High-strength wear-resistant polyester fiber and preparation method thereof

Abstract

The present application relates to the technical field of polyester fiber, in particular to a high-strength wear-resistant polyester fiber and a preparation method thereof. The present application aims to solve the problem that the mechanical strength and wear resistance of the existing polyester fiber are difficult to be considered simultaneously. Modified PET is obtained by esterification and polycondensation of terephthalic acid, ethylene glycol, hydroxyl-terminated polydimethylsiloxane and isophthalic acid; graphene and multi-walled carbon nanotubes are respectively subjected to oxidation treatment, and then grafted with polyether amine; then, the modified PET is melt-blended with PET chips to obtain nano master batch; short glass fibers and PET chips are melt-blended to prepare micron master batch; the modified PET, the nano master batch and the micron master batch are mixed, ultrasonically dispersed, and then additives are added; through melt spinning, three-stage stretching and three-stage heat setting treatment, the high-strength wear-resistant polyester fiber is obtained. Through the synergistic effect of components and process, the prepared fiber has excellent mechanical properties and wear resistance, and has wide application prospect in the fields of clothing, home textiles and industry.

Description

Technical Field

[0001] This invention relates to the field of polyester fiber technology, specifically to a high-strength, wear-resistant polyester fiber and its preparation method. Background Technology

[0002] Polyester is an important type of synthetic fiber and is the commercial name for polyester fiber. It is a fiber-forming polymer made from terephthalic acid or dimethyl terephthalate and ethylene glycol through esterification or transesterification and polycondensation reactions, and then spun and post-processed into fibers. Due to its high strength and easy processing properties, polyester fiber is widely used in the textile and industrial fields, but there is often a contradiction between its mechanical strength and abrasion resistance.

[0003] Traditional polyester fibers suffer from low elongation at break due to the rigidity and high crystallinity of PET molecular chains, and their abrasion resistance depends on surface coatings, which are susceptible to coating peeling. Existing technologies improve toughness through copolymerization modification or the addition of inorganic fillers, but the synergy between these methods is poor, and it is difficult to simultaneously achieve interfacial compatibility and uniform dispersion between the rigid reinforcing phase and the flexible toughening phase, thus limiting the application range of polyester fibers. In existing technologies, simply increasing crystallinity can enhance strength, but this leads to excessive molecular chain rigidity, decreased elongation at break, and stress concentration during friction, causing wear. Introducing flexible segments to improve toughness may reduce high-temperature stability and load-bearing capacity. In some studies, adding micron-sized glass fibers alone can provide rigid support, but interfacial defects easily lead to fracture; using only nanofillers results in stress concentration due to uneven dispersion, making it difficult to simultaneously achieve a balance between strength and abrasion resistance.

[0004] In summary, existing technologies improve flexibility through copolymerization modification but inevitably sacrifice strength and thermal stability. While adding fillers enhances overall fiber strength, interfacial compatibility issues reduce abrasion resistance. Focusing on improving a single property while neglecting synergistic optimization of multiple properties results in a persistent challenge in balancing mechanical strength and abrasion resistance, leading to insufficient overall performance and reduced service life in practical applications.

[0005] To address this, a high-strength, abrasion-resistant polyester fiber and its preparation method are proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a high-strength, abrasion-resistant polyester fiber and its preparation method. Modified PET is obtained by esterification and polycondensation of terephthalic acid, ethylene glycol, hydroxyl-terminated polydimethylsiloxane, and isophthalic acid. Graphene and multi-walled carbon nanotubes are oxidized separately and then grafted with polyetheramine. These are then melt-blended with PET chips to obtain nano-masterbatch. Short-cut glass fibers and PET chips are melt-blended to prepare micron-sized masterbatch. The modified PET, nano-masterbatch, and micron-sized masterbatch are mixed, ultrasonically dispersed, and then auxiliaries are added. The fiber is then melt-spun, stretched in three stages, and heat-set in three stages to obtain the high-strength, abrasion-resistant polyester fiber. Through the synergistic effect of the components and the process, the obtained fiber exhibits excellent mechanical properties and abrasion resistance, and has broad application prospects in clothing, home textiles, and industrial fields.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for preparing high-strength, abrasion-resistant polyester fiber, the preparation of which includes the following steps:

[0009] Modified PET was added to a high-speed mixer, followed by nano-masterbatch and micron-masterbatch. The mixture was heated and stirred to obtain a mixture. Additives were added to the mixture to obtain a composite material. The composite material was melt-spun and cooled to obtain nascent fibers. The nascent fibers were subjected to three-stage hot stretching and three-stage heat setting treatments, and then cooled and wound to obtain polyester fibers.

