Preparation method of chinlon-imitated high-strength high-elongation polyester industrial yarn

Abstract

The invention discloses a preparation method of a chinlon-imitated high-strength high-elongation polyester industrial yarn, and relates to the field of polyester industrial yarn preparation. The method comprises the following components: S1, a raw material drying treatment step, S2, a spinning and nascent filament preparation step, S3, a pre-drafting and curing step, S4, a drafting and heating treatment step, S5, a heat setting temperature adjustment step, S6, a network treatment step, S7, a post-treatment step and S8, a hydrophobic modification treatment step. Through the specific steps of pre-drafting treatment, two-time low-temperature setting and drafting heating treatment, the strength and the elongation of the polyester industrial yarn are effectively improved, in the pre-drafting treatment, the draft multiple, the draft speed and the draft temperature are accurately controlled, macromolecular chain segments of primary polyester yarn are preliminarily oriented, conditions are created for obtaining higher strength and elongation subsequently, and the production cost is reduced. The temperature and time are accurately controlled step by step in the two times of low-temperature setting, so that macromolecular chain segments in the fibers are further arranged in order, and a stable crystal structure is formed.

Description

Technical Field

[0001] The invention relates to the technical field of polyester industrial yarn preparation, in particular to a method for preparing nylon-imitation high-strength and high-elongation polyester industrial yarn. Background Art

[0002] As an important synthetic fiber material, polyester industrial yarn is widely used in textiles, industrial cord fabrics, safety belts, conveyor belts and other fields. With the continuous advancement of industrial technology and the increasing diversification of market demand, the performance requirements for polyester industrial yarn are also getting higher and higher.

[0003] Traditional polyester industrial yarn preparation methods have many limitations in improving fiber strength and elongation. First, traditional spinning and drawing processes make it difficult to accurately control the orientation and crystal structure of the macromolecular chain segments inside the fiber, resulting in limited improvement in the mechanical properties of the fiber. Secondly, although a single high-temperature shaping process can stabilize the fiber structure, it is often difficult to take into account both the strength and elongation of the fiber, and it is easy to generate large internal stress inside the fiber, affecting its dimensional stability and long-term performance. In addition, polyester industrial yarn prepared by traditional methods also has deficiencies in hydrophobicity and processing performance, making it difficult to meet the comprehensive performance requirements of fibers in specific application fields.

[0004] In view of the shortcomings of the traditional polyester industrial yarn preparation method, the present invention proposes a method for preparing nylon-like high-strength and high-elongation polyester industrial yarn, which is particularly important. Summary of the Invention

[0005] The purpose of the present invention is to make up for the shortcomings of the existing technology and provide a preparation method of nylon-like high-strength and high-elongation polyester industrial yarn. It can effectively improve the strength and elongation of the polyester industrial yarn through specific pre-stretching treatment, two low-temperature setting and stretching heating treatment steps, while optimizing the crystal structure and internal stress distribution of the fiber. In addition, by introducing hydrophobic modification treatment and network treatment procedures, the hydrophobicity and processing performance of the polyester industrial yarn are further enhanced, making it more in line with the performance requirements of nylon-like high strength and high elongation.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for preparing nylon-like high-strength and high-elongation polyester industrial yarn, the specific steps of the method are: S1, raw material drying step: select conventional polyester chips as raw materials and place them in a drying equipment for drying; S2, spinning and spun yarn preparation step: the dried polyester chips are put into a spinning machine, melt extruded, spun through a spinneret, and cooled to form spun polyester yarn; S3, pre-stretching and curing step: pre-stretching the spun polyester filaments and then curing them; S4, drawing and heating step: between the second and third heated rollers of the production equipment, ordinary compressed air is replaced with compressed steam at a temperature of about 120°C and a pressure of 0.2 MPa, and the pre-drawn and cured polyester yarn is placed in the compressed steam environment for heating; S5, heat setting temperature adjustment step: change the original one-time high temperature setting for ordinary varieties to two-time low temperature setting; S6, network processing step: add a network processing step at a specific location to control the temperature and pressure of the pre-network steam; S7, post-processing step: oiling and winding the polyester industrial yarn after the above treatment; S8, hydrophobic modification treatment step: immersing the polyester industrial yarn in a solution containing a fluorocarbon hydrophobic agent for treatment, and then washing and drying.

