High-temperature-resistant nylon / PTFE (Polytetrafluoroethylene) composite material as well as preparation method and application thereof

Abstract

The invention relates to the field of nylon materials, in particular to a high-temperature-resistant nylon / PTFE composite material and a preparation method and application thereof. The high-temperature-resistant nylon / PTFE composite material is prepared from the following raw materials in parts by weight: 40 to 90 parts of modified nylon, 0.5 to 15 parts of polytetrafluoroethylene, 5 to 15 parts of composite filler, 1 to 3 parts of compatilizer and 0.1 to 0.3 part of antioxidant, the composite filler comprises modified calcium fluoride whiskers, modified glass beads and modified hexagonal boron nitride. Through collaborative design of multiple performance dimensions such as interface, heat resistance, wear resistance, mechanics and the like, the composite material has excellent high-temperature stability, low-friction wear resistance and high-strength mechanical performance at the same time, has remarkable breakthrough in comprehensive performance and service life compared with a traditional nylon-based composite material, and has extremely high technical innovation and practical value.

Description

Technical Field

[0001] This invention relates to the field of nylon materials, specifically to a high-temperature resistant nylon / PTFE composite material, its preparation method, and its applications. Background Technology

[0002] Nylon (polyamide) materials are widely used in mechanical parts, electronics, and the automotive industry due to their excellent mechanical properties, wear resistance, and chemical stability. However, with the increasing demands for high-temperature operating environments and complex working conditions, traditional nylon materials are prone to problems such as decreased mechanical properties, dimensional instability, and increased friction and wear at high temperatures, making it difficult to meet the reliability requirements for long-term use.

[0003] To improve the overall performance of nylon under high-temperature environments, existing technologies mainly employ the following methods: on the one hand, by modifying the polymer through material modification or blending, the thermal stability and toughness of the molecular chain are enhanced; on the other hand, by adding inorganic or organic fillers, mechanical strength, wear resistance, and thermal stability are improved. However, existing methods still have some shortcomings, such as uneven filler dispersion, weak interfacial bonding, and limited improvement in wear resistance and thermal stability, leading to unstable performance of composite materials under high-temperature and high-load conditions.

[0004] Therefore, there is an urgent need for a nylon composite material that can have wear resistance and thermal stability. Summary of the Invention

[0005] In view of this, the present invention aims to provide a high-temperature resistant nylon / PTFE composite material, its preparation method and application, so as to solve the problem of poor high-temperature resistance and wear resistance of nylon materials in the prior art.

[0006] To solve the above-mentioned technical problems, this application is implemented as follows: This invention provides a high-temperature resistant nylon / PTFE composite material, comprising the following raw materials in parts by weight: The mixture contains 40-90 parts modified nylon, 0.5-15 parts polytetrafluoroethylene, 5-15 parts composite filler, 1-3 parts compatibilizer, and 0.1-0.3 parts antioxidant. The composite filler includes modified calcium fluoride whiskers, modified glass microspheres, and modified hexagonal boron nitride.

[0007] In some specific embodiments, the method for preparing the modified nylon includes the following steps: (1) Under an inert atmosphere, nylon was mixed with hexafluoroisopropanol and dispersed to obtain a nylon solution; (2) Under an inert atmosphere, maleic anhydride and glycidyl methacrylate are mixed and dissolved in a solvent to obtain a mixed monomer solution; the nylon solution is heated to 95~105℃, and the mixed monomer solution and initiator solution are added dropwise to carry out the reaction to obtain the first product; (3) Under an inert atmosphere, the first product and the styrene-2-methyl-2-oxazoline block copolymer were mixed and reacted to obtain modified nylon.

[0008] In this invention, the mechanism of action involved in the preparation of modified nylon is as follows: maleic anhydride and glycidyl methacrylate are grafted onto the nylon molecular chain under the action of an initiator, thereby introducing carboxyl groups and highly active epoxy groups into the nylon; subsequently, the oxazoline groups of the styrene-2-methyl-2-oxazoline block copolymer undergo a ring-opening reaction with the grafted carboxyl groups, grafting the styrene-2-methyl-2-oxazoline block copolymer onto the nylon molecular chain.

