Lubricating oil additive, lubricating oil and preparation method

Abstract

The present application provides a lubricating oil additive, a lubricating oil and a preparation method. The lubricating oil additive includes fluorinated graphene and bismuth particles dispersed on the layers of fluorinated graphene, and the bismuth particles are chemically bonded to the fluorinated graphene. The present application uses bismuth particles to modify the surface of fluorinated graphene, which has the characteristics of good stability and good lubricity.

Description

Technical Field

[0001] The present application relates to the technical field of lubricating oils, and particularly to a lubricating oil additive, a lubricating oil and a preparation method thereof. Background Art

[0002] Since the base lubricating oil itself has poor performance in withstanding different working environments and weak load-bearing capacity, in order to improve the anti-wear and abrasion resistance of the base lubricating oil, specific lubricating oil additives need to be added for blending to improve the anti-wear and abrasion resistance of the lubricating oil. Fluorinated graphene is a derivative of graphene with a structure similar to that of graphene. It is a lubricating material with excellent tribological properties. This is because fluorine atoms are tightly bonded to the surface of fluorinated graphene, and there is a great repulsive force between the fluorine atoms between the layers. While offsetting the external pressure, it makes it easier for relative sliding to occur between the layers of fluorinated graphene. However, fluorinated graphene has a low surface energy and is oleophobic and hydrophobic, making it difficult to disperse in lubricating oil and having poor stability.

[0003] Therefore, how to provide a lubricating oil with good stability and good wear resistance has become an urgent technical problem to be solved at present. Summary of the Invention

[0004] Based on this, it is necessary to provide a lubricating oil additive, a lubricating oil and a preparation method thereof, which have high stability and high wear resistance.

[0005] In a first aspect, the present application provides a lubricating oil additive, which includes fluorinated graphene and bismuth particles dispersed on the surface of the fluorinated graphene, and the bismuth particles are chemically bonded to the fluorinated graphene.

[0006] In some embodiments, the sheet diameter of the fluorinated graphene is 1 μm to 10 μm.

[0007] Optionally, the sheet diameter of the fluorinated graphene is 1 μm to 3 μm.

[0008] In some embodiments, the mass percentage of fluorine element in the fluorinated graphene is 60% to 70%.

[0009] In some embodiments, the specific surface area of the fluorinated graphene is 300 m 2 / g to 450 m 2 / g.

[0010] In some embodiments, the average particle size D50 of the bismuth particles is 3 nm to 10 nm.

[0011] In some embodiments, the mass ratio between the fluorinated graphene and the bismuth particles is 1:(0.2 to 0.8).

[0012] In some embodiments, the number of layers of the fluorinated graphene is from 1 to 3 layers.

[0013] In a second aspect, the present application provides a method for preparing the lubricating oil additive as described in the first aspect, and the preparation method includes:

[0014] Performing ultrasonic treatment, electrospinning, and fiber heat treatment on a premix containing fluorinated graphene, bismuth particles, and a coupling agent in sequence to obtain the lubricating oil additive.

[0015] In some embodiments, the premix further contains an auxiliary agent.

[0016] Optionally, the auxiliary agent includes at least one of a dispersant, a surfactant, and a solvent.

[0017] In some embodiments, the coupling agent includes one or more of silane coupling agents.

[0018] Optionally, the coupling agent includes 1,1,2,2,3,3,4,4,5,5,6,6,7,7,7 - heptadecafluorodecyltriethoxysilane.

[0019] In some embodiments, the pressure of the ultrasonic treatment is from 0.45 MPa to 0.55 MPa.

[0020] In some embodiments, the ultrasonic power of the ultrasonic treatment is from 3.0 kW to 3.6 kW.

[0021] In some embodiments, the treatment time of the ultrasonic treatment is from 3 h to 5 h.

[0022] In some embodiments, the temperature of the electrospinning is from 60 °C to 65 °C.

[0023] In some embodiments, the injection speed of the electrospinning is from 3.5 ml / h to 4.0 ml / h.

[0024] In some embodiments, the voltage of the electrospinning is from 26 kV to 30 kV.

[0025] In some embodiments, the process of the fiber heat treatment includes:

[0026] Performing first heat treatment, second heat treatment, and third heat treatment on the fibers obtained by the electrospinning in sequence.

[0027] Optionally, the temperature of the first heat treatment is from 100 °C to 110 °C, and the time is from 12 h to 14 h.

[0028] Optionally, the temperature of the second heat treatment is from 250 °C to 300 °C, and the time is from 3 h to 5 h.

[0029] Optionally, the temperature of the third heat treatment is 650°C to 700°C, the time is 3h to 4h, the heating rate is 3°C / min to 5°C / min, and the atmosphere includes a protective gas and a reducing gas.

