Fabric for flame-retardant carpet and preparation method thereof

Abstract

The invention discloses a fabric for a flame-retardant carpet and a preparation method of the fabric, and belongs to the technical field of functional textile materials. The preparation method of the fabric comprises the following steps: firstly, mixing deionized water, a wetting and penetrating agent, amino-functionalized zirconium hydrogen phosphate, microencapsulated red phosphorus, waterborne polyurethane, boron-silicon-zinc hybrid sol and a thickening agent to prepare flame-retardant slurry; then dipping carpet base cloth in the slurry, and finally obtaining a finished product through padding, pre-drying and high-temperature baking. Wherein the amino-functionalized zirconium hydrogen phosphate is obtained by synthesizing zirconium hydrogen phosphate by a hydrothermal method and then carrying out surface modification by utilizing a silane coupling agent; the boron-silicon-zinc hybrid sol is prepared from zinc salt, boric acid and silane through a sol-gel process. The carpet fabric prepared by the method has excellent flame-retardant property and durability, and the flame-retardant functional layer on the surface of the carpet fabric is firmly combined, so that the carpet fabric can tolerate repeated washing.

Description

Technical Field

[0001] This invention relates to the field of functional textile materials technology, specifically to a flame-retardant carpet fabric and its preparation method. Background Technology

[0002] As an important component of interior decoration and flooring materials, carpets are widely used, accompanied by ongoing concerns about fire safety. Most ordinary carpet fabrics are flammable or combustible materials, easily igniting and spreading rapidly upon contact with a fire source, releasing large amounts of heat and toxic fumes, posing a serious fire hazard. Therefore, effective flame-retardant treatment of carpet fabrics is a necessary requirement for improving the safety levels of public buildings, transportation vehicles, and residences. Existing flame-retardant methods can be mainly divided into two categories: one is incorporating flame retardants during fiber production, and the other is surface finishing after the fabric is finished. The former may affect the spinning process and basic fiber properties; the latter relies on impregnation, coating, and other technologies to apply a flame-retardant functional layer to the fabric surface. However, regardless of the method, achieving high efficiency, durability, and compatibility with the physical properties of the application remains a core challenge for the industry.

[0003] Currently, all flame retardant systems used in textiles have their own significant limitations. Some traditional inorganic flame retardants require extremely high dosages to meet flame retardant standards, often resulting in a hardened and stiff fabric feel, impaired mechanical strength, and poor compatibility between components and the polymer matrix, leading to migration and shedding. The application of some highly efficient halogenated flame retardants is being strictly limited due to environmental and health risks. While the much-anticipated phosphorus-nitrogen-based halogen-free flame retardants perform well in many scenarios, their washability and durability are often insufficient when dealing with carpets that require frequent cleaning. A deeper problem lies in the fact that many flame retardant treatments only bind the flame-retardant components to fibers through physical adhesion or simple mixing, resulting in weak interfacial forces. This bonding method may be effective in a dry state, but after exposure to friction, washing, and other practical conditions, the flame-retardant components are easily lost, leading to rapid performance degradation. Furthermore, single-mechanism flame retardancy is often insufficient to cope with complex combustion processes, making it difficult to form a robust and multi-layered fire barrier.

[0004] To address the aforementioned bottlenecks, the latest research trends focus on constructing novel flame-retardant systems through materials design and interface engineering. Among these, layered inorganic compounds have gained attention due to their potential physical barriers and catalytic char formation properties; however, improving their compatibility and bonding with organic matrices remains crucial. Meanwhile, sol-gel technology offers the possibility of constructing continuous, dense nano-protective layers on fiber surfaces, but the performance of single-component networks still has room for improvement. Therefore, the ingenious integration of multiple flame-retardant elements through chemical methods, enabling them to exert synergistic effects in different stages such as gas-phase inhibition, condensed-phase char formation, and thermal insulation, and firmly anchoring the entire flame-retardant functional layer to the fiber substrate using strong chemical bonding strategies, has become an important direction for overcoming the limitations of existing technologies. Against this backdrop, this invention aims to develop a carpet fabric solution that combines excellent flame-retardant performance, outstanding durability, and good practicality. Its core lies in the innovative preparation of two key functional components and the optimization of processes to achieve synergistic and robust bonding. Summary of the Invention

[0005] The purpose of this invention is to provide a flame-retardant carpet fabric and its preparation method, which solves the technical problems of poor washability of existing flame-retardant carpets due to the weak bonding between flame retardants and fibers, and the serious damage to the fabric's feel and physical properties caused by excessive addition of fillers in pursuit of flame-retardant effects.

[0006] The present invention achieves the above objectives through the following technical solutions: A method for preparing a flame-retardant carpet fabric, comprising the following steps: S1. By weight, add 35-65 parts of deionized water and 0.8-2.5 parts of fatty alcohol polyoxyethylene ether to a stirrer. While stirring continuously, add 6-14 parts of amino-functionalized α-zirconium hydrogen phosphate and 7-13 parts of microencapsulated red phosphorus in sequence. Stir, then add 16-24 parts of waterborne polyurethane and 11-19 parts of boron-silicon-zinc hybrid sol and stir to mix. Add 0.25-0.75 parts of polyacrylic acid thickener to obtain flame retardant slurry. S2. Impregnate the carpet base fabric in flame-retardant slurry to obtain impregnated wet fabric; send the impregnated wet fabric into a hot air oven and pre-dry it at 105-115℃ to obtain pre-dried fabric; transfer the pre-dried fabric to a high-temperature baking machine and bake it at 165-175℃; cool and roll it up.

