Preparation method of perfluoropolyether lubricating grease with high lubricating property

Abstract

The invention provides a preparation method of perfluoropolyether lubricating grease with high lubricating property, which comprises the following steps: adding a fluorine solvent and a fluorocarbon surfactant, stirring two groups of components to eliminate'agglomeration 'of a solid lubricating micro powder material and uniformly dispersing the solid lubricating micro powder material in the fluorine solvent, and for high-viscosity perfluoropolyether base oil, firstly adding the fluorine solvent containing uniformly distributed solid lubricating micro powder into the high-viscosity perfluoropolyether base oil, and then adding the fluorine solvent into the high-viscosity perfluoropolyether base oil to uniformly disperse the high-viscosity perfluoropolyether base oil to uniformly disperse the high-viscosity perfluoropolyether base oil; adding the mixture into perfluoropolyether base oil; adding the thickening agent into the perfluoropolyether base oil, heating, stirring and thickening to prepare perfluoropolyether lubricating grease; in the grease forming process, the perfluorosolvent volatilizes and does not become a constituent part of the perfluoropolyether lubricating grease. For the low-viscosity perfluoropolyether base oil, the prepared fluorine solvent can be added in the grease forming process. The solid lubricating material micro powder can be uniformly distributed on the fiber structure of the perfluoropolyether lubricating grease, the anti-attrition and anti-wear properties of the solid lubricating material are maximized, the prepared perfluoropolyether lubricating grease is greatly improved in anti-attrition, anti-wear and extreme pressure aspects, and the anti-wear property is improved by more than 40%.

Description

Technical Field

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

[0002] Perfluoropolyether grease has excellent durability, oxidation stability, chemical resistance and low temperature performance at high temperatures, and can be used under very harsh conditions, but perfluoropolyether oil has extremely strong chemical inertness and cannot be saponified to obtain a stable colloid or paste appearance. Most anti-wear and friction-reducing materials are incompatible with perfluoropolyether, and only solid lubricating materials can be used as anti-wear additives for perfluoropolyether, but the anti-wear effect is general. U.S. Patent US0180273871 uses polyol ester polyurea, adds anti-wear additive dialkyl dithiophosphate, and then mixes it with perfluoropolyether grease at a mass ratio of 5:95. Although it can improve lubricity a little, due to the incompatibility of perfluoropolyether with polyol ester, the effect of adding too little is limited. Therefore, most perfluoropolyether greases (referred to as fluoro greases) on the market have poor anti-wear performance and can only be used in low-speed and light and medium load scenes but in harsh working environments. For high-temperature, high-speed, and heavy-load working scenes, they lack long-term effective working life, which greatly limits the application range of fluoro greases.

[0003] The main reason that affects the anti-wear and friction-reducing effects of solid lubricants in fluorogrease is that these solid lubricants are micron-sized powder particles. These powder particles have the characteristics of aggregation and "agglomeration", and it is difficult to disperse them evenly when directly added to fluorogrease. This results in the lubricant being unable to be continuously and evenly distributed in the grease, and unable to form a continuous anti-wear oil film without breakpoints, so that the anti-wear performance will be greatly reduced. 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: 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 them in a closed container and stir or disperse them by ultrasonic vibration for later use; 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, evenly 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; S2: heat the perfluoropolyether base oil to 80-90°C, add an inorganic thickener during stirring, and continue stirring to form a paste structure; S3 adds the fluorine solvent solid lubricant powder dispersion prepared in S1 to the paste structure prepared in S2, and keeps the temperature and stirs rapidly for not less than 30 minutes until the fluorine solvent is completely volatilized; S4 uses a three-roll mill to homogenize the grease twice to complete the grease preparation; The raw materials used to prepare perfluoropolyether grease are mixed according to 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%.

[0005] Preferably, the fluorinated solvent may be selected from the group consisting of perfluoroalkane, perfluorodialkyl ether, and perfluorotrialkylamine.

[0006] Preferably, in consideration of environmental protection requirements, the fluorine solvent is one of perfluoroalkane, perfluorodialkyl ether and perfluorotrialkylamine.

[0007] Preferably, the amount of the fluorine solvent in step S1 is 2 times or more, preferably 2 times, the weight of the solid lubricating powder material added in S1.

[0008] 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.

