Highly colloidal stable perfluoropolyether type grease, process for its preparation and use

Abstract

The present application relates to a kind of high colloidal stability grease and its preparation method and the high colloidal stability grease prepared by the preparation method and its application.The preparation raw material of high colloidal stability grease includes perfluoropolyether base oil, thickening agent and hydrophobic silica additive treated by fluorine modifier, based on the total amount of perfluoropolyether base oil, thickening agent and hydrophobic silica additive treated by fluorine modifier, the content of perfluoropolyether base oil is 40wt%-80wt%, the content of thickening agent is 19wt%-50wt%, the content of hydrophobic silica additive treated by fluorine modifier is 1wt%-25wt%;The average particle size of hydrophobic silica additive is 10 μm-1000 μm.The perfluoropolyether type lubricating grease of the present application, hydrophobic silica additive treated by fluorine modifier is more evenly dispersed in perfluoropolyether base oil, improves the colloidal stability of perfluoropolyether lubricating grease.

Description

Technical Field

[0001] This invention belongs to the field of lubricating materials, specifically a high colloidal stability perfluoropolyether type lubricating grease, its preparation method, and its application. Background Technology

[0002] In the field of lubrication technology, perfluoropolyether grease is mainly composed of perfluoropolyether base oil and polytetrafluoroethylene thickener. It has excellent low volatility, thermal stability, chemical stability, high and low temperature characteristics and lubrication properties, and has been widely used in harsh operating environments such as high temperature, vacuum and corrosion.

[0003] However, in practical applications, it has been found that perfluoropolyether greases have certain defects in colloidal stability, with significant oil separation, which affects the service life of the grease. Furthermore, in some cleanrooms, oil separation can lead to environmental pollution of equipment and affect its normal operation.

[0004] Research has found that perfluoropolyether grease is prepared by physical formulation. The thickener in the grease acts like a "sponge," interacting with the base oil through physical adsorption or chemical bonding. Due to the special molecular structure of PFPE and PTFE, the binding force between them is relatively weak, resulting in poor colloidal stability of perfluoropolyether grease and more obvious oil separation phenomenon than other types of grease.

[0005] Chinese patent application CN115125047A discloses a method for preparing modified silica as an additive for perfluoropolyether lubricants. It uses a silane coupling agent as a bridge and utilizes the -CONH- generated by the reaction of -NH2 in triethylamine and -COF in perfluoropolyether acyl fluoride to graft perfluoropolyether onto the surface of nano silica to improve the dispersion stability of silica in perfluoropolyether. The process is relatively complex and involves a variety of chemical reagents. Summary of the Invention

[0006] In order to solve the technical problems of high oil separation and poor colloidal stability in existing perfluoropolyether grease products, the present invention aims to provide a perfluoropolyether grease with high colloidal stability, its preparation method and application.

[0007] Therefore, in a first aspect, the present invention provides a high colloidal stability grease, the raw materials for which include perfluoropolyether base oil, thickener, and hydrophobic silica additive treated with fluorine modifier. Based on the total amount of perfluoropolyether base oil, thickener, and hydrophobic silica additive treated with fluorine modifier, the content of perfluoropolyether base oil is 40wt% to 80wt%, the content of thickener is 19wt% to 50wt%, and the content of hydrophobic silica additive treated with fluorine modifier is 1wt% to 25wt%; the average particle size of the hydrophobic silica additive is 10μm to 1000μm.

[0008] Specifically, due to the unique molecular structure of perfluoropolyether oils, they exhibit both hydrophobic and oleophobic properties, making it difficult for them to form a stable dispersion system with ordinary lubricating oil additives and functional particles. This results in the additives failing to perform their intended function. Therefore, different dispersion methods are needed to modify the additives and improve their dispersibility in perfluoropolyether. Thus, the perfluoropolyether grease provided by this invention incorporates a hydrophobic silica additive treated with a fluorine modifier into its raw material. The fluorine modifier treatment fluorinates the CH groups on the surface of the hydrophobic silica into CF groups, allowing the hydrophobic silica to disperse more uniformly in the perfluoropolyether, further improving the colloidal stability of the perfluoropolyether grease, reducing oil separation, and extending equipment lifespan.

