High-pressure wear-resistant hydraulic oil and method for producing same

Abstract

The application belongs to the field of hydraulic oil, and particularly relates to a high-pressure wear-resistant hydraulic oil and a preparation method thereof. The hydraulic oil comprises, by weight, 90-100 parts of base oil, 1-3 parts of modified nano-alumina anti-wear agent, 0.1-1 part of antioxidant, 0.1-1 part of detergent, 0.1-0.5 part of anti-rust agent, 0.1-0.5 part of metal deactivator and 0.01-0.1 part of defoaming agent. The dispersion stability of the nano-alumina in the base oil is significantly improved through the synergistic effect of multi-point anchoring, steric hindrance and pi-pi stacking of the double-benzimidazole salt, the hydraulic oil is endowed with excellent high-pressure wear resistance, oxidation resistance and long service life characteristics, and can be widely applied to high-pressure hydraulic systems.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic oil, specifically relating to a high-pressure anti-wear hydraulic oil and its preparation method. Background Technology

[0002] Hydraulic transmission technology, due to its advantages of high power density, fast response speed, and high control precision, has been widely used in high-pressure and heavy-duty fields such as engineering machinery, metallurgy and mining, aerospace, and deep-sea drilling. As the working pressure of hydraulic systems develops towards 35MPa and even higher levels, hydraulic oil not only serves as an energy transmission medium but also needs to build a stable and durable lubricating protective film between key friction pairs such as high-pressure pumps, valve cores, and hydraulic cylinders to prevent adhesive wear and fatigue spalling caused by direct metal-to-metal contact. Therefore, developing high-pressure anti-wear hydraulic oils with high extreme pressure carrying capacity, excellent viscosity-temperature properties, and good environmental compatibility has become an important research direction in the field of lubrication technology.

[0003] For a long time, zinc dialkyl dithiophosphate (ZDDP) has been the most widely used extreme pressure anti-wear agent in industrial anti-wear hydraulic oils. Since its introduction in the 1940s, ZDDP has dominated the hydraulic oil additive market due to its multifunctional properties of anti-oxidation, anti-corrosion, and anti-wear, as well as its low cost. However, with increasingly stringent environmental regulations and the continuous improvement of the precision of hydraulic systems, the inherent defects of ZDDP have become increasingly prominent. First, ZDDP contains the heavy metal zinc, and its hydrolysis and thermal decomposition products have potential ecotoxicity to water and soil, and are increasingly restricted by environmental regulations such as REACH. Second, ZDDP is prone to decomposition under high temperature and high pressure conditions, producing sludge and varnish, which can cause precision hydraulic valve core jamming and filter clogging, and in severe cases, can lead to system pressure fluctuations and failures. Therefore, developing zinc-free or low-zinc high-efficiency extreme pressure anti-wear systems to replace or partially replace ZDDP has become an urgent need for the technological upgrading of high-pressure hydraulic oils. Patent CN118344356A discloses a phosphate ester amine salt ionic liquid, which, by introducing benzothiazole derivatives into the phosphate ester amine salt structure, endows it with good anti-wear, friction-reducing, and rust-preventing properties, and can be used as a core anti-wear agent to replace ZDDP in ashless hydraulic oil. Patent CN106947571A discloses an ionic liquid-modified zinc sulfide nano-extreme pressure anti-wear agent, which utilizes imidazole ionic liquids to modify the surface of zinc sulfide nanoparticles and disperses them in base oil to prepare energy-saving anti-wear hydraulic oil. However, zinc sulfide nanoparticles may decompose and release toxic gases such as sulfur dioxide or hydrogen sulfide under frictional high temperatures, resulting in poor environmental friendliness and safety; secondly, they are prone to agglomeration and sedimentation in oil phases with significant polarity differences, leading to generally poor wear resistance.

