High-strength and high-elasticity PA66 fiber as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of melt spinning, and discloses a high-strength and high-elasticity PA66 fiber as well as a preparation method and application thereof. The method comprises the following steps: mixing PA66 and an elastomer according to a specific ratio, drying, carrying out melt spinning, directly inducing to form a high-regularity oriented lamellar crystal structure in the spinning process by utilizing a melt stretching technology, and carrying out annealing treatment, so that the tensile modulus and yield strength of the fiber can be remarkably improved without a traditional post-stretching process. According to the process, the flow is simplified, the energy consumption is reduced, the elastic recovery rate of the prepared fiber can be greater than 90% at room temperature, and the technical problem that the strength and the elasticity of the traditional PA66 fiber are difficult to consider at the same time is successfully solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of melt spinning, and particularly relates to a high-strength and high-elasticity PA66 fiber and a preparation method and application thereof. BACKGROUND

[0002] Nylon 66 (PA66) is one of the earliest synthetic fibers to achieve industrial production. With its excellent mechanical strength, wear resistance, heat resistance and chemical stability, it has long occupied an important position in the fields of tire cord, airbag, high-grade sportswear and industrial rope, etc. However, with the rapid development of modern high-end equipment, intelligent textiles and biomedical materials, the market has put forward unprecedentedly stringent requirements on the comprehensive performance of fiber materials: while having extremely high strength to bear heavy load, it must also have excellent elastic recovery ability to adapt to dynamic deformation and maintain shape memory. This combination of "high strength and high elasticity" has long been a key target and major challenge in the field of synthetic fibers, especially PA66 fibers.

[0003] The preparation of traditional PA66 fibers relies heavily on the classic process route of melt spinning-post stretching-heat setting. Through the post-stretching process, the orientation degree and crystallinity of the molecular chain along the fiber axis can be greatly improved, thereby significantly improving the tensile modulus and yield strength of the fiber. However, the crystal structure induced by this post-stretching is usually mainly in the form of micro-fibril with relatively imperfect and wide size distribution. Its defects are: the contradiction between strength and elasticity: high orientation and crystallinity bring high strength and high modulus, but often at the expense of the ductility and elasticity of the material. The fiber becomes rigid and lacks flexible resilience. Process complexity and energy consumption: the multi-step post-stretching and heat setting process increases the complexity and energy consumption of the production process. Structural limitations: the interface between the crystal region and the amorphous region of the crystal structure formed by the traditional method is prone to stress concentration when subjected to cyclic load, leading to plastic deformation accumulation and difficulty in breaking through the elastic recovery rate (usually below 70%).

[0004] In recent years, academia and industry have realized that to break this performance bottleneck, innovation must be made from the fundamental source of microstructure design of the fiber. Studies have shown that an ideal structure called "oriented lamella" is expected to solve the problems of strength and elasticity at the same time. This structure is composed of highly regular nanocrystal lamellas that are preferentially aligned along the fiber direction, connected by flexible amorphous segments. When stretched, the lamella itself provides strength and modulus as a rigid unit; while the amorphous region between the lamellas and the possible reversible slip and rotation of the lamellas provide the material with a large elastic deformation capacity and energy dissipation mechanism. However, how to efficiently and controllably construct such a highly ordered nanostructure in the continuous fiber processing process is a highly challenging core scientific problem. SUMMARY

[0005] In order to overcome the shortcomings and deficiencies existing in the prior art, the primary purpose of the present application is to provide a preparation method of high-strength and high-elasticity PA66 fiber; the method is to mix PA66 and elastomer, and to spin the mixture through a melt spinning process, and the obtained fiber is annealed and not stretched to obtain high-strength and high-elasticity PA66 fiber, so that the tensile modulus and yield strength can be improved, and an elastic recovery effect of more than 90% can be realized at room temperature.

[0006] Another purpose of the present application is to provide high-strength and high-elasticity PA66 fiber prepared by the above preparation method.

[0007] Still another purpose of the present application is to provide an application of the above high-strength and high-elasticity PA66 fiber.

