Lubricating grease as well as preparation method and application thereof

Abstract

The invention relates to the technical field of lubricating grease, and provides lubricating grease as well as a preparation method and application thereof. The lubricating grease provided by the invention comprises the following components in percentage by mass: 65-94% of base oil, 5-15% of a thickening agent and 1-20% of an additive, wherein the additive is lithium salt. The lithium salt is adopted as the additive and can be complexed with carbonyl in the thickening agent and / or the base oil, the soap fiber structure of the lubricating grease is enhanced, and the lubricating grease is effectively prevented from leaking in a high-temperature environment; meanwhile, due to the formation of the complex, the viscosity of the lubricating grease can be enhanced, and the mechanical strength and high-temperature stability of the lubricating grease are improved, so that the lubricating grease has excellent antifriction and antiwear properties in a wider temperature range. The lubricating grease provided by the invention is suitable for transmission equipment for metal processing, railway transportation and the like, can effectively overcome the problems of aggravated wear of transmission parts at high temperature and the like, is beneficial to prolonging the service life of the equipment, and achieves the purposes of environmental protection, safety and health.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating grease, and in particular to lubricating grease and a preparation method and application thereof. Background Art

[0002] Grease is a greasy semi-solid lubricant, mainly composed of base oil and thickener. It can lubricate and seal, and is widely used in the lubrication and protection of mechanical moving parts such as gears and bearings.

[0003] In the production process of major equipment, it is inevitable to encounter friction loss and severe wear failures under extreme conditions. In the entire system, there are a large number of mechanical equipment with high energy consumption, high safety risks and low utilization efficiency, which has caused great obstacles to the advancement of manufacturing technology and enterprise cost management. Therefore, it is essential to use grease to reduce wear and anti-wear of mechanical equipment to improve the smooth operation of equipment parts.

[0004] The operating conditions of transmission systems such as metal processing equipment and railway transportation equipment are complex, especially under high temperature conditions, the wear of transmission parts will be aggravated. In the prior art, in order to improve the high temperature resistance of grease, the commonly used measure is to add a multi-component antioxidant. For example, Chinese patent CN115109629A discloses a high temperature grease, in which 0.5 to 2 parts of amine antioxidants or phenolic antioxidants are added; Chinese patent CN111269743A provides a wear-resistant and high temperature resistant grease, in which 0.5 to 1.5 parts of alkylated phenyl naphthylamine antioxidants are added. However, these antioxidants may interact with other additives, resulting in reduced performance of the additives or undesirable chemical reactions; more importantly, although the above-mentioned grease has good high temperature resistance, it does not mention how the friction reduction and wear resistance at lower temperatures. Greases used for transmission equipment such as metal processing or railway transportation need to meet the normal operation under variable temperature environments while meeting the daily operation, so as to ensure a longer maintenance cycle and maintenance-free equipment, that is, the grease needs to have excellent friction reduction and wear resistance in a wide temperature range. Summary of the invention

[0005] In view of this, the present invention provides a lubricating grease and a preparation method and application thereof. The lubricating grease provided by the present invention has excellent friction reduction and anti-wear performance in a wide temperature range, is suitable for transmission equipment such as metal processing and railway transportation, can effectively overcome the problem of increased wear of transmission parts at high temperatures, is conducive to extending the service life of the equipment, and achieves the purpose of green environmental protection, safety and health.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A lubricating grease comprising the following components by mass fraction: 65-94% base oil, 5-15% thickener, and 1-20% additive;

[0008] The base oil includes one or more of mineral oil, hydrocarbon oil and ester oil;

[0009] The thickener includes a soap-based thickener and / or a non-soap-based thickener; the non-soap-based thickener includes a polyurea thickener and / or an inorganic thickener;

[0010] The additive is a lithium salt.

[0011] Preferably, the lithium salt includes one or more of butyl lithium, phenyl lithium, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate and lithium hexafluorophosphate.

[0012] Preferably, the kinematic viscosity of the base oil at 40°C is 28 mm 2 / s~62mm 2 / s.

[0013] Preferably, the mineral oil comprises one or more of 150N, 150SN and 300N;

[0014] The hydrocarbon oil includes one or more of polyalphaolefins, alkane oils, cyclohexane oils and aromatic oils;

[0015] The ester oil includes one or more of trimethylolpropane oleate, dipentaerythritol ester and glycol fatty acid ester.

