A kind of composite fatty amine polyurea grease and preparation method thereof

Abstract

The present invention discloses a composite fatty amine polyurea grease and a preparation method thereof, belonging to the field of lubricating grease technology. The grease comprises the following raw materials in parts by weight: 80-120 parts of mineral base oil, 5-10 parts of fatty amine, 2-6 parts of isocyanate, 4-12 parts of a synergistic antioxidant, 2-8 parts of water, 20-30 parts of quench oil, 3-6 parts of an extreme pressure anti-wear agent, and 4-8 parts of a rust inhibitor. The resulting grease has excellent performance, being a composite of short-chain and long-chain fatty amines. The short-chain fatty amine provides a high dropping point, while the long-chain fatty amine provides thickening capacity, achieving complementary advantages and improving the overall performance of the grease. The synergistic antioxidant significantly enhances the grease's oxidative stability and extreme pressure wear resistance, and also provides stable performance and resistance to shedding.

Description

Technical Field

[0001] The present invention belongs to the technical field of lubricating greases, and in particular relates to a composite fatty amine polyurea lubricating grease and a preparation method thereof. Background Art

[0002] Polyurea grease is a type of non-soap grease, and its production volume is increasing year by year. Compared with soap grease, polyurea grease has advantages such as high temperature resistance and oxidation resistance, but it also has disadvantages such as poor shear resistance and storage hardening. These disadvantages are mainly caused by organic amines. Therefore, compounding with organic fatty amines of different chain lengths can effectively complement these disadvantages and improve overall performance.

[0003] CN111718773A discloses a polyurea thickener, a grease prepared therefrom, and a method for preparing the grease. A mixture of 2-amino-6-methoxybenzothiazole and R-NH2, wherein R is an alkyl or cycloalkyl group with 8 to 22 carbon atoms, is compounded with aniline and alkylamine to prepare a polyurea grease with excellent performance.

[0004] CN116656411A discloses a method for preparing high-temperature polyurea grease, which uses diphenylmethane-4,4'-diisocyanate, toluene diisocyanate and hexamethylene diisocyanate as diisocyanates, octadecylamine, p-toluidine and cyclohexylamine as organic amines, and is compounded with fatty amines, aniline and alicyclic amines to prepare high-dropping-point polyurea grease.

[0005] CN104560265B discloses a polyurea grease and a preparation method thereof, wherein a base oil is thickened with graphene and a polyurea compound. The method is simple in process, environmentally friendly, and has stable quality, and uses an organic monoamine as a thickener component.

[0006] Combining the above inventions, the first method uses a combination of aniline and alkylamines to produce polyurea grease, which produces excellent products. However, aniline is expensive and generally toxic. The second method, which aims to produce high-temperature grease, combines aliphatic amines with aniline and alicyclic amines to produce polyurea grease, also suffers from high cost, high raw material toxicity, and poor shear resistance. Furthermore, the grease is prone to oxidation during operation, and traditional antioxidants can dissolve during use, resulting in reduced grease performance. Therefore, a polyurea grease with simple and stable processing and excellent and stable performance is urgently needed to fill this gap. Summary of the Invention

[0007] The purpose of the present invention is to overcome the defects of the prior art and provide a composite fatty amine polyurea grease and a preparation method thereof.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A method for preparing a composite fatty amine polyurea grease comprises the following steps:

[0010] A1. Mix mineral base oil, fatty amine, isocyanate and synergistic antioxidant in a reactor and react at 80-100°C for 1-2 hours. After the reaction is completed, maintain the temperature at 80-100°C.

[0011] A2. Add water to the reactor in step A1 to remove isocyanate and react at 80-100°C for 30 minutes;

[0012] A3. Heat the reactor of step A2 to 180-200°C, then add quenching oil. After 1-2 hours, cool to 80-100°C, add extreme pressure anti-wear agent and rust inhibitor, and stir evenly; cool to room temperature and grind homogenously 2-3 times to obtain composite fatty amine polyurea grease.