[0007] In this invention, the final formation and performance of the flame-retardant carpet fabric rely on the physicochemical synergy and interfacial integration of amino-functionalized α-zirconium hydrogen phosphate and boron-silicon-zinc hybrid sol with other components during processing. Its preparation begins with the formulation of a flame-retardant finishing slurry, a multiphase composite system in which amino-functionalized α-zirconium hydrogen phosphate serves as a nanoscale solid synergist, microencapsulated red phosphorus as a highly efficient phosphorus source, boron-silicon-zinc hybrid sol as a liquid network precursor, and waterborne polyurethane as a film-forming binder. Through a padding process, this composite slurry is uniformly applied to the surface and gaps of the carpet base fabric fibers. The subsequent pre-drying stage primarily removes moisture, allowing the slurry to initially enrich the fiber surface. The most critical reaction occurs during the high-temperature baking stage. During this process, multiple interfacial chemical reactions and phase transitions occur simultaneously: the waterborne polyurethane resin molecular chains crosslink and solidify, forming a continuous elastic film; the borosilicate-zinc hybrid sol precursor undergoes deep polycondensation, shedding residual small molecules and transforming from a sol state into a robust, glassy inorganic-organic hybrid network; importantly, the primary amine groups exposed on the surface of the amino-functionalized zirconium hydrogen phosphate undergo rapid addition reactions with the isocyanate groups at the ends of the polyurethane prepolymer, forming strong urea bonds; simultaneously, these amino groups and the polar groups on the polyurethane segments can also form strong hydrogen bonds with the abundant silanol groups in the hybrid sol network, and may even participate in condensation. Microencapsulated red phosphorus is embedded in this forming dense composite film. This multi-level interfacial interaction, dominated by chemical bonds and supplemented by hydrogen bonds and physical entanglement, creates a strong and robust "integrated" bond between the flame-retardant functional layer and the fiber matrix, as well as between the various flame-retardant components, which is the fundamental reason for the fabric's excellent durability. In terms of the flame-retardant mechanism, this system exhibits perfect multi-element, multi-mechanism synergy. Upon contact with fire, the combustible gases produced by the decomposition of polyurethane and fibers are first diluted and interfered with by the inert gases released by red phosphorus and boron-containing species. Subsequently, amino-functionalized zirconium hydrogen phosphate strongly catalyzes the dehydration and carbonization of the organic matrix, and together with phosphorus and nitrogen species, promotes the formation of an expanding and robust char layer. Simultaneously, the boron-silicon-zinc hybrid network transforms into a ceramic protective layer covering the char layer and the surface of unburned fibers at high temperatures. This layer combines heat insulation, oxygen barrier, and smoke suppression functions. The char layer and ceramic layer support each other and are tightly bonded, forming an indestructible condensed-phase fire barrier, thus achieving efficient, durable, and environmentally friendly flame-retardant protection.

[0008] According to a preferred embodiment of the present invention, in step S1, the viscosity of the flame-retardant slurry is 2000-3000 mPa·s.

[0009] According to a preferred embodiment of the present invention, in step S2, the baking time at 165-175°C is 2-3 minutes.

[0010] According to a preferred embodiment of the present invention, the method for preparing the amino-functionalized α-zirconium hydrogen phosphate includes: A1. Dissolve zirconium oxychloride octahydrate in hydrochloric acid to obtain a zirconium solution; add an aqueous phosphoric acid solution dropwise to the zirconium solution while stirring to obtain a mixture; transfer the mixture to a high-pressure reactor and hydrothermally crystallize it at 195-205℃; after natural cooling, centrifuge to obtain a precipitate; wash the precipitate with water and then with ethanol, and dry it at 78-82℃ to obtain crystalline α-zirconium hydrogen phosphate. A2. Disperse crystalline α-zirconium hydrogen phosphate in deionized water, and add anhydrous ethanol solution of 3-aminopropyltriethoxysilane dropwise while stirring at 60-80℃ to obtain a reaction mixture. Centrifuge the reaction mixture to obtain a precipitate. Wash the precipitate with ethanol and dry it at 78-82℃.

[0011] In this invention, the preparation of amino-functionalized α-zirconium hydrogen phosphate is a two-step process involving inorganic crystal synthesis and organic surface modification. Its core lies in constructing hybrid particles that possess both a layered inorganic framework and organic reactivity. The first step involves synthesizing highly crystalline α-zirconium hydrogen phosphate using a classic hydrothermal crystallization method. This process uses soluble zirconium salt and phosphoric acid as precursors, mixed in a strongly acidic environment. Under high temperature and pressure hydrothermal conditions, zirconium ions and phosphate ions undergo a slow dissolution and recrystallization process, gradually assembling into α-type zirconium hydrogen phosphate crystals with a regular layered structure through precise ion coordination and dehydration condensation. Each layer is composed of zirconium-oxygen octahedra connected to phosphate groups via shared oxygen atoms. The layers are stacked through hydrogen bonds and van der Waals forces. The surface and edges of the layers are rich in phosphate hydroxyl and zirconium hydroxyl groups; these active hydroxyl groups form the basis for subsequent chemical modification. The second step involves surface grafting modification of the synthesized α-zirconium hydrogen phosphate using a silane coupling agent. The selected aminosilane coupling agent molecule contains both a hydrolyzable alkoxy group and a reactive amino group. In a mildly heated aqueous environment, the alkoxy group of the silane coupling agent first undergoes hydrolysis to generate highly reactive silanol groups. These newly generated silanol groups then undergo a condensation reaction with the phosphate hydroxyl or zirconium hydroxyl groups inherent on the surface and edges of the α-zirconium hydrogen phosphate particles, removing water molecules and forming stable siloxane-phosphorus bonds or siloxane-zirconium bonds, thereby firmly anchoring the entire molecular chain of the silane coupling agent to the surface of the inorganic laminate in the form of covalent bonds. Finally, the amino functional group at the other end of the silane molecule is successfully introduced and exposed to the outside of the particle, transforming the originally hydrophilic inorganic zirconium hydrogen phosphate into a functionalized material with a surface rich in organic primary amine groups. This modification not only significantly improves its dispersion stability in the organic polymer matrix, but also provides crucial reaction sites for subsequent formation of strong chemical bonds with other components.

