Intelligent fireproof fabric and preparation method and application thereof

Abstract

The invention discloses an intelligent fireproof fabric and a preparation method and application thereof, and belongs to the technical field of fireproof materials.Graphene / polyimide aerogel is blended with polyimide fibers to prepare a composite fabric, graphene / polyimide aerogel in-situ synthesis enables the composite fabric to have good dispersion uniformity and bonding strength, and the graphene / polyimide aerogel in-situ synthesis enables the composite fabric to have good flame retardance. Meanwhile, the aerogel taking the polyimide as the matrix and the polyimide fiber have the same molecular structure and chemical composition and have a good interface structure, and the strength of the composite fabric is enhanced. The thermal decomposition temperature of the intelligent fireproof fabric is increased (5% thermal decomposition temperature gt; meanwhile, the high temperature resistance and the flame retardant property are also improved. According to the intelligent fireproof fabric, the aerogel is used as a light filler, a low-density and high-air-permeability protective layer is prepared, the overall weight of the intelligent fireproof fabric is reduced, and the wearing comfort is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fire protection materials, and particularly relates to an intelligent fireproof fabric, a preparation method thereof, and an application thereof. Background Art

[0002] Protective fabrics are widely used in the fields of fire protection, chemical protection, industrial protection, and military. They usually have certain properties such as heat resistance, chemical corrosion resistance, abrasion resistance, and flame retardancy. Existing protective fabrics mostly use polyester fibers, aramid fibers, polyimide fibers, etc. as substrates, and these materials enhance their performance through multi-layer compounding, coating, or adding special materials. Among them, flame retardant fabrics usually use chlorine- and phosphorus-containing flame retardants or add flame retardant coatings. Fireproof and protective fibers generally use materials with good thermal stability and high temperature resistance, such as aramid fibers, polyimide fibers, etc. However, the thermal stability and mechanical properties of the above single fabrics may be insufficient when exposed to extreme environments. The mechanical strength of traditional protective fabrics gradually decreases after long-term exposure to high temperatures or physical friction, and problems such as tearing and abrasion are likely to occur, resulting in a reduction in protective performance. In order to enhance the protective performance, many traditional protective fabrics adopt thick coatings or multi-layer composite structures, which lead to poor breathability of the fabric. Wearers will feel stuffy and uncomfortable after long-term use, and it may even affect work efficiency and safety. Traditional protective materials usually cannot effectively avoid static electricity accumulation or electromagnetic interference. In some high-risk environments (such as chemical production, electronic equipment protection, etc.), static electricity discharge may trigger safety accidents, and electromagnetic interference may also affect the normal operation of electronic equipment.

[0003] Patent CN110205832A discloses a double-sided grid aerogel thermal insulation felt for fire-fighting clothing with good breathability. The aerogel technology applied in the thermal insulation protection device provided by this patent can solve problems such as a sharp reduction in breathability, poor adhesion of aerogel, and affecting the wearing comfort. However, the fabric obtained by compounding silica aerogel powder with aramid-based felt used in this patent is prone to problems such as poor adhesion and aerogel shedding; and this patent uses grid bars to conduct air, which increases the extra weight and process cost.

[0004] Patent CN115107338A discloses a fireproof fabric for fire-fighting clothing. This patent provides a fireproof fabric applied in a harmful chemical agent protection device, which can solve problems such as the existing fireproof fabric being unable to maintain continuous combustion, poor heat insulation effect, and firefighters being fatigued at work. However, the thermal 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 there is a problem of poor adhesion between aerogel and fiber, and aerogel shedding; and in today's complex fire field environment, there is no potential for further intelligent upgrading. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides an intelligent fireproof fabric, its preparation method and application. The intelligent fireproof fabric of the present invention has a protective layer with low density and high air permeability, which reduces the overall weight and improves the wearing comfort.

[0006] The present invention provides an intelligent fireproof fabric, which has a sandwich structure. The middle layer is a composite fabric of graphene / polyimide aerogel and polyimide fiber blended, the outer layer is a fireproof polyimide fiber cloth, and the inner layer is aramid fiber.

