Fire extinguishing cases, fire extinguishing equipment

Abstract

This provides a fire extinguishing case that is more suitable for chemical batteries and capacitors than conventional ones. [Solution] The fire extinguishing case is a fire extinguishing case having a mechanism that senses heat and releases a fire extinguishing agent, comprising a hollow part in which an object to be extinguished is placed, a wall part surrounding the hollow part, and a fire extinguishing section that senses heat and releases a fire extinguishing agent, characterized in that the fire extinguishing agent contains a silicate aqueous solution or a phosphate aqueous solution that, upon contact with the object to be extinguished, generates a solid silicate compound or a solid phosphate compound on the surface of the object to be extinguished to extinguish the fire.

Description

[Technical Field]

[0001] The present invention relates to fire prevention and fire extinguishing, and more specifically to a fire extinguishing case and fire extinguishing equipment for extinguishing or cooling fires and suppressing the spread of fire in the event of an unexpected fire or overheating. [Background technology]

[0002] Chemical batteries are one example of objects targeted for fire prevention and extinguishing. Chemical batteries are devices that generate electrical energy using chemical reactions, and their range of applications is wide. Chemical batteries are broadly classified into three types: primary batteries, secondary batteries, and fuel cells. Primary batteries are disposable batteries in which the chemical reaction proceeds in one direction and cannot be recharged after discharge. Secondary batteries can be charged and discharged and are also called storage batteries or rechargeable batteries. Fuel cells are a type of battery that is supplied with gaseous or liquid fuel and obtains electrical energy from chemical reactions that occur within the battery.

[0003] In particular, recent technological advancements in capacitors and rechargeable batteries have been remarkable. Lithium-ion rechargeable batteries, in particular, are used in a wide range of devices such as smartphones, laptops, electric vehicles, backup power supplies, renewable energy storage, and load leveling due to their high energy density, and are contributing to the introduction of energy-saving and new energy technologies.

[0004] Conventional rechargeable batteries have mainly consisted of batteries containing water as an electrolyte, such as lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-iron batteries. However, in recent years, the use of primary and secondary batteries using non-aqueous electrolytes has been increasing due to their characteristics of miniaturization, weight reduction, and the realization of high voltage.

[0005] These non-aqueous electrolyte secondary batteries consist of a positive electrode, a negative electrode, an electrolyte, and a battery case (outer casing). Furthermore, if the electrolyte is fluid, a separator is interposed between the positive and negative electrodes.

[0006] Electrodes, such as positive and negative electrodes, are primarily composed of an active material, a conductive additive, a binder, and a current collector. Generally, a positive electrode is manufactured by mixing a positive electrode active material, a carbon-based conductive additive, and a resin-based binder in an organic solvent such as N-methyl-2-pyrrolidone (NMP) to form a slurry, coating this slurry onto aluminum foil (which serves as the current collector), drying it, and then adjusting the pressure using a roll press or similar device.

[0007] The manufacturing process for the negative electrode is similar: the negative electrode active material and a resin-based binder are mixed in a dispersion medium or solvent such as water or NMP to form a slurry, which is then coated onto copper (Cu) foil, which serves as the current collector, and dried to form the negative electrode composite layer. Finally, the pressure is adjusted using a roll press or similar device. When materials with a high equilibrium potential (noble), such as lithium titanate, niobium titanium oxide, or sulfides, are used as the negative electrode active material, or when sodium ions are the carrier, aluminum (Al) foil is mainly used as the current collector.

[0008] The battery case (outer casing) is a container that houses the electrodes and electrolyte, and consists of, for example, a positive electrode can or a negative electrode can and a gasket. In the charging and discharging process, in the case of a lithium-ion battery (hereinafter referred to as a lithium-ion battery), aluminum (Al) is used for the positive electrode can and nickel (Ni) is used for the negative electrode can. On the other hand, in the case of a sodium-ion battery (hereinafter referred to as a sodium-ion battery), aluminum is generally used for both the positive and negative electrode cans. An insulating resin is used for the gasket to maintain insulation inside the battery.

[0009] During the charging process of a non-aqueous electrolyte secondary battery, carriers responsible for electrical conduction (e.g., lithium ions in lithium-ion batteries, sodium ions in sodium-ion batteries) are released from the positive electrode and inserted into the negative electrode via the electrolyte, or deposited as metal on the negative electrode current collector. During the discharging process, this reaction is reversed, and the carriers inserted into the negative electrode, or the deposited metal, are ionized to become carriers and re-inserted into the positive electrode via the electrolyte.

[0010] Incidentally, in primary batteries, secondary batteries, and capacitors, there is a problem that the risk of thermal runaway increases as the electrical capacity increases. Furthermore, it is known that in any type of chemical battery or capacitor, the tendency to generate heat increases as the current used increases. In particular, thermal runaway in chemical batteries is a phenomenon in which the temperature of the battery rises to an uncontrollable level due to internal or external factors, and it has been pointed out that this can lead to fire or explosion.

[0011] For example, in a lithium-ion secondary battery consisting of a ternary (Li(Ni-Co-Mn)O2) positive electrode, a graphite negative electrode, an organic electrolyte made of ethylene carbonate (EC) and dimethyl carbonate (DMC) in which lithium hexafluoride phosphate (LiPF6) is dissolved, and a polyolefin microporous membrane separator, the negative electrode and electrolyte react when the battery temperature exceeds 80°C, and the separator melts down and an internal short circuit occurs when the temperature exceeds 140°C. Above 200°C, the positive electrode active material decomposes thermally, releasing oxygen, which then burns violently with the vaporized electrolyte. Furthermore, above 660°C, the Al in the positive electrode current collector melts, and in the final stages of thermal runaway, a thermite reaction occurs between the positive electrode active material and Al, which can reach temperatures of over 1000°C.

[0012] In this way, thermal runaway is a phenomenon in which a series of chemical reactions occurring inside a battery accelerate in a chain reaction, causing the temperature to rise rapidly. During this process, the battery overheats abnormally, and in the worst case, it can lead to ignition or explosion.

[0013] Whether thermal runaway ends with abnormal heat generation or progresses to smoke and fire depends on the battery design, materials used, battery condition, and environmental conditions. For example, if appropriate cooling measures are taken in the initial stages, or if the battery is designed with highly heat-resistant materials, the situation may be contained before ignition occurs. On the other hand, if there is a severe internal short circuit or if external conditions deteriorate, the risk of ignition increases.

[0014] To address this issue, commercially available lithium-ion batteries incorporate PTC (Positive Temperature Coefficient) elements, CID (Current Interrupt Device), and safety valves (pressure release valves). These safety devices activate and cut off the current when the temperature, current, or internal pressure exceeds certain standards.

[0015] Unfortunately, even with these safety measures in place, the number of battery-related fires has not decreased. Therefore, establishing safe transportation and storage methods is urgently needed to guarantee the safe operation of batteries.

[0016] Therefore, a readily conceivable method is to cover the battery with flame-retardant materials that have excellent heat resistance and fire resistance, such as aramid, polyimide, polyphenylene ether, and poly-p-phenylene benzbisoxazole. Compared to general flammable materials, these materials are expected to suppress the spread of fire (fire spreading).

[0017] On the other hand, it is also important to develop firefighting technologies that can quickly and effectively deal with thermal runaway in batteries and capacitors.

[0018] For example, Patent Document 1 describes a waste bag for enclosing lithium batteries, which has a fire-extinguishing gel layer and a heat-resistant explosion-proof layer arranged in order from the inside to the outside. The fire-extinguishing gel layer includes a bladder made of plastic film, and the bladder is filled with fire-extinguishing gel containing a gas propellant. When the ambient temperature exceeds the burst temperature of the gel release point, the gel flows out of the gel bag from the release point, and after the fire-extinguishing gel comes into contact with the lithium battery or equipment containing a lithium battery, it lowers the temperature of the battery, suppresses thermal runaway, and reduces the risk of smoke and fire.

[0019] Patent Document 2 shows that a thermosensitive inorganic composition prepared by mixing an aqueous solution of sodium silicate (sodium silicate) with aluminum silicate and a metal carbonate such as strontium carbonate forms a porous body upon heating, and its porosity is maintained or improved even at high temperatures upon further heating.

Prior Art Documents

Patent Documents

[0020]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0021] However, in the technology of Patent Document 1, suppression of thermal runaway in high-capacity chemical batteries and battery packs may be insufficient. In particular, in the case of chemical batteries or capacitors using metal lithium, lithium alloys, sodium-storing carbon, potassium-storing carbon, etc. as the negative electrode, the extinguishing ability cannot be sufficiently obtained, and it is difficult to suppress the spread of fire. Therefore, even in such battery systems, the realization of effective fire extinguishing equipment is desired. Also, the technology of Patent Document 2 does not assume chemical batteries or capacitors as the objects to be extinguished.

