Complex lithium-based lubricating grease and preparation method thereof

Abstract

The invention provides composite lithium-based lubricating grease and a preparation method thereof. The composite lithium-based lubricating grease comprises lubricating base oil, a composite lithium-based thickening agent and an additive, wherein the lubricating base oil comprises base oil (I) and base oil (II), and the base oil (I) is a trimethylolpropane ester composition; the trimethylolpropane ester composition comprises the following components: (a) # imgabs0 #, (b) # imgabs1 # and (c) # imgabs2 #, wherein R1, R2 and R3 groups are respectively and differently selected from C4-C9 straight chain or branched chain alkyl groups, and the carbon numbers in the R1, R2 and R3 groups are different from one another; the molar ratio of the component (a) to the component (b) to the component (c) is 1: (1.7-2.3): (0.7-1.3); the base oil (II) is selected from one or more of synthetic oil, mineral oil and vegetable oil. The composite lithium-based lubricating grease provided by the invention has excellent high and low temperature performance, good colloid stability, excellent mechanical stability and excellent oxidation resistance.

Description

Technical Field

[0001] The invention relates to a lubricating grease, in particular to a composite lithium-based lubricating grease with excellent high and low temperature performance. Background Art

[0002] Grease is a necessary working medium for the normal operation of mechanical equipment and the manufacturing and processing of materials. With the progress and development of the machinery industry, more stringent requirements have gradually been put forward for related grease products. For example, some special grease products are required to have excellent low-temperature performance, thermal oxidation stability, low volatility and radiation resistance, etc.

[0003] In some special applications, grease needs to take into account both high and low temperature performance. It must be stable and low volatile at high temperatures, while still being able to ensure sufficient lubrication performance at low temperatures. This places very high demands on the base oil used in the grease.

[0004] Polyol ester base oils have good high and low temperature performance and additive sensitivity and are widely used in aviation lubricants. By adjusting the substituents, polyol ester products with different performances can be obtained. IN338518B and US3309318A reported the performance comparison of polyol esters prepared using different raw acid. However, synthetic ester base oils that take into account both excellent high temperature performance and low temperature performance are still rare in the prior art. Developing polyol ester base oils with better low temperature performance and low volatility to prepare greases for use in specific working conditions is still the research and development direction of those skilled in the art. Summary of the invention

[0005] The invention provides a composite lithium-based grease and a preparation method thereof.

[0006] The composite lithium-based grease of the present invention comprises, based on the total weight of the grease, 65% to 95% of a lubricating base oil, 3% to 30% of a composite lithium-based thickener, and 1% to 10% of an additive; wherein the lubricating base oil comprises a base oil (I) and a base oil (II), wherein the base oil (I) is a trimethylolpropane ester composition; and the trimethylolpropane ester composition comprises the following components:

[0007]

[0008] Where R 1 , R 2 , R 3 The groups are each selected from C4 to C9 straight or branched alkyl groups, and R 1 , R 2 , R 3The carbon numbers in the groups are different from each other; the molar ratio between the components (a), (b), and (c) is 1: (1.7-2.3): (0.7-1.3);

[0009] The base oil (II) is selected from one or more of synthetic oil, mineral oil and vegetable oil.

[0010] According to the present invention, R 1 , R 2 , R 3 The carbon numbers of the groups are different from each other in the C4 straight chain or branched chain alkyl, C5 straight chain or branched chain alkyl, C6 straight chain or branched chain alkyl, C7 straight chain or branched chain alkyl, C8 straight chain or branched chain alkyl, and C9 straight chain or branched chain alkyl. For example, R 1 , R 2 , R 3 The groups are each selected from n-heptyl, n-pentyl, and n-hexyl groups; or, R 1 , R 2 , R 3 The groups are each selected from n-heptyl, n-octyl, and n-nonyl groups; or, R 1 , R 2 , R 3 The groups are each selected from n-hexyl, n-butyl and n-pentyl groups.

[0011] According to the present invention, optionally, R 1 The group is selected from n-heptyl, R 2 , R 3 The groups are each selected from n-pentyl and n-hexyl groups; or, R 1 The group is selected from n-hexyl, R 2 , R 3 The groups are each selected from n-pentyl and n-heptyl; or, R 1 The group is selected from n-heptyl, R 2 , R 3 The groups are each selected from n-octyl and n-nonyl groups; or, R 1 The group is selected from n-hexyl, R 2 , R 3 The groups are each selected from n-butyl and n-pentyl groups.

[0012] According to the present invention, the preparation method of the trimethylolpropane ester composition comprises the following steps:

[0013] (1) allowing trimethylolpropane to undergo an alcohol hydroxyl group protecting reaction with an alcohol hydroxyl group protecting agent to obtain a monohydroxyl product;

[0014] (2) the monohydroxy product obtained in step (1) is reacted with R 1 COX undergoes an acylation reaction to obtain an acylated product;

[0015] (3) subjecting the acylated product obtained in step (2) to a deprotection reaction of the alcoholic hydroxyl group to obtain a dihydroxy product;

[0016] (4) making the dihydroxy product obtained in step (3) and R 2 COX', R 3 COX' undergoes acylation reaction and collects the product;

[0017] Among them, R 1 , R 2 , R 3 The groups are each selected from C4 to C9 straight or branched alkyl groups, and R 1 , R 2 , R 3 The carbon numbers in the groups are different from each other; the X group is selected from F, Cl, Br, I, OH; the X' groups are each independently selected from F, Cl, Br, I, OH; the R 1 COX, R 2 COX', R 3 The molar ratio between COX' is 1:(0.9~1.2):(0.9~1.2).

[0018] According to the present invention, in step (1), the molar ratio of trimethylolpropane to the alcoholic hydroxyl protecting agent can be 1:2 to 200, preferably 1:10 to 50; the temperature of the alcoholic hydroxyl protecting reaction can be -20 to 80°C, preferably 15 to 70°C; the time of the alcoholic hydroxyl protecting reaction can be 1 to 120 hours, preferably 30 to 100 hours.

[0019] According to the present invention, in step (1), the alcoholic hydroxyl protecting agent can be selected from one or more of acetone, 2,2-dimethoxypropane and 2-methoxypropylene, preferably acetone. When acetone is selected as the alcoholic hydroxyl protecting agent, the unreacted acetone can play the role of a solvent to promote the smooth progress of the reaction, so the amount of acetone added can be excessive, generally in excess to the amount of solvent added in the alcoholic hydroxyl protection reaction. The unreacted acetone can be removed by distillation, rectification or other methods known in the art after the reaction is completed.

