Preparation method of high-temperature-resistant modified nylon 66 composite fiber material

Abstract

This invention discloses a method for preparing a high-temperature resistant modified nylon 66 composite fiber material, relating to the field of nylon technology. The method includes the steps of preparing a composite reinforcing antioxidant component, preparing modified nano-silica, and obtaining the composite fiber material. The raw materials used to prepare the composite reinforcing antioxidant component include maleic anhydride-grafted polyolefin elastomer, 1,6-hexanediamine, processing stabilizer, 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, and p-toluenesulfonic acid. The raw materials used to prepare the modified nano-silica include nano-silica and a composite silane coupling agent. The raw materials used to obtain the composite fiber material include nylon 66 resin, the composite reinforcing antioxidant component, modified nano-silica, pentaerythritol stearate, epoxy resin, and a composite antioxidant additive. The nylon 66 composite fiber material prepared by this invention exhibits strong high-temperature resistance, excellent mechanical properties, and superior aging resistance.

Description

Technical Field

[0001] This invention relates to the field of nylon technology, and specifically to a method for preparing a high-temperature resistant modified nylon 66 composite fiber material. Background Technology

[0002] Nylon 66 is the core matrix material for elastic weft yarns in tires due to its excellent mechanical strength, wear resistance, impact resistance and stable spinnability. As a key skeleton auxiliary material for tire carcass and belt layer, its performance directly determines the tire's dimensional stability, dynamic cushioning performance and long service life.

[0003] As the demands on tires for new energy vehicles and heavy-duty commercial vehicles become increasingly stringent in terms of high speed, high load, and long service life, the performance shortcomings of conventional nylon 66 fiber are becoming more and more apparent. Under the high internal temperature conditions of 120-150℃ during high-speed tire operation, tensile strength and elastic recovery rate decrease significantly, easily leading to irreversible permanent deformation. At the same time, conventional nylon 66 is susceptible to the effects of vulcanizing media and copper ion catalytic aging in steel wires, resulting in easy degradation and embrittlement of the molecular chains. Furthermore, its interfacial adhesion with the rubber matrix is ​​poor, making it prone to interfacial debonding under dynamic loads. Existing modification schemes mostly use physical blending of polyolefin elastomers and inorganic fillers for toughening. Although this can improve a single property, it is difficult to simultaneously achieve high-temperature resistance, long-term anti-aging properties, high elastic recovery, and continuous spinning stability. Moreover, small-molecule antioxidants are prone to migration and precipitation, resulting in poor long-term protective effects, which cannot meet the core requirements of tire elastic weft yarns for long-term and demanding service. The prior art disclosed in CN118165508A is a high-temperature resistant modified nylon 66 composite material and its preparation method. This prior art improves the temperature resistance of the material by linking rigid polybenzene ring side groups to the nylon 66 molecule. Although it has achieved optimization of heat resistance and dimensional stability in the field of engineering plastics, this technology is only suitable for injection molding of engineering plastics and cannot meet the industrial requirements of continuous melt spinning of nylon 66 fibers. Moreover, the modified material is brittle and has low elongation at break. It does not have a long-term antioxidant system and cannot solve the problems of easy volatilization and precipitation of small molecule antioxidants at high temperatures and rapid decay of fiber properties.

[0004] In summary, although the existing technical solutions have improved some properties of nylon 66 to a certain extent, the following technical problems still exist: poor high-temperature resistance, and insufficient mechanical and aging resistance. Summary of the Invention

[0005] In order to solve the above-mentioned problems in the prior art, the present invention provides a method for preparing high-temperature resistant modified nylon 66 composite fiber material, and achieves the following objective: to prepare nylon 66 composite fiber material with strong high-temperature resistance, excellent mechanical properties and aging resistance.

[0006] To achieve the above objectives, the following technical solution is adopted: A method for preparing a high-temperature resistant modified nylon 66 composite fiber material includes the steps of preparing a composite reinforcing antioxidant component, preparing modified nano-silica, and obtaining the composite fiber material.

[0007] The preparation of the composite reinforced antioxidant component involves: adding dried maleic anhydride-grafted polyolefin elastomer, 1,6-hexanediamine, and processing stabilizer to a mixer and stirring; then transferring the mixture to an extruder, purging with nitrogen for primary extrusion, followed by pelletizing and drying to obtain mixed granules; mixing the mixed granules, 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, and p-toluenesulfonic acid evenly, adding the mixture again to a twin-screw extruder, purging with nitrogen for secondary extrusion, followed by pelletizing and vacuum drying to obtain the composite reinforced antioxidant component.

[0008] Furthermore, the raw materials used are proportioned as follows by weight: 95-100 parts POE-g-MAH, 4.5-8 parts 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, 2-2.5 parts 1,6-hexanediamine, 0.1-0.3 parts p-toluenesulfonic acid, and 0.2-0.3 parts processing stabilizer. The processing stabilizer selected is antioxidant 1010.

