Process for preparing perfluoropolyether-type grease and perfluoropolyether-type grease

Abstract

This invention discloses a method for preparing perfluoropolyether grease and the perfluoropolyether grease itself. The preparation method includes the following steps: heating and stirring perfluoropolyether oil, a first thickener, and additives, followed by ultrasonic treatment to form pre-soap A; adding a second thickener, and mixing by heating, stirring, and ultrasonication to form pre-soap B; adding a third thickener, and mixing by heating, stirring, and ultrasonication to form pre-soap C; adding solvent to pre-soap C to obtain a mixture, cooling it, and then performing vacuum degassing to obtain an oil paste mixture; grinding the oil paste mixture to obtain the perfluoropolyether grease. This invention, through a batch thickening process, adds the thickener in stages, resulting in a perfluoropolyether grease colloid with good stability, significantly improved anti-wear properties, and noise reduction capabilities.

Description

Technical Field

[0001] This invention relates to the field of lubricating materials technology, specifically to a method for preparing a perfluoropolyether type lubricating grease and the perfluoropolyether type lubricating grease itself. Background Technology

[0002] With the rapid development of science and technology and the economy, industrial equipment is constantly being upgraded, and various industries are placing higher demands on reducing bearing noise. Factors affecting rolling bearing noise include the bearing's own structural design, materials, and processing technology, as well as the matching lubricating grease. Increasingly mature bearing structural designs and higher bearing processing precision result in lower noise levels from the bearings themselves; therefore, improving the matching lubricating grease has become a crucial factor in reducing bearing noise.

[0003] Perfluoropolyether greases, due to their long lifespan, excellent high-temperature stability, and chemical inertness, are commonly used in bearings of certain high-end or specialized equipment, such as office automation equipment, home appliances, and military equipment. To further improve environmental quality, modern manufacturing has placed higher demands on the noise reduction performance of bearings, making the noise reduction capability of perfluoropolyether greases a hot topic in the manufacturing industry. Perfluoropolyether greases are mainly prepared from perfluoropolyether oil, fluorinated polymeric thickeners, and special additives. Research has found that perfluoropolyether greases have poor anti-wear properties and less than ideal lubrication performance, resulting in relatively high noise levels in equipment. Factors such as the thickener, base oil, additives, and preparation process of the grease all have varying degrees of influence on noise levels.

[0004] Currently, noise reduction in perfluoropolyether greases is often achieved by adding anti-wear additives. Patent document CN201410728148.7 describes a grease that can be used in low-temperature and vacuum environments. This grease can reduce noise during low-temperature operation, but its coefficient of friction is relatively high, and the anti-wear modification effect is not significant. CN201611256942.1 specifically relates to a high-temperature resistant perfluoropolyether grease that can provide long-term lubrication at temperatures above 300°C and exhibits low noise at low temperatures. However, the additive used is a K-type perfluoropolyether derivative, making the synthesis process relatively complex. CN202110969438.0 describes a method for preparing extreme-pressure anti-wear perfluoropolyether grease and the grease itself. The prepared extreme-pressure anti-wear perfluoropolyether grease has good extreme-pressure anti-wear performance. However, surface modification of the extreme-pressure anti-wear additives is required, making the improvement process relatively complex.

[0005] Therefore, there is an urgent need for a perfluoropolyether type grease with excellent anti-friction properties and a simple and easy-to-operate preparation method. Summary of the Invention

[0006] The purpose of this invention is to address the performance problems of existing perfluoropolyether greases by providing a method for preparing perfluoropolyether grease and a perfluoropolyether grease itself. The method for preparing perfluoropolyether grease provided by this invention changes the way the thickener is added by using a stepwise addition of different types of thickeners, resulting in a perfluoropolyether grease with good stability, excellent anti-friction performance and noise reduction capability. Furthermore, the preparation process is simple and easy to implement.

