Water-added fire extinguishing agent

Abstract

To provide a water-added fire extinguishing agent which exhibits high fire extinguishing performance and allows fire extinguishment to be easily carried out by spraying.SOLUTION: A water-added fire extinguishing agent contains, as a fire extinguishing agent component, a thermally depolymerizable polymer having a structure to which a water-soluble functional group is imparted, an alkali metal salt thereof, or an alkaline earth metal salt thereof, wherein the thermally depolymerizable polymer having a structure to which a water-soluble functional group is imparted preferably has a structure represented by a specific chemical formula, and, in the case of the alkali metal salt, a sodium (Na) salt or a potassium (K) salt can be used, and, in the case of the alkaline earth metal salt, a calcium (Ca) salt or a magnesium (Mg) salt can be used.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a water-added fire extinguishing agent for use in the event of a fire. [Background technology]

[0002] Fires are typically extinguished using water (firewater). Water has a high specific heat and heat of vaporization, giving it a powerful cooling effect. It efficiently removes heat from burning or combustible materials, thereby extinguishing or preventing fires. However, water has a high surface tension, meaning it tends to fall and wash away rather than remain on the surface of the burning or combustible material. It is said that only about 10% of the water used in firefighting efforts actually contributes to the extinguishing of the fire. Therefore, a large amount of water is required for firefighting, as it must be continuously sprayed over an extended period of time. Furthermore, because the sprayed water flows down in large quantities rather than remaining in a pool, when extinguishing a fire in a high-rise building, for example, water can flow into lower floors not directly related to the fire, or splash onto adjacent buildings, potentially causing secondary damage.

[0003] On the other hand, there are cases where the amount of water resources near the fire site is limited. For example, in forest fires, it is often difficult to secure enough water to extinguish the fire. In such cases, it is particularly important to efficiently use the limited amount of water to extinguish the fire.

[0004] To date, the following water-added fire extinguishing agents have been developed to enhance the fire-extinguishing action of water.

[0005] (a) Phosphate inorganic compound fire extinguishing agents It usually contains ammonium phosphate as its main ingredient. When firewater containing phosphate inorganic compound fire extinguishing agents is sprayed on a fire area, the ammonium phosphate decomposes when heated, absorbing heat from the surrounding area. It also generates non-flammable gases, forming a gas layer around the area that blocks oxygen, and when it becomes even hotter, it turns into a molten glass-like substance, covering the burning surface and blocking oxygen. Because firewater containing phosphate inorganic compound fire extinguishing agents is colorless, adding a coloring agent is the first step in identifying the area where it has been sprayed, especially in forest fires.

[0006] However, in order to enhance the extinguishing effect of firewater by adding inorganic phosphate compound fire extinguishing agents, a large amount of fire extinguishing agent must be added to the water. Furthermore, the addition of coloring agents and other additives is time-consuming, making it difficult to quickly prepare firewater in the event of a fire. Furthermore, inorganic phosphate compounds are poorly soluble in water, so they are prone to forming powder. When stored for long periods, the components precipitate and form clumps, requiring equipment to crush them before use. The poor solubility of inorganic phosphate compounds in water also creates the problem of time-consuming cleaning of equipment and materials.

[0007] Furthermore, because ammonium phosphate is similar to the components used in fertilizers, it has been pointed out that it can cause environmental problems, such as eutrophication in the soil where it is applied.

[0008] (b) Synthetic surfactant-based fire extinguishing agents Because synthetic surfactants are the main ingredient, fire water containing synthetic surfactant-based fire extinguishing agents has low surface tension and easily penetrates into fire targets such as burning materials and combustible materials. Furthermore, the foam formed by the impact of a collision covers the burning materials and combustible materials, blocking oxygen, improving the effectiveness of fire extinguishing, preventing re-ignition, and suppressing the spread of fire. The surfactant-based fire extinguishing agent only needs to be added to water at a low concentration, and fire water can be prepared by adding only the agent to water, allowing for relatively quick preparation of fire water.

[0009] However, when spraying water from the air above a fire using a helicopter or airplane, fire extinguishing water containing synthetic surfactant-based fire extinguishing agents is prone to generating bubbles due to air resistance, and is blown away by the updraft caused by the fire and the air currents generated by the flight of the aircraft itself, such as helicopters, flying boats, and airplanes, causing the water to disperse and disappear, making it difficult for the water to reach the desired point.

[0010] Furthermore, synthetic surfactants retain their surfactant activity for a certain period of time even when released into the environment, raising concerns about their toxicity to aquatic organisms.

[0011] (c) Water-absorbent polymer-based fire extinguishing agents The main component is a water-absorbing polymer, and when the water-absorbing polymer that has absorbed sufficient water comes into contact with burning or combustible materials, it has the effect of extinguishing the fire, preventing re-ignition, and suppressing the spread of fire.