[0009] Specifically, the mass of hydrophobic silica additives treated with fluorine modifiers is only slightly increased compared to untreated hydrophobic silica additives. This may be because the fluorine modifier treatment simply fluorinates the CH groups on the surface of the hydrophobic silica into CF groups.

[0010] In a specific embodiment of the present invention, preferably, the specific surface area of ​​the hydrophobic silica additive is 20 m². 2 / g~1000m 2 / g. Hydrophobic silica additives within this range can function as lubricating grease additives.

[0011] In a preferred embodiment of the present invention, the hydrophobic silica additive has an average particle size of 250 μm to 500 μm. Hydrophobic silica additives within this range can function as better lubricating grease additives.

[0012] As a specific embodiment of the present invention, preferably, the specific surface area of ​​the hydrophobic silica additive is 200 m². 2 / g~500m 2 / g. Hydrophobic silica additives within this range can perform better as lubricating grease additives.

[0013] As a specific embodiment of the present invention, preferably, the hydrophobic silica additive is present in the high colloidal stability grease at a content of 5wt% to 25wt%.

[0014] As a specific embodiment of the present invention, preferably, the perfluoropolyether base oil includes at least one of K-type perfluoropolyether base oil, Y-type perfluoropolyether base oil, Z-type perfluoropolyether base oil, and D-type perfluoropolyether.

[0015] As a specific embodiment of the present invention, preferably, the molecular weight of the perfluoropolyether base oil is 1000g / mol to 30000g / mol.

[0016] As a specific embodiment of the present invention, preferably, the molecular weight of the perfluoropolyether base oil is 3000g / mol to 10000g / mol.

[0017] As a specific embodiment of the present invention, preferably, the molecular weight of the perfluoropolyether base oil is 4000g / mol to 8000g / mol.

[0018] As a specific embodiment of the present invention, preferably, the thickener includes at least one of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, bentonite, and boron nitride.

[0019] In a specific embodiment of the present invention, preferably, the fluorine modifier is fluorine gas.

[0020] Specifically, the perfluoropolyether grease provided by this invention uses fluorine gas as a fluorine modifier, which can fluorinate the CH groups on the surface of hydrophobic silica into CF groups, allowing the hydrophobic silica to be dispersed more uniformly in the perfluoropolyether, further improving the colloidal stability of the perfluoropolyether grease, reducing grease separation, and extending the service life of equipment.

[0021] As a specific embodiment of the present invention, preferably, the preparation method of the hydrophobic silica additive treated with fluorine modifier includes: introducing the fluorine modifier when the hydrophobic silica additive is mixed with the perfluoropolyether base oil.

[0022] Specifically, the hydrophobic silica additive treated with fluorine modifier provided by this invention can fluorinate the CH groups on the surface of hydrophobic silica into CF groups, allowing the hydrophobic silica to be more uniformly dispersed in perfluoropolyether, further improving the colloidal stability of perfluoropolyether grease, reducing grease oil separation, and extending the service life of equipment.

[0023] As a specific embodiment of the present invention, preferably, the mixing conditions include: a fluorine gas flow rate of 20 ml / min to 300 ml / min relative to 20 g of hydrophobic silica additive, and an introduction time of 1-4 hours.

[0024] As a specific embodiment of the present invention, preferably, the mixing conditions include a temperature of 80°C to 200°C.

[0025] Therefore, in a second aspect, the present invention provides a method for preparing a high colloidal stability grease, comprising the following steps:

[0026] S1. Under the condition of continuous addition of fluorine modifier, the perfluoropolyether base oil and hydrophobic silica additive are mixed to obtain a suspension containing perfluoropolyether base oil and hydrophobic silica additive treated with fluorine modifier.

[0027] S2. Add a thickener to the suspension obtained in step S1 to thicken it, and then grind it to obtain the high colloidal stability grease.

[0028] Specifically, in step S1, under the condition of continuous addition of fluorine modifier, the perfluoropolyether base oil and hydrophobic silica additive are mixed, thereby fluorinating the CH groups on the surface of the hydrophobic silica into CF groups, allowing the hydrophobic silica to be more uniformly dispersed in the perfluoropolyether, further improving the colloidal stability of the perfluoropolyether grease, reducing grease separation, and extending the service life of the equipment.

