A method for preparing metal chelate modified flame-retardant fabric and the flame-retardant fabric

Abstract

This invention discloses a method for preparing a metal chelate-modified flame-retardant fabric and the flame-retardant fabric itself. The preparation method includes: (1) preparing a cationic solution and an anionic solution respectively, and adding sodium chloride solution to the cationic solution and anionic solution respectively; (2) immersing the fabric alternately in the cationic solution and anionic solution for layer-by-layer self-assembly, and then immersing the fabric in a metal ion solution, rinsing, and drying to obtain the metal chelate-modified flame-retardant fabric. This invention forms a nano-coating of a poorly soluble polyelectrolyte complex on the fabric surface through electrostatic bonding, and adsorbs metal ions by means of the chelation effect of anions and cations on metal ions, further improving the thermal stability of the fabric; and by adding sodium chloride, the ionic strength of the solution is increased, the coating structure is optimized, and its stability, durability and flame retardancy are enhanced. This method is simple and can achieve flame retardancy without dripping.

Description

Technical Field

[0001] This invention belongs to the field of fiber technology, specifically, it relates to a method for preparing a metal chelate modified flame-retardant fabric and the flame-retardant fabric itself. Background Technology

[0002] Textiles are widely used in all aspects of life, from clothing and home textiles to industrial fabrics. However, statistics show that fires caused by textiles account for 30% to 50% of all fires worldwide each year, posing a huge threat and causing significant losses to people's lives and property. In particular, with the widespread use of synthetic fibers (such as polyester and nylon), these thermoplastic fibers not only spread flames rapidly when burning, but also produce molten drips that can easily ignite other items, causing secondary fires. Therefore, developing efficient, environmentally friendly, and durable flame-retardant textiles has significant social and economic value.

[0003] Traditional flame retardant treatments primarily employ halogenated flame retardants (such as decabromodiphenyl ether and hexabromocyclododecane). While these flame retardants offer high flame retardancy and require only small amounts, they release large quantities of toxic and corrosive hydrogen halide gases (such as HBr and HCl) during combustion, while also producing highly toxic substances like dioxins and furans, seriously threatening human safety and the environment. Therefore, the EU RoHS Directive, REACH regulations, and numerous other countries and regions worldwide have explicitly prohibited or restricted the use of halogenated flame retardants in textiles.

[0004] To replace halogen-containing flame retardants, researchers have developed various halogen-free flame retardant systems, mainly including phosphorus-based flame retardants (such as phosphate esters, phytic acid, and ammonium polyphosphate), nitrogen-based flame retardants (such as melamine and its derivatives), silicon-based flame retardants, and nano-flame retardants (such as layered double hydroxides, montmorillonite, and carbon nanotubes). However, existing halogen-free flame retardant technologies still have many shortcomings in application: (a) The contradiction between flame retardant efficiency and addition amount: Most halogen-free flame retardants require a high addition amount (usually 15% to 30% of the fabric weight) to achieve a satisfactory flame retardant effect. However, a high addition amount will seriously affect the hand feel, breathability and mechanical properties of the fabric, especially for lightweight fabrics, this problem is more prominent.

[0005] (ii) Poor durability: In the currently commonly used pad-baking process, flame retardants mainly adhere to the fiber surface through physical adsorption or simple chemical bonding, resulting in poor washability. According to GB / T 17591-2015 "Flame Retardant Fabrics" standard, B1 grade flame retardant fabrics need to maintain their flame retardant properties after more than 20 washes, but many existing products fail to meet this requirement.

[0006] (iii) The problem of molten droplets is difficult to solve: For thermoplastic fibers such as polyester and nylon, existing halogen-free flame retardant technologies can often only slow down the burning rate during combustion, but cannot fundamentally solve the problem of molten droplets. The presence of molten droplets can not only ignite flammable materials below, but may also cause severe skin burns.

[0007] In recent years, layer-by-layer self-assembly (LbL) technology has attracted widespread attention in the field of flame-retardant functionalization of textiles as a novel surface modification method. This technology involves alternately immersing fabrics in polyelectrolyte solutions with opposite charges, utilizing electrostatic attraction to deposit nanoscale functional coatings layer by layer on the fiber surface.