[0022] Also, when the battery undergoes thermal runaway, even if the thermite reaction is not reached, the temperature may exceed 800°C. Also, depending on the type of battery, toxic gases such as organic gases, hydrogen fluoride (HF), carbon monoxide (CO), and hydrogen sulfide (H2S) may be generated during thermal runaway.

[0023] Therefore, simply improving fire resistance technology has limitations in preventing damage caused by thermal runaway in batteries and capacitors. This is because while fire-resistant technology is effective in reducing the risk of direct fires and explosions caused by thermal runaway in batteries and capacitors, it does not solve the problems of fire suppression or the harmful gases generated during thermal runaway.

[0024] Here, three conditions (the three elements of combustion) are necessary for something to burn: combustible material, oxygen, and heat. If even one of these is removed, combustion can be stopped. Based on this principle, fire extinguishing methods are broadly classified into three types: removal extinguishing (combustible material), cooling extinguishing (heat), and suffocation extinguishing (oxygen).

[0025] In ordinary fires, cooling methods using water or extinguishing liquids, such as water cannons or fire extinguishers, are effective. However, in the case of chemical batteries and capacitors, combustion and chemical reactions occur at high temperatures, and materials with a specific gravity lighter than water are often used in batteries, so appropriate fire extinguishing methods are required.

[0026] For example, in the case of a lithium-ion battery fire, spraying water on it is not only largely ineffective in extinguishing the fire, but the water and active material react violently, generating a large amount of hydrogen gas and potentially worsening the fire.

[0027] Furthermore, when using powder spray fire extinguishers or CO2 fire extinguishers, the fire may be extinguished while the extinguishing agent is being sprayed, but it may reignite (re-ignite) once the spraying stops.

[0028] Furthermore, using acidic or alkaline fire extinguishing liquids can corrode the aluminum casing of lithium-ion secondary batteries and other devices, generating hydrogen gas. Acidic and alkaline fire extinguishing liquids also adversely affect normal batteries, posing a risk of secondary fires caused by the liquids themselves.

[0029] Incidentally, in order to increase the capacity of non-aqueous electrolyte batteries, the use of materials such as lithium metal and lithium alloys in the negative electrode is being considered.

[0030] These are water-reactive substances, meaning they ignite or generate hydrogen upon contact with water. For this reason, it is generally advisable to avoid contact with water. For example, in the case of metallic lithium fires, suffocation extinguishing using fire-fighting sand such as dry sand, expanded vermiculite, or expanded perlite is considered effective.

[0031] However, in the case of a battery fire involving metallic lithium, not only the metallic lithium but also the vaporized organic electrolyte burns fiercely, and oxygen may also be supplied from the positive electrode material inside the battery. For example, even if one attempts to extinguish a battery fire involving metallic lithium by suffocating it with dry sand, flammable gases from the organic electrolyte and oxygen released from the positive electrode leak out through the gaps in the sand, causing flames to rise and engulf the sand.

[0032] When halogenated fire extinguishing agents, which are effective against general fires and fires involving flammable liquids, are used, metallic lithium and halogen react violently to produce lithium halide. For this reason, the inventors considered the use of halogenated fire extinguishing agents to be inappropriate.

[0033] As mentioned above, Patent Document 1 presents a technology in which a pouch made of plastic film ruptures upon receiving heat during a fire, automatically releasing fire-extinguishing gel. However, this configuration has the drawback that the heat transferred to the plastic film is quickly absorbed by the fire-extinguishing gel, making it difficult for the temperature of the plastic film exposed to the flames to reach the temperature necessary for rupture.

[0034] This occurs because heat rapidly transfers from the plastic film to the fire-extinguishing gel, which then absorbs that heat. This is similar to the principle behind why a container filled with water doesn't melt or burn when exposed to flames. Water has a high specific heat of approximately 4200 J / kg·K, allowing it to absorb a large amount of thermal energy. Therefore, even when directly heated by fire, the temperature of water does not rise immediately. Furthermore, water has high thermal conductivity, meaning it quickly disperses heat from the heated area throughout the entire substance.

[0035] Furthermore, fires involving batteries and capacitors are not the only examples of explosions that occur during combustion, causing the contents to scatter. For instance, sealed containers such as aerosol cans and gas cylinders can explode due to increased internal pressure from combustion heat or leakage of flammable gas into the air. Additionally, substances that react violently with water to produce hydrogen gas, such as alkali metals, alkaline earth metals, active hydrogen storage alloys, and hydrides, are prone to ignition and scattering. Therefore, the inventors considered it important to develop techniques to prevent the contents from scattering during combustion when extinguishing fires.

[0036] Furthermore, once the thermite reaction occurs at the end of a battery's thermal runaway phase, extinguishing the fire becomes extremely difficult. Currently, there is no effective way to stop the reaction once it has started. For this reason, the inventors believed it was important to detect the battery's thermal runaway phase early and activate the fire extinguishing system quickly.

[0037] Furthermore, some batteries and capacitors have a structure in which electrodes and separators are stacked or wound in multiple layers. Due to this structure, it is difficult to effectively transfer heat through the multiple layers of separators, so even if the outside of the battery or capacitor is cooled when it catches fire, the inside may not be cooled sufficiently, maintaining a high temperature inside and increasing the risk of re-ignition. Also, if there is any remaining electrical capacity in the battery, this capacity may cause thermal runaway to recur. In addition, in the case of battery packs, if a fire occurs in one battery cell, the heat can spread to adjacent battery cells, potentially causing a time-limited and chain reaction of secondary fires.

[0038] Given this background, developing technologies to safely dispose of batteries after thermal runaway is extremely important not only for extinguishing fires and suppressing their spread, but also for minimizing the risk of re-ignition.

[0039] This invention has been made in view of the above, and aims to provide a fire extinguishing case that is more suitable for chemical batteries and capacitors than conventional ones. [Means for solving the problem]

[0040] According to one embodiment of the present invention for achieving the above objective, the fire extinguishing case has a mechanism for discharging a fire extinguishing agent upon sensing heat, and comprises a hollow section in which an object to be extinguished is placed, a wall section surrounding the hollow section, and a fire extinguishing section that discharges a fire extinguishing agent upon sensing heat, wherein the fire extinguishing agent contains a silicate aqueous solution or a phosphate aqueous solution that, upon contact with the object to be extinguished, generates a solid silicate compound or a solid phosphate compound on the surface of the object to be extinguished to extinguish the fire. With this configuration, when a fire breaks out inside the fire extinguishing case, the fire extinguishing agent discharged from the fire extinguishing section comes into contact with the object to be extinguished, and a solid silicate compound or a solid phosphate compound is generated on the surface of the object to be extinguished, thereby enabling efficient fire extinguishing.

[0041] Using a fire extinguishing agent containing a silicate or phosphate aqueous solution slows down the transfer of heat from the heated area to the surroundings, making it easier for heat to concentrate locally. As a result, the amount of heat transferred to the heat-sensitive part made of thermoplastic resin is not immediately absorbed by the fire extinguishing agent. With a small amount of heat, the temperature of the heat-sensitive part near the heat source or exposed to the flame rises, causing it to break or deform due to the heat, forming an opening, which allows the fire extinguishing liquid to flow towards the object being extinguished, thus enabling fire suppression.

[0042] In this fire extinguishing case, the fire extinguishing section comprises a sealed container equipped with a heat-sensitive element and the fire extinguishing agent sealed inside the sealed container. The heat-sensitive element is made of thermoplastic resin and, when exposed to heat, it breaks or deforms, opening up and causing the fire extinguishing agent inside the sealed container to leak out. With this structure, when a fire breaks out, the heat-sensitive element breaks or deforms, causing the fire extinguishing agent to leak out and the fire can be extinguished immediately. Furthermore, because the fire extinguishing agent is sealed inside the sealed container, it can block out the atmosphere and suppress deterioration of the fire extinguishing agent.

[0043] This fire extinguishing case is characterized in that the walls constituting the sealed container also serve as the heat-sensitive element. With this structure, the walls of the sealed container act as the heat-sensitive element without the need for a separate heat-sensitive element, resulting in a simple structure, and also allowing the extinguishing agent to flow out efficiently and extinguish the fire in the event of a fire.

[0044] In this fire extinguishing case, the fire extinguishing section is a sheet-shaped fire extinguishing sheet, and the fire extinguishing sheet is provided on the inner surface of the wall portion. With this configuration, a sheet-shaped fire extinguishing sheet containing a fire extinguishing agent is provided on the inner surface of the wall portion of the case, so when a fire breaks out inside the case, the fire extinguishing agent flows out from this fire extinguishing sheet and extinguishes the object to be extinguished.

