Gear lubricating grease composition and preparation method thereof

Abstract

The invention relates to the technical field of lubricating grease, and particularly discloses a gear lubricating grease composition and a preparation method thereof. The invention relates to a gear lubricating grease composition which comprises the following components in percentage by mass: 70-85% of base oil, 8-16% of a thickening agent, 3.5-10.7% of modified nano silicon dioxide and 3-10% of an additive, the base oil is poly-alpha-olefin synthetic oil and ester oil in a mass ratio of 1: (0.1-0.3); the thickening agent comprises silane-terminated polyether, 12-hydroxystearic acid and lithium hydroxide in a mass ratio of 1: (8-12): (15-21). The gear lubricating grease composition can be used for lubricating an electric shovel gear in an extremely cold low-temperature environment, has excellent low-temperature fluidity and pumpability, and can provide a continuous and stable lubricating effect for low-temperature operation of an electric shovel.

Description

Technical Field

[0001] The present application relates to the technical field of lubricating grease, and more specifically, to a gear lubricating grease composition and a preparation method thereof. Background Art

[0002] The electric shovel, also known as a mechanical single-bucket excavator, is mainly used for stripping of surface objects in mines and mining and loading of ores. The electric shovel has a high operating rate and low operating cost, and is one of the main large-scale equipment for open-pit mining. The electric shovel is composed of four major mechanical systems: the pushing system, the lifting system, the rotary system, and the walking system, as well as two auxiliary systems: the air system and the automatic lubrication system. In the automatic lubrication system of the electric shovel, the most critical issue is the lubrication of the open gears.

[0003] The power of the open gear of the electric shovel comes from the interaction and relative movement of each pair of meshing tooth surfaces in the gear mechanism, which can transmit very high torque. The roughness of its tooth surface is relatively high, and the working conditions are harsh. During startup, normal operation and shutdown, the open gear is usually in a state of boundary friction or mixed friction, so the tooth surface will be subjected to extremely high stress. If it cannot be effectively lubricated, the friction and contact stress between the meshing gear teeth will cause the temperature of the micro-convex bodies on the contacting tooth surfaces to rise sharply, causing the two tooth surfaces to stick or even weld, causing fatigue wear of the gears, and eventually leading to tooth breakage.

[0004] Therefore, preparing an open gear grease with excellent performance that meets the lubrication requirements of the open gears of the electric shovel can effectively extend the service life of the open gears of the electric shovel, reduce spare parts loss and downtime losses, and improve the overall long-term operating stability of the equipment, which is crucial for large open gear transmission devices with low speed, heavy load and huge torque transmission.

[0005] With respect to the above-mentioned related technologies, the inventors found that the electric shovel gear grease in the prior art can provide good lubrication protection at room temperature. However, under low temperature conditions, especially in cold areas where the temperature can be as low as -40°C in winter, the fluidity of the gear grease will drop sharply, and it will easily thicken or even solidify. This directly leads to a sharp drop in the pumpability of the grease, causing the lubrication system to be blocked, and the lubrication system has difficulty in effectively delivering the grease to the gear parts. On the one hand, the gears cannot be fully lubricated, which aggravates the wear of the gears and shortens the service life of the equipment; on the other hand, the lubrication pump will often send out fault signals during operation, seriously affecting the operating efficiency. In addition, the extreme pressure and adhesion of the grease will also be reduced under low temperature conditions, and it will not be able to provide continuous and effective lubrication protection for the electric shovel gears. Summary of the invention

[0006] In order to improve the low-temperature fluidity and pumpability of gear grease and enhance the lubrication performance of gear grease at low temperatures, the present application provides a gear grease composition and a preparation method thereof.

