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CN-122006199-A - High-dispersibility fiber composite aerogel fire extinguishing agent and preparation method thereof

CN122006199ACN 122006199 ACN122006199 ACN 122006199ACN-122006199-A

Abstract

The invention discloses a high-dispersity fiber composite aerogel fire extinguishing agent and a preparation method thereof, wherein the fire extinguishing agent comprises, by mass, 40-55wt% of SiO 2 aerogel base material, 5-10wt% of aramid nanofiber, 5-8wt% of expanded graphite, 8-12wt% of zinc borate, 10-15wt% of polyimide, 2-5wt% of methyltrimethoxysilane and 1-3wt% of nano montmorillonite. The preparation method comprises the steps of aramid nanofiber stripping, expanded graphite pretreatment, polyimide precursor preparation, sol-gel synthesis, aging replacement, supercritical drying and hydrophobic modification. Through multicomponent synergy and dispersion optimization, the material dispersion uniformity, mechanical strength, fire extinguishing efficiency, high temperature resistance and storage stability are improved, the problems of poor dispersion, mechanical brittleness, unstable storage and the like of the traditional aerogel are solved, and the whole-process suppression of spontaneous combustion of coal is realized through grouting, spraying or filling construction.

Inventors

  • AN CHUN

Assignees

  • 安华新材科技(江苏)有限公司

Dates

Publication Date
20260512
Application Date
20260126

Claims (10)

