (1) The dried in-situ synthesized nano-SiO2 was mixed with HMDS at a mass ratio of 100:0.1; (2) Reaction in an oil bath at 80℃ for 2 hours (Reaction formula: ≡Si-OH+(CH3)3Si-N(Si(CH3)3)2 → ≡Si-O-Si(CH3)3+H2N(Si(CH3)3)2); (3) Wash twice with anhydrous ethanol and vacuum dry at 60°C for 6 hours to obtain hydrophobic modified nano SiO2 (contact angle > 120°).
[0039] S3, Preparation of Lubricating Grease Formula: 80% base oil, 15% hydrophobically modified nano-SiO2, and 5% additives.
[0040] Preparation process: Add hydrophobically modified nano-SiO2 to base oil preheated to 40-80℃, stir for 30 minutes, add additives, cool naturally, stir and mix evenly, and then grind with a three-roll mill to obtain thickened grease.
[0041] Additives: 0.8% antioxidant, a mixture of 2',6-di-tert-butyl-p-cresol and dipentyl dithiocarbamate in a mass ratio of 1:1; 2.5% rust inhibitor, a mixture of sorbitol monooleate and barium dinonylnaphthalenesulfonate (T705) in a mass ratio of 2:1; 1.4% extreme pressure agent, a mixture of zinc dialkyl dithiophosphate, Vanlube 829, and molybdenum thiocarbamate in a mass ratio of 1:2:1; 0.3% polymerization inhibitor, copper di-n-butyl dithiocarbamate.
[0042] The infrared spectrum of the dried, in-situ synthesized nano-SiO2 prepared in step S1 of Example 1 is as follows: Figure 1As shown. The spectrum is only at approximately 1100 cm⁻¹. -1 A strong, broad absorption peak appears at 3400-3600 cm⁻¹, attributed to the antisymmetric stretching vibration of the Si-O-Si bond, a characteristic peak of the silica framework. Notably, this peak is also observed in the 3400-3600 cm⁻¹ range. -1 No obvious broad absorption peaks were observed within the range, indicating that after sufficient drying and purification, the physically adsorbed water and most of the silanol groups (≡Si-OH) on the surface of the sample were effectively removed. This provides a pure and consistent starting point for subsequent quantitative and controllable surface modification in this invention, avoiding fluctuations in the degree of modification caused by uncontrollable residual hydroxyl content.
[0043] The infrared spectrum of the hydrophobically modified nano-SiO2 prepared in step S2 of Example 1 is as follows: Figure 2 As shown. With Figure 1 In contrast, the spectrum of the modified sample is at approximately 2960 cm⁻¹. -1 A new characteristic absorption peak appeared at 2960 cm⁻¹. -1 The absorption peak at this point is attributed to the CH asymmetric stretching vibration of -CH3. The appearance of this peak is direct evidence that the trimethylsilyl group (-Si(CH3)3) in HMDS has been successfully grafted onto the surface of nano-silica (forming ≡Si-O-Si(CH3)3). Example
[0044] S1 is the same as S1 in Example 1.
[0045] S2. The preparation steps are the same as S2 in Example 1, except that the mass ratio of dried in-situ synthesized nano-SiO2 to HMDS is 100:0.8.
[0046] S3 is the same as S3 in Example 1.
[0047] The infrared spectrum of the hydrophobically modified nano-SiO2 prepared in step S2 of Example 2 is as follows: Figure 3 As shown. With Figure 1 In contrast, the spectrum of the modified sample is at approximately 2960 cm⁻¹. -1 A new characteristic absorption peak appeared at 2960 cm⁻¹. -1 The absorption peak at this point is attributed to the CH asymmetric stretching vibration of -CH3. The appearance of this peak is direct evidence that the trimethylsilyl group (-Si(CH3)3) in HMDS has been successfully grafted onto the surface of nano-silica (forming ≡Si-O-Si(CH3)3). Example
[0048] S1 is the same as S1 in Example 1.
[0049] S2. The preparation steps are the same as S2 in Example 1, except that the mass ratio of dried in-situ synthesized nano-SiO2 to HMDS is 100:1.5.
[0050] S3 is the same as S3 in Example 1.
