High-temperature-resistant self-lubricating PA6T material and preparation method thereof
Patent Information
- Application Number
- CN202610797962.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-04
- Publication Date
- 2026-07-03
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer materials technology, specifically relating to a high-temperature resistant self-lubricating PA6T material and its preparation method. Background Technology
[0002] Poly(hexamethylene terephthalamide) (PA6T), as a high-performance semi-aromatic polyamide engineering plastic, has excellent heat resistance, mechanical strength, chemical corrosion resistance and molding processability. It is widely used in high-end fields such as automobile manufacturing, aerospace, electronics and electrical appliances, and precision machinery. It is especially suitable for manufacturing components with stringent requirements for comprehensive material performance, such as engine peripheral parts, oil-free self-lubricating bearings, and precision transmission gears. However, PA6T has a high intrinsic coefficient of friction and poor wear resistance. Under oilless or high-speed friction conditions, it is prone to severe adhesive wear and plowing wear, resulting in a significant reduction in component lifespan and failing to meet the requirements for self-lubricating wear-resistant components. PA6T also has inherent defects of being rigid and brittle, with insufficient notched impact toughness, making it prone to fracture failure under high temperature and high load conditions, making it difficult to balance high-temperature rigidity and toughness. PA6T has a low thermal conductivity, belonging to typical low thermal conductivity polymers, which easily leads to local heat accumulation during friction, causing material softening and performance degradation, further aggravating wear and failure. PA6T is prone to moisture absorption and expansion and thermal contraction in high temperature and high humidity environments, resulting in poor dimensional stability and failing to meet the dimensional accuracy requirements of precision structural components.
[0003] Therefore, PA6T material needs to be modified to compensate for its many performance shortcomings and improve its application in high-end extreme working conditions. In traditional modification methods, a single additive is unlikely to achieve simultaneous improvement in multiple properties. If multiple additives are used in combination, problems such as poor interfacial compatibility and performance antagonism may occur, resulting in the material's overall performance failing to meet expectations, or even leading to the degradation of some properties. This makes it impossible to meet the stringent requirements for the overall performance of materials in high-end applications such as automotive engine peripheral components and aerospace structural parts. Summary of the Invention
[0004] To address the shortcomings mentioned in the background art, the present invention aims to provide a high-temperature resistant self-lubricating PA6T material and its preparation method. The present invention uses PA6T as the base resin and adds modified polytetrafluoroethylene micro powder and composite filler. The two complement each other in function and have synergistic interface, which not only solves the traditional pain points of PA6T such as poor friction and wear and high brittleness, but also improves the material's high-temperature resistance, thermal conductivity and dimensional stability.
[0005] The objective of this invention can be achieved through the following technical solutions: A high-temperature resistant self-lubricating PA6T material comprises the following raw materials in parts by weight: 60-70 parts PA6T resin, 10-15 parts modified glass fiber, 3-5 parts modified polytetrafluoroethylene micro powder, 4-6 parts composite filler, 2-5 parts compatibilizer, 0.3-0.5 parts antioxidant, and 0.2-0.4 parts lubricant; The modified polytetrafluoroethylene micro powder is a copolymer layer of composite nano-ceramic hybrids in situ coated with polytetrafluoroethylene microspheres after surface modification by silane coupling agent. The composite nano-ceramic is nano-SiO2 and nano-Al2O3, and the copolymer is PA6T oligomer, hexafluorobutyl methacrylate and glycidyl acrylate copolymer. The composite filler is composed of porous aluminum nitride and three-dimensional porous graphene, which are self-assembled and modified with bisphenol A type epoxy resin modified silane coupling agent, and finally grafted with PA6T molecular chains by in-situ melt polymerization.
[0006] Preferably, the modified glass fiber is a short-cut glass fiber that has been surface-treated with silane coupling agent KH550; The compatibilizer is POE-g-GMA; The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 2:1; The lubricant is calcium stearate.
[0007] Preferably, the preparation method of the modified polytetrafluoroethylene micro powder includes the following steps: A. Add PTFE microspheres to anhydrous ethanol and ultrasonically disperse for 20-40 min to form a uniform suspension. Add deionized water and vinyltriethoxysilane, heat to 70°C with stirring, and reflux at a constant temperature for 4-8 h. After the reaction is complete, filter under vacuum, wash with anhydrous ethanol 2-4 times, and dry under vacuum to obtain activated PTFE microspheres. B. Add PA6T oligomer to THF, heat to 80°C under nitrogen atmosphere, stir until completely dissolved, add HFBM, GMA and BPO in sequence, stir evenly, add nano Al2O3 and nano SiO2, and ultrasonically disperse for 0.5 to 1.5 h to form a uniform inorganic-organic hybrid dispersion. C. Add the activated PTFE microspheres to the above inorganic-organic hybrid dispersion, heat to 90°C under a nitrogen atmosphere, stir at a constant temperature for 6-10 hours, cool to room temperature after the reaction is completed, add acetone for sedimentation and washing, centrifuge, repeat washing 3 times, vacuum dry, and then pulverize through a 200-mesh sieve to obtain modified polytetrafluoroethylene micro powder.
[0008] Preferably, in step A, the mass ratio of PTFE microspheres to vinyltriethoxysilane is 12.5:1.
