Composite polyurea sulfonate lubricating grease and preparation method thereof

Abstract

The invention relates to the technical field of lubricating grease, discloses composite polyurea sulfonate lubricating grease and provides a preparation method thereof. The lubricating grease comprises the following components in percentage by mass: 75-85% of base oil, 15-20% of a thickening agent and 0-5% of an additive, the thickening agent is polyurea sulfonate. According to the invention, sulfonate is introduced into polyurea thickening agent molecules, so that the lubricating grease also has good extreme pressure antiwear property, mechanical stability, colloidal stability and other properties under the condition of ensuring high dropping point and thermal stability of the lubricating grease; the preparation method of the lubricating grease is simple in process, production conditions are easy to control, and the obtained product is stable in quality.

Description

Technical Field

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

[0002] Grease as a bearing lubricant has the advantages of simplifying bearing devices and miniaturizing mechanical devices. About 80% of rolling bearings are lubricated with grease. The use conditions of modern precision bearings are becoming more and more demanding, and the requirements for grease are also getting higher and higher, mainly reflected in long life, adaptability to high / low temperature, high / low speed use, low noise, etc. In recent years, with the increasing application of precision rolling bearings, bearing vibration and noise have attracted more and more attention, especially in some new military equipment and concentrated bearings and micro bearings of civilian precision machinery, such as disk storage drives, linear or rotary read-write heads and printer drives, audio-visual equipment, textile machinery, precision instruments, small motors, air conditioners, washing machines, military electronics, precision instruments, etc. Bearing grease requires the use of low-noise grease, which puts very high requirements on bearing noise. At the same time, with the rapid development of bearing materials and production and processing technology, the noise generated by the bearing itself has been greatly reduced, making lubricants the main factor affecting bearing noise.

[0003] Common low-noise grease products at home and abroad are mostly lithium-based grease and urea-based grease. Common lithium-based grease on the market has a good noise reduction effect at the beginning, but the noise becomes louder after running for a period of time. Urea-based grease was often used as high-temperature grease in the past. In recent years, grease with organic urea as a thickener has been developed, and it has been found that ultra-quiet grease can also be obtained. This urea-based grease is a diurea grease prepared by reacting alkenyl succinimide with isocyanate and adding alkylbenzene sulfonate metal salt or petroleum sulfonate metal salt detergent. This grease can maintain low noise even when used for a long time at high temperatures above 120°C. Urea-based grease prepared by combining aliphatic amines and cycloalkyl amines with isocyanates has excellent low-noise performance and can be used as a better high-temperature low-noise grease.

[0004] However, for some rolling bearings, which are used in low-speed and heavy-load conditions, such as metallurgy, wind power and other industries, the quality of quiet performance is no longer the main contradiction, and the extreme pressure and anti-wear properties of grease are the main factors to ensure the long-term operation of the bearing. The extreme pressure and anti-wear properties of grease are excellent, which can fully lubricate the bearing under load conditions, effectively prevent wear, abrasion and even sintering of the metal surface, thereby ensuring the normal operation of the bearing, improving mechanical efficiency and reducing energy consumption.

[0005] Polyurea grease has excellent high and low temperature performance and anti-oxidation performance, but its extreme pressure and anti-wear performance is relatively weak. At present, there is no polyurea bearing grease with good extreme pressure and anti-wear performance on the domestic market. Therefore, it is necessary to develop a domestic product for rolling / sliding bearing lubrication under heavy load conditions and master its core technology. Summary of the invention

[0006] The present invention aims at the deficiencies of the prior art and provides a composite polyurea sulfonate grease. The grease prepared by introducing sulfonate into polyurea molecules has good high and low temperature performance, oxidation resistance, and excellent shear stability and wear resistance. The application also provides a preparation method of the composite polyurea sulfonate grease. The preparation method has a simple process, easy-to-control production conditions, and stable product quality.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A composite polyurea sulfonate grease, wherein the components of the grease include the following components by mass percentage: Base oil 75-85% Thickener 15-20% Additives 0-5%; The thickener is polyurea sulfonate, and the structural formula is shown in I: (I), Among them, R 1 for , n=1-12, M is an alkali metal selected from Group I or an alkaline earth metal selected from Group II in the periodic table; R 2 is an alkylene group or an arylene group, the carbon number of the alkylene group is 2-12; R 3 is an arylene group, an alkylene group or a cycloalkylene group, and has a carbon number of 6 to 30; The additive is selected from one or more of a series of materials, which include but are not limited to extreme pressure anti-wear agents, antioxidants, and rust inhibitors.