[0009] Furthermore, in the primary extrusion: the extruder's feeding section temperature is 155-160℃, the compression section temperature is 170-175℃, the melting section temperature is 180-185℃, the die head temperature is 175-180℃, and the screw speed is 120-150 rpm. In the secondary extrusion: the extruder's feeding section temperature is 165-170℃, the compression section temperature is 175-180℃, the melting section temperature is 190-195℃, the die head temperature is 185-190℃, the screw speed is 30-50 rpm, the melting section is equipped with a vacuum exhaust port, the vacuum degree is -0.095MPa to -0.098MPa, and the material residence time is 5-8 minutes. In the forced-air drying: the temperature is 75-80℃, and the drying time is 3-4 hours. The vacuum drying process involves a temperature of 70-75℃, a vacuum degree of -0.09MPa to -0.095MPa, and a drying time of 6-8 hours.

[0010] Furthermore, the preparation of the composite reinforced antioxidant component involves: adding dried maleic anhydride-grafted polyolefin elastomer (POE-g-MAH), 1,6-hexanediamine, and processing stabilizer to a high-speed mixer and stirring at room temperature for 5-8 minutes at a speed of 300-400 rpm; then transferring it to a twin-screw extruder under nitrogen protection for primary extrusion, followed by pelleting and drying to obtain mixed granules; mixing the mixed granules, 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, and p-toluenesulfonic acid evenly, adding it again to the twin-screw extruder under nitrogen protection for secondary extrusion, followed by pelleting and vacuum drying to obtain the composite reinforced antioxidant component.

[0011] Preparation of the modified nano-silica: Nano-silica is added to anhydrous ethanol and ultrasonically dispersed to obtain a dispersion; a composite silane coupling agent is added, the pH value of the system is adjusted, the temperature is raised, and the mixture is stirred and refluxed; then the mixture is cooled, centrifuged, washed, and vacuum dried to obtain modified nano-silica.

[0012] Furthermore, the mass ratio of the nano-silica, the composite silane coupling agent, and anhydrous ethanol is 1:(0.15-0.25):(450-500). The ultrasonic dispersion is performed with an ultrasonic power of 300-400W for 30-40 minutes. The composite silane coupling agent is obtained by compounding silane coupling agent KH550 and silane coupling agent KH560 at a mass ratio of (1.8-2):1. The vacuum drying process is carried out at a temperature of 60-65℃, a vacuum degree of -0.09MPa to -0.095MPa, and a drying time of 10-12 hours.

[0013] Further, the modified nano-silica is prepared as follows: nano-silica is added to anhydrous ethanol and ultrasonically dispersed to obtain a dispersion; a composite silane coupling agent is added, the pH of the system is adjusted to 4.3-4.5 with glacial acetic acid, the temperature is raised to 80-85℃, and the mixture is stirred and refluxed for 4.5-5 hours; after the reaction is completed, the mixture is cooled to room temperature, the solid is collected by centrifugation, washed 3-4 times with anhydrous ethanol, and vacuum dried to obtain modified nano-silica.

[0014] The composite fiber material is prepared by: adding dried nylon 66 resin, composite reinforcing antioxidant component, modified nano silica, pentaerythritol stearate, epoxy resin, and composite antioxidant additive into a mixer and stirring to obtain a premix; melting and extruding the premix, cooling and pelletizing it to obtain a composite masterbatch; vacuum drying the composite masterbatch, melt spinning, two-stage stretching, heat setting, cooling and winding to obtain the composite fiber material.

[0015] Furthermore, the raw materials used are proportioned as follows by weight: 75-88 parts nylon 66 resin, 8-12 parts composite reinforcing antioxidant component, 3-5 parts modified nano silica, 0.6-1.2 parts pentaerythritol stearate, 1-2 parts epoxy resin, and 0.4-0.8 parts composite antioxidant additive. The composite antioxidant additive is a mixture of antioxidant 168 and metal passivator 1024 at a mass ratio of (1.8-2):1.

[0016] Furthermore, the melt extrusion employs a twin-screw extruder with a feeding section temperature of 220-230℃, a compression section temperature of 240-255℃, a melting section temperature of 275-280℃, a die head temperature of 265-275℃, a screw speed of 240-250 rpm, a material residence time of 5-7 minutes, and a vacuum exhaust port in the melting section with a vacuum degree of -0.095MPa to -0.098MPa. The vacuum drying process involves a temperature of 115-120℃, a vacuum degree of -0.095MPa to -0.098MPa, and a drying time of 12-14 hours. The melt spinning process utilizes a screw spinning machine with a spinning box temperature of 270-275℃, a spinneret orifice diameter of 0.2-0.3mm, and a length-to-diameter ratio of 20:1. The two-stage stretching process employs a two-stage tandem hot roller stretching machine. The first-stage stretching temperature is 70-75℃, with a stretching ratio of 2.8-3.2 times; the second-stage stretching temperature is 110-115℃, with a stretching ratio of 1.5-1.8 times. The heat setting process involves a temperature of 165-170℃ and a setting time of 8-10 seconds.