[0008] The purpose of the present application is achieved by the following technical solutions: A preparation method of high-strength and high-elasticity PA66 fiber, according to the following operation steps: S1, selecting PA66 and elastomer raw materials, and pretreating the raw materials respectively, specifically drying and pretreating in an oven at 85℃ for 4h; the elastomer is nylon 6 / spandex elastomer; S2, putting the PA66 and elastomer pretreated in step S1 into a mixer according to a mass ratio of 9:1, 8:2, 7:3 or 6:4, and mixing for 5 minutes; S3, putting the mixed raw materials into a single-screw melt spinning machine, controlling the heating temperature at 270-280℃, so that the raw materials are melt-extruded to obtain a yarn, the yarn is solidified into a fiber through a cooling water tank; the obtained fiber is stretched, and the stretched fiber is wound through a winding machine to form a fiber product in the form of a bobbin; S4, putting the fiber product obtained in step S3 into an oven for drying at a temperature of 85℃; increasing the temperature of the dried fiber product in the oven to 150℃ at a speed of <3℃ / min, and maintaining the temperature for 20 minutes for annealing treatment; reducing the temperature in the oven to below 40-50℃ at a speed of 2-3℃ / min, and taking out to obtain high-strength and high-elasticity PA66 fiber.

[0009] The drying in step S1 is to dry the raw materials to a water content of 0.02wt% or less.

[0010] The PA66 in step S1 is nylon 66 with a relative viscosity of 2.5, 3.1 or 4.1.

[0011] The mixer in step S2 is a high-speed vortex mixer; the mixing is carried out at a speed of 1200 rpm under the conditions of room temperature and relative humidity less than 50%.

[0012] The mass ratio of the PA66 and the elastomer after the pretreatment in step S2 is 8:2.

[0013] The length-diameter ratio of the single screw melt spinning machine in step S3 is greater than or equal to 28:1, and the screw rotation speed is set to a stable value of 10-20 rpm; and the total draw ratio of the drawing is set to 3.0-5.0 times.

[0014] A high-strength and high-elasticity PA66 fiber prepared by the preparation method described above, wherein the strength of the high-strength and high-elasticity PA66 fiber is up to 6.0-8.8 cN / dtex, the elongation at break is 30%-50%, and the elastic recovery rate is greater than 90%.

[0015] The high-strength and high-elasticity PA66 fiber is vacuum-sealed and packaged in a high-barrier aluminum-plastic composite bag with a water vapor transmission rate of less than 0.5 g / m²·day and an oxygen transmission rate of less than 1 cm ³ / m ² ·day, the vacuum degree is controlled to be below -0.09 MPa, a drying agent and an oxygen indicator card are placed in the bag, and the sealed product is stored in a special warehouse with a temperature of less than or equal to 25 DEG C and a relative humidity of less than or equal to 60%, in a cool, dry and light-proof manner.

[0016] The high-strength and high-elasticity PA66 fiber described above successfully breaks through the performance limitations of single materials due to its high strength and high elastic recovery similar to spandex, and is particularly suitable for "critical task" application scenarios that need to withstand high loads and undergo repeated stretching, bending and impact while maintaining shape and function without failure, such as high-end safety protection and police equipment, high-performance sports and outdoor products, industrial and special materials, high-end textiles and medical rehabilitation, precision devices and composite materials, etc.

[0017] Compared with the prior art, the present application has the following advantages and beneficial effects: (1) Structural design: the high-strength and high-elasticity PA66 fiber obtained by the present application has a high-regularity oriented lamellar structure; the lamellar itself is highly ordered and arranged along the fiber direction, connected by more regular and more ductile amorphous segments, forming a continuous and uniform nanocomposite network similar to "brick-mud". The structure determines the performance, and this lamellar network structure is an ideal toughening model in polymer physics, which fundamentally solves the "strength-elasticity" contradiction and provides a perfect microstructure.

[0018] (2) Process: ① Process simplification: The complex and large equipment post-drawing unit is omitted, and the production line is more compact. ② Energy consumption reduction: The huge energy consumption of post-drawing is avoided, and the annealing energy consumption can also be reduced due to the fact that the structure has been basically formed. ③ Efficiency and controllability: The structure is formed at the source, and the process window is more easily controlled, and the production stability is higher. ④ Active guidance: The structure guidance (stretching) is carried out at the same time as the crystallization occurs, and the molecular chains are "actively" arranged into the ideal structure, and the internal stress is smaller, and the obtained fiber structure is more perfect and has fewer defects.

