Nano-particle blended flame-retardant yarn based on electrostatic-airflow spraying and preparation method of nano-particle blended flame-retardant yarn

Abstract

The invention discloses a nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying and a preparation method thereof.The preparation method comprises the steps that chlorocyclotriphosphazene (HCCP) and a multi-amino compound react to prepare flame-retardant nanoparticles, the flame-retardant nanoparticles are added into an adhesive according to a certain mass ratio to be evenly dispersed, and the flame-retardant nanoparticles are obtained; the dispersed flame-retardant nano-particles are blended according to the gradient to enter a cotton net to be converged into strips, the strips are dried and crosslinked to obtain flame-retardant cotton strips, and the flame-retardant cotton strips are spun into flame-retardant yarn; by increasing the viscosity of the adhesive, delaying the fluidity of particles among fibers, releasing isocyanate groups and forming covalent bonds with hydroxyl groups of part of alcoholysis PVA and hydroxymethyl cellulose, the thermal movement of molecular chains is balanced, so that the molecular chains are orderly arranged at different stages to form a uniform network structure; compared with the prior art, the mechanical property and the flame retardant property of the prepared yarn are improved.

Description

Technical Field

[0001] This invention relates to a flame-retardant yarn, and more particularly to a nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying and its preparation method. Background Technology

[0002] Apparel materials refer to all materials used in the apparel industry. These materials mainly include natural fiber materials, chemical fiber materials, and functional materials. Natural fiber materials include cotton, linen, silk, wool, and asbestos; chemical fiber materials include regenerated fibers, polyester, polypropylene, acrylic, vinylon, spandex, nylon, and aramid; functional materials refer to materials with specific functions and uses, including waterproof and breathable fabrics, UV-resistant fabrics, thermal insulation fabrics, antibacterial fabrics, odor-resistant fabrics, flame-retardant fabrics, corrosion-resistant fabrics, high-strength fiber fabrics, and bulletproof fabrics.

[0003] Flame-retardant materials for apparel are used to enhance the combustion conditions of clothing through surface modification, blending with functional materials, or finishing processes. This makes the materials less flammable and reduces afterflame and smoldering times. Flame-retardant materials effectively slow the spread of flames and reduce combustion hazards, playing a crucial role in minimizing casualties and property damage in fire accidents. Examples of flame-retardant materials for apparel include: aromatic polyamide fibers (such as para-aramid, meta-aramid, and heterocyclic aramid), polyimide fibers (such as Kermel and P84), polybenzimidazole fibers (PBI), melamine fibers (Basofil), modified polyester, modified acrylic, modified polypropylene, and modified viscose fibers.

[0004] Traditional flame-retardant yarn manufacturing methods mainly achieve this through the blending of non-flame-retardant and flame-retardant fibers. Traditionally, flame-retardant fibers are simply sprayed evenly onto non-flame-retardant fibers, resulting in poor yarn mechanical properties and flame-retardant effects. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a nanoparticle blended flame-retardant yarn based on electrostatic-airflow spray and its preparation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a flame-retardant yarn blended with nanoparticles based on electrostatic-airflow spray and its preparation method, comprising: S1, preparing flame-retardant nanoparticles by reacting hexachlorocyclotriphosphazene and a polyamino compound in a first mass ratio, wherein the first mass ratio is 10-22:30-66;

[0007] S2. Add flame-retardant nanoparticles to the adhesive at a mass ratio of 20-60:100 and disperse them evenly.

[0008] S3. The dispersed flame-retardant nanoparticles are blended into the cotton web in a gradient distribution and then dried and cross-linked to obtain flame-retardant cotton strips.

[0009] S4. Spin the flame-retardant cotton slivers into flame-retardant yarn.

[0010] In a preferred embodiment of the present invention, the specific steps for preparing flame-retardant nanoparticles in step S1 are as follows: hexachlorocyclotriphosphazene and a polyamino compound are added to acetonitrile solvent at a second mass ratio of 10-22:30-66:200-660 to obtain a mixed solution; a weakly basic catalyst is added to the mixed solution, and nitrogen gas is introduced for protection; the reaction is refluxed and stirred at 90-100℃ for 23-24 hours; after the reaction is completed, the precipitate is separated by centrifugation, and the precipitate is washed three times with water and ethanol respectively; the precipitate is dried in a vacuum oven at 50-60℃ for 46-48 hours to obtain flame-retardant nanoparticles.

[0011] In a preferred embodiment of the present invention, the weakly basic catalyst is triethylamine or TEA.

[0012] In a preferred embodiment of the present invention, the particle size of the burning nanoparticles obtained in step S1 is 500 nm to 2 μm.

[0013] In a preferred embodiment of the present invention, the specific steps for uniform dispersion in step S2 are as follows: adding flame-retardant nanoparticles to the adhesive at a mass ratio of 20-60:100 while stirring; and ultrasonically dispersing for 30-60 minutes.

