Environment-friendly flame-retardant soundproof carpet base fabric and preparation method thereof

Abstract

This invention discloses an environmentally friendly flame-retardant and sound-insulating carpet substrate fabric and its preparation method in the field of functional textile materials technology. The preparation method includes: preparing a mixture of water-based polyurethane resin, deionized water, organosilicon emulsion, and sodium polycarboxylate; hydrolyzing and activating a coupling agent to obtain a hydrolysate; mixing a phytic acid-calcium stearate synergistically intercalated magnesium aluminum iron base layer bimetallic hydroxide with a nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite and adding it to the mixture, then adding aluminum hydroxide, sepiolite fiber, polyvinyl alcohol fiber, hydrolysate, and thickener, and stirring to obtain a composite slurry; immersing a polyester needle-punched nonwoven fabric in the composite slurry for impregnation-rolling treatment, followed by drying, curing, cross-linking, and room temperature storage to obtain the final product. This invention, through the synergistic effect of two novel inorganic modifying compounds, enables the carpet substrate fabric to possess excellent flame retardancy, sound insulation, and environmental protection properties, making it suitable for building decoration and vehicle interior decoration.

Description

Technical Field

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

[0002] With the increasing demands for indoor environmental quality in modern architecture and the increasingly stringent fire safety regulations, the flame retardant and sound insulation properties of carpets, as an important indoor flooring material, have become key indicators for evaluating product quality. At the same time, the growing environmental awareness of consumers has led to widespread attention being paid to the green sustainability of carpet materials. Traditional carpet substrates typically use synthetic fibers such as polypropylene and polyester. While these fibers possess good processing performance and mechanical strength, they suffer from two major problems: firstly, these materials are highly flammable and release large amounts of dense smoke and toxic gases during combustion, seriously threatening human safety; secondly, the single-fiber structure has limited sound wave dissipation capabilities, making it difficult to meet the stringent sound insulation and noise reduction requirements of modern architecture. To address these issues, researchers have attempted to introduce inorganic flame-retardant fillers such as aluminum hydroxide, magnesium hydroxide, and layered bimetallic hydroxides into the polymer matrix, imparting flame-retardant properties to the material through physical blending. However, the addition of traditional inorganic fillers often faces a dilemma: on the one hand, a high addition amount is required to achieve the desired flame retardant effect; on the other hand, a high addition amount will seriously impair the mechanical properties and processing fluidity of the material, and at the same time, phase separation problems will occur due to the poor compatibility between the filler and the polymer matrix. In recent years, layered bimetallic hydroxides have been regarded as a class of highly promising environmentally friendly flame retardants due to their unique layered structure, intercalation modification characteristics, and endothermic and smoke-reducing mechanism during combustion. However, existing materials of this type still have problems such as poor compatibility with the polymer matrix and uneven dispersion, which limit the full realization of their flame retardant efficiency.

[0003] In terms of sound insulation, existing technologies mostly employ methods such as increasing the surface density of materials or introducing porous structures to dissipate sound waves. However, traditional porous sound insulation materials pose health risks such as fiber shedding and respiratory irritation, and their preparation process is energy-intensive. Hollow glass microspheres, due to their lightweight and hollow structure, possess excellent sound and heat insulation properties and are widely used in functional composite materials. However, as inorganic fillers, hollow glass microspheres also face interfacial compatibility issues, and they lack inherent flame-retardant properties, requiring compounding with other flame retardants, which further increases the complexity of formulation design. Metal-organic frameworks (MOFs) are a new type of porous functional material that has emerged in recent years. They possess ultra-high specific surface area, tunable pore structure, and abundant metal active centers, exhibiting unique advantages in catalysis, adsorption, and electromagnetic wave absorption. Recent research shows that MOFs and their derivatives in polymer matrices can significantly improve the flame-retardant properties of materials through mechanisms such as catalytic char formation and free radical capture, while their hierarchical porous structure has excellent sound dissipation capabilities. However, the dispersion stability of metal-organic framework materials in polymer matrices and their interfacial bonding strength with the matrix remain key technical bottlenecks restricting their application. Based on this background, designing a functional filler that combines high flame retardancy, excellent sound insulation, and good interfacial compatibility, and using this as a basis to construct environmentally friendly carpet substrate fabrics, has become a pressing technical challenge in this field. Summary of the Invention

[0004] The purpose of this invention is to provide an environmentally friendly flame-retardant and sound-insulating carpet substrate fabric and its preparation method, which solves the technical problems of low flame-retardant efficiency, poor sound insulation effect and insufficient interfacial compatibility of existing carpet substrates.

[0005] The present invention achieves the above objectives through the following technical solutions: A method for preparing an environmentally friendly flame-retardant and sound-insulating carpet substrate fabric, comprising the following steps: S1. By weight, place 90-110 parts of waterborne polyurethane resin in a stirrer and stir. Then, add 10-20 parts of deionized water, 0.5-2 parts of silicone emulsion, and 1-3 parts of sodium polycarboxylate salt in sequence, and continue stirring to obtain a mixture. Mix 1-3 parts of γ-glycidyl etheroxypropyltrimethoxysilane with 5-8 parts of deionized water, adjust the pH to 3.5-4.5 with glacial acetic acid, and hydrolyze at room temperature to obtain a hydrolysate. Mix 15-25 parts of phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide with nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite and add it to the mixture. Then, add 10-20 parts of aluminum hydroxide, 5-15 parts of sepiolite fiber, 3-10 parts of polyvinyl alcohol fiber, hydrolysate, and 1-2 parts of waterborne associative polyurethane thickener in sequence, and continue stirring to obtain a composite slurry. S2. The polyester needle-punched nonwoven fabric is immersed in the composite slurry for impregnation-rolling process to obtain the impregnated substrate; the impregnated substrate is dried at 78-82℃ and then placed in an oven at 118-122℃ for curing and cross-linking treatment to obtain the cured fabric; the cured fabric is placed at room temperature.