[0007] Furthermore, in the raw material drying step, the drying equipment adopts a vacuum drum dryer, and the drying is carried out for 6-8 hours at a temperature of 160-180°C and a vacuum degree of -0.08-0.09MPa. The vacuum drum dryer has the characteristics of high drying efficiency and uniform heating of the material. Under the conditions of temperature and vacuum, it can effectively remove moisture from the polyester chips, avoid bubbles, broken ends, and rough surface problems in the subsequent spinning process due to residual moisture, ensure the quality of the nascent polyester yarn, and lay the foundation for the subsequent preparation of high-performance polyester industrial yarn. In addition, by precisely controlling the drying time, the moisture content of the polyester chips can be stabilized within an appropriate range, preventing excessive drying from causing a decrease in chip performance, and ensuring the stability of the entire production process and the consistency of product quality.

[0008] Furthermore, during the pre-stretching treatment, the stretching ratio is controlled at 2.8-3.2 times, the stretching speed is 80-100 m / min, and the stretching temperature is maintained at 80-90°C. The appropriate stretching ratio can enable the macromolecular chain segments of the nascent polyester yarn to be initially oriented, creating conditions for subsequent acquisition of higher strength and elongation. The precise control of the stretching speed and temperature can ensure the smooth progress of the stretching process, avoiding fiber breakage or uneven internal structure due to excessive speed or inappropriate temperature. When the stretching speed is 80-100 m / min, the fiber can complete the stretching deformation within an appropriate time, and the stretching temperature of 80-90°C can make the fiber in a highly elastic state, reduce the movement resistance of the macromolecular chain segments, promote the orientation and crystallization of the molecular chains, and thus improve the physical properties of the fiber.

[0009] Furthermore, in the two low-temperature setting processes, the first low-temperature setting temperature is 145-155°C, the setting time is 25-35 seconds, and the second low-temperature setting temperature is 135-145°C, and the setting time is 20-30 seconds. Compared with the single high-temperature setting process, this step-by-step low-temperature setting method can more accurately control the crystallinity and orientation of the polyester industrial yarn. The first low-temperature setting process is mainly to stabilize and adjust the structure of the fiber after drawing. At a temperature of 145-155°C, the macromolecular chain segments inside the fiber are further regularly arranged to form a certain crystalline structure. The second low-temperature setting process is based on the first setting process, further refining the crystalline structure, reducing the internal stress inside the fiber, and improving the dimensional stability and mechanical properties of the fiber. By reasonably adjusting the temperature and time of the two setting processes, the elongation at break of the polyester industrial yarn can be accurately controlled according to the needs of different varieties, making it closer to the performance characteristics of nylon.

[0010] Furthermore, in the network processing process, a specific position is set between the third hot roller and the fourth hot roller, the pre-network steam temperature is 105-115°C, and the pressure is 0.12-0.18MPa. The network processing position is set between the third hot roller and the fourth hot roller, which can effectively perform network processing on the fibers after they have undergone a certain degree of stretching and preliminary shaping, so that good cohesion and bundling are formed between the fibers. The temperature and pressure of the pre-network steam have a key influence on the network effect. At a temperature of 105-115°C and a pressure of 0.12-0.18MPa, the steam can evenly penetrate into the fiber bundle, causing the fibers to entangle and interweave with each other to form a stable network structure. This network structure can not only improve the processing performance of polyester industrial yarn and reduce the breakage phenomenon during the weaving process, but also further improve its physical properties, increase the wear resistance and tear strength of the fibers, and make it more in line with the high strength and high elongation performance requirements of imitation nylon.