[0004] Nanomaterials, due to their unique quantum size effect, surface effect, and macroscopic quantum tunneling effect, have shown great application potential in the field of hydraulic oil anti-wear and friction reduction. Nano-alumina (Al2O3) possesses advantages such as high hardness, excellent chemical stability, good thermal conductivity, wide availability of raw materials, and controllable cost, making it considered one of the most promising nano-anti-wear agents. However, nano-alumina particles have a large specific surface area, extremely high surface energy, and a large number of unsaturated hydroxyl groups on their surface. In hydrocarbon base oils, they are prone to agglomeration and sedimentation due to van der Waals forces, hydrogen bonding, and capillary forces, resulting in extremely poor dispersion stability in hydraulic oils. Agglomeration of nanoparticles not only significantly reduces their anti-wear performance but may also clog precision filters and servo valves in hydraulic systems, leading to serious equipment failures.

[0005] Therefore, developing a high-pressure anti-wear hydraulic oil that combines excellent dispersion stability and high-pressure anti-wear performance is of great significance for improving the operational reliability and service life of high-end hydraulic equipment under extreme working conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a high-pressure anti-wear hydraulic oil and its preparation method, to solve the problems of poor dispersion stability and poor anti-wear performance of nano-anti-wear agents in base oils in the prior art. To achieve the above objective, this invention adopts the following technical solution:

[0007] A high-pressure anti-wear hydraulic oil, by weight, comprises the following components:

[0008] Base oil: 90-100 parts;

[0009] Modified nano-alumina anti-wear agent: 1-3 parts;

[0010] Antioxidant: 0.1~1 part;

[0011] Cleaning agent: 0.1~1 part;

[0012] Rust inhibitor: 0.1~0.5 parts;

[0013] Metal deactivating agent: 0.1~0.5 parts;

[0014] Defoamer: 0.01~0.1 parts;

[0015] The modified nano-alumina anti-wear agent is prepared by adding nano-alumina and 1,1-propenylbis(3-hexylbenzimidazole) hexafluorophosphate into an alcohol solvent, ultrasonically dispersing, and mechanically ball milling to obtain the modified nano-alumina anti-wear agent.

[0016] The structural formula of the 1,1-propenylbis(3-hexylbenzimidazole) hexafluorophosphate is: .

[0017] In some embodiments, the base oil is a mixture of API-III hydrotreated base oil and API-IV polyalphaolefin base oil, wherein the mass ratio of API-III hydrotreated base oil to API-IV polyalphaolefin base oil is (3-5):1.

[0018] In some embodiments, the API-III hydrotreated base oil is API-III 100N hydrotreated base oil or API-III 150N hydrotreated base oil; the API-IV polyalphaolefin base oil is PAO6, PAO8, PAO4, PAO10, PAO40 or PAO100.

[0019] In some embodiments, the antioxidant is a mixture of amine antioxidant and phenolic antioxidant, wherein the mass ratio of the amine antioxidant to the phenolic antioxidant is (1~3):1.

[0020] In some embodiments, the amine antioxidant is selected from BASF Irganox L57, BASF Irganox L06 and BASF Irganox L67; the phenolic antioxidant is selected from BASF Irganox L135, BASF Irganox L115, BASF Irganox L101 and BASF Irganox L107.

[0021] In some embodiments, the detergent is selected from one or more of alkylphenol calcium salts, calcium salicylate salts, and calcium sulfonate salts. Preferably, the detergent is alkylphenol calcium T115B or Wuxi Nanfang T109A.

[0022] In some embodiments, the rust inhibitor is neutral dinonylnaphthalenesulfonate barium or neutral dinonylnaphthalenesulfonate zinc.

[0023] In some embodiments, the metal deactivator is a thiadiazole derivative or a benzotriazole derivative; the defoamer is a composite defoamer T921 or an organosilicon defoamer T901.

[0024] In some embodiments, the metal deactivator is a thiadiazole derivative T561, a benzotriazole derivative T551, or BASF Irgamet 39.

[0025] This invention also provides a method for preparing the above-mentioned high-pressure anti-wear hydraulic oil, characterized by comprising the following steps:

[0026] Add the base oil to the mixing vessel, heat it to 50~90℃, turn on the mechanical stirrer, and add the modified nano alumina anti-wear agent, detergent, rust inhibitor, metal deactivator and antioxidant in sequence, and stir for 20~60 min; then add the defoamer and continue stirring for 10~30 min; cool to room temperature to obtain high pressure anti-wear hydraulic oil.