[0006] In this invention, the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric is prepared using water-based polyurethane resin as the matrix, achieving flame-retardant and sound-insulating functions through synergistic composite technology. First, the coupling agent is pre-hydrolyzed and activated to form a silanol structure, which is then mixed with flame-retardant fillers to ensure a strong interfacial bond between the inorganic fillers and the organic matrix. Flame-retardant components such as phytic acid-calcium stearate synergistically intercalated magnesium aluminum iron base layer bimetallic hydroxide, aluminum hydroxide, sepiolite fiber, and polyvinyl alcohol fiber are uniformly dispersed in the resin, forming a multi-layered flame-retardant network. The impregnation-rolling process allows the composite slurry to fully penetrate the gaps between the polyester needle-punched nonwoven fibers, and the thermosetting treatment cross-links the polyurethane into a film, enhancing the overall structural stability. The synergistic effect of the flexible matrix of water-based polyurethane and the inorganic flame-retardant fillers enables the fabric to maintain good flexibility while possessing excellent flame-retardant and sound-insulating properties. The final product is fully conditioned to humidity equilibrium at room temperature to ensure structural stability and long-term performance, meeting the high standards required for environmentally friendly flame-retardant and sound-insulating carpet substrates.

[0007] According to a preferred embodiment of the present invention, in step S1, the hydrolysis time at room temperature is 15-20 min.

[0008] According to a preferred embodiment of the present invention, in step S2, the curing and crosslinking treatment time is 5-10 min.

[0009] According to a preferred embodiment of the present invention, the method for preparing the phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide includes: A1. By weight, dissolve 20-25 parts of magnesium chloride hexahydrate, 8-10 parts of aluminum chloride hexahydrate, and 2-3 parts of ferric chloride hexahydrate in deionized water to obtain a mixed metal salt solution; dissolve 40-50 parts of sodium hydroxide and 5-6 parts of anhydrous sodium carbonate in deionized water to obtain an alkaline solution; add 10-15 parts of phytic acid and 8.5-10 parts of calcium stearate to the alkaline solution and stir at 78-82℃; add the mixed metal salt solution, adjust the pH, and stir the reaction at 78-82℃ to obtain a slurry; A2. The slurry is aged at 68-72℃, filtered and separated to obtain a solid product; the solid product is washed with deionized water and then washed with anhydrous ethanol to obtain a washed solid product; the washed solid product is dried in a vacuum drying oven at 78-82℃, ground and sieved.

[0010] In this invention, the preparation of phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron layered bimetallic hydroxide is based on a co-precipitation method, where a layered bimetallic hydroxide framework is formed through the reaction of metal salts with alkaline solutions. Magnesium chloride hexahydrate, aluminum chloride hexahydrate, and ferric chloride hexahydrate hydrolyze in an alkaline environment to generate metal hydroxides, forming a layered bimetallic hydroxide structure. Phytic acid, as a polyphenolic acid, has a strong coordinating ability with its phosphate groups and good solubility, allowing it to enter the interlayer via ion exchange. Calcium stearate has low solubility in alkaline aqueous solutions, and its surface slowly releases stearate anions, which synergistically interact with phytic acid anions to enter the LDH interlayer via ion exchange. Simultaneously, undissolved particles are adsorbed onto the surface of the layers, forming a synergistic structure of "surface adsorption-interlayer intercalation." This synergistic intercalation mechanism significantly improves the flame retardant properties of the material. The phosphate groups of phytic acid promote char formation, while the long organic chains of calcium stearate enhance interlayer stability. Together, they enable the material to form a dense protective layer at high temperatures, effectively blocking heat and oxygen transfer.

[0011] According to a preferred embodiment of the present invention, in step A1, the pH is adjusted to 9.0-10.0.

[0012] According to a preferred embodiment of the present invention, in step A2, the slurry is aged at 68-72°C for 12-14 hours.

[0013] According to a preferred embodiment of the present invention, the preparation method of the nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite includes: B1. By weight, mix 150-200 parts anhydrous ethanol and 50-100 parts deionized water, add 5-6 parts glacial acetic acid to adjust the pH to 3.5-4.5, add 5-6 parts 3-aminopropyltriethoxysilane, and hydrolyze at room temperature to obtain a silane hydrolysate; transfer the silane hydrolysate to a round-bottom flask, add hollow glass microspheres, and reflux and stir the reaction at 58-62℃; after the reaction is complete, filter to separate and obtain a solid; wash the solid with anhydrous ethanol and vacuum dry at 58-62℃ to obtain amino-modified hollow glass microspheres; 5.82-6.5 parts of nickel nitrate hexahydrate and 3.62-4.0 parts of 2-aminoterephthalic acid were dissolved in a mixed solvent of 150-200 parts of N,N-dimethylformamide and anhydrous ethanol. Aminated modified hollow glass microspheres were added, and the mixture was ultrasonically dispersed to obtain a suspension. The suspension was transferred to a high-pressure reactor and reacted at 118-122℃. After the reaction was completed, the mixture was naturally cooled to room temperature, and the solid product was collected by centrifugation. The solid product was washed sequentially with N,N-dimethylformamide and anhydrous ethanol, and then vacuum dried at 58-62℃ to obtain composite microspheres. B2. Place the composite microspheres in a tube furnace, heat to 795-805℃ under a nitrogen atmosphere, hold at that temperature, and then allow to cool naturally to room temperature.

