Flame-retardant high-temperature-resistant fiber and preparation method thereof

Abstract

The invention discloses a flame-retardant high-temperature-resistant fiber and a preparation method thereof, and relates to the technical field of fibers. When the flame-retardant high-temperature-resistant fiber is prepared, 1, 6-hexamethylenediamine, 1, 6-adipic acid, tetrahydrodifuran [3, 4-B: 3 ', 4'-D] furantetraone and a phosphorus-sulfur composite flame retardant are copolymerized to generate a polyamide-polyamide acid solution; 4-aminopyridine and the polyamide-polyamide acid solution are subjected to a reaction, and modified polyamide is prepared; the modified polyamide is subjected to melt spinning, and polyamide fibers are prepared; the preparation method comprises the following steps: pretreating nano titanium dioxide by using 4-bromobutyl trimethoxy silane to prepare modified nano titanium dioxide; mixing the modified nano titanium dioxide and ethanol to prepare a light-resistant antibacterial finishing agent; and carrying out post-treatment on the polyamide fiber by using an anti-light antibacterial finishing agent to prepare the flame-retardant and high-temperature-resistant fiber. The prepared fiber is excellent in comprehensive performance, particularly outstanding in flame retardance and high temperature resistance, and suitable for the fields of special protective clothing, high-temperature filtering materials and the like.

Description

Technical Field

[0001] This invention relates to the field of fibers, specifically to a flame-retardant and high-temperature resistant fiber and its preparation method. Background Technology

[0002] Polyamide fiber is an important synthetic fiber with excellent comprehensive properties. It boasts high strength, good abrasion resistance, and excellent resilience, making it widely used in clothing, home furnishings, industrial applications, and special protective equipment. However, conventional polyamide fibers have a low limiting oxygen index (LOI), making them highly flammable and prone to dripping. They are also susceptible to thermal oxidative degradation at high temperatures, leading to a significant decrease in mechanical properties. This severely limits their application in fields with extremely high requirements for flame retardancy and heat resistance, such as fire fighting, military, and aerospace. Furthermore, polyamide fibers themselves lack UV resistance and antibacterial properties. When used outdoors or in special sanitary environments, they are prone to aging, discoloration, and microbial growth, affecting their lifespan and posing hygiene and safety hazards.

[0003] In recent years, with the increasing demand for special protection, the development of high-performance fibers that integrate multiple functions such as flame retardancy, high temperature resistance, resistance to photoaging, and antibacterial properties has become a research hotspot in the field of materials science. Currently, the modification of polyamides mostly employs physical blending or simple post-treatment methods, which suffer from problems such as poor compatibility between flame retardants and the matrix, limited modified functions, and poor durability. In particular, achieving synergistic effects across multiple functions remains a significant challenge. Therefore, by designing the molecular structure to efficiently introduce flame-retardant elements into the polymer backbone and combining this with surface functionalization techniques, the development of a flame-retardant, high-temperature resistant, multifunctional polyamide fiber with excellent comprehensive performance is of great significance for meeting the application needs of high-end fields and improving safety levels. Summary of the Invention

[0004] The purpose of this invention is to provide a flame-retardant and high-temperature resistant fiber and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A flame-retardant and high-temperature resistant fiber, wherein the flame-retardant and high-temperature resistant fiber is obtained by post-treatment of polyamide fiber with an anti-light and antibacterial finishing agent.

[0006] As an optimization, the polyamide fiber is obtained by melt spinning modified polyamide.

[0007] As an optimization, the modified polyamide is prepared by reacting 4-aminopyridine with a polyamide-polyamic acid solution.

[0008] As an optimization, the polyamide-polyamic acid solution is prepared by copolymerization of 1,6-hexanediamine, 1,6-adipic acid, tetrahydrodifuran[3,4-B:3',4'-D]furantetraone and phosphorus-sulfur composite flame retardant.

[0009] As an optimization, the anti-light and antibacterial finishing agent is formulated from 4-bromobutyltrimethoxysilane-modified nano-titanium dioxide and ethanol.

[0010] A method for preparing flame-retardant and high-temperature resistant fiber includes the following preparation steps: (1) Prepare amino monomer solution and carboxyl monomer solution by mixing 1,6-hexanediamine in amino monomer solution and 1,6-adipic acid in carboxyl monomer solution at a ratio of 1:1. Under nitrogen atmosphere, control the temperature at 0~5℃. Add amino monomer solution to carboxyl monomer solution at a uniform rate within 2~3h and stir at 800rpm. Raise the temperature to 70~80℃ and continue stirring and reacting for 8~12h to obtain polyamide-polyamic acid solution. Mix 4-aminopyridine and polyamide-polyamic acid solution at a mass ratio of 1:(24~26), raise the temperature to 140~150℃ and continue reacting for 4~5h. Dry at 60~70℃ for 12~14h to obtain modified polyamide. (2) Add the modified polyamide to the melt spinning machine, melt spin, cool it initially with a cross-blowing air of 0.2~0.8m / s, and then cool it finally with deionized water to obtain polyamide fiber; (3) Take nano-titanium dioxide and 4-bromobutyltrimethoxysilane in a mass ratio of 1:(19~20), add 2~2.5 times the volume of deionized water of 4-bromobutyltrimethoxysilane, adjust the pH to 3~4 with 1mol / L hydrochloric acid, add the 4-bromobutyltrimethoxysilane, ultrasonically disperse for 15~20min, magnetically stir at 1000rpm for 30~45min, and then ultrasonically disperse for 15min to obtain a mixed solution; add nano-titanium dioxide to the mixed solution, stir at 500rpm at 50℃ for 1~2h, centrifuge for 15min, wash and dry to obtain modified nano-titanium dioxide; (4) Mix modified nano-titanium dioxide and methanol in a mass ratio of 1:(49~50), and ultrasonically disperse for 15 min to prepare an anti-light and antibacterial finishing agent; immerse polyamide fiber in the anti-light and antibacterial finishing agent, react at 60~70℃ for 22~26 h, take it out, and obtain flame-retardant and high-temperature resistant fiber.