[0009] 5. The high-temperature resistant self-lubricating PA6T material according to claim 3, characterized in that the mass ratio of PA6T oligomer, HFBM, GMA, nano Al2O3, nano SiO2 and activated PTFE microspheres in steps B and C is 6:3:1:1:1:20, and the amount of BPO is 2-3% of the total mass of PA6T oligomer, HFBM and GMA.
[0010] Preferably, the method for preparing the composite filler includes the following steps: (1) Nano-AlN and polystyrene microsphere template are uniformly mixed, pressed into shape, calcined at 1200℃ for 3-5h under nitrogen protection, cooled to room temperature, crushed and ground and passed through a 300-mesh sieve to obtain porous aluminum nitride. 3D-G and porous aluminum nitride are dispersed in a mixed solvent of ethanol and water, ultrasonically dispersed for 1.5-2.5h, the solvent is removed by vacuum filtration, and the porous aluminum nitride graphene composite microspheres are obtained by vacuum drying. (2) Add bisphenol A type epoxy resin and KH560 to anhydrous ethanol, stir and heat to 60℃, react for 2-4h to prepare KH560-EP coupling agent complex, add porous aluminum nitride graphene composite microspheres, ultrasonically disperse for 0.5-1.5h, heat to 80℃ and react at a constant temperature for 4-6h, filter, wash with ethanol 3 times, vacuum dry to obtain modified porous aluminum nitride graphene composite microspheres; (3) Add caprolactam, terephthalic acid, and modified porous aluminum nitride graphene composite microspheres to a high-pressure reactor, heat to 260°C under a nitrogen atmosphere, melt and stir for 3-5 hours, maintain a vacuum of -0.06MPa during the reaction, cool to 200°C, stop stirring, and obtain the composite filler precursor. (4) After crushing the composite packing precursor, wash it 5 times with deionized water, centrifuge and vacuum dry it, then use a planetary ball mill for ultrafine grinding and pass it through a 300-mesh sieve to obtain the composite packing.
[0011] Preferably, in step (1), the mass ratio of nano-AlN to polystyrene microspheres is 1:2~3, and the mass ratio of 3D-G to porous aluminum nitride is 1:1~1.2.
[0012] Preferably, in step (2), the mass ratio of bisphenol A epoxy resin, KH560 and porous aluminum nitride graphene composite microspheres is 1:0.8:10.
[0013] Preferably, in step (3), the mass ratio of caprolactam, terephthalic acid and modified porous aluminum nitride graphene composite microspheres is 1.5:0.8:1.
[0014] A method for preparing a high-temperature resistant, self-lubricating PA6T material includes the following steps: S1. Vacuum dry PA6T resin to remove moisture. Mix PA6T resin, modified polytetrafluoroethylene micro powder, composite filler, compatibilizer, antioxidant and lubricant at high speed for 10-20 minutes according to the formula ratio to ensure uniform dispersion of components. S2. Add the uniformly mixed material to a twin-screw extruder. The twin-screw extruder temperature is 260~290℃, the screw speed is 300~400r / min, and the vacuum exhaust is -0.08MPa. The modified glass fiber is added from the feed port. After the molten material is extruded from the extruder head, it is cooled and pelletized by water to obtain modified PA6T pellets. S3. After drying the modified PA6T granules at 110℃ for 2-4 hours, they are injection molded using an injection molding machine at an injection temperature of 270-290℃ and an injection pressure of 80MPa to obtain high-temperature resistant self-lubricating PA6T material.
[0015] The beneficial effects of this invention are: This invention uses PA6T as the base resin and relies on the semi-aromatic nylon structure of PA6T itself. By adding modified polytetrafluoroethylene micro powder and composite filler, the two complement each other and work synergistically at the interface. This not only solves the traditional pain points of PA6T such as poor friction and wear and high brittleness, but also improves the material's high temperature resistance, thermal conductivity and dimensional stability. It can be stably applied to high-performance applications such as wear-resistant parts around automotive engines, high-temperature resistant structural parts for high-end electronic appliances, precision transmission gears, and oil-free self-lubricating bearings.
[0016] The modified polytetrafluoroethylene (PTFE) micropowder of this invention is a copolymer layer of composite nano-ceramic hybrids after PTFE microspheres are surface modified with a silane coupling agent. The composite nano-ceramic consists of nano-SiO2 and nano-Al2O3, and the copolymer consists of PA6T oligomer, hexafluorobutyl methacrylate, and glycidyl acrylate copolymer. It adopts a core-shell structure with a PTFE core and a fluorosilicone-amide copolymer shell. Under the action of frictional shear force, the internal PTFE core migrates to the material surface and works synergistically with the fluorocarbon groups provided by the hexafluorobutyl methacrylate shell to form a continuous, dense, low-shear-strength fluorine-based lubricating film on the surface of the mating parts. This lubricating film transforms the hard contact between the PA6T matrix and its mating components into slippage within the lubricating film, significantly reducing interfacial friction resistance and achieving an ultra-low coefficient of friction. The outer shell is grafted with PA6T oligomers and glycidyl acrylate. The PA6T oligomers can form molecular chain entanglements with the PA6T matrix, and the epoxy groups of GMA can undergo ring-opening reactions with the amide bonds of PA6T, forming stable covalent bonds. Simultaneously, the siloxane network of the intermediate transition layer firmly anchors the PTFE core, preventing the lubricating phase from being peeled off, migrated, or agglomerated during friction, ensuring the long-term stability of the lubricating film and solving the problems of poor compatibility and easy detachment of traditional PTFE and PA6T. Addressing industry pain points; the shell-doped nano-Al2O3 and hydrophobic nano-SiO2 can significantly improve the surface hardness of the material, enhance its resistance to abrasive scratches and plastic deformation, and reduce the generation of wear debris; at the same time, the fluorosilicone shell has excellent high-temperature stability, which can prevent the lubricating film from decomposing and failing when friction heats up, further improving the long-term wear resistance; when subjected to impact loads, the microsphere structure can induce a large number of micro-silver crevice and local shear yield inside the material. These micro-silver crevice and shear yield zones can dissipate a large amount of impact energy without causing the overall material to fracture, thus achieving the dual function of lubrication and toughening, making up for the defect of traditional lubricating additives that easily lead to a decrease in material toughness.