[0010] The modified PET is obtained by esterification polycondensation of terephthalic acid, ethylene glycol, hydroxyl-terminated polydimethylsiloxane and isophthalic acid;

[0011] Nano masterbatch is obtained by melt extrusion of nanofiller and PET chips;

[0012] The nanofiller was obtained by grafting graphene oxide and carbon oxide nanotubes with polyetheramine.

[0013] Micron-sized masterbatch is obtained by melt extrusion of chopped glass fibers and PET chips.

[0014] Preferably, the additives include polyethylene terephthalate-grafted maleic anhydride copolymer, antioxidant 1010, perfluoropolyether, and polytetrafluoroethylene micropowder.

[0015] Preferably, the preparation of modified PET includes the following steps:

[0016] Terephthalic acid, ethylene glycol, hydroxyl-terminated polydimethylsiloxane, and isophthalic acid were added and vacuum dried to obtain a dried raw material. The dried raw material was added to a high-speed mixer and heated and stirred to obtain a mixed system. The mixed system was added to a reaction vessel, and tetrabutyl titanate and triphenyl phosphite were added. Under nitrogen protection, esterification reaction was carried out to obtain esterified oligomers. The esterified oligomers were transferred to a polycondensation reaction vessel for polycondensation reaction. The material was discharged under nitrogen pressure, granulated underwater, and vacuum dried to obtain modified PET. The intrinsic viscosity of the modified PET was 0.65-0.75 dL / g. The average molecular weight of the hydroxyl-terminated polydimethylsiloxane was 1500-2500.

[0017] Preferably, the molar ratio of terephthalic acid to ethylene glycol is 1:1.2-1.5; the molar ratio of hydroxyl-terminated polydimethylsiloxane to terephthalic acid is 0.03-0.05:1; the molar ratio of isophthalic acid to terephthalic acid is 0.1-0.3:1; tetrabutyl titanate accounts for 0.05-0.1% of the mass of terephthalic acid; and triphenyl phosphite accounts for 0.1-0.2% of the mass of terephthalic acid.

[0018] Preferably, the preparation of the nanomasterbatch includes the following steps:

[0019] By mass fraction, 8-15 parts of nanofiller, 5 parts of polyethylene terephthalate-grafted maleic anhydride copolymer, and 75-90 parts of PET chips are added to a co-rotating twin-screw extruder for melt blending, using a combination of strong dispersion and weak shear, and vacuum degassing; then, through water cooling and stretching, pelletizing and drying, nano masterbatch is obtained.

[0020] Preferably, the temperature of the feeding section is 250-260℃; the temperature of the compression section is 270-275℃; the temperature of the metering section is 270-285℃; the temperature of the die head is 260-270℃; the control speed is 300-500 rpm; and the residence time is 8-10 min.

[0021] Preferably, during melt spinning, the spinning speed is controlled at 1200 m / min, a three-lobed hollow spinneret is used, the spinneret orifice diameter is 0.3 mm, the length-to-diameter ratio is 1:5, the cooling air temperature is 20℃, the air velocity is 1.5 m / s, and the cooling air humidity is controlled at 30%-40%, and nascent fibers are obtained by cooling.

[0022] Preferably, the three-stage hot stretching method includes: a low-temperature stage with a temperature of 80-90℃ and a stretching ratio of 1.5-2.0; a medium-temperature stage with a temperature of 100-120℃ and a stretching ratio of 1.8-2.5; and a high-temperature stage with a temperature of 120-130℃ and a stretching ratio of 1.2-1.5.

[0023] The three-stage heat setting process includes: the first stage temperature is 180-190℃, with a dwell time of 20s; the second stage temperature is 200-210℃, with a dwell time of 15s; and the third stage temperature is 220-230℃, with a dwell time of 10s.

[0024] Preferably, the preparation of the nanofiller includes the following steps:

