Flame resistant composite fabric having a three-dimensional interlocking gradient structure and methods of making the same

Abstract

The application belongs to the technical field of flame-retardant fabrics, and particularly relates to a flame-retardant composite fabric with a three-dimensional interlocking gradient structure and a preparation method thereof, which comprises a three-dimensional fiber skeleton and a nano-hybrid flame-retardant network; the three-dimensional fiber skeleton is a flame-retardant fiber fabric which is modified by low-temperature plasma and has a silane coupling bridge layer grafted on the surface; the nano-hybrid flame-retardant network is formed by in-situ crosslinking of transition metal carbide nanosheets and polyamide acid precursors, and is filled in the gaps of the three-dimensional fiber skeleton; and the nano-hybrid flame-retardant network is asymmetrically distributed in a gradient on the three-dimensional fiber skeleton and is anchored through covalent bonding, forming a three-dimensional interlocking interpenetrating network structure.

Description

Technical Field

[0001] This invention belongs to the field of flame-retardant fabric technology, specifically relating to a flame-retardant composite fabric with a three-dimensional interlocking gradient structure and its preparation method. Background Technology

[0002] With the rapid development of the automotive industry and the increasing demands for vehicle safety, the flame-retardant properties of automotive interior materials have gradually become a crucial factor to consider in automotive design and manufacturing. Interior components such as car seats, door panels, and headliners typically use fabric materials, which, while providing comfort and aesthetics, also require extremely high thermal safety performance.

[0003] Currently, most commercially available flame-retardant fabrics for automotive interiors employ a three-layer physical composite structure: a surface fabric, a middle flame-retardant layer, and a bottom support layer. The middle flame-retardant layer is typically composed of a simple composite of flame-retardant fibers and expanded graphite particles. However, in practical applications, this traditional structure has been found to have the following significant drawbacks: Poor interfacial bonding stability: Traditional physical laminated structures mainly rely on hot-pressing or adhesive bonding for connection. Under the long-term vibration, bumps and high and low temperature cycling environment of automobiles, fatigue peeling or delamination can easily occur between the layers, leading to the failure of the overall material structure.

[0004] The flame-retardant char layer is not strong enough. The char layer structure formed by the expanded graphite microparticles (usually with a particle size of 50μm to 200μm) used in the traditional structure after being heated is relatively loose. In the event of a sudden fire, it is easy to break and scatter under the scouring of hot air, making it difficult to form a continuous and stable thermal shield barrier.

[0005] The contradiction between comfort and function: In order to achieve a high flame retardant rating, traditional solutions often need to increase the thickness of the intermediate flame retardant layer (usually 1mm to 4mm) or increase the amount of flame retardant filling. This will result in the overall composite material becoming harder, too thick, and heavier, making it difficult to meet the needs of modern new energy vehicles for lightweight interior materials and ultimate comfort.

[0006] Therefore, overcoming the difficulty in simultaneously achieving good interfacial bonding, flame retardant stability, and lightweight comfort in automotive interiors is a technical problem that urgently needs to be solved in this field.

[0007] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention

[0008] This disclosure provides at least one flame-retardant composite fabric with a three-dimensional interlocking gradient structure and a method for preparing the same.

[0009] In a first aspect, embodiments of this disclosure provide a flame-retardant composite fabric, comprising: a three-dimensional fiber skeleton and a nano-hybrid flame-retardant network; the three-dimensional fiber skeleton is a flame-retardant fiber fabric modified by low-temperature plasma and grafted with a silane coupling bridging layer on its surface; the nano-hybrid flame-retardant network is formed by in-situ crosslinking of transition metal carbide nanosheets and polyamic acid precursor, and fills the gaps in the three-dimensional fiber skeleton; and the nano-hybrid flame-retardant network is asymmetrically gradient distributed on the three-dimensional fiber skeleton and is anchored by covalent bonding to form a three-dimensional interlocking interpenetrating network structure.

[0010] In one alternative embodiment, the flame-retardant fiber fabric is selected from at least one of aramid fiber fabric, carbon fiber fabric, pre-oxidized fiber fabric, polyphenylene sulfide (PPS) fiber fabric, or blended fabrics thereof.

[0011] In one alternative embodiment, after plasma modification, the concentration of active free radicals in the three-dimensional fiber skeleton gradually decreases from the side adjacent to the nano-hybrid flame retardant network to the side away from the nano-hybrid flame retardant network.