[0008] Preferably, R 2 is an alkylene group or an arylene group, the carbon number of the alkylene group is 2-8, and the arylene group is a phenylene group or a biphenylene group; R 3 It is an arylene group, an alkylene group or a cycloalkylene group, and has 6 to 20 carbon atoms.

[0009] More preferably, R 3 It is toluene, methyl diphenyl, dicyclohexyltoluene, meta-xylylene or hexylene.

[0010] Preferably, the base oil is mineral oil, synthetic oil, vegetable oil or a mixture thereof, and has a kinematic viscosity of 2-20 mm at 100°C. 2 / s, 40℃ kinematic viscosity is 80-140mm 2 / s.

[0011] Preferably, the base oil is synthetic oil with a kinematic viscosity of 8-12 mm at 100°C. 2 / s, 40℃ kinematic viscosity is 90-100mm 2 / s, synthetic oils include but are not limited to PAO, mPAO, ester oil, alkyl silicone oil, and Fischer-Tropsch synthetic oil.

[0012] Preferably, the base oil is an ester oil, and the ester oil is at least one of diisooctyl sebacate, diisodecyl adipate, trimethylolpropane octyl decanoate, adipic acid ester, polyol ester, phthalate and trimellitate.

[0013] More preferably, the base oil is a mixture of trimellitic acid ester and diisooctyl sebacate.

[0014] Preferably, the addition amount of the extreme pressure anti-wear agent is 0-3.5%, and the extreme pressure anti-wear agent is selected from one or more of sulfur extreme pressure anti-wear agents, phosphorus extreme pressure anti-wear agents and sulfur-phosphorus extreme pressure anti-wear agents. Specifically, the sulfur extreme pressure agent can be sulfurized oils and fats, thiofatty acids, thioesters, thioolefins, dialkyl polysulfides, thiadiazole compounds, alkylthiocarbamoyl compounds, thiocarbamate compounds, etc.; the phosphorus extreme pressure agent can be phosphates, phosphites, acidic phosphates, acidic phosphites and their amine salts, etc.; the sulfur-phosphorus extreme pressure agent can be zinc dialkylthiocarbamate (Zn-DTC), molybdenum dialkylthiocarbamate (Mo-DTC), zinc dialkyl dithiophosphate (Zn-DTP), molybdenum dialkyl dithiophosphate (Mo-DTP), etc.

[0015] Preferably, the antioxidant is added in an amount of 0.1-0.5%, and the antioxidant is selected from any one or two of phenolic antioxidants, amine antioxidants and molybdenum antioxidants. Specifically, the phenolic antioxidant may be a monophenolic antioxidant, a diphenolic antioxidant, a hindered phenolic antioxidant, etc.; the amine antioxidant may be diphenylamine, alkyl diphenylamine, phenyl-α-naphthylamine, etc.; the molybdenum antioxidant may be a molybdenum amine complex formed by the reaction of molybdenum trioxide and / or molybdic acid with an amine compound, etc.

[0016] Preferably, the amount of the rust inhibitor added is 0.05-1.5%, and the rust inhibitor is selected from any one or more combinations of benzotriazole, alkyltriazole, benzothiazole, benzimidazole, thiadiazole and their corresponding derivatives.

[0017] Furthermore, the present invention also provides a method for preparing the composite polyurea sulfonate grease, comprising the following steps: S1. Take 1 / 3-1 / 2 of the base oil, add aminosulfonate and organic diamine, and stir to dissolve at 30-40℃; S2, add diisocyanate, heat to 50-60°C and stir thoroughly, then heat to 170-180°C at a rate of 30°C / min, react at 170-180°C for 1-2h, and cool; S3, add the remaining base oil and additives, stir and grind to obtain the finished product.