[0025] Graphene was dispersed in deionized water by mass fraction and ultrasonically treated to obtain an ultrasonic solution. The solution was then washed three times with deionized water until neutral using the Hummer method and vacuum dried at 80°C for 5 hours to obtain graphene oxide. Its purity should be greater than 95%, and the particle size should be less than 1 μm. Multi-walled carbon nanotubes were added to a mixed solvent of concentrated sulfuric acid and concentrated nitric acid in a 3:1 volume ratio, oxidized at 60°C for 2 hours, separated and centrifuged at 6000 rpm for 20 minutes, washed five times with deionized water until neutral, and vacuum dried at 100°C for 10 hours to obtain carbon nanotube oxide. Its length should be uniformly within the range of 1-2 μm. Fifty parts of graphene oxide and fifty parts of carbon nanotube oxide were added to a mortar and pestle, using zirconium oxide grinding balls, controlling the ball-to-material ratio at 5:1-10:1, and rotating at 300-500 rpm. Ball milling for 2-4 hours yields a nano-mixture; the nano-mixture is dispersed in anhydrous DMF, and excess thionyl chloride is added at a mass ratio of 5:1 to the nano-mixture. The mixture is reacted at 60-70℃ for 3-6 hours under nitrogen protection, and the residual solvent is removed by rotary evaporation to obtain an acyl chloride material; under nitrogen protection, 50 parts of polyetheramine (molecular weight 1000-2000) are added to the acyl chloride material, and the temperature is raised to 100-120℃ for a grafting reaction for 10-15 hours to obtain a reaction system; the reaction system is placed in an absorption device containing an appropriate amount of water to absorb the generated HCl gas, then separated and centrifuged. The mixture is washed five times alternately with deionized water and anhydrous ethanol, and then dried at -40℃ and 10 Pa vacuum for 12 hours using a vacuum freeze-drying method to obtain the nanofiller. The grafting rate should be greater than 70%.

[0026] Preferably, the preparation of micron-sized masterbatch includes the following steps:

[0027] 20-30 parts of chopped glass fiber (3-5 mm in length), 5 parts of PET-g-MAH, and 70-80 parts of PET chips are added to a co-rotating twin-screw extruder for melt blending. The residence time is 6-8 minutes, using a combination of weak shear and rapid conveying. The feeding section temperature is 245-255℃; the compression section temperature is 260-270℃; the metering section temperature is 265-275℃; and the die head temperature is 250-260℃. The rotation speed is controlled at 150-250 rpm. The mixture is then water-cooled, stretched, granulated, and dried to obtain micron-sized masterbatch.

[0028] The present invention also provides a high-strength, wear-resistant polyester fiber, comprising modified PET, nano masterbatch, micron masterbatch, polyethylene terephthalate-grafted maleic anhydride copolymer, antioxidant 1010, perfluoropolyether, and polytetrafluoroethylene micropowder.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. This invention introduces flexible siloxane segments and isophthalic acid through copolymerization. Although this reduces the regularity of the PET molecular chain, the low glass transition temperature of the siloxane bond endows the chain segments with mobility, alleviating the rigidity and brittleness of pure PET. Simultaneously, the siloxane segments act as "molecular springs" to absorb energy during stretching, preventing stress concentration-induced breakage. The isophthalic acid disrupts the linear regularity of the PET molecular chain, inhibiting the formation of large-sized crystals and forming uniformly sized small crystals, resulting in more uniform molecular chain slippage during stretching. Through the synergistic effect of these two components, the mechanical properties of polyester fibers are improved. Furthermore, the introduction of graphene oxide and carbon nanotubes, grafted with polyetheramine, allows the surface amine groups to bond with PET-g-M... The anhydride groups of AH form covalent bonds, improving the interfacial bonding strength. Ultrasonic dispersion ensures the nanofiller is uniformly distributed within the PET matrix, forming a nano-reinforcing network. Under external force, the fiber strength is further enhanced through load transfer and crack deflection effects. The addition of chopped glass fibers as a rigid framework creates a micron-nano dual-scale reinforcement system. Micron-scale fibers resist macroscopic deformation, while nanofillers suppress microscopic cracks, further improving fiber strength. Finally, a three-stage stretching process is employed: low-temperature high-strength stretching fixes the initial molecular chain orientation; medium-temperature relaxation stretching forms an oriented crystalline network; and high-temperature qualitative stretching eliminates internal stress, achieving a balance between breaking strength and elongation.

[0031] 2. This invention introduces polysiloxane, whose high bond energy allows siloxane segments to form a "flexible heat insulation layer" at temperatures above 200°C, hindering heat conduction to the PET matrix and increasing the heat distortion temperature, thus improving heat resistance. The synergistic introduction of graphene and carbon nanotubes, with their high thermal conductivity, rapidly dissipates localized heat, preventing hotspot formation. The nanosheets form a thermal conductivity barrier within the matrix, delaying heat diffusion and further enhancing the fiber's heat resistance. During the segmented heat setting process, the first stage at low temperature promotes the diffusion of molecular chains from the amorphous region to the crystalline region, forming initial crystal nuclei. The second stage at medium temperature promotes rapid growth of these nuclei into a complete α-crystalline form. The third stage at high temperature dissolves and recrystallizes small crystals, forming large, stable crystals, reducing crystal defects and significantly enhancing heat distortion resistance. Through the synergistic effect of the components and processes, the heat resistance of the fiber is further improved, increasing the overall strength of the fiber.

