Anti-fatigue nylon composite material based on micro-phase regulation and preparation method and application thereof

Abstract

The application belongs to the technical field of nylon materials, and proposes an anti-fatigue nylon composite material based on micro-phase regulation and a preparation method and application thereof, raw materials of the anti-fatigue nylon composite material include, in terms of mass fractions, 50-60 parts of polyamide 66, 30-35 parts of modified glass fiber, 3-5 parts of maleic anhydride grafted polyolefin elastomer, 2-5 parts of modified calcium carbonate, 0.5-0.8 parts of antioxidant, 2-4 parts of heat stabilizer, 0.5-1 part of lubricant, and 0.2-0.8 part of dispersant; the modified glass fiber is obtained by sequentially treating glass fiber raw materials with vinyltriethoxysilane, grafting maleic anhydride, and reacting with polyamide 6; and the modified calcium carbonate is obtained by modifying calcium carbonate raw materials with silane coupling agent KH-550. The anti-fatigue nylon composite material provided by the application has excellent fatigue resistance and meets the requirements of long service life and high reliability of rail transit.

Description

Technical Field

[0001] This invention belongs to the field of nylon material technology, and relates to a fatigue-resistant nylon composite material based on microphase regulation, its preparation method and application. Background Technology

[0002] With the rapid development of high-speed railways and urban rail transit networks, track systems are placing higher demands on the reliability, durability, and safety of key polymer components. Polyamide 66, commonly known as Nylon 66 or PA66 for short, is an engineering plastic with excellent comprehensive performance. Due to its high strength, high rigidity, good heat resistance, and chemical resistance, it has been widely used in key elastic components such as baffle seats, gauge blocks, and sleeves in track fastening systems. These components directly bear the periodic impacts, vibrations, and stresses generated during train operation, and their performance directly affects the stability, safety, and ride comfort of the track system.

[0003] Currently, a common method to improve the mechanical properties of PA66 components is reinforcement modification, with glass fiber (GF) reinforcement being the most mature and widely used. GF reinforcement can significantly improve the tensile strength, stiffness, and dimensional stability of the material. However, this method has obvious limitations: the bond between GF and the PA66 matrix is ​​mainly physical, and the interface region becomes a weak point in the material. Under long-term cyclic loading, it is prone to interfacial debonding or brittle fracture, resulting in limited improvement in fatigue resistance. Especially under low temperature or dynamic stress environments, the material's toughness decreases, and fatigue cracks are more likely to initiate and propagate, seriously affecting the long-term service safety of components under harsh conditions. For example, Chinese patent CN 117659696 A discloses a fatigue-resistant and low-temperature-resistant nylon composite material, its preparation method, and its application. The nylon composite material comprises the following components by weight: 30-60 parts nylon 66, 20-40 parts core-shell particles, 20-35 parts glass fiber, 5-20 parts nylon toughening agent, 0.2-1.0 parts nylon dispersant, 1-2 parts nylon compatibilizer, 2-5 parts nylon heat stabilizer, and 0.2-0.8 parts antioxidant. This nylon composite material exhibits high fatigue resistance and low-temperature resistance, enabling its application in environments as low as -50°C. Furthermore, when applied to baffle seats, the baffle seats demonstrate high impact and fatigue resistance after being conditioned by boiling in water. Although this patent improves the low-temperature toughness of the nylon composite material by introducing core-shell particles, its interfacial bonding is still primarily based on physical processes, and its fatigue resistance under long-term dynamic loads still needs further improvement. For example, Chinese patent CN 114163692 A discloses a method for modifying the surface of glass fibers and its application in PA66. It reveals a glass fiber surface modification technology and its application in PA66, which uses a double-bond coupling agent and maleic anhydride to modify the glass fiber surface. Then, low molecular weight PA6 is grafted onto the glass fiber surface using reactive extrusion technology. The resulting PA6 / glass fiber composite material is then melt-blended with PA66 to obtain a PA66 / GF composite material with good mechanical properties. However, this patent mainly focuses on the static mechanical properties of the composite material and does not address the fatigue resistance of the material under long-term dynamic loads, nor does it consider the comprehensive requirements of rail fastening systems for high toughness, low deformation, and long service life.

[0004] Therefore, there is an urgent need for a nylon composite material with excellent fatigue resistance, simple processing, and suitability for long-term dynamic service environments to meet the increasingly stringent reliability requirements of key elastic components in the rail transportation sector. Summary of the Invention

[0005] This invention proposes a fatigue-resistant nylon composite material based on microphase regulation, its preparation method, and its application. The fatigue-resistant nylon composite material provided by this invention has excellent fatigue resistance, meeting the requirements of long service life and high reliability in rail transit.

[0006] The technical solution of this invention is implemented as follows:

[0007] A fatigue-resistant nylon composite material based on microphase regulation, comprising, by weight parts: 50-60 parts polyamide 66, 30-35 parts modified glass fiber, 3-5 parts maleic anhydride-grafted polyolefin elastomer, 2-5 parts modified calcium carbonate, 0.5-0.8 parts antioxidant, 2-4 parts heat stabilizer, 0.5-1 part lubricant, and 0.2-0.8 parts dispersant;

[0008] The method for preparing the modified glass fiber includes the following steps: treating the glass fiber raw material with vinyltriethoxysilane and grafting it with maleic anhydride to obtain grafted maleic anhydride glass fiber; then reacting the grafted maleic anhydride glass fiber with polyamide 6 in a molten state in the presence of a catalyst to obtain the modified glass fiber.

[0009] The calcium carbonate is obtained by modifying calcium carbonate raw material with silane coupling agent KH-550.

[0010] Preferably, the amounts of vinyltriethoxysilane, maleic anhydride, and polyamide 6 are 0.3%–0.5%, 3%–8%, and 25%–30% of the glass fiber mass, respectively.

