A lubricating additive for high-viscosity perfluoropolyether

Abstract

The present invention discloses a fluorinated biphenyl β-diketone with a polyether structure and side chains. The lubricating additive can be well dispersed in high-viscosity PFPE, effectively reducing friction and wear at the friction interface without affecting the structural stability and lubrication performance of the molecule itself. In particular, for precision machinery such as precision instruments and micromotors that adopt a lifetime lubrication method, fluorinated biphenyl β-diketone can significantly enhance the anti-dispersion property of PFPE on the friction pair surface, ensuring that the oil can be firmly retained at the friction interface, thereby improving the working stability and service life of the equipment. Therefore, it has a good application prospect in the high-end lubrication market.

Description

Technical Field

[0001] The present invention belongs to the technical field of lubricating oils, and particularly relates to a lubricating additive for high-viscosity perfluoropolyether. Background Art

[0002] Reducing friction is of great significance for improving the operating efficiency of machinery and extending the service life of equipment. Compared with hydrocarbon base oils such as mineral oils, polyalphaolefins (PAOs), and polyol esters (POEs), fluorine-based lubricating oils represented by perfluoropolyether (PFPE) have good chemical inertness, low volatility, high thermal stability, strong oxidation stability, and good viscosity-temperature performance due to the strong bond energy characteristics of the C-F bond, and have been widely used in fields such as aviation, aerospace, precision devices, the electronics industry, and the magnetic recording industry.

[0003] However, PFPE also has disadvantages such as poor adsorption ability on metal surfaces, relatively high friction coefficients, and easy flow dispersion during long-term operation, resulting in lubrication failure. In hydrocarbon oils, corresponding lubricating additives can be applied to compensate for the deficiencies in the performance of the base oil, such as molybdenum dialkyldithiocarbamate (MoDTC) friction-reducing additives and zinc dialkyldithiophosphate (ZDDP) anti-wear additives. However, due to the strong polarity of the C-F bond, these additives cannot dissolve in PFPE. To solve this problem, the patent "A Fluorine-based Lubricating Additive and Its Preparation Method" (ZL202010871218..X) discloses a fluorinated β-diketone lubricating additive, whose molecular structure is shown below:

[0004]

[0005] Among them, R1 is C m F 2m+1 or C m F 2m OCF3, R2 is C n F 2n+1 or C n F 2n OCF3, where m and n are positive integers, 0 < m < 19, 0 < n < 19, and 3 < m + n < 30. This fluorinated diketone can undergo a tribochemical reaction with the surface of the metal friction pair using the diketone functional group, reduce the contact of microprotrusions between solids, and form a firm chemical adsorption layer; at the same time, the center of its molecule has a relatively rigid rod-like structure, similar to a liquid crystal, with strong intermolecular forces, and reduces the viscous resistance of the fluid through molecular orientation under shear conditions. Therefore, it can play a good auxiliary lubrication role in PFPE.

[0006] Although fluorinated β-diketone is a very promising fluorine lubricant additive, the fluorinated β-diketone has a short molecular chain and is based on fluorination of an alkyl chain, which has a significant difference in polarity from the polyether segment in PFPE. When the PFPE molecule is small and the viscosity is low, the fluorinated β-diketone has good compatibility with PFPE and can effectively reduce friction and wear. However, for PFPE with longer molecular chains and higher viscosities (viscosity exceeding 150 cSt at 40°C), the compatibility of the fluorinated β-diketone with PFPE decreases significantly, causing stratification in the oil, thereby losing its effectiveness as an additive.

[0007] To enhance compatibility with high-viscosity PFPE, one possible approach is to introduce a polyether structure into the side chain of the fluorinated β-diketone and extend the molecular chain. However, this side chain extension reduces the structural stability of the molecule, making it prone to breakage under the high pressure and shear conditions experienced during friction. Furthermore, the extended side chain also reduces the proportion of the central structure formed by the β-diketone and benzene rings in the overall molecule, shifting the molecule from a rod-like structure to a clustered structure, reducing intermolecular interactions and losing the molecular orientation effect.

[0008] In summary, how to improve the compatibility with high-viscosity PFPE through molecular design while not affecting the lubricating properties of the fluorinated β-diketone itself is an urgent problem that needs to be solved in order to promote the application of this new type of fluorinated lubricant additive to a wider range of applications. Summary of the Invention

[0009] To address the problem that existing fluorinated β-diketones are only soluble in low-viscosity PFPE, the present invention aims to provide a biphenyl β-diketone lubricant additive that can be used in high-viscosity PFPE to improve the friction reduction, anti-wear and anti-dispersion properties of high-viscosity PFPE.

