Lithium battery two-component fire extinguishing agent and fire extinguishing composition adopted by lithium battery two-component fire extinguishing agent

Abstract

The invention provides a lithium battery two-component fire extinguishing agent and a fire extinguishing composition adopted by the lithium battery two-component fire extinguishing agent. The fire extinguishing composition provided by the invention is prepared from the following raw materials in parts by weight: 1 to 2 parts of guar gum, 2 to 3 parts of polyvinyl alcohol, 3 to 4 parts of acrylamide, 2 to 3 parts of methacrylic acid, 1.5 to 2 parts of a framework supporting material, 1.3 to 2.5 parts of a cross-linking agent and 0.2 to 0.3 part of an initiator. The fire extinguishing composition provided by the invention has a stable three-dimensional structure, evaporation of water in the structure can adsorb a large amount of heat, and the heat is attached to the surface of a battery to form carbon deposition along with reduction of the evaporation volume of the water, so that the effects of isolating air and obstructing combustion are achieved, the flame retardance can be improved, and re-combustion can be prevented; the high polymer consumes combustible gas in the process of burning and heating to form carbon, so that the burning reaction is prevented. The fire extinguishing hydrogel or the double-component fire extinguishing agent comprising the water-based component and the hydrogel component can be prepared from the water-based fire extinguishing agent, and the water-based fire extinguishing agent and the hydrogel component have multiple synergistic fire extinguishing effects on the lithium battery, so that efficient fire extinguishing of the lithium battery is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of functional materials, and in particular to a two-component fire extinguishing agent for lithium batteries and a fire extinguishing composition used therein. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density, long cycle life, and pollution-free operation, and are widely used in fields such as power storage and electric vehicles. However, under conditions of abuse, lithium-ion batteries are very prone to thermal runaway, releasing large amounts of heat and harmful flammable gases. Electric vehicle fires caused by battery thermal runaway have become a thorny problem facing fire departments. In recent years, lithium-ion battery fire accidents have occurred frequently, and the consequences of fire accidents are also extremely serious. Therefore, the development of fast and efficient fire extinguishing agents is of great significance to extinguish lithium battery fires and inhibit the development of thermal runaway.

[0003] At present, the research on fire extinguishing technology for lithium-ion battery fires mainly focuses on perfluorohexanone, liquid nitrogen, gas fire extinguishing agents and water-based fire extinguishing agents. A comparative analysis of the inhibitory effects of carbon dioxide and fine water mist on ternary lithium battery fires found that the battery reignited after being acted upon by carbon dioxide, while the battery did not reignite in the test using fine water mist, and the fine water mist could significantly reduce the battery temperature; although perfluorohexanone can extinguish fires quickly compared to fine water mist, as the concentration of the fire extinguishing agent decreases, the battery subsequently reignites, and the cooling effect of fine water mist is better than that of perfluorohexanone, but it has the disadvantage of large water consumption, making it difficult to carry out practical applications. Gas fire extinguishing agents can effectively suppress thermal runaway of lithium-ion batteries in confined spaces, but are not suitable for extinguishing fires in open spaces such as electric vehicle fires. Water-based fire extinguishing agents have the characteristics of high specific heat capacity and strong isolation, and have more efficient fire extinguishing performance, but their water retention and covering capabilities are very limited.

[0004] The Chinese patent with the announcement number CN111978489B provides a hydrogel for temporarily plugging an oil pipeline, wherein the hydrogel is obtained by grafting, copolymerizing and chemically crosslinking reactants, wherein the reactants include gelatin, water, amide monomers, acrylic monomers, neutralizers, initiators, two-component crosslinkers, thickeners and preservatives, wherein the mass percentages of the various substances in the reactants are: two-component crosslinkers 0.5%-0.8%, initiators 0.1-0.2%; gelatin 1%-2%, amide monomers 2%-3%, acrylic monomers 1.5%-2%, thickeners 0.2%-0.5%, neutralizers 1.5%-2%, preservatives 0.1%-0.3%, and the balance is water. In the patent document, a two-crosslinker is used for chemical crosslinking during the reaction process to make the product structure more stable, and then a surfactant is added to enhance the performance of the product, and finally a high-viscosity and high-strength hydrogel is generated.

