Urea-based lubricating grease and preparation method thereof

Abstract

The urea-based lubricating grease provided by the invention has excellent oxidation resistance, corrosion and rust resistance and colloid stability. The urea-based lubricating grease disclosed by the invention is prepared from the following components in percentage by weight based on the total weight of the lubricating grease: 0.1 to 10 percent of imidazoline derivative, 3 to 30 percent of urea-based thickening agent and 65 to 95 percent of lubricating base oil, wherein the structure of the imidazoline derivative is shown as a formula (I), in the formula (I), n is an integer between 1 and 10, and each R group is independently selected from C2-C5 alkylene; the R0 group is selected from C15-C20 alkyl, cycloalkyl or alkenyl; and each R'group is independently selected from alkyl groups of C1 to C20, aryl groups of C6 to C10, and aryl groups of C6 to C10 substituted by straight chain or branched chain alkyl groups of C1 to C10.

Description

Technical Field

[0001] The present invention relates to a lubricating grease, in particular to a urea-based lubricating grease with excellent antioxidant, anti-corrosion and anti-rust properties and colloid stability. Background Art

[0002] Grease is an essential working medium for the normal operation of mechanical equipment and in the manufacturing and processing of materials. With the progress and development of the machinery industry, more stringent requirements have gradually been placed on related grease products. Grease needs to have good antioxidant properties, anti-rust properties, and a long service life, etc.

[0003] To improve the antioxidant properties of grease, it is usually necessary to add different types of antioxidants to the grease. Commonly used antioxidants include phenolic antioxidants, amine antioxidants, sulfur-phosphorus-zinc salts, and the like. CN 111500344A proposes adding one of diphenylamine, diisooctyldiphenylamine, N-phenyl-α-naphthylamine, 2,6-di-tert-butyl-p-cresol, and 2,6-di-tert-butyl-4-methylphenol to urea-based grease as an antioxidant; CN 112522008A proposes adding tert-butyl / octyldiphenylamine to urea-based grease as an antioxidant. These greases still have room for further improvement in terms of corrosion and rust prevention.

[0004] Developing grease with good anti-oxidation, anti-corrosion and anti-rust properties is still the research and development direction of technical personnel in this field. Summary of the Invention

[0005] The present invention provides a urea-based lubricating grease with excellent antioxidant, anti-corrosion and anti-rust properties and colloid stability.

[0006] The urea-based grease of the present invention comprises, based on the total weight of the grease, 0.1% to 10% of an imidazoline derivative, 3% to 30% of a urea-based thickener, and 65% to 95% of a lubricating base oil; wherein the structure of the imidazoline derivative is as shown in formula (I):

[0007]

[0008] In formula (I), n is an integer between 1 and 10, each R group is independently selected from a C2 to C5 alkylene group; R0 group is selected from C 15 ~C 20 alkyl, cycloalkyl or alkenyl; each R' group is independently selected from C1 to C 20 Alkyl, C6~C 10 Aryl, C1~C 10 C6~C 10 of aromatic groups.

[0009] According to the present invention, the R0 group can be C 15 ~C 20 The alkyl group can also be C 15 ~C 20 The cycloalkyl group can also be C 15 ~C 20 The alkenyl group. 15 ~C 20 The alkenyl group may be a group containing one or more carbon-carbon double bonds within the group and an alkyl group at the end of the group, a group with a carbon-carbon double bond at the end of the group, or a group containing one or more carbon-carbon double bonds within the group and a carbon-carbon double bond at the end of the group.

[0010] According to the present invention, preferably, in formula (I), n is an integer between 1 and 5 (for example, 1, 2, 3, 4 or 5), each R group is independently selected from ethylene or propylene; R0 group is selected from C 16 ~C 18 Each R' group is independently selected from C2 to C8 alkyl, phenyl, C4 to C 10 The phenyl group substituted by a straight or branched alkyl group. 10 The straight chain or branched alkyl substituted phenyl group is preferably replaced by C4 to C 10 The phenyl group substituted with a straight-chain or branched alkyl group may be, for example, p-butylphenyl, p-isooctylphenyl, or p-nonylphenyl.