[0032] 3. This invention introduces hydroxyl-terminated polydimethylsiloxane into the modified PET matrix structure. During processing, the siloxane accumulates on the fiber surface, forming an elastic lubricating layer that buffers abrasive impacts, reduces surface microcracks during friction, and improves wear resistance. The synergistic use of nanofillers further enhances wear resistance. Graphene sheet structures are added in stages and uniformly distributed on the fiber surface to resist abrasive cutting. The addition of carbon nanotubes acts as micro-springs to absorb frictional heat and reduce frictional losses. Finally, the low surface energy of PFPE and the self-lubricating core-shell structure of PTFE work synergistically to form a lubricating film on the fiber surface, further resisting frictional losses. Utilizing the synergistic effect of multiple components and processes, a three-dimensional wear-resistant mechanism is formed, where a flexible matrix bears stress, rigid fillers disperse load, and a lubricating layer reduces friction, thereby improving the overall wear resistance of the fiber. Attached Figure Description

[0033] Figure 1 These are test diagrams of the heat resistance properties of polyester fibers obtained in Examples 6-7, Comparative Examples 4-6, and Comparative Examples 10-12 of the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] PET-g-MAH is a copolymer of polyethylene terephthalate grafted with maleic anhydride.

[0036] Please see Figure 1 This invention provides a high-strength, wear-resistant polyester fiber and its preparation method, the technical solution of which is as follows:

[0037] Example 1

[0038] 500 parts of terephthalic acid, 260 parts of ethylene glycol, 600 parts of hydroxyl-terminated polydimethylsiloxane, and 200 parts of isophthalic acid were added to a vacuum drying oven and dried at 100°C for 2 hours to obtain dried raw materials. The dried raw materials were added to a high-speed mixer, heated to 90°C, and stirred for 45 minutes to obtain a mixed system. The mixed system was added to a reaction vessel, along with 0.4 parts of tetrabutyl titanate and 0.8 parts of triphenyl phosphite. Under nitrogen protection, the mixture was stirred and heated to 250°C, with the pressure controlled at 0.4 MPa, and the esterification reaction was carried out for 3 hours to obtain esterified oligomers. The esterified oligomers were transferred to a polycondensation reaction vessel, heated to 280°C, and the vacuum degree was maintained at 50 Pa. The polycondensation reaction was carried out for 5 hours, and the mixture was discharged under nitrogen pressure, granulated underwater, and vacuum dried at 100°C for 10 hours to obtain modified PET.

[0039] Graphene was dispersed in deionized water and ultrasonicated at 300W for 60 min to obtain an ultrasonic solution. The solution was then washed three times with deionized water using the Hummer method until neutral, and vacuum dried at 80℃ for 5 h to obtain graphene oxide. Multi-walled carbon nanotubes were added to a mixed solvent of concentrated sulfuric acid and concentrated nitric acid in a 3:1 volume ratio, oxidized at 60℃ for 2 h, separated and centrifuged at 6000 rpm for 20 min, washed five times with deionized water until neutral, and vacuum dried at 100℃ for 10 h to obtain carbon nanotube oxide. 50 parts of graphene oxide and 50 parts of carbon nanotube oxide were added to a mortar and pestle, and zirconia grinding balls were used at a ball-to-material ratio of 8:1 and a grinding speed of 400 rpm. The nano-mixture was obtained by ball milling for 3 hours. The nano-mixture was dispersed in anhydrous DMF, and excess thionyl chloride was added at a mass ratio of 5:1 to the nano-mixture. The mixture was reacted at 70°C for 4 hours under nitrogen protection, and the residual solvent was removed by rotary evaporation to obtain the acyl chloride material. Under nitrogen protection, 50 parts of polyetheramine were added to the acyl chloride material, and the temperature was raised to 120°C. The grafting reaction was carried out for 10 hours to obtain the reaction system. The reaction system was placed in an absorption device containing an appropriate amount of water to absorb the generated HCl gas. After separation and centrifugation, the mixture was washed 5 times alternately with deionized water and anhydrous ethanol. The mixture was then dried at -40°C and 10 Pa under vacuum for 12 hours using a vacuum freeze-drying method to obtain the nanofiller.

[0040] Twelve parts of nanofiller, five parts of PET-g-MAH, and eighty-five parts of PET chips were added to a co-rotating twin-screw extruder for melt blending. The residence time was set to 10 minutes. A combination of strong dispersion and weak shear was used, and the speed was controlled at 500 rpm. The mixture was melt-extruded and vacuum-vented. The nano masterbatch was then obtained by water-cooling, pelletizing, and drying.

[0041] Twenty parts of chopped glass fiber, five parts of PET-g-MAH, and eighty parts of PET chips were added to a co-rotating twin-screw extruder for melt blending. The residence time was 8 minutes, and a combination of weak shear and rapid transport was used, with the speed controlled at 200 rpm. The mixture was then granulated and dried by water cooling to obtain micron-sized masterbatch.