[0019] (3) Final performance: The high-strength and high-elasticity PA66 fiber obtained by the present application has the following high performance: ① High-strength and high-elasticity synergy: High modulus / high strength is derived from high regularity / high orientation lamellar hard phase; super-high elastic recovery (>90%) is derived from regular and flexible amorphous region and possible reversible deformation mechanism of lamellar structure itself. (2) Small internal stress in the structure, which can be further stabilized by annealing, thus having more excellent creep resistance, fatigue resistance and long-term dimensional stability. (3) The regular nanolamellar structure provides a more ordered template and interface for subsequent functionalization (such as thermal conductivity, electrical conductivity, intelligent response). BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the infrared spectrum of the high-strength and high-elasticity PA66 fiber prepared in Example 3.

[0021] Figure 2 is the thermogravimetric analysis diagram of the high-strength and high-elasticity PA66 fiber prepared in Example 3. DETAILED DESCRIPTION

[0022] The present application will be further described in detail below in conjunction with examples, but the embodiments of the present application are not limited thereto.

[0023] The raw materials used in the following examples are all from the market.

[0024] The PA66 raw material is nylon 6 with a relative viscosity of 2.5, 3.1 or 4.1.

[0025] The elastomer is a nylon 6 / spandex elastomer; Raw material preparation: Strictly select the raw materials of PA66 and elastomer, and test and record the raw materials; To achieve stable preparation of high-strength and high-elasticity PA66 fiber, the specifications and quality standards of polyamide 66 (PA66) and elastomer raw materials need to be first determined according to the product performance target. It is necessary to select a reliable supplier, purchase raw materials with matching model, traceable quality and compliance with relevant regulations. After the arrival of raw materials, strict incoming inspection should be carried out, covering appearance, size, chemical composition and mechanical properties, etc., to ensure that only qualified batches are received.

[0026] Special storage is implemented according to the characteristics of raw materials: PA66 needs to be stored in a moisture-proof and light-proof manner, and spandex elastomer should be sealed to prevent oxidation. Complete archives of all batches of raw materials should be established, and the source, test data and storage state should be recorded in detail to realize traceability and quality control in the whole process.

[0027] The following examples use a laboratory small single-screw melt spinning machine equipped with a melt stretching device, which is located 10-50 cm below the spinneret, and can realize precise control of temperature, airflow and drafting force.

[0028] The performance test methods used in the following examples are as follows: (1) Infrared spectrum test: according to the national standard GB / T 6040, using Nicolet iS50R type Fourier infrared spectrometer for testing. The purpose is to verify whether the raw materials have been degraded, to confirm that the elastomer has been successfully introduced and uniformly dispersed, and to understand the high-elastic high-strength mechanism from the chemical bond level.

[0029] (2) Structure characterization: wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) are used to characterize the crystalline structure, orientation degree and lamellar morphology of the fiber.

[0030] (3) Tensile modulus and yield strength: tested on a universal material testing machine according to ASTM D3822 standard, with an initial clamping distance of 100 mm and a tensile speed of 50 mm / min. The tensile modulus is taken as the slope in the strain range of 0.1%-0.5%.

[0031] (4) Elastic recovery rate: the fiber is stretched to 5% strain, unloaded after 10 seconds, and the residual strain er is measured after 60 seconds. The elastic recovery rate R = (5% - er) / 5% x 100%.

[0032] The preparation method of high-strength high-elasticity PA66 fiber in the following examples is as follows: S1, select PA66 and elastomer raw materials, pretreat the raw materials respectively, specifically dry pretreatment in an oven at 85°C for 4h; the dry air dew point is controlled below-40°C. This step aims to completely eliminate moisture in the raw materials, prevent PA66 from hydrolytic degradation in subsequent high-temperature melt processing, and ensure melt flowability and blending uniformity. After drying, a Karl Fischer moisture meter is used for detection to ensure that the moisture content of the mixed raw materials is reduced to below 0.02wt%. After this pretreatment, the raw materials can enter the melt spinning process.