[0010] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0011] A lubricating additive for high-viscosity perfluoropolyether, the molecular structure of which is as follows:

[0012]

[0013] Wherein, R1 and R2 are -CF2-[(OC(C x F 2x+1 )FCF2) m -(OCF2) n ]O-CF3, wherein m, n, and x are all positive integers, m+n=10~20, and x=3~5.

[0014] According to the above solution, the amount of the lubricating additive added to the high-viscosity perfluoropolyether is 0..1 to 20 wt%.

[0015] According to the above solution, the high-viscosity perfluoropolyether is a perfluoropolyether with a viscosity of 150 to 500 cSt at 40°C.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The invention increases the side chains R1 and R2 of the original fluorinated beta-diketone and changes the fluorinated alkyl chain into a fluorinated polyether structure, thereby greatly enhancing the compatibility of the fluorinated beta-diketone with high-viscosity PFPE.

[0018] The present invention introduces a branched chain into the fluorinated polyether structure of the side chain, thereby ensuring the stability of the molecular structure.

[0019] The present invention adds a fluorinated benzene ring into the central structure to form a biphenyl structure with the original benzene ring, so that the long-chain molecule can still maintain sufficient rigidity and lubricity.

[0020] To address the current problem of poor compatibility between fluorinated β-diketones and high-viscosity PFPE lubricants, the present invention designs a fluorinated biphenyl β-diketone with a polyether structure and side chains. This lubricating additive can be well dispersed in high-viscosity PFPE, effectively reducing friction and wear at the friction interface without affecting the structural stability and lubrication properties of the molecule itself. Especially for precision machinery such as precision instruments and micromotors that use lifetime lubrication, fluorinated biphenyl β-diketone can significantly enhance the anti-dispersion properties of PFPE on the friction pair surface, ensuring that the oil can be firmly retained at the friction interface, improving the operating stability and service life of the equipment, and has excellent application prospects in the high-end lubrication market. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 : Comparison of friction and wear performance between the PFPE / fluorinated biphenyl β-diketone composite oil of Example 1 and PFPE lubricating oil.

[0022] Figure 2 : Comparison of the anti-flow performance of the PFPE / fluorinated biphenyl β-diketone composite oil of Example 1 and PFPE lubricating oil. DETAILED DESCRIPTION

[0023] The following examples further illustrate the technical solutions of the present invention but are not intended to limit the scope of protection of the present invention.

[0024] In a specific embodiment, a lubricating additive for high-viscosity perfluoropolyether is provided, and its molecular structure is as follows:

[0025]

[0026] Wherein, R1 and R2 are -CF2-[(OC(C x F 2x+1 )FCF2)m -(OCF2) n ]O-CF3, wherein m, n, and x are all positive integers, m+n=10 to 20, and x=3 to 5. R1 and R2 may have the same or different molecular structures.

[0027] Specifically, the amount of the lubricating additive of the present invention added to the high-viscosity perfluoropolyether is 0.1 to 20 wt%.

[0028] Example 1

[0029] A composite oil was formed using Solvay's M30 PFPE (viscosity 159 cSt at 40°C, molecular weight approximately 9800) as the base oil and fluorinated biphenyl β-diketone (m=7, n=4, x=3 in the side chain R1; m=7, n=4, x=3 in R2) as a lubricating additive (doping amount 5wt%). The composite oil was then compared with pure PFPE in a test.

[0030] The friction and wear performance of lubricating oil is tested by oil pool friction test of steel ball and steel disc. During the test, both ball and disc are immersed in the oil pool. The test conditions are load 20N, rotation radius 3mm, speed 600rpm, and test time 1h, in order to examine the friction and wear performance of lubricating oil under full oil supply. Figure 1 As shown in the figure, compared with pure PFPE, the addition of fluorinated biphenyl β-diketone can reduce the friction coefficient by 23% and the wear spot diameter of the steel ball by 14%.

[0031] The anti-dispersion performance of lubricating oil is tested by dripping oil friction test between steel ball and steel disk. At the beginning of the test, 1 drop of lubricating oil is applied to the steel disk. The test conditions are load 20N, rotation radius 3mm, and rotation speed 2000rpm. The dispersion of lubricating oil is accelerated by limiting the amount of lubricating oil and high-speed rotation to examine the lubrication stability of lubricating oil in a long-term oil-poor state. When the friction coefficient rises to 0.2, it is determined that the lubrication has failed, and the test time at this time is recorded as the dispersion time of lubricating oil. Figure 2 As shown in Figure 3, the addition of fluorinated biphenyl β-diketone can extend the flow time by 4.3 times compared with pure PFPE.