[0007] In a first aspect, the present application provides a gear grease composition, which adopts the following technical solution: A gear grease composition, wherein the components include, by mass percentage, 70-85% of base oil, 8-16% of thickener, 3.5-10.7% of modified nano-silicon dioxide and 3-10% of additives; The base oil is a poly-alpha-olefin synthetic oil and an ester oil in a mass ratio of 1:(0.1-0.3); The thickener comprises silane-terminated polyether, 12-hydroxystearic acid and lithium hydroxide in a mass ratio of 1:(8-12):(15-21).

[0008] By adopting the above technical solution, poly-α-olefin synthetic oil as a synthetic hydrocarbon base oil has good high and low temperature performance and can maintain good low temperature fluidity and viscosity at low temperatures. The addition of a small amount of ester oil can further adjust the viscosity-temperature properties of the base oil, so that the grease can still maintain good viscosity characteristics at lower temperatures.

[0009] The silane-terminated polyether structure retains the long flexible polyether chain, which is combined with lithium stearate soap as a thickener, significantly improving the low-temperature resistance of the thickener. The long flexible polyether chain can significantly improve the flexibility of the grease, making it difficult for the grease to crystallize or solidify at low temperatures, reducing the resistance of the grease during transportation, and thus effectively improving the low-temperature pumpability of the grease. The long flexible polyether chain can maintain good fluidity in low-temperature environments, reduce the low-temperature similar viscosity of the grease, and help the grease to be better distributed and penetrated under extremely cold low-temperature conditions.

[0010] Silane-terminated polyether also has excellent weather resistance and water resistance, has good wetting ability on the metal substrate of the gear, and can produce good adhesion to the substrate, which enables the grease to maintain good adhesion at low temperatures and form a uniform lubricating film on the gear surface, providing continuous and effective lubrication protection for the electric shovel gears.

[0011] Nano-silicon dioxide is introduced as a nano solid lubricant to improve the thixotropy of grease, making it easier to flow and pump at low temperatures, and quickly restore its original structure after the shear force is removed. Spherical nano-silicon dioxide can effectively reduce the friction coefficient of composite lithium-based grease, improve the colloidal stability and skeleton structure stability of the system, enhance the boundary lubrication effect, and provide additional protection even if the oil film is destroyed at low temperatures, thereby improving the low-temperature extreme pressure and anti-wear properties of the grease.

[0012] After the nano-silica is modified and mixed with the thickener, the silane-terminated polyether can form a chemical interaction with the modified nano-silica. The tiny particles of nano-silica can serve as the "anchor point" of the silane-terminated polyether chain, enhancing the dispersion stability and uniformity of the raw material in the grease. At the same time, the flexible chain segments of the silane-terminated polyether chain can also better wrap the nano-silica particles, forming a stable lubricating film, significantly reducing the agglomeration between the nano-silica particles.

[0013] Optionally, the raw materials of the modified nano-silica include 22-28 parts of spherical nano-silica, 7-13 parts of toluene diisocyanate, 0.1-0.3 parts of dibutyltin dilaurate and 5-12 parts of dihydroxy polymer in parts by weight; The preparation method of the modified nano silicon dioxide comprises the following steps: The spherical nano-silica was placed in ethanol for ultrasonic dispersion, toluene diisocyanate and dibutyltin dilaurate were added, and the temperature was raised to 60-80° C. and heated in a water bath for 2-3 hours to obtain a blend; Add the dihydroxy polymer to blend A, continue the reaction at a constant temperature for 3-5 hours, then centrifuge, wash, dry and grind to obtain the product.

[0014] By adopting the above technical solution, the surface of nano-silica is modified using a dihydroxy polymer. On the one hand, active hydroxyl groups are introduced on the surface of nano-silica, which can act as an antifreeze agent in the grease. The hydroxyl groups can form stable chemical bonds through the interaction with water molecules or other polar components, thereby lowering the freezing point of the grease and further improving the low-temperature flow properties of the grease.

[0015] On the other hand, silane-terminated polyethers have silane groups, which can react with the active hydroxyl groups on the surface of modified nano-silica to form stable silicon-oxygen bonds. This interfacial bonding can enhance the interaction between polyether and modified nano-silica, further improving the dispersion stability of modified nano-silica in grease.