[0007] The present invention also provides a preparation method of the above intelligent fireproof fabric, which includes the following steps:

[0008] After in-situ synthesizing graphene / polyimide aerogel, mix the graphene / polyimide aerogel with pretreated polyimide fiber, add polyamic acid solution after stirring evenly, let it stand to obtain a second wet gel. After the second wet gel is washed, freeze-dried and cured under a nitrogen atmosphere, a composite fabric of graphene / polyimide aerogel and polyimide fiber blended is obtained;

[0009] Take the composite fabric of graphene / polyimide aerogel and polyimide fiber blended as the middle layer, the fireproof polyimide fiber cloth as the outer layer, and the aramid fiber as the inner layer, and obtain the intelligent fireproof fabric through hot pressing and forming.

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

[0011] Mix the graphene dispersion liquid with the polyamic acid precursor liquid, adjust the pH to 6 - 7, let it stand at 60 - 80 °C to form a first wet gel, wash the first wet gel with water until the residual solvent is completely removed, soak the first wet gel after removing the residual solvent in ethanol, first freeze it in liquid nitrogen, and then freeze-dry it at -50 °C to obtain graphene / polyamic acid aerogel;

[0012] Cure the graphene / polyamic acid aerogel 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 liquid includes the following steps:

[0014] Disperse graphene powder in water and ultrasonicate it under ice bath conditions to obtain a graphene dispersion liquid with a concentration of 1 - 2 mg / mL;

[0015] Add diaminodiphenyl ether to N,N-dimethylacetamide, stir 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] Drop the pyromellitic dianhydride solution into the diaminodiphenyl ether solution, ensuring that the solid content of the mixed solution is 10-20 wt.%, and stir until transparent at a temperature of 0-5°C to obtain a polyamic acid precursor solution.

[0018] Furthermore, the preparation method of the composite fabric with graphene / polyimide aerogel blended with polyimide fiber is as follows: Mix the graphene / polyimide aerogel with the pretreated polyimide fiber, stir evenly and then add the polyamic acid solution. Let it stand for 24 hours at 60-80°C to obtain a second wet gel. Immerse the second wet gel in ethanol, wash it with water and then freeze-dry it. Under a nitrogen atmosphere, cure it at 250-300°C for 2 hours to obtain the composite fabric with graphene / polyimide aerogel blended with polyimide fiber.

[0019] Conventional fireproof materials are prone to cracking and wear under extreme use conditions and have poor durability. The graphene in the intelligent fireproof fabric of the present invention significantly improves the tensile strength, bending strength and wear resistance of the material, making the intelligent fireproof fabric of the present invention have better mechanical properties and long-term stability. The present invention uses the method of composite nanomaterials to blend graphene / polyimide aerogel with polyimide fiber to make a composite fabric. The in-situ synthesis of graphene / polyimide aerogel gives it good dispersion uniformity and bonding strength. At the same time, the aerogel with polyimide as the matrix (i.e., graphene / polyimide aerogel) has the same molecular structure and chemical composition as the polyimide fiber and has a good interfacial structure, enhancing the strength of the composite fabric. The thermal decomposition temperature of the intelligent fireproof fabric of the present invention is increased (5% thermal decomposition temperature > 500°C), and at the same time, the high-temperature resistance and flame retardancy are also improved. Traditional heavy protective materials affect wearing comfort and hinder long-term work. The intelligent fireproof fabric of the present invention uses aerogel as a lightweight filler to prepare a protective layer with low density and high breathability, reducing the overall weight of the intelligent fireproof fabric and improving the wearing comfort. Moreover, traditional fireproof fabrics do not have electromagnetic shielding and antistatic functions and cannot be effectively used in special environments (such as electromagnetic interference). The present invention blends graphene with polyimide fiber to construct a complete conductive network in the fabric. On the one hand, it provides a path for the transmission of electrical signals. On the other hand, the electrons inside it can be rearranged according to the external electromagnetic field in the protective fabric to neutralize the influence of the external electromagnetic field, making it suitable for intelligent protective clothing and electromagnetic shielding environments.

[0020] In the present invention, the aerogel matrix (graphene / polyimide aerogel) and the polyimide fiber have 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 the interfacial stress and enhancing the bonding strength. Meanwhile, during the preparation process of the composite fabric, the polyamic acid solution penetrates into the gaps between the graphene / polyimide aerogel and the polyimide fiber as an adhesive. After high-temperature curing, the polyamic acid is converted into polyimide, which undergoes a polycondensation reaction with the polyimide fiber body to form a continuous phase structure connected by covalent bonds, further strengthening the bonding force between the graphene / polyimide aerogel and the polyimide fiber. Moreover, graphene forms a continuous conductive network in the fabric, and the oxygen-containing functional groups (such as hydroxyl groups and epoxy groups) at its edges have strong interactions with the polar groups on the surface of the polyimide fiber. This bridging effect further locks the relative positions of the graphene / polyimide aerogel and the polyimide fiber. Therefore, in the intelligent fireproof fabric of the present invention, the aerogel and the fiber are firmly attached, and the aerogel is not easily detached.