[0029] As a specific embodiment of the present invention, preferably, in step S1, the fluorine modifier is fluorine gas. Preferably, relative to 20g of hydrophobic silica additive, the flow rate of fluorine gas is 20ml / min to 300ml / min, and the introduction time is 1-4 hours.

[0030] As a specific embodiment of the present invention, preferably, in step S1, the mixing conditions further include a temperature of 80°C to 200°C.

[0031] As a specific embodiment of the present invention, preferably, in step S2, the thickening conditions include: temperature 40℃~80℃, vacuum degree 1Pa~1000Pa, and stirring, preferably for 2 hours to 10 hours.

[0032] As a specific embodiment of the present invention, preferably, in step S2, the grinding conditions include: a temperature of 20°C to 30°C, and / or a grinding time of 0.5 hours to 3 hours.

[0033] Therefore, in a third aspect, the present invention provides a highly colloidal stable grease prepared by the above-described preparation method.

[0034] Therefore, in a fourth aspect, the present invention provides the application of the above-mentioned high colloidal stability grease in high-cleanliness or high-temperature environment equipment.

[0035] As a specific embodiment of the present invention, preferably, the high-cleanliness environment equipment includes high-vacuum equipment for semiconductor manufacturing and equipment for aerospace optical systems.

[0036] As a specific embodiment of the present invention, preferably, the high-temperature environment equipment includes a high-temperature bearing for a heat setting machine and a high-temperature bearing for an extrusion granulator.

[0037] The present invention has the following beneficial effects:

[0038] The high colloidal stability grease provided by this invention contains a fluorine modifier in its raw materials, which can fluorinate the CH groups in hydrophobic silica into CF groups, allowing the hydrophobic silica to be more uniformly dispersed in perfluoropolyether, thereby improving the colloidal stability of the perfluoropolyether grease, reducing grease separation, and extending the service life of equipment.

[0039] The preparation method provided by this invention involves continuously introducing fluorine gas into a mixture containing hydrophobic silica and perfluoropolyether when adding hydrophobic silica, so that the hydrophobic silica is more uniformly dispersed in the perfluoropolyether. The prepared perfluoropolyether grease has a uniform paste appearance and good colloidal stability, thermal stability, and chemical stability, and can be applied to equipment in high-temperature, high-vacuum, and high-cleanliness environments. Detailed Implementation

[0040] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0041] Example 1

[0042] (1) Take 100g of Y-type perfluoropolyether base oil with a molecular weight of 5000 g / mol and mix it with 20g of oil with an average particle size of 500μm and a specific surface area of ​​200m². 2 / g of hydrophobic silica (Cabot TS-530) was added to the reactor for mixing. During the mixing process, fluorine gas was continuously introduced for 2 hours at a flow rate of 50ml / min.

[0043] (2) Add 80g of polytetrafluoroethylene (Daikin L-5F, Japan) to the above mixture and stir for 5 hours at 50°C and 100Pa. After cooling to room temperature, grind for 1 hour to obtain the grease of Example 1.

[0044] Example 2

[0045] (1) Take 120g of K-type perfluoropolyether base oil with a molecular weight of 6000g / mol and mix it with 20g of oil with an average particle size of 400μm and a specific surface area of ​​220m². 2 / g of hydrophobic silica (Huifu Nano HB-152) was added to the reactor for mixing. During the mixing process, fluorine gas was continuously introduced for 2 hours at a flow rate of 60ml / min.

[0046] (2) Add 60g of polytetrafluoroethylene (Daikin L-5F, Japan) to the above mixture and stir for 4 hours at 60°C and 150Pa. After cooling to room temperature, grind for 2 hours to obtain the grease of Example 1.

[0047] Example 3

[0048] (1) Take 80g of Z-type perfluoropolyether base oil with a molecular weight of 7000g / mol and mix it with 10g of oil with an average particle size of 350μm and a specific surface area of ​​300m². 2 / g of hydrophobic silica (Huifu Nano HB-630) was added to the reactor for mixing. During the mixing process, fluorine gas was continuously introduced for 2 hours at a flow rate of 70ml / min.