[0011] Furthermore, in the hydrophobic modification step, a cross-linking agent with a mass fraction of 0.5-1.5% is added to the fluorocarbon hydrophobic agent solution, and the cross-linking agent is an aziridine cross-linking agent. Adding the cross-linking agent to the hydrophobic agent solution can cause a cross-linking reaction between the hydrophobic agent molecules and the macromolecular chains on the surface of the polyester fiber to form a more stable hydrophobic membrane structure. The aziridine cross-linking agent has good reactivity and can react with functional groups such as hydroxyl groups on the surface of the polyester fiber to form a three-dimensional network structure on the fiber surface, thereby enhancing the bonding force between the hydrophobic membrane and the fiber. When the mass fraction of the cross-linking agent is 0.5-1.5%, it can ensure that the cross-linking reaction is fully carried out to form a stable hydrophobic film, and the fiber will not become hard and brittle due to excessive cross-linking, affecting its flexibility and mechanical properties. By adding a cross-linking agent, the hydrophobic durability of the polyester industrial yarn can be significantly improved, so that it can maintain good non-water absorption properties even if it is affected by external factors such as friction and washing during long-term use.

[0012] Furthermore, the oiling treatment in the post-treatment step adopts an emulsion-type oil agent, the concentration of the oil agent is 8-12 g / L, and the oiling rate is controlled at 0.8-1.2%. The emulsion-type oil agent has good dispersibility and wettability, and can be evenly attached to the surface of the polyester industrial yarn. At a concentration of 8-12 g / L, the oil agent can form an oil film of appropriate thickness on the fiber surface, effectively improving the smoothness, bundling and antistatic properties of the fiber. The appropriate oiling rate can ensure that the fiber has good processing performance in the subsequent processing process and reduce the damage to the fiber caused by friction and static electricity, and will not cause the fiber surface to be greasy due to excessive oiling, affecting the product quality and appearance. At the same time, the oil agent formula also has good heat resistance and chemical stability, and is compatible with subsequent processes such as hydrophobic modification treatment, and will not have a negative impact on other properties of the polyester industrial yarn.

[0013] Furthermore, in the drawing and heating treatment step, the humidity of the compressed air steam is controlled at 85-95% RH. The humidity of the compressed air steam has an important influence on the heating effect and performance improvement of the polyester yarn. When the humidity is controlled at 85-95% RH, the steam can transfer heat more evenly, so that the polyester yarn is heated more evenly in the process of entering the high elastic state, avoiding uneven fiber performance due to local overheating or overcooling. The high-humidity steam forms a water film on the fiber surface, which helps the movement of the macromolecular chain segments and further inhibits the rapid crystallization of the macromolecular chain segments during the hot roller drawing process, thereby more effectively improving the elongation performance of the polyester industrial yarn. In addition, the appropriate steam humidity can also reduce the static electricity generated by the fiber during high-temperature treatment, ensuring the smooth progress of the production process.

[0014] Furthermore, in the spinning process, the spinneret hole diameter is 0.15-0.25 mm, and the spinneret hole aspect ratio is 3-5. The spinneret hole parameters of the spinneret directly affect the morphology and structure of the nascent polyester yarn. The spinneret hole diameter of 0.15-0.25 mm can control the single fiber fineness of the fiber, so that the produced polyester yarn has a linear density and meets the performance requirements of high strength and high elongation. The aspect ratio of 3-5 is conducive to the flow and molding of the melt in the spinneret hole, so that the fiber can better form a uniform cross-sectional shape during the extrusion process, reducing defects and stress concentration inside the fiber. A reasonable combination of spinneret hole diameter and aspect ratio can improve the quality of the nascent polyester yarn, provide a good foundation for subsequent drawing and shaping processes, and ultimately help to prepare nylon-like high-strength and high-elongation polyester industrial yarn with excellent performance.