[0017] Furthermore, the composite fiber material is prepared by: adding dried nylon 66 resin, composite reinforcing antioxidant component, modified nano silica, pentaerythritol stearate, epoxy resin, and composite antioxidant additive into a mixer and stirring for 10-15 minutes at a speed of 450-500 rpm to obtain a premix; melting and extruding the premix, cooling and pelletizing it to obtain a composite masterbatch; vacuum drying the composite masterbatch, melt spinning, two-stage stretching, heat setting, cooling and winding to obtain the composite fiber material.

[0018] The beneficial effects of this invention are as follows: (1) In the composite reinforced antioxidant component of the present invention, the hindered phenolic antioxidant groups are anchored by the macromolecular chain and are always stably dispersed in the nylon 66 matrix, continuously exerting antioxidant effects; the hindered phenolic groups terminate the free radical chain degradation reaction by capturing the peroxide free radicals, alkoxy free radicals and hydroxyl free radicals generated by the thermo-oxidative degradation of nylon 66, and inhibit the chain breaking and cross-linking of nylon 66 molecular chains; the grafted polar hindered phenolic groups and the residual acid anhydride groups can react with the terminal amino groups of nylon 66 and the epoxy groups of epoxy resin, improving the interfacial compatibility between the elastomer phase and the nylon 66 matrix; in addition, the POE elastomer segments can significantly improve the toughness of the fiber, solving the problem of increased brittleness caused by inorganic filler filling.

[0019] Modified nano-silica, through its surface organic coating, reduces the surface energy of the powder, enabling nanoscale dispersion within a nylon 66 matrix. Nano-silica particles act as heterogeneous nucleating agents for nylon 66 crystallization, enhancing its crystallinity and crystal perfection, thereby improving the fiber's tensile strength, modulus, and heat distortion temperature. The active amino and epoxy groups on the surface of nano-silica can form stable covalent bonds with the nylon 66 matrix and epoxy resin, tightly binding the inorganic rigid particles to the organic matrix through chemical bonds, forming an organic-inorganic hybrid network. Under external force, stress can be efficiently transferred from the matrix to the rigid nanoparticles through covalent bonds, achieving a significant reinforcement and stiffening effect. Simultaneously, this hybrid network restricts the thermal motion of nylon 66 molecular chains at high temperatures, improving the material's heat distortion temperature and long-term heat resistance stability.

[0020] Furthermore, epoxy resin is a polyepoxy oligomer that can undergo ring-opening reactions with the terminal amino groups of nylon 66, the amino / epoxy groups on the surface of modified nano-silica, and the active amino / residual anhydride groups on the composite reinforcing antioxidant components. This covalently links the nylon 66 matrix, the elastomer toughening phase, and the inorganic nano-reinforcing phase into a complete three-dimensional cross-linked network, further optimizing the interfacial compatibility between the multiple phases and enhancing the high-temperature stability of the molecular chains.

[0021] (2) The high-temperature resistant modified nylon 66 composite fiber material of the present invention has excellent high-temperature resistance. The prepared composite fiber material has a 5% heat loss temperature of 432-438℃ and a heat distortion temperature of 248-255℃.

[0022] (3) The high-temperature resistant modified nylon 66 composite fiber material of the present invention has excellent mechanical properties and aging resistance. The prepared composite fiber material has a breaking strength of 549-562 cN and a breaking elongation of 335-342%; after heat aging for 168 h, the breaking strength retention rate is 91.1-92.3%. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0024] Example 1: A method for preparing a high-temperature resistant modified nylon 66 composite fiber material A method for preparing a high-temperature resistant modified nylon 66 composite fiber material, comprising the following steps: Step 1: Preparation of composite antioxidant components Dry POE-g-MAH, 1,6-hexanediamine, and processing stabilizer were added to a high-speed mixer and stirred at room temperature for 5 minutes at a speed of 400 rpm. Then, the mixture was transferred to a twin-screw extruder and subjected to nitrogen protection for primary extrusion. After pelleting and drying by forced air, mixed granules were obtained. The mixed granules, 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, and p-toluenesulfonic acid were mixed evenly and added to a twin-screw extruder again. After nitrogen protection, a secondary extrusion was performed. After pelleting and vacuum drying, a composite reinforced antioxidant component was obtained.

[0025] The raw materials used are in the following weight ratios: 95 parts POE-g-MAH, 8 parts 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, 2 parts 1,6-hexanediamine, 0.3 parts p-toluenesulfonic acid, and 0.2 parts processing stabilizer.

[0026] The initial extrusion is as follows: the extruder's feeding section temperature is 155℃, the compression section temperature is 170℃, the melting section temperature is 180℃, the die head temperature is 175℃, and the screw speed is 120rpm.