[0012] According to a preferred embodiment of the present invention, in step A1, the hydrothermal crystallization time at 195-205°C is 24-48 hours.

[0013] According to a preferred embodiment of the present invention, in step A2, the reaction time for adding anhydrous ethanol solution of 3-aminopropyltriethoxysilane is 4-6 hours.

[0014] According to a preferred embodiment of the present invention, the preparation method of the boron-silicon-zinc hybrid sol includes: B1. Dissolve zinc nitrate hexahydrate in anhydrous ethanol to obtain a zinc nitrate solution; dissolve boric acid and 3-aminopropyltriethoxysilane in a mixed solvent composed of anhydrous ethanol and deionized water to obtain a mixture; add the mixture dropwise to the zinc nitrate solution while stirring at room temperature to obtain a reaction mixture; B2. Place the reaction mixture in an oil bath at 68-72℃ and stir to obtain a sol. After cooling the sol to room temperature, add acetylacetone and continue stirring.

[0015] In this invention, the preparation of boron-silicon-zinc hybrid sol is a typical sol-gel process, essentially constructing an inorganic-organic hybrid network containing boron, silicon, and zinc through the controlled hydrolysis and condensation of molecular precursors. The process uses hydrolyzable aminosilanes, boric acid, and zinc salts as the main reactants. In an alcohol-water mixed solvent, the alkoxy groups of the aminosilane first undergo hydrolysis, generating reactive silanol intermediates. These silanol groups can further undergo condensation reactions to form preliminary linear or branched siloxane-silicon chain structures. Simultaneously, the boric acid molecules present in the solution can co-condense with the silanol groups to form boron-oxysilicon bonds, thereby chemically embedding boron atoms into the growing silicon-oxygen network; boric acid can also coordinate with zinc ions to form zinc-boron-oxygen coordination structures. Zinc ions play a dual role in this system: on the one hand, as a Lewis acid, they can coordinate with oxygen atoms on silanol or boronol groups, acting as cross-linking points and promoting the development of linear siloxane chains into a three-dimensional network structure; on the other hand, zinc ions themselves may also participate in the formation of zinc-containing oxygen cluster units and connect with the siloxane network. The entire reaction is carried out under mild heating and reflux conditions, which is conducive to the thorough mixing and gradual condensation of reactants, inhibiting precipitation and ultimately forming a clear, homogeneous, and stable sol system. In this sol, what is formed is not a long-range ordered crystal, but an amorphous hybrid polymer precursor with a siloxane backbone, boron doping, and zinc ions as cross-linking nodes. The finally added acetylacetone, as an effective chelating agent, can form a stable complex with any free zinc ions that may be present in the system. This further inhibits the premature precipitation of insoluble substances such as zinc hydroxide, ensuring that the hybrid sol has good storage stability and process applicability, laying the precursor foundation for the subsequent formation of a continuous and dense hybrid flame-retardant coating on the fiber surface.

[0016] According to a preferred embodiment of the present invention, in step B1, the volume ratio of anhydrous ethanol to deionized water is 4:1.

[0017] According to a preferred embodiment of the present invention, in step B2, the stirring reaction time is 5-10 hours.

[0018] The present invention also provides a flame-retardant carpet fabric prepared according to the method for preparing flame-retardant carpet fabric.

[0019] The beneficial effects of this invention are as follows: The flame-retardant carpet fabric and its preparation method provided by this invention can produce synergistic and multi-layered beneficial technical effects, and successfully achieve an optimized balance between flame-retardant performance, durability performance and practical performance of the fabric.

[0020] Firstly, regarding the core flame-retardant performance, the amino-functionalized zirconium hydrogen phosphate and borosilicate zinc hybrid sol of this invention construct a unique multi-component synergistic flame-retardant system, achieving a fundamental breakthrough in flame-retardant efficiency. During heated combustion, each component exerts a multi-stage and multi-mechanism synergistic effect. The amino-functionalized zirconium hydrogen phosphate not only provides excellent thermal insulation and physical barrier effects due to its layered structure, but its surface active groups can also effectively catalyze the dehydration and carbonization of the fiber matrix, and produce a significant phosphorus-nitrogen synergistic effect with the active phosphorus-containing substances released by microencapsulated red phosphorus, jointly promoting the formation of an expanded, dense, and high-strength charcoal protective layer. Simultaneously, the borosilicate zinc hybrid sol can be transformed at high temperatures into a continuous, hard glassy or ceramic inorganic network covering the surface of the fiber and char layer. This network can efficiently isolate heat and oxygen, and can capture free radicals required for the combustion chain reaction in the gas phase, thus forming a dual protection of "solid-gas" linkage with the condensed phase char layer barrier. This precise synergy significantly improves the limiting oxygen index of the treated fabric, easily meeting stringent flame retardant standards. At the same time, it effectively suppresses dripping and reduces smoke generation during combustion, significantly enhancing fire safety.

[0021] Secondly, this invention effectively solves the common industry problems of poor durability of flame-retardant treatment and damage to the physical properties of fabrics, achieving a balance between long-lasting protection and user experience. The key lies in the innovative material design and process that establishes a strong interfacial bond, primarily based on chemical bonding, between the flame-retardant functional layer and the fiber substrate. The active amino groups introduced onto the surface of the amino-functionalized zirconium hydrogen phosphate can chemically react with the molecular chains of waterborne polyurethane, and also interact strongly with the functional groups in the borosilicate-zinc hybrid sol network. During the final baking and curing stage, these components crosslink with each other and with the fiber surface through covalent bonds, coordination bonds, etc., forming a dense and robust three-dimensional network structure. This strong interfacial bonding force allows the flame-retardant functional layer to adhere to the carpet fibers extremely persistently, remaining stable even after repeated friction, bending, and even dozens of standard washes, with an extremely low rate of flame-retardant performance degradation, far exceeding the lifespan of traditional physically adsorbed finishing products. Furthermore, thanks to the use of nanocomposite and molecular hybrid technology, the flame retardant components are highly dispersed and achieve high efficiency with a low addition amount. Therefore, the original softness, fullness, tensile strength and abrasion resistance of the carpet fabric are preserved and optimized to the greatest extent, completely avoiding the drawbacks of fabric stiffness, brittleness or serious decline in mechanical properties caused by the addition of flame retardants.

