Preparation method of high-performance aramid fiber

Abstract

This invention discloses a method for preparing high-performance aramid fibers, relating to the field of aramid technology. The high-performance aramid fibers are composed of the following components: p-phenylenediamine-terephthaloyl chloride polymer, polyvinylpyrrolidone, antioxidant, ultraviolet stabilizer, and flame retardant. The preparation method includes: dissolving the p-phenylenediamine-terephthaloyl chloride polymer in concentrated sulfuric acid to obtain a spinning solution; adding polyvinylpyrrolidone, antioxidant, ultraviolet stabilizer, flame retardant, and antistatic modifier to the spinning solution, stirring and mixing evenly to obtain a modified spinning solution; extruding the modified spinning solution through a spinneret, stretching it through an air gap, and then solidifying it into filaments in a coagulation bath; washing, drying, and heat-treating the filament bundle to obtain high-performance aramid fibers. The high-performance aramid fibers provided by this invention significantly improve dyeing performance and enhance coating adhesion, solving the processing compatibility problem of aramid fibers in the textile field.

Description

Technical Field

[0001] This invention relates to the field of aramid technology, and in particular to a method for preparing high-performance aramid fibers. Background Technology

[0002] Aramid fibers, with their excellent high strength, heat resistance, and chemical corrosion resistance, are widely used in protective textiles and composite materials. However, during textile processing and application, aramid fibers suffer from low affinity for traditional dyes, leading to uneven coloring and insufficient color fastness, thus increasing post-processing costs. Furthermore, the poor interfacial adhesion between aramid fibers and coating materials makes them prone to peeling, limiting the development of multifunctional composite textiles and hindering their application in fashion fabrics. Therefore, there is an urgent need for a high-performance aramid fiber with strong dyeing properties and adhesive adhesion to solve the processing compatibility issues of aramid fibers in the textile field. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a high-performance aramid fiber and its preparation method, the specific technical solution of which is as follows:

[0004] A high-performance aramid fiber, by weight, comprises the following components: 94-96.5 parts of p-phenylenediamine-terephthaloyl chloride polymer, 2-3 parts of polyvinylpyrrolidone, 0.1-0.5 parts of antioxidant, 0.2-0.8 parts of ultraviolet stabilizer, and 0.3-1.0 parts of flame retardant.

[0005] Preferably:

[0006] The antioxidant is selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate];

[0007] The ultraviolet stabilizer is selected from 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol;

[0008] The flame retardant is selected from triphenyl phosphate.

[0009] The present invention also provides a preparation method for preparing high-performance aramid fibers as described in any one of the above claims, the preparation method comprising the following steps:

[0010] S1. Dissolve the p-phenylenediamine-terephthaloyl chloride polymer in concentrated sulfuric acid to prepare a spinning solution;

[0011] S2. Add polyvinylpyrrolidone, antioxidant, ultraviolet stabilizer and flame retardant to the spinning solution, stir and mix evenly to obtain modified spinning solution;

[0012] S3. The modified spinning solution is extruded through a spinneret, stretched through an air gap, and then solidified into filaments in a coagulation bath;

[0013] S4. The high-performance aramid fiber is obtained by washing, drying and heat treatment of the filament bundle.

[0014] Preferably, the p-phenylenediamine-terephthaloyl chloride polymer is prepared by the following steps:

[0015] a. Under inert gas protection, p-phenylenediamine is dissolved in a polar organic solvent and cooled to -10~0℃;

[0016] b. Slowly add terephthaloyl chloride to p-phenylenediamine at a molar ratio of 1:1, and stir for 1-2 hours to form a polymer solution;

[0017] c. The polymer solution is precipitated, washed, and dried to obtain the p-phenylenediamine-terephthaloyl chloride polymer.

[0018] Preferably:

[0019] In step a, the polar organic solvent is selected from at least one of N,N-dimethylacetamide and N-methylpyrrolidone, and the concentration of p-phenylenediamine in the polar organic solvent is 10-20 wt%.

[0020] In step b, the addition time of terephthaloyl chloride is 20~60 min, the stirring speed is 200~500 rpm, and the reaction temperature is 0~5℃;

[0021] In step c, the solvent used for precipitation is selected from water or methanol, the washing uses deionized water, the washing is performed 3 to 5 times, and the drying temperature is 80 to 120°C.

[0022] Preferably, step S2 specifically includes the following sub-steps:

[0023] S21. Add polyvinylpyrrolidone powder to the spinning solution and stir for 1 to 2 hours at a temperature of 20 to 40°C and a stirring speed of 200 to 500 rpm;

[0024] S22. Dissolve the antioxidant, ultraviolet stabilizer and flame retardant separately in dilute sulfuric acid with a concentration of less than 10 wt% to prepare a mixed solution with a concentration of 0.1~2 wt%.

[0025] S23. The mixed solution is injected into the spinning solution through a static mixer at a pressure of 1.4~10.3 MPa, and stirred and mixed at a temperature of 40~60℃ for 30~60 min to obtain a mixture, ensuring that the viscosity ratio is greater than 500:1;

[0026] S24. Heat the mixture to 70~90℃ and degas it under reduced pressure (3.3~6.7 kPa) for 1~3 hours to obtain the modified spinning solution.