[0032] Ordinary fluorinated β-diketones cannot be dissolved in high-viscosity PFPE, and the two cannot form a composite oil when mixed and separated.

[0033] Example 2

[0034] This example differs from Example 1 in that the fluorinated biphenyl β-diketone additive was added at a dosage of 1 wt %. All other steps, reagents, and parameters were the same as in Example 1. The friction and wear properties of the composite oil prepared in this example were confirmed by oil pool friction testing, showing that the addition of fluorinated biphenyl β-diketone reduced the friction coefficient of PFPE by 17% and wear by 13%. The anti-flow properties of the composite oil were confirmed by oil drip friction testing, showing that the addition of fluorinated biphenyl β-diketone extended the flow time of PFPE by 3.3 times.

[0035] Example 3

[0036] This example differs from Example 1 in that a fluorinated biphenyl β-diketone additive (m=8, n=4, x=3 in the side chain R1) is used. All other steps, reagents, and parameters are the same as in Example 1. The friction and wear properties of the composite oil prepared in this example were confirmed by oil pool friction testing, showing that the addition of fluorinated biphenyl β-diketone reduced the friction coefficient of PFPE by 20% and reduced wear by 15%. The anti-flow properties of the composite oil were confirmed by oil drip friction testing, showing that the addition of fluorinated biphenyl β-diketone extended the flow time of PFPE by 3.8 times.

[0037] Example 4

[0038] This example differs from Example 1 in that a fluorinated biphenyl β-diketone additive (m=7, n=5, x=3 in the side chain R1) is used. All other steps, reagents, and parameters are the same as in Example 1. The friction and wear properties of the composite oil prepared in this example were confirmed by oil pool friction testing, showing that the addition of fluorinated biphenyl β-diketone reduced the friction coefficient of PFPE by 19% and wear by 16%. The anti-flow properties of the composite oil were confirmed by oil drip friction testing, showing that the addition of fluorinated biphenyl β-diketone extended the flow time of PFPE by 3.8 times.

[0039] Example 5

[0040] This example differs from Example 1 in that a fluorinated biphenyl β-diketone additive (m=7, n=4, x=4 in the side chain R1) is used. All other steps, reagents, and parameters are the same as in Example 1. The friction and wear properties of the composite oil prepared in this example were confirmed by oil pool friction testing, showing that the addition of fluorinated biphenyl β-diketone reduced the friction coefficient of PFPE by 18% and the wear by 17%. The anti-flow properties of the composite oil were confirmed by oil drip friction testing, showing that the addition of fluorinated biphenyl β-diketone extended the flow time of PFPE by 3.6 times.

[0041] Example 6

[0042] This example differs from Example 1 in that a fluorinated biphenyl β-diketone additive (m=8, n=5, x=4 in the side chain R2) is used. All other steps, reagents, and parameters are the same as in Example 1. The friction and wear properties of the composite oil prepared in this example were confirmed by oil pool friction testing, showing that the addition of fluorinated biphenyl β-diketone reduced the friction coefficient of PFPE by 18% and the wear by 17%. The anti-flow properties of the composite oil were confirmed by oil drip friction testing, showing that the addition of fluorinated biphenyl β-diketone extended the flow time of PFPE by 3.6 times.

[0043] Example 7

[0044] This Example differs from Example 1 in that the base oil used was Solvay M60 PFPE (viscosity 310 cSt at 40°C, molecular weight approximately 12,500). All other steps, reagents, and parameters were the same as in Example 1. The friction and wear properties of the composite oil prepared in this Example were confirmed by oil pool friction testing, showing that the addition of fluorinated biphenyl β-diketone reduced the PFPE's friction coefficient by 15% and wear by 11%. The composite oil's anti-flow properties were confirmed by oil drip friction testing, showing that the addition of fluorinated biphenyl β-diketone extended the PFPE's flow time by 3.1 times.

Claims

1. A lubricating additive for high viscosity perfluoropolyether, characterized in that The molecular structure is as follows: Wherein, R1 and R2 are -CF2-[(OC(C x F 2x+1 )FCF2) m -(OCF2) n ]O-CF3, where m, n, and x are all positive integers, m+n=10~20, and x=3~5; The amount of the lubricating additive added to the high-viscosity perfluoropolyether is 0.1-20 wt %; The high-viscosity perfluoropolyether is a perfluoropolyether with a viscosity of 150 to 500 cSt at 40°C.

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