[0009] In some specific embodiments, in step (1), the ratio of the amount of nylon to the amount of hexafluoroisopropanol is 10g:100~150mL; the inert atmosphere includes nitrogen and / or argon.

[0010] In some specific embodiments, in step (2), the mass ratio of maleic anhydride to nylon in step (1) is 0.2~0.3:10; the mass ratio of glycidyl methacrylate to nylon in step (1) is 0.2~0.3:10; the mass ratio of initiator to maleic anhydride is 0.04~0.06:0.4~0.6; the volume ratio of maleic anhydride to solvent is 1g:50~80mL; the volume ratio of initiator to solvent in the initiator solution is 0.04~0.1g:5~10mL; the initiator in the initiator solution includes benzoyl peroxide; the solvent in the initiator solution includes N,N-dimethylformamide; the inert atmosphere includes nitrogen and / or argon.

[0011] In some specific embodiments, in step (3), the mass ratio of the styrene-2-methyl-2-oxazoline block copolymer to the nylon in step (1) is 0.5~1:10; the mass content of 2-methyl-2-oxazoline in the styrene-2-methyl-2-oxazoline block copolymer is 20~30%; and the inert atmosphere includes nitrogen and / or argon.

[0012] In some specific embodiments, in step (2), the reaction temperature is 100~110℃ and the reaction time is 2~4h.

[0013] In some specific embodiments, in step (3), the temperature of the reaction is 100~110℃ and the reaction time is 1~2h.

[0014] In some specific embodiments, step (3) further includes post-processing after the reaction is completed; the post-processing includes: The product obtained after the reaction was washed and dried under vacuum.

[0015] In some specific embodiments, the mass ratio of the modified calcium fluoride whiskers, the modified glass microspheres, and the modified hexagonal boron nitride is 1~15:5~20:2~15.

[0016] In some specific embodiments, the modified calcium fluoride whiskers include calcium fluoride whiskers modified with aminosilane coupling agents.

[0017] In some specific embodiments, the modified glass microspheres include glass microspheres modified with aminosilane coupling agents.

[0018] In some specific embodiments, the modified hexagonal boron nitride includes hexagonal boron nitride modified with an aminosilane coupling agent.

[0019] In some specific embodiments, the method for preparing the composite filler includes the following steps: The aminosilane coupling agent was mixed with an ethanol / water solution for a second dispersion to obtain a mixed solution. Calcium fluoride whiskers, glass microspheres, and hexagonal boron nitride were mixed with a mixed solution and mechanically stirred. The resulting products were washed and dried to obtain aminosilane coupling agent modified calcium fluoride whiskers, aminosilane coupling agent modified glass microspheres, and aminosilane coupling agent modified hexagonal boron nitride, respectively. Aminosilane coupling agent-modified calcium fluoride whiskers, aminosilane coupling agent-modified glass microspheres, aminosilane coupling agent-modified hexagonal boron nitride, and dispersant were mixed to obtain a mixture; the mixture was then ball-milled to obtain a composite filler.

[0020] In some specific embodiments, the mass ratio of the aminosilane coupling agent to the calcium fluoride whiskers is 0.1~0.2:10.

[0021] In some specific embodiments, the mass ratio of the aminosilane coupling agent to the glass microspheres is 0.1~0.2:10.

[0022] In some specific embodiments, the mass ratio of the aminosilane coupling agent to the hexagonal boron nitride is 0.1~0.2:10.

[0023] In some specific embodiments, the ratio of the aminosilane coupling agent to the ethanol / water solution is 0.1~0.2g:90~150mL.

[0024] In some specific embodiments, the volume ratio of ethanol to water in the ethanol / water solution is 7~9:3~1.

[0025] In some specific embodiments, the temperature of the second dispersion is 20~30°C, and the dispersion time is 15~20 min.

[0026] In some specific embodiments, the temperature of the mechanical stirring is 70~80℃, and the mechanical stirring time is 2~4h.

[0027] In some specific embodiments, the dispersing agent includes zinc stearate.

[0028] In some specific embodiments, the mass ratio of the dispersing agent to the modified calcium fluoride whiskers is 0.3~3:1~15.

[0029] In some specific embodiments, the ball milling conditions are as follows: ball-to-material ratio of 2 to 4:1; grinding balls are zirconium oxide; rotation speed is 150 to 200 rpm; and time is 1 to 3 hours.