[0015] Compared with the existing technology, the preparation method of nylon-like high-strength and high-elongation polyester industrial yarn has the following beneficial effects: 1. The present invention effectively improves the strength and elongation of polyester industrial yarn through specific pre-stretching treatment, two low-temperature setting and stretching heating treatment steps. During the pre-stretching treatment, the stretching multiple, speed and temperature are precisely controlled to initially orient the macromolecular segments of the nascent polyester yarn, creating conditions for subsequent acquisition of higher strength and elongation. The two low-temperature setting processes precisely control the temperature and time in steps to further regularly arrange the macromolecular segments inside the fiber, forming a stable crystalline structure, refining the crystalline structure and reducing the internal stress inside the fiber, thereby significantly improving the dimensional stability and mechanical properties of the polyester industrial yarn.

[0016] 2. The present invention adds a hydrophobic modification treatment step in the preparation process, and forms a more stable hydrophobic membrane structure by immersing the polyester industrial yarn in a solution containing a fluorocarbon hydrophobic agent and an aziridine cross-linking agent. The addition of the cross-linking agent enhances the bonding force between the hydrophobic membrane and the fiber, significantly improves the hydrophobic durability of the polyester industrial yarn, and enables it to maintain good non-water absorption performance during long-term use. In addition, the introduction of the network treatment process effectively improves the cohesion and bundling of the polyester industrial yarn, reduces the breakage phenomenon during the weaving process, and further improves its processing performance, making it more in line with the performance requirements of high strength and high elongation of imitation nylon.

[0017] Other advantages, objects and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be learned from the practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0019] Figure 1 This is a process diagram of a method for preparing nylon-like high-strength and high-elongation polyester industrial yarn; Figure 2 The present invention is a detailed flow chart of a method for preparing a nylon-like high-strength and high-elongation polyester industrial yarn. DETAILED DESCRIPTION

[0020] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0021] Example 1 The reason for using a vacuum drum dryer is: the boiling point of water is lowered through a vacuum environment, and efficient dehydration is achieved at a low temperature of 170°C, avoiding high-temperature oxidation and degradation of polyester chips. At the same time, the drum structure allows the chips to be heated evenly, and the moisture content after drying can be stably controlled at 0.005%-0.008%.

[0022] Equipment parameter linkage: The vacuum degree of -0.085MPa and the temperature of 170℃ work synergistically to increase the moisture diffusion rate inside the slices by 30%, and shorten the drying time by 50% compared with normal pressure drying.

[0023] Spinneret design: A combination of 0.20 mm diameter spinneret holes and aspect ratio 4 is selected. The melt stays in the spinneret holes for about 0.8 seconds, and the shear rate is controlled at 5×10 3 s -1 , avoid melt fracture caused by high shear, and ensure that the diameter deviation of the primary silk is ≤±1.5%.

[0024] Cooling system: A side-blowing cooling air device is used with a wind speed of 0.8m / s, a wind temperature of 20℃±2℃, and a relative humidity of 65%±5%, so that the cooling rate of the spun silk reaches 150℃ / s, forming a fine and uniform initial crystal structure.

[0025] Pre-drawing machine: equipped with hot oil circulating heating rollers, the temperature control accuracy is ±1°C. When the drafting ratio is 3.0 times, the fiber orientation (birefringence value) is increased from 0.015 to 0.032, laying the foundation for subsequent steam treatment.

[0026] Compressed air steam device: uses a saturated steam generator, and the steam humidity is controlled at 90% RH through a steam-water separator. A hot and humid environment of 120°C and 0.2MPa is formed between the second and third hot rollers, which keeps the fiber in a highly elastic state (above the glass transition temperature), improves the mobility of macromolecular segments, and avoids internal defects caused by sudden cooling and crystallization during stretching.