[0011] Preferably, the method for preparing the modified glass fiber includes the following steps:

[0012] A. Immerse the glass fiber raw material in a silane coupling agent solution and react at 50-70°C for 1-3 hours to obtain pretreated glass fiber;

[0013] B. The pretreated glass fiber obtained in step A is reacted with maleic anhydride in an inert atmosphere and in the presence of an initiator to obtain maleic anhydride-grafted glass fiber;

[0014] C. The grafted maleic anhydride glass fiber obtained in step B is reacted with polyamide 6 in the molten state in the presence of a catalyst to obtain modified glass fiber.

[0015] Preferably, step A includes: adding vinyltriethoxysilane to a mixed solution of ethanol and water, adjusting the pH to 3-5 with acid, and hydrolyzing to obtain a silane coupling agent solution; immersing the glass fiber raw material in the silane coupling agent solution, reacting at 50-70°C for 1-3 hours, and washing and drying to obtain pretreated glass fiber.

[0016] Preferably, the volume ratio of the ethanol to water mixture in step A is 9:1.

[0017] Preferably, the acid in step A is acetic acid.

[0018] Preferably, the amount of maleic anhydride used is 3% to 5% of the mass of the glass fiber.

[0019] Preferably, step B includes: dispersing the pretreated glass fibers obtained in step A in an organic solvent, adding maleic anhydride and the initiator under an inert atmosphere, refluxing at 100-120°C for 3-6 hours, and then washing and drying to obtain grafted maleic anhydride glass fibers.

[0020] Preferably, in step B, the initiator is dicumyl peroxide.

[0021] Preferably, the amount of initiator used is 2 to 4% of the mass of maleic anhydride.

[0022] Preferably, the amount of initiator used is 3% of the mass of maleic anhydride.

[0023] Preferably, step C includes: premixing the grafted maleic anhydride glass fiber obtained in step B with polyamide 6 and a catalyst, reacting them in a molten state using a screw extruder, and extruding and granulating them to obtain the modified glass fiber.

[0024] Preferably, the catalyst in step C is an organotin compound, and the amount of catalyst used is 0.4 to 0.6% of the mass of polyamide 6.

[0025] Preferably, the organotin compound is dibutyltin dilaurate.

[0026] Preferably, the silane coupling agent KH-550 is 0.5~3 wt% of the calcium carbonate raw material.

[0027] Preferably, the silane coupling agent KH-550 is 2 wt% of the calcium carbonate raw material.

[0028] Preferably, the method for preparing the modified calcium carbonate includes the following steps:

[0029] Mix silane coupling agent KH-550, water, and ethanol, adjust the pH to acidic, and react at 60–80°C for 20–40 minutes to obtain a treatment solution. Disperse calcium carbonate raw material in the treatment solution and stir to react. Wash and dry the product after reaction.

[0030] Preferably, the mass ratio of the silane coupling agent KH-550, water, and ethanol is 1:2 to 4:6 to 8.

[0031] Preferably, the pH is adjusted to 4-5 using acetic acid.

[0032] Preferably, the stirring reaction is carried out at a temperature of 60–80°C for 3–5 hours.

[0033] Preferably, the washing process includes washing with ethanol and water in sequence.

[0034] Preferably, the drying is carried out at 40–60°C for 10–14 hours.

[0035] Preferably, the maleic anhydride-grafted polyolefin elastomer is selected from one or more of KT-906, KT-913 and KT-9.

[0036] Preferably, the antioxidant is selected from one or more of antioxidant 1010, antioxidant 1076 and antioxidant 168.

[0037] Preferably, the heat stabilizer is organotin heat stabilizer JX-181 and / or organocopper salt composite heat stabilizer Finner-336.

[0038] Preferably, the lubricant is selected from one or two of the following: lubricant EBS P130, calcium stearate, and polysiloxane.

[0039] Preferably, the dispersant is HYPER C100 and / or AC540A.

[0040] This invention also provides a method for preparing the aforementioned fatigue-resistant nylon composite material based on microphase regulation, comprising the following steps:

[0041] S1. Premix polyamide 66, maleic anhydride-grafted polyolefin elastomer, modified calcium carbonate, antioxidant, heat stabilizer, lubricant and dispersant to obtain the main material;

[0042] S2. The main material is added from the main feed port of the twin-screw extruder, and the modified glass fiber is added from the side feed port. After melt blending, extrusion, granulation and drying, composite material particles are obtained.

[0043] S3. The composite material particles are injection molded to obtain the nylon composite material.

[0044] Preferably, the modified glass fiber is vacuum dried at 90–110°C for 6–10 hours before use.

[0045] Preferably, in step S2, the parameters of the extrusion process are: screw temperature 230℃~280℃, screw speed 250~320rpm, and vacuum degree not lower than -0.095MPa.

[0046] Preferably, in step S3, the parameters of the injection molding process are: barrel temperature 275℃~300℃, mold temperature 90℃, injection pressure 80~85MPa, injection speed 30~45mm / s, holding pressure 70~85 MPa, holding time 10~15s, and cooling time 40~45s.

[0047] This invention also provides the application of the aforementioned microphase-modulated fatigue-resistant nylon composite material in rail transit track fastening systems.

[0048] Preferably, the nylon composite material is used to manufacture baffle seats, gauge blocks, or insulating sleeves in the track fastening system.

[0049] The beneficial effects of the present invention using the above technical solution are as follows:

[0050] 1. This invention modifies glass fiber using a three-step method of siloxane-anhydride-polyamide 6, and simultaneously uses KH-550-modified calcium carbonate in synergy with the modified glass fiber, significantly improving the fatigue resistance and durability of nylon materials. Verification shows that the material maintains structural integrity and stable performance after 5 to 5.3 million fatigue tests under long-term dynamic loads, greatly extending the service life of track elastic components and giving the material excellent impact toughness, reaching 13 to 16 times.

[0051] 2. This invention significantly improves the fatigue resistance and long-term service stability of nylon composite materials through the synergistic compounding of modified glass fiber, modified calcium carbonate, and maleic anhydride-grafted polyolefin elastomer toughening agents. Furthermore, the addition of polyamide 66, heat stabilizers, and lubricants ensures the material maintains excellent structural stability even after cyclic loading. The gauge widening is only +1 to +3 mm, and the residual compressive deformation is ≤0.073 mm. This indicates that the material of this invention exhibits minimal deformation and good recovery capability under long-term dynamic stress, ensuring the long-term geometric accuracy and safety of the track fastening system. Detailed Implementation

[0052] 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.