[0007] To solve the above-mentioned technical problems, the first aspect of the present invention provides a method for preparing a perfluoropolyether type lubricating grease, comprising the following steps: (1) heating and stirring a perfluoropolyether oil, a first thickener, and an additive, and then subjecting the mixture to ultrasonic treatment to form a pre-made soap A; (2) adding a second thickener to the pre-made soap A, and then heating, stirring, and ultrasonically mixing to form a pre-made soap B; (3) adding a third thickener to the pre-made soap B, and then heating, stirring, and ultrasonically mixing to form a pre-made soap C; (4) adding a solvent to the pre-made soap C to obtain a mixture, and then subjecting the mixture to vacuum degassing treatment after cooling to obtain an oil paste mixture; (5) grinding the oil paste mixture to obtain the perfluoropolyether type lubricating grease.

[0008] Wherein, the first thickener and the third thickener may be the same or different, and each is independently selected from one or more of polytetrafluoroethylene, trifluorochloroethylene-polyethylene copolymer, and tetrafluoroethylene-hexafluoropropylene copolymer;

[0009] The second thickener is selected from one or more of nano boron nitride particles, nano calcium fluoride particles, and nano aluminum nitride particles.

[0010] This invention introduces a first thickener, a second thickener, and a third thickener in batches using a thickening process. The second thickener is different from the first thickener added earlier and the third thickener added later. This method of thickening improves the dispersibility and compatibility of the second thickener in the perfluoropolyether oil. The second thickener binds well with the perfluoropolyether oil and is less prone to precipitation. The resulting perfluoropolyether grease has good stability and significantly improved anti-wear and noise reduction capabilities.

[0011] In some embodiments of the present invention, the molar ratio of the first thickener, the second thickener and the third thickener is 1:(0.5-3):(0.8-5); preferably 1:(0.8-1.5):(1-3).

[0012] This invention improves the dispersibility and compatibility of the thickeners in perfluoropolyether oil by further controlling the molar ratio of the first thickener, the second thickener, and the third thickener. The resulting perfluoropolyether grease has good stability and further improved anti-wear and noise reduction capabilities.

[0013] The additives suitable for use in this invention include, but are not limited to, one or more of the following: nano calcium carbonate, nano titanium dioxide, nano aluminum oxide, nano silicon dioxide, molybdenum disulfide, alkyl molybdenum thiophosphate, and dialkyl dithiocarbamate.

[0014] In some embodiments of the present invention, the additive includes a first additive and a second additive, wherein the mass ratio of the first additive to the second additive is (1-3):1;

[0015] The first additive is selected from one or more of nano-calcium carbonate, nano-titanium dioxide, nano-alumina, and nano-silica; the second additive is selected from one or more of molybdenum disulfide, alkylmolybdenum thiophosphate, and dialkyldithiocarbamate.

[0016] In this invention, by selecting suitable first and second additives and adjusting their proportions, the synergistic effect of the first and second additives significantly improves the anti-wear performance and noise reduction capability of perfluoropolyether grease. Furthermore, the selection of the first additive facilitates the formation of a network structure in the perfluoropolyether oil, enhancing the structural strength and colloidal stability of the perfluoropolyether grease.

[0017] In some embodiments of the present invention, the solvent is selected from one or more of petroleum ether, hydrofluoroether solvent, perfluoroamine solvent, and polyhexafluoropropylene solvent.

[0018] This invention employs a rapid cooling process, using only volatile solvents to enhance the additives' ability to improve the structure of perfluoropolyether greases, thereby increasing their structural strength and colloidal stability, particularly their high-temperature stability. This significantly improves their anti-wear and noise reduction capabilities. By selecting suitable solvents, the dispersibility of thickeners and additives is improved, preventing agglomeration. The improved flowability of the additives enhances the anti-wear and noise reduction capabilities of the perfluoropolyether grease, further improving its structural improvement ability. This facilitates the formation of a network structure within the perfluoropolyether oil, and the improved dispersion of the thickener enhances the structural strength and colloidal stability of the grease, especially its high-temperature stability, thus further improving its noise reduction capabilities. Furthermore, the use of these volatile solvents also facilitates the degassing process.