[0027] The secondary extrusion process involves the following conditions: the extruder's feeding section temperature is 165℃, the compression section temperature is 175℃, the melting section temperature is 190℃, the die head temperature is 185℃, the screw speed is 30 rpm, the melting section is equipped with a vacuum exhaust port with a vacuum degree of -0.095 MPa, and the material residence time is 5 minutes.

[0028] The forced-air drying process involves a temperature of 75°C and a drying time of 4 hours.

[0029] The vacuum drying process involves a temperature of 70°C, a vacuum degree of -0.09 MPa, and a drying time of 8 hours.

[0030] The processing stabilizer is antioxidant 1010.

[0031] Step 2: Preparation of modified nano-silica Nano-silica was added to anhydrous ethanol and ultrasonically dispersed to obtain a dispersion. A composite silane coupling agent was added, and the pH of the system was adjusted to 4.3 with glacial acetic acid. The temperature was raised to 80°C, and the mixture was stirred and refluxed for 5 hours. After the reaction was completed, the mixture was cooled to room temperature, centrifuged to collect the solid, washed three times with anhydrous ethanol, and vacuum dried to obtain modified nano-silica.

[0032] The mass ratio of the nano-silica, the composite silane coupling agent, and the anhydrous ethanol is 1:0.15:450.

[0033] The ultrasonic dispersion was performed with an ultrasonic power of 300W and an ultrasonic time of 40min.

[0034] The composite silane coupling agent is obtained by compounding silane coupling agent KH550 and silane coupling agent KH560 at a mass ratio of 1.8:1.

[0035] The vacuum drying process involves a temperature of 60°C, a vacuum degree of -0.09 MPa, and a drying time of 12 hours.

[0036] Step 3: Obtaining composite fiber materials Dry nylon 66 resin, composite reinforcing antioxidant component, modified nano silica, pentaerythritol stearate, epoxy resin, and composite antioxidant additive are added to a mixer and stirred for 10 minutes at a speed of 500 rpm to obtain a premix. The premix is ​​melt-extruded, cooled, and pelletized to obtain a composite masterbatch. The composite masterbatch is vacuum dried, melt-spun, two-stage stretched, heat-set, cooled, and wound to obtain a composite fiber material.

[0037] The raw materials used are in the following weight ratios: 75 parts nylon 66 resin, 12 parts composite reinforcing antioxidant component, 3 parts modified nano silica, 1.2 parts pentaerythritol stearate, 1 part epoxy resin, and 0.8 parts composite antioxidant additive.

[0038] The composite antioxidant is a mixture of antioxidant 168 and metal passivator 1024 in a mass ratio of 1.8:1.

[0039] The melt extrusion process employs a twin-screw extruder with a feeding section temperature of 220°C, a compression section temperature of 240°C, a melting section temperature of 275°C, a die head temperature of 265°C, a screw speed of 240 rpm, a material residence time of 5 min, and a vacuum exhaust port in the melting section with a vacuum degree of -0.095 MPa.

[0040] The vacuum drying process involves a temperature of 115℃, a vacuum degree of -0.095MPa, and a drying time of 14 hours.

[0041] The melt spinning process employs a screw spinning machine with a spinning box temperature of 270°C, a spinneret orifice diameter of 0.2 mm, and an aspect ratio of 20:1.

[0042] The two-stage stretching process employs a two-stage tandem hot roller stretching machine. The first-stage stretching temperature is 70℃ with a stretching ratio of 2.8 times; the second-stage stretching temperature is 110℃ with a stretching ratio of 1.8 times.

[0043] The heat setting process involves a temperature of 165°C and a setting time of 10 seconds.

[0044] Example 2: A method for preparing a high-temperature resistant modified nylon 66 composite fiber material A method for preparing a high-temperature resistant modified nylon 66 composite fiber material, comprising the following steps: Step 1: Preparation of composite antioxidant components Dry POE-g-MAH, 1,6-hexanediamine, and processing stabilizer were added to a high-speed mixer and stirred at room temperature for 6 minutes at a speed of 400 rpm. Then, the mixture was transferred to a twin-screw extruder and subjected to nitrogen protection for primary extrusion. After pelleting and drying by forced air, mixed granules were obtained. The mixed granules, 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, and p-toluenesulfonic acid were mixed evenly and added to a twin-screw extruder again. After nitrogen protection, a secondary extrusion was performed. After pelleting and vacuum drying, a composite reinforced antioxidant component was obtained.

[0045] The raw materials used are in the following weight ratios: 98 parts POE-g-MAH, 6 parts 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, 2 parts 1,6-hexanediamine, 0.2 parts p-toluenesulfonic acid, and 0.25 parts processing stabilizer.

[0046] The initial extrusion is as follows: the extruder's feeding section temperature is 155℃, the compression section temperature is 170℃, the melting section temperature is 180℃, the die head temperature is 175℃, and the screw speed is 130rpm.