[0017] The filler of this invention is composed of porous aluminum nitride and three-dimensional porous graphene, which are self-assembled and modified by bisphenol A type epoxy resin modified silane coupling agent. Finally, PA6T molecular chains are grafted by in-situ melt polymerization. Its three-dimensional graphene has extremely high strength and modulus, and forms a continuous rigid framework with porous AlN, which runs through the entire PA6T matrix. In high-temperature environments, this rigid framework physically restricts the unentanglement, slippage, and thermal motion of PA6T molecular chains, significantly improving the material's high-temperature creep resistance and heat deformation temperature. Simultaneously, the porous AlN itself possesses extremely high thermal stability and hardness, further enhancing the material's high-temperature load-bearing capacity and thermal stability, preventing softening and degradation during high-temperature processing and service. The three-dimensional network structure allows impact cracks to deflect and bridge multiple times during propagation, extending the crack propagation path and dissipating a large amount of impact energy. The PA6T molecular chains grafted onto the filler surface exhibit good flexibility, undergoing plastic deformation under external force, further dissipating impact energy. Graphene sheets undergo pull-out and debonding upon impact, a process that also absorbs a significant amount of energy. The porous structure of AlN can also play a stress-dispersing role, reducing local stress concentration. In this process, rapid crack propagation is avoided, ultimately leading to a significant improvement in the material's toughness, transforming it from brittle to quasi-tough. Three-dimensional graphene possesses extremely high in-plane thermal conductivity, and its self-supporting network can construct a continuous high-speed thermal conduction pathway within the PA6T matrix, solving the core problem of poor intrinsic thermal conductivity in polymers. Simultaneously, porous AlN exhibits excellent thermal conductivity, filling the gaps in the three-dimensional graphene network, reducing interfacial thermal resistance, and forming a three-dimensional thermal conduction network of high-speed heat transfer from graphene and uniform heat dissipation from AlN. This significantly improves the overall thermal conductivity of the material, enabling rapid dissipation of localized heat generated during friction and working heat, preventing softening and failure due to localized overheating. Through in-situ melt polymerization, PA6T molecular chains are covalently bonded to the surfaces of three-dimensional graphene and porous AlN, forming a gradient interface structure of PA6T matrix, PA6T grafted chains, and inorganic fillers. This structure can completely eliminate interfacial defects, voids and stress concentrations between inorganic fillers and organic polymers, significantly improve load transfer efficiency and interfacial bonding force, and ensure that the reinforcement, toughening and thermal conductivity functions of the filler are fully utilized, avoiding the performance degradation problems caused by poor compatibility and uneven dispersion of traditional inorganic fillers.
[0018] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation
[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0020] Example 1 A modified glass fiber, which is a short-cut glass fiber surface-treated with silane coupling agent KH550, is prepared by the following steps: a. Immerse 100g of alkali-free glass fiber in 200mL of acetone, ultrasonically clean for 5min, filter, dry at 100℃ for 2h, and cool to room temperature; b. Add 2 mL of silane coupling agent KH550 to a mixed solution of 200 mL of ethanol and 50 mL of deionized water, stir until fully dissolved, and adjust the pH value to 9-10 with ammonia. c. Add the cleaned alkali-free glass fiber, stir at room temperature for 40 minutes, filter, put into an oven, first keep at 80℃ for 20 minutes, then raise the temperature to 120℃ and keep at 60 minutes, cool to room temperature to obtain modified glass fiber.