[0030] In some specific embodiments, the compatibilizer includes at least one of maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene-octene copolymer, and maleic anhydride-grafted ethylene-propylene-butadiene.

[0031] In some specific embodiments, the antioxidant includes at least one of antioxidant 1010, antioxidant 1076, and antioxidant 168.

[0032] This invention also provides a method for preparing a high-temperature resistant nylon / PTFE composite material, comprising the following steps: Modified nylon, polytetrafluoroethylene, composite filler, compatibilizer and antioxidant are mixed and stirred to disperse, thus obtaining a mixture; The mixture is added to a twin-screw extruder, and after melt blending and extrusion granulation, a high-temperature resistant nylon / PTFE composite material is obtained.

[0033] In some specific embodiments, the stirring and dispersing speed is 800~1200 rpm, and the stirring and dispersing time is 5~15 min.

[0034] In some specific embodiments, the twin-screw extruder is configured with the following conditions: rotational speed 200~300 rpm and extrusion temperature 220~280℃.

[0035] The present invention also provides an application of the above-mentioned high-temperature resistant nylon / PTFE composite material in a high-end encoder knob.

[0036] The beneficial technical effects of the present invention through the above technical solution are as follows: (1) Modified nylon introduces polar functional groups into the nylon molecular chain by grafting maleic anhydride and glycidyl methacrylate onto the molecular chain and further reacting it with styrene-2-methyl-2-oxazoline block copolymer, which enhances the inter-chain forces and thermal stability and improves the heat resistance; at the same time, it significantly improves the interfacial bonding with polytetrafluoroethylene and inorganic fillers, thereby improving the uniformity and overall performance of the composite system.

[0037] (2) Polytetrafluoroethylene (PTFE) plays a role in friction reduction and self-lubrication in the system, which can effectively reduce the coefficient of friction, reduce wear and adhesion; it forms a good dispersion with modified nylon, so that the friction reduction effect can be fully utilized, and improves wear resistance while maintaining the mechanical strength of the material.

[0038] (3) The composite filler consists of one-dimensional modified calcium fluoride whiskers, zero-dimensional modified glass microspheres, and two-dimensional modified hexagonal boron nitride. Modified calcium fluoride whiskers have high strength and high modulus, and can form a reinforcing skeleton in the matrix to improve tensile strength and heat resistance; modified glass microspheres, as spherical structure fillers, can reduce material shrinkage and density, enhance dimensional stability and creep resistance, and play a role in stress transfer and buffering in the system; modified hexagonal boron nitride has excellent thermal conductivity and lubricity, and can form heat conduction channels in the material to improve heat dissipation performance, while reducing the coefficient of friction and enhancing wear resistance. After being modified by aminosilane coupling agent, the three fillers are tightly bonded to the matrix interface, avoiding agglomeration and debonding, and forming a multi-scale structure of "point-line-surface" in the composite material: whiskers provide main load-bearing reinforcement, microspheres fill gaps and disperse stress, and lamellae construct heat conduction and lubrication channels, thereby achieving a synergistic effect of mechanical reinforcement, thermal performance improvement and tribological performance improvement.

[0039] (4) The introduction of compatibilizers can further improve the interfacial compatibility between modified nylon, PTFE and inorganic fillers, making the system uniformly dispersed and structurally stable; antioxidants can inhibit the thermo-oxidative aging reaction during processing and use, delay molecular chain degradation, and ensure the long-term service performance of materials. Detailed Implementation

[0040] This invention discloses a high-temperature resistant nylon / PTFE composite material, its preparation method, and its applications. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0041] The present invention will be further described in detail below through examples. All raw materials used in the examples are commercially available.

[0042] In the following examples, the grafting rate of the maleic anhydride-grafted polypropylene is 0.8%, and the polypropylene is homopolymer polypropylene.

