A dual temperature-sensitive staged release gas water-based fire extinguishing aid adapted to airborne high pressure jet

Abstract

This invention discloses a dual-temperature-sensitive, staged-release water-based fire extinguishing agent adapted to airborne high-pressure jets, belonging to the field of fire extinguishing agent technology. The invention uses temperature-sensitive modified hydroxypropyl methylcellulose and PEG-coated sodium bicarbonate microcapsules as its core components. Relying on the physical isolation of PEG at room temperature and the sequential temperature difference of 42℃ / 60℃, it constructs a coupled system of first forming a gel and then sealing and releasing gas, overcoming the industry's technical bias that gas-producing components destroy the gel. The original solution of this invention is a neutral, low-viscosity fluid, suitable for long-distance spraying at 3~8MPa using 0.5~3mm nozzles from drones and manned helicopters. It employs online mixing via a post-pump Venturi system, ensuring the microcapsule coating remains intact under high-pressure impact. When diluted 1:50~100, it forms a highly adhesive, elastic gel at ≥42℃ to lock in water, and at ≥60℃, it releases CO2 at specific points and seals it within the gel, resisting oxygen backfilling due to the high-rise chimney effect. Under national standard closed-loop conditions with a 1:50 dilution ratio, the fire extinguishing efficiency is more than 8 times that of pure water, and the reignition rate is reduced by 88%. The product is easily biodegradable, causing no secondary damage to building facades or greenery. It is stable in storage, has a simple process, and is easy to mass-produce, making it suitable for airborne fire fighting in ultra-high-rise buildings.

Description

Technical Field

[0001] This invention belongs to the technical field of water-based extinguishing agents for Class A solid fires, specifically relating to a dual-temperature-sensitive, graded-release water-based extinguishing agent suitable for airborne high-pressure long-range jet operations. Its core application is in airborne high-pressure jet extinguishing of Class A solid fires in high-rise buildings over 24m and super high-rise buildings over 100m, using drones and manned helicopters. After dilution, it is compatible with ground fire trucks, mobile firefighting robots, and other high-pressure firefighting equipment. The product's performance complies with GB4351.1-2023 "Portable Fire Extinguishers Part 1: Performance and Structural Requirements" and GB17835-2008 "Water-based Extinguishing Agents" industry standards. In open, well-ventilated mountain forest environments, inert gases are easily dissipated, limiting the synergistic flame-retardant gain. Therefore, the core optimization direction of this invention is for fires in enclosed indoor spaces of buildings. Background Technology

[0002] High-rise and super high-rise buildings have dense vertical shafts, resulting in a significant chimney effect, rapid longitudinal spread of fire, and poor fire controllability. The maximum operating height of conventional ground-based aerial ladder rescue is only 50-80m. For super high-rise buildings over 100 meters tall, it is impossible to rely on ground equipment for close-range firefighting, and they rely heavily on airborne high-pressure jet equipment for long-distance high-altitude operations.

[0003] Existing airborne fire extinguishing media have multiple inherent defects: pure water relies solely on physical heat absorption, has poor adhesion, and flows away rapidly after spraying. In high-rise fires, thermal convection continuously replenishes oxygen, resulting in extremely high rates of deep smoldering and reignition. Conventional high-viscosity fire extinguishing gels have poor fluidity at room temperature, easily clogging airborne small-diameter precision nozzles, and the high-pressure spray range is reduced by more than 30%, making them unsuitable for long-distance operations. Water-based agents directly compounded with sodium bicarbonate continuously hydrolyze and produce gas at room temperature, resulting in poor storage stability. Furthermore, the released carbon dioxide is unrestrained and easily dispersed by airflow, failing to achieve long-term oxygen isolation.

[0004] Two prior art documents are currently the closest: Document 1 (CN112972942A) discloses a temperature-sensitive water-based fire extinguishing gel that relies on a temperature-sensitive polymer phase change to achieve gelation and water retention. However, it only has a single heat absorption and cooling function, lacks a controlled gas release component, and cannot form a long-term oxygen-barrier environment in a confined space, thus failing to solve the problems of continuous oxygen refilling and high reignition rates in high-rise fires. Document 2 (CN108620035A) discloses a sodium bicarbonate microcapsule gas-generating fire extinguishing agent that relies on decomposition to release carbon dioxide to achieve oxygen barrier. However, it lacks a temperature-sensitive gel coating system, and the released carbon dioxide is easily dispersed by hot air currents at high altitudes, lacking long-term suffocation capability and failing to meet the requirements of high-pressure, low-viscosity airborne delivery.

[0005] Meanwhile, there is a long-standing recognized technical bias in this field: in the mixed system of gas-generating components and temperature-sensitive gels, the bubbles generated by gas generation will tear the continuous dense film structure of the gel, significantly reducing the adhesion and water retention time of the gel. Therefore, the industry generally uses the two types of materials as independent fire extinguishing solutions separately, and there is no technical inspiration to combine the two to solve the problem of high-rise airborne fire extinguishing.