[0049] (2) 110g of polytetrafluoroethylene (Solvay F-5A R) was added to the above mixture and stirred for 3 hours at 55°C and 500Pa. After cooling to room temperature, it was ground for 2 hours to obtain the grease of Example 3.

[0050] Example 4

[0051] (1) Take 110g of K-type perfluoropolyether base oil with a molecular weight of 6500 g / mol and mix it with 40g of oil with an average particle size of 260μm and a specific surface area of ​​500m². 2 / g of hydrophobic silica (Huifu Nano HB-620) was added to the reactor for mixing. During the mixing process, fluorine gas was continuously introduced for 1.5 hours at a flow rate of 250ml / min.

[0052] (2) Add 50g of polytetrafluoroethylene (Solvay F-5A R) to the above mixture and stir for 3 hours at 75°C and 600Pa. After cooling to room temperature, grind for 1.5 hours to obtain the grease of Example 4.

[0053] Comparative Example 1

[0054] (1) Take 80g of polytetrafluoroethylene (Daikin L-5F, Japan) and add it to 100g of Y-type perfluoropolyether base oil with a molecular weight of 5000g / mol.

[0055] (2) Stir at 50℃ and 100Pa for 5 hours. After cooling to room temperature, grind for 1 hour to obtain the grease of Comparative Example 1.

[0056] Comparative Example 2

[0057] (1) Take 100g of Y-type perfluoropolyether base oil with a molecular weight of 5000g / mol and mix it with 20g of oil with an average particle size of 500μm and a specific surface area of ​​200m². 2 / g of hydrophobic silica (Cabot TS-530) was added to the reactor for mixing;

[0058] (2) Add 80g of polytetrafluoroethylene (Daikin L-5F, Japan) to the above mixture and stir for 5 hours at 50°C and 100Pa. After cooling to room temperature, grind for 1 hour to obtain the grease of Comparative Example 2.

[0059] Comparative Example 3

[0060] (1) Take 100g of Y-type perfluoropolyether base oil with a molecular weight of 5000g / mol and mix it with 1g of oil with an average particle size of 550μm and a specific surface area of ​​220m². 2 / g of hydrophobic silica (Cabot TS-530) was added to the reactor for mixing; during the mixing process, fluorine gas was continuously introduced for 2 hours at a flow rate of 50ml / min.

[0061] (2) Add 70g of polytetrafluoroethylene (Solwegian XPP511) to the above mixture and stir for 5 hours at 50°C and 100Pa. After cooling to room temperature, grind for 1 hour to obtain the grease of Comparative Example 3.

[0062] Comparative Example 4

[0063] (1) Take 100g of Y-type perfluoropolyether base oil with a molecular weight of 5000g / mol and mix it with 30g of oil with an average particle size of 5μm and a specific surface area of ​​220m². 2 / g of hydrophobic silica (Huifu Nano HB-615) was added to the reactor for mixing; during the mixing process, fluorine gas was continuously introduced for 2 hours at a flow rate of 50ml / min.

[0064] (2) Add 70g of polytetrafluoroethylene (Sowes L100) to the above mixture and stir for 5 hours at 50°C and 100Pa. After cooling to room temperature, grind for 1 hour to obtain the grease of Comparative Example 4.

[0065] Table 1

[0066]

[0067]

[0068] As can be seen from the comparison between Example 1 and Comparative Example 1, the hydrophobic silica additive can improve the oil separation performance of perfluoropolyether grease and enhance the colloidal stability of the grease.

[0069] As can be seen from the comparison between Example 1 and Comparative Example 2, the hydrophobic silica treated with fluorine gas forms a stable dispersion system with perfluoropolyether, resulting in a grease with smaller oil separation and better colloidal stability.

[0070] As can be seen from the comparison between Example 1 and Comparative Example 3, the addition of hydrophobic silica is less than 1 wt%, which has no significant effect on the oil separation performance and colloidal stability of perfluoropolyether grease.

[0071] As can be seen from the comparison between Example 1 and Comparative Example 4, the average particle size of the hydrophobic silica additive is less than 10 μm, and it does not significantly improve the oil separation performance and colloidal stability of the perfluoropolyether grease.

