A gear grease composition and a preparation method thereof

Abstract

This application relates to the technical field of greases, and specifically discloses a gear grease composition and a preparation method thereof. A gear grease composition, by mass percentage, each component includes 70 - 85% of base oil, 8 - 16% of thickener, 3.5 - 10.7% of modified nano-silica, and 3 - 10% of additive; the base oil is a synthetic polyalphaolefin oil and an ester oil with a mass ratio of 1:(0.1 - 0.3); the thickener includes a silane-capped polyether, 12-hydroxystearic acid, and lithium hydroxide with a mass ratio of 1:(8 - 12):(15 - 21). A gear grease composition of this application can be used for lubricating the gears of an electric shovel in an extremely cold low-temperature environment, and it has excellent low-temperature fluidity and pumpability, and can provide continuous and stable lubrication for the low-temperature operation of the electric shovel.

Description

Technical Field

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

[0002] An electric shovel, also known as a mechanical single-bucket excavator, is mainly used for the stripping of surface materials in mines and the loading and unloading of ores. The electric shovel has a high operation rate and low operation cost, and is one of the main large-scale equipment for open-pit mining. An electric shovel is composed of four major mechanical systems, namely a push system, a hoist system, a slewing system, and a traveling system, as well as two auxiliary systems, namely an air system and an automatic lubrication system. In the automatic lubrication system of an electric shovel, the most critical is the lubrication problem of the open gears.

[0003] The power of the open gears of an electric shovel comes from the interaction and relative movement of each pair of meshing tooth surfaces in the gear mechanism, which can transmit a very high torque. The tooth surface has a relatively high roughness and harsh working conditions. During startup, normal operation, and shutdown, the open gears are usually in the boundary friction or mixed friction state, so the tooth surface will bear extremely high stresses. If effective lubrication cannot be obtained, the frictional force and contact stress between the meshing gear teeth will cause the temperature of the micro-protrusions on the mutually contacting tooth surfaces to rise sharply, resulting in adhesion or even welding of the two tooth surfaces, causing fatigue wear of the gears, and ultimately leading to tooth breakage.

[0004] Therefore, preparing an open gear grease with excellent performance and meeting the lubrication working conditions requirements of the open gears of an electric shovel can effectively extend the service life of the open gears of an electric shovel, reduce spare part losses and shutdown losses, and improve the long-term operation stability of the overall equipment. This is crucial for large open gear transmission devices with low speed, heavy load, and huge transmitted torque.

[0005] In view of the above related technologies, the inventor found that the existing electric shovel gear grease can provide good lubrication protection at room temperature. However, under low-temperature conditions, especially in cold regions where the winter temperature can be as low as -40°C, the fluidity of the gear grease will drop sharply, and it is easy to become thick or even solidify. This directly leads to a sharp drop in the pumpability of the grease, causing blockage of the lubrication system, and it is difficult for the lubrication system to effectively transport the grease to the gear part. On the one hand, the gears cannot be fully lubricated, which exacerbates gear wear and shortens the service life of the equipment; on the other hand, the lubrication pump often emits fault signals during operation, seriously affecting the operation efficiency. In addition, the extreme pressure and adhesion of the grease will also decrease under low-temperature conditions, and it cannot 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 the gear grease and enhance the lubrication performance of the 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, adopting the following technical solution:

[0008] A gear grease composition, by mass percentage, each component includes 70 - 85% of base oil, 8 - 16% of thickener, 3.5 - 10.7% of modified nano-silica, and 3 - 10% of additive;

[0009] The base oil is a synthetic oil of polyalphaolefin and ester oil with a mass ratio of 1:(0.1 - 0.3);

[0010] The thickener includes silane-capped polyether, 12-hydroxystearic acid, and lithium hydroxide with a mass ratio of 1:(8 - 12):(15 - 21).

