Lithium-based lubricating grease as well as preparation method and application thereof

Abstract

The invention relates to the field of lithium-based lubricating grease, and discloses lithium-based lubricating grease as well as a preparation method and application thereof. The method comprises the following steps: mixing a lithium-based thickening agent, a zirconium-based additive and base oil, and heating and refining; wherein the zirconium-based additive has a structure as shown in a formula (I), the lithium-based lubricating grease is excellent in comprehensive performance and particularly has excellent extreme pressure wear resistance and oxidation stability, and the application performance of the lithium-based lubricating grease is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-based greases, and more specifically to a lithium-based grease, its preparation method, and its application. Background Technology

[0002] Lithium-based grease is the fastest-growing, most widely produced, and most widely used type of grease to date, and it is one of the most promising grease varieties of the 21st century. General-purpose lithium-based greases possess excellent water resistance, rust prevention, mechanical stability, and colloidal stability, and have a high dropping point. They can be used on wet or water-contact mechanical parts, and will not thin or run off under high-speed mechanical shearing. They can also be used at high temperatures. According to literature, lithium-based grease accounts for 60-80% of global grease production, making it the largest grease variety currently available, and it is widely used in industries such as metallurgy, automotive, bearings, and construction machinery.

[0003] With the advancement of science and technology, the requirements for lubrication in various industries in my country are constantly increasing, mainly in terms of the demand for extreme pressure anti-wear performance and long service life. These two indicators determine the limits of workload and oxidation resistance. Traditional lithium-based greases can no longer meet the lubrication requirements of mechanical equipment. Summary of the Invention

[0004] The purpose of this invention is to overcome the aforementioned problems in the prior art and provide a lithium-based grease, its preparation method, and its application. This lithium-based grease exhibits excellent overall performance, particularly superior extreme pressure anti-wear properties and oxidation stability, significantly improving its application performance.

[0005] To achieve the above objectives, the present invention provides a method for preparing lithium-based grease, the method comprising: mixing a lithium-based thickener, a zirconium-based additive and a base oil, and then heating and refining the mixture;

[0006] The zirconium-based additive has a structure as shown in formula (I).

[0007]

[0008] Wherein, R1 is selected from hydrogen, substituted or unsubstituted C2-C10 alkyl, substituted or unsubstituted C6-C18 aryl, R2 is selected from substituted or unsubstituted C2-C20 alkylene, and R3 is selected from substituted or unsubstituted C1-C8 alkylene.

[0009] Of these, the amount of zirconium-based additives used is 0.1-10 wt% relative to the total mass of lithium-based thickeners, zirconium-based additives, and base oils.

[0010] A second aspect of the present invention provides a lithium-based grease prepared by the method described above.

[0011] A third aspect of the present invention provides a lubricating grease comprising a lithium-based thickener, a zirconium-based additive, and a base oil;

[0012] The zirconium-based additive has a structure as shown in formula (I).

[0013]

[0014] Wherein, R1 is selected from hydrogen, substituted or unsubstituted C2-C10 alkyl, substituted or unsubstituted C6-C18 aryl, R2 is selected from substituted or unsubstituted C2-C20 alkylene, and R3 is selected from substituted or unsubstituted C1-C8 alkylene.

[0015] The zirconium-based additive contains 0.1-10 wt% of the total mass of the grease.

[0016] The fourth aspect of the present invention provides the use of zirconium-based additives as defined in the first aspect in improving the extreme pressure anti-wear properties and / or oxidation stability of lithium-based thickeners.

[0017] The lithium-based grease provided by this invention exhibits excellent overall performance, particularly superior extreme pressure anti-wear properties and oxidation stability, significantly enhancing its application performance. It also possesses excellent adhesion, colloidal stability, mechanical stability, and a high dropping point. Furthermore, the preparation method provided by this invention is controllable, resulting in stable product quality. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] In a first aspect, the present invention provides a method for preparing lithium-based grease, the method comprising: mixing a lithium-based thickener, a zirconium-based additive and a base oil, and heating and refining the mixture;

[0020] The zirconium-based additive has a structure as shown in formula (I).