[0030] In a third aspect, the present application provides a lubricating oil, which includes a base lubricating oil and the lubricating oil additive as described in the first aspect.

[0031] In some embodiments, the mass ratio of the lubricating oil additive in the lubricating oil is 2% to 8%.

[0032] In a fourth aspect, the present application provides a preparation method of the lubricating oil as described in the third aspect, and the preparation method includes:

[0033] Adding the lubricating oil additive to the base lubricating oil, and obtaining the lubricating oil after wet grinding.

[0034] Compared with the traditional technology, the present application has at least the following beneficial effects:

[0035] In the present application, the lubricating oil additive uses fluorinated graphene, and bismuth particles are bonded on the fluorinated graphene sheets, so as to improve the surface properties of fluorinated graphene, improve the dispersion stability of fluorinated graphene, and the bismuth particles can be deposited on the friction surface during the friction process to form an amorphous or non-crystalline film, playing an anti-wear and friction-reducing role, and having the characteristics of good stability and good lubricity. Specific Embodiments

[0036] The following combines embodiments and examples to further describe the present invention in detail. These embodiments and examples are only used to illustrate the present invention and not to limit the scope of the present invention. The purpose of providing these embodiments and examples is to make the understanding of the disclosed content of the present invention more thorough and comprehensive. It should also be understood that the present invention can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without departing from the connotation of the present invention, and the equivalent forms obtained also fall within the protection scope of the present invention. In addition, in the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. It should be understood that the present invention can be implemented without one or more of these details.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0038] In the present invention, "optionally", "optional", "option" mean that it may or may not be present, that is, it refers to any one of two alternative schemes of "present" or "absent". If "optional" appears in multiple places in a technical solution, without special instructions and without contradictions or mutual restrictions, each "optional" is independent of each other.

[0039] In the present invention, in "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc., the terms "first", "second", "third", "fourth", etc. are only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0040] In the present invention, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open-ended technical solution containing the listed features.

[0041] In the present invention, regarding a numerical interval (i.e., a numerical range), without special instructions, the distribution of the optional numerical values within this numerical interval is considered continuous, and it includes the two numerical endpoints of this numerical interval (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Without special instructions, when the numerical interval only refers to the integers within this numerical interval, it includes the two endpoint integers of this numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in the present application should be understood to include any and all sub-ranges subsumed therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" allows for a broad inclusion of quantitative intervals such as percentage intervals, ratio intervals, ratio value intervals, etc.

[0042] All the documents mentioned in the present invention are cited in this application for reference, just as if each document is cited separately for reference. Unless it conflicts with the invention purpose and / or technical solution of the present application, the cited documents related to the present invention are cited in their entirety and for all purposes. When the present invention involves cited documents, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited together. When the present invention involves cited documents, the examples and preferred methods of the relevant technical features cited can also be incorporated into this application as references, but only to the extent that the present invention can be implemented. It should be understood that when the cited content conflicts with the description in the present application, the present application shall prevail or be adaptively corrected according to the description in the present application.

[0043] In the traditional technology, graphene fluoride is a lubricating material with excellent tribological properties. This is because fluorine atoms are tightly bonded to the surface of the graphene fluoride sheets, and there is a great repulsive force between the fluorine atoms between the layers. While offsetting the external pressure, it makes it easier for relative sliding to occur between the graphene fluoride layers. However, graphene fluoride has a low surface energy and is hydrophobic and oleophobic, so its dispersibility and stability in lubricating oil are poor. Nano-material additives are also additives that can improve the wear resistance of lubricating oil because they are not sensitive to temperature and are not prone to chemical reactions with lubricating oil. However, after nano-materials are added to lubricating oil, their dispersion stability is poor, which in turn affects the addition of nano-materials in lubricating oil. And in this application, by using bismuth particles to modify the surface of graphene fluoride, a multi-component friction-enhancing fiber material is formed, solving the problems of the dispersibility and stability of graphene fluoride and bismuth particles.

[0044] In the first aspect of this application, a lubricating oil additive is provided. The lubricating oil additive includes graphene fluoride and bismuth particles dispersed on the surface of the graphene fluoride, and the bismuth particles are chemically bonded to the graphene fluoride.

[0045] In this application, the lubricating oil additive uses graphene fluoride and bonds bismuth particles on the graphene fluoride sheets, thereby improving the surface properties of graphene fluoride, enhancing the dispersion stability of graphene fluoride, and the bismuth particles can deposit on the friction surface to form an amorphous or non-crystalline film during the friction process, playing a role in anti-wear and friction reduction, and having characteristics such as good stability and good lubricity.

[0046] In some embodiments, the sheet diameter of the graphene fluoride is 1 μm to 10 μm. For example, it can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm. Optionally, the sheet diameter of the graphene fluoride is 1 μm to 3 μm.