[0005] The hydrogels obtained by the above prior art still have poor fire extinguishing and cooling effects. At the same time, the obtained hydrogels have high viscosity and poor fluidity, and cannot effectively cover the battery to isolate and extinguish fires and interrupt the battery thermal runaway to release gas and intensify combustion. Summary of the invention

[0006] The first purpose of the present invention is to overcome the technical problems in the prior art such as poor fire extinguishing and cooling effect, inability to effectively cover the battery to isolate the fire and interrupt the battery thermal runaway to release gas to intensify combustion, and the like, and provide a fire extinguishing composition, wherein the raw materials include, by weight: 1-2 parts of guar gum, 2-3 parts of polyvinyl alcohol, 3-4 parts of acrylamide, 2-3 parts of methacrylic acid, 1.5-2 parts of skeleton support material, 1.3-2.5 parts of cross-linking agent, and 0.2-0.3 parts of initiator.

[0007] The fire extinguishing composition provided by the present invention uses guar gum, acrylamide and polyvinyl alcohol to react under the action of a crosslinking agent and an initiator to form a polymer material with a three-dimensional spatial structure, and by adding a skeleton support material, the three-dimensional structure of the polymer material is more stable, the flame retardancy is improved, and the re-ignition is prevented. The copolymerization of methacrylic acid can make the product tougher and more encapsulating after dehydration, and the encapsulation layer is not easy to crack after the water evaporates, thereby increasing the fire extinguishing efficiency and reducing the probability of re-ignition. The fire extinguishing composition provided by the present invention has a structure in which the evaporation of water can absorb a large amount of heat, and as the volume of water evaporates, it adheres to the surface of the battery to form carbon deposits, thereby achieving the effect of isolating air and blocking combustion; at the same time, the polymer consumes combustible gas in the process of burning and heating to form carbon, thereby preventing the combustion reaction from proceeding.

[0008] In some embodiments of the present invention, the skeleton support material is selected from nano-silicon dioxide.

[0009] The present invention adopts the above-mentioned skeleton support material to effectively improve the stability of the three-dimensional structure of the fire extinguishing composition, thereby structurally providing the fire extinguishing composition with stable and efficient fire extinguishing performance, especially late fire extinguishing performance, and avoiding the accumulation of combustibles during the fire extinguishing process, which may destroy the three-dimensional structure of the fire extinguishing composition and cause incomplete fire extinguishing, re-ignition, etc.

[0010] In some embodiments of the present invention, the raw material further comprises 2-3 wt % of a neutralizing agent.

[0011] In some embodiments of the present invention, the neutralizing agent is selected from at least one of sodium hydroxide and bicarbonate.

[0012] The present invention adopts a neutralizing agent, especially a mild bicarbonate as a neutralizing agent, such as at least one of sodium bicarbonate, potassium bicarbonate, calcium bicarbonate and ammonium bicarbonate; the neutralizing agent is used to adjust the pH of the fire extinguishing composition, and can achieve slow and accurate pH adjustment to make the system neutral, thereby avoiding corrosion to the fire extinguishing object, and ensuring the safe use of the fire extinguishing composition, thereby avoiding harm to users due to the pH.

[0013] In some embodiments of the present invention, the raw materials further include 0.1-0.3 parts of preservatives by weight; the present invention uses preservatives to effectively extend the shelf life of the fire extinguishing composition.

[0014] In some embodiments of the present invention, the preservative is selected from at least one of potassium sorbate and sodium benzoate.

[0015] In some embodiments of the present invention, the cross-linking agent is selected from at least one of N-hydroxymethyl acrylamide and ethylene glycol dimethacrylate.

[0016] The second object of the present invention is to provide a method for preparing the fire extinguishing composition, comprising: Step 1: mixing and dissolving guar gum, polyvinyl alcohol, acrylamide and a skeleton support material to obtain a first solution; Step 2: dissolving methacrylic acid to obtain a second solution; Step 3: pouring the second solution into the first solution, mixing evenly, adding a crosslinking agent and an initiator, and performing a graft copolymerization reaction to obtain a fire extinguishing composition; In some embodiments of the present invention, in step 1, the guar gum, polyvinyl alcohol, acrylamide and skeleton support material are dissolved at 50-70° C. to obtain the first solution.

