A tensile-resistant composite fiber and its preparation method

Abstract

This invention discloses a tensile-resistant composite fiber and its preparation method, belonging to the field of fiber preparation technology. It addresses the technical problem that the tensile and antistatic properties of composite fibers in existing technologies need further improvement. Specifically, it comprises the following components by weight: 60-80 parts modified PET, 15-20 parts modified toughening agent, 6-8 parts maleic anhydride-grafted polyolefin, and 1-3 parts auxiliary additives. The invention involves uniformly mixing the modified PET, modified toughening agent, maleic anhydride-grafted polyolefin, and auxiliary additives, adding them to a twin-screw extruder, melt-extruding, pelletizing to obtain masterbatch, then adding the masterbatch to a spinning machine for melt spinning, drawing and setting to obtain the composite fiber. This not only improves the tensile properties of the composite fiber but also enhances its antistatic and abrasion resistance.

Description

Technical Field

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

[0002] With the widespread application of high-performance fiber materials in fields such as electronic packaging, smart textiles, and industrial protection, the tensile strength, abrasion resistance, and antistatic properties of composite fibers have become key research and application areas.

[0003] Currently, commonly used matrix materials include polyethylene terephthalate (PET), polyamide (PA), and polyacrylonitrile (PAN), which are combined with toughening, conductive, and functional fillers to produce composite fibers. Common modification methods to improve fiber performance mainly include: introducing conductive reinforcing fillers such as carbon nanotubes, graphene, and conductive carbon black to improve antistatic properties and strength; achieving toughening by blending or grafting flexible segments such as elastic polyurethane, polyetheramine, and aliphatic polyamide; and improving wear resistance by introducing nano-inorganic materials.

[0004] However, traditional material systems and modification methods still have some obvious shortcomings:

[0005] For example, conductive fillers such as graphene and carbon nanotubes have poor dispersibility in polymer matrices and are prone to agglomeration, resulting in discontinuous conductive networks, which in turn limits the stability and durability of antistatic properties.

[0006] While flexible toughening agents can improve elongation at break, they often sacrifice some strength and have poor interfacial compatibility with rigid polymers such as PET, making them prone to microcracks.

[0007] Wear-resistant fillers are prone to falling off or failing under high-load friction conditions.

[0008] The main reasons for the above problems include: interface incompatibility, unstable physical filler structure, low efficiency of chemical modification, and lack of overall system architecture with collaborative design. Therefore, a solution is proposed. Summary of the Invention

[0009] The purpose of this invention is to provide a tensile-resistant composite fiber and its preparation method, which solves the technical problem that the tensile and antistatic properties of composite fibers in the prior art need to be further improved.

[0010] The objective of this invention can be achieved through the following technical solution: a tensile-resistant composite fiber, comprising the following components by weight: 60-80 parts modified PET, 15-20 parts modified toughening agent, 6-8 parts maleic anhydride grafted polyolefin and 1-3 parts auxiliary additives.

[0011] The modified PET is prepared by the following steps:

[0012] A1. Place modified graphene and ethylene glycol in a reaction vessel, heat the reaction vessel to 165-175℃, and keep the reaction at this temperature for 1-2 hours to obtain a graphene dispersion.

[0013] The reaction principle for preparing graphene dispersion is as follows:

[0014] During the reaction, the anhydride structure present on the surface of the modified graphene can undergo transesterification with ethylene glycol at high temperature, further introducing hydroxyl groups to obtain a uniformly dispersed graphene dispersion.

[0015] A2. Place the graphene dispersion, PTA powder, ethylene glycol, and antimony trioxide in a sealed reactor under nitrogen atmosphere and stir. Heat the reactor to 220-250℃ and maintain the temperature for 2-4 hours. Drain the water, heat the reactor to 250-270℃, evacuate to a vacuum of 50-100 Pa, and maintain the temperature for 0.5-1 hour. Post-process to obtain modified PET.

[0016] The reaction principle for the preparation of modified PET is as follows:

[0017] During the reaction, PTA reacts with ethylene glycol under the catalysis of antimony trioxide to generate ethylene glycol terephthalate intermediate. Further polycondensation reaction occurs under the catalysis of antimony trioxide. At this time, graphene has been introduced into ethylene glycol and undergoes co-condensation, block copolymerization and physical encapsulation with PTA / ethylene glycol to achieve chemical bonding into the PET main chain, thus obtaining modified PET.

[0018] Further, in step A1, the ratio of modified graphene to ethylene glycol is 3-5g:100-120mL; in step A2, the ratio of graphene dispersion, PTA powder, ethylene glycol, and antimony trioxide is 20-40mL:40-60g:10-20mL:0.5-1.0g; the post-processing step includes: after the reaction is completed, the reaction system is cooled to room temperature and the pressure is released to obtain modified PET.