[0051] The infrared spectrum of the hydrophobically modified nano-SiO2 prepared in step S2 of Example 3 is as follows: Figure 4 As shown. With Figure 1 In contrast, the spectrum of the modified sample is at approximately 2960 cm⁻¹. -1 A new characteristic absorption peak appeared at 2960 cm⁻¹. -1 The absorption peak at this point is attributed to the CH asymmetric stretching vibration of -CH3. The appearance of this peak is direct evidence that the trimethylsilyl group (-Si(CH3)3) in HMDS has been successfully grafted onto the surface of nano-silica (forming ≡Si-O-Si(CH3)3).
[0052] contrast Figure 2 , Figure 3 , Figure 4 It can be observed that there are significant differences in the relative intensities of the methyl characteristic peaks in the figure. With the increase in the mass ratio of HMDS to nano-SiO2 in the examples (from 100:0.1 in Example 1 to 100:1.5 in Example 3), the intensity of the peak at 2960 cm⁻¹... -1 The peak intensity increases sequentially. This directly reflects the sequential increase in the number of trimethylsilyl groups grafted onto the surface. Example
[0053] S1 is the same as S1 in Example 1.
[0054] S2 is the same as S2 in Example 1.
[0055] S3, Preparation of Lubricating Grease Formula: 86% base oil, 1% lithium dodecyl hydroxystearate, 8% hydrophobically modified nano-SiO2, and 5% additives.
[0056] Preparation process: Base oil and lithium dodecyl stearate are added to the mixing tank in sequence, stirred and mixed and heated to 120°C, hydrophobic modified nano-SiO2 is added, stirred for 30 min, additives are added, and the mixture is cooled naturally. After stirring and mixing evenly, the mixture is milled with three rollers to obtain thickened grease.
[0057] Additives: Same as S3 in Example 1.
[0058] Comparative Example 1: In-situ synthesis of unmodified nano-SiO2 S1, the same as S1 in Example 1, yields in-situ synthesized nano-SiO2.
[0059] S2 is the same as S4 in Example 1, except that in-situ synthesized nano-SiO2 is used to replace hydrophobically modified nano-SiO2.
[0060] S3 is the same as S3 in Example 1. Due to its strong hydrophilicity, it agglomerates severely and is difficult to disperse, resulting in an inability to form an effective web.
[0061] Comparative Example 2: Silane Coupling Agent Modified Nano-SiO2 S1 is the same as S1 in Example 1.
[0062] S2. Silane coupling agent modification: Dry in-situ synthesized nano-SiO2 was dispersed in ethanol, and silane coupling agent KH560 was added dropwise to the solution at a rate of 0.5 g / min. The solution was then stirred at 60 °C for 6 h to obtain silane coupling agent modified nano-SiO2.
[0063] S3 is the same as S3 in Example 4, except that the hydrophobic modified nano-SiO2 is replaced with the silane coupling agent modified nano-SiO2 prepared in Comparative Example S2.
[0064] Comparative Example 3: Siloxane-modified nano-SiO2 S1 is the same as S1 in Example 1.
[0065] S2 is the same as S2 in Example 1, except that hexamethyldisiloxane is used instead of hexamethyldisilazane to obtain siloxane-modified nano-SiO2.
[0066] S3 is the same as S3 in Example 4, except that the hydrophobic modified nano-SiO2 is replaced with the siloxane modified nano-SiO2 prepared in Comparative Example S2.
[0067] Comparative Example 4: Over-modification of hydrophobically modified nano-SiO2 S1 is the same as S1 in Example 1.
[0068] S2. The preparation steps are the same as S2 in Example 1, except that the mass ratio of dried in-situ synthesized nano-SiO2 to HMDS is 100:2.0.
[0069] S3 is the same as S3 in Example 1.
[0070] The basis for testing the physicochemical properties of lubricating grease is as follows: Color: Visually estimated Cone penetration (not in operation): GB / T269 Copper sheet corrosion (T2, 100℃, 24h): GB / T7326 Corrosion resistance (52℃, 48h): GB / T5018 Evaporation rate (99℃, 22h): GB / T7325 Water loss rate (79℃, 1h): SH / T0109 Extreme pressure performance (PD, N): SH / T0202 Four-ball wear (75℃, 1200r / min, 392N, 60min): SH / T0204 Table 1 Physicochemical Properties of Lubricating Grease
[0071] As shown in Table 1, the HMDS-modified nano-silica prepared in situ in this application has a lower cone penetration, less evaporation, and excellent anti-wear properties.