[0011] By adopting the above technical solution, polyalphaolefin synthetic oil, as a synthetic hydrocarbon base oil, has good high and low temperature performance, can maintain good low temperature fluidity and viscosity at low temperature, and the addition of a small amount of ester oil can further adjust the viscosity-temperature performance of the base oil, enabling the grease to still maintain good viscosity characteristics at lower temperatures.

[0012] The silane-capped polyether structure retains the flexible polyether long chain, which is compounded with lithium stearate soap as a thickener, significantly improving the low temperature resistance of the thickener. The flexible polyether long chain can significantly enhance the flexibility of the grease, making the grease not easy to crystallize or solidify at low temperature, reducing the resistance during the transportation of the grease, and thus effectively improving the low temperature pumpability of the grease. The flexible polyether long chain can maintain good fluidity in a low temperature environment, reducing the low temperature apparent viscosity of the grease, and helping the grease to better distribute and penetrate under extremely cold low temperature conditions.

[0013] The silane-capped polyether also has excellent weather resistance and water resistance, has good wetting ability for the metal substrate of the gear, and can generate good adhesion to the substrate, which enables the grease to maintain good adhesion at low temperature, form a uniform lubricating film on the gear surface, and provide continuous and effective lubrication protection for the electric shovel gear.

[0014] Nano-silica is introduced as a nano-solid lubricant, improving the thixotropy of the grease, making the grease easier to flow and be pumped at low temperature, and being able to quickly restore the original structure after the shear force is removed. Spherical nano-silica can effectively reduce the friction coefficient of the complex lithium base grease, improve the colloidal stability and the stability of the framework structure of the system, enhance the boundary lubrication effect, and provide additional protection even when the oil film is damaged at low temperature, improving the low temperature extreme pressure anti-wear performance of the grease.

[0015] After modifying nano-silica and mixing it with a thickening agent, a chemical interaction can form between the silane-capped polyether and the modified nano-silica. The tiny particles of nano-silica can serve as "anchor points" for the silane-capped polyether chains, enhancing the dispersion stability and uniformity of the raw materials in the grease. At the same time, the flexible segments of the silane-capped polyether chains can also better wrap the nano-silica particles, forming a stable lubricating film and significantly reducing the agglomeration between nano-silica particles.

[0016] Optionally, 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.

[0017] The preparation method of the modified nano-silica includes the following steps:

[0018] Place the spherical nano-silica in ethanol for ultrasonic dispersion, add toluene diisocyanate and dibutyltin dilaurate, and heat in a water bath at 60-80°C for 2-3h to obtain a blend.

[0019] Add the dihydroxy polymer to the blend A, continue the constant-temperature reaction for 3-5h, then centrifuge, wash, dry, and grind to obtain the product.

[0020] By adopting the above technical solution, using a dihydroxy polymer to modify the surface of nano-silica, on the one hand, active hydroxyl groups are introduced on the surface of nano-silica, which can act as an antifreeze in the grease. The hydroxyl groups can form stable chemical bonds through interactions with water molecules or other polar components, reducing the freezing point of the grease and further improving the low-temperature flow performance of the grease.

[0021] On the other hand, the silane-capped polyether has silane groups, and these groups can react with the active hydroxyl groups on the surface of the modified nano-silica to form stable silicon-oxygen bonds. This interfacial bonding can enhance the interaction between the polyether and the modified nano-silica, further improving the dispersion stability of the modified nano-silica in the grease.

[0022] Optionally, the dihydroxy compound has a linear or branched dihydroxy structure and is selected from polypropylene glycol or polyethylene glycol.

[0023] By adopting the above technical solution, using a linear or branched dihydroxy structure makes the molecular chain of the product have higher flexibility. This flexibility helps the molecular chain better adjust its conformation during the reaction, making it easier for the hydroxyl groups to approach and react with other functional groups.

[0024] When the silane - terminated polyether reacts with the di - hydroxyl polymer on the surface of nano - silica, the di - hydroxyl polymer increases the length of the flexible chain segment of the silane - terminated polyether, endowing the grease with better flexibility and elasticity. This makes the grease not easy to thicken or even solidify at low temperatures, further improving the low - temperature fluidity and pumpability of the grease.