[0022] Finally, the overall technical solution of this invention demonstrates significant advantages in terms of industrial production feasibility, environmental friendliness, and comprehensive cost-effectiveness. All raw materials used in the preparation process are common commercially available chemicals, ensuring stable sources and controllable costs. The core slurry preparation and padding / baking processes are highly compatible with existing textile dyeing and finishing industry production lines, enabling continuous, large-scale, and stable production without major equipment modifications. The process exhibits good reproducibility and simple quality control. The entire technical system completely eliminates harmful substances such as halogens, aligning with the stringent global trends of green environmental protection and sustainable development. In summary, this invention not only provides a high-quality carpet fabric product with excellent flame retardant properties and outstanding durability but also offers a complete, efficient, reliable, and environmentally friendly preparation technology solution. It has significant practical value and broad application prospects for improving fire safety levels in various locations and meeting the market's urgent demand for flooring materials that combine safety and comfort. Detailed Implementation

[0023] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0024] Example 1 Preparation of amino-functionalized α-zirconium hydrogen phosphate: First, accurately weigh 32.2 g of zirconium oxychloride octahydrate and transfer it to a 500 mL beaker. Add 200 mL of 2 mol / L hydrochloric acid solution and place the beaker on a magnetic stirrer. Stir at 500 rpm for 15 min until a completely clear zirconium salt solution without suspended solids is obtained. In another container, measure 200 mL of 3 mol / L phosphoric acid aqueous solution. While continuously stirring the zirconium salt solution magnetically (maintaining a speed of 500 rpm), slowly and evenly add the phosphoric acid solution dropwise to the beaker at a rate of approximately 2 mL / min using a constant pressure dropping funnel. During the dropwise addition, a large amount of white flocculent precipitate immediately forms in the system. After the dropwise addition is complete, continue stirring the mixture for 30 min. Subsequently, carefully transfer the entire mixture to a 500 mL polytetrafluoroethylene-lined high-pressure reactor and tighten the lid. The reactor was placed in a temperature-controlled oven and heated to 200°C at a rate of 5°C / min, and maintained at this temperature for hydrothermal crystallization. The reaction time was precisely controlled to be 24 hours. After the reaction, the oven heating was turned off, and the reactor was allowed to cool naturally to room temperature (approximately 25°C). The reactor lid was opened, and all the material inside was transferred to centrifuge tubes. The tubes were centrifuged at 8000 rpm for 10 minutes, and the supernatant was discarded, yielding a white solid precipitate. The precipitate was redispersed in 400 mL of deionized water, sonicated for 5 minutes, and centrifuged again. This washing process was repeated until the pH of the supernatant was approximately 7, as measured by pH paper. The precipitate was then washed three times with anhydrous ethanol. The washed wet solid was placed in a petri dish, spread evenly, and then placed in a forced-air drying oven at 80°C for 12 hours. The dried material was removed, ground in an agate mortar for 10 minutes, and passed through a 200-mesh sieve to obtain crystalline α-zirconium hydrogen phosphate, which was then sealed and stored for later use.

[0025] Take 20.0 g of the self-made α-zirconium hydrogen phosphate powder and place it in a 250 mL three-necked round-bottom flask, then add 200 mL of deionized water. Place the flask in a 70 °C constant temperature water bath, install a mechanical stirrer, condenser, and constant pressure dropping funnel, and stir at 400 rpm to fully disperse the powder and form a uniform suspension. Accurately weigh 2.0 g of 3-aminopropyltriethoxysilane (APTES) and dissolve it in 40 mL of anhydrous ethanol to prepare a modifier solution. Under continuous stirring and a constant temperature of 70 °C, slowly add the modifier solution dropwise to the α-zirconium hydrogen phosphate suspension at a rate of 1 mL / min through the dropping funnel. After the addition is complete, maintain the water bath temperature at 70 °C and the stirring speed at 400 rpm, and continue the reaction for 5 h to allow APTES to fully hydrolyze, and its silanol groups to undergo a condensation reaction with the P-OH / Zr-OH on the α-ZrP surface. After the reaction was complete, the mixture in the flask was transferred to a centrifuge tube and centrifuged at 8000 rpm for 10 min, collecting the lower solid layer. The solid was washed with anhydrous ethanol and centrifuged three times to completely remove physically adsorbed unreacted silanes and byproducts. The washed solid was placed in a desiccator and dried in an oven at 80 °C for 10 h to obtain amino-functionalized α-zirconium hydrogen phosphate powder, which was then stored in a desiccator for later use.

[0026] Preparation of boron-silicon-zinc hybrid sol: Accurately weigh 5.95 g of zinc nitrate hexahydrate and place it in a 250 mL Erlenmeyer flask. Add 100 mL of anhydrous ethanol, seal the flask tightly, and stir on a magnetic stirrer for 30 min to obtain a completely clear zinc nitrate ethanol solution, labeled as solution C. In a separate 150 mL beaker, accurately weigh 0.62 g of boric acid and 2.48 g of 3-aminopropyltriethoxysilane (APTES). First, add 20 mL of deionized water and stir gently to partially dissolve the boric acid. Then, add 80 mL of anhydrous ethanol and continue stirring for about 20 min until a homogeneous and transparent mixed solution is obtained, labeled as solution D. In a 250 mL three-necked flask equipped with a magnetic stirrer, condenser, and dropping funnel, pre-fill solution C. At room temperature (25 °C) and with continuous stirring (300 rpm), slowly add solution D dropwise to solution C through the dropping funnel at a rate of approximately 3 mL / min. During the dropwise addition, the system gradually turned milky white. After the addition was complete, the three-necked flask was transferred to a constant-temperature oil bath at 70°C, the stirring speed was adjusted to 400 rpm, and reflux was initiated with cooling water. This condition was maintained for 5 hours, during which time the system gradually transformed from a milky white suspension into a translucent, homogeneous, and stable sol. After the reaction was complete, the oil bath was removed, and the sol was allowed to cool naturally to room temperature. 0.20 g of acetylacetone was added to the cooled sol, and stirring was continued for 30 minutes to ensure thorough mixing. The resulting product is the boron-silicon-zinc hybrid sol, which was transferred to a sealed bottle and stored in a cool, dark place for later use.

