Easily-demolded high-insulation low-corrosion condensed aerosol fire extinguishing agent and preparation method therefor

Abstract

An easily-demolded high-insulation low-corrosion condensed aerosol fire extinguishing agent and a preparation method therefor. Strontium nitrate and potassium nitrate are jointly used as an oxidizing

Description

[0001] The present disclosure relates to the technical field of condensed aerosol fire extinguishing agent preparation, and particularly to an easily-demolded high-insulation low-corrosion condensed aerosol fire extinguishing agent and a preparation method therefor. BACKGROUND

[0002] The condensed aerosol fire extinguishing agent is a solid mixture composed of an oxidizer, a reducing agent, and a binder, and has been developed as a novel fire extinguishing agent in the past forty years. The condensed aerosol fire extinguishing agent can be classified into a K-type aerosol fire extinguishing agent, in which potassium salts serve as the main oxidizer, and an S-type aerosol fire extinguishing agent, in which strontium salts serve as the main oxidizer. Hie K-type aerosol fire extinguishing agent has the advantage of strong fire extinguishing capability; however, the discharged products thereof have a high moisture absorption rate, and after absorbing moisture, exhibit strong electrical conductivity, which is likely to cause short circuits in battery products widely used in energy storage and other fields, thereby inducing secondary fires. In addition, the discharge products, after absorbing moisture, also exhibit strong corrosiveness, and within a certain period of time, are likely to cause corrosion of electronic components and certain precision instruments, thereby resulting m immeasurable losses. The S-type condensed aerosol fire extinguishing agent, in which strontium nitrate serves as a main oxidizer, has relatively strong fire extinguishing capability, and the discharged products thereof have high insulation strength and low corrosion, and thus has been widely applied.

[0003] Chinese Patent CN102225228B discloses a condensed aerosol fire extinguishing agent, which comprises an oxidizer including 10—15 parts of potassium nitrate, 20—25 parts of strontium nitrate, 3-5 parts of zinc nitrate, 3 5 parts of magnesium nitrate, and 1-5 parts of calcium nitrate. The prepared condensed aerosol fire extinguishing agent not only has a good fire extinguishing effect but also is energy-efficient, environmentally friendly, and low-cost. Meanwhile, the discharged products thereof do not corrode or damage equipment, effectively avoiding secondary combustion of documents and equipment. Chinese Patent CN102614616B discloses a condensed aerosol fire extinguishing agent and a production process therefor. Strontium nitrate is used as a first oxidizer, guanidine nitrate is used as a second oxidizer, and manganese dioxide, bamboo charcoal, magnesium metal, com starch, and aluminium metal are combined to prepare a condensed aerosol fire extinguishing agent with fewer harmful deposits, and no wastewater or waste residues are generated in the whole production process, which is environmentally friendly.

[0004] However, research has revealed that when strontium nitrate is used as an oxidizer and formulated into a priming composition according to a specific formula, moisture absorption tests showed that at a relative humidity of 65%, the moisture absorption rate of strontium nitrate was 2.44% after 8 h and 6.33% after 24 h; while at a relative humidity of 95%, the moisture absorption rates after 4 h and 8 h reached 2.21% and 3.08%, respectively, and the moisture absorption rate after 24 h reached 8.03%. Moreover, the moisture uptake had no equilibrium point and continued to increase. In addition, as the particle size of strontium nitrate increased, the specific surface area also increased, and the moisture absorption rate increased accordingly (see Zhu Yahong et al., Discussion on the Moisture Absorption Property of Strontium Nitrate. 4:34-38,2006). Therefore, the condensed aerosol fire extinguishing agent with strontium nitrate as the main oxidizer has the problem of harsh storage conditions due to the easy moisture absorption of the agent. Meanwhile, in the actual production process, it is found that during the demolding process after the agent is pressed into shape, the moisture absorption of the agent causes significant friction between the agent column and the inner surface of the mold. This friction easily leads to the breakage of the agent column, which affects the quality and output of the agent column; in severe cases, it may even cause safety accidents, such as combustion of the agent column due to excessive friction. Currently, the solution to this problem is to pre-coat the inner wall of the mold with a solid lubricant to facilitate demolding of the agent column. However, this method is inefficient and labour-intensive, and the lubricant adhering to the surface of the agent column adversely affects the combustion effect of the agent column. SUMMARY

[0005] In view of the above technical problems, the present disclosure provides an easily-demolded high-insulation low-corrosion condensed aerosol fire extinguishing agent and a preparation method therefor. By introducing additives, the demolding difficulty of the condensed aerosol fire extinguishing agent is fundamentally resolved, thereby improving the production efficiency of the agent column.

