High-strength low-elongation industrial polyester yarn and preparation method thereof

Abstract

This invention discloses a high-strength, low-elongation industrial polyester filament and its preparation method, belonging to the technical field of polyester filament materials. It addresses the technical problem that the mechanical strength, elongation at break, thermal stability, and acid and alkali resistance of existing industrial polyester filaments need further improvement. Specifically, it comprises the following components by weight: 100 parts amide-reinforced PET, 5-7 parts reactive PCDI, 1-1.5 parts epoxy-modified particles, and 3-5 parts auxiliary additives. This invention uses ester-terminated polyamide to reinforce the rigidity of the PET chain segments, reactive PCDI to extend the chain, increase viscosity, reduce carboxyl end-group content, and improve hydrolytic stability, and epoxy-modified particles to promote crystallization and stabilize the orientation structure. This results in a polyester filament with high breaking strength, low elongation at break, low dry heat shrinkage, and good acid and alkali corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of polyester filament material technology, specifically to a high-strength, low-elongation industrial polyester filament and its preparation method. Background Technology

[0002] Polyester industrial yarn typically refers to high-performance filaments made primarily from polyethylene terephthalate (PET). Due to its high mechanical strength, good fatigue resistance, abrasion resistance, and dimensional stability, it has been widely used in industrial fields such as conveyor belts, tire cords, geotextiles, cables, tarpaulins, and flexible composite material skeletons.

[0003] Currently, to improve the overall performance of polyester industrial yarn, modifications are typically made by increasing the polyester molecular weight, optimizing the spinning and drawing process, introducing functional comonomers, adding inorganic nanoparticles, or using chain extenders. While increasing the polyester molecular weight helps improve strength, it often increases melt viscosity, affecting spinning stability. In addition, simply increasing the draw ratio can improve orientation, but it can also easily increase the internal stress of the yarn, thus affecting subsequent thermal stability. While introducing inorganic particles can improve modulus and thermal dimensional stability to some extent, if the particles are unevenly dispersed or the interfacial bonding is poor, agglomeration and structural defects are likely to occur, which is not conducive to improving mechanical properties. Meanwhile, industrial polyester filaments are often exposed to certain temperatures, humidity, or acid and alkali environments during actual use. Ordinary industrial polyester filaments still have shortcomings in terms of chemical corrosion resistance, hydrolysis resistance, and thermal dimensional stability. The ester bonds in the polyester molecular chain of industrial polyester filaments are prone to degradation, leading to a decrease in fiber strength retention and deterioration in elongation properties, which in turn affects the service life of the product.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength, low-elongation industrial polyester filament and its preparation method, which solves the technical problem that the mechanical strength, elongation at break, thermal stability and acid and alkali resistance of industrial polyester filament in the prior art need to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: a high-strength, low-elongation industrial polyester filament, comprising the following components by weight: 100 parts of amide-reinforced PET, 5-7 parts of reactive PCDI, 1-1.5 parts of epoxy-modified particles, and 3-5 parts of auxiliary additives; The preparation method of amide-reinforced PET is as follows: Under the protection of an inert gas atmosphere, dimethyl terephthalate, ethylene glycol, 3-amino-1,5-pentanediol and transesterification catalyst are mixed and stirred. The reaction system is heated to 180-200℃ and kept at this temperature until the methanol removal reaches 90% of the theoretical amount. Ester-terminated polyamide and antimony trioxide are added to the reaction system. The reaction system is then subjected to a negative pressure of -0.1MPa. The reaction system is heated to 240-250℃ and kept at this temperature for condensation for 2-3 hours. The product is discharged while hot to obtain amide-reinforced PET. The reactive PCDI is obtained by catalytic decarboxylation condensation of tetramethyl diphenyl diisocyanate and 1,5-diisocyanopentane, followed by chain termination using 2-(ethylene oxide-2-yl)ethanol-1-ol as a capping agent.

[0007] Furthermore, the weight ratio of dimethyl terephthalate, ethylene glycol, 3-amino-1,5-pentanediol, transesterification catalyst, ester-terminated polyamide, and antimony trioxide is 310:75-85:30:0.12-0.15:70-80:0.1, and the transesterification catalyst is zinc acetate.

[0008] Furthermore, the preparation method of ester-terminated polyamide is as follows: under the protection of an inert gas atmosphere, dimethyl terephthalate and diphenyl terephthalate are mixed and stirred, the reaction system is heated to 215-225℃, a catalyst solution is added to the reaction system, the mixture is kept at the temperature and stirred for 20-25 min, the reaction system is cooled to 140-150℃, 1,4-butanediamine is added to the reaction system, the mixture is kept at the temperature for 4-6 h, and then post-treated to obtain ester-terminated polyamide.