[0025] Optionally, the silane - terminated polyether is selected from any one of GENIOSIL® XT50, GENIOSIL® XT55, and GENIOSIL® STP - E.

[0026] Optionally, the additive includes 1.5 - 5% extreme - pressure and anti - wear agent, 0.5 - 2% antioxidant, and 1 - 3% rust inhibitor.

[0027] Optionally, the extreme - pressure and anti - wear agent is a fluorinated phosphate - type extreme - pressure and anti - wear agent.

[0028] Optionally, the fluorinated phosphate - type extreme - pressure and anti - wear agent is selected from any one or a combination of bis(2,2,2 - trifluoroethyl) phosphite, tris(2,2,2 - trifluoroethyl) phosphite, tris(2,2,2 - trifluoroethyl) phosphine, and tris(fluoroalkyl) phosphate.

[0029] By adopting the above - mentioned technical solution, the fluorinated phosphate - type extreme - pressure and anti - wear agent has a fluorine group with a unique low surface energy, which can improve the adhesion of the grease at low temperatures, especially the spreading property on the metal surface. This enables 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.

[0030] Optionally, the antioxidant is an aromatic amine - type antioxidant.

[0031] Optionally, the aromatic amine - type antioxidant is selected from any one or a combination 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.

[0032] Optionally, the rust inhibitor is an organic sulfonate - type rust inhibitor.

[0033] Optionally, the organic sulfonate - type rust inhibitor is selected from any one or a combination of barium petroleum sulfonate, sodium petroleum sulfonate, barium dinonylnaphthalene sulfonate, zinc dinonylnaphthalene sulfonate, and zinc naphthenate.

[0034] In the second aspect, the present application provides a preparation method of a gear grease composition, adopting the following technical solution:

[0035] A preparation method of a gear grease composition includes the following steps:

[0036] Add 12 - hydroxy stearic 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, and continue to heat up to 100 - 110 °C for saponification for 1 - 1.5 h to obtain blend A;

[0037] Keep blend A at a constant temperature of 190 - 200 °C and heat for 1 - 1.5 h, add the remaining 1 / 2 of the base oil, continue to heat up to 220 - 240 °C, keep at a constant temperature and heat for 0.5 - 1 h, and then naturally cool to below 120 °C to obtain blend B;

[0038] Add modified nano - silica and additives to blend B, continue to cool to 40 - 60 °C and stir evenly, and then grind after cooling to room temperature to obtain the product.

[0039] By adopting the above - mentioned technical solution, the preparation method of this application enables the various compositions of the grease to fully dissolve and react with each other, effectively ensuring the dispersion stability between the compositions, and making the product have excellent low - temperature flow performance and extreme - pressure anti - wear performance.

[0040] To sum up, this application has the following beneficial effects:

[0041] 1. Since this application uses silane - terminated polyether, a polyether flexible long chain is introduced into the grease. As a thickener in combination with lithium stearate soap, the introduction of the polyether flexible long chain can significantly improve the flexibility of the grease, reduce the low - temperature apparent viscosity of the grease, making the grease not easy to crystallize or solidify at low temperatures, reducing the resistance during the transportation of the grease, and thus effectively improving the low - temperature pumpability of the grease;

[0042] 2. This application introduces solid lubricant nano - silica and modifies it, improving the thixotropy of the grease, making the grease easier to flow and be pumped at low temperatures. Spherical nano - silica can effectively reduce the friction coefficient of the complex lithium - based grease and improve the low - temperature extreme - pressure anti - wear performance of the grease;

[0043] 3. In this application, a straight - chain or branched - chain dihydroxy compound is preferably used to modify the surface of nano - silica. On the one hand, it makes it easier for silane - terminated polyether to wrap nano - silica particles, forming a stable lubricating film and reducing the agglomeration of nano - silica; on the other hand, the dihydroxy polymer increases the length of the flexible chain segment of silane - terminated polyether, endowing the grease with better flexibility and elasticity, making the grease not easy to thicken or even solidify at low temperatures, and further improving the low - temperature fluidity and pumpability of the grease;

[0044] 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

[0045] The following examples further illustrate the present application in detail.

