A smart fire-resistant fabric, its preparation method and application

Abstract

This invention discloses an intelligent fire-retardant fabric, its preparation method, and its application, belonging to the field of fire-retardant materials technology. This invention involves blending graphene / polyimide aerogel with polyimide fibers to create a composite fabric. The in-situ synthesis of the graphene / polyimide aerogel gives it good dispersion uniformity and bonding strength. Simultaneously, the aerogel, with polyimide as the matrix, shares the same molecular structure and chemical composition with the polyimide fibers, exhibiting a good interfacial structure and enhancing the strength of the composite fabric. The thermal decomposition temperature of this intelligent fire-retardant fabric is increased (5% thermal decomposition temperature > 500℃), while its high-temperature resistance and flame-retardant properties are also improved. This intelligent fire-retardant fabric uses aerogel as a lightweight filler to prepare a low-density, highly breathable protective layer, reducing the overall weight of the intelligent fire-retardant fabric and improving wearing comfort.

Description

Technical Field

[0001] This invention belongs to the field of fire protection materials technology, and in particular relates to an intelligent fireproof fabric, its preparation method and application. Background Technology

[0002] Protective fabrics are widely used in firefighting, chemical protection, industrial protection, and military applications, typically possessing properties such as heat resistance, chemical corrosion resistance, abrasion resistance, and flame retardancy. Existing protective fabrics mostly use polyester, aramid, and polyimide fibers as base materials, which are enhanced through multi-layer composites, coatings, or the addition of special materials. Flame-retardant fabrics usually use chlorine- or phosphorus-containing flame retardants or add flame-retardant coatings. Fire-resistant protective fibers generally use materials with good thermal stability and high-temperature resistance, such as aramid and polyimide fibers. However, the thermal stability and mechanical properties of these single fabrics may be insufficient when exposed to extreme environments. The mechanical strength of traditional protective fabrics gradually decreases after prolonged exposure to high temperatures or physical friction, easily leading to tearing and abrasion, resulting in reduced protective performance. Many traditional protective fabrics employ thick coatings or multi-layer composite structures to enhance protective performance, resulting in poor breathability. Wearers may experience stuffiness and discomfort after prolonged use, potentially impacting work efficiency and safety. Traditional protective materials are usually ineffective in preventing static electricity buildup or electromagnetic interference. In some high-risk environments (such as chemical production and electronic equipment protection), electrostatic discharge may cause safety accidents, and electromagnetic interference may also affect the normal operation of electronic equipment.

[0003] Patent CN110205832A discloses a double-sided grid aerogel insulation felt for firefighter uniforms with good breathability. The aerogel technology provided by this patent, applied in heat insulation protection devices, can solve problems such as drastically reduced breathability, poor aerogel adhesion, and impact on wearing comfort. However, the fabric composite of silica aerogel powder and aramid-based felt used in this patent is prone to poor adhesion and aerogel detachment; furthermore, the use of grid strips for air conduction increases additional weight and processing costs.

[0004] Patent CN115107338A discloses a fire-resistant fabric for firefighting clothing. This patent provides a fire-resistant fabric for use in protective devices against harmful chemicals, which can solve the problems of existing fire-resistant fabrics, such as inability to sustain continuous combustion, poor thermal insulation, and firefighter fatigue. However, the insulation layer used in this patent is made of a composite material composed of aerogel, pre-oxidized fiber, ceramic fiber, and carbon fiber. The process is relatively complex, and the aerogel is prone to poor adhesion between the fibers, resulting in aerogel detachment. Furthermore, in today's complex fire scene environment, there is no potential for further upgrades to intelligent systems. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes an intelligent fire-retardant fabric, its preparation method, and its application. The intelligent fire-retardant fabric of this invention features a low-density, highly breathable protective layer, reducing overall weight and improving wearing comfort.

[0006] This invention provides an intelligent fire-resistant fabric with a sandwich structure. The middle layer is a composite fabric made of graphene / polyimide aerogel and polyimide fiber, the outer layer is fire-resistant polyimide fiber cloth, and the inner layer is aramid fiber.

[0007] This invention also provides a method for preparing the above-mentioned intelligent fire-resistant fabric, comprising the following steps:

[0008] After in-situ synthesis of graphene / polyimide aerogel, the graphene / polyimide aerogel is mixed with pretreated polyimide fibers, stirred evenly, and then polyamic acid solution is added. After standing, a second wet gel is obtained. The second wet gel is washed, freeze-dried, and cured under a nitrogen atmosphere to obtain a composite fabric of graphene / polyimide aerogel and polyimide fibers.