[0013] Furthermore, the raw materials are calculated in parts by weight as follows: 80-120 parts of mineral base oil, 5-10 parts of fatty amine, 2-6 parts of isocyanate, 4-12 parts of synergistic antioxidant, 2-8 parts of water, 20-30 parts of quench oil, 3-6 parts of extreme pressure anti-wear agent, and 4-8 parts of rust inhibitor.

[0014] Furthermore, the fatty amine is two or more of octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine and octadecylamine.

[0015] Furthermore, the extreme pressure anti-wear agent is one of sulfided fatty acid ester, sulfided lard and triethyl phosphate.

[0016] Furthermore, the rust inhibitor is one or both of sulfonate and benzotriazole.

[0017] The prepared composite fatty amine polyurea has excellent lubricating performance, and the use of composite fatty amine can improve the overall high-temperature and shear resistance of the grease.

[0018] Furthermore, the synergistic antioxidant is prepared by the following steps:

[0019] S1. In a three-necked flask equipped with a thermometer, an electromagnetic stirrer, and a spherical condenser, a drying tube is added to the outlet of the condenser, and the drying tube is connected to a tail gas absorption device to absorb the generated hydrogen chloride gas. After pentaerythritol and benzene are mixed, phosphorus trichloride is slowly added dropwise under stirring, and the temperature is controlled not to exceed 30° C. After the addition is complete, the temperature is raised to 72° C. and the reaction is refluxed for 3 hours. After the reaction is complete, the solvent benzene and excess phosphorus trichloride are distilled off to obtain dichloropentaerythritol phosphite; the ratio of pentaerythritol, benzene, and phosphorus trichloride is 13.6 g:100 mL:27.4 g;

[0020] Pentaerythritol reacts with phosphorus trichloride to obtain dichloropentaerythritol phosphite; the specific reaction is as follows:

[0021]

[0022] S2. In a three-necked flask equipped with a stirring device, dichloropentaerythritol phosphite, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, potassium carbonate (acid binding agent) and N,N-dimethylformamide (DMF) were mixed and stirred uniformly, the reaction temperature was controlled to 75° C., and the reaction was kept warm for 6 hours. After the reaction was completed, the mixture was filtered, and part of the solvent was removed by rotary evaporation. The mixture was then purified by column chromatography (eluent was a mixed solvent of benzene / ethyl acetate in a volume ratio of 4:3), and the eluent was removed by rotary evaporation to obtain intermediate 1; the ratio of dichloropentaerythritol phosphite, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, potassium carbonate, and N,N-dimethylformamide was 28.7 g:23.6 g:15 mL:100 mL;

[0023] Under the catalysis of potassium carbonate, dichloropentaerythritol phosphite and 3,5-di-tert-butyl-4-hydroxybenzyl alcohol react. By controlling the molar ratio of the two to be close to 1:1 and a slight excess of dichloropentaerythritol phosphite, only one chlorine group on the dichloropentaerythritol phosphite participates in the reaction to obtain intermediate 1. The specific reaction process is shown below:

[0024]

[0025] S3, in a three-necked flask equipped with a stirring apparatus, 4-hydroxystyrene, intermediate 1, triethylamine (acid binding agent) and toluene were mixed and stirred, the reaction temperature was controlled to 75 ° C, and the reaction was incubated for 8 hours. After the reaction was complete, triethylamine hydrochloride was filtered out, and part of the solvent was removed by rotary evaporation. The mixture was purified by column chromatography (eluent was a mixed solvent of benzene / ethyl acetate in a volume ratio of 5:3), and the eluent was removed by rotary evaporation to obtain intermediate 2; the ratio of the amount of 4-hydroxystyrene, intermediate 1, triethylamine and toluene was 11.9 g:46.4 g:15 mL:120 mL;

[0026] Triethylamine acts as an acid-binding agent to remove the hydrogen chloride generated by the reaction, and 4-hydroxystyrene and intermediate 1 undergo a nucleophilic substitution reaction to obtain intermediate 2. The specific reaction process is shown below:

[0027]