[0027] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0028] (1) This invention innovatively uses 1,1-propenylbis(3-hexylbenzimidazole) hexafluorophosphate to modify the surface of nano-alumina. This bisbenzimidazole salt has two cations, which can form a two-site anchoring on the surface of nano-alumina, and the adsorption energy is significantly higher than that of conventional monoimidazolium salts; the rigid planar structure of the benzimidazole ring and the benzene ring conjugated system can interact strongly with the surface of nano-alumina through π-π stacking, which further enhances the firmness and thermal stability of the surface modification layer, making the modified layer less likely to fall off under high pressure shear and high temperature conditions.

[0029] (2) The long-chain hexyl group of the 1,1-propenylbis(3-hexylbenzimidazole) hexafluorophosphate of the present invention faces outward, forming a thick hydrophobic coating layer around the nanoparticles, resulting in a significant steric hindrance effect; the dual-cationic structure gives the particle surface a higher charge density, forming a stronger electrostatic repulsion effect. The two work together to effectively prevent the nanoparticles from approaching, colliding and agglomerating. The hexafluorophosphate anion has good structural similarity and compatibility with hydrocarbon base oils, promoting the uniform dispersion and long-term suspension stability of the modified nanoparticles in the oil phase. In addition, the benzimidazole ring has excellent thermal stability and load-bearing capacity. Its electron-rich nitrogen atoms can coordinate with the metal friction surface to form a strong boundary lubrication film; the nano-alumina particles fill the micro-pits and scratches on the friction surface, thereby significantly improving the maximum non-seize load of the hydraulic oil and reducing the wear scar diameter, thus giving the hydraulic oil excellent comprehensive performance and meeting the stringent requirements of high-pressure hydraulic systems. Detailed Implementation

[0030] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention. It should be noted that any aspects not described in detail in this invention are conventional practices in the art and are not the focus of this invention.

[0031] Furthermore, regarding numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art described herein. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0032] Preparation Example 1: Preparation of 1,1-propenylbis(3-hexylbenzimidazole)hexafluorophosphate ,

[0033] Step 1: N-hexylbenzimidazole (0.25 mol) and 1-bromo-3-chloropropane (0.1 mol) were added to acetonitrile (200 mL), and the mixture was heated to 85 °C and stirred under reflux for 24 h. After the reaction was completed, the solvent was evaporated under reduced pressure, and the residue was washed with 1,4-dioxane to obtain 1,1-propenebis(3-hexylbenzimidazole)bromochloride, which was used directly in the next step.

[0034] The obtained 1,1-propenylbis(3-hexylbenzimidazole) bromide chloride salt, KPF6 (0.25 mol), and methanol (150 mL) were added to a reactor and stirred at room temperature for 24 h. A solid precipitated, was filtered, the filter cake was washed with distilled water and dried to obtain the crude product. The crude product was recrystallized from acetone to obtain 1,1-propenylbis(3-hexylbenzimidazole) hexafluorophosphate as a white solid with a yield of 70.3%.

[0035] 1 H-NMR (500 MHz, DMSO-d6): δ (ppm): 0.88 (6H, t), 1.30-1.39 (12H, m ), 1.88-1.95 (4H, m ), 2.58-2.68 (2H, m), 4.61 (4H, t), 4.67 (4H, t ), 7.65-7.76 (4H, m), 8.05-8.14 (4H, m), 9.54 (2H, s).

[0036] Preparation Example 2: Preparation of Modified Nano-Alumina Anti-wear Agent

[0037] Nano-alumina (50 nm, 50 g) and 1,1-propenylbis(3-hexylbenzimidazole) hexafluorophosphate (50 g) obtained in Preparation Example 1 were added to ethanol (100 mL) solvent and ultrasonically dispersed for 30 min. The mixture was then transferred to a ball mill jar and mechanically ball-milled at 400 rpm for 0.5 h. After ball milling, the product was dried in a vacuum drying oven at 60 °C until constant weight, and then ground to obtain a white powder of modified nano-alumina anti-wear agent.