[0020] According to the present invention, a first solvent may be added to the reaction in step (1), and the first solvent may be one or more of ethyl acetate, dichloromethane, chloroform, toluene and acetonitrile. The first solvent may be removed by distillation, rectification or other methods known in the art after the reaction is completed. In step (1), the volume ratio between the alcoholic hydroxyl protecting agent and the first solvent may be 10:1 to 1:20. When acetone is selected as the alcoholic hydroxyl protecting agent, the first solvent may be added to carry out the alcoholic hydroxyl protection reaction, or the first solvent may not be added. When acetone is selected as the alcoholic hydroxyl protecting agent and the first solvent is not added, because the unreacted acetone can play the role of a solvent to promote the smooth progress of the reaction, the amount of acetone added may be excessive, generally to the sum of the amount added as the alcoholic hydroxyl protecting agent and the amount added of the first solvent.

[0021] According to the present invention, an acidic catalyst may be added in step (1), and the acidic catalyst may be selected from one or more of p-toluenesulfonic acid, hydrochloric acid, sulfuric acid, benzenesulfonic acid and dodecylbenzenesulfonic acid; the molar ratio between the acidic catalyst and trimethylolpropane may be 1:10 to 1000, preferably 1:20 to 800. After the reaction is completed, the acidic catalyst may be removed by one or more of alkali neutralization, solvent extraction and water washing methods, and the alkali in the alkali neutralization method may be selected from one or more of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide or aqueous solutions of these substances, and the solvent in the solvent extraction method may be the first solvent described above.

[0022] According to the present invention, in step (1), the monohydroxy product obtained after the reaction may be purified, or the monohydroxy product obtained after the reaction may be directly subjected to step (2) without being purified. The purification method may include one or more of solvent extraction, water washing, drying, filtering, and solvent removal methods, and is not particularly limited. The solvent in the solvent extraction may use the first solvent described above.

[0023] According to the present invention, in step (2), the monohydroxy product obtained in step (1) is reacted with R 1 The molar ratio of COX can be 1:0.5-2, preferably 1:0.8-1.5; the reaction temperature can be 0-80°C, preferably 15-70°C, and the reaction time can be 1-48 hours, preferably 5-40 hours.

[0024] According to the present invention, a second solvent and / or an alkaline catalyst may be added to the reaction of step (2). The second solvent may be one or more of tetrahydrofuran, dichloromethane, chloroform, acetone, ethyl acetate and acetonitrile, preferably dichloromethane. The second solvent may be removed by distillation, rectification or other methods known in the art after the reaction. The alkaline catalyst may be one or more of triethylamine, tert-butylamine, pyridine, diisopropylethylamine and hexamethyldisilazane, preferably triethylamine. Based on the monohydroxy product obtained in step (1), the mass ratio of the second solvent to the monohydroxy product obtained in step (1) is 1:0.02-0.5, preferably 1:0.05-0.25; the molar ratio of the alkaline catalyst to the monohydroxy product obtained in step (1) is 1:0.5-2, preferably 1:0.8-1.5.

[0025] According to the present invention, in step (2), the acylated product obtained after the reaction may be purified, or the acylated product obtained after the reaction may be directly subjected to step (3) without being purified. The purification method may include one or more of filtration, acid washing, alkali washing, water washing, drying, solvent extraction, and solvent removal, and is not particularly limited. The purpose of the acid washing method is to remove the alkaline catalyst in step (2), and the purpose of the alkali washing method is to remove R 1 The solvent may be the second solvent described above.

[0026] According to the present invention, in step (3), the acylation product obtained in step (2) can be subjected to a deprotection reaction of the alcoholic hydroxyl group with a C1-C5 alcohol or an acid solution.

[0027] According to the present invention, in step (3), the C1-C5 alcohol may be one or more of methanol, ethanol, propanol, isopropanol, butanol and pentanol, preferably methanol; the acid solution may be an aqueous solution of an inorganic acid, for example, one or more of a hydrochloric acid aqueous solution, a sulfuric acid aqueous solution, a nitric acid aqueous solution and a phosphoric acid aqueous solution, preferably a hydrochloric acid aqueous solution, more preferably a hydrochloric acid aqueous solution with a molar concentration of 0.5 to 2M.

[0028] According to the present invention, in step (3), the molar concentration of the acylated product obtained in step (2) in the solution formed by the C1-C5 alcohol, the acid solution and the acylated product obtained in step (2) is 0.5-5 mol / L, preferably 1-2.5 mol / L; the acid solution is prepared by mixing H +The molar ratio of the acylated product obtained in step (2) to the acid solution can be 1:0.01-1, preferably 1:0.05-0.25; the reaction temperature can be 20-80°C, preferably 30-70°C; the reaction time can be 1-48 hours, preferably 5-40 hours.

[0029] According to the present invention, in step (3), the dihydroxy product obtained after the reaction may be purified, or the dihydroxy product obtained after the reaction may be directly subjected to step (4) without being purified. The purification method may include one or more of solvent extraction, water washing, drying, filtering, and solvent removal. The solvent may be a third solvent. The third solvent may be one or more of ethyl acetate, tetrahydrofuran, dichloromethane, chloroform, acetone, and acetonitrile, preferably ethyl acetate. The third solvent may be removed after the purification by distillation, rectification, or other methods known in the art. In step (3), the mass ratio between the acylated product obtained in step (2) and the third solvent is 1:1 to 20, preferably 1:2 to 10.

[0030] According to the present invention, in step (4), the dihydroxy product obtained in step (3) is reacted with R 2 COX', R 3 The molar ratio of COX' can be 1:0.8-1.5:0.8-1.5, preferably 1:1.0-1.3:1.0-1.3; the reaction temperature can be 0-80°C, preferably 15-70°C, and the reaction time can be 1-48 hours, preferably 5-40 hours.

[0031] According to the present invention, a carbodiimide condensation reagent and / or an activator may be added in step (4). The carbodiimide condensation reagent may be one or more of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCI), dicyclohexylcarbodiimide (DCC) and N,N'-diisopropylcarbodiimide (DIC), preferably 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCI). The activator may be one or more of 4-dimethylaminopyridine (DMAP), 1-hydroxybenzotriazole (HOBt) and 1-hydroxy-7-azabenzotriazole (HOAt), preferably 4-dimethylaminopyridine (DMAP). The molar ratio between the dihydroxy product obtained in step (3) and the carbodiimide condensation reagent is 1:0.5-2, preferably 1:0.8-1.5; the molar ratio between the dihydroxy product obtained in step (3) and the activator is 1:0.01-0.5, preferably 1:0.05-0.1.