[0016] Preferably, the polyurea thickener is obtained by reacting a monoamine, a diamine and a diisocyanate; when the thickener is a polyurea thickener, the mass fraction of the thickener in the grease is calculated based on the total mass fraction of the raw materials used to prepare the thickener;

[0017] The monoamine includes one or more of octadecylamine, monoethanolamine, aniline, piperazine and isobutylamide; the diamine includes one or more of ethylenediamine, p-phenylenediamine and 4,4'-methylenedianiline; the diisocyanate includes one or more of toluene diisocyanate, methane diisocyanate, 1,6-hexamethylene diisocyanate and 4,4'-diphenylmethane diisocyanate.

[0018] Preferably, the inorganic thickener includes one or more of bentonite, silicon dioxide, attapulgite, aluminum silicate and boron nitride;

[0019] The soap-based thickener includes one or more of lithium soap, calcium soap, aluminum soap and barium soap.

[0020] The present invention also provides a method for preparing the grease described in the above scheme, comprising the following steps:

[0021] dissolving a thickener or a raw material for preparing the thickener in the first part of the base oil to obtain a solution;

[0022] The dissolving liquid and a second part of base oil are mixed and then heat treated to obtain a heat-treated liquid;

[0023] The heat-treated liquid, additives and remaining base oil are mixed, and the resulting mixed liquid is ground to obtain the grease.

[0024] Preferably, the dissolving temperature is 110-125°C;

[0025] The temperature of the mixture of the dissolving liquid and the second part of the base oil is 130-150°C;

[0026] The heat treatment temperature is 210-220° C. and the time is 10-20 min.

[0027] Preferably, the method of mixing the heat treatment liquid, the additive and the remaining base oil includes: lowering the temperature of the heat treatment liquid to 180-190° C., then adding the additive and the remaining base oil, continuing to stir until the temperature drops to 60-100° C., and then naturally cooling to room temperature.

[0028] The present invention also provides the use of the grease described in the above scheme or the grease prepared by the preparation method described in the above scheme in transmission equipment.

[0029] The present invention provides a grease, comprising the following components by mass fraction: 65-94% base oil, 5-15% thickener, and 1-20% additive; the base oil comprises one or more of mineral oil, hydrocarbon oil, and ester oil; the thickener comprises a soap-based thickener and / or a non-soap-based thickener; the non-soap-based thickener comprises a polyurea thickener and / or an inorganic thickener; and the additive is a lithium salt. The present invention uses lithium salt as an additive, and the lithium salt can be complexed with the carbonyl group in the thickener and / or the base oil to enhance the soap fiber structure of the grease, keep the soap fiber molecules from being destroyed, and effectively prevent the grease from leaking under high temperature conditions; at the same time, the formation of the complex can provide additional crosslinking points and intermolecular interactions, thereby enhancing the viscosity of the grease, improving its mechanical strength and high-temperature stability, and thus enabling the grease to have excellent friction reduction and anti-wear properties in a wider temperature range. The grease provided by the present invention is suitable for transmission equipment such as metal processing and railway transportation, and can effectively overcome the problems of increased wear of transmission parts at high temperatures, which is conducive to extending the service life of the equipment and achieving the purpose of green environmental protection, safety and health. The results of the embodiments show that the lubricating grease provided by the present invention has a low friction coefficient and excellent wear resistance within the range of 30 to 150°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1The transmission electron microscopy image and mapping element analysis image of the grease soap structure obtained in Experiment 3 of Example 1;

[0031] Figure 2 This is the XPS curve of each element in the grease soap structure obtained in Experiment 3 of Example 1;

[0032] Figure 3 Shear viscosity curves at 25°C for the base grease and the greases with 3.0%, 5.0%, 10.0%, 15% and 20% lithium bis(trifluoromethanesulfonyl)imide contents in Example 1;

[0033] Figure 4 The friction coefficient curve test results of the greases prepared in Example 1 with 1.0%, 3.0%, 5.0% and 10.0% lithium bis(trifluoromethanesulfonyl)imide contents at 30°C are shown;

[0034] Figure 5 The friction coefficient curve test results of the grease prepared in Example 1 with 1.0%, 3.0%, 5.0% and 10.0% lithium bis(trifluoromethanesulfonyl)imide contents at 100°C;

[0035] Figure 6 The friction coefficient curve test results of the greases prepared in Example 1 with bis(trifluoromethanesulfonyl)imide lithium contents of 1.0%, 3.0%, 5.0% and 10.0% at 150°C;