[0017] In some embodiments of the present invention, in step 2, the methacrylic acid is dissolved at 30-50°C.

[0018] In some embodiments of the present invention, in step 2, after the methacrylic acid is completely dissolved, a neutralizing agent is added for neutralization, and the degree of neutralization is 80-90%, thereby obtaining the second solution.

[0019] In some embodiments of the present invention, in step 3, the graft copolymerization reaction is carried out at 70-80° C. for 1 hour.

[0020] In some embodiments of the present invention, in step 3, after the graft copolymerization reaction is carried out for 1 hour, a preservative is added to obtain the fire extinguishing composition.

[0021] The fire extinguishing composition obtained by the preparation method provided by the present invention is in a gel state and has a stable three-dimensional structure, which structurally provides the fire extinguishing composition with stable and efficient fire extinguishing performance.

[0022] The third object of the present invention is to provide application of the fire extinguishing composition or the fire extinguishing composition obtained by the preparation method in the field of batteries, and preferably the battery is selected from lithium batteries.

[0023] The fourth object of the present invention is to provide a fire extinguishing hydrogel, the raw materials of which include 10-20wt% of the fire extinguishing composition or the fire extinguishing composition obtained by the preparation method.

[0024] The fire extinguishing hydrogel provided by the present invention is insoluble in water but its molecular structure can absorb a large amount of water. When used in the process of extinguishing a lithium ion battery, the evaporation of water in its structure can absorb a large amount of heat, effectively reducing the temperature of the battery surface. At the same time, the fire extinguishing hydrogel provided by the present invention has the characteristics of strong water retention and high adhesion. During the fire extinguishing process, the volume of the fire extinguishing composition is reduced while it can adhere to the battery surface to form carbon deposits, thereby achieving the effect of isolating air and blocking combustion, and preventing re-ignition. During the synthesis process, sulfonic acid groups are introduced into both the raw materials and the copolymer products. The sulfonyl free radicals generated by the cracking after being heated are very active and can be quickly combined with the hydroxyl free radicals released during the battery combustion process, thereby terminating the chain reaction, thereby achieving the multiple synergistic fire extinguishing effects of the fire extinguishing hydrogel provided by the present invention on the lithium battery, and realizing efficient fire extinguishing of the lithium battery.

[0025] The fifth object of the present invention is to provide a two-component fire extinguishing agent, comprising 30-40wt% of a water-based fire extinguishing component and 60-70wt% of the fire extinguishing hydrogel; the water-based fire extinguishing agent and the fire extinguishing hydrogel are stored separately.

[0026] In some embodiments of the present invention, the water-based fire extinguishing agent includes 1-2 wt % of dodecyl phosphate monoester.

[0027] The two-component fire extinguishing agent provided by the present invention includes a water-based component and a hydrogel component, and is used for lithium-ion battery fire extinguishing. It has the effect of rapid cooling of the water-based fire extinguishing agent, and at the same time, the hydrogel component solves the shortcomings of the water-based component that can only touch the external surface of the battery, and has limited water retention and covering capabilities. In the early stage of use of the two-component fire extinguishing agent, the water-based component can significantly reduce the temperature of the battery and efficiently cool the battery; in the later stage of use, the stable three-dimensional structure of the hydrogel component can avoid problems such as uncontrolled high temperature of the battery and the release of combustible gas and re-ignition. The two-component fire extinguishing agent provided by the present invention has multiple synergistic fire extinguishing effects on lithium batteries, further realizing efficient fire extinguishing of lithium batteries.

[0028] The fire extinguishing composition obtained by the preparation method provided by the present invention comprises a water-based component and a hydrogel component, wherein the main function of the water-based component is to reduce the temperature of the battery by evaporation of water, thereby reducing the subsequent reactions caused by thermal runaway of the battery. The hydrogel component is in a gel-like state, and the free water and bound water in its molecular structure further reduce the temperature. At the same time, after the water evaporates, the hydrogel covers the surface of the battery to play the role of isolation and cooling. The fire extinguishing composition plays a multiple fire extinguishing effect in the fire extinguishing process. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The embodiments of the present invention partially provide a two-component fire extinguishing agent for lithium batteries, comprising 60-70wt% of a hydrogel component and 30-40wt% of an aqueous component; the two components are stored separately.