[0042] 90 parts of modified PET were added to a high-speed mixer. After stirring, 15 parts of nano masterbatch and 25 parts of micron masterbatch were added sequentially. The mixture was heated to 90℃ and stirred for 2 hours to obtain a mixture. 0.5 parts of antioxidant 1010, 6 parts of PET-g-MAH, and 6 parts of a mixture of PFPE and PTFE micro powder in a 2:1 mass ratio were added to the mixture to obtain a molten material. The molten material was added to a melt spinning device, and the extrusion speed was controlled at 60 ml / h to obtain a melt. The melt was then spun and cooled to obtain nascent fibers.

[0043] The nascent fibers are subjected to three-stage hot stretching using a stretching machine to obtain stretched fibers; the stretched fibers are then added to a vacuum drying oven for three-stage heat setting treatment, and cooled and wound to obtain high-strength, wear-resistant polyester fibers.

[0044] The three-stage hot stretching process includes: a low-temperature stage at 80℃ with a stretching ratio of 1.5-2.0; a medium-temperature stage at 120℃ with a stretching ratio of 1.8-2.5; and a high-temperature stage at 130℃ with a stretching ratio of 1.2-1.5.

[0045] The three-stage heat setting process includes: the first stage temperature is 180℃, and the dwell time is 20s; the second stage temperature is 205℃, and the dwell time is 15s; the third stage temperature is 230℃, and the dwell time is 10s.

[0046] Examples 2-5 follow the same preparation method and parameter conditions as Example 1, with differences shown in Table 1.

[0047] Table 1. Parameter variations in Examples 1-5

[0048]

[0049] Comparative Example 1 is the same as Example 1, except that no hydroxyl-terminated polydimethylsiloxane was added to obtain modified PET.

[0050] Comparative Example 2 is the same as Example 1, except that no isophthalic acid was added to obtain modified PET.

[0051] Comparative Example 3 is the same as Example 1, except that no modification treatment is performed during the synthesis of PET.

[0052] Comparative Example 4 is the same as Example 1, except that no nano-masterbatch is introduced, and only micron-masterbatch is used.

[0053] Comparative Example 5 is the same as Example 1, except that micron-sized masterbatches are not introduced, and only nano-sized masterbatches are used.

[0054] Comparative Example 6 is the same as Example 1, except that neither micron-sized masterbatch nor nano-sized masterbatch is introduced at the same time, and nascent fibers are obtained by directly modifying PET in equal amounts and melt spinning.

[0055] Comparative Example 7 is the same as Example 1, except that the three-stage stretching process is not used, and only the medium-temperature and high-temperature stages are performed.

[0056] Comparative Example 8 is the same as Example 1, except that the three-stage stretching process is not used, and only the high-temperature stage is performed.

[0057] Comparative Example 9 is the same as Example 1, except that high-speed stirring is not performed during the preparation of nascent fibers.

[0058] Experiment Example 1 Mechanical Property Testing

[0059] The polyester fibers prepared in Examples 1-5 and Comparative Examples 1-9 were tested for breaking strength and breaking elongation according to the test method of GB / T 14344-2022. The test results are shown in Table 2.

[0060] Table 2 Test results of Examples 1-5 and Comparative Examples 1-9

[0061]

[0062]