[0036] Figure 7 The friction coefficient curve of the grease obtained in Examples 2 to 4 at 150°C;

[0037] Figure 8 The friction coefficient curve of the grease obtained in Examples 5 to 7 at 150°C;

[0038] Fig. 9 The friction coefficient curve of the grease obtained in Comparative Examples 1 to 3 at 150°C;

[0039] Fig.10 Wear volume test results of greases prepared in Example 1 with lithium bis(trifluoromethanesulfonyl)imide contents of 1.0%, 3.0%, 5.0% and 10.0% at 30°C;

[0040] Fig.11 Wear volume test results of greases prepared in Example 1 with lithium bis(trifluoromethanesulfonyl)imide contents of 1.0%, 3.0%, 5.0% and 10.0% at 100°C;

[0041] Fig.12Wear volume test results of greases prepared in Example 1 with lithium bis(trifluoromethanesulfonyl)imide contents of 1.0%, 3.0%, 5.0% and 10.0% at 150°C. DETAILED DESCRIPTION

[0042] The present invention provides a lubricating grease, comprising the following components by mass fraction: 70-94% base oil, 5-15% thickener, and 1-15% additive;

[0043] The base oil includes one or more of mineral oil, hydrocarbon oil and ester oil;

[0044] The thickener includes a soap-based thickener and / or a non-soap-based thickener; the non-soap-based thickener includes a polyurea thickener and / or an inorganic thickener;

[0045] The additive is a lithium salt.

[0046] Unless otherwise specified, all components / raw materials used in the present invention are commercially available.

[0047] The grease provided by the present invention comprises 65-94% of base oil, preferably 78-92% by mass; the base oil comprises one or more of mineral oil, hydrocarbon oil and ester oil; the kinematic viscosity of the base oil at 40°C is preferably 28 mm 2 / s~62mm 2 / s; the mineral oil preferably includes one or more of 150N, 150SN and 300N, more preferably 150N; the hydrocarbon oil preferably includes one or more of polyalphaolefins, alkane oils, cycloalkane oils and aromatic oils, more preferably polyalphaolefins; the ester oil preferably includes one or more of trimethylolpropane oleate, dipentaerythritol ester and glycol fatty acid ester, more preferably trimethylolpropane oleate.

[0048] In terms of mass fraction, the grease provided by the present invention comprises 5-15% of a thickener, preferably 7-12%; the thickener preferably comprises a soap-based thickener and / or a non-soap-based thickener; the non-soap-based thickener preferably comprises a polyurea thickener and / or an inorganic thickener; the polyurea thickener is preferably obtained by reacting a monoamine, a diamine and a diisocyanate; the monoamine preferably comprises one or more of octadecylamine, monoethanolamine, aniline, piperazine and isobutylamide, more preferably octadecylamine; the diamine preferably comprises one or more of ethylenediamine, p-phenylenediamine and 4,4'-methylenedianiline, More preferably, it is 4,4-methylenedianiline; the diisocyanate preferably includes one or more of toluene diisocyanate, methane diisocyanate, 1,6-hexamethylene diisocyanate and 4,4'-diphenylmethane diisocyanate, more preferably toluene diisocyanate; in the present invention, when the thickener is a polyurea thickener, the grease is a urea-based grease; when the thickener is a polyurea thickener, the mass fraction of the thickener in the grease is based on the total mass fraction of the raw materials used to prepare the thickener (i.e., the total mass fraction of the monoamine, diamine and diisocyanate in the grease).

[0049] In the present invention, the inorganic thickener preferably includes one or more of bentonite, silicon dioxide, attapulgite, aluminum silicate and boron nitride, more preferably bentonite; the soap-based thickener is specifically a metal soap, preferably including one or more of lithium soap, calcium soap, aluminum soap and barium soap; the lithium soap is specifically lithium hydroxide, the calcium soap is specifically calcium hydroxide, the aluminum soap is specifically aluminum hydroxide, and the barium soap is specifically barium hydroxide.

[0050] In terms of mass fraction, the grease provided by the present invention includes 1 to 20% of additives, preferably 1.0%, 3.0%, 5.0%, 10.0%, 15% or 20%; the lithium salt preferably includes one or more of butyl lithium, phenyl lithium, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate and lithium hexafluorophosphate, more preferably lithium bis(trifluoromethanesulfonyl)imide.