[0045] In this fire extinguishing case, the fire extinguishing section is a second hollow section in the wall section, the fire extinguishing agent is filled into the second hollow section, part or all of the inner surface of the wall section is made up of a heat-sensitive section, the heat-sensitive section is made of thermoplastic resin and is destroyed or deformed by heat, opening up and allowing the fire extinguishing agent in the second hollow section to flow out. With this configuration, the fire extinguishing agent is filled into the hollow section provided in the wall section of the case, and the heat-sensitive section is arranged on the inner surface of the wall section, so that when a fire breaks out inside the case, the fire extinguishing agent flows out from the hollow section in the wall section through the heat-sensitive section and extinguishes the object to be extinguished.

[0046] In this fire extinguishing case, the inner surface of the wall is composed of the heat-sensitive part, and the outer surface is made of a thermoplastic resin different from the inner surface. The inner surface of the wall is made of a resin with a lower melting point than the outer surface, and the outer surface of the wall is made of a resin with higher mechanical strength than the inner surface. With this configuration, by using a resin that melts at a low temperature for the wall closer to the object to be extinguished, the thermal sensitivity of the heat-sensitive part is increased, and by using a resin with high mechanical strength for the wall further away from the object to be extinguished, a fire extinguishing system with excellent physical durability can be created.

[0047] In this fire extinguishing case, the fire extinguishing sheet is equipped with a rig that divides the internal space into multiple compartments, and the fire extinguishing agent is sealed in each of these compartments. With this configuration, by sealing the fire extinguishing agent in multiple compartments, it becomes possible to release the extinguishing liquid again if the object being extinguished reignites. Furthermore, it is possible to fill each compartment with multiple different fire extinguishing agents to create a fire extinguishing system that can handle various types of fires.

[0048] In this fire extinguishing case, an insulating material is further provided on the inner surface of the wall or the inner surface of the fire extinguishing sheet. The insulating material consists of a porous insulating material or a group of fibers, and the Gurley value of the insulating material as defined in JIS P8117 is 0.1 seconds or more / 100cc and 50 seconds or less / 100cc. This configuration suppresses the release of heat to the outside, thereby increasing the effectiveness of preventing the spread of fire and secondary fires.

[0049] In this fire extinguishing case, the insulating material is an insulating material supported with silicate or phosphate. This configuration further improves the insulating properties of the insulating material.

[0050] In this fire extinguishing case, the thermal insulation material is an insulating material having at least one selected from polyvinyl chloride resin, chlorinated polyvinyl chloride resin, ethylene vinyl acetate copolymer, and ethylene propylene diene rubber. With this configuration, the thermal insulation performance of the insulating material is further improved.

[0051] In this fire extinguishing case, the silicate aqueous solution is a liquid obtained by dissolving a silicate represented by A2O·nSiO2 in water, where A is at least one of an alkali metal element, a guanidine compound, or an ammonium compound, and n is between 0.5 and 12. The phosphate aqueous solution is a liquid obtained by dissolving a phosphate represented by Al2O3·nP2O5 in water, where n is between 0.5 and 12. With this configuration, the solid silicate compound is firmly formed on the surface of the object to be extinguished, enhancing its function as a barrier agent to prevent the scattering of contents. Furthermore, when n is between 1.7 and 5.5, hydrogen generation does not occur even when the extinguishing liquid comes into contact with Al. Furthermore, the solid phosphate compound is firmly formed on the surface of the object to be extinguished, enhancing its function as a barrier agent to prevent the scattering of contents. Furthermore, hydrogen is not generated by the reaction between the extinguishing liquid and Al. Furthermore, when n is 1.7 or higher, hydrogen generation does not occur even when the extinguishing liquid comes into contact with Al.

[0052] In this fire extinguishing case, the solid silicate compound or solid phosphate compound that is formed on the surface of the object to be extinguished upon contact with the object is porous. With this configuration, the specific surface area of ​​the solid silicate compound or solid phosphate compound is high, which improves hygroscopicity and enhances the cooling effect. On the other hand, in the absence of moisture supply to the solid silicate compound or solid phosphate compound, or in low humidity environments, the hygroscopicity decreases, allowing it to function as an insulating material and suppress the release of heat to the outside.

[0053] In this fire extinguishing case, the solid content concentration of the silicate or phosphate is greater than 30% by mass and less than 70% by mass. Within this concentration range, water-reactive substances such as zero-valent alkali metals, alkali metal alloys, and materials that have absorbed alkali metals can be deactivated while suppressing rapid reactions. It is particularly effective against zero-valent metallic lithium, lithium metal alloys, carbon that has absorbed lithium metal ions, carbon that has absorbed sodium metal ions, and carbon that has absorbed potassium metal ions.

[0054] In this fire extinguishing case, the surfactant is contained in an amount of 0.01% by mass or more and 10% by mass or less, based on the solid content of the fire extinguishing agent. With this configuration, air bubbles are easily encapsulated in the silicate aqueous solution or phosphate aqueous solution that becomes the fire extinguishing liquid, suppressing the amount of heat transferred to the heat-sensitive part from being absorbed by the fire extinguishing liquid, and causing the temperature of the heat-sensitive part to rise more easily when it is close to a heat source or when exposed to flames. As a result, it becomes easier to melt with heat, causing destruction or deformation, increasing the diameter of the holes in the openings or increasing the number of openings, increasing the outflow rate of the fire extinguishing liquid toward the object being extinguished, and improving the fire extinguishing capacity. In addition, the inclusion of a surfactant makes it easier to form porous solid silicate compound or solid phosphate compound with finer air bubbles. Furthermore, the formation of a solid silicate compound or solid phosphate compound containing a surfactant improves hygroscopicity, enhances the duration of the cooling effect, and contributes to preventing re-ignition.

[0055] In this fire extinguishing case, the gas adsorbent is contained in an amount of 1% by mass or more and 50% by mass or less, based on the solid content of the fire extinguishing agent. If the gas adsorbent is capable of adsorbing organic gases, hydrogen fluoride (HF), carbon monoxide (CO), and hydrogen sulfide (H2S) generated during thermal runaway of batteries and capacitors, the amount of these toxic gases released to the outside can be reduced.

[0056] In this fire extinguishing case, the extinguishing agent contains 1% to 40% by mass of thermally expanding powder based on its solid content, and the thermally expanding powder is a group of particles made of thermoplastic resin containing liquid hydrocarbons or liquid halogen-based solvents. With this configuration, by filling the sealed container with the extinguishing agent at a temperature lower than room temperature, the thermally expanding powder expands when the temperature rises to room temperature, increasing the pressure inside the sealed container. Furthermore, the heat from the fire causes the thermally expanding powder to expand even further, increasing the pressure. As a result, the amount of extinguishing agent that flows out when the container is opened increases.

[0057] In this fire extinguishing case, based on the solid content of the fire extinguishing agent, ceramic powder is contained in an amount of 1% by mass or more and 30% by mass or less, wherein the ceramic powder is an oxide of an element selected from Si, Al, Fe, Ti, Mg, and Ca, and has a median diameter (D50) of 10 nm or more and 500 nm or less. With this configuration, the fine ceramic particles adhere to the surface of the object to be extinguished during the combustion process, blocking the supply of oxygen and absorbing thermal energy, thereby enhancing the fire extinguishing effect. Here, the median diameter (D50) is the particle size at which the cumulative frequency reaches 50% when converted to volume based on the volume standard, using the laser diffraction-scattering particle size distribution method, and the particle size in this application refers to this.

[0058] In this fire extinguishing case, the object to be extinguished may be a chemical battery with a non-aqueous electrolyte, a capacitor with a non-aqueous electrolyte, or a device equipped with either of these.

[0059] In this fire extinguishing case, the chemical battery or the capacitor, or the device equipped with either of these, may comprise zero-valent lithium metal, an alkali metal alloy, or alkali metal ion storage carbon.

[0060] According to one embodiment of the present invention, the fire extinguishing case The fire extinguishing system is equipped with the fire extinguishing case which constitutes a room The hollow portion The space of the aforementioned chamber In other words, it can also be used as a fire extinguishing system. [Effects of the Invention]

[0061] According to the fire extinguishing case of the present invention, since heat can be detected and the extinguishing agent can be released quickly, fires can be effectively extinguished even if they break out inside the case. [Brief explanation of the drawing]

[0062] [Figure 1] This figure shows the change in liquid temperature and reaction time during the reaction of various potassium silicate aqueous solutions with metallic lithium according to one embodiment of the present invention. [Figure 2] This figure shows a concept of a fire extinguishing sheet according to one embodiment of the present invention. [Figure 3] This figure shows a conceptual cross-section of a fire extinguishing case according to one embodiment of the present invention. [Figure 4] This figure shows a three-dimensional concept of a fire extinguishing case according to one embodiment of the present invention. [Figure 5] This figure shows the temperature change of a fire extinguishing case according to one embodiment of the present invention. [Figure 6] This figure shows a modified example of a fire extinguishing case according to one embodiment of the present invention. [Modes for carrying out the invention]

[0063] The following describes embodiments and examples according to one aspect of the present invention, but various additions, modifications, or deletions are possible without departing from the spirit of the present invention.