[0032] According to the present invention, a fourth solvent may be added in the reaction of step (4), and the fourth solvent may be one or more of dichloromethane, ethyl acetate, tetrahydrofuran, chloroform, acetone and acetonitrile, preferably dichloromethane. In step (4), the mass ratio between the dihydroxy product obtained in step (3) and the fourth solvent is 1:0.5-10, preferably 1:1-5. The fourth solvent may be removed by distillation, rectification or other methods known in the art after the reaction is completed.

[0033] According to the present invention, in step (4), the crude product obtained after the reaction can be purified to obtain the final reaction product. The purification method can include one or more of solvent extraction, acid washing, alkali washing, water washing, drying, filtering, and solvent removal. The solvent in the solvent extraction method can be the fourth solvent described above.

[0034] The trimethylolpropane ester composition of the present invention has excellent high and low temperature performance, low pour point, and low evaporation loss, and is suitable for use as a base oil for lubricating grease. The preparation method of the trimethylolpropane ester composition of the present invention has mild reaction conditions and high product purity.

[0035] According to the present invention, the base oil (II) can be selected from one or more of synthetic oil, mineral oil and vegetable oil. The synthetic oil can be one or more of polyalphaolefin oil, ester oil, fluorine oil and silicone oil. Common trade names or products include PAO4, PAO6, PAO8, PAO10, monoester, diester, polyol ester, complex ester, polyester, methyl silicone oil, etc. The mineral oil can be one or more of paraffin base oil, intermediate base oil and naphthenic base oil. Common trade names or grades include 500N, 150BS, HVI Ia, HVI Ib, HVI Ic, HVI II, HVI III, etc. The vegetable oil can be one or more of castor oil, rapeseed oil, peanut oil and soybean oil. The base oil (II) preferably has a kinematic viscosity of 2 to 60 mm at 100°C. 2 / s lubricating base oil, preferably with a kinematic viscosity of 3 to 30 mm at 100°C 2 / s lubricating base oil.

[0036] According to the present invention, the composite lithium-based thickener is preferably obtained by saponification reaction of an acid with lithium hydroxide. The acid is a mixed acid of a fatty acid and an auxiliary acid, and the fatty acid is preferably selected from C 12 ~C 20 Fatty acids and / or C 12 ~C 20The hydroxy fatty acid may be one or more of lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid and 12-hydroxystearic acid, more preferably 12-hydroxystearic acid and / or stearic acid; the auxiliary acid is preferably selected from one or more of acetic acid, propionic acid, butyric acid, valeric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, terephthalic acid, phosphoric acid and boric acid, more preferably sebacic acid and / or azelaic acid. The molar ratio of the fatty acid to the auxiliary acid is preferably 0.1 to 10:2, more preferably 0.5 to 5:2. The composite lithium-based thickener obtained by the saponification reaction can be directly subjected to the subsequent preparation process. The temperature of the saponification reaction is preferably 60-180°C, more preferably 70-160°C. The time of the saponification reaction is preferably 30-300min, more preferably 50-240min. Water is preferably added in the saponification reaction. The water can directly participate in the saponification reaction, or can be mixed with the lithium hydroxide to form a solution and then participate in the saponification reaction. The base oil (II) can also be added in the saponification reaction. The mixture of the composite lithium-based thickener and the base oil (II) obtained by the saponification reaction can be directly subjected to the subsequent preparation process. In the lubricating base oil, the mass ratio between the base oil (I) and the base oil (II) can be 1:0.2-5; preferably 1:0.5-2.

[0037] According to the present invention, the additives include oiliness agent, extreme pressure anti-wear agent and antioxidant. The oiliness agent can be selected from benzotriazole fatty amine and sulfurized olefin cottonseed oil; the extreme pressure anti-wear agent can be selected from one or more of aminothioester, sulfurized isobutylene, di-n-butyl phosphite, tricresyl phosphate, triphenyl thiophosphate and dialkyl dithiocarbamate; the antioxidant can be selected from one or more of 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, dialkyl diphenylamine, N-phenyl-α-naphthylamine and 3,5-di-tert-butyl-4-hydroxyphenyl methyl acrylate.

[0038] According to the present invention, the weight ratio of the oiliness agent, the extreme pressure anti-wear agent and the antioxidant is preferably 1:1-50:1-30, more preferably 1:5-30:5-20.

[0039] The preparation method of the composite lithium-based grease of the present invention comprises: refining the composite lithium-based thickener and part of the lubricating base oil at a constant temperature of 180-230° C., cooling, adding the additive and the remaining lubricating base oil, and grinding into grease. The constant temperature refining time is preferably 1-25 minutes.

[0040] The composite lithium-based lubricating grease of the present invention has excellent high and low temperature performance, and has good colloidal stability, excellent mechanical stability and excellent anti-oxidation performance. The composite lithium-based lubricating grease of the present invention can be competent for harsh working conditions such as high temperature, low temperature, high speed, high load, and high water content. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is the gas chromatogram of the crude product of step (4) in Example 1. DETAILED DESCRIPTION

[0042] The present invention is described below by means of specific embodiments, but the present invention is not limited thereto.

[0043] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified. Unless otherwise specified, the percentages in the present invention are all mass percentages.

[0044] Main raw material sources:

[0045] Trimethylolpropane, Aladdin Biochemical Technology Co., Ltd., analytical grade;

[0046] Acetone, Sinopharm Chemical Reagent Co., Ltd., analytical grade;

[0047] 2-Methoxypropylene, Aladdin Biochemical Technology Co., Ltd., analytical grade;

[0048] 2,2-Dimethoxypropane, Aladdin Biochemical Technology Co., Ltd., analytical grade;

[0049] p-Toluenesulfonic acid monohydrate, Sinopharm Chemical Reagent Co., Ltd., analytical grade

[0050] Potassium carbonate, Sinopharm Chemical Reagent Co., Ltd., analytical grade

[0051] Ethyl acetate was purchased from Sinopharm Chemical Reagent Co., Ltd., analytical grade;

[0052] Dichloromethane, Sinopharm Chemical Reagent Co., Ltd., analytical grade;

[0053] Triethylamine, analytical grade, Sinopharm Chemical Reagent Co., Ltd.