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

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

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

[0024] In the preparation method of the intelligent fireproof fabric, the pretreatment step of the polyimide fiber is as follows: soak the polyimide fiber in ethanol for 1 hour to remove surface impurities, then add it to N,N-dimethylacetamide, and perform ultrasonic treatment at a power of 200 - 400 W for 30 minutes under ice bath conditions.

[0025] In the preparation method of the intelligent fireproof fabric, the mass ratio of the graphene / polyimide aerogel to the polyimide fiber is (7 - 9)∶(1 - 3). Exemplarily, the mass ratio of the graphene / polyimide aerogel to the polyimide fiber is 7∶3, 8∶2, or 9∶1.

[0026] In the preparation method of the 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 intelligent fireproof fabric in the preparation of intelligent protective clothing and / or wearable devices in an electromagnetic interference environment.

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

[0030] The intelligent fireproof fabric of the present invention is a composite fabric of graphene / polyimide aerogel and polyimide fiber, which integrates excellent properties such as flame retardancy, conductivity, light weight, and chemical corrosion resistance. It is a multifunctional material, especially suitable for the fields of fire protection, protection, industrial electromagnetic shielding, and intelligent wearable devices. Among them, the synergistic effect of graphene and polyimide increases the 5% thermal decomposition temperature of the fabric to above 500 °C, effectively ensuring its safety in high-temperature environments. In addition, as a free radical scavenger, graphene delays the thermal degradation of the material, thereby delaying the combustion time. The strengthening effect of graphene also significantly improves the mechanical strength of the intelligent fireproof fabric. For example, the tensile strength of the intelligent fireproof fabric is increased to above 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 enables the fabric to exhibit higher durability in severely stretched or bent environments. At the same time, graphene constructs a conductive network in the intelligent fireproof fabric, endowing the fabric with excellent antistatic properties. Its moderate conductivity can also be used for intelligent protective clothing or wearable devices in an electromagnetic interference environment. The low-density characteristic of the aerogel makes the intelligent fireproof fabric lightweight, suitable for preparing fireproof clothing for long-term wear. The pores in the aerogel structure improve air flow and enhance wearing comfort. The high strength, high thermal stability, and electromagnetic shielding ability of the intelligent fireproof fabric provide comprehensive performance guarantees for fireproof clothing and special protective clothing. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0032] Figure 1 is the synthesis process and molecular formula of graphene / polyimide aerogel;

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

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

[0035] Figure 4 is the SEM photograph of the fireproof fabric in Comparative Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as a limitation on 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 terms used in the present invention are only for describing particular embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0038] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0039] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and embodiments of the present invention are merely exemplary.

[0040] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

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

[0042] Disperse graphene powder in water, and ultrasonicate (with the power set to 200 - 400 W) for 1 hour under an ice bath condition to obtain a uniformly mixed graphene dispersion with a concentration of 1 - 2 mg / mL;

[0043] Dropwise add 4,4'-oxydianiline (ODA) to N,N-dimethylacetamide (DMAc) at a molar ratio of 1:1, and stir for 2 hours until completely dissolved to obtain an ODA solution;

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

[0045] The PMDA solution was dropped into the ODA solution to ensure that the solid content of the mixed solution was 10 - 20 wt.%, and it was stirred until transparent at a temperature of 0 - 5 °C to obtain a 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 mixed solution was 5 - 15%. The pH was adjusted to 6 - 7 with ammonia water or ethylenediamine to promote stable compounding. The mixed solution was poured into a mold and left standing at 60 - 80 °C for 24 hours to form a 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 for solvent replacement. The first wet gel after solvent replacement was first quickly frozen in liquid nitrogen and then freeze-dried at -50 °C for 48 hours to obtain a graphene / polyamic acid aerogel;