[0053] The glass fiber raw material used in the modified glass fiber of this invention has a diameter of 10~25μm and a length of 1~2mm;

[0054] Calcium carbonate raw material, particle size 40~100nm;

[0055] Maleic anhydride-grafted polyolefin elastomers can be purchased from Shenyang Ketong Plastics Co., Ltd. as toughening agent KT-906.

[0056] Maleic anhydride-grafted polyolefin elastomers can be purchased from Shenyang Ketong Plastics Co., Ltd. as toughening agent KT-913.

[0057] Maleic anhydride-grafted polyolefin elastomers can be purchased from Shenyang Ketong Plastics Co., Ltd. as toughening agent KT-9.

[0058] Organotin heat stabilizer JX-181 is available from Taian Lantian Additives Co., Ltd.

[0059] The organic copper salt composite heat stabilizer Finner-336 was purchased from Shaorui Chemical (Shanghai) Co., Ltd.

[0060] Lubricant EBS P130 was purchased from Shenzhen Winova Chemical Materials Co., Ltd.

[0061] The polysiloxane was purchased from Silico Technology Co., Ltd. as an organosilicon superdispersant SILIMER6150.

[0062] The dispersant HyPer C100 was purchased from Wuhan Hyperbranched Resin Technology Co., Ltd. as a multifunctional additive for hyperbranched plastics.

[0063] Dispersant AC540A can be purchased from Guangzhou Fantai New Material Technology Co., Ltd.

[0064] Polyamide 66 was purchased from Nanjing Julong Technology Co., Ltd., brand name: AN0FBK, density: 1.14 g / cm³. 3 ;

[0065] Polyamide 6 was purchased from Yueyang Baling Jiayun Petrochemical Co., Ltd., with a relative viscosity of 2.4~2.5 and model number BL3180.

[0066] Preparation Example 1

[0067] Preparation of modified glass fiber

[0068] A. Vinyltriethoxysilane is added to a 9:1 volume ratio mixture of ethanol and water, wherein acetic acid is added to adjust the pH of the mixture to 3. The mixture is stirred and hydrolyzed for 30 minutes to obtain a silane coupling agent solution. The vinyltriethoxysilane accounts for 1% of the total volume of the ethanol and water mixture. The cleaned and dried glass fiber raw material is immersed in the above silane coupling agent solution, ensuring complete wetting. The reaction is carried out at a constant temperature of 60°C with stirring for 2 hours. After the reaction is complete, the material is washed repeatedly by centrifugation with anhydrous ethanol to remove physically adsorbed vinyltriethoxysilane. Then, it is dried in a vacuum oven at 100°C for 4 hours to obtain pretreated glass fiber. The amount of vinyltriethoxysilane used is 0.4% of the glass fiber mass.

[0069] B. Disperse the pretreated glass fibers in dry xylene solvent at a solid-liquid ratio of approximately 1:15 (1g:15mL). Probe nitrogen gas for protection. Add maleic anhydride (MAH) and a small amount of dicumyl peroxide (diisopropylbenzene peroxide), which is 3% of the MAH mass. Recycle the mixture under nitrogen atmosphere in a 110°C oil bath for 4.5 hours with vigorous stirring. After the reaction, wash repeatedly with hot toluene to thoroughly remove unreacted MAH and homopolymer. Finally, vacuum dry at 80°C to obtain grafted maleic anhydride glass fibers. The amount of maleic anhydride used is 4% of the glass fiber mass.

[0070] C. Grafted maleic anhydride glass fiber and polyamide 6 are premixed in a high-speed mixer. The amount of polyamide 6 is 28% of the mass of glass fiber. A trace amount of dibutyltin dilaurate catalyst is added, with the amount of dibutyltin dilaurate being 0.5% of the mass of PA6. The premixed material is added to a twin-screw extruder for melt reaction. The extruder adopts a low-shear screw combination, reducing or removing strong shear elements such as kneading blocks. A double-headed screw is used, and the screw speed is controlled at 100-150 rpm to prevent excessive shearing of the glass fiber. The residence time of the material in the screw is about 1-2 minutes. The twin-screw extruder can also be replaced by a single-screw extruder or other low-shear equipment. After water cooling, air drying, and pelletizing, the extruded strip is used to obtain modified GF-1. Before use, it is vacuum dried at 100℃ for more than 8 hours to remove moisture.

[0071] Preparation Example 2

[0072] Preparation of modified glass fiber

[0073] A. Vinyltriethoxysilane is added to a 9:1 volume ratio mixture of ethanol and water, wherein acetic acid is added to adjust the pH of the mixture to 4. The mixture is stirred and hydrolyzed for 30 minutes to obtain a silane coupling agent solution. The vinyltriethoxysilane accounts for 0.5% of the total volume of the ethanol and water mixture. The cleaned and dried glass fiber raw material is immersed in the above silane coupling agent solution, ensuring complete wetting. The reaction is carried out at 50°C with constant stirring for 3 hours. After the reaction is complete, the raw material is washed repeatedly with anhydrous ethanol by centrifugation to remove physically adsorbed vinyltriethoxysilane. Then, it is dried in a vacuum oven at 100°C for 4 hours to obtain pretreated glass fiber. The amount of vinyltriethoxysilane used is 0.3% of the glass fiber mass.

[0074] B. Disperse the pretreated glass fibers in dry xylene solvent at a solid-liquid ratio of approximately 1:15, under nitrogen protection, and add maleic anhydride (MAH) and a small amount of initiator dicumyl peroxide (3% of the MAH mass). React under nitrogen atmosphere in a 100°C oil bath for 6 hours with vigorous stirring. After the reaction, wash repeatedly with hot toluene to thoroughly remove unreacted MAH and homopolymer. Finally, vacuum dry at 80°C to obtain grafted maleic anhydride glass fibers; the amount of maleic anhydride used is 3% of the glass fiber mass.