[0033] Through the above-mentioned precise control of the pre-treatment of moisture, the risk of moisture-induced polymer degradation is fundamentally eliminated, which provides a crucial material basis for subsequent realization of high-ratio melt stretching, formation of regular oriented crystalline structure, and obtaining of high-strength, high-elasticity and stable performance fiber products. This step is the key guarantee for stable operation of the process and achievement of performance targets.

[0034] S2, the PA66 and the elastomer with qualified water content after the pre-treatment of step S1 are accurately weighed by a high-precision electronic scale, and the raw materials are prepared according to the mass ratio of 450g:50g, 400g:100g, 350g:150g, 300g:200g; the weighed raw materials are put into a high-speed vortex mixer together, and mixed at a speed of 1200 rpm under the condition of room temperature and relative humidity less than 50% for 5 minutes; this process aims to realize micro-uniform pre-dispersion of the two components in the solid state, and establish uniform initial distribution for subsequent melt blending. After the mixing is completed, the uniformity of the mixing is qualitatively confirmed by rapid sampling and image analysis method. The pre-mixed material needs to be immediately transferred into a sealed container or a conveying system, and is prepared for melt extrusion.

[0035] Through the above-mentioned pre-mixing of accurately controlled mixing ratio and kinetic parameters, it is ensured that the PA66 (continuous phase matrix) and the elastomer (dispersed phase) can enter the melt field with the most optimized spatial distribution. This effectively shortens the shear history and residence time required to reach molecular / micron level dispersion in the melt extruder, reduces the risk of high-temperature thermal degradation, is the key precursor step for finally forming a stable and uniform "rigidity-elasticity" two-phase microstructure, and realizing synchronous improvement of high strength and high elasticity of the fiber.

[0036] S3, the mixed raw materials are put into a single screw melt spinning machine, the heating temperature is controlled at 270-280°C, the raw materials are melt extruded to obtain a yarn, and the yarn is solidified into a fiber through a cooling water tank; the obtained fiber is stretched, and the stretched fiber is wound through a winding machine to prepare a fiber product in the form of a bobbin; A single screw melt spinning machine is selected, the length-diameter ratio (L / D) of the screw is recommended to be greater than or equal to 28:1, and a multi-section independent temperature control system and a high-precision metering pump are provided, and a spinneret (pore diameter is designed according to the target fiber fineness) is provided. The temperature is between 270-280°C, the screw rotation speed is set to a stable value of 10-20 rpm, and the metering pump is matched to ensure stable melt delivery and non-pulsating pressure.

[0037] Deionized water is used in the cooling water tank to prevent impurities from adhering. The path length should ensure that the yarn is completely solidified into a solid state before entering the stretching zone to prevent adhesion. The cooling rate directly affects the crystallinity and grain size, which is the key to regulating the rigidity and toughness balance of the fiber.

[0038] The two or more stages of godets are used to achieve the condition that the linear speed of the godets in the later stage (V2) is significantly higher than that of the godets in the former stage (V1). The key parameter is the draw ratio (DR): DR = V2 / V1. The total draw ratio is the core process parameter, which needs to be optimized according to the target performance. The total draw ratio can be set between 3.0-5.0 times. The drawing is usually carried out in the plastic state of the yarn with residual heat (slightly higher than the glass transition temperature). The orientation degree of the macromolecular chains along the fiber axis and the integrity of the crystalline region are greatly improved, directly and significantly improving the tensile strength and modulus of the fiber.

[0039] S4, drying the fiber product obtained in step S3 in an oven at a temperature of 85℃; increasing the temperature of the dried fiber product in the oven to 150℃ at a speed of <3℃ / min, and keeping the temperature for 20 minutes, only annealing treatment is carried out, no post-drawing is carried out; reducing the temperature in the oven to below 40-50℃ at a speed of 2-3℃ / min, and taking out to obtain the high-strength and high-elasticity PA66 fiber.