[0027] The target breaking strength is 850 cN / dtex (compared to approximately 700 cN / dtex for ordinary polyester industrial yarn). Through three draft ratio optimizations (pre-drafting 3.0x + hot roller drafting 1.8x + steam drafting 1.2x), the fiber crystallinity is increased from 35% to 42%, while retaining an elongation at break of 28% (compared to approximately 25% for nylon webbing).

[0028] Test method: Use a constant-speed tensile testing machine with a clamping length of 200 mm and a tensile speed of 100 mm / min. Test 20 specimens in each group, and the coefficient of variation is ≤5%.

[0029] Oil formulation optimization: The emulsion oil contains 50% mineral oil + 30% fatty acid ester + 20% antistatic agent. At a concentration of 10g / L, the fiber surface friction coefficient is reduced to 0.25-0.30 (dry state), and the bending stiffness is ≤5cN·cm / cm, meeting the "soft but not collapsing" feel requirement of luggage webbing.

[0030] Monitoring the cross-linking degree of the hydrophobic membrane: The absorption peak intensity of the -CF2- group on the fiber surface is detected by infrared spectroscopy to ensure that the grafting rate of the cross-linking agent (aziridine) reaches more than 85%. At the same time, the fiber hardness is tested by a Shore hardness tester and controlled at 20-25HA to avoid stiffness caused by excessive cross-linking.

[0031] Bending resistance: Simulating the repeated bending conditions of luggage handles, the product was subjected to 100,000 bending tests, and the breaking strength retention rate was ≥95%, which is better than that of ordinary polyester webbing (about 85%).

[0032] Color stability: 0.5% light-fast dye is compounded in the hydrophobic agent treatment bath. After 100 hours of xenon lamp aging test, the color fastness reaches level 4-5 (ISO105-B02 standard), which is suitable for long-term outdoor display needs of luggage.

[0033] Example 2 Spinneret hole miniaturization: Using a 0.15mm diameter spinneret + aspect ratio of 5, combined with a melt filter (precision 5μm), impurities ≥5μm are filtered out to avoid spinning breakage. The specific surface area of ​​fine denier fiber (single yarn fineness 1.2dtex) is 60% higher than that of conventional fiber (3dtex), which doubles the number of fibers per unit area of ​​the airbag fabric, and simultaneously optimizes breathability and flexibility.

[0034] High-speed spinning equipment: spinning speed 4000m / min, using heat tube spinning technology, the melt cooling rate at the spinneret outlet reaches 200℃ / s, forming a primary silk with an amorphous structure accounting for ≥70%, providing conditions for subsequent high-multiple drawing.

[0035] Pre-stretching equipment: A dual-zone stretching machine is used, with the first zone (normal temperature) stretching at 1.5 times and the second zone (90°C) stretching at 1.7 times, for a total stretching ratio of 3.2 times. This avoids micro-cracks in the fiber caused by high stretching in a single zone. During the stretching process, a laser diameter gauge is used to monitor the changes in the wire diameter in real time.

[0036] Steam humidity control: The humidity of compressed air steam is precisely controlled at 95% RH by an ultrasonic humidifier. The high humidity environment forms a 1-2μm thick water film on the fiber surface, reducing frictional heat during drawing (by about 30%), inhibiting the rapid crystallization of macromolecular segments at 120°C, and allowing the fiber to retain 35% of its elongation at break (about 20% for ordinary polyester yarn).

[0037] The first high-temperature setting (155°C): Using a relaxation heat setting machine, the fiber is treated in a tension-free state for 25 seconds to eliminate the internal stress of drafting, and the crystallinity is increased from 28% to 35%, while maintaining a shrinkage rate of 2.5% (the airbag fabric requires ≤3%).

[0038] Second low-temperature setting (135°C): Using a tension heat setting machine, a tension of 0.05 cN / dtex is applied to reduce the grain size from 50 nm to below 30 nm, thereby improving the impact resistance of the fiber (impact strength increased by 20%).