[0009] Furthermore, in order to improve the surface state and structural agglomeration of the solid lubricating micropowder, make it uniformly dispersed in the fluorinated solvent, and improve the dispersion medium efficiency of the fluorinated solvent, the fluorinated surfactant in S1 is one of a fluorocarbon surfactant, a fluorosilicone surfactant, and a fluoroether surfactant, preferably a fluorocarbon surfactant. Fluorocarbon surfactants have better compatibility with fluorinated solvents, and their temperature resistance is similar to that of perfluoropolyether oil, and will not affect the high temperature performance of the prepared perfluoropolyether grease.

[0010] 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.

[0011] Preferably, the inorganic thickener is one or more of polytetrafluoroethylene powder, ultrafine fumed silica powder, and melamine urate.

[0012] Preferably, the fluorinated solvent is a perfluoro solvent that can completely dissolve the perfluoropolyether base oil, and the perfluoroalkane is preferably perfluorohexane, perfluorocyclohexane, perfluoromethylcyclohexane, perfluorotoluene, and perfluoroheptane; the perfluorodialkyl ether is preferably perfluoro 2-butyltetrahydrofuran; and the perfluorotrialkylamine is preferably perfluorotriethylamine.

[0013] Further, another method for preparing a perfluoropolyether grease with high lubricity comprises the following steps: S1 Pre-prepare fluorine solvent solid lubricant powder dispersion: first take fluorine solvent, add fluorine-containing surfactant and solid lubricant powder in sequence, place in a closed container and stir or disperse by ultrasonic vibration for use; 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. First, the selected high-viscosity perfluoropolyether base oil is heated to 80-90°C, and the fluorine solvent solid lubricant powder dispersion prepared in S1 is added, and the mixture is fully stirred; S3: adding an inorganic thickener to the mixture obtained in S2, and continuously maintaining the temperature and rapidly stirring for not less than 30 minutes, until the fluorine solvent is completely volatilized and thickened into a perfluoropolyether grease; S4 uses a three-roll mill to homogenize the grease twice to complete the grease preparation.

[0014] The beneficial effects of the present invention are as follows: the present invention provides a method for preparing a perfluoropolyether grease with high lubrication properties. The perfluoropolyether grease prepared by the method can obtain a uniform and dense distribution of solid lubricating materials, which can greatly improve the friction reduction, anti-wear and extreme pressure of the prepared perfluoropolyether grease. The additional preparation process includes adding fluorine solvent and fluorocarbon surfactant to the two groups of components, first eliminating the "agglomeration" of 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 solid lubricating micropowders; the preparation process includes using fluorine solvents and fluorine-containing surfactants to evenly disperse the solid lubricating micropowder materials. For the selection of high-viscosity perfluoropolyether base oil, the prepared solid lubricating material micropowder dispersion containing evenly distributed fluorine solvents is added to the perfluoropolyether base oil, and the thickener is added after sufficient stirring. Add, heat and stir to thicken to form perfluoropolyether grease. During the grease formation process, the perfluoro solvent will volatilize and not become a component of the perfluoropolyether grease. The fluorine solvent needs to be completely volatilized before the colloid of the perfluoropolyether grease is stable. For low-viscosity perfluoropolyether base oil, the prepared fluorine solvent solid lubricant powder dispersion can be added during the grease formation process, heated and stirred to thicken to form perfluoropolyether grease. The perfluoro solvent will volatilize and not become a component of the perfluoropolyether grease. The fluorine 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, directly adding raw materials to the perfluoropolyether base oil, heating and stirring to thicken to form 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

[0015] 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.

[0016] This embodiment further describes a method for preparing a perfluoropolyether grease with high lubricity: Implementation Case 1: Based on the standard mass ratio of 1002 grams, the kinematic viscosity of the perfluoropolyether base oil in this embodiment is 205 centistokes: The mass distribution of the fluorogrease components is as follows: 205 centistokes perfluoropolyether base oil: 830 grams Perfluorohexane: 200 g Diameter <20μm polytetrafluoroethylene (PTFE) powder: 50g Hexagonal boron nitride powder: 50g Polyoxyethylene: 0.4 g Ultrafine fumed silica powder: 21.6 g Polytetrafluoroethylene (PTFE) powder: 50 g Preparation process: S1: Pre-prepare fluorine solvent solid lubricant powder dispersion. Add 0.4 g of fluorocarbon surfactant, 50 g of polytetrafluoroethylene (PTFE) powder with a diameter of less than 20 μm, and 50 g of cubic boron nitride powder into 200 g of fluorine solvent perfluorohexane, place in a closed container and disperse by ultrasonic vibration for later use; S2: Take 830 g of 205 centistokes perfluoropolyether base oil and heat it to 85°C, then add 50 g of polytetrafluoroethylene (PTFE) micropowder and 21.6 g of ultrafine fumed silica micropowder into the perfluoropolyether base oil at a temperature of 85°C, and continue stirring until it becomes a paste; S3: Add the fluorine solvent solid lubricant powder dispersion prepared in S1 to the fluorine grease paste prepared in S2, and continue to stir and keep warm for 30 minutes until the fluorine solvent is completely volatilized; S4: Use a three-roll grinder to homogenize the grease twice to complete the preparation of the fluorogrease. At this time, the weight of the grease is 1002 grams.