[0019] Furthermore, the modified graphene is prepared by placing graphene oxide and N-methylpyrrolidone in a reaction vessel and stirring for 15-30 min. Hydroxyethyl methacrylate and dihydro-2,5-furandione are added and stirred for 5-10 min. Azobisisobutyronitrile is added, the reaction vessel is heated to 75-85℃, and the reaction is maintained for 4-6 h. The modified graphene is then obtained through post-treatment.

[0020] The preparation reaction principle of modified graphene is as follows:

[0021] During the reaction, the surface of graphene oxide contains abundant carboxyl, hydroxyl and epoxy groups. Under the initiation of azobisisobutyronitrile, hydroxyethyl methacrylate and dihydro-2,5-furandione undergo free radical polymerization on the surface of graphene oxide to form an organic coating, thus obtaining modified graphene.

[0022] Furthermore, the ratio of graphene oxide, N-methylpyrrolidone, hydroxyethyl methacrylate, dihydro-2,5-furandione, and azobisisobutyronitrile is 2-4g:100-150mL:6-8g:4-6g:0.4-0.8g. The post-processing steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed 2-4 times with ethanol and deionized water, transferred to an oven at 50-60℃, and dried to constant weight to obtain modified graphene.

[0023] Furthermore, the modified toughening agent is prepared by the following steps:

[0024] B1. Place the modified polyetheramine and tetrahydrofuran in a reaction vessel under nitrogen atmosphere and stir. Add diphenylmethane diisocyanate. Heat the reaction vessel to 30-40℃ and keep it at this temperature for 20-24 hours to obtain the prepolymer.

[0025] B2. Place the prepolymer and 1,5-diaminopentane in a reactor, heat the reactor to 45-55℃, and maintain the temperature for 40-48 hours. Then, perform post-treatment to obtain the modified toughening agent.

[0026] The preparation reaction principle of the modified toughening agent is as follows:

[0027] During the reaction, under heating conditions, the isocyanate groups of diphenylmethane diisocyanate react with the amino groups of modified polyetheramine to generate urea groups. Each diphenylmethane diisocyanate molecule can react with two amino groups to form a prepolymer. By controlling the amount of diphenylmethane diisocyanate added, a prepolymer with isocyanate groups at the end is obtained. Furthermore, the prepolymer undergoes a chain extension reaction with 1,5-diaminopentane to obtain a modified toughening agent.

[0028] Further, in step B1, the ratio of the modified polyetheramine to tetrahydrofuran is 15-20g:100-150mL, and diphenylmethane diisocyanate is added at 0.55 times the total molar amount of the modified polyetheramine amino group; in step B2, the ratio of the prepolymer to 1,5-diaminopentane is 100-120mL:2-4g, and the post-treatment step includes: after the reaction is completed, the reaction solution is transferred to an oven at a temperature of 50-60℃ and dried to constant weight to obtain the modified toughening agent.

[0029] Furthermore, the modified polyetheramine is prepared by the following steps:

[0030] C1. Place 3-bromothiophene-2-carbonyl diethyl acetal and tetrahydrofuran in a reaction vessel and stir. Cool the reaction vessel to -60℃±5℃, slowly add n-butyllithium, keep warm and stir for 20-30 min, add perfluorocyclopentene, restore the reaction vessel to room temperature, stir for 10-12 h, add p-toluenesulfonic acid, keep warm and react for 10-12 h, and then post-process to obtain intermediate I.

[0031] The reaction formula for the preparation of intermediate I is as follows:

[0032]

[0033] The reaction principle for the preparation of intermediate I is as follows:

[0034] During the reaction, under low temperature conditions, n-butyllithium undergoes a lithium-halogen exchange reaction with 3-bromothiophene-2-carbonyl diethyl acetal to generate an aromatic lithium active intermediate. Perfluorocyclopentene is a strongly electron-deficient double bond compound with strong reactivity to the aromatic lithium active intermediate. The two substances further undergo nucleophilic addition and hydrolyze to an aldehyde group under the catalysis of p-toluenesulfonic acid to obtain intermediate I.

[0035] C2. Place intermediate I, 3A molecular sieve and polyetheramine in a reaction vessel and stir. Add acetic acid aqueous solution to pH 6-7 and react at room temperature for 4-6 hours. Post-treatment yields modified polyetheramine.

[0036] The reaction formula for the preparation of modified polyetheramine is:

[0037]

[0038] The preparation reaction principle of modified polyetheramine is as follows:

[0039] During the reaction, the aldehyde group of intermediate I undergoes an amine-aldehyde condensation reaction with the amino group of the polyetheramine to generate a modified polyetheramine with a Schiff base structure.