[0047] In some embodiments, the mass fraction of fluorine element in the graphene fluoride is 60% to 70%, for example, it can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69% or 70%.

[0048] In some embodiments, the specific surface area of the graphene fluoride is 300 m 2 / g to 450 m 2 / g, for example, it can be 300 m 2 / g, 310 m 2 / g, 320 m 2 / g, 330 m 2 / g, 340 m 2 / g, 350 m 2 / g, 360 m 2 / g, 370 m2 / g, 380 m 2 / g, 390 m 2 / g, 400 m 2 / g, 410 m 2 / g, 420 m 2 / g, 430 m 2 / g, 440 m 2 / g or 450 m 2 / g.

[0049] In some embodiments, the average particle size D50 of the bismuth particles is 3 nm to 10 nm, for example, it can be 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm.

[0050] In some embodiments, the mass ratio between the fluorinated graphene and the bismuth particles is 1:(0.2 - 0.8), for example, it can be 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7 or 1:0.8.

[0051] This application controls the mass ratio between the fluorinated graphene and the bismuth particles, thus having advantages such as uniform dispersion and excellent lubrication performance. If the content of bismuth particles is relatively high, there may be saturation of the attachment of bismuth particles on the fluorinated graphene sheets, which not only easily causes the sedimentation of the fluorinated graphene sheets but also increases the cost; if the content of bismuth particles is relatively low, there may be a situation where the bismuth particles cannot fully attach to the fluorinated graphene sheets, resulting in a poor lubrication effect.

[0052] In some embodiments, the number of layers of the fluorinated graphene is 1 layer to 3 layers, for example, it can be 1 layer, 2 layers or 3 layers.

[0053] The second aspect of this application provides a preparation method of a lubricating oil additive as described in the first aspect, and the preparation method includes:

[0054] Performing ultrasonic treatment, electrospinning and fiber heat treatment on a premix containing fluorinated graphene, bismuth particles and a coupling agent in sequence to obtain the lubricating oil additive.

[0055] This application uses ultrasonic treatment to fully disperse the fluorinated graphene and bismuth particles and achieve surface modification, and then cures the fibers by electrospinning to pre-dry the material, effectively avoiding the agglomeration problem of the fluorinated graphene and bismuth particles. Furthermore, through fiber heat treatment, the residual solvent is removed and the oxygen-containing groups remaining on the surface of the fluorinated graphene or bismuth particles due to the processing are reduced, achieving the effect of purifying the raw materials.

[0056] In some embodiments, the premix further contains an auxiliary agent.

[0057] Optionally, the auxiliary agent includes at least one of a dispersant, a surfactant, and a solvent.

[0058] In some embodiments, the coupling agent includes one or more of silane coupling agents. Optionally, the coupling agent includes a fluorosilane coupling agent.

[0059] Optionally, the coupling agent includes heptadecafluorodecyltriethoxysilane.

[0060] In some embodiments, by mass parts, the premix includes:

[0061] Fluorinated graphene, 5 parts to 10 parts; bismuth particles 2 parts to 4 parts; dispersant, 4 parts to 8 parts; surfactant, 10 parts to 20 parts; coupling agent 3 parts to 5 parts.

[0062] In some embodiments, the solvent includes at least one of N,N-dimethylformamide, polyethylene glycol, and ethanol.

[0063] Optionally, the solvent includes N,N-dimethylformamide, polyethylene glycol, and ethanol, and the volume ratio of N,N-dimethylformamide, polyethylene glycol, and ethanol is (150 - 180):(50 - 100):(50 - 100).

[0064] In some embodiments, the pressure of the ultrasonic treatment is 0.45 MPa to 0.55 MPa, for example, it can be 0.45 MPa, 0.46 MPa, 0.47 MPa, 0.48 MPa, 0.49 MPa, 0.50 MPa, 0.51 MPa, 0.52 MPa, 0.53 MPa, 0.54 MPa, or 0.55 MPa.

[0065] In some embodiments, the ultrasonic power of the ultrasonic treatment is 3.0 kW to 3.6 kW, for example, it can be 3.0 kW, 3.1 kW, 3.2 kW, 3.3 kW, 3.4 kW, 3.5 kW, or 3.6 kW.

[0066] In some embodiments, the treatment time of the ultrasonic treatment is 3 h to 5 h, for example, it can be 3.0 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4.0 h, 4.2 h, 4.4 h, 4.6 h, 4.8 h, or 5.0 h.

[0067] In some embodiments, the temperature of the electrospinning is 60 °C to 65 °C, for example, it can be 60 °C, 61 °C, 62 °C, 63 °C, 64 °C, or 65 °C.

