A method for preparing perfluoropolyether grease with high lubrication properties

Abstract

The present invention provides a method for preparing a perfluoropolyether grease with high lubricity. A fluorine solvent and a fluorocarbon surfactant are added to the two components, and the solid lubricating powder material is stirred to eliminate "agglomeration" and evenly dispersed in the fluorine solvent. For high-viscosity perfluoropolyether base oil, the fluorine solvent containing evenly distributed solid lubricating powder is first added to the perfluoropolyether base oil; then a thickener is added to the perfluoropolyether base oil, and the oil is heated and stirred to thicken to form a perfluoropolyether grease; during the grease-forming process, the perfluorosolvent will evaporate and will not become a component of the perfluoropolyether grease. For low-viscosity perfluoropolyether base oil, the prepared fluorine solvent can be added during the grease-forming process. The solid lubricating material powder of the present invention can be evenly distributed on the fiber structure of the perfluoropolyether grease, maximizing the wear-reducing and anti-wear properties of the solid lubricating material. The perfluoropolyether grease prepared has greatly improved wear-reducing, anti-wear and extreme pressure properties, and the anti-wear properties are improved by more than 40%.

Description

Technical Field

[0001] The present invention relates to the field of lubrication technology, and in particular to a method for preparing perfluoropolyether grease with high lubrication properties. Background Art

[0002] Perfluoropolyether greases offer excellent durability, oxidative stability, chemical resistance, and low-temperature performance at high temperatures, and are suitable for use under extremely harsh conditions. However, perfluoropolyether oils are extremely chemically inert, making it difficult to obtain a stable colloid or paste-like appearance through saponification. Most anti-wear and friction-reducing materials are incompatible with perfluoropolyethers, forcing the use of solid lubricants as anti-wear additives, but these have limited anti-wear effectiveness. U.S. Patent No. 0180273871 utilizes polyol ester polyurea with the anti-wear additive dialkyl dithiophosphate, then mixes it with perfluoropolyether grease at a mass ratio of 5:95. While this improves lubricity somewhat, the incompatibility between perfluoropolyether and polyol esters limits the effectiveness of the added amount. Consequently, most commercially available perfluoropolyether greases (referred to as fluorogreases) exhibit poor anti-wear performance and are limited to low-speed, light- to medium-load applications in harsh operating environments. They lack a long-term effective operating life in high-temperature, high-speed, and heavy-load environments, significantly limiting their application.

[0003] The main factor affecting the anti-wear and friction-reducing effects of solid lubricants in fluorogreases is that these solid lubricants are micron-sized powder particles. These particles tend to aggregate and "clump," making it difficult to disperse them evenly when added directly to the fluorogrease. This prevents the lubricant from being continuously and evenly distributed throughout the grease, preventing the formation of a continuous, seamless anti-wear film. This significantly reduces the anti-wear performance. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for preparing a perfluoropolyether grease with high lubrication properties, the method comprising the following steps:

[0005] S1 Preparing a fluorine solvent solid lubricant powder dispersion: First, take a fluorine solvent, add a fluorine-containing surfactant and a solid lubricant powder material in sequence, place the mixture in a closed container, stir or disperse it by ultrasonic vibration, and then set aside; in order to fully disperse the solid lubricant powder material, the amount of fluorine solvent used in this step is 2 times or more of the weight of the added solid lubricant powder material, preferably 2 times; in order to improve the surface state and structural agglomeration of the solid lubricant powder, uniformly disperse the solid lubricant powder in the fluorine solvent, and improve the dispersion medium efficiency of the fluorine solvent, the fluorine-containing surfactant is one of a fluorocarbon surfactant, a fluorosilicone surfactant, and a fluoroether surfactant;

[0006] S2: heat the perfluoropolyether base oil to 80-90°C, add an inorganic thickener during stirring, and continue stirring to form a paste-like structure;

[0007] S3 adds the fluorine solvent solid lubricant powder dispersion prepared in S1 to the paste structure prepared in S2, and continuously heats and rapidly stirs for no less than 30 minutes until the fluorine solvent is completely volatilized;

[0008] S4 uses a three-roll mill to homogenize the grease twice to complete the grease preparation;

[0009] The raw materials used to prepare perfluoropolyether grease are mixed in the following mass percentages:

[0010] Perfluoropolyether base oil 50%-95%;

[0011] Fluorinated solvent 15%-40%;

[0012] Solid lubricating powder material 5%-20%;

[0013] Fluorinated surfactant 0.015%-0.4%;

[0014] Inorganic thickener 5%-40%.