[0009] The intelligent fireproof fabric is obtained by hot pressing a composite fabric made of graphene / polyimide aerogel and polyimide fiber as the middle layer, fireproof polyimide fiber cloth as the outer layer, and aramid fiber as the inner layer.

[0010] Furthermore, the preparation method of the in-situ synthesized graphene / polyimide aerogel includes the following steps:

[0011] The graphene dispersion was mixed with the polyamic acid precursor solution, the pH was adjusted to 6-7, and the mixture was allowed to stand at 60-80℃ to form a first wet gel. The first wet gel was washed with water until the residual solvent was completely removed. The first wet gel with the residual solvent removed was immersed in ethanol, first frozen in liquid nitrogen, and then freeze-dried at -50℃ to obtain graphene / polyamic acid aerogel.

[0012] The graphene / polyamic acid aerogel was cured in a nitrogen atmosphere at 250-300°C for 2 hours to obtain the graphene / polyimide aerogel.

[0013] Furthermore, the preparation method of the polyamic acid precursor solution includes the following steps:

[0014] Graphene powder was dispersed in water and sonicated under ice bath conditions to obtain a graphene dispersion with a concentration of 1-2 mg / mL.

[0015] Diaminodiphenyl ether was added to N,N-dimethylacetamide and stirred until dissolved to obtain a diaminodiphenyl ether solution.

[0016] Add pyromellitic dianhydride to N,N-dimethylacetamide and stir until dissolved to obtain a pyromellitic dianhydride solution;

[0017] The pyromellitic dianhydride solution is added dropwise to the diaminodiphenyl ether solution to ensure that the solid content of the mixed solution is 10-20 wt.%, and stirred at 0-5°C until transparent to obtain a polyamic acid precursor solution.

[0018] Furthermore, the preparation method of the composite fabric of graphene / polyimide aerogel and polyimide fiber blend is as follows: the graphene / polyimide aerogel is mixed with pretreated polyimide fiber, stirred evenly, and then polyamic acid solution is added. After standing at 60-80℃ for 24 hours, a second wet gel is obtained. The second wet gel is soaked in ethanol, washed with water, freeze-dried, and cured at 250-300℃ for 2 hours in a nitrogen atmosphere to obtain the composite fabric of graphene / polyimide aerogel and polyimide fiber blend.

[0019] Conventional fire-resistant materials are prone to cracking and wear under extreme conditions, exhibiting poor durability. The graphene in the intelligent fire-resistant fabric of this invention significantly improves the tensile strength, flexural strength, and abrasion resistance of the material, giving the intelligent fire-resistant fabric better mechanical properties and long-term stability. This invention employs a composite nanomaterial method, blending graphene / polyimide aerogel with polyimide fibers to create a composite fabric. The in-situ synthesis of the graphene / polyimide aerogel ensures good dispersion uniformity and bonding strength. Simultaneously, the aerogel with polyimide as the matrix (i.e., graphene / polyimide aerogel) shares the same molecular structure and chemical composition as the polyimide fibers, resulting in a good interfacial structure and enhancing the strength of the composite fabric. The thermal decomposition temperature of the intelligent fire-resistant fabric of this invention is increased (5% thermal decomposition temperature > 500℃), while high-temperature resistance and flame retardant properties are also improved. Traditional heavy protective materials affect wearing comfort and hinder prolonged work. The intelligent fire-resistant fabric of this invention uses aerogel as a lightweight filler to prepare a low-density, highly breathable protective layer, reducing the overall weight of the intelligent fire-resistant fabric and improving wearing comfort. Furthermore, traditional fire-resistant fabrics lack electromagnetic shielding and antistatic functions, making them unsuitable for use in special environments (such as those with electromagnetic interference). This invention, however, constructs a complete conductive network within the fabric by blending graphene with polyimide fibers. This provides a pathway for electrical signal transmission, and the electrons within the fabric can rearrange themselves according to external electromagnetic fields, neutralizing their influence and making it suitable for intelligent protective clothing and electromagnetic shielding environments.