[0046] Raw materials: Unless otherwise specified, the raw materials used in the examples and comparative examples of this application are all commercially available products, specifically:

[0047] Ester oil, which is a diester oil, diisopropyl adipate, selected from Zhongyan New Materials, zy-230;

[0048] Polyalphaolefin synthetic oil, selected from Exxon, PAO2C, JCY11;

[0049] 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;

[0050] 12-Hydroxystearic acid, selected from Guangzhou Wanchen Chemical, B0235461-5;

[0051] Lithium hydroxide, LiOH·H 2 0, selected from ALT New Energy Materials, ALT-LI-C01;

[0052] Toluene diisocyanate, selected from Shanghai Yuanye Biotechnology Co., Ltd., W10121;

[0053] Dibutyltin dilaurate, selected from Shanghai Yuanye Biotechnology Co., Ltd., W10608;

[0054] Polyethylene glycol 2000, selected from Zhonghe Shengtai, PEG-2000;

[0055] Polypropylene glycol 2000, selected from Zhonghe Shengtai, PEG-2000;

[0056] Bis(2,2,2-trifluoroethyl)phosphite selected from VicoQ, WKQ-0040082;

[0057] Di-n-butyl phosphite, selected from Hubei Kanosi Technology, 8598479;

[0058] N-phenyl-β-naphthylamine, selected from Shanghai Jieshikai Biotechnology, KA630362;

[0059] Barium dinonylnaphthalenesulfonate, selected from Hubei Wonder Chemical Industry, WD2956;

[0060] GENIOSIL® XT50, GENIOSIL® XT55, and GENIOSIL® STP-E were all purchased from Wacker Chemie.

[0061] Preparation Examples of Modified Nano-Silica

[0062] Preparation Example 1: Modified nano-silica, with the raw materials and their dosages shown in Table 1. Among them, the nano-silica is spherical nano-silica, and the dihydroxy polymer is polyethylene glycol 2000;

[0063] Table 1

[0064]

[0065] The preparation method of the above-mentioned modified nano-silica includes the following steps:

[0066] S1: The spherical nano-silica was vacuum-dried at 120°C for 2 h, then placed in absolute ethanol according to a solid-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 for water bath heating for 2 h to obtain a blend;

[0067] S2: The dihydroxy polymer was added to the blend A, and the reaction was continued at a constant temperature for 3 h, then centrifuged, washed, and vacuum-dried at 120°C for 8 h, and then ground to obtain the product.

[0068] Preparation Example 2: Modified nano-silica, different from Preparation Example 1 in that the raw materials and their dosages are shown in Table 1. Among them, the dihydroxy compound is polypropylene glycol 2000;

[0069] The preparation method of the above-mentioned modified nano-silica includes the following steps:

[0070] S1: The spherical nano-silica was vacuum-dried at 120°C for 2 h, then placed in absolute ethanol according to a solid-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 for water bath heating for 3 h to obtain a blend;

[0071] S2: The dihydroxy polymer was added to the blend A, and the reaction was continued at a constant temperature for 5 h, then centrifuged, washed, and vacuum-dried at 120°C for 8 h, and then ground to obtain the product.

[0072] Preparation Example 3: Modified nano-silica, different from Preparation Example 1 in that the raw materials and their dosages are shown in Table 1;

[0073] The preparation method of the above-mentioned modified nano-silica includes the following steps:

[0074] S1: Vacuum-dry spherical nano-silica at 120 °C for 2 h, then place it in absolute ethanol according to a solid-liquid ratio of 1:7. After ultrasonic dispersion for 1 h, transfer it to a three-necked flask, add toluene diisocyanate and dibutyltin dilaurate, and raise the temperature to 70 °C for water bath heating for 3 h to obtain a blend.