[0068] In some embodiments, the injection speed of the electrospinning is 3.5 ml / h to 4.0 ml / h, and for example, it can be 3.5 ml / h, 3.6 ml / h, 3.7 ml / h, 3.8 ml / h, 3.9 ml / h or 4.0 ml / h.

[0069] In some embodiments, the voltage of the electrospinning is 26 kV to 30 kV, and for example, it can be 26.0 kV, 26.5 kV, 27.0 kV, 27.5 kV, 28.0 kV, 28.5 kV, 29.0 kV, 29.5 kV or 30.0 kV.

[0070] In some embodiments, the distance between the liquid outlet of the injection needle of the electrospinning and the receiving plate is 22 cm to 24 cm, and for example, it can be 22.0 cm, 22.5 cm, 23.0 cm, 23.5 cm or 24.0 cm.

[0071] In some embodiments, the rotation speed of the spinning receiving roller of the electrospinning is 80 rpm to 100 rpm, and for example, it can be 80 rpm, 85 rpm, 90 rpm, 95 rpm or 100 rpm.

[0072] In some embodiments, the process of the fiber heat treatment includes:

[0073] Performing first heat treatment, second heat treatment and third heat treatment on the fibers obtained by the electrospinning in sequence.

[0074] This application divides the heat treatment into multiple stages of heat treatment, which can remove impurities such as residual dispersants and solvents in the fibers, and at the same time avoid the influence of oxidation by-products on additives during the preparation process. Among them, the first heat treatment is to perform a drying pretreatment on the fibers, the second heat treatment can remove most of the residual solvents and surfactants, and the third heat treatment can completely remove the residual solvents, and at the same time reduce the residual oxygen-containing groups on the surface of the reduced graphene fluoride or bismuth particles to purify the material.

[0075] In some embodiments, the temperature of the first heat treatment is 100 °C to 110 °C, and for example, it can be 100 °C, 101 °C, 102 °C, 103 °C, 104 °C, 105 °C, 106 °C, 107 °C, 108 °C, 109 °C or 110 °C.

[0076] Optionally, the time of the first heat treatment is 12 h to 14 h, and for example, it can be 12.0 h, 12.5 h, 13.0 h, 13.5 h or 14.0 h.

[0077] In some embodiments, the temperature of the second heat treatment is 250 °C to 300 °C, and for example, it can be 250 °C, 260 °C, 270 °C, 280 °C, 290 °C or 300 °C.

[0078] Optionally, the time of the second heat treatment is 3 h to 5 h, and for example, it can be 3.0 h, 3.5 h, 4.0 h, 4.5 h or 5.0 h.

[0079] In some embodiments, the temperature of the third heat treatment is 650 °C to 700 °C, and for example, it can be 650 °C, 655 °C, 660 °C, 665 °C, 670 °C, 675 °C, 680 °C, 685 °C, 690 °C, 695 °C or 700 °C.

[0080] By controlling the temperature of the third heat treatment in the present application, the intermediate reaction impurities can be fully removed without damaging the fluorinated graphene composite structure. If the temperature is relatively low, the impurities generated by the intermediate reaction may not be fully decomposed and removed; if the temperature is relatively high, the stability of the fluorinated graphene composite structure may be damaged.

[0081] Optionally, the time of the third heat treatment is 3 h to 4 h, and for example, it can be 3.0 h, 3.1 h, 3.2 h, 3.3 h, 3.4 h, 3.5 h, 3.6 h, 3.7 h, 3.8 h, 3.9 h or 4.0 h.

[0082] Optionally, the heating rate of the third heat treatment is 3 °C / min to 5 °C / min, and for example, it can be 3.0 °C / min, 3.2 °C / min, 3.4 °C / min, 3.6 °C / min, 3.8 °C / min, 4.0 °C / min, 4.2 °C / min, 4.4 °C / min, 4.6 °C / min, 4.8 °C / min or 5.0 °C / min.

[0083] Optionally, the atmosphere of the third heat treatment includes a protective gas and a reducing gas. Further optionally, the reducing gas includes hydrogen.

[0084] Further optionally, the volume ratio of the protective gas to the hydrogen is 1:(1.05 to 1.2), and for example, it can be 1:1.05, 1:1.06, 1:1.08, 1:1.10, 1:1.12, 1:1.14, 1:1.16, 1:1.18 or 1:1.20.

[0085] The third aspect of the present application provides a lubricating oil, and the lubricating oil includes a base lubricating oil and the lubricating oil additive as described in the first aspect.

[0086] In some embodiments, the mass ratio of the lubricating oil additive in the lubricating oil is 2% to 8%, and for example, it can be 2%, 3%, 4%, 5%, 6%, 7% or 8%.

[0087] In some embodiments, the base lubricating oil includes at least one of polyalphaolefin synthetic base oil, ester synthetic base oil, and silicone oil.