[0021] Example 2 A modified polytetrafluoroethylene (PTFE) micropowder is prepared by in-situ coating of a composite nano-ceramic hybrid copolymer layer onto PTFE microspheres after surface modification with a silane coupling agent. The composite nano-ceramic consists of nano-SiO2 and nano-Al2O3, and the copolymer is a copolymer of PA6T oligomer, hexafluorobutyl methacrylate, and glycidyl acrylate. The preparation method includes the following steps: A. Add 100g of PTFE microspheres to 500mL of anhydrous ethanol and sonicate for 30min to form a uniform suspension. Add 100mL of deionized water and 9mL of vinyltriethoxysilane, heat to 70℃ with stirring, and reflux at a constant temperature for 6h. After the reaction is completed, filter under vacuum, wash three times with anhydrous ethanol, and dry under vacuum to obtain activated PTFE microspheres. B. Add 30g of PA6T oligomer to 200mL of THF, heat to 80℃ under nitrogen atmosphere, stir until completely dissolved, add 15g of HFBM, 5g of GMA and 1.2g of BPO in sequence, stir evenly, add 5g of nano Al2O3 and 5g of nano SiO2, and ultrasonically disperse for 1h to form a uniform inorganic-organic hybrid dispersion. C. Add 100g of activated PTFE microspheres to the above inorganic-organic hybrid dispersion, heat to 90℃ under nitrogen atmosphere, stir at constant temperature for 8h, cool to room temperature after the reaction is completed, add acetone for sedimentation and washing, centrifuge, repeat washing 3 times, vacuum dry, and then pulverize through a 200-mesh sieve to obtain modified polytetrafluoroethylene micro powder.
[0022] Example 3 A composite filler, consisting of porous aluminum nitride and three-dimensional porous graphene self-assembled and modified with a bisphenol A type epoxy resin-modified silane coupling agent, and finally grafted with PA6T molecular chains by in-situ melt polymerization, is prepared by the following steps: (1) 80g of nano AlN and 200g of polystyrene microsphere template were uniformly mixed, pressed into shape, calcined at 1200℃ for 4h under nitrogen protection, cooled to room temperature, crushed and ground and passed through a 300-mesh sieve to obtain porous aluminum nitride. 100g of 3D-G and 80g of porous aluminum nitride were dispersed in a mixed solvent of ethanol and water, ultrasonically dispersed for 2h, the solvent was removed by vacuum filtration, and the porous aluminum nitride graphene composite microspheres were obtained by vacuum drying. (2) Add 10g of bisphenol A epoxy resin and 8g of KH560 to 200mL of anhydrous ethanol, stir and heat to 60℃, react for 3h to prepare KH560-EP coupling agent complex, add 100g of porous aluminum nitride graphene composite microspheres, ultrasonically disperse for 1h, heat to 80℃ and react at a constant temperature for 3h, filter, wash with ethanol 3 times, vacuum dry to obtain modified porous aluminum nitride graphene composite microspheres; (3) Add 150g caprolactam, 80g terephthalic acid and 100g modified porous aluminum nitride graphene composite microspheres to a high-pressure reactor, heat to 260℃ under nitrogen atmosphere, melt and stir for 4h, maintain vacuum degree of -0.06MPa during the reaction, cool down to 200℃ and stop stirring to obtain composite filler precursor; (4) After crushing the composite packing precursor, wash it 5 times with deionized water, centrifuge and vacuum dry it, then use a planetary ball mill for ultrafine grinding and pass it through a 300-mesh sieve to obtain the composite packing.
[0023] Example 4 A high-temperature resistant self-lubricating PA6T material, characterized in that it comprises the following raw materials in parts by weight: 60 parts PA6T resin, 15 parts modified glass fiber, 3 parts modified polytetrafluoroethylene micro powder, 6 parts composite filler, 2 parts POE-g-GMA, 0.3 parts antioxidant 1010, 0.15 parts antioxidant 168, and 0.2 parts calcium stearate; the modified glass fiber is prepared in Example 1, the modified polytetrafluoroethylene micro powder is prepared in Example 2, and the composite filler is prepared in Example 3.
[0024] The preparation method of the above-mentioned high-temperature resistant self-lubricating PA6T material includes the following steps: S1. Vacuum dry PA6T resin to remove moisture. Mix PA6T resin, modified polytetrafluoroethylene micro powder, composite filler, POE-g-GMA, antioxidant 1010, antioxidant 168 and calcium stearate at high speed for 20 minutes according to the formula ratio to ensure uniform dispersion of components. S2. Add the uniformly mixed material to a twin-screw extruder. The twin-screw extruder temperature is 260~290℃, the screw speed is 300r / min, and the vacuum exhaust is -0.08MPa. The modified glass fiber is added from the feed port. After the molten material is extruded from the extruder head, it is cooled and pelletized by water to obtain modified PA6T pellets. S3. After drying the modified PA6T granules at 110℃ for 4 hours, they were injection molded using an injection molding machine at an injection temperature of 270~290℃ and an injection pressure of 80MPa to obtain high-temperature resistant self-lubricating PA6T material.
[0025] Example 5 A high-temperature resistant self-lubricating PA6T material, characterized in that it comprises the following raw materials in parts by weight: 70 parts PA6T resin, 10 parts modified glass fiber, 5 parts modified polytetrafluoroethylene micro powder, 4 parts composite filler, 5 parts POE-g-GMA, 0.2 parts antioxidant 1010, 0.1 parts antioxidant 168, and 0.4 parts calcium stearate; the modified glass fiber is prepared in Example 1, the modified polytetrafluoroethylene micro powder is prepared in Example 2, and the composite filler is prepared in Example 3.