[0028] S4. Add intermediate 2, azobisisobutyronitrile (AIBN), mercaptoethylamine and toluene to a three-necked flask and stir to mix evenly. Maintain the temperature of the system at 80°C and keep the reaction for 6 hours. After the reaction is completed, distill under reduced pressure and then purify by column chromatography (the eluent is a mixed solvent of ethyl acetate / benzene in a volume ratio of 2:5). The eluent is removed by rotary evaporation to obtain a synergistic antioxidant; the ratio of intermediate 2, AIBN, mercaptoethylamine and toluene is 54.8 g:0.8 g:7.7 g:120 mL;

[0029] Under the action of AIBN, the unsaturated carbon-carbon double bond on the intermediate 2 molecule undergoes a thiol-ene click reaction with the thiol group of mercaptoethylamine to obtain a synergistic antioxidant. The specific reaction process is as follows:

[0030]

[0031] The prepared synergistic antioxidant molecule contains phosphite, hindered phenol, sulfur element and amino structure. Among them, the introduced phosphite can serve as a kind of auxiliary antioxidant, which can decompose the hydroperoxides generated by oxidative aging in the polymer and make them inactive substances, thereby achieving the purpose of terminating or delaying the oxidative degradation of the polymer; moreover, the hindered phenol group belongs to phenolic antioxidants, and the structure of this type of antioxidant contains -OH functional groups. The -OH functional groups are more likely to provide H atoms in the reaction. This process occurs through proton donation, thereby destroying the free radical auto-oxidation in the chain reaction and achieving the antioxidant effect. , can play a synergistic role with phosphites, greatly enhancing the oxidation stability of grease; in addition, elemental sulfur can react with metals to form a sulfide film, thereby playing an anti-wear role. Not only that, when the working conditions are harsh or enter extreme pressure conditions, due to the breakage of the CS bond, an inorganic sulfide protective film can be generated, which can give the grease strong extreme pressure and wear resistance, and can play a synergistic role with phosphorus and nitrogen to further enhance the extreme pressure and anti-wear properties of the grease; finally, the introduced amino group can participate in the polymerization reaction and connect to the macromolecular chain of polyurea, thereby improving the migration and exudation resistance of the synergistic antioxidant and improving the stability of the synergistic antioxidant.

[0032] Beneficial effects of the present invention:

[0033] 1. The lubricating grease prepared by the present invention adopts a plurality of fatty amine composite components, which can improve the overall shear resistance, high temperature performance and storage stability of the lubricating grease;

[0034] 2. The synergistic antioxidant produced can significantly enhance the oxidation stability and extreme pressure and wear resistance of grease, and has stable performance and is not easy to fall off;

[0035] Therefore, the grease prepared by the present invention has a simple process, excellent overall performance, and stable and efficient oxidation stability and extreme pressure and wear resistance, and has important application value in the field of grease technology. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making any creative efforts shall fall within the scope of protection of the present invention.

[0037] Example 1

[0038] Preparation of synergistic antioxidants:

[0039] S1. In a three-necked flask equipped with a thermometer, an electromagnetic stirrer and a spherical condenser, a drying tube is added to the outlet of the condenser, and the drying tube is connected to a tail gas absorption device to absorb the generated hydrogen chloride gas. After mixing 13.6 g of pentaerythritol and 100 mL of benzene, 27.4 g of phosphorus trichloride is slowly added dropwise under stirring, and the temperature is controlled not to exceed 30° C. After the addition is complete, the temperature is raised to 72° C. and the reaction is refluxed for 3 hours. After the reaction is complete, the solvent benzene and excess phosphorus trichloride are distilled off to obtain dichloropentaerythritol phosphite;

[0040] S2. In a three-necked flask equipped with a stirring device, 28.7 g of dichloropentaerythritol phosphite, 23.6 g of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 15 mL of potassium carbonate and 100 mL of N,N-dimethylformamide were mixed and stirred uniformly. The reaction temperature was controlled to 75° C. and the reaction was kept warm for 6 h. After the reaction was completed, the product was filtered, and some of the solvent was removed by rotary evaporation. The product was then purified by column chromatography (eluent: a mixed solvent of benzene / ethyl acetate in a volume ratio of 4:3), and the eluent was removed by rotary evaporation to obtain intermediate 1.