[0012] However, firewater containing water-absorbent polymer-based extinguishing agents is transparent, making it impossible to identify the areas where the water has reached, so coloring agents are usually added. This makes preparation of the water cumbersome. Furthermore, water-absorbent polymer-based extinguishing agents have weaker penetration power than water containing surfactant-based extinguishing agents, making it difficult for the water to spread from the area where it has adhered to the surrounding area, and therefore, the water cannot be expected to have much effect in extinguishing the fire, preventing re-ignition, or suppressing the spread of the fire. Furthermore, water-absorbent polymers can cause people to slip when working on fire removal and on-site investigations after a fire.

[0013] In addition, water-absorbing polymers are difficult to biodegrade and accumulate in the environment, causing adverse effects on the ecosystem. It has been pointed out that (see Patent Document 1). [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-167357 Summary of the Invention [Problem to be solved by the invention]

[0015] Although excellent water-added fire extinguishing agents have been developed, each has its own issues, and since there are no extinguishing agents suitable for extinguishing large-scale forest fires, forest fire prevention has become a major social issue worldwide.In addition, fires caused by lithium-ion batteries, such as fires in electric vehicles (EVs), are said to be unable to be extinguished with conventional fire extinguishing agents.

[0016] The present invention has been made in view of the above problems, and an object of the present invention is to provide a water-added fire extinguishing agent that has high fire extinguishing performance and is easy to extinguish fires by spraying. [Means for solving the problem]

[0017] In order to solve the above problems, the present invention provides a water-addition type fire extinguishing agent containing, as a component of the fire extinguishing agent, a thermally depolymerizable polymer having a structure to which a water-soluble functional group has been added, an alkali metal salt thereof, or an alkaline earth metal salt thereof (Invention 1).

[0018] In the above invention (Invention 1), the thermally depolymerizable polymer having a structure to which a water-soluble functional group has been added preferably has a structure represented by the following chemical formula (Invention 2). [ka] (wherein X is hydrogen (H) or an alkyl group having 1 to 3 carbon atoms, and Y is COOH, SO3H, OCOOH, OSO3H, COO(CH2) m COOH, COO(CH2) m SO3H, benzene ring-COOH or benzene ring-SO3H, n is a positive integer of 5 to 27,000, and m is a positive integer of 1 to 5.

[0019] In the above invention (Invention 1), the alkali metal salt is preferably a potassium salt or a sodium salt (Invention 3).

[0020] In the above invention (Invention 1), the alkaline earth metal salt is preferably a Ca salt or an Mg salt (Invention 4).

[0021] In the above invention (Invention 1), the content of the thermally depolymerizable polymer having a structure to which a water-soluble functional group has been added, its alkali metal salt, or its alkaline earth metal salt in the water-addition type fire extinguishing agent is preferably 0.1 to 20% by weight (Invention 5).

[0022] In the above invention (Invention 1), it is preferable that the weight average molecular weight (MW) of the thermally depolymerizable polymer having a structure to which the water-soluble functional group is added, its alkali metal salt, or its alkaline earth metal salt in the water-addition type fire extinguishing agent is 1,000,000 or less (Invention 6).

[0023] In the above invention (Invention 6), the water-addition type fire extinguishing agent may contain two or more types of thermally depolymerizable polymers having a structure to which water-soluble functional groups have been added, their alkali metal salts, or their alkaline earth metal salts (Invention 7).

[0024] In the above inventions (Inventions 1 to 7), the thermally depolymerizable polymer having a structure to which a water-soluble functional group has been added is preferably poly(methacrylic acid) (Invention 8).

[0025] According to such inventions (Inventions 1 to 8), fires can be extinguished efficiently with a small amount of water discharged due to the effect of the thermally depolymerizable polymer having a structure to which a water-soluble functional group has been added, particularly poly(methacrylic acid). [Effects of the Invention]

[0026] The water-added fire extinguishing agent of the present invention, due to the effect of the thermally depolymerizable polymer having a structure with water-soluble functional groups, particularly poly(methacrylic acid), can efficiently extinguish fires with a smaller amount of water discharged than when water is used alone. This makes it possible to extinguish fires using limited water resources at the fire site and also reduces secondary damage caused by the discharged water. The water-added fire extinguishing agent of the present invention is effective against all fires for which water can be used, such as forest fires, residential fires, and electric vehicle (EV) fires. DETAILED DESCRIPTION OF THE INVENTION

[0027] The water-addition type fire extinguishing agent of the present invention will be described in detail based on the following embodiments.

[0028] [Water-added fire extinguishing agent] The water-added fire extinguishing agent of this embodiment contains, as a component of the fire extinguishing agent, a polymer having a structure in which a water-soluble functional group such as a carboxylic acid group or a sulfonic acid group is added to a thermally depolymerizable polymer, an alkali metal salt thereof, or an alkaline earth metal salt thereof (hereinafter, these may be referred to as polymer components).

