Water-inclusive fire extinguishing agent

Abstract

This water-inclusive fire extinguishing agent contains, as a component of a fire extinguishing agent, 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. It is preferable that the thermally depolymerizable polymer having a structure to which a water-soluble functional group is imparted has a structure that is represented by a specific chemical formula. In the case of the alkali metal salt, a sodium (Na) salt, a potassium (K) salt, or the like can be used. In the case of the alkaline earth metal salt, a calcium (Ca) salt, a magnesium (Mg) salt, or the like can be used. Such a water-inclusive fire extinguishing agent has high fire extinguishing performance, and can easily extinguish a fire by being sprayed.

Description

Water-added fire extinguishing agent

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

[0002] Fires are typically extinguished using water (firewater). Water has a high specific heat and heat of vaporization, providing 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 and tends to fall and wash away rather than remaining on the surface of burning or combustible materials. It is said that only about 10% of the water used in firefighting efforts actually contributes to the extinguishing of the fire. Therefore, firefighting requires continuous spraying over an extended period of time, necessitating a large amount of water. Furthermore, because 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. These typically contain ammonium phosphate as the main ingredient. When fire extinguishing water containing a phosphate inorganic compound fire extinguishing agent is sprayed on a fire area, the ammonium phosphate decomposes due to heating, and absorbs heat from the surrounding area through its endothermic action. It also generates non-flammable gases, forming a gas layer around the fire, blocking oxygen. At higher temperatures, it transforms into a molten glass-like substance, covering the burning surface and blocking oxygen. Because fire extinguishing water containing a phosphate inorganic compound fire extinguishing agent is colorless, adding a coloring agent is essential for 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 tend to form powder. When stored for long periods, the components precipitate and form lumps, 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 of the soil where it is applied.

[0008] (b) Synthetic Surfactant-Based Fire Extinguishing Agents Because synthetic surfactants are the main component, fire extinguishing 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, foam formed by impact or other factors covers the burning materials and combustible materials, blocking oxygen, thereby improving the effectiveness of fire extinguishing, preventing re-ignition, and suppressing the spread of fire. Because the surfactant-based fire extinguishing agent needs to be added to water in a low concentration, and fire extinguishing water can be prepared by adding only the agent to water, fire extinguishing water can be prepared relatively quickly.

[0009] However, when water is sprayed from the air above a fire using a helicopter or airplane, fire extinguishing water containing a synthetic surfactant-based fire extinguishing agent 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 These agents are mainly composed of water-absorbent polymers, and when the water-absorbent polymers that have absorbed sufficient water are brought into contact with burning or combustible materials, they are effective in extinguishing the fire, preventing re-ignition, and suppressing the spread of the 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 colorants are usually added. This makes preparation of the firewater cumbersome. Furthermore, firewater containing water-absorbent polymer-based extinguishing agents has weaker penetration power than firewater 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, it cannot be expected to be very effective in extinguishing the fire, preventing re-ignition, or suppressing the spread of the fire. Furthermore, water-absorbent polymers can cause people to slip during post-fire fire cleanup, on-site investigation, and other tasks.

[0013] In addition, it has been pointed out that water-absorbent polymers are difficult to biodegrade, accumulate in the environment, and have adverse effects on ecosystems (see Patent Document 1).

[0014] JP 2011-167357 A

[0015] Although excellent water-added fire extinguishing agents have been developed, each has its own issues, and since there is no fire extinguishing agent 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.

[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). (wherein X is hydrogen (H) or an alkyl group having 1 to 3 carbon atoms, and Y is COOH, SO ３ H, OCOOH, OSO ３ H, COO (CH2) ｍCOOH, COO(CH2) ｍ SO ３ H, benzene ring-COOH or benzene ring-SO ３ H, n is a positive integer from 5 to 27,000, and m is a positive integer from 1 to 5.

[0019] In the above invention (Invention 1), the alkali metal salt is preferably a K salt or a Na 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 extinguisher 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 a water-soluble functional group is added, its alkali metal salt, or its alkaline earth metal salt in the water-addition type fire extinguisher 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 a water-soluble functional group has been added, alkali metal salts thereof, or alkaline earth metal salts thereof (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 these 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).

[0026] The water-addition type 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 to prevent secondary damage caused by the discharged water. Such a water-addition type 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.

[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 the present 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: (wherein X is hydrogen (H) or an alkyl group having 1 to 3 carbon atoms, and Y is COOH, SO ３ H, OCOOH, OSO ３ H, COO(CH2)mCOOH, COO(CH2)mSO ３ H, benzene ring-COOH or benzene ring-SO ３ H, n is a positive integer from 4 to 27,000, and m is a positive integer from 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, a sodium (Na) salt, a potassium (K) salt, etc. can be used, and as the alkaline earth metal salt, a calcium (Ca) salt, a 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 production efficiency of the polymer. 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 is sufficient if it is 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 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 will increase, making it difficult to handle, which is undesirable.