[0027] Preferably:

[0028] In step S1, the concentration of concentrated sulfuric acid is ≥98 wt%, the dissolution temperature is -5~20℃, and the solution is heated to 70~90℃ after dissolution;

[0029] In step S3, the length of the air gap is 0.5~2.5 cm, the coagulation bath uses water as the medium, and the curing temperature is 0~10℃;

[0030] In step S4, the washing process involves washing with dilute alkaline water and deionized water at pH 8-10 for 3-5 times in sequence. The drying temperature is 150-200℃ and the drying time is 5-10 min. The heat treatment temperature is 250-550℃ and the heat treatment time is 1-6 s.

[0031] Preferably, in step S2, an antistatic modifier is also added to the spinning solution, the amount of which is 0.3% to 1.5% of the total mass of the modified spinning solution, and the antistatic modifier is selected from polyimide aerogel or polyurea oligomer.

[0032] Preferably, the antistatic modifier is selected from polyimide aerogel, which is obtained by modifying the polyimide aerogel through the following steps:

[0033] Dissolve γ-aminopropyltriethoxysilane in anhydrous ethanol, adjust the pH to 4-5 with glacial acetic acid, and stir for 20-40 min to obtain hydrolysate.

[0034] Polyimide aerogel nanoparticles were added to the hydrolysate and ultrasonically dispersed for 0.5–1.5 h, followed by stirring for another 1.5–2.5 h.

[0035] Centrifuge, wash with ethanol 2-4 times, wash with deionized water 1-2 times, and vacuum dry at 60-70℃ for 0.5-1.5h to obtain modified polyimide aerogel.

[0036] Preferably, the antistatic modifier is selected from polyurea oligomers, which are prepared by the following steps:

[0037] Under nitrogen protection, diamine is dissolved in DMF, cooled to -3~2℃, and isocyanate is slowly added dropwise over 20~40 min. The mixture is stirred at room temperature for 0.5~1.5 h to form an oligomeric polyurea prepolymer.

[0038] Polyether glycol and dibutyltin dilaurate catalyst were added to the prepolymer and reacted at room temperature for 0.5-1.5 h.

[0039] Precipitate with cold methanol at 0-5℃, filter and wash 2-4 times, and vacuum dry at 40-60℃ for 1-3 hours to obtain polyurea oligomers.

[0040] The high-performance aramid fiber provided by this invention has the following beneficial effects:

[0041] 1. Significantly improves staining performance: PVP provides polar sites, enhancing staining performance and resulting in high color fastness.

[0042] 2. Enhanced coating and adhesive adhesion: Surface PVP enrichment improves surface roughness and chemical bonding, effectively overcoming the risk of peeling caused by surface inertia and enhancing the durability of multifunctional textiles. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0044] This embodiment provides a high-performance aramid fiber, which, by weight, comprises the following components: 94-96.5 parts of p-phenylenediamine-terephthaloyl chloride polymer, 2-3 parts of polyvinylpyrrolidone, 0.1-0.5 parts of antioxidant, 0.2-0.8 parts of ultraviolet stabilizer, and 0.3-1.0 parts of flame retardant.

[0045] The fiber is primarily composed of p-phenylenediamine-terephthaloyl chloride polymer (PPD-T), with polyvinylpyrrolidone (PVP) premixed in the spinning solution as the core modifier, and antioxidants, UV stabilizers, and flame retardants as auxiliary components, achieving in-situ functionalization. During the preparation process using concentrated sulfuric acid spinning solution, the amide groups of PVP form hydrogen bonds with PPD-T. Some PVP is uniformly distributed within the fiber, increasing dye diffusion channels and polar adsorption sites, thus improving dye affinity. Another portion of PVP, due to its surface activity, migrates to the fiber surface in the air gaps of wet spinning, forming an enriched layer, introducing active hydroxyl / amino sites, improving surface roughness and wettability, and promoting chemical bonding with the coating material. Antioxidants inhibit free radical oxidation at high spinning temperatures, maintaining PVP stability; UV stabilizers absorb UV radiation, protecting surface sites from degradation; and flame retardants form a charred layer in the fiber matrix, further enhancing the thermal barrier.

[0046] The high-performance aramid fiber provided in this embodiment has the following beneficial effects:

[0047] 1. Significantly improves staining performance: PVP provides polar sites, enhancing staining performance and resulting in high color fastness.

[0048] 2. Enhanced coating and adhesive adhesion: Surface PVP enrichment improves surface roughness and chemical bonding, effectively overcoming the risk of peeling caused by surface inertia and enhancing the durability of multifunctional textiles.

[0049] Furthermore:

[0050] The antioxidant is selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid].

[0051] The UV stabilizer is selected from 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol.

[0052] The flame retardant is selected from triphenyl phosphate.

[0053] The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010), the UV stabilizer is 2-(2H-benzotriazole-2-yl)-4,6-di-tert-pentylphenol (Tinuvin 327), and the flame retardant is triphenyl phosphate (TPP). The hindered phenolic groups of Irganox 1010 capture free radicals during spinning through steric hindrance, inhibiting the oxidative degradation of PPD-T and PVP segments. The benzotriazole ring of Tinuvin 327 efficiently absorbs 290–400 nm UV photons, converting them into heat energy and preventing photo-oxidation of PVP sites on the surface. The phosphorus-oxygen bonds of TPP decompose during heat treatment to form phosphate complexes, which then complex with aramid groups to form a carbon layer. Through these specific chemical interactions, these components precisely regulate the stability of the spinning solution, surface durability, and thermal barrier at low addition levels.