[0040] Further, in step C1, the ratio of 3-bromothiophene-2-carbonyl diethyl acetal, tetrahydrofuran, n-butyllithium, perfluorocyclopentene, and p-toluenesulfonic acid is 4-6 g: 50-80 mL: 15-20 mL: 2-4 g: 0.5-1.0 g. The post-treatment step includes: after the reaction is complete, wait for the reaction system to cool to room temperature, add 30 mL of dichloromethane and 50 mL of deionized water to the reaction solution, wash 2-4 times, and transfer the organic phase to a temperature of 60-70°C. In a rotary evaporator at 0°C, the mixture is evaporated under reduced pressure until no liquid is collected, yielding intermediate I; in step C2, the weight ratio of intermediate I, 3A molecular sieve, and polyetheramine is 4-6:1-2:8-10, and the concentration of the acetic acid aqueous solution is 0.5-1.0 mol / L. The post-processing steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, and the filtrate is transferred to a rotary evaporator at a temperature of 90-100°C, evaporated under reduced pressure until no liquid is collected, yielding modified polyetheramine.

[0041] The present invention also provides a method for preparing a tensile-resistant composite fiber, comprising the following steps:

[0042] S1. Mix the modified PET, modified toughening agent, maleic anhydride grafted polyolefin and auxiliary additives evenly, add them to a twin-screw extruder, melt extrude, and pelletize to obtain masterbatch;

[0043] S2. Add the masterbatch to the spinning machine, melt spin, draw and set to obtain composite fiber.

[0044] Furthermore, the auxiliary additive is composed of antioxidants, plasticizers, and lubricants in a mass ratio of 1:4:4. The antioxidant is one or more of 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 4,4'-thiobis(6-tert-butyl-3-methylphenol). The plasticizer is one or more of dibutyl phthalate, diisononyl phthalate, and dioctyl sebacate. The lubricant is one or more of fatty acid amides, oleamides, and paraffin wax.

[0045] The present invention has the following beneficial effects:

[0046] 1. This invention involves the formation of an aromatic lithium intermediate from 3-bromothiophene-2-carbonyl acetal under the action of n-butyllithium, followed by addition with octafluorocyclopentene. This successfully introduces a perfluorinated functional group and a thiophene ring, endowing the modified polyetheramine with excellent thermal stability, hydrophobicity, and rigid structural units. Subsequently, acid-catalyzed deprotection forms an aldehyde group capable of condensing with amines, achieving covalent bonding between the polyetheramine and the heterocyclic structure. This enhances the molecular chain entanglement and interfacial bonding of the material. Furthermore, after the modified polyetheramine reacts with diisocyanate to form a prepolymer, it undergoes chain extension with 1,5-diaminopentane to form a higher molecular weight, more complex structure. A more stable polyurea-based toughening agent, which acts as a reactive toughening agent in composite fibers, can not only be effectively dispersed in the polyester matrix, but also form hydrogen bonds and chemical bonds with modified PET molecules through end groups. This enhances the compatibility and interfacial bonding strength between the modified toughening agent and other matrices, suppresses stress concentration, and thus significantly improves the tensile strength, elongation at break, and abrasion resistance of the composite fibers. In addition, the intramolecular freedom brought by the flexible segments of polyetheramine can also buffer the propagation of microcracks in the fibers during processing and use, enabling the composite fibers to maintain strength while possessing better abrasion resistance and toughness.

[0047] 2. This invention introduces functional groups into a thiophene acetal intermediate using n-butyllithium and octafluorocyclopentene, forming a structure with a diarylethylene backbone. This structure belongs to the photoisomerization unit and can undergo reversible ring-opening and ring-closing isomerization reactions under ultraviolet and visible light, thereby changing its electronic structure, polarity, and spatial configuration. When the composite fiber is slightly damaged or has microcracks, this structure can generate molecular motion under light or heat excitation, and through π-π stacking, hydrogen bond reconstruction, or dynamic covalent bond self-assembly, the cracks on the surface of the composite fiber can be partially closed or repaired, thereby achieving a self-healing effect. As a result, the tensile and abrasion resistance of the composite fiber is improved. In addition, the diisocyanate undergoes a polymerization reaction with the modified polyetheramine and 1,5-diaminopentane to form a network structure rich in amino groups, urea groups, flexible segments and rigid diarylene structures. This design endows the material with dynamic and reversible cross-linking points and flexible molecular migration channels. When micro-damage occurs, it can self-regulate and heal through molecular rearrangement and stress release. This not only improves the toughness and stability of the composite fiber, but also endows the material with reversibility, reconfigurability and local repair ability under light or heat response, thereby improving the service life and reliability of the composite fiber.

[0048] 3. In the preparation of modified PET, this invention involves surface grafting modification of graphene oxide with hydroxyethyl methacrylate and dihydro-2,5-furandione to form organically modified graphene with active double bonds and polar functional groups. This modified graphene is then reacted with ethylene glycol at high temperature to form a stable graphene dispersion. The addition of graphene significantly improves the antistatic properties of traditional PET and acts as a reinforcing and toughening filler at the microscale, enhancing the wear resistance of the composite fiber. Furthermore, the graphene dispersion is further condensed with PTA powder and ethylene glycol under antimony trioxide catalysis. The polymerization reaction forms a polyester backbone with an intramolecular graphene structure. This in-situ composite modification method has higher stability and interfacial compatibility compared with simple physical filling. The graphene sheets are connected to the modified PET chain segments through covalent bonds and hydrogen bonds, effectively avoiding the problem of aggregation and precipitation, and forming conductive channels in the material, which effectively improves the electron migration ability of the modified PET. Secondly, the two-dimensional sheet structure of graphene can build a micro-conductive network in the polymer, which can significantly reduce the surface resistance of the material even at low filling levels, prevent static electricity accumulation, and thus improve the antistatic ability of the fiber. Detailed Implementation

[0049] 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] The graphene oxide used in this invention was purchased from Henan Liugong Graphite Co., Ltd., with the grade lgshimo and a particle size of 500 mesh.