[0009] Furthermore, the weight ratio of dimethyl terephthalate, diphenyl terephthalate, catalyst solution, and 1,4-butanediamine is 950-970:300-310:25-28:320-350. The catalyst solution is composed of 2-ethyl-1-hexanotoxide titanium and xylene at a ratio of 1 g:2 mL. The post-treatment includes: after the reaction is complete, discharging the material while it is hot, cooling it, pulverizing it, mixing it with xylene at a solid-liquid ratio of 1:7-8, heating the reaction system to reflux, maintaining the temperature for 3-5 hours, cooling the reaction system to room temperature, filtering it, washing the filter cake twice with xylene, drying it, transferring the filter cake to a drying oven at a temperature of 70-80℃, and drying it to constant weight to obtain ester-terminated polyamide.

[0010] Furthermore, the preparation method of epoxy modified particles is as follows: nano-silica, KH-560 and anhydrous ethanol are mixed and stirred, the reaction system is heated to 55-65℃, alkali solution is added to the reaction system, the reaction is kept at the temperature for 40-60 min, and then post-processed to obtain epoxy modified particles.

[0011] Furthermore, the ratio of nano-silica, KH-560, anhydrous ethanol, and alkaline solution is 7g:2-3g:50mL:5mL, and the alkaline solution is a 3-5mol / L sodium hydroxide aqueous solution. The post-treatment includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, dried, and the filter cake is transferred to a drying oven at a temperature of 60-70℃ and dried to constant weight to obtain epoxy modified particles.

[0012] Furthermore, the preparation method of reactive PCDI is as follows: under an inert gas atmosphere, tetramethyl diphenyl diisocyanate and 1,5-diisocyanopentane are mixed and stirred, the reaction system is heated to 180-200℃, a catalyst is added to the reaction system, the reaction is maintained at this temperature for 6-8 hours, the reaction system is cooled to 80-90℃, toluene and 2-(ethylene oxide-2-yl)ethanol-1-ol are added to the reaction system, the reaction is maintained at this temperature for 60-80 minutes, and after post-treatment, reactive PCDI is obtained.

[0013] Furthermore, the ratio of tetramethyl diphenyl diisocyanate, 1,5-diisocyanatopentane, catalyst, toluene, and 2-(ethylene oxide-2-yl)ethanol-1-ol is 10-12 g: 5-7 g: 0.05 g: 50 mL: 1-2 g, the catalyst is 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide, and the post-treatment includes: after the reaction is complete, the reaction system is evaporated to -0.1 MPa, and low-boiling substances are removed by vacuum distillation to obtain reactive PCDI.

[0014] This invention also proposes a method for preparing high-strength, low-elongation industrial polyester yarn, comprising the following steps: S1. Place amide-reinforced PET, reactive PCDI, epoxy-modified particles and auxiliary additives in a drying oven at a temperature of 95-105℃ and dry until the moisture content is reduced to less than 10ppm to obtain pretreated dried material. S2. Add the pretreated dried material to a twin-screw extruder, melt mix for 3-5 minutes, filter through a 40-mesh sieve, melt extrude into a melt spinning machine, spin through a spinneret and cool to obtain polyester filament crude product; S3. Coarse polyester filament is heat-stretched and shaped to obtain polyester filament.

[0015] Further, in step S1, the auxiliary additives are composed of a dispersant, a lubricant, a heat stabilizer, an antioxidant, and an antistatic agent in a weight ratio of 5:3:2:2:1. The dispersant is stearate, the lubricant is pentaerythritol tetrastearate, the heat stabilizer is an organotin stabilizer, the antioxidant is antioxidant 1010, and the antistatic agent is antistatic agent SN. In step S2, the temperatures of the five temperature zones of the twin-screw extruder from the feed end to the discharge end are 255℃, 260℃, 260℃, 265℃, and 265℃ respectively; the die temperature is 270℃; the melt spinning temperature is 288-298℃; and the spinneret orifice diameter is 0.2 mm. -0.3mm, length-to-diameter ratio 3:1, spinning speed 600-800m / min, spinning cooling by air cooling, air cooling temperature 20±2℃, humidity 80±5%, wind speed 0.7±0.10m / s; in step S3, the hot drawing and setting operation is as follows: the polyester filament is sequentially passed through the first hot roller at 85-95°C for drawing, the second hot roller at 130-150°C for drawing, the third hot roller at 230-250°C for hot setting, and the fourth hot roller at 200-220°C for stabilization, with the total drawing ratio set at 5.6-6.2 times, and wound at a speed of 3000-3400m / min to obtain polyester filament.