[0014] In a preferred embodiment of the present invention, the preparation step of the adhesive solution is as follows:

[0015] S21. Add a portion of the alcoholyzed PVA, hydroxymethyl cellulose and end-capped isocyanate crosslinking agent to water at a third mass ratio of 5-9:1-5:0.2-0.6:30-70, and stir until completely dissolved to obtain a stirred solution;

[0016] S22. Add fumed silica to the stirring liquid at a mass ratio of 0.5-2:100 and stir for 30 minutes to obtain a thixotropic adhesive.

[0017] S23. Use sodium bicarbonate solution to adjust the pH of the thixotropic adhesive solution to 8-9 to obtain the adhesive solution.

[0018] In a preferred embodiment of the present invention, the specific steps of gradient distribution blending in step S3 are as follows: the cotton fibers are combed using a carding machine to remove impurities and form a uniform cotton web with a thickness of 2-5 mm; the adhesive-flame retardant particle solution is sprayed onto the surface of the cotton web using a dual-air spray-electrostatic atomization integrated device, with the spraying amount distributed in a gradient manner; the sprayed cotton web is evenly wound and gathered to form a continuous cotton sliver with a diameter of 2-4 mm.

[0019] In a preferred embodiment of the present invention, the gradient distribution is 45:30-42:20-40:9-35.

[0020] In a preferred embodiment of the present invention, the specific steps of drying and crosslinking in step S3 are as follows:

[0021] S31. The continuous cotton sliver is dried in the first stage at a temperature of 55℃ for 25 minutes.

[0022] S32. After the first stage of drying, the second stage of drying is carried out at a temperature of 85℃ for 18 minutes.

[0023] S33. After the second stage of drying, a third stage of drying is carried out at a temperature of 125℃ for 12 minutes to obtain flame-retardant cotton strips.

[0024] In a preferred embodiment of the present invention, a nanoparticle blended flame-retardant yarn based on electrostatic-airflow spray is prepared by a method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spray.

[0025] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0026] (1) Flame-retardant nanoparticles were prepared by reacting chlorocyclotriphosphazene (HCCP) with polyamine compounds. The flame-retardant nanoparticles were added to an adhesive at a certain mass ratio and dispersed evenly. The dispersed flame-retardant nanoparticles were then blended into a cotton web in a gradient manner and spun into strips. After drying and crosslinking, flame-retardant cotton strips were obtained. The flame-retardant cotton strips were then spun into flame-retardant yarns. By increasing the viscosity of the adhesive, the fluidity of the particles between the fibers was slowed down. By releasing isocyanate groups and forming covalent bonds with the hydroxyl groups of partially hydrolyzed PVA and hydroxymethyl cellulose, the thermal motion of the molecular chains was balanced, and the molecular chains were arranged in an orderly manner at different stages to form a uniform network structure. Compared with the existing technology, the mechanical properties and flame-retardant properties of the prepared yarns were improved.

[0027] (2) Add a portion of alcoholyzed PVA, hydroxymethyl cellulose and end-capped isocyanate crosslinking agent to water at a mass ratio of 7:3:0.4:50, stir until completely dissolved, and add fumed silica to the stirring liquid at a mass ratio of 1:100, stir for 30 minutes to obtain a thixotropic adhesive; increase the viscosity of the adhesive and delay the flow of particles between fibers; compared with the prior art, reduce the flow of flame retardant particles on the surface of the cotton web and delay the flow. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a flowchart of a preferred embodiment of the present invention;

[0030] Figure 2 This is a flowchart of the adhesive preparation process of the present invention; Detailed Implementation

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0033] Application Overview

[0034] Electrostatic airflow spraying technology can disperse flame retardant particles onto the surface of a fiber cotton web through the combined effects of electric field force and airflow. After being made into yarn, it ensures that the flame retardant is evenly distributed on the yarn surface, allowing the flame retardant to play its full role. It not only has good flame retardant properties, but also maintains the softness and comfort of cotton fibers. It has broad application prospects in the textile industry, especially in the production of flame retardant clothing and home textiles. This yarn can provide effective fire protection without affecting the user experience of the product.

[0035] like Figure 1As shown, a nanoparticle-blended flame-retardant yarn based on electrostatic-airflow spraying and its preparation method are disclosed, comprising:

[0036] S1. Flame-retardant nanoparticles are prepared by reacting hexachlorocyclotriphosphazene (HCCP) and a polyamino compound in a first mass ratio of 10-22:30-66.

[0037] S2. Add flame-retardant nanoparticles to the adhesive at a mass ratio of 20-60:100 and disperse them evenly.

[0038] S3. The dispersed flame-retardant nanoparticles are blended into the cotton web in a gradient distribution and then dried and cross-linked to obtain flame-retardant cotton strips.