[0027] Preparation of flame-retardant carpet fabric: First, prepare the flame-retardant finishing slurry. In a 1000mL plastic beaker, add 500g of deionized water and 1.5g of fatty alcohol polyoxyethylene ether (wetting and penetrating agent JFC) sequentially. Place the beaker under a high-speed disperser and stir at 300rpm for 5min to ensure the additives are fully dissolved and dispersed. While maintaining stirring at 300rpm, add 10.0g of the aforementioned self-made amino-functionalized α-zirconium hydrogen phosphate powder and 10.0g of microencapsulated red phosphorus (MRP) with an average particle size ≤10μm sequentially to the beaker. After the addition is complete, increase the speed of the high-speed disperser to 3000rpm and continue high-speed shear dispersion for 30min to ensure uniform dispersion of solid particles and absence of visible agglomerates. Subsequently, the rotation speed was reduced to 500 rpm, and 50.0 g of a 40% solids waterborne polyurethane (PU) dispersion (of which the dry matter mass of PU was 20.0 g) and 150.0 g of the aforementioned self-made boron-silicon-zinc hybrid sol (its solids content was determined by the 105℃ drying method to be approximately 10%, of which the dry matter mass was approximately 15.0 g) were added to the system sequentially. Each material was stirred for 5 minutes after addition to allow for initial mixing. After all materials were added, stirring was continued at 500 rpm for 15 minutes to obtain a preliminary mixed slurry. Finally, 0.50 g of a polyacrylic acid thickener was added to the slurry, the rotation speed was adjusted to 800 rpm, and stirring was carried out for 10 minutes. At this point, the slurry became homogeneous and smooth. The viscosity of the slurry was measured at 25℃ using a rotational viscometer and was approximately 2500 mPa·s. A 100.0 g piece of polyamide 6 (PA6) tufted carpet base fabric (approximately 800 g / m²) was taken. 2 The fabric is fixed to the fabric clamp of a small benchtop padding machine. The padding machine speed is adjusted to 4 m / min, and the base fabric is immersed in the aforementioned flame-retardant slurry using a "two-dip, two-ply" process: the base fabric is immersed in the slurry, squeezed through rollers, immersed again, and squeezed again, controlling the residual rate (liquid content) to 85%. The wet fabric after padding is immediately sent to a hot air circulating oven and pre-dried at 110°C for 4 minutes to allow most of the moisture to evaporate and form a preliminary film. Subsequently, the pre-dried fabric is quickly transferred to a high-temperature baking machine and treated at 170°C for 2.5 minutes. During this stage, the waterborne polyurethane completes cross-linking and curing, and the hybrid sol further condenses to form a dense network. Finally, the baked fabric is cooled at room temperature for 5 minutes and then rolled up to obtain the finished high-durability flame-retardant carpet fabric.

[0028] Example 2 The specific implementation method is the same as in Example 1, except that the amino-functionalized α-zirconium hydrogen phosphate is prepared as follows: 32.2 g of zirconium oxychloride octahydrate is accurately weighed and dissolved in 200 mL of 2 mol / L hydrochloric acid solution. The solution is stirred at 500 rpm for 15 min to obtain a clear zirconium solution. 200 mL of 3 mol / L phosphoric acid solution is measured and added dropwise to the zirconium solution at a rate of 2 mL / min. After the addition is complete, stirring is continued for 30 min. The mixture is transferred to a 500 mL high-pressure reactor, placed in an oven, and heated to 198 °C at 5 °C / min. After crystallization for 30 h, the mixture is cooled with the furnace. The product is collected by centrifugation at 8000 rpm for 10 min, washed with deionized water until neutral, then washed three times with anhydrous ethanol, dried at 80 °C for 12 h, and ground through a 200-mesh sieve to obtain α-zirconium hydrogen phosphate powder. 20.0 g of this powder is dispersed in 200 mL of deionized water and placed in a 65 °C water bath with mechanical stirring (400 rpm). Weigh 1.6 g of APTES and dissolve it in 40 mL of anhydrous ethanol. Add the solution dropwise to the suspension at a rate of 1 mL / min. After the addition is complete, continue the reaction at 65 °C for 4.5 h. After the reaction, centrifuge the mixture, wash the solid three times with anhydrous ethanol, and dry it at 80 °C for 10 h to obtain amino-functionalized α-zirconium hydrogen phosphate powder.

[0029] Preparation of boron-silicon-zinc hybrid sol: Weigh 5.95 g of zinc nitrate hexahydrate and dissolve it in 100 mL of anhydrous ethanol. Stir for 30 min to obtain solution C. Weigh 0.62 g of boric acid and 2.48 g of APTES and dissolve them in a mixed solvent of 20 mL of deionized water and 80 mL of anhydrous ethanol. Stir for 20 min to obtain solution D. At room temperature and with stirring at 300 rpm, add solution D dropwise at 3 mL / min to a three-necked flask containing solution C. After the addition is complete, place the flask in a 69 °C oil bath and reflux at 400 rpm for 7 h to obtain a translucent sol. After cooling to room temperature, add 0.15 g of acetylacetone and continue stirring for 30 min to obtain the boron-silicon-zinc hybrid sol.