[0040] Ensure that the surface of the PA66 part to be annealed is clean, free of oil stains, dust or other chemicals, so as to avoid degradation or contamination at high temperature. Place the part smoothly on the net rack or tray of the oven, and ensure that the air can circulate evenly. Avoid stacking or contacting the parts to prevent uneven heating and local deformation. For long strip-shaped or easily deformed parts, special clamps may be used to fix them in the desired shape for annealing. Annealing temperature: usually set in the range higher than the glass transition temperature of PA66, but far below its melting point. 150℃ can be used. The holding time depends on the maximum wall thickness of the part, and 20 minutes is used in the present application. For very thick parts or large load conditions, the time needs to be appropriately extended to ensure that the heat penetrates to the core.

[0041] Place the part in the oven preheated to the target temperature, or slowly increase the temperature with the oven (the recommended rate is not more than 2-3℃ / min), avoiding thermal shock. The key is that the cooling must be slow to room temperature (usually below 40℃). It is absolutely forbidden to take out the part immediately after the holding time ends and expose it to room temperature air, which will cause a large difference in cooling speed between the surface and the interior, resulting in new, even greater internal stress.

[0042] Examples 1-8 were prepared according to the raw material ratio and process parameters shown in Table 1, respectively.

[0043] Table 1: Each ratio and parameter condition of Examples 1-8

[0044] The infrared spectrum analysis (as shown in Figure 1 Table 2) of the product obtained in Example 2 confirmed its chemical structure: 3296 cm -¹ (N-H stretching vibration), 1635 cm-¹ (Amide I band, C=O stretching vibration) and 1529 cm -¹ The characteristic strong peak at the (amide II band) confirms the complete preservation of the PA66 matrix structure; while at 1264 cm⁻¹... -¹ With 1196 cm -¹ The characteristic peak of CO stretching vibration at the point directly proves the successful introduction of the elastomer (such as thermoplastic polyurethane). The sharp NH peak of PA66 in the spectrum indicates that it is in a strongly hydrogen-bonded state. This reveals that there is a strong intermolecular interaction between the amide group of PA66 and the polar group (such as C=O) in the elastomer, which constitutes good interfacial compatibility between the two phases. This chemically blended and tightly bonded microstructure is the fundamental reason why the fiber can simultaneously achieve high strength (due to the oriented crystallization of the PA66 phase) and high elastic recovery (due to the reversible deformation and effective stress transfer of the elastomer phase) under subsequent high stretching, explaining the origin of the performance of this high-strength and high-elasticity PA66 fiber at the molecular level.

[0045] Thermogravimetric analysis (TGA) diagram of the high-strength, high-elasticity PA66 fiber prepared in Example 2 is shown below. Figure 2 As shown in the figure, the thermogravimetric analysis (TGA) and differential thermogravimetric (DTG) curves further confirm the structural characteristics of the PA66 / elastomer blend fiber obtained in this embodiment from the perspectives of thermal stability and component interactions. As shown, the material remains highly stable before 300℃ (weight loss of approximately 2%), mainly due to the removal of moisture or low-molecular-weight volatiles. Its main decomposition stage is concentrated in the 300-500℃ range. The DTG curve shows a sharp and single main peak at approximately 420-440℃, indicating that the decomposition temperature regions of the two components in the blend system overlap. This is usually due to the strong interaction (such as hydrogen bonding) between the PA66 matrix and the elastomer phase, leading to mutual influence on thermal decomposition behavior rather than complete independence. The morphology of this single decomposition peak is also consistent with the good compatibility revealed by infrared spectroscopy. The final residual rate is approximately 3%, indicating that the material is mostly organic polymer with good thermal stability, meeting the temperature requirements for conventional processing and applications. Combined with infrared spectroscopy analysis, this thermal behavior data confirms from another dimension that the product is a PA66-based blend material with tight interfacial bonding and synergistic thermal stability, providing support for the stability of its macroscopic mechanical properties.

[0046] Examples 9-16 were prepared according to the raw material ratios and process parameters shown in Table 2 to obtain PA66 fibers.

[0047] Table 2. Proportions and parameters for Examples 9-16

[0048] Examples 17-24 show the preparation of PA66 fibers according to the raw material ratios and process parameters shown in Table 3.