[0041] S3, in a three-necked flask equipped with a stirring device, 11.9g 4-hydroxystyrene, 46.4g intermediate 1, 15mL triethylamine and 120mL toluene were mixed and stirred uniformly, the reaction temperature was controlled to 75°C, and the reaction was kept warm for 8h. After the reaction was completed, triethylamine hydrochloride was filtered out, and part of the solvent was removed by rotary evaporation. The product was then purified by column chromatography (eluent: a mixed solvent of benzene / ethyl acetate, the volume ratio of the two being 5:3), and the eluent was removed by rotary evaporation to obtain intermediate 2;

[0042] S4. Add 54.8 g of intermediate 2, 0.8 g of azobisisobutyronitrile, 7.7 g of mercaptoethylamine and 120 mL of toluene into a three-necked flask and stir to mix evenly. Maintain the temperature of the system at 80°C and keep the reaction for 6 hours. After the reaction is completed, distill under reduced pressure and purify by column chromatography (the eluent is a mixed solvent of ethyl acetate / benzene in a volume ratio of 2:5). Remove the eluent by rotary evaporation to obtain a synergistic antioxidant.

[0043] Example 2

[0044] Preparation of synergistic antioxidants:

[0045] S1. In a three-necked flask equipped with a thermometer, an electromagnetic stirrer and a spherical condenser, a drying tube is added to the outlet of the condenser, and the drying tube is connected to a tail gas absorption device to absorb the generated hydrogen chloride gas. After mixing 27.2g of pentaerythritol and 200mL of benzene, 54.8g of phosphorus trichloride is slowly added dropwise under stirring, and the temperature is controlled not to exceed 30°C. After the addition is complete, the temperature is raised to 72°C, and the reaction is refluxed for 3h. After the reaction is completed, the solvent benzene and excess phosphorus trichloride are distilled off to obtain dichloropentaerythritol phosphite;

[0046] S2. In a three-necked flask equipped with a stirring device, 57.4 g of dichloropentaerythritol phosphite, 47.2 g of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 30 mL of potassium carbonate and 200 mL of N,N-dimethylformamide were mixed and stirred uniformly. The reaction temperature was controlled to 75° C. and the reaction was kept warm for 6 h. After the reaction was completed, the product was filtered, and some of the solvent was removed by rotary evaporation. The product was then purified by column chromatography (eluent: a mixed solvent of benzene / ethyl acetate in a volume ratio of 4:3), and the eluent was removed by rotary evaporation to obtain intermediate 1.

[0047] S3, in a three-necked flask equipped with a stirring device, 23.8g 4-hydroxystyrene, 92.8g intermediate 1, 30mL triethylamine and 240mL toluene were mixed and stirred uniformly, the reaction temperature was controlled to 75°C, and the reaction was kept warm for 8h. After the reaction was completed, triethylamine hydrochloride was filtered out, and part of the solvent was removed by rotary evaporation. The product was then purified by column chromatography (eluent: a mixed solvent of benzene / ethyl acetate, the volume ratio of the two being 5:3), and the eluent was removed by rotary evaporation to obtain intermediate 2;

[0048] S4. Add 109.6 g of intermediate 2, 1.6 g of azobisisobutyronitrile, 15.4 g of mercaptoethylamine and 240 mL of toluene into a three-necked flask and stir to mix evenly. Maintain the temperature of the system at 80°C and keep the reaction for 6 hours. After the reaction is completed, distill under reduced pressure and purify by column chromatography (the eluent is a mixed solvent of ethyl acetate / benzene in a volume ratio of 2:5). Remove the eluent by rotary evaporation to obtain a synergistic antioxidant.

[0049] Example 3

[0050] A1. In a reactor, 80 g of 500N base oil, 3 g of dodecylamine, 3.5 g of hexadecylamine, 4 g of MDI, and 4 g of the synergistic antioxidant prepared in Example 1 were mixed and reacted at 80° C. for 1 h. After the reaction, the temperature was maintained at 80° C.;

[0051] A2. Add 2 g of water to the reactor in step A1 and mix, and react at 80°C for 30 min;

[0052] A3. Heat the reactor of step A2 to 180°C, then add 20g of 500N quench oil. After 1 hour, cool to 80°C, add 3g of sulfurized lard and 4g of sulfonate, and stir evenly; cool to room temperature and grind homogenously twice to obtain a composite fatty amine polyurea grease.