[0026] The preparation method of the above-mentioned high-temperature resistant self-lubricating PA6T material includes the following steps: S1. Vacuum dry PA6T resin to remove moisture. Mix PA6T resin, modified polytetrafluoroethylene micro powder, composite filler, POE-g-GMA, antioxidant 1010, antioxidant 168 and calcium stearate at high speed for 10 minutes according to the formula ratio to ensure uniform dispersion of components. S2. Add the uniformly mixed material to a twin-screw extruder. The twin-screw extruder temperature is 260~290℃, the screw speed is 400r / min, and the vacuum exhaust is -0.08MPa. The modified glass fiber is added from the feed port. After the molten material is extruded from the extruder head, it is cooled and pelletized by water to obtain modified PA6T pellets. S3. After drying the modified PA6T granules at 110℃ for 2 hours, they were injection molded using an injection molding machine at an injection temperature of 270~290℃ and an injection pressure of 80MPa to obtain a high-temperature resistant self-lubricating PA6T material.
[0027] Example 6 A high-temperature resistant self-lubricating PA6T material, characterized in that it comprises the following raw materials in parts by weight: 65 parts PA6T resin, 12 parts modified glass fiber, 4 parts modified polytetrafluoroethylene micro powder, 5 parts composite filler, 3 parts POE-g-GMA, 0.3 parts antioxidant 1010, 0.15 parts antioxidant 168, and 0.3 parts calcium stearate; the modified glass fiber is prepared in Example 1, the modified polytetrafluoroethylene micro powder is prepared in Example 2, and the composite filler is prepared in Example 3.
[0028] The preparation method of the above-mentioned high-temperature resistant self-lubricating PA6T material includes the following steps: S1. Vacuum dry PA6T resin to remove moisture. Mix PA6T resin, modified polytetrafluoroethylene micro powder, composite filler, POE-g-GMA, antioxidant 1010, antioxidant 168 and calcium stearate at high speed for 15 minutes according to the formula ratio to ensure uniform dispersion of components. S2. Add the uniformly mixed material to a twin-screw extruder. The twin-screw extruder temperature is 260~290℃, the screw speed is 350r / min, and the vacuum exhaust is -0.08MPa. The modified glass fiber is added from the feed port. After the molten material is extruded from the extruder head, it is cooled and pelletized by water to obtain modified PA6T pellets. S3. After drying the modified PA6T granules at 110℃ for 3 hours, they were injection molded using an injection molding machine at an injection temperature of 270~290℃ and an injection pressure of 80MPa to obtain a high-temperature resistant self-lubricating PA6T material.
[0029] Comparative Example 1 A high-temperature resistant self-lubricating PA6T material, characterized in that it comprises the following raw materials in parts by weight: 65 parts PA6T resin, 12 parts modified glass fiber, 5 parts composite filler, 3 parts POE-g-GMA, 0.3 parts antioxidant 1010, 0.15 parts antioxidant 168, and 0.3 parts calcium stearate; the modified glass fiber is prepared in Example 1, and the composite filler is prepared in Example 3.
[0030] The preparation method of the above-mentioned high-temperature resistant self-lubricating PA6T material is the same as that in Example 6, except that modified polytetrafluoroethylene micro powder is not added in step S1.
[0031] Comparative Example 2 A high-temperature resistant self-lubricating PA6T material, characterized in that it comprises the following raw materials in parts by weight: 65 parts PA6T resin, 12 parts modified glass fiber, 4 parts modified polytetrafluoroethylene micro powder, 3 parts POE-g-GMA, antioxidant 1010 and antioxidant 1680.45 parts, and calcium stearate 0.3 parts; the modified glass fiber is prepared in Example 1, and the modified polytetrafluoroethylene micro powder is prepared in Example 2.
[0032] The preparation method of the above-mentioned high-temperature resistant self-lubricating PA6T material is the same as that in Example 6, except that no composite filler is added in step S1.
[0033] Performance testing The mechanical properties, thermal properties, tribological properties, processing and dimensional stability, and thermal conductivity of the high-temperature resistant self-lubricating PA6T materials prepared in Examples 4-6, Comparative Examples 1 and 2 were tested, and the materials were processed into corresponding test samples according to the referenced national / industry standards.
[0034] (1) Mechanical property testing Tensile properties were tested according to GB / T1040.2-2018 using an electronic universal testing machine. The specimen was fixed on the machine fixture, and the tensile rate was set to 50 mm / min. The tensile strength (MPa) and elongation at break (%) were recorded. Bending properties were tested according to GB / T9341-2008 using an electronic universal testing machine. A three-point bending test was performed with a span of 64 mm and a bending rate of 2 mm / min. The bending strength (MPa) and bending modulus (GPa) were recorded. Notched impact properties were tested according to GB / T1843-2008 using a simply supported beam impact testing machine. The specimen was placed on an impact frame, and a pendulum impacted the specimen. The notched impact strength (kJ / m²) was recorded. 2 The test results are shown in Table 1 below.