[0021]

[0022] Wherein, R1 is selected from hydrogen, substituted or unsubstituted C2-C10 alkyl, substituted or unsubstituted C6-C18 aryl, R2 is selected from substituted or unsubstituted C2-C20 alkylene, and R3 is selected from substituted or unsubstituted C1-C8 alkylene.

[0023] Of these, the amount of zirconium-based additives used is 0.1-10 wt% relative to the total mass of lithium-based thickeners, zirconium-based additives, and base oils.

[0024] It is understandable that lithium-based grease refers to grease obtained by thickening base oil with lithium-containing compounds.

[0025] The inventors of this invention discovered in their research that the grease prepared according to the method described above has excellent overall performance, especially excellent extreme pressure anti-wear properties and oxidation stability.

[0026] According to the present invention, preferably, the heating and refining temperature is 190-230°C and the time is 8-20 min.

[0027] In this process, lithium-based thickeners and base oils can be mixed first (e.g., mixed and stirred for 20-40 minutes), and then mixed with zirconium-based additives and heated for refining.

[0028] After the heating and refining process is completed, the temperature can be lowered by stirring (to room temperature 23-28℃), and then homogenized (e.g., homogenized 1-3 times using a three-roll mill, e.g., 2 times) and degassed to obtain the finished product.

[0029] According to the present invention, preferably, the lithium-based thickener is a fatty acid lithium thickener, preferably lithium stearate and / or lithium 12-hydroxystearate.

[0030] According to the present invention, preferably, the base oil is at least one selected from mineral oil, synthetic oil, and vegetable oil. The synthetic oil may be polyalphaolefin oil (PAO), ester oil, alkyl silicone oil, Fischer-Tropsch synthetic oil, etc. For example, the base oil may be 500SN, DOS oil, etc.

[0031] According to the present invention, preferably, the kinematic viscosity of the base oil at 100°C is 3-180 mmHg. 2 / s, preferably 4-60mm 2 / s. The method for determining the above kinematic viscosity is GB / T 265.

[0032] Under the above conditions, the overall performance of the lubricating grease can be further guaranteed.

[0033] According to the present invention, preferably, R1 is selected from substituted or unsubstituted C3-C9 alkyl groups, and more preferably (substituted or unsubstituted) C5-C8 straight-chain alkyl groups.

[0034] Preferably, R2 is a substituted or unsubstituted C5-C15 alkylene group, and more preferably a (substituted or unsubstituted) C9-C12 straight-chain alkylene group.

[0035] Preferably, R3 is a substituted or unsubstituted C2-C5 alkylene group, preferably -CH(CH3)- or -C4H8-CH(NH2)-.

[0036] The substituted group is selected from at least one of amino, aryl, hydroxyl, carboxyl, aldehyde and ester groups.

[0037] According to a particularly preferred embodiment of the present invention, the zirconium-based additive is selected from:

[0038]

[0039] More preferably, R1 and R2 in the above structural formula are linear structures.

[0040] The preparation method of zirconium-based additives can be as follows: contacting and reacting a compound having the structure shown in formula (II) with zirconium hydroxide.

[0041]

[0042] According to the present invention, preferably, the mass ratio of the compound having the structure shown in formula (II) to the zirconium hydroxide is 100:(10-50). The zirconium hydroxide can be ZrO(OH)2, or ZrO(OH)2·nH2O, or Zr(OH)4, or Zr(OH)4·nH2O, etc., or it can be freshly prepared zirconium hydroxide such as ZrO(OH)2·xH2O, especially ZrO(OH)2·8H2O.

[0043] It is understood that compounds with the structure shown in formula (II) are carboxylic acids. When in contact with the above-mentioned hydroxide, an acid-base neutralization reaction occurs, yielding the corresponding carboxylate salt.

[0044] ZrO(OH)₂·8H₂O can be obtained by mixing an alkali solution (such as NaOH or KOH) with an aqueous solution of ZrOCl₂·8H₂O. The mass ratio of alkali to ZrOCl₂·8H₂O can be 1:(2.5-5). After mixing, the mixture is stirred rapidly, and a large amount of white precipitate will appear in the system. After solid-liquid separation, the precipitate is obtained. After washing the precipitate, ZrO(OH)₂·8H₂O can be obtained.