[0016] The present invention has the following beneficial effects: 1. This invention involves the co-participation of 3-amino-1,5-pentanediol and ester-terminated polyamide in polycondensation to form amide-reinforced PET containing amide segments, a slightly branched structure, and a continuous polyester phase. This significantly enhances the binding effect between molecular chains while maintaining the crystallization and stretchability of PET. The polyamide segments are introduced into the PET system in the form of chemical bonds, avoiding the incompatibility and interface defects caused by ordinary physical blending. The amide bonds and aromatic structures improve the rigidity of the chain segments and the interchain forces, while the ester groups at the ends continue to participate in the polyester polycondensation. The synergy between amide-reinforced PET and reactive PCDI increases the molecular weight, chain entanglement, and melt strength of the system. This makes it easier for the material to form a stable axial orientation structure during subsequent spinning and stretching, improving the breaking strength of polyester filaments while reducing the breaking elongation, resulting in outstanding high-strength, low-elongation industrial yarn performance advantages.

[0017] 2. This invention also utilizes the synergistic effect of reactive PCDI, epoxy-modified particles, and multi-stage hot stretching and setting processes. Reactive PCDI not only reduces the carboxyl end-group content in PET materials and mitigates high-temperature processing degradation during processing, but also improves melt stability through chain extension and slight branching, providing a good molecular weight basis for high-ratio stretching. The nano-silica in the epoxy-modified particles, after surface modification with a silane coupling agent, forms a stronger interfacial bond with the amide-reinforced PET matrix. Through interfacial reactions between surface epoxy groups and matrix active groups, it improves particle dispersion and stress transfer efficiency, while also playing a heterogeneous nucleation role, promoting crystallization, refining grains, and improving orientation structure stability. The fiber filaments after melt spinning undergo multi-stage hot roller stretching, high-temperature heat setting, and stabilization treatments, sequentially achieving molecular chain orientation, crystallization perfection, and residual stress release. This fixes the aforementioned molecular reinforcement and interfacial reinforcement effects into a stable condensed state structure, effectively reducing the fiber's dry heat shrinkage rate and improving the product's dimensional stability and reliability under high-temperature conditions.

[0018] 3. This invention also utilizes the synergistic effect of reactive PCDI, amide-reinforced PET, and epoxy-modified particles. The carbodiimide structure in reactive PCDI preferentially reacts with the carboxyl groups at the polyester chain ends, reducing the content of carboxyl end groups and inhibiting autocatalytic hydrolysis induced by carboxyl groups under acidic or humid conditions. Simultaneously, its chain-extending effect improves the continuity of the molecular chain, allowing the material to maintain a high load-bearing capacity even after media erosion. The reinforced main chain structure formed by amide-reinforced PET, along with its high orientation and high crystallinity, reduces the penetration rate of acidic and alkaline media into the fiber interior, mitigating the preferential damage to amorphous and weak regions. The epoxy-modified particles further enhance the interfacial bonding strength and internal structural density, helping to reduce localized damage caused by the diffusion of media along interfacial defects and improving the retention rate of mechanical properties in acidic and alkaline media. This results in superior chemical corrosion resistance, enabling the resulting fiber to maintain its original mechanical properties well in acidic media, and while some surface erosion may occur in alkaline media, the overall load-bearing skeleton still maintains high stability. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] In this invention, the nano-silica particles have a diameter of 10-20 nm and an effective component content of 99%. In this invention, KH-560 is 3-glycidyl etheroxypropyltrimethoxysilane, CAS number 2530-83-8.

[0021] Example 1 This embodiment provides a method for preparing high-strength, low-elongation industrial polyester yarn, including the following steps: Step S1: Preparation of ester-terminated polyamide 2-Ethyl-1-hexanotoxide titanium and xylene were mixed evenly at a ratio of 1 g: 2 mL to obtain a catalyst solution; Weigh out 950g of dimethyl terephthalate and 300g of diphenyl terephthalate and add them to a reaction flask under nitrogen protection. Stir the mixture and heat it to 215℃. Add 25g of catalyst solution to the reaction flask and stir for 20min. Cool the reaction flask to 140℃ and add 320g of 1,4-butanediamine. Keep the mixture warm for 4h. Discharge the mixture while it is still hot, cool it, pulverize it, and pass it through a 40-mesh sieve. Add xylene to a reaction flask at a solid-liquid ratio of 1:7 and stir. Heat the reaction flask to reflux and maintain the temperature for 3 hours. Cool the reaction flask to room temperature, filter, wash the filter cake twice with xylene and dry it. Transfer the filter cake to a drying oven at 70°C and dry it to constant weight to obtain ester-terminated polyamide.