[0039] S4. Spin the flame-retardant cotton slivers into flame-retardant yarn.

[0040] In step S1, the specific steps for preparing flame-retardant nanoparticles are as follows: Hexachlorocyclotriphosphazene and a polyamino compound are added to acetonitrile solvent at a second mass ratio of 10-22:30-66:200-660 to obtain a mixed solution; a weakly basic catalyst is added to the mixed solution, and nitrogen gas is introduced for protection; the reaction is refluxed and stirred at 90-100℃ for 23-24 hours; after the reaction, the precipitate is separated by centrifugation, and washed three times with water and ethanol respectively; the precipitate is dried in a vacuum oven at 50-60℃ for 46-48 hours to obtain flame-retardant nanoparticles.

[0041] Specifically, the polyamino compound is one or more of the following polyamino compounds: 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, p-phenylenediamine, m-phenylenediamine, spermidine, spermine, etc.

[0042] The weakly basic catalyst is triethylamine or TEA.

[0043] Specifically, the obtained combustion nanoparticles have a particle size of 500 nm to 2 μm.

[0044] In step S2, the specific steps for uniform dispersion are as follows: add flame-retardant nanoparticles to the adhesive at a mass ratio of 20-60:100 while stirring; ultrasonically disperse for 30-60 minutes to ensure uniform dispersion of particles without agglomeration.

[0045] Specifically, ultrasonic dispersion involves using an ultrasonic disperser with a power of 200-400W and a frequency of 20-40kHz.

[0046] like Figure 1 As shown, the preparation steps of the adhesive solution are as follows:

[0047] S21. Partially hydrolyzed PVA, hydroxymethyl cellulose and end-capped isocyanate crosslinking agent are added to water at a third mass ratio of 5-9:1-5:0.2-0.6:30-70 to obtain a stirred solution;

[0048] S22. Add fumed silica to the stirring liquid at a mass ratio of 0.5-2:100 and stir for 30 minutes to obtain a thixotropic adhesive.

[0049] S23. Use sodium bicarbonate solution to adjust the pH of the thixotropic adhesive solution to 8-9 to obtain the adhesive solution.

[0050] Specifically, the partially hydrolyzed PVA (degree of polymerization 1700-2400) is sourced from Kuraray Co., Ltd. of Japan, the hydroxymethyl cellulose (HEC) is sourced from Dow Chemical, and the end-capping isocyanate crosslinking agent is sodium bisulfite end-capping agent sourced from BASF.

[0051] Specifically, partially hydrolyzed PVA molecules, with their longer chains and the retention of some hydrophobic acetate groups (not fully hydrolyzed), can form a physically entangled network in water, providing a basic adhesive force. The partially hydrolyzed PVA chains bond with hydroxymethyl cellulose via hydrogen bonds, forming a dense three-dimensional network that further enhances the basic adhesive force. The added fumed silica forms a "carousel structure" in water, and upon standing, van der Waals forces create a three-dimensional network, significantly increasing the initial viscosity. Furthermore, the addition of a capped isocyanate crosslinking agent releases isocyanate groups (-NCO) during drying, which react with the hydroxyl groups of partially hydrolyzed PVA and hydroxymethyl cellulose to form covalent bonds (carbamate bonds), thus forming a rigid crosslinked network and increasing the initial viscosity of the prepared adhesive. The formation of both a physically entangled network and a hydrogen-bonded three-dimensional network, along with the synergistic chemical bonding between the physical network and the crosslinking agent, enhances particle fixation and improves viscosity.

[0052] By increasing the initial viscosity of the adhesive, the flowability of particles between fibers can be slowed down, thereby preventing flame-retardant particles in high-density areas from migrating to low-density areas due to capillary action and disrupting the preset gradient.

[0053] In step S3, the specific steps of gradient blending are as follows: the cotton fibers are combed using a carding machine to remove impurities and form a uniform cotton web with a thickness of 2-5mm. The adhesive-flame retardant particle solution is sprayed onto the surface of the cotton web through a dual-air spray-electrostatic atomization integrated device, with the spraying amount distributed according to the gradient. The sprayed cotton web is then evenly wound and gathered to form a continuous cotton sliver with a diameter of 2-4mm.

[0054] Converging into strips specifically refers to winding into strips;

[0055] The specific parameters of the dual-air-spray-electrostatic atomization integrated device are as follows: the voltage is 20-30kV; the gradient distribution can be changed by moving the nozzle of the dual-air-spray-electrostatic atomization integrated device from left to right along the width of the cotton web in a reciprocating motion to ensure that the spray covers the entire width of the cotton web; the nozzle moving frequency is 30-60 times / min; the cotton web conveying speed is set to 0.5-1.5m / min; the distance between the nozzle and the cotton web is maintained at 10-20cm; and the spraying time is usually set to 30-60s / m to match the nozzle moving frequency, ensuring a high surface coating amount and a gradual decrease in the inner layer coating amount.