[0063] As shown in Table 2, the polyester fibers obtained in the comparative examples, through adjustments to the components and processes, exhibited significantly reduced mechanical properties compared to the examples, failing to maintain a balance between breaking strength and elongation at break. In Comparative Examples 1-3, the absence of hydroxyl-terminated polydimethylsiloxane and the lack of introduction of siloxane bonds through copolymerization resulted in reduced molecular chain flexibility and excessive rigidity of the PET molecular chains, leading to a decrease in elongation at break. Simultaneously, the lack of lubrication from the siloxane resulted in stress concentration within the fibers, further reducing breaking strength. The absence of isophthalic acid resulted in high regularity of the PET molecular chains, increased molecular chain rigidity, and a significant decrease in elongation at break. While the initial strength of the material is reduced due to its high crystallinity, the change in strength is small. Without modification, pure PET molecules are highly polar and crystalline, lacking flexible segments and comonomers for regulation. This results in brittle fibers with significantly reduced breaking strength and elongation. The lack of synergistic effects from isophthalic acid and siloxanes further degrades mechanical properties. Comparative Examples 4-6 show that nanofillers can enhance interfacial bonding and uniformly disperse stress. Simultaneously, micron-sized glass fibers provide rigid support. However, when only micron-sized masterbatches are used, the stress-dispersing effect of nanofillers is lacking, and the fibers are prone to stress instability due to interfacial defects in the micron-fillers. Fracture leads to a decrease in strength and elongation. The "skeleton effect" of glass fiber can restrict molecular chain slippage. Although the elongation increases slightly after the fiber is missing, the strength loss is more significant. Nano and micro fillers achieve a strength-toughness balance through synergistic effects. Nano fillers refine the grains, while micro fillers bear the load. After the fiber is missing, it relies solely on the properties of the modified PET itself, lacking external reinforcement, resulting in a decrease in both strength and elongation. The results of Comparative Examples 7-8 show that the three-stage stretching process gradually optimizes the molecular chain arrangement through low-temperature orientation, medium-temperature refinement, and high-temperature setting. The absence of low-temperature orientation results in insufficient initial orientation of the molecular chains. During high-temperature stretching, slippage or breakage is prone to occur, leading to a decrease in breaking strength and elongation. Similarly, direct high-temperature processing results in violent molecular chain movement at high temperatures, lacking the gradual orientation at low and medium temperatures, leading to a loose internal fiber structure and extremely low orientation. This makes the fiber prone to random breakage during stretching, significantly reducing both strength and elongation. In Comparative Example 9, the high-speed mechanical stirring process breaks up the nanofiller agglomerates, ensuring their uniform dispersion in the PET matrix. Without this process, the nanofillers are prone to agglomerate, forming stress concentration points, which leads to a decrease in fiber strength. At the same time, the agglomerates hinder molecular chain slippage, further reducing the breaking elongation.

[0064] Example 6 is the same as Example 1;

[0065] Examples 7-9 follow the same preparation method parameters and conditions as Example 1, with differences shown in Table 3.

[0066] Table 3. Parameter changes in Examples 6-9

[0067]

[0068] Comparative Example 10 is the same as Example 1, except that only graphene oxide was used to modify the nanofiller.

[0069] Comparative Example 11 is the same as Example 1, except that only carbon oxide nanotubes are used to modify the nanofiller.

[0070] Comparative Example 12 is the same as Example 1, except that polyetheramine modification treatment is not used.

[0071] Comparative Example 13 is the same as Example 1, except that the nanofiller is not obtained by melting PET chips to obtain nano masterbatch, but is directly melt-blended and spun.

[0072] Comparative Example 14 is the same as Example 1, except that it does not undergo the three-stage heat setting process, but only the second stage of heat setting.

[0073] Comparative Example 15 is the same as Example 1, except that it does not undergo the three-stage heat setting process, but only undergoes the third stage of heat setting treatment.

[0074] Experiment Example 2: Heat Resistance Test

[0075] The initial breaking strength of the polyester fibers prepared in Examples 6-9, Comparative Examples 1, 4-6, and 10-15 was tested according to the test method of GB / T14344-2022. The polyester fibers were placed in a heat aging chamber and treated at 180°C for 30 min, then cooled to room temperature. The strength after treatment was tested, and the breaking strength retention rate was calculated. The test results are shown in Table 4. The breaking strength retention rates of the polyester fibers obtained in Examples 6-7, Comparative Examples 4-6, and Comparative Examples 10-12 are shown in Table 4. Figure 1 As shown.

[0076] Table 4. Test results of Examples 6-9, Comparative Examples 1, Comparative Examples 4-6, and Comparative Examples 10-15

[0077]

[0078]