[0038] Example 1

[0039] A high-pressure anti-wear hydraulic oil, by weight, comprises the following components:

[0040] Base oil (a blend of Group III 150N hydrotreated base oil and PAO8 at a mass ratio of 4:1): 95 parts;

[0041] Preparation of the modified nano-alumina anti-wear agent obtained in Example 2: 1.5 parts;

[0042] Antioxidant (BASF Irganox L57 and BASF Irganox L135 in a mass ratio of 2:1): 0.5 parts;

[0043] Detergent (alkylphenol calcium sulfide T115B): 0.5 parts;

[0044] Rust inhibitor (barium dinonylnaphthalenesulfonate T705A): 0.1 parts;

[0045] Metal deactivator (benztriazole derivative T551): 0.1 parts;

[0046] Defoamer (organosilicon defoamer T901, Jinzhou Shengda): 0.05 parts.

[0047] The preparation method of the above-mentioned hydraulic oil includes the following steps:

[0048] Add the base oil to the mixing vessel, heat it to 60°C, turn on the mechanical stirrer (500 rpm), and add the modified nano alumina anti-wear agent, detergent, rust inhibitor, metal deactivator and antioxidant in sequence, and stir for 30 min; then add the defoamer and continue stirring for 20 min; cool to room temperature to obtain high pressure anti-wear hydraulic oil.

[0049] Example 2

[0050] A high-pressure anti-wear hydraulic oil, by weight, comprises the following components:

[0051] Base oil (a blend of Group III 150N hydrotreated base oil and PAO8 at a mass ratio of 5:1): 95 parts;

[0052] Preparation of the modified nano-alumina anti-wear agent obtained in Example 2: 1.2 parts;

[0053] Antioxidant (BASF Irganox L06 and BASF Irganox L115 in a mass ratio of 3:1): 0.5 parts;

[0054] Detergent (alkylphenol calcium sulfide T115B): 0.5 parts;

[0055] Rust inhibitor (barium dinonylnaphthalenesulfonate T705A): 0.1 parts;

[0056] Metal deactivator (benzotriazole derivative T551): 0.08 parts;

[0057] Defoamer (organosilicon defoamer T901, Jinzhou Shengda): 0.03 parts.

[0058] The preparation method of the above-mentioned hydraulic oil includes the following steps:

[0059] Add the base oil to the mixing vessel, heat it to 70°C, turn on the mechanical stirrer (500 rpm), and add the modified nano alumina anti-wear agent, detergent, rust inhibitor, metal deactivator, and antioxidant in sequence, and stir for 30 min; then add the defoamer and continue stirring for 20 min; cool to room temperature to obtain high-pressure anti-wear hydraulic oil.

[0060] Example 3

[0061] A high-pressure anti-wear hydraulic oil, by weight, comprises the following components:

[0062] Base oil (a blend of Group III 150N hydrotreated base oil and PAO8 at a mass ratio of 4:1): 100 parts;

[0063] Preparation of the modified nano-alumina anti-wear agent obtained in Example 2: 1.5 parts;

[0064] Antioxidant (BASF Irganox L06 and BASF Irganox L115 in a mass ratio of 3:1): 0.5 parts;

[0065] Detergent (calcium salicylate, Wuxi Nanfang T109A): 0.5 parts;

[0066] Rust inhibitor (zinc dinonylnaphthalenesulfonate, Vanlube® RI-ZSN): 0.1 parts;

[0067] Metal deactivator (thiadiazole derivative T561): 0.1 parts;

[0068] Defoamer (compound defoamer T921): 0.05 parts.