[0014] In this invention, the preparation of a nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite employs surface modification and in-situ growth techniques. After treatment with 3-aminopropyltriethoxysilane, amino functional groups form on the surface of the hollow glass microspheres, providing active sites for MOF growth. Nickel nitrate hexahydrate and 2-aminoterephthalic acid coordinate and self-assemble on the microsphere surface, forming a nickel-based metal-organic framework structure. At a relatively high temperature, the MOF grows in situ on the microsphere surface, forming a uniform shell. Subsequently, high-temperature carbonization is performed under a nitrogen atmosphere, transforming the organic ligands into a porous carbon framework, and reducing nickel ions to metal nanoparticles, which are uniformly dispersed in the carbon matrix, forming a core-shell structure. This structure not only maintains the lightweight properties of the microspheres but also endows the material with excellent electrical conductivity, catalytic carbonization ability, and electromagnetic wave absorption properties, providing crucial support for flame-retardant and sound-insulating functions.

[0015] According to a preferred embodiment of the present invention, in step B1, the reaction time at 118-122°C is 24-30 h.

[0016] According to a preferred embodiment of the present invention, in step B2, the time for holding the temperature at 795-805°C is 2-4 hours.

[0017] The present invention also provides an environmentally friendly flame-retardant and sound-insulating carpet substrate fabric prepared according to the preparation method of the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric.

[0018] The beneficial effects of this invention are as follows: This invention significantly improves the flame retardancy, sound insulation, and environmental friendliness of carpet substrate fabrics by designing two novel inorganic modified compounds and optimizing their preparation process. Regarding flame retardancy, in the phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide, phytic acid anions release phosphate groups during combustion, promoting the formation of a dense char layer in the polymer matrix. Simultaneously, calcium ions in calcium stearate synergistically construct a calcium-phosphate composite char layer with higher thermal stability, effectively blocking heat and oxygen transfer. The nickel-doped metal-organic framework-derived porous carbon hollow glass microsphere core-shell composite generates nickel nanoparticles uniformly distributed within the porous carbon framework during carbonization. These nickel nanoparticles catalyze the accelerated char formation of the polymer matrix in the early stages of combustion, forming a synergistic flame retardant mechanism of "early-stage catalytic char formation - later-stage char layer strengthening." The synergistic effect of the two modified compounds significantly reduces the heat release rate during combustion, effectively suppresses flame spread, and substantially reduces smoke production, aligning with the development direction of environmentally friendly flame-retardant materials.

[0019] In terms of sound insulation performance, this invention fully leverages the complementary structural advantages of the two modified compounds. The phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron layered bimetallic hydroxide exhibits a typical layered structure, where sound waves undergo multiple reflections and refractions at the interlayer interfaces, increasing the sound energy dissipation path. The nickel-doped metal-organic framework-derived porous carbon hollow glass microsphere core-shell composite combines the efficient sound dissipation effect of the hollow structure of the hollow glass microspheres with the viscous absorption effect of the hierarchical porous structure of the metal-organic framework-derived porous carbon. The combination of these two structural units allows sound waves to undergo multiple mechanisms within the material: "hollow cavity resonance dissipation - porous channel viscous dissipation - layered interface reflection dissipation," significantly improving the material's sound insulation performance in the mid-to-low frequency range. Furthermore, the addition of sepiolite fibers further enhances the porous network structure of the material, forming a multi-scale, multi-mechanism sound insulation network with the two modified compounds, enabling the resulting carpet substrate fabric to maintain its lightweight characteristics while possessing excellent noise reduction capabilities.

[0020] In terms of environmental friendliness and overall performance, neither of the two modified compounds used in this invention contains halogen elements, and they do not produce toxic or harmful gases such as dioxins or hydrogen halides during combustion. The use of waterborne polyurethane resin completely avoids the volatile organic compound emissions problems associated with traditional solvent-based adhesives, and the overall formulation meets the stringent requirements for green and environmentally friendly materials. Simultaneously, this invention significantly improves the interfacial compatibility between the inorganic filler and the polymer matrix through pre-hydrolysis activation treatment with coupling agents and the design of the surface structures of the two modified compounds. This allows the filler to achieve nanoscale uniform dispersion in the resin, avoiding the phase separation and mechanical property degradation problems commonly found in traditional high-filler systems. The resulting carpet substrate fabric maintains excellent flame retardant and sound insulation properties while also possessing good tensile strength and elongation at break, meeting the mechanical performance requirements of carpet substrates in practical use. It can be widely used in residential buildings, commercial spaces, vehicle interior decoration, and public places with special requirements for fire prevention and noise reduction. Detailed Implementation

[0021] 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.

[0022] Example 1 This embodiment provides a method for preparing an environmentally friendly, flame-retardant, and sound-insulating carpet substrate fabric, the steps of which include: S1. Place 100g of waterborne polyurethane resin in a stirrer, and add 15g of deionized water, 1g of silicone emulsion (purchased from Guangzhou Qifu Biotechnology Co., Ltd.), and 2g of sodium polycarboxylate (purchased from Hubei Hongxin Ruiyu Fine Chemical Co., Ltd.) sequentially while stirring at 900rpm. Continue stirring for 10min to obtain a mixture. Mix 2g of γ-glycidyl etheroxypropyltrimethoxysilane with 6g of deionized water, adjust the pH to 4.0 with glacial acetic acid, and hydrolyze for 18min at room temperature to obtain a hydrolysate. Add 20g of phytic acid-stearin... A calcium-acid synergistic intercalated magnesium-aluminum-iron base layer bimetallic hydroxide and 18g of nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite were premixed uniformly at a weight ratio of 1:0.9. The mixture was added to the above mixture in three portions, and the rotation speed was increased to 1500 rpm and dispersed for 15 min after each addition. Then, 15g of aluminum hydroxide, 10g of sepiolite fiber, 6g of polyvinyl alcohol fiber, the above hydrolysate and 1.5g of water-based associative polyurethane thickener were added in sequence, and the mixture was dispersed at 1200 rpm for 30 min to obtain the composite slurry.