[0045] According to the present invention, preferably, the reaction conditions include: a temperature of 70-100°C and a time of 0.5-3.5 h, preferably 1-2 h. The above reaction is a saponification reaction, which can be carried out in water, for example, by mixing zirconium hydroxide with water and then contacting and reacting it with a compound of the structure shown in formula (II). The mass content of zirconium hydroxide in the mixture of zirconium hydroxide and water is not particularly limited, for example, it can be 0.1-0.3 g / g of the mixture.

[0046] The present invention does not impose any particular limitation on the method of obtaining compounds having the structure shown in formula (II). These compounds can be commercially available or synthesized in-house. Those skilled in the art can determine the synthetic method using conventional organic synthesis knowledge. According to one synthetic method provided by the present invention, the preparation method of compounds having the structure shown in formula (II) may include:

[0047] (1) A compound having the structure shown in formula (III), an N-hydroxyimide and a dehydrating agent are mixed and a first reaction is carried out at 23-28°C for 6-14 h, preferably 10-13 h.

[0048]

[0049] (2) The product obtained from the first reaction is mixed with a compound having the structure of formula (IV), and a second reaction is carried out at a pH of 9-11 (e.g., 9.5-10.5) and a temperature of 23-28°C for 2-8 hours, preferably 4-6 hours. The product of the second reaction is then reduced at a pH of 1-3.

[0050] H2N—R3—COOH (IV).

[0051] Step (1) can be carried out in the presence of a first organic solvent (such as dichloromethane, trichloromethane, isopropanol, ethyl acetate, etc.). The amount of the first organic solvent is not particularly limited, but can be 1.5-3 L relative to 600 g of the compound having the structure shown in formula (III). For example, the compound having the structure shown in formula (III), N-hydroxyimide, and dehydrating agent can be added to cold, dry dichloromethane, stirred in an ice bath (to mix thoroughly) for about 0.8-1.5 h, and then heated to the temperature of the first reaction for reaction. Taking the case where R1 is a C6 straight-chain alkyl group and R2 is a C10 straight-chain alkylene group as an example, a white precipitate (N,N'-dicyclohexylurea, i.e., DCU) will be generated after the first reaction. The precipitate is removed by filtration, and the filtrate is concentrated (e.g., using a rotary evaporator) to precipitate the solid, which is then dried under vacuum to constant weight to obtain the product (active ester) obtained from the first reaction.

[0052] In step (1), the molar ratio of the compound having the structure shown in formula (III), the N-hydroxyimide and the dehydrating agent can be 1:(1-3):(1-3).

[0053] The N-hydroxyimide may be selected from N-hydroxysuccinimide (NHS) and / or N-hydroxymaleimide.

[0054] The dehydrating agent may be selected from at least one of N,N'-dicyclohexylcarbodiimide (DCC), N,N'-diisopropylcarbodiimide (DIC), and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC).

[0055] Step (2) can be carried out in the presence of a second organic solvent (e.g., acetone, diethyl ether, etc.). The amount of the second organic solvent is not particularly limited; for example, the amount of the second organic solvent can be 0.2-0.8 L relative to 100 g of the product obtained from the first reaction. The product obtained from the first reaction can be dissolved in the second organic solvent, and then a compound having the structure of formula (IV) can be added, followed by the addition of a component that provides an alkaline environment (e.g., triethylamine) to carry out the reaction. After the reaction, the second organic solvent is removed by vacuum distillation. Then, 1 mol / L hydrochloric acid can be added to reach the reducing pH, and then solid-liquid separation (e.g., filtration) can be performed to collect the product (the solid phase is the product), and it is washed with ice water. The washed solid phase is dissolved in a mixture of water and ethanol for recrystallization (the volume ratio of water to ethanol in the mixture can be 1:1-3, and the mass ratio of the solid phase to the mixture can be 1:5-10). After drying, a compound having the structure shown in formula (III) is obtained.