[0029] The thermally depolymerizable polymer having a structure to which a water-soluble functional group has been added preferably has a structure represented by the following chemical formula: [ka] (In the formula, X is hydrogen (H) or an alkyl group having 1 to 3 carbon atoms; Y is COOH, SO3H, OCOOH, OSO3H, COO(CH2)mCOOH, COO(CH2)mSO3H, benzene ring-COOH, or benzene ring-SO3H; n is a positive integer of 4 to 27,000; and m is a positive integer of 1 to 5.)

[0030] As such a thermally depolymerizable polymer having a structure to which a water-soluble functional group is added, poly(methacrylic acid) can be suitably used.

[0031] As the alkali metal salt of the thermally depolymerizable polymer having a structure to which a water-soluble functional group is added, sodium (Na) salt, potassium (K) salt, etc. can be used, and as the alkaline earth metal salt, calcium (Ca) salt, magnesium (Mg) salt, etc. can be used.

[0032] These polymer components preferably have a weight-average molecular weight (MW) of 1,000,000 or less, particularly 100,000 or less. A weight-average molecular weight (MW) exceeding 1,000,000 not only reduces the solubility in water but also reduces the efficiency of polymer production. There is no particular lower limit for the weight-average molecular weight (MW) as long as it is in the form of a polymer, but it should be 500 or more, particularly 1,000 or more.

[0033] The water-added fire extinguishing agent of this embodiment is a water-added type, i.e., an aqueous solution, of the polymer component as described above. The content of the polymer component in this aqueous solution is preferably 0.1 to 20% by weight, particularly 0.1 to 10% by weight, and even more preferably 0.1 to 5% by weight. If the polymer component content is less than 0.1% by weight, sufficient fire extinguishing performance cannot be obtained, and a large amount (volume) of the aqueous solution of the fire extinguishing agent must be sprayed. On the other hand, if the polymer component content exceeds 20% by weight, not only will no further improvement in fire extinguishing performance be obtained, but the viscosity of the aqueous solution of the fire extinguishing agent increases, making it difficult to handle, which is undesirable.

[0034] In the water-addition type fire extinguisher of this embodiment, the thermally depolymerizable polymer having a structure to which a water-soluble functional group has been added, such as poly(methacrylic acid), its alkali metal salt, or its alkaline earth metal salt, its alkali metal salt, or its alkaline earth metal salt, may be used alone or in combination of two or more. When two or more types are used in combination, two or more aqueous solutions in which each is dissolved may be mixed, or two or more types of the thermally depolymerizable polymer having a structure to which a water-soluble functional group has been added, its alkali metal salt, or its alkaline earth metal salt may be dissolved in the same aqueous solvent.

[0035] [Fire extinguishing method using water-added fire extinguishing agent] The water-added fire extinguishing agent described above may be supplied directly to the flame during fire extinguishing, but it is preferable to spray it onto the flame in the form of a mist or droplets in terms of the extinguishing efficiency per unit volume of the water-added fire extinguishing agent. For example, in the case of widespread fires such as forest fires, it may be sprayed from the air using a helicopter, drone, or airplane. It can also be made into a spray can or spray gun to serve as a simple auxiliary fire extinguishing device for home use. It can also be used as an extinguishing agent in a regular fire extinguisher, and can be used for general fires, fires in electric vehicles (EVs), and the like.

[0036] The water-added fire extinguishing agent of this embodiment exhibits fire extinguishing performance approximately 10 times or more times greater per unit volume than water alone, allowing for efficient fire extinguishing with a small amount of water sprayed. This allows for effective fire extinguishing using limited water resources at the fire site, and also prevents secondary damage caused by sprayed water. This makes the agent particularly suitable as a fire extinguishing agent for large-scale fires such as forest fires and widespread fires. It also makes it possible to extinguish fires caused by lithium-ion batteries, such as fires in electric vehicles (EVs).

[0037] The water-addition type fire extinguishing agent of the present invention has been described above. However, the present invention is not particularly limited in its application form, as long as it utilizes an aqueous solution containing a thermally depolymerizable polymer having a structure with a water-soluble functional group, or an alkali metal salt or alkaline earth metal salt thereof, as the active ingredient of the fire extinguishing agent. For example, a non-flammable or flame-retardant fabric cloth may be wetted with the water-addition type fire extinguishing agent of the present invention, and the cloth may be used to cover the flame and extinguish the fire. Depending on the intended use, the water-addition type fire extinguishing agent of the present invention may also contain various additives, such as colorants for forest fire extinguishing agents, non-fluorine-containing surfactants for foam fire extinguishing agents, fire extinguishing agents other than those of the present invention, foam retention improvers, antifoaming agents, pH adjusters, neutralizers, thickeners, and rust inhibitors. However, if the fire extinguishing agent is not intended to be a foam fire extinguishing agent, it is preferable not to contain non-fluorine-containing surfactants or foam retention improvers. [Example]

[0038] The present invention will be described in more detail based on the following specific examples, but the present invention is not limited to the following examples.