[0012] In one alternative embodiment, the transition metal carbide nanosheets comprise a monolayer or few-layer Ti3C2T x The structure; the few-layer structure refers to transition metal carbide nanosheets with 2-10 layers; the surface of the transition metal carbide nanosheets is modified with polydopamine; and the mass fraction of the transition metal carbide nanosheets in the nano-hybrid flame retardant network is 0.5% to 3.0%.

[0013] In one optional embodiment, the nano-hybrid flame retardant network further includes a phosphorus-containing flame retardant monomer, which includes at least one of the amino derivatives of bis(p-aminophenyl)phenylphosphine oxide, bis(4-carboxyphenyl)phenylphosphine oxide, or 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; the phosphorus-containing flame retardant monomer undergoes in-situ polycondensation with the polyamic acid precursor to form a continuous ceramicized precursor coating on the surface of the three-dimensional fiber skeleton.

[0014] Secondly, this disclosure also provides a method for preparing the flame-retardant composite fabric as described above, comprising the following steps: S1, using low-temperature plasma to asymmetrically modify the three-dimensional fiber skeleton; S2, impregnating the modified three-dimensional fiber skeleton in a silane coupling agent solution to obtain a flame-retardant fiber fabric with a silane coupling bridging layer grafted on the surface; S3, mixing an MXene dispersion containing transition metal carbide nanosheets with a polyamic acid precursor to form a hybrid sol, and gradient-injecting it into the gaps between the skeleton fibers of the flame-retardant fiber fabric through a vacuum pressure difference; S4, using multi-stage hot pressing to cause the hybrid sol in the injected flame-retardant fiber fabric to gel in situ and covalently lock with the three-dimensional fiber skeleton, and then drying to form a three-dimensional interlocked interpenetrating network structure to obtain the flame-retardant composite fabric.

[0015] In one optional embodiment, the power of the low-temperature plasma modification in S1 is 200W to 400W, and the processing time is 60s to 120s; the mass fraction of the silane coupling agent solution in S2 is 1.5% to 4.0%; the vacuum pressure difference in S3 is 0.05MPa to 0.09MPa, and the longitudinal penetration depth of the MXene dispersion in the three-dimensional fiber skeleton is adjusted by controlling the filtration speed.

[0016] In one optional embodiment, the multi-stage hot pressing in S4 includes: pre-pressing at 80°C to 100°C for 5 to 10 minutes to allow interfacial penetration, followed by pressurizing at 140°C to 160°C to 0.5 to 1.0 MPa to carry out a covalent cross-linking reaction.

[0017] In one alternative embodiment, the drying in S4 includes removing the solvent using supercritical CO2 drying or vacuum freeze-drying processes to form a flame-retardant gas gel core with a fractal porous structure in the interstices of the skeletal fibers of the flame-retardant fiber fabric.

[0018] Thirdly, embodiments of this disclosure also provide an automotive interior that uses the flame-retardant composite fabric as described above.

[0019] The beneficial effects of this flame-retardant composite fabric with a three-dimensional interlocking gradient structure and its preparation method are as follows: 1. By utilizing the covalent bonds formed between the active sites generated by low-temperature plasma excitation and the silane coupling agent, a stable Si-OC or Si-O-Si covalent bond system is formed at the interface between the flame-retardant network and the fiber skeleton. This molecular-level anchoring mechanism eliminates the interlayer physical interface and solves the interlayer fatigue peeling defect that is prone to occur in automotive interiors under long-term complex alternating stress. 2. Under the premise of satisfying the interfacial bonding force, replacing conventional expanded graphite with two-dimensional nano-MXene not only has a better infrared heat reflection effect, but also can catalyze the in-situ transformation of the polymer matrix into a dense ceramic carbon layer, which has excellent self-supporting ability and resistance to airflow erosion, and can effectively block the diffusion of heat flux and molten droplets. 3. By employing a vacuum-assisted in-situ sol-gel process, an interpenetrating network structure with asymmetric gradient characteristics is constructed. In this invention, the flame-retardant component no longer exists in the form of a thick filler layer, but rather in a root-like distribution with an extremely low load in the fiber gaps. Combined with the fractal porous aerogel structure, the material weight reduction and driving comfort requirements of automotive interiors are achieved while maintaining the original porous and breathable properties and rich feel of the fibers. 4. In this invention, flame-retardant functional monomers and NXene nanosheets are chemically cross-linked and locked inside the three-dimensional fiber skeleton. This interpenetrating network structure can effectively prevent the physical shedding and chemical migration of flame retardants during long-term use and standard washing, ensuring the safety and consistency of automotive interiors throughout their entire life cycle.