[0015] Preferably, the fluorinated solvent can be selected from perfluoroalkane, perfluorodialkyl ether, and perfluorotrialkylamine.

[0016] Preferably, in consideration of environmental protection requirements, the fluorinated solvent is one of perfluoroalkane, perfluorodialkyl ether and perfluorotrialkylamine.

[0017] Preferably, the amount of the fluorinated solvent in step S1 is 2 times or more, preferably 2 times, the weight of the solid lubricating powder material added in S1.

[0018] Preferably, to improve the properties of the grease, the solid lubricating powder material is one or more of polytetrafluoroethylene powder, hexagonal boron nitride powder, molybdenum disulfide powder, and colloidal graphite powder with a diameter of less than 20 μm.

[0019] Furthermore, to improve the surface condition and structural agglomeration of the solid lubricating powder, uniformly disperse it in the fluorinated solvent, and improve the dispersion medium efficiency of the fluorinated solvent, the fluorinated surfactant in S1 is selected from the group consisting of a fluorocarbon surfactant, a fluorosilicone surfactant, and a fluoroether surfactant, preferably a fluorocarbon surfactant. Fluorocarbon surfactants have better compatibility with fluorinated solvents and have similar temperature resistance to perfluoropolyether oil, thus not affecting the high-temperature performance of the prepared perfluoropolyether grease.

[0020] Preferably, the mass of the fluorocarbon surfactant is 0.1%-1%, preferably 0.2%, of the mass of the fluorinated solvent; the fluorocarbon surfactant is preferably a non-ionic fluorocarbon surfactant, which is a polyoxyethylene group, and its polar group is usually an oxygen-containing ether bond.

[0021] Preferably, the inorganic thickener is one or more of polytetrafluoroethylene powder, ultrafine fumed silica powder, and melamine urate.

[0022] Preferably, the fluorinated solvent is a perfluorosolvent that can completely dissolve the perfluoropolyether base oil, wherein the perfluoroalkane is preferably perfluorohexane, perfluorocyclohexane, perfluoromethylcyclohexane, perfluorotoluene, or perfluoroheptane; the perfluorodialkyl ether is preferably perfluoro-2-butyltetrahydrofuran; and the perfluorotrialkylamine is preferably perfluorotriethylamine.

[0023] Furthermore, another method for preparing a perfluoropolyether grease with high lubricity comprises the following steps:

[0024] S1 Preparing a fluorine solvent solid lubricant powder dispersion: First, take a fluorine solvent, add a fluorine-containing surfactant, and solid lubricant powder in sequence, place in a closed container, stir or disperse by ultrasonic vibration, and then set aside;

[0025] The perfluoropolyether base oil selected in S2 has a viscosity greater than 200 centistokes at 25°C and is a high-viscosity perfluoropolyether base oil. The selected high-viscosity perfluoropolyether base oil is first heated to 80-90°C, and the fluorinated solvent solid lubricant powder dispersion prepared in S1 is added thereto, and the mixture is thoroughly stirred.

[0026] S3: adding an inorganic thickener to the mixture obtained in S2, and continuously stirring the mixture at high speed while maintaining the temperature for not less than 30 minutes, until the fluorine solvent is completely volatilized and the mixture is thickened into a perfluoropolyether grease;

[0027] S4 uses a three-roll mill to homogenize the grease twice to complete the grease preparation.