[0075] C. Grafted maleic anhydride glass fiber and polyamide 6 are premixed in a high-speed mixer. The amount of polyamide 6 is 25% of the mass of glass fiber. A trace amount of dibutyltin dilaurate catalyst is added, with the amount of dibutyltin dilaurate being 0.4% of the mass of PA6. The premixed material is added to a twin-screw extruder for melt reaction. The extruder adopts a low-shear screw combination, reducing or removing strong shear elements such as kneading blocks. A double-headed screw is used, and the screw speed is controlled at 100-150 rpm to prevent excessive shearing of the glass fiber. The residence time of the material in the screw is about 1-2 minutes. The twin-screw extruder can also be replaced by a single-screw extruder or other low-shear equipment. After water cooling, air drying, and pelletizing, the extruded strip is used to obtain modified GF-2. Before use, it is vacuum dried at 100℃ for more than 8 hours to remove moisture.

[0076] Preparation Example 3

[0077] Preparation of modified glass fiber

[0078] A. Vinyltriethoxysilane is added to a 9:1 volume ratio mixture of ethanol and water, wherein acetic acid is added to adjust the pH of the mixture to 4. The mixture is stirred and hydrolyzed for 30 minutes to obtain a silane coupling agent solution. The vinyltriethoxysilane accounts for 2% of the total volume of the ethanol and water mixture. The cleaned and dried glass fiber raw material is immersed in the above silane coupling agent solution, ensuring complete wetting. The reaction is carried out at 70°C with constant stirring for 1 hour. After the reaction is complete, the material is washed repeatedly with anhydrous ethanol by centrifugation to remove physically adsorbed vinyltriethoxysilane. Then, it is dried in a vacuum oven at 100°C for 4 hours to obtain pretreated glass fiber. The amount of vinyltriethoxysilane used is 0.5% of the glass fiber mass.

[0079] B. Disperse the pretreated glass fibers in dry xylene solvent at a solid-liquid ratio of approximately 1:15, under nitrogen protection, add maleic anhydride (MAH) and a small amount of initiator dicumyl peroxide (3% of the MAH mass); react under vigorous stirring and reflux in a 120°C oil bath under nitrogen atmosphere for 3 hours. After the reaction, wash repeatedly with hot toluene to thoroughly remove unreacted MAH and homopolymer, and finally vacuum dry at 80°C to obtain grafted maleic anhydride glass fibers; the amount of maleic anhydride used is 8% of the glass fiber mass.

[0080] C. Grafted maleic anhydride glass fiber and polyamide 6 are premixed in a high-speed mixer. The amount of polyamide 6 is 30% of the mass of glass fiber. A trace amount of dibutyltin dilaurate catalyst is added, with the amount of dibutyltin dilaurate being 0.6% of the mass of PA6. The premixed material is added to a twin-screw extruder for melt reaction. The extruder adopts a low-shear screw combination, reducing or removing strong shear elements such as kneading blocks. A double-headed screw is used, and the screw speed is controlled at 100-150 rpm to prevent excessive shearing of the glass fiber. The residence time of the material in the screw is about 1-2 minutes. The twin-screw extruder can also be replaced by a single-screw extruder or other low-shear equipment. After water cooling, air drying, and pelletizing, the extruded strip is used to obtain modified GF-3. Before use, it is vacuum dried at 100℃ for more than 8 hours to remove moisture.

[0081] Preparation Example 4

[0082] Preparation of modified calcium carbonate

[0083] Silane coupling agent KH-550, deionized water, and anhydrous ethanol were mixed in a mass ratio of 1:3:7. Acetic acid was added to adjust the pH to 5, and the mixture was pre-hydrolyzed at 70°C for 30 min to obtain a treatment solution. A certain amount of calcium carbonate raw material was dispersed in the treatment solution, with silane coupling agent KH-550 accounting for 2 wt% of the calcium carbonate raw material. The mixture was then stirred at 70°C for 4 h. The product after the reaction was washed twice with anhydrous ethanol and twice with deionized water to remove residual KH-550 and other impurities. The product was then dried in an oven at 50°C for 12 h to obtain CaCO3-1.

[0084] Preparation Example 5

[0085] Preparation of modified calcium carbonate

[0086] Silane coupling agent KH-550, deionized water, and anhydrous ethanol were mixed in a mass ratio of 1:2:8. Acetic acid was added to adjust the pH to 4, and the mixture was pre-hydrolyzed at 60°C for 40 min to obtain a treatment solution. A certain amount of calcium carbonate raw material was dispersed in the treatment solution, with silane coupling agent KH-550 being 0.5 wt% of the calcium carbonate raw material. The mixture was then stirred at 60°C for 5 h. The reaction product was washed twice with anhydrous ethanol and twice with deionized water to remove residual KH-550 and other impurities. The product was then dried in an oven at 40°C for 14 h to obtain CaCO3-2.

[0087] Preparation Example 6

[0088] Preparation of modified calcium carbonate

[0089] Silane coupling agent KH-550, deionized water, and anhydrous ethanol were mixed in a mass ratio of 1:4:6. Acetic acid was added to adjust the pH to 4, and the mixture was pre-hydrolyzed at 80°C for 20 min to obtain a treatment solution. A certain amount of calcium carbonate raw material was dispersed in the treatment solution, with silane coupling agent KH-550 accounting for 3 wt% of the calcium carbonate raw material. The mixture was then stirred at 80°C for 3 h. The product after the reaction was washed twice with anhydrous ethanol and twice with deionized water to remove residual KH-550 and other impurities. The product was then dried in an oven at 60°C for 10 h to obtain CaCO3-3.

[0090] Example 1

[0091] A fatigue-resistant nylon composite material based on microphase regulation, comprising, by mass parts: 54 parts polyamide 66, 35 parts modified GF-1, 3 parts toughening agent KT-906, 4 parts CaCO3-1, 0.8 parts antioxidant 1010, 4 parts organic copper salt composite heat stabilizer Finner-336, 1 part lubricant EBS P130, and 0.2 parts dispersant HYPER C100.