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

[0048] The polyimide fiber (PI fiber) was soaked in ethanol for 1 hour to remove surface impurities. Subsequently, the polyimide fiber treated as above was added to DMAc and ultrasonically treated at a power of 200 - 400 W for 30 minutes under ice bath conditions to ensure uniform dispersion of the PI fiber, obtaining a pretreated PI fiber;

[0049] The graphene / polyimide aerogel and the pretreated PI fiber were mixed in a mass ratio of (7 - 9)∶(1 - 3) and stirred in a mechanical stirrer at a rate of 300 rpm for 2 hours to ensure that the PI fiber was evenly distributed in the aerogel matrix. Subsequently, a 20 wt.% polyamic acid (PAA) precursor solution (the PAA precursor solution can improve the overall strength and adhesion of the material) was added to make the proportion of the PAA precursor solution in the system 5 - 10 wt.%. The mixed solution was poured into a mold (according to the fabric size) and left standing at 60 - 80 °C 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 DMAc and other solvent residues were removed. Then it was freeze-dried at -50 °C for 48 hours and cured in a nitrogen atmosphere at 250 - 300 °C for 2 hours to obtain a composite fabric of graphene / polyimide aerogel and PI fiber blend to promote the conversion of PAA to polyimide and prevent material oxidation;

[0050] The composite fabric obtained by blending graphene / polyimide aerogel with PI fibers is used as the middle layer, the fireproof polyimide fiber cloth is used as the outer layer, and the skin-friendly layer woven with aramid fiber fabric is used as the inner layer. After hot pressing and forming, an intelligent fireproof fabric is obtained.

[0051] Hot pressing and forming is a forming process that processes materials under high temperature and high pressure, and is widely used in the fields of manufacturing high-performance composite materials, plastic products, etc. In the following examples of the present invention, the method of hot pressing and forming is as follows: Cut the above three-layer fabrics to the required size, clean the surface to remove impurities, and then dry them in an oven at 80 °C for 2 hours; then lay them flat in the mold in the order of "outer layer → middle layer → inner layer", ensure that each layer is aligned without wrinkles, put them into the hot pressing mold, and the temperature during the hot pressing and forming process is 280 - 300 °C (it needs to be higher than the glass transition temperature of polyimide to ensure the molecular chain fluidity and interlayer fusion); the pressure is 8 - 12 MPa (too high pressure may cause damage to the pore structure of the aerogel, and it needs to be optimized through preliminary experiments). After maintaining at 8 - 12 MPa for 20 - 30 min, naturally cool to below 80 °C under the pressure maintaining state, then release the pressure and demold to prevent delamination or deformation caused by rapid cooling. Finally, cut off the edge flash and check the integrity of the interlayer bonding.

[0052] The intelligent fireproof fabric of the embodiment of the present 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 prepare intelligent protective clothing and wearable devices in an electromagnetic interference environment.

[0053] In the comparative example of the following examples of the present invention, the fireproof polyimide fiber cloth of the outer layer is the P84 polyimide flame retardant fiber cloth purchased from Wuxi Yaoxin Textile Co., Ltd., which is a flame retardant, heat insulation and fireproof material, and the density is 1800 g / m 2 ; the aramid used in the skin-friendly layer woven with aramid fiber fabric of the inner layer is the aramid flame retardant fabric purchased from Jiangsu Tiandizao New Material Technology Co., Ltd., and the gram weight is 200 g / m 2 .

[0054] Unless otherwise specified, the room temperature in the present invention is calculated as 25 ± 2 °C.

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

[0056] The technical solutions of the present invention will be further described below through examples.

[0057] Example 1

[0058] This example provides a preparation method of an intelligent fireproof fabric, and the specific method is as follows:

[0059] Disperse graphene powder (1250 mesh) in deionized water, and then ultrasonically treat it for 1 hour under ice bath conditions with an ultrasonic power of 300 W to obtain a uniformly dispersed graphene solution with a concentration of 1.5 mg / mL;

[0060] Using N,N-dimethylacetamide (DMAc) as a solvent, gradually add 4,4'-oxydianiline (ODA) dropwise at a molar ratio of 1:1, and stir for 2 hours until completely dissolved to obtain an ODA solution;

[0061] Dissolve pyromellitic dianhydride (PMDA) with an equimolar amount of ODA in N,N-dimethylacetamide (DMAc), and then drop it into the above ODA solution. Control the reaction temperature at 3 °C to ensure that the solid content of the mixed solution is 15 wt.%, and continue to stir at room temperature for 12 hours to form a transparent polyamic acid (PAA) precursor solution;