[0022] Step S2: Preparation of amide-reinforced PET Weigh out 3100g of dimethyl terephthalate, 750g of ethylene glycol, 300g of 3-amino-1,5-pentanediol, and 1.2g of zinc acetate and add them to a reaction flask under nitrogen protection. Stir the mixture and heat the flask to 180℃. Maintain the temperature until 90% of the theoretical amount of methanol is removed. Add 700g of ester-terminated polyamide and 1g of antimony trioxide to the reaction flask. Apply a negative pressure of -0.1MPa to the reaction flask and heat it to 240℃. Maintain the temperature for condensation for 2 hours and discharge the product while it is still hot to obtain amide-reinforced PET.

[0023] Step S3: Preparation of reactive PCDI Weigh out 100g of tetramethyldiphenyl diisocyanate and 50g of 1,5-diisocyanatopentane and add them to a reaction flask under nitrogen protection. Stir the mixture and heat the flask to 180℃. Add 0.5g of 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide catalyst to the reaction flask and maintain the temperature for 6h. Cool the reaction flask to 80℃ and add 500mL of toluene and 10g of 2-(ethylene oxide-2-yl)ethanol-1-ol to the reaction flask. Maintain the temperature for 60min and then apply a negative pressure of -0.1MPa to the reaction flask. Remove low-boiling substances by vacuum distillation to obtain reactive PCDI.

[0024] Step S4: Preparation of epoxy-modified particles Weigh out 70g of nano-silica, 20g of KH-560, and 500mL of anhydrous ethanol and add them to a reaction flask. Stir the mixture and heat the reaction flask to 55℃. Add 50mL of 3mol / L sodium hydroxide aqueous solution to the reaction flask and keep it at this temperature for 40min. Cool the reaction flask to room temperature, filter the mixture, wash the filter cake with purified water until neutral, and then dry it. Transfer the filter cake to a drying oven at 60℃ and dry it to constant weight to obtain epoxy-modified particles.

[0025] Step S5: Prepare polyester yarn Dispersant zinc stearate, lubricant pentaerythritol tetrastearate, organotin stabilizer, antioxidant 1010, and antistatic agent SN were mixed evenly in a weight ratio of 5:3:2:2:1 to obtain auxiliary additives; Weigh out the following by weight: 100 parts of amide-reinforced PET, 5 parts of reactive PCDI, 1 part of epoxy-modified particles, and 3 parts of auxiliary additives. Place them in a drying oven at 95°C and dry until the moisture content is reduced to less than 10 ppm to obtain the pretreated dried material. The pretreated and dried material was added to a twin-screw extruder. The temperatures of the five temperature zones of the twin-screw extruder from the feed end to the discharge end were set to 255℃, 260℃, 260℃, 265℃, and 265℃ respectively, and the die temperature was set to 270℃. After melting and mixing for 3 minutes, the mixture was filtered through a 40-mesh sieve and then melt-extruded into a melt spinning machine. The melt spinning temperature was set to 288℃, and the filaments were ejected through a spinneret with an aperture of 0.2mm and an aspect ratio of 3:1. The spinning speed was set to 600m / min, and the spinning was cooled by air with a temperature of 18℃, a humidity of 75%, and an air velocity of 0.6m / s to obtain crude polyester filaments. The crude polyester filament is sequentially drawn through a first hot roller at 85°C, a second hot roller at 130°C, a third hot roller at 230°C, and a fourth hot roller at 200°C, with a total draw ratio of 5.6 times. It is then wound at a speed of 3000 m / min to obtain the polyester filament.

[0026] Example 2 This embodiment provides a method for preparing high-strength, low-elongation industrial polyester yarn, including the following steps: Step S1: Preparation of ester-terminated polyamide 2-Ethyl-1-hexanotoxide titanium and xylene were mixed evenly at a ratio of 1 g: 2 mL to obtain a catalyst solution; Weigh out 960g of dimethyl terephthalate and 305g of diphenyl terephthalate and add them to a reaction flask under nitrogen protection. Stir the mixture and heat the reaction flask to 220℃. Add 26.5g of catalyst solution to the reaction flask and keep it heated and stirred for 23min. Cool the reaction flask to 145℃ and add 335g of 1,4-butanediamine to the reaction flask. Keep it heated for 5h. Discharge the material while it is hot, cool it and then crush it and pass it through a 40-mesh sieve. Add xylene to a reaction flask at a solid-liquid ratio of 1:7.5 and stir. Heat the reaction flask to reflux and maintain the temperature for 4 hours. Cool the reaction flask to room temperature, filter, wash the filter cake twice with xylene and dry it. Transfer the filter cake to a drying oven at 75°C and dry it to constant weight to obtain ester-terminated polyamide.