[0035] Table 1. Test results of mechanical properties of high-temperature resistant self-lubricating PA6T material
[0036] As can be seen from the data in Table 1, the mechanical properties of the materials in Examples 4-6 of this invention are superior to those in Comparative Examples 1 and 2. The composite filler achieves reinforcement and toughening, and the modified polytetrafluoroethylene (PTFE) micropowder assists in toughening without weakening rigidity, synergistically solving the problem of the rigidity and brittleness of traditional reinforced PA6T, achieving a balance between rigidity and toughness. The core-shell structure of the modified PTFE micropowder of this invention forms a good chemical bond with the PA6T matrix, and the rigidity can be slightly improved through micro- and nano-filling. At the same time, its microsphere structure can induce crimping and passivate crack tips to achieve auxiliary toughening. In Comparative Example 1, the lack of modified PTFE micropowder not only resulted in the loss of this toughening and reinforcing effect, but also caused stress concentration under stress due to the lack of buffering effect of lubricating microspheres, leading to a significant decrease in toughness and elongation at break. The three-dimensional network structure of the composite filler in this invention is the core support for the rigidity and toughness of the system. Its three-dimensional graphene and porous aluminum nitride form a continuous rigid skeleton, which can effectively share external stress and improve strength and modulus. At the same time, the grafted PA6T chain segments, the crack deflection of the graphene sheets and the stress dispersion of the porous aluminum nitride can jointly dissipate impact energy and achieve efficient toughening. In contrast, after the composite filler was missing in Comparative Example 2, the system lost the rigid skeleton support and efficient toughening mechanism, the load transfer efficiency decreased, and it was prone to fracture under stress, resulting in a significant reduction in strength, modulus and toughness.
[0037] (2) Thermal performance testing The heat distortion temperature (HDT) test was conducted according to GB / T1634.2-2019, using a heat distortion Vicat softening point tester. A bending load of 1.82 MPa was applied, and the heating rate was 2 °C / min. The temperature ( °C) at which the bending deformation of the sample reached the specified value was recorded. The Vicat softening temperature (VST) test was conducted according to GB / T1633-2000, using a Vicat softening point tester with a load of 1 kg and an indenter cross-sectional area of 1 mm². 2 The heating rate was 50℃ / h, and the temperature (℃) when the indenter penetrated 1mm into the sample was recorded. The thermal decomposition temperature (TGA) test was performed according to ASTM E1131-20 using a synchronous thermal analyzer in a nitrogen atmosphere at a heating rate of 10℃ / min. The test temperature range was 50~800℃, and the 5% thermogravimetric temperature (T5%) and the maximum decomposition temperature (T_max) were recorded. The test results are shown in Table 2 below.
[0038] Table 2. Thermal performance test results of high-temperature resistant self-lubricating PA6T material
[0039] As can be seen from the data in Table 2, the thermal properties of the materials in Examples 4-6 are higher than those in the comparative examples. The three-dimensional network of the composite filler restricts the movement of molecular chains, and the fluorosilicone structure of the modified polytetrafluoroethylene (PTFE) micropowder provides thermal shielding. Together, they enable the heat distortion temperature to exceed 300℃ and exhibit excellent thermal stability. The modified PTFE micropowder of this invention has an excellent thermal shielding effect, which can inhibit the transfer of heat to the PA6T main chain and delay thermo-oxidative degradation. At the same time, its core-shell structure can reduce interface defects and avoid local thermal softening. In contrast, the system of Comparative Example 1, lacking the modified PTFE micropowder, has a weakened thermal shielding ability. The PA6T molecular chains are more prone to thermal motion and thermal degradation at high temperatures, resulting in a significant decrease in both heat distortion temperature and thermal stability. The three-dimensional network of the composite filler in this invention can physically restrict the unentanglement and slippage of PA6T molecular chains at high temperatures. At the same time, porous aluminum nitride has ultra-high thermal stability (decomposition temperature > 2000℃), which can improve the system's high-temperature creep resistance and thermal stability. In contrast, without the composite filler in Comparative Example 2, the movement of PA6T molecular chains at high temperatures is unrestrained, which easily leads to softening and thermal degradation, resulting in a decrease in heat distortion temperature and thermal stability, making it unable to adapt to high-temperature service environments.
[0040] (3) Testing of friction, wear and thermal conductivity Friction and wear performance was tested according to GB / T3960-2016 using a friction and wear testing machine under dry friction conditions. The mating parts were made of 45# steel (surface roughness Ra=0.8μm), with a load of 5N, a sliding speed of 0.5m / s, and a sliding distance of 1000m. The average coefficient of friction was recorded, and the mass difference before and after wear was measured using an electronic balance. The wear volume (mm³) was calculated based on the density. 3The thermal conductivity of the sample was tested according to GB / T11034-2018. The test was conducted using a thermal conductivity meter and the steady-state method at a test temperature of 25℃. The thermal conductivity of the sample (W / (m·K)) was recorded. The test results are shown in Table 3 below.
[0041] Table 3. Test results of friction, wear and thermal conductivity of high temperature resistant self-lubricating PA6T material
[0042] As can be seen from the data in Table 3, compared with the comparative examples, the materials in Examples 4-6 of this invention have excellent wear resistance and thermal conductivity. The modified polytetrafluoroethylene micro powder constructs an ultra-low friction lubricating film, and the composite filler improves surface hardness and thermal conductivity, thereby achieving an ultra-low coefficient of friction and extremely low wear.