[0023] S2, with a surface density of 180 g / m² 2 Polyester needle-punched nonwoven fabric is immersed in a composite slurry for impregnation-rolling process. The impregnation time is 30s and the roll-off rate is 70%, resulting in an impregnated substrate. The impregnated substrate is pre-dried at 80℃ for 10min and then placed in a 120℃ oven for curing and cross-linking treatment for 8min, resulting in a cured fabric. The cured fabric is placed at room temperature for 24h to fully adjust the humidity, thus obtaining the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric.

[0024] Preparation of phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide: A1. Dissolve 22g magnesium chloride hexahydrate, 9g aluminum chloride hexahydrate, and 2.5g ferric chloride hexahydrate in 500mL of deionized water to prepare a mixed metal salt solution; dissolve 45g sodium hydroxide and 5.5g anhydrous sodium carbonate in 500mL of deionized water to prepare an alkaline solution; add 12g of 70% phytic acid aqueous solution and 9g of calcium stearate to the alkaline solution, and stir vigorously in an 80℃ water bath to fully disperse and emulsify the calcium stearate; add the mixed metal salt solution dropwise to the alkaline solution containing phytic acid and calcium stearate at a rate of 3mL / min, maintaining the pH of the solution at 9.5 during the dropwise addition, adjusting by adding 1mol / L sodium hydroxide solution; after the dropwise addition is complete, continue stirring at 80℃ for 2h. During the reaction, the stearate anions released from the surface of the calcium stearate particles and the phytate anions enter the LDH interlayer through synergistic effects of ion exchange and surface adsorption, forming a synergistic intercalation structure to obtain the slurry.

[0025] A2. The slurry was aged at 70℃ for 12 hours, filtered, and the solid product was obtained. The solid product was washed with hot deionized water at 70℃ until the pH of the filtrate was 7.0, and then washed twice with anhydrous ethanol to obtain the washed solid product. The washed solid product was placed in a vacuum drying oven at 80℃ for 24 hours and ground through a 500-mesh sieve to obtain the phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide.

[0026] Preparation of nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composites: B1. Take 11g of hollow glass microspheres for later use; mix 180g of anhydrous ethanol and 80g of deionized water, add 5.5g of glacial acetic acid to adjust the pH to 4.0, add 5.5g of 3-aminopropyltriethoxysilane, and hydrolyze and activate at room temperature for 10min to obtain silane hydrolysate; transfer the silane hydrolysate to a round-bottom flask, add the prepared hollow glass microspheres, and reflux and stir at 60℃ for 6h to perform surface amination modification. After the reaction, filter and separate, wash three times with anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain amination-modified hollow glass microspheres; add 6.2g of nitro hexahydrate... Nickel oxide and 3.8 g of 2-aminoterephthalic acid were dissolved in a mixed solvent of 180 g of N,N-dimethylformamide and anhydrous ethanol in a volume ratio of 3:1. 10 g of aminated modified hollow glass microspheres were added, and the mixture was ultrasonically dispersed for 30 min to obtain a suspension. The suspension was transferred to a high-pressure reactor and reacted at 120 °C for 26 h. After the reaction was completed, the mixture was naturally cooled to room temperature, and the solid product was collected by centrifugation. The solid product was washed three times each with N,N-dimethylformamide and anhydrous ethanol, and then vacuum dried at 60 °C for 12 h to obtain composite microspheres with an in-situ grown Ni-MOF-NH2 shell.

[0027] B2. The composite microspheres are placed in a tube furnace and heated to 800°C at a heating rate of 5°C / min under a nitrogen atmosphere. The mixture is then held at the temperature for 3 hours for carbonization. During the carbonization process, the Ni-MOF-NH2 layer is converted into nickel-doped porous carbon. The mixture is then naturally cooled to room temperature to obtain the nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite.

[0028] Example 2 The specific implementation method is the same as in Example 1, except that this example provides a method for preparing an environmentally friendly flame-retardant and sound-insulating carpet substrate fabric, the steps of which include: S1. Place 90g of waterborne polyurethane resin in a stirrer, and add 10g of deionized water, 0.5g of silicone emulsion, and 1g of sodium polycarboxylate salt sequentially under stirring at 800rpm. Continue stirring for 10min to obtain a mixture. Mix 1g of γ-glycidyl etheroxypropyltrimethoxysilane with 5g of deionized water, adjust the pH to 3.5 with glacial acetic acid, and hydrolyze at room temperature for 15min to obtain a hydrolysate. Premix 15g of phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide with 12g of nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite at a weight ratio of 1:0.8. Add the mixture to the above mixture in three portions, increasing the speed to 1500rpm and dispersing for 15min after each addition. Then add 10g of aluminum hydroxide, 5g of sepiolite fiber, 3g of polyvinyl alcohol fiber, the above hydrolysate, and 1g of waterborne associative polyurethane thickener sequentially, and continue dispersing at 1200rpm for 30min to obtain a composite slurry.

[0029] S2, with a surface density of 150 g / m³ 2 Polyester needle-punched nonwoven fabric is immersed in a composite slurry for impregnation-rolling process. The impregnation time is 30s and the roll-off rate is 65%, resulting in an impregnated substrate. The impregnated substrate is pre-dried at 78℃ for 10min and then placed in an oven at 118℃ for curing and cross-linking treatment for 5min, resulting in a cured fabric. The cured fabric is placed at room temperature for 24h to fully adjust the humidity and achieve equilibrium, thus obtaining the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric.