[0028] The beneficial effects of the present invention are: the present invention provides a method for preparing a perfluoropolyether grease with high lubrication properties. The solid lubricating material of the perfluoropolyether grease prepared by the method can be evenly and densely distributed, which can greatly improve the friction reduction, anti-wear and extreme pressure of the perfluoropolyether grease. The additional preparation process includes adding fluorine solvent and fluorocarbon surfactant to the two groups of components, first eliminating the "agglomeration" of the solid lubricating particles by physical stirring and evenly dispersing them in the fluorine solvent, and modifying the surface of the ultrafine solid lubricating material with a fluorine-containing surfactant to deconstruct the agglomeration of the solid lubricating micropowder; the preparation process includes using a fluorine solvent and a fluorine-containing surfactant to evenly disperse the solid lubricating micropowder material. For the selection of high-viscosity perfluoropolyether base oil, the prepared solid lubricating material micropowder dispersion containing evenly distributed fluorine solvent is added to the perfluoropolyether base oil, and after sufficient stirring, the thickener is added. The perfluoropolyether grease is prepared by heating, stirring and thickening. During the grease-forming process, the perfluorosolvent will evaporate and will not become a component of the perfluoropolyether grease. The fluorinated solvent needs to be completely volatilized before the colloid of the perfluoropolyether grease is stable. For low-viscosity perfluoropolyether base oil, the prepared fluorinated solvent solid lubricant powder dispersion can be added during the grease-forming process, heated, stirred and thickened to form the perfluoropolyether grease. The perfluorosolvent will evaporate and will not become a component of the perfluoropolyether grease. The fluorinated solvent needs to be completely volatilized before the colloid of the perfluoropolyether grease is stable. Compared with the conventional production of perfluoropolyether lubricating grease, which does not require the above-mentioned preparation method and directly adds the raw materials to the perfluoropolyether base oil, and heats, stirs and thickens to form the perfluoropolyether grease, the perfluoropolyether grease prepared according to the process of the present invention has an anti-wear performance improved by more than 40%. Implementation Method

[0029] The invention discloses a method for preparing a perfluoropolyether grease with high lubricity, which greatly improves the colloidal stability of the lubricating silicone grease and greatly enhances the applicable fields and industries of the lubricating silicone grease.

[0030] This embodiment further illustrates a method for preparing a perfluoropolyether grease with high lubricity:

[0031] Implementation Case 1:

[0032] Based on a standard mass ratio of 1002 grams, the kinematic viscosity of the perfluoropolyether base oil in this embodiment is 205 centistokes:

[0033] The mass distribution of the fluorogrease components is as follows:

[0034] 205 centistokes perfluoropolyether base oil: 830 grams

[0035] Perfluorohexane: 200 g

[0036] Diameter <20μm polytetrafluoroethylene (PTFE) powder: 50g

[0037] Hexagonal boron nitride powder: 50g

[0038] Polyoxyethylene: 0.4 g

[0039] Ultrafine fumed silica powder: 21.6 g

[0040] Polytetrafluoroethylene (PTFE) powder: 50g

[0041] Preparation process:

[0042] S1: Prepare a fluorinated solvent solid lubricant powder dispersion. Add 0.4g of fluorocarbon surfactant, 50g of polytetrafluoroethylene (PTFE) powder (<20μm in diameter), and 50g of cubic boron nitride powder to 200g of perfluorohexane (fluorinated solvent). Place the mixture in a sealed container and disperse it by ultrasonic vibration for later use.

[0043] S2: Heat 830 g of 205 centistokes perfluoropolyether base oil to 85°C, then add 50 g of polytetrafluoroethylene (PTFE) powder and 21.6 g of ultrafine fumed silica powder to the perfluoropolyether base oil at 85°C and continue stirring until it becomes a paste.

[0044] S3: Add the fluorine solvent solid lubricant powder dispersion prepared in S1 to the fluorine grease paste prepared in S2, and continue stirring at the temperature for 30 minutes until the fluorine solvent is completely evaporated;

[0045] S4: Use a three-roll mill to homogenize the grease twice to complete the preparation of the fluorogrease. At this time, the weight of the grease is 1002 grams.