[0054] This embodiment also provides a preparation method for preparing high-performance aramid fibers as described in any of the above embodiments, the preparation method comprising the following steps:

[0055] S1. Dissolve p-phenylenediamine-terephthaloyl chloride polymer in concentrated sulfuric acid to prepare a spinning solution.

[0056] S2. Add polyvinylpyrrolidone, antioxidant, UV stabilizer and flame retardant to the spinning solution, stir and mix evenly to obtain the modified spinning solution.

[0057] S3. The modified spinning solution is extruded through a spinneret, stretched through an air gap, and then solidified into filaments in a coagulation bath.

[0058] S4. After washing, drying and heat treatment, high-performance aramid fibers are obtained from the filament bundle.

[0059] In step S1, PPD-T forms a liquid crystal phase in concentrated sulfuric acid to ensure high fiber orientation; in step S2, PVP and other components are mixed in and uniformly distributed through hydrogen bonding / electrostatic interaction to induce internal / surface gradient modification; in step S3, air gap stretching promotes PVP migration, and phase separation in the coagulation bath fixes the structure; in step S4, washing neutralizes residual acid, and drying / heat treatment crystallizes sites to improve modulus.

[0060] Furthermore, the p-phenylenediamine-terephthaloyl chloride polymer is prepared by the following steps:

[0061] a. Under inert gas protection, p-phenylenediamine is dissolved in a polar organic solvent and cooled to -10~0℃.

[0062] b. Slowly add terephthaloyl chloride to p-phenylenediamine at a molar ratio of 1:1, and stir for 1-2 hours to form a polymer solution.

[0063] c. The polymer solution is precipitated, washed, and dried to obtain p-phenylenediamine-terephthaloyl chloride polymer.

[0064] In step a, the polar solvent dissolves PPD and cooling inhibits side reactions; in step b, TCl is slowly added dropwise to ensure uniform monomer contact, avoid exothermic self-polymerization, and form high molecular weight linear chains; in step c, precipitation removes solvent residue, washing and purification, and drying stabilizes the structure. PPD-T, as the fiber skeleton, provides high orientation modulus and works synergistically with subsequent PVP modification to avoid fiber strength fluctuations caused by uneven polymerization.

[0065] Furthermore:

[0066] In step a, the polar organic solvent is selected from at least one of N,N-dimethylacetamide and N-methylpyrrolidone, and the concentration of p-phenylenediamine in the polar organic solvent is 10-20 wt%.

[0067] In step b, the addition time of terephthaloyl chloride is 20~60 min, the stirring speed is 200~500 rpm, and the reaction temperature is 0~5℃.

[0068] In step c, the solvent used for precipitation is selected from water or methanol, the washing is done with deionized water, the number of washings is 3 to 5, and the drying temperature is 80 to 120°C.

[0069] Furthermore, step S2 specifically includes the following sub-steps:

[0070] S21. Add polyvinylpyrrolidone powder to the spinning solution and stir for 1 to 2 hours at a temperature of 20 to 40°C and a stirring speed of 200 to 500 rpm.

[0071] S22. Dissolve the antioxidant, ultraviolet stabilizer and flame retardant separately in dilute sulfuric acid with a concentration of less than 10 wt% to prepare a mixed solution with a concentration of 0.1~2 wt%.

[0072] S23. Inject the mixed solution into the spinning solution through a static mixer at a pressure of 1.4~10.3 MPa, and stir and mix at a temperature of 40~60℃ for 30~60 min to obtain a mixture, ensuring that the viscosity ratio is greater than 500:1.

[0073] S24. Heat the mixture to 70~90℃ and degas it under reduced pressure (3.3~6.7 kPa) for 1~3 hours to obtain the modified spinning solution.

[0074] In step S21, PVP is stirred at 20-40℃ to form hydrogen bonds for pre-composite bonding, preventing agglomeration. In step S22, auxiliary components are pre-dissolved in dilute sulfuric acid to improve ionic compatibility. In step S23, high shear force is utilized for distribution through injection at 1.4-10.3 MPa. In step S24, degassing is performed at 70-90℃ under reduced pressure to remove bubbles and stabilize anisotropy. This ensures that the components are uniformly embedded in the spinning solution, guaranteeing PVP migration and functional site formation, thereby avoiding fiber defects caused by uneven mixing.

[0075] Furthermore:

[0076] In step S1, the concentration of concentrated sulfuric acid is ≥98 wt%, the dissolution temperature is -5~20℃, and after dissolution, it is heated to 70~90℃.

[0077] In step S3, the air gap length is 0.5~2.5 cm, the coagulation bath uses water as the medium, and the curing temperature is 0~10℃.

[0078] In step S4, the washing process involves washing with dilute alkaline water and deionized water at pH 8-10 for 3-5 times in sequence. The drying temperature is 150-200℃ and the drying time is 5-10 min. The heat treatment temperature is 250-550℃ and the heat treatment time is 1-6 s.

[0079] Furthermore, in step S2, an antistatic modifier is added to the spinning solution, the amount of which is 0.3% to 1.5% of the total mass of the modified spinning solution. The antistatic modifier is selected from polyimide aerogel or polyurea oligomer.