[0008] However, the existing technology for preparing flame-retardant fabrics using layer-by-layer self-assembly still has the following technical defects that urgently need to be addressed: Flame retardant efficiency needs to be further improved: Existing LbL flame retardant coatings are difficult to achieve ideal flame retardant effects at low weight gain rates (usually <5%), especially difficult to meet the requirements of the B1 flame retardant standard (damage length <150mm).

[0009] Insufficient washability and durability: The coating and fibers are mainly bonded by electrostatic attraction, which can easily lead to desorption and detachment during washing, making it difficult to guarantee the durability of the flame retardant effect.

[0010] There is a lack of effective solutions to the dripping problem of thermoplastic fibers: For fibers such as polyester and nylon that are prone to melting and dripping when burning, most existing LbL flame retardant technologies can only delay combustion and cannot achieve a "drip-free" flame retardant effect.

[0011] Therefore, developing a method for preparing flame-retardant fabrics that has high flame retardant efficiency, good washability, can effectively suppress melt dripping, and has a simple process is a technical problem that urgently needs to be solved in this field.

[0012] In view of this, the present invention is hereby proposed. Summary of the Invention

[0013] The purpose of this invention is to provide a method for preparing a metal chelate-modified flame-retardant fabric and the flame-retardant fabric itself. This invention utilizes electrostatic bonding to self-assemble a sparingly soluble polyelectrolyte complex nano-coating on the fabric surface. The adsorption of metal ions through the chelation of cations and anions further enhances the thermal stability of the fabric. Furthermore, the addition of sodium chloride increases the ionic strength of the solution, optimizes the coating structure, and enhances its stability, durability, and flame retardancy. This method is simple and can achieve flame retardancy without dripping.

[0014] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows: (1) Prepare cation solutions and anion solutions respectively, and add sodium chloride solution to the cation solutions and anion solutions respectively to change the ionic strength of the solutions; (2) After the fabric is alternately immersed in cationic and anionic solutions for layer-by-layer self-assembly, it is then immersed in a metal ion solution, rinsed, and dried to obtain a metal chelate modified flame retardant fabric.

[0015] The fabrics include, but are not limited to, cotton, nylon, cellulose fiber, polyester, polyester and their blends. Preferably, the nylon includes nylon 56 (PA56). This invention utilizes the positive charge of cations and the negative charge of anions to self-assemble a sparingly soluble polyelectrolyte complex nanocoating on the fabric surface through electrostatic bonding, and further enhances the thermal stability of the fabric by adsorbing metal ions through the chelating effect of cations and anions.

[0016] In this invention, by adding sodium chloride to the cationic and anionic solutions, the ionic strength of the solution is increased. Higher ionic strength can increase the interaction force between ions in the coating, thereby improving the stability of the coating, reducing peeling or decomposition, and extending the service life of the coating. Furthermore, the increase in ionic strength helps to promote the adsorption and accumulation of ions, thereby increasing the thickness of the coating. A thicker coating can provide better protection and improve the flame retardant properties of the coating. In addition, higher ionic strength can promote the cross-linking and aggregation of ions, forming a denser coating structure. Such a structure can improve the mechanical strength and thermal stability of the coating, and enhance its stability and durability in complex environments.

[0017] Furthermore, in step (1), the amount of sodium chloride solution added is 0.03 to 0.1 mol / L.

[0018] When the concentration of sodium chloride is below 0.03 mol / L, the ionic strength is insufficient, and the increase in coating weight and density is not significant; when it is above 0.1 mol / L, the excessively high ionic strength will cause the polyelectrolyte to curl excessively or even precipitate (especially melamine), affecting the stability of the solution and the uniformity of the coating.

[0019] Further, in step (1), the preparation of the cationic solution includes: adding melamine to the cationic electrolyte solution and adjusting the pH of the solution to 2-6, preferably 3-5, to obtain the solution; Preferably, the melamine has a mass fraction of 0.1–1 wt%. Preferably, the cationic electrolyte is selected from one or more of polyethyleneimine, chitosan, and polyethyleneamine.