[0019] In some embodiments of the present invention, the average particle size of the first thickener and the third thickener is 0.01 to 100 μm; preferably 20 to 50 μm.

[0020] In some embodiments of the present invention, the average particle size of the second thickener is 30-200 nm.

[0021] In some embodiments of the present invention, the weight-average molecular weight of the first thickener and the third thickener is independently 1,000 to 10,000; preferably 5,000 to 8,000.

[0022] In some embodiments of the present invention, the total stirring time in steps (1) to (3) is 4 to 6 hours, the stirring speed is 1000 r / min to 3000 r / min, and the stirring temperature is 50 to 100°C; the ultrasound is water bath ultrasound, the ultrasound temperature is 50 to 70°C, and the total ultrasound time is 4 to 6 hours.

[0023] In some embodiments of the present invention, the stirring time in step (1) is 60 to 120 min; the stirring time in step (2) is 90 to 120 min; and the stirring time in step (3) is 90 to 120 min.

[0024] In some embodiments of the present invention, the ultrasonic treatment time in step (1) is 90 to 120 min; the ultrasonic mixing time in step (2) is 90 to 120 min; and the ultrasonic mixing time in step (3) is 60 to 90 min.

[0025] In some embodiments of the present invention, in step (4), the conditions for the vacuum degassing treatment include: a degassing temperature of room temperature, a degassing time of 4 to 6 hours, and a vacuum degree of 0.1 to 10 kPa.

[0026] In some embodiments of the present invention, the perfluoropolyether grease comprises, based on 100 wt%, the perfluoropolyether grease as follows:

[0027] Perfluoropolyether oil 55-85 wt%, preferably 60-75 wt%;

[0028] The first thickener, the second thickener, and the third thickener are 10-40 wt%, preferably 24-39 wt%;

[0029] The additive is 0.1 wt% to 5 wt%, preferably 2 wt% to 4 wt%.

[0030] In some embodiments of the present invention, the perfluoropolyether oil is a branched perfluoropolyether base oil with the chemical formula CF3-O-(CF2CF(CF3)O). m -(CF2O) n -CF3, where m and n are integers between 1 and 500, preferably 100-300, and 1≤m / n≤3.

[0031] In some embodiments of the present invention, the kinematic viscosity of the perfluoropolyether oil at 40°C is 0–800 cSt, preferably 500–800 cSt.

[0032] In some embodiments of the present invention, the kinematic viscosity of the perfluoropolyether oil at 40°C is 10 to 100 cSt.

[0033] A second aspect of the present invention provides a perfluoropolyether type grease, wherein the perfluoropolyether type grease is prepared by the above-described preparation method.

[0034] Beneficial effects:

[0035] (1) The present invention adds a first thickener, a second thickener and a third thickener in batches through a thickening process. The type of the second thickener is different from the first thickener added first and the third thickener added later. The above-mentioned method of adding thickener improves the dispersibility and compatibility of the second thickener in perfluoropolyether oil. The second thickener combines well with perfluoropolyether oil and is not easy to precipitate. The resulting perfluoropolyether type lubricating grease colloid has good stability and significantly improved anti-wear and noise reduction capabilities.

[0036] (2) The perfluoropolyether grease of the present invention has excellent thermal stability and is suitable for some harsh working conditions; the grease preparation method of the present invention is simple and easy to operate and is suitable for industrial production. Detailed Implementation

[0037] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified, specific conditions in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the materials used in the embodiments are commercially available products or conventional products that can be synthesized by known methods.