[0016] Optionally, the dihydroxy compound is a linear or branched dihydroxy structure selected from polypropylene glycol or polyethylene glycol.

[0017] By adopting the above technical solution, the use of a straight-chain or branched dihydroxy structure makes the molecular chain of the product more flexible. This flexibility helps the molecular chain to better adjust its conformation during the reaction, making it easier for the hydroxyl group to approach and react with other functional groups.

[0018] When the silane-terminated polyether reacts with the dihydroxy polymer on the surface of nano-silica, the dihydroxy polymer increases the length of the flexible chain segment of the silane-terminated polyether, giving the grease better flexibility, making the grease less likely to thicken or even solidify at low temperatures, further improving the low-temperature fluidity and pumpability of the grease.

[0019] Optionally, the silane-terminated polyether is selected from any one of GENIOSIL® XT50, GENIOSIL® XT55 and GENIOSIL® STP-E.

[0020] Optionally, the additives include 1.5-5% of an extreme pressure anti-wear agent, 0.5-2% of an antioxidant and 1-3% of a rust inhibitor.

[0021] Optionally, the extreme pressure anti-wear agent is a fluorine-containing phosphate ester extreme pressure anti-wear agent.

[0022] Optionally, the fluorine-containing phosphate ester type extreme pressure antiwear agent is selected from any one or more combinations of bis(2,2,2-trifluoroethyl)phosphite, tris(2,2,2-trifluoroethyl)phosphite, tris(2,2,2-trifluoroethyl)phosphine and tris(fluorine-containing alkyl)phosphate.

[0023] By adopting the above technical solution, the fluorinated phosphate ester type extreme pressure anti-wear agent has a fluorine group, and its unique low surface energy can improve the adhesion of grease at low temperatures, especially its spreading on metal surfaces. This allows the grease to stably adhere to the surface of the electric shovel gear under low temperature conditions, providing continuous and effective lubrication protection for the electric shovel gear.

[0024] Optionally, the antioxidant is an aromatic amine antioxidant.

[0025] Optionally, the aromatic amine antioxidant is selected from any one or more combinations of diphenylamine, diisooctyl diphenylamine, β-naphthylamine, N-phenyl-α-naphthylamine, N-phenyl-β-naphthylamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N,N'-di-β-naphthyl-p-phenylenediamine and N,N'-di-sec-butyl-p-phenylenediamine.

[0026] Optionally, the rust inhibitor is an organic sulfonate type rust inhibitor.

[0027] Optionally, the organic sulfonate type rust inhibitor is selected from any one or more combinations of barium petroleum sulfonate, sodium petroleum sulfonate, barium dinonylnaphthalene sulfonate, zinc dinonylnaphthalene sulfonate, and zinc naphthenate.

[0028] In a second aspect, the present application provides a method for preparing a gear grease composition, using the following technical solution: A method for preparing a gear grease composition comprises the following steps: Add 12-hydroxystearic acid and silane-terminated polyether to 1 / 2 of the base oil, mix and heat to 70-90°C to melt the reactants, add lithium hydroxide, continue to heat to 100-110°C for saponification for 1-1.5 hours, and obtain blend A; The blend A is heated at a constant temperature of 190-200°C for 1-1.5h, the remaining 1 / 2 of the base oil is added, the temperature is continued to be raised to 220-240°C, and the temperature is heated at a constant temperature for 0.5-1h, and then the temperature is naturally lowered to below 120°C to obtain blend B; Add modified nano-silica and additives to blend B, continue to cool to 40-60°C, stir evenly, cool to room temperature, and grind to obtain the mixture.

[0029] By adopting the above technical scheme, the preparation method of the present application allows the various compositions of the grease to fully dissolve in each other, effectively ensuring the dispersion stability between the compositions, so that the product has excellent low-temperature flow properties and extreme pressure and anti-wear properties.