[0039] Air permeability: Tested with YG461E air permeability tester, under standard conditions (pressure difference 100Pa), the air permeability must be ≥2200L / (m 2 ·s), which is achieved by controlling the network node spacing (8-10mm) and the cohesion between fibers (friction coefficient 0.20-0.22).

[0040] Burst strength: Simulating the airbag inflation process, under 100kPa air pressure impact, the tow elongation at break must be ≥32%. The fiber storage modulus under high-frequency vibration (50Hz) is tested using a dynamic mechanical analyzer (DMA) (target value ≤1.5GPa) to ensure that the fiber can deform evenly during rapid inflation.

[0041] Cross-linking agent residue control: Use gas chromatography-mass spectrometry (GC-MS) to detect the residual amount of aziridine on the fiber surface, which must be ≤0.1ppm to avoid high-temperature decomposition and the production of harmful substances.

[0042] Flame retardant performance: Adding 0.3% phosphorus flame retardant to the oil can make the fiber oxygen index reach 28% (GB / T2406.2 standard), meeting the flame retardant requirements of automotive interior materials.

[0043] Environmental tolerance: After 100 cycles of high and low temperature cycling tests from -30°C to 80°C, the fiber breaking strength retention rate is ≥98%, adapting to the needs of automobiles in different climate zones.

[0044] Batch stability: An online quality monitoring system has been established, using a near-infrared spectrometer to monitor the spinning melt viscosity (fluctuation ≤ ±2%) and drafting tension (fluctuation ≤ ±5 cN) in real time. This ensures that the standard deviation of the breaking strength of each batch of yarns is ≤15 cN / dtex, meeting the consistency requirements of large-scale production of automotive parts.

[0045] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing nylon-like high-strength and high-elongation polyester industrial yarn, characterized in that: The specific steps of this method are: S1, raw material drying step: select polyester chips as raw materials and place them in a drying equipment for drying; S2, spinning and spun yarn preparation step: the dried polyester chips are put into a spinning machine, melt extruded, spun through a spinneret, and cooled to form spun polyester yarn; S3, pre-stretching and curing step: pre-stretching the spun polyester filaments and then curing them; S4, drawing and heating step: between the second and third heated rollers of the production equipment, ordinary compressed air is replaced with compressed steam at a temperature of about 120°C and a pressure of 0.2 MPa, and the pre-drawn and cured polyester yarn is placed in the compressed steam environment for heating; S5, heat setting temperature adjustment step: change the original one-time high temperature setting for ordinary varieties to two-time low temperature setting; S6, network processing step: add a network processing step at a specific location to control the temperature and pressure of the pre-network steam; S7, post-processing step: oiling and winding the polyester industrial yarn after the above treatment; S8, hydrophobic modification treatment step: immersing the polyester industrial yarn in a solution containing a fluorocarbon hydrophobic agent for treatment, and then washing and drying.

2. The method for preparing a nylon-like high-strength and high-elongation polyester industrial yarn according to claim 1, characterized in that: In the raw material drying step, the drying equipment adopts a vacuum drum dryer, and the drying is carried out for 6-8 hours at a temperature of 160-180° C. and a vacuum degree of -0.08-0.09 MPa.

3. The method for preparing a nylon-like high-strength and high-elongation polyester industrial yarn according to claim 1, characterized in that: During the pre-stretching process, the stretching ratio is controlled at 2.8-3.2 times, the stretching speed is 80-100 m / min, and the stretching temperature is maintained at 80-90°C. Precise control of the stretching speed and temperature can ensure the smooth progress of the stretching process, avoiding fiber breakage or uneven internal structure due to excessive speed or inappropriate temperature. When the stretching speed is 80-100 m / min, the fiber can complete the stretching deformation within an appropriate time, and the stretching temperature of 80-90°C can make the fiber in a highly elastic state, reduce the movement resistance of the macromolecular chain segments, and promote the orientation and crystallization of the molecular chains.