[0027] Step S2: Preparation of amide-reinforced PET Weigh out 3100g of dimethyl terephthalate, 800g of ethylene glycol, 300g of 3-amino-1,5-pentanediol, and 1.35g of zinc acetate and add them to a reaction flask under nitrogen protection. Stir the mixture and heat the flask to 190℃. Maintain the temperature until 90% of the theoretical amount of methanol is removed. Add 750g of ester-terminated polyamide and 1g of antimony trioxide to the reaction flask. Apply a negative pressure of -0.1MPa to the reaction flask and heat it to 245℃. Maintain the temperature for condensation for 2.5h. Discharge the mixture while it is still hot to obtain amide-reinforced PET.

[0028] Step S3: Preparation of reactive PCDI Weigh out 110g of tetramethyldiphenyl diisocyanate and 60g of 1,5-diisocyanatopentane and add them to a reaction flask under nitrogen protection. Stir the mixture and heat the flask to 190℃. Add 0.5g of 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide catalyst to the reaction flask and maintain the temperature for 7h. Cool the reaction flask to 85℃ and add 500mL of toluene and 15g of 2-(ethylene oxide-2-yl)ethanol-1-ol to the reaction flask. Maintain the temperature for 70min and then apply a negative pressure of -0.1MPa to the reaction flask. Remove low-boiling substances by vacuum distillation to obtain reactive PCDI.

[0029] Step S4: Preparation of epoxy-modified particles Weigh out 70g of nano-silica, 25g of KH-560, and 500mL of anhydrous ethanol and add them to a reaction flask. Stir the mixture and heat the reaction flask to 60℃. Add 50mL of 4mol / L sodium hydroxide aqueous solution to the reaction flask and keep the mixture at this temperature for 50min. Cool the reaction flask to room temperature, filter the mixture, wash the filter cake with purified water until neutral, and then dry it. Transfer the filter cake to a drying oven at 65℃ and dry it to constant weight to obtain epoxy-modified particles.

[0030] Step S5: Prepare polyester yarn The dispersant calcium stearate, the lubricant pentaerythritol tetrastearate, the organotin stabilizer, the antioxidant 1010, and the antistatic agent SN were mixed evenly in a weight ratio of 5:3:2:2:1 to obtain the auxiliary additive. Weigh out the following by weight: 100 parts of amide-reinforced PET, 6 parts of reactive PCDI, 1.25 parts of epoxy-modified particles, and 4 parts of auxiliary additives. Place them in a drying oven at 100°C and dry until the moisture content is reduced to less than 10 ppm to obtain the pretreated dried material. The pretreated and dried material was added to a twin-screw extruder. The temperatures of the five temperature zones of the twin-screw extruder from the feed end to the discharge end were set to 255℃, 260℃, 260℃, 265℃, and 265℃ respectively, and the die temperature was set to 270℃. After melting and mixing for 4 minutes, the mixture was filtered through a 40-mesh sieve and then melt-extruded into a melt spinning machine. The melt spinning temperature was set to 293℃, and the filaments were ejected through a spinneret with an aperture of 0.25mm and an aspect ratio of 3:1. The spinning speed was set to 700m / min, and the spinning was cooled by air with a temperature of 20℃, a humidity of 80%, and an air velocity of 0.7m / s to obtain crude polyester filaments. The crude polyester filament is sequentially drawn through a first hot roller at 90°C, a second hot roller at 140°C, a third hot roller at 240°C, and a fourth hot roller at 210°C, with a total draw ratio of 5.9 times. It is then wound at a speed of 3200 m / min to obtain the polyester filament.