[0051] The present invention also provides a method for preparing the grease described in the above scheme, comprising the following steps:

[0052] dissolving a thickener or a raw material for preparing the thickener in the first part of the base oil to obtain a solution;

[0053] The dissolving liquid and a second part of base oil are mixed and then heat treated to obtain a heat-treated liquid;

[0054] The heat-treated liquid, additives and remaining base oil are mixed, and the resulting mixed liquid is ground to obtain the grease.

[0055] The present invention dissolves a thickener or a raw material for preparing the thickener in a first part of base oil to obtain a solution. In the present invention, when the thickener is an inorganic thickener or a soap-based thickener, it is preferred to directly dissolve the inorganic thickener or soap-based thickener in the first part of base oil; when the thickener is a polyurea thickener, specifically, the raw materials for preparing the polyurea thickener (i.e., monoamine, diamine and diisocyanate) are dissolved in the first part of base oil; the dissolution temperature is preferably 110-125°C, more preferably 115-120°C; the dissolution is preferably carried out under stirring conditions; the first part of base oil is preferably 35-40% of the total mass of the base oil.

[0056] After obtaining the dissolved liquid, the present invention mixes the dissolved liquid with the second part of the base oil and then performs heat treatment to obtain a heat-treated liquid. In the present invention, the temperature of the mixture of the dissolved liquid and the second part of the base oil is preferably 130-150°C, more preferably 140°C; the second part of the base oil is preferably 25-30% of the total mass of the base oil; in a specific embodiment of the present invention, preferably after the dissolution is completed, the temperature of the obtained dissolved liquid is raised to 130-150°C, and then the second part of the base oil is added.

[0057] In the present invention, the temperature of the heat treatment is preferably 210-220°C, and the time is preferably 10-20 minutes. During the heat treatment process, a hydrogen bond network is formed between the thickeners to construct a stable thickener skeleton to fix the base oil, thereby forming different types of greases. Taking the thickener as a polyurea thickener as an example, the ability of the polyurea thickener to form hydrogen bonds is significantly enhanced with increasing temperature. With increasing temperature, the number of hydrogen bonds between urea molecules will continue to increase. Then, under high temperature conditions, the urea molecules will change from a chaotic disordered structure to an ordered structure, forming a stable thickener skeleton structure through hydrogen bonds. Finally, under high temperature conditions, the base oil molecules are activated and fully absorbed into the spatial spiral tube to form a urea-based grease with tight bonding and excellent thermal stability.

[0058] After obtaining the heat treatment liquid, the present invention mixes the heat treatment liquid, the additive and the remaining base oil, and grinds the obtained mixed liquid to obtain the grease. In the present invention, the method of mixing the heat treatment liquid, the additive and the remaining base oil preferably includes: lowering the temperature of the heat treatment liquid to 180-190°C, then adding the additive and the remaining base oil, continuing to stir until the temperature drops to 60-100°C, preferably to 80°C, and then naturally cooling to room temperature; the present invention has no special requirements for the grinding method, and a method well known to those skilled in the art can be used.

[0059] The present invention also provides the use of the grease described in the above scheme or the grease prepared by the preparation method described in the above scheme in transmission equipment; the transmission equipment is preferably metal processing equipment or railway transportation equipment.

[0060] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions 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.

[0061] Example 1

[0062] The mass fractions of the various components in the grease of this embodiment are shown in Table 1.

[0063] Table 1 Ratio of each component in grease

[0064] project Thickener additive Base oil Comparative experiment 1 11％ 0 margin Experiment 1 11％ 1％ margin Experiment 2 11％ 3％ margin Experiment 3 11％ 5％ margin Experiment 4 11％ 10％ margin Experiment 5 11％ 15％ margin Experiment 6 11％ 20％ margin

[0065] Among them, the thickener is a polyurea thickener, and the mass fraction of the thickener is calculated based on the total mass fraction of the raw materials used to prepare the thickener. The mass fractions of the raw materials are as follows: 2.5% octadecylamine, 3.3% 4,4'-methylenedianiline, and 5.2% toluene diisocyanate; the additive is lithium bis(trifluoromethanesulfonyl)imide, and the base oil is polyalphaolefin; the grease obtained in comparative experiment 1 is recorded as the base grease.