[0043] Preparation Example 1 The preparation of modified nylon includes the following steps: (1) Under a nitrogen atmosphere, 20g of nylon 66 and 200mL of hexafluoroisopropanol were mixed and stirred at 300rpm for 20min to obtain a nylon 66 solution. (2) Under a nitrogen atmosphere, 0.5 g of maleic anhydride and 0.5 g of glycidyl methacrylate were mixed and dissolved in 30 mL of N,N-dimethylformamide to obtain a mixed monomer solution; 0.05 g of benzoyl peroxide was dissolved in 10 mL of N,N-dimethylformamide to obtain a benzoyl peroxide solution; the nylon 66 solution was heated to 95 °C, and the mixed monomer solution and benzoyl peroxide solution were added dropwise over a period of 2 h. After the addition was completed, the mixture was reacted at 105 °C for 3 h to obtain the first product. (3) In a nitrogen atmosphere, 1.5g of styrene-2-methyl-2-oxazoline block copolymer (25% by mass of 2-methyl-2-oxazoline) was added to the first product and mixed. The mixture was then stirred and reacted at 105°C for 2h. After the reaction was completed, the product was washed with water and ethanol in sequence. Finally, it was vacuum dried at 80°C for 12h to obtain modified nylon.

[0044] Preparation Example 2 The preparation of modified nylon includes the following steps: (1) Under a nitrogen atmosphere, 20g of nylon 66 and 200mL of hexafluoroisopropanol were mixed and stirred at 300rpm for 20min to obtain a nylon 66 solution. (2) Under a nitrogen atmosphere, 0.4 g maleic anhydride and 0.6 g glycidyl methacrylate were mixed and dissolved in 30 mL of N,N-dimethylformamide to obtain a mixed monomer solution; 0.06 g benzoyl peroxide was dissolved in 8 mL of N,N-dimethylformamide to obtain a benzoyl peroxide solution; the nylon 66 solution was heated to 95 °C, and the mixed monomer solution and benzoyl peroxide solution were added dropwise over a period of 2 h. After the addition was completed, the mixture was reacted at 100 °C for 4 h to obtain the first product. (3) In a nitrogen atmosphere, 2g of styrene-2-methyl-2-oxazoline block copolymer (20% by mass of 2-methyl-2-oxazoline) was added to the first product and mixed. The mixture was then stirred and reacted at 110°C for 2h. After the reaction was completed, the product was washed with water and ethanol in sequence. Finally, it was vacuum dried at 80°C for 12h to obtain modified nylon.

[0045] Preparation Example 3 The preparation of modified nylon includes the following steps: (1) Under a nitrogen atmosphere, 20g of nylon 66 and 200mL of hexafluoroisopropanol were mixed and stirred at 300rpm for 20min to obtain a nylon 66 solution. (2) Under a nitrogen atmosphere, 0.6 g of maleic anhydride and 0.4 g of glycidyl methacrylate were mixed and dissolved in 30 mL of N,N-dimethylformamide to obtain a mixed monomer solution; 0.04 g of benzoyl peroxide was dissolved in 10 mL of N,N-dimethylformamide to obtain a benzoyl peroxide solution; the nylon 66 solution was heated to 95 °C, and the mixed monomer solution and benzoyl peroxide solution were added dropwise over a period of 2 h. After the addition was completed, the mixture was reacted at 110 °C for 2 h to obtain the first product. (3) In a nitrogen atmosphere, 1g of styrene-2-methyl-2-oxazoline block copolymer (2-methyl-2-oxazoline mass content is 30%) was added to the first product and mixed. Then, the mixture was stirred and reacted at 110°C for 2h. After the reaction was completed, the product was washed with water and ethanol in sequence. Finally, it was vacuum dried at 80°C for 12h to obtain modified nylon.

[0046] Preparation Example 4 The preparation of composite fillers includes the following steps: Mix 0.15g of aminosilane coupling agent KH550 with 100mL of ethanol / water solution (ethanol to water volume ratio of 7:3), and stir and disperse at 25℃ and 200rpm for 15min to obtain a mixed solution; prepare three portions of the above mixed solution. 10g of calcium fluoride whiskers were dried at 100℃ for 2 hours and then mixed with one portion of a mixed solution. The mixture was stirred at 75℃ and 250 rpm for 3 hours. After the reaction, the product was washed with ethanol and then dried at 60℃ to obtain aminosilane coupling agent modified calcium fluoride whiskers. 10g of glass microspheres were dried at 100℃ for 2 hours and then mixed with one portion of a mixed solution. The mixture was stirred at 75℃ and 250 rpm for 3 hours. After the reaction, the product was washed with ethanol and then dried at 60℃ to obtain aminosilane coupling agent modified glass microspheres. 10g of hexagonal boron nitride was dried at 100℃ for 2 hours and then mixed with one portion of a mixed solution. The mixture was stirred at 75℃ and 250 rpm for 3 hours. After the reaction, the product was washed with ethanol and then dried at 60℃ to obtain aminosilane coupling agent modified hexagonal boron nitride. Aminosilane coupling agent modified calcium fluoride whiskers, aminosilane coupling agent modified glass microspheres, aminosilane coupling agent modified hexagonal boron nitride and zinc stearate were mixed in a mass ratio of 8:12:8:1 and ball-milled (ball-to-material ratio of 3:1; grinding balls were zirconium oxide, rotation speed was 200 rpm, and time was 2 h) to obtain composite filler.