[0020] In this invention, the aerogel matrix (graphene / polyimide aerogel) and the polyimide fibers share the same polyimide molecular chain structure. At the interface, they form a seamless bond through physical entanglement and chemical bonding of molecular chains, significantly reducing interfacial stress and improving bonding strength. Simultaneously, during the composite fabric preparation process, a polyamic acid solution acts as a binder, penetrating the gaps between the graphene / polyimide aerogel and the polyimide fibers. After high-temperature curing, the polyamic acid transforms into polyimide, undergoing a condensation reaction with the polyimide fiber matrix to form a continuous phase structure linked by covalent bonds, further enhancing the bonding force between the graphene / polyimide aerogel and the polyimide fibers. Furthermore, the graphene forms a continuous conductive network within the fabric, and its edge oxygen-containing functional groups (such as hydroxyl and epoxy groups) strongly interact with the polar groups on the surface of the polyimide fibers. This bridging effect further locks the relative positions of the graphene / polyimide aerogel and the polyimide fibers. Therefore, in the intelligent fireproof fabric of this invention, the aerogel is firmly attached to the fiber, and the aerogel is not easy to fall off.

[0021] In the preparation method of intelligent fireproof fabric, when preparing graphene dispersion, the ultrasonic power is 200-400W and the ultrasonic time is 1 hour.

[0022] In the preparation method of intelligent fireproof fabric, the molar ratio of diaminodiphenyl ether and N,N-dimethylacetamide is 1:1.

[0023] In the preparation method of intelligent fireproof fabric, the molar ratio of the pyromellitic dianhydride and the diaminodiphenyl ether is 1:1.

[0024] In the preparation method of intelligent fireproof fabric, the pretreatment step of the polyimide fiber is as follows: the polyimide fiber is soaked in ethanol for 1 hour to remove surface impurities, and then added to N,N-dimethylacetamide and ultrasonically treated with 200-400W power for 30 minutes under ice bath conditions.

[0025] In the preparation method of intelligent fire-resistant fabric, the mass ratio of graphene / polyimide aerogel to polyimide fiber is (7-9):(1-3). For example, the mass ratio of graphene / polyimide aerogel to polyimide fiber is 7:3, 8:2, or 9:1.

[0026] In the preparation method of intelligent fireproof fabric, after adding the polyamic acid solution, the proportion of the polyamic acid solution in the system is 5-10 wt.%.

[0027] The present invention also provides the application of the above-mentioned intelligent fireproof fabric in the fields of fire protection, protection, industrial electromagnetic shielding and intelligent wearable devices.

[0028] The present invention also provides the application of the above-mentioned intelligent fire-resistant fabric in the preparation of intelligent protective clothing and / or wearable devices in electromagnetic interference environments.

[0029] Compared with the prior art, the present invention has the following advantages and technical effects:

[0030] The intelligent fire-resistant fabric of this invention is a composite fabric of graphene / polyimide aerogel and polyimide fiber, integrating excellent properties such as flame retardancy, conductivity, lightweight, and chemical corrosion resistance. It is a multifunctional material, especially suitable for fire protection, protection, industrial electromagnetic shielding, and smart wearable devices. The synergistic effect of graphene and polyimide increases the fabric's 5% thermal decomposition temperature to over 500°C, effectively ensuring its safety in high-temperature environments. Furthermore, graphene, as a free radical scavenger, delays the material's thermal degradation, thereby prolonging the combustion time. The reinforcing effect of graphene also significantly improves the mechanical strength of the intelligent fire-resistant fabric; for example, the tensile strength is increased to over 100 MPa, the tensile modulus is greater than 2.5 GPa, the elongation at break is 8%-15%, and the flexural strength exceeds 80 MPa. The composite structure gives the fabric higher durability under severe tensile or bending conditions. Simultaneously, graphene constructs a conductive network within the intelligent fire-resistant fabric, endowing it with excellent antistatic properties. Its moderate conductivity also makes it suitable for use in smart protective clothing or wearable devices in environments with electromagnetic interference. The low density of aerogel makes the intelligent fire-resistant fabric lightweight, making it suitable for manufacturing fire-fighting suits worn for extended periods. The pores in the aerogel structure improve airflow and enhance wearing comfort. The high strength, high thermal stability, and electromagnetic shielding capabilities of the intelligent fire-resistant fabric provide comprehensive performance guarantees for fire-fighting suits and special protective clothing. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 Synthesis process and molecular formula of graphene / polyimide aerogel;