[0075] S2: Add a dihydroxy polymer to the blend A, continue the constant-temperature reaction for 5 h, then centrifuge, wash, and vacuum-dry at 120 °C for 8 h. After grinding, it is obtained.

[0076] Preparation Example 4: Modified nano-silica, different from Preparation Example 1 in that the dihydroxy compound in the raw materials is replaced with an equal mass of ethylene glycol, and other steps are the same as those in Preparation Example 1.

[0077] Preparation Example 5: Modified nano-silica, different from Preparation Example 1 in that the dihydroxy compound in the raw materials is replaced with an equal mass of propylene glycol, and other steps are the same as those in Preparation Example 1.

[0078] Examples

[0079] Example 1: A gear grease composition, the raw materials and their dosages are shown in Table 2. Among them, the base oil is a synthetic polyalphaolefin oil and an ester oil with a mass ratio of 1:0.2; the thickener includes a silane-capped polyether, 12-hydroxystearic acid, and lithium hydroxide with a mass ratio of 1:12:17; the modified nano-silica is obtained from Preparation Example 1; the silane-capped polyether is GENIOSIL® XT50; the extreme pressure and anti-wear agent is a fluorinated phosphate ester type extreme pressure and 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 dinonylnaphthalene sulfonate;

[0080] Table 2

[0081]

[0082] The preparation method of the above gear grease composition includes the following steps:

[0083] S1: Divide the base oil into two equal parts. Add 12-hydroxystearic acid and the silane-capped polyether to 1 / 2 of the base oil, mix and heat to 90 °C to completely melt the reactants, add lithium hydroxide, and continue to raise the temperature to 110 °C for saponification for 1 h to obtain a blend A;

[0084] S2: Keep the blend A at a constant temperature of 200 °C for 1 h, add the remaining 1 / 2 of the base oil, continue to raise the temperature to 240 °C, keep it at a constant temperature for 0.5 h, and then naturally cool to below 120 °C to obtain a blend B;

[0085] S3: Add the modified nano-silica and additives to Blend B, continue to cool down to 60 °C, stir evenly, and then grind after cooling to room temperature to obtain the product.

[0086] Example 2: A gear grease composition, which is different from Example 1 in that the raw materials and their dosages are shown in Table 2, where the base oil is a synthetic poly-α-olefin oil and an ester oil with a mass ratio of 1:0.3; the thickener includes a polyether end-capped with silane, 12-hydroxystearic acid, and lithium hydroxide with a mass ratio of 1:10:15; the modified nano-silica is obtained from Preparation Example 2;

[0087] The preparation method of the above gear grease composition includes the following steps:

[0088] S1: Divide the base oil into two equal parts, add 12-hydroxystearic acid and the polyether end-capped with silane to 1 / 2 of the base oil, mix and heat to 70 °C to completely melt the reactants, add lithium hydroxide, and continue to heat up to 100 °C for saponification for 1.5 h to obtain Blend A;

[0089] S2: Keep Blend A heated at a constant temperature of 190 °C for 1.5 h, add the remaining 1 / 2 of the base oil, continue to heat up to 220 °C, keep heated at a constant temperature for 1 h, and then naturally cool down to below 120 °C to obtain Blend B;

[0090] S3: Add the modified nano-silica and additives to Blend B, continue to cool down to 40 °C, stir evenly, and then grind after cooling to room temperature to obtain the product.