[0018] Preferably, the structural formula of the aminosulfonate is , wherein n=1-12, and M is selected from the alkaline metals of Group I in the periodic table, such as lithium, potassium, sodium, rubidium and cesium, or the alkaline earth metals of Group II, such as beryllium, magnesium, calcium, strontium and barium. More preferably, the aminosulfonate is at least one of sodium 2-cyclohexylaminoethanesulfonate, sodium 3-cyclohexylaminopropanesulfonate and sodium cyclohexylaminobutanesulfonate.

[0019] Preferably, the diisocyanate structural formula is OCN—R 3 —NCO. Among them, R 3 is an arylene group, an alkylene group or a cycloalkylene group, and the carbon number may be 6-30; preferably, R 3 The carbon number may be 6-20. More preferably, R 3 The diisocyanate is toluene, methyl diphenyl, dicyclohexyltoluene, meta-xylylene or hexylene. More preferably, the diisocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, 1,6-hexylene diisocyanate, dicyclohexylmethyl diisocyanate and meta-xylylene diisocyanate.

[0020] Preferably, the structural formula of the organic diamine is NH 2 —R 2 —NH 2 Among them, R 2 is an arylene group or an alkylene group having 2 to 12 carbon atoms; preferably, R 2 is phenylene or biphenylene or alkylene with carbon number of 2 to 8. More preferably, the organic diamine is aromatic amine such as p-phenylenediamine, o-phenylenediamine, 4,4'-biphenylenediamine and / or linear aliphatic amine such as ethylenediamine, propylenediamine and 1,6-hexanediamine.

[0021] The beneficial effects of the present invention are as follows: the present invention provides a composite polyurea sulfonate grease. Compared with the prior art, the present invention introduces sulfonate into the polyurea thickener molecule, thereby ensuring the high dropping point and thermal stability of the grease while also having good extreme pressure anti-wear properties, mechanical stability and colloidal stability; and the preparation method of the grease is simple in process, the production conditions are easy to control, and the obtained product quality is stable. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The raw material components used in the examples and comparative examples of this application are shown in Table 1 below.

[0024] Table 1 Components Name / Model CAS source Base oil Trioctyl trimellitate 3319-31-1 Maclean Base oil Di(2-ethylhexyl)sebacate 122-62-3 Maclean Thickener raw materials Methylene diphenyl diisocyanate (MDI) 101-68-8 Maclean Thickener raw materials Ethylenediamine 107-15-3 Maclean Thickener raw materials Octadecylamine 124-30-1 Maclean Thickener raw materials Sodium 2-cyclohexylaminoethanesulfonate 3076-05-9 Hubei Wei's Chemical Thickener raw materials Sodium 3-cyclohexylaminopropanesulfonate 105140-23-6 Hubei Wei's Chemical Thickener raw materials Sodium Cyclamate 161308-34-5 Hubei Wei's Chemical Extreme pressure anti-wear agent T309 / Jinzhou Kangtai Antioxidants T534 / Jinzhou Shengda University Rust inhibitor T705 / Jinzhou Hongze The relevant properties of the base oil in each embodiment and comparative example of the present application are shown in Table 2 below.

[0025] Table 2 name type <![CDATA[Kinematic viscosity @ 100 °C / mm²·s -1 > <![CDATA[Kinematic viscosity @ 40 °C / mm²·s -1 > Viscosity Index Trioctyl trimellitate Ester oil 9.4 95.8 82 Di(2-ethylhexyl)sebacate Base oil, friction reducer 3.26 11.87 151.4 From the properties of the components in Table 2, it can be seen that the grease base oil of the present application is mainly composed of trioctyl trimellitate, and a small amount of diisooctyl sebacate with a high viscosity index is added for blending. Diisooctyl sebacate also plays a friction reducing role. The kinematic viscosity of the obtained base oil at 100°C is 8-12 mm 2 / s, 40℃ kinematic viscosity is 90-100mm 2 / s. Example

[0026] The formulas of the composite polyurea sulfonate greases provided in Examples 1-9 are shown in Table 3.