[0033] Figure 2 Here is a SEM image of the graphene / polyimide aerogel in Example 2;

[0034] Figure 3 This is a high-temperature resistant photograph of the intelligent fireproof fabric in Example 2;

[0035] Figure 4 This is a SEM image of the fire-resistant fabric in Comparative Example 1. Detailed Implementation

[0036] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0037] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0038] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0039] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0040] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0041] An embodiment of the present invention provides a method for preparing an intelligent fire-resistant fabric, comprising the following steps:

[0042] Graphene powder was dispersed in water and sonicated (power set to 200-400W) for 1 hour under ice bath conditions to obtain a uniformly mixed graphene dispersion with a concentration of 1-2 mg / mL.

[0043] Diaminodiphenyl ether (ODA) was added dropwise to N,N-dimethylacetamide (DMAc) at a 1:1 molar ratio, and stirred for 2 hours until completely dissolved to obtain an ODA solution.

[0044] Add an equimolar amount of pyromellitic dianhydride (PMDA) to DMAc and stir until dissolved to obtain a PMDA solution;

[0045] Add PMDA solution dropwise to ODA solution, ensuring the solid content of the mixed solution is 10-20 wt.%, and stir at 0-5℃ until transparent to obtain polyamic acid (PAA) precursor solution;

[0046] The graphene dispersion was mixed with the PAA precursor solution to ensure that the mass fraction of graphene in the final mixture was 5-15%. The pH was adjusted to 6-7 with ammonia or ethylenediamine to promote stable composite. The mixture was poured into a mold and allowed to stand at 60-80℃ for 24 hours to form the first wet gel. The first wet gel was washed with deionized water until the residual solvent was completely removed. The first wet gel after removing the residual solvent was soaked in ethanol for 24 hours to perform solvent replacement. The first wet gel after solvent replacement was first rapidly frozen in liquid nitrogen and then freeze-dried at -50℃ for 48 hours to obtain graphene / polyamic acid aerogel.

[0047] Graphene / polyamic acid aerogel was cured in a nitrogen atmosphere at 250-300℃ for 2 hours to promote the conversion of PAA to polyimide and prevent material oxidation, resulting in graphene / polyimide aerogel (G / PI aerogel). The synthesis process and molecular formula of graphene / polyimide aerogel are described in [link to documentation]. Figure 1 ;

[0048] Polyimide fibers (PI fibers) were soaked in ethanol for 1 hour to remove surface impurities. Then, the polyimide fibers treated as above were added to DMAc and ultrasonically treated with 200-400W power for 30 minutes under ice bath conditions to ensure uniform dispersion of PI fibers and obtain pretreated PI fibers.

[0049] Graphene / polyimide aerogel and pretreated PI fibers were mixed at a mass ratio of (7-9):(1-3) and stirred at 300 rpm for 2 hours in a mechanical stirrer to ensure that the PI fibers were evenly distributed in the aerogel matrix. Then, a 20 wt.% polyamic acid (PAA) precursor solution (PAA precursor solution can improve the overall strength and adhesion of the material) was added to make the proportion of PAA precursor solution in the system 5-10 wt.%. The mixture was poured into a mold (depending on the fabric size) and allowed to stand at 60-80℃ for 24 hours to obtain a second wet gel. The second wet gel was soaked in ethanol for 12 hours and washed with deionized water until the solvent residues such as DMAc were removed. Then, it was freeze-dried at -50℃ for 48 hours and cured at 250-300℃ for 2 hours in a nitrogen atmosphere to obtain a composite fabric of graphene / polyimide aerogel and PI fiber blend, so as to promote the conversion of PAA to polyimide and prevent the material from oxidizing.

[0050] A composite fabric made of graphene / polyimide aerogel and PI fiber is used as the middle layer, fire-retardant polyimide fiber cloth is used as the outer layer, and a skin-friendly layer woven from aramid fiber fabric is used as the inner layer. The intelligent fire-retardant fabric is obtained by hot pressing.