[0051] The polyetheramine used in this invention is purchased from Huaxiang Kejie brand polyetheramine with a molecular weight of 2000.

[0052] The maleic anhydride-grafted polyolefin used in this invention was purchased from Dongguan Hongyi Plastics Technology Co., Ltd., and its model number is XH8250LF5OV8.

[0053] Example 1

[0054] This embodiment provides a method for preparing modified polyetheramine used as a toughening agent for tensile-resistant composite fibers, comprising the following steps:

[0055] Step I: Preparation of intermediate I

[0056] Weigh 40g of 3-bromothiophene-2-carbonyl diethyl acetal and 500mL of tetrahydrofuran and place them in a reaction vessel and stir. Cool the reaction vessel to -65℃, slowly add 150mL of n-butyllithium, keep warm and stir for 20min, add 20g of perfluorocyclopentene, restore the reaction vessel to room temperature and stir for 10h, add 5g of p-toluenesulfonic acid, keep warm and react for 10h. After the reaction is complete, wait for the reaction system to cool to room temperature, add 300mL of dichloromethane and 50mL of deionized water to the reaction solution, wash twice, transfer the organic phase to a rotary evaporator at 60℃, and evaporate to a vacuum of 50Pa until no liquid is collected to obtain intermediate I.

[0057] Step II: Preparation of modified polyetheramine

[0058] Weigh out 40g of intermediate I, 10g of 3A molecular sieve and 80g of polyetheramine and place them in a reaction vessel and stir. Add 0.5mol / L acetic acid aqueous solution to pH=6 and react at room temperature for 4h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, and transfer the filtrate to a rotary evaporator at 90℃. Reduce the pressure and evaporate until no liquid is collected to obtain modified polyetheramine.

[0059] Example 2

[0060] This embodiment provides a method for preparing modified polyetheramine used as a toughening agent for tensile-resistant composite fibers, comprising the following steps:

[0061] Step I: Preparation of intermediate I

[0062] Weigh 50g of 3-bromothiophene-2-carbonyl diethyl acetal and 650mL of tetrahydrofuran and place them in a reaction vessel and stir. Cool the reaction vessel to -60℃, slowly add 175mL of n-butyllithium, keep warm and stir for 25min, add 30g of perfluorocyclopentene, restore the reaction vessel to room temperature and stir for 11h, add 7g of p-toluenesulfonic acid, keep warm and react for 11h. After the reaction is complete, wait for the reaction system to cool to room temperature, add 300mL of dichloromethane and 500mL of deionized water to the reaction solution, wash and extract 3 times, transfer the organic phase to a rotary evaporator at 65℃, and evaporate under reduced pressure until no liquid is collected to obtain intermediate I.

[0063] Step II: Preparation of modified polyetheramine

[0064] Weigh out 50g of intermediate I, 15g of 3A molecular sieve and 90g of polyetheramine and place them in a reaction vessel and stir. Add 0.7mol / L acetic acid aqueous solution to pH=6.5 and react at room temperature for 5h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, and transfer the filtrate to a rotary evaporator at 95℃. Reduce the pressure and evaporate until no liquid is collected to obtain modified polyetheramine.

[0065] Example 3

[0066] This embodiment provides a method for preparing modified polyetheramine used as a toughening agent for tensile-resistant composite fibers, comprising the following steps:

[0067] Step I: Preparation of intermediate I

[0068] Weigh 60g of 3-bromothiophene-2-carbonyl diethyl acetal and 800mL of tetrahydrofuran and place them in a reaction vessel and stir. Cool the reaction vessel to -55℃, slowly add 200mL of n-butyllithium, keep warm and stir for 30min, add 40g of perfluorocyclopentene, restore the reaction vessel to room temperature and stir for 12h, add 10g of p-toluenesulfonic acid, keep warm and react for 12h. After the reaction is complete, wait for the reaction system to cool to room temperature, add 300mL of dichloromethane and 500mL of deionized water to the reaction solution, wash and extract 4 times, transfer the organic phase to a rotary evaporator at 70℃, and evaporate under reduced pressure until no liquid is collected to obtain intermediate I.