[0080] In step S23, the porous network of polyimide aerogel is uniformly dispersed in the spinning solution during high-shear injection, forming a micro-buffer layer that reduces fiber stiffness and introduces polar surface sites, promoting charge dissipation. The porous nanostructure of the aerogel forms a "micro-buffer layer" on the fiber surface, similar to an "air cushion." By reducing the macroscopic stiffness of the fiber and increasing air / moisture permeability channels, it achieves soft cushioning and breathability that is skin-friendly. The flexible urea chains of polyurea oligomers are hydrogen-bonded with PVP and preferentially migrate to the surface during air gap stretching in step S3, constructing an elastic interface and inhibiting electrostatic accumulation. These modifiers fix the structure during heat treatment in step S4, preventing phase separation, reducing fiber surface resistance, and avoiding electrostatic accumulation in aramid fibers.

[0081] Furthermore, the antistatic modifier is selected from polyimide aerogel, which is obtained by modifying polyimide aerogel through the following steps:

[0082] Dissolve γ-aminopropyltriethoxysilane in anhydrous ethanol, adjust the pH to 4-5 with glacial acetic acid, and stir for 20-40 min to obtain hydrolysate.

[0083] Polyimide aerogel nanoparticles were added to the hydrolysate and ultrasonically dispersed for 0.5–1.5 h, followed by stirring for another 1.5–2.5 h.

[0084] Centrifuge, wash with ethanol 2-4 times, wash with deionized water 1-2 times, and vacuum dry at 60-70℃ for 0.5-1.5h to obtain modified polyimide aerogel.

[0085] The antistatic modifier is a silane-modified polyimide aerogel, which is surface functionalized through steps (1) KH-550 hydrolysis, (2) ultrasonic dispersion and stirring reaction, and (3) separation and drying. In step (1), hydrolysis at pH 4~5 generates Si-OH active groups. In step (2), ultrasonic / stirring promotes the covalent grafting of amide groups of KH-550 with the polyimide skeleton of the aerogel, introduces acid-loving NH2 sites, and improves sulfuric acid compatibility. In step (3), ethanol / water washing removes unreacted substances, and vacuum drying fixes the nanostructure. The modified aerogel is uniformly dispersed in the S2 injection spinning solution to form a microporous elastic layer, which works synergistically with PVP to reduce static electricity and stiffness. Through this pre-modification, the stable expression of antistatic and soft fibers is achieved, thereby avoiding the problem of poor compatibility of modifiers. The modified aerogel, when incorporated into the spinning solution, preferentially migrates to the fiber surface during wet spinning coagulation in step S3, forming a nano-coating. This layer absorbs mechanical stress, reduces the fiber flexural modulus, and gives the fabric an "elastic rebound" feel when in contact with the skin, reducing indentations and friction damage. The porous structure increases the fabric's moisture evaporation rate and reduces the surface friction coefficient, improving the skin microenvironment and preventing discomfort caused by stuffiness and sweating.

[0086] Furthermore, the antistatic modifier is selected from polyurea oligomers, which are prepared through the following steps:

[0087] Under nitrogen protection, diamine is dissolved in DMF, cooled to -3~2℃, and isocyanate is slowly added dropwise over 20~40 min. The mixture is stirred at room temperature for 0.5~1.5 h to form an oligomeric polyurea prepolymer.

[0088] Polyether glycol and the catalyst dibutyltin dilaurate were added to the prepolymer and reacted at room temperature for 0.5-1.5 h.

[0089] Precipitate with cold methanol at 0-5℃, filter and wash 2-4 times, and vacuum dry at 40-60℃ for 1-3 hours to obtain polyurea oligomers.

[0090] The antistatic modifier is a polyurea oligomer, which is synthesized by low-temperature dropwise addition of prepolymer in step (1), end-group sealing reaction in step (2), and precipitation drying in step (3) to control molecular weight. In step (1), cooling at -3~2℃ and dropwise addition for 20~40 min inhibits chain growth and forms NCO end-group prepolymer; in step (2), PEG end-capping and DBTDL catalysis induce the formation of flexible chains; in step (3), cold methanol precipitation purification and drying at 40~60℃ fix the oligomeric structure. The modified oligomer is compounded with PVP in S2 and enriched on the surface during stretching in S3 to form an elastic antistatic layer. Through this end-capping strategy, overpolymerization in the spinning solution is avoided, ensuring stable flexibility and avoiding the problem of uncontrolled polymer reaction. The flexible urea-ether segments of the oligomeric polyurea are similar to the energy dissipation mechanism of skin collagen, providing dynamic flexibility and solving the "itching" sensation caused by the rigidity of aramid.

[0091] Specific embodiments are provided below. These embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way.

[0092] Example 1

[0093] Under nitrogen protection (flow rate 0.5 L / min), 1.2 kg of N-methylpyrrolidone (NMP) was added to the reactor as a polar organic solvent, followed by the slow addition of 475 g of p-phenylenediamine (PPD). The mixture was stirred at room temperature (300 rpm) for 30 min to dissolve. The mixture was then cooled to -5°C (ice-salt bath). 520 g of terephthaloyl chloride (TCl) was slowly added through a titration funnel over 35 min, with the reaction temperature controlled at 2°C and the stirring speed at 400 rpm. The reaction was continued for 1.5 h to form a viscous polymer solution. The polymer solution was poured into 2.5 kg of ice water to precipitate the solid. The solid was collected by filtration, washed four times with deionized water (1 L of water each time, stirring for 10 min), and dried in a vacuum drying oven at 80°C for 2 h to obtain PPD-T powder.