[0064] The fire extinguishing case of this embodiment is equipped with a fire extinguishing unit that senses heat and releases a fire extinguishing agent inside the case. This fire extinguishing unit extinguishes the fire by a mechanism that senses heat and releases a liquid fire extinguishing agent (hereinafter sometimes referred to as "fire extinguishing liquid"). This heat is generated by combustion, reaction, short circuit, etc., of the object to be extinguished. For example, it is the heat generated by abnormal heat generation or ignition of chemical batteries, capacitors, or devices equipped with these.

[0065] The fire extinguishing unit of this embodiment comprises a sealed container and the fire extinguishing agent sealed inside the sealed container. This sealed container is a container for housing the fire extinguishing agent which has a heat-sensitive element. The heat-sensitive element breaks or deforms and opens when it reaches a certain temperature due to the heat during a fire or thermal runaway, causing the fire extinguishing agent to leak out of the container.

[0066] Examples of suitable materials include thermoplastic resins such as polypropylene (PP), polyethylene (PE), polylactic acid (PLA), polyvinyl chloride (PVC), polyvinylidene chloride (PVdC), polystyrene (PS), polyvinyl acetate (PVAc), polyurethane (PUR), polyvinyl alcohol (PVA), polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer, acrylonitrile butadiene styrene (ABS), acrylonitrile styrene (AS), acrylic resin (PMMA), polyethylene terephthalate (PET), nylon 6 (PA6), nylon 66 (PA66), nylon 12 (PA12), polyacetal (POM), polycarbonate, and polybutylene terephthalate (BET). Since thermoplastic resins with lower melting points are more easily opened by heat, it is preferable to use a resin with a melting point of 250°C or lower among the above materials.

[0067] The above-mentioned sealed container has a hollow section inside, and the front and back walls are a continuous, integrated hollow structure. The fire extinguishing agent may be filled into the hollow section of the sealed container. With this structure, since the fire extinguishing agent is sealed inside the sealed container, it is possible to block out the atmosphere and suppress deterioration of the fire extinguishing agent.

[0068] The front wall or the back wall may each be made of different thermoplastic resins. By using different materials for the front and back walls, properties and functionalities that cannot be obtained with a single material can be imparted. In other words, the advantages of each material can be combined.

[0069] By using a resin that melts at a low temperature for the wall closest to the object being extinguished, the thermal sensitivity of the heat-sensitive part can be increased. Therefore, if the front wall is the wall closest to the object being extinguished and the back wall is the wall furthest from the object, it is preferable that the front wall is made of a thermoplastic resin with a lower melting point than the back wall. Furthermore, by using a thermoplastic resin with high mechanical strength for the wall furthest from the object being extinguished, a fire extinguishing system with superior physical durability can be created. Therefore, it is preferable that the back wall is made of a resin with higher mechanical strength than the front wall.

[0070] For example, if two different resins, one made of polyethylene (PE) resin for the outer wall and the other of polypropylene (PP) resin for the inner wall, are integrated together with a hollow space between them, and this hollow space is filled with a fire extinguishing agent, the PE outer wall has a lower melting point than the PP inner wall, allowing it to open at a relatively low temperature and release the fire extinguishing agent. Furthermore, the PP inner wall has superior tensile strength, fatigue resistance, and chemical resistance compared to the PE outer wall, resulting in a fire extinguishing section that is more resistant to external impacts and chemicals.

[0071] To manufacture a fire extinguishing unit of this type, it is first necessary to obtain a structure in which two different resins are integrated, with a hollow space between them. To manufacture this structure, an existing hollow structure obtained by injection molding or blow molding is prepared, and after filling this hollow space with a fire extinguishing agent, the opening for the fire extinguishing agent is sealed by heat welding or bonding. For example, when manufactured by injection molding, molten thermoplastic resin is injected into the cavity of a mold, and the fire extinguishing agent is injected into the hollow space obtained by cooling and solidifying. In the case of blow molding, molten thermoplastic resin is passed through an extruder to create a shape with an opening and a closed end, and the fire extinguishing agent is filled into this shape.

[0072] This fire extinguishing unit is characterized by having a fire extinguishing agent that is physically connected in multiple sections and stored in multiple compartments. With this configuration, by storing the fire extinguishing agent in multiple compartments, it becomes possible to release the extinguishing liquid again when the object being extinguished reignites. Furthermore, with this configuration, it is possible to fill each compartment with multiple different fire extinguishing agents to create a fire extinguishing device that can handle various types of fires. Here, "physically connected" specifically means that multiple parts or elements are integrated by physical means. In other words, it has a base material that is physically connected in multiple sections and stored in multiple compartments.

[0073] A fire extinguishing device of this type can be manufactured, for example, by sealing one side of the cross-section of a commercially available corrugated plastic cardboard, injecting a fire extinguishing agent from the other open side, replacing the air inside the cardboard, and then sealing the opening with heat welding or adhesive. This allows for the creation of a structure in which each of multiple compartments is filled with fire extinguishing agent. The amount of fire extinguishing agent injected should be adjusted according to the volume of the hollow part of the corrugated plastic cardboard and the volume of each compartment.

[0074] The base materials, which are physically connected in multiple units and stored in separate compartments, have a thickness of 0.1 mm to 5000 mm and a basis weight of 2 g / m². 2 More than 30000g / cm 2 Preferably, the following conditions apply: a thickness of 0.5 mm or more and 2000 mm or less, and a basis weight of 10 g / m². 2 More than 10000g / cm 2 The following applies:

[0075] To suppress the release of heat to the outside, insulating material may be provided in the front wall or back wall as described above. In this case, the insulating material is preferably made of a porous body or a group of fibers, and the Gurley value of the insulating material as defined in JIS P8117 is preferably 0.1 seconds or more / 100cc and 100 seconds or less / 100cc. When the Gurley value of the insulating material is within this range, and the structure is configured in the order of front wall, insulating material, fire extinguishing agent, and back wall from the fire target outward, that is, when the insulating material is placed between the front wall, which is made of thermoplastic resin that acts as the heat-sensitive part, and the fire extinguishing agent, the transfer of heat to the fire extinguishing agent is delayed, making it easier to open (thermally destroy) the front wall with a small amount of heat, and allowing the fire extinguishing agent to be released more quickly. At that time, the fire extinguishing agent can be allowed to flow out to the fire target side through the insulating material. Furthermore, if the structure is configured in the order of insulation material, front wall, fire extinguishing agent, and back wall from the fire target outward, that is, if insulation material is placed between the fire target and the thermoplastic resin that acts as the heat-sensitive part, the thermal sensitivity of the front wall, which acts as the heating part, will decrease, but the heat resistance of the front and back walls will improve dramatically, and when the fire extinguishing agent is released, it will be able to flow towards the fire target through the insulation material.

[0076] As the density of an insulating material decreases, its thermal conductivity tends to decrease as well. However, if the density is too low, the number of voids increases, leading to heat exchange between gas molecules, which can actually increase thermal conductivity. Therefore, the density of the insulating material mentioned above is 30 kg / m³. 3 More than 500kg / m 3 The following is preferable: 80 kg / m 3 More than 300kg / m 3 The following are preferable.

[0077] Further, the above heat insulating material is preferably a heat insulating material carrying a silicate or a phosphate (for example, glass wool, rock wool, cellulose fiber, insulation board, wool, cork charcoal, polystyrene porous body, urethane porous body, phenol porous body, etc., to which an aqueous silicate solution or an aqueous phosphate solution is applied and dried), or a heat insulating material having at least one selected from polyvinyl chloride resin, chlorinated polyvinyl chloride resin, ethylene vinyl acetate copolymer, and ethylene propylene diene rubber. The loading amount is preferably 0.1 mg / cm 2 or more and 100 mg / cm 2 or less. This has the effect of improving both the heat insulation and the flame retardancy of the heat insulating material.

[0078] The fire extinguishing agent of this embodiment may be a powder or a liquid having fluidity, but since it can extinguish fire without generating harmful gases during fire extinguishing, it is preferable to use a fire extinguishing liquid containing an aqueous silicate solution or an aqueous phosphate solution. These are non-combustible, and by containing an aqueous silicate solution or an aqueous phosphate solution, the heat of the heated part is retarded from being transferred to the surroundings, and the heat is likely to be locally concentrated. As a result, the amount of heat transferred to the heat-sensitive part made of a thermoplastic resin is not immediately taken away by the fire extinguishing agent, and with a small amount of heat, the temperature of the heat-sensitive part close to the heat source or exposed to the flame rises, thermally melts to form an opening, and the fire extinguishing agent flows out toward the fire extinguishing object, enabling fire extinguishing.