[0069] Step II: Preparation of modified polyetheramine

[0070] Weigh out 60g of intermediate I, 20g of 3A molecular sieve and 100g of polyetheramine and place them in a reaction vessel and stir. Add 1.0mol / L acetic acid aqueous solution to pH=7 and react at room temperature for 6h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, and transfer the filtrate to a rotary evaporator at 100℃. Reduce the pressure and evaporate until no liquid is collected to obtain modified polyetheramine.

[0071] Example 4

[0072] This embodiment provides a method for preparing a modified toughening agent for tensile-resistant composite fibers, comprising the following steps:

[0073] Step ①: Preparation of prepolymer

[0074] Weigh 150g of the modified polyetheramine prepared in Example 1 and 1000mL of tetrahydrofuran and place them in a reaction vessel under nitrogen atmosphere and stir. Weigh 0.55 times the total molar amount of amino groups in the modified polyetheramine and add it to the reaction solution. Heat the reaction vessel to 30°C and keep it at that temperature for 20h to obtain the prepolymer.

[0075] Step 2: Preparation of modified toughening agent

[0076] Weigh 1000 mL of prepolymer and 20 g of 1,5-diaminopentane and place them in a reaction vessel. Heat the reaction vessel to 45°C and keep it at that temperature for 40 h. After the reaction is complete, transfer the reaction solution to an oven at 50°C and dry it to constant weight to obtain the modified toughening agent.

[0077] Example 5

[0078] This embodiment provides a method for preparing a modified toughening agent for tensile-resistant composite fibers, comprising the following steps:

[0079] Step ①: Preparation of prepolymer

[0080] Weigh 175g of the modified polyetheramine prepared in Example 2 and 1250mL of tetrahydrofuran and place them in a reaction vessel under nitrogen atmosphere and stir. Weigh 0.55 times the total molar amount of amino groups in the modified polyetheramine and add it to the reaction solution. Heat the reaction vessel to 35°C and keep it at that temperature for 22 hours to obtain the prepolymer.

[0081] Step 2: Preparation of modified toughening agent

[0082] Weigh 1100 mL of prepolymer and 30 g of 1,5-diaminopentane and place them in a reaction vessel. Heat the reaction vessel to 50 °C and keep it at that temperature for 44 h. After the reaction is complete, transfer the reaction solution to an oven at 55 °C and dry it to constant weight to obtain the modified toughening agent.

[0083] Example 6

[0084] This embodiment provides a method for preparing a modified toughening agent for tensile-resistant composite fibers, comprising the following steps:

[0085] Step ①: Preparation of prepolymer

[0086] Weigh 200g of the modified polyetheramine prepared in Example 3 and 1500mL of tetrahydrofuran and place them in a reaction vessel under nitrogen atmosphere and stir. Weigh 0.55 times the total molar amount of amino groups in the modified polyetheramine and add it to the reaction solution. Heat the reaction vessel to 40°C and keep it at that temperature for 24 hours to obtain the prepolymer.

[0087] Step 2: Preparation of modified toughening agent

[0088] Weigh 1200 mL of prepolymer and 40 g of 1,5-diaminopentane and place them in a reaction vessel. Heat the reaction vessel to 55 °C and keep it at that temperature for 48 h. After the reaction is complete, transfer the reaction solution to an oven at 60 °C and dry it to constant weight to obtain the modified toughening agent.

[0089] Example 7

[0090] This embodiment provides a method for preparing modified PET for tensile-resistant composite fibers, comprising the following steps:

[0091] Step 1: Preparation of modified graphene

[0092] Weigh 20g of graphene oxide and 1000mL of N-methylpyrrolidone and place them in a reaction vessel. Stir for 15min, add 60g of hydroxyethyl methacrylate and 40g of dihydro-2,5-furandione, stir for 5-10min, add 4g of azobisisobutyronitrile, heat the reaction vessel to 75℃, and keep it at that temperature for 4h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, wash the filter cake twice with ethanol and deionized water, transfer it to an oven at 50℃, and dry it to constant weight to obtain modified graphene.

[0093] Step 2: Preparation of graphene dispersion

[0094] Weigh 30g of modified graphene and 1000mL of ethylene glycol and place them in a reaction vessel. Heat the reaction vessel to 165℃ and keep it at that temperature for 1h to obtain a graphene dispersion.

[0095] Step 3: Preparation of modified PET

[0096] Weigh out 200 mL of graphene dispersion, 400 g of PTA powder, 100 mL of ethylene glycol, and 5 g of antimony trioxide and place them in a sealed reactor under nitrogen atmosphere. Stir the reactor and heat it to 220°C. Maintain the temperature for 2 hours. Drain the water and heat the reactor to 250°C. Evacuate the reactor to a vacuum of 50 Pa and maintain the temperature for 0.5 hours. After the reaction is complete, allow the reaction system to cool to room temperature and depressurize to obtain modified PET.