[0011] As an optimization, the amino monomer solution in step (1) refers to a solution in which the solute is hexamethylenediamine and phosphorus-sulfur composite flame retardant in a molar ratio of 4:1, and the solvent is N-methylpyrrolidone with a solute content of 20wt%.

[0012] As an optimization, the carboxyl monomer solution in step (1) refers to a solution in which the solute is adipic acid and tetrahydrodifuran[3,4-B:3',4'-D]furantetraone in a molar ratio of 4:1, and the solvent is a solution in which the solute content of N-methylpyrrolidone is 20wt%.

[0013] As an optimization, the preparation method of the phosphorus-sulfur composite flame retardant in step (1) is as follows: Under nitrogen atmosphere, 4,4'-diaminodiphenyl sulfone, triethylamine and acetonitrile are mixed in a mass ratio of 1:(1.2~1.4):(9~10), heated to 40℃, and stirred at 800rpm for 0.5h to prepare a 4,4'-diaminodiphenyl sulfone solution; 0.5~0.6 times the molar amount of 4,4'-diaminodiphenyl sulfone phenylphosphine dichloride is added dropwise to the 4,4'-diaminodiphenyl sulfone solution within 1h, cooled to 25℃, stirred for 3h, then heated to 75℃, reacted for 18h, cooled to room temperature, the solvent is eluted with methyl tert-butyl ether, washed three times with hot acetonitrile, filtered, and dried at 60~70℃ for 2~3h under vacuum to obtain the phosphorus-sulfur composite flame retardant.

[0014] As an optimization, the melt spinning parameters in step (2) are as follows: the spinning temperature is set to 260~280℃, the spinneret diameter is 0.15~0.2mm, the draw ratio is 3~4 times, and the winding speed is 800~1000m / min.

[0015] As an optimization, the nano titanium dioxide in step (3) is of type R-902+, purchased from Dongguan Meidelong Plastics & Chemicals Co., Ltd.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are: In preparing flame-retardant and high-temperature resistant fibers, this invention first synthesizes a composite flame retardant whose molecular backbone contains both phosphorus and sulfur elements through the polycondensation reaction of 4,4'-diaminodiphenyl sulfone and phenylphosphine dichloride. Subsequently, this flame retardant is used as a functional monomer to copolymerize with diamine, diacid, and dianhydride, and then imidized by 4-aminopyridine catalysis to obtain a modified polyamide resin. The resin is then melt-spun into a fiber substrate. Finally, a finishing agent is prepared by modifying nano-titanium dioxide with a silane coupling agent to functionalize the fiber.

[0017] First, a phosphorus-sulfur composite flame retardant was introduced into the polymer molecular backbone. This flame retardant uses phenylphosphoryl dichloride as the key raw material. The phosphorus-chlorine bond in its molecule undergoes a nucleophilic substitution reaction with the amino group of 4,4'-diaminodiphenyl sulfone, successfully introducing phosphorus and sulfone groups into the molecular structure. During combustion, phosphorus promotes fiber cross-linking to form char, creating a dense, expanded char layer that effectively isolates heat and oxygen. Simultaneously, the sulfone-containing structure generates non-combustible gases at high temperatures, diluting the concentration of combustibles and producing a synergistic flame-retardant effect with phosphorus, significantly increasing the limiting oxygen index of the fiber and suppressing dripping, thereby greatly enhancing the flame-retardant performance of the fiber.

[0018] Secondly, by using the aforementioned flame retardants as comonomers in the polymerization process, they are firmly bonded to the polyamide molecular backbone through chemical bonds. This avoids the failure issues caused by migration and precipitation of small-molecule flame retardants during processing and use, thus endowing the fiber with durable and stable flame retardancy. Simultaneously, the introduced rigid benzene ring structure and large side groups effectively increase the rigidity of the molecular chain, restricting chain segment movement and significantly improving the polymer's glass transition temperature and heat distortion temperature, giving the fiber excellent high-temperature resistance.

[0019] Finally, 4-bromobutyltrimethoxysilane was used to modify the surface of nano-titanium dioxide. The silanol groups generated after silane hydrolysis condense with the hydroxyl groups on the surface of nano-titanium dioxide, introducing a long organic chain into the surface of the inorganic particles through strong silicon-oxygen-titanium covalent bonds. The bromine group at the end of this long chain can serve as an active reaction site. During subsequent finishing with polyamide fibers, the bromine group can react with the nitrogen on the pyridine, thereby firmly anchoring the nano-titanium dioxide to the fiber surface in a covalent manner, while simultaneously introducing a quaternary ammonium structure into the fiber. The introduction of nano-titanium dioxide endows the fiber with excellent UV aging resistance, effectively absorbing and scattering ultraviolet rays to prevent molecular chain breakage; at the same time, its inherent photocatalytic antibacterial properties give the fiber a long-lasting antibacterial function. The introduction of quaternary ammonium provides the fiber with antibacterial properties, synergistically enhancing the efficiency and broad-spectrum antibacterial activity in conjunction with nano-titanium dioxide. This surface functionalization finishing technology through chemical bonding solves the problems of easy detachment and poor durability of functional nanoparticles.