[0054] Octanoyl chloride, Aladdin Biochemical Technology Co., Ltd., analytical grade;

[0055] Heptanoyl chloride, Aladdin Biochemical Technology Co., Ltd., analytical grade;

[0056] DMAP, Beijing Inokai Technology Co., Ltd., analytical grade;

[0057] Hexanoic acid, Beijing Inokai Technology Co., Ltd., analytical grade;

[0058] n-Heptanoic acid, Beijing Inokai Technology Co., Ltd., analytical grade;

[0059] Octanoic acid, Beijing Inokai Technology Co., Ltd., analytical grade;

[0060] N-nonanoic acid, Beijing Inokai Technology Co., Ltd., analytical grade;

[0061] Decanoic acid, Beijing Inokai Technology Co., Ltd., analytical grade;

[0062] EDCI, Beijing Inokai Technology Co., Ltd., analytical grade;

[0063] Comparison of polyol esters, trimethylolpropane n-heptanoate, Nico, France, industrial product;

[0064] T406, benzotriazole fatty octadecylamine salt, Huihua Petroleum Additives Co., Ltd., industrial product;

[0065] N-phenyl-α-naphthylamine, Aladdin Biochemical Technology Co., Ltd., analytical grade;

[0066] Dialkyl dithiocarbamate, Changsha Wangcheng Petrochemical Co., Ltd., industrial products.

[0067] Example 1: Synthesis of trimethylolpropane ester composition 1 (structural formulas I-a1, I-a2 and I-a3)

[0068] (1) Weigh trimethylolpropane (100 g, 745.32 mmol) in a 1 L reaction bottle, add acetone 700 mL, add p-toluenesulfonic acid monohydrate (1.42 g, 7.45 mmol), stir at room temperature for 3 days, add potassium carbonate (1.03 g, 7.45 mmol), stir at room temperature for 1 hour to generate a suspension. Remove acetone from the suspension by rotary evaporation, add 700 mL of ethyl acetate to dissolve, wash twice with water (2*200 mL), then dry with anhydrous sodium sulfate, filter and spin dry the solvent to obtain the product of step (1). The H NMR spectrum of the product of step (1) is: 1 H-NMR (700MHz, CDCl3) δ (ppm) = 3.72 (s, 2H), 3.70-3.60 (m, 4H), 2.80 (br, 1H), 1.43 (s, 3H), 1.39 (s, 3H), 1.30 (q, J = 7.0 Hz, 2H), 0.84 (t, J = 7.0 Hz, 3H). The NMR carbon spectrum of the product of step (1) is: 13 C-NMR (175MHz, CDCl3) δ (ppm) = 99.27, 65.25, 62.54, 37.05, 27.35, 23.86, 20.38, 7.12.

[0069] (2) Add the product of step (1) (58.72 g, 0.3336 mol), 500 mL of dichloromethane, and triethylamine (37.14 g, 0.367 mol) to a reaction flask, stir at room temperature, and dropwise add octanoyl chloride (59.72 g, 0.367 mol) to the reaction system, and react for 12 hours under stirring at room temperature. Filter to remove solids, wash the filtrate twice with saturated sodium bicarbonate solution, wash three times with water, and dry over anhydrous sodium sulfate. Filter and spin dry the solvent to obtain the product of step (2). The H NMR spectrum of the product of step (2) is: 1 H-NMR (700MHz, CDCl3) δ (ppm) = 4.19 (s, 2H), 3.70-3.61 (m, 4H), 2.33 (t, J = 7.6Hz, 2H), 1.70-1.60 (m, 4H), 1.42 (s, 3H), 1.39 (s, 3H), 1.37-1.22 (m, 10H), 0.88 (t, J = 7.0Hz, 3H), 0.83 (t, J = 7.8Hz, 3H). The NMR carbon spectrum of the product of step (2) is: 13 C-NMR (175MHz, CDCl3) δ (ppm) = 173.9, 97.4, 65.2, 63.9, 37.2, 34.4, 31.8, 29.2, 29.1, 26.8, 25.1, 24.1, 22.7, 20.8, 14.2, 7.1.

[0070] (3) The product of step (2) was dissolved in methanol (200 mL), 40 mL of 1 M hydrochloric acid was prepared and added to the reaction bottle, and the reaction was carried out at 40° C. for 24 hours. The crude product was spin-dried, and then 350 mL of ethyl acetate was added to dissolve it, and it was washed with water for several times. When the pH test paper showed that the washed water phase was neutral, it was dried with anhydrous sodium sulfate, filtered and spin-dried to obtain the product of step (3). The nuclear magnetic hydrogen spectrum of the product of step (3) is: 1 H-NMR (700MHz, CDCl3) δ (ppm) = 4.16 (s, 2H), 3.56 (dd, J = 21.0, 7.0Hz, 4H), 3.41 (br, 2H), 2.35 (t, J = 7.6Hz, 2H), 1.70-1.60 (m, 2H), 1.42-1.21 (m, 10H), 0.92-0.85 (m, 6H). The nuclear magnetic carbon spectrum of the product of step (3) is: 13 C-NMR (175MHz, CDCl3) δ (ppm) = 175.1, 65.5, 64.1, 42.9, 34.5, 31.8, 29.2, 29.1, 25.2, 22.7, 22.5, 14.2, 7.5.

[0071] (4) The product of step (3) (i.e., diol compound) (169.26 g, 0.65 mol) was dissolved in 400 mL of dichloromethane, and DMAP (15.86 g, 0.13 mol), n-hexanoic acid (90.48 g, 0.78 mol) and n-heptanoic acid (101.4 g, 0.78 mol) were added. Then, EDCI (299.52 g, 1.56 mol) was added to the system and stirred at room temperature for 12 hours to obtain a crude product. A small amount of crude product sample was extracted and subjected to gas chromatography analysis. The results are shown in FIG. Figure 1 The crude product was washed with 1M hydrochloric acid solution, washed twice with water, the dichloromethane solvent was removed by rotary evaporation, and the excess acid was removed by reduced pressure distillation. After reduced pressure distillation, the product was washed with 1% potassium hydroxide solution at 80°C, then washed twice with water, and dried to obtain 300g of the final product, which is the trimethylolpropane ester composition 1 of the present invention. The mass spectrum data of the final product include: HRMS (FT-ICRMS) calculation for C 26 H 48 NaO6(M+Na):479.3343,found:479.3340;calcd for C 27 H 50 NaO6(M+Na):493.3500,found:493.3494; calcd for C 28 H 52 NaO6(M+Na):507.3656,found:507.3653. Figure 1 The gas chromatography results of the crude product in step (4) show that a mixture of three compounds is obtained after the reaction, and the molar ratio between the three compounds is close to 1:2:1.