[0047] Preparation Example 5 The preparation of composite fillers includes the following steps: Mix 0.15g of aminosilane coupling agent KH550 with 100mL of ethanol / water solution (ethanol to water volume ratio of 7:3), and stir and disperse at 25℃ and 200rpm for 15min to obtain a mixed solution; prepare three portions of the above mixed solution. 10g of calcium fluoride whiskers were dried at 100℃ for 2 hours and then mixed with one portion of a mixed solution. The mixture was stirred at 70℃ and 200 rpm for 2 hours. After the reaction, the product was washed with ethanol and then dried at 60℃ to obtain aminosilane coupling agent modified calcium fluoride whiskers. 10g of glass microspheres were dried at 100℃ for 2 hours and then mixed with one portion of a mixed solution. The mixture was stirred at 70℃ and 200 rpm for 2 hours. After the reaction, the product was washed with ethanol and then dried at 60℃ to obtain aminosilane coupling agent modified glass microspheres. 10g of hexagonal boron nitride was dried at 100℃ for 2 hours and then mixed with one portion of a mixed solution. The mixture was stirred at 70℃ and 200 rpm for 2 hours. After the reaction, the product was washed with ethanol and then dried at 60℃ to obtain aminosilane coupling agent modified hexagonal boron nitride. Aminosilane coupling agent modified calcium fluoride whiskers, aminosilane coupling agent modified glass microspheres, aminosilane coupling agent modified hexagonal boron nitride and zinc stearate were mixed in a mass ratio of 8:8:12:2 and ball-milled (ball-to-material ratio of 2:1; grinding balls were zirconium oxide, rotation speed was 150 rpm, and time was 2 h) to obtain composite filler.

[0048] Preparation Example 6 The preparation of composite fillers includes the following steps: Mix 0.15g of aminosilane coupling agent KH550 with 100mL of ethanol / water solution (ethanol to water volume ratio of 7:3), and stir and disperse at 25℃ and 200rpm for 15min to obtain a mixed solution; prepare three portions of the above mixed solution. 10g of calcium fluoride whiskers were dried at 100℃ for 2 hours and then mixed with one portion of a mixed solution. The mixture was stirred at 80℃ and 150 rpm for 2 hours. After the reaction, the product was washed with ethanol and then dried at 60℃ to obtain aminosilane coupling agent modified calcium fluoride whiskers. 10g of glass microspheres were dried at 100℃ for 2 hours and then mixed with one portion of a mixed solution. The mixture was stirred at 80℃ and 150 rpm for 2-4 hours. After the reaction, the product was washed with ethanol and then dried at 60℃ to obtain aminosilane coupling agent modified glass microspheres. 10g of hexagonal boron nitride was dried at 100℃ for 2 hours and then mixed with one portion of a mixed solution. The mixture was stirred at 80℃ and 150 rpm for 2 hours. After the reaction, the product was washed with ethanol and then dried at 60℃ to obtain aminosilane coupling agent modified hexagonal boron nitride. Aminosilane coupling agent modified calcium fluoride whiskers, aminosilane coupling agent modified glass microspheres, aminosilane coupling agent modified hexagonal boron nitride and zinc stearate were mixed in a mass ratio of 12:8:8:1 and ball-milled (ball-to-material ratio of 4:1; grinding balls were zirconium oxide, rotation speed was 180 rpm, and time was 2.5 h) to obtain composite filler. Example 1