[0092] The preparation method of the above-mentioned nylon composite material includes the following steps:

[0093] S0 and polyamide 66 are thoroughly dried at 120°C for 5 hours.

[0094] S1. Premix polyamide 66, toughening agent KT-906, CaCO3-1, antioxidant 1010, organic copper salt composite heat stabilizer Finner-336, lubricant EBS P130 and dispersant HYPER C100 for 4 minutes to obtain the main material;

[0095] S2. The main material is added from the main feed port of the twin-screw extruder, and the modified GF-1 is added from the side feed port. After melt blending, extrusion, granulation, and drying, composite material particles are obtained. The screw temperature control is as follows: Zones 1-2: 230℃, 240℃; Zones 3-5: 255℃, 265℃, 270℃; Zone 6: 270℃; Zones 7-8: 270℃, 275℃; Zones 9-10: 275℃, 275℃; Zones 11-12: 275℃, 280℃; Screw speed: 300 rpm; Vacuum degree: not lower than -0.095 MPa.

[0096] S3. The composite material particles are injection molded to obtain the nylon composite material; the injection molding process conditions are as follows: Zone 1: 275℃, Zone 2: 285℃, Zone 3: 285℃, Nozzle temperature: 290℃; Barrel temperature: 290℃, Mold temperature: 90℃, Injection pressure: 83MPa, Injection speed: 40mm / s, Holding pressure: 80MPa, Holding time: 12s, Cooling time: 42s.

[0097] Example 2

[0098] A fatigue-resistant nylon composite material based on microphase regulation, comprising, by mass parts: 50 parts polyamide 66, 32 parts modified GF-2, 5 parts toughening agent KT-913, 2 parts CaCO3-2, 0.5 parts antioxidant 1010, 3 parts organic copper salt composite heat stabilizer Finner-336, 0.5 parts lubricant EBS P130, and 0.8 parts dispersant HYPER C100.

[0099] The preparation method of the above-mentioned nylon composite material includes the following steps:

[0100] S0 and polyamide 66 are thoroughly dried at 120°C for 4 hours.

[0101] S1. Premix polyamide 66, toughening agent KT-913, CaCO3-2, antioxidant 1010, organic copper salt composite heat stabilizer Finner-336, lubricant EBS P130 and dispersant HYPER C100 for 5 minutes to obtain the main material;

[0102] S2. The main material is added from the main feed port of the twin-screw extruder, and the modified GF-2 is added from the side feed port. After melt blending, extrusion, granulation, and drying, composite material particles are obtained. The screw temperature control is as follows: Zones 1-2: 230℃, 240℃; Zones 3-5: 255℃, 265℃, 270℃; Zone 6: 270℃; Zones 7-8: 270℃, 275℃; Zones 9-10: 275℃, 275℃; Zones 11-12: 275℃, 280℃; Screw speed: 250 rpm; Vacuum degree: not lower than -0.095 MPa.

[0103] S3. The composite material particles are injection molded to obtain the nylon composite material; the injection molding process conditions are as follows: Zone 1: 275℃, Zone 2: 285℃, Zone 3: 285℃, Nozzle temperature: 290℃; Barrel temperature: 290℃, Mold temperature: 90℃, Injection pressure: 80MPa, Injection speed: 45mm / s, Holding pressure: 75MPa, Holding time: 15s, Cooling time: 40s.

[0104] Example 3

[0105] A fatigue-resistant nylon composite material based on microphase regulation, comprising, by mass parts: 60 parts polyamide 66, 30 parts modified GF-3, 4 parts toughening agent KT-9, 5 parts CaCO3-3, 0.5 parts antioxidant 1010, 3 parts organic copper salt composite heat stabilizer Finner-336, 0.8 parts lubricant EBS P130, and 0.5 parts dispersant HYPER C100.

[0106] The preparation method of the above-mentioned nylon composite material includes the following steps:

[0107] S0 and polyamide 66 were thoroughly dried at 120°C for 6 hours.

[0108] S1. Premix polyamide 66, toughening agent KT-9, CaCO3-3, antioxidant 1010, organic copper salt composite heat stabilizer Finner-336, lubricant EBS P130 and dispersant HYPER C100 for 3 minutes to obtain the main material;

[0109] S2. The main material is added from the main feed port of the twin-screw extruder, and the modified GF-3 is added from the side feed port. After melt blending, extrusion, granulation, and drying, composite material particles are obtained. The screw temperature control is as follows: Zones 1-2: 230℃, 240℃; Zones 3-5: 255℃, 265℃, 270℃; Zone 6: 270℃; Zones 7-8: 270℃, 275℃; Zones 9-10: 275℃, 275℃; Zones 11-12: 275℃, 280℃; Screw speed: 320 rpm; Vacuum degree: not lower than -0.095 MPa.

[0110] S3. The composite material particles are injection molded to obtain the nylon composite material. The injection molding process conditions are as follows: Zone 1: 275℃, Zone 2: 285℃, Zone 3: 285℃, Nozzle temperature: 290℃, Barrel temperature: 290℃, Mold temperature: 90℃, Injection pressure: 85MPa, Injection speed: 30mm / s, Holding pressure: 80MPa, Holding time: 10s, Cooling time: 45s.

[0111] Example 4

[0112] A fatigue-resistant nylon composite material based on microphase regulation, comprising, by mass parts: 56 parts polyamide 66, 33 parts modified GF-2, 4 parts toughening agent KT-906, 4 parts CaCO3-1, 0.8 parts antioxidant 1010, 4 parts organic copper salt composite heat stabilizer Finner-336, 1 part lubricant EBS P130, and 0.2 parts dispersant HYPER C100.

[0113] The preparation method of the above-mentioned nylon composite material includes the following steps:

[0114] S0 and polyamide 66 are thoroughly dried at 120°C for 5 hours.