[0097] Example 8

[0098] This embodiment provides a method for preparing modified PET for tensile-resistant composite fibers, comprising the following steps:

[0099] Step 1: Preparation of modified graphene

[0100] Weigh out 30g of graphene oxide and 1250mL of N-methylpyrrolidone and place them in a reaction vessel. Stir for 20min, add 70g of hydroxyethyl methacrylate and 50g of dihydro-2,5-furandione, stir for 7min, add 6g of azobisisobutyronitrile, heat the reaction vessel to 80℃, and keep it at that temperature for 5h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, wash the filter cake three times with ethanol and deionized water, transfer it to an oven at 55℃, and dry it to constant weight to obtain modified graphene.

[0101] Step 2: Preparation of graphene dispersion

[0102] Weigh 40g of modified graphene and 1100mL of ethylene glycol and place them in a reaction vessel. Heat the reaction vessel to 170℃ and keep it at that temperature for 1.5h to obtain a graphene dispersion.

[0103] Step 3: Preparation of modified PET

[0104] Weigh out 300 mL of graphene dispersion, 500 g of PTA powder, 150 mL of ethylene glycol, and 7 g of antimony trioxide and place them in a sealed reactor under nitrogen atmosphere. Stir the reactor and heat it to 235 °C. Keep the reactor at this temperature for 3 hours. Drain the water and heat the reactor to 260 °C. Evacuate the reactor to a vacuum of 75 Pa and keep the reactor at this temperature for 1 hour. After the reaction is complete, wait for the reaction system to cool to room temperature and release the pressure to obtain modified PET.

[0105] Example 9

[0106] This embodiment provides a method for preparing modified PET for tensile-resistant composite fibers, comprising the following steps:

[0107] Step 1: Preparation of modified graphene

[0108] Weigh out 40g of graphene oxide and 1500mL of N-methylpyrrolidone and place them in a reaction vessel. Stir for 30min, add 80g of hydroxyethyl methacrylate and 60g of dihydro-2,5-furandione, stir for 10min, add 8g of azobisisobutyronitrile, heat the reaction vessel to 85℃, and keep it at that temperature for 6h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, wash the filter cake 4 times with ethanol and deionized water, transfer it to an oven at 60℃, and dry it to constant weight to obtain modified graphene.

[0109] Step 2: Preparation of graphene dispersion

[0110] Weigh 50g of modified graphene and 1200mL of ethylene glycol and place them in a reaction vessel. Heat the reaction vessel to 175℃ and keep it at that temperature for 2 hours to obtain a graphene dispersion.

[0111] Step 3: Preparation of modified PET

[0112] Weigh out 400 mL of graphene dispersion, 600 g of PTA powder, 200 mL of ethylene glycol, and 10 g of antimony trioxide and place them in a sealed reactor under nitrogen atmosphere. Stir the reactor and heat it to 250 °C. Maintain the temperature for 4 hours. Drain the water and heat the reactor to 270 °C. Evacuate the reactor to a vacuum of 100 Pa and maintain the temperature for 1 hour. After the reaction is complete, allow the reaction system to cool to room temperature and depressurize to obtain modified PET.

[0113] Example 10

[0114] This embodiment provides a method for preparing tensile-resistant composite fibers, including the following steps:

[0115] Step 10: Preparation of masterbatch

[0116] Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], diisononyl phthalate and oleamide were mixed evenly in a mass ratio of 1:4:4 to obtain an auxiliary additive for later use.

[0117] Weigh out the following parts by weight: 60 parts of the modified PET prepared in Example 7, 15 parts of the modified toughening agent prepared in Example 4, 6 parts of maleic anhydride grafted polyolefin and 1 part of auxiliary additive, mix them evenly, add them to a twin-screw extruder, melt extrude, and pelletize to obtain masterbatch.

[0118] The twin-screw extruder has four temperature zones from the feed inlet to the discharge outlet: 220℃, 235℃, 245℃ and 250℃, with a screw speed of 100 rpm.

[0119] Step 10: Preparation of composite fibers

[0120] The masterbatch is added to a spinning machine, melt-spun, drawn and shaped to obtain composite fibers;

[0121] The temperature of the feeding zone of the spinning machine is 240℃, the temperature of the melting zone is 255℃, the temperature of the spinning head is 265℃, and the draw ratio is 1:3.

[0122] Example 11

[0123] This embodiment provides a method for preparing tensile-resistant composite fibers, including the following steps:

[0124] Step 10: Preparation of masterbatch

[0125] Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], diisononyl phthalate and oleamide were mixed evenly in a mass ratio of 1:4:4 to obtain an auxiliary additive for later use.

[0126] Weigh out the following parts by weight: 70 parts of the modified PET prepared in Example 8, 17 parts of the modified toughening agent prepared in Example 5, 7 parts of maleic anhydride grafted polyolefin and 2 parts of auxiliary additives, mix them evenly, add them to a twin-screw extruder, melt extrude, and pelletize to obtain masterbatch.

[0127] The twin-screw extruder has four temperature zones from the feed inlet to the discharge outlet: 225℃, 240℃, 250℃ and 255℃, with a screw speed of 150 rpm.