[0062] Mix the graphene solution with the PAA precursor solution to ensure that the mass fraction of graphene in the final mixed solution is 10%. Stir at room temperature for 4 hours to ensure that the graphene is uniformly dispersed in the PAA matrix, and adjust the pH to 7 with ammonia water to promote stable compounding. Pour the obtained mixed solution into a mold and let it stand at 70 °C for 24 hours to form a wet gel. Wash the wet gel repeatedly with deionized water until the residual solvent is removed. Immerse the wet gel in ethanol for 24 hours for solvent replacement; first, quickly freeze the wet gel after solvent replacement in liquid nitrogen, and then freeze-dry it at -50 °C for 48 hours to obtain a graphene / PAA aerogel;

[0063] Cure the obtained graphene / PAA aerogel in a nitrogen atmosphere at 280 °C for 2 hours to promote the conversion of PAA to polyimide and prevent material oxidation to obtain a graphene / polyimide aerogel (G / PI aerogel);

[0064] Immerse polyimide fibers (PI fibers) in ethanol for 1 hour to remove surface impurities. Then add the polyimide fibers treated above to DMAc and ultrasonically treat them at a power of 300 W under ice bath conditions for 30 minutes to ensure uniform dispersion of the fibers;

[0065] Mix the graphene / polyimide aerogel with uniformly dispersed polyimide fibers (the graphene / polyimide aerogel accounts for 90 wt.% of the total mass of the graphene / polyimide aerogel and polyimide fibers, and the polyimide fibers account for 10 wt.% of the total mass of the graphene / polyimide aerogel and polyimide fibers), and stir in a mechanical stirrer at 300 rpm for 2 hours to ensure that the polyimide fibers are evenly distributed in the graphene / polyimide aerogel matrix. Subsequently, add a polyamic acid (PAA) precursor solution with a concentration of 20 wt.%, so that the proportion of the PAA precursor solution in the mixed system is 8 wt.%, to obtain a mixed solution (the role of the PAA precursor solution is to further improve the overall strength and adhesion of the fireproof fabric). Pour the mixed solution into a mold (according to the fabric size), and let it stand at 70 °C for 24 hours to form a wet gel. Then soak the wet gel in ethanol for 12 hours and wash it repeatedly to remove residual solvents such as DMAc. Then freeze-dry at -50 °C for 48 hours to form a lightweight composite fabric, and perform a curing treatment in a nitrogen atmosphere at 280 °C for 2 hours to promote the conversion of PAA to polyimide and prevent material oxidation, to obtain a composite fabric blended with graphene / polyimide composite aerogel and polyimide fibers.

[0066] Use the above composite fabric as the core heat-insulating layer in the middle, the outer layer is a fireproof polyimide fiber cloth, and the inner layer is a skin-friendly layer woven from aramid fiber fabric. The three layers of materials are formed by hot pressing. The specific method of hot pressing is as follows: Cut the above three layers of fabric to the required size, clean the surface to remove impurities, and then dry in an oven at 80 °C for 2 hours; then lay them flat in the mold in the order of "outer layer → middle layer → inner layer", ensure that each layer is aligned without wrinkles, put it into the hot pressing mold, the temperature during the hot pressing process is 290 °C, after maintaining at 10 MPa for 25 min, naturally cool to below 80 °C under the pressure-holding state, and then release the pressure and demold to prevent delamination or deformation caused by rapid cooling. Finally, cut off the edge flash, check the integrity of the interlayer bonding, and ensure that they are closely fitted to obtain the intelligent fireproof fabric.

[0067] Example 2

[0068] In this example, the preparation method of the intelligent fireproof fabric is the same as that in Example 1, except that the graphene / polyimide aerogel accounts for 80 wt.% of the total mass of the graphene / polyimide aerogel and polyimide fibers, and the polyimide fibers account for 20 wt.% of the total mass of the graphene / polyimide aerogel and polyimide fibers.

[0069] The SEM photograph of the graphene / polyimide aerogel in this example is shown in Figure 2 ; The high-temperature resistance photograph of the intelligent fireproof fabric in this example is shown in Figure 3 , indicating that the intelligent fireproof fabric prepared by the present invention has good high-temperature resistance characteristics.