[0051] Hot pressing is a molding process that processes materials under high temperature and high pressure, and is widely used in the manufacture of high-performance composite materials, plastic products, and other fields. In the following embodiments of the present invention, the hot pressing method is as follows: the three layers of fabric are cut to the required size, the surface is cleaned to remove impurities, and then dried in an oven at 80°C for 2 hours; then, they are laid flat in the mold in the order of "outer layer → middle layer → inner layer", ensuring that each layer is aligned and wrinkle-free, and placed in the hot pressing mold. The temperature during the hot pressing process is 280-300°C (which needs to be higher than the glass transition temperature of polyimide to ensure molecular chain fluidity and interlayer fusion); the pressure is 8-12 MPa (excessive pressure may cause damage to the aerogel pore structure, and optimization through pre-experimentation is required). After maintaining 8-12 MPa for 20-30 minutes, the material is naturally cooled to below 80°C under pressure, and then the pressure is released and the material is demolded to prevent delamination or deformation due to rapid cooling. Finally, the edge overflow is removed, and the integrity of the interlayer bonding is checked.

[0052] The intelligent fireproof fabric of this invention can be used in the fields of fire protection, protection, industrial electromagnetic shielding and intelligent wearable devices. For example, it can be used to manufacture intelligent protective clothing and wearable devices in electromagnetic interference environments.

[0053] In the comparative examples of the following embodiments of the present invention, the outer fire-retardant polyimide fiber cloth is P84 polyimide flame-retardant fiber cloth purchased from Wuxi Yaoxin Textile Co., Ltd., which is a flame-retardant, heat-insulating, and fire-resistant material with a density of 1800 g / m³. 2 The inner aramid fiber fabric, woven into a skin-friendly layer, uses aramid flame-retardant fabric purchased from Jiangsu Tiandizao New Material Technology Co., Ltd., with a weight of 200g / m². 2 .

[0054] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0055] All raw materials used in the embodiments of the present invention were obtained through commercial purchase.

[0056] The technical solution of the present invention will be further illustrated by the following embodiments.

[0057] Example 1

[0058] This embodiment provides a method for preparing an intelligent fire-resistant fabric, the specific method of which is as follows:

[0059] Graphene powder (1250 mesh) was dispersed in deionized water and then ultrasonically treated in an ice bath for 1 hour with an ultrasonic power of 300W to obtain a uniformly dispersed graphene solution with a concentration of 1.5 mg / mL.

[0060] Using N,N-dimethylacetamide (DMAc) as a solvent, diaminodiphenyl ether (ODA) was added dropwise at a 1:1 molar ratio and stirred for 2 hours until completely dissolved to obtain an ODA solution.

[0061] An equimolar amount of pyromellitic dianhydride (PMDA) was dissolved in N,N-dimethylacetamide (DMAc), and then added dropwise to the above ODA solution. The reaction temperature was controlled at 3°C, and the solid content of the mixed solution was ensured to be 15 wt.%. The mixture was stirred at room temperature for 12 hours to form a transparent polyamic acid (PAA) precursor solution.

[0062] The graphene solution was mixed with the PAA precursor solution to ensure that the mass fraction of graphene in the final mixture was 10%. The mixture was stirred at room temperature for 4 hours to ensure that the graphene was uniformly dispersed in the PAA matrix. The pH was adjusted to 7 with ammonia to promote stable composite. The resulting mixture was poured into a mold and allowed to stand at 70°C for 24 hours to form a wet gel. The wet gel was repeatedly washed with deionized water until the residual solvent was removed. The wet gel was then soaked in ethanol for 24 hours to perform solvent replacement. The solvent-replaced wet gel was first immersed in liquid nitrogen for rapid freezing, and then freeze-dried at -50°C for 48 hours to obtain graphene / PAA aerogel.

[0063] The obtained graphene / PAA aerogel was cured at 280°C under a nitrogen atmosphere for 2 hours to promote the conversion of PAA into polyimide and prevent the material from oxidizing, thus obtaining graphene / polyimide aerogel (G / PI aerogel).

[0064] Polyimide fibers (PI fibers) were soaked in ethanol for 1 hour to remove surface impurities. Then, the polyimide fibers treated as described above were added to DMAc and ultrasonically treated at 300W power for 30 minutes under ice bath conditions to ensure uniform fiber dispersion.