[0031] Among them, the raw materials of the hydrogel component include, by weight: 1-2 parts of guar gum, 2-3 parts of polyvinyl alcohol, 3-4 parts of acrylamide, 2-3 parts of methacrylic acid, 2-3 parts of neutralizer, 1.5-2 parts of skeleton support material, 1-2 parts of cross-linking agent N-hydroxymethyl acrylamide, 0.3-0.5 parts of cross-linking agent ethylene glycol dimethacrylate, 0.2-0.3 parts of initiator, 0.1-0.3 parts of preservative and water; the sum of the weight parts of each substance is 100 parts, that is, the above raw materials by weight can also be expressed as mass percentage, which is explained below in terms of weight percentage.

[0032] The preparation process of the hydrogel component is as follows: Step A: Preparation of an aqueous component: stirring and dissolving 1%-2% by mass of dodecyl phosphate monoester at 40-60° C. to obtain an aqueous component; Step B: Preparation of hydrogel components: Step 1: dissolving and stirring 1%-2% guar gum, 2%-3% polyvinyl alcohol, 3%-4% acrylamide, and 1.5%-2% skeleton support material at 50-70° C. to obtain a first solution; Step 2: Dissolve 2%-3% methacrylic acid at 30-50°C and stir, and add a neutralizing agent for neutralization, with a neutralization degree of 80-90%, to obtain a second solution; Step 3: Pour the second solution into the first solution, stir and mix, add 0.5%-0.8% of a crosslinking agent and 0.2-0.3% of an initiator, and carry out a graft copolymerization reaction at 70-80° C.; after reacting for 1 hour, add 0.1%-0.3% of a preservative to obtain a hydrogel component; Step C: Cooling the water-based component and the hydrogel component to room temperature respectively to obtain the two-component fire extinguishing agent.

[0033] Among them, the skeleton support material is selected from nano-silica; the cross-linking agent is selected from N-hydroxymethyl acrylamide and ethylene glycol dimethacrylate; the neutralizing agent is selected from bicarbonate (such as sodium bicarbonate, potassium bicarbonate, calcium bicarbonate and ammonium bicarbonate), sodium hydroxide; the preservative is selected from potassium sorbate and sodium benzoate.

[0034] The two-component fire extinguishing agent provided by the present invention is used by mixing 30-40wt% of the water-based component with 60-70wt% of the hydrogel component, and can be used for extinguishing fires of batteries such as lithium batteries, and has excellent fire extinguishing performance.

[0035] All chemical raw materials involved in the present invention are chemically pure and purchased from Sinopharm Chemical Reagent Co., Ltd.

[0036] Wherein, polyvinyl alcohol was purchased from McLean Biochemical Technology Co., Ltd., with a degree of alcoholysis of 88-89 mol% and a viscosity of 3.2-3.8 mPa·s.

[0037] Example 1 This embodiment 1 provides a two-component fire extinguishing agent, including a water-based component and a hydrogel component.

[0038] The water-based component is composed of 20 g of dodecyl phosphate monoester and 980 g of water, and its preparation method is: stirring and dissolving dodecyl phosphate monoester at 40-60° C. to obtain the water-based component.

[0039] Among them, the raw material composition of the hydrogel component is: 10g guar gum, 20g polyvinyl alcohol, 30g acrylamide, 20g methacrylic acid, 20g neutralizer sodium bicarbonate, 15g skeleton support material, 10g cross-linking agent N-hydroxymethyl acrylamide, 3g cross-linking agent ethylene glycol dimethacrylate, 2g initiator ammonium persulfate, 1g preservative sodium benzoate, and 872g water.