[0072] After structural identification, the final product synthesized is indeed a composition of the target compound trimethylolpropane ester (structural formulas are I-a1, I-a2 and I-a3).

[0073] The synthetic reaction formula of Example 1 is shown below.

[0074]

[0075] Example 2: Synthesis of trimethylolpropane ester composition 2 (structural formulas I-b1, I-b2 and I-b3)

[0076] (1) Weigh trimethylolpropane (100.05 g, 745.32 mmol) in a 1 L reaction bottle, add 700 mL of dichloromethane and 2,2-dimethoxypropane (2329 g, 22.36 mol), add p-toluenesulfonic acid monohydrate (1.418 g, 7.45 mmol), stir at room temperature for 3 days, add potassium carbonate (1.037 g, 7.45 mmol), stir at room temperature for 1 hour to generate a suspension. Remove the solvent from the suspension by rotary evaporation, add 700 mL of ethyl acetate to dissolve, wash twice with water (2*200 mL), then dry with anhydrous sodium sulfate, filter and dry the solvent to obtain the product of step (1). The H NMR spectrum of the product of step (1) is: 1 H-NMR (700MHz, CDCl3) δ (ppm) = 3.72 (s, 2H), 3.70-3.60 (m, 4H), 2.80 (br, 1H), 1.43 (s, 3H), 1.39 (s, 3H), 1.30 (q, J = 7.0 Hz, 2H), 0.84 (t, J = 7.0 Hz, 3H). The NMR carbon spectrum of the product of step (1) is: 13 C-NMR (175MHz, CDCl3) δ (ppm) = 99.27, 65.25, 62.54, 37.05, 27.35, 23.86, 20.38, 7.12.

[0077] (2) Add the product of step (1) (58.74 g, 0.3336 mol), 500 mL of dichloromethane, and triethylamine (37.18 g, 0.367 mol) to a reaction flask, stir at room temperature, and dropwise add heptanoyl chloride (54.55 g, 0.367 mol) to the reaction system, and react for 12 hours under stirring at room temperature. Filter to remove solids, wash the filtrate twice with saturated sodium bicarbonate solution, wash three times with water, and dry over anhydrous sodium sulfate. Filter and spin dry the solvent to obtain the product of step (2). The H NMR spectrum of the product of step (2) is: 1 H-NMR (700MHz, CDCl3) δ (ppm) = 4.18 (s, 2H), 3.71-3.61 (m, 4H), 2.34 (t, J = 7.6Hz, 2H), 1.70-1.60 (m, 4H), 1.43 (s, 3H), 1.40 (s, 3H), 1.38-1.22 (m, 8H), 0.88 (t, J = 7.0Hz, 3H), 0.82 (t, J = 7.8Hz, 3H). The nuclear magnetic carbon spectrum of the product of step (2) is: 13 C-NMR (175MHz, CDCl3) δ (ppm) = 174.0, 97.5, 65.1, 63.8, 37.3, 34.5, 31.7, 29.3, 26.9, 25.2, 22.7, 22.4, 20.9, 14.2, 7.1.

[0078] (3) The product of step (2) was dissolved in methanol (200 mL), 40 mL of 1M hydrochloric acid was prepared and added to the reaction bottle, and the reaction was carried out at 40°C for 24 hours. The crude product was spin-dried, and then 350 mL of ethyl acetate was added to dissolve it, and it was washed with water for several times. When the pH test paper showed that the washed water phase was neutral, it was dried with anhydrous sodium sulfate, filtered and spin-dried to obtain the product of step (3). The nuclear magnetic hydrogen spectrum of the product of step (3) is: 1 H-NMR (700MHz, CDCl3) δ (ppm) = 4.18 (s, 2H), 3.57 (dd, J = 21.0, 7.0 Hz, 4H), 3.40 (br, 2H), 2.33 (t, J = 7.6 Hz, 2H), 1.75-1.60 (m, 2H), 1.44-1.21 (m, 8H), 0.94-0.85 (m, 6H). The nuclear magnetic carbon spectrum of the product of step (3) is: 13 C-NMR (175MHz, CDCl3) δ (ppm) = 175.4, 65.3, 64.2, 43.1, 34.4, 31.6, 29.2, 25.2, 22.7, 22.5, 14.2, 7.5.

[0079] (4) The product of step (3) (160.17 g, 0.65 mol) was dissolved in 400 mL of dichloromethane, DMAP (15.88 g, 0.13 mol), hexanoic acid (90.55 g, 0.78 mol) and octanoic acid (112.48 g, 0.78 mol) were added, and then EDCI (300.10 g, 1.56 mol) was added to the system and stirred at room temperature for 12 hours. The crude product was washed with 1 M hydrochloric acid solution, washed twice with water, and the dichloromethane solvent was removed by rotary evaporation, and the excess acid was removed by vacuum distillation. After vacuum distillation, the product was washed with 1% potassium hydroxide solution at 80° C., then washed twice with water, and dried to obtain 307 g of the final product, which was the trimethylolpropane ester composition 2 of the present invention. The mass spectrum data of the final product include: HRMS (FT-ICRMS) calculation for C 25 H 46 NaO6(M+Na):465.3187,found:465.3192; calcd for C 27 H 50 NaO6(M+Na):493.3500,found:493.3504; calcd for C 29 H 54 NaO6(M+Na):521.3813,found:521.3819.

[0080] After structural identification, the final product synthesized is indeed a composition of the target compound trimethylolpropane ester (structural formula I-b1, I-b2 and I-b3).

[0081] The synthetic reaction formula of Example 2 is shown below.