[0030] In summary, this application has the following beneficial effects: 1. Since the present application adopts silane-terminated polyether, a polyether flexible long chain is introduced into the grease, and the polyether flexible long chain is compounded with lithium stearate soap as a thickener. The introduction of the polyether flexible long chain can significantly improve the flexibility of the grease, reduce the low-temperature similar viscosity of the grease, make the grease less likely to crystallize or solidify at low temperatures, reduce the resistance of the grease during transportation, and thus effectively improve the low-temperature pumpability of the grease; 2. The present application introduces solid lubricant nano-silicon dioxide and modifies it, thereby improving the thixotropy of the grease, making the grease easier to flow and be pumped at low temperatures. The spherical nano-silicon dioxide can effectively reduce the friction coefficient of the composite lithium-based grease and improve the low-temperature extreme pressure and anti-wear properties of the grease; 3. In the present application, it is preferred to use a linear or branched dihydroxy compound to modify the surface of nano-silica. On the one hand, the silane-terminated polyether is more likely to wrap the nano-silica particles to form a stable lubricating film, thereby reducing the aggregation of nano-silica. On the other hand, the dihydroxy polymer increases the length of the flexible chain segment of the silane-terminated polyether, giving the grease better flexibility, making it less likely for the grease to thicken or even solidify at low temperatures, further improving the low-temperature fluidity and pumpability of the grease. 4. This application adopts fluorine-containing phosphate ester extreme pressure anti-wear agent to introduce low surface energy fluorine groups into the grease, so that the grease can stably spread and adhere to the surface of the electric shovel gear under extremely cold conditions, providing continuous and effective lubrication protection for the electric shovel gear. DETAILED DESCRIPTION

[0031] The following examples further illustrate the present application in detail.

[0032] Raw materials: Unless otherwise specified, the raw materials used in the examples and comparative examples of this application are all commercially available products, specifically: Ester oil, which is a diester oil, diisopropyl adipate, selected from Zhongyan New Materials, zy-230; Polyalphaolefin synthetic oil, selected from Exxon, PAO2C, JCY11; Nano-silicon dioxide is spherical nano-silicon dioxide, selected from Shanghai Yaotian New Materials, YT-Oy-01-1, with an average particle size of 20nm; 12-Hydroxystearic acid, selected from Guangzhou Wanchen Chemical, B0235461-5; Lithium hydroxide, which is lithium hydroxide monohydrate LiOH·H20, selected from ALT New Energy Materials, ALT-LI-C01; Toluene diisocyanate, selected from Shanghai Yuanye Biotechnology Co., Ltd., W10121; Dibutyltin dilaurate, selected from Shanghai Yuanye Biotechnology Co., Ltd., W10608; Polyethylene glycol 2000, selected from Zhonghe Shengtai, PEG-2000; Polypropylene glycol 2000, selected from Zhonghe Shengtai, PEG-2000; Bis(2,2,2-trifluoroethyl)phosphite selected from VicoQ, WKQ-0040082; Di-n-butyl phosphite, selected from Hubei Kanosi Technology, 8598479; N-phenyl-β-naphthylamine, selected from Shanghai Jieshikai Biotechnology, KA630362; Barium dinonylnaphthalenesulfonate, selected from Hubei Wonder Chemical Industry, WD2956; GENIOSIL® XT50, GENIOSIL® XT55 and GENIOSIL® STP-E are all available from Wacker Chemicals.

[0033] Preparation example of modified nano-silica

[0034] Preparation Example 1: Modified nano-silicon dioxide, the raw materials and amounts are shown in Table 1, wherein the nano-silicon dioxide is spherical nano-silicon dioxide, and the dihydroxy polymer is polyethylene glycol 2000; Table 1

[0035] The preparation method of the modified nano-silicon dioxide comprises the following steps: S1: After vacuum drying at 120° C. for 2 h, spherical nano-silica was placed in anhydrous ethanol at a material-liquid ratio of 1:7, ultrasonically dispersed for 1 h, placed in a three-necked flask, toluene diisocyanate and dibutyltin dilaurate were added, and the temperature was raised to 80° C. and heated in a water bath for 2 h to obtain a blend; S2: Add dihydroxy polymer to blend A, continue the reaction at constant temperature for 3 hours, then centrifuge, wash, vacuum dry at 120°C for 8 hours, and grind to obtain.