[0011] According to the present invention, the imidazoline derivative may be one or more of the following compounds:

[0012]

[0013]

[0014] According to the present invention, the preparation method of the imidazoline derivative comprises the following steps:

[0015] (1) reacting CS2 with a compound represented by formula (X);

[0016]

[0017] The R' groups are independently selected from C1 to C 20 Alkyl, C6~C 10 Aryl, C1~C 10 C6~C 10 aryl groups;

[0018] (2) reacting the reaction product of step (1) with a compound represented by formula (Y), and collecting the product;

[0019]

[0020] wherein n is an integer between 1 and 10, each R group is independently selected from a C2 to C5 alkylene group; R0 group is selected from a C 15 ~C 20 an alkyl, cycloalkyl or alkenyl group.

[0021] According to the present invention, preferably, n is an integer between 1 and 5 (for example, 1, 2, 3, 4 or 5), each R group is independently selected from ethylene or propylene; R0 group is selected from C 16 ~C 18 Each R' group is independently selected from C2 to C8 alkyl, phenyl, C4 to C 10 The phenyl group substituted by a straight or branched alkyl group. 10 The straight chain or branched alkyl substituted phenyl group is preferably replaced by C4 to C 10 The phenyl group substituted with a straight-chain or branched alkyl group may be, for example, p-butylphenyl, p-isooctylphenyl, or p-nonylphenyl.

[0022] According to the present invention, in step (1), the reaction formula between CS2 and the compound represented by formula (X) is as follows.

[0023]

[0024] According to the present invention, in step (2), the reaction formula between the reaction product of step (1) and the compound represented by formula (Y) is as follows.

[0025]

[0026] According to the present invention, in step (1), the molar ratio between CS2 and the compound represented by formula (X) can be 0.8 to 1.3:1, preferably 0.9 to 1.2:1; in step (2), the molar ratio between the compound represented by formula (Y) and CS2 in step (1) can be 1:0.5 to 1.5, preferably 1:0.8 to 1.2.

[0027] According to the present invention, in step (1), the temperature for the reaction between CS2 and the compound represented by formula (X) can be 10 to 50° C., preferably 15 to 25° C.; the reaction time is usually 0.5 to 5 h, preferably 0.5 to 2.5 h; in step (2), the temperature for the reaction between the reaction product of step (1) and the compound represented by formula (Y) can be 60 to 100° C., preferably 70 to 90° C.; the reaction time is usually 0.5 to 3 h, preferably 1 to 2 h.

[0028] According to the present invention, the compound represented by formula (Y) can be prepared by subjecting the compound represented by formula (α) and the compound represented by formula (β) to an amidation dehydration reaction followed by a cyclodehydration reaction;

[0029] R0COOH(β),

[0030] wherein n is an integer between 1 and 10, each R group is independently selected from a C2 to C5 alkylene group; R0 group is selected from a C 15 ~C 20 an alkyl, cycloalkyl or alkenyl group.

[0031] According to the present invention, preferably, n is an integer between 1 and 5 (for example, 1, 2, 3, 4 or 5), each R group is independently selected from ethylene or propylene; R0 group is selected from C 16 ~C 18 alkyl or alkenyl.

[0032] According to the present invention, the molar ratio between the compound represented by formula (α) and the compound represented by formula (β) can be 1 to 2:1, preferably 1 to 1.5:1; during the reaction of the compound represented by formula (α) and the compound represented by formula (β), the temperature for the amidation dehydration reaction can be 140 to 180°C, preferably 140 to 160°C, and the reaction time is usually 1 to 3 hours, preferably 1 to 2 hours; the temperature for the cyclodehydration reaction can be 180 to 250°C, preferably 220 to 240°C, and the reaction time is usually 2 to 6 hours, preferably 3 to 5 hours.