[0006] In summary, existing technologies have not yet disclosed or revealed a dual-temperature-sensitive gradient coupling system that features "physical isolation at room temperature, sequential gelation at low temperature, fixed-point gas release at high temperature, and gas-locking gelation." Furthermore, there are no graded gas release fire extinguishing agents specifically adapted to airborne high-pressure, low-viscosity, and long-distance spraying conditions. This sub-field has a clear and long-standing unresolved technological gap. Summary of the Invention

[0007] This invention aims to overcome the core defects of existing technologies and solve the following four major technical problems: Existing fire extinguishing media cannot simultaneously achieve low viscosity at room temperature and high adhesion at fire scene. Either the viscosity is too high, which can easily clog the airborne nozzle and cause a serious reduction in range, or the adhesion is poor and the water flow is rapid, making them unsuitable for airborne high-pressure long-distance jet conditions. Without a timed, staged gas release and a closed, airtight structure, carbon dioxide easily escapes, making it unable to resist the continuous refilling of oxygen due to the high-rise chimney effect, resulting in a persistently high rate of fire reignition. The gas-producing components are prone to premature decomposition when in direct contact with water at room temperature, and have poor long-term storage stability, which cannot meet the long-term standby requirements of fire-fighting equipment; moreover, high-pressure injection and online mixing impact can easily cause the coating to break, making it impossible to achieve targeted gas release at the fire scene. Due to the industry's technical bias that "gas-producing components will destroy the continuous structure of the gel," the two types of functional materials cannot be synergistically compounded, making it difficult to simultaneously achieve integrated functions such as high-altitude low-viscosity transportation, long-term water retention in fire areas, fixed-point sealed gas release, and anti-reignition.

[0008] To address the aforementioned issues, this invention utilizes a technical solution involving PEG coating for physical isolation and precise temperature timing differences of 42°C and 60°C. This overcomes industry biases by constructing a graded gas release coupling system, fundamentally solving the technical challenges of low airborne fire suppression efficiency, high reignition rate, and poor adaptability to operating conditions in high-rise buildings.

[0009] To achieve the above objectives, the present invention provides a dual-temperature-sensitive, staged-release water-based fire extinguishing agent adapted to airborne high-pressure jets, comprising the following components by mass percentage: 3%~6% temperature-sensitive modified hydroxypropyl methylcellulose, 15%~25% PEG-coated sodium bicarbonate microcapsules, 0.3%~0.7% suspension-grade xanthan gum, 0.8%~1.2% fatty alcohol polyoxyethylene ether AEO-3, 0.1%~0.3% Kathon preservative, and the balance being deionized water.

[0010] As a preferred embodiment, the thermosensitive modified hydroxypropyl methylcellulose has a low critical dissolution temperature range of 40~44℃ and a peak phase transition point of 42℃; the viscosity of a 2% aqueous solution at room temperature (25℃) is ≤100mPa・s. At room temperature, the polymer chains are hydrophilically extended, and the system viscosity is close to that of water, allowing it to pass smoothly through onboard high-pressure pipelines and 0.5~3mm diameter precision nozzles, ensuring no significant attenuation in long-distance spraying range; when the system temperature reaches or exceeds 42℃, the polymer chains rapidly hydrophobically associate and thicken, forming a highly adhesive elastic hydrogel in situ, tightly coating the surface of combustible materials, and achieving long-term water-locking and cooling.

[0011] As a preferred embodiment, the PEG-coated sodium bicarbonate microcapsules can be commercially available or prepared using a conventional spray drying process: a core-to-wall mass ratio of 85:15, an inlet air temperature of 70°C, and an outlet air temperature of 45°C, yielding microcapsules with a particle size of 100-200 mesh and a coating integrity rate ≥90%; the shell material is polyethylene glycol with a molecular weight of 2000 and a peak melting temperature of 60°C, and the effective sodium bicarbonate content in the core material is ≥85%. At room temperature, the dense PEG shell completely physically isolates sodium bicarbonate from water, preventing premature decomposition and gas generation during room temperature storage and dilution; when the system temperature reaches or exceeds 60°C, the PEG shell melts and ruptures, allowing sodium bicarbonate to rapidly decompose upon contact with the high-temperature water, releasing inert carbon dioxide gas at specific points.

[0012] Suspension-grade xanthan gum is a low-viscosity, high-suspension type. At low addition levels, it forms a suspended network, preventing the PEG-coated sodium bicarbonate microcapsules from settling and stratifying over long-term static storage. At low concentrations, its synergistic thickening effect with thermosensitive cellulose is weak, contributing ≤20 mPa·s to the bulk viscosity of the system, and does not affect its low-viscosity transport performance at room temperature. Fatty alcohol polyoxyethylene ether (AEO-3) accumulates only at the gas-liquid interface at low addition levels, reducing the surface tension of the system and improving the spreading and wetting effect of the additive on combustible surfaces without disrupting the hydrophobic association structure of the thermosensitive polymer. Kathon preservative is stable and effective within the pH range of 4–8, ensuring the system does not mold during long-term storage and meeting the requirements for long-term fire-fighting storage.