[0115] S1. Premix polyamide 66, toughening agent KT-906, CaCO3-1, antioxidant 1010, organic copper salt composite heat stabilizer Finner-336, lubricant EBS P130 and dispersant HYPER C100 for 4 minutes to obtain the main material;

[0116] S2. The main material is added from the main feed port of the twin-screw extruder, and the modified GF-2 is added from the side feed port. After melt blending, extrusion, granulation, and drying, composite material particles are obtained. The screw temperature control is as follows: Zones 1-2: 230℃, 240℃; Zones 3-5: 255℃, 265℃, 270℃; Zone 6: 270℃; Zones 7-8: 270℃, 275℃; Zones 9-10: 275℃, 275℃; Zones 11-12: 275℃, 280℃; Screw speed: 300 rpm; Vacuum degree: not lower than -0.095 MPa.

[0117] S3. The composite material particles are injection molded to obtain the nylon composite material; the injection molding process conditions are as follows: Zone 1: 275℃, Zone 2: 285℃, Zone 3: 285℃, Nozzle temperature: 290℃; Barrel temperature: 290℃, Mold temperature: 90℃, Injection pressure: 83MPa, Injection speed: 40mm / s, Holding pressure: 78MPa, Holding time: 12s, Cooling time: 42s.

[0118] Comparative Example 1

[0119] Compared with Example 1, the only difference is that CaCO3-1 is omitted. Specifically:

[0120] A nylon composite material, by mass parts, comprises: 54 parts polyamide 66, 35 parts modified GF-1, 3 parts toughening agent KT-906, 0.8 parts antioxidant 1010, 4 parts organic copper salt composite heat stabilizer Finner-336, 1 part lubricant EBSP130, and 0.2 parts dispersant HYPER C100.

[0121] The preparation method of the above-mentioned nylon composite material includes the following steps:

[0122] S0 and polyamide 66 are thoroughly dried at 120°C for 5 hours.

[0123] S1. Premix polyamide 66, toughening agent KT-906, antioxidant 1010, organic copper salt composite heat stabilizer Finner-336, lubricant EBS P130 and dispersant HYPER C100 for 4 minutes to obtain the main material;

[0124] S2. The main material is added from the main feed port of the twin-screw extruder, and the modified GF-1 is added from the side feed port. After melt blending, extrusion, granulation, and drying, composite material particles are obtained. The screw temperature control is as follows: Zones 1-2: 230℃, 240℃; Zones 3-5: 255℃, 265℃, 270℃; Zone 6: 270℃; Zones 7-8: 270℃, 275℃; Zones 9-10: 275℃, 275℃; Zones 11-12: 275℃, 280℃; Screw speed: 300 rpm; Vacuum degree: not lower than -0.095 MPa.

[0125] S3. The composite material particles are injection molded to obtain the nylon composite material; the injection molding process conditions are as follows: Zone 1: 275℃, Zone 2: 285℃, Zone 3: 285℃, Nozzle temperature: 290℃; Barrel temperature: 290℃, Mold temperature: 90℃, Injection pressure: 83MPa, Injection speed: 40mm / s, Holding pressure: 80MPa, Holding time: 12s, Cooling time: 42s.

[0126] Comparative Example 2

[0127] Compared to Example 1, the only difference is that modified GF-1 is omitted. Specifically:

[0128] A nylon composite material, by mass parts, comprises: 54 parts polyamide 66, 3 parts toughening agent KT-906, 4 parts CaCO3-1, 0.8 parts antioxidant 1010, 4 parts organic copper salt composite heat stabilizer Finner-336, 1 part lubricant EBSP130, and 0.2 parts dispersant HYPER C100.

[0129] The preparation method of the above-mentioned nylon composite material includes the following steps:

[0130] S0 and polyamide 66 are thoroughly dried at 120°C for 5 hours.

[0131] S1. Premix polyamide 66, toughening agent KT-906, CaCO3-1, antioxidant 1010, organic copper salt composite heat stabilizer Finner-336, lubricant EBS P130 and dispersant HYPER C100 for 4 minutes to obtain the main material;

[0132] S2. The main material is added from the main feed port of the twin-screw extruder, and after melt blending, extrusion, granulation, and drying, composite material particles are obtained; wherein, the screw temperature control is as follows: Zone 1-2: 230℃, 240℃; Zone 3-5: 255℃, 265℃, 270℃; Zone 6: 270℃; Zone 7-8: 270℃, 275℃; Zone 9-10: 275℃, 275℃; Zone 11-12: 275℃, 280℃; Screw speed: 300rpm; Vacuum degree: not lower than -0.095Mpa;

[0133] S3. The composite material particles are injection molded to obtain the nylon composite material; the injection molding process conditions are as follows: Zone 1: 275℃, Zone 2: 285℃, Zone 3: 285℃, Nozzle temperature: 290℃; Barrel temperature: 290℃, Mold temperature: 90℃, Injection pressure: 83MPa, Injection speed: 40mm / s, Holding pressure: 80MPa, Holding time: 12s, Cooling time: 42s.

[0134] Comparative Example 3

[0135] Compared with Example 1, the only difference is that modified GF-1 and CaCO3-1 are omitted. Specifically:

[0136] A nylon composite material, by mass parts, comprises: 54 parts polyamide 66, 3 parts toughening agent KT-906, 0.8 parts antioxidant 1010, 4 parts organic copper salt composite heat stabilizer Finner-336, 1 part lubricant EBS P130, and 0.2 parts dispersant HYPER C100.

[0137] The preparation method of the above-mentioned nylon composite material includes the following steps:

[0138] S0 and polyamide 66 are thoroughly dried at 120°C for 5 hours.

[0139] S1. Premix polyamide 66, toughening agent KT-906, antioxidant 1010, organic copper salt composite heat stabilizer Finner-336, lubricant EBS P130 and dispersant HYPER C100 for 4 minutes to obtain the main material;

[0140] S2. The main material is added from the main feed port of the twin-screw extruder, and after melt blending, extrusion, granulation, and drying, composite material particles are obtained; wherein, the screw temperature control is as follows: Zone 1-2: 230℃, 240℃; Zone 3-5: 255℃, 265℃, 270℃; Zone 6: 270℃; Zone 7-8: 270℃, 275℃; Zone 9-10: 275℃, 275℃; Zone 11-12: 275℃, 280℃; Screw speed: 300rpm; Vacuum degree: not lower than -0.095Mpa;

[0141] S3. The composite material particles are injection molded to obtain the nylon composite material; the injection molding process conditions are as follows: Zone 1: 275℃, Zone 2: 285℃, Zone 3: 285℃, Nozzle temperature: 290℃; Barrel temperature: 290℃, Mold temperature: 90℃, Injection pressure: 83MPa, Injection speed: 40mm / s, Holding pressure: 80MPa, Holding time: 12s, Cooling time: 42s.