[0033] According to the present invention, a water-carrying agent may or may not be added during the reaction between the compound represented by formula (α) and the compound represented by formula (β). The water-carrying agent may be an aromatic hydrocarbon solvent, such as xylene.

[0034] According to the present invention, the compound represented by formula (X) can be selected from one or more of di-n-butylamine, diphenylamine, 4-butyldiphenylamine, 4,4'-di-n-butyldiphenylamine, 4-isooctyldiphenylamine and 4,4'-diisooctyldiphenylamine; the compound represented by formula (α) can be selected from one or more of diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine; and the compound represented by formula (β) can be selected from one or more of hexadecanoic acid, octadecanoic acid, oleic acid and linoleic acid.

[0035] According to the present invention, in step (2), the product of the reaction product of step (1) and the compound shown in formula (Y) reacts comprises the imidazoline derivative main product and a small amount of by-products. Since these by-products themselves can be used as additives, these by-products can be separated out in step (2), or these by-products can be retained in the product and directly used as additives. Those skilled in the art can obtain pure imidazoline derivatives by purification or separation methods, such as those that can be enumerated by vacuum distillation, molecular distillation, column chromatography or preparative chromatography.

[0036] According to the present invention, the urea-based thickener is preferably obtained by reacting an organic amine with an isocyanate. The organic amine can be selected from C6-C9 aromatic amines, C6-C 18 The alkylamine of C5-C8, cycloalkylamine of C5-C8, for example, can be one or more of aniline, benzylamine, C1-C3 alkyl-substituted aniline, benzylamine, C1-C2 alkylbenzylamine, octadecylamine, hexadecylamine, tetradecylamine, dodecylamine, aramidamine, nonylamine, octylamine, heptylamine, hexylamine and cyclohexylamine. The isocyanate can be selected from diisocyanates, for example, diphenylmethane diisocyanate ( MDI ), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI) and lysine diisocyanate (LDI). The molar ratio between the organic amine and the isocyanate can be 1:0.2 to 1, for example, 1:0.5.

[0037] According to the present invention, the lubricating base oil 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, fluorinated oil and silicone oil; the mineral oil can be one or more of paraffin base oil, intermediate base oil and naphthenic base oil; the vegetable oil can be one or more of castor oil, rapeseed oil, peanut oil and soybean oil; the lubricating base oil preferably has a kinematic viscosity of 2 to 60 mm at 100°C. 2 / s lubricating base oil, more preferably a kinematic viscosity of 3 to 30 mm at 100°C 2 / s lubricating base oil.

[0038] The method for preparing a urea-based grease of the present invention comprises: stirring and mixing a urea-based thickener and a portion of a lubricating base oil in a reaction kettle, adding the remaining lubricating base oil and an imidazoline derivative, mixing them uniformly, and then grinding them into a grease. The urea-based thickener is a reaction product of an organic amine and an isocyanate.

[0039] The urea-based lubricating grease of the present invention has excellent antioxidant performance, anti-corrosion and anti-rust performance and colloid stability performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is the LC-MS chart of the alkyl-substituted imidazoline product of step (1) in Example 1.

[0041] Figure 2 LC-MS chart of the product of step (3) in Example 1 (i.e., the imidazoline derivative of the present invention). DETAILED DESCRIPTION

[0042] The present invention is further described below by way of examples, but is not intended to limit the present invention. The main raw materials used in the present invention are as follows:

[0043]

[0044]

[0045] Example 1

[0046] (1) 113 g of diethylenetriamine was added to a reaction kettle, and 282 g of oleic acid was added dropwise to the reaction kettle at 90° C. The temperature was raised to 160° C. for amidation dehydration. After 18 ml of water was removed, the temperature was raised to 240° C. for cyclization dehydration. After another 18 mL of water was removed, the reaction was stopped to obtain a hydrocarbon-substituted imidazoline.