[0056] Specifically, the gradient distribution is 45:30-42:20-40:9-35.

[0057] In step S3, the specific steps for drying and crosslinking are as follows:

[0058] S31. The continuous cotton sliver is dried in the first stage at a temperature of 55℃ for 25 minutes.

[0059] S32. After the first stage of drying, the second stage of drying is carried out at a temperature of 85℃ for 18 minutes.

[0060] S33. After the second stage of drying, a third stage of drying is carried out at a temperature of 125℃ for 12 minutes to obtain flame-retardant cotton strips.

[0061] Specifically, the drying process involves three stages: a first stage of low-temperature pre-curing, a second stage of medium-temperature cross-linking, and a third stage of high-temperature curing. This gradient configuration helps reduce particle flow and avoids affecting the particle gradient setting on the cotton sliver. Simultaneously, the end-capped isocyanate cross-linking agent releases isocyanate groups (-NCO) during the staged drying process. These groups react with the hydroxyl groups of partially alcoholyzed PVA and hydroxymethyl cellulose to form covalent bonds (carbamate bonds), thereby forming a rigid cross-linked network. This reduces the migration of flame-retardant particles from high-density areas to low-density areas due to capillary action.

[0062] In step S4, the specific steps for spinning flame-retardant cotton sliver into flame-retardant yarn are as follows: the flame-retardant cotton sliver that has been dried and cross-linked is fed evenly into the spinning machine, and the fibers in the cotton sliver are further stretched by the drafting device to make them more uniform and longer. A twist of 200-333 twists / m is applied to the drafted fibers to obtain the final yarn.

[0063] A nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying is prepared by a method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying.

[0064] Hexachlorocyclotriphosphazene was derived from Sigma-Aldrich (H1471), p-phenylenediamine from Aladdin (B123456), acetonitrile solvent from Fisher Scientific (A123456), triethylamine (TEA) from Sigma-Aldrich (T0886), partially alcoholyzed PVA from Kuraray Co., Ltd. (PVA-205), and hydroxymethyl cellulose (HEC) from Dow Chemical (Methocel). TM A4M), the end-capped isocyanate crosslinking agent is derived from BASF ( 2056), fumed silica is derived from Evonik ( 200);

[0065] Example 1

[0066] S1. Hexachlorocyclotriphosphazene (HCCP) and p-phenylenediamine were added to acetonitrile solvent (concentration 99.9%) at a mass ratio of 14:43:400 to obtain a mixed solution; triethylamine (TEA) was added to the mixed solution, and nitrogen gas was introduced for protection; the reaction was stirred under reflux at 100℃ for 24 h; after the reaction was completed, the precipitate was separated by centrifugation, and washed three times with water and ethanol respectively; the precipitate was dried in a vacuum oven at 60℃ for 48 h to obtain flame-retardant nanoparticles;

[0067] S2. Add flame-retardant nanoparticles to the adhesive at a mass ratio of 40:100 while stirring; then ultrasonically disperse for 60 minutes.

[0068] The preparation steps of the adhesive solution are as follows:

[0069] S21. Add a portion of the alcoholyzed PVA, hydroxymethyl cellulose and end-capped isocyanate crosslinking agent to water in a mass ratio of 7:3:0.4:50, and stir until completely dissolved to obtain a stirred solution.

[0070] S22. Add fumed silica to the stirring liquid at a mass ratio of 1:100 and stir for 30 minutes to obtain a thixotropic adhesive.

[0071] S23. Using sodium bicarbonate solution, adjust the pH of the thixotropic adhesive solution to 8 to obtain the adhesive solution;

[0072] S3. Use a carding machine to comb the cotton fibers to remove impurities and form a uniform cotton web with a thickness of 2-5mm. Apply an adhesive-flame retardant granule solution to the surface of the cotton web through a dual-air spray-electrostatic atomization integrated device, with the amount of spraying distributed in a gradient. Then, evenly wind and gather the sprayed cotton web to form a continuous cotton sliver with a diameter of 2-4mm.

[0073] The gradient distribution is 45:35:25:15;

[0074] The specific steps for drying and crosslinking are as follows:

[0075] S31. The continuous cotton sliver is dried in the first stage at a temperature of 55℃ for 25 minutes.

[0076] S32. After the first stage of drying, the second stage of drying is carried out at a temperature of 85℃ for 18 minutes.

[0077] S33. After the second stage of drying, a third stage of drying is carried out at a temperature of 125℃ for 12 minutes to obtain flame-retardant cotton strips.