[0091] Example 3: A gear grease composition, which is different from Example 1 in that the raw materials and their dosages are shown in Table 2, where the base oil is a synthetic poly-α-olefin oil and an ester oil with a mass ratio of 1:0.1; the thickener includes a polyether end-capped with silane, 12-hydroxystearic acid, and lithium hydroxide with a mass ratio of 1:12:15; the modified nano-silica is obtained from Preparation Example 3;

[0092] The preparation method of the above gear grease composition includes the following steps:

[0093] S1: Divide the base oil into two equal parts, add 12-hydroxystearic acid and the polyether end-capped with silane to 1 / 2 of the base oil, mix and heat to 80 °C to completely melt the reactants, add lithium hydroxide, and continue to heat up to 100 °C for saponification for 1.5 h to obtain Blend A;

[0094] S2: Keep Blend A heated at a constant temperature of 200 °C for 1 h, add the remaining 1 / 2 of the base oil, continue to heat up to 230 °C, keep heated at a constant temperature for 1 h, and then naturally cool down to below 120 °C to obtain Blend B;

[0095] S3: Add modified nano-silica and additives to Blend B, continue to cool down to 50 °C, stir evenly, and then grind after cooling to room temperature to obtain the product.

[0096] Example 4: A gear grease composition, which is different from Example 1 in that the raw materials and their dosages are shown in Table 2, wherein the base oil is a synthetic polyalphaolefin oil and an ester oil with a mass ratio of 1:0.2; the thickener includes a silane-capped polyether, 12-hydroxy stearic acid, and lithium hydroxide with a mass ratio of 1:8:21;

[0097] The preparation method of the above gear grease composition includes the following steps:

[0098] S1: Divide the base oil into two equal parts, add 12-hydroxy stearic acid and silane-capped polyether to 1 / 2 of the base oil, mix and heat to 85 °C to completely melt the reactants, add lithium hydroxide, and continue to heat up to 100 °C for saponification for 1.2 h to obtain Blend A;

[0099] S2: Keep Blend A heated at a constant temperature of 200 °C for 1.2 h, add the remaining 1 / 2 of the base oil, continue to heat up to 230 °C, keep heated at a constant temperature for 0.8 h, and then naturally cool down to below 120 °C to obtain Blend B;

[0100] S3: Add modified nano-silica and additives to Blend B, continue to cool down to 55 °C, stir evenly, and then grind after cooling to room temperature to obtain the product.

[0101] Example 5: A gear grease composition, which is different from Example 1 in that the modified nano-silica in the raw materials is obtained from Preparation Example 4, and other steps are the same as those in Example 1.

[0102] Example 6: A gear grease composition, which is different from Example 1 in that the modified nano-silica in the raw materials is obtained from Preparation Example 5, and other steps are the same as those in Example 1.

[0103] Example 7: A gear grease composition, which is different from Example 1 in that the silane-capped polyether in the raw material thickener is GENIOSIL® XT55, and other steps are the same as those in Example 1.

[0104] Example 8: A gear grease composition, which is different from Example 1 in that the silane-capped polyether in the raw material thickener is GENIOSIL® STP-E, and other steps are the same as those in Example 1.

[0105] Example 9: A gear grease composition, which is different from Example 1 in that the extreme pressure and anti-wear agent in the raw material additives is di-n-butyl phosphite with equal mass, and other steps are the same as those in Example 1.

[0106] Comparative Example

[0107] Comparative Example 1: A gear grease composition, which is different from Example 1 in that the modified nano-silica in the raw materials is replaced with nano-silica of the same mass, and the other steps are the same as those in Example 1.

[0108] Comparative Example 2: A gear grease composition, which is different from Example 1 in that the silane-capped polyether in the raw material thickener is replaced with 12-hydroxy stearic acid of the same mass, and the other steps are the same as those in Example 1.

[0109] Comparative Example 3: A gear grease composition, which is different from Example 1 in that no ester oil is added, and the base oil in the raw materials is polyalphaolefin synthetic oil, and the other steps are the same as those in Example 1.

[0110] Comparative Example 4: A gear grease composition, which is different from Example 1 in that the base oil in the raw materials is polyalphaolefin synthetic oil and ester oil with a mass ratio of 1:0.6, and the other steps are the same as those in Example 1.

[0111] Performance Detection Test

[0112] The following relevant performance detection tests are carried out on a gear grease composition obtained from Examples 1-9 and Comparative Examples 1-4.