[0049] Table 3. Formulation and parameter conditions for Examples 17-24

[0050] Effect Example 1: The PA66 fibers obtained in Examples 1-24 above were subjected to tensile testing, with the following specific steps: (1) Cut the sample to a standard size; (2) Clamping the sample, one end fixed, the other end applied tension; (3) Continuously apply tension, record the change of force and elongation; (4) When the sample is broken, record the maximum applied force and elongation.

[0051] The tensile test was performed on a universal material testing machine. Pneumatic or mechanical flat-jaw grips were used to ensure clamping without slipping, while avoiding premature breakage due to stress concentration at the clamping site. An extensometer is a critical sensor for accurately measuring tensile modulus and yield point. An extensometer must be used to accurately measure the true strain within the gauge length of the sample bar. The extensometer was installed on the parallel section of the sample bar. When the yield point was about to be reached, the extensometer was safely removed to prevent damage.

[0052] For modulus and yield strength measurements, the common speed is: Measurement modulus phase: use a lower speed, such as 1 mm / min, to obtain a smooth initial linear segment. Whole test: can be set to 5 mm / min.

[0053] The test software generates a stress-strain curve, from which the data is extracted: Calculation method of tensile modulus (Young's modulus, E): In the initial linear elastic segment of the stress-strain curve, select a segment (for example, strain from 0.05% to 0.25%). Calculate the ratio of the change in stress (Δσ) to the change in strain (Δε) in this interval: E = Δσ / Δε. The unit is usually MPa or GPa. After annealing, the crystallinity increases, and the molecular chain arrangement is more compact, so the tensile modulus usually increases significantly.

[0054] The determination method of yield strength (σ_y) (two commonly used): inflection point method: on the stress-strain curve, find out the stress value corresponding to the inflection point at which the elastic segment ends and the curve begins to deviate from the linearity. Offset yield method (more common, objective): draw a straight line from a certain point on the strain axis (usually 0.2%, i.e. strain is 0.002), which is parallel to the straight line part of the elastic segment. The stress value corresponding to the intersection of the straight line and the stress-strain curve is the "0.2% offset yield strength". Unit: MPa. Annealing eliminates internal stress and perfects the crystal structure, so that the material can withstand higher stress before yielding, and the yield strength will increase.

[0055] The PA66 fibers obtained in Examples 1-24 were subjected to the above performance tests, and the results are shown in Table 4: Table 4 Breaking strength, elongation at break and elastic recovery rate of Examples 1-24

[0056] From the results shown in Table 4, it can be seen that: (1) When the relative viscosity of PA66 increases (from 2.5→3.1→4.1), the breaking strength shows an upward trend (such as Examples 1→9→17, the strength increases from 8.2→8.4→8.8), which shows that PA66 with higher relative viscosity helps to improve the strength of the fiber; (2) When the amount of elastomer increases (from 50g→200g), the elongation at break increases significantly (such as Examples 1→4, the elongation increases from 35→50), but the strength decreases slightly, which reflects the strengthening effect of elastomer on the toughness of the fiber; (3) Optimal ratio determination: PA66: elastomer = 8:2 is the optimal ratio of comprehensive performance. The examples using this ratio (such as Examples 2, 6, 10, 14, 18, 22) all show a perfect balance between strength and elasticity - for example, Example 2 (8:2 ratio, 270℃ process) has a breaking strength of 7.9cN / dtex, an elongation at break of 40%, and an elastic recovery rate of 91%; Example 6 (8:2 ratio, 280℃ process) has a breaking strength of 8.3cN / dtex and an elastic recovery rate of 93%, which not only retains high mechanical strength, but also has excellent elasticity and toughness, far superior to other ratios (such as 9:1 ratio with low elongation, 7:3 and below with significantly reduced strength).

[0057] The high-strength and high-elasticity PA66 fibers obtained by the present application are packaged and stored, and the packaging requires vacuum sealing with moisture-proof tin foil bags and storage in a cool and dry space.