[0047] The secondary extrusion process involves the following conditions: the extruder's feeding section temperature is 165℃, the compression section temperature is 175℃, the melting section temperature is 190℃, the die head temperature is 185℃, the screw speed is 40rpm, the melting section is equipped with a vacuum exhaust port with a vacuum degree of -0.098MPa, and the material residence time is 6min.

[0048] The forced-air drying process involves a temperature of 80℃ and a drying time of 4 hours.

[0049] The vacuum drying process involves a temperature of 75°C, a vacuum degree of -0.095 MPa, and a drying time of 7 hours.

[0050] The processing stabilizer is antioxidant 1010.

[0051] Step 2: Preparation of modified nano-silica Nano-silica was added to anhydrous ethanol and ultrasonically dispersed to obtain a dispersion. A composite silane coupling agent was added, and the pH of the system was adjusted to 4.4 with glacial acetic acid. The temperature was raised to 85°C, and the mixture was stirred and refluxed for 4.5 h. After the reaction was completed, the mixture was cooled to room temperature, and the solid was collected by centrifugation. The solid was washed four times with anhydrous ethanol and dried under vacuum to obtain modified nano-silica.

[0052] The mass ratio of the nano-silica, composite silane coupling agent, and anhydrous ethanol is 1:0.2:480.

[0053] The ultrasonic dispersion was performed with an ultrasonic power of 400W and an ultrasonic time of 40min.

[0054] The composite silane coupling agent is obtained by compounding silane coupling agent KH550 and silane coupling agent KH560 at a mass ratio of 2:1.

[0055] The vacuum drying process involves a temperature of 65°C, a vacuum degree of -0.095 MPa, and a drying time of 11 hours.

[0056] Step 3: Obtaining composite fiber materials Dry nylon 66 resin, composite reinforcing antioxidant component, modified nano silica, pentaerythritol stearate, epoxy resin, and composite antioxidant additive are added to a mixer and stirred for 15 minutes at a speed of 500 rpm to obtain a premix. The premix is ​​melt-extruded, cooled, and pelletized to obtain a composite masterbatch. The composite masterbatch is vacuum dried, melt-spun, two-stage stretched, heat-set, cooled, and wound to obtain a composite fiber material.

[0057] The raw materials used are formulated in the following proportions by weight: 80 parts nylon 66 resin, 10 parts composite reinforcing antioxidant component, 4 parts modified nano silica, 1 part pentaerythritol stearate, 1.5 parts epoxy resin, and 0.6 parts composite antioxidant additive.

[0058] The composite antioxidant is a mixture of antioxidant 168 and metal passivator 1024 in a mass ratio of 2:1.

[0059] The melt extrusion process employs a twin-screw extruder with a feeding section temperature of 225°C, a compression section temperature of 245°C, a melting section temperature of 275°C, a die head temperature of 270°C, a screw speed of 240 rpm, a material residence time of 6 min, and a vacuum exhaust port in the melting section with a vacuum degree of -0.098 MPa.

[0060] The vacuum drying process involves a temperature of 120°C, a vacuum degree of -0.098 MPa, and a drying time of 13 hours.

[0061] The melt spinning process employs a screw spinning machine with a spinning box temperature of 270°C, a spinneret orifice diameter of 0.3 mm, and an aspect ratio of 20:1.

[0062] The two-stage stretching process employs a two-stage tandem hot roller stretching machine. The first-stage stretching temperature is 70℃ with a stretching ratio of 3 times; the second-stage stretching temperature is 110℃ with a stretching ratio of 1.6 times.

[0063] The heat setting process involves a temperature of 165°C and a setting time of 10 seconds.

[0064] Example 3: A method for preparing a high-temperature resistant modified nylon 66 composite fiber material A method for preparing a high-temperature resistant modified nylon 66 composite fiber material, comprising the following steps: Step 1: Preparation of composite antioxidant components Dry POE-g-MAH, 1,6-hexanediamine, and processing stabilizer were added to a high-speed mixer and stirred at room temperature for 8 minutes at 300 rpm. Then, the mixture was transferred to a twin-screw extruder and subjected to nitrogen protection for primary extrusion. After pelleting and drying, mixed granules were obtained. The mixed granules, 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, and p-toluenesulfonic acid were mixed evenly and added to a twin-screw extruder again. After nitrogen protection, a second extrusion was performed. After pelleting and vacuum drying, a composite reinforced antioxidant component was obtained.

[0065] The raw materials used are in the following weight ratios: 100 parts POE-g-MAH, 4.5 parts 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, 2.5 parts 1,6-hexanediamine, 0.1 parts p-toluenesulfonic acid, and 0.3 parts processing stabilizer.

[0066] The initial extrusion is as follows: the extruder's feeding section temperature is 160℃, the compression section temperature is 175℃, the melting section temperature is 185℃, the die head temperature is 180℃, and the screw speed is 150rpm.