[0031] Example 3 This embodiment provides a method for preparing high-strength, low-elongation industrial polyester yarn, including the following steps: Step S1: Preparation of ester-terminated polyamide 2-Ethyl-1-hexanotoxide titanium and xylene were mixed evenly at a ratio of 1 g: 2 mL to obtain a catalyst solution; Weigh out 970g of dimethyl terephthalate and 310g of diphenyl terephthalate and add them to a reaction flask under nitrogen protection. Stir the mixture and heat it to 225°C. Add 28g of catalyst solution to the reaction flask and stir for 25 minutes. Cool the reaction flask to 150°C and add 350g of 1,4-butanediamine. Keep the mixture warm for 6 hours. Discharge the mixture while it is still hot, cool it, pulverize it, and pass it through a 40-mesh sieve. Add xylene to a reaction flask at a solid-liquid ratio of 1:8 and stir. Heat the reaction flask to reflux and maintain the temperature for 5 hours. Cool the reaction flask to room temperature, filter, wash the filter cake twice with xylene and dry it. Transfer the filter cake to a drying oven at 80°C and dry it to constant weight to obtain ester-terminated polyamide.

[0032] Step S2: Preparation of amide-reinforced PET Weigh out 3100g of dimethyl terephthalate, 850g of ethylene glycol, 300g of 3-amino-1,5-pentanediol, and 1.5g of zinc acetate and add them to a reaction flask under nitrogen protection. Stir the mixture and heat the reaction flask to 200℃. Maintain the temperature until the methanol content reaches 90% of the theoretical amount. Add 800g of ester-terminated polyamide and 1g of antimony trioxide to the reaction flask. Apply a negative pressure of -0.1MPa to the reaction flask and heat it to 250℃. Maintain the temperature for condensation for 3 hours and discharge the material while it is still hot to obtain amide-reinforced PET.

[0033] Step S3: Preparation of reactive PCDI Weigh 120g of tetramethyldiphenyl diisocyanate and 70g of 1,5-diisocyanatopentane and add them to a reaction flask under nitrogen protection. Stir the mixture and heat the flask to 200℃. Add 0.5g of 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide catalyst to the reaction flask and maintain the temperature for 8 hours. Cool the reaction flask to 90℃ and add 500mL of toluene and 20g of 2-(ethylene oxide-2-yl)ethanol-1-ol to the reaction flask. Maintain the temperature for 80 minutes and then apply a negative pressure of -0.1MPa to the reaction flask. Remove low-boiling substances by vacuum distillation to obtain reactive PCDI.

[0034] Step S4: Preparation of epoxy-modified particles Weigh out 70g of nano-silica, 30g of KH-560, and 500mL of anhydrous ethanol and add them to a reaction flask. Stir the mixture and heat the reaction flask to 65℃. Add 50mL of 5mol / L sodium hydroxide aqueous solution to the reaction flask and keep it at this temperature for 60min. Cool the reaction flask to room temperature, filter the mixture, wash the filter cake with purified water until neutral, and then dry it. Transfer the filter cake to a drying oven at 70℃ and dry it to constant weight to obtain epoxy-modified particles.

[0035] Step S5: Prepare polyester yarn The dispersant barium stearate, the lubricant pentaerythritol tetrastearate, the organotin stabilizer, the antioxidant 1010, and the antistatic agent SN were mixed evenly in a weight ratio of 5:3:2:2:1 to obtain the auxiliary additive. Weigh out the following by weight: 100 parts of amide-reinforced PET, 7 parts of reactive PCDI, 1.5 parts of epoxy-modified particles, and 5 parts of auxiliary additives. Place them in a drying oven at 105°C and dry until the moisture content is reduced to less than 10 ppm to obtain the pretreated dried material. The pretreated and dried material was added to a twin-screw extruder. The temperatures of the five temperature zones of the twin-screw extruder from the feed end to the discharge end were set to 255℃, 260℃, 260℃, 265℃, and 265℃ respectively, and the die temperature was set to 270℃. After melting and mixing for 5 minutes, the mixture was filtered through a 40-mesh sieve and then melt-extruded into a melt spinning machine. The melt spinning temperature was set to 298℃, and the filaments were ejected through a spinneret with an aperture of 0.3mm and an aspect ratio of 3:1. The spinning speed was set to 800m / min, and the spinning was cooled by air with a temperature of 22℃, a humidity of 85%, and an air velocity of 0.80m / s to obtain crude polyester filaments. The polyester filament is sequentially drawn through a first hot roller at 95°C, a second hot roller at 150°C, a third hot roller at 250°C, and a fourth hot roller at 220°C, with a total draw ratio of 6.2 times. It is then wound at a speed of 3400 m / min to obtain the polyester filament.

[0036] Comparative Example 1 The difference between this comparative example and Example 3 is that step S1 is omitted and ester-terminated polyamide is not added in step S2.

[0037] Comparative Example 2 The difference between this comparative example and Example 3 is that 2-(ethylene oxide-2-yl)ethanol-1-ol was not added in step S3.

[0038] Comparative Example 3 The difference between this comparative example and Example 3 is that step S4 is omitted, and the epoxy-modified particles in step S5 are replaced with nano-silica in step S4.

