A polytetrafluoroethylene and polyacrylonitrile composite friction material, and a preparation method and application thereof
The preparation of polytetrafluoroethylene and polyacrylonitrile composite materials by pre-monomer semi-continuous emulsion polymerization process solves the problems of poor dispersibility and high friction coefficient of lubricating oil additives, achieves high efficiency dispersion and low friction performance of lubricating oil, simplifies the preparation process, and reduces costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NATOR LUBRICATION TECH JIANGSU CO LTD
- Filing Date
- 2023-09-19
- Publication Date
- 2026-07-14
AI Technical Summary
Existing lubricant additives have poor dispersibility, high friction coefficient, and are complicated and toxic in preparation, making it difficult to meet market demand.
Polytetrafluoroethylene (PTFE) and polyacrylonitrile (PAI) composite friction materials were prepared using a pre-monomer semi-continuous emulsion polymerization process. By designing a structure with PTFE emulsion as the core and acrylonitrile as the shell, and using potassium persulfate as an initiator for polymerization, the reaction conditions and the amount of raw materials added were controlled to obtain a composite material with controllable particle size.
The prepared composite material exhibits good dispersibility in lubricating oil, a low coefficient of friction, and excellent anti-friction properties. The process is simple, environmentally friendly, non-toxic, and low-cost, making it suitable as a lubricating oil additive.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer composite materials technology, and specifically discloses a composite friction material of polytetrafluoroethylene and polyacrylonitrile, its preparation method and application. Background Technology
[0002] Improving the wear resistance and reducing the coefficient of friction of lubricating oils are common applications of commercial lubricating oil additives. However, most commercially available lubricating oil additives have a certain degree of toxicity and require complex preparation processes, which seriously hinders their application and development. Therefore, developing a highly efficient and high-performance lubricating oil additive is of great significance.
[0003] Polytetrafluoroethylene (PTFE) is known as the "King of Plastics" due to its excellent overall properties. Because of its good lubrication properties and low coefficient of friction, using PTFE as a lubricant additive to improve the performance of lubricating oils is a very effective method. By uniformly dispersing PTFE in lubricating oil, the viscosity and consistency of the oil can be increased, thereby improving its lubrication and anti-friction properties.
[0004] Currently, the dispersibility and anti-friction properties of domestically produced polytetrafluoroethylene (PTFE) in lubricating oils cannot meet market demands. Therefore, surface modification of PTFE is primarily used to improve its dispersibility and friction properties. However, current modification methods mainly focus on plasma irradiation modification, grafting modification, and treatment with strong acid and alkali solutions, which suffer from drawbacks such as short-term effectiveness, cumbersome operations, and toxicity. Therefore, developing a green, efficient, well-dispersed, and low-friction composite material additive for use in lubricating oils is urgently needed. Summary of the Invention
[0005] This invention addresses the problems of poor dispersion and high friction coefficient in lubricant additives prepared by existing technologies by providing a method for preparing a composite friction material of polytetrafluoroethylene (PTFE) and polyacrylonitrile (PAI) as a lubricant additive using a pre-monomer semi-continuous emulsion polymerization process. This material exhibits good dispersibility in lubricating oil, a low friction coefficient, and excellent anti-friction properties.
[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0007] The composite friction material of polytetrafluoroethylene and polyacrylonitrile is made by polymerizing acrylonitrile and water through a pre-monomer semi-continuous emulsion process with polytetrafluoroethylene emulsion as the core.
[0008] The solid content of the polytetrafluoroethylene emulsion is 40-60%; acrylonitrile should be used after vacuum distillation.
[0009] The preparation of polytetrafluoroethylene and polyacrylonitrile composite friction materials adopts a pre-monomer semi-continuous emulsion polymerization process, which mainly consists of three steps.
[0010] (1) The first step is the nuclear expansion of polytetrafluoroethylene. In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, a certain amount of deionized water is added, and a certain amount of polytetrafluoroethylene emulsion is added to the reaction vessel and ultrasonically dispersed for 10 min-60 min.
[0011] (2) The second part is the secondary core process, in which a portion of the total amount of polyacrylonitrile monomer and a portion of the total amount of initiator are added. The mixture is heated and stirred to a certain temperature.
[0012] Acrylonitrile is used after vacuum distillation, with potassium persulfate as the initiator.
[0013] The added acrylonitrile monomer accounts for 10%-40% of the total, and the added initiator accounts for 10%-30% of the total.