[0030] Preparation of phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide: A1. Dissolve 20g magnesium chloride hexahydrate, 8g aluminum chloride hexahydrate, and 2g ferric chloride hexahydrate in 500mL of deionized water to prepare a mixed metal salt solution; dissolve 40g sodium hydroxide and 5g anhydrous sodium carbonate in 500mL of deionized water to prepare an alkaline solution; add 10g of 70% phytic acid aqueous solution and 8.5g of calcium stearate to the alkaline solution, and stir vigorously in a 78℃ water bath to fully disperse and emulsify the calcium stearate; add the mixed metal salt solution dropwise to the alkaline solution containing phytic acid and calcium stearate at a rate of 3mL / min, maintaining the pH of the solution at 9.0 during the dropwise addition, adjusting by adding 1mol / L sodium hydroxide solution; after the dropwise addition is complete, continue stirring at 78℃ for 2h. During the reaction, the stearate anions released from the surface of the calcium stearate particles and the phytate anions enter the LDH interlayer through synergistic effects of ion exchange and surface adsorption, forming a synergistic intercalation structure to obtain the slurry.

[0031] A2. The slurry was aged at 68℃ for 13 hours, filtered, and the solid product was obtained. The solid product was washed with hot deionized water at 70℃ until the pH of the filtrate was 7.0, and then washed twice with anhydrous ethanol to obtain the washed solid product. The washed solid product was placed in a vacuum drying oven at 78℃ for 24 hours and ground through a 500-mesh sieve to obtain the phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide.

[0032] Preparation of nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composites: B1. Take 10g of hollow glass microspheres for later use; mix 150g of anhydrous ethanol and 50g of deionized water, add 5g of glacial acetic acid to adjust the pH to 3.5, add 5g of 3-aminopropyltriethoxysilane, and hydrolyze and activate at room temperature for 10min to obtain silane hydrolysate; transfer the silane hydrolysate to a round-bottom flask, add the prepared hollow glass microspheres, and reflux and stir at 58℃ for 6h to perform surface amination modification. After the reaction, filter and separate, wash three times with anhydrous ethanol, and vacuum dry at 58℃ for 12h to obtain amination-modified hollow glass microspheres; add 5.82g of nickel nitrate hexahydrate. 3.62 g of 2-aminoterephthalic acid was dissolved in a mixed solvent of 150 g of N,N-dimethylformamide and anhydrous ethanol in a volume ratio of 3:1. 10 g of aminated modified hollow glass microspheres were added, and the mixture was ultrasonically dispersed for 30 min to obtain a suspension. The suspension was transferred to a high-pressure reactor and reacted at 118 °C for 24 h. After the reaction was completed, the mixture was naturally cooled to room temperature, and the solid product was collected by centrifugation. The solid product was washed three times each with N,N-dimethylformamide and anhydrous ethanol, and then vacuum dried at 58 °C for 12 h to obtain composite microspheres with an in-situ grown Ni-MOF-NH2 shell.

[0033] B2. The composite microspheres are placed in a tube furnace and heated to 795°C at a heating rate of 5°C / min under a nitrogen atmosphere. The mixture is then held at the temperature for 2 hours for carbonization. During the carbonization process, the Ni-MOF-NH2 layer is converted into nickel-doped porous carbon. The mixture is then naturally cooled to room temperature to obtain the nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite.

[0034] Example 3 The specific implementation method is the same as in Example 1, except that this example provides a method for preparing an environmentally friendly flame-retardant and sound-insulating carpet substrate fabric, the steps of which include: S1. Place 110g of waterborne polyurethane resin in a stirrer, and add 20g of deionized water, 2g of silicone emulsion, and 3g of sodium polycarboxylate salt sequentially under stirring at 1000rpm. Continue stirring for 10min to obtain a mixture. Mix 3g of γ-glycidyl etheroxypropyltrimethoxysilane with 8g of deionized water, adjust the pH to 4.5 with glacial acetic acid, and hydrolyze at room temperature for 20min to obtain a hydrolysate. Premix 25g of phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide and 22g of nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite at a weight ratio of 1:1.2. Add the mixture to the above mixture in three portions, increasing the speed to 1500rpm and dispersing for 15min after each addition. Then add 20g of aluminum hydroxide, 15g of sepiolite fiber, 10g of polyvinyl alcohol fiber, the above hydrolysate, and 2g of waterborne associative polyurethane thickener sequentially, and continue dispersing at 1200rpm for 30min to obtain a composite slurry.

[0035] S2, with a surface density of 200g / m³ 2 Polyester needle-punched nonwoven fabric is immersed in a composite slurry for impregnation-rolling process. The impregnation time is 30s and the roll-off rate is 75%, resulting in an impregnated substrate. The impregnated substrate is pre-dried at 82℃ for 10min and then placed in a 122℃ oven for curing and cross-linking treatment for 10min to obtain a cured fabric. The cured fabric is placed at room temperature for 24h to fully adjust the humidity and achieve equilibrium, thus obtaining the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric.