[0006] The technical solution adopted by the present disclosure is as follows:

[0007] The present disclosure provides an easily-demolded high-insulation low-corrosion condensed aerosol fire extinguishing agent, comprising 60-80 parts of an oxidizer, 5-20 parts of a reducing agent, 5-10 parts of a binder and 1-10 parts of an additive.

[0008] Preferably, the oxidizer comprises strontium nitrate and potassium nitrate at a ratio of 6:1-2:5.

[0009] Preferably, the reducing agent is any one of carbon, guanidine nitrate, nitroguanidine, melamine, dicyandiamide and urea.

[0010] Preferably, the binder is any one of epoxy resin, phenolic resin, shellac, starch, and rubber. Preferably, the additive is any one of tungsten disulfide, molybdenum disulfide, niobium diselenide, polytetrafluoroethylene, ethylene bis stearamide, and hexagonal boron nitride.

[0011] The present disclosure further provides a preparation method for the condensed aerosol fire extinguishing agent, comprising the following steps:

[0012] (1) weighing a binder, dissolving the binder in anhydrous ethanol, and mixing uniformly to obtain a binder solution;

[0013] (2) respectively sieving the oxidizer and the reducing agent by using a 100-mesh sieve, performing dry mixing, and mixing uniformly to obtain a first material;

[0014] (3) adding a proper amount of additive to the first material obtained in step (2) and stirring and mixing uniformly to obtain a second material;

[0015] (4) adding the binder solution to the second material and mixing fu 1 ly to obtain a mixed material;

[0016] (5) granulating the mixed material obtained in step (4) by sieving through a 20-mesh sieve, and drying at 50°C to obtain condensed aerosol fire extinguishing agent granules; and

[0017] (6) placing the condensed aerosol fire extinguishing agent granules obtained in step (5) in a mold for pressing at 4-6 MPa, and demolding to obtain a ¢25 mm fire extinguishing agent column.

[0018] Preferably, in step (1), a mass of the anhydrous ethanol is 4%-10% of a total mass of the condensed aerosol fire extinguishing agent.

[0019] Beneficial effects of the present disclosure are as follows: strontium nitrate and potassium nitrate are jointly used as oxidizers of the condensed aerosol fire extinguishing agent, reducing the content of potassium nitrate, thereby weakening the alkalinity of discharged products, reducing the corrosion to documents and equipment after fire extinguishment, improving electrical insulation, promoting the development and application of the condensed aerosol fire extinguishing agent, and breaking the use limitation of the condensed aerosol fire extinguishing agent in electrified places, precision instrument places, and new-energy places.

[0020] In the condensed aerosol fire extinguishing agent of the present disclosure, a proper amount of additive is further added. Weak interaction forces exist between additive molecules. During molding and demolding of the condensed aerosol fire extinguishing agent, molecular layers undergo relative slip due to the action of shear force, so that a lubricating effect can be achieved in the demolding process of agent columns, thereby realizing rapid demolding, reducing the demolding difficulty of the condensed aerosol fire extinguishing agent columns, and improving demolding efficiency. Additive components form a dense hydrophobic interface on the surface of agent columns of the condensed aerosol fire extinguishing agent after compression molding, effectively improving the problem that the condensed aerosol fire extinguishing agent is prone to moisture absorption, achieving a certain moisture-proof effect, and greatly reducing the requirements for a storage environment. In addition, additive components can react with oxygen during combustion, and after being added, do not hinder the combustion of the agent, so that a burning rate can be stabilized. The above three advantages of the additive can enable large-scale production, storage, and use of the condensed aerosol fire extinguishing agent, and contribute to further popularization and application of the condensed aerosol fire extinguishing agent. DETAILED DESCRIPTION OF EMBODIMENTS

[0021] The technical solution of the present disclosure is described in further detail below in conjunction with the specific embodiments. It should be noted that the following examples are only preferred examples of the present disclosure and should not be constmed as limiting the present disclosure. The scope of protection of the present disclosure shall be subject to the content recorded in the claims. Modifications and equivalent substitutions made to the technical solution of the present disclosure by those skilled in the art without making creative work shall all fall within the scope of protection of the present disclosure.