[0034] In the water-addition type fire extinguishing agent 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-Additive Fire Extinguishing Agent] The water-additive 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-additive fire extinguishing agent. For example, in the case of widespread fires such as forest fires, the agent may be sprayed from the sky using a helicopter, drone, or aircraft. In addition, the agent may be made into a spray can or spray gun to serve as a simple auxiliary fire extinguishing device for home use. The agent may also be used as a fire extinguishing agent in a normal fire extinguisher, and may 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 furthermore, it can prevent secondary damage caused by the sprayed water. This makes it 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 use form, as long as it utilizes an aqueous solution containing a thermally depolymerizable polymer having a structure with a water-soluble functional group attached thereto, or an alkali metal salt or alkaline earth metal salt thereof, as the active ingredient of the fire extinguishing agent. For example, a fire may be extinguished by wetting a non-flammable or flame-retardant fabric cloth with the water-addition type fire extinguishing agent of the present invention and covering the cloth with the flame. 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, neutralizing agents, 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.

[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. A mini fire stand Tetra ST-941 (manufactured by Shin Fuji Burner Co., Ltd.) was assembled as a combustion stand, and one pellet (12 g) of Aomori Mirai Pellets (manufactured by Takahashi HD Co., Ltd.) was placed in it as a combustion material. The combustion material was ignited with a gas burner, and when the height of the flame of the combustion material exceeded 10 cm, a water-added fire extinguishing agent was sprayed with a spray gun capable of spraying about 0.7 mL of liquid in one spray, and the amount of fire extinguishing agent required until the flame was completely extinguished was measured. It was also confirmed whether the flame re-flamed during the extinguishing process.

[0040] (Examples 1 to 3, Comparative Example 1) The above-described fire extinguishing tests were carried out using a water-added fire extinguishing agent (Example 1) prepared by dissolving 1 wt % of poly(methacrylic acid) as solids to form an aqueous solution, a water-added fire extinguishing agent (Example 2) prepared by dissolving 1 wt % of poly(methacrylic acid) potassium salt as solids to form 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 to form an aqueous solution, respectively. The number of sprays with a spray gun until the fire was extinguished was measured, the amount of extinguishing agent required was calculated, and the presence or absence of re-flaming was confirmed. The results are shown in Table 1 together 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 carried out using water (Comparative Example 1), and the number of sprays with a spray gun until the fire was extinguished was measured, the amount of extinguishing agent required was calculated, and the presence or absence of re-flaming was confirmed. The results are also shown in Table 1.

[0041]

[0042] As is clear from Table 1, the extinguishing agents of Examples 1 to 3 required 1 / 10 or less of the amount of 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 carried out in the state where the flame was emitted. In the overcharge test with the lithium ion battery, a 3.4 V, 3.2 Ah laminated lithium ion cell was used, and the battery was overcharged at 15 V, 9.6 A (3C). As a result, a violent explosion and fire occurred after about 19 minutes, and the flame continued.

[0044] While this flame was continuing, a water-added fire extinguishing agent (Example 4) was used, which was prepared as an aqueous solution by dissolving 4% by weight of poly(methacrylic acid) potassium salt as solids. 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]

[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. A water-added 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, its alkali metal salt, or its alkaline earth metal salt.

2. The water-addition type fire extinguishing agent according to claim 1, wherein the thermally depolymerizable polymer having a structure to which a water-soluble functional group has been added has a structure represented by the following chemical formula: (wherein X is hydrogen (H) or an alkyl group having 1 to 3 carbon atoms, and Y is COOH, SO ３ H, OCOOH, OSO ３ H, COO (CH2) ｍ COOH, COO(CH2) ｍ SO ３ H, benzene ring-COOH or benzene ring-SO ３ H, n is a positive integer from 5 to 27,000, and m is a positive integer from 1 to 5.

3. The water-addition type fire extinguishing agent according to claim 1, wherein the alkali metal salt is a potassium salt or a sodium salt.

4. The water-added fire extinguishing agent according to claim 1, wherein the alkaline earth metal salt is a Ca salt or a Mg salt.

5. The water-addition type fire extinguishing agent according to claim 1, wherein 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 0.1 to 20% by weight.

6. A water-added fire extinguishing agent according to claim 1, wherein the weight-average molecular weight (MW) of the thermally depolymerizable polymer having a structure to which a water-soluble functional group is added, its alkali metal salt, or its alkaline earth metal salt in the water-added fire extinguishing agent is 1,000,000 or less.

7. The water-addition type fire extinguishing agent according to claim 1, which contains 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.

8. A water-added fire extinguishing agent according to any one of claims 1 to 7, wherein the thermally depolymerizable polymer having a structure to which a water-soluble functional group has been added is poly(methacrylic acid).

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