[0094] In a sealed glass reactor, 2.5 kg of concentrated sulfuric acid (98.5 wt%) was cooled to 0°C, and 475 g of PPD-T powder was slowly added (initial temperature controlled at 10°C, stirring speed 250 rpm), dissolving for 1 h. The mixture was then heated to 80°C and stirred for another 1.5 h to form a spinning solution.

[0095] 12.5 g of PVP powder was added to the spinning solution and stirred at 25°C and 350 rpm for 1.5 h until completely dissolved. 1.5 g of Irganox 1010, 2.5 g of Tinuvin 327, and 3.5 g of TPP were dissolved in 150 g of dilute sulfuric acid (8 wt%) to prepare a mixed solution. This mixed solution was injected into the spinning solution at a pressure of 4.5 MPa using a static mixer and stirred at 45°C for 45 min to obtain a homogeneous mixture. The mixture was heated to 75°C and degassed under reduced pressure (4.5 kPa) for 2 h to obtain the modified spinning solution.

[0096] The modified spinning solution was heated to 82°C and pumped into the spinneret of a wet spinning machine (0.06 mm orifice, 267 holes). It was stretched through a 1.2 cm air gap and then placed in a coagulation bath (water medium, 5°C) to solidify into a filament bundle. The spinning was continued for 2 hours at a winding speed of 450 m / min to obtain a wet filament bundle.

[0097] The fiber bundles were washed three times with a dilute alkaline solution (NaOH) at pH 9 (5 min each time at room temperature), and then washed twice with deionized water (5 min each time at room temperature). They were then dried in an oven at 160°C for 8 min. Finally, they were heat-treated under tension (8 g / den) at 320°C for 3 s (continuous furnace). The fibers were then equilibrated at room temperature (24°C, 55% RH) for 16 h to obtain the finished fiber.

[0098] The fibers are spun into 20 tex yarn. Small fabric samples (0.5 m) are woven on a shuttle loom. 2 ), backup test.

[0099] The sample was stained in a dye bath (basic dye, liquor ratio 1:50, 80℃ for 1 h), then washed / dried. The reflectance was measured using a spectrophotometer (wavelength 450 nm), and K / S = (1-R) ​​was calculated. 2 / 2R.

[0100] Simulated washing (40℃, 30 min), gray card colorimetric assessment of fading / staining (grades 1-5). Light fastness measured after 42 h of xenon lamp exposure.

[0101] The sample was coated with epoxy resin (0.1 mm thick, cured for 24 h), and the peel strength was measured by peeling at 90° (speed 300 mm / min). The average force was recorded.

[0102] The two-electrode method was used to measure the surface resistivity of the sample.

[0103] The KES-FB system measures the feel index, FB1 measures bending (B value, N·m), FB4 measures friction (MIU), and the total THV is calculated.

[0104] The test data is shown in Table 1 below:

[0105]

[0106] Example 2

[0107] Under nitrogen protection (flow rate 0.5 L / min), 1.2 kg of N-methylpyrrolidone (NMP) was added to the reactor as a polar organic solvent, followed by the slow addition of 475 g of p-phenylenediamine (PPD). The mixture was stirred at room temperature (300 rpm) for 30 min to dissolve. The mixture was then cooled to -5°C (ice-salt bath). 520 g of terephthaloyl chloride (TCl) was slowly added through a titration funnel over 35 min, with the reaction temperature controlled at 2°C and the stirring speed at 400 rpm. The reaction was continued for 1.5 h to form a viscous polymer solution. The polymer solution was poured into 2.5 kg of ice water to precipitate the solid. The solid was collected by filtration, washed four times with deionized water (1 L of water each time, stirring for 10 min), and dried in a vacuum drying oven at 80°C for 2 h to obtain PPD-T powder.

[0108] In a sealed glass reactor, 2.5 kg of concentrated sulfuric acid (98.5 wt%) was cooled to 0°C, and 475 g of PPD-T powder was slowly added (initial temperature controlled at 10°C, stirring speed 250 rpm), dissolving for 1 h. The mixture was then heated to 80°C and stirred for another 1.5 h to form a spinning solution.

[0109] 3 g of γ-aminopropyltriethoxysilane (KH-550) was dissolved in 100 g of anhydrous ethanol, and the pH was adjusted to 4.5 with glacial acetic acid. The solution was hydrolyzed by stirring at room temperature for 30 min to obtain the hydrolysate. 5 g of polyimide aerogel nanoparticles were added to the hydrolysate, and the mixture was ultrasonically dispersed (frequency 30 kHz) for 1 h, followed by stirring at room temperature for 2 h. The mixture was then centrifuged (4500 rpm) for 10 min, washed three times with ethanol (50 g ethanol each time), washed once with deionized water, and dried in a vacuum oven at 65 °C for 1 h (vacuum degree 8 kPa) to obtain modified polyimide aerogel powder.

[0110] 12.5 g of PVP powder was added to the spinning solution and stirred at 25°C and 350 rpm for 1.5 h until completely dissolved. 1.5 g of Irganox 1010, 2.5 g of Tinuvin 327, and 3.5 g of TPP were dissolved in 150 g of dilute sulfuric acid (8 wt%) to prepare a mixed solution. 5 g of modified polyimide aerogel powder was added to the above mixed solution and ultrasonically dispersed for 10 min. The mixed solution was injected into the spinning solution at a pressure of 4.5 MPa using a static mixer and stirred at 45°C for 45 min to obtain a homogeneous mixture. The mixture was heated to 75°C and degassed under reduced pressure (4.5 kPa) for 2 h to obtain the modified spinning solution.