[0014] (3) The third part is the shell growth stage. After the temperature stabilizes, the remaining acrylonitrile and potassium persulfate aqueous solution of the initiator are dripped in using a peristaltic pump to carry out a constant temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is washed repeatedly with a diluent. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0015] The molar mass ratio of polytetrafluoroethylene emulsion, acrylonitrile, initiator, and water is 10-15:5-20:0.002-0.2:50-300.
[0016] The isothermal reaction temperature for polymerization is 60℃-100℃, and the reaction time is 4-8 hours.
[0017] The diluent is ethanol, methanol, tetrahydrofuran, or acetone.
[0018] This invention also provides the application of the prepared polytetrafluoroethylene and polyacrylonitrile composite friction material in the preparation of lubricating oil.
[0019] Beneficial effects:
[0020] (1) This invention obtains a polymer layer by reacting polytetrafluoroethylene emulsion, acrylonitrile, and an initiator. The polymer layer contains –CH2, –CH, and –CN groups, but does not contain hydrophilic polar groups, which greatly improves the oleophilicity of polytetrafluoroethylene@An and significantly enhances the oleophilic properties of the sample. Furthermore, the prepared polytetrafluoroethylene and polyacrylonitrile composite friction material exhibits excellent self-lubricating properties, high chemical activity, and high wear resistance without disrupting the C–F molecular chain skeleton.
[0021] (2) The preparation method of polytetrafluoroethylene and polyacrylonitrile composite friction material provided by the present invention is simple and can avoid the damage to the surface of polytetrafluoroethylene and polyacrylonitrile composite friction material caused by conventional irradiation and plasma treatment in the prior art. The raw material cost is low, it is environmentally friendly, and the product structure and particle size are controllable, so it can be widely used. Attached Figure Description
[0022] Figure 1 The image shows the infrared spectrum of the polytetrafluoroethylene and polyacrylonitrile composite friction material obtained in Example 1.
[0023] Figure 2 This is a TEM image of the polytetrafluoroethylene and polyacrylonitrile composite friction material obtained in Example 1.
[0024] Figure 3 The friction coefficient curves of the polytetrafluoroethylene and polyacrylonitrile composite friction material obtained in Example 1 and the polytetrafluoroethylene material of Comparative Example 1 in polyalphaolefin PAO 6 base oil, under the conditions of 1 wt% additive addition, room temperature, 2 Hz and 100 N.
[0025] Figure 4 The images show the three-dimensional morphology of the wear tracks and the diameter of the grinding plate in the polytetrafluoroethylene and polyacrylonitrile composite friction material obtained in Example 1 and the polytetrafluoroethylene material in Comparative Example 1 in polyalphaolefin PAO 6 base oil at an addition amount of 1 wt% under the conditions of 2 Hz and 100 N. Detailed Implementation
[0026] The present invention will be further described with reference to the following embodiments, but it should be understood that these embodiments are for illustrative purposes only and should not be construed as limiting the implementation of the present invention.
[0027] In this invention, a composite friction material of polytetrafluoroethylene and polyacrylonitrile was synthesized using a pre-monomer semi-continuous emulsion polymerization process. By adjusting the amount of raw materials added and the reaction conditions during the synthesis process, composite friction materials of polytetrafluoroethylene and polyacrylonitrile with different particle sizes can be obtained.
[0028] Unless otherwise specified, all raw materials used in this invention are commercially available products well known to those skilled in the art.
[0029] Example 1
[0030] (1) In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add 100 mL of deionized water and 10 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 30 min.
[0031] (2) Add 1.875 mL of acrylonitrile monomer and 0.001 g of potassium persulfate as initiator. Heat and stir to 75 °C.
[0032] (3) After the temperature stabilizes, the remaining 13.125 mL of acrylonitrile and 0.007 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is repeatedly washed with tetrahydrofuran. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0033] Figure 1 This is the infrared spectrum of the composite friction material. As can be seen from the figure, the composite friction material of polytetrafluoroethylene and polyacrylonitrile has been successfully synthesized.
[0034] Figure 2 This is a TEM image of the composite friction material. The image shows that the composite friction material of polytetrafluoroethylene and polyacrylonitrile was successfully synthesized with a particle size of 150 nm.
[0035] The polytetrafluoroethylene (PTFE) and polyacrylonitrile (PAI) composite friction material prepared according to this invention can be widely used in the field of lubricant additives, greatly improving the tribological effect of lubricating oil and achieving long-lasting friction performance. Because the acrylonitrile-encapsulated surface has -CH2, -CH, and -CN groups, and does not contain hydrophilic polar groups, it significantly improves the oleophilicity of PTFE, thus achieving good dispersion. The acrylonitrile, chemically bonded to the surface of nano-PTFE particles in a shell structure, effectively improves the dispersibility of PTFE in base oils, while also imparting high wear resistance and a low coefficient of friction.