[0030] Preparation of flame-retardant carpet fabric: Add 550g deionized water and 1.0g fatty alcohol polyoxyethylene ether to a beaker and stir at 300rpm for 5min. Add 8.0g of the aforementioned amino-functionalized α-zirconium hydrogen phosphate and 8.0g microencapsulated red phosphorus sequentially, and disperse at 3000rpm for 30min. Reduce the speed to 500rpm, and add 60.0g of an aqueous polyurethane dispersion with a solid content of 40% (24.0g dry matter) and 120.0g of the aforementioned hybrid sol (10% solid content, 12.0g dry matter), stirring for 5min each time, for a total stirring time of 15min. Add 0.30g of polyacrylic acid thickener and stir at 800rpm for 10min to obtain a slurry with a viscosity of approximately 2200mPa·s. Take 100.0g of PA6 tufted base fabric and perform two dip-and-roll processes at a speed of 4m / min, with a roll-off rate of 85%. Pre-dry the wet fabric at 110℃ for 4min, then bake at 168℃ for 3min. After cooling, the product is rolled up to obtain the finished product.

[0031] Example 3 The specific implementation method is the same as in Example 1, except that the amino-functionalized α-zirconium hydrogen phosphate is prepared as follows: 32.2 g of zirconium oxychloride octahydrate is accurately weighed and dissolved in 200 mL of 2 mol / L hydrochloric acid solution. The solution is stirred at 500 rpm for 15 min to obtain a clear zirconium solution. 200 mL of 3 mol / L phosphoric acid solution is measured and added dropwise to the zirconium solution at a rate of 2 mL / min. After the addition is complete, stirring is continued for 30 min. The mixture is transferred to a 500 mL high-pressure reactor, placed in an oven, and heated to 202 °C at 5 °C / min. After crystallization for 36 h, the mixture is cooled with the furnace. The product is collected by centrifugation at 8000 rpm for 10 min, washed with deionized water until neutral, then washed three times with anhydrous ethanol, dried at 80 °C for 12 h, and ground through a 200-mesh sieve to obtain α-zirconium hydrogen phosphate powder. 20.0 g of this powder is dispersed in 200 mL of deionized water and placed in a 75 °C water bath with mechanical stirring (400 rpm). Weigh 2.8 g of APTES and dissolve it in 40 mL of anhydrous ethanol. Add the solution dropwise to the suspension at a rate of 1 mL / min. After the addition is complete, continue the reaction at 75 °C for 5.5 h. After the reaction, centrifuge the mixture, wash the solid three times with anhydrous ethanol, and dry it at 80 °C for 10 h to obtain amino-functionalized α-zirconium hydrogen phosphate powder.

[0032] Preparation of boron-silicon-zinc hybrid sol: Weigh 5.95 g of zinc nitrate hexahydrate and dissolve it in 100 mL of anhydrous ethanol. Stir for 30 min to obtain solution C. Weigh 0.62 g of boric acid and 2.48 g of APTES and dissolve them in a mixed solvent of 20 mL of deionized water and 80 mL of anhydrous ethanol. Stir for 20 min to obtain solution D. Add solution D dropwise at 3 mL / min to a three-necked flask containing solution C while stirring at 300 rpm at room temperature. After the addition is complete, place the flask in a 71 °C oil bath and reflux at 400 rpm for 8 h to obtain a translucent sol. After cooling to room temperature, add 0.25 g of acetylacetone and continue stirring for 30 min to obtain the boron-silicon-zinc hybrid sol.

[0033] Preparation of flame-retardant carpet fabric: Add 450g deionized water and 2.0g fatty alcohol polyoxyethylene ether to a beaker and stir at 300rpm for 5min. Then add 12.0g of the aforementioned amino-functionalized α-zirconium hydrogen phosphate and 12.0g microencapsulated red phosphorus sequentially, and disperse at 3000rpm for 30min. Reduce the speed to 500rpm, and add 40.0g of an aqueous polyurethane dispersion with a solid content of 40% (16.0g dry matter) and 180.0g of the aforementioned hybrid sol (10% solid content, 18.0g dry matter), stirring for 5min each time, for a total stirring time of 15min. Add 0.60g of polyacrylic acid thickener and stir at 800rpm for 10min to obtain a slurry with a viscosity of approximately 2800mPa·s. Take 100.0g of PA6 tufted base fabric and perform a two-dip and two-nip process at a speed of 4m / min, with a nip-out rate of 85%. The damp cloth is pre-dried at 112℃ for 3.5 minutes, and then baked at 172℃ for 2 minutes. After cooling, it is rolled to obtain the finished product.

[0034] Comparative Example 1 The specific implementation method is the same as in Example 1, except that unmodified α-zirconium hydrogen phosphate is used instead of amino-functionalized α-zirconium hydrogen phosphate. The unmodified α-zirconium hydrogen phosphate is prepared according to step A1 of Example 1 (crystallization at 200°C for 24 hours). The fabric preparation slurry composition is: 500g deionized water, 1.5g fatty alcohol polyoxyethylene ether, 10.0g unmodified α-zirconium hydrogen phosphate powder, 10.0g microencapsulated red phosphorus, 50.0g aqueous polyurethane dispersion with a solid content of 40%, 150.0g boron-silicon-zinc hybrid sol prepared by the method in Example 1, and 0.50g polyacrylic acid thickener. The subsequent padding, pre-drying (110°C, 4 min), and baking (170°C, 2.5 min) process parameters are exactly the same as in Example 1.