[0111] The modified spinning solution was heated to 82°C and pumped into the spinneret of a wet spinning machine (0.06 mm orifice, 267 holes). It was stretched through a 1.2 cm air gap and then placed in a coagulation bath (water medium, 5°C) to solidify into a filament bundle. The spinning was continued for 2 hours at a winding speed of 450 m / min to obtain a wet filament bundle.

[0112] The fiber bundles were washed three times with a dilute alkaline solution (NaOH) at pH 9 (5 min each time at room temperature), and then washed twice with deionized water (5 min each time at room temperature). They were then dried in an oven at 160°C for 8 min. Finally, they were heat-treated under tension (8 g / den) at 320°C for 3 s (continuous furnace). The fibers were then equilibrated at room temperature (24°C, 55% RH) for 16 h to obtain the finished fiber.

[0113] The fibers are spun into 20 tex yarn. Small fabric samples (0.5 m) are woven on a shuttle loom. 2 ), backup test.

[0114] The test items and methods are the same as in Example 1, and the test data are shown in Table 2 below:

[0115]

[0116] Example 3

[0117] Under nitrogen protection (flow rate 0.5 L / min), 1.2 kg of N-methylpyrrolidone (NMP) was added to the reactor as a polar organic solvent, followed by the slow addition of 475 g of p-phenylenediamine (PPD). The mixture was stirred at room temperature (300 rpm) for 30 min to dissolve. The mixture was then cooled to -5°C (ice-salt bath). 520 g of terephthaloyl chloride (TCl) was slowly added through a titration funnel over 35 min, with the reaction temperature controlled at 2°C and the stirring speed at 400 rpm. The reaction was continued for 1.5 h to form a viscous polymer solution. The polymer solution was poured into 2.5 kg of ice water to precipitate the solid. The solid was collected by filtration, washed four times with deionized water (1 L of water each time, stirring for 10 min), and dried in a vacuum drying oven at 80°C for 2 h to obtain PPD-T powder.

[0118] In a sealed glass reactor, 2.5 kg of concentrated sulfuric acid (98.5 wt%) was cooled to 0°C, and 475 g of PPD-T powder was slowly added (initial temperature controlled at 10°C, stirring speed 250 rpm), dissolving for 1 h. The mixture was then heated to 80°C and stirred for another 1.5 h to form a spinning solution.

[0119] Under nitrogen protection (flow rate 0.3 L / min), 10 g of diamine (isofluorodiamine) was added to 50 g of DMF and cooled to 0°C. 17.4 g of isocyanate (TDI) was slowly added dropwise over 30 min, and the mixture was stirred at room temperature for 1 h to form an oligomeric polyurea prepolymer. 2 g of polyether glycol (PEG) and 0.03 g of dibutyltin dilaurate (DBTDL) catalyst were added to the prepolymer, and the reaction was carried out at room temperature for 1 h. The mixture was precipitated with 500 g of cold methanol at 0°C, filtered and washed three times (100 g methanol each time), and dried in a vacuum oven at 50°C for 2 h (vacuum degree 4 kPa) to obtain polyurea oligomer powder.

[0120] 12.5 g of PVP powder was added to the spinning solution and stirred at 25°C and 350 rpm for 1.5 h until completely dissolved. 1.5 g of Irganox 1010, 2.5 g of Tinuvin 327, and 3.5 g of TPP were dissolved in 150 g of dilute sulfuric acid (8 wt%) to prepare a mixed solution. 3 g of polyurea oligomer powder was added to the above mixed solution and stirred for 15 min. The mixed solution was injected into the spinning solution at a pressure of 4.5 MPa using a static mixer and stirred at 45°C for 45 min to obtain a homogeneous mixture. The mixture was heated to 75°C and degassed under reduced pressure (4.5 kPa) for 2 h to obtain the modified spinning solution.

[0121] The modified spinning solution was heated to 82°C and pumped into the spinneret of a wet spinning machine (0.06 mm orifice, 267 holes). It was stretched through a 1.2 cm air gap and then placed in a coagulation bath (water medium, 5°C) to solidify into a filament bundle. The spinning was continued for 2 hours at a winding speed of 450 m / min to obtain a wet filament bundle.

[0122] The fiber bundles were washed three times with a dilute alkaline solution (NaOH) at pH 9 (5 min each time at room temperature), and then washed twice with deionized water (5 min each time at room temperature). They were then dried in an oven at 160°C for 8 min. Finally, they were heat-treated under tension (8 g / den) at 320°C for 3 s (continuous furnace). The fibers were then equilibrated at room temperature (24°C, 55% RH) for 16 h to obtain the finished fiber.

[0123] The fibers are spun into 20 tex yarn. Small fabric samples (0.5 m) are woven on a shuttle loom. 2 ), backup test.