[0020] In summary, this invention, through a strategy combining "molecular backbone structure design" and "surface functionalization finishing," successfully produces fibers that integrate multiple functions such as high-efficiency flame retardancy, excellent heat resistance, UV resistance, and antibacterial properties, with all properties remaining stable and durable. These fibers have broad application prospects in fields such as special protective clothing, high-temperature filtration, and advanced decoration. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] To more clearly illustrate the method provided by the present invention, the following embodiments will be described in detail. Example 1:

[0023] A method for preparing flame-retardant and high-temperature resistant fiber includes the following preparation steps: (1) Under nitrogen atmosphere, 4,4'-diaminodiphenyl sulfone, triethylamine and acetonitrile in a mass ratio of 1:1.2:9 were mixed, heated to 40°C, and stirred at 800 rpm for 0.5 h to prepare a 4,4'-diaminodiphenyl sulfone solution; 0.5 times the molar amount of 4,4'-diaminodiphenyl sulfone phenylphosphine dichloride was added dropwise to the 4,4'-diaminodiphenyl sulfone solution over 1 h, cooled to 25°C, stirred for 3 h, then heated to 75°C, reacted for 18 h, cooled to room temperature, eluted with methyl tert-butyl ether, washed three times with hot acetonitrile, filtered, and dried at 60°C for 2 h under vacuum to obtain a phosphorus-sulfur composite flame retardant; (2) Take 1,6-hexanediamine, 1,6-adipic acid, tetrahydrodifuran[3,4-B:3',4'-D]furantetraone, and phosphorus-sulfur composite flame retardant in a molar ratio of 1:1:0.25:0.25. Dissolve the 1,6-hexanediamine and phosphorus-sulfur composite flame retardant in N-methylpyrrolidone at 10 times the mass of 1,6-hexanediamine to prepare an amino monomer solution. Dissolve the 1,6-adipic acid and tetrahydrodifuran[3,4-B:3',4'-D]furantetraone in 1,6-hexanediamine... A carboxyl monomer solution was prepared by adding 10 times the mass of N-methylpyrrolidone to the acid. Under nitrogen atmosphere and with the temperature controlled at 0°C, the amino monomer solution was added to the carboxyl monomer solution at a uniform rate over 2 hours while stirring at 800 rpm. The temperature was then raised to 70°C, and stirring was continued for 8 hours to obtain a polyamide-polyamic acid solution. 4-aminopyridine and the polyamide-polyamic acid solution were mixed at a mass ratio of 1:24, and the mixture was heated to 140°C and reacted for 4 hours. The mixture was then dried at 60°C for 12 hours to obtain the modified polyamide. (3) Add the modified polyamide to the melt spinning machine, set the spinning temperature to 260℃, the spinneret diameter to 0.15mm, the draw ratio to 3 times, the winding speed to 800m / min, and pre-cool it with a cross-blowing air of 0.2m / s, and then finally cool it with deionized water to obtain polyamide fiber; (4) Take nano-titanium dioxide and 4-bromobutyltrimethoxysilane in a mass ratio of 1:19, add deionized water with a volume of 2 times that of 4-bromobutyltrimethoxysilane, adjust the pH to 3 with 1 mol / L hydrochloric acid, add the 4-bromobutyltrimethoxysilane, ultrasonically disperse for 15 min, magnetically stir at 1000 rpm for 30 min, and ultrasonically disperse for another 15 min to obtain a mixed solution; add nano-titanium dioxide to the mixed solution, stir at 500 rpm at 50℃ for 1 h, centrifuge for 15 min, wash 3 times with anhydrous ethanol, and dry at 60℃ for 10 h under nitrogen protection to obtain modified nano-titanium dioxide; (5) Mix modified nano-titanium dioxide and methanol at a mass ratio of 1:49, and ultrasonically disperse for 15 min to prepare an anti-light and antibacterial finishing agent; immerse polyamide fiber in the anti-light and antibacterial finishing agent, react at 60°C for 22 h, take it out, wash it three times with anhydrous ethanol, and dry it at room temperature for 10 h to obtain flame-retardant and high-temperature resistant fiber. Example 2:

[0024] A method for preparing flame-retardant and high-temperature resistant fiber includes the following preparation steps: (1) Under nitrogen atmosphere, 4,4'-diaminodiphenyl sulfone, triethylamine and acetonitrile were mixed in a mass ratio of 1:1.3:9.5, heated to 40°C, and stirred at 800 rpm for 0.5 h to prepare a 4,4'-diaminodiphenyl sulfone solution; 0.55 times the molar amount of 4,4'-diaminodiphenyl sulfone phenylphosphine dichloride was added dropwise to the 4,4'-diaminodiphenyl sulfone solution over 1 h, cooled to 25°C, stirred for 3 h, then heated to 75°C, reacted for 18 h, cooled to room temperature, eluted with methyl tert-butyl ether, washed three times with hot acetonitrile, filtered, and dried at 65°C for 2.5 h under vacuum to obtain a phosphorus-sulfur composite flame retardant; (2) Take 1,6-hexanediamine, 1,6-adipic acid, tetrahydrodifuran[3,4-B:3',4'-D]furantetraone, and phosphorus-sulfur composite flame retardant in a molar ratio of 1:1:0.25:0.25. Dissolve the 1,6-hexanediamine and phosphorus-sulfur composite flame retardant in N-methylpyrrolidone at 10 times the mass of 1,6-hexanediamine to prepare an amino monomer solution. Dissolve the 1,6-adipic acid and tetrahydrodifuran[3,4-B:3',4'-D]furantetraone in 1,6-adipic acid at a molar ratio of 1:1:0.25:0.25. A carboxyl monomer solution was prepared by dissolving 0 times N-methylpyrrolidone. Under nitrogen atmosphere and at a controlled temperature of 2.5℃, the amino monomer solution was added to the carboxyl monomer solution at a uniform rate over 2.5 hours with stirring at 800 rpm. The temperature was then raised to 75℃, and stirring was continued for 10 hours to obtain a polyamide-polyamic acid solution. 4-aminopyridine and the polyamide-polyamic acid solution were mixed at a mass ratio of 1:25, heated to 145℃, and reacted for 4.5 hours. The mixture was then dried at 65℃ for 13 hours to obtain the modified polyamide. (3) Add the modified polyamide into the melt spinning machine, set the spinning temperature to 270℃, the spinneret diameter to 0.175mm, the draw ratio to 3.5 times, the winding speed to 900m / min, and pre-cool it with a cross-blowing air of 0.5m / s, and then finally cool it with deionized water to obtain polyamide fiber. (4) Take nano-titanium dioxide and 4-bromobutyltrimethoxysilane in a mass ratio of 1:19.5, add 2.25 times the volume of deionized water to 4-bromobutyltrimethoxysilane, adjust the pH to 3.5 with 1 mol / L hydrochloric acid, add the 4-bromobutyltrimethoxysilane, disperse by ultrasonication at 80 kHz for 17.5 min, stir magnetically at 1000 rpm for 37.5 min, and then disperse by ultrasonication for 15 min to obtain a mixed solution; add nano-titanium dioxide to the mixed solution, stir at 500 rpm at 50℃ for 1.5 h, centrifuge for 15 min, wash 3 times with anhydrous ethanol, and dry at 60℃ for 11 h under nitrogen protection to obtain modified nano-titanium dioxide; (5) Mix modified nano-titanium dioxide and methanol at a mass ratio of 1:49.5, and ultrasonically disperse for 15 min to prepare an anti-light and antibacterial finishing agent; immerse polyamide fiber in the anti-light and antibacterial finishing agent, react at 65°C for 24 h, take it out, wash it three times with anhydrous ethanol, and dry it at room temperature for 11 h to obtain flame-retardant and high-temperature resistant fiber. Example 3:

[0025] A method for preparing flame-retardant and high-temperature resistant fiber includes the following preparation steps: (1) Under nitrogen atmosphere, 4,4'-diaminodiphenyl sulfone, triethylamine and acetonitrile were mixed in a mass ratio of 1:1.4:10, heated to 40°C, and stirred at 800 rpm for 0.5 h to prepare a 4,4'-diaminodiphenyl sulfone solution; 0.6 times the molar amount of 4,4'-diaminodiphenyl sulfone phenylphosphine dichloride was added dropwise to the 4,4'-diaminodiphenyl sulfone solution over 1 h, cooled to 25°C, stirred for 3 h, then heated to 75°C, reacted for 18 h, cooled to room temperature, eluted with methyl tert-butyl ether, washed three times with hot acetonitrile, filtered, and dried at 70°C for 3 h under vacuum to obtain a phosphorus-sulfur composite flame retardant; (2) Take 1,6-hexanediamine, 1,6-adipic acid, tetrahydrodifuran[3,4-B:3',4'-D]furantetraone and phosphorus-sulfur composite flame retardant in a molar ratio of 1:1:0.25:0.25. Dissolve the 1,6-hexanediamine and phosphorus-sulfur composite flame retardant in N-methylpyrrolidone at 10 times the mass of 1,6-hexanediamine to prepare an amino monomer solution. Dissolve the 1,6-adipic acid and tetrahydrodifuran[3,4-B:3',4'-D]furantetraone in 1,6-adipic acid. A carboxyl monomer solution was prepared by adding 10 times the mass of N-methylpyrrolidone. Under nitrogen atmosphere and at a controlled temperature of 5°C, the amino monomer solution was added to the carboxyl monomer solution at a uniform rate over 3 hours while stirring at 800 rpm. The temperature was then raised to 80°C, and stirring was continued for 12 hours to obtain a polyamide-polyamic acid solution. 4-aminopyridine and the polyamide-polyamic acid solution were mixed at a mass ratio of 1:26, and the mixture was heated to 150°C and reacted for 5 hours. The mixture was then dried at 70°C for 14 hours to obtain the modified polyamide. (3) Add the modified polyamide into the melt spinning machine, set the spinning temperature to 280℃, the spinneret diameter to 0.2mm, the draw ratio to 4 times, the winding speed to 1000m / min, and pre-cool it with a cross-blowing air of 0.8m / s, and then finally cool it with deionized water to obtain polyamide fiber. (4) Take nano-titanium dioxide and 4-bromobutyltrimethoxysilane in a mass ratio of 1:20, add 2.5 times the volume of deionized water to 4-bromobutyltrimethoxysilane, adjust the pH to 4 with 1 mol / L hydrochloric acid, add the 4-bromobutyltrimethoxysilane, disperse by ultrasonication at 80 kHz for 20 min, stir magnetically at 1000 rpm for 45 min, and then disperse by ultrasonication for 15 min to obtain a mixed solution; add nano-titanium dioxide to the mixed solution, stir at 500 rpm at 50 °C for 2 h, centrifuge for 15 min, wash 3 times with anhydrous ethanol, and dry at 60 °C for 12 h under nitrogen protection to obtain modified nano-titanium dioxide; (5) Mix modified nano-titanium dioxide and methanol at a mass ratio of 1:50, and ultrasonically disperse for 15 min to prepare an anti-light and antibacterial finishing agent; immerse polyamide fiber in the anti-light and antibacterial finishing agent, react at 70°C for 26 h, take it out, wash it three times with anhydrous ethanol, and dry it at room temperature for 12 h to obtain flame-retardant and high-temperature resistant fiber.

[0026] Comparative Example 1: A method for preparing flame-retardant and high-temperature resistant fiber includes the following preparation steps: (1) Take 1,6-hexanediamine, 1,6-adipic acid and tetrahydrodifuran[3,4-B:3',4'-D]furantetraone in a molar ratio of 1.25:1:0.25. Dissolve the 1,6-hexanediamine in N-methylpyrrolidone at 10 times the mass of 1,6-hexanediamine to prepare an amino monomer solution. Dissolve the 1,6-adipic acid and tetrahydrodifuran[3,4-B:3',4'-D]furantetraone in N-methylpyrrolidone at 10 times the mass of 1,6-adipic acid. Alkyl ketone was used to prepare a carboxyl monomer solution. Under nitrogen atmosphere and with the temperature controlled at 2.5℃, the amino monomer solution was added to the carboxyl monomer solution at a uniform rate over 2.5 hours while stirring at 800 rpm. The temperature was raised to 75℃, and stirring was continued for 10 hours to obtain a polyamide-polyamic acid solution. 4-Aminopyridine and the polyamide-polyamic acid solution were mixed at a mass ratio of 1:25, heated to 145℃, and reacted for 4.5 hours. The mixture was then dried at 65℃ for 13 hours to obtain the modified polyamide. (2) Add the modified polyamide to the melt spinning machine, set the spinning temperature to 220℃, the spinneret diameter to 0.175mm, the draw ratio to 3.5 times, the winding speed to 900m / min, and pre-cool it with a cross-blowing air of 0.5m / s, and then finally cool it with deionized water to obtain polyamide fiber. (3) Take nano-titanium dioxide and 4-bromobutyltrimethoxysilane in a mass ratio of 1:19.5, add 2.25 times the volume of deionized water to 4-bromobutyltrimethoxysilane, adjust the pH to 3.5 with 1 mol / L hydrochloric acid, add the 4-bromobutyltrimethoxysilane, disperse by ultrasonication at 80 kHz for 17.5 min, stir magnetically at 1000 rpm for 37.5 min, and then disperse by ultrasonication for 15 min to obtain a mixed solution; add nano-titanium dioxide to the mixed solution, stir at 500 rpm at 50℃ for 1.5 h, centrifuge for 15 min, wash 3 times with anhydrous ethanol, and dry at 60℃ for 11 h under nitrogen protection to obtain modified nano-titanium dioxide; (4) Mix modified nano-titanium dioxide and methanol at a mass ratio of 1:49.5, and ultrasonically disperse for 15 min to prepare an anti-light and antibacterial finishing agent; immerse polyamide fiber in the anti-light and antibacterial finishing agent, react at 65°C for 24 h, take it out, wash it three times with anhydrous ethanol, and dry it at room temperature for 11 h to obtain flame-retardant and high-temperature resistant fiber.