4. The method for preparing a nylon-like high-strength and high-elongation polyester industrial yarn according to claim 1, characterized in that: In the two low-temperature setting processes, the first low-temperature setting temperature is 145-155°C, the setting time is 25-35 seconds, and the second low-temperature setting temperature is 135-145°C, the setting time is 20-30 seconds. The first low-temperature setting is mainly to stabilize and adjust the structure of the fiber after stretching. At a temperature of 145-155°C, the macromolecular chain segments inside the fiber are further regularly arranged to form a certain crystalline structure. The second low-temperature setting is based on the first setting to further refine the crystalline structure and reduce the internal stress inside the fiber.

5. The method for preparing a nylon-like high-strength and high-elongation polyester industrial yarn according to claim 1, characterized in that: In the network processing process, a specific position is set between the third hot roller and the fourth hot roller, the pre-network steam temperature is 105-115°C, and the pressure is 0.12-0.18MPa. The network processing position is set between the third hot roller and the fourth hot roller, so that the fiber can be effectively network processed after it has undergone a certain degree of stretching and preliminary shaping. The temperature and pressure of the pre-network steam have a key influence on the network effect. At a temperature of 105-115°C and a pressure of 0.12-0.18MPa, the steam can evenly penetrate into the fiber bundle, causing the fibers to entangle and interweave with each other, forming a stable network structure.

6. The method for preparing a nylon-like high-strength and high-elongation polyester industrial yarn according to claim 1, characterized in that: In the hydrophobic modification treatment step, a cross-linking agent with a mass fraction of 0.5-1.5% is also added to the fluorocarbon hydrophobic agent solution. The cross-linking agent is an aziridine cross-linking agent. Adding the cross-linking agent to the hydrophobic agent solution can cause a cross-linking reaction between the hydrophobic agent molecules and the macromolecular chains on the surface of the polyester fiber to form a more stable hydrophobic membrane structure. The aziridine cross-linking agent has good reactivity and can react with functional groups such as hydroxyl groups on the surface of the polyester fiber to form a three-dimensional network structure on the fiber surface, thereby enhancing the bonding force between the hydrophobic membrane and the fiber. When the mass fraction of the cross-linking agent is 0.5-1.5%, it can ensure that the cross-linking reaction is fully carried out to form a stable hydrophobic membrane, and the fiber will not become hard or brittle due to excessive cross-linking, thereby affecting its flexibility and mechanical properties.

7. The method for preparing a nylon-like high-strength and high-elongation polyester industrial yarn according to claim 1, characterized in that: The oiling treatment in the post-treatment step adopts an emulsion-type oil agent with a concentration of 8-12 g / L and an oiling rate controlled at 0.8-1.2%. The emulsion-type oil agent has good dispersibility and wettability. At a concentration of 8-12 g / L, the oil agent can form an oil film of appropriate thickness on the fiber surface. At the same time, the oil agent formula also has good heat resistance and chemical stability.

8. The method for preparing a nylon-like high-strength and high-elongation polyester industrial yarn according to claim 1, characterized in that: During the stretching and heating treatment step, the humidity of the compressed air steam is controlled at 85-95% RH. The high-humidity steam forms a water film on the fiber surface, further inhibiting the rapid crystallization of the macromolecular chain segments during the hot roller stretching process.

9. The method for preparing a nylon-like high-strength and high-elongation polyester industrial yarn according to claim 1, characterized in that: During the spinning process, the spinneret hole diameter is 0.15-0.25 mm, and the spinneret hole aspect ratio is 3-5. The spinneret hole parameters of the spinneret directly affect the morphology and structure of the spun polyester yarn. The spinneret hole diameter of 0.15-0.25 mm can control the single fiber fineness of the fiber, while the aspect ratio of 3-5 is conducive to the flow and formation of the melt in the spinneret hole.

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