[0067] The secondary extrusion process involves the following conditions: the extruder's feeding section temperature is 170℃, the compression section temperature is 180℃, the melting section temperature is 195℃, the die head temperature is 190℃, the screw speed is 50rpm, the melting section is equipped with a vacuum exhaust port with a vacuum degree of -0.098MPa, and the material residence time is 8min.

[0068] The forced-air drying process involves a temperature of 80℃ and a drying time of 3 hours.

[0069] The vacuum drying process involves a temperature of 75°C, a vacuum degree of -0.095 MPa, and a drying time of 6 hours.

[0070] The processing stabilizer is antioxidant 1010.

[0071] Step 2: Preparation of modified nano-silica Nano-silica was added to anhydrous ethanol and ultrasonically dispersed to obtain a dispersion. A composite silane coupling agent was added, and the pH of the system was adjusted to 4.5 with glacial acetic acid. The temperature was raised to 85°C, and the mixture was stirred and refluxed for 4.5 h. After the reaction was completed, the mixture was cooled to room temperature, and the solid was collected by centrifugation. The solid was washed four times with anhydrous ethanol and dried under vacuum to obtain modified nano-silica.

[0072] The mass ratio of the nano-silica, the composite silane coupling agent, and the anhydrous ethanol is 1:0.25:500.

[0073] The ultrasonic dispersion was performed with an ultrasonic power of 400W and an ultrasonic time of 30min.

[0074] The composite silane coupling agent is obtained by compounding silane coupling agent KH550 and silane coupling agent KH560 at a mass ratio of 2:1.

[0075] The vacuum drying process involves a temperature of 65°C, a vacuum degree of -0.095 MPa, and a drying time of 10 hours.

[0076] Step 3: Obtaining composite fiber materials Dry nylon 66 resin, composite reinforcing antioxidant component, modified nano silica, pentaerythritol stearate, epoxy resin, and composite antioxidant additive are added to a mixer and stirred for 15 minutes at a speed of 450 rpm to obtain a premix. The premix is ​​melt-extruded, cooled, and pelletized to obtain a composite masterbatch. The composite masterbatch is vacuum dried, melt-spun, two-stage stretched, heat-set, cooled, and wound to obtain a composite fiber material.

[0077] The raw materials used are in the following weight ratios: 88 parts nylon 66 resin, 8 parts composite reinforcing antioxidant component, 5 parts modified nano silica, 0.6 parts pentaerythritol stearate, 2 parts epoxy resin, and 0.4 parts composite antioxidant additive.

[0078] The composite antioxidant is a mixture of antioxidant 168 and metal passivator 1024 in a mass ratio of 2:1.

[0079] The melt extrusion process employs a twin-screw extruder with a feeding section temperature of 230°C, a compression section temperature of 255°C, a melting section temperature of 280°C, a die head temperature of 275°C, a screw speed of 250 rpm, a material residence time of 7 min, and a vacuum exhaust port in the melting section with a vacuum degree of -0.098 MPa.

[0080] The vacuum drying process involves a temperature of 120°C, a vacuum degree of -0.098 MPa, and a drying time of 12 hours.

[0081] The melt spinning process employs a screw spinning machine with a spinning box temperature of 275°C, a spinneret orifice diameter of 0.3 mm, and an aspect ratio of 20:1.

[0082] The two-stage stretching process employs a two-stage tandem hot roller stretching machine. The first-stage stretching temperature is 75℃ with a stretching ratio of 3.2 times; the second-stage stretching temperature is 115℃ with a stretching ratio of 1.5 times.

[0083] The heat setting process involves a temperature of 170°C and a setting time of 8 seconds.

[0084] Comparative Example 1 A method for preparing a high-temperature resistant modified nylon 66 composite fiber material, comprising the following steps: Step 1: Preparation of modified nano-silica This step is the same as the "Preparation of Modified Nano-Silica" step in Example 2.

[0085] Step 2: Obtaining composite fiber materials Dry nylon 66 resin, POE-g-MAH, modified nano silica, pentaerythritol stearate, epoxy resin, and composite antioxidant additives are added to a mixer and stirred for 15 minutes at a speed of 500 rpm to obtain a premix. The premix is ​​melt-extruded, cooled, and pelletized to obtain a composite masterbatch. The composite masterbatch is vacuum dried, melt-spun, two-stage stretched, heat-set, cooled, and wound to obtain a composite fiber material.

[0086] The raw materials used are in the following weight ratios: 80 parts nylon 66 resin, 10 parts POE-g-MAH, 4 parts modified nano silica, 1 part pentaerythritol stearate, 1.5 parts epoxy resin, and 0.6 parts composite antioxidant.

[0087] The composite antioxidant is a mixture of antioxidant 168 and metal passivator 1024 in a mass ratio of 2:1.