[0035] Comparative Example 2 The specific implementation method is the same as in Example 1, except that silica sol is used instead of boron-silicon-zinc hybrid sol. This silica sol (purchased from Zhejiang Delixin Micro-Nano Technology Co., Ltd.) has a solid content of 20% and a pH of approximately 9. The fabric preparation sizing composition is as follows: 500g deionized water, 1.5g fatty alcohol polyoxyethylene ether, 10.0g amino-functionalized α-zirconium hydrogen phosphate powder obtained by the method in Example 1, 10.0g microencapsulated red phosphorus, 50.0g aqueous polyurethane dispersion with a solid content of 40%, 75.0g ordinary silica sol (15.0g dry matter to match the solid content), and 0.50g polyacrylic acid thickener. The subsequent padding, pre-drying (110℃, 4min), and baking (170℃, 2.5min) process parameters are exactly the same as in Example 1.

[0036] Comparative Example 3 The specific implementation method is the same as in Example 1, except that only waterborne polyurethane adhesive (purchased from Guangzhou Xingusheng Chemical Technology Co., Ltd.) is used, and it does not contain amino-functionalized α-zirconium hydrogen phosphate and boron-silicon-zinc hybrid sol. The composition of the fabric preparation slurry is: 500g deionized water, 1.5g fatty alcohol polyoxyethylene ether, 50.0g waterborne polyurethane dispersion with a solid content of 40%, and 0.50g polyacrylic acid thickener. The subsequent padding (85% roll-off), pre-drying (110℃, 4min), and baking (170℃, 2.5min) process parameters are exactly the same as in Example 1.

[0037] Performance testing The flame-retardant carpet fabrics prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests according to the following method, which included the following steps: Limiting Oxygen Index (LOI) Test: The sample was cut into 150mm × 58mm specimens and tested using an oxygen index analyzer at a temperature of 23±2℃ and a relative humidity of 50±5%. The specimen was vertically clamped in the center of the fixture inside a transparent combustion cylinder. The oxygen and nitrogen flow rates were adjusted, and the upper part of the specimen was ignited by a flame using a top-ignition method. The minimum oxygen volume concentration percentage required for the specimen to maintain stable flaming combustion for at least 3 minutes or for a damaged length of 50mm in a nitrogen-oxygen mixed gas flow was determined. Five specimens were tested in parallel for each sample, and the results were taken as the arithmetic mean.

[0038] Vertical Burning Test: Cut the sample into 300mm × 80mm specimens, with the long side parallel to the warp or weft direction of the fabric. Under standard temperature and humidity conditions, using a vertical burning tester, place the specimen in a U-shaped stainless steel specimen holder, keeping the specimen vertical. Using a specific-sized blowtorch, adjust the flame height to 40mm, aligning the flame center with the center of the lower edge of the specimen. Ignite the specimen for 12.0 seconds, then remove the flame source. Use a stopwatch to accurately record the afterflame time and smoldering time after removing the flame source, accurate to 0.1s. After all burning and smoldering have stopped, remove the specimen and measure the maximum distance from the top to the bottom of the damaged portion as the damaged length, accurate to 1mm. Test 3 sets of specimens in each direction (warp and weft), and take the average of the results.

[0039] Washability Test: The sample was cut into 300mm × 300mm specimens. A standard household washing machine was used with standard detergent at a liquor ratio of 1:30. The washing program was set to a water temperature of 40℃, and normal agitation was performed for 45 minutes per cycle. After washing, the specimen was removed, rinsed twice with clean water, and then laid flat to dry in an oven not exceeding 60℃, or laid flat to air dry at room temperature. This process was counted as one washing cycle. After 10, 30, and 50 washing cycles, new specimens were cut from the same sample, and their LOI values ​​were re-determined according to the aforementioned Limiting Oxygen Index (LOI) test method. The percentage of LOI value retained after each stage of washing was calculated based on the LOI value of the unwashed original sample.

[0040] Physical property testing: breaking strength and elongation at break testing. Cut the sample into strips of 250mm × 50mm, ensuring the long side is parallel to the warp or weft direction being tested. Apply epoxy resin or perform edge binding on both ends of the sample to prevent slippage or tearing at the clamps. On the universal testing machine, set the initial distance between the two clamps to 100mm and the tensile speed to 100mm / min. Clamp the sample vertically and flat into the clamps and start the test until the sample completely breaks. The equipment automatically records the maximum strength and corresponding elongation at the moment of breakage. Breaking strength is recorded in Newtons, and elongation at break is calculated as a percentage of the original clamping length. Five valid samples are tested in both the warp and weft directions for each sample, and the average value in both directions is calculated. Using the test value of the untreated raw base fabric as 100% as the baseline, calculate the retention rate of breaking strength and elongation at break of the treated sample.

[0041] Abrasion resistance test: Cut the sample into a circular specimen with a diameter of 140 mm, and attach a pad of the same size to the back. Use a Martindale abrasion tester equipped with standard wool felt and standard wool abrasive. Mount the specimen on the test head and apply a pressure of 9.0 kPa. Start the instrument and allow the specimen to rub continuously against the abrasive along a Lissajous pattern. After every 5000 cycles, pause the test, remove the specimen, and observe its surface wear under a standard light source to check for yarn breakage or holes. Then continue the test until at least two or more independent yarn breaks appear on the specimen surface, or a hole with an area greater than 1 mm² appears. 2 The total number of friction cycles at the point of the hole is recorded as the wear resistance rating of the sample, expressed in thousands of cycles. Three points are tested for each sample, and the results are taken as the arithmetic mean.

[0042] Test results: Table 1: Test results of each embodiment and comparative example ; As can be seen from Table 1, Examples 1-3 effectively solved two major technical problems in existing flame-retardant carpet fabrics by using the core technical solutions of amino-functionalized α-zirconium hydrogen phosphate and boron-silicon-zinc hybrid sol, which are due to poor washability caused by weak bonding between flame retardants and fibers, and the serious damage to the physical properties of the fabric caused by excessive addition of fillers in pursuit of flame retardant effect.