[0036] Preparation of phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide: A1. Dissolve 25g magnesium chloride hexahydrate, 10g aluminum chloride hexahydrate, and 3g ferric chloride hexahydrate in 500mL of deionized water to prepare a mixed metal salt solution; dissolve 50g sodium hydroxide and 6g anhydrous sodium carbonate in 500mL of deionized water to prepare an alkaline solution; add 15g of 70% phytic acid aqueous solution and 10g of calcium stearate to the alkaline solution, and stir vigorously in an 82℃ water bath to fully disperse and emulsify the calcium stearate; add the mixed metal salt solution dropwise to the alkaline solution containing phytic acid and calcium stearate at a rate of 3mL / min, maintaining the pH of the solution at 10.0 during the dropwise addition, adjusting by adding 1mol / L sodium hydroxide solution; after the dropwise addition is complete, continue stirring at 82℃ for 2h. During the reaction, the stearate anions released from the surface of the calcium stearate particles and the phytate anions enter the LDH interlayer through synergistic effects of ion exchange and surface adsorption, forming a synergistic intercalation structure to obtain the slurry.

[0037] A2. The slurry was aged at 72℃ for 14 hours, filtered, and the solid product was obtained. The solid product was washed with hot deionized water at 70℃ until the pH of the filtrate was 7.0, and then washed twice with anhydrous ethanol to obtain the washed solid product. The washed solid product was placed in a vacuum drying oven at 82℃ for 24 hours and ground through a 500-mesh sieve to obtain the phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide.

[0038] Preparation of nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composites: B1. Take 12g of hollow glass microspheres for later use; mix 200g of anhydrous ethanol and 100g of deionized water, add 6g of glacial acetic acid to adjust the pH to 4.5, add 6g of 3-aminopropyltriethoxysilane, and hydrolyze and activate at room temperature for 10min to obtain silane hydrolysate; transfer the silane hydrolysate to a round-bottom flask, add the prepared hollow glass microspheres, and reflux and stir at 62℃ for 6h to perform surface amination modification. After the reaction, filter and separate, wash three times with anhydrous ethanol, and vacuum dry at 62℃ for 12h to obtain amination-modified hollow glass microspheres; add 6.5g of nickel nitrate hexahydrate. 4.0 g of 2-aminoterephthalic acid was dissolved in a mixed solvent of 200 g of N,N-dimethylformamide and anhydrous ethanol in a volume ratio of 3:1. 10 g of aminated modified hollow glass microspheres were added, and the mixture was ultrasonically dispersed for 30 min to obtain a suspension. The suspension was transferred to a high-pressure reactor and reacted at 122 °C for 30 h. After the reaction was completed, the mixture was naturally cooled to room temperature, and the solid product was collected by centrifugation. The solid product was washed three times each with N,N-dimethylformamide and anhydrous ethanol, and then vacuum dried at 62 °C for 12 h to obtain composite microspheres with an in-situ grown Ni-MOF-NH2 shell.

[0039] B2. The composite microspheres are placed in a tube furnace and heated to 805°C at a heating rate of 5°C / min under a nitrogen atmosphere. The mixture is then held at the temperature for carbonization for 4 hours. During the carbonization process, the Ni-MOF-NH2 layer is converted into nickel-doped porous carbon. The mixture is then naturally cooled to room temperature to obtain the nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite.

[0040] Comparative Example 1 The specific implementation method is the same as in Example 1, except that phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide is not added. In step S1, 38g of nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite is used to replace the total amount of phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide and nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite added in Example 1. Other raw materials, dosages, and operating steps are the same as in Example 1.

[0041] Comparative Example 2 The specific implementation method is the same as in Example 1, except that nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite is not added. In step S1, 38g of phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide is used to replace the total amount of the two modified compounds added in Example 1. Other raw materials, dosages, and operating steps are the same as in Example 1.

[0042] Comparative Example 3 The specific implementation method is the same as in Example 1, except that ordinary aluminum hydroxide and hollow glass microspheres are used instead of the phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron stratified bimetallic hydroxide and the nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite. In step S1, 20g of aluminum hydroxide and 18g of hollow glass microspheres are used instead of the phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron stratified bimetallic hydroxide and the nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite in Example 1. Other raw materials, dosages, and operating steps are the same as in Example 1.

[0043] Performance testing The environmentally friendly flame-retardant and sound-insulating carpet substrate fabrics prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests according to the following methods, which included the following steps: Limiting oxygen index test: Cut the sample into rectangular strips 150 mm long and 58 mm wide, and take 5 samples for each sample. Install the sample vertically in the sample holder and place it in the combustion chamber. Adjust the total flow rate of the oxygen and nitrogen mixture to 40 L / min. Starting with an oxygen concentration of 18% by volume, gradually adjust the oxygen concentration in increments of 0.2% until the sample can maintain combustion in the combustion chamber for more than 3 minutes or the combustion length reaches 50 mm. Record the oxygen concentration value, and use the arithmetic mean of the 5 samples as the limiting oxygen index.

[0044] Vertical Burning Test: Cut the sample into rectangular strips 300mm long and 80mm wide, and take 5 samples for each sample. Fix the sample vertically on the sample holder, adjust the Bunsen burner flame height to 20mm, apply the flame for 12s, and record the afterflame time after removing the flame. Record the smoldering time after the afterflame ends. At the same time, observe whether molten droplets are generated during the sample combustion process and whether the molten droplets ignite the degreased cotton placed 300mm below the sample. Evaluate the vertical burning rating according to the grading criteria specified in the standard based on the afterflame time, smoldering time, and molten droplet ignition. The worst rating among the 5 samples is taken as the final rating.

[0045] Smoke density test: The sample was cut into square specimens 75mm long and 75mm wide, with 3 specimens taken from each sample. A smoke density chamber was used for testing. The specimens were placed horizontally on a specimen holder, and the radiant heat flux was set to 25kW / m².2 Thermal radiation heating is performed without an external flame. The optical system consists of a light source and a photovoltaic cell. The light source is an incandescent lamp, and the photovoltaic cell receives the transmitted light intensity. The data acquisition system records the change curve of light transmittance over time. The maximum smoke density value is the difference between the percentage when the light transmittance drops to the lowest point during the test and 100%. The smoke density level is calculated based on the area under the curve of light transmittance over time, and the arithmetic mean of three samples is used as the final result.