[0049] A high-temperature resistant nylon / PTFE composite material, comprising the following raw materials in parts by weight: The modified nylon 60 parts, polytetrafluoroethylene 5 parts, composite filler 10 parts, maleic anhydride grafted polypropylene compatibilizer 2 parts, and antioxidant 1010 0.2 parts were prepared in Preparation Example 1. A method for preparing high-temperature resistant nylon / PTFE composite materials includes the following steps: Modified nylon, polytetrafluoroethylene, composite filler, compatibilizer and antioxidant are mixed and stirred and dispersed at 1000 rpm for 12 min to obtain a mixture; The mixture is added to a twin-screw extruder, and then melt-blended, extruded, and granulated. The twin-screw extruder is set with the following conditions: rotation speed 220 rpm and extrusion temperature 265℃. A high-temperature resistant nylon / PTFE composite material is obtained. Example 2

[0050] A high-temperature resistant nylon / PTFE composite material, comprising the following raw materials in parts by weight: The modified nylon prepared in Preparation Example 2 consisted of 40 parts, polytetrafluoroethylene 0.5 parts, composite filler prepared in Preparation Example 5 consisted of 5 parts, maleic anhydride-grafted polypropylene compatibilizer 1 part, and antioxidant 1010 0.1 parts. A method for preparing high-temperature resistant nylon / PTFE composite materials includes the following steps: Modified nylon, polytetrafluoroethylene, composite filler, compatibilizer and antioxidant were mixed and stirred and dispersed at 1200 rpm for 7 minutes to obtain a mixture. The mixture is added to a twin-screw extruder, and then melt-blended, extruded, and granulated. The twin-screw extruder is set with the following conditions: rotation speed 280 rpm and extrusion temperature 250°C. A high-temperature resistant nylon / PTFE composite material is obtained. Example 3

[0051] A high-temperature resistant nylon / PTFE composite material, comprising the following raw materials in parts by weight: The modified nylon 90 parts, polytetrafluoroethylene 15 parts, composite filler 15 parts, maleic anhydride grafted polypropylene compatibilizer 3 parts, and antioxidant 1010 0.3 parts were prepared in Preparation Example 3. A method for preparing high-temperature resistant nylon / PTFE composite materials includes the following steps: Modified nylon, polytetrafluoroethylene, composite filler, compatibilizer and antioxidant are mixed and stirred and dispersed at 800 rpm for 15 min to obtain a mixture; The mixture is added to a twin-screw extruder, and then melt-blended, extruded, and granulated. The twin-screw extruder is set with the following conditions: rotation speed 255 rpm and extrusion temperature 240℃. A high-temperature resistant nylon / PTFE composite material is obtained.

[0052] Comparative Example 1 A high-temperature resistant nylon / PTFE composite material, which differs from Example 1 in that: The modified nylon prepared in Preparation Example 1 was replaced with untreated nylon 66.

[0053] Everything else is the same as in Example 1.

[0054] Comparative Example 2 The high-temperature resistant nylon / PTFE composite material differs from that in Example 1 in that: The modified nylon prepared in Preparation Example 1 was replaced with the modified nylon prepared according to the following method; The preparation of modified nylon includes: (1) Under a nitrogen atmosphere, 20g of nylon 66 and 200mL of hexafluoroisopropanol were mixed and stirred at 300rpm for 20min to obtain a nylon 66 solution. (2) Under a nitrogen atmosphere, 0.5 g maleic anhydride and 0.5 g glycidyl methacrylate were mixed and dissolved in 30 mL of N,N-dimethylformamide to obtain a mixed monomer solution; 0.05 g benzoyl peroxide was dissolved in 10 mL of N,N-dimethylformamide to obtain a benzoyl peroxide solution; the nylon 66 solution was heated to 95 °C, and the mixed monomer solution and benzoyl peroxide solution were added dropwise over a period of 2 h. After the addition was completed, the reaction was carried out at 105 °C for 3 h. After the reaction was completed, the product was washed with water and ethanol in sequence, and finally dried under vacuum at 80 °C for 12 h to obtain modified nylon.

[0055] Everything else is the same as in Example 1.