[0039] Performance testing: The breaking strength and dry heat shrinkage of the polyester filament samples prepared in Examples 1-3 and Comparative Examples 1-3 were determined according to the standard GB / T 16604-2017 "Polyester Industrial Filament" (Method A, 190℃). The elongation at break of the polyester filament samples prepared in Examples 1-3 and Comparative Examples 1-3 was determined according to the standard GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments" (tensile speed 50 mm / min). Referring to the standard GB / T 11547-2008 "Determination of the resistance of plastics to liquid chemical reagents", the polyester filament samples prepared in Examples 1-3 and Comparative Examples 1-3 were placed in a 10wt% hydrochloric acid and 5wt% sodium hydroxide aqueous solution at a temperature of 70±2℃ and soaked for 1 week. The breaking strength and elongation at break of the samples were measured. The specific test data are shown in Table 1 below.

[0040]

[0041] Data Analysis: Comparative analysis of the data in Table 1 shows that the polyester filament prepared by this invention exhibits a breaking strength of 8.14-8.52 cN / dtex, an elongation at break of 7.53-7.14%, and a dry heat shrinkage rate of 4.2-4.5%. After immersion in 10 wt% hydrochloric acid, the breaking strength reaches 7.62-8.03 cN / dtex, and the elongation at break reaches 6.95-7.31%. After immersion in 5 wt% sodium hydroxide aqueous solution, the breaking strength reaches 7.43-7.82 cN / dtex, and the elongation at break reaches 6.34- The yield was 6.65%, and all performance test data were superior to the comparative example. This indicates that the present invention prepares ester-terminated polyamide, which is then polycondensed with dimethyl terephthalate, ethylene glycol, and 3-amino-1,5-pentanediol to obtain amide-reinforced PET. The amide-reinforced PET, reactive PCDI, epoxy modified particles, and auxiliary additives are blended, and then melt-spun and subjected to multi-stage hot roller stretching and heat setting. This not only effectively improves the breaking strength and acid and alkali corrosion resistance of polyester filament, but also effectively reduces the breaking elongation and dry heat shrinkage of polyester filament material, demonstrating outstanding performance advantages in industrial environments.

[0042] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-strength low-elongation industrial polyester yarn, characterized by, It comprises the following components by weight: 100 parts amide-reinforced PET, 5-7 parts reactive PCDI, 1-1.5 parts epoxy-modified particles, and 3-5 parts auxiliary additives; The preparation method of amide-reinforced PET is as follows: Under the protection of an inert gas atmosphere, dimethyl terephthalate, ethylene glycol, 3-amino-1,5-pentanediol and transesterification catalyst are mixed and stirred. The reaction system is heated to 180-200℃ and kept at this temperature until the methanol removal reaches 90% of the theoretical amount. Ester-terminated polyamide and antimony trioxide are added to the reaction system. The reaction system is then subjected to a negative pressure of -0.1MPa. The reaction system is heated to 240-250℃ and kept at this temperature for condensation for 2-3 hours. The product is discharged while hot to obtain amide-reinforced PET. The reactive PCDI is obtained by catalytic decarboxylation condensation of tetramethyl diphenyl diisocyanate and 1,5-diisocyanopentane, followed by chain termination using 2-(ethylene oxide-2-yl)ethanol-1-ol as a capping agent.

2. The high-strength low-elongation industrial polyester yarn according to claim 1, characterized by, The weight ratio of dimethyl terephthalate, ethylene glycol, 3-amino-1,5-pentanediol, transesterification catalyst, ester-terminated polyamide, and antimony trioxide is 310:75-85:30:0.12-0.15:70-80: 0.1, wherein the transesterification catalyst is zinc acetate.

3. The high-strength low-elongation industrial polyester yarn according to claim 1, characterized by, The preparation method of ester-terminated polyamide is as follows: under the protection of an inert gas atmosphere, dimethyl terephthalate and diphenyl terephthalate are mixed and stirred, the reaction system is heated to 215-225℃, a catalyst solution is added to the reaction system, the mixture is kept at the temperature and stirred for 20-25 min, the reaction system is cooled to 140-150℃, 1,4-butanediamine is added to the reaction system, the mixture is kept at the temperature for 4-6 h, and then post-treated to obtain ester-terminated polyamide.