[0027] Comparative Example 2: A method for preparing flame-retardant and high-temperature resistant fiber includes the following preparation steps: (1) Under nitrogen atmosphere, 4,4'-diaminodiphenyl sulfone, triethylamine and acetonitrile were mixed in a mass ratio of 1:1.3:9.5, heated to 40°C, and stirred at 800 rpm for 0.5 h to prepare a 4,4'-diaminodiphenyl sulfone solution; 0.55 times the molar amount of 4,4'-diaminodiphenyl sulfone phenylphosphine dichloride was added dropwise to the 4,4'-diaminodiphenyl sulfone solution over 1 h, cooled to 25°C, stirred for 3 h, then heated to 75°C, reacted for 18 h, cooled to room temperature, eluted with methyl tert-butyl ether, washed three times with hot acetonitrile, filtered, and dried at 65°C for 2.5 h under vacuum to obtain a phosphorus-sulfur composite flame retardant; (2) Take 1,6-hexanediamine, 1,6-adipic acid and phosphorus-sulfur composite flame retardant in a molar ratio of 1:1.25:0.25. Dissolve the 1,6-hexanediamine and phosphorus-sulfur composite flame retardant in N-methylpyrrolidone at 10 times the mass of 1,6-hexanediamine to prepare an amino monomer solution. Dissolve the 1,6-adipic acid in N-methylpyrrolidone at 10 times the mass of 1,6-adipic acid to prepare a carboxyl monomer solution. Under nitrogen atmosphere, control the temperature at 2.5℃. Within 2.5h, add the amino monomer solution to the carboxyl monomer solution at a uniform rate and stir at 800rpm. Raise the temperature to 75℃, continue stirring and react for 10h. Raise the temperature to 145℃ to evaporate for 4.5h. Dry at 65℃ for 13h to obtain modified polyamide. (3) Add the modified polyamide into the melt spinning machine, set the spinning temperature to 270℃, the spinneret diameter to 0.175mm, the draw ratio to 3.5 times, the winding speed to 900m / min, and pre-cool it with a cross-blowing air of 0.5m / s, and then finally cool it with deionized water to obtain polyamide fiber. (4) Take nano-titanium dioxide and 4-bromobutyltrimethoxysilane in a mass ratio of 1:19.5, add 2.25 times the volume of deionized water to 4-bromobutyltrimethoxysilane, adjust the pH to 3.5 with 1 mol / L hydrochloric acid, add the 4-bromobutyltrimethoxysilane, disperse by ultrasonication at 80 kHz for 17.5 min, stir magnetically at 1000 rpm for 37.5 min, and then disperse by ultrasonication for 15 min to obtain a mixed solution; add nano-titanium dioxide to the mixed solution, stir at 500 rpm at 50℃ for 1.5 h, centrifuge for 15 min, wash 3 times with anhydrous ethanol, and dry at 60℃ for 11 h under nitrogen protection to obtain modified nano-titanium dioxide; (5) Mix modified nano-titanium dioxide and methanol at a mass ratio of 1:49.5, and ultrasonically disperse for 15 min to prepare an anti-light and antibacterial finishing agent; immerse polyamide fiber in the anti-light and antibacterial finishing agent, react at 65°C for 24 h, take it out, wash it three times with anhydrous ethanol, and dry it at room temperature for 11 h to obtain flame-retardant and high-temperature resistant fiber.