[0082]

[0083] Example 3: Synthesis of trimethylolpropane ester composition 3 (structural formulas I-d1, I-d2 and I-d3)

[0084] (1) Weigh trimethylolpropane (100.10 g, 745.32 mmol) in a 1 L reaction bottle, add acetone 700 mL, add p-toluenesulfonic acid monohydrate (1.416 g, 7.45 mmol), stir at room temperature for 3 days, add potassium carbonate (1.030 g, 7.45 mmol), stir at room temperature for 1 hour to generate a suspension. Remove acetone from the suspension by rotary evaporation, add 700 mL of ethyl acetate to dissolve, wash twice with water (2*200 mL), and then dry over anhydrous sodium sulfate. Filter and spin dry the solvent to obtain the product of step (1). The H NMR spectrum of the product of step (1) is: 1 H-NMR (700MHz, CDCl3) δ (ppm) = 3.72 (s, 2H), 3.70-3.60 (m, 4H), 2.80 (br, 1H), 1.43 (s, 3H), 1.39 (s, 3H), 1.30 (q, J = 7.0 Hz, 2H), 0.84 (t, J = 7.0 Hz, 3H). The NMR carbon spectrum of the product of step (1) is: 13 C-NMR (175MHz, CDCl3) δ (ppm) = 99.27, 65.25, 62.54, 37.05, 27.35, 23.86, 20.38, 7.12.

[0085] (2) Add the product of step (1) (58.73 g, 0.3336 mol), 500 mL of dichloromethane, and triethylamine (37.17 g, 0.367 mol) to a reaction flask, stir at room temperature, and dropwise add heptanoyl chloride (54.55 g, 0.367 mol) to the reaction system, and stir at room temperature for 12 hours. Filter to remove solids, wash the filtrate twice with saturated sodium bicarbonate solution, wash three times with water, and dry over anhydrous sodium sulfate. Filter and spin dry the solvent to obtain the product of step (2). The H NMR spectrum of the product of step (2) is: 1H-NMR (700MHz, CDCl3) δ (ppm) = 4.18 (s, 2H), 3.71-3.61 (m, 4H), 2.34 (t, J = 7.6 Hz, 2H), 1.70-1.60 (m, 4H), 1.43 (s, 3H), 1.40 (s, 3H), 1.38-1.22 (m, 8H), 0.88 (t, J = 7.0 Hz, 3H), 0.82 (t, J = 7.8 Hz, 3H). The NMR carbon spectrum of the product of step (1) is: 13 C-NMR (175MHz, CDCl3) δ (ppm) = 174.0, 97.5, 65.1, 63.8, 37.3, 34.5, 31.7, 29.3, 26.9, 25.2, 22.7, 22.4, 20.9, 14.2, 7.1.

[0086] (3) The product of step (2) was dissolved in methanol (200 mL), 40 mL of 1M hydrochloric acid was prepared and added to the reaction bottle, and the reaction was carried out at 40°C for 24 hours. The crude product was spin-dried, and then 350 mL of ethyl acetate was added to dissolve it, and it was washed with water for several times. When the pH test paper showed that the washed water phase was neutral, it was dried with anhydrous sodium sulfate, filtered and spin-dried to obtain the product of step (3). The nuclear magnetic hydrogen spectrum of the product of step (3) is: 1 H-NMR (700MHz, CDCl3) δ (ppm) = 4.18 (s, 2H), 3.57 (dd, J = 21.0, 7.0 Hz, 4H), 3.40 (br, 2H), 2.33 (t, J = 7.6 Hz, 2H), 1.75-1.60 (m, 2H), 1.44-1.21 (m, 8H), 0.94-0.85 (m, 6H). The nuclear magnetic carbon spectrum of the product of step (3) is: 13 C-NMR (175MHz, CDCl3) δ (ppm) = 175.4, 65.3, 64.2, 43.1, 34.4, 31.6, 29.2, 25.2, 22.7, 22.5, 14.2, 7.5.

[0087] (4) The product of step (3) (160.17 g, 0.65 mol) was dissolved in 400 mL of dichloromethane, and DMAP (15.88 g, 0.13 mol), hexanoic acid (90.52 g, 0.78 mol) and pentanoic acid (79.67 g, 0.78 mol) were added, and then EDCI (300.17 g, 1.56 mol) was added to the system and stirred at room temperature for 12 hours. The crude product was washed with 1 M hydrochloric acid solution, washed twice with water, and the dichloromethane solvent was removed by rotary evaporation. The excess acid was removed by vacuum distillation. After vacuum distillation, the product was washed with 1% potassium hydroxide solution at 80° C., then washed twice with water, and dried to obtain 301 g of the final product, which was the trimethylolpropane ester composition 3 of the present invention. The mass spectrum data of the final product include: HRMS (FT-ICRMS) calculation for C 23 H 42 NaO6(M+Na):437.2874,found:437.2877;calcd for C 24 H 44 NaO6(M+Na):451.3030,found:451.3037; calcd for C 25 H 46 NaO6(M+Na):465.3187,found:465.3192.

[0088] After structural identification, the final product synthesized is indeed a composition of the target compound trimethylolpropane ester (structural formulas are I-d1, I-d2 and I-d3).

[0089] The synthetic reaction formula of Example 3 is shown below.

[0090]

[0091] The physical properties of the final products in Examples 1 to 3 and commercially available trimethylolpropane n-heptanoate (as Comparative Example 1) were evaluated by the methods of kinematic viscosity determination and dynamic viscosity calculation of petroleum products (GB / T 265), pour point determination of petroleum products (GB / T 3535) and lubricating oil evaporation loss determination-Noack method (NB / SH / T 0059-2010), and the evaluation results are shown in Table 1. The corresponding physical properties of trimethylolpropane n-nonanoate in the document "Synthetic Lubricants" (China Petrochemical Press, published in June 1996) are listed in Table 1 as Comparative Example 2 for comparison.

[0092] Table 1

[0093]

[0094] Example 4 Preparation of complex lithium-based grease

[0095] Raw material components: PAO4 365g (100℃ viscosity is 3.9mm 2 / s), trimethylolpropane ester composition 1415g (100℃ viscosity 3.52mm 2 / s), 24.77g lithium hydroxide monohydrate, 89.55g dodecyl hydroxystearic acid, 27.40g azelaic acid, 26.62g dialkyl dithiocarbamate, 1.35g benzotriazole fatty octadecylamine salt, and 10.73g N-phenyl-α-naphthylamine.