[0079] By including an aqueous silicate solution or an aqueous phosphate solution in this fire extinguishing agent, the following effects can be obtained. When a silicate or phosphate aqueous solution comes into contact with a fire-fighting target, the water in the solution vaporizes, cooling the target. As the water vaporizes, the concentration of the solution near the point of contact increases, resulting in a high-viscosity silicate or phosphate aqueous solution. This suppresses the flow of the extinguishing agent and extends the contact time. Furthermore, once the water is removed and the solution dries, solid silicate compounds or solid phosphate compounds derived from the solid components of each solution are formed on the surface of the fire-fighting target, suffocating the fire. Because this solid is hygroscopic, it also absorbs moisture from the outside (such as dilute salt solutions or moisture in the air) and has a cooling effect. In addition, the solid formed on the surface of the fire-fighting target increases in thickness and forms a porous body containing air bubbles as the temperature of the fire-fighting target increases. The porous solid then functions as an insulator, suppressing heat release to the outside. Furthermore, increasing the specific surface area of ​​the solid material enhances its hygroscopic properties, which in turn improves its cooling effect.

[0080] In other words, the solid material formed on the surface of the object being extinguished has reduced hygroscopicity in the absence of moisture supply or in low humidity environments, functioning as an insulator and suppressing the release of heat to the outside. On the other hand, in the presence of moisture supply or in high humidity environments, it exhibits high hygroscopicity and functions as a coolant, absorbing heat from the object being extinguished.

[0081] Furthermore, if the object to be extinguished is a water-reactive substance such as metallic lithium, lithium alloy, or carbon containing alkali metals, the water in these aqueous solutions will vaporize, cooling the object, but simultaneously generating hydrogen bubbles due to the decomposition reaction of water. As the decomposition of water in the aqueous solution progresses, the concentration of the aqueous solution near the water-reactive substance increases, resulting in a highly viscous silicate or phosphate aqueous solution containing hydrogen bubbles. As the decomposition of water progresses further, the surface of metallic lithium, etc., will be covered with a porous white solid. This solid also functions as a barrier agent to prevent scattering due to rupture, etc., and because it contains little water, the water decomposition reaction is less likely to occur, suppressing the rapid progress of the reaction. In addition, because it is a foam, it exhibits high heat insulation properties. However, this porous material is hygroscopic. Therefore, it does not have a complete waterproofing effect, and it can gradually react with water over time to deactivate the water-reactive substance.

[0082] On the other hand, even if the extinguishing agent is simply water, the water will vaporize upon contact with the object being extinguished, thus having a cooling effect. However, since there is no change in viscosity near the contact surface with the object, the water flows off quickly, resulting in a drawback of a short contact time. Adding a water-soluble resin to the water to increase its viscosity will have the same thickening effect as the silicate or phosphate aqueous solutions mentioned above, but since the water-soluble resin is flammable, there is a risk of it becoming a new fuel source. Furthermore, even after the water is removed and the solid is dried, this solid does not exhibit the excellent hygroscopic properties of the silicates or phosphates mentioned above, so a sufficient cooling effect cannot be obtained. In addition, the solid formed on the surface of the object being extinguished does not form a thick porous body containing air bubbles, so the effect is limited to string droplets. Moreover, if the target contains alkaline components such as alkali metals, hydroxides, or carbonates, the viscosity that is optimal for increasing pH may change significantly.

[0083] Thus, the fire extinguishing agent of this embodiment provides a conventional cooling effect, as well as a suffocation and heat insulation effect due to the solid matter derived from its solid components. Furthermore, because this solid matter has excellent hygroscopic properties, it can provide a sustained cooling effect through the water contained in the fire extinguishing agent and moisture in the atmosphere.

[0084] The above silicate aqueous solution may be a polysilicate such as orthosilicate (A4SiO4), metasilicate (A2SiO3), pyrosilicate (A6Si2O7), disilicate (A2Si2O5), or tetrasilicate (A2Si4O9), or a solution of A2Si2O5, A2Si3O7, A2Si4O9, etc. in water. However, it is preferable that the silicate represented by the general formula A2O·nSiO2 satisfies the conditions that A is an alkali metal element, or at least one of a guanidine compound or an ammonium compound, and n is between 0.5 and 12, because the solid silicate compound is firmly formed on the surface of the object to be extinguished, and its function as a barrier agent to prevent the scattering of contents is enhanced. More preferably, A is at least one alkali metal element from lithium (Li), sodium (Na), or potassium (K). Furthermore, it is preferable that n is between 1.7 and 5.5, because hydrogen generation does not occur even when the extinguishing liquid comes into contact with Al. Furthermore, from the viewpoint of a longer pot life for the silicate aqueous solution, it is preferable that n is 5 or less.

[0085] The above-mentioned aqueous phosphate solution may be a solution of monoaluminum phosphate (Al(H2PO4)3), aluminum hydrogen phosphate (Al2(H2PO2)3), aluminum metaphosphate (Al(PO3)3), monomagnesium phosphate (Mg(H2PO4)3), magnesium hydrogen phosphate (MgHPO4), magnesium metaphosphate (Mg(PO3)2), monocalcium phosphate (Ca(H2PO4)3), calcium hydrogen phosphate (CaHPO4), tricalcium phosphate (Ca3(H2PO4)2), calcium metaphosphate (Ca(PO3)2), etc., dissolved in water. However, it is preferable that the phosphate represented by the general formula Al2O3·nP2O5 satisfies the condition that n is between 0.5 and 5.5, because the solid silicate compound is firmly formed on the surface of the object to be extinguished, and its function as a barrier agent to prevent the scattering of contents is enhanced. Furthermore, it is preferable that n is 1.7 or higher, because hydrogen generation does not occur even when the extinguishing liquid comes into contact with Al. Furthermore, from the viewpoint of a longer pot life for the phosphate aqueous solution, it is preferable that n is 5 or less.

[0086] Furthermore, for the reasons of improved hydrophilicity to the object being extinguished and the ease with which foam is generated, it is preferable that the silicate aqueous solution or phosphate aqueous solution contains at least one surfactant, such as a nonionic surfactant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or a nonionic surfactant. In that case, it is preferable that the surfactant is contained in an amount of 0.01% by mass or more and 10% by mass or less, based on the solid content of the fire extinguishing agent. By containing a surfactant within this range, bubbles are more likely to be present in the silicate aqueous solution or phosphate aqueous solution, and these bubbles delay the transfer of heat from the heated area to the surroundings, making it easier for heat to concentrate locally. In addition, the solid material formed on the surface of the object being extinguished is more likely to become a foam, and the resulting foam is more likely to become a porous body containing fine bubbles. If the bubbles contained in the porous body are fine and the porosity is high, the heat insulation properties will be high. In addition, countless fine voids suppress the reaction between water-reactive substances and water, and suppress rapid hydrogen reactions.

[0087] Even in the case of water with a surfactant dissolved in it, foam is more likely to form, and these bubbles have the effect of delaying heat transfer from the heated area. However, for surfactants to function effectively, it is essential to use them within the appropriate temperature range, and fire extinguishing agents that use surfactants alone are unsuitable.

[0088] Furthermore, in order to increase the porosity of the porous material, gas generating agents such as sodium peroxide, hydrogen peroxide, sodium perborate, percarbonate, and ammonium phosphate may be added as needed.

[0089] In the above-mentioned fire extinguishing agent, a gas adsorbent may be added to the fire extinguishing agent in order to adsorb toxic gases generated from the object being extinguished. In this case, if the amount of gas adsorbent is too high, the function of the fire extinguishing agent will be reduced, and if it is too low, a sufficient gas adsorption effect cannot be obtained. Therefore, it is preferable to include the gas adsorbent in an amount of 1% by mass or more and 50% by mass or less, based on the solid content of the fire extinguishing agent.

[0090] For example, activated carbon, carbonates, phosphates, calcium hydroxide, potassium hydroxide, copper, and copper oxide function as gas adsorbents for HF. Mixtures of copper compounds and manganese dioxide, or mixtures of copper and manganese dioxide, calcium oxide and potassium chromate, platinum catalysts, palladium catalysts, and activated carbon function as gas adsorbents for CO. Activated carbon also functions as an absorbent for organic gases. Zinc oxide, copper oxide, iron oxide, hydroxides, silicates, and activated carbon function as absorbents for H2S. The inclusion of the above-mentioned gas adsorbents allows them to adsorb or neutralize specific gases, thereby reducing the amount of harmful gases released into the environment.