[0043] The modified polytetrafluoroethylene (PTFE) micropowder of this invention is the core of the system's self-lubricating performance. Its PTFE core and fluorocarbon shell can form a continuous, low-shear-strength lubricating film at the friction interface, transforming hard contact into slippage within the lubricating film, significantly reducing friction and wear. In Comparative Example 1, without the modified PTFE micropowder, the friction interface loses its lubricating protection, and the PA6T matrix directly contacts the 45# steel mating part rigidly, resulting in severe plowing and adhesive wear, leading to a surge in the friction coefficient and a significant increase in wear. The composite filler of this invention can improve the surface hardness of the material, and its high thermal conductivity can quickly dissipate frictional heat, reducing adhesive wear caused by frictional heat, and assisting the modified PTFE micropowder in improving the lubrication and wear resistance. In Comparative Example 2, without the composite filler, the surface hardness of the material is insufficient, making it prone to plastic loss and abrasive wear during friction. At the same time, frictional heat cannot be dissipated in time, leading to a decrease in the stability of the lubricating film, which in turn increases the friction coefficient and wear.
[0044] The modified polytetrafluoroethylene (PTFE) micropowder of this invention, doped with nano-Al2O3 / SiO2, possesses a certain thermal conductivity, which can assist in heat transfer. Simultaneously, its uniformly dispersed microsphere structure reduces localized thermal resistance caused by the lubricating phase. In Comparative Example 1, without the modified PTFE micropowder, the system loses this auxiliary thermal conductivity, relying solely on glass fiber and a small amount of other components for heat transfer, resulting in a significant decrease in thermal conductivity. The three-dimensional graphene composite filler of this invention constructs a continuous thermal conductivity pathway throughout the matrix, while porous aluminum nitride fills the network gaps, reducing interfacial thermal resistance and forming a highly efficient three-dimensional thermal conductivity network. In Comparative Example 2, without the composite filler, the system loses this continuous thermal conductivity pathway, relying only on sporadic heat transfer from a small amount of inorganic components, leading to a significant decrease in thermal conductivity and failing to address the inherently poor thermal conductivity and localized heat accumulation issues of PA6T.
[0045] (4) Processing and dimensional stability testing Melt flow rate (MFR) was tested according to GB / T3682.1-2018. A melt flow rate meter was used at 320℃ with a load of 2.16 kg. The mass of melt extruded within 10 min was recorded, and the MFR (g / 10 min) was calculated. The sample was aged for 1000 h at 120℃ and 95% relative humidity. The length, width, and thickness of the sample before and after aging were measured. The linear dimensional change rate (%) was calculated as (dimensional change after aging - dimensional change before aging) / dimensional change before aging × 100%. The test results are shown in Table 4 below.
[0046] Table 4. Processing and dimensional stability test results of high-temperature self-lubricating PA6T material
[0047] As shown in Table 4, compared with the examples, Comparative Example 2 exhibits increased melt flow rate and dimensional change rate. The composite filler constructs a thermally conductive pathway, and the modified PTFE micropowder blocks water molecules, synergistically achieving rapid heat dissipation, low moisture absorption, and low deformation. Both additives are PA6T-compatible, uniformly dispersed, and do not cause severe entanglement or clogging. The melt flow rate is moderate. The fluorosilicone shell structure of the modified PTFE micropowder in this invention is dense, effectively blocking water molecule penetration and reducing the hygroscopic expansion and thermal contraction of PA6T. In Comparative Example 1, the absence of modified PTFE micropowder allows water molecules to more easily penetrate the matrix, leading to increased sample dimensional deformation and decreased dimensional stability under high temperature and high humidity conditions. Furthermore, the absence of modified PTFE micropowder reduces the solid phase component of the system, slightly decreases the melt viscosity, and slightly improves the fluidity. However, this improvement comes at the cost of sacrificing other core properties and has no practical application value. The three-dimensional network framework of the composite filler in this invention can effectively constrain the thermal and hygroscopic expansion of PA6T molecular chains, reducing dimensional deformation. In Comparative Example 2, without the composite filler, the system loses its rigid constraint, and PA6T is prone to moisture absorption and thermal shrinkage under high temperature and humidity environments, leading to an increased rate of dimensional change and failing to meet the dimensional accuracy requirements of precision structural parts. Similarly, the slight improvement in processing fluidity is due to the decrease in system viscosity after the filler is removed.
[0048] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.
Claims
1. A high-temperature resistant, self-lubricating PA6T material, characterized in that, The raw materials include the following parts by weight: 60-70 parts PA6T resin, 10-15 parts modified glass fiber, 3-5 parts modified polytetrafluoroethylene micro powder, 4-6 parts composite filler, 2-5 parts compatibilizer, 0.3-0.5 parts antioxidant, and 0.2-0.4 parts lubricant; The modified polytetrafluoroethylene micro powder is a copolymer layer of composite nano-ceramic hybrids in situ coated with polytetrafluoroethylene microspheres after surface modification by silane coupling agent. The composite nano-ceramic is nano-SiO2 and nano-Al2O3, and the copolymer is PA6T oligomer, hexafluorobutyl methacrylate and glycidyl acrylate copolymer. The composite filler is composed of porous aluminum nitride and three-dimensional porous graphene, which are self-assembled and modified with bisphenol A type epoxy resin modified silane coupling agent, and finally grafted with PA6T molecular chains by in-situ melt polymerization.
2. The high-temperature resistant self-lubricating PA6T material according to claim 1, characterized in that, The modified glass fiber is a short-cut glass fiber that has been surface-treated with silane coupling agent KH550; The compatibilizer is POE-g-GMA; The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 2:1; The lubricant is calcium stearate.