[0036] Preparation Example 2: Modified nano-silicon dioxide, the difference from Preparation Example 1 is that the raw materials and amounts are as shown in Table 1, wherein the dihydroxy compound is polypropylene glycol 2000; The preparation method of the modified nano-silicon dioxide comprises the following steps: S1: After vacuum drying at 120° C. for 2 h, spherical nano-silica was placed in anhydrous ethanol at a material-liquid ratio of 1:7, ultrasonically dispersed for 1 h, placed in a three-necked flask, toluene diisocyanate and dibutyltin dilaurate were added, and the temperature was raised to 60° C. and heated in a water bath for 3 h to obtain a blend; S2: Add dihydroxy polymer to blend A, continue the reaction at constant temperature for 5 hours, then centrifuge, wash, vacuum dry at 120°C for 8 hours, and grind to obtain.

[0037] Preparation Example 3: Modified nano-silicon dioxide, which is different from Preparation Example 1 in that the raw materials and amounts are shown in Table 1; The preparation method of the modified nano-silicon dioxide comprises the following steps: S1: After vacuum drying at 120° C. for 2 h, spherical nano-silica was placed in anhydrous ethanol at a material-liquid ratio of 1:7, ultrasonically dispersed for 1 h, placed in a three-necked flask, toluene diisocyanate and dibutyltin dilaurate were added, and the temperature was raised to 70° C. and heated in a water bath for 3 h to obtain a blend; S2: Add dihydroxy polymer to blend A, continue the reaction at constant temperature for 5 hours, then centrifuge, wash, vacuum dry at 120°C for 8 hours, and grind to obtain.

[0038] Preparation Example 4: Modified nano-silica. The difference from Preparation Example 1 is that the dihydroxy compound in the raw material is replaced by an equal mass of ethylene glycol, and the other steps are the same as those in Preparation Example 1.

[0039] Preparation Example 5: Modified nano-silica. The difference from Preparation Example 1 is that the dihydroxy compound in the raw material is replaced by an equal mass of propylene glycol, and the other steps are the same as those in Preparation Example 1.

[0040] Example

[0041] Example 1: A gear grease composition, the raw materials and amounts are shown in Table 2, wherein the base oil is a poly-α-olefin synthetic oil and an ester oil in a mass ratio of 1:0.2; the thickener comprises a silane-terminated polyether, 12-hydroxystearic acid and lithium hydroxide in a mass ratio of 1:12:17; the modified nano-silica is obtained by Preparation Example 1; the silane-terminated polyether is GENIOSIL® XT50; the extreme pressure anti-wear agent is a fluorine-containing phosphate type extreme pressure anti-wear agent, bis(2,2,2-trifluoroethyl)phosphite; the antioxidant is an aromatic amine type antioxidant, N-phenyl-β-naphthylamine; the rust inhibitor is an organic sulfonate type rust inhibitor, barium dinonylnaphthalenesulfonate; Table 2

[0042] The preparation method of the gear grease composition comprises the following steps: S1: Divide the base oil into two parts, add 12-hydroxystearic acid and silane-terminated polyether into 1 / 2 of the base oil, mix and heat to 90°C to completely melt the reactants, add lithium hydroxide, continue to heat to 110°C for saponification for 1h, and obtain blend A; S2: Blend A was heated at a constant temperature of 200° C. for 1 h, the remaining 1 / 2 of the base oil was added, the temperature was further raised to 240° C., and the temperature was heated at a constant temperature for 0.5 h, and then the temperature was naturally lowered to below 120° C. to obtain blend B; S3: Add modified nano-silica and additives to blend B, continue cooling to 60°C and stir evenly, cool to room temperature and grind to obtain the mixture.