  1. 1. The high-dispersibility fiber composite aerogel fire extinguishing agent is characterized by comprising the following components in percentage by mass: 40-55wt% of SiO 2 aerogel base material; 5-12wt% of Aramid Nanofiber (ANF); 5-12wt% of Expanded Graphite (EG); 8-12wt% of Zinc Borate (ZB); Polyimide (PI) 10-15wt%; Methyltrimethoxysilane (MTMS) 2-10wt%; 1-3wt% of nano montmorillonite.
  2. 2. The high-dispersibility fiber composite aerogel fire extinguishing agent according to claim 1, wherein the aramid nanofibers are prepared from poly (paraphenylene terephthalamide) (PPTA) fibers by chemical stripping with methane sulfonic acid, the length is 100-500nm, the diameter is 5-20nm, the expanded graphite is subjected to puffing treatment at 850-900 ℃ and the particle size is 10-50 μm, and the polyimide is formed by in-situ polymerization of 4,4' -diaminodiphenyl ether (ODA) and pyromellitic dianhydride (PMDA).
  3. 3. The high-dispersibility fiber composite aerogel fire extinguishing agent according to claim 1, wherein the porosity of the SiO 2 aerogel substrate is 85-95%, and the thermal conductivity is less than or equal to 0.025W/(m.K).
  4. 4. The high-dispersibility fiber composite aerogel fire extinguishing agent according to claim 2, wherein in the preparation process of the aramid nanofibers, the mass ratio of the poly-paraphenylene terephthalamide fibers to the methane sulfonic acid is 1:40-1:60, the chemical stripping temperature is 50-60 ℃, and the stripping time is 4-6 days.
  5. 5. The high-dispersibility fiber composite aerogel fire extinguishing agent according to claim 2, wherein the expanded graphite is pretreated by a method that the expandable graphite is subjected to high-temperature puffing at 850-900 ℃ for 30-60 seconds, crushed and then screened by a 300-1000 mesh sieve, then immersed in 1-3wt% of silane coupling agent KH-550 ethanol solution, stirred for 1-2 hours at 50-60 ℃, and dried for later use.
  6. 6. The high-dispersibility fiber composite aerogel fire extinguishing agent according to claim 2, wherein the polyimide has a monomer molar ratio of 4,4' -diaminodiphenyl ether (ODA) of pyromellitic dianhydride=1:1.02-1:1.05, and a polyimide precursor solution concentration of 12-18wt%.
  7. 7. A method for preparing the high-dispersibility fiber composite aerogel fire extinguishing agent according to any one of claims 1 to 6, which comprises the following steps: (1) Preparation of Aramid Nanofibers (ANF) Immersing poly-p-phenylene terephthamide (PPTA) fibers into methane sulfonic acid, wherein the mass ratio of the poly-p-phenylene terephthamide fibers to the methane sulfonic acid is 1:40-1:60, stirring for 4-6 days at 50-60 ℃ to perform chemical stripping to obtain an aramid nanofiber dispersion with the mass fraction of 2-3% for later use; (2) Expanded Graphite (EG) pretreatment Puffing expandable graphite at 850-900 deg.C for 30-60s, pulverizing, sieving with 300-1000 mesh sieve, soaking the puffed graphite in 1-3wt% silane coupling agent KH-550 ethanol solution, stirring at 50-60 deg.C for 1-2h, and oven drying; (3) Preparation of polyimide Precursor (PAA) Mixing 4,4 '-diaminodiphenyl ether (ODA) and N, N-dimethylacetamide, stirring until the mixture is completely dissolved, cooling to 0-5 ℃ in an ice bath, slowly adding pyromellitic dianhydride, wherein the molar ratio of the 4,4' -diaminodiphenyl ether to the pyromellitic dianhydride is 1:1.02-1:1.05, and stirring for 2-4 hours to obtain polyimide precursor solution with the mass fraction of 12-18 wt%; (4) SiO 2 Sol preparation Mixing Tetraethoxysilane (TEOS), ethanol and deionized water according to a molar ratio of 1:2:2.5-1:3:3, adding hydrochloric acid to adjust the pH value to 2-3, and hydrolyzing at 70-80 ℃ for 1-1.5h to obtain SiO 2 sol; (5) Co-gel synthesis Weighing the raw materials obtained in the step 1-4 according to a proportion, adding 5-12% of expanded graphite, 8-12% of zinc borate and 1-3% of nano montmorillonite into SiO 2 sol, and performing ultrasonic dispersion for 20-30min; Continuously adding the aramid nanofiber dispersion liquid, wherein the aramid nanofiber is added according to the proportion of 5-12% of the mass of the aerogel, and mechanically stirring for 30-40min to form a uniform dispersion system; slowly adding polyimide precursor solution into the obtained uniform dispersion system, adding polyimide accounting for 10-15% of the mass of the aerogel, stirring for 20-30min, adding ammonia water to adjust pH to 7.5-8.5, standing at room temperature for gel for 12-24h to obtain cogel; (6) Aging and solvent displacement Aging the cogel in an oven at 80-90 ℃ for 8-12h, then replacing the cogel with absolute ethyl alcohol for 3-4 times, each time for 6-8h, and removing water and residual solvent in the system; (7) Drying treatment Carrying out supercritical CO 2 drying on the cogel subjected to solvent replacement, wherein the drying temperature is 35-45 ℃, the air pressure is 8-12MPa, and the drying time is 24-36h, so as to obtain a composite aerogel intermediate; (8) Hydrophobically modified Immersing the composite aerogel intermediate in methyl trimethoxy silane ethanol solution, stirring for 2-3h at 50-60 ℃, taking out, and drying for 2-4h at 80-100 ℃ to obtain the composite aerogel extinguishing agent.
  8. 8. The method according to claim 7, wherein the power of ultrasonic dispersion in the step (5) is 300 to 500W and the rotation speed of mechanical stirring is 600 to 800r/min.
  9. 9. The preparation method according to claim 7, wherein the temperature rising rate of supercritical CO 2 in the step (7) is 1-2 ℃ per minute, the pressure releasing rate is 0.5-1MPa per hour, and the volume fraction of the methyltrimethoxysilane ethanol solution in the step (8) is 50-60%.
  10. 10. Use of a highly dispersible fiber composite aerogel fire suppression agent according to any one of claims 1 to 6 in coal mine fire protection and suppression, wherein the fire suppression agent is applicable to goaf or roadway areas of coal mine by grouting, spraying or filling, for suppressing spontaneous combustion of coal and extinguishing coal mine fires.