[0046] Weighted sound insulation test: The sample is cut into rectangular specimens 1000mm long and 800mm wide, with 3 specimens for each sample. The specimens are tightly installed in the sound insulation test window frame, ensuring no gaps at the edges. Steady-state noise is generated in the sound source chamber, and the sound pressure level is measured by a microphone. The sound pressure level difference is measured in the receiving chamber, and the reverberation time in the receiving chamber is also measured. The sound insulation is measured at the center frequency of each one-third octave band in the range of 100Hz to 3150Hz. The sound insulation of each frequency band is fitted according to the standard reference curve to determine the weighted sound insulation. The arithmetic mean of the 3 specimens is taken as the final result.

[0047] Noise reduction coefficient test: The sample was cut into circular specimens with a diameter of 100mm, and three specimens were taken for each sample. The standing wave tube method was used for testing. The specimen was placed at the end of the standing wave tube, and a pure tone sound wave with an adjustable frequency was generated in the standing wave tube. The standing wave ratio was measured by moving the probe, and the sound absorption coefficient was calculated. The sound absorption coefficients were measured at four frequencies: 250Hz, 500Hz, 1000Hz, and 2000Hz. The arithmetic mean of the sound absorption coefficients at the four frequencies was taken as the noise reduction coefficient, and the arithmetic mean of the three specimens was taken as the final result.

[0048] Tensile strength test: Cut the specimen into rectangular strips 200 mm long and 50 mm wide, and take 5 specimens for each sample. Use a constant speed elongation tensile testing machine, set the interval length to 100 mm, the tensile speed to 100 mm / min, clamp both ends of the specimen in the upper and lower clamps respectively, start the testing machine to stretch until the specimen breaks, record the maximum strength value at fracture, and take the arithmetic mean of 5 specimens as the tensile strength.

[0049] Elongation at break test: Cut the specimen into rectangular strips 200 mm long and 50 mm wide, and take 5 specimens for each sample. Use a constant speed elongation tensile testing machine, set the spacing length to 100 mm, and the tensile speed to 100 mm / min. Clamp both ends of the specimen in the upper and lower fixtures respectively, start the testing machine to stretch until the specimen breaks, and record the percentage of the distance the fixtures moved at break to the initial spacing length. The arithmetic mean of the 5 specimens is taken as the elongation at break.

[0050] Test results: Table 1: Test results of each embodiment and comparative example ; As can be seen from Table 1, the phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide and nickel-doped metal-organic framework derived porous carbon hollow glass microsphere core-shell composite designed and prepared in this invention significantly solves the technical problems of low flame retardancy efficiency, poor sound insulation effect and insufficient interface compatibility of existing carpet substrates when used in synergy.

[0051] In terms of flame retardant performance, the limiting oxygen indices of Examples 1-3 reached 34.2%, 32.8%, and 35.1%, respectively, which were significantly higher than those of Comparative Example 1 (27.6%), Comparative Example 2 (28.4%), and Comparative Example 3 (23.5%). Furthermore, all examples achieved a vertical combustion V-0 rating, with afterflame time and smoldering time of 0 seconds or only 1 second. In contrast, Comparative Examples 1 and 2 were only V-2 ratings, and Comparative Example 3 even had no flame retardant rating. This indicates that the flame retardant efficiency drops significantly when either modified compound is used alone. A simple mixture of ordinary aluminum hydroxide and hollow glass microspheres can hardly provide effective flame retardant protection. Only when the two modified compounds work synergistically can efficient flame retardancy be achieved in the early stages of combustion through multiple mechanisms, including phytate anions promoting the formation of a dense char layer, calcium ions and phosphate ions constructing a calcium-phosphorus composite char layer with higher thermal stability, and nickel nanoparticles catalyzing the polymer matrix to accelerate char formation. In terms of sound insulation performance, the weighted sound insulation values ​​of Examples 1 to 3 were 24, 22 and 25, respectively, and the noise reduction coefficients were 0.42, 0.38 and 0.45, respectively. These were significantly better than those of Comparative Example 1 (16 and 0.26), Comparative Example 2 (17 and 0.28), and Comparative Example 3 (14 and 0.22). This is due to the interfacial reflection and dissipation of sound waves by the layered structure provided by the two modified compounds, and the resonant dissipation and viscous absorption of sound energy by the hollow structure of hollow glass microspheres and the multi-level porous carbon structure derived from metal-organic framework. The two compounds form a wide-band sound insulation network from low frequency to mid frequency. However, when used alone, the sound insulation effect is obviously insufficient because the single mechanism is difficult to cover the wide-band sound waves. From a mechanical property perspective, the tensile strengths of Examples 1-3 were 8.6 MPa, 7.9 MPa, and 9.2 MPa, respectively, and the elongation at break were 42%, 38%, and 45%, respectively. These were significantly higher than those of Comparative Example 1 (6.1 MPa and 29%), Comparative Example 2 (6.3 MPa and 31%), and Comparative Example 3 (5.2 MPa and 24%). This indicates that the intercalation of calcium stearate between the layered bimetallic hydroxide layers effectively improved the interfacial compatibility between the inorganic filler and the polymer matrix. The metal-organic framework-derived porous carbon shell and the hollow glass microspheres... The chemical bonding of the surface ensures the stability of the core-shell structure. In addition, the pre-hydrolysis activation treatment of the coupling agent enables the silanol and the hydroxyl groups on the filler surface to fully condense and form chemical bonds, thereby achieving uniform dispersion and firm bonding of inorganic fillers in the polymer matrix. This effectively solves the problem of mechanical property degradation caused by poor interfacial compatibility in traditional high-filler systems. Therefore, this invention comprehensively solves the core problems of the prior art from three dimensions: flame retardancy, sound insulation and mechanical properties through the molecular structure design, surface chemical modification and synergistic mechanism of two novel inorganic modified compounds.