[0046] Preparation of conventional fluororesin control group 1:

[0047] 830g of 205 centistokes perfluoropolyether base oil

[0048] Polytetrafluoroethylene PTFE powder: 100g

[0049] Ultrafine fumed silica powder: 20g

[0050] Hexagonal boron nitride powder: 50g

[0051] The polytetrafluoroethylene (PTFE) powder is divided into two equal parts for standby use.

[0052] The preparation process is as follows:

[0053] Heat 830g of perfluoropolyether (PFPE) base oil to 85°C, add 50g of polytetrafluoroethylene (PTFE) powder and 20g of ultrafine fumed silica powder, and continue stirring. Once a paste forms, add 50g of polytetrafluoroethylene (PTFE) powder and 50g of hexagonal boron nitride (HBN) powder. Once the paste is fully formed, homogenize the paste three times using a three-roll mill. The finished fluorogrease weighs 1000g.

[0054] Implementation Case 2:

[0055] Based on a standard mass ratio of 1002 grams, the perfluoropolyether base oil in this embodiment has a kinematic viscosity of 500 centistokes:

[0056] The mass distribution of the fluorogrease components is as follows:

[0057] 500 centistokes perfluoropolyether base oil: 830 grams

[0058] Perfluorohexane: 200 g

[0059] Diameter <20μm polytetrafluoroethylene (PTFE) powder: 50g

[0060] Hexagonal boron nitride powder: 50g

[0061] Polyoxyethylene: 0.4 g

[0062] Ultrafine fumed silica powder: 21.6 g

[0063] Polytetrafluoroethylene (PTFE) powder: 50g

[0064] Preparation process:

[0065] S1: Pre-prepare fluorine solvent solid lubricant powder dispersion: 0.4g fluorocarbon surfactant, 50g polytetrafluoroethylene with diameter less than 20μm

[0066] Add PTFE powder and 50g hexagonal boron nitride powder to 200g fluorine solvent perfluorohexane, place in a closed container, stir and disperse, and set aside;

[0067] S2: Take 830 g of 500 centistokes perfluoropolyether base oil in a container and stir and heat to 85°C. Then add the fluorinated solvent solid lubricant powder dispersion prepared in S1. Continue to keep warm and stir for more than 30 minutes until the fluorinated solvent is completely evaporated.

[0068] S3: Add 50g of polytetrafluoroethylene (PTFE) powder and 21.6g of ultrafine fumed silica powder to the perfluoropolyether base oil prepared in S2 and continue stirring until it becomes a paste;

[0069] S4: Use a three-roll mill to homogenize the grease twice to complete the preparation of the fluorogrease. The weight of the finished grease is 1002 grams.

[0070] Preparation of conventional fluororesin control group 2:

[0071] 830g 500 centistokes perfluoropolyether base oil

[0072] Polytetrafluoroethylene PTFE powder: 100g

[0073] Ultrafine fumed silica powder: 20g

[0074] Hexagonal boron nitride powder: 50g

[0075] The polytetrafluoroethylene (PTFE) powder is divided into two equal parts for standby use.

[0076] The preparation process is as follows:

[0077] Heat 830g of perfluoropolyether (PFPE) base oil to 85°C. Add 50g of polytetrafluoroethylene (PTFE) powder and 20g of ultrafine fumed silica powder to the heated perfluoropolyether base oil while stirring continuously. Once a paste forms, add 50g of polytetrafluoroethylene (PTFE) powder and 50g of hexagonal boron nitride (HBN) powder. Once the paste is fully formed, homogenize the paste three times using a three-roll mill. The finished fluorogrease weighs 1000g.

[0078] Comparison of experimental results:

[0079] Test items Example 1 Control group 1 Example 2 Control group 2 consistency 268 290 260 283 Four-ball wear spot diameter 0.62mm 2.68mm 0.58mm 2.0mm BP value (kg) 80 50 80 60 Extreme pressure value PD (kg) 350 250 375 300

[0080] Experimental test results show that the four-ball wear spot diameter of the fluorogrease prepared by conventional methods is 3.5-4.3 times that of the experimental examples. This demonstrates that the novel process of the present invention significantly improves the lubricity of the fluorogrease. The PB value represents the maximum load at which no seizure occurs under experimental conditions. The fluorogrease prepared using the novel process of the present invention exhibits a 33%-60% improvement, indicating a significant improvement in wear resistance. The extreme pressure performance (PD) value also increases by 25%-40%.