[0065] Graphene / polyimide aerogel was mixed with uniformly dispersed polyimide fibers (graphene / polyimide aerogel accounted for 90 wt.% of the total mass of graphene / polyimide aerogel and polyimide fibers, and polyimide fibers accounted for 10 wt.% of the total mass of graphene / polyimide aerogel and polyimide fibers), and stirred at 300 rpm for 2 hours in a mechanical stirrer to ensure that the polyimide fibers were uniformly distributed in the graphene / polyimide aerogel matrix. Then, a 20 wt.% polyamic acid (PAA) precursor solution was added, so that the proportion of PAA precursor solution in the mixed system was 8 wt.%, to obtain a mixed solution (the role of PAA precursor solution is to further improve the overall strength and adhesion of the fireproof fabric). The mixed solution was poured into a mold (according to the fabric size) and allowed to stand at 70°C for 24 hours to form a wet gel. The wet gel was then soaked in ethanol for 12 hours and repeatedly washed to remove residual solvents such as DMAc. The material was then freeze-dried at -50°C for 48 hours to form a lightweight composite fabric. It was then cured at 280°C in a nitrogen atmosphere for 2 hours to promote the conversion of PAA into polyimide and prevent the material from oxidizing, resulting in a composite fabric made of graphene / polyimide composite aerogel and polyimide fiber blend.

[0066] The aforementioned composite fabric serves as the core heat insulation layer, with an outer layer of fire-retardant polyimide fiber cloth and an inner layer of skin-friendly aramid fiber fabric. These three layers are thermoformed. The specific thermoforming method is as follows: the three layers are cut to the required size, the surface is cleaned to remove impurities, and then dried in an oven at 80°C for 2 hours. Afterward, they are laid flat in a mold in the order of "outer layer → middle layer → inner layer," ensuring alignment and no wrinkles. The mold is then placed in a thermoforming mold at a temperature of 290°C. After maintaining a pressure of 10MPa for 25 minutes, the mold is allowed to cool naturally to below 80°C under pressure. The pressure is then released and the mold is demolded to prevent delamination or deformation due to rapid cooling. Finally, excess material is removed from the edges, and the integrity of the interlayer bonding is checked to ensure a tight fit, thus obtaining the intelligent fire-retardant fabric.

[0067] Example 2

[0068] The preparation method of the intelligent fireproof fabric in this embodiment is the same as that in Embodiment 1, except that the graphene / polyimide aerogel accounts for 80 wt.% of the total mass of the graphene / polyimide aerogel and polyimide fiber, and the polyimide fiber accounts for 20 wt.% of the total mass of the graphene / polyimide aerogel and polyimide fiber.

[0069] The SEM image of the graphene / polyimide aerogel in this embodiment is shown below. Figure 2 The high-temperature resistance photos of the intelligent fire-resistant fabric in this embodiment are shown below. Figure 3 It can be seen that the intelligent fireproof fabric prepared by the present invention has good high temperature resistance properties.

[0070] Example 3

[0071] The preparation method of the intelligent fireproof fabric in this embodiment is the same as that in Embodiment 1, except that the graphene / polyimide aerogel accounts for 70 wt.% of the total mass of the graphene / polyimide aerogel and polyimide fiber, and the polyimide fiber accounts for 30 wt.% of the total mass of the graphene / polyimide aerogel and polyimide fiber.

[0072] Comparative Example 1

[0073] Polyimide fibers were soaked in ethanol for 1 hour to remove surface impurities. Then, they were added to DMAc and ultrasonically treated at 300W for 30 minutes under ice bath conditions to ensure uniform fiber dispersion. The mixture was stirred at 300rpm for 2 hours in a mechanical stirrer. Then, a PAA precursor solution with a concentration of 20wt.% was added, so that the proportion of PAA precursor solution in the mixture was 8wt.%. The resulting mixture was poured into a mold (according to the fabric size) and allowed to stand at 70℃ for 24 hours to form a wet gel. The wet gel was then soaked in ethanol for 12 hours and washed repeatedly to remove residual solvents such as DMAc. The mixture was freeze-dried at -50℃ for 48 hours to obtain a lightweight composite fabric. The lightweight composite fabric was cured at 280℃ under a nitrogen atmosphere for 2 hours to promote the conversion of PAA to polyimide and prevent material oxidation, thus obtaining the composite fabric.

[0074] The above-mentioned composite fabric is used as the core heat insulation layer in the middle, the outer layer is fire-retardant polyimide fiber cloth, and the inner layer is a skin-friendly layer woven from aramid fiber fabric. The three layers are formed by hot pressing to ensure that they fit tightly together, thus obtaining the fire-retardant fabric.

[0075] SEM images of the fire-retardant fabric prepared in this comparative example are shown below. Figure 4 As can be seen, polyimide has a spatial network structure, without graphene covering it.