[0056] In step (2), the molar ratio of the product obtained from the first reaction to the compound having the structure of formula (IV) can be 100:(50-200) or 100:(90-110).

[0057] Among them, the compound having the structure of formula (IV) can be at least one of 20 currently known amino acids such as alanine, glutamic acid, lysine, cysteine, and leucine, preferably at least one of alanine, lysine, and cysteine.

[0058] According to the present invention, preferably, the mass amount of the zirconium-based additive is 1-6 wt%, more preferably 2-4 wt%, relative to the total mass amount of the lithium-based thickener, zirconium-based additive and base oil.

[0059] According to the present invention, preferably, the mass amount of lithium-based thickener is 1-40 wt%, more preferably 5-30 wt%, and more preferably 7-25 wt%, relative to the total mass amount of lithium-based thickener, zirconium-based additive and base oil.

[0060] According to the present invention, preferably, the mass content of the base oil is 50-95 wt% relative to the total mass content of the lithium-based thickener, zirconium-based additive and base oil, more preferably 60-90 wt%, and most preferably 75-90 wt%.

[0061] Under the above conditions, the overall performance of the lubricating grease can be further guaranteed.

[0062] Secondly, the present invention provides a lithium-based grease prepared by the method described above.

[0063] Thirdly, the present invention provides a lubricating grease containing a lithium-based thickener, a zirconium-based additive, and a base oil;

[0064] The zirconium-based additive has a structure as shown in formula (I).

[0065]

[0066] Wherein, R1 is selected from hydrogen, substituted or unsubstituted C2-C10 alkyl, substituted or unsubstituted C6-C18 aryl, R2 is selected from substituted or unsubstituted C2-C20 alkylene, and R3 is selected from substituted or unsubstituted C1-C8 alkylene.

[0067] The zirconium-based additive contains 0.1-10 wt% of the total mass of the grease.

[0068] It is understood that preferred types of lithium-based thickeners, base oils, and zirconium-based additives are as described in the first aspect.

[0069] Preferably, the zirconium-based additive has a mass content of 1-6 wt% relative to the total mass of the grease, more preferably 2-4 wt%.

[0070] Preferably, the lithium-based thickener has a mass content of 1-40 wt% relative to the total mass of the grease, more preferably 5-30 wt%, and even more preferably 7-25 wt%.

[0071] Preferably, the base oil content is 50-95 wt% relative to the total mass of the grease, more preferably 60-90 wt%, and most preferably 75-90 wt%.

[0072] According to a particularly preferred embodiment of the present invention, the lithium-based grease contains only the lithium-based thickener, zirconium-based additive and base oil as described above.

[0073] Fourthly, the present invention provides the use of zirconium-based additives as defined in the first aspect in improving the extreme pressure anti-wear properties and / or oxidation stability of lithium-based thickeners.

[0074] Zirconium-based additives can also play a partial thickening role in greases.

[0075] The present invention will be described in detail below through examples. In the following examples, the structure of the product obtained by the saponification reaction was confirmed by infrared spectroscopy; unless otherwise stated, the content of ZrO(OH)2·8H2O in the mixture of ZrO(OH)2·8H2O and water used below is 0.2 g / g of the mixture.

[0076] Example 1

[0077] 600g of 12-hydroxystearic acid (2mol), 412g of DCC (2mol), and 230g of NHS (2mol) were dissolved in 2L of cold, dry dichloromethane. The mixture was stirred in an ice bath for approximately 1 hour, then reacted at room temperature (25℃) for 10 hours. After the reaction was complete, the white precipitate N,N′-dicyclohexylurea (DCU) was removed by filtration. The filtrate was concentrated using a rotary evaporator, and the precipitated solid was dried under vacuum to constant weight. The product was the active ester and was used for later use. The reaction equation is as follows:

[0078]

[0079] Reaction formula (1)