[0096] The preparation method is as follows: first, 365 grams of PAO4 base oil, 89.55 grams of 12-hydroxystearic acid and 27.40 grams of azelaic acid are added to a fat-making kettle, stirred evenly, heated to 90°C, and a lithium hydroxide aqueous solution (containing 24.77 grams of lithium hydroxide monohydrate and 202 grams of water) is added to carry out a saponification reaction for 120 minutes, 205 grams of trimethylolpropane ester composition 1 is added, and the temperature is raised to 210°C for high-temperature refining for 5 minutes; 210 grams of trimethylolpropane ester composition 1 is added, the temperature is lowered to 110°C, 26.62 grams of dialkyl dithiocarbamate, 1.35 grams of benzotriazole fatty octadecylamine salt, and 10.73 grams of N-phenyl-α-naphthylamine are added, stirred evenly, and ground three times by a three-roll mill to form fat.

[0097] Example 5 Preparation of complex lithium-based grease

[0098] Raw material components: PAO6 435g (viscosity 5.8mm at 100℃) 2 / s), trimethylolpropane ester composition 1530g (100℃ viscosity 3.52mm 2 / s), 35.47g lithium hydroxide monohydrate, 132g dodecyl hydroxystearic acid, 40g sebacic acid, 26.9g dialkyl dithiocarbamate, 1.17g benzotriazole fatty octadecylamine salt, and 10.24g N-phenyl-α-naphthylamine.

[0099] The preparation method is as follows: first, 435 grams of PAO6 base oil, 132 grams of 12-hydroxystearic acid and 40 grams of sebacic acid are added to a fat-making kettle, stirred evenly, heated to 90°C, added with a lithium hydroxide aqueous solution (containing 35.47 grams of lithium hydroxide monohydrate and 280 grams of water) for saponification reaction for 120 minutes, added with 230 grams of trimethylolpropane ester composition 1, heated to 210°C for high-temperature refining for 5 minutes; added with 300 grams of trimethylolpropane ester composition 1, cooled to 110°C, added with 26.9 grams of dialkyl dithiocarbamate, 1.17 grams of benzotriazole fatty octadecylamine salt, and 10.24 grams of N-phenyl-α-naphthylamine, stirred evenly, and ground by a three-roll mill for 3 times to form fat.

[0100] Example 6 Preparation of complex lithium-based grease

[0101] Raw material components: PAO10 355g (viscosity 10mm at 100℃) 2 / s), trimethylolpropane ester composition 2420g (100℃ viscosity 3.52mm 2 / s), lithium hydroxide monohydrate 24.76g, dodecanedioic acid 90.01g, azelaic acid 27.35g, dialkyl dithiocarbamate 16.0g, benzotriazole fatty octadecylamine salt 0.96g, N-phenyl-α-naphthylamine 8.21g.

[0102] The preparation method is as follows: first, 355 grams of PAO10 base oil, 90.01 grams of 12-hydroxystearic acid and 27.35 grams of azelaic acid are added to a fat-making kettle, stirred evenly, heated to 90°C, added with a lithium hydroxide aqueous solution (containing 24.76 grams of lithium hydroxide monohydrate and 220 grams of water) for saponification reaction for 120 minutes, added with 210 grams of trimethylolpropane ester composition 2, heated to 210°C for high-temperature refining for 5 minutes; added with 210 grams of trimethylolpropane ester composition 2, cooled to 110°C, added with 16.0 grams of dialkyl dithiocarbamate, 0.96 grams of benzotriazole fatty octadecylamine salt, and 8.21 grams of N-phenyl-α-naphthylamine, stirred evenly, and ground by a three-roll mill for 3 times to form fat.

[0103] Example 7 Preparation of complex lithium-based grease

[0104] Raw material components: 500N 335g (viscosity 11mm at 100℃ 2 / s); trimethylolpropane ester composition 3410g (100 ℃ viscosity 3.52mm 2 / s), lithium hydroxide monohydrate 21.75g, dodecanedioic acid 79.30g, sebacic acid 25.51g, dialkyl dithiocarbamate 18.91g, benzotriazole fatty octadecylamine salt 0.87g, N-phenyl-α-naphthylamine 7.83g.

[0105] The preparation method is as follows: first, 335 g of 500N base oil, 79.30 g of 12-hydroxystearic acid and 25.51 g of sebacic acid are added to a fat-making kettle, stirred evenly, heated to 90°C, and a lithium hydroxide aqueous solution (containing 21.75 g of lithium hydroxide monohydrate and 170 g of water) is added to carry out a saponification reaction for 120 min, 200 g of trimethylolpropane ester composition 3 is added, and the temperature is raised to 210°C for high-temperature refining for 5 min; 210 g of trimethylolpropane ester composition is added, the temperature is lowered to 110°C, 18.91 g of dialkyl dithiocarbamate, 0.87 g of benzotriazole fatty octadecylamine salt, and 7.83 g of N-phenyl-α-naphthylamine are added, stirred evenly, and ground three times by a three-roll mill to form fat.

[0106] Comparative Example 3 Preparation of complex lithium-based grease

[0107] Raw material components: PAO6 965g (viscosity 5.8mm at 100℃) 2 / s), 35.47g lithium hydroxide monohydrate, 132g dodecyl hydroxystearic acid, 40g sebacic acid, 26.9g dialkyl dithiocarbamate, 1.17g benzotriazole fatty octadecylamine salt, and 10.24g N-phenyl-α-naphthylamine.

[0108] The preparation method is as follows: first, add 435 grams of PAO6 base oil, 132 grams of 12-hydroxystearic acid and 40 grams of sebacic acid into a fat-making kettle, stir evenly, heat to 90°C, add lithium hydroxide aqueous solution (containing 35.47 grams of lithium hydroxide monohydrate and 280 grams of water) to carry out saponification reaction for 120 minutes, add 230 grams of PAO6 base oil, heat to 210°C for high-temperature refining for 5 minutes; add 300 grams of PAO6 base oil, cool to 110°C, add 26.9 grams of dialkyl dithiocarbamate, 1.17 grams of benzotriazole fatty octadecylamine salt, 10.24g N-phenyl-α-naphthylamine, stir evenly, and grind three times through a three-roll mill to form fat.

[0109] The performance of the lithium-based composite greases of Examples 4 to 7 and Comparative Example 3 was evaluated. The evaluation methods and results are shown in Table 2.