[0091] In the above-mentioned fire extinguishing agent, thermally expanding powder may be included to increase the pressure inside the sealed container and increase the amount of fire extinguishing agent released when the container is opened. However, if there is too much, the function of the fire extinguishing agent will be reduced, and if there is too little, a sufficient effect in increasing the release volume will not be obtained. For this reason, it is preferable to include thermally expanding powder in an amount of 1% by mass or more and 40% by mass or less, based on the solid content of the fire extinguishing agent. Within this range, by filling the sealed container with the fire extinguishing agent at a temperature lower than room temperature, the thermally expanding powder will expand when it reaches room temperature, increasing the pressure inside the sealed container. Furthermore, the heat from the fire will cause the thermally expanding powder to expand further, increasing the pressure. As a result, the amount of fire extinguishing agent released when the container is opened will increase.

[0092] This thermally expanding powder is preferably a thermoplastic resin containing a liquid hydrocarbon or a liquid halogen-based solvent.

[0093] The above-mentioned fire extinguishing agent preferably has a solid content concentration of 15% by mass or more and 70% by mass or less. Within this concentration range, fires can be extinguished even if the object to be extinguished contains water-reactive substances such as zero-valent metallic lithium, lithium alloy anodes, and carbon-based materials that adsorb alkali metals. Furthermore, when these materials come into contact with the fire extinguishing agent, rapid reactions can be suppressed, and they can be safely deactivated. Moreover, a solid content concentration of more than 30% by mass and less than 70% by mass is more preferable, as the above effects are even greater.

[0094] Here, Li, Na, K, and rubidium (Rb) are known as alkali metals with a 0 valence. Of these, metallic Li is only a water-reactive substance, while metallic Na, metallic K, and metallic Rb are both spontaneously combustible and water-reactive substances. Since the effects of the invention cannot be obtained even if metallic Na, metallic K, and metallic Rb are used, they are unsuitable. Only metallic Li is considered a zero-valence alkali metal.

[0095] A Li alloy electrode refers to a negative or positive electrode containing an alloying material with Li. Examples include electrodes containing Li-indium (In) alloy, Li-silicon (Si) alloy, Li-tin (Sn) alloy, Li-germanium (Ge) alloy, Li-antimony (Sb) alloy, Li-bismuth (Bi) alloy, Li-Al alloy, and lithium-based sulfur materials. Other examples include negative electrodes made by doping silicon oxide (SiO) with Li. In alkali metal alloys, the alkali metal is preferably lithium.

[0096] Carbon-based materials that absorb alkali metals are materials containing alkali metal ions (Li + kaNa + , K + These are carbon-based materials in which alkali metals are intercalated. Examples include graphite, soft carbon, and hard carbon intercalated with lithium ions, soft carbon and hard carbon intercalated with sodium ions, and graphite, soft carbon, and hard carbon intercalated with potassium ions. The alkali metal in carbon-based materials that absorb alkali metals is not particularly limited as long as it is an alkali metal ion.

[0097] According to the above configuration, the sealed container is normally filled with a fire extinguishing agent. In the event of a fire or overheating, the heat-sensitive part made of thermoplastic resin melts and opens, allowing the fire extinguishing agent inside the sealed container to leak out, extinguishing the target object, preventing the spread of fire, and safely deactivating the agent. In this embodiment, the fire extinguishing system may also include a non-aqueous electrolyte chemical battery or a non-aqueous electrolyte capacitor, or a device equipped with either of these, as the object to be extinguished.

[0098] Here, non-aqueous electrolyte chemical batteries refer to a general term for battery systems that use electrolytes that do not primarily consist of water. For example, various non-aqueous electrolyte batteries are known, such as manganese dioxide-lithium primary batteries, graphite fluoride-lithium primary batteries, thionyl chloride-lithium primary batteries, copper oxide-lithium primary batteries, iron sulfide-lithium primary batteries, iodine-lithium primary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, lithium all-solid-state secondary batteries, lithium metal secondary batteries, lithium-air batteries, lithium-sulfur batteries, sodium-ion secondary batteries, sodium-sulfur batteries, sodium metal batteries, potassium-ion secondary batteries, polyvalent ion secondary batteries, and fluoride ion secondary batteries.

[0099] Non-aqueous electrolyte capacitors are a general term for capacitor systems that use electrolytes that do not primarily consist of water. Examples include electric double-layer capacitors, lithium-ion capacitors, sodium-ion capacitors, potassium-ion capacitors, magnesium-ion capacitors, and calcium-ion capacitors.

[0100] Furthermore, the fire extinguishing case of this embodiment may also extinguish a zero-valent lithium metal, a lithium alloy, or sodium storage carbon. In other words, it may be a chemical battery or capacitor equipped with zero-valent lithium metal, an alkali metal alloy, or alkali metal storage carbon.

[0101] The fire extinguisher case of this embodiment can also be applied to fire extinguishing equipment such as storage rooms and building fixtures, where the case is a chamber and the hollow section is a space. In other words, it can be used in places, equipment, structures, etc., where fires may occur. In that case, existing mechanisms, equipment, and devices such as pressure release mechanisms, explosion-proof equipment, ventilation equipment, temperature measuring devices, pressure measuring devices, voltage measuring devices, charging mechanisms, and discharge mechanisms may be used in combination. Furthermore, terminals may be attached to the storage case of this embodiment and used as a battery case or the like. [Examples]

[0102] [Consideration of fire extinguishing agents 1] A 50 mL beaker was placed containing metallic lithium (15 mm in diameter, 500 μm thick), and 12 mL of the specified fire extinguishing agent shown in Table 1, adjusted to 22°C (±1°C), was added. The time it took for the metallic lithium to completely dissolve in the solution and disappear was then measured.

[0103] [Table 1]

[0104] In this test, the fire extinguishing agents in Examples 1-38 and Comparative Examples 1-3 contained water. Therefore, in all test cases, water and metallic lithium reacted to generate hydrogen, producing heat, and the metallic lithium disappeared over time (2Li + xH2O → 2LiOH aq. + H2↑). Also, because metallic lithium is lighter than the fire extinguishing agent, it always floated on the surface of the water in the fire extinguishing agent while reacting. However, because the amount of metallic lithium used was small, spontaneous combustion did not occur in any of the test cases.

[0105] Table 2 shows the time it takes for metallic lithium to completely dissolve and disappear using each fire extinguishing agent. As is clear from Table 2, there was a difference in the time it took for metallic lithium to completely disappear depending on the fire extinguishing agent, and therefore the rate of hydrogen generation also differed for each fire extinguishing agent.

[0106] [Table 2]

[0107] Specifically, in Examples 1-38, Comparative Example 2, and Comparative Example 3, the hydrogen generation rate was slower compared to Comparative Example 1. However, the metallic lithium disappearance process observed in these test examples was different. In the fire extinguishing agents of Examples 1 to 38, it was observed that a white solid substance immediately formed as a film on the surface upon contact with metallic lithium.

[0108] This coating tended to become thicker and more porous as the solid content concentration of the aqueous solution increased. This is presumed to be because the increased viscosity associated with the increased concentration makes it more difficult for air bubbles to escape into the atmosphere, leading to the growth of a thicker porous film.

[0109] Furthermore, since this film inhibits contact with water, it is thought that the time required for complete dissolution increases once the film is formed. The reason the film becomes porous is thought to be that the solid content concentration of the fire extinguishing agent increases due to the decomposition of water and the generation of heat, leading to an increase in viscosity and the inclusion of hydrogen bubbles generated by the water decomposition reaction.

[0110] This solid material covers the metallic lithium and has low moisture content, making it less likely for the water to decompose. However, this porous material is hygroscopic and therefore does not provide complete waterproofing. For this reason, it is believed that the fire extinguishing agents in Examples 1-38 gradually deactivated the metallic lithium over time, eventually causing the metallic lithium to disappear.

[0111] When comparing the results of each example (Examples 6, 19, 28, and 35) where the solid content concentration was 25% by mass, the reaction with metallic lithium was significantly slower when using an aqueous aluminum phosphate solution. Since the aqueous aluminum phosphate solution is acidic, and metallic lithium becomes alkaline when dissolved in water, the two react and neutralize each other. The neutralized salt produced in this process also becomes a solid covering the surface of the metallic lithium, and it is thought that this suppresses direct contact with water, thereby reducing the reaction rate.

[0112] Furthermore, when comparing silicate aqueous solutions, the reaction with metallic lithium tended to be slower with sodium salts than with potassium salts, and slower with lithium salts than with sodium salts.

[0113] The fire extinguishing agent in Comparative Example 2 had high viscosity, which suppressed its fluidity, making it difficult to form fine flows and vortices in water. This likely reduced contact with metallic lithium and slowed the reaction rate. However, as the metallic lithium dissolved, the pH of the fire extinguishing agent increased, the viscosity gradually decreased, and the reaction became progressively more vigorous. Furthermore, the metallic lithium reacted while surrounded by hydrogen bubbles generated by the decomposition reaction of water. However, when the bubble diameter exceeded 10 mm, the bubbles burst, and their duration was short. These bubbles also remained fluid and did not solidify.