[0027] Table 3 Component dosage / g Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 4 Trioctyl trimellitate 80 77.2 75.5 79.7 78 80.4 80.3 79.3 72.3 Di(2-ethylhexyl)sebacate 2 1.8 1.5 2 2 2 2 2 2 MDI 7.1 8.5 9.5 7.1 7.1 7.1 7.1 7.1 7.1 Ethylenediamine 0.9 1.1 1.2 0.9 0.9 0.9 0.9 0.9 0.9 Sodium 3-cyclohexylaminopropanesulfonate 7.0 8.4 9.3 7.0 7.0 0 0 0 7.0 Sodium 2-cyclohexylaminoethanesulfonate 0 0 0 0 0 6.6 0 0 0 Sodium Cyclamate 0 0 0 0 0 0 6.7 0 0 Octadecylamine 0 0 0 0 0 0 0 7.7 7.7 Sodium N-methyl-4-aminobutyrate 0 0 0 0 0 0 0 0 0 T309 0 0 0 0.3 2 0 0 0 0 T534 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 T705 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Among them, the base oil in Examples 1-7 is a combination of trioctyl trimellitate and diisooctyl sebacate, the diisocyanate is MDI, the organic diamine is ethylenediamine, the extreme pressure anti-wear agent is T309, the antioxidant is T534, and the rust inhibitor is T705; in Examples 1-5, the aminosulfonate is sodium 3-cyclohexylaminopropanesulfonate, in Example 6, the aminosulfonate is sodium 2-cyclohexylaminoethanesulfonate, and in Example 7, the aminosulfonate is sodium cyclohexylaminobutanesulfonate.

[0028] Preparation method of the composite polyurea sulfonate grease of Examples 1-7: S1: Trioctyl trimellitate and diisooctyl sebacate are mixed evenly to obtain a base oil, 1 / 3 of the base oil is added with aminosulfonate and ethylenediamine, and stirred to dissolve at 35°C; S2: Add MDI, heat to 50°C and stir thoroughly, then heat to 170°C at a rate of 30°C / min, keep the temperature constant, react for 1.5h, and cool to 110°C; S3: Add all the remaining base oil, extreme pressure anti-wear agent, antioxidant and rust inhibitor, stir evenly, transfer the material to a three-roll mill and grind it three times to obtain the finished product.

[0029] Comparative Example Comparative Example 1 A lubricating grease, which is different from Example 1 in that octadecylamine is used instead of sodium 3-cyclohexylaminopropanesulfonate. The lubricating grease formula is shown in Table 3.

[0030] Comparative Example 2 A lubricating grease, the formula of which is: 80 g of trioctyl trimellitate, 2 g of diisooctyl sebacate, 7.1 g of MDI, 0.9 g of ethylenediamine, 6.3 g of 3-cyclohexylaminopropanesulfonic acid, 1.2 g of sodium hydroxide, 1.5 g of T534, and 1.5 g of T705.

[0031] The preparation steps are: S1: Trioctyl trimellitate and diisooctyl sebacate are mixed evenly to obtain a base oil, 1 / 3 of the base oil is added with 3-cyclohexylaminopropanesulfonic acid and ethylenediamine, and stirred to dissolve at 35°C; S2: Add MDI, heat to 50°C and stir thoroughly, then heat to 170°C at a rate of 30°C / min, keep the temperature constant, react for 1.5h, and cool to 80°C; S3: Add sodium hydroxide and stir evenly, continue to heat to 170°C, and react for 0.5h; S3: Add all the remaining base oil, extreme pressure anti-wear agent, antioxidant and rust inhibitor, stir evenly, transfer the material to a three-roll mill and grind it three times to obtain the finished product.