[0066] The preparation method of grease is as follows:

[0067] (1) Octadecylamine, 4,4'-methylenedianiline, toluene diisocyanate and 35% poly-alpha-olefin were added to a stainless steel reactor and mixed evenly, and the mixture was heated to 120° C. and stirred to dissolve;

[0068] (2) heating to 140° C. and adding 25% polyalphaolefin as diluent oil;

[0069] (3) Raise the temperature to 220°C, keep the reaction constant for 10 min, and then stop heating;

[0070] (4) When the temperature drops to 180°C, add lithium bis(trifluoromethanesulfonyl)imide and the remaining polyalphaolefin as cooling oil, continue stirring until the temperature reaches 80°C, and then take out;

[0071] (5) After the temperature cools naturally to room temperature, grind to obtain grease.

[0072] Example 2

[0073] The mass fractions of the components in the grease of this embodiment are: 11% thickener (including 2.5% octadecylamine, 3.3% 4,4'-methylenedianiline, 5.2% toluene diisocyanate), 5% lithium bis(trifluoromethanesulfonyl)imide, and the balance liquid paraffin.

[0074] The preparation method of the grease is the same as that of Example 1.

[0075] Example 3

[0076] The mass fractions of the various components in the grease of this embodiment are: 11% thickener (lithium hydroxide), 5% lithium bis(trifluoromethanesulfonyl)imide, and the balance is trimethylolpropane oleate.

[0077] The preparation method of the grease is the same as that of Example 1.

[0078] Example 4

[0079] The mass fractions of the components in the grease of this embodiment are: 7% thickener (lithium hydroxide), 10% lithium bis(trifluoromethanesulfonyl)imide, and the balance is trimethylolpropane oleate.

[0080] The preparation method of the grease is the same as that of Example 1.

[0081] Example 5

[0082] The other conditions were the same as those of Experiment 3 in Example 1, except that lithium bis(trifluoromethanesulfonyl)imide was replaced by lithium tetrafluoroborate.

[0083] Example 6

[0084] The other conditions were the same as those of Experiment 3 in Example 1, except that lithium bis(trifluoromethanesulfonyl)imide was replaced by lithium hexafluorophosphate.

[0085] Example 7

[0086] The other conditions were the same as those of Experiment 3 in Example 1, except that lithium bis(trifluoromethanesulfonyl)imide was replaced by butyl lithium.

[0087] Comparative Example 1

[0088] The other conditions were the same as those of Experiment 3 in Example 1, except that lithium bis(trifluoromethanesulfonyl)imide was replaced by nano-calcium carbonate.

[0089] Comparative Example 2

[0090] The other conditions were the same as those of Experiment 3 in Example 1, except that lithium bis(trifluoromethanesulfonyl)imide was replaced by hexagonal boron nitride.

[0091] Comparative Example 3

[0092] The other conditions were the same as those of Experiment 3 in Example 1, except that lithium bis(trifluoromethanesulfonyl)imide was replaced by talc.

[0093] Characterization and testing

[0094] 1. Transmission electron microscope test and mapping element analysis

[0095] The soap structure obtained after washing the grease obtained in Experiment 3 of Example 1 was subjected to transmission electron microscopy test and mapping element analysis. The results are as follows: Figure 1 As shown. Figure 1 It can be seen that the soap contains C, N, F, S, and O elements, and the element distribution is consistent with the soap structure, indicating that lithium bis(trifluoromethanesulfonyl)imide is completely complexed with the thickener.

[0096] 2. XPS test

[0097] Figure 2 This is the XPS curve of each element in the grease soap structure obtained in Experiment 3 of Example 1. Figure 2 It can be seen that each element in the soap structure has obvious characteristic peaks, indicating that the soap contains elements such as F.

[0098] 3. Shear viscosity test

[0099] Figure 3 Shear viscosity curves at 25°C for the base grease and the greases with 3.0%, 5.0%, 10.0%, 15% and 20% lithium bis(trifluoromethanesulfonyl)imide contents in Example 1. Figure 3 It can be seen that the viscosity of the grease increases with the increase of the content of lithium bis(trifluoromethanesulfonyl)imide, indicating that the addition of lithium bis(trifluoromethanesulfonyl)imide can enhance the grease soap fiber structure, enhance the oil storage capacity of the grease and thus improve its lubrication ability.