[0088] The fourth aspect of the present application provides a preparation method of the lubricating oil as described in the third aspect, and the preparation method includes:

[0089] Adding the lubricating oil additive to the base lubricating oil, and obtaining the lubricating oil after wet grinding.

[0090] By adopting the wet grinding method in the present application, the particle size of the lubricating oil additive can be ground smaller and finer, avoiding the agglomeration problem caused by conventional dry ball milling, improving the dispersion effect of the lubricating oil additive in the lubricating oil, and having advantages such as high efficiency and good stability.

[0091] In some embodiments, the rotation speed of the wet grinding is 3000 rpm to 5000 rpm, and for example, it can be 3000 rpm, 3200 rpm, 3400 rpm, 3600 rpm, 3800 rpm, 4000 rpm, 4200 rpm, 4400 rpm, 4600 rpm, 4800 rpm, or 5000 rpm.

[0092] In some embodiments, the time of the wet grinding is 6 h to 9 h, and for example, it can be 6.0 h, 6.5 h, 7.0 h, 7.5 h, 8.0 h, 8.5 h, or 9.0 h.

[0093] In some embodiments, the wet grinding is performed using a horizontal grinding machine.

[0094] Exemplarily, a preparation method of the above lubricating oil is provided, including:

[0095] Taking graphene fluoride, bismuth particles, a dispersant, a surfactant, and a coupling agent, adding them to a solvent, and mixing evenly under vacuum conditions to obtain a premix;

[0096] Performing ultrasonic treatment on the premix for 3 h to 5 h under the conditions of 0.45 MPa to 0.55 MPa and 3.0 kW to 3.6 kW to obtain a mixed solution;

[0097] Performing electrospinning on the mixed solution at 60°C to 65°C with a constant injection speed of 3.5 ml / h to 4.0 ml / h and a voltage of 26 kV to 30 kV. During the electrospinning process, the distance between the injection needle and the drum receiving plate is a constant 22 cm to 24 cm, and the rotation speed of the spinning receiving roller is 80 rpm to 100 rpm to obtain nanofibers;

[0098] The nanofibers are first heat-treated at 100°C to 110°C for 12 h to 14 h, and then heat-treated at 250°C to 300°C for 3 h to 5 h. The first heat treatment and the second heat treatment are carried out in a forced-air drying oven. Then, the nanofibers are transferred to a tubular furnace, and heated to 650°C to 700°C at a heating rate of 3°C / min to 5°C / min in an Ar / H2 (volume ratio of 1:1.05 to 1.2) atmosphere, heat-treated for 3 to 4 h, and cooled in the furnace to obtain the lubricating oil additive.

[0099] The lubricating oil additive is added to the base lubricating oil, and wet-ground at a rotational speed of 3000 rpm to 5000 rpm for 6 h to 9 h using a horizontal grinder to obtain the lubricating oil. The mass ratio of the lubricating oil additive in the lubricating oil is 2% to 8%.

[0100] The embodiments of the present invention will be described in detail below in conjunction with the examples. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. For the experimental methods without specific conditions in the following examples, the guidance given in the present invention is preferably referred to, and it can also be carried out according to the experimental manuals or conventional conditions in the art, or according to the conditions recommended by the manufacturer, or referring to the experimental methods known in the art.

[0101] Example 1

[0102] Take 5 g of fluorinated graphene, 2 g of bismuth particles, 4 g of dispersant, 10 g of surfactant, and 3 g of coupling agent, add them to a solvent, and mix evenly under vacuum conditions to obtain a premix. Among them, the sheet diameter of the fluorinated graphene is 5 μm, the fluorine content is 60%, the specific surface area is 300 m 2 / g, the average particle size D50 of the bismuth particles is 5 nm, the dispersant is polyvinylpyrrolidone, the surfactant is polydimethylsiloxane, the coupling agent is heptadecafluorodecyltriethoxysilane, and the solvent is a mixed solution of 150 ml of N,N-dimethylformamide (DMF) + 50 ml of polyethylene glycol + 50 ml of ethanol;

[0103] The premix is ultrasonically treated for 3 h under the conditions of 0.45 MPa and 3.0 kW to obtain a mixed solution;

[0104] The mixed solution is electrospun at 60°C at a constant injection speed of 3.5 ml / h and a voltage of 26 kV. During the electrospinning process, the distance between the injection needle and the drum receiving plate is a constant 22 cm, and the rotational speed of the spinning receiving roller is 80 rpm to obtain nanofibers.

[0105] The nanofibers are first heat-treated at 100 °C for 12 h and then at 250 °C for 3 h. The first and second heat treatments are carried out in a forced-air drying oven. Then, the nanofibers are transferred to a tube furnace and heated to 650 °C at a heating rate of 3 °C / min in an Ar / H2 (volume ratio of 1:1.05) atmosphere, heat-treated for 3 h, and cooled in the furnace to obtain the lubricant additive.