[0058] In order to permanently maintain the high performance of the fiber, the qualified fiber product is subjected to protective packaging. The aluminum-plastic composite bag with high barrier property (water vapor transmission rate <0.5 g / m2·day, oxygen transmission rate <1 cm3 / m2·day) is used for vacuum sealing packaging, the vacuum degree is controlled below-0.09 MPa, and a drying agent and an oxygen indicator card are placed in the bag. The sealed product is stored in a special warehouse in a cool (≤25℃), dry (relative humidity ≤60%) and light-proof manner, and the "first in, first out" principle is strictly implemented for stacking. This step builds a stable microenvironment isolated from water, oxygen and light, effectively prevents the moisture absorption and plasticization of the PA66 component and the thermal oxidation aging of the polymer, and ensures the stability of the tensile strength and elastic recovery rate of the fiber during the shelf life, which is the final guarantee for realizing the terminal application value of the high-strength and high-elasticity fiber preparation process.

[0059] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement methods and shall be within the protection scope of the present application.

Claims

1. A method for preparing high-strength, high-elasticity PA66 fiber, characterized in that... Follow these steps: S1. PA66 and elastomer are selected as raw materials, and the raw materials are pretreated separately, specifically by drying at 85°C in an oven for 4 hours; the elastomer is nylon 6 / spandex elastomer. S2. Place the PA66 and elastomer pretreated in step S1 into a mixer at a mass ratio of 9:1, 8:2, 7:3 or 6:4 and mix for 5 minutes. S3. The mixed raw materials are put into a single screw melt spinning machine, and the heating temperature is controlled at 270-280℃ to melt and extrude them to obtain filaments. The filaments are solidified into fibers through a cooling water tank. The obtained fibers are stretched, and then the stretched fibers are wound through a winding machine to make a roll-shaped fiber product. S4. Place the fiber product obtained in step S3 into an oven and dry it at 85°C. After drying, heat the fiber product in the oven to 150°C at a rate of <3°C / min and keep it at that temperature for 20 minutes for annealing. Then, reduce the temperature in the oven to below 40-50°C at a rate of 2-3°C / min and remove the product to obtain high-strength and high-elasticity PA66 fiber.

2. The method for preparing high-strength, high-elasticity PA66 fiber according to claim 1, characterized in that: The drying process described in step S1 involves drying the raw material to a moisture content of less than 0.02 wt%.

3. The method for preparing high-strength, high-elasticity PA66 fiber according to claim 1, characterized in that: The PA66 mentioned in step S1 is nylon 66 with a relative viscosity of 2.5, 3.1 or 4.

1.

4. The method for preparing high-strength, high-elasticity PA66 fiber according to claim 1, characterized in that: The mixer mentioned in step S2 is a high-speed vortex mixer; the mixing process is carried out at a speed of 1200 rpm under the conditions of room temperature and relative humidity less than 50%.

5. The method for preparing high-strength, high-elasticity PA66 fiber according to claim 1, characterized in that: The mass ratio of the pretreated PA66 to the elastomer in step S2 is 8:

2.

6. The method for preparing high-strength, high-elasticity PA66 fiber according to claim 1, characterized in that: In step S3, the screw length-to-diameter ratio of the single-screw melt spinning machine is ≥28:1, and the screw speed is set to a stable value of 10-20 rpm; the total stretching ratio of the stretching is set to 3.0-5.0 times.

7. A high-strength, high-elasticity PA66 fiber prepared by the preparation method according to any one of claims 1-6, characterized in that: The high-strength, high-elasticity PA66 fiber has a strength of 6.0-8.8 cN / dtex, an elongation at break of 30%-50%, and an elastic recovery rate of more than 90%.

8. The high-strength, high-elasticity PA66 fiber according to claim 7, characterized in that: The high-strength, high-elasticity PA66 fiber is vacuum-sealed in a high-barrier aluminum-plastic composite bag with a water vapor permeability of <0.5g / m²·day and an oxygen permeability of <1cm³ / m²·day. The vacuum degree is controlled below -0.09MPa. A desiccant and an oxygen indicator card are placed inside the bag. The sealed product is stored in a cool, dry, and light-proof special warehouse with a temperature of ≤25℃ and a relative humidity of ≤60%.

9. The application of the high-strength and high-elasticity PA66 fiber according to claim 7 in high-end safety protection and military and police equipment, high-performance sports and outdoor products, industrial and special materials, high-end textiles and medical rehabilitation, precision devices and composite materials.

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