4. The high-strength, low-elongation industrial polyester filament according to claim 3, characterized in that, The weight ratio of dimethyl terephthalate, diphenyl terephthalate, catalyst solution, and 1,4-butanediamine is 950-970:300-310:25-28:320-350. The catalyst solution is composed of 2-ethyl-1-hexanotoxide titanium and xylene at a ratio of 1 g:2 mL. The post-treatment includes: after the reaction is complete, discharging the material while it is hot, cooling it, pulverizing it, mixing it with xylene at a solid-liquid ratio of 1:7-8, heating the reaction system to reflux, holding it at that temperature for 3-5 hours, cooling the reaction system to room temperature, filtering it, washing the filter cake twice with xylene, drying it, transferring the filter cake to a drying oven at a temperature of 70-80℃, and drying it to constant weight to obtain ester-terminated polyamide.

5. The high-strength, low-elongation industrial polyester filament according to claim 1, characterized in that, The preparation method of epoxy modified particles is as follows: nano-silica, KH-560 and anhydrous ethanol are mixed and stirred, the reaction system is heated to 55-65℃, alkali solution is added to the reaction system, the reaction is kept at the temperature for 40-60 min, and then post-processed to obtain epoxy modified particles.

6. The high-strength, low-elongation industrial polyester filament according to claim 5, characterized in that, The ratio of nano-silica, KH-560, anhydrous ethanol, and alkaline solution is 7g:2-3g:50mL:5mL. The alkaline solution is a 3-5mol / L sodium hydroxide aqueous solution. The post-treatment includes: after the reaction is complete, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, dried, and the filter cake is transferred to a drying oven at 60-70℃ and dried to constant weight to obtain epoxy modified particles.

7. The high-strength, low-elongation industrial polyester filament according to claim 1, characterized in that, The preparation method of reactive PCDI is as follows: under an inert gas atmosphere, tetramethyl diphenyl diisocyanate and 1,5-diisocyanopentane are mixed and stirred. The reaction system is heated to 180-200℃, a catalyst is added to the reaction system, and the reaction is maintained at this temperature for 6-8 hours. The reaction system is then cooled to 80-90℃, toluene and 2-(ethylene oxide-2-yl)ethanol-1-ol are added to the reaction system, and the reaction is maintained at this temperature for 60-80 minutes. After post-treatment, reactive PCDI is obtained.

8. The high-strength, low-elongation industrial polyester filament according to claim 7, characterized in that, The ratio of tetramethyl diphenyl diisocyanate, 1,5-diisocyanopentane, catalyst, toluene, and 2-(ethylene oxide-2-yl)ethanol-1-ol is 10-12 g: 5-7 g: 0.05 g: 50 mL: 1-2 g. The catalyst is 3-methyl-1-phenyl-2-phosphacyclopentene-1-oxide. The post-treatment includes: after the reaction is complete, the reaction system is evaporated to -0.1 MPa to remove low-boiling substances under reduced pressure, thereby obtaining reactive PCDI.

9. A method for preparing a high-strength, low-elongation industrial polyester filament as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Place amide-reinforced PET, reactive PCDI, epoxy-modified particles and auxiliary additives in a drying oven at a temperature of 95-105℃ and dry until the moisture content is reduced to less than 10ppm to obtain pretreated dried material. S2. Add the pretreated dried material to a twin-screw extruder, melt mix for 3-5 minutes, filter through a 40-mesh sieve, melt extrude into a melt spinning machine, spin through a spinneret and cool to obtain polyester filament crude product; S3. Coarse polyester filament is heat-stretched and shaped to obtain polyester filament.

10. The method for preparing high-strength, low-elongation industrial polyester yarn according to claim 9, characterized in that, In step S1, the auxiliary additives consist of dispersant, lubricant, heat stabilizer, antioxidant, and antistatic agent in a weight ratio of 5:3:2:2:

1. In step S2, the twin-screw extruder has five temperature zones from the feed end to the discharge end with temperatures of 255℃, 260℃, 260℃, 265℃, and 265℃ respectively; the die temperature is 270℃; the melt spinning temperature is 288-298℃; the spinneret orifice diameter is 0.2-0.3mm; the aspect ratio is 3:1; and the spinning speed is 600-800m / min. The yarn is cooled by air cooling at a temperature of 20±2℃, a humidity of 80±5%, and a wind speed of 0.7±0.10m / s. In step S3, the hot drawing and setting operation is as follows: the polyester yarn rough is sequentially passed through a first hot roller at 85-95°C for drawing, a second hot roller at 130-150°C for drawing, a third hot roller at 230-250°C for hot setting, and a fourth hot roller at 200-220°C for stabilization. The total drawing ratio is set to 5.6-6.2 times, and the yarn is wound at a speed of 3000-3400m / min to obtain polyester yarn.

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