[0032] Comparative Example 3 A lubricating grease, the formula of which is the same as that of Example 1, and the preparation steps are as follows: S1: Trioctyl trimellitate and diisooctyl sebacate are mixed evenly to obtain a base oil, 1 / 3 of the base oil is added with aminosulfonate and ethylenediamine, and stirred to dissolve at 35°C; S2: Add MDI, heat to 50°C and stir thoroughly, react for 40 minutes, heat to 170°C and react for 1.5 hours, and cool to 110°C; S3, add all the remaining base oil, extreme pressure anti-wear agent, antioxidant and rust inhibitor, stir evenly and then transfer the material to a three-roll mill and grind it three times to obtain the finished product.

[0033] Comparative Example 4 A lubricating grease, the formula of which is shown in Table 3, and the preparation steps are: S1: Evenly mix trioctyl trimellitate and diisooctyl sebacate to obtain a base oil; S2: Take 1 / 3 of the base oil, add octadecylamine and ethylenediamine, stir and dissolve at 35°C, add MDI, heat to 50°C and stir well, then heat to 170°C at a rate of 30°C / min, keep the temperature constant, react for 1.5h, and obtain polytetraurea grease; S3: Take 1 / 3 of the base oil, add aminosulfonate, heat to 95°C, keep warm and stir for 30 minutes to obtain aminosulfonate grease; S4: Mix the polytetraurea grease and aminosulfonate grease, cool to 110°C, add all the remaining base oil, extreme pressure anti-wear agent, antioxidant and rust inhibitor, stir evenly, transfer the material to a three-roll mill and grind it three times to obtain the finished product.

[0034] Performance testing The performance tests were carried out on the greases prepared in Examples 1-7 and Comparative Examples 1-4, and the test results are shown in Table 4.

[0035] Dropping point: GB / T 4929-1985 "Determination of dropping point of grease" is used to determine the dropping point of grease.

[0036] Mechanical shear stability: GB / T 269-1991 "Determination of cone penetration of greases and petroleum greases" was used to measure the unworked cone penetration, 60-times worked cone penetration and 100,000-times worked cone penetration of the grease at 25°C. The difference in cone penetration was obtained by subtracting the 60-times worked cone penetration from the 100,000-times worked cone penetration.

[0037] Anti-friction performance: The average wear spot diameter of the grease sample was measured using ASTM D2266 "Standard Test Method for Anti-wear Properties of Grease (Four-ball Machine Method)"; the four-ball test conditions were: load: 392 N (40 kgf); spindle speed: 1200 r / min; test time: 60 min; test temperature: 75°C. After the test, the wear spot diameter of the lower steel ball was measured, where the smaller the wear spot diameter, the better the anti-wear performance of the sample. The average of the wear spot diameters of the three lower steel balls was taken to evaluate the anti-wear performance of the grease sample.

[0038] Colloid stability: NB / SH / T 0324-2010 "Determination of steel mesh oil separation of grease - cone mesh method" was used to test the steel mesh oil separation percentage (w / w, %) of the grease. The test conditions were: 100°C, 30 h.

[0039] Copper sheet corrosion: GB 7326-1987 "Lubricating grease copper sheet corrosion test method" is used to measure the corrosion of grease to copper sheets.

[0040] Table 4 Test items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Appearance Light yellow Light yellow Light yellow Light yellow Light yellow Light yellow Light yellow Light yellow Light yellow Light yellow Light yellow Dropping point / ℃ 315 302 300 298 298 300 299 298 305 296 300 Unworked cone penetration / 0.1mm 235 238 242 250 255 239 240 255 245 245 246 60 times shear penetration / 0.1mm 245 250 250 265 268 248 252 270 251 258 262 100,000 times shear cone penetration / 0.1mm 270 278 280 300 313 275 281 330 283 306 315 Cone penetration difference 25 28 30 35 45 27 29 60 32 48 53 Four-ball wear spot diameter / mm 0.365 0.375 0.381 0.360 0.358 0.368 0.372 0.680 0.455 0.397 0.519 Steel mesh oil separation rate / % 0.14 0.17 0.20 0.28 0.35 0.17 0.22 1.2 0.37 0.40 0.66 Copper corrosion / grade 1b 1b 1b 1b 1b 1b 1b 1b 1b 1b 1b It can be seen from the test results of Examples 1-7 in Table 4 that the composite polyurea sulfonate grease prepared in the present application has high high temperature performance, excellent mechanical shear stability and colloidal stability, and still has good anti-wear performance without adding extreme pressure anti-wear agents, greatly broadening the market application field of polyurea-based grease.