[0124] The test items and methods are the same as in Example 1, and the test data are shown in Table 3 below:

[0125]

[0126] Comparative Example 1

[0127] Under nitrogen protection (flow rate 0.5 L / min), 1.2 kg of N-methylpyrrolidone (NMP) was added to the reactor as a polar organic solvent, followed by the slow addition of 500 g of p-phenylenediamine (PPD). The mixture was stirred at room temperature (300 rpm) for 30 min to dissolve. The mixture was then cooled to -5°C (ice-salt bath). 548 g of terephthaloyl chloride (TCl) was slowly added through a titration funnel over 35 min, with the reaction temperature controlled at 2°C and the stirring speed at 400 rpm. The reaction was continued for 1.5 h to form a viscous polymer solution. The polymer solution was poured into 2.5 kg of ice water to precipitate the solid. The solid was collected by filtration, washed four times with deionized water (1 L of water each time, stirring for 10 min), and dried in a vacuum drying oven at 80°C for 2 h to obtain PPD-T powder.

[0128] In a sealed glass reactor, 2.5 kg of concentrated sulfuric acid (98.5 wt%) was cooled to 0°C, and 500 g of PPD-T powder was slowly added (initial temperature controlled at 10°C, stirring speed 250 rpm), dissolving for 1 h. The mixture was then heated to 80°C and stirred for another 1.5 h to form a spinning solution.

[0129] The spinning solution was heated to 82°C and pumped into the spinneret of a wet spinning machine (0.06 mm orifice, 267 holes). It was stretched through a 1.2 cm air gap and then placed in a coagulation bath (water medium, 5°C) to solidify into a filament bundle. The spinning was continued for 2 hours at a winding speed of 450 m / min to obtain a wet filament bundle.

[0130] The fiber bundles were washed three times with a dilute alkaline solution (NaOH) at pH 9 (5 min each time at room temperature), and then washed twice with deionized water (5 min each time at room temperature). They were then dried in an oven at 160°C for 8 min. Finally, they were heat-treated under tension (8 g / den) at 320°C for 3 s (continuous furnace). The fibers were then equilibrated at room temperature (24°C, 55% RH) for 16 h to obtain the finished fiber.

[0131] The fibers are spun into 20 tex yarn. Small fabric samples (0.5 m) are woven on a shuttle loom. 2 ), backup test.

[0132] The test items and methods are the same as in Example 1, and the test data are shown in Table 4 below:

[0133]

[0134] Comparative Example 2

[0135] Under nitrogen protection (flow rate 0.5 L / min), 1.2 kg of N-methylpyrrolidone (NMP) was added to the reactor as a polar organic solvent, followed by the slow addition of 475 g of p-phenylenediamine (PPD). The mixture was stirred and dissolved at room temperature (300 rpm) for 30 min. The mixture was then cooled to -5°C (ice-salt bath). 520 g of terephthaloyl chloride (TCl) was slowly added through a titration funnel over 35 min, with the reaction temperature controlled at 2°C and the stirring speed at 400 rpm. The reaction was continued for 1.5 h to form a viscous polymer solution. The polymer solution was poured into 2.5 kg of ice water to precipitate the solid. The solid was collected by filtration, washed four times with deionized water (1 L of water each time, stirring for 10 min), and dried in a vacuum drying oven at 80°C for 2 h to obtain PPD-T powder.

[0136] In a sealed glass reactor, 2.5 kg of concentrated sulfuric acid (98.5 wt%) was cooled to 0°C, and 475 g of PPD-T powder was slowly added (initial temperature controlled at 10°C, stirring speed 250 rpm), dissolving for 1 h. The mixture was then heated to 80°C and stirred for another 1.5 h to form a spinning solution.

[0137] 12.5 g of PVP powder was added to the spinning solution and stirred at 25°C and 350 rpm for 1.5 h until completely dissolved. 1.5 g of Irganox 1010, 2.5 g of Tinuvin 327, and 3.5 g of TPP were dissolved in 150 g of dilute sulfuric acid (8 wt%) to prepare a mixed solution. 5 g of polyimide aerogel powder was directly added to the above mixed solution and stirred for 15 min to disperse. The mixed solution was injected into the spinning solution at a pressure of 4.5 MPa using a static mixer and stirred at 45°C for 45 min to obtain a homogeneous mixture. The mixture was heated to 75°C and degassed under reduced pressure (4.5 kPa) for 2 h to obtain the modified spinning solution.

[0138] The modified spinning solution was heated to 82°C and pumped into the spinneret of a wet spinning machine (0.06 mm orifice, 267 holes). It was stretched through a 1.2 cm air gap and then placed in a coagulation bath (water medium, 5°C) to solidify into a filament bundle. The spinning was continued for 2 hours at a winding speed of 450 m / min to obtain a wet filament bundle.

[0139] The fiber bundles were washed three times with a dilute alkaline solution (NaOH) at pH 9 (5 min each time at room temperature), and then washed twice with deionized water (5 min each time at room temperature). They were then dried in an oven at 160°C for 8 min. Finally, they were heat-treated under tension (8 g / den) at 320°C for 3 s (continuous furnace). The fibers were then equilibrated at room temperature (24°C, 55% RH) for 16 h to obtain the finished fiber.

[0140] The fibers are spun into 20 tex yarn. Small fabric samples (0.5 m) are woven on a shuttle loom. 2 ), backup test.

[0141] The test items and methods are the same as in Example 1, and the test data are shown in Table 5 below:

[0142]

[0143] The data above show that this invention addresses the weaknesses of traditional aramid dyeing / adhesion through in-situ modification with PVP, and further optimizes textile suitability with an antistatic modifier. Comparative Example 1 exposes the dyeing / adhesion problems of traditional aramid, while Comparative Example 2 confirms that the modification step with polyimide aerogel is indispensable.