[0080] 100g of active ester (0.25mol) was dissolved in 0.5L of acetone, 22.4g of alanine (0.25mol) was added, and then triethylamine (0.2L) was added as an alkaline solvent. The pH was about 10. The mixture was stirred at room temperature for about 4 hours, and the reaction was stopped. The acetone was removed by vacuum distillation. The pH of the reaction solution was adjusted to 2 with 1mol / L hydrochloric acid. The product was collected by filtration, washed with a large amount of ice water, recrystallized from a mixture of water and ethanol, and dried to obtain pure N-12-hydroxystearoylalanine (the structure was confirmed by infrared spectroscopy). 100g of the product was added to a mixture of ZrO(OH)2·8H2O and water (the amount was such that the mass ratio of N-12-hydroxystearoylalanine to ZrO(OH)2·8H2O was 100:37.3) for saponification reaction. The conditions included a reaction temperature of 90℃ and a reaction time of 1.5h. The final product N-12-hydroxystearoylalanine zirconium additive as shown in reaction formula (3) was obtained for later use. The reaction equation is as follows:

[0081]

[0082] Reaction formula (2)

[0083]

[0084] Reaction formula (3).

[0085] The above describes the preparation method of the additive. Next, we will describe the preparation process of the lubricating grease:

[0086] 450g of 500SN oil (kinematic viscosity of 11mm at 100℃) is added to a 2L reactor equipped with heating, stirring, circulation, and cooling systems. 240g of lithium stearate was stirred for 30 minutes, then heated to 215℃, and 10g of N-12-hydroxystearoylalanine zirconium additive was added. The mixture was kept at a constant temperature for 10 minutes, stirred, and cooled to room temperature. After homogenization and degassing by a three-roll mill, the finished product was obtained.

[0087] Grease composition: relative to the total mass of the grease, the base oil content is 90 wt%, the thickener content is 8 wt%, and the additive content is 2 wt%.

[0088] Example 2

[0089] 57g of ZrOCl2·8H2O was dissolved in 250g of water. An aqueous solution containing 15g of NaOH was slowly added to the above ZrOCl2 aqueous solution and stirred rapidly. Immediately, a large amount of white precipitate appeared. The precipitate was filtered and washed three times with 1000g of water to obtain ZrO(OH)2·8H2O, which was then set aside.

[0090] 600g of 12-hydroxystearic acid (2mol), 412g of DCC (2mol), and 230g of NHS (2mol) were dissolved in 2L of cold, dry dichloromethane. The mixture was first stirred in an ice bath for approximately 1 hour, then reacted at room temperature for 12 hours. After the reaction was complete, the white precipitate N,N′-dicyclohexylurea (DCU) was removed by filtration. The filtrate was concentrated using a rotary evaporator, and the precipitated solid was dried under vacuum to constant weight. The product was the active ester and was reserved for later use. The reaction equation is as follows:

[0091]

[0092] Reaction formula (1)

[0093] 100g of active ester (0.25mol) was dissolved in 0.5L of acetone, 37g of lysine (0.25mol) was added, and then triethylamine (0.2L) was added as an alkaline solvent. The pH was about 10. The mixture was stirred at room temperature for about 6 hours. The reaction was stopped, and the acetone was removed by vacuum distillation. The pH of the reaction solution was adjusted to 2 with 1mol / L hydrochloric acid. The product was collected by filtration, washed with a large amount of ice water, recrystallized from a mixture of water and ethanol, and dried to obtain pure N-12-hydroxystearoyl lysine (the structure was confirmed by infrared spectroscopy). 100g of the product was added to a mixture of ZrO(OH)2·8H2O and water (the amount was such that the mass ratio of N-12-hydroxystearoyl alanine to ZrO(OH)2·8H2O was 100:26.1) for saponification reaction. The conditions included a reaction temperature of 80℃ and a reaction time of 2 hours. The final product N-12-hydroxystearoyl lysine zirconium additive as shown in reaction formula (3) was obtained for later use. The reaction equation is as follows:

[0094]

[0095] Reaction formula (2)

[0096]

[0097] Reaction formula (3)

[0098] The above describes the preparation method of the additive. Next, we will describe the preparation process of the lubricating grease:

[0099] 450g of 500SN oil (kinematic viscosity of 11mm at 100℃) is added to a 2L reactor equipped with heating, stirring, circulation, and cooling systems. 2 40g of lithium 12-hydroxystearate was stirred for 30 minutes, then heated to 210℃. 10g of N-12-hydroxystearyl lysine zirconium additive was added, and the mixture was kept at a constant temperature for 11 minutes. The mixture was then stirred and cooled to room temperature. After homogenization and degassing by a three-roll mill, the finished product was obtained.