[0076] The mechanical properties of the fire-resistant fabrics prepared in Examples 1-3 and Comparative Example 1 were tested according to the method in GB / T 3923.1-2013. The test results are shown in Table 1.

[0077] Table 1 Mechanical properties of the fire-retardant fabrics prepared in Examples 1-3 and Comparative Example 1

[0078]

[0079]

[0080] As shown in Table 1, the tensile properties and flexural strength of Examples 1-3 are much greater than those of Comparative Example 1, while the elongation at break is less than that of Comparative Example 1.

[0081] The thermal properties of the fire-retardant fabrics prepared in Examples 1-3 and Comparative Example 1 were tested according to the method in GB / T 5455-2014. The test results are shown in Table 2.

[0082] Table 2. Thermal properties of the fire-retardant fabrics prepared in Examples 1-3 and Comparative Example 1

[0083]

[0084] As shown in Table 2, the 5% and 10% thermal decomposition temperatures of the fire-retardant fabrics in Examples 1-3 are much higher than those in Comparative Example 1, indicating that the fire-retardant fabrics in Examples 1-3 have better thermal stability.

[0085] The electrical conductivity of the fire-retardant fabrics prepared in Examples 1-3 and Comparative Example 1 was tested according to the method in GB / T 1410-2006. The test results are shown in Table 3.

[0086] Table 3. Electrical conductivity of the fire-retardant fabrics prepared in Examples 1-3 and Comparative Example 1

[0087]

[0088] As shown in Table 3, the electrical conductivity of the fireproof fabrics in Examples 1-3 is much better than that in Comparative Example 1, indicating that the fireproof fabrics in Examples 1-3 have certain electrical conductivity and can be used for intelligent protection.

[0089] In Comparative Example 1, no graphene was introduced, so the bonding strength between the aerogel and the fiber could not be improved through its bridging effect (while in this invention, graphene can provide hydrogen bonds and π-π interactions, improving the bonding strength between the aerogel and the fiber). Therefore, the composite fabric in Comparative Example 1 lacks conductivity and electromagnetic shielding performance, and its mechanical strength is reduced.

[0090] The percentage of retained mass of the fire-retardant fabrics prepared in Examples 1-3 and Comparative Example 1 was tested according to the method in GB / T 8629-2017. The test results are shown in Table 4.

[0091] Table 4. Percentage of retained mass of fire-retardant fabrics prepared in Examples 1-3 and Comparative Example 1

[0092]

[0093] As shown in Table 4, the retention quality of the fire-retardant fabrics in Examples 1-3 is slightly lower than that in Comparative Example 1, indicating that the fire-retardant fabrics in Examples 1-3 have good durability and washing stability.

[0094] As shown in Examples 1-3, the ratio of graphene / polyimide aerogel to polyimide fiber affects the performance of fire-retardant fabrics, specifically in the following ways:

[0095] (1) Effect on mechanical properties

[0096] The high modulus of graphene and the porous structure of aerogel in a high G / PI aerogel ratio can improve the compression resilience and deformation resistance of the fabric. However, excessive aerogel can lead to a decrease in inter-fiber bonding strength, reducing the tensile strength and flexibility of the fire-resistant fabric (potentially causing brittle fracture). In a high PI fiber ratio, the high strength and toughness of polyimide fibers dominate the mechanical properties, making the fabric softer and more resistant to repeated bending. However, insufficient aerogel can reduce the cushioning effect of the porous structure, potentially limiting impact resistance.

[0097] (2) Effect on thermal properties

[0098] In high G / PI aerogel ratios, the porous structure of the aerogel significantly reduces thermal conductivity, while the graphene nanosheets reflect radiant heat, synergistically improving flame retardancy (e.g., increased oxygen index). Simultaneously, graphene's high-temperature resistance (>500℃) delays the thermal decomposition of polyimide, resulting in higher mass retention at high temperatures. In high PI fiber ratios, polyimide itself has a high limiting oxygen index (LOI>30%), but the dense fiber arrangement may form thermal conduction channels, reducing overall insulation efficiency.

[0099] (3) Effect on conductivity

[0100] Graphene with a high G / PI aerogel ratio forms a continuous conductive network, significantly reducing the surface resistivity of the fabric (up to 10). 2 -10 4 (Ω / sq), suitable for antistatic or electromagnetic shielding scenarios.