[0069] The preparation method of the above-mentioned hydraulic oil includes the following steps:

[0070] Add the base oil to the mixing vessel, heat it to 70°C, turn on the mechanical stirrer (500 rpm), and add the modified nano alumina anti-wear agent, detergent, rust inhibitor, metal deactivator, and antioxidant in sequence, and stir for 30 min; then add the defoamer and continue stirring for 20 min; cool to room temperature to obtain high-pressure anti-wear hydraulic oil.

[0071] Comparative Example 1

[0072] Based on Preparation Example 2, 1,1-propenylbis(3-hexylbenzimidazole) hexafluorophosphate was replaced with The other steps and operations are the same as in Preparation Example 2, to obtain the modified nano-alumina anti-wear agent X.

[0073] Based on Example 1, the modified nano-alumina anti-wear agent was replaced with the aforementioned modified nano-alumina anti-wear agent X. Other steps and operations were the same as in Example 1.

[0074] Performance testing

[0075] The hydraulic oils obtained in Examples 1-3 and Comparative Example 1 were subjected to relevant performance tests. The test methods and standards are as follows:

[0076] (1) Kinematic viscosity and viscosity index: The kinematic viscosity at 40℃ was determined according to GB / T 265-1988 "Determination of kinematic viscosity and calculation of dynamic viscosity of petroleum products", and the viscosity index was calculated according to GB / T 1995-1998.

[0077] (2) Pour point: Determined according to GB / T 3535-2025 "Determination of Pour Point of Petroleum Products";

[0078] (3) Open cup flash point: determined according to GB / T 3536-2008 "Determination of flash point and fire point of petroleum products - Cleveland open cup method";

[0079] (4) Load-bearing capacity and wear resistance: The maximum non-seize load (PB value, test conditions: rotation speed 1450 r / min, room temperature, 10 s) and wear scar diameter (WS1.4, test conditions: 392 N, 1200 r / min, 75℃, 60 min) were determined according to GB / T 3142-2019 "Determination of load-bearing capacity of lubricants by four-ball method".

[0080] (5) Dispersion stability: The hydraulic oil sample was left to stand at room temperature for 30 days, and the sedimentation of nanoparticles was observed and recorded;

[0081] The test results are shown in Table 1.

[0082] Table 1 Test Results ,

[0083] As shown in Table 1, the PB values ​​of Examples 1-3 of the present invention are as high as 1428 N, 1305 N, and 1367 N, respectively, which are higher than 850 N of Comparative Example 1. This indicates that the nano-alumina anti-wear agent modified with 1,1-propenylbis(3-hexylbenzimidazole) hexafluorophosphate of the present invention can form a more robust boundary lubrication film with stronger load-bearing capacity on the surface of the friction pair. In addition, in terms of wear scar diameter, Examples 1-3 are only 0.27 mm, 0.32 mm, and 0.30 mm, respectively, which are lower than Comparative Example 1 (0.52 mm), indicating a significant anti-wear and friction-reducing effect.

[0084] Regarding low-temperature fluidity, the pour points of Examples 1-3 of this invention are as low as -34℃, -37℃, and -35℃, respectively, which are lower than those of Comparative Example 1. This is mainly because 1,1-propenylbis(3-hexylbenzimidazole)hexafluorophosphate forms a complete and dense organic modification layer on the surface of nano-alumina, effectively shielding the strong polar hydroxyl groups on the surface of nanoparticles and preventing the flocculation network structure formed between particles due to hydrogen bonding. This reduces the interference of nano-aggregates on the orderly arrangement of base oil molecules at low temperatures, significantly improving the low-temperature pumping performance and cold-start fluidity of hydraulic oil.

[0085] Regarding thermal safety, the open flash points of Examples 1-3 of this invention are 232℃, 238℃, and 235℃, respectively, all higher than Comparative Example 1 (201℃). This is mainly because 1,1-propenylbis(3-hexylbenzimidazole)hexafluorophosphate has extremely low vapor pressure and excellent thermal stability. After it is firmly coated on the surface of nanoparticles, it effectively inhibits the catalytic activity of nano-alumina on the oxidative cracking of base oil at high temperatures. At the same time, the uniformly dispersed nanoparticles increase the specific heat capacity and thermal conductivity of the oil, delaying the formation of local hot spots, thereby improving the safety of hydraulic oil use.