[0070] Example 3

[0071] In this example, the preparation method of the intelligent fireproof fabric is the same as that in Example 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] The polyimide fiber was soaked in ethanol for 1 hour to remove surface impurities, and then added to DMAc, and ultrasonically treated at a power of 300 W for 30 minutes under ice bath conditions to ensure uniform dispersion of the fibers. It was stirred at 300 rpm in a mechanical stirrer for 2 hours, and then a PAA precursor solution with a concentration of 20 wt.% was added, so that the proportion of the PAA precursor solution in the mixed system was 8 wt.%. The obtained mixed solution was poured into a mold (according to the fabric size) and left standing at 70 °C for 24 hours to form a wet gel. Then the wet gel was soaked in ethanol for 12 hours and washed repeatedly to remove residual solvents such as DMAc. It was freeze-dried at -50 °C for 48 hours to obtain a lightweight composite fabric. The lightweight composite fabric was cured at 280 °C in a nitrogen atmosphere for 2 hours to promote the conversion of PAA to polyimide and prevent material oxidation, and a composite fabric was obtained;

[0074] Taking the above composite fabric as the core heat insulation layer in the middle, the outer layer is a fireproof polyimide fiber cloth, and the inner layer is a skin-friendly layer woven with aramid fiber fabric. The three-layer materials are hot-pressed to ensure tight fitting, and then the fireproof fabric is obtained.

[0075] The SEM photograph of the fireproof fabric prepared in this comparative example is shown in Figure 4 , and it can be seen that the polyimide presents a spatial network structure and there is no graphene coverage on it.

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

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

[0078]

[0079]

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

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

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

[0083]

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

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

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

[0087]

[0088] As can be seen from 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] Graphene was not introduced in Comparative Example 1, and the bonding strength between the aerogel and the fiber could not be improved through its bridging effect (while in the present invention, graphene can provide hydrogen bonds and π-π interactions to improve the bonding strength between the aerogel and the fiber). Therefore, the composite fabric in Comparative Example 1 lacks electrical conductivity and electromagnetic shielding performance, and its mechanical strength is reduced.

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

[0091] Table 4 Retention mass percentage of the fireproof fabrics prepared in Examples 1-3 and Comparative Example 1

[0092]

[0093] As can be seen from Table 4, the retention mass of the fireproof fabrics in Examples 1-3 is slightly less than that in Comparative Example 1, indicating that the fireproof fabrics in Examples 1-3 have good durability and washing stability.

[0094] It can be seen from Examples 1-3 that the ratio of graphene / polyimide aerogel to polyimide fiber affects the performance of the fireproof fabric, specifically manifested as follows:

[0095] (1) Influence on mechanical properties

[0096] In the high G / PI aerogel ratio, the high modulus of graphene and the porous structure of the aerogel can improve the compression resilience and anti-deformation ability of the fabric. However, too much aerogel will lead to a decrease in the bonding force between fibers, and the tensile strength and flexibility of the fireproof fabric will be reduced (brittle fracture may occur). In the high PI fiber ratio, the high strength and toughness of the polyimide fiber dominate the mechanical properties, and the fabric is softer and more resistant to repeated bending. However, insufficient aerogel will reduce the buffering effect of the porous structure, and the anti-impact performance may be limited.

[0097] (2) Influence on thermal properties

[0098] In the high G / PI aerogel ratio, the porous structure of the aerogel significantly reduces heat conduction, and the nanosheets of graphene can reflect radiant heat, synergistically improving the flame retardancy (such as an increase in the oxygen index). At the same time, the high-temperature resistance of graphene (>500 °C) delays the thermal decomposition of polyimide, and the mass retention rate is higher at high temperatures. In the high PI fiber ratio, polyimide itself has a high limiting oxygen index (LOI>30%), but the dense arrangement of fibers may form heat conduction channels, reducing the overall heat insulation efficiency.

[0099] (3) Influence on electrical conductivity

[0100] In the high G / PI aerogel ratio, graphene forms a continuous conductive network, and the surface resistivity of the fabric is significantly reduced (can reach 10 2 -10 4 Ω / sq), suitable for anti-static or electromagnetic shielding scenarios.