[0088] The melt extrusion process employs a twin-screw extruder with a feeding section temperature of 225°C, a compression section temperature of 245°C, a melting section temperature of 275°C, a die head temperature of 270°C, a screw speed of 240 rpm, a material residence time of 6 min, and a vacuum exhaust port in the melting section with a vacuum degree of -0.098 MPa.

[0089] The vacuum drying process involves a temperature of 120°C, a vacuum degree of -0.098 MPa, and a drying time of 13 hours.

[0090] The melt spinning process employs a screw spinning machine with a spinning box temperature of 270°C, a spinneret orifice diameter of 0.3 mm, and an aspect ratio of 20:1.

[0091] The two-stage stretching process employs a two-stage tandem hot roller stretching machine. The first-stage stretching temperature is 70℃ with a stretching ratio of 3 times; the second-stage stretching temperature is 110℃ with a stretching ratio of 1.6 times.

[0092] The heat setting process involves a temperature of 165°C and a setting time of 10 seconds.

[0093] Comparative Example 2 A method for preparing a high-temperature resistant modified nylon 66 composite fiber material, comprising the following steps: Step 1: Preparation of composite antioxidant components This step is the same as the "Preparation of Composite Enhanced Antioxidant Components" step in Example 2.

[0094] Step 2: Obtaining composite fiber materials Dry nylon 66 resin, composite reinforcing antioxidant components, nano silica, pentaerythritol stearate, epoxy resin, and composite antioxidant additives are added to a mixer and stirred for 15 minutes at a speed of 500 rpm to obtain a premix. The premix is ​​melt-extruded, cooled, and pelletized to obtain a composite masterbatch. The composite masterbatch is vacuum dried, melt-spun, two-stage stretched, heat-set, cooled, and wound to obtain a composite fiber material.

[0095] The raw materials used are formulated in the following proportions by weight: 80 parts nylon 66 resin, 10 parts composite reinforcing antioxidant component, 4 parts nano silica, 1 part pentaerythritol stearate, 1.5 parts epoxy resin, and 0.6 parts composite antioxidant additive.

[0096] The composite antioxidant is a mixture of antioxidant 168 and metal passivator 1024 in a mass ratio of 2:1.

[0097] The melt extrusion process employs a twin-screw extruder with a feeding section temperature of 225°C, a compression section temperature of 245°C, a melting section temperature of 275°C, a die head temperature of 270°C, a screw speed of 240 rpm, a material residence time of 6 min, and a vacuum exhaust port in the melting section with a vacuum degree of -0.098 MPa.

[0098] The vacuum drying process involves a temperature of 120°C, a vacuum degree of -0.098 MPa, and a drying time of 13 hours.

[0099] The melt spinning process employs a screw spinning machine with a spinning box temperature of 270°C, a spinneret orifice diameter of 0.3 mm, and an aspect ratio of 20:1.

[0100] The two-stage stretching process employs a two-stage tandem hot roller stretching machine. The first-stage stretching temperature is 70℃ with a stretching ratio of 3 times; the second-stage stretching temperature is 110℃ with a stretching ratio of 1.6 times.

[0101] The heat setting process involves a temperature of 165°C and a setting time of 10 seconds.

[0102] Example 4 Performance Testing (1) Example 1 3 and Comparative Example 1 2. The high-temperature resistance of the prepared composite fiber material was tested. Thermogravimetric analysis was performed according to the test method specified in GB / T 27761-2011, and the 5% thermogravimetric temperature was measured. The heat distortion temperature was tested according to the test method specified in ASTM D648, with a heating rate of 2℃ / min, and the temperature at which the sample bent by 0.25mm was recorded. The test results are shown in Table 1.

[0103] Table 1 As shown in Table 1, the composite fiber materials prepared in Examples 1-3 have a 5% thermogravimetric temperature of 432-438℃ and a heat distortion temperature of 248-255℃. This demonstrates that the composite fiber materials prepared in this invention have excellent high-temperature resistance.

[0104] (2) Example 1 3 and Comparative Example 1 2. The prepared composite fiber materials were tested for mechanical properties and aging resistance. Breaking strength and elongation at break were tested according to the test methods specified in GB / T3916-2013. The samples were placed in a heat aging oven at 180℃ for 168 hours, and then removed to test the retention rate of breaking strength. The test results are shown in Table 2.

[0105] Table 2 As shown in Table 2, the composite fiber materials prepared in Examples 1-3 have a tensile strength of 549-562 cN and a tensile elongation of 335-342%. After 168 h of thermal aging, the tensile strength retention rate is 91.1-92.3%. This demonstrates that the composite fiber materials prepared by this invention have excellent mechanical properties and aging resistance.

[0106] The specific parameters of the raw materials used in this invention are as follows: The nylon 66 resin is fiber grade, with a relative viscosity of 2.4-2.8 and a terminal amino content of 40-50 mmol / kg.

[0107] The maleic anhydride grafting rate of the POE-g-MAH is 1-1.5%, and the melt index is 2-4 g / 10 min (190℃ / 2.16 kg).