[0020] Melamine molecules contain multiple nitrogen elements, a key component of many flame retardants. During combustion, nitrogen decomposes at high temperatures, releasing nitrogen gas, which dilutes the oxygen in the combustion process, inhibits combustion, reduces flame temperature and speed, and improves flame retardancy. Furthermore, melamine decomposes at high temperatures to generate carbon-rich char residues. These residues can coat the fiber surface to form a protective layer, preventing further flame spread and improving the fabric's flame retardant properties. In addition, melamine can synergistically enhance flame retardant effects with other flame retardants; for example, melamine interacts with phosphorus-containing flame retardant components to form a more stable flame retardant system, improving overall flame retardant performance.

[0021] Furthermore, melamine, as an additive in both anion and cation solutions, contains multiple imine groups in its molecules. These imine groups can form cation complexes with cations in water. When melamine solution is added to a solution containing cations, the imine groups attract the cations, forming ion pairs. This increases the interaction force between ions in the coating, thereby enhancing the stability of the coating, helping to prevent peeling or decomposition, and improving the coating's durability and flame retardant effect.

[0022] In particular, the size of melamine molecules is moderate, neither too large to cause uneven coating thickness nor too small to effectively enhance the interaction between ions. The appropriate molecular size allows melamine to form stable ion pairs with other cations in the solution, increasing the stability of the coating.

[0023] Furthermore, in step (1), preparing the anion solution includes: adjusting the pH of the anion electrolyte solution to 2-6, preferably 3-5. A pH that is too low (<2) will cause the phosphate groups to protonate, weakening the anion properties; a pH that is too high (>6) may cause metal ions to precipitate prematurely or affect the chelation efficiency.

[0024] Preferably, the mass fraction of the anion solution is 0.5 wt% to 2.5 wt%. Preferably, the anionic electrolyte is selected from one or more of sodium polyphosphate, phytic acid, ammonium polyphosphate, and sodium alginate; preferably, phytic acid. Phytic acid contains six phosphate groups and has extremely strong metal chelating ability and char-forming catalytic effect.

[0025] Furthermore, in step (2), the specific process of layer-by-layer self-assembly includes: alternatingly immersing the fabric in cationic and anionic solutions, and rinsing after each immersion to remove physically adsorbed unbound polyelectrolytes.

[0026] Preferably, after the first double-layer impregnation is completed, the fabric is rinsed and dried. During the assembly process after the first double-layer assembly, the fabric is rinsed after impregnation and then impregnated again until the assembly is completed.

[0027] In other words, each layer is rinsed and dried after impregnation; after the first double layer is dried, subsequent double layers are only rinsed after impregnation and no further intermediate drying is performed until the last double layer is assembled. This "first layer drying + subsequent continuous assembly" process ensures a strong bond between the first layer and the fabric substrate, while also improving the efficiency and coating uniformity of subsequent assembly.

[0028] A further step, involving the first double impregnation, includes: First impregnation: Immerse the fabric in a cationic solution, rinse, and dry; Second impregnation: Immerse the fabric in an anionic solution, rinse, and dry; The process parameters for the first and second impregnation processes can be the same or different. In a preferred embodiment, the impregnation duration, rinsing duration, drying temperature, and drying time are consistent between the first and second impregnation processes.

[0029] Preferably, the soaking time is 1-10 min, the rinsing time is 1-5 min, the drying temperature is 40℃-80℃, and the drying time is 20-60 min. More preferably, the soaking time is 3-7 min, the rinsing time is 2-3 min, the drying temperature is 60℃-80℃, and the drying time is 20-40 min.

[0030] Furthermore, in step (2), the alternating impregnation of the cation solution and the anion solution forms a double layer.

[0031] Furthermore, in step (2), the self-assembly layer reaches 5 to 40 double layers. When the number of double layers is less than 5, the coating is too thin and the flame retardant effect is insufficient; when the number of double layers is greater than 40, the weight gain tends to saturate, the marginal benefit of continuing to increase the number of layers decreases, and it may affect the fabric's hand feel and breathability. Preferably, there are 10 to 30 double layers, more preferably 15 to 25 double layers.