[0142] Comparative Example 4

[0143] The nylon composite material was prepared according to the method of Example 1 in Chinese Patent Publication No. CN114163692A, as follows:

[0144] By weight, the raw materials include: 50 parts polyamide 66, 40 parts polyamide 6, 15 parts chopped glass fibers (diameter 3-10 μm, length 0.2-0.6 mm), 1.5 parts vinyltrimethoxysilane, 0.5 parts maleic anhydride, and 3 parts antioxidant (antioxidant 1010 and antioxidant 1098 in a 1:1 mass ratio).

[0145] Preparation process:

[0146] S1: Preparation of modified glass fibers

[0147] Vinyltrimethoxysilane was dissolved in an aqueous ethanol solution to prepare a solution. Glass fiber and vinyltrimethoxysilane solution (10 wt% of glass fiber) were placed in a high-speed stirrer and stirred for 3 minutes. Then it was placed in an oven at 120°C to dry.

[0148] Glass fibers treated with the above coupling agent, maleic anhydride and acetone were added to a three-necked flask, and nitrogen gas was introduced for protection. Under the action of dicumyl peroxide, the two underwent a grafting reaction. After the reaction was completed, the glass fibers were taken out and placed in an oven to dry, thus obtaining modified glass fibers.

[0149] S2: Preparation of PA6 / Surface-Modified GF Composite Material

[0150] Modified glass fiber, PA6, and antioxidant are mixed evenly and then added to a twin-screw extruder. The processing temperature is 260-280℃ and the screw speed is 120rpm. After extrusion, cooling, drying, and pelletizing, PA6 / surface-modified GF composite material is obtained.

[0151] S3: Preparation of Nylon Composite Materials

[0152] After the PA6 / surface-modified GF composite material, PA66, and antioxidant are mixed evenly, they are added to a twin-screw extruder. The processing temperature is 260-280℃ and the screw speed is 120rpm. After extrusion, cooling, drying, and pelletizing, the mixture is placed in a forced-air drying oven at 90℃ and dried to constant weight.

[0153] The dried material is added to an injection molding machine and injection molded at 260-280℃ to obtain a nylon composite material test strip - baffle seat.

[0154] Comparative Example 5

[0155] Compared to Comparative Example 4, the only difference is that 33.24 parts of glass fiber raw material (diameter 10~25μm, length 1~2mm) were used, so that the mass percentage of glass fiber in the nylon material was the same as in Example 1. Specifically, as follows:

[0156] By weight, the raw materials include: 50 parts polyamide 66, 40 parts polyamide 6, 33.24 parts glass fiber raw material (diameter 10-25μm, length 1-2mm), 1.5 parts vinyltrimethoxysilane, 0.5 parts maleic anhydride, and 3 parts antioxidant (antioxidant 1010 and antioxidant 1098 in a 1:1 mass ratio).

[0157] Preparation process:

[0158] S1: Preparation of modified glass fibers

[0159] Vinyltrimethoxysilane was dissolved in an aqueous ethanol solution to prepare a solution. Glass fiber and vinyltrimethoxysilane solution (10 wt% of glass fiber) were placed in a high-speed stirrer and stirred for 3 minutes. Then it was placed in an oven at 120°C to dry.

[0160] Glass fibers treated with the above coupling agent, maleic anhydride and acetone were added to a three-necked flask, and nitrogen gas was introduced for protection. Under the action of dicumyl peroxide, the two underwent a grafting reaction. After the reaction was completed, the glass fibers were taken out and placed in an oven to dry, thus obtaining modified glass fibers.

[0161] S2: Preparation of PA6 / Surface-Modified GF Composite Material

[0162] Modified glass fiber, PA6, and antioxidant are mixed evenly and then added to a twin-screw extruder. The processing temperature is 260-280℃ and the screw speed is 120rpm. After extrusion, cooling, drying, and pelletizing, PA6 / surface-modified GF composite material is obtained.

[0163] S3: Preparation of Nylon Composite Materials

[0164] After the PA6 / surface-modified GF composite material, PA66, and antioxidant are mixed evenly, they are added to a twin-screw extruder. The processing temperature is 260-280℃ and the screw speed is 120rpm. After extrusion, cooling, drying, and pelletizing, the mixture is placed in a forced-air drying oven at 90℃ and dried to constant weight.

[0165] The dried material is added to an injection molding machine and injection molded at 260-280℃ to obtain a nylon composite material test strip - baffle seat.

[0166] Comparative Example 6

[0167] Compared to Example 1, the only difference is that the toughening agent KT-906 is omitted. Specifically:

[0168] A nylon composite material, by mass parts, comprises the following raw materials: 54 parts polyamide 66, 35 parts modified GF-1, 4 parts CaCO3-1, 0.8 parts antioxidant 1010, 4 parts organic copper salt composite heat stabilizer Finner-336, 1 part lubricant EBS P130, and 0.2 parts dispersant HYPER C100.

[0169] The preparation method of the above-mentioned nylon composite material includes the following steps:

[0170] S0 and polyamide 66 are thoroughly dried at 120°C for 5 hours.

[0171] S1. Premix polyamide 66, CaCO3-1, antioxidant 1010, organic copper salt composite heat stabilizer Finner-336, lubricant EBS P130 and dispersant HYPER C100 for 4 minutes to obtain the main material;

[0172] S2. The main material is added from the main feed port of the twin-screw extruder, and the modified GF-1 is added from the side feed port. After melt blending, extrusion, granulation, and drying, composite material particles are obtained. The screw temperature control is as follows: Zones 1-2: 230℃, 240℃; Zones 3-5: 255℃, 265℃, 270℃; Zone 6: 270℃; Zones 7-8: 270℃, 275℃; Zones 9-10: 275℃, 275℃; Zones 11-12: 275℃, 280℃; Screw speed: 300 rpm; Vacuum degree: not lower than -0.095 MPa.