[0056] Comparative Example 3 The high-temperature resistant nylon / PTFE composite material differs from that in Example 1 in that: Replace the composite packing material prepared in Preparation Example 4 with the composite packing material prepared according to the following method; The preparation of composite fillers includes: Calcium fluoride whiskers, glass microspheres, hexagonal boron nitride, and zinc stearate were mixed in a mass ratio of 8:12:8:1 and ball-milled (ball-to-material ratio of 3:1; grinding balls were zirconium oxide, rotation speed was 200 rpm, and time was 2 h) to obtain a composite filler.

[0057] Everything else is the same as in Example 1.

[0058] Comparative Example 4 The high-temperature resistant nylon / PTFE composite material differs from that in Example 1 in that: The composite filler prepared in Preparation Example 4 was replaced with the aminosilane coupling agent modified hexagonal boron nitride in Preparation Example 4.

[0059] Everything else is the same as in Example 1.

[0060] Comparative Example 5 The high-temperature resistant nylon / PTFE composite material differs from that in Example 1 in that: Replace the composite packing material prepared in Preparation Example 4 with the composite packing material prepared according to the following method; The preparation of composite fillers includes: The aminosilane coupling agent modified calcium fluoride whiskers, aminosilane coupling agent modified glass microspheres, and aminosilane coupling agent modified hexagonal boron nitride prepared in Preparation Example 4 were mixed in a mass ratio of 8:12:8 to obtain a composite filler.

[0061] Performance testing (1) Tensile strength test was conducted in accordance with GB / T 1040.2-2006 standard. The specimen was dumbbell type I (gauge length 50mm, width 10mm, thickness 4mm), the tensile rate was 1mm / min, and the average value of 5 specimens was taken.

[0062] (2) The heat distortion temperature was determined according to GB / T 1634.2-2019 standard, with a load of 1.8MPa and a heating rate of 120℃ / h. The temperature of the sample when it was bent by 0.2mm was recorded.

[0063] (3) The coefficient of friction was tested according to the standard GB-3960-83, the sample size was 30mm*6mm*7mm, the upper shaft was kept stationary during the test, the lower shaft rotated at 200r / min, the friction pair performed sliding friction, and the test was conducted for 2 hours with a load of 20 kg. The test results are shown in Table 1.

[0064] Table 1

[0065] 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.

Claims

1. A high-temperature resistant nylon / PTFE composite material, characterized in that, Including the following parts by weight of raw materials: The mixture contains 40-90 parts modified nylon, 0.5-15 parts polytetrafluoroethylene, 5-15 parts composite filler, 1-3 parts compatibilizer, and 0.1-0.3 parts antioxidant. The composite filler includes modified calcium fluoride whiskers, modified glass microspheres, and modified hexagonal boron nitride.

2. The high-temperature resistant nylon / PTFE composite material according to claim 1, characterized in that, The method for preparing the modified nylon includes the following steps: (1) Under an inert atmosphere, nylon was mixed with hexafluoroisopropanol and dispersed to obtain a nylon solution; (2) Under an inert atmosphere, maleic anhydride and glycidyl methacrylate are mixed and dissolved in a solvent to obtain a mixed monomer solution; the nylon solution is heated to 95~105℃, and the mixed monomer solution and initiator solution are added dropwise to carry out the reaction to obtain the first product; (3) Under an inert atmosphere, the first product and the styrene-2-methyl-2-oxazoline block copolymer were mixed and reacted to obtain modified nylon.

3. The high-temperature resistant nylon / PTFE composite material according to claim 2, characterized in that, In step (1), the ratio of nylon to hexafluoroisopropanol is 10g:100~150mL; the inert atmosphere includes nitrogen and / or argon. In step (2), the mass ratio of maleic anhydride to nylon in step (1) is 0.2~0.3:10; the mass ratio of glycidyl methacrylate to nylon in step (1) is 0.2~0.3:10; the mass ratio of initiator to maleic anhydride is 0.04~0.06:0.4~0.6; the volume ratio of maleic anhydride to solvent is 1g:50~80mL; the volume ratio of initiator to solvent in the initiator solution is 0.04~0.1g:5~10mL; the initiator in the initiator solution includes benzoyl peroxide; the solvent in the initiator solution includes N,N-dimethylformamide; the inert atmosphere includes nitrogen and / or argon. In step (3), the mass ratio of the styrene-2-methyl-2-oxazoline block copolymer to the nylon in step (1) is 0.5~1:10; the mass content of 2-methyl-2-oxazoline in the styrene-2-methyl-2-oxazoline block copolymer is 20~30%; the inert atmosphere includes nitrogen and / or argon.