[0028] Comparative Example 3: A method for preparing flame-retardant and high-temperature resistant fiber includes the following preparation steps: (1) Under nitrogen atmosphere, 4,4'-diaminodiphenyl sulfone, triethylamine and acetonitrile were mixed in a mass ratio of 1:1.3:9.5, heated to 40°C, and stirred at 800 rpm for 0.5 h to prepare a 4,4'-diaminodiphenyl sulfone solution; 0.55 times the molar amount of 4,4'-diaminodiphenyl sulfone phenylphosphine dichloride was added dropwise to the 4,4'-diaminodiphenyl sulfone solution over 1 h, cooled to 25°C, stirred for 3 h, then heated to 75°C, reacted for 18 h, cooled to room temperature, eluted with methyl tert-butyl ether, washed three times with hot acetonitrile, filtered, and dried at 65°C for 2.5 h under vacuum to obtain a phosphorus-sulfur composite flame retardant; (2) Take 1,6-hexanediamine, 1,6-adipic acid, tetrahydrodifuran[3,4-B:3',4'-D]furantetraone and phosphorus-sulfur composite flame retardant in a molar ratio of 1:1:0.25:0.25. Dissolve the 1,6-hexanediamine and phosphorus-sulfur composite flame retardant in N-methylpyrrolidone at 10 times the mass of 1,6-hexanediamine to prepare an amino monomer solution. Dissolve the 1,6-adipic acid and tetrahydrodifuran[3,4-B:3',4'-D]furantetraone in 10 times the mass of 1,6-adipic acid. N-methylpyrrolidone was used to prepare a carboxyl monomer solution. Under nitrogen atmosphere and with the temperature controlled at 2.5℃, the amino monomer solution was added to the carboxyl monomer solution at a uniform rate over 2.5 hours while stirring at 800 rpm. The temperature was raised to 75℃, and stirring was continued for 10 hours to obtain a polyamide-polyamic acid solution. N,N-dimethylethylenediamine and the polyamide-polyamic acid solution were mixed at a mass ratio of 1:25, heated to 145℃, and reacted for 4.5 hours. The mixture was then dried at 65℃ for 13 hours to obtain the modified polyamide. (3) Add the modified polyamide into the melt spinning machine, set the spinning temperature to 270℃, the spinneret diameter to 0.175mm, the draw ratio to 3.5 times, the winding speed to 900m / min, and pre-cool it with a cross-blowing air of 0.5m / s, and then finally cool it with deionized water to obtain polyamide fiber. (4) Take nano-titanium dioxide and 4-bromobutyltrimethoxysilane in a mass ratio of 1:19.5, add 2.25 times the volume of deionized water to 4-bromobutyltrimethoxysilane, adjust the pH to 3.5 with 1 mol / L hydrochloric acid, add the 4-bromobutyltrimethoxysilane, disperse by ultrasonication at 80 kHz for 17.5 min, stir magnetically at 1000 rpm for 37.5 min, and then disperse by ultrasonication for 15 min to obtain a mixed solution; add nano-titanium dioxide to the mixed solution, stir at 500 rpm at 50℃ for 1.5 h, centrifuge for 15 min, wash 3 times with anhydrous ethanol, and dry at 60℃ for 11 h under nitrogen protection to obtain modified nano-titanium dioxide; (5) Mix modified nano-titanium dioxide and methanol at a mass ratio of 1:49.5, and ultrasonically disperse for 15 min to prepare an anti-light and antibacterial finishing agent; immerse polyamide fiber in the anti-light and antibacterial finishing agent, react at 65°C for 24 h, take it out, wash it three times with anhydrous ethanol, and dry it at room temperature for 11 h to obtain flame-retardant and high-temperature resistant fiber.

[0029] Comparative Example 4: A method for preparing flame-retardant and high-temperature resistant fiber includes the following preparation steps: (1) Under nitrogen atmosphere, 4,4'-diaminodiphenyl sulfone, triethylamine and acetonitrile were mixed in a mass ratio of 1:1.3:9.5, heated to 40°C, and stirred at 800 rpm for 0.5 h to prepare a 4,4'-diaminodiphenyl sulfone solution; 0.55 times the molar amount of 4,4'-diaminodiphenyl sulfone phenylphosphine dichloride was added dropwise to the 4,4'-diaminodiphenyl sulfone solution over 1 h, cooled to 25°C, stirred for 3 h, then heated to 75°C, reacted for 18 h, cooled to room temperature, eluted with methyl tert-butyl ether, washed three times with hot acetonitrile, filtered, and dried at 65°C for 2.5 h under vacuum to obtain a phosphorus-sulfur composite flame retardant; (2) Take 1,6-hexanediamine, 1,6-adipic acid, tetrahydrodifuran[3,4-B:3',4'-D]furantetraone, and phosphorus-sulfur composite flame retardant in a molar ratio of 1:1:0.25:0.25. Dissolve the 1,6-hexanediamine and phosphorus-sulfur composite flame retardant in N-methylpyrrolidone at 10 times the mass of 1,6-hexanediamine to prepare an amino monomer solution. Dissolve the 1,6-adipic acid and tetrahydrodifuran[3,4-B:3',4'-D]furantetraone in 1,6-adipic acid at a molar ratio of 1:1:0.25:0.25. A carboxyl monomer solution was prepared by dissolving 0 times N-methylpyrrolidone. Under nitrogen atmosphere and at a controlled temperature of 2.5℃, the amino monomer solution was added to the carboxyl monomer solution at a uniform rate over 2.5 hours with stirring at 800 rpm. The temperature was then raised to 75℃, and stirring was continued for 10 hours to obtain a polyamide-polyamic acid solution. 4-aminopyridine and the polyamide-polyamic acid solution were mixed at a mass ratio of 1:25, heated to 145℃, and reacted for 4.5 hours. The mixture was then dried at 65℃ for 13 hours to obtain the modified polyamide. (3) Add the modified polyamide into the melt spinning machine, set the spinning temperature to 270℃, the spinneret diameter to 0.175mm, the draw ratio to 3.5 times, the winding speed to 900m / min, and pre-cool it with a cross-blowing air of 0.5m / s, and then finally cool it with deionized water to obtain polyamide fiber. (4) The polyamide fiber was immersed in 4-bromobutyltrimethoxysilane and reacted at 65°C for 24 hours. The fiber was then removed, washed three times with anhydrous ethanol, and dried at room temperature for 11 hours to obtain flame-retardant and high-temperature resistant fiber.