[0020] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0024] In this document, as used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0025] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0026] The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0027] This disclosure provides a flame-retardant composite fabric, comprising: a three-dimensional fiber skeleton and a nano-hybrid flame-retardant network; the three-dimensional fiber skeleton is a flame-retardant fiber fabric modified by low-temperature plasma and grafted with a silane coupling bridging layer on its surface; the nano-hybrid flame-retardant network is formed by in-situ crosslinking of transition metal carbide nanosheets with a polyamic acid precursor and filling the gaps in the three-dimensional fiber skeleton; and the nano-hybrid flame-retardant network is asymmetrically gradient distributed on the three-dimensional fiber skeleton and anchored by covalent bonding to form a three-dimensional interlocking interpenetrating network structure.

[0028] Specifically, the three-dimensional fiber skeleton serves as a substrate, providing mechanical support and the physical properties required for automotive interiors; the low-temperature plasma modification, combined with the silane coupling bridging layer, solves the peeling problem caused by the mismatch in thermal expansion and contraction coefficients between organic fibers and inorganic flame retardants; the transition metal carbide nanosheets (MXene nanosheets) serve as the core flame retardant, utilizing their two-dimensional structure to achieve infrared heat reflection and catalyze the ceramicization of the matrix, replacing bulky traditional flame retardant fillers; the polyamic acid precursor acts as a film-forming agent, encapsulating MXene and forming an interpenetrating network structure with the fiber skeleton.

[0029] In some embodiments, specifically, the flame-retardant fiber fabric is selected from at least one of aramid fiber fabric, carbon fiber fabric, pre-oxidized fiber fabric, polyphenylene sulfide (PPS) fiber fabric, or blended fabrics thereof. All of the above high-performance fibers contain active sites that can be excited by plasma, enabling them to form a stable interlocking structure with the nano-hybrid flame-retardant network.

[0030] In some embodiments, specifically, after plasma modification, the concentration of active free radicals in the three-dimensional fiber skeleton gradually decreases from the side adjacent to the nano-hybrid flame retardant network to the side away from the nano-hybrid flame retardant network.

[0031] In some embodiments, specifically, the transition metal carbide nanosheets comprise a single layer or few layers of Ti3C2T. x The structure; the few-layer structure refers to transition metal carbide nanosheets with 2-10 layers, which have a high specific surface area, which is conducive to sufficient in-situ cross-linking with polyamic acid, thereby improving the density of the ceramic carbon layer; the surface of the transition metal carbide nanosheets is modified with polydopamine; and the mass fraction of the transition metal carbide nanosheets in the nano-hybrid flame retardant network is 0.5% to 3.0%.

[0032] In some embodiments, the nano-hybrid flame retardant network further includes a phosphorus-containing flame retardant monomer, which includes at least one of the amino derivatives of bis(p-aminophenyl)phenylphosphine oxide (DAPPO), bis(4-carboxyphenyl)phenylphosphine oxide (BCPPO), or 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO); the phosphorus-containing flame retardant monomer undergoes in-situ polycondensation with the polyamic acid precursor to form a continuous ceramicized precursor coating on the surface of the three-dimensional fiber skeleton.

[0033] In some embodiments, specifically, the silane coupling agent is a functionalized silane containing amino, epoxy, or isocyanate groups.

[0034] This disclosure also provides a method for preparing the flame-retardant composite fabric as described above, comprising the following steps: S1, using low-temperature plasma to asymmetrically modify the three-dimensional fiber skeleton; S2, impregnating the modified three-dimensional fiber skeleton in a silane coupling agent solution to obtain a flame-retardant fiber fabric with a silane coupling bridging layer grafted on the surface; S3, mixing an MXene dispersion containing transition metal carbide nanosheets with a polyamic acid precursor to form a hybrid sol, and gradient-injecting it into the interstices of the skeleton fibers of the flame-retardant fiber fabric through a vacuum pressure difference; S4, using multi-stage hot pressing to cause the hybrid sol in the injected flame-retardant fiber fabric to gel in situ and covalently lock with the three-dimensional fiber skeleton, and then drying to form a three-dimensional interlocked interpenetrating network structure to obtain the flame-retardant composite fabric.

[0035] In some embodiments, specifically, the power of the low-temperature plasma modification in S1 is 200W to 400W, and the processing time is 60s to 120s. In S1, the high-energy particles of the plasma bombardment induces the generation of functional groups such as active hydroxyl or carboxyl groups on the fiber surface, thereby improving the chemical wettability of the fiber surface and providing reaction sites for subsequent molecular-level anchoring.