4. The high-temperature resistant nylon / PTFE composite material according to claim 2, characterized in that, In step (2), the reaction temperature is 100~110℃ and the reaction time is 2~4h; In step (3), the reaction temperature is 100~110℃ and the reaction time is 1~2h; In step (3), after the reaction is completed, a post-processing is also included; the post-processing includes: The product obtained after the reaction was washed and dried under vacuum.

5. The high-temperature resistant nylon / PTFE composite material according to claim 1, characterized in that, The mass ratio of the modified calcium fluoride whiskers, the modified glass microspheres, and the modified hexagonal boron nitride is 1~15:5~20:2~15; The modified calcium fluoride whiskers include calcium fluoride whiskers modified with aminosilane coupling agents. The modified glass microspheres include glass microspheres modified with aminosilane coupling agents; The modified hexagonal boron nitride includes hexagonal boron nitride modified with an aminosilane coupling agent.

6. The high-temperature resistant / PTFE composite material according to claim 1, characterized in that, The method for preparing the composite filler includes the following steps: The aminosilane coupling agent was mixed with an ethanol / water solution for a second dispersion to obtain a mixed solution. Calcium fluoride whiskers, glass microspheres, and hexagonal boron nitride were mixed with a mixed solution and mechanically stirred. The resulting products were washed and dried to obtain aminosilane coupling agent modified calcium fluoride whiskers, aminosilane coupling agent modified glass microspheres, and aminosilane coupling agent modified hexagonal boron nitride, respectively. Aminosilane coupling agent-modified calcium fluoride whiskers, aminosilane coupling agent-modified glass microspheres, aminosilane coupling agent-modified hexagonal boron nitride, and dispersant were mixed to obtain a mixture; the mixture was then ball-milled to obtain a composite filler. The mass ratio of the aminosilane coupling agent to the calcium fluoride whiskers is 0.1~0.2:10; The mass ratio of the aminosilane coupling agent to the glass microspheres is 0.1~0.2:10; The mass ratio of the aminosilane coupling agent to the hexagonal boron nitride is 0.1~0.2:10; The ratio of the aminosilane coupling agent to the ethanol / water solution is 0.1~0.2g:90~150mL; The volume ratio of ethanol to water in the ethanol / water solution is 7~9:3~1; The second dispersion temperature is 20~30℃, and the second dispersion time is 15~20min; The temperature of the mechanical stirring is 70~80℃, and the mechanical stirring time is 2~4h; The dispersing agent includes zinc stearate; The mass ratio of the dispersing agent to the modified calcium fluoride whiskers is 0.3~3:1~15; The ball milling conditions are as follows: ball-to-material ratio of 2 to 4:1; grinding balls are zirconium oxide; rotation speed is 150 to 200 rpm; and time is 1 to 3 hours.

7. The high-temperature resistant nylon / PTFE composite material according to claim 1, characterized in that, The compatibilizer includes at least one of maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene-octene copolymer, and maleic anhydride-grafted ethylene-propylene-butadiene. The antioxidant includes at least one of antioxidant 1010, antioxidant 1076, and antioxidant 168.

8. The method for preparing the high-temperature resistant nylon / PTFE composite material according to any one of claims 1 to 7, characterized in that, Includes the following steps: Modified nylon, polytetrafluoroethylene, composite filler, compatibilizer and antioxidant are mixed and stirred to disperse, thus obtaining a mixture; The mixture is added to a twin-screw extruder, and after melt blending and extrusion granulation, a high-temperature resistant nylon / PTFE composite material is obtained.

9. The method for preparing the high-temperature resistant nylon / PTFE composite material according to claim 8, characterized in that, The stirring and dispersing speed is 800~1200 rpm, and the stirring and dispersing time is 5~15 min; The setup conditions for the twin-screw extruder are: rotation speed 200~300 rpm, extrusion temperature 220~280℃.

10. The application of the high-temperature resistant nylon / PTFE composite material according to any one of claims 1 to 7 in high-end encoder knobs.

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