[0079] The results in Table 4 show that the polyester fibers obtained by adjusting the components and processes in the comparative examples have significantly reduced heat resistance compared to the examples. Comparative Example 1 shows that the introduction of siloxane bonds in hydroxyl-terminated polydimethylsiloxane improves the heat resistance of the main chain. Simultaneously, the flexible segments can dissipate heat stress through molecular chain sliding, preventing the PET molecular chains from breaking due to rigid stacking at high temperatures. Without these additions, the rigidity of the PET molecular chains increases, leading to increased stress concentration at high temperatures and a more significant decrease in breaking strength. Comparative Examples 4-6 show that when only micron-sized glass fibers are used, the lack of thermal conductivity and interfacial reinforcement from nanofillers results in concentrated internal thermal stress at high temperatures, leading to a more significant decrease in strength. Similarly, relying solely on nanofillers fails to provide sufficient high-temperature support, exacerbating molecular chain slippage and increasing the magnitude of strength reduction, thus lowering heat resistance. Nano / micron fillers form a thermally conductive-reinforcing network; nanofillers conduct heat, while microfillers bear the load. Without these additions, the fibers rely solely on the thermal stability of the modified PET itself, and the violent movement of molecular chain segments reduces strength under thermal conditions. Significant decrease; in Comparative Examples 10-11, when graphene oxide is used alone, the lack of a directional heat conduction path provided by carbon nanotubes leads to heat accumulation within the fibers, resulting in a decrease in high-temperature strength; the absence of graphene oxide also results in poor dispersion of the nanofiller, weak interfacial adhesion, and easy detachment from the matrix at high temperatures; combined with the results of Comparative Example 12, it can be seen that polyetheramine introduces amine groups onto the surface of the nanofiller through a grafting reaction, forming chemical bonds with PET-g-MAH, thereby improving the interfacial adhesion between the filler and the matrix. When the grafting rate is insufficient, the nanofiller and the PET matrix are physically adsorbed. The primary issue is that the interface is prone to debonding at high temperatures, leading to a greater decrease in strength. In Comparative Example 13, direct blending easily causes filler agglomeration, forming stress defects. The agglomerates become sources of thermal stress concentration at high temperatures, further triggering fiber breakage. In Comparative Examples 14-15, the absence of the first stage results in the failure to eliminate initial internal stress. At high temperatures, the molecular chains slip due to stress relaxation, exacerbating the strength decrease. The lack of the first and second stages of gradual crystallization optimization leads to the formation of coarse grains inside the fiber, which are prone to grain boundary slip at high temperatures, resulting in a significant decrease in strength.

[0080] Example 10 is the same as Example 1;

[0081] Examples 11-14 follow the preparation method and parameter conditions of Example 1, with differences shown in Table 5.

[0082] Table 5. Parameter variations in Examples 10-14

[0083]

[0084]

[0085] Comparative Example 16 is the same as Example 1, except that the nanofiller is not melted with PET chips to obtain nano masterbatch, and the chopped glass fiber is not melted with PET chips to obtain micron masterbatch. Instead, the nanofiller, chopped glass fiber and modified PET are directly melt-spun to obtain nascent fiber.

[0086] Comparative Example 17 is the same as Example 1, except that no lubricant is added.

[0087] Comparative Example 18 is the same as Example 1, except that the lubricant does not use PTFE micro powder, but uses an equal amount of PFPE.

[0088] Comparative Example 19 is the same as Example 1, except that the lubricant used is not PFPE, but an equal amount of PTFE micro powder.

[0089] Experiment Example 3: Wear Resistance Test

[0090] The polyester fibers prepared in Examples 10-14, Comparative Examples 1, 4-6, 13, and 16-19 were tested according to the GB / T 21196.1-2007 test method. The abrasion resistance of the fibers was reflected by the number of abrasion cycles, mass loss, and appearance changes under a load of 12 kPa. The test results are shown in Table 6.

[0091] Table 6 Test results of Examples 10-14, Comparative Examples 1, Comparative Examples 4-6, Comparative Examples 13, and Comparative Examples 16-19

[0092]

[0093]

[0094] As shown in Table 6, the polyester fibers obtained in the comparative examples, through adjustments to the composition and process, exhibited significantly reduced wear resistance compared to the examples. Comparative Example 1 revealed that the low glass transition temperature of the siloxane bonds allowed the molecular chains to alleviate frictional stress through slippage; their absence made the rigid PET chains prone to breakage due to stress concentration, leading to wear loss during friction. Furthermore, siloxanes could improve the interfacial adhesion between PET and fillers; their absence made the glass fibers and nanofillers prone to detach from the matrix. In Comparative Examples 4-6, the lack of nanofillers filling the gaps resulted in wear concentration around the glass fibers, creating micron-sized gaps that caused glass fibers to detach during friction, reducing wear resistance. The lack of the "physical barrier" provided by micron-sized glass fibers led to excessive deformation of the PET matrix during friction, causing internal tearing and a decrease in the number of wear cycles. Although hydrogen bonds between PET molecular chains provided some strength, the lack of external fillers to share the frictional load meant that wear acted directly on the matrix, leading to premature hole formation and a significant reduction in wear resistance. In Comparative Example 13, direct blending resulted in the formation of micron-sized aggregates of graphene oxide and carbon nanotubes, which became "hard" aggregates during friction. The "points" exacerbate matrix abrasion and wear, with visible pits formed at the agglomeration sites. Furthermore, in direct blending, the small contact area between large-diameter fillers and PET results in weak adhesion, making them prone to detachment during wear and affecting friction performance. In Comparative Example 16, without pre-melt extrusion of PET, the interaction between nanofiller agglomerates and glass fiber clumps during preparation leads to a chain reaction of wear, significantly reducing the number of wear cycles. Simultaneously, the edges of the glass fiber clumps cut into the PET matrix, and the detachment of nanofillers forms grooves, manifesting as matrix tearing and fiber detachment. In Comparative Examples 17-19, the high surface roughness of PET means that without lubricant, frictional work is directly converted into heat, leading to fiber melt-adhesive wear, resulting in severe scratches and exposed fibers. The addition of lubricant allows it to migrate to the surface during friction, forming a lubricating film and further improving fiber wear resistance. Without PTFE forming hard points to resist abrasives, the PET debris generated by friction exacerbates internal wear. However, the high surface energy of single PTFE leads to a dynamic imbalance between interfacial adhesion and friction at the contact surface, exacerbating fiber surface fatigue fracture.