[0043] Example 2: A gear grease composition, which is different from Example 1 in that the raw materials and amounts are as shown in Table 2, wherein the base oil is a poly-α-olefin synthetic oil and an ester oil in a mass ratio of 1:0.3; the thickener comprises a silane-terminated polyether, 12-hydroxystearic acid and lithium hydroxide in a mass ratio of 1:10:15; and the modified nano-silicon dioxide is obtained by Preparation Example 2; The preparation method of the gear grease composition comprises the following steps: S1: Divide the base oil into two parts, add 12-hydroxystearic acid and silane-terminated polyether into 1 / 2 of the base oil, mix and heat to 70°C to completely melt the reactants, add lithium hydroxide, continue to heat to 100°C for saponification for 1.5 hours, and obtain blend A; S2: Blend A was heated at a constant temperature of 190° C. for 1.5 h, the remaining 1 / 2 of the base oil was added, the temperature was further raised to 220° C., and the temperature was heated at a constant temperature for 1 h, and then the temperature was naturally lowered to below 120° C. to obtain blend B; S3: Add modified nano-silica and additives to blend B, continue cooling to 40°C and stir evenly, cool to room temperature and grind to obtain.

[0044] Example 3: A gear grease composition, which is different from Example 1 in that the raw materials and amounts are as shown in Table 2, wherein the base oil is a poly-α-olefin synthetic oil and an ester oil in a mass ratio of 1:0.1; the thickener comprises a silane-terminated polyether, 12-hydroxystearic acid and lithium hydroxide in a mass ratio of 1:12:15; the modified nano-silicon dioxide is obtained by Preparation Example 3; The preparation method of the gear grease composition comprises the following steps: S1: Divide the base oil into two parts, add 12-hydroxystearic acid and silane-terminated polyether into 1 / 2 of the base oil, mix and heat to 80°C to completely melt the reactants, add lithium hydroxide, continue to heat to 100°C for saponification for 1.5 hours, and obtain blend A; S2: Blend A is heated at a constant temperature of 200° C. for 1 h, the remaining 1 / 2 of the base oil is added, the temperature is further raised to 230° C., and the temperature is heated at a constant temperature for 1 h, and then the temperature is naturally lowered to below 120° C. to obtain blend B; S3: Add modified nano-silica and additives to blend B, continue cooling to 50°C and stir evenly, cool to room temperature and grind to obtain the mixture.

[0045] Example 4: A gear grease composition, which is different from Example 1 in that the raw materials and amounts are as shown in Table 2, wherein the base oil is a poly-α-olefin synthetic oil and an ester oil in a mass ratio of 1:0.2; the thickener includes a silane-terminated polyether, 12-hydroxystearic acid and lithium hydroxide in a mass ratio of 1:8:21; The preparation method of the gear grease composition comprises the following steps: S1: The base oil is divided into two parts, 12-hydroxystearic acid and silane-terminated polyether are added to 1 / 2 of the base oil, the mixture is heated to 85°C to completely melt the reactants, lithium hydroxide is added, and the temperature is continued to rise to 100°C for saponification for 1.2 hours to obtain blend A; S2: Blend A was heated at a constant temperature of 200° C. for 1.2 h, the remaining 1 / 2 of the base oil was added, the temperature was further raised to 230° C., and the temperature was heated at a constant temperature for 0.8 h, and then the temperature was naturally lowered to below 120° C. to obtain blend B; S3: Add modified nano-silica and additives to blend B, continue cooling to 55° C., stir evenly, cool to room temperature, and grind to obtain the mixture.

[0046] Example 5: A gear grease composition, which is different from Example 1 in that the modified nano-silicon dioxide in the raw material is obtained from Preparation Example 4, and the other steps are the same as Example 1.