[0038] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0039] The reagents used in this invention are mainly sourced from the following sources:

[0040] Perfluoropolyether oil (i.e., perfluoropolyether base oil) has the chemical formula [formula missing], where m and n are 55 and 50 respectively, and the molecular weight is 12615 g / mol. It is produced by Sinopec Lubricating Oil Company Beijing Branch. The kinematic viscosity of the perfluoropolyether oil at 40℃ is 600 cSt.

[0041] Polytetrafluoroethylene (PTFE), PTFE New Materials (Suzhou) Co., Ltd., particle size 0.5–50 μm, preferably 20–30 μm.

[0042] Trichlorofluoroethylene-polyethylene copolymer, Dongguan Bolin, particle size 10-100μm, preferably 10-50μm.

[0043] Tetrafluoroethylene-hexafluoropropylene copolymer, Shandong Dongyue Shenzhou, 99% purity, particle size 0.01-10μm, preferably 0.01-0.1μm.

[0044] Nano-sized boron nitride particles, Suzhou Napo Materials Technology Co., Ltd., with a particle size of 50nm.

[0045] Nano-sized calcium fluoride particles, Jiangsu Xianfeng Nanomaterials Technology, with a particle size of 30nm.

[0046] Nano-sized aluminum nitride particles, Bohuas Nanotechnology (Ningbo), particle size 40nm.

[0047] Nano-calcium carbonate, Shanghai Maclean Biochemical, particle size 50nm.

[0048] Nano titanium dioxide, Sigma-Aldrich (Shanghai), particle size 25nm.

[0049] Nano-alumina, Hubei Huifu Nanomaterials, particle size 50nm.

[0050] Silica, Jinan Qingtian Chemical, particle size 20μm.

[0051] Molybdenum disulfide, Dingqiannuo, particle size 2000 mesh, purity 99%.

[0052] Alkyl molybdenum thiophosphate, Luoyang Tongrun Nanotechnology Co., Ltd.

[0053] Dialkyl dithiocarbamate, Hunan Fucheng Environmental Protection Technology Co., Ltd.

[0054] The main testing methods used in this invention are:

[0055] The performance of the samples prepared in each embodiment and comparative example was compared through performance testing. Specific test items included: grease penetration to 1 / 4 working cone, grease separation on the stencil, evaporation rate, wear scar diameter, coefficient of friction, and noise. The testing process employed the following methods:

[0056] (1) The 1 / 4 working cone penetration test of grease refers to the standard GB / T 3498-2008;

[0057] (2) The oil separation test of steel mesh should refer to the standard SH / T 0324;

[0058] (3) Evaporation test reference standard SH / T 0337;

[0059] (4) The test of grease wear scar diameter and friction coefficient shall refer to standard SH / T0204;

[0060] (5) Noise reference standard GB / T32333, test temperature 150℃.

[0061] In the above tests, the oil separation on the stencil indicates the colloidal stability of the grease, the evaporation rate indicates the high temperature resistance of the grease, the wear scar diameter and coefficient of friction indicate the anti-friction and wear performance of the grease, and the noise indicates the noise reduction performance of the grease.

[0062] Example 1

[0063] Preparation method of perfluoropolyether grease

[0064] (1) Place 180g of perfluoropolyether oil, 37.8g of polytetrafluoroethylene (weight average molecular weight 8000), 3g of nano calcium carbonate and 3g of molybdenum disulfide in a mixer and stir for 1 hour at a temperature of 50°C and a speed of 1000r / min. The resulting mixture is then sonicated in a water bath sonicator at a temperature of 70°C for 30 minutes to form pre-made soap A.

[0065] (2) Add 0.2g of nano boron nitride particles to pre-made soap A, heat and stir at 50°C for 1h, stirring at 1000r / min, and then sonicate the mixture in a water bath sonicator at 70°C for 30min to form pre-made soap B.

[0066] (3) Add 38.1g of polytetrafluoroethylene (weight average molecular weight 8000) to pre-made soap B, continue heating and stirring at 50°C for 1h, stirring speed is 1000r / min, and the resulting mixture is ultrasonicated in a water bath ultrasonicator at 70°C for 30min to form pre-made soap C.