[0110] Table 2 Performance evaluation of grease

[0111]

Claims

1. Lithium-based composite grease, based on the total weight of the grease, includes 65% to 95% of lubricating base oil, 3% to 30% of a composite lithium-based thickener, and 1% to 10% of an additive; wherein the lubricating base oil comprises a base oil (I) and a base oil (II), and the base oil (I) is a trimethylolpropane ester composition; and the trimethylolpropane ester composition comprises the following components: (a) (b) (c) Where R 1 , R 2 , R 3 The groups are each selected from C4 to C9 straight or branched alkyl groups, and R 1 , R 2 , R 3 The carbon numbers in the groups are different from each other; the molar ratio between the components (a), (b) and (c) is 1:(1.7-2.3):(0.7-1.3); the base oil (II) is selected from one or more of synthetic oil, mineral oil and vegetable oil.

2. The lithium complex grease according to claim 1, characterized in that: R 1 , R 2 , R 3 The groups are C4 straight chain or branched chain alkyl, C5 straight chain or branched chain alkyl, C6 straight chain or branched chain alkyl, C7 straight chain or branched chain alkyl, C8 straight chain or branched chain alkyl, and C9 straight chain or branched chain alkyl groups with different carbon numbers.

3. The lithium complex grease according to claim 1, characterized in that: R 1 The group is selected from n-heptyl, R 2 , R 3 The groups are each selected from n-pentyl and n-hexyl groups; or, R 1 The group is selected from n-hexyl, R 2 , R 3 The groups are each selected from n-pentyl and n-heptyl; or, R 1 The group is selected from n-heptyl, R 2 , R 3 The groups are each selected from n-octyl and n-nonyl groups; or, R 1 The group is selected from n-hexyl, R 2 , R 3 The groups are each selected from n-butyl and n-pentyl groups.

4. The lithium complex grease according to claim 1, characterized in that: The preparation method of the trimethylolpropane ester composition comprises the following steps: (1) allowing trimethylolpropane to undergo an alcohol hydroxyl group protecting reaction with an alcohol hydroxyl group protecting agent to obtain a monohydroxyl product; (2) the monohydroxy product obtained in step (1) is reacted with R 1 COX undergoes an acylation reaction to obtain an acylated product; (3) subjecting the acylated product obtained in step (2) to a deprotection reaction of the alcoholic hydroxyl group to obtain a dihydroxy product; (4) making the dihydroxy product obtained in step (3) and R 2 COX', R 3 COX' undergoes acylation reaction and collects the product; Among them, R 1 , R 2 , R 3 The groups are each selected from C4 to C9 straight or branched alkyl groups, and R 1 , R 2 , R 3 The carbon numbers in the groups are different from each other; the X group is selected from F, Cl, Br, I, OH; the X' groups are each independently selected from F, Cl, Br, I, OH; the R 1 COX, R 2 COX', R 3 The molar ratio between COX' is 1:(0.9~1.2):(0.9~1.2).

5. The lithium complex grease according to claim 4, characterized in that: In step (1), the molar ratio of trimethylolpropane to the alcoholic hydroxyl protecting agent is 1:2-200; the temperature of the alcoholic hydroxyl protecting reaction is -20-80°C; and the time of the alcoholic hydroxyl protecting reaction is 1-120 hours.

6. The lithium complex grease according to claim 5, characterized in that: The alcohol hydroxyl protecting agent is selected from one or more of acetone, 2,2-dimethoxypropane and 2-methoxypropylene.

7. The lithium complex grease according to claim 4, characterized in that: In step (2), the monohydroxy product obtained in step (1) is reacted with R 1 The molar ratio of COX is 1:0.5-2; the reaction temperature is 0-80°C, and the reaction time is 1-48 hours; a second solvent and / or an alkaline catalyst is added to the reaction in step (2), the second solvent is one or more of tetrahydrofuran, dichloromethane, chloroform, acetone, ethyl acetate and acetonitrile, and the alkaline catalyst is one or more of triethylamine, tert-butylamine, pyridine, diisopropylethylamine and hexamethyldisilazane.

8. The lithium complex grease according to claim 4, characterized in that: In step (3), the acylated product obtained in step (2) is subjected to a deprotection reaction of the alcoholic hydroxyl group with a C1-C5 alcohol or an acid solution.

9. The lithium complex grease according to claim 4, characterized in that: In step (4), the dihydroxy product obtained in step (3) is reacted with R 2 COX', R 3 The molar ratio of COX' is 1:0.8-1.5:0.8-1.5; the reaction temperature is 0-80°C, and the reaction time is 1-48 hours.

10. The lithium complex grease according to any one of claims 1 to 9, characterized in that: The synthetic oil is selected from one or more of poly-α-olefin oil, ester oil, fluorine oil and silicone oil; the mineral oil is selected from one or more of paraffin base oil, intermediate base oil and cycloalkyl base oil; the vegetable oil is selected from one or more of castor oil, rapeseed oil, peanut oil and soybean oil.

11. The lithium complex grease according to any one of claims 1 to 9, characterized in that: The base oil (II) is selected from a base oil having a kinematic viscosity of 2 to 60 mm at 100°C. 2 / s lubricating base oil.

12. The lithium complex grease according to any one of claims 1 to 9, characterized in that: The composite lithium-based thickener is obtained by saponification reaction between an acid and lithium hydroxide, wherein the acid is a mixed acid of a fatty acid and an auxiliary acid, and the fatty acid is selected from C 12 ~C 20 Fatty acids and / or C 12 ~C 20 the auxiliary acid is selected from one or more of acetic acid, propionic acid, butyric acid, valeric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, terephthalic acid, phosphoric acid and boric acid.

13. The lithium complex grease according to any one of claims 1 to 9, characterized in that: The additives include oiliness agent, extreme pressure anti-wear agent and antioxidant.

14. The lithium complex grease according to claim 13, characterized in that: The oiliness agent is selected from benzotriazole fatty amine and sulfurized olefin cottonseed oil; the extreme pressure anti-wear agent is selected from one or more of aminothioester, sulfurized isobutylene, di-n-butyl phosphite, tricresyl phosphate, triphenyl thiophosphate, and dialkyl dithiocarbamate; the antioxidant is selected from one or more of 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, dialkyl diphenylamine, N-phenyl-α-naphthylamine and 3,5-di-tert-butyl-4-hydroxyphenyl methyl acrylate.

15. The method for preparing the complex lithium-based grease according to any one of claims 1 to 14, comprising: The composite lithium-based thickener and part of the lubricating base oil are refined at a constant temperature of 180-230° C., cooled, and the additive and the remaining lubricating base oil are added to grind into grease.

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