[0108] The nano-silica has a particle size of 20-50 nm and a specific surface area of ​​200±50 m². 2 / g.

[0109] The epoxy resin used is epoxy resin E-20.

[0110] Obviously, there are many other possible implementation methods under the concept of this invention. It should be stated here that any changes made under the inventive concept of this invention will fall within the protection scope of this invention.

Claims

1. A method for preparing a high-temperature resistant modified nylon 66 composite fiber material, characterized in that: The process includes steps such as preparing composite reinforced antioxidant components, preparing modified nano-silica, and obtaining composite fiber materials. The preparation of the composite reinforced antioxidant component involves: adding dried maleic anhydride-grafted polyolefin elastomer, 1,6-hexanediamine, and processing stabilizer to a mixer and stirring; then transferring the mixture to an extruder, purging with nitrogen for primary extrusion, followed by pelletizing and drying to obtain mixed granules; mixing the mixed granules, 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, and p-toluenesulfonic acid evenly, adding the mixture again to a twin-screw extruder, purging with nitrogen for secondary extrusion, followed by pelletizing and vacuum drying to obtain the composite reinforced antioxidant component; the raw material weight ratio used is: POE-g-MAH 95-100 parts, 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid 4.5-8 parts, 1,6-hexanediamine 2-2.5 parts, p-toluenesulfonic acid 0.1-0.3 parts, and processing stabilizer 0.2-0.3 parts; The modified nano-silica is prepared as follows: nano-silica is added to anhydrous ethanol and ultrasonically dispersed to obtain a dispersion; a composite silane coupling agent is added, the pH value of the system is adjusted, the temperature is raised, and the mixture is stirred and refluxed; then the mixture is cooled, centrifuged, washed, and vacuum dried to obtain modified nano-silica; in the preparation steps of the modified nano-silica, the mass ratio of nano-silica, composite silane coupling agent, and anhydrous ethanol is 1:(0.15-0.25):(450-500); the composite silane coupling agent is obtained by compounding silane coupling agent KH550 and silane coupling agent KH560 at a mass ratio of (1.8-2):1; The composite fiber material is prepared by: adding dried nylon 66 resin, composite reinforcing antioxidant component, modified nano silica, pentaerythritol stearate, epoxy resin, and composite antioxidant additive into a mixer and stirring to obtain a premix; melting and extruding the premix, cooling and pelletizing it to obtain a composite masterbatch; vacuum drying the composite masterbatch, melt spinning, two-stage stretching, heat setting, cooling and winding to obtain the composite fiber material.

2. The method for preparing a high-temperature resistant modified nylon 66 composite fiber material according to claim 1, characterized in that: The primary extrusion: the extruder's feeding section temperature is 155-160℃, the compression section temperature is 170-175℃, the melting section temperature is 180-185℃, the die head temperature is 175-180℃, and the screw speed is 120-150 rpm; the secondary extrusion: the extruder's feeding section temperature is 165-170℃, the compression section temperature is 175-180℃, the melting section temperature is 190-195℃, the die head temperature is 185-190℃, the screw speed is 30-50 rpm, and the material residence time is 5-8 minutes.

3. The method for preparing a high-temperature resistant modified nylon 66 composite fiber material according to claim 1, characterized in that: In the preparation steps of the modified nano-silica, the pH value of the system is adjusted by using glacial acetic acid to adjust the pH value of the system to 4.3-4.

5.

4. The method for preparing a high-temperature resistant modified nylon 66 composite fiber material according to claim 1, characterized in that: In the step of preparing the composite fiber material, the raw materials used are in the following weight ratios: 75-88 parts of nylon 66 resin, 8-12 parts of composite reinforcing antioxidant component, 3-5 parts of modified nano silica, 0.6-1.2 parts of pentaerythritol stearate, 1-2 parts of epoxy resin, and 0.4-0.8 parts of composite antioxidant additive.

5. The method for preparing a high-temperature resistant modified nylon 66 composite fiber material according to claim 1, characterized in that: The composite antioxidant is a mixture of antioxidant 168 and metal passivator 1024 in a mass ratio of (1.8-2):

1.

6. The method for preparing a high-temperature resistant modified nylon 66 composite fiber material according to claim 1, characterized in that: The melt extrusion process employs a twin-screw extruder with a feeding section temperature of 220-230℃, a compression section temperature of 240-255℃, a melting section temperature of 275-280℃, a die head temperature of 265-275℃, a screw speed of 240-250 rpm, and a material residence time of 5-7 minutes.

7. The method for preparing a high-temperature resistant modified nylon 66 composite fiber material according to claim 1, characterized in that: The two-stage stretching process employs a two-stage tandem hot roller stretching machine. The first-stage stretching temperature is 70-75℃, with a stretching ratio of 2.8-3.2 times. The second-stage stretching temperature is 110-115℃, with a stretching ratio of 1.5-1.8 times.

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