[0047]

[0048] The prepared alkyl substituted imidazoline was subjected to high performance liquid chromatography-mass spectrometry analysis using a Waters liquid chromatography-mass spectrometer. Figure 1 . Figure 1 The upper middle graph is the UV absorption peak graph, and the lower graph is the mass spectrum signal graph. Figure 1 It can be seen that the mass-to-charge ratio of the molecular ion peak corresponding to the two peaks at 0.33-0.55 min is 350.7 m / z, and these two peaks correspond to the peaks of the hydrocarbon-substituted imidazoline; the mass-to-charge ratio of the molecular ion peak corresponding to the peak at 0.6-0.75 min is 368.7 m / z, which corresponds to the peak of the oleamide by-product that failed to cyclize; the peaks at 4.6 and 4.8 min correspond to the peaks of the by-products of the continued amidation of imidazoline and oleic acid, and the continued amidation of oleamide and oleic acid, respectively.

[0049] (2) 129 g of di-n-butylamine and 76 g of carbon disulfide were reacted in 100 mL of water at a reaction temperature of 20° C. for 2 hours to generate a dithiocarbamic acid intermediate.

[0050]

[0051] (3) adding the hydrocarbon-substituted imidazoline obtained in step (1) to the dithiocarbamic acid intermediate obtained in step (2), reacting at 80° C. for 2 hours, and removing hydrogen sulfide to obtain the imidazoline derivative of the present invention.

[0052]

[0053] The prepared imidazoline derivatives were subjected to HPLC-MS analysis using Waters liquid chromatography-mass spectrometry. Figure 2 . Figure 2 The upper middle graph is the UV absorption peak graph, and the lower graph is the mass spectrum signal graph. Figure 2 It can be seen that the ion peak of 0.8min corresponds to the product of step (1); the ion peak of 1-1.3min corresponds to the imidazoline derivative; the ion peaks between 1.6-1.8min and 7-9min are the residual by-products in step (1).

[0054] In the product of embodiment 1, comprise described imidazoline derivative main product and a small amount of alkyl substituted imidazoline by-product, the by-product that fails cyclization oleamide by-product, alkyl substituted imidazoline continues to carry out amidation reaction with oleic acid, the by-product that fails cyclization oleamide continues to carry out amidation reaction with oleic acid.Because these by-products all can be used as lubricating oil additive, therefore in the present embodiment, there is no need to separate these by-products.Those skilled in the art can obtain pure imidazoline derivative by known purification or separation method.

[0055] Example 2

[0056] (1) 113 g of diethylenetriamine was added to a reaction kettle, and 280 g of linoleic acid was added dropwise to the reaction kettle at 90° C. The temperature was raised to 160° C. for amidation dehydration. After 18 ml of water was removed, the temperature was raised to 240° C. for cyclization dehydration. After another 18 mL of water was removed, the reaction was stopped to obtain a hydrocarbon-substituted imidazoline.

[0057] (2) 129 g of di-n-butylamine and 76 g of carbon disulfide were reacted in 100 mL of water at a reaction temperature of 20° C. for 2 hours to generate a dithiocarbamic acid intermediate.

[0058] (3) adding the hydrocarbon-substituted imidazoline obtained in step (1) to the dithiocarbamic acid intermediate obtained in step (2), reacting at 80° C. for 2 hours, and removing hydrogen sulfide to obtain the imidazoline derivative of the present invention.

[0059] Its structure is shown below.

[0060]

[0061] Example 3

[0062] (1) 113 g of diethylenetriamine was added to a reaction kettle, and 282 g of oleic acid was added dropwise to the reaction kettle at 90° C. The temperature was raised to 160° C. for amidation dehydration. After 18 ml of water was removed, the temperature was raised to 240° C. for cyclization dehydration. After another 18 mL of water was removed, the reaction was stopped to obtain a hydrocarbon-substituted imidazoline.