[0106] The lubricant additive is added to a poly-α-olefin synthetic base oil and wet-milled for 6 h at a speed of 3000 rpm using a horizontal grinder with zirconia ball grinding media with a diameter of 0.3 mm to obtain the lubricant. The mass ratio of the lubricant additive in the lubricant is 2%. After wet-milling, the sheet diameter of the fluorinated graphene in the lubricant additive is 2 μm and the number of layers is 2.

[0107] Example 2

[0108] Take 10 g of fluorinated graphene, 4 g of bismuth particles, 8 g of dispersant, 20 g of surfactant, and 5 g of coupling agent, add them to a solvent, and mix evenly under vacuum conditions to obtain a premix. Among them, the sheet diameter of the fluorinated graphene is 10 μm, the fluorine content is 65%, the specific surface area is 400 m 2 / g, the average particle size D50 of the bismuth particles is 7 nm, the dispersant is polyvinylpyrrolidone, the surfactant is polydimethylsiloxane, the coupling agent is heptadecafluorodecyltriethoxysilane, and the solvent is a mixed solution of 150 ml of N,N-dimethylformamide (DMF) + 50 ml of polyethylene glycol + 50 ml of ethanol;

[0109] The premix is ultrasonically treated for 4 h under the conditions of 0.55 MPa and 3.6 kW to obtain a mixed solution;

[0110] The mixed solution is electrospun at 65 °C at a constant injection speed of 4.0 ml / h and a voltage of 28 kV. During the electrospinning process, the distance between the injection needle and the drum receiving plate is a constant 22 cm, and the rotation speed of the spinning receiving roller is 90 rpm to obtain nanofibers;

[0111] The nanofibers are first heat-treated at 110 °C for 14 h and then at 300 °C for 4 h. The first and second heat treatments are carried out in a forced-air drying oven. Then, the nanofibers are transferred to a tube furnace and heated to 700 °C at a heating rate of 5 °C / min in an Ar / H2 (volume ratio of 1:1.2) atmosphere, heat-treated for 3.5 h, and cooled in the furnace to obtain the lubricant additive.

[0112] Add the lubricating oil additive to the base lubricating oil and wet grind it for 9 hours at a speed of 5000 rpm using a horizontal grinder to obtain the lubricating oil. The mass ratio of the lubricating oil additive in the lubricating oil is 5%. After wet grinding, the sheet diameter of the fluorinated graphene in the lubricating oil additive is 1 μm and the number of layers is 1 layer.

[0113] Example 3

[0114] Take 7 g of fluorinated graphene, 3 g of bismuth particles, 6 g of dispersant, 15 g of surfactant and 4 g of coupling agent, add them to a solvent, and mix evenly under vacuum conditions to obtain a premix. Among them, the sheet diameter of the fluorinated graphene is 8 μm, the fluorine content is 70%, and the specific surface area is 450 m 2 / g. The average particle size D50 of the bismuth particles is 3 nm. The dispersant is polyvinylpyrrolidone, the surfactant is polydimethylsiloxane, the coupling agent is heptadecafluorodecyltriethoxysilane, and the solvent is a mixed solution of 150 ml of N,N-dimethylformamide (DMF) + 50 ml of polyethylene glycol + 50 ml of ethanol;

[0115] Perform ultrasonic treatment on the premix for 5 hours under the conditions of 0.5 MPa and 3.3 kW to obtain a mixed solution;

[0116] Perform electrospinning on the mixed solution at 62 °C at a constant injection speed of 3.7 ml / h and a voltage of 30 kV. During the electrospinning process, the distance between the injection needle and the drum receiving plate is a constant 22 cm, and the rotation speed of the spinning receiving roller is 100 rpm to obtain nanofibers;

[0117] First heat-treat the nanofibers at 105 °C for 13 hours, and then perform a second heat treatment at 270 °C for 5 hours. The first heat treatment and the second heat treatment use a blast drying oven; then transfer the nanofibers to a tube furnace, and heat them up to 670 °C at a heating rate of 4 °C / min in an Ar / H2 (volume ratio of 1:1.1) atmosphere, heat-treat for 4 hours, and cool with the furnace to obtain the lubricating oil additive;

[0118] Add the lubricating oil additive to the base lubricating oil and wet grind it for 7 hours at a speed of 4000 rpm using a horizontal grinder to obtain the lubricating oil. The mass ratio of the lubricating oil additive in the lubricating oil is 8%. After wet grinding, the sheet diameter of the fluorinated graphene in the lubricating oil additive is 3 μm and the number of layers is 3 layers.