[0043] Regarding the bonding strength and washability of the flame retardant, Examples 1-3 maintained a limiting oxygen index retention rate of 90.5-92.0% after 50 washes, demonstrating excellent durability. In contrast, Comparative Example 1 (using non-amine-modified α-zirconium hydrogen phosphate) and Comparative Example 2 (using ordinary silica sol instead of hybrid sol) showed a sharp decrease in retention rates to 60.3% and 67.0%, respectively, after the same number of washes. This significant difference directly proves that the amine functionalization modification enables the amino groups on the surface of zirconium hydrogen phosphate to form strong chemical bonds (such as urea bonds, hydrogen bonds, etc.) with the waterborne polyurethane and hybrid sol network, rather than physical adsorption. At the same time, the boron-silicon-zinc hybrid sol forms a dense covalent network after baking, "anchoring" the flame retardant components to the fiber surface. The synergy of both fundamentally overcomes the problem of the flame retardant layer falling off due to washing and friction, achieving high durability of flame retardant performance.

[0044] In terms of balancing flame retardancy and physical properties, Examples 1-3 achieved a high limiting oxygen index of 32.8-34.2%, and the vertical burning test achieved the highest level of no afterflame and no smoldering. This indicates that the two modified compounds designed have extremely high flame retardancy efficiency, avoiding the need for large amounts of inorganic fillers to meet standards. Meanwhile, Examples 1-3 exhibited a high retention rate of 91-95% in breaking strength and elongation at break, and abrasion resistance of 42-45,000 cycles. Their physical and mechanical properties showed only a slight and acceptable decrease compared to the untreated base fabric (Comparative Example 3), and even improved abrasion resistance, far superior to Comparative Examples 1 and 2. This confirms that amine functionalization improves the dispersibility and compatibility of the flame retardant in the matrix. The hybrid sol, acting as a film-forming substance rather than an inert filler, forms a strong yet flexible integrated coating with the fiber, rather than simply depositing it. This provides excellent flame retardancy while maximizing the preservation of the fabric's soft feel, tensile strength, and durability. In summary, the test data fully demonstrate that this invention, through innovative material design and interface bonding strategy, successfully achieves a balance between high-efficiency and long-lasting flame retardant effect and good maintenance of the fabric's inherent properties, breaking through the contradictory bottlenecks in traditional technologies.

[0045] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a flame-retardant carpet fabric, characterized in that the steps include... include: S1. By weight, add 35-65 parts of deionized water and 0.8-2.5 parts of fatty alcohol polyoxyethylene ether to a stirrer. While stirring continuously, add 6-14 parts of amino-functionalized α-zirconium hydrogen phosphate and 7-13 parts of microencapsulated red phosphorus in sequence. Stir, then add 16-24 parts of waterborne polyurethane and 11-19 parts of boron-silicon-zinc hybrid sol and stir to mix. Add 0.25-0.75 parts of polyacrylic acid thickener to obtain flame retardant slurry. S2. Impregnate the carpet base fabric in flame-retardant slurry to obtain impregnated wet fabric; send the impregnated wet fabric into a hot air oven and pre-dry it at 105-115℃ to obtain pre-dried fabric; transfer the pre-dried fabric to a high-temperature baking machine and bake it at 165-175℃; cool and roll it up.

2. The method for preparing flame-retardant carpet fabric according to claim 1, characterized in that, In step S1, the viscosity of the flame-retardant slurry is 2000-3000 mPa·s.

3. The method for preparing flame-retardant carpet fabric according to claim 1, characterized in that, In step S2, the baking time at 165-175℃ is 2-3 minutes.

4. The method for preparing flame-retardant carpet fabric according to claim 1, characterized in that, The preparation method of the amino-functionalized α-zirconium hydrogen phosphate includes: A1. Dissolve zirconium oxychloride octahydrate in hydrochloric acid to obtain a zirconium solution; add an aqueous phosphoric acid solution dropwise to the zirconium solution while stirring to obtain a mixture; transfer the mixture to a high-pressure reactor and hydrothermally crystallize it at 195-205℃; after natural cooling, centrifuge to obtain a precipitate; wash the precipitate with water and then with ethanol, and dry it at 78-82℃ to obtain crystalline α-zirconium hydrogen phosphate. A2. Disperse crystalline α-zirconium hydrogen phosphate in deionized water, and add anhydrous ethanol solution of 3-aminopropyltriethoxysilane dropwise while stirring at 60-80℃ to obtain a reaction mixture. Centrifuge the reaction mixture to obtain a precipitate. Wash the precipitate with ethanol and dry it at 78-82℃.

5. The method for preparing flame-retardant carpet fabric according to claim 4, characterized in that, In step A1, the hydrothermal crystallization time at 195-205℃ is 24-48 hours.

6. The method for preparing flame-retardant carpet fabric according to claim 4, characterized in that, In step A2, the reaction time for adding anhydrous ethanol solution of 3-aminopropyltriethoxysilane is 4-6 hours.

7. The method for preparing flame-retardant carpet fabric according to claim 1, characterized in that, The preparation method of the boron-silicon-zinc hybrid sol includes: B1. Dissolve zinc nitrate hexahydrate in anhydrous ethanol to obtain a zinc nitrate solution; dissolve boric acid and 3-aminopropyltriethoxysilane in a mixed solvent composed of anhydrous ethanol and deionized water to obtain a mixture; add the mixture dropwise to the zinc nitrate solution while stirring at room temperature to obtain a reaction mixture; B2. Place the reaction mixture in an oil bath at 68-72℃ and stir to obtain a sol. After cooling the sol to room temperature, add acetylacetone and continue stirring.

8. The method for preparing flame-retardant carpet fabric according to claim 7, characterized in that, In step B1, the volume ratio of anhydrous ethanol to deionized water is 4:

1.

9. The method for preparing flame-retardant carpet fabric according to claim 7, characterized in that, In step B2, the stirring reaction time is 5-10 hours.

10. A flame-retardant carpet fabric, characterized in that, The flame-retardant carpet fabric is prepared by the method for preparing flame-retardant carpet fabric according to any one of claims 1-9.