[0128] Step 10: Preparation of composite fibers

[0129] The masterbatch is added to a spinning machine, melt-spun, drawn and shaped to obtain composite fibers;

[0130] The temperature of the feeding zone of the spinning machine is 245℃, the temperature of the melting zone is 260℃, the temperature of the spinning head is 270℃, and the draw ratio is 1:3.5.

[0131] Example 12

[0132] This embodiment provides a method for preparing tensile-resistant composite fibers, including the following steps:

[0133] Step 10: Preparation of masterbatch

[0134] Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], diisononyl phthalate and oleamide were mixed evenly in a mass ratio of 1:4:4 to obtain an auxiliary additive for later use.

[0135] Weigh out the following parts by weight: 80 parts of the modified PET prepared in Example 9, 20 parts of the modified toughening agent prepared in Example 6, 8 parts of maleic anhydride grafted polyolefin and 3 parts of auxiliary additives, mix them evenly, add them to a twin-screw extruder, melt extrude, and pelletize to obtain masterbatch;

[0136] The twin-screw extruder has four temperature zones from the feed inlet to the discharge outlet: 230℃, 235-250℃, 255℃ and 260℃, with a screw speed of 200 rpm.

[0137] Step 10: Preparation of composite fibers

[0138] The masterbatch is added to a spinning machine, melt-spun, drawn and shaped to obtain composite fibers;

[0139] The temperature of the feeding zone of the spinning machine is 250℃, the temperature of the melting zone is 265℃, the temperature of the spinning head is 275℃, and the draw ratio is 1:4.

[0140] Comparative Example 1

[0141] The difference between this comparative example and Example 12 is that, in step ① when preparing the prepolymer, polyetheramine is used in an equal amount to replace the modified polyetheramine.

[0142] Comparative Example 2

[0143] The difference between this comparative example and Example 12 is that the addition of the toughening agent was omitted in step ⒜ when preparing the masterbatch.

[0144] Comparative Example 3

[0145] The difference between this comparative example and Example 12 is that, in step (2) when preparing the graphene dispersion, graphene oxide is used in an equal amount to replace the modified graphene.

[0146] Performance testing:

[0147] The breaking strength and breaking elongation of the composite fibers prepared in Examples 10-12 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 14337-2022 "Test Method for Tensile Properties of Short Chemical Fibers".

[0148] The resistivity of the composite fibers prepared in Examples 10-12 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 14342-2015 "Test Method for Specific Resistivity of Short Chemical Fibers".

[0149] The abrasion resistance of the composite fibers prepared in Examples 10-12 and Comparative Examples 1-3 was tested according to the standard GB / T 21196.3-2007 "Textiles - Martindale Method - Determination of Abrasion Resistance of Fabrics - Part 3: Determination of Mass Loss". The specific data are shown in Table 1.

[0150] Table 1 - Performance Test Data for Each Sample

[0151] Project Group Example 10 Example 11 Example 12 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[Breaking strength / cN·dtex -1 > 5.9 6.3 6.1 3.6 3.0 3.8 Elongation at break / % 94.3 95.3 94.6 54.9 49.3 62.0 <![CDATA[Specific resistance / Ω·cm -1 > <![CDATA[2.3×10 6 ]]> <![CDATA[2.1×10 6 ]]> <![CDATA[2.2×10 6 ]]> <![CDATA[2.4×10 6 ]]> <![CDATA[2.5×10 6 ]]> <![CDATA[2.9×10 6 ]]> <![CDATA[Wear resistance index / times·mg -1 > 378 386 385 261 244 299

[0152] Data Analysis:

[0153] A comparative analysis of the data in Table 1 reveals that the composite fiber prepared in this invention has a tensile strength of 6.3 cN·dtex. -1 The elongation at break is 95.3%, and the resistivity is 2.1 × 10⁻⁶. 6 Meanwhile, the abrasion resistance index is 386 cycles / mg. -1 The data in this invention are superior to those in the comparative example. This invention successfully introduces a perfluorinated functional group and a thiophene ring by forming an aromatic lithium intermediate from 3-bromothiophene-2-carbonyl acetal under the action of n-butyllithium, followed by addition with octafluorocyclopentene, thus obtaining a modified polyetheramine. Furthermore, the modified polyetheramine reacts with diisocyanate to form a prepolymer, which is then chain-extended with 1,5-diaminopentane to form a polyurea-based toughening agent with higher molecular weight and more stable structure. Surface grafting modification of graphene oxide with hydroxyethyl methacrylate and dihydro-2,5-furandione forms a polymer with active double bonds and polar functional groups. Modified graphene is then reacted with ethylene glycol at high temperature to form a stable graphene dispersion. Further, the graphene dispersion undergoes a polycondensation reaction with PTA powder and ethylene glycol under antimony trioxide catalysis to form modified PET with an intramolecular graphene structure. The modified PET, toughening agent, maleic anhydride-grafted polyolefin, and auxiliary additives are mixed evenly and added to a twin-screw extruder for melt extrusion and pelletizing to obtain masterbatch. The masterbatch is then added to a spinning machine for melt spinning, drawing, and shaping to obtain composite fibers. This process not only improves the tensile strength of the composite fibers but also enhances their antistatic and abrasion resistance.