[0030] Comparative Example 5: A method for preparing flame-retardant and high-temperature resistant fiber includes the following preparation steps: (1) Under nitrogen atmosphere, 4,4'-diaminodiphenyl sulfone, triethylamine and acetonitrile were mixed in a mass ratio of 1:1.3:9.5, heated to 40°C, and stirred at 800 rpm for 0.5 h to prepare a 4,4'-diaminodiphenyl sulfone solution; 0.55 times the molar amount of 4,4'-diaminodiphenyl sulfone phenylphosphine dichloride was added dropwise to the 4,4'-diaminodiphenyl sulfone solution over 1 h, cooled to 25°C, stirred for 3 h, then heated to 75°C, reacted for 18 h, cooled to room temperature, eluted with methyl tert-butyl ether, washed three times with hot acetonitrile, filtered, and dried at 65°C for 2.5 h under vacuum to obtain a phosphorus-sulfur composite flame retardant; (2) Take 1,6-hexanediamine, 1,6-adipic acid, tetrahydrodifuran[3,4-B:3',4'-D]furantetraone, and phosphorus-sulfur composite flame retardant in a molar ratio of 1:1:0.25:0.25. Dissolve the 1,6-hexanediamine and phosphorus-sulfur composite flame retardant in N-methylpyrrolidone at 10 times the mass of 1,6-hexanediamine to prepare an amino monomer solution. Dissolve the 1,6-adipic acid and tetrahydrodifuran[3,4-B:3',4'-D]furantetraone in 1,6-adipic acid at a molar ratio of 1:1:0.25:0.25. A carboxyl monomer solution was prepared by dissolving 0 times N-methylpyrrolidone. Under nitrogen atmosphere and at a controlled temperature of 2.5℃, the amino monomer solution was added to the carboxyl monomer solution at a uniform rate over 2.5 hours with stirring at 800 rpm. The temperature was then raised to 75℃, and stirring was continued for 10 hours to obtain a polyamide-polyamic acid solution. 4-aminopyridine and the polyamide-polyamic acid solution were mixed at a mass ratio of 1:25, heated to 145℃, and reacted for 4.5 hours. The mixture was then dried at 65℃ for 13 hours to obtain the modified polyamide. (3) Add the modified polyamide to the melt spinning machine, set the spinning temperature to 270℃, the spinneret diameter to 0.175mm, the draw ratio to 3.5 times, the winding speed to 900m / min, and pre-cool it with a cross-blowing air of 0.5m / s, and then finally cool it with deionized water to obtain flame-retardant and high-temperature resistant fiber.

[0031] Experimental Example 1 Flame retardant performance testing Test method: The limiting oxygen index of the examples and comparative examples was tested using an oxygen index instrument according to GB / T5454 "Test for Burning Performance of Textiles - Oxygen Index Method". The results are shown in Table 1.

[0032] Table 1 Limiting oxygen index (%) Limiting oxygen index (%) Example 1 34.3 Comparative Example 1 21.2 Example 2 34.7 Comparative Example 2 30.5 Example 3 35.0 Comparative Example 3 29.8 Comparative Example 4 28.7 Comparative Example 5 30.8 As shown in the table above, the limiting oxygen index of Examples 1-3 is significantly higher than that of Comparative Example 1. In Examples 1-3, phosphorus-sulfur composite flame retardants are involved in copolymerization on the fiber backbone. During combustion, phosphorus can promote the cross-linking of fibers into char, forming a dense expanded char layer that effectively isolates heat and oxygen. At the same time, the sulfone-containing structure can generate non-combustible gas at high temperatures, diluting the concentration of combustibles and producing a synergistic flame retardant effect with phosphorus, significantly improving the limiting oxygen index of the fiber and inhibiting dripping, thereby greatly improving the inherent flame retardant performance of the fiber.

[0033] Experimental Example 2 High temperature resistance test Test method: Thermogravimetric analysis was performed on Examples 1-3 and Comparative Examples 1-5 under a nitrogen atmosphere using a thermogravimetric analyzer. The heating range was room temperature to 800℃, and the heating rate was 10℃ / min. 2 mg of each of Examples 1-3 and Comparative Examples 1-5 was used as a sample. The 5% thermal decomposition temperature (t) of the fibers was tested. 5% The results are shown in Table 2.

[0034] Table 2 <![CDATA[t 5% (℃)]]> <![CDATA[t 5% (℃)]]> Example 1 425 Comparative Example 1 307 Example 2 432 Comparative Example 2 341 Example 3 440 Comparative Example 3 348 Comparative Example 4 414 Comparative Example 5 426 As can be seen from the table above, the 5% thermal decomposition temperature of Examples 1-3 is significantly higher than that of Comparative Examples 1-3. In the process of polymerizing fibers, rigid benzene rings or imide rings were added in Examples 1-3. These two structures have high bond energy, resonance stability energy and structural rigidity, which provide the fibers with high temperature resistance.

[0035] Experimental Example 3 Antibacterial performance test Test method: The antibacterial rate was calculated by comparing the number of Escherichia coli colonies after 16 hours of incubation on agar medium using the shaking method (GB / T 20944.3). The antibacterial performance of the examples and comparative examples was then analyzed. The results are shown in Table 3.

[0036] Table 3 Antibacterial rate (%) Antibacterial rate (%) Example 1 98.5 Comparative Example 1 98.4 Example 2 99.2 Comparative Example 2 70.7 Example 3 99.1 Comparative Example 3 97.9 Comparative Example 4 80.6 Comparative Example 5 43.2 Examples 1-3 exhibited high antibacterial rates, while Comparative Examples 2, 4, and 5 showed lower antibacterial rates, with Comparative Example 5 showing the lowest. Examples 1-3 contained quaternary ammonium structures and nano-titanium dioxide particles, while Comparative Example 2 lacked quaternary ammonium structures, Comparative Example 4 lacked nano-titanium dioxide particles, and Comparative Example 5 lacked both quaternary ammonium structures and titanium dioxide particles. Quaternary ammonium can achieve an antibacterial effect by disrupting cell structures through electrostatic adsorption, while titanium dioxide can generate reactive oxygen species through photocatalysis, reacting with cells to achieve an antibacterial effect. The simultaneous presence of both can improve the efficiency and broad-spectrum antibacterial activity.

[0037] Test Example 4 Lightfastness test: Test method: Referring to GB / T3916-2013, the breaking strength A of the examples and comparative examples was tested using a YG061F electronic single yarn tensile tester; the examples and comparative examples were irradiated with a xenon lamp for 10 days, and the breaking strength B of the examples and comparative examples after ultraviolet light treatment was tested. The rate of change of breaking strength of the examples and comparative examples before and after ultraviolet aging treatment was calculated; the rate of change of breaking strength = (AB) / A × 100%. The results are shown in Table 4.