[0086] Regarding dispersion stability, Examples 1-3 of the present invention remained uniform and transparent without any visible precipitation after standing at room temperature for 30 days, while Comparative Example 1 showed obvious stratification with bottom precipitation. This indicates that the dicationic and long-chain hexyl substituents of 1,1-propenylbis(3-hexylbenzimidazole)hexafluorophosphate produced stronger electrostatic stabilization and steric hindrance effects, effectively inhibiting the aggregation and sedimentation of nano-alumina.

[0087] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A high-pressure anti-wear hydraulic oil, characterized in that, By weight, its raw materials include the following components: Base oil: 90-100 parts; Modified nano-alumina anti-wear agent: 1-3 parts; Antioxidant: 0.1~1 part; Cleaning agent: 0.1~1 part; Rust inhibitor: 0.1~0.5 parts; Metal deactivating agent: 0.1~0.5 parts; Defoamer: 0.01~0.1 parts; The modified nano-alumina anti-wear agent is prepared by adding nano-alumina and 1,1-propenylbis(3-hexylbenzimidazole) hexafluorophosphate into an alcohol solvent, ultrasonically dispersing, and mechanically ball milling to obtain the modified nano-alumina anti-wear agent. The structural formula of the 1,1-propenylbis(3-hexylbenzimidazole) hexafluorophosphate is: .

2. The high-pressure anti-wear hydraulic oil according to claim 1, characterized in that, The base oil is a mixture of API-III hydrotreated base oil and API-IV polyalphaolefin base oil, with a mass ratio of API-III hydrotreated base oil to API-IV polyalphaolefin base oil of (3-5):

1.

3. The high-pressure anti-wear hydraulic oil according to claim 2, characterized in that, The API-III hydrotreated base oil is API-III 100N hydrotreated base oil or API-III 150N hydrotreated base oil; the API-IV polyalphaolefin base oil is PAO6, PAO8, PAO4, PAO10, PAO40 or PAO100.

4. The high-pressure anti-wear hydraulic oil according to claim 1, characterized in that, The antioxidant is a mixture of amine antioxidant and phenolic antioxidant, and the mass ratio of the amine antioxidant to the phenolic antioxidant is (1~3):

1.

5. The high-pressure anti-wear hydraulic oil according to claim 4, characterized in that, The amine-type antioxidants are selected from BASF Irganox L57, BASF Irganox L06 and BASF Irganox L67; the phenol-type antioxidants are selected from BASF Irganox L135, BASF Irganox L115, BASF Irganox L101 and BASF Irganox L107.

6. The high-pressure anti-wear hydraulic oil according to claim 1, characterized in that, The detergent is selected from one or more of alkylphenol calcium salts, calcium salicylate salts, and calcium sulfonate salts.

7. The high-pressure anti-wear hydraulic oil according to claim 1, characterized in that, The rust inhibitor is neutral dinonylnaphthalenesulfonate barium or neutral dinonylnaphthalenesulfonate zinc.

8. The high-pressure anti-wear hydraulic oil according to claim 1, characterized in that, The metal deactivator is a thiadiazole derivative or a benzotriazole derivative; the defoamer is a composite defoamer T921 or an organosilicon defoamer T901.

9. The high-pressure anti-wear hydraulic oil according to claim 8, characterized in that, The metal deactivator is a thiadiazole derivative T561, a benzotriazole derivative T551, or BASF Irgamet 39.

10. A method for preparing the high-pressure anti-wear hydraulic oil according to any one of claims 1 to 9, characterized in that, Includes the following steps: Add the base oil to the mixing vessel, heat it to 50~90℃, turn on the mechanical stirrer, and add the modified nano alumina anti-wear agent, detergent, rust inhibitor, metal deactivator and antioxidant in sequence, and stir for 20~60 min; then add the defoamer and continue stirring for 10~30 min; cool to room temperature to obtain high pressure anti-wear hydraulic oil.

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