[0072] The thickener in Example 1 of this application is pure HMDS-modified nano-silica (HMDS-modified nano-silica in this document refers to the hydrophobic modified nano-SiO2 of this application). Compared with Example 1, the thickener in Example 4 is a combination of HDMS-modified nano-silica and lithium soap. The test results show that the cone penetration of Example 1 is much smaller than that of Example 4, indicating that the thickening ability of HDMS-modified nano-silica is extremely outstanding, and its thickening ability is much higher than that of lithium soap thickener. In addition, the evaporation is much smaller than that of Example 4, and the PD value is much higher than that of Example 4. The diameter of the four-ball wear scar is smaller than that of Example 4, showing outstanding volatility and anti-wear performance. However, the water leaching loss is slightly higher than that of Example 4, indicating that the water erosion resistance is worse than that of Example 4. Therefore, different thickener ratios can be selected according to the needs of different application scenarios.
[0073] Compared to Example 3, Comparative Example 4 uses HMDS-modified nano-silica as a thickener. It can be seen that the cone penetration is higher than in Example 3, the thickening ability is poor, and the evaporation, water leaching, and anti-wear performance are all worse than in Example 3. Excessive hydrophobic modification disrupts the hydrogen bond network, weakening the thickening effect.
[0074] Compared to Example 4, Comparative Example 1 uses unmodified in-situ synthesized nano-SiO2 and lithium soap composite as thickener. It can be seen that the cone penetration is higher than that of Example 4, the thickening ability is poor, and the evaporation, water loss and anti-wear performance are all worse than those of Example 4.
[0075] Compared to Example 4, Comparative Example 2, which modifies in-situ prepared nano-silica with a silane coupling agent, produces a grease with a higher cone penetration than Example 4 under the same lithium soap content. However, its thickening ability is relatively weaker, and its oil-soap binding is slightly worse than Example 4. Furthermore, its water loss and evaporation test data are inferior to Example 4. The four-ball wear scar diameter and extreme pressure PD value indicate that Example 4 exhibits better anti-wear performance than Comparative Example 2. The reasons for these results may be that the modification of in-situ prepared nano-silica with a silane coupling agent is prone to over-modification, resulting in a fragile network due to insufficient hydroxyl groups, leading to a high cone penetration. This network is easily damaged under mechanical shear or high temperatures, causing oil-soap separation (relatively high water loss). Aggregates or a weak network result in insufficient film strength in the contact area of the friction pair, exhibiting poorer extreme pressure anti-wear performance compared to Example 4.
[0076] Compared to Example 4, Comparative Example 3, which modifies in-situ synthesized nano-silica with siloxane, produced a grease with the same amount of lithium soap. The test results showed that its thickening ability, evaporation rate, water erosion resistance, and anti-wear properties were all inferior to those of Example 4. The reason for this may be that although hexamethyldisiloxane introduces similar groups onto the surface of nano-silica in the same way as hexamethyldisilazane, there are certain differences. Siloxane bonds are more stable and extremely difficult to react with the hydroxyl groups on the silica surface under normal conditions, ultimately resulting in weak thickening ability and performance similar to unmodified nano-silica.
[0077] Comparing Example 1 and Comparative Example 1 with Example 2 and Comparative Example 2, it can be found that, with the same amount of soap, the sample prepared in situ using this method to modify HMDS nano-silica has a smaller cone penetration and stronger thickening ability. At the same time, because the particle size of the in-situ synthesized nano-silica is relatively controllable and uniform, the oil-soap binding degree is better, which improves the water loss and evaporation to a certain extent compared with the original sample. In addition, the smaller particle size also improves the friction and extreme pressure performance of the solid particles, thus the four-ball wear scar and extreme pressure PD also yielded better results.
[0078] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.