[0036] In some embodiments, specifically, the silane coupling agent solution in S2 has a mass fraction of 1.5% to 4.0% and reacts at 45°C to 60°C for 30 to 60 minutes to construct a chemically reactive molecular bridging layer on the fiber surface; in S2, one end of the coupling agent condenses with the active groups on the fiber surface, while the other end retains an active functional group that can react with the flame-retardant precursor, thereby constructing a stable covalent bridge at the interface.

[0037] In some embodiments, the preparation method of the hybrid sol specifically includes adding MXene nanosheets, flame-retardant monomers and polyamic acid precursors to a solvent, and preparing a hybrid sol system with uniformly distributed nano-components by high-speed shearing or ultrasonic dispersion treatment. The nano-sized MXene has extremely high specific surface area and surface activity, and can form molecular-level hybrids with polymer monomers in the sol system, laying the foundation for the subsequent construction of high-performance thermal shielding networks.

[0038] In some embodiments, specifically, the vacuum pressure difference in S3 is 0.05MPa to 0.09MPa, and the longitudinal penetration depth of the MXene dispersion in the three-dimensional fiber skeleton is adjusted by controlling the filtration speed; in S3, the penetration depth of the sol is adjusted by controlling the vacuum degree, so that the flame retardant components are distributed in an asymmetric gradient inside the skeleton, eliminating obvious physical layering interfaces and forming an interpenetrating network structure.

[0039] In some embodiments, specifically, the multi-stage hot pressing in S4 includes: pre-pressing at 80℃~100℃ for 5~10min to allow interfacial penetration, followed by pressurizing at 140℃~160℃ to 0.5~1.0MPa to carry out a covalent cross-linking reaction; this process achieves covalent locking between the functional network and the fiber skeleton, forming a stable three-dimensional interlocking system, which significantly improves the bonding strength of the material under dynamic stress.

[0040] In some embodiments, specifically, the drying in S4 includes removing the solvent using supercritical CO2 drying or vacuum freeze-drying processes to form a flame-retardant gas gel core with a fractal porous structure in the gaps between the skeleton fibers of the flame-retardant fiber fabric; the special drying process can maintain the micro-nano pore structure of the aerogel, further improve the thermal insulation performance by utilizing the "thermal labyrinth" effect, and achieve the ultimate lightweighting of the material.

[0041] This disclosure also provides an automotive interior that uses the flame-retardant composite fabric as described above. Example

[0042] This embodiment discloses a method for preparing a nano-hybrid flame-retardant composite material with a three-dimensional interlocked gradient structure, the specific steps of which are as follows: S1, Interfacial activity activation: The aramid fiber fabric skeleton is placed in a plasma cleaner and oxygen plasma is used for unilateral asymmetric treatment. The electrode power is set to 300W and the treatment time is 90s, so that a high density of hydroxyl active sites are generated on the fiber surface. S2, Molecular bridging pretreatment: The excited skeleton is immersed in a 3.0% (w / w) silane coupling agent (KH-550) ethanol solution and reacted at 50°C for 45 min. After being removed, it is dried at 80°C to construct covalently anchored "molecular hooks" on the fiber surface. S3, preparation of hybrid flame retardant sol: MXene nanosheets modified with polydopamine (PDA) (monolayer Ti3C2T) are prepared. x MXene, a polyamic acid precursor, and a phosphorus-containing flame-retardant monomer were dispersed in dimethylacetamide (DMAc) solvent. The amount of MXene was 1.5% of the total sol mass, and the mass fraction of polyamic acid was 12%. A homogeneous and stable hybrid system was formed by high-energy ultrasonic dispersion for 40 min. S4, In-situ gradient infusion and interlocking: The skeleton is placed in a vacuum-sealed mold, and a pressure difference of 0.07MPa is established by a vacuum pump. The hybrid sol is directionally infused into the fiber gap from the excitation side, and the pressure gradient is used to achieve the gradient distribution of flame retardant components in the longitudinal direction. S5, In-situ Curing Anchoring: The injected material is pre-pressed at 100℃ for 10 minutes to promote interfacial penetration, and then the temperature is raised to 150℃ and the pressure is increased to 0.8MPa and held for 20 minutes to initiate the imidization reaction of the precursor and covalently cross-link with the coupling agent on the fiber surface to form a three-dimensional interlocking structure. S6, Fractal Pore Shaping: The residual solvent is removed by vacuum freeze drying to obtain the finished product.