[0013] This invention also provides a method for preparing the above-mentioned fire extinguishing agent, which operates at room temperature and pressure with low shear throughout the process to avoid damaging the microcapsule membrane structure, ensure the integrity of the dual temperature-sensitive graded coupling system, and ultimately obtain a highly stable airborne fire extinguishing agent.

[0014] This invention also provides an airborne high-pressure jet fire extinguishing system comprising the aforementioned fire extinguishing adjuvant. Precise agent proportioning is achieved through a Venturi online dilution structure. Water is pressurized by a high-pressure pump and then drawn into the adjuvant under negative pressure, ensuring the adjuvant does not undergo high shear within the pump and maximizing the integrity of the microcapsule coating. This system is suitable for high-altitude, long-distance operations. This technical solution can be extended to customized microcapsule preparation processes, airborne online dilution devices, and specialized formulations for different scenarios, possessing comprehensive potential for technological expansion.

[0015] Compared with existing technologies, this invention has outstanding substantive features and significant technological advancements, breaking through inherent technological biases in the industry and producing unexpected synergistic technological effects. Specific advantages are as follows: Dual-temperature-sensitive time-sequential graded response, adaptable to airborne operations under all conditions. This invention constructs a two-level gradient temperature-sensitive triggering mechanism at 42℃ and 60℃. At room temperature, the system has low viscosity and fluidity close to that of clear water, making it suitable for high-speed injection from airborne high-pressure small-diameter nozzles, with no clogging and no significant range attenuation. Actual testing showed that continuous injection for 30 minutes at 5MPa pressure resulted in no clogging, with a nozzle outlet liquid temperature of 39.2℃, below the phase change threshold, providing sufficient safety redundancy. The microcapsule breakage rate during the Venturi online mixing process was <0.5%, maintaining full functionality. During droplet flight, the temperature rise was <3℃ and the vaporization loss rate was <5%, maintaining stable flight at low viscosity, triggering phase change only upon contact with high-temperature combustibles.

[0016] Under high temperatures in a fire, the agent droplets sequentially complete gelation and gas release along the contact heating path. Even if the overall temperature of the fire exceeds 60°C, the graded sequence can still be guaranteed, and synchronous failure will not be triggered, completely solving the problem of poor adaptability of traditional media under working conditions. Relying on the physical isolation structure of the PEG coating, the core material is completely isolated from the aqueous phase at room temperature. After 12 months of sealed storage at room temperature, the system has a uniform appearance, a microcapsule sedimentation rate of ≤5%, and a fire extinguishing efficiency retention rate of ≥90%. After verification by 14 days of hot storage at 54°C and 30 days of cold storage at -10°C, the sample has a uniform appearance, no microcapsule breakage, and a fire extinguishing efficiency retention rate of ≥92% after dilution, which meets the storage and transportation standards for fire protection products and meets the long-term standby requirements of fire protection equipment.

[0017] The aforementioned characteristics precisely match the core requirements of airborne firefighting scenarios: First, drones and helicopters have limited payload and liquid storage space. This invention uses a concentrated formula and employs an online venturi dilution method after pumping, significantly reducing the amount of raw liquid carried and alleviating the platform's load burden. Second, airborne pipelines and precision nozzles have small diameters and high operating pressures. The low viscosity characteristics of this invention at room temperature ensure smooth pipeline flow without blockages and no significant attenuation of the spray range, solving the pain point that conventional high-viscosity gels cannot be adapted to high-altitude, long-distance spraying. Third, the droplets are not affected by ambient temperature during high-altitude flight and will not prematurely change phase and fail. Fourth, it rapidly thickens and adheres to the surface of combustible materials after reaching them, avoiding agent waste caused by high-altitude airflow scouring and gravity flow, truly achieving a "water-like delivery and adhesive-like adhesion" effect specifically for airborne applications.

[0018] Breaking through industry technical biases, this invention constructs a triple-coupled fire extinguishing system. It overcomes the industry's technical prejudice that "gas-producing components destroy the gel film structure," achieving a triple synergistic effect of "first gelling and coating, then targeted gas release, and finally gel sealing and gas locking" through PEG coating at room temperature physical isolation and gradient temperature difference time-series control. The three-dimensional gel network possesses elastic deformation capabilities, accommodating the volume expansion from gas release and moisture vaporization without instantaneous rupture, and can maintain continuous oxygen isolation for ≥15 minutes. Carbon dioxide is confined to the core area of ​​the fire source by the gel film, effectively resisting the dispersion of airflow due to the chimney effect, achieving long-lasting oxygen isolation and deep flame suppression. Under the GB 4351.1-2023 standard Class A fire sealing test conditions and an additive dilution of 1:50, the fire extinguishing efficiency coefficient of this invention is 9.2, more than 8 times that of pure water; the anti-reignition rate is 7.2%, more than 88% lower than that of pure water, representing an order-of-magnitude improvement in performance.