[0053] Example 4

[0054] A1. In a reactor, 100 g of 500N base oil, 6 g of octadecylamine, 3 g of dodecylamine, 5 g of MDI, and 8 g of the synergistic antioxidant prepared in Example 1 were mixed and reacted at 80° C. for 1-2 h. After the reaction, the temperature was maintained at 100° C.;

[0055] A2. Add 5 g of water to the reactor in step A1 and mix, and react at 100°C for 30 min;

[0056] A3. Heat the reactor of step A2 to 200°C, then add 20g 500N quench oil. After 1h, cool to 100°C, add 4g triethyl phosphate and 6g benzotriazole, and stir evenly; cool to room temperature and grind homogenously 3 times to obtain a composite fatty amine polyurea grease.

[0057] Example 5

[0058] A1. In a reactor, 120 g of 500N base oil, 7.7 g of hexadecylamine, 4 g of octadecylamine, 6 g of MDI, and 12 g of the synergistic antioxidant prepared in Example 2 were mixed and reacted at 100° C. for 2 h. After the reaction, the temperature was maintained at 100° C.;

[0059] A2. Add 8 g of water to the reactor in step A1 and mix, and react at 100°C for 30 min;

[0060] A3. Heat the reactor of step A2 to 200°C, then add 30g 500N quench oil. After 2h, cool to 100°C, add 6g triethyl phosphate and 8g benzotriazole, and stir evenly; cool to room temperature and grind homogenously 3 times to obtain a composite fatty amine polyurea grease.

[0061] Comparative Example 1

[0062] A1. Add 50g of 500N base oil to a reactor to dissolve 5.3g of octadecylamine, then add 2.5g of MDI and react at 80°C for 1h.

[0063] A2. Add 6 g of water to the reactor in step A1, stir at 100°C for 10 min, and then refine to 200°C;

[0064] A3. Add 10 g of 500N quench oil, 3 g of triethyl phosphate, 6 g of the synergistic antioxidant prepared in Example 2, and 4 g of benzotriazole to the reactor in step A2. After cooling to room temperature, grind three times to remove the fat.

[0065] A4. Dissolve 5.8 g of dodecyl hydroxystearic acid in 50 g of 500N base oil heated to 80°C in a reactor. Maintain the temperature at 80°C after dissolution.

[0066] A5. Add 0.6 g of lithium hydroxide and 1.8 g of water to the reactor in step A4, stir the reaction for 5 min, then add 0.2 g of calcium hydroxide and 0.6 g of water; stir the reaction for 1 h;

[0067] A6. Refining the reactor in step A5 to 210°C, adding 10g 500N quench oil, 3g triethyl phosphate, 6g synergistic antioxidant prepared in Example 2 and 4g benzotriazole, cooling to room temperature, grinding three times to extract the fat;

[0068] A7. Evenly mix the lithium calcium greases from step A3 and step A6, and grind again to obtain grease.

[0069] Comparative Example 2

[0070] The synergistic antioxidant in Example 5 was replaced by a commercially available hindered phenol antioxidant of equal mass, and the remaining steps were the same as in Example 5 to prepare a lubricating grease.

[0071] The following performance tests were performed on the greases of Examples 3-5 and Comparative Examples 1-2:

[0072] The dropping point is measured using the national standard GB / T 3498 "Determination of the dropping point of lubricating greases over a wide temperature range";

[0073] The national standard GB / T 269 "Determination of cone penetration of lubricating greases and petroleum greases" is used to determine the shear stability (the difference between the extended working cone penetration and the working cone penetration);

[0074] The national standard GB / T 5096 "Petroleum Products Copper Strip Corrosion Test Method" is used to determine the copper strip corrosion level;

[0075] The national standard GB / T 5018 "Test method for corrosion resistance of lubricating grease" is used to determine whether the corrosion resistance is qualified;

[0076] The wear spot diameter of the sample before and after 90 days at room temperature was measured using the NB / SH / T 0189 "Determination of Anti-wear Properties of Lubricating Oils - Four-ball Method";

[0077] The national standard SH / T 0193-2008 "Determination of oxidation stability of lubricating oils - Rotating oxygen bomb method" was used to measure the oxidation stability of the samples before and after 90 days at room temperature.