[0043] Example 2: The preparation method of this example is basically the same as that of Example 1, except that: in S1, carbon fiber fabric is used as the skeleton, and the plasma treatment power is adjusted to 200W; in S3, polydopamine (PDA) modified few-layer (3-5 layers) Ti3C2T is used. x The amount of nanosheets was adjusted to 0.5% of the total mass of the sol. The phosphorus-containing flame retardant monomer was bis(4-carboxyphenyl)phenylphosphine oxide (BCPPO, with an addition amount of 3.0%), and the mass fraction of polyamic acid was 10%.

[0044] Example 3: The preparation method of this example is basically the same as that of Example 1, except that: in S1, a pre-oxidized fiber fabric is used as the skeleton; in S3, the amount of polydopamine (PDA) modified few-layer (8-10 layers) MXene nanosheets is adjusted to 3.0% of the total mass of the sol, and the phosphorus-containing flame retardant monomer is an amino derivative of DOPO (added at 2.0%); in S4, the vacuum pressure difference is adjusted to 0.09 MPa to obtain a steeper component gradient distribution.

[0045] Example 4: The preparation method of this example is basically the same as that of Example 1, except that: in S1, polyphenylene sulfide (PPS) fiber fabric is used as the skeleton; in S2, the mass fraction of silane coupling agent solution is adjusted to 5.0%; in S5, the curing temperature is adjusted to 160℃ and the hot pressing pressure is adjusted to 1.0MPa.

[0046] Example 5: The preparation method of this example is basically the same as that of Example 1, except that: in S1, the plasma treatment power is adjusted to 400W and the treatment time is 120s; in S3, the amount of polydopamine (PDA) modified few-layer (5-layer) MXene nanosheets is adjusted to 4.0% of the total mass of the sol, and the proportion of flame retardant monomers is increased to 15%.

[0047] The performance tests are shown in Table 1 below: Table 1. Comparison of Comprehensive Performance Tests of Nano-Hybrid Flame-Retardant Composite Materials

[0048] Conclusions and evaluations based on the preparation and testing of the above embodiments show that: The combination of MXene-polyimide aerogel network and plasma-modified fiber skeleton produces a significant structural synergistic effect. The biomimetic shielding layer formed by MXene nanosheets in the aerogel skeleton, together with the in-situ generated ceramicized carbon layer, constructs a dense thermal barrier.

[0049] This invention employs a three-pronged process of "interface excitation-molecular bridging-in-situ gradient infusion" to achieve interlocking of the flame-retardant network and fiber skeleton at the molecular energy level. This "interfaceless" gradient structure exhibits excellent performance in peel strength testing (Example 1: peel strength reaches 32.8 N / cm), far exceeding traditional physical lamination methods.

[0050] By controlling the vacuum pressure difference and plasma asymmetric excitation, a stable asymmetric interpenetrating network (IPN) can be constructed inside the ultrathin fiber substrate, achieving V-0 intrinsic flame retardancy while significantly reducing the material weight.

[0051] In summary, the beneficial effects of the present invention are as follows: 1. By utilizing the covalent bonds formed between the active sites generated by low-temperature plasma excitation and the silane coupling agent, a stable Si-OC or Si-O-Si covalent bond system is formed at the interface between the flame-retardant network and the fiber skeleton. This molecular-level anchoring mechanism eliminates the interlayer physical interface and solves the interlayer fatigue peeling defect that is prone to occur in automotive interiors under long-term complex alternating stress. 2. Under the premise of satisfying the interfacial bonding force, replacing conventional expanded graphite with two-dimensional nano-MXene not only has a better infrared heat reflection effect, but also can catalyze the in-situ transformation of the polymer matrix into a dense ceramic carbon layer, which has excellent self-supporting ability and resistance to airflow erosion, and can effectively block the diffusion of heat flux and molten droplets. 3. By employing a vacuum-assisted in-situ sol-gel process, an interpenetrating network structure with asymmetric gradient characteristics is constructed. In this invention, the flame-retardant component no longer exists in the form of a thick filler layer, but rather in a root-like distribution with an extremely low load in the fiber gaps. Combined with the fractal porous aerogel structure, the material weight reduction and driving comfort requirements of automotive interiors are achieved while maintaining the original porous and breathable properties and rich feel of the fibers. 4. In this invention, flame-retardant functional monomers and MXene nanosheets are chemically cross-linked and locked inside the three-dimensional fiber skeleton. This interpenetrating network structure can effectively prevent the physical shedding and chemical migration of flame retardants during long-term use and standard washing, ensuring the safety and consistency of automotive interiors throughout their entire life cycle.