[0019] The aforementioned triple synergistic effect cannot be achieved by simply combining two materials: when the overall temperature threshold is low (Comparative Example 4), the PEG coating physical isolation is removed (Comparative Example 5), and gelation and gas release are triggered simultaneously (Comparative Example 6), the system exhibits problems such as gel structure breakage, decreased adhesion, reduced fire extinguishing efficiency, and a significant increase in reignition rate, resulting in significant performance degradation. This fully demonstrates that the temperature gradient design and physical isolation structure of this invention are key innovations that overcome industry technical biases and achieve unexpected technical effects, and are not conventional choices for those skilled in the art.

[0020] Clean, environmentally friendly, and residue-free, suitable for all scenarios of urban building fire suppression. The finished additive has a pH value of 6-8, is a near-neutral system, free of strong acids, strong alkalis, heavy metals, and persistent organic pollutants, and its main components are all naturally biodegradable. According to the GB / T1763 corrosion test method, after soaking marble, 6061 aluminum alloy, and tempered glass for 72 hours, there was no change in appearance and the weight loss rate was <0.01%. After extinguishing the fire, it only forms an ultra-thin water-soluble transparent film on the surface of combustible materials, with no dust or corrosion residue, and can be completely rinsed away with water. It will not damage indoor furniture and appliances, exterior wall stone, glass, or metal components. When the agent is diluted at a high ratio of 1:50 to 1:100 before spraying, the waste liquid flowing into the soil will not cause plant burns or soil compaction, and there is no long-term persistent secondary pollution. It can be safely used in various built-up areas such as residential buildings and office buildings.

[0021] The process is simple, the raw materials are universal, and it has strong industrial mass production potential. The entire preparation process is carried out at room temperature and pressure, without the need for special equipment or demanding processes. The raw materials are all common industrial bulk raw materials, which are compatible with existing water-based fire extinguishing agent production lines. The production cost is controllable, and it can be quickly scaled up for production, making it highly valuable for promotion and application.

[0022] This invention designs a dual-temperature-sensitive time-series coupling system for enclosed fire scenes in ultra-high-rise buildings, which effectively improves the fire extinguishing efficiency of high-altitude fires and reduces the probability of reignition. It has important practical value and social significance for improving the emergency rescue system for fire safety in urban high-rise buildings and enhancing high-altitude fire rescue capabilities.

[0023] The two-stage temperature gradient design of the 42℃ gelation threshold and 60℃ gas release threshold in this invention is not a conventional parameter selection in the field. Instead, it is an optimal solution jointly constrained by airborne operating conditions, material property matching, and synergistic effects. It was obtained through screening by multiple sets of parallel gradient experiments. Its non-obviousness is reflected in the following aspects: ① The gelation threshold of 42℃ is much higher than the highest storage and transportation temperature in extreme environments worldwide (about 38℃), ensuring the stability of the system and preventing thickening throughout the entire process of room temperature storage, transportation, and standby. At the same time, it is significantly lower than the boiling point of water. After the droplets come into contact with high-temperature flammable materials, they can trigger a phase change through contact heat transfer in milliseconds, completing film formation and adhesion before a large amount of water vaporizes and is lost. This precisely balances storage stability and fire response speed. If the threshold is too low, the storage and transportation will easily thicken and clog the pipes in advance. If the threshold is too high, the gelation will be delayed and the water will be lost quickly. Neither of these is suitable for long-distance airborne operations. ② Gas release threshold of 60℃: Matching the standard melting temperature of PEG2000, the raw materials are readily available for industrial production and have strong batch consistency. More importantly, it maintains a reasonable temperature gradient of 18℃ with the gelation threshold, ensuring that the three-dimensional cross-linked network of the gel is fully formed first, followed by the melting and gas release of the microcapsule shell. This fundamentally avoids the common industry problem of bubbles breaking through the immature gel membrane, which is a necessary prerequisite for achieving the synergistic effect of "gel sealing and gas locking". ③ This gradient combination cannot be obtained through conventional reasoning: It is generally believed in the art that the gas-generating component will destroy the gel structure, so there is no motivation to combine the two, let alone to achieve time-sequential grading through precise temperature differences; any combination deviating from the temperature range of this invention cannot achieve a stable triple synergistic fire extinguishing effect.

[0024] The core innovation of this invention lies in the graded gas release and water locking mechanism coupled with temperature difference and time sequence. Relying on the precise temperature threshold difference between the two stages, it overcomes the defects of existing single materials and industry technical biases, and achieves a synergistic qualitative change effect.

[0025] First-order temperature-sensitive phase change water-locking (≥42℃): At room temperature (25℃), the temperature-sensitive modified hydroxypropyl methylcellulose molecular chains hydrophilically expand, and the system viscosity is close to that of pure water, meeting the flowability requirements of long-distance, high-pressure airborne injection. After the agent is sprayed and comes into contact with the high-temperature fire, the droplets impact the surface of the combustible material, rapidly heating up through contact heat transfer, reaching the 42℃ phase change threshold in milliseconds. The polymer rapidly undergoes hydrophobic cross-linking and association, and the system viscosity increases instantaneously, forming a dense and continuous elastic gel coating layer on the surface of the combustible material. This locks in moisture, prevents flow and loss, and continuously absorbs heat for cooling, solving the problems of short retention time and unsustainable cooling in pure water media. The short flight time of the droplets in the air and the slow heat transfer from the air prevent premature phase change triggering.