[0078] Use an electronic watch to measure the synthesis time;

[0079] The measured results are shown in the following table:

[0080]

[0081] As can be seen from the above table, the grease prepared in the embodiment of the present invention takes a short time to synthesize, the short-chain fatty amine provides a high dropping point, the long-chain fatty amine provides thickening ability, the overall performance is excellent, and it has stable and efficient oxidation stability and extreme pressure and wear resistance, and has important application value in the field of grease technology.

[0082] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0083] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a composite fatty amine polyurea grease, characterized in that: The following steps are involved: A1. Mix mineral base oil, fatty amine, isocyanate and synergistic antioxidant in a reactor and react at 80-100°C for 1-2 hours. After the reaction is completed, maintain the temperature at 80-100°C. A2. Add water to the reactor in step A1 and react at 80-100°C for 30 minutes; A3. Heat the reactor of step A2 to 180-200°C, then add quenching oil. After 1-2 hours, cool to 80-100°C, add extreme pressure anti-wear agent and rust inhibitor, and stir evenly; cool to room temperature and grind homogenously to obtain composite fatty amine polyurea grease; The raw materials are calculated in parts by weight as follows: 80-120 parts of mineral base oil, 5-10 parts of fatty amine, 2-6 parts of isocyanate, 4-12 parts of synergistic antioxidant, 2-8 parts of water, 20-30 parts of quench oil, 3-6 parts of extreme pressure anti-wear agent, and 4-8 parts of rust inhibitor; Wherein, the synergistic antioxidant is prepared by the following steps: S1. After pentaerythritol and benzene are mixed, phosphorus trichloride is added dropwise under stirring, and the temperature is controlled not to exceed 30° C. After the addition is complete, the mixture is refluxed at 72° C. for 3 hours. After the reaction is complete, distillation is performed to obtain dichloropentaerythritol phosphite; S2. Dichloropentaerythritol phosphite, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, potassium carbonate and N,N-dimethylformamide were mixed and stirred uniformly, and reacted at 75° C. for 6 h. After the reaction was completed, the mixture was filtered, rotary evaporated, purified by column chromatography, and rotary evaporated to obtain intermediate 1; S3, 4-hydroxystyrene, intermediate 1, triethylamine and toluene were mixed and stirred, and reacted at 75°C for 8 hours. After the reaction was completed, the mixture was filtered, rotary evaporated, purified by column chromatography, and rotary evaporated to obtain intermediate 2; S4. The intermediate 2, azobisisobutyronitrile, mercaptoethylamine and toluene were stirred and mixed evenly, and reacted at 80° C. for 6 h. After the reaction was completed, the mixture was distilled under reduced pressure, purified by column chromatography, and rotary evaporated to obtain a synergistic antioxidant.

2. The method for preparing a composite fatty amine polyurea grease according to claim 1, characterized in that: In step S1, the ratio of pentaerythritol, benzene and phosphorus trichloride is 13.6 g:100 mL:27.4 g.

3. The method for preparing a composite fatty amine polyurea grease according to claim 1, characterized in that: In step S2, the ratio of dichloropentaerythritol phosphite, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, potassium carbonate, and N,N-dimethylformamide is 28.7 g:23.6 g:15 mL:100 mL.

4. The method for preparing a composite fatty amine polyurea grease according to claim 1, characterized in that: In step S3, the ratio of 4-hydroxystyrene, intermediate 1, triethylamine, and toluene is 11.9 g:46.4 g:15 mL:120 mL.

5. The method for preparing a composite fatty amine polyurea grease according to claim 1, characterized in that: In step S4, the ratio of the amount of intermediate 2, azobisisobutyronitrile, mercaptoethylamine, and toluene is 54.8 g:0.8 g:7.7 g:120 mL.

6. The method for preparing a composite fatty amine polyurea grease according to claim 1, characterized in that: The fatty amines are two or more of octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine and octadecylamine.

7. A composite fatty amine polyurea grease, characterized in that: Prepared according to the method according to any one of claims 1 to 6.

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