[0078] S4. The flame-retardant cotton sliver that has been dried and cross-linked is evenly fed into the spinning machine. The fibers in the cotton sliver are further stretched by the drafting device to make them more uniform and longer. A twist of 200-333 twists / m is applied to the drafted fibers to obtain the final yarn.

[0079] Example 2

[0080] The difference is as follows: S21, add part of the alcoholyzed PVA, hydroxymethyl cellulose and end-capped isocyanate crosslinking agent to water in a mass ratio of 5:1:0.2:30, stir until completely dissolved, and obtain a stirred solution;

[0081] S22. Add fumed silica to the stirring liquid at a mass ratio of 0.5:100 and stir for 30 minutes to obtain a thixotropic adhesive.

[0082] The specific steps are as follows: S1. Hexachlorocyclotriphosphazene (HCCP) and p-phenylenediamine are added to acetonitrile solvent at a mass ratio of 14:43:400 to obtain a mixed solution; triethylamine (TEA) is added to the mixed solution, and nitrogen gas is introduced for protection; the reaction is refluxed and stirred at 100℃ for 24h; after the reaction is completed, the precipitate is separated by centrifugation, and the precipitate is washed three times with water and ethanol respectively; the precipitate is dried in a vacuum oven at 60℃ for 48h to obtain flame-retardant nanoparticles.

[0083] S2. Add flame-retardant nanoparticles to the adhesive at a mass ratio of 40:100 while stirring; then ultrasonically disperse for 60 minutes.

[0084] The preparation steps of the adhesive solution are as follows:

[0085] S21. Add a portion of the alcoholyzed PVA, hydroxymethyl cellulose and end-capped isocyanate crosslinking agent to water in a mass ratio of 5:1:0.2:30, and stir until completely dissolved to obtain a stirred solution.

[0086] S22. Add fumed silica to the stirring liquid at a mass ratio of 0.5:100 and stir for 30 minutes to obtain a thixotropic adhesive.

[0087] S23. Using sodium bicarbonate solution, adjust the pH of the thixotropic adhesive solution to 8 to obtain the adhesive solution;

[0088] S3. Use a carding machine to comb the cotton fibers to remove impurities and form a uniform cotton web with a thickness of 2-5mm. Apply an adhesive-flame retardant granule solution to the surface of the cotton web through a dual-air spray-electrostatic atomization integrated device, with the amount of spraying distributed in a gradient. Then, evenly wind and gather the sprayed cotton web to form a continuous cotton sliver with a diameter of 2-4mm.

[0089] The gradient distribution is 45:35:25:15;

[0090] The specific steps for drying and crosslinking are as follows:

[0091] S31. The continuous cotton sliver is dried in the first stage at a temperature of 55℃ for 25 minutes.

[0092] S32. After the first stage of drying, the second stage of drying is carried out at a temperature of 85℃ for 18 minutes.

[0093] S33. After the second stage of drying, a third stage of drying is carried out at a temperature of 125℃ for 12 minutes to obtain flame-retardant cotton strips.

[0094] S4. The flame-retardant cotton sliver that has been dried and cross-linked is evenly fed into the spinning machine. The fibers in the cotton sliver are further stretched by the drafting device to make them more uniform and longer. A twist of 200-333 twists / m is applied to the drafted fibers to obtain the final yarn.

[0095] Example 3

[0096] The difference is as follows: S21, add part of the alcoholyzed PVA, hydroxymethyl cellulose and end-capped isocyanate crosslinking agent to water in a mass ratio of 9:5:0.6:70, stir until completely dissolved, and obtain a stirred solution;

[0097] S22. Add fumed silica to the stirring liquid at a mass ratio of 2:100 and stir for 30 minutes to obtain a thixotropic adhesive.

[0098] The specific steps are as follows: S1. Hexachlorocyclotriphosphazene (HCCP) and p-phenylenediamine are added to acetonitrile solvent at a mass ratio of 14:43:400 to obtain a mixed solution; triethylamine (TEA) is added to the mixed solution, and nitrogen gas is introduced for protection; the reaction is refluxed and stirred at 100℃ for 24h; after the reaction is completed, the precipitate is separated by centrifugation, and the precipitate is washed three times with water and ethanol respectively; the precipitate is dried in a vacuum oven at 60℃ for 48h to obtain flame-retardant nanoparticles.

[0099] S2. Add flame-retardant nanoparticles to the adhesive at a mass ratio of 40:100 while stirring; then ultrasonically disperse for 60 minutes.

[0100] The preparation steps of the adhesive solution are as follows:

[0101] S21. Add a portion of the alcoholyzed PVA, hydroxymethyl cellulose and end-capped isocyanate crosslinking agent to water in a mass ratio of 9:5:0.6:70, and stir until completely dissolved to obtain a stirred solution.

[0102] S22. Add fumed silica to the stirring liquid at a mass ratio of 2:100 and stir for 30 minutes to obtain a thixotropic adhesive.