[0026] In the second-order temperature-sensitive, point-release oxygen-isolation system (≥60℃), at room temperature, the sodium bicarbonate core material is completely encapsulated by a dense PEG shell, completely isolating it from water without hydrolysis, gas generation, or failure. After gelation, the internal temperature of the gel layer continues to rise to 60℃, causing the PEG coating to melt and rupture. The sodium bicarbonate decomposes rapidly upon contact with hot water, releasing over 80% of effective carbon dioxide within 10 seconds at 60℃. At this point, the outer gel film is fully formed, creating a sealed microenvironment. The three-dimensional gel network has elastic deformation capabilities, accommodating gas expansion and locking inert gases at the combustion interface. This significantly reduces local oxygen concentration, blocks the combustion chain reaction, and resists oxygen backfilling caused by high-rise thermal convection and the chimney effect, thus inhibiting smoldering and reignition at the source.

[0027] The PEG shell is a tough polymer material with high mechanical strength in the glassy state at room temperature, which can withstand the instantaneous impact shear of the airborne high-pressure nozzle and the low shear force of the Venturi online mixing. After 10 cycles of injection at 5MPa pressure, the microcapsule breakage rate is <2%, and it will not prematurely release gas and fail, ensuring the function of targeted release at the fire scene.

[0028] A common technical bias exists in this field: when gas-generating components are mixed with temperature-sensitive gels, the bubbles disrupt the continuous, dense structure of the gel, thus reducing its adhesion and water-locking effect. Therefore, existing technologies use these two components separately as independent fire extinguishing solutions. This invention achieves physical isolation between the two phases at room temperature through PEG coating and uses a gradient temperature difference of 42°C and 60°C to ensure that the gel forms first and the gas is released later. This preserves the complete coating structure of the gel while achieving airtight confinement of the gas, fundamentally overcoming the aforementioned technical bias.

[0029] Both functional materials have fatal flaws when used alone: ​​the temperature-sensitive gel alone lacks oxygen-isolating and gas-releasing capabilities, failing to address the problem of reignition due to oxygen refilling at high altitudes; the PEG-coated microcapsules alone lack a sealed enclosure for gas generation, resulting in rapid gas dissipation and no long-lasting flame-retardant effect. In a synchronously triggered mixed system, bubbles can break through the unformed gel membrane, leading to a significant deterioration in performance. Only through the precise formulation ratios, gradient temperature-sensitive parameters, and matching preparation processes defined in this invention can an unexpected triple synergistic fire extinguishing effect be achieved; any missing or deviated key components, temperature ranges, or process parameters will result in the loss of the core airtight and gas-locking fire extinguishing performance. This is not a simple raw material compounding in the field and represents a substantial innovation.

[0030] All performance tests were conducted strictly in accordance with the standard test methods for Class A solid fires in GB 4351.1-2023 "Portable Fire Extinguishers Part 1: Performance and Structural Requirements", simulating the windless convection conditions of a closed indoor fire in a high-rise building. High and low temperature storage tests were performed in accordance with the storage and transportation performance requirements of GB17835-2008 "Water-based Fire Extinguishing Agents".

[0031] Standardized test conditions: Standard pine wood stacks, individual pieces measuring 2cm×4cm×50cm, stacked in 8 layers, moisture content 12%, ignited with ethanol; spray pressure 5MPa, spray distance 10m, nozzle diameter 1.5mm, ambient temperature 25℃, test completed in a closed test space. Reignition resistance observation period is 30min.

[0032] Two quantitative evaluation indicators are set: (1) Fire extinguishing efficiency coefficient E: E = the volume of pure water required to extinguish the same standard fire source ÷ the volume of diluted agent required to extinguish the same standard fire source. The higher the value, the stronger the fire extinguishing efficiency; (2) Reignition resistance rate Rr: Rr = the area of ​​reignition zone within a 30-minute standing period ÷ the total area completely covered by the extinguishing medium × 100%. The lower the value, the better the reignition resistance performance. Attached Figure Description

[0033] Figure 1 This is a schematic diagram comparing the fire extinguishing effect of the diluted fire extinguishing agent of the present invention with that of pure water.

[0034] Figure 2 This is a schematic diagram of the dual-temperature-sensitive staged gas release coupling mechanism of the present invention.

[0035] Figure 1 The left side of the image shows the pure water condition: after being sprayed, the pure water flows away quickly and cannot adhere, the flame continues to burn, and there is no oxygen-blocking or flame-suppressing effect; the right side shows the additive condition: the agent forms a gel coating on the surface of the combustible material and seals carbon dioxide inside, achieving a synergistic fire extinguishing effect of cooling and oxygen isolation.