[0114] In Comparative Example 3, compared to Comparative Example 1, a larger amount of hydrogen bubbles were generated when the extinguishing agent came into contact with metallic lithium. These bubbles surrounded the metallic lithium, reducing the contact area with the extinguishing agent and thus slowing down the reaction rate. Furthermore, these bubbles were fluid and did not solidify.

[0115] Furthermore, it was found that in all fire extinguishing agents, the inclusion of surfactants tended to prolong the time it took for the metallic lithium to completely disappear.

[0116] The experimental results above revealed that when the fire extinguishing agent contains silicate or phosphate aqueous solutions, porous solid material forms on the surface of metallic lithium. Furthermore, when the concentration and viscosity of the fire extinguishing liquid are high, bubbles are less likely to escape into the atmosphere, allowing them to remain on the surface of metallic lithium for a longer period. This demonstrated that the reaction can be effectively suppressed. It was also confirmed that including a surfactant in the fire extinguishing liquid makes it easier to generate smaller bubbles.

[0117] [Consideration of fire extinguishing agents 2] To investigate whether metallic lithium can be ignited by an external flame, metallic lithium (diameter φ15 mm, thickness 500 μm) was placed in a 50 mL beaker, 12 mL of the specified extinguishing agent shown in Table 1, adjusted to 22 °C (±1 °C), was added, and after 5 seconds, it was directly heated for 10 seconds with a gas burner flame to verify whether or not the metallic lithium ignited during the reaction.

[0118] Table 3 shows the ignition results of metallic lithium during the reaction. "○" indicates no ignition, "△" indicates ignition but the ignition stopped over time, "×" indicates ignition, and "××" indicates a hydrogen explosion.

[0119] [Table 3]

[0120] As is clear from Table 3, in Comparative Example 1, when a flame was brought near the metallic lithium during the reaction, the hydrogen ignited and an explosion occurred. The metallic lithium then ignited, and a red flame color originating from the lithium metal was observed. In Comparative Examples 2 and 3, no explosion occurred, but when a flame was brought near the metallic lithium during the reaction, it ignited, and a red flame color originating from the lithium metal was observed.

[0121] In Examples 1, 2, 14, 15, 23, and 24, where the solid content concentration was 5% or less, no explosion occurred, similar to Comparative Examples 2 and 3. Although metallic lithium briefly ignited when a flame was brought near, sustained ignition was not observed. This indicates that metallic lithium could not maintain combustion.

[0122] In Examples 3-13, 16-22, and 25-38, where the solid content concentration was 10% or higher, the metallic lithium did not ignite when a flame was brought near it during the reaction, and no flame test was observed.

[0123] [Consideration of fire extinguishing agents 3] Figure 1 shows the time it took for the metallic lithium to completely disappear and the liquid temperature of the potassium silicate aqueous solution fire extinguishing agent at the time of complete disappearance in Examples 23, 25, 29, 31 and Comparative Example 1. As is clear from Figure 1, it can be seen that the rise in liquid temperature tends to become more gradual as the solid content ratio of the fire extinguishing agent increases.

[0124] In Comparative Example 1, upon contact with water, metallic lithium immediately generated a large amount of hydrogen, resulting in a rapid temperature increase. As the metallic lithium dissolved in the water and its volume decreased, the liquid temperature peaked at 47.4°C, and the heat generation gradually slowed down. Finally, when the metallic lithium completely dissolved in the water and the heat source disappeared, the water temperature decreased.

[0125] On the other hand, while hydrogen generation was confirmed in the examples, it was found that the temperature rise of the fire extinguishing agent was relatively small. In particular, in Example 31, the liquid temperature remained below 32°C, indicating that the temperature rise of the fire extinguishing agent was minimal. As the solid content ratio of the fire extinguishing agent increased, the solid material formed on the surface of the metallic lithium tended to foam and become thicker. This is thought to have exhibited high thermal insulation properties, suppressing the rise in liquid temperature.

[0126] [Consideration of fire extinguishing agents 4] To investigate whether metallic lithium would spontaneously ignite upon contact with the fire extinguishing agent, metallic lithium (diameter φ15 mm, thickness 500 μm) was immersed for 1 second in the fire extinguishing agents of Examples 20 and 36, which had been adjusted to 22°C (±1°C). After immersion, the mixture was wrapped in tissue paper and left in the atmosphere. Examples 20 and 36 did not spontaneously ignite even after being left for 24 hours.

[0127] [Consideration of fire extinguishing agents 5] Lithium metal covered with flammable material is prone to ignition when it comes into contact with water. Therefore, we investigated whether lithium metal (diameter φ15 mm, thickness 500 μm) wrapped in pulp nonwoven fabric (dimensions: 120 x 215 mm) would ignite when 2 mL of each fire extinguishing agent was sprayed onto it. Examples 20, 36, and Comparative Example 1, adjusted to 22°C (±1°C), were used as the fire extinguishing agents.

[0128] In Examples 20 and 36, no ignition occurred even after being left for 12 hours after water was sprayed, but in Comparative Example 1, ignition occurred 5 to 6 seconds after water was sprayed.

[0129] [Consideration of fire extinguishing agents 6] Li(Ni) 0.6 Co 0.2 Mn 0.2 A flat-wound lithium-ion battery with a rated capacity of 3Ah, consisting of an O2 positive electrode, an artificial graphite negative electrode, a polyolefin-based microporous separator, a 1M LiPF6 / (EC:DEC=1:1vol.,+vinylene carbonate 1wt.%) electrolyte, and an aluminum laminate casing, was overcharged at 9A (equivalent to a 3C rate) and ignited. 500 mL of the fire extinguishing agent from Example 7 or Comparative Example 1 was then sprayed onto the ignited battery.

[0130] In Example 7, the fire was extinguished by spraying water, but in Comparative Example 1, there was almost no effect on extinguishing the fire, and it continued to burn until all the combustible material was gone.

[0131] [Firefighting Department Review 1] PP corrugated cardboard (2.5mm thick, 300g / m² weight) 2 One side of the cross-section of the corrugated cardboard was sealed with silicone sealant, and the other open side was used to inject the fire extinguishing agents from Example 21 and Comparative Example 1, replacing the air inside the cardboard. The opening was then sealed with silicone sealant to obtain a fire extinguishing sheet in which each of the multiple compartments was filled with fire extinguishing agent.

[0132] Figure 2 shows a conceptual diagram of the fire extinguishing sheet. Figure 2(a) is a perspective view, and (b) is an exploded view. This sheet was installed as a lining on all six inner walls of a rectangular PLA resin case (100 mm long x 150 mm wide x 90 mm high), and a lithium-ion battery, which is the object to be extinguished, was placed inside.

[0133] Lithium-ion batteries are Li(Ni 0.6 Co 0.2 Mn 0.2A flat-wound lithium-ion battery with a rated capacity of 3Ah was used, consisting of an O2 positive electrode, an artificial graphite negative electrode, a polyolefin-based microporous separator, a 1M LiPF6 / (EC:DEC=1:1vol.,+vinylene carbonate 1wt.%) electrolyte, and an aluminum laminate outer casing. This battery was overcharged at 9A (equivalent to a 3C rate), causing it to overheat and catch fire.

[0134] When the fire extinguishing agent of Example 1 was used, it was confirmed that the PP material near the flame emitted from the battery melted and the fire extinguishing agent was released. Furthermore, the storage case made of PLA resin did not burn or deform due to heat.

[0135] On the other hand, when the fire extinguishing agent of Comparative Example 1 was used, the openings formed in the PP were small, and the fire extinguishing agent only seeped out, failing to release a sufficient amount. This is presumed to be because heat was absorbed by the fire extinguishing agent, making it difficult for the temperature to rise above the melting point of the PP, thus preventing the formation of large openings. Furthermore, from the above lithium-ion battery, Na(Ni 0.33 -Fe 0.33 -Mn 0.33 The same results were obtained when using a sodium-ion battery with a flat wound structure and a rated capacity of 1Ah, consisting of an O2 positive electrode, a hardbon negative electrode, a polyolefin-based microporous separator, a 1M NaPF6 / (EC:PC:DEC=1:1:1vol.) electrolyte, and an aluminum laminate outer casing.

[0136] [Firefighting Department Review 2] Study of fire extinguishing equipment injected with fire extinguishing agent in Example 17: Glass wool (thickness 10 mm, density 150 kg / m³) supported on the surface of the fire extinguishing sheet 1. 3 A composite sheet was created by layering these materials.

[0137] Glass wool supported with sodium silicate (Na2O·3.0SiO2) was prepared by applying Example 18 to glass wool and then drying it in the air (80°C, 10 hours).