[0173] S3. The composite material particles are injection molded to obtain the nylon composite material; the injection molding process conditions are as follows: Zone 1: 275℃, Zone 2: 285℃, Zone 3: 285℃, Nozzle temperature: 290℃; Barrel temperature: 290℃, Mold temperature: 90℃, Injection pressure: 83MPa, Injection speed: 40mm / s, Holding pressure: 80MPa, Holding time: 12s, Cooling time: 42s.

[0174] Example of effect

[0175] The nylon materials prepared in the examples and comparative examples were injection molded into baffle seats in step S3, and then performance tests were conducted.

[0176] 1. Fatigue performance test: The fatigue test shall be conducted in accordance with TB / T 3396.3-2015 Determination of static stiffness of assembly and TB / T3396.4-2015 Fatigue performance test of assembly. Record the number of fatigue cycles in which the sample fails or breaks under cyclic loading. If no failure occurs, record the number of times the test is terminated.

[0177] 2. Impact toughness test: Refer to TB / T 1495-2020 Type I elastic clip fastener. The impact test of the baffle seat shall be carried out according to the following steps:

[0178] a) The ambient temperature during the test was 23℃±3℃;

[0179] b) Fix the baffle seat to the base plate of the impactor and let the impact bar weighing 4.5kg±0.05kg fall freely from a height of 0.45m, with the impact point in the middle of the protruding edge of the baffle seat.

[0180] c) Continuously impact the baffle seat until visible cracks appear or it breaks completely, and record the total number of impacts. Test each sample 5 times and take the average number of times the baffle seat breaks.

[0181] 3. Compressive residual deformation: Test according to Q-CR 563-2017 Type I elastic clip fastener, and record the residual deformation of the sample after unloading the compressive load.

[0182] The experimental results are shown in Table 1.

[0183] Table 1

[0184]

[0185] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fatigue-resistant nylon composite material based on microphase modulation, characterized in that, By weight, the raw materials include: 50-60 parts polyamide 66, 30-35 parts modified glass fiber, 3-5 parts maleic anhydride grafted polyolefin elastomer, 2-5 parts modified calcium carbonate, 0.5-0.8 parts antioxidant, 2-4 parts heat stabilizer, 0.5-1 part lubricant, and 0.2-0.8 parts dispersant; The method for preparing the modified glass fiber includes the following steps: treating the glass fiber raw material with vinyltriethoxysilane and grafting it with maleic anhydride to obtain grafted maleic anhydride glass fiber; then reacting the grafted maleic anhydride glass fiber with polyamide 6 in a molten state in the presence of a catalyst to obtain the modified glass fiber. The modified calcium carbonate is obtained by modifying calcium carbonate raw material with silane coupling agent KH-550.

2. The fatigue-resistant nylon composite material based on microphase regulation according to claim 1, characterized in that, The amounts of vinyltriethoxysilane, maleic anhydride, and polyamide 6 are 0.3%–0.5%, 3%–8%, and 25%–30% of the glass fiber mass, respectively.

3. The fatigue-resistant nylon composite material based on microphase regulation according to claim 1, characterized in that, The method for preparing the modified glass fiber includes the following steps: A. Immerse the glass fiber raw material in a silane coupling agent solution and react at 50-70°C for 1-3 hours to obtain pretreated glass fiber; B. The pretreated glass fiber obtained in step A is reacted with maleic anhydride in an inert atmosphere and in the presence of an initiator to obtain maleic anhydride-grafted glass fiber; C. The grafted maleic anhydride glass fiber obtained in step B is reacted with polyamide 6 in the molten state in the presence of a catalyst to obtain modified glass fiber.

4. The fatigue-resistant nylon composite material based on microphase regulation according to claim 3, characterized in that, The catalyst in step C is an organotin compound, and the amount of catalyst used is 0.4 to 0.6% of the mass of polyamide 6.

5. The fatigue-resistant nylon composite material based on microphase regulation according to claim 1, characterized in that, The silane coupling agent KH-550 is 0.5~3wt% of the calcium carbonate raw material.

6. The fatigue-resistant nylon composite material based on microphase regulation according to claim 1, characterized in that, The method for preparing the modified calcium carbonate includes the following steps: Mix silane coupling agent KH-550, water, and ethanol, adjust the pH to acidic, and react at 60–80°C for 20–40 minutes to obtain a treatment solution. Disperse calcium carbonate raw material in the treatment solution and stir to react. Wash and dry the product after reaction.

7. The method for preparing fatigue-resistant nylon composite material based on microphase regulation as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Premix polyamide 66, maleic anhydride-grafted polyolefin elastomer, modified calcium carbonate, antioxidant, heat stabilizer, lubricant and dispersant to obtain the main material; S2. The main material is added from the main feed port of the twin-screw extruder, and the modified glass fiber is added from the side feed port. After melt blending, extrusion, granulation and drying, composite material particles are obtained. S3. The composite material particles are injection molded to obtain the nylon composite material.

8. The method for preparing fatigue-resistant nylon composite material based on microphase regulation according to claim 7, characterized in that, In step S2, the extrusion process parameters are: screw temperature 230℃~280℃, screw speed 250~320rpm, and vacuum degree not lower than -0.095MPa.

9. The method for preparing fatigue-resistant nylon composite material based on microphase regulation according to claim 7, characterized in that, In step S3, the parameters of the injection molding process are: barrel temperature 275℃~300℃, injection pressure 80~85MPa, injection speed 30~45mm / s, holding pressure 70~85MPa, holding time 10~15s, and cooling time 40~45s.

10. The application of the fatigue-resistant nylon composite material based on microphase regulation as described in any one of claims 1 to 6 in rail transit track fastening systems.

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