[0101] (4) Impact on the percentage of retained quality (durability)

[0102] In high G / PI aerogel ratios, the aerogel is prone to detachment during washing due to mechanical friction, resulting in a decreased quality retention rate. High PI fiber ratios, with the fiber matrix providing skeletal support, lead to a higher quality retention rate after washing. Because aerogel materials are difficult to process and shape, they are generally used as rigid materials (e.g., in batteries). Aerogel materials alone lack sufficient strength as a fire-retardant layer and are easily detached when combined with other fibers or fabrics to prepare fire-retardant materials. Furthermore, it is difficult to create flexible materials such as fabrics after aerogel materials are combined with fibers. This invention uses graphene / polyimide aerogel composites with polyimide fibers, which can solve the problems existing in the fabric preparation process of aerogel materials. As can be seen from the data in Tables 1-4, this invention can successfully use aerogel materials as wearable protective clothing, suitable for antistatic or electromagnetic shielding scenarios, while simultaneously solving the problem of easy detachment of aerogel materials after being combined with fibers.

[0103] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an intelligent fireproof fabric, characterized in that, Includes the following steps: After in-situ synthesis of graphene / polyimide aerogel, the graphene / polyimide aerogel is mixed with pretreated polyimide fibers, stirred evenly, and then polyamic acid solution is added. After standing, a second wet gel is obtained. The second wet gel is washed, freeze-dried, and cured under a nitrogen atmosphere to obtain a composite fabric of graphene / polyimide aerogel and polyimide fibers. The intelligent fireproof fabric is obtained by hot pressing a composite fabric made of graphene / polyimide aerogel and polyimide fiber as the middle layer, fireproof polyimide fiber cloth as the outer layer, and aramid fiber as the inner layer.

2. The method of claim 1, wherein the method further comprises the step of: The method for preparing the in-situ synthesized graphene / polyimide aerogel includes the following steps: The graphene dispersion was mixed with the polyamic acid precursor solution, the pH was adjusted to 6-7, and the mixture was allowed to stand at 60-80℃ to form a first wet gel. The first wet gel was washed with water until the residual solvent was completely removed. The first wet gel with the residual solvent removed was immersed in ethanol, first frozen in liquid nitrogen, and then freeze-dried at -50℃ to obtain graphene / polyamic acid aerogel. The graphene / polyamic acid aerogel was cured in a nitrogen atmosphere at 250-300°C for 2 hours to obtain graphene / polyimide aerogel.

3. The method of claim 2, wherein the method further comprises the step of applying a flame retardant to the fabric. The preparation method of the polyamic acid precursor solution includes the following steps: Diaminodiphenyl ether was added to N,N-dimethylacetamide and stirred until dissolved to obtain a diaminodiphenyl ether solution. Add pyromellitic dianhydride to N,N-dimethylacetamide and stir until dissolved to obtain a pyromellitic dianhydride solution; The pyromellitic dianhydride solution is added dropwise to the diaminodiphenyl ether solution to ensure that the solid content of the mixed solution is 10-20 wt.%, and stirred at 0-5°C until transparent to obtain the polyamic acid precursor solution.

4. The method for preparing the intelligent fire-resistant fabric according to claim 3, characterized in that, The molar ratio of the pyromellitic dianhydride to the diaminodiphenyl ether is 1:

1.

5. The method for preparing the intelligent fire-resistant fabric according to claim 1, characterized in that, The pretreatment steps for the polyimide fiber are as follows: the polyimide fiber is soaked in ethanol for 1 hour to remove surface impurities, and then it is added to N,N-dimethylacetamide and ultrasonically treated for 30 minutes at 200-400 W power under ice bath conditions.

6. The method for preparing the intelligent fire-resistant fabric according to claim 1, characterized in that, The mass ratio of the graphene / polyimide aerogel to the polyimide fiber is (7-9):(1-3).

7. The method for preparing the intelligent fire-resistant fabric according to claim 1, characterized in that, After adding the polyamic acid solution, the proportion of the polyamic acid solution in the system is 5-10 wt.%.

8. The application of an intelligent fireproof fabric prepared by the preparation method according to any one of claims 1 to 7 in the fields of fire protection, protection, industrial electromagnetic shielding and intelligent wearable devices.

9. The application of an intelligent fire-resistant fabric prepared by the preparation method according to any one of claims 1 to 7 in the preparation of intelligent protective clothing and / or wearable devices in electromagnetic interference environments.

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