[0036] Figure 2 This is a schematic diagram of the "dual-temperature-sensitive graded gas release coupling mechanism," which sequentially illustrates three time-series states: room temperature low viscosity transport state, 42°C gelation and encapsulation state, and 60°C gas release and gas-locking state. The evolutionary logic of this diagram from left to right—"molecular expansion and dispersion → cross-linking to form a network → gas bubbles encapsulated within the network"—perfectly matches the core mechanism of the invention: "room temperature isolation → first-stage gelation → second-stage gas release and gas-locking."

[0037] Explanation of reference numerals in the attached figures: 1. Carbon dioxide bubbles: Inert gas released by the microcapsules after being triggered at 60°C, which is sealed and locked in the combustion interface by the gel layer; 2. Elastic hydrogel coating layer: A continuous gel film formed by phase change triggered at 42℃, which tightly coats the surface of flammable materials to lock in water and cool down; 3. Combustible wood stack: Standard pine wood test stack, simulating a Class A solid fire combustion carrier; 4. This is the pure water fire extinguishing mode on the left. 5. The fire extinguishing condition of the additive of the present invention on the right; 6. Room temperature isolation; 7. First-stage gelation; 8. Second-order gas release and gas lock; 9. Temperature-sensitive polymer chains: Modified hydroxypropyl methylcellulose molecules that hydrophilically expand at room temperature, corresponding to the linear dispersion structure in the left figure, reflecting the system's low viscosity at room temperature; 10. Three-dimensional gel cross-linking network: At temperatures ≥42℃, the continuous elastic gel skeleton formed by the hydrophobic association of polymers corresponds to the network structure in the middle diagram, achieving water-locking coating on the surface of combustible materials; 11. Carbon dioxide bubbles: Inert gas released by the decomposition of sodium bicarbonate after the PEG coating melts at temperatures ≥60℃, corresponding to the internal circular structure in the right figure; 12. Elastic gel sealing layer: The continuous outer membrane of the gel after molding seals and locks carbon dioxide at the combustion interface, preventing the escape of airflow. Detailed Implementation

[0039] The following embodiments are used to illustrate the present invention and do not limit the scope of protection of the present invention. Conventional adjustments to raw material parameters and process parameters made by those skilled in the art without departing from the core concept of the present invention are all within the scope of protection of the present invention.

[0040] All raw materials used in this invention are commercially available industrial grade: the thermosensitive modified hydroxypropyl methylcellulose (HPMC) with a peak LCST of 42℃ and a viscosity of 90 mPa·s in a 2% aqueous solution at 25℃; the PEG-coated sodium bicarbonate microcapsules were coated with PEG2000 by spray drying, with a particle size of 100-200 mesh and a sodium bicarbonate content of 88% in the core material; the suspension-grade xanthan gum, AEO-3, and Kathon preservative were all commercially available industrial grade. All tests were conducted in a simulated high-rise indoor closed fire environment.

[0041] Component mass percentage: 5% thermosensitive modified HPMC, 20% PEG-coated sodium bicarbonate microcapsules, 0.5% suspension-grade xanthan gum, 1% AEO-3, 0.2% Kathon preservative, and 73.3% deionized water.

[0042] Preparation steps: Control the water temperature at 30℃, add deionized water to the stirred tank, slowly add temperature-sensitive modified HPMC while stirring at 1000r / min, stir for 18min until the system is transparent and free of clumps; reduce the speed to 400r / min, add xanthan gum, AEO-3 and Kathon in sequence, and stir until completely dispersed; reduce the speed to 100r / min, slowly add microcapsules, stir at low speed for 10min; let stand for 30min to degas, and obtain the finished product.

[0043] Test results: The finished product viscosity at 25℃ is 85 mPa·s; the sedimentation rate after 30 days of standing is 2.1%; the fire extinguishing efficiency retention rate after 12 months of sealed storage at room temperature is 91.3%; after dilution with water at a ratio of 1:50, the fire extinguishing efficiency coefficient E=9.2 and the reignition rate Rr=7.2%; after 14 days of hot storage at 54℃ and 30 days of cold storage at -10℃, the fire extinguishing efficiency retention rate is 94.1%, demonstrating excellent storage stability; it is compatible with nozzles of 0.5~3mm diameter, and the spray distance at 5MPa pressure is 22m without clogging or significant range attenuation; after 10 cycles of spraying at 5MPa pressure, the microcapsule breakage rate is 1.7%, and the fire extinguishing efficiency retention rate is 97.3%; after online mixing with Venturi, the microcapsule breakage rate is 0.3%, and the function remains intact; the original solution has a pH of 7.2, and after soaking marble, glass, and aluminum alloy samples for 72 hours, there is no corrosion, discoloration, or blooming; after continuous watering of herbaceous plants with the 1:50 diluted solution for 7 days, there is no wilting or burning.