[0100] 4. Friction coefficient test

[0101] The SRV-IV micro-motion friction and wear tester produced by Optimol Grease of Germany was used to test the friction coefficient f of the base grease prepared in Example 1 and the grease with 1.0%, 3.0%, 5.0% and 10.0% lithium bis(trifluoromethanesulfonyl)imide content at 30°C, frequency 25Hz, load 200N, and long grinding for 30min. The steel ball used in the test was GCr15 bearing steel with a diameter of 10mm, and the lower sample was a GCr15 steel block with a size of 24×7.9mm. The results are shown in Figure 4 .Depend on Figure 4 It can be seen that when the addition amount of lithium bis(trifluoromethanesulfonyl)imide is 1.0%, 3.0%, 5.0% and 10.0%, the friction coefficient of the grease at 30°C can be significantly reduced.

[0102] The friction coefficient f of the base grease prepared in Example 1 and the grease containing 1.0%, 3.0%, 5.0% and 10.0% lithium bis(trifluoromethanesulfonyl)imide was tested by SRV-IV micro-motion friction and wear tester produced by Optimol Oil Company of Germany at 100°C, 25Hz frequency and 200N load for 30min. The steel ball used in the test was GCr15 bearing steel with a diameter of 10mm, and the lower sample was a GCr15 steel block with a size of 24×7.9mm. The results are shown in Figure 5 .Depend on Figure 5 It can be seen that when the addition amount of lithium bis(trifluoromethanesulfonyl)imide is 1.0%, 3.0%, 5.0% and 10.0%, the friction coefficient of the grease at 100°C can be significantly reduced.

[0103] The friction coefficient f of the base grease prepared in Example 1 and the grease with 1.0%, 3.0%, 5.0% and 10.0% lithium bis(trifluoromethanesulfonyl)imide content was tested by using the SRV-IV micro-motion friction and wear tester produced by Optimol Oil Company of Germany at 150°C, 25Hz frequency and 200N load for 30min. The steel ball used in the test was GCr15 bearing steel with a diameter of 10mm, and the lower sample was a GCr15 steel block with a size of 24×7.9mm. The results are shown in Figure 6 .Depend on Figure 6 It can be seen that when the addition amount of lithium bis(trifluoromethanesulfonyl)imide is 1.0%, 3.0%, 5.0% and 10.0%, the friction coefficient of the grease at 150°C can be significantly reduced.

[0104] The same method was used to test the friction coefficient curves of the greases obtained in Examples 2 to 4 at 150°C and compared them with the friction coefficient curves of the greases obtained in Experiment 3 in Example 1. The results are shown in FIG. Figure 7 .according to Figure 7 It can be seen that the greases obtained in Examples 2 to 4 also have a certain friction reduction effect.

[0105] The same method was used to test the friction coefficient curves of the greases obtained in Examples 5 to 7 at 150°C and compared with the friction coefficient curve of the grease obtained in Experiment 3 in Example 1. The results are shown in FIG. Figure 8 .according to Figure 8 It can be seen that the addition of bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, lithium hexafluorophosphate and butyl lithium can all reduce the friction dilution of the grease, among which bis(trifluoromethanesulfonyl)imide has the best effect.

[0106] The same method was used to test the friction coefficient curves of the greases obtained in Comparative Examples 1 to 3 at 150°C, and compared with the friction coefficient curve of the grease obtained in Experiment 3 of Example 1. The results are shown in FIG. Fig. 9 .according to Fig. 9 It can be seen that the friction reduction effect of the greases obtained in Comparative Examples 1 to 3 is poor and the friction coefficient is unstable.

[0107] 5. Wear test

[0108] The wear volume of the wear spot of the base grease prepared in Example 1 and the grease with 1.0%, 3.0%, 5.0% and 10.0% lithium bis(trifluoromethanesulfonyl)imide content was tested by using MicroXAM 3D non-contact surface tester under the conditions of temperature 30°C, frequency 25Hz, stroke 1mm, load 200N, and long wear for 30min. The results are as follows: Fig.10 shown. Fig.10 The results show that when the addition amount of lithium bis(trifluoromethanesulfonyl)imide is 1.0%, 3.0%, 5.0% and 10.0%, the anti-wear performance of grease at 30°C can be significantly increased.

[0109] The wear volume of the wear spot of the base grease prepared in Example 1 and the grease with 1.0%, 3.0%, 5.0% and 10.0% lithium bis(trifluoromethanesulfonyl)imide content was tested by using MicroXAM 3D non-contact surface tester under the conditions of temperature 100°C, frequency 25Hz, stroke 1mm, load 200N, and long wear for 30min. The results are as follows: Fig.11 shown. Fig.11 The results show that when the addition amount of lithium bis(trifluoromethanesulfonyl)imide is 1.0%, 3.0%, 5.0% and 10.0%, the anti-wear performance of grease at 100°C can be significantly increased.