[0036] Example 2
[0037] (1) In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add 150 mL of deionized water and 10 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 60 min.
[0038] (2) Add 2.25 mL of acrylonitrile monomer and 0.0012 g of initiator, and heat and stir to 70 °C.
[0039] (3) After the temperature stabilizes, the remaining 12.75 mL of acrylonitrile and 0.0068 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is washed repeatedly with ethanol. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0040] Example 3
[0041] (1) In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add 200 mL of deionized water and 10 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 30 min.
[0042] (2) Add 2.25 g of acrylonitrile monomer and 0.0012 g of initiator. Heat and stir to 80°C.
[0043] (3) After the temperature stabilizes, the remaining 12.75 mL of acrylonitrile and 0.0068 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is washed repeatedly with acetone. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0044] Example 4
[0045] (1) In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add 50 mL of deionized water and 10 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 30 min.
[0046] (2) Add 2.375 mL of acrylonitrile monomer and 0.0014 g of initiator. Heat and stir to 75 °C.
[0047] (3) After the temperature stabilizes, the remaining 12.625 mL of acrylonitrile and 0.0066 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is repeatedly washed with tetrahydrofuran. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0048] Example 5
[0049] (1) In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add 100 mL of deionized water and 20 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 30 min.
[0050] (2) Add 3 mL of acrylonitrile monomer and 0.0016 g of initiator. Heat and stir to 75 °C.
[0051] (3) After the temperature stabilizes, the remaining 12 mL of acrylonitrile and 0.0064 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is repeatedly washed with tetrahydrofuran. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0052] Example 6
[0053] (1) In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add 100 mL of deionized water and 15 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 30 min.
[0054] (2) Add 3.75 mL of acrylonitrile monomer and 0.002 g of initiator. Heat and stir to 75 °C.
[0055] (3) After the temperature stabilizes, the remaining 11.25 mL of acrylonitrile and 0.006 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is repeatedly washed with tetrahydrofuran. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0056] Example 7
[0057] (1) In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add 100 mL of deionized water and 30 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 60 min.
[0058] (2) Add 1.5 mL of acrylonitrile monomer and 0.0015 g of initiator. Heat and stir to 70 °C.
[0059] (3) After the temperature stabilizes, the remaining 8.5 mL of acrylonitrile and 0.0085 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is repeatedly washed with tetrahydrofuran. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0060] Example 8
[0061] (1) Add 150 mL of deionized water to a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, and add 20 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 40 min.
[0062] (2) Add 3 mL of acrylonitrile monomer and 0.0015 g of initiator. Heat and stir to 70 °C.
[0063] (3) After the temperature stabilizes, the remaining 17 mL of acrylonitrile and 0.0085 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is repeatedly washed with tetrahydrofuran. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0064] Example 9
[0065] (1) The first step is the nuclear expansion of polytetrafluoroethylene. In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add 100 mL of deionized water and add 10 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 30 min.
[0066] (2) Add 3 mL of acrylonitrile monomer and 0.0016 g of initiator. Heat and stir to 90 °C.
[0067] (3) After the temperature stabilizes, the remaining 12 mL of acrylonitrile and 0.0064 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is repeatedly washed with tetrahydrofuran. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0068] Example 10
[0069] (1) In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add 100 mL of deionized water and 10 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 30 min.
[0070] (2) Add 1.875 mL of acrylonitrile monomer and 0.001 g of initiator. Heat and stir to 80 °C.
[0071] (3) After the temperature stabilizes, the remaining 13.125 mL of acrylonitrile and 0.007 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is repeatedly washed with tetrahydrofuran. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0072] Example 11
[0073] (1) In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add 100 mL of deionized water and 10 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 30 min.
[0074] (2) Add 2.25 mL of acrylonitrile monomer and 0.0012 g of initiator. Heat and stir to 60 °C.
[0075] (3) After the temperature stabilizes, the remaining 12.75 mL of acrylonitrile and 0.0068 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is repeatedly washed with tetrahydrofuran. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polyacrylonitrile.
[0076] Comparative Example 1
[0077] Polytetrafluoroethylene (PTFE) micropowder was prepared by a direct drying method. A PTFE emulsion (40% solid content) was dispersed in a beaker and placed in an 80°C oil bath at room temperature and atmospheric pressure. The dispersion was stirred with a magnetic stirrer until dry, thus obtaining the PTFE micropowder.