[0047] Example 6: A gear grease composition, which is different from Example 1 in that the modified nano-silicon dioxide in the raw material is obtained from Preparation Example 5, and the other steps are the same as Example 1.

[0048] Example 7: A gear grease composition, which is different from Example 1 in that the silane-terminated polyether in the raw material thickener is GENIOSIL® XT55, and the other steps are the same as Example 1.

[0049] Example 8: A gear grease composition, which is different from Example 1 in that the silane-terminated polyether in the raw material thickener is GENIOSIL® STP-E, and the other steps are the same as those in Example 1.

[0050] Example 9: A gear grease composition, which differs from Example 1 in that the extreme pressure anti-wear agent in the raw material additive is an equal mass of di-n-butyl phosphite, and the other steps are the same as Example 1.

[0051] Comparative Example

[0052] Comparative Example 1: A gear grease composition, which differs from Example 1 in that the modified nano-silicon dioxide in the raw material is replaced by nano-silicon dioxide of equal mass, and the other steps are the same as Example 1.

[0053] Comparative Example 2: A gear grease composition, which differs from Example 1 in that the silane-terminated polyether in the raw material thickener is replaced with an equal mass of 12-hydroxystearic acid, and the other steps are the same as Example 1.

[0054] Comparative Example 3: A gear grease composition, which differs from Example 1 in that no ester oil is added, the base oil in the raw material is poly-α-olefin synthetic oil, and the other steps are the same as Example 1.

[0055] Comparative Example 4: A gear grease composition, which differs from Example 1 in that the base oil in the raw materials is a poly-α-olefin synthetic oil and an ester oil in a mass ratio of 1:0.6, and the other steps are the same as Example 1.

[0056] Performance testing The gear grease composition obtained in Examples 1-9 and Comparative Examples 1-4 was subjected to the following relevant performance test.

[0057] 1. Working cone penetration: refer to the method specified in GB / T 269-1991 to test the working cone penetration of the grease composition at -40°C; 2. Corrosion: Refer to the method specified in GB / T 7326 (Method B)-1987; 3. Similar viscosity: refer to the method specified in SH / T 0048-1991, and measure the similar viscosity of the grease composition at -50°C; 4. Extreme pressure performance: refer to the method specified in GB / T 12583; 5. Anti-wear performance: refer to the method specified in SH / T 0204.

[0058] Table 3

[0059] According to the performance test results in Table 3, it can be seen that a gear grease composition of the present application can still maintain good low-temperature fluidity and pumpability at -40°C or even lower temperatures, and the grease can be pumped to the gears to ensure adhesion and extreme pressure wear resistance between the gears at low temperatures, providing continuous and effective lubrication protection for the gears of the electric shovel. It effectively improves the lubrication performance of the gear grease at low temperatures, reduces the occurrence of grease thickening or even solidification caused by low temperatures, slows down the wear of the gears, and thus extends the service life of the equipment.

[0060] It can be seen from the performance test results of Examples 1-8 and Comparative Examples 1-2 that the introduction of silane-terminated polyether flexible long chains into the grease and the combination with lithium stearate soap as a thickener can significantly improve the flexibility of the grease, thereby reducing the low-temperature similar viscosity of the grease, making the grease less likely to crystallize or solidify at low temperatures, reducing the resistance of the grease during transportation, and effectively improving the low-temperature pumpability of the grease.

[0061] After modification, nano-silica is mixed with other raw materials. Active hydroxyl groups are introduced on the surface of nano-silica. Hydroxyl groups can form stable chemical bonds through interactions with water molecules or other polar components, effectively improving the dispersion stability of modified nano-silica in grease and further improving the low-temperature flow properties of grease.

[0062] The surface of nano-silica is modified by using dihydroxy compounds with a straight-chain or branched structure. The silane groups of the silane-terminated polyether react with the active hydroxyl groups on the surface of the modified nano-silica to form silicon-oxygen bonds, which further extend the length of the flexible chain segments of the silane-terminated polyether, give the grease better flexibility, and further improve the low-temperature fluidity and pumpability of the grease.