[0052] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A flame-retardant composite fabric, characterized in that, include: Three-dimensional fiber skeleton and nano-hybrid flame-retardant network; The three-dimensional fiber skeleton is a flame-retardant fiber fabric modified by low-temperature plasma and grafted with a silane coupling bridging layer on its surface. The nano-hybrid flame retardant network is formed by in-situ cross-linking of transition metal carbide nanosheets with polyamic acid precursors and fills the gaps in the three-dimensional fiber skeleton. Furthermore, the nano-hybrid flame-retardant network exhibits an asymmetric gradient distribution on the three-dimensional fiber skeleton and is anchored through covalent bonding, forming a three-dimensional interlocking interpenetrating network structure.

2. The flame-retardant composite fabric as described in claim 1, characterized in that, The flame-retardant fiber fabric is selected from at least one of aramid fiber fabric, carbon fiber fabric, pre-oxidized fiber fabric, polyphenylene sulfide fiber fabric, or blended fabrics thereof.

3. The flame-retardant composite fabric as described in claim 1, characterized in that, After plasma modification, the concentration of active free radicals in the three-dimensional fiber skeleton gradually decreases from the side adjacent to the nano-hybrid flame retardant network to the side away from the nano-hybrid flame retardant network.

4. The flame-retardant composite fabric as described in claim 1, characterized in that, The transition metal carbide nanosheets include monolayer or few-layer Ti3C2T x structure; The few-layer structure refers to transition metal carbide nanosheets with 2-10 layers. The surface of the transition metal carbide nanosheets is modified with polydopamine; Furthermore, the mass fraction of the transition metal carbide nanosheets in the nano-hybrid flame retardant network is 0.5% to 3.0%.

5. The flame-retardant composite fabric as described in claim 1, characterized in that, The nano-hybrid flame retardant network further includes phosphorus-containing flame retardant monomers, which include at least one of bis(p-aminophenyl)phenylphosphine oxide, bis(4-carboxyphenyl)phenylphosphine oxide, or an amino derivative of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. The phosphorus-containing flame-retardant monomer undergoes in-situ polycondensation with the polyamic acid precursor, forming a continuous ceramicized precursor coating on the surface of the three-dimensional fiber skeleton.

6. A method for preparing a flame-retardant composite fabric as described in any one of claims 1-5, characterized in that, Includes the following steps: S1, using low-temperature plasma to perform asymmetric modification on the three-dimensional fiber skeleton; S2, the modified three-dimensional fiber skeleton is impregnated in a silane coupling agent solution to obtain a flame-retardant fiber fabric with a silane coupling bridging layer grafted on the surface. S3, MXene dispersion containing transition metal carbide nanosheets is mixed with polyamic acid precursor to form a hybrid sol, which is then gradient-infused into the gaps between the skeleton fibers of flame-retardant fiber fabric through vacuum pressure difference. S4, through multi-stage hot pressing, the hybrid sol in the injected flame-retardant fiber fabric is gelled in situ and covalently locked with the three-dimensional fiber skeleton. Then, through drying, a three-dimensional interlocking interpenetrating network structure is formed, resulting in a flame-retardant composite fabric.

7. The preparation method according to claim 6, characterized in that, The power of the low-temperature plasma modification in S1 is 200W to 400W, and the processing time is 60s to 120s. The mass fraction of the silane coupling agent solution in S2 is 1.5% to 4.0%; The vacuum pressure difference in S3 is 0.05MPa to 0.09MPa, and the longitudinal penetration depth of the MXene dispersion in the three-dimensional fiber skeleton is adjusted by controlling the filtration speed.

8. The preparation method according to claim 6, characterized in that, The multi-stage hot pressing in S4 includes: pre-pressing at 80℃~100℃ for 5~10min to allow interfacial penetration, followed by pressurizing at 140℃~160℃ to 0.5~1.0MPa to carry out a covalent cross-linking reaction.

9. The preparation method according to claim 6, characterized in that, The drying process in S4 includes removing the solvent using supercritical CO2 drying or vacuum freeze-drying to form a flame-retardant gas gel core with a fractal porous structure in the gaps between the skeleton fibers of the flame-retardant fiber fabric.

10. An automotive interior, characterized in that, The flame-retardant composite fabric as described in any one of claims 1-5 is used.

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