3. The high-temperature resistant self-lubricating PA6T material according to claim 1, characterized in that, The preparation method of the modified polytetrafluoroethylene micro powder includes the following steps: A. Add PTFE microspheres to anhydrous ethanol and ultrasonically disperse for 20-40 min to form a uniform suspension. Add deionized water and vinyltriethoxysilane, heat to 70°C with stirring, and reflux at a constant temperature for 4-8 h. After the reaction is complete, filter under vacuum, wash with anhydrous ethanol 2-4 times, and dry under vacuum to obtain activated PTFE microspheres. B. Add PA6T oligomer to THF, heat to 80°C under nitrogen atmosphere, stir until completely dissolved, add HFBM, GMA and BPO in sequence, stir evenly, add nano Al2O3 and nano SiO2, and ultrasonically disperse for 0.5 to 1.5 h to form a uniform inorganic-organic hybrid dispersion. C. Add the activated PTFE microspheres to the above inorganic-organic hybrid dispersion, heat to 90°C under a nitrogen atmosphere, stir at a constant temperature for 6-10 hours, cool to room temperature after the reaction is completed, add acetone for sedimentation and washing, centrifuge, repeat washing 3 times, vacuum dry, and then pulverize through a 200-mesh sieve to obtain modified polytetrafluoroethylene micro powder.
4. The high-temperature resistant self-lubricating PA6T material according to claim 3, characterized in that, In step A, the mass ratio of PTFE microspheres to vinyltriethoxysilane is 12.5:
1.
5. The high-temperature resistant self-lubricating PA6T material according to claim 3, characterized in that, In steps B and C, the mass ratio of PA6T oligomer, HFBM, GMA, nano-Al2O3, nano-SiO2 and activated PTFE microspheres is 6:3:1:1:1:20, and the amount of BPO used is 2-3% of the total mass of PA6T oligomer, HFBM and GMA.
6. The high-temperature resistant self-lubricating PA6T material according to claim 1, characterized in that, The method for preparing the composite filler includes the following steps: (1) Nano-AlN and polystyrene microsphere template are uniformly mixed, pressed into shape, calcined at 1200℃ for 3-5h under nitrogen protection, cooled to room temperature, crushed and ground and passed through a 300-mesh sieve to obtain porous aluminum nitride. 3D-G and porous aluminum nitride are dispersed in a mixed solvent of ethanol and water, ultrasonically dispersed for 1.5-2.5h, the solvent is removed by vacuum filtration, and the porous aluminum nitride graphene composite microspheres are obtained by vacuum drying. (2) Add bisphenol A type epoxy resin and KH560 to anhydrous ethanol, stir and heat to 60℃, react for 2-4h to prepare KH560-EP coupling agent complex, add porous aluminum nitride graphene composite microspheres, ultrasonically disperse for 0.5-1.5h, heat to 80℃ and react at a constant temperature for 4-6h, filter, wash with ethanol 3 times, vacuum dry to obtain modified porous aluminum nitride graphene composite microspheres; (3) Add caprolactam, terephthalic acid, and modified porous aluminum nitride graphene composite microspheres to a high-pressure reactor, heat to 260°C under a nitrogen atmosphere, melt and stir for 3-5 hours, maintain a vacuum of -0.06MPa during the reaction, cool to 200°C, stop stirring, and obtain the composite filler precursor. (4) After crushing the composite packing precursor, wash it 5 times with deionized water, centrifuge and vacuum dry it, then use a planetary ball mill for ultrafine grinding and pass it through a 300-mesh sieve to obtain the composite packing.
7. The high-temperature resistant self-lubricating PA6T material according to claim 6, characterized in that, In step (1), the mass ratio of nano-AlN to polystyrene microspheres is 1:2~3, and the mass ratio of 3D-G to porous aluminum nitride is 1:1~1.
2.
8. The high-temperature resistant self-lubricating PA6T material according to claim 6, characterized in that, In step (2), the mass ratio of bisphenol A epoxy resin, KH560 and porous aluminum nitride graphene composite microspheres is 1:0.8:
10.
9. The high-temperature resistant self-lubricating PA6T material according to claim 6, characterized in that, In step (3), the mass ratio of caprolactam, terephthalic acid and modified porous aluminum nitride graphene composite microspheres is 1.5:0.8:
1.
10. The method for preparing the high-temperature resistant self-lubricating PA6T material according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Vacuum dry PA6T resin to remove moisture. Mix PA6T resin, modified polytetrafluoroethylene micro powder, composite filler, compatibilizer, antioxidant and lubricant at high speed for 10-20 minutes according to the formula ratio to ensure uniform dispersion of components. S2. Add the uniformly mixed material to a twin-screw extruder. The twin-screw extruder temperature is 260~290℃, the screw speed is 300~400r / min, and the vacuum exhaust is -0.08MPa. The modified glass fiber is added from the feed port. After the molten material is extruded from the extruder head, it is cooled and pelletized by water to obtain modified PA6T pellets. S3. After drying the modified PA6T granules at 110℃ for 2-4 hours, they are injection molded using an injection molding machine at an injection temperature of 270-290℃ and an injection pressure of 80MPa to obtain a high-temperature resistant self-lubricating PA6T material.