[0103] S23. Using sodium bicarbonate solution, adjust the pH of the thixotropic adhesive solution to 8 to obtain the adhesive solution;

[0104] S3. Use a carding machine to comb the cotton fibers to remove impurities and form a uniform cotton web with a thickness of 2-5mm. Apply an adhesive-flame retardant granule solution to the surface of the cotton web through a dual-air spray-electrostatic atomization integrated device, with the amount of spraying distributed in a gradient. Then, evenly wind and gather the sprayed cotton web to form a continuous cotton sliver with a diameter of 2-4mm.

[0105] The gradient distribution is 45:35:25:15;

[0106] The specific steps for drying and crosslinking are as follows:

[0107] S31. The continuous cotton sliver is dried in the first stage at a temperature of 55℃ for 25 minutes.

[0108] S32. After the first stage of drying, the second stage of drying is carried out at a temperature of 85℃ for 18 minutes.

[0109] S33. After the second stage of drying, a third stage of drying is carried out at a temperature of 125℃ for 12 minutes to obtain flame-retardant cotton strips.

[0110] S4. The flame-retardant cotton sliver that has been dried and cross-linked is evenly fed into the spinning machine. The fibers in the cotton sliver are further stretched by the drafting device to make them more uniform and longer. A twist of 200-333 twists / m is applied to the drafted fibers to obtain the final yarn.

[0111] Example 4

[0112] The difference lies in the gradient distribution, which is 45:40:35:30.

[0113] The specific steps are as follows: S1. Hexachlorocyclotriphosphazene (HCCP) and p-phenylenediamine are added to acetonitrile solvent at a mass ratio of 14:43:400 to obtain a mixed solution; triethylamine (TEA) is added to the mixed solution, and nitrogen gas is introduced for protection; the reaction is refluxed and stirred at 100℃ for 24h; after the reaction is completed, the precipitate is separated by centrifugation, and the precipitate is washed three times with water and ethanol respectively; the precipitate is dried in a vacuum oven at 60℃ for 48h to obtain flame-retardant nanoparticles.

[0114] S2. Add flame-retardant nanoparticles to the adhesive at a mass ratio of 40:100 while stirring; then ultrasonically disperse for 60 minutes.

[0115] The preparation steps of the adhesive solution are as follows:

[0116] S21. Add a portion of the alcoholyzed PVA, hydroxymethyl cellulose and end-capped isocyanate crosslinking agent to water in a mass ratio of 7:3:0.4:50, and stir until completely dissolved to obtain a stirred solution.

[0117] S22. Add fumed silica to the stirring liquid at a mass ratio of 1:100 and stir for 30 minutes to obtain a thixotropic adhesive.

[0118] S23. Using sodium bicarbonate solution, adjust the pH of the thixotropic adhesive solution to 8 to obtain the adhesive solution;

[0119] S3. Use a carding machine to comb the cotton fibers to remove impurities and form a uniform cotton web with a thickness of 2-5mm. Apply an adhesive-flame retardant granule solution to the surface of the cotton web through a dual-air spray-electrostatic atomization integrated device, with the amount of spraying distributed in a gradient. Then, evenly wind and gather the sprayed cotton web to form a continuous cotton sliver with a diameter of 2-4mm.

[0120] The gradient distribution is 45:40:35:30;

[0121] The specific steps for drying and crosslinking are as follows:

[0122] S31. The continuous cotton sliver is dried in the first stage at a temperature of 55℃ for 25 minutes.

[0123] S32. After the first stage of drying, the second stage of drying is carried out at a temperature of 85℃ for 18 minutes.

[0124] S33. After the second stage of drying, a third stage of drying is carried out at a temperature of 125℃ for 12 minutes to obtain flame-retardant cotton strips.

[0125] S4. The flame-retardant cotton sliver that has been dried and cross-linked is evenly fed into the spinning machine. The fibers in the cotton sliver are further stretched by the drafting device to make them more uniform and longer. A twist of 200-333 twists / m is applied to the drafted fibers to obtain the final yarn.

[0126] The difference in Example 5 is that the gradient distribution is 45:33:21:9;

[0127] The specific steps are as follows: S1. Hexachlorocyclotriphosphazene (HCCP) and p-phenylenediamine are added to acetonitrile solvent at a mass ratio of 14:43:400 to obtain a mixed solution; triethylamine (TEA) is added to the mixed solution, and nitrogen gas is introduced for protection; the reaction is refluxed and stirred at 100℃ for 24h; after the reaction is completed, the precipitate is separated by centrifugation, and the precipitate is washed three times with water and ethanol respectively; the precipitate is dried in a vacuum oven at 60℃ for 48h to obtain flame-retardant nanoparticles.