[0067] (4) Add 500 mL of hydrofluoric ether solvent to pre-made soap C quickly to obtain a mixture; after the mixture cools, place it in a vacuum chamber for degassing treatment for 5 h with a vacuum degree of 10 kPa to obtain an oil paste mixture.

[0068] (5) The oil mixture is placed in a three-roll mill and ground repeatedly three times to obtain perfluoropolyether grease.

[0069] Example 2

[0070] Preparation method of perfluoropolyether grease

[0071] (1) Place 189g of perfluoropolyether oil, 33g of trifluorochloroethylene-polyethylene copolymer (weight average molecular weight 6000), 6g of nano titanium dioxide, and 6g of alkyl thiophosphate molybdenum in a mixer and stir for 1h at a temperature of 60℃ and a speed of 2000r / min. The resulting mixture is then sonicated in a water bath sonicator at a temperature of 60℃ for 1h to form pre-made soap A.

[0072] (2) Add 0.5g of nano calcium fluoride particles to pre-made soap A, heat and stir at 60°C for 0.5h, stirring speed is 2000r / min, and the resulting mixture is ultrasonicated in a water bath ultrasonicator at 60°C for 30min to form pre-made soap B.

[0073] (3) Add 33g of trichlorotrifluoroethylene-polyethylene copolymer (weight average molecular weight 6000) to pre-made soap B, continue heating and stirring at 60°C for 1h, stirring speed 2000r / min, and the resulting mixture is ultrasonicated in a water bath ultrasonicator at 60°C for 30min to form pre-made soap C.

[0074] (4) Add 500 mL of perfluoroamine solvent to pre-made soap C quickly to obtain a mixture; after the mixture cools, place it in a vacuum chamber for 4 h for degassing treatment with a vacuum degree of 1 kPa to obtain an oil paste mixture.

[0075] (5) The oil mixture is placed in a three-roll mill and ground repeatedly three times to obtain perfluoropolyether grease.

[0076] Example 3

[0077] Preparation method of perfluoropolyether grease

[0078] (1) Place 210g of perfluoropolyether oil, 27g of polytetrafluoroethylene (weight average molecular weight 8000), 5g of silica, and 4g of dialkyl dithiocarbamate in a mixer and stir for 1 hour at a temperature of 100°C and a speed of 2500r / min. The resulting mixture is then sonicated in a water bath sonicator at a temperature of 70°C for 2 hours to form pre-made soap A.

[0079] (2) Add 0.2g of nano aluminum nitride particles to pre-made soap A, heat and stir at 100℃ for 1h, stirring speed is 2500r / min, and the resulting mixture is ultrasonicated in a water bath ultrasonicator at 70℃ for 1h to form pre-made soap B.

[0080] (3) Add 27g of polytetrafluoroethylene (weight average molecular weight 8000) to pre-made soap B, continue heating and stirring at 100℃ for 1h, stirring speed is 2500r / min, and the resulting mixture is ultrasonicated in a water bath ultrasonicator at 70℃ for 1h to form pre-made soap C.

[0081] (4) Add 500 mL of polyhexafluoropropylene solvent to pre-made soap C quickly to obtain a mixture; after the mixture cools, place it in a vacuum chamber for degassing treatment for 5 h with a vacuum degree of 0.1 kPa to obtain an oil paste mixture;

[0082] (5) The oil mixture is placed in a three-roll mill and ground repeatedly three times to obtain perfluoropolyether grease.

[0083] Example 4

[0084] Preparation method of perfluoropolyether grease

[0085] (1) 225g of perfluoropolyether oil, 21g of tetrafluoroethylene-hexafluoropropylene copolymer (weight average molecular weight 5000), 6g of nano alumina and 6g of dialkyl dithiocarbamate were placed in a mixer and stirred for 1 hour at a temperature of 80°C and a speed of 2000r / min. The resulting mixture was then sonicated in a water bath sonicator at a temperature of 70°C for 1.5 hours to form pre-made soap A.