[0119] Example 4

[0120] Prepare the lubricating oil according to the method of Example 1, except that the mass of the fluorinated graphene is 10 g, the mass of the bismuth particles is 4 g, the mass of the dispersant is 8 g, the mass of the surfactant is 20 g, the mass of the coupling agent is 5 g, and the solvent is 180 ml of N,N-dimethylformamide (DMF) + 100 ml of polyethylene glycol + 100 ml of ethanol. Among them, the sheet diameter of the fluorinated graphene is 10 μm, the fluorine content is 70%, and the specific surface area is 450 m 2 / g.

[0121] Example 5

[0122] Prepare the lubricating oil according to the method of Example 1, except that the pressure of the ultrasonic treatment is 0.55 MPa, the power is 3.6 kW, and the time is 5 h.

[0123] Example 6

[0124] Prepare the lubricating oil according to the method of Example 1, except that the temperature of the electrospinning is 65 °C, the injection speed is 4.0 mL / h, the voltage is 30 kV, the distance between the injection needle and the drum receiving plate is a constant 24 cm, and the rotation speed of the spinning receiving roller is 100 rpm.

[0125] Example 7

[0126] Prepare the lubricating oil according to the method of Example 1, except that during the heat treatment, the temperature of the first heat treatment is 110 °C and the time is 14 h; the temperature of the second heat treatment is 300 °C and the time is 5 h, and the temperature of the third heat treatment is 700 °C and the time is 4 h.

[0127] Example 8

[0128] Prepare the lubricating oil according to the method of Example 1, except that the rotation speed of the wet grinding is 5000 rpm, the time is 9 h, and the mass ratio of the lubricating oil additive in the lubricating oil is 8%.

[0129] Example 9

[0130] Prepare the lubricating oil according to the method of Example 1, except that the mass of the bismuth particles is 0.5 g.

[0131] Example 10

[0132] Prepare the lubricating oil according to the method of Example 1, except that the mass of the bismuth particles is 5 g.

[0133] Example 11

[0134] Prepare the lubricating oil according to the method of Example 1, except that the temperature of the third heat treatment is 600 °C.

[0135] Example 12

[0136] Prepare the lubricating oil according to the method of Example 1, except that the temperature of the third heat treatment is 750 °C.

[0137] Example 13

[0138] Prepare the lubricating oil according to the method of Example 1, except that the dispersant is replaced by sodium dodecylbenzenesulfonate and the coupling agent is replaced by KH560.

[0139] Example 14

[0140] Prepare the lubricating oil according to the method of Example 1, except that the ultrasonic treatment is carried out under normal pressure (atmospheric pressure).

[0141] Example 15

[0142] Prepare the lubricating oil according to the method of Example 1, except that the third heat treatment is not carried out, and the heat treatment includes: the first heat treatment at 100 °C for 12 h, and then the second heat treatment at 250 °C for 3 h.

[0143] Example 16

[0144] Prepare the lubricating oil according to the method of Example 1, except that the wet grinding is replaced by mechanical stirring at 3000 rpm for 6 h.

[0145] Comparative Example 1

[0146] Prepare the lubricating oil according to the method of Example 1, except that the fluorinated graphene is replaced by graphene.

[0147] Comparative Example 2

[0148] Prepare the lubricating oil according to the method of Example 1, except that the bismuth particles are replaced by bismuth oxide.

[0149] Comparative Example 3

[0150] Prepare the lubricating oil according to the method of Example 1, except that the electrospinning step is replaced by freeze-drying treatment, and the parameters of freeze-drying are: vacuum degree 8 Pa, cold trap temperature -60 °C, and drying time 20 h.

[0151] Perform performance tests on the lubricating oils prepared in the above examples and comparative examples. The test methods include:

[0152] Four-ball friction test: Test according to SH / T 0189-2017.

[0153] Dispersion stability test: Place the sample horizontally at room temperature (25 °C) and let it stand for 90 days, and observe the dispersion situation.

[0154] The test results are shown in Table 1.

[0155] Table 1

[0156]

[0157] From the above examples and comparative examples, it can be seen that:

[0158] In this application, fluorinated graphene and nano bismuth powder are selected. Among them, fluorinated graphene has better friction performance than graphene. When it is dry or wet and at high temperature, the friction coefficient is smaller and the service life is longer. Bismuth powder is a material with excellent friction performance and environmental friendliness. It can deposit on the friction surface to form an amorphous or non-crystalline film during friction, thus playing an anti-wear and friction-reducing role. By modifying the two kinds of reinforcing agents, a binary lubricating reinforcing material is prepared, which has the characteristics of good stability and lubricity.