[0017] Preparation of conventional fluororesin control group 1: 205 centistokes perfluoropolyether base oil 830 grams Polytetrafluoroethylene PTFE powder: 100g Ultrafine fumed silica powder: 20 g Hexagonal boron nitride powder: 50g The polytetrafluoroethylene (PTFE) powder is divided into two equal parts for standby use.

[0018] The preparation process is as follows: Heat 830g of perfluoropolyether PFPE base oil to 85℃, add 50g of polytetrafluoroethylene PTFE powder and 20g of ultrafine fumed silica powder, and continue stirring; when it becomes a paste, add 50g of polytetrafluoroethylene PTFE powder and 50g of hexagonal boron nitride powder, and use a three-roll grinder to homogenize the fat three times after it is completely fattened. The weight of the finished fluorogrease is 1000g.

[0019] Implementation Case 2: Based on the standard mass ratio of 1002 grams, the perfluoropolyether base oil in this embodiment has a kinematic viscosity of 500 centistokes: The mass distribution of the fluorogrease components is as follows: 500 centistokes perfluoropolyether base oil: 830 grams Perfluorohexane: 200 g Diameter <20μm polytetrafluoroethylene (PTFE) powder: 50g Hexagonal boron nitride powder: 50g Polyoxyethylene: 0.4 g Ultrafine fumed silica powder: 21.6 g Polytetrafluoroethylene (PTFE) powder: 50 g Preparation process: S1: Pre-prepared fluorine solvent solid lubricant powder dispersion: 0.4 g fluorocarbon surfactant, 50 g polytetrafluoroethylene with a diameter of less than 20 μm Add PTFE powder and 50g hexagonal boron nitride powder into 200g fluorine solvent perfluorohexane, place in a closed container, stir and disperse, and set aside; S2: Take 830 g of 500 centistokes perfluoropolyether base oil in a container and stir and heat to 85°C, then add the fluorine solvent solid lubricant powder dispersion prepared in S1, keep warm and stir for more than 30 minutes until the fluorine solvent is completely evaporated; S3: Add 50 g of polytetrafluoroethylene (PTFE) powder and 21.6 g of ultrafine fumed silica powder to the perfluoropolyether base oil prepared in S2, and continue stirring until it becomes a paste; S4: Use a three-roll grinder to homogenize the grease twice to complete the preparation of the fluorogrease. The weight of the finished grease is 1002 grams.

[0020] Preparation of conventional fluororesin control group 2: 500 centistokes perfluoropolyether base oil 830 grams Polytetrafluoroethylene PTFE powder: 100g Ultrafine fumed silica powder: 20 g Hexagonal boron nitride powder: 50g The polytetrafluoroethylene (PTFE) powder is divided into two equal parts for standby use. The preparation process is as follows: Heat 830g of PFPE base oil to 85℃, add 50g of PTFE powder and 20g of ultrafine fumed silica powder into the heated PFPE base oil, and keep stirring; when it becomes a paste, add 50g of PTFE powder and 50g of hexagonal boron nitride powder; after it is completely greased, use a three-roll grinder to homogenize the grease three times. The weight of the finished fluorogrease is 1000g.

[0021] Comparison of experimental results: 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 From the experimental test results, the diameter of the four-ball wear spot of the fluorogrease prepared by the conventional method is 3.5-4.3 times that of the implementation case. This shows that the new process of the present invention greatly improves the lubricity of the fluorogrease. The PB value represents the highest load without biting under experimental conditions. The fluorogrease prepared by the new process of the present invention has an improvement of 33%-60%. This shows that the wear resistance has been greatly improved. The extreme pressure performance PD value has also been improved by 25%-40%.