[0086] (2) Add 0.3g of nano calcium fluoride particles to pre-made soap A, heat and stir at 80°C for 0.5h at a stirring speed of 2000r / min, and sonicate the resulting mixture in a water bath sonicator at a temperature of 70°C for 1.5h to form pre-made soap B.

[0087] (3) Add 21g of tetrafluoroethylene-hexafluoropropylene copolymer (weight average molecular weight 5000) to pre-made soap B, continue heating and stirring at 80°C for 1h, stirring speed is 2000r / min, and the resulting mixture is ultrasonicated in a water bath ultrasonicator at 70°C for 1.5h to form pre-made soap C.

[0088] (4) Add 500 mL of petroleum ether to pre-made soap C quickly to obtain a mixture; after the mixture cools, place it in a vacuum chamber for degassing treatment for 6 hours at a vacuum degree of 0.1 kPa to obtain an oil paste mixture;

[0089] (5) The oil mixture is placed in a three-roll mill and ground repeatedly three times to obtain perfluoropolyether grease.

[0090] Example 5

[0091] The perfluoropolyether grease was prepared according to the method described in Example 3, except that 4g of dialkyl dithiocarbamate was not added in step (1).

[0092] Example 6

[0093] The perfluoropolyether grease was prepared according to the method described in Example 3, except that 5g of silica was not added in step (1).

[0094] Example 7

[0095] The perfluoropolyether grease was prepared according to the method described in Example 3, except that in step (4), 500 mL of ethanol was used instead of 500 mL of polyhexafluoropropylene solvent.

[0096] Example 8

[0097] The perfluoropolyether grease was prepared according to the method described in Example 3, except that in step (2), 1.0 g of nano aluminum nitride particles were added to pre-made soap A.

[0098] Comparative Example 1

[0099] The perfluoropolyether grease was prepared according to the method described in Example 3, except that no volatile solvent was added in step (4).

[0100] Comparative Example 2

[0101] The perfluoropolyether grease was prepared according to the method described in Example 3, except that in step (1), the first thickener, the second thickener and the third thickener were added at once.

[0102] Comparative Example 3

[0103] The perfluoropolyether grease was prepared according to the method described in Example 3, except that in step (2), an equimolar amount of polytetrafluoroethylene was added instead of nano-aluminum nitride particles.

[0104] Comparative Example 4

[0105] The perfluoropolyether grease was prepared according to the method described in Example 3, except that the first thickener and the third thickener were added first, and the second thickener was added last. That is, after completing steps (1) and (3), step (2) was then performed.

[0106] The greases prepared in the above embodiments and comparative examples were subjected to performance tests according to the test methods. The test results are shown in Tables 1 and 2 below.

[0107] Table 1. Performance of the perfluoropolyether greases prepared in the examples.

[0108]

[0109] Table 2. Performance of the perfluoropolyether greases prepared in the comparative examples

[0110]

[0111]

[0112] Analysis of the test results in Table 1-2 above shows that:

[0113] (1) In Examples 1-8, a first thickener, a second thickener, and a third thickener were added in batches using a thickening process. The type of the second thickener was different from the first thickener added first and the third thickener added later. The addition method of the thickener improved the dispersibility and compatibility of the second thickener in the perfluoropolyether oil. The second thickener combined well with the perfluoropolyether oil and was not easy to precipitate. The resulting perfluoropolyether grease colloid had good stability, and its anti-wear and noise reduction capabilities were significantly improved (smaller wear scar diameter, lower coefficient of friction, and a large decrease in vibration value after the addition of perfluoropolyether grease). At the same time, a rapid cooling process was adopted, and a volatile solvent was added to enhance the ability of the additive to improve the structure of the perfluoropolyether grease, improve the structural strength and stability of the colloid, especially its high-temperature stability (lower oil separation rate on the steel mesh, lower evaporation loss rate), thereby greatly improving its anti-wear and noise reduction capabilities (smaller wear scar diameter, lower coefficient of friction, and a large decrease in vibration value after the addition of perfluoropolyether grease). Examples 5 and 6, with only one additive, showed a decrease in high-temperature stability and an increase in evaporation loss rate compared to Example 3; the wear scar diameter and coefficient of friction also increased; and the vibration value reduction was slightly reduced after adding the perfluoropolyether greases of Examples 5 and 6. Example 7 used the conventional solvent ethanol. Compared to Example 3, the high-temperature stability of the perfluoropolyether grease decreased, and the evaporation loss rate increased; the wear scar diameter and coefficient of friction also increased; and the vibration value reduction was slightly reduced after adding the perfluoropolyether grease of Example 7. Example 8 added a larger amount of the second thickener. Compared to Example 3, the high-temperature stability of the perfluoropolyether grease decreased, and the evaporation loss rate increased; the wear scar diameter and coefficient of friction also increased; and the vibration value reduction was slightly reduced after adding the perfluoropolyether grease of Example 8.

[0114] (2) Compared with Example 3, Comparative Example 1 did not add volatile solvents and did not use a rapid cooling process. The high-temperature stability of the perfluoropolyether grease decreased and the evaporation loss rate increased. The wear scar diameter and friction coefficient also increased. After adding the perfluoropolyether grease of Comparative Example 1, the vibration value decreased.

[0115] (3) Compared with Example 3, in step (1), the first thickener, the second thickener and the third thickener were added at once without being added in batches. The oil separation rate and evaporation loss rate of the steel mesh increased significantly, and the wear scar diameter and friction coefficient also increased significantly. After adding the perfluoropolyether grease of Comparative Example 2, the vibration value decreased significantly.

[0116] (4) Compared with Example 3, Comparative Example 3 added equimolar polytetrafluoroethylene instead of nano aluminum nitride particles, that is, no second thickener was added. The oil separation rate and evaporation loss rate of the steel mesh increased significantly, and the wear scar diameter and friction coefficient also increased significantly. After adding the perfluoropolyether grease of Comparative Example 3, the vibration value decreased significantly.

[0117] (5) Compared with Example 3, Comparative Example 4 first added the first thickener and the third thickener, and finally added the second thickener. That is, after completing the operations of steps (1) and (3), step (2) was carried out. The oil separation rate and evaporation loss rate of the steel mesh increased significantly, and the wear scar diameter and friction coefficient also increased significantly. After adding the perfluoropolyether grease of Comparative Example 4, the vibration value decreased significantly.

[0118] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing a perfluoropolyether-type lubricating grease, characterized in that, Includes the following steps: (1) After heating and stirring the perfluoropolyether oil, the first thickener and the additives, the mixture is subjected to ultrasonic treatment to form pre-made soap A; (2) The second thickener is added to the pre-made soap A, and the pre-made soap B is formed by heating, stirring and ultrasonic mixing. (3) Add the third thickener to the pre-made soap B, and mix it by heating, stirring and ultrasonication to form pre-made soap C; (4) Add the solvent to the pre-made soap C to obtain a mixture. After cooling, perform vacuum degassing to obtain an oil-oil mixture. (5) Grind the oil mixture to obtain the perfluoropolyether type grease; Wherein, the first thickener and the third thickener may be the same or different, and each is independently selected from one or more of polytetrafluoroethylene, trifluorochloroethylene-polyethylene copolymer, and tetrafluoroethylene-hexafluoropropylene copolymer; The second thickener is selected from one or more of nano boron nitride particles, nano calcium fluoride particles, and nano aluminum nitride particles.