[0052] 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 an environmentally friendly flame-retardant and sound-insulating carpet substrate fabric, characterized in that the steps include... include: S1. By weight, place 90-110 parts of waterborne polyurethane resin in a stirrer and stir. Then, add 10-20 parts of deionized water, 0.5-2 parts of silicone emulsion, and 1-3 parts of sodium polycarboxylate salt in sequence, and continue stirring to obtain a mixture. Mix 1-3 parts of γ-glycidyl etheroxypropyltrimethoxysilane with 5-8 parts of deionized water, adjust the pH to 3.5-4.5 with glacial acetic acid, and hydrolyze at room temperature to obtain a hydrolysate. Mix 15-25 parts of phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base layer bimetallic hydroxide with nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite and add it to the mixture. Then, add 10-20 parts of aluminum hydroxide, 5-15 parts of sepiolite fiber, 3-10 parts of polyvinyl alcohol fiber, hydrolysate, and 1-2 parts of waterborne associative polyurethane thickener in sequence, and continue stirring to obtain a composite slurry. S2. The polyester needle-punched nonwoven fabric is immersed in the composite slurry for impregnation-rolling process to obtain the impregnated substrate; the impregnated substrate is dried at 78-82℃ and then placed in an oven at 118-122℃ for curing and cross-linking treatment to obtain the cured fabric; the cured fabric is placed at room temperature.

2. The method for preparing the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric according to claim 1, characterized in that, In step S1, the hydrolysis time at room temperature is 15-20 min.

3. The method for preparing the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric according to claim 1, characterized in that, In step S2, the curing and crosslinking treatment time is 5-10 minutes.

4. The method for preparing the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric according to claim 1, characterized in that, The method for preparing the phytic acid-calcium stearate synergistic intercalated magnesium aluminum iron base-like bimetallic hydroxide includes: A1. By weight, dissolve 20-25 parts of magnesium chloride hexahydrate, 8-10 parts of aluminum chloride hexahydrate, and 2-3 parts of ferric chloride hexahydrate in deionized water to obtain a mixed metal salt solution; dissolve 40-50 parts of sodium hydroxide and 5-6 parts of anhydrous sodium carbonate in deionized water to obtain an alkaline solution; add 10-15 parts of phytic acid and 8.5-10 parts of calcium stearate to the alkaline solution and stir at 78-82℃; add the mixed metal salt solution, adjust the pH, and stir the reaction at 78-82℃ to obtain a slurry; A2. The slurry is aged at 68-72℃, filtered and separated to obtain a solid product; the solid product is washed with deionized water and then washed with anhydrous ethanol to obtain a washed solid product; the washed solid product is dried in a vacuum drying oven at 78-82℃, ground and sieved.

5. The method for preparing the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric according to claim 4, characterized in that, In step A1, adjust the pH to 9.0-10.

0.

6. The method for preparing the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric according to claim 4, characterized in that, In step A2, the slurry is aged at 68-72℃ for 12-14 hours.

7. The method for preparing the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric according to claim 1, characterized in that, The preparation method of the nickel-doped MOF-derived porous carbon-hollow glass microsphere core-shell composite includes: B1. By weight, mix 150-200 parts anhydrous ethanol and 50-100 parts deionized water, add 5-6 parts glacial acetic acid to adjust the pH to 3.5-4.5, add 5-6 parts 3-aminopropyltriethoxysilane, and hydrolyze at room temperature to obtain a silane hydrolysate; transfer the silane hydrolysate to a round-bottom flask, add hollow glass microspheres, and reflux and stir the reaction at 58-62℃; after the reaction is complete, filter to separate and obtain a solid; wash the solid with anhydrous ethanol and vacuum dry at 58-62℃ to obtain amino-modified hollow glass microspheres; 5.82-6.5 parts of nickel nitrate hexahydrate and 3.62-4.0 parts of 2-aminoterephthalic acid were dissolved in a mixed solvent of 150-200 parts of N,N-dimethylformamide and anhydrous ethanol. Aminated modified hollow glass microspheres were added, and the mixture was ultrasonically dispersed to obtain a suspension. The suspension was transferred to a high-pressure reactor and reacted at 118-122℃. After the reaction was completed, the mixture was naturally cooled to room temperature, and the solid product was collected by centrifugation. The solid product was washed sequentially with N,N-dimethylformamide and anhydrous ethanol, and then vacuum dried at 58-62℃ to obtain composite microspheres. B2. Place the composite microspheres in a tube furnace, heat to 795-805℃ under a nitrogen atmosphere, hold at that temperature, and then allow to cool naturally to room temperature.

8. The method for preparing the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric according to claim 7, characterized in that, In step B1, the reaction time is 24-30 hours at 118-122°C.

9. The method for preparing the environmentally friendly flame-retardant and sound-insulating carpet substrate fabric according to claim 7, characterized in that, In step B2, the temperature is raised to 795-805℃ and held for 2-4 hours.

10. An environmentally friendly, flame-retardant, and sound-insulating carpet substrate fabric, characterized in that, The environmentally friendly flame-retardant and sound-insulating carpet substrate fabric is prepared by the method described in any one of claims 1-9.