[0039] (Fire extinguishing test) The fire extinguishing test was carried out in the following manner. An assembled mini fire pit, Tetra ST-941 (manufactured by Shin Fuji Burner Co., Ltd.), was used as the combustion platform, and one pellet (12g) of Aomori Mirai Pellets (manufactured by Takahashi HD Co., Ltd.) was placed in it as the combustion material. The combustion material was ignited with a gas burner, and when the flame height of the combustion material exceeded 10cm, a water-added fire extinguishing agent was sprayed using a spray gun capable of spraying approximately 0.7mL of liquid in one spray, and the amount of fire extinguishing agent required to completely extinguish the flame was measured. It was also confirmed whether the flame would re-ignite during the extinguishing process.

[0040] (Examples 1 to 3, Comparative Example 1) The above-described fire extinguishing tests were conducted using a water-added fire extinguishing agent (Example 1) prepared by dissolving 1 wt % of poly(methacrylic acid) as solids into an aqueous solution, a water-added fire extinguishing agent (Example 2) prepared by dissolving 1 wt % of poly(methacrylic acid) potassium salt as solids into an aqueous solution, and a water-added fire extinguishing agent (Example 3) prepared by dissolving 1 wt % of poly(methacrylic acid) sodium salt as solids into an aqueous solution. The number of sprays required to extinguish the fire was measured, the amount of extinguishing agent required was calculated, and the occurrence of re-flaming was confirmed. The results are shown in Table 1, along with the content of the polymer component of the fire extinguishing agent and the weight-average molecular weight of the polymer component used. For comparison, a similar fire extinguishing test was conducted using water (Comparative Example 1). The number of sprays required to extinguish the fire was measured, the amount of extinguishing agent required was calculated, and the occurrence of re-flaming was confirmed. The results are also shown in Table 1.

[0041] [Table 1]

[0042] As is clear from Table 1, the extinguishing agents of Examples 1 to 3 required less than 1 / 10 of the amount of extinguishing water required to extinguish the fire compared to Comparative Example 1, which used water, and it was confirmed that they exhibited excellent fire extinguishing ability without causing any re-flame.

[0043] (Example 4, Comparative Example 2) A lithium-ion battery was ignited in an overcharge test, and a fire extinguishing test was conducted while the flame was still burning. The overcharge test on the lithium-ion battery used a 3.4V, 3.2Ah laminated lithium-ion cell, which was overcharged at 15V, 9.6A (3C). After about 19 minutes, a violent explosion and fire occurred, and the flame continued.

[0044] While this flame was continuing, a water-added fire extinguishing agent (Example 4) was used, which was prepared by dissolving 4% by weight of poly(methacrylic acid) potassium salt as solid content into an aqueous solution. The number of sprays with a spray gun until the fire was extinguished was measured, the amount of fire extinguishing agent required was calculated, and the presence or absence of re-flaming was confirmed. The results are shown in Table 2, along with the content of the polymer component of the fire extinguishing agent and the weight-average molecular weight of the polymer component used. For comparison, a similar fire extinguishing test was conducted using water (Comparative Example 2), and the number of sprays with a spray gun until the fire was extinguished was measured, the amount of fire extinguishing agent required was calculated, and the presence or absence of re-flaming was confirmed. The results are also shown in Table 2.

[0045] [Table 2]

[0046] As is clear from Table 2, the amount of water required to extinguish the fire with the fire extinguishing agent of Example 4 was 1 / 10 or less of that required with Comparative Example 2, which used water, and there was no re-flame, demonstrating excellent fire extinguishing ability.

Claims

1. The fire extinguishing agent contains a depolymerizable alkali metal salt as a component, the depolymerizable alkali metal salt includes at least one of a potassium poly(methacrylic acid) salt and a sodium poly(methacrylic acid) salt; A water-addition type fire extinguishing agent, wherein the content of the alkali metal salt in the water-addition type fire extinguishing agent is 1 to 20% by weight.

2. 2. The water-added fire extinguishing agent according to claim 1, wherein the weight average molecular weight (MW) of the depolymerizable alkali metal salt in the water-added fire extinguishing agent is 1,000,000 or less.

3. A water-additive fire extinguishing agent as described in claim 1 or 2, wherein the depolymerizable alkali metal salt includes poly(methacrylic acid) potassium salt and poly(methacrylic acid) sodium salt.

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