[0113] 1. Work penetration: Refer to the method specified in GB / T 269-1991 to test the work penetration of the grease composition at -40°C;

[0114] 2. Corrosion: Refer to the method specified in GB / T 7326 (Method B)-1987;

[0115] 3. Apparent viscosity: Refer to the method specified in SH / T 0048-1991 to measure the apparent viscosity of the grease composition at -50°C;

[0116] 4. Extreme pressure performance: Refer to the method specified in GB / T 12583;

[0117] 5. Anti-wear performance: Refer to the method specified in SH / T 0204.

[0118] Table 3

[0119]

[0120] 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. The grease can be pumped to the gears, ensuring adhesion and extreme pressure anti-wear properties between the grease and the gears at low temperatures, providing continuous and effective lubrication protection for the electric shovel gears. It effectively improves the lubrication performance of the gear grease at low temperatures, reduces the occurrence of thickening or even solidification of the grease caused by low temperatures, slows down the wear of the gears, and thus extends the service life of the equipment.

[0121] According to the performance test results of Examples 1-8 and Comparative Examples 1-2, it can be seen that introducing a silane-capped polyether flexible long chain into the grease and compounding it with lithium stearate soap as a thickener can significantly improve the flexibility of the grease, thereby reducing the low-temperature apparent viscosity of the grease, making the grease less likely to crystallize or solidify at low temperatures, reducing the resistance during the transportation of the grease, and effectively improving the low-temperature pumpability of the grease.

[0122] After modifying nano-silica and mixing it with other raw materials, reactive hydroxyl groups are introduced onto the surface of the nano-silica. The hydroxyl groups can form stable chemical bonds through interactions with water molecules or other polar components, effectively improving the dispersion stability of the modified nano-silica in the grease and further enhancing the low-temperature flow performance of the grease.

[0123] Surface modification of nano-silica is carried out using a straight-chain or branched-chain dihydroxy compound. The silane group of the silane-capped polyether reacts with the reactive hydroxyl groups on the surface of the modified nano-silica to form siloxane bonds, further extending the length of the flexible chain segment of the silane-capped polyether, endowing the grease with better flexibility and elasticity, and further enhancing the low-temperature fluidity and pumpability of the grease.

[0124] According to the performance test results of Examples 1-4 and Example 9, it can be seen that by using a fluorinated phosphate ester type extreme pressure anti-wear agent and introducing low-surface-energy fluorine groups into the grease, the grease can stably spread and adhere to the surface of the electric shovel gears under extremely cold and low-temperature conditions, providing continuous and effective lubrication protection for the electric shovel gears, thereby enhancing its extreme pressure anti-wear performance.

[0125] According to the performance test results of Examples 1-4 and Comparative Examples 3-4, it can be seen that within the formula range specified in the present application, the addition of a small amount of ester oil can further adjust the viscosity-temperature performance of the base oil, enabling the grease to still maintain good viscosity characteristics at lower temperatures, ensuring the low-temperature fluidity of the grease and the adhesion between the grease and the equipment.

[0126] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively as needed, but as long as they are within the scope of the claims of the present application, they are 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-silica 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); 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: 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 dihydroxy polymer to the blend, continue the reaction at constant temperature for 3-5 hours, then centrifuge, wash, dry and grind to obtain; The dihydroxy polymer is a linear or branched dihydroxy structure selected from polypropylene glycol or polyethylene glycol.

2. 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.

3. 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.

4. The gear grease composition according to claim 3, characterized in that: The extreme pressure anti-wear agent is a fluorine-containing phosphate ester extreme pressure anti-wear agent.

5. The gear grease composition according to claim 3, characterized in that: The antioxidant is an aromatic amine antioxidant.

6. The gear grease composition according to claim 3, characterized in that: The rust inhibitor is an organic sulfonate type rust inhibitor.

7. A method for preparing a gear grease composition according to any one of claims 1 to 6, 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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