[0128] S2. Add flame-retardant nanoparticles to the adhesive at a mass ratio of 40:100 while stirring; then ultrasonically disperse for 60 minutes.

[0129] The preparation steps of the adhesive solution are as follows:

[0130] S21. Add a portion of the alcoholyzed PVA, hydroxymethyl cellulose and end-capped isocyanate crosslinking agent to water in a mass ratio of 7:3:0.4:50, and stir until completely dissolved to obtain a stirred solution.

[0131] S22. Add fumed silica to the stirring liquid at a mass ratio of 1:100 and stir for 30 minutes to obtain a thixotropic adhesive.

[0132] S23. Using sodium bicarbonate solution, adjust the pH of the thixotropic adhesive solution to 8 to obtain the adhesive solution;

[0133] S3. Use a carding machine to comb the cotton fibers to remove impurities and form a uniform cotton web with a thickness of 2-5mm. Apply an adhesive-flame retardant granule solution to the surface of the cotton web through a dual-air spray-electrostatic atomization integrated device, with the amount of spraying distributed in a gradient. Then, evenly wind and gather the sprayed cotton web to form a continuous cotton sliver with a diameter of 2-4mm.

[0134] The gradient distribution is 45:33:21:9;

[0135] The specific steps for drying and crosslinking are as follows:

[0136] S31. The continuous cotton sliver is dried in the first stage at a temperature of 55℃ for 25 minutes.

[0137] S32. After the first stage of drying, the second stage of drying is carried out at a temperature of 85℃ for 18 minutes.

[0138] S33. After the second stage of drying, a third stage of drying is carried out at a temperature of 125℃ for 12 minutes to obtain flame-retardant cotton strips.

[0139] S4. The flame-retardant cotton sliver that has been dried and cross-linked is evenly fed into the spinning machine. The fibers in the cotton sliver are further stretched by the drafting device to make them more uniform and longer. A twist of 200-333 twists / m is applied to the drafted fibers to obtain the final yarn.

[0140] Experimental Example 1

[0141] By conducting tests on Example 1 and Comparative Examples 1-4, the following tests were performed: Limiting Oxygen Index (LOI) test: GB / T5454-1997; Afterflame Time test: GB / T5455-2014; Tensile Strength and Elongation Test: GB / T3916-2013.

[0142] Examples 1-5 were placed in a constant temperature and humidity chamber (temperature 40℃, humidity 80%) and left to stand for 24 hours;

[0143] The cross-section of the cotton web was observed by SEM / EDS to determine the amount and rate of surface migration; as shown in Table 1.

[0144] Table 1

[0145]

[0146] According to the data in Table 1, Example 1 has the highest LOI compared to Examples 2-3, with the shortest afterflame and smoldering times. Furthermore, Example 1 exhibits the highest tensile strength and elongation at break, and the lowest migration amount and migration rate, indicating that the yarn prepared in Example 1 has the best flame retardant effect and the highest mechanical properties. This is because Example 1 uses a suitable ratio (7:3) of partially hydrolyzed PVA and hydroxymethyl cellulose, which allows for the formation of sufficient hydrogen bonds, thus constructing a dense and uniform three-dimensional network. This network then forms covalent bonds (carbamate bonds) with the end-capped isocyanate crosslinking agent. This achieves a perfect synergy between physical entanglement and chemical crosslinking, significantly increasing the viscosity of the flame-retardant particles and reducing the flame retardancy in high-density areas. Particles migrate to low-density areas due to capillary action, enhancing flame retardancy and mechanical properties. However, in Example 2, the proportion is too low, and the three-dimensional network structure may not be dense enough to effectively fix the particles. Furthermore, when crosslinking with the end-capped isocyanate crosslinking agent, the proportion of the end-capped isocyanate crosslinking agent is too low, resulting in insufficient crosslinking density. The network structure may be easily destroyed under high temperature or stress. In Example 3, the proportion is too high, and the three-dimensional network is too crowded, leading to an abnormal increase in viscosity, affecting flowability and uniformity. Moreover, when crosslinking with the end-capped isocyanate crosslinking agent, the proportion of the end-capped isocyanate crosslinking agent is too high. Over-crosslinking may cause the network structure to become brittle, reducing its flexibility and adaptability, resulting in a decrease in flame retardancy and mechanical properties.