[0044] Component mass percentage: thermosensitive modified HPMC 3%, PEG-coated sodium bicarbonate microcapsules 15%, xanthan gum 0.3%, AEO-3 0.8%, Kathon preservative 0.1%, deionized water 80.8%. The preparation process is completely consistent with Example 1.

[0045] Test results: Excellent fluid flowability, high-pressure jet range attenuation <2%; after 1:100 dilution, the fire extinguishing efficiency coefficient E=6.5, Rr=9.1%, low agent consumption, suitable for long-distance extinguishing of small initial fires in ultra-high-rise buildings, and extending the operating endurance of airborne equipment.

[0046] Component mass percentage: thermosensitive modified HPMC 6%, PEG-coated sodium bicarbonate microcapsules 25%, xanthan gum 0.7%, AEO-3 1.2%, Kathon preservative 0.3%, deionized water 66.8%. The preparation process is completely consistent with Example 1.

[0047] Test results: It has the best gel film-forming properties and gas-locking flame retardancy; after dilution at 1:60, the fire extinguishing efficiency E=10.3, the reignition rate Rr=6.5%, and the deep flame suppression effect is outstanding, making it suitable for thick layers of combustibles and deep smoldering fires.

[0048] Under the same working conditions, the fire extinguishing efficiency coefficient of pure water is E=1.0 and the reignition rate is Rr=63.5%; the water flows away rapidly and has no oxygen-blocking effect, so the risk of reignition in high-rise fires is extremely high.

[0049] Under the same working conditions, the fire extinguishing efficiency coefficient of conventional foam fire extinguishing agent is E=1.8 and the reignition rate is Rr=35.2%; it only isolates oxygen on the surface and has no fixed-point gas release and long-term water-locking ability, and cannot resist the oxygen supply of the chimney effect.

[0050] Airborne spray compatibility test: Conventional gel has high viscosity at room temperature, and the range of high-pressure spray decreases by more than 30%, making it unsuitable for long-distance airborne operations; the fire extinguishing efficiency coefficient E=4.5, there is no staged gas release mechanism, and the anti-reignition rate Rr=22.7%.

[0051] Microcapsules with temperature-sensitive HPMC (peak LCST 32℃) and PEG (melting temperature 50℃) were used, and the rest of the formulation and process were the same as in Example 1.

[0052] Test results: Slight thickening occurred after 7 days of storage at room temperature, the high-pressure jet range decreased by 18%, the fire extinguishing efficiency coefficient E=5.8, and the reignition resistance rate Rr=18.3%, indicating a significant decline in overall performance. After deviating from the temperature threshold, the time difference between gelation and gas release disappeared, making it impossible to form a stable airtight structure.

[0053] Ordinary sodium bicarbonate powder was used instead of PEG-coated microcapsules, and the rest of the formulation and process were the same as in Example 1.

[0054] Test results: Gas production and swelling occurred after 3 days of storage at room temperature, and the product became completely ineffective after 15 days; the gas dissipated rapidly during fire extinguishing, with a reignition rate of Rr=29.6%, and no long-term oxygen barrier effect. Without the physical isolation structure of PEG coating, not only was storage stability lost, but the synergistic effect of time-sequential gelation and gas locking could not be achieved.

[0055] Microcapsules with a peak LCST of 50°C for temperature-sensitive HPMC and a melting temperature of 50°C for PEG were used. The gelation and gas release were triggered simultaneously, and the rest of the formulation and process were the same as in Example 1.

[0056] Test results: Bubbles were generated simultaneously and broke through the incompletely formed gel film, resulting in gel structure breakage and decreased adhesion; the fire extinguishing efficiency coefficient E=6.1 and the reignition resistance rate Rr=21.4%, significantly inferior to the staged triggering system. This demonstrates that the gradient temperature difference between 42℃ and 60℃ is a necessary condition for achieving the synergistic effect of gel-airlocking, and is not a conventional parameter adjustment in this field.

[0057] Multiple standardized control tests show that the present invention adopts a dual-temperature-sensitive graded gas release coupling system, which breaks through industry technical biases. Under the premise of meeting the requirements of airborne high-pressure jetting, it significantly improves the fire extinguishing efficiency and anti-reignition performance of closed fire sites in high-rise buildings. Compared with the existing technology, it has outstanding substantive features and significant technical progress. The technical solution is complete and reproducible and has industrial applicability.

Claims

1. A dual-temperature-sensitive, staged-release water-based fire extinguishing agent adapted to airborne high-pressure jets, characterized in that, With thermosensitive modified hydroxypropyl methylcellulose and PEG-coated sodium bicarbonate microcapsules as core functional components, the system relies on the PEG shell to achieve physical isolation between the two phases at room temperature, constructing a time-series coupling system with two-stage gradient thermosensitive triggering at 42℃ and 60℃ peak values. This results in a graded gas release coupling structure where combustibles are preferentially gelled in situ at 42℃ and released at a delayed point at 60℃, with carbon dioxide sealed by the pre-gel process. This system is suitable for high-pressure long-distance jetting conditions of 3~8MPa in high-rise buildings. By mass percentage, it consists of the following components: thermosensitive modified hydroxypropyl methylcellulose 3%~6%, PEG-coated sodium bicarbonate microcapsules 15%~25%, suspension-grade xanthan gum 0.3%~0.7%, fatty alcohol polyoxyethylene ether AEO-3 0.8%~1.2%, Kathon preservative 0.1%~0.3%, and the balance being deionized water.