[0032] Furthermore, in step (2), the metal ion solution is selected from one or more of anhydrous calcium chloride, magnesium chloride hexahydrate, anhydrous zinc acetate, ferric chloride hexahydrate, and aluminum chloride solution; Preferably, the metal ion solution is selected from anhydrous calcium chloride or anhydrous zinc acetate; calcium ions and zinc ions have moderate chelation stability constants, which can effectively bind to the polyelectrolyte coating and effectively catalyze carbonization at high temperatures, while having little impact on the whiteness and hand feel of the fabric.

[0033] Preferably, the concentration of the metal ion solution is 0.1–1 mol / L. When the concentration is below 0.1 mol / L, the amount of metal ions adsorbed is insufficient, and the chelation and cross-linking effect is limited; when the concentration is above 1 mol / L, the excessive ionic strength may cause the coating to shrink excessively or metal ions to form precipitated particles on the surface, affecting uniformity.

[0034] Further, in step (2), the fabric is immersed in a metal ion solution for 1–60 min, preferably 5–20 min. If the immersion time is too short, the chelation reaction will be insufficient; if the immersion time is too long, the efficiency will decrease and there will be no additional gain. After immersion, the fabric is rinsed with water for 1–10 min, preferably 1–5 min, to remove unbound metal ions. After immersion, the fabric is dried at 40°C–80°C for 10–40 min, preferably at 60°C–80°C for 10–20 min.

[0035] The present invention also provides a metal chelate modified flame-retardant fabric, which is prepared by any of the preparation methods described above.

[0036] Preferably, the flame-retardant fabric fibers are selected from at least one of cellulose fibers (such as cotton, linen, viscose), polyester, nylon (such as nylon 6, nylon 66, nylon 56), or blended fabrics thereof.

[0037] Preferably, the flame-retardant fabric has at least one of the following characteristics: (i) According to GB / T 5455-2014, its afterflame time and smoldering time are both 0 seconds, and the damaged length is ≤15cm, preferably ≤13cm; (ii) No molten drips ignited the degreased cotton below during the vertical burning test, thus achieving "no molten drips"; (iii) Its limiting oxygen index (LOI) is ≥28%, preferably ≥30%; (iv) After washing 20 times according to AATCC 61-2013 standard, the length of damage is still ≤17 cm, preferably ≤15 cm.

[0038] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0039] (1) Excellent flame retardant properties and no dripping: Through the synergistic effect of electrostatic layer-by-layer self-assembly and metal chelation technology, a highly efficient flame retardant coating is formed on the surface of the fabric. The resulting fabric has a 0-second afterflame time and smoldering time in the vertical burning test, a short damaged length (≤15 cm), and no molten dripping during the burning process, avoiding the risk of secondary fire caused by molten dripping, which meets the requirements of GB / T 17591-2015 "Flame Retardant Fabrics" Class B1.

[0040] (2) Good stability and durability: By adding an appropriate amount of sodium chloride (0.03-0.1 mol / L) to the cationic and anionic solutions, the ionic strength of the solution is increased. Higher ionic strength can increase the interaction force between ions in the coating, thereby improving the stability of the coating, reducing peeling or decomposition, and extending the service life of the coating. In addition, the increase in ionic strength helps to promote the adsorption and accumulation of ions, thereby increasing the thickness of the coating. A thicker coating can provide better protection and improve the flame retardant performance of the coating. Furthermore, higher ionic strength can promote the cross-linking and aggregation of ions, forming a denser coating structure. Such a structure can improve the mechanical strength and thermal stability of the coating, enhancing its stability and durability in complex environments. Thus, the conformation of the polyelectrolyte and the density of the coating are optimized, enhancing the ionic and physical cross-linking within the coating. The resulting flame-retardant fabric can still maintain good flame retardant effect after multiple standard washes, exhibiting excellent washability and service life.

[0041] (3) Simple process and environmentally friendly: This invention adopts an aqueous layer-by-layer self-assembly process, which does not require organic solvents and does not use traditional halogenated flame retardants, thus avoiding the release of toxic gases during combustion. The process conditions are mild (room temperature to 80°C), the equipment requirements are low, and it is easy to realize continuous industrial production, which has significant environmental and economic benefits.