[0110] The wear volume of the wear spot of the base grease prepared in Example 1 and the grease with 1.0%, 3.0%, 5.0% and 10.0% lithium bis(trifluoromethanesulfonyl)imide content was tested by using MicroXAM 3D non-contact surface tester under the conditions of temperature 150°C, frequency 25Hz, stroke 1mm, load 200N, and long wear for 30min. The results are as follows: Fig.12 shown. Fig.12 The results show that when the addition amount of lithium bis(trifluoromethanesulfonyl)imide is 1.0%, 3.0%, 5.0% and 10.0%, the anti-wear performance of grease at 150°C can be significantly increased.

[0111] The results of the above embodiments show that the new urea-based grease composition provided by the present invention has excellent friction reduction and anti-wear properties, is suitable for transmission equipment such as metal processing and railway transportation, and effectively overcomes the problems of increased wear of transmission parts at high temperatures, which is beneficial to prolonging the service life of the equipment and achieving the purpose of green, environmental protection, safety and health.

[0112] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A lubricating grease, characterized in that: The composition comprises the following components by mass fraction: base oil 65-94%, thickener 5-15%, additive 1-20%; The base oil includes one or more of mineral oil, hydrocarbon oil and ester oil; The thickener includes a soap-based thickener and / or a non-soap-based thickener; the non-soap-based thickener includes a polyurea thickener and / or an inorganic thickener; The additive is a lithium salt.

2. The lubricating grease according to claim 1, characterized in that The lithium salt includes one or more of butyl lithium, phenyl lithium, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, and lithium hexafluorophosphate.

3. The lubricating grease according to claim 1, characterized in that: The kinematic viscosity of the base oil at 40°C is 28 mm 2 / s~62mm 2 / s.

4. The lubricating grease according to claim 3, characterized in that: The mineral oil includes one or more of 150N, 150SN and 300N; The hydrocarbon oil includes one or more of polyalphaolefins, alkane oils, cyclohexane oils and aromatic oils; The ester oil includes one or more of trimethylolpropane oleate, dipentaerythritol ester and glycol fatty acid ester.

5. The lubricating grease according to claim 1, characterized in that: The polyurea thickener is obtained by reacting a monoamine, a diamine and a diisocyanate; when the thickener is a polyurea thickener, the mass fraction of the thickener in the grease is calculated based on the total mass fraction of the raw materials used to prepare the thickener; The monoamine includes one or more of octadecylamine, monoethanolamine, aniline, piperazine and isobutylamide; the diamine includes one or more of ethylenediamine, p-phenylenediamine and 4,4'-methylenedianiline; the diisocyanate includes one or more of toluene diisocyanate, methane diisocyanate, 1,6-hexamethylene diisocyanate and 4,4'-diphenylmethane diisocyanate.

6. The lubricating grease according to claim 1, characterized in that: The inorganic thickener includes one or more of bentonite, silicon dioxide, attapulgite, aluminum silicate and boron nitride; The soap-based thickener includes one or more of lithium soap, calcium soap, aluminum soap and barium soap.

7. The method for preparing the lubricating grease according to any one of claims 1 to 6, characterized in that: The following steps are involved: dissolving a thickener or a raw material for preparing the thickener in the first part of the base oil to obtain a solution; The dissolving liquid and a second part of base oil are mixed and then heat treated to obtain a heat-treated liquid; The heat-treated liquid, additives and remaining base oil are mixed, and the resulting mixed liquid is ground to obtain the grease.

8. The preparation method according to claim 7, characterized in that: The dissolving temperature is 110-125°C; The temperature of the mixture of the dissolving liquid and the second part of the base oil is 130-150°C; The heat treatment temperature is 210-220° C. and the time is 10-20 min.

9. The preparation method according to claim 7, characterized in that: The method of mixing the heat treatment liquid, the additive and the remaining base oil includes: lowering the temperature of the heat treatment liquid to 180-190° C., then adding the additive and the remaining base oil, continuing to stir until the temperature drops to 60-100° C., and then naturally cooling to room temperature.

10. Use of the grease according to any one of claims 1 to 6 or the grease prepared by the preparation method according to any one of claims 7 to 9 in transmission equipment.

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