[0095] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for the production of high strength abrasion resistant polyester fiber, characterized by, The preparation of the polyester fiber includes the following steps: Modified PET is added to a high-speed mixer, followed by the sequential addition of nano-masterbatch and micron-masterbatch. The mixture is heated and stirred to obtain a mixture. Additives are added to the mixture to obtain a blend material. The blend material is melt-spun and cooled to obtain nascent fibers. The nascent fibers are subjected to three-stage hot stretching and three-stage heat setting treatments, and then cooled and wound to obtain polyester fibers. The modified PET is obtained by esterification polycondensation of terephthalic acid, ethylene glycol, hydroxyl-terminated polydimethylsiloxane and isophthalic acid; The nano masterbatch is obtained by melt extrusion of nanofillers and PET chips; The nanofiller is obtained by grafting graphene oxide and carbon nanotubes with polyetheramine. The micron-sized masterbatch is obtained by melt extrusion of chopped glass fibers and PET chips.

2. The method for preparing high-strength, abrasion-resistant polyester fiber according to claim 1, characterized in that: The additives include polyethylene terephthalate-grafted maleic anhydride copolymer, antioxidant 1010, perfluoropolyether, and polytetrafluoroethylene micropowder.

3. The method for preparing high-strength, abrasion-resistant polyester fiber according to claim 1, characterized in that, The preparation of the modified PET includes the following steps: The terephthalic acid, ethylene glycol, hydroxyl-terminated polydimethylsiloxane, and isophthalic acid are added to a vacuum dryer to obtain a dried raw material; the dried raw material is added to a high-speed mixer and heated and stirred to obtain a mixed system; the mixed system is added to a reaction vessel, and tetrabutyl titanate and triphenyl phosphite are added. Under nitrogen protection, an esterification reaction is carried out to obtain an esterified oligomer; the esterified oligomer is transferred to a polycondensation reaction vessel for polycondensation reaction. The modified PET is obtained by nitrogen pressurization, underwater pelletizing, and vacuum drying.

4. The method for preparing high-strength, abrasion-resistant polyester fiber according to claim 1, characterized in that, The preparation of the nanomasterbatch includes the following steps: The nanofiller, polyethylene terephthalate-grafted maleic anhydride copolymer, and PET chips are added to a co-rotating twin-screw extruder for melt blending, using a combination of strong dispersion and weak shear, and vacuum degassing; then, the nano masterbatch is obtained by water-cooling, pelletizing, and drying.

5. The process for the preparation of high tenacity abrasion resistant polyester fiber as claimed in claim 4 wherein, The preparation of the nanofiller includes the following steps: Graphene was dispersed in deionized water, sonicated, washed with deionized water prepared by the Hummer method until neutral, and vacuum dried to obtain graphene oxide. Multi-walled carbon nanotubes were added to a mixed solvent of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1, oxidized, separated by centrifugation, washed with deionized water, and vacuum dried to obtain carbon nanotube oxide. The graphene oxide and carbon nanotube oxide were ball-milled to obtain a nano-mixture. The nano-mixture was dispersed in anhydrous DMF, and excess sulfoxide was added to react and obtain an acyl chloride material. Polyetheramine was added to the acyl chloride material to perform a grafting reaction to obtain a reaction system. The reaction system was separated by centrifugation, washed alternately with deionized water and anhydrous ethanol, and vacuum freeze-dried to obtain the nanofiller.

6. The method for preparing high-strength, abrasion-resistant polyester fiber according to claim 1, characterized in that, The preparation of the micron-sized masterbatch includes the following steps: The chopped glass fibers, PET-g-MAH, and PET chips are added to a co-rotating twin-screw extruder for melt blending, using a combination of weak shear and rapid transport; then, the mixture is granulated and dried by water cooling to obtain the micron-sized masterbatch.

7. A high strength abrasion resistant polyester fiber prepared by the process of claim 1, characterized by: The polyester fiber includes modified PET, nano master batch, micron master batch, polyethylene terephthalate grafted maleic anhydride copolymer, antioxidant 1010, perfluoropolyether, and polytetrafluoroethylene micro powder.

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