[0040] The preparation method of the hydrogel component is: Step 1: dissolving guar gum, polyvinyl alcohol, acrylamide and a skeleton support material at 50-70° C. and stirring to obtain a first solution; Step 2: dissolving methacrylic acid at 30-50° C. with stirring, and adding a neutralizing agent for neutralization, with a neutralization degree of 80-90%, to obtain a second solution; Step 3: Pour the second solution into the first solution, stir and mix, add a crosslinking agent and an initiator, and carry out a graft copolymerization reaction at 70-80° C.; after reacting for 1 hour, add a preservative to obtain the hydrogel component.

[0041] The two-component fire extinguishing agent provided in this embodiment, wherein the water-based component and the hydrogel component are stored separately, for example, can be stored in two cavities of a fire extinguishing tank. When it is needed, through specific operations, 40wt% of the water-based component and 60wt% of the hydrogel component are mixed, and can be used to extinguish a fire of a lithium battery.

[0042] Example 2 This embodiment provides a fire extinguishing agent, which is basically the same as Embodiment 1, except that the water-based component is not added, that is, the hydrogel component (that is, the fire extinguishing hydrogel provided by the present invention) is used as the fire extinguishing agent.

[0043] Comparative Example 1 This comparative example provides a two-component fire extinguishing agent, which is basically the same as Example 1, except that no skeleton support material is added to the raw materials of the hydrogel component, that is, the nano-silicon dioxide is replaced by an equal mass of water.

[0044] Comparative Example 2 This comparative example provides a two-component fire extinguishing agent, which is basically the same as Example 1, except that polyvinyl alcohol is not added to the raw materials of the hydrogel component, that is, it is replaced by an equal mass of water.

[0045] Comparative Example 3 This comparative example provides a fire extinguishing agent, which is basically the same as Example 1, except that the hydrogel component is not added, that is, the water-based component is used as the fire extinguishing agent.

[0046] Test example Test object: the two-component fire extinguishing agent or fire extinguishing hydrogel obtained in each embodiment and comparative example.

[0047] Test method: In order to verify the performance of the fire extinguishing agent, a cylindrical lithium-ion-graphite battery with a diameter of 18mm and a height of 65mm was selected for thermal runaway fire extinguishing experiment. The battery capacity was 3Ah and the nominal voltage was 4.2V. First, the battery was fully charged and discharged several times with a charging device, and then the battery was charged to 100% state of charge for the experiment. During the test, four batteries were placed side by side close together. The battery on the far left of the thermal runaway was used to observe the impact of thermal runaway on the two adjacent batteries. The fire extinguishing performance of the blank group, fine water mist, perfluorohexanone and prepared hydrogel were compared in the experiment. During the experiment, once the battery safety valve was observed to be open, the heating rod was turned off and the battery heating was stopped. When the battery subsequently had a jet fire, the fire extinguishing agent was immediately released to extinguish the battery fire.

[0048] Test results: The data obtained during the test are shown in the following table.

[0049] Table 1 Fire extinguishing data of different fire extinguishing agents

[0050] As can be seen from Table 1, the fire-extinguishing hydrogel two-component fire extinguishing agent provided by the present invention can complete the fire extinguishing of lithium batteries in a shorter time. After the fire is extinguished, it will not reignite and can also block the impact of the battery on the surrounding battery packs after it loses control. From the experimental results of Examples 1-2 and Comparative Example 3, it can be seen that the main fire extinguishing component of the two-component fire extinguishing agent is the hydrogel component, and the main function of the water-based component is to reduce the temperature of the battery surface. After the hydrogel component is missing (Comparative Example 3), the battery re-ignites and also causes the surrounding batteries to lose control. From the experimental results of Example 1 and Comparative Example 1, it is found that although the fire extinguishing agent lacking the skeleton support material can play a role in extinguishing fire, the insulation and cooling effect of the hydrogel covering the battery surface after the water evaporates due to the unstable structure is reduced, which leads to an increase in temperature. From the results of Example 1 and Comparative Example 2, it can be seen that the addition of polyvinyl alcohol helps to improve the fire extinguishing efficiency and reduce the maximum temperature of the thermal runaway battery after extinguishing the fire.