[0042] (4) Minimal impact on the original properties of the fabric: The layer-by-layer self-assembly technology forms a nanoscale coating only on the fiber surface without damaging the fiber structure. By controlling the number of double layers, ionic strength and metal ion types, the original hand feel, breathability and mechanical properties of the fabric can be preserved to the greatest extent while ensuring flame retardant performance. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0044] Example 1

[0045] (1) Preparation of cation solutions: A 2.5 wt% polyethyleneimine cationic electrolyte was dissolved in water, and a 1 wt% melamine was added. The pH of the solution was adjusted to 4 using hydrochloric acid. 0.1 mol / L sodium chloride was added to the solution to increase the ionic strength. (2) Preparation of anionic solutions: A 2.5 wt% phytic acid anionic electrolyte was dissolved in water, and the pH of the solution was adjusted to 4 using a 1 mol / L sodium hydroxide solution. 0.1 mol / L sodium chloride was added to the solution to increase the ionic strength. (3) Preparation of metal ion solutions: Prepare a 1 mol / L anhydrous calcium chloride metal ion solution.

[0046] (4) Preparation of flame-retardant fabrics: (41) First monolayer: Immerse the nylon 56 filament fabric in a cationic solution for 5 min, then rinse in water for 2 min. After rinsing, dry the fabric at 80°C for 20 min.

[0047] (42) Second monolayer: Immerse the fabric in an anionic solution for 5 min, then rinse in water for 2 min. Dry the fabric at 80°C for 20 min. At this point, the first double layer stacking is complete.

[0048] Repeat steps (41) and (42) 20 times to obtain 20 double-layered self-assembled fabrics.

[0049] (43) After the last layer is assembled and rinsed, the fabric is soaked in a metal ion solution for 5 minutes, then rinsed with water for 1 minute, and finally dried at 80°C for 20 minutes to obtain the metal chelate modified flame retardant fabric. Its vertical burning performance is tested according to GB / T5455-2014, and the results are shown in Table 1 below.

[0050] Vertical burning performance: Tested according to GB / T 5455-2014 "Determination of vertical damage length, smoldering and afterflame time of textiles". The sample size was 300mm × 80mm, and the ignition time was 12s. The afterflame time, smoldering time, and damage length were recorded, and it was observed whether molten drips ignited the absorbent cotton below ("with molten drips" or "no molten drips").

[0051] Weight gain rate: Weigh the dry weight of the fabric before and after treatment, and calculate it according to the following formula: Weight gain rate (%) = (weight after treatment - weight before treatment) / weight before treatment × 100%.

[0052] Table 1 Vertical burning performance of calcium chloride chelate modified flame-retardant fabrics

[0053] The results showed that the fabric obtained in Example 1 had no smoldering or afterflame, and the damaged length was less than 150 mm, which met the requirements of Class B1 flame-retardant fabrics in the national standard GB / T 17591-2015 "Flame-retardant Fabrics", and achieved no dripping.

[0054] Example 2

[0055] (1) Preparation of cation solutions: Dissolve 0.5 wt% cationic electrolyte polyethyleneamine in water, add 0.1 wt% melamine, adjust the pH of the solution to 2 using hydrochloric acid or acetic acid, and add 0.03 mol / L sodium chloride to the solution to increase ionic strength. (2) Preparation of anionic solutions: Phytic acid, an anionic electrolyte with a mass fraction of 0.5 wt%, was dissolved in water. The pH of the solution was adjusted to 2 using sodium hydroxide solution. 0.03 mol / L sodium chloride was added to the solution to increase the ionic strength. (3) Preparation of metal ion solutions: Solution without added metal ions.

[0056] (4) Preparation of flame-retardant fabrics: (41) First monolayer: Immerse the nylon 56 filament fabric in a cationic solution for 1 min. Then rinse in water for 1 min. After rinsing, dry the fabric at 40°C for 20 min.

[0057] (42) Second monolayer: Immerse the fabric in an anionic solution for 1 min. Then rinse in water for 1 min. Dry the fabric at 60°C for 20 min. At this point, the first double layer stacking is complete.

[0058] Repeat steps (41) and (42), this time soaking for 1 minute. Rinse for 1 minute.