[0063] (2) 226 g of 4-butyldiphenylamine and 76 g of carbon disulfide were reacted in 100 mL of water at a reaction temperature of 20° C. for 2 hours to generate a dithiocarbamic acid intermediate.

[0064] (3) adding the hydrocarbon-substituted imidazoline obtained in step (1) to the dithiocarbamic acid intermediate obtained in step (2), reacting at 80° C. for 2 hours, and removing hydrogen sulfide to obtain the imidazoline derivative of the present invention.

[0065] Its structure is shown below.

[0066]

[0067] Example 4

[0068] (1) 113 g of diethylenetriamine was added to a reaction kettle, and 282 g of oleic acid was added dropwise to the reaction kettle at 90° C. The temperature was raised to 160° C. for amidation dehydration. After 18 ml of water was removed, the temperature was raised to 240° C. for cyclization dehydration. After another 18 mL of water was removed, the reaction was stopped to obtain a hydrocarbon-substituted imidazoline.

[0069] (2) 283 g of 4,4'-di-n-butyldiphenylamine and 76 g of carbon disulfide were reacted in 100 mL of water at a reaction temperature of 20°C for 2 hours to generate a dithiocarbamic acid intermediate.

[0070] (3) adding the hydrocarbon-substituted imidazoline obtained in step (1) to the dithiocarbamic acid intermediate obtained in step (2), reacting at 80° C. for 2 hours, and removing hydrogen sulfide to obtain the imidazoline derivative of the present invention.

[0071] Its structure is shown below.

[0072]

[0073] Example 5

[0074] (1) 113 g of diethylenetriamine was added to a reaction kettle, and 282 g of oleic acid was added dropwise to the reaction kettle at 90° C. The temperature was raised to 160° C. for amidation dehydration. After 18 ml of water was removed, the temperature was raised to 240° C. for cyclization dehydration. After another 18 mL of water was removed, the reaction was stopped to obtain a hydrocarbon-substituted imidazoline.

[0075] (2) 395 g of 4,4'-diisooctyldiphenylamine and 76 g of carbon disulfide were reacted in 100 mL of water at a reaction temperature of 20°C for 2 hours to generate a dithiocarbamic acid intermediate.

[0076] (3) adding the hydrocarbon-substituted imidazoline obtained in step (1) to the dithiocarbamic acid intermediate obtained in step (2), reacting at 80° C. for 2 hours, and removing hydrogen sulfide to obtain the imidazoline derivative of the present invention.

[0077] Its structure is shown below.

[0078]

[0079] Comparative Example 1

[0080] 113g of diethylenetriamine was placed in a reaction kettle. 282g of oleic acid was added dropwise at 90°C. The temperature was raised to 160°C for amidation dehydration. After 18ml of water was removed, the temperature was raised to 240°C for further cyclodehydration. The reaction was terminated after another 18ml of water was removed to yield a alkyl-substituted imidazoline. Its structure is shown below.

[0081]

[0082] Comparative Example 2

[0083] (1) 113 g of diethylenetriamine was placed in a reaction kettle, and 282 g of oleic acid was added dropwise to the reaction kettle at 90°C. The temperature was raised to 160°C for amidation dehydration. After 18 ml of water was removed, the temperature was raised to 240°C for cyclodehydration. After another 18 mL of water was removed, the reaction was stopped to obtain a hydrocarbon-substituted imidazoline.

[0084] (2) Add dodecenylsuccinic acid to the hydrocarbon-substituted imidazoline obtained in step (1), and react at 130° C. for 2 hours to obtain heptadecenyl imidazoline alkenylsuccinate. The structure of the heptadecenyl imidazoline alkenylsuccinate is shown below.