[0081] The present invention utilizes a preparation process to evenly distribute the solid lubricant powder throughout the fiber structure of the perfluoropolyether grease, maximizing the solid lubricant's wear-reducing and anti-wear properties. Because the solid material is added via a solvent carrier, rather than as a dry powder, the natural dispersion effect is significantly improved. Due to the extreme inertness of perfluoropolyether, other organic solvents, other than perfluorosolvents, are incompatible with perfluoropolyether, so perfluorosolvents are the solvent medium of choice for dispersing the solid lubricant.

[0082] The smaller the particle size of solid lubricants, the better, as this allows for seamless distribution within the grease. However, small particle sizes can lead to agglomeration, with dozens or even hundreds of particles clumping together. Even when dispersed in a perfluorinated solvent, this agglomeration is difficult to eliminate. Therefore, in this technical solution, fluorocarbon surfactants are added to the perfluorinated solvent. These surfactants alter the surface energy of the solid lubricant particles, breaking down the agglomeration. This allows the solid surfactant to be dispersed and suspended in the fluorinated solvent as individual particles, ensuring that the solid material ultimately forms a complete anti-wear system within the fluorinated grease.

[0083] The present invention can improve the lubrication performance of perfluoropolyether grease by more than 40%.

[0084] The new process of the present invention improves the lubricating performance of perfluoropolyether grease and expands the application range of perfluoropolyether grease.

[0085] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Relevant personnel in the relevant fields, without making any creative work, shall use the description of the present invention and the equivalent component transformation made, or directly or indirectly apply it to other related technical fields, which are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a perfluoropolyether grease with high lubrication properties, characterized in that: The preparation method of the perfluoropolyether grease comprises the following steps: S1: Preparing a fluorine solvent solid lubricant powder dispersion: First, take a fluorine solvent, add a fluorine-containing surfactant, and solid lubricant powder in sequence, place in a closed container, and stir or disperse by ultrasonic vibration for later use; S2: Heat the perfluoropolyether base oil to 80-90°C, add an inorganic thickener during stirring, and continue stirring to form a paste-like structure; S3: Add the fluorine solvent solid lubricant powder dispersion prepared in S1 to the paste structure prepared in S2, and continue to heat and rapidly stir for no less than 30 minutes until the fluorine solvent is completely evaporated; S4: Use a three-roll mill to homogenize the grease twice to complete the grease preparation; The raw materials used to prepare perfluoropolyether grease are mixed in the following mass percentages: Perfluoropolyether base oil 50%-95%; Fluorinated solvent 15%-40%; Solid lubricating powder material 5%-20%; Fluorinated surfactant 0.015%-0.4%; Inorganic thickener 5%-40%; The fluorinated solvent is one of perfluoroalkane, perfluorodialkyl ether and perfluorotrialkylamine; The solid lubricating powder material is one or more of polytetrafluoroethylene powder, hexagonal boron nitride powder, molybdenum disulfide powder, and colloidal graphite powder with a diameter of less than 20 μm; In step S1, the fluorine-containing surfactant is one of a fluorocarbon surfactant, a fluorosilicone surfactant, and a fluoroether surfactant; The inorganic thickener is one or more of polytetrafluoroethylene powder, ultrafine fumed silica powder, and melamine urate.

2. The method according to claim 1, characterized in that The amount of the fluorine solvent used in step S1 is 2 times or more of the weight of the solid lubricating micropowder material added in S1.

3. The method according to claim 1, characterized in that The mass of the fluorocarbon surfactant is 0.1%-1% of the mass of the fluorinated solvent; the fluorocarbon surfactant is a non-ionic fluorocarbon surfactant.

4. The method according to claim 1, wherein The perfluoroalkane is perfluorohexane, perfluorocyclohexane, perfluoromethylcyclohexane, or perfluoroheptane; and the perfluorotrialkylamine is perfluorotriethylamine.