2. The method for preparing perfluoropolyether-type lubricating grease according to claim 1, characterized in that, The molar ratio of the first thickener, the second thickener, and the third thickener is 1:(0.5-3):(0.8-5); preferably 1:(0.8-1.5):(1-3).

3. The method for preparing perfluoropolyether-type lubricating grease according to claim 1 or 2, characterized in that, The additives include a first additive and a second additive, wherein the mass ratio of the first additive to the second additive is (1-3):1; The first additive is selected from one or more of nano-calcium carbonate, nano-titanium dioxide, nano-alumina, and nano-silica; the second additive is selected from one or more of molybdenum disulfide, alkylmolybdenum thiophosphate, and dialkyldithiocarbamate.

4. The method for preparing the perfluoropolyether type lubricating grease according to any one of claims 1-3, characterized in that, The solvent is selected from one or more of petroleum ether, hydrofluoroether solvent, perfluoroamine solvent, and polyhexafluoropropylene solvent.

5. The method for preparing the perfluoropolyether-type lubricating grease according to any one of claims 1-4, characterized in that, The average particle size of the first thickener and the third thickener is independently 0.01–100 μm; preferably 20–50 μm. And / or, the average particle size of the second thickener is 30-200 nm.

6. The method for preparing the perfluoropolyether type lubricating grease according to any one of claims 1-5, characterized in that, The weight-average molecular weight of the first thickener and the third thickener is independently 1,000 to 10,000; preferably 5,000 to 8,000.

7. The method for preparing the perfluoropolyether type lubricating grease according to any one of claims 1-6, characterized in that, The total stirring time in steps (1) to (3) is 4 to 6 hours, the stirring speed is 1000 r / min to 3000 r / min, and the stirring temperature is 50 to 100°C; the ultrasound is water bath ultrasound, the ultrasound temperature is 50 to 70°C, and the total ultrasound time is 4 to 6 hours.

8. The method for preparing the perfluoropolyether type lubricating grease according to claim 7, characterized in that, The stirring time for step (1) is 60-120 min; the stirring time for step (2) is 90-120 min; the stirring time for step (3) is 90-120 min. And / or, the ultrasonic treatment time in step (1) is 90-120 min; the ultrasonic mixing time in step (2) is 90-120 min; and the ultrasonic mixing time in step (3) is 60-90 min.

9. The method for preparing the perfluoropolyether-type lubricating grease according to any one of claims 1-8, characterized in that, In step (4), the conditions for vacuum degassing include: degassing temperature at room temperature, degassing time of 4 to 6 hours, and vacuum degree of 0.1 to 10 kPa.

10. The method for preparing the perfluoropolyether type lubricating grease according to any one of claims 1-9, characterized in that, Based on 100 wt% of the perfluoropolyether grease, the perfluoropolyether grease comprises: Perfluoropolyether oil 55-85 wt%, preferably 60-75 wt%; The first thickener, the second thickener, and the third thickener are 10-40 wt%, preferably 24-39 wt%; The additive is 0.1 wt% to 5 wt%, preferably 2 wt% to 4 wt%.

11. The method for preparing the perfluoropolyether type lubricating grease according to any one of claims 1-10, characterized in that, The perfluoropolyether oil is a branched perfluoropolyether base oil with the chemical formula CF3-O-(CF2CF(CF3)O). m -(CF2O) n -CF3, where m and n are integers between 1 and 500, preferably 100-300, and 1≤m / n≤3.

12. The method for preparing the perfluoropolyether type lubricating grease according to any one of claims 1-11, characterized in that, The kinematic viscosity of the perfluoropolyether oil at 40°C is 0–800 cSt.

13. The method for preparing perfluoropolyether grease according to claim 12, wherein the kinematic viscosity of the perfluoropolyether oil at 40°C is 10-100 cSt.

14. A perfluoropolyether type lubricating grease, characterized in that, The perfluoropolyether grease is prepared by the preparation method according to any one of claims 1-13.

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