[0041] Comparing the test results of Examples 1, 4, and 5, Example 4 adds an extreme pressure anti-wear agent compared to Example 1. It can be seen that the addition of the extreme pressure anti-wear agent has a certain improvement in the anti-wear performance of the grease of the present application, but the improvement is limited, and the addition of the extreme pressure anti-wear agent will instead cause the difference in the cone penetration of the grease of the present application to become larger and the steel mesh oil separation rate to become higher, that is, the mechanical shear stability and colloid stability of the grease are reduced to a certain extent. Example 5 increases the amount of the extreme pressure anti-wear agent compared to Example 4. It can be seen that with the increase in the amount of the extreme pressure anti-wear agent, the anti-wear performance of the grease of the present application has not been improved, and the values ​​of the 100,000 cone penetrations and the steel mesh oil separation rate have increased significantly, indicating that the increase in the amount of the extreme pressure anti-wear agent has a significant negative impact on the mechanical shear stability and colloid stability of the grease of the present application.

[0042] The test results of Example 1 and Comparative Example 1 are compared. Comparative Example 1 is a polytetraurea grease. Compared with Example 1, sodium sulfonate salt is not used for compounding. It can be seen that the mechanical shear stability and colloid stability are worse than those of Example 1. Without adding extreme pressure anti-wear agent, the test result of the four-ball wear spot diameter is 0.680 mm, which is much higher than 0.365 mm of Example 1.

[0043] The test results of Example 1 and Comparative Example 2 were compared. Compared with Example 1, the preparation steps of Comparative Example 2 were changed. Aminosulfonic acid was first reacted with diisocyanate, and then sodium hydroxide was added to react to obtain a composite polyurea sodium sulfonate-based grease. The preparation steps were relatively more complicated. Judging from the test results of the grease performance, the colloid stability and wear resistance were also reduced.

[0044] The test results of Example 1 and Comparative Example 3 are compared. Compared with Example 1, the preparation steps of Comparative Example 3 are changed. In Comparative Example 3, after the thickener raw materials are mixed and heated for reaction, the temperature is directly raised to 170°C before grease refining. It can be seen from the test results that the grease prepared by this method has various properties that have declined, especially the mechanical shear stability and colloid stability have the largest decline.

[0045] The test results of Example 1 and Comparative Example 4 are compared. Compared with Example 1, no sulfonate is introduced into the thickener of Comparative Example 4, and only sodium 3-cyclohexylaminopropanesulfonate is added for physical mixing. It can be seen from the test results that the performance of the grease prepared by this method is greatly reduced.

[0046] The above is a description of the embodiments of the present invention. Through the above description of the disclosed embodiments, professionals and technicians in the field can implement or use the present invention. Various modifications to these embodiments will be apparent to professionals and technicians in the field. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this article, but will conform to the widest range consistent with the principles and novelties disclosed herein.

Claims

1. A composite polyurea sulfonate grease, characterized in that: The components of the lubricating grease include the following components by mass percentage: Base oil 75-85% Thickener 15-20% Additives 0-5%; The thickener is polyurea sulfonate, and the structural formula is shown in I: （I）， Among them, R1 is , n=1-12, M is an alkali metal selected from Group I or an alkaline earth metal selected from Group II in the periodic table; R2 is an alkylene group or an arylene group, the carbon number of the alkylene group is 2-12; R3 is an arylene group, an alkylene group or a cycloalkylene group, the carbon number is 6-30; The additive is selected from one or more of a series of materials, which include but are not limited to extreme pressure anti-wear agents, antioxidants, and rust inhibitors.