[0144] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing high-performance aramid fiber, characterized in that, The high-performance aramid fiber is made of the following components in parts by weight: 94-96.5 parts of p-phenylenediamine-terephthaloyl chloride polymer, 2-3 parts of polyvinylpyrrolidone, 0.1-0.5 parts of antioxidant, 0.2-0.8 parts of ultraviolet stabilizer, and 0.3-1.0 parts of flame retardant; The preparation method includes the following steps: S1. Dissolve the p-phenylenediamine-terephthaloyl chloride polymer in concentrated sulfuric acid to prepare a spinning solution; S2. Add polyvinylpyrrolidone, antioxidant, ultraviolet stabilizer, flame retardant and antistatic modifier to the spinning solution, stir and mix evenly to obtain modified spinning solution; S3. The modified spinning solution is extruded through a spinneret, stretched through an air gap, and then solidified into filaments in a coagulation bath; S4. The filament bundle is washed, dried and heat-treated to obtain the high-performance aramid fiber; Step S2 specifically includes the following sub-steps: S21. Add polyvinylpyrrolidone powder to the spinning solution and stir for 1 to 2 hours at a temperature of 20 to 40°C and a stirring speed of 200 to 500 rpm. S22. Dissolve the antioxidant, ultraviolet stabilizer, flame retardant and antistatic modifier separately in dilute sulfuric acid with a concentration of less than 10 wt% to prepare a mixed solution with a concentration of 0.1~2 wt%. S23. The mixed solution is injected into the spinning solution through a static mixer at a pressure of 1.4~10.3 MPa, and stirred and mixed at a temperature of 40~60℃ for 30~60 min to obtain a mixture, ensuring that the viscosity ratio is greater than 500:1; S24. Heat the mixture to 70~90℃ and degas it under reduced pressure (3.3~6.7 kPa) for 1~3 hours to obtain the modified spinning solution; The amount of antistatic modifier added in step S2 is 0.3% to 1.5% of the total mass of the modified spinning solution, and the antistatic modifier is selected from polyimide aerogel or polyurea oligomer. The polyimide aerogel was obtained by the following modification steps: Dissolve γ-aminopropyltriethoxysilane in anhydrous ethanol, adjust the pH to 4-5 with glacial acetic acid, and stir for 20-40 min to obtain hydrolysate. Polyimide aerogel nanoparticles were added to the hydrolysate and ultrasonically dispersed for 0.5–1.5 h, followed by stirring for another 1.5–2.5 h. Centrifuge, wash with ethanol 2-4 times, wash with deionized water 1-2 times, and vacuum dry at 60-70℃ for 0.5-1.5h to obtain modified polyimide aerogel; The polyurea oligomer was prepared by the following steps: Under nitrogen protection, diamine is dissolved in DMF, cooled to -3~2℃, and isocyanate is slowly added dropwise over 20~40 min. The mixture is stirred at room temperature for 0.5~1.5 h to form an oligomeric polyurea prepolymer. Polyether glycol and dibutyltin dilaurate catalyst were added to the prepolymer and reacted at room temperature for 0.5-1.5 h. Precipitate with cold methanol at 0-5℃, filter and wash 2-4 times, and vacuum dry at 40-60℃ for 1-3 hours to obtain polyurea oligomers.

2. The method for preparing high-performance aramid fiber according to claim 1, characterized in that: The antioxidant is selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; The ultraviolet stabilizer is selected from 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol; The flame retardant is selected from triphenyl phosphate.

3. The method for preparing high-performance aramid fiber according to claim 1, characterized in that, The p-phenylenediamine-terephthaloyl chloride polymer was prepared by the following steps: a. Under inert gas protection, p-phenylenediamine is dissolved in a polar organic solvent and cooled to -10~0℃; b. Slowly add terephthaloyl chloride to p-phenylenediamine at a molar ratio of 1:1, and stir for 1-2 hours to form a polymer solution; c. The polymer solution is precipitated, washed, and dried to obtain the p-phenylenediamine-terephthaloyl chloride polymer.

4. The method for preparing high-performance aramid fiber according to claim 3, characterized in that: In step a, the polar organic solvent is selected from at least one of N,N-dimethylacetamide and N-methylpyrrolidone, and the concentration of p-phenylenediamine in the polar organic solvent is 10-20 wt%. In step b, the addition time of terephthaloyl chloride is 20~60 min, the stirring speed is 200~500 rpm, and the reaction temperature is 0~5℃; In step c, the solvent used for precipitation is selected from water or methanol, the washing uses deionized water, the washing is performed 3 to 5 times, and the drying temperature is 80 to 120°C.

5. The method for preparing high-performance aramid fiber according to claim 1, characterized in that: In step S1, the concentrated sulfuric acid concentration is ≥98 wt%, the dissolution temperature is -5~20℃, and after dissolution, it is heated to 70~90℃; In step S3, the length of the air gap is 0.5~2.5 cm, the coagulation bath uses water as the medium, and the curing temperature is 0~10℃; In step S4, the washing process involves washing with dilute alkaline water and deionized water at pH 8-10 for 3-5 times in sequence, drying at 150-200℃ for 5-10 minutes, and heat treatment at 250-550℃ for 1-6 seconds.

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