[0085]

[0086] Example 6

[0087] 290 g of PAO6 base oil, 29.7 g of octadecylamine and 3.0 g of p-toluidine were added to a fat-making kettle, stirred evenly, heated to 70°C, and a mixed solution of MDI and PAO6 base oil (containing 17.3 g of MDI and 50 g of PAO6 base oil) was added. The mixture was stirred for 30 minutes, and 100 g of PAO6 base oil and 10 g of the imidazoline derivative synthesized in Example 1 were added. The mixture was ground three times on a three-roll mill to form fat.

[0088] Example 7

[0089] The grease of Example 7 was prepared under the same conditions as in Example 6, except that the imidazoline derivative prepared in Example 1 was replaced by the imidazoline derivative prepared in Example 2.

[0090] Example 8

[0091] 340 g of PAO10 base oil, 33.4 g of octadecylamine and 3.1 g of cyclohexylamine were added to a fat-making kettle, stirred evenly, heated to 70°C, 13.5 g of TDI was added, and stirred for 30 minutes. 100 g of PAO10 base oil and 10 g of the imidazoline derivative prepared in Example 3 were added, and the mixture was ground three times on a three-roll mill to form fat.

[0092] Example 9

[0093] The grease of Example 9 was prepared under the same conditions as in Example 8, except that the imidazoline derivative prepared in Example 3 was replaced by the imidazoline derivative prepared in Example 4.

[0094] Example 10

[0095] 325 g of 500N base oil and 40.8 g of dodecylamine were added to a fat-making kettle, stirred evenly, heated to 50° C., 19.2 g of TDI was added, and stirred for 30 min. 100 g of 500N base oil and 15 g of the imidazoline derivative prepared in Example 5 were added, and the mixture was ground three times on a three-roll mill to form fat.

[0096] Comparative Example 3

[0097] The grease of Comparative Example 3 was prepared under the same conditions as in Example 6, except that the imidazoline derivative prepared in Example 1 was replaced by the imidazoline derivative prepared in Comparative Example 1.

[0098] Comparative Example 4

[0099] The grease of Comparative Example 4 was prepared under the same conditions as in Example 8, except that the imidazoline derivative prepared in Example 3 was replaced by the imidazoline derivative prepared in Comparative Example 2.

[0100] Comparative Example 5

[0101] The grease of Comparative Example 5 was prepared under the same conditions as in Example 6, except that the imidazoline derivative prepared in Example 1 was replaced by V81.

[0102] The performance of the greases of Examples 6 to 10 and Comparative Examples 3 to 5 was evaluated using the following evaluation methods: GB / T 269 "Determination of cone penetration of lubricating greases and petroleum greases", GB / T 3498 "Determination of dropping point of lubricating greases over a wide temperature range", NB / SH / T 0324 "Determination of oil separation of lubricating greases - cone and mesh method", SH / T 0325 "Determination of oxidation stability of lubricating greases", SH / T 0790 "Determination of oxidation induction period of lubricating greases", GB / T 5018 "Test method for corrosion resistance of lubricating greases", and GB / T 7326 "Test method for copper corrosion of lubricating greases". The evaluation results are shown in Table 1.

[0103] Table 1 Grease performance evaluation results

[0104]

Claims

1. A urea-based grease comprising, based on the total weight of the grease, 0.1% to 10% of an imidazoline derivative, 3% to 30% of a urea-based thickener, and 65% to 95% of a lubricating base oil; wherein the structure of the imidazoline derivative is as shown in formula (I): In formula (I), n is an integer between 1 and 10, each R group is independently selected from a C2 to C5 alkylene group; R0 group is selected from C 15 ~C 20 alkyl, cycloalkyl or alkenyl; each R' group is independently selected from C1 to C 20 Alkyl, C6~C 10 Aryl, C1~C 10 C6~C 10 of aromatic groups.