[0147] According to the data in Table 1, Example 1 has the highest LOI compared to Examples 4-5, with the shortest afterflame time and smoldering time. Example 1 also has the highest tensile strength and elongation at break, and the lowest migration amount and migration rate, indicating that the yarn prepared in Example 1 has the best flame retardant effect and the highest mechanical properties. This is because when the gradient distribution is 45:35:25:15, the partially hydrolyzed PVA and hydroxymethyl cellulose are optimized to form sufficient hydrogen bonds. The three-dimensional network constructed through hydrogen bond optimization forms an effective flame retardant network. The optimized three-dimensional network structure provides sufficient adhesion and fixation in different regions, reducing particle flowability and ensuring uniform distribution of flame retardant particles in the fiber. The flame retardant particles in the high-density area are effectively fixed, while the particles in the low-density area are evenly distributed, reducing particle migration to the low-density area due to capillary action. This increases viscosity, further reducing flame retardant particle migration and preventing fiber embrittlement caused by excessive particle concentration. It also maintains fiber flexibility and strength, thereby improving overall mechanical properties. In contrast, the distribution of flame retardant particles in Example 4 is too uniform, lacking a clear gradient. In high-density areas, the flame-retardant particle density is insufficient to form an effective flame-retardant network, while in low-density areas, the particle density is relatively high, leading to increased particle flow between fibers and a decrease in flame-retardant effect and mechanical properties. In Example 5, the distribution of flame-retardant particles in the fibers is too steep, with excessively high particle density in high-density areas and excessively low particle density in low-density areas. This uneven distribution results in a discontinuous flame-retardant network, increased particle flow between fibers, and a decrease in flame-retardant effect and mechanical properties.

[0148] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying, characterized in that, include: S1. Flame-retardant nanoparticles are prepared by reacting hexachlorocyclotriphosphazene and a polyamino compound in a first mass ratio of 10-22:30-66. S2. Add flame-retardant nanoparticles to the adhesive at a mass ratio of 20-60:100 and disperse them evenly. S3. The dispersed flame-retardant nanoparticles are blended into the cotton web in a gradient distribution and then dried and cross-linked to obtain flame-retardant cotton strips. S4. Spin the flame-retardant cotton slivers into flame-retardant yarn.

2. The method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying according to claim 1, characterized in that: In step S1, the specific steps for preparing flame-retardant nanoparticles are as follows: hexachlorocyclotriphosphazene and a polyamino compound are added to acetonitrile solvent at a second mass ratio of 10-22:30-66:200-660 to obtain a mixed solution; a weakly basic catalyst is added to the mixed solution, and nitrogen gas is introduced for protection; the reaction is refluxed and stirred at 90-100℃ for 23-24h; after the reaction is completed, the precipitate is separated by centrifugation, and washed three times with water and ethanol respectively; the precipitate is dried in a vacuum oven at 50-60℃ for 46-48h to obtain flame-retardant nanoparticles.

3. The method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying according to claim 2, characterized in that: The weakly basic catalyst is triethylamine or TEA.

4. The method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying according to claim 2, characterized in that: The nanoparticles obtained in step S1 have a particle size of 500 nm to 2 μm.

5. The method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying according to claim 1, characterized in that: In step S2, the specific steps for uniform dispersion are as follows: add flame-retardant nanoparticles to the adhesive at a mass ratio of 20-60:100 while stirring; and ultrasonically disperse for 30-60 minutes.

6. The method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying according to claim 5, characterized in that: in, The preparation steps of the adhesive solution are as follows: S21. Add a portion of the alcoholyzed PVA, hydroxymethyl cellulose and end-capped isocyanate crosslinking agent to water at a third mass ratio of 5-9:1-5:0.2-0.6:30-70, and stir until completely dissolved to obtain a stirred solution; S22. Add fumed silica to the stirring liquid at a mass ratio of 0.5-2:100 and stir for 30 minutes to obtain a thixotropic adhesive. S23. Use sodium bicarbonate solution to adjust the pH of the thixotropic adhesive solution to 8-9 to obtain the adhesive solution.

7. The method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying according to claim 1, characterized in that: In step S3, the specific steps of gradient distribution blending are as follows: the cotton fibers are combed using a carding machine to remove impurities and form a uniform cotton web with a thickness of 2-5mm. The adhesive-flame retardant particle solution is sprayed onto the surface of the cotton web through a dual-air spray-electrostatic atomization integrated device, with the spraying amount distributed in a gradient manner. The sprayed cotton web is then evenly wound and gathered to form a continuous cotton sliver with a diameter of 2-4mm.

8. The method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying according to claim 7, characterized in that: The gradient distribution is 45:30-42:20-40:9-35.

9. The method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying according to claim 1, characterized in that: In step S3, the specific steps for drying and crosslinking are as follows: S31. The continuous cotton sliver is dried in the first stage at a temperature of 55℃ for 25 minutes. S32. After the first stage of drying, the second stage of drying is carried out at a temperature of 85℃ for 18 minutes. S33. After the second stage of drying, a third stage of drying is carried out at a temperature of 125℃ for 12 minutes to obtain flame-retardant cotton strips.

10. A nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying, prepared according to the method for preparing nanoparticle blended flame-retardant yarn based on electrostatic-airflow spraying as described in any one of claims 1-9.

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