Description

High-dispersibility fiber composite aerogel fire extinguishing agent and preparation method thereof Technical Field The invention belongs to the technical field of coal mine fire prevention and extinguishing materials, and particularly relates to a high-dispersibility fiber composite aerogel fire extinguishing agent and a preparation method thereof, which are suitable for preventing and controlling spontaneous combustion of coal in complex environments such as a coal mine goaf. Background Coal is used as a core component of the Chinese energy structure, has an irreplaceable effect in the fields of metallurgy, chemical industry, electric power and the like, and is expected to maintain the dominant energy status in the next twenty years. However, the problem of spontaneous combustion of coal is always a key bottleneck for restricting the safe production of coal mines, and more than 90% of coal seams in large and medium mining areas in China have flammable or spontaneous combustion tendency, about 2 hundred million tons of coal resource loss is caused by spontaneous combustion of coal each year, and fire accidents caused by spontaneous combustion cause a large number of casualties and property loss, and simultaneously release toxic and harmful gases such as CO, SO 2 and the like to severely pollute the environment. The spontaneous combustion of residual coal in the goaf of the coal mine has the characteristics of concealment, uncertainty, persistence and the like, and the traditional fire prevention and extinguishing means such as grouting, inert gas injection, single inhibitor spraying and the like have obvious limitations. The grouting material is easy to block the pipeline and has poor water retention, the fire extinguishing effect is short due to easy leakage of inert gas, the whole coal spontaneous combustion process is difficult to be inhibited by a single inhibitor, and the grouting material is easy to fail in a high-temperature stage. Therefore, development of a novel fire preventing and extinguishing material with high mechanical strength, good dispersibility, long-acting fire extinguishing performance and environmental suitability becomes an urgent need in the field of coal mine safety. Aerogel, as a novel porous material with high porosity (80-99.8%), low thermal conductivity (0.005-0.02W/(m·k)), exhibits great potential in the field of fire prevention and extinguishment. The SiO 2 aerogel has low preparation cost and excellent heat insulation performance, and becomes a research hot spot of mining fire prevention and extinguishing materials. However, the traditional SiO 2 aerogel has the defects of high mechanical brittleness, poor dispersibility, easy failure due to moisture absorption and the like, and limits the application of the traditional SiO 2 aerogel in complex underground environments. To improve the mechanical properties of aerogels, researchers have attempted to incorporate fibrous materials for reinforcement. The preparation method comprises the steps of (1) activating clay mineral fibers to obtain acid-activated nano clay mineral fibers, (2) preparing a nano clay mineral fiber three-dimensional composite material to obtain a three-dimensional fiber block composite gel material B, (3) immersing the three-dimensional fiber block composite gel material B in a component C solution, curing for 30-150min at 50-120 ℃, soaking in an organic solvent, and carrying out vacuum freeze-drying to obtain the nano clay mineral fiber-reinforced three-dimensional structure phenolic resin aerogel material which can be used for heat preservation and insulation of high-end equipment or used as a catalyst carrier, an adsorbent for organic pollutants and the like. CN111849018B discloses a rectorite-based flame-retardant aerogel, which comprises polyaniline/polyvinyl alcohol composite aerogel and a rectorite@cellulose nanocrystalline composite material in situ compounded in the composite aerogel, wherein the rectorite@cellulose nanocrystalline composite material comprises two-dimensional rectorite and one-dimensional cellulose nanocrystalline compounded between layers and/or on the surface of the rectorite/polyvinyl alcohol composite aerogel. The preparation method comprises the steps of carrying out self-assembly modification on rectorite by cellulose nanocrystals in advance, then carrying out aniline in-situ polymerization and PVA mutual doping modification, and finally carrying out freeze drying to obtain the flame-retardant aerogel with excellent mechanical properties and flame retardance. However, in the coal mine environment, the problems of uneven dispersion caused by insufficient compatibility of the fiber and the aerogel matrix, lack of a response fire extinguishing mechanism aiming at the coal spontaneous combustion temperature range, and difficulty in maintaining long-acting fire extinguishing effect due to easy degradation of the fiber at high temperature still exist. As a high-efficiency environme