[0072] In summary, the perfluoropolyether grease provided by this invention exhibits excellent colloidal stability. Specific hydrophobic silica is treated with a fluorine modifier, allowing the treated hydrophobic silica to disperse more uniformly in the perfluoropolyether base oil. The resulting perfluoropolyether grease has a uniform paste-like appearance and possesses good colloidal stability, thermal stability, and chemical stability, making it suitable for use in high-temperature, high-vacuum, and high-cleanliness environments.

[0073] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A highly colloidal stable grease, characterized in that, The raw materials for its preparation include perfluoropolyether base oil, thickener, and hydrophobic silica additive treated with fluorine modifier. Based on the total amount of perfluoropolyether base oil, thickener, and hydrophobic silica additive treated with fluorine modifier, the content of perfluoropolyether base oil is 40wt% to 80wt%, the content of thickener is 19wt% to 50wt%, and the content of hydrophobic silica additive treated with fluorine modifier is 1wt% to 25wt%. The average particle size of the hydrophobic silica additive is 10μm to 1000μm.

2. The lubricating grease according to claim 1, characterized in that, The hydrophobic silica additive has an average particle size of 250 μm-500 μm and / or a specific surface area of ​​20 m². 2 / g~1000m 2 / g, preferably 200m 2 / g~500m 2 / g; and / or The hydrophobic silica additive treated with fluorine modifier is present in the high colloidal stability grease at a content of 5 wt% to 25 wt%.

3. The lubricating grease according to claim 1 or 2, characterized in that, The perfluoropolyether base oil includes at least one of type K, type Y, type Z, and type D perfluoropolyether; and / or, The perfluoropolyether base oil has a molecular weight of 1000 g / mol to 30000 g / mol, preferably 3000 g / mol to 10000 g / mol, and more preferably 4000 g / mol to 8000 g / mol; and / or, The thickener includes at least one of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, bentonite, and boron nitride.

4. The lubricating grease according to any one of claims 1-3, characterized in that, The fluorine modifier is fluorine gas. Preferably, the preparation method of the hydrophobic silica additive treated with the fluorine modifier includes: introducing the fluorine modifier when the hydrophobic silica additive is mixed with the perfluoropolyether base oil. Preferably, the mixing conditions include: a fluorine gas flow rate of 20 ml / min to 300 ml / min relative to 20 g of hydrophobic silica additive, and an introduction time of 1 hour to 4 hours; and / or a temperature of 80°C to 200°C.

5. A method for preparing a high colloidal stability lubricating grease, characterized in that, Includes the following steps: S1. Under the condition of continuous addition of fluorine modifier, the perfluoropolyether base oil and hydrophobic silica additive are mixed to obtain a suspension containing perfluoropolyether base oil and hydrophobic silica additive treated with fluorine modifier. S2. Add a thickener to the suspension obtained in step S1 to thicken it, and then grind it to obtain the high colloidal stability grease.

6. The preparation method according to claim 5, characterized in that, In step S1, the fluorine modifier is fluorine gas. Preferably, the flow rate of fluorine gas is 20 ml / min to 300 ml / min relative to 20 g of hydrophobic silica additive, and the introduction time is 1 hour to 4 hours. And / or, in step S1, the mixing conditions further include a temperature of 80°C to 200°C.

7. The preparation method according to claim 5 or 6, characterized in that, In step S2, the thickening conditions include: temperature 40℃~80℃, vacuum degree 1Pa~1000Pa, and stirring, preferably for 2 hours~10 hours.

8. The preparation method according to any one of claims 5-7, characterized in that, In step S2, the grinding conditions include: a temperature of 20℃-30℃, and / or a grinding time of 0.5 hours to 3 hours.

9. A highly colloidal stable grease prepared by any one of claims 5-8.

10. The application of a high colloidal stability grease according to any one of claims 1-4 and 9 in high-cleanliness environment equipment or high-temperature environment equipment, preferably, the high-cleanliness environment equipment includes high-vacuum equipment for semiconductor manufacturing and equipment for aerospace optical systems; the high-temperature environment equipment includes high-temperature bearings for heat setting machines and high-temperature bearings for extrusion granulators.

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