Claims
1. A lubricating grease containing hydrophobically modified nano-SiO2, characterized in that, The composition of the grease, by mass percentage, includes the following components: Base oil 75-90%, Thickener 8-20%, Additives 0-5%; The thickener includes hydrophobically modified nano-SiO2, and the mass percentage of hydrophobically modified nano-SiO2 in the thickener is ≤100%. The preparation method of the hydrophobic modified nano-SiO2 includes the following steps: mixing dried in-situ synthesized nano-SiO2 with hexamethyldisilazane, wherein the weight ratio of in-situ synthesized nano-SiO2 to hexamethyldisilazane is 100:(0.1-1.5); reacting in an oil bath at 60-90℃ to obtain a crude product; washing the crude product with anhydrous ethanol and drying to obtain hydrophobic modified nano-SiO2; The in-situ synthesized nano-SiO2 particles have a size between 10-50 nm.
2. The lubricating grease containing hydrophobically modified nano-SiO2 according to claim 1, characterized in that, The base oil is polyalphaolefin synthetic oil (PAO).
3. The lubricating grease containing hydrophobically modified nano-SiO2 according to claim 1, characterized in that, The oil bath reaction lasts for 1-3 hours.
4. The lubricating grease containing hydrophobically modified nano-SiO2 according to claim 1, characterized in that, The method for preparing in-situ synthesized nano-SiO2 includes the following steps: 1) Premixing: Dissolve alkoxysilane in ethanol, stir, add deionized water and HCl to form a transparent mixture; 2) Hydrolysis-condensation: Stirring, pH maintenance, forming a transparent viscous sol; 3) Purification: Centrifuge and discard the supernatant; wash with deionized water, with the washing solution at pH 7.0; 4) Drying: Vacuum drying yields a white powder, which is nano-silica.
5. The lubricating grease containing hydrophobically modified nano-SiO2 according to claim 4, characterized in that, The alkoxysilane is selected from one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate, preferably ethyl orthosilicate.
6. The lubricating grease containing hydrophobically modified nano-SiO2 according to claim 4, characterized in that, The pH during the hydrolysis-condensation process is 1-5, preferably 3-4.
7. The lubricating grease containing hydrophobically modified nano-SiO2 according to claim 1, characterized in that, The additive is selected from at least one of antioxidants, rust inhibitors, dispersants, lubrication improvers, thickeners, detergents and dispersants, corrosion inhibitors, and extreme pressure agents; Preferably, the antioxidant is selected from at least one of phenolic antioxidants, naphthylamine antioxidants, and diphenylamine antioxidants; Preferably, the rust inhibitor is selected from at least one of fatty acid soaps, carboxylic acid rust inhibitors, carboxylate rust inhibitors, sulfonic acid metal salts, organic phosphites, organic phosphate esters, amine salts of organic phosphate esters, organophosphate metal salts, alkenyl succinic anhydride, alkenyl succinic acid polyol esters, amine rust inhibitors, fatty acid amines, thiadiazoles and their derivatives, and benzotriazoles and their derivatives. Preferably, the dispersant is selected from at least one of aprotic polar solvents, alcohols, and ester surfactants; Preferably, the lubricant improver is selected from at least one of thiophosphates, thiocarbamates, thioterpenes, dialkyl thiodipropionates, phosphate esters, and phosphites. Preferably, the thickener is selected from at least one of polymethacrylate, olefin copolymer, polyalkylstyrene, and styrene-diene copolymer; Preferably, the detergent dispersant is selected from at least one of succinimide and boron-based succinimide; Preferably, the preservative is selected from at least one of benzotriazole compounds and thiazole compounds; Preferably, the extreme pressure agent is selected from at least one of phosphorus compounds, zinc dithiophosphate, and organomolybdenum.
8. The method for preparing the lubricating grease according to any one of claims 1-7, characterized in that, Includes the following steps: Add hydrophobically modified nano-SiO2 to preheated base oil, stir, add additives, stir evenly, and allow to cool naturally to obtain thickened grease.
9. The method for preparing the lubricating grease according to claim 8, characterized in that, After adding hydrophobically modified nano-SiO2 to the preheated base oil, the temperature is controlled at 40-80℃.