2. The urea-based grease according to claim 1, characterized in that: In formula (I), n is an integer between 1 and 5, each R group is independently selected from ethylene or propylene; R0 group is selected from C 16 ~C 18 Each R' group is independently selected from C2 to C8 alkyl, phenyl, C4 to C 10 The phenyl group substituted by a straight chain or branched alkyl group (the C4 to C 10 The straight chain or branched alkyl substituted phenyl group is preferably replaced by C4 to C 10 a phenyl group substituted with a straight-chain or branched-chain alkyl group).

3. The urea-based grease according to claim 1, characterized in that: The imidazoline derivatives are one or more of the following compounds:

4. The urea-based grease according to claim 1, characterized in that: The preparation method of the imidazoline derivative comprises the following steps: (1) reacting CS2 with a compound represented by formula (X); The R' groups are independently selected from C1 to C 20 Alkyl, C6~C 10 Aryl, C1~C 10 C6~C 10 aryl groups; (2) reacting the reaction product of step (1) with a compound represented by formula (Y), and collecting the product; wherein n is an integer between 1 and 10, each R group is independently selected from a C2 to C5 alkylene group; R0 group is selected from a C 15 ~C 20 an alkyl, cycloalkyl or alkenyl group.

5. The urea-based grease according to claim 4, characterized in that: n is an integer between 1 and 5, each R group is independently selected from ethylene or propylene; R0 group is selected from C 16 ~C 18 Each R' group is independently selected from C2 to C8 alkyl, phenyl, C4 to C 10 The phenyl group substituted by a straight chain or branched alkyl group (the C4 to C 10 The straight chain or branched alkyl substituted phenyl group is preferably replaced by C4 to C 10 a phenyl group substituted with a straight-chain or branched-chain alkyl group).

6. The urea-based grease according to claim 4, characterized in that: In step (1), the molar ratio of CS2 to the compound represented by formula (X) is 0.8 to 1.3:1; in step (2), the molar ratio of the compound represented by formula (Y) to CS2 in step (1) is 1:0.5 to 1.

5.

7. The urea-based grease according to claim 4, characterized in that: In step (1), the temperature for the reaction between CS2 and the compound represented by formula (X) is 10 to 50° C., and the reaction time is 0.5 to 5 h. In step (2), the temperature for the reaction between the reaction product of step (1) and the compound represented by formula (Y) is 60 to 100° C., and the reaction time is 0.5 to 3 h.

8. The urea-based grease according to claim 4, characterized in that: The compound represented by formula (Y) is prepared by subjecting the compound represented by formula (α) and the compound represented by formula (β) to an amidation dehydration reaction followed by a cyclization dehydration reaction; wherein n is an integer between 1 and 10, each R group is independently selected from a C2 to C5 alkylene group; R0 group is selected from a C 15 ~C 20 an alkyl, cycloalkyl or alkenyl group.

9. The urea-based grease according to any one of claims 1 to 8, characterized in that: The urea-based thickener is obtained by reacting an organic amine with an isocyanate; and the lubricating base oil is selected from one or more of synthetic oil, mineral oil and vegetable oil.

10. The urea-based grease according to claim 9, characterized in that The organic amine is selected from C6-C9 aromatic amine, C6-C 18 The invention relates to a method for preparing an alkylamine having a C5-C8 alkylamine and a cycloalkylamine having a C5-C8 alkylamine; the isocyanate is selected from diisocyanate; the synthetic oil is one or more of poly-α-olefin oil, ester oil, fluoro oil and silicone oil; the mineral oil is one or more of paraffin base oil, intermediate base oil and cycloalkyl base oil; and the vegetable oil is one or more of castor oil, rapeseed oil, peanut oil and soybean oil.

11. A method for preparing the urea-based grease according to any one of claims 1 to 10, comprising: The urea-based thickener and part of the lubricating base oil are stirred and mixed in a reactor, and the remaining lubricating base oil and imidazoline derivative are added, mixed evenly and then ground into fat.

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