[0078] Comparative Example 2
[0079] First, polytetrafluoroethylene (PTFE) micropowder was prepared using a direct drying method. A PTFE emulsion (40% solid content) was dispersed in a beaker and placed in an 80°C oil bath at room temperature and atmospheric pressure. The dispersion was stirred with a magnetic stirrer until dry. PTFE micropowder was then obtained. Subsequently, 5g of the PTFE micropowder was mixed with 1g of polyacrylonitrile (PAI) powder to obtain a PTFE and PAI composite material.
[0080] Comparative Example 3
[0081] (1) In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add 100 mL of deionized water and 10 mL of polytetrafluoroethylene emulsion (solid content 40%) to the reaction vessel and ultrasonically disperse for 30 min.
[0082] (2) Add 1.875 mL of styrene monomer and 0.001 g of potassium persulfate initiator, and heat and stir to 75 °C.
[0083] (3) After the temperature stabilizes, 13.125 mL of styrene and 0.007 g of potassium persulfate initiator are added dropwise using a peristaltic pump to carry out a constant-temperature reaction. Throughout the process, the mixture is continuously stirred and nitrogen gas is introduced. After the reaction is completed, the reaction solution is transferred from the reaction vessel and centrifuged. The lower precipitate is repeatedly washed with tetrahydrofuran. Finally, the lower precipitate is removed by centrifugation to obtain a solid product. The solid product is dried to obtain a solid product. The solid product is then crushed into powder to obtain a composite friction material of polytetrafluoroethylene and polystyrene.
[0084] Test case
[0085] This invention utilizes a German Optimol SRV5 tribological testing system to evaluate the tribological performance of a lubricating oil (PAO 6) containing a composite friction material of polytetrafluoroethylene (PTFE) and polyacrylonitrile (PAA) and PTFE micropowder. The addition amount of both the PTFE / PAA composite friction material and the PTFE micropowder was 1%. The experimental load was 200 N, the friction rate was 25 Hz, the experimental time was 30 min, and the experiment was conducted at room temperature. The friction distance was 1 mm. The experimental ball used was made of AISI 52100 steel, with a diameter of 10 mm, a hardness of 60 HRC ± 2, Ra 0.025 μm ± 0.005 μm, and a hardness of HRC 59-61. During the experiment, the friction torque was recorded, and the coefficient of friction was calculated. The wear scar diameter of the steel ball was measured using a microscope, and the average of three measurements was taken.
[0086] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
[0087] Table 1 shows the performance test results of the polytetrafluoroethylene and polyacrylonitrile composite friction materials, polytetrafluoroethylene micropowder, and polytetrafluoroethylene and polystyrene composite friction materials prepared in Examples 1-11 and Comparative Examples 1-3.
[0088]
Claims
1. A composite friction material of polytetrafluoroethylene and polyacrylonitrile, characterized in that, The composite friction material is prepared using a pre-monomer semi-continuous emulsion polymerization process. The specific preparation steps are as follows: (1) In a reaction vessel equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet, add deionized water, add polytetrafluoroethylene emulsion to the reaction vessel and disperse it by ultrasonication. (2) Add a portion of acrylonitrile monomer and a portion of initiator, heat and stir to raise the temperature; after the temperature stabilizes, use a peristaltic pump to drip in the remaining acrylonitrile and initiator to carry out a constant temperature reaction, and continuously stir and introduce nitrogen gas throughout the process; The molar ratio of polytetrafluoroethylene emulsion to acrylonitrile is 10-15:5-20, and the molar ratio of initiator to acrylonitrile is 0.002-0.2:5-20. The isothermal reaction temperature is 60℃-100℃, and the reaction time is 4-8 hours; The acrylonitrile monomer added first accounts for 10%-40% of the total, and the initiator accounts for 10%-30% of the total. (3) After the reaction is completed, the reaction liquid is transferred out and centrifuged. The lower precipitate is washed with a diluent and then centrifuged to obtain a solid product. After drying, the solid product is obtained and crushed into powder to obtain a polytetrafluoroethylene and polyacrylonitrile composite friction material. The obtained polytetrafluoroethylene and polyacrylonitrile composite friction material is used as a lubricating oil additive.
2. The polytetrafluoroethylene and polyacrylonitrile composite friction material according to claim 1, characterized in that, Step (1) The solid content of the polytetrafluoroethylene emulsion is 40%-60%, and the ultrasonic dispersion time is 10 min-60 min.
3. The composite friction material of polytetrafluoroethylene and polyacrylonitrile according to claim 1, characterized in that, Step (2) Acrylonitrile is used after vacuum distillation, and the initiator is potassium persulfate.
4. The polytetrafluoroethylene and polyacrylonitrile composite friction material according to claim 1, characterized in that, The diluent for step (3) is ethanol, methanol, tetrahydrofuran or acetone.