[0059] (43) After the last layer is assembled and rinsed, the fabric is immersed in a metal ion solution for 1 min. Then it is rinsed with water for 1 min. Finally, the fabric is dried at 40°C for 20 min to obtain the modified flame retardant fabric. Its vertical burning performance is tested according to GB / T 5455-2014. The results are shown in Table 2 below. Under the minimum dosage and without the addition of metal chelates, the damage length is less than 150 mm, but slightly larger than that of the modified flame retardant fabric with added chelates.

[0060] Table 2 Vertical burning performance of flame-retardant fabrics without chelate modification

[0061] Example 3

[0062] (1) Preparation of cation solutions: Dissolve 2.5 wt% cationic electrolyte chitosan in water, add 1 wt% melamine, and adjust the pH of the solution to 6 using hydrochloric acid or acetic acid; add 0.1 mol / L sodium chloride to the solution to increase ionic strength. (2) Preparation of anionic solutions: A 2.5 wt% sodium polyphosphate anionic electrolyte was dissolved in water, and the pH of the solution was adjusted to 6 using sodium hydroxide solution. 0.1 mol / L sodium chloride was added to the solution to increase the ionic strength. (3) Preparation of metal ion solutions: Prepare a 1 mol / L solution of anhydrous zinc acetate containing metal ions.

[0063] (4) Preparation of flame-retardant fabrics: (41) First monolayer: Immerse the nylon 56 filament fabric in a cationic solution for 10 min. Then rinse in water for 5 min. After rinsing, dry the fabric at 80°C for 60 min.

[0064] (42) Second monolayer: Immerse the fabric in an anionic solution for 10 min. Then rinse in water for 5 min. Dry the fabric at 60°C for 60 min. At this point, the first double layer stacking is complete.

[0065] After each soaking step following the first double layer, no further drying is performed until the final layer is assembled.

[0066] Repeat steps (41) and (42), this time soaking for 5 minutes. Rinse for 5 minutes.

[0067] (43) After the last layer is assembled and rinsed, the fabric is soaked in a metal ion solution for 60 min. Then it is rinsed with water for 10 min. Finally, the fabric is dried at 80℃ for 60 min to obtain the metal chelate modified flame retardant fabric. Its vertical burning performance is tested according to GB / T5455-2014. The results are shown in Table 3 below. The damaged length is less than 150 mm.

[0068] Table 3 Vertical burning performance of flame-retardant fabrics modified with zinc acetate chelate

[0069] Experimental Example 1 This experimental example verifies the effect of adding sodium chloride solution and its concentration to cationic and anionic solutions on fabric properties: Experimental Group 1: The only difference between this experimental group and Example 1 is that no sodium chloride solution is added to either the cation solution or the anion solution.

[0070] Experimental Group 2: The only difference between this experimental group and Example 1 is that 0.01 mol / L sodium chloride solution was added to both the cation solution and the anion solution.

[0071] Experimental Group 3: The only difference between this experimental group and Example 1 is that 0.15 mol / L sodium chloride solution was added to both the cation solution and the anion solution.

[0072] The properties of the fabrics obtained in Example 1, Test Group 1 and Test Group 2 were tested, and the results are shown in Table 4 below.

[0073] Table 4. Weight gain of flame-retardant fabrics with different sodium chloride solutions

[0074] Experiments revealed that the greater the weight gain of the modified flame-retardant additive, the better the flame-retardant effect. The weight gain of the modified flame-retardant fabric gradually increased with increasing sodium chloride concentration; however, experiments showed that a NaCl concentration exceeding 0.1 mol / L led to melamine precipitation.

[0075] As can be seen from the above embodiments and comparative examples, the present invention, through electrostatic layer-by-layer self-assembly combined with metal chelation technology and the addition of an appropriate amount of sodium chloride (0.03~0.1 mol / L) during the assembly process, can significantly improve the flame retardant properties of fabrics without dripping. The method of the present invention is applicable to various fabric substrates (PA56, cotton, polyester, etc.) and various polyelectrolyte / metal ion combinations, and has broad industrial application prospects.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a metal chelate-modified flame-retardant fabric, characterized in that: (1) Prepare cation solutions and anion solutions respectively, and add sodium chloride solution to the cation solutions and anion solutions respectively; (2) After the fabric is alternately immersed in cationic and anionic solutions for layer-by-layer self-assembly, it is then immersed in a metal ion solution, rinsed, and dried to obtain a metal chelate modified flame retardant fabric.