[0154] 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 tensile-resistant composite fiber, characterized in that, It comprises the following components by weight: 60-80 parts modified PET, 15-20 parts modified toughening agent, 6-8 parts maleic anhydride grafted polyolefin and 1-3 parts auxiliary additives. The modified PET is prepared by the following steps: A1. Place modified graphene and ethylene glycol in a reaction vessel, heat the reaction vessel to 165-175℃, and keep the reaction at this temperature for 1-2 hours to obtain a graphene dispersion. A2. Place the graphene dispersion, PTA powder, ethylene glycol, and antimony trioxide in a sealed reactor under nitrogen atmosphere and stir. Heat the reactor to 220-250℃ and maintain the temperature for 2-4 hours. Drain the water, heat the reactor to 250-270℃, evacuate to a vacuum of 50-100 Pa, and maintain the temperature for 0.5-1 hour. Post-process to obtain modified PET. The modified graphene is prepared by placing graphene oxide and N-methylpyrrolidone in a reaction vessel and stirring for 15-30 min. Then, hydroxyethyl methacrylate and dihydro-2,5-furandione are added and stirred for 5-10 min. Azobisisobutyronitrile is added, and the reaction vessel is heated to 75-85℃ and kept at that temperature for 4-6 h. The modified graphene is then obtained after post-treatment. The modified toughening agent is prepared by the following steps: B1. Place the modified polyetheramine and tetrahydrofuran in a reaction vessel under nitrogen atmosphere and stir. Add diphenylmethane diisocyanate. Heat the reaction vessel to 30-40℃ and keep it at this temperature for 20-24 hours to obtain the prepolymer. B2. Place the prepolymer and 1,5-diaminopentane in a reactor, heat the reactor to 45-55℃, keep the reaction at this temperature for 40-48 hours, and then perform post-treatment to obtain the modified toughening agent. The modified polyetheramine is prepared by the following steps: C1. Place 3-bromothiophene-2-carbonyl diethyl acetal and tetrahydrofuran in a reaction vessel and stir. Cool the reaction vessel to -60℃±5℃, slowly add n-butyllithium, keep warm and stir for 20-30 min, add perfluorocyclopentene, restore the reaction vessel to room temperature, stir for 10-12 h, add p-toluenesulfonic acid, keep warm and react for 10-12 h, and then post-process to obtain intermediate I. C2. Place intermediate I, 3A molecular sieve and polyetheramine in a reaction vessel and stir. Add acetic acid aqueous solution to pH 6-7 and react at room temperature for 4-6 hours. Post-treatment yields modified polyetheramine.

2. The tensile-resistant composite fiber according to claim 1, characterized in that, In step A1, the ratio of modified graphene to ethylene glycol is 3-5g:100-120mL; in step A2, the ratio of graphene dispersion, PTA powder, ethylene glycol, and antimony trioxide is 20-40mL:40-60g:10-20mL:0.5-1.0g.

3. The tensile-resistant composite fiber according to claim 1, characterized in that, The ratio of graphene oxide, N-methylpyrrolidone, hydroxyethyl methacrylate, dihydro-2,5-furandione, and azobisisobutyronitrile is 2-4g:100-150mL:6-8g:4-6g:0.4-0.8g.

4. The tensile-resistant composite fiber according to claim 1, characterized in that, In step B1, the ratio of the modified polyetheramine to tetrahydrofuran is 15-20g:100-150mL, and diphenylmethane diisocyanate is added at 0.55 times the total molar amount of the modified polyetheramine amino group; in step B2, the ratio of the prepolymer to 1,5-diaminopentane is 100-120mL:2-4g.

5. The tensile-resistant composite fiber according to claim 1, characterized in that, In step C1, the ratio of 3-bromothiophene-2-carbonyl diethyl acetal, tetrahydrofuran, n-butyllithium, perfluorocyclopentene, and p-toluenesulfonic acid is 4-6 g: 50-80 mL: 15-20 mL: 2-4 g: 0.5-1.0 g; in step C2, the weight ratio of intermediate I, 3A molecular sieve, and polyetheramine is 4-6: 1-2: 8-10, and the concentration of the acetic acid aqueous solution is 0.5-1.0 mol / L.

6. A method for preparing a tensile-resistant composite fiber as described in any one of claims 1-5, characterized in that, The method for preparing the tensile-resistant composite fiber includes the following steps: S1. Mix the modified PET, modified toughening agent, maleic anhydride grafted polyolefin and auxiliary additives evenly, add them to a twin-screw extruder, melt extrude, and pelletize to obtain masterbatch; S2. Add the masterbatch to the spinning machine, melt spin, draw and set to obtain composite fiber.

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