[0038] Table 4 Fracture strength change rate (%) Fracture strength change rate (%) Example 1 5.5 Comparative Example 1 5.8 Example 2 5.9 Comparative Example 2 6.3 Example 3 6.4 Comparative Example 3 6.7 Comparative Example 4 29.3 Comparative Example 5 32.5 As shown in the table, Examples 1-3 exhibited a lower rate of change in breaking strength after accelerated photoaging compared to Comparative Examples 4-5, indicating that Examples 1-3 possess stronger anti-light properties compared to Comparative Examples 4-5. In the fabrication process of Examples 1-3, anti-light and antibacterial finishing agents were prepared using silane coupling agents and nano-titanium dioxide, and the fibers underwent post-treatment. The nano-titanium dioxide particles absorb light energy, thus protecting the fibers from photo-oxidation.

[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A flame-retardant and high-temperature resistant fiber, characterized in that, The flame-retardant and high-temperature resistant fiber is obtained by post-treatment of polyamide fiber with an anti-light and antibacterial finishing agent.

2. The flame-retardant and high-temperature resistant fiber according to claim 1, characterized in that, The polyamide fiber is obtained by melt spinning modified polyamide.

3. The flame-retardant and high-temperature resistant fiber according to claim 2, characterized in that, The modified polyamide is prepared by reacting 4-aminopyridine with a polyamide-polyamic acid solution.

4. The flame-retardant and high-temperature resistant fiber according to claim 3, characterized in that, The polyamide-polyamic acid solution is prepared by copolymerization of 1,6-hexanediamine, 1,6-adipic acid, tetrahydrodifuran[3,4-B:3',4'-D]furantetraone and phosphorus-sulfur composite flame retardant.

5. The flame-retardant and high-temperature resistant fiber according to claim 1, characterized in that, The anti-light and antibacterial finishing agent is formulated from 4-bromobutyltrimethoxysilane-modified nano-titanium dioxide and ethanol.

6. A method for preparing flame-retardant and high-temperature resistant fibers, characterized in that, The preparation steps include the following: (1) Prepare amino monomer solution and carboxyl monomer solution by mixing 1,6-hexanediamine in amino monomer solution and 1,6-adipic acid in carboxyl monomer solution at a ratio of 1:

1. Under nitrogen atmosphere, control the temperature at 0~5℃. Add amino monomer solution to carboxyl monomer solution at a uniform rate within 2~3h and stir at 800rpm. Raise the temperature to 70~80℃ and continue stirring and reacting for 8~12h to obtain polyamide-polyamic acid solution. Mix 4-aminopyridine and polyamide-polyamic acid solution at a mass ratio of 1:(24~26), raise the temperature to 140~150℃ and continue reacting for 4~5h. Dry at 60~70℃ for 12~14h to obtain modified polyamide. (2) Add the modified polyamide to a melt spinning machine, melt spin it, then cool it initially with a cross-blowing air of 0.2~0.8m / s, and finally cool it with deionized water to obtain polyamide fiber; (3) Take nano-titanium dioxide and 4-bromobutyltrimethoxysilane in a mass ratio of 1:(19~20), add 2~2.5 times the volume of deionized water of 4-bromobutyltrimethoxysilane, adjust the pH to 3~4 with 1mol / L hydrochloric acid, add the 4-bromobutyltrimethoxysilane, ultrasonically disperse for 15~20min, magnetically stir at 1000rpm for 30~45min, and then ultrasonically disperse for 15min to obtain a mixed solution; add nano-titanium dioxide to the mixed solution, stir at 500rpm at 50℃ for 1~2h, centrifuge for 15min, wash and dry to obtain modified nano-titanium dioxide; (4) Mix modified nano-titanium dioxide and methanol in a mass ratio of 1:(49~50), and ultrasonically disperse for 15 min to prepare an anti-light and antibacterial finishing agent; immerse polyamide fiber in the anti-light and antibacterial finishing agent, react at 60~70℃ for 22~26 h, take it out, and obtain flame-retardant and high-temperature resistant fiber.

7. The method for preparing a flame-retardant and high-temperature resistant fiber according to claim 6, characterized in that, The amino monomer solution mentioned in step (1) refers to a solution in which the solute is hexamethylenediamine and phosphorus-sulfur composite flame retardant in a molar ratio of 4:1, and the solvent is N-methylpyrrolidone with a solute content of 20 wt%.

8. The method for preparing a flame-retardant and high-temperature resistant fiber according to claim 6, characterized in that, The carboxyl monomer solution mentioned in step (1) refers to a solution in which the solutes are adipic acid and tetrahydrodifuran[3,4-B:3',4'-D]furantetraone in a molar ratio of 4:1, and the solvent is N-methylpyrrolidone with a solute content of 20wt%.

9. The method for preparing a flame-retardant and high-temperature resistant fiber according to claim 7, characterized in that, The preparation method of the phosphorus-sulfur composite flame retardant in step (1) is as follows: Under nitrogen atmosphere, 4,4'-diaminodiphenyl sulfone, triethylamine and acetonitrile are mixed in a mass ratio of 1:(1.2~1.4):(9~10), heated to 40℃, and stirred at 800rpm for 0.5h to prepare a 4,4'-diaminodiphenyl sulfone solution; 0.5~0.6 times the molar amount of 4,4'-diaminodiphenyl sulfone phenylphosphine dichloride is added dropwise to the 4,4'-diaminodiphenyl sulfone solution within 1h, cooled to 25℃, stirred for 3h, then heated to 75℃, reacted for 18h, cooled to room temperature, the solvent is eluted with methyl tert-butyl ether, washed three times with hot acetonitrile, filtered, and dried at 60~70℃ for 2~3h under vacuum to obtain the phosphorus-sulfur composite flame retardant.

10. The method for preparing a flame-retardant and high-temperature resistant fiber according to claim 6, characterized in that, The melt spinning parameters in step (2) are as follows: the spinning temperature is set to 260~280℃, the spinneret diameter is 0.15~0.2mm, the draw ratio is 3~4 times, and the winding speed is 800~1000m / min.