[0138] This composite sheet was attached to the six sides (entire inner surface) of the case's interior, and K-type thermocouples were installed at designated positions in the cross-section of the storage case shown in Figure 3, thereby creating a rectangular parallelepiped-shaped PLA resin case (external dimensions: 214mm (length) x 172mm (width) x 98mm (height), internal dimensions: 185mm (length) x 121mm (width) x 85mm (height)). Furthermore, a pressure adjustment valve (internal pressure release valve) was installed to control the internal pressure.

[0139] Figure 4 shows a conceptual diagram of the fire extinguishing case. Twelve canisters of explosives to be extinguished (only the gunpowder-coated parts of handheld sparklers) were placed inside this case. After igniting the explosives, the case was immediately sealed. Point A was defined as the surface of the composite sheet near the explosives (the surface of the glass wool near the explosives), point B was defined as the space between the glass wool and the fire extinguishing sheet, and point C was defined as the PLA resin separated by the composite sheet (between the fire extinguishing sheet and the case). The temperature change at each point was measured.

[0140] Figure 5 shows the temperature of the case. Even under conditions where the internal temperature (point A) exceeded 1100°C, the temperature rise at point B, through the sodium silicate-supported insulation material, remained below 60°C. Furthermore, the temperature rise at point C, separated by the composite sheet, was low at approximately 19°C, preventing the case from burning or deforming due to heat. In addition, the same experiment was conducted with the outer casing replaced with a paper box, but the case did not burn. These results demonstrate that the fire extinguishing unit of the present invention functions effectively even at high temperatures, and its potential application as a safety measure, particularly in the event of battery fires, is recognized.

[0141] As described above, preferred embodiments of the present invention have been explained with reference to the drawings, but various additions, modifications, or deletions are possible without departing from the spirit of the present invention. For example, although a liquid fire extinguishing agent was used in this embodiment, it is thought that a certain effect can also be obtained with a powdered fire extinguishing agent. Furthermore, in the fire extinguishing section of this embodiment, it is also possible to seal liquid fire extinguishing agent and powdered fire extinguishing agent in each compartment, respectively. In addition, the concentrations and ratios of various elements such as the solid content concentration of silicates and phosphates in the fire extinguishing agent are not limited to the values ​​of the embodiments described above.

[0142] Furthermore, although the fire extinguishing case of this embodiment was described in which a sheet-like fire extinguishing section is arranged on the inner wall side of the case, it is not limited to this, and a structure can also be formed in which a second hollow section separate from the hollow section for housing the object to be extinguished is formed inside the wall of the case, as shown in Figure 6. In this case, the second hollow section is filled with a fire extinguishing agent, and part or all of the inner surface of the wall of the case is made of a heat-sensitive section, the heat-sensitive section is made of a thermoplastic resin, and the heat-sensitive section is destroyed or deformed by heat and opens, allowing the fire extinguishing agent in the second hollow section to flow out and extinguish the object to be extinguished. Therefore, such a structure is also included within the scope of the present invention.

Claims

1. A fire extinguishing case having a mechanism that senses heat and releases a fire extinguishing agent, It comprises a hollow section into which the object to be extinguished is placed, a wall section surrounding the hollow section, and a fire extinguishing section that senses heat and releases a fire extinguishing agent, The fire extinguishing agent includes a silicate aqueous solution or a phosphate aqueous solution that, upon contact with the object to be extinguished, generates a solid silicate compound or a solid phosphate compound on the surface of the object to be extinguished to extinguish the fire. The fire extinguishing unit comprises a sealed container equipped with a heat-sensitive element and the fire extinguishing agent sealed inside the sealed container. The heat-sensitive part is made of thermoplastic resin, and when it is damaged or deformed by heat, it opens up, causing the fire extinguishing agent inside the sealed container to leak out. Fire extinguisher case.

2. The aforementioned fire extinguishing unit is The walls constituting the aforementioned sealed container also serve as the heat-sensing element. The fire extinguishing case according to claim 1.

3. The fire extinguishing section is a sheet-shaped fire extinguishing sheet. The fire extinguishing sheet is provided on the inner surface of the wall portion. The fire extinguishing case according to claim 1.

4. A fire extinguishing case having a mechanism that senses heat and releases a fire extinguishing agent, It comprises a hollow section into which the object to be extinguished is placed, a wall section surrounding the hollow section, and a fire extinguishing section that senses heat and releases a fire extinguishing agent, The fire extinguishing agent includes a silicate aqueous solution or a phosphate aqueous solution that, upon contact with the object to be extinguished, generates a solid silicate compound or a solid phosphate compound on the surface of the object to be extinguished to extinguish the fire. The fire extinguishing section is the second hollow section of the wall section, The second hollow section is filled with the fire extinguishing agent. A part or all of the inner surface of the aforementioned wall portion is composed of a heat-sensing element. The heat-sensitive part is made of thermoplastic resin, and when it is damaged or deformed by heat, it opens up, causing the fire extinguishing agent in the second hollow part to leak out. Fire extinguisher case.

5. The aforementioned wall portion is The inner surface is composed of the heat-sensitive part, The outer surface is formed of a thermoplastic resin different from the inner surface, The inner wall of the aforementioned wall portion is made of a resin with a lower melting point than the outer wall. The outer wall of the aforementioned wall portion is made of a resin with higher mechanical strength than the inner wall. The fire extinguishing case according to claim 1.

6. The fire extinguishing sheet is equipped with a rig that divides the internal space into multiple sections, and each of the sections is sealed with the fire extinguishing agent. The fire extinguishing case according to claim 3.

7. An insulating material is further provided on the inner surface of the wall portion or on the inner surface of the fire extinguishing sheet. The aforementioned thermal insulation material consists of a porous thermal insulation material or a group of fibers. The Gurley value of the aforementioned insulation material, as defined in JIS P8117, is 0.1 seconds or more / 100cc and 50 seconds or less / 100cc. The fire extinguishing case according to claim 3.

8. The aforementioned thermal insulation material is a thermal insulation material supported with silicate or phosphate. The fire extinguishing case according to claim 7.

9. The aforementioned thermal insulation material is a thermal insulation material having at least one selected from polyvinyl chloride resin, chlorinated polyvinyl chloride resin, ethylene vinyl acetate copolymer, and ethylene propylene diene rubber. The fire extinguishing case according to claim 7.

10. The silicate aqueous solution is A 2 O・nSiO 2 A liquid obtained by dissolving a silicate represented by in water, wherein A is at least one of an alkali metal element, a guanidine compound, or an ammonium compound, and n is between 0.5 and 12. The aforementioned phosphate aqueous solution is Al 2 O 3 nP 2 O 5 A liquid obtained by dissolving a phosphate represented by in water, wherein n is between 0.5 and 12. The fire extinguishing case according to any one of claims 1 to 9.

11. The solid silicate compound or solid phosphate compound that is formed on the surface of the object to be extinguished when it comes into contact with the object to be extinguished is porous. The fire extinguishing case according to claim 10.

12. The solid content concentration of the silicate or phosphate is greater than 30% by mass and less than 70% by mass. The fire extinguishing case according to claim 10.

13. Based on the solid content of the fire extinguishing agent, the surfactant is contained in an amount of 0.01% by mass or more and 10% by mass or less. The fire extinguishing case according to claim 10.

14. Based on the solid content of the fire extinguishing agent, the gas adsorbent is contained in an amount of 1% by mass or more and 50% by mass or less. The fire extinguishing case according to claim 10.

15. Based on the solid content of the aforementioned fire extinguishing agent, it contains 1% by mass or more and 40% by mass or less of thermally expanding powder. The aforementioned thermally expanding powder is a group of particles made of thermoplastic resin containing a liquid hydrocarbon or a liquid halogen-based solvent. The fire extinguishing case according to claim 10.

16. Based on the solid content of the aforementioned fire extinguishing agent, it contains ceramic powder in an amount of 1% by mass or more and 30% by mass or less. The ceramic powder is an oxide of an element selected from Si, Al, Fe, Ti, Mg, and Ca, and has a median diameter (D ５０ ) is between 10 nm and 500 nm. The fire extinguishing case according to claim 1.

17. The object to be extinguished is a chemical battery with a non-aqueous electrolyte, a capacitor with a non-aqueous electrolyte, or a device equipped with either of these. The fire extinguishing case according to claim 10.

18. The chemical battery or the capacitor, or the device equipped with either thereof, comprises zero-valent lithium metal, or alkali metal alloy, or alkali metal ion storage carbon. The fire extinguishing case according to claim 17.

19. A fire extinguishing system comprising the fire extinguishing case described in claim 10, The fire extinguishing case constitutes a chamber, and the hollow portion constitutes the space within the chamber. Fire extinguishing equipment.

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