[0101] (4) Influence on the percentage of retained mass (durability)

[0102] In the high G / PI aerogel ratio, the aerogel is easily detached due to mechanical friction during washing, resulting in a decrease in the mass retention rate. In the high PI fiber ratio, the fiber matrix provides a skeleton support, and the mass retention rate is higher after washing. Since aerogel materials are difficult to process and form, they are generally used as rigid materials (such as in batteries). The strength of the aerogel material alone as a fireproof layer is insufficient, and it is very easy to fall off when combined with other fibers or fabrics to prepare fireproof materials. Moreover, it is difficult to make flexible materials such as fabrics after the aerogel material is compounded with fibers. The present invention uses graphene / polyimide aerogel composite polyimide fibers, which can solve the problems existing in the preparation of fabrics with aerogel materials. From the data in Table 1 - Table 4, it can be seen that the present invention can successfully use the aerogel material as a wearable protective clothing, suitable for anti-static or electromagnetic shielding scenarios, and at the same time can solve the problem that the aerogel material is easily detached after being compounded with fibers.

[0103] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An intelligent fireproof fabric, characterized in that: It has a sandwich structure, with the middle layer being a composite fabric blended from graphene / polyimide aerogel and polyimide fiber, the outer layer being a fire-resistant polyimide fiber cloth, and the inner layer being aramid fiber.

2. A method for preparing the intelligent fireproof fabric according to claim 1, characterized in that: The following steps are involved: After in-situ synthesis of graphene / polyimide aerogel, the graphene / polyimide aerogel is mixed with pretreated polyimide fiber, and after being stirred evenly, a polyamic acid solution is added, and the mixture is allowed to stand to obtain a second wet gel, and the second wet gel is washed, freeze-dried, and cured in a nitrogen atmosphere to obtain a composite fabric of graphene / polyimide aerogel and polyimide fiber blended together; The intelligent fireproof fabric is obtained by hot pressing a composite fabric blended with the graphene / polyimide aerogel and polyimide fiber as a middle layer, a fireproof polyimide fiber cloth as an outer layer, and an aramid fiber as an inner layer.

3. The method for preparing the intelligent fireproof fabric according to claim 2, characterized in that: The preparation method of the in-situ synthesized graphene / polyimide aerogel comprises the following steps: The graphene dispersion liquid is mixed with the polyamic acid precursor liquid, the pH is adjusted to 6-7, and the mixture is allowed to stand at 60-80° C. to form a first wet gel, the first wet gel is washed with water until the residual solvent is completely removed, the first wet gel after the residual solvent is removed is immersed in ethanol, first frozen in liquid nitrogen, and then freeze-dried at -50° C. to obtain a graphene / polyamic acid aerogel; The graphene / polyamic acid aerogel is cured in a nitrogen atmosphere at 250-300° C. for 2 hours to obtain a graphene / polyimide aerogel.

4. The method for preparing the intelligent fireproof fabric according to claim 3, characterized in that: The method for preparing the polyamic acid precursor solution comprises the following steps: Adding diaminodiphenyl ether to N,N-dimethylacetamide, stirring until dissolved to obtain a diaminodiphenyl ether solution; Add pyromellitic anhydride to N,N-dimethylacetamide and stir until dissolved to obtain a pyromellitic anhydride solution; The pyromellitic anhydride solution is added dropwise into the diaminodiphenyl ether solution to ensure that the solid content of the mixed solution is 10-20 wt.%, and stirred at a temperature of 0-5° C. until transparent to obtain the polyamic acid precursor solution.

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

1.

6. The method for preparing the intelligent fireproof fabric according to claim 2, characterized in that: The pretreatment step of the polyimide fiber is: immersing the polyimide fiber in ethanol for 1 hour to remove surface impurities, then adding the polyimide fiber to N,N-dimethylacetamide, and ultrasonically treating the polyimide fiber at a power of 200-400W for 30 minutes under ice bath conditions.

7. The method for preparing the intelligent fireproof fabric according to claim 2, characterized in that: The mass ratio of the graphene / polyimide aerogel to the polyimide fiber is (7-9): (1-3).

8. The method for preparing the intelligent fireproof fabric according to claim 2, characterized in that: After the polyamic acid solution is added, the proportion of the polyamic acid solution in the system is 5-10 wt.%.

9. Application of the intelligent fireproof fabric according to claim 1 in the fields of fire protection, protection, industrial electromagnetic shielding and intelligent wearable devices.

10. Use of the intelligent fireproof fabric according to claim 1 in the preparation of intelligent protective clothing and / or wearable devices in electromagnetic interference environments.

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