[0063] It can be seen from the performance test results of Examples 1-4 and Example 9 that by using fluorine-containing phosphate extreme pressure anti-wear agents and introducing low surface energy fluorine groups into the grease, the grease can be stably spread and adhered to the surface of the electric shovel gear under extremely cold conditions, providing continuous and effective lubrication protection for the electric shovel gear, thereby improving its extreme pressure anti-wear performance.

[0064] It can be seen from the performance test results of Examples 1-4 and Comparative Examples 3-4 that, within the formulation range specified in the present application, the addition of a small amount of ester oil can further adjust the viscosity-temperature properties of the base oil, so that the grease can still maintain good viscosity characteristics at lower temperatures, thereby ensuring the low-temperature fluidity of the grease and its adhesion to the equipment.

[0065] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. A gear grease composition, characterized in that: In terms of mass percentage, the components include 70-85% base oil, 8-16% thickener, 3.5-10.7% modified nano-silicon dioxide and 3-10% additives; The base oil is a poly-alpha-olefin synthetic oil and an ester oil in a mass ratio of 1:(0.1-0.3); The thickener comprises silane-terminated polyether, 12-hydroxystearic acid and lithium hydroxide in a mass ratio of 1:(8-12):(15-21).

2. The gear grease composition according to claim 1, characterized in that: In parts by weight, the raw materials of the modified nano-silica include 22-28 parts of spherical nano-silica, 7-13 parts of toluene diisocyanate, 0.1-0.3 parts of dibutyltin dilaurate and 5-12 parts of dihydroxy polymer; The preparation method of the modified nano silicon dioxide comprises the following steps: Spherical nano-silica is placed in ethanol for ultrasonic dispersion, toluene diisocyanate and dibutyltin dilaurate are added, the temperature is raised to 60-80° C. and heated in a water bath for 2-3 hours to obtain a blend; Add the dihydroxy polymer to blend A, continue the constant temperature reaction for 3-5 hours, then centrifuge, wash, dry and grind to obtain the product.

3. The gear grease composition according to claim 2, characterized in that: The dihydroxy compound is a linear or branched dihydroxy structure selected from polypropylene glycol or polyethylene glycol.

4. The gear grease composition according to claim 1, characterized in that: The silane-terminated polyether is selected from any one of GENIOSIL® XT50, GENIOSIL® XT55 and GENIOSIL® STP-E.

5. The gear grease composition according to claim 1, characterized in that: The additives include 1.5-5% of extreme pressure anti-wear agent, 0.5-2% of antioxidant and 1-3% of rust inhibitor.

6. The gear grease composition according to claim 5, characterized in that: The extreme pressure anti-wear agent is a fluorine-containing phosphate ester extreme pressure anti-wear agent.

7. The gear grease composition according to claim 5, characterized in that: The antioxidant is an aromatic amine antioxidant.

8. The gear grease composition according to claim 5, characterized in that: The rust inhibitor is an organic sulfonate type rust inhibitor.

9. The method for preparing a gear grease composition according to any one of claims 1 to 8, characterized in that: The following steps are involved: Add 12-hydroxystearic acid and silane-terminated polyether to 1 / 2 of the base oil, mix and heat to 70-90°C to melt the reactants, add lithium hydroxide, continue to heat to 100-110°C for saponification for 1-1.5 hours, and obtain blend A; The blend A is heated at a constant temperature of 190-200°C for 1-1.5h, the remaining 1 / 2 of the base oil is added, the temperature is continued to be raised to 220-240°C, and the temperature is heated at a constant temperature for 0.5-1h, and then the temperature is naturally lowered to below 120°C to obtain blend B; Add modified nano-silica and additives to blend B, continue to cool to 40-60°C, stir evenly, cool to room temperature, and grind to obtain the mixture.

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