[0159] In addition, in this application, by adding corresponding dispersants, surface modifiers, and solvents, and performing ultrasonic treatment under high-pressure conditions, the two nano materials of fluorinated graphene and nano bismuth powder are fully exfoliated and dispersed in the solution, and surface modification is achieved. Further, electrospinning is a conventional treatment method for fluid electrostatic atomization. The tiny jets of the spinning dope can be solidified into fibers during a long running distance, effectively solving the agglomeration problem of fluorinated graphene and bismuth powder during the drying process of the solution. Moreover, in this application, fiber heat treatment can remove impurities such as residual dispersants and solvents in the mixture, and at the same time avoid the influence of oxidation by-products on the additives during the preparation process. The heat treatment is divided into the first heat treatment, the second heat treatment, and the third heat treatment, which can effectively remove the residual auxiliaries and solvents, and at the same time reduce the oxygen-containing groups remaining on the surface of fluorinated graphene or bismuth powder due to itself or during the processing process, and purify the raw materials. Furthermore, in this application, horizontal wet grinding can perform self-circulating grinding on fluorinated graphene, grind its particle size smaller and finer, avoid the agglomeration problem in conventional dry ball milling, and improve its dispersion in lubricating oil. Compared with ordinary mechanical stirring, it has the advantages of high efficiency and good stability.

[0160] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0161] The above-described embodiments only represent several implementation manners of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of this application patent should be subject to the appended claims.

Claims

1. A preparation method of a lubricating oil additive, characterized in that, The preparation method includes: Subjecting a premix containing graphene fluoride, bismuth particles, and a coupling agent to ultrasonic treatment, electrospinning, and fiber heat treatment in sequence to obtain the lubricating oil additive, where The process of the fiber heat treatment includes: Subjecting the fibers obtained by electrospinning to a first heat treatment, a second heat treatment, and a third heat treatment in sequence; The temperature of the first heat treatment is 100°C to 110°C, and the time is 12 h to 14 h; The temperature of the second heat treatment is 250°C to 300°C, and the time is 3 h to 5 h; The temperature of the third heat treatment is 650°C to 700°C, the time is 3 h to 4 h, the heating rate is 3°C / min to 5°C / min, and the atmosphere includes a protective gas and a reducing gas; where The coupling agent includes heptadecafluorodecyltriethoxysilane, and The mass ratio between the graphene fluoride and the bismuth particles is 1:(0.2 - 0.8).

2. The preparation method according to claim 1, characterized in that, The premix further contains an auxiliary agent.

3. The preparation method according to claim 2, characterized in that, The auxiliary agent includes at least one of a dispersant, a surfactant, and a solvent.

4. The preparation method according to claim 1, characterized in that, The ultrasonic treatment satisfies at least one of the following conditions: (1) The pressure of the ultrasonic treatment is 0.45 MPa to 0.55 MPa; (2) The ultrasonic power of the ultrasonic treatment is 3.0 kW to 3.6 kW; (3) The treatment time of the ultrasonic treatment is 3 h to 5 h.

5. The preparation method according to claim 1, characterized in that, The electrospinning satisfies at least one of the following conditions: (1) The temperature of the electrospinning is 60°C to 65°C; (2) The injection speed of the electrospinning is 3.5 ml / h to 4.0 ml / h; (3) The voltage of the electrospinning is 26 kV to 30 kV.

6. A lubricating oil additive prepared by the preparation method of the lubricating oil additive according to any one of claims 1 to 5, characterized in that, The lubricating oil additive includes graphene fluoride and bismuth particles dispersed on the surface of the graphene fluoride, and the bismuth particles are chemically bonded to the graphene fluoride.

7. The lubricating oil additive according to claim 6, characterized in that, The lubricating oil additive satisfies at least one of the following conditions: (1) The sheet diameter of the graphene fluoride is 1 μm to 10 μm; (2) The mass proportion of fluorine element in the graphene fluoride is 60% to 70%; (3) The specific surface area of the graphene fluoride is 300 m 2 / g to 450 m 2 / g; (4) The average particle size D50 of the bismuth particles is 3 nm to 10 nm; (5) The mass ratio between the graphene fluoride and the bismuth particles is 1:(0.2 - 0.8); (6) The number of layers of the graphene fluoride is 1 layer to 3 layers.

8. The lubricating oil additive according to claim 7, characterized in that, The sheet diameter of the graphene fluoride is 1 μm to 3 μm.

9. A lubricating oil, characterized in that, The lubricating oil includes a base lubricating oil and the lubricating oil additive according to any one of claims 6 to 8.

10. The lubricating oil according to claim 9, characterized in that, The mass proportion of the lubricating oil additive in the lubricating oil is 2% to 8%.

11. A method for preparing the lubricating oil according to claim 9 or 10, characterized in that, The preparation method includes: Adding the lubricating oil additive to the base lubricating oil and obtaining the lubricating oil after wet grinding.

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