[0051] In other embodiments of the present invention, when preparing the fire extinguishing composition, it is not necessary to add a neutralizing agent and / or a mildew inhibitor, and they can be replaced with an equal amount of water. Among them, the neutralizing agent is used to adjust the pH of the fire extinguishing composition to prevent it from corroding the fire extinguishing object, and to ensure the safe use of the fire extinguishing composition to avoid harm to the user due to the pH. Therefore, even if the embodiments of the present invention do not provide relevant embodiments, those skilled in the art can also expect that the obtained hydrogel fire extinguishing agent can also achieve stable fire extinguishing performance without adding a neutralizing agent. Similarly, even if the embodiments of the present invention do not provide relevant embodiments without adding a mildew inhibitor, those skilled in the art can also expect that the obtained hydrogel fire extinguishing agent can also achieve stable fire extinguishing performance without adding a mildew inhibitor.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fire extinguishing composition, characterized in that: The raw materials include, by weight: 1-2 parts of guar gum, 2-3 parts of polyvinyl alcohol, 3-4 parts of acrylamide, 2-3 parts of methacrylic acid, 1.5-2 parts of skeleton support material, 1.3-2.5 parts of crosslinking agent, and 0.2-0.3 parts of initiator.

2. The fire extinguishing composition according to claim 1, characterized in that: The skeleton support material is selected from nano-silicon dioxide.

3. The fire extinguishing composition according to claim 1 or 2, characterized in that: The raw material further comprises 2-3 parts of a neutralizing agent by weight; Preferably, the neutralizing agent is selected from at least one of sodium hydroxide and bicarbonate; Preferably, the bicarbonate is selected from at least one of potassium bicarbonate, sodium bicarbonate, calcium bicarbonate and ammonium bicarbonate.

4. The fire extinguishing composition according to any one of claims 1 to 3, characterized in that: The raw material further comprises 0.1-0.3 parts by weight of a preservative; Preferably, the preservative is selected from at least one of potassium sorbate and sodium benzoate.

5. The fire extinguishing composition according to any one of claims 1 to 4, characterized in that: The crosslinking agent is selected from at least one of N-hydroxymethyl acrylamide and ethylene glycol dimethacrylate; preferably, the crosslinking agent comprises N-hydroxymethyl acrylamide and ethylene glycol dimethacrylate in a mass ratio of (2-7):

1.

6. The method for preparing the fire extinguishing composition according to any one of claims 1 to 5, characterized in that: include: Step 1: mixing and dissolving guar gum, polyvinyl alcohol, acrylamide and a skeleton support material to obtain a first solution; Step 2: dissolving methacrylic acid to obtain a second solution; Step 3: Pour the second solution into the first solution, mix them evenly, add a cross-linking agent and an initiator, and carry out a graft copolymerization reaction to obtain a fire extinguishing composition.

7. The preparation method according to claim 6, characterized in that: In step 1, the guar gum, polyvinyl alcohol, acrylamide and skeleton support material are dissolved at 50-70° C. to obtain the first solution; and / or, in step 2, the methacrylic acid is dissolved at 30-50° C.; And / or, in step 2, after the methacrylic acid is completely dissolved, a neutralizing agent is added for neutralization, and the degree of neutralization is 80-90%, to obtain the second solution; And / or, in step 3, the graft copolymerization reaction is carried out at 70-80° C. for 1 h; And / or, in step 3, after the graft copolymerization reaction is carried out for 1 hour, a preservative is added to obtain the fire extinguishing composition.

8. Use of the fire extinguishing composition according to any one of claims 1 to 5 or the fire extinguishing composition obtained by the preparation method according to claim 6 or 7 in the field of batteries, wherein the battery is preferably selected from lithium batteries.

9. A fire extinguishing hydrogel, characterized in that: The raw materials include 10-20wt% of the fire extinguishing composition according to any one of claims 1-5 or the fire extinguishing composition obtained by the preparation method according to claim 6 or 7.

10. A two-component fire extinguishing agent, characterized in that: The invention comprises 30-40 wt % of a water-based fire extinguishing component and 60-70 wt % of the fire extinguishing hydrogel component according to claim 9; the water-based fire extinguishing component and the fire extinguishing hydrogel component are stored separately; Preferably, the aqueous component comprises 1-2 wt % of dodecyl phosphate monoester.

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