[0100] Grease composition: relative to the total mass of the grease, the base oil content is 90 wt%, the thickener content is 8 wt%, and the additive content is 2 wt%.

[0101] Example 3

[0102] Take the additive prepared in Example 1.

[0103] 450g of DOS oil (kinematic viscosity 4.3mm at 100℃) was added to a 2L reactor equipped with heating, stirring, circulation, and cooling systems. 2 40g of lithium stearate was stirred for 30 minutes, then heated to 220°C. 10g of the above additive was added, and the mixture was kept at a constant temperature for 10 minutes. The mixture was then stirred and cooled to room temperature. After homogenization and degassing by a three-roll mill, the finished product was obtained.

[0104] Grease composition: relative to the total mass of the grease, the base oil content is 90 wt%, the thickener content is 8 wt%, and the additive content is 2 wt%.

[0105] Example 4

[0106] Take the additive prepared in Example 2.

[0107] 400g of 500SN oil (kinematic viscosity of 11mm at 100℃) is added to a 2L reactor equipped with heating, stirring, circulation, and cooling systems. 2 80g of 12-hydroxystearic acid lithium was stirred for 30 minutes, then heated to 220℃, 20g of the above additive was added, the temperature was kept constant for 10 minutes, stirred and cooled to room temperature, and the finished product was obtained after homogenization and degassing by a three-roll mill.

[0108] Grease composition: Relative to the total mass of the grease, the base oil content is 80 wt%, the thickener content is 16 wt%, and the additive content is 4 wt%.

[0109] Comparative Example 1

[0110] 450g of 500SN oil (kinematic viscosity 11mm at 100℃) was added to a 2L reactor equipped with heating, stirring, circulation, and cooling systems. 2 50g of lithium 12-hydroxystearate was stirred for 30 minutes, then heated to 220℃ and held at that temperature for 10 minutes. The mixture was then stirred and cooled, homogenized, and degassed to obtain the final product.

[0111] Grease composition: The base oil content is 90 wt% and the thickener content is 10 wt% relative to the total mass of the grease.

[0112] Comparative Example 2

[0113] The grease was prepared according to the method in Example 1, except that 12-hydroxystearic acid was replaced with 2 mol of 3-hydroxymyristic acid during the preparation of the additive, i.e., reaction formulas (1), (2), and (3) are as follows:

[0114]

[0115] Reaction formula (1).

[0116]

[0117] Reaction formula (2)

[0118]

[0119] Reaction formula (3)

[0120] Test case

[0121] The physicochemical properties of the greases prepared in the above embodiments and comparative examples were tested, and the results are shown in Table 1.

[0122] Table 1

[0123]

[0124]

[0125] As can be seen from the results in Table 1, the lithium-based grease provided by this invention has excellent overall performance, especially excellent extreme pressure anti-wear and oxidation stability, which greatly improves the application performance of lithium-based grease.

[0126] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a lithium-based lubricating grease, characterized in that, The method includes: mixing a lithium-based thickener, a zirconium-based additive, and a base oil, and then heating and refining them; The zirconium-based additive has a structure as shown in formula (I). Wherein, R1 is selected from hydrogen, substituted or unsubstituted C2-C10 alkyl, substituted or unsubstituted C6-C18 aryl, R2 is selected from substituted or unsubstituted C2-C20 alkylene, and R3 is selected from substituted or unsubstituted C1-C8 alkylene. Of these, the amount of zirconium-based additives used is 0.1-10 wt% relative to the total mass of lithium-based thickeners, zirconium-based additives, and base oils.