2. The dual-temperature-sensitive, staged-release water-based fire extinguishing agent according to claim 1, characterized in that, The temperature-sensitive modified hydroxypropyl methylcellulose has a low critical dissolution temperature range of 40~44℃ and a peak phase transition point of 42℃; at room temperature of 25℃, its 2% aqueous solution viscosity is ≤100 mPa・s; when the system temperature reaches or exceeds 42℃, the polymer undergoes a hydrophobic association phase transition to form a continuous elastic hydrogel film.

3. The dual-temperature-sensitive, staged-release water-based fire extinguishing agent according to claim 1, characterized in that, The PEG-coated sodium bicarbonate microcapsules have a particle size of 100-200 mesh, the peak melting temperature of the PEG coating is 60℃, and the effective content of sodium bicarbonate in the core material is ≥85%. At room temperature, the PEG shell isolates the aqueous phase to prevent premature decomposition and gas production of the core material. When the system temperature reaches or exceeds 60℃, the shell melts and the core material releases carbon dioxide at specific points.

4. The dual-temperature-sensitive, staged-release water-based fire extinguishing agent according to claim 1, characterized in that, The viscosity of the finished additive at 25℃ is 50~200 mPa・s. After standing in a sealed container at room temperature for 30 days, the microcapsule sedimentation rate is ≤3%, with no stratification or premature gas production and swelling.

5. The dual-temperature-sensitive, staged-release water-based fire extinguishing agent according to claim 1, characterized in that, The preferred formulation by weight percentage is: 5% thermosensitive modified hydroxypropyl methylcellulose, 20% PEG-coated sodium bicarbonate microcapsules, 0.5% suspension-grade xanthan gum, 1% fatty alcohol polyoxyethylene ether AEO-3, 0.2% Kathon preservative, and 73.3% deionized water.

6. The preparation method of the dual-temperature-sensitive, staged-release water-based fire extinguishing agent according to any one of claims 1 to 5, characterized in that, The steps include: (1) Take 25~35℃ room temperature deionized water of the formula and place it in a stirring tank. Turn on high speed stirring at 800~1200r / min to form a stable vortex. Slowly and evenly add temperature-sensitive modified hydroxypropyl methylcellulose powder and continue stirring for 15~20min until the system is completely transparent, without clumps or solid particles, and obtain a homogeneous polymer base liquid. The water temperature is controlled at ≤35℃ throughout the process. (2) Reduce the stirring speed to medium speed 300~500r / min and add suspension-grade xanthan gum, fatty alcohol polyoxyethylene ether AEO-3, and Kathon preservative in sequence. After each component is completely dispersed and homogenized, add the next component. (3) Reduce the stirring speed to low speed 80~150r / min again and slowly add PEG-coated sodium bicarbonate microcapsules. Continue stirring at low speed for 8~12min until the microcapsules are uniformly suspended and dispersed. High-speed shearing and stirring are prohibited throughout the process to avoid damage to the capsule shell and premature gas release and failure; (4) Let stand for 20~40 minutes to remove microbubbles on the surface of the system and obtain the finished fire extinguishing agent.

7. The method of using the dual-temperature-sensitive, graded-release, water-based fire extinguishing agent according to any one of claims 1 to 5, characterized in that, Fire extinguishing agent is diluted and mixed with water at a volume ratio of 1:(50~100); a 1:50 dilution ratio is suitable for moderate to severe, deep smoldering fires, and a 1:70~1:100 dilution ratio is suitable for initial light fires; the diluted solution is suitable for high-pressure jet equipment with a working pressure of 3~8MPa and a long distance of 10~30m for spraying operations.

8. The method of use according to claim 7, characterized in that, The high-pressure jet equipment is a fire-fighting drone or a manned fire-fighting helicopter, with a jet pressure of 5~8MPa and an operating height covering high-rise and super high-rise buildings of 24~300m, used to extinguish Class A solid fires indoors.

9. An airborne high-pressure jet fire extinguishing system, characterized in that, The system includes an airborne auxiliary agent storage tank, a clean water storage tank, a high-pressure jet pump, a Venturi online mixing device, a precision nozzle, and the dual-temperature-sensitive, graded-release water-based fire extinguishing agent as described in any one of claims 1 to 5. Clean water is pressurized by the high-pressure jet pump and then enters the Venturi online mixing device. The auxiliary agent is drawn in under negative pressure and diluted online at a volume ratio of 1:(50~100). The mixture is then sprayed out through the precision nozzle. The system's spraying working pressure is 3~8MPa, the spraying distance is ≥15m, and the diameter of the precision nozzle is 0.5~3mm.

Images