[0022] The present invention starts with the preparation process, and the solid lubricant powder can be evenly distributed on the fiber structure of the perfluoropolyether grease, maximizing the wear reduction and anti-wear performance of the solid lubricant, because the solid material is added with a solvent as a carrier instead of a dry powder, and the natural dispersion effect is greatly improved. Since the inertness of perfluoropolyether is extremely large, other organic solvents except perfluoro solvents are not miscible with perfluoropolyether, so the solvent medium for dispersing the solid lubricant is a perfluoro solvent.

[0023] The smaller the particle size of solid lubricating materials, the better, so that they can be distributed in the grease without gaps. However, if the particle size is small, agglomeration will occur. That is, dozens or hundreds of particles will gather together. Even if dispersed in a perfluorinated solvent, it is difficult to eliminate this agglomeration phenomenon. Therefore, in this technical solution, we use fluorocarbon surfactants to add to the perfluorinated solvent. They can change the surface energy of the solid lubricating particles and deconstruct the agglomeration phenomenon, which makes the solid surfactant dispersed and suspended in the fluorinated solvent in the form of single particles. This is the guarantee that the solid material will eventually form a complete anti-wear system in the fluorinated grease.

[0024] The invention can improve the lubrication performance of perfluoropolyether grease by more than 40%.

[0025] The new process of the invention improves the lubricating performance of the perfluoropolyether grease and expands the application range of the perfluoropolyether grease.

[0026] 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, all use of the present invention specification and equivalent component transformations made, or direct or indirect application in other related technical fields, are 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 Pre-prepare fluorine solvent solid lubricant powder dispersion: first take fluorine solvent, add fluorine-containing surfactant and solid lubricant powder in sequence, place in a closed container and stir or disperse by ultrasonic vibration for use; S2: heat the perfluoropolyether base oil to 80-90°C, add an inorganic thickener during stirring, and continue stirring to form a paste structure; S3 adds the fluorine solvent solid lubricant powder dispersion prepared in S1 to the paste structure prepared in S2, and keeps the temperature and stirs rapidly for not less than 30 minutes until the fluorine solvent is completely volatilized; S4 uses a three-roll mill to homogenize the grease twice to complete the grease preparation; The raw materials used to prepare perfluoropolyether grease are mixed according to 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%.

2. The method according to claim 1, characterized in that The fluorine solvent is one of perfluoroalkane, perfluorodialkyl ether and perfluorotrialkylamine.

3. 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, preferably 2 times.

4. The method according to claim 1, characterized in that 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 less than 20 μm.

5. The method according to claim 1, characterized in that The fluorine-containing surfactant in S1 is one of a fluorocarbon surfactant, a fluorosilicone surfactant, and a fluoroether surfactant, preferably a fluorocarbon surfactant.

6. The method according to claim 5, characterized in that 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.

7. The method according to claim 1, characterized in that: The inorganic thickener is one or more of polytetrafluoroethylene powder, ultrafine fumed silica powder, and melamine urate.

8. The method according to claim 2, characterized in that: The perfluoroalkane is preferably perfluorohexane, perfluorocyclohexane, perfluoromethylcyclohexane, perfluorotoluene, and perfluoroheptane; the perfluorodialkyl ether is preferably perfluoro 2-butyltetrahydrofuran; and the perfluorotrialkylamine is preferably perfluorotriethylamine.

9. A method for preparing a perfluoropolyether grease with high lubricity, comprising the following steps: S1 Pre-prepare fluorine solvent solid lubricant powder dispersion: first take fluorine solvent, add fluorine-containing surfactant and solid lubricant powder in sequence, place in a closed container and stir or disperse by ultrasonic vibration for use; S2: heat the perfluoropolyether base oil to 80-90°C, add an inorganic thickener during stirring, and continue stirring to form a paste structure; S3 adds the fluorine solvent solid lubricant powder dispersion prepared in S1 to the paste structure prepared in S2, and keeps the temperature and stirs rapidly for not less than 30 minutes until the fluorine solvent is completely volatilized; S4 uses a three-roll mill to homogenize the grease twice to complete the grease preparation; It is characterized in that when the viscosity of the perfluoropolyether base oil is greater than 200 centistokes at 25°C, the S2 perfluoropolyether base oil is heated to 80-90°C, the S1 prefabricated fluorine solvent solid lubricant powder dispersion is first added, and after sufficient stirring, the S3 inorganic thickener is added, and stirring is continued until the fluorine solvent is completely volatilized to form a perfluoropolyether grease.