2. The method according to claim 1, wherein, The heating and refining process is carried out at a temperature of 190-230℃ for 8-20 minutes.

3. The method according to claim 1, wherein, The lithium-based thickener is a fatty acid lithium thickener, preferably lithium stearate and / or lithium 12-hydroxystearate.

4. The method according to any one of claims 1-3, wherein, The base oil is at least one of mineral oil, synthetic oil, and vegetable oil; Preferably, the base oil has a kinematic viscosity of 3-180 mmHg at 100°C. 2 / s, preferably 4-60mm 2 / s.

5. The method according to any one of claims 1-3, wherein, R1 is selected from substituted or unsubstituted C3-C9 alkyl groups, preferably C5-C8 straight-chain alkyl groups; And / or, R2 is a substituted or unsubstituted C5-C15 alkylene group, preferably a C9-C12 straight-chain alkylene group; And / or, R3 is a substituted or unsubstituted C2-C5 alkylene group, preferably -CH(CH3)- or -C4H8-CH(NH2)-.

6. The method according to claim 1, wherein, The zirconium-based additive is selected from:

7. The method according to claim 1 or 6, wherein, The amount of zirconium-based additive is 1-6 wt%, preferably 2-4 wt%, relative to the total mass of lithium-based thickener, zirconium-based additive and base oil.

8. The method according to claim 1 or 3, wherein, The amount of lithium-based thickener used is 1-40 wt%, preferably 5-30 wt%, and more preferably 7-25 wt%, relative to the total mass of lithium-based thickener, zirconium-based additive, and base oil.

9. The method according to claim 1, wherein, The mass content of the base oil is 50-95 wt%, preferably 60-90 wt%, and most preferably 75-90 wt%, relative to the total mass content of the lithium-based thickener, zirconium-based additive, and base oil.

10. The lithium-based grease prepared by the method of any one of claims 1-9.

11. A lubricating grease, characterized in that, This grease contains lithium-based thickeners, zirconium-based additives, and base oils; The zirconium-based additive has a structure as shown in formula (I). Wherein, R1 is selected from hydrogen, substituted or unsubstituted C2-C10 alkyl, substituted or unsubstituted C6-C18 aryl, R2 is selected from substituted or unsubstituted C2-C20 alkylene, and R3 is selected from substituted or unsubstituted C1-C8 alkylene. The zirconium-based additive contains 0.1-10 wt% of the total mass of the grease.

12. The grease according to claim 11, wherein, The lithium-based thickener is a fatty acid lithium thickener, preferably lithium stearate and / or lithium 12-hydroxystearate; And / or, the base oil is at least one of mineral oil, synthetic oil and vegetable oil; And / or, the kinematic viscosity of the base oil at 100°C is 3-180 mmHg. 2 / s, preferably 4-60mm 2 / s.

13. The grease according to claim 11 or 12, wherein, R1 is selected from substituted or unsubstituted C3-C9 alkyl groups, preferably C5-C8 straight-chain alkyl groups; And / or, R2 is a substituted or unsubstituted C5-C15 alkylene group, preferably a C9-C12 straight-chain alkylene group; And / or, R3 is a substituted or unsubstituted C2-C5 alkylene group, preferably -CH(CH3)- or -C4H8-CH(NH2)-.

14. The grease according to claim 11 or 12, wherein, The zirconium-based additive is selected from:

15. The grease according to claim 11, wherein, The zirconium-based additive has a mass content of 1-6 wt%, preferably 2-4 wt%, relative to the total mass of the grease.

16. The grease according to claim 11 or 12, wherein, The lithium-based thickener has a mass content of 1-40 wt% relative to the total mass of the grease, preferably 5-30 wt%, and more preferably 7-25 wt%.

17. The grease according to claim 11 or 12, wherein, The base oil content is 50-95 wt% relative to the total mass of the grease, preferably 60-90 wt%, and most preferably 75-90 wt%.

18. The use of the zirconium-based additive as defined in any one of claims 1-9 in improving the extreme pressure anti-wear properties and / or oxidation stability of lithium-based thickeners.

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