2. The method for preparing a metal chelate-modified flame-retardant fabric according to claim 1, characterized in that: In step (1), the amount of sodium chloride solution added is 0.03 to 0.1 mol / L.

3. The method for preparing a metal chelate-modified flame-retardant fabric according to claim 1 or 2, characterized in that: In step (1), the preparation of the cationic solution includes: adding melamine to the cationic electrolyte solution and adjusting the pH of the solution to 2 to 6, preferably 3 to 5, to obtain the solution; Preferably, the melamine has a mass fraction of 0.1–1 wt%. Preferably, the cationic electrolyte is selected from one or more of polyethyleneimine, chitosan, and polyethyleneamine; Preferably, the mass fraction of the cationic electrolyte is 0.5 wt% to 2.5 wt%.

4. A method for preparing a metal chelate-modified flame-retardant fabric according to any one of claims 1-3, characterized in that: In step (1), preparing the anion solution includes: adjusting the pH of the anion electrolyte solution to 2-6, preferably 3-5; Preferably, the mass fraction of the anion solution is 0.5 wt% to 2.5 wt%. Preferably, the anionic electrolyte is selected from one or more of sodium polyphosphate, phytic acid, ammonium polyphosphate, and sodium alginate; preferably, phytic acid.

5. A method for preparing a metal chelate-modified flame-retardant fabric according to any one of claims 1-4, characterized in that: In step (2), the specific process of layer-by-layer self-assembly includes: immersing the fabric alternately in cationic and anionic solutions, and rinsing after each immersion to remove physically adsorbed unbound polyelectrolytes; Preferably, after the first double-layer impregnation is completed, the fabric is rinsed and dried. During the assembly process after the first double-layer assembly, the fabric is rinsed after impregnation and then impregnated again until the assembly is completed.

6. A method for preparing a metal chelate-modified flame-retardant fabric according to any one of claims 1-5, characterized in that: In step (2), the first double-layer impregnation includes: First impregnation: Immerse the fabric in a cationic solution, rinse, and dry; Second impregnation: Immerse the fabric in an anionic solution, rinse, and dry; The process parameters for the first impregnation layer and the second impregnation layer may be the same or different; Preferably, the soaking time, rinsing time, drying temperature, and drying time are the same in the first and second impregnation processes; Preferably, the soaking time is 1-10 min, the rinsing time is 1-5 min, the drying temperature is 40℃-80℃, and the drying time is 20-60 min; More preferably, the soaking time is 3 to 7 minutes, the rinsing time is 2 to 3 minutes, the drying temperature is 60°C to 80°C, and the drying time is 20 to 40 minutes.

7. A method for preparing a metal chelate-modified flame-retardant fabric according to any one of claims 1-6, characterized in that: In step (2), the self-assembly layer by layer reaches 5 to 40 double layers.

8. A method for preparing a metal chelate-modified flame-retardant fabric according to any one of claims 1-7, characterized in that: In step (2), the metal ion solution is selected from one or more of anhydrous calcium chloride, magnesium chloride hexahydrate, anhydrous zinc acetate, ferric chloride hexahydrate, and aluminum chloride solution; preferably, the metal ion solution is selected from anhydrous calcium chloride or anhydrous zinc acetate; preferably, the concentration of the metal ion solution is 0.1 to 1 mol / L.

9. A method for preparing a metal chelate-modified flame-retardant fabric according to any one of claims 1-8, characterized in that: In step (2), the fabric is immersed in a metal ion solution for 1 to 60 minutes, preferably 5 to 20 minutes; after immersion, it is rinsed with water for 1 to 10 minutes, preferably 1 to 5 minutes; after immersion, the fabric is dried at 40°C to 80°C for 10 to 40 minutes, preferably at 60°C to 80°C for 10 to 20 minutes.

10. A flame-retardant fabric modified with a metal chelate, characterized in that: Prepared using the preparation method described in any one of claims 1-9; Preferably, the fabric fibers of the flame-retardant fabric are selected from at least one of cellulose fibers, polyester, and nylon.

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