2. The composite polyurea sulfonate grease according to claim 1, characterized in that: R2 is an alkylene group or an arylene group, the carbon number of the alkylene group is 2-8, and the arylene group is a phenylene group or a biphenylene group; R3 is an arylene group, an alkylene group or a cycloalkylene group, and the carbon number is 6-20. Preferably, R3 is toluene, methyl diphenyl, dicyclohexyltoluene, meta-xylene or hexylene.

3. The composite polyurea sulfonate grease according to claim 1, characterized in that: The base oil is mineral oil, synthetic oil, vegetable oil or a mixture thereof, and has a kinematic viscosity of 2-20 mm at 100°C. 2 / s, 40℃ kinematic viscosity is 80-140mm 2 / s; Preferably, the base oil is a synthetic oil with a kinematic viscosity of 8-12 mm at 100 °C. 2 / s, 40℃ kinematic viscosity is 90-100mm 2 / s, synthetic oil includes but is not limited to PAO, mPAO, ester oil, alkyl silicone oil, Fischer-Tropsch synthetic oil; more preferably, the base oil is ester oil, and the ester oil is at least one of diisooctyl sebacate, diisodecyl adipate, trimethylolpropane octyl decanoate, adipic acid ester, polyol ester, phthalate and trimellitic acid ester; more preferably, the base oil is a mixture of trimellitic acid ester and diisooctyl sebacate.

4. The composite polyurea sulfonate grease according to claim 1, characterized in that: The addition amount of the extreme pressure anti-wear agent is 0-3.5%, and the extreme pressure anti-wear agent is selected from one or more of sulfur-based extreme pressure anti-wear agents, phosphorus-based extreme pressure anti-wear agents and sulfur-phosphorus-based extreme pressure anti-wear agents.

5. The composite polyurea sulfonate grease according to claim 1, characterized in that: The added amount of the antioxidant is 0.1-0.5%, and the antioxidant is selected from any one or two of phenolic antioxidants, amine antioxidants and molybdenum antioxidants.

6. The composite polyurea sulfonate grease according to claim 1, characterized in that: The addition amount of the rust inhibitor is 0.05-1.5%, and the rust inhibitor is selected from any one or more combinations of benzotriazole, alkyltriazole, benzothiazole, benzimidazole, thiadiazole and their corresponding derivatives.

7. The method for preparing the composite polyurea sulfonate grease according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Take 1 / 3-1 / 2 of the base oil, add aminosulfonate and organic diamine, and stir to dissolve at 30-40℃; S2, add diisocyanate, heat to 50-60°C and stir thoroughly, then heat to 170-180°C at a rate of 30°C / min, react at 170-180°C for 1-2h, and cool; S3, add the remaining base oil and additives, stir and grind to obtain the finished product.

8. The preparation method according to claim 7, characterized in that: The structural formula of the aminosulfonate is , wherein n=1-12, M is selected from an alkali metal of Group I or an alkaline earth metal of Group II in the periodic table; Preferably, the aminosulfonate is at least one of sodium 2-cyclohexylaminoethanesulfonate, sodium 3-cyclohexylaminopropanesulfonate, and sodium cyclohexylaminobutanesulfonate.

9. The preparation method according to claim 7, characterized in that: The diisocyanate structural formula is OCN—R3—NCO; R3 is an arylene group, an alkylene group or a cycloalkylene group, and has a carbon number of 6-30; Preferably, R3 has a carbon number of 6-20; More preferably, R3 is toluene, methyl diphenyl, dicyclohexyltoluene, meta-xylylene or hexylene; More preferably, the diisocyanate is at least one of tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethyl diisocyanate, and meta-xylylene diisocyanate.

10. The preparation method according to claim 7, characterized in that: The structural formula of the organic diamine is NH2—R2—NH2; R2 is an arylene group or an alkylene group having 2 to 12 carbon atoms; Preferably, R2 is phenylene or biphenylene or an alkylene group having 2 to 8 carbon atoms; More preferably, the organic diamine is an aromatic amine such as p-phenylenediamine, o-phenylenediamine, or 4,4'-biphenylenediamine and / or a linear fatty amine such as ethylenediamine, propylenediamine, or 1,6-hexanediamine.

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