[0022] Example 1

[0023] (1) Take 10 parts of epoxy resin, add the epoxy resin into anhydrous ethanol (accounting for 5% of the total mass of the condensed aerosol fire extinguishing agent), and stir until completely dissolved to obtain an epoxy resin solution;

[0024] (2) Take 60 parts of strontium nitrate. 10 parts of potassium nitrate, and 20 parts of melamine, sieve the materials by using a 100-mesh sieve for preliminary mixing of dry materials, and mix uniformly to obtain a first material;

[0025] (3) Add 5 parts of tungsten disulfide to the first material, continuously stir, and mix uniformly to obtain a second material;

[0026] (4) Pour the epoxy resin solution obtained in step (1) into the second material, stir thoroughly, and mix uniformly to obtain a mixed material;

[0027] (5) Sieve the mixed material by using a 20-mesh sieve for granulation, and dry at 50°C until the volatile content is less than l%to obtain a condensed aerosol fire extinguishing agent; and

[0028] (6) Press the condensed aerosol fire extinguishing agent obtained in step (5) at 5 MPa to form a ¢25 mm cylindrical fire extinguishing agent column.

[0029] Example 2

[0030] The method and steps are the same as those in Example 1, except that in step (2), the amount of strontium nitrate is changed to 50 parts and the amount of potassium nitrate is changed to 20 parts, thereby preparing an agent column.

[0031] Example 3

[0032] The method and steps are the same as those in Example 1, except that in step (2), the amount of strontium nitrate is changed to 40 parts and the amount of potassium nitrate is changed to 30 parts, thereby preparing an agent column.

[0033] Example 4

[0034] The method and steps are the same as those in Example 1, except that in step (2), the amount of strontium nitrate is changed to 30 parts and the amount of potassium nitrate is changed to 40 parts, thereby preparing an agent column.

[0035] Example 5

[0036] The method and steps are the same as those in Example I, except that in step (2), the amount of strontium nitrate is changed to 20 parts and the amount of potassium nitrate is changed to 50 parts, thereby preparing an agent column.

[0037] Example 6

[0038] The method and steps are the same as those in Example 1, except that in step (1), 8 parts of shellac is used instead of 10 parts of epoxy resin, in step (2) the amount of strontium nitrate is changed to 40 parts and the amount of potassium nitrate is changed to 25 parts, and 27 parts of urea is used instead of 20 parts of melamine, thereby preparing an agent column.

[0039] Example 7

[0040] (1) Take 10 parts of phenolic resin, add the phenolic resin into anhydrous ethanol (accounting for 5% of the total mass of the condensed aerosol fire extinguishing agent), and stir until completely dissolved to obtain a phenolic resin solution;

[0041] (2) Take 40 parts of strontium nitrate, 30 parts of potassium nitrate, and 20 parts of nitroguanidine, sieve the materials by using a 100-mesh sieve for preliminary mixing of dry materials, and mix uniformly to obtain a first material;

[0042] (3) Add 6 parts of molybdenum disulfide to the first material, continuously stir, and mix uniformly to obtain a second material;

[0043] (4) Pour the phenolic resin solution obtained in step (1) into the second material, stir thoroughly, and mix uniformly to obtain a mixed material;

[0044] (5) Sieve the mixed material by using a 20-mesh sieve for granulation, and dry at 50°C until the volatile content is less than l%to obtain a condensed aerosol fire extinguishing agent; and

[0045] (6) Press the condensed aerosol fire extinguishing agent obtained in step (5) at 5 MPa to form a 25 mm cylindrical fire extinguishing agent column.

[0046] Example 8

[0047] The method and steps are the same as those in Example 7, except that in step (2), nitroguanidine is replaced with dicyandiamide, and in step (3), 7 parts of polytetrafluoroethylene are used instead of 6 parts of molybdenum disulfide, thereby preparing an agent column.

[0048] Example 9

[0049] The method and steps are the same as those in Example 7, except that in step (1), phenolic resin is replaced with rubber, in step (2), nitroguanidine is replaced with carbon, and in step (3), 1 part of tungsten disulfide is used instead of 6 parts of molybdenum disulfide, thereby preparing an agent column.

[0050] Example 10

[0051] The method and steps are the same as those in Example 9, except that in step (3), 3 parts of tungsten disulfide are used instead of 1 part of tungsten disulfide, thereby preparing an agent column.

[0052] Example 11

[0053] The method and steps are the same as those in Example 9, except that in step (3), 8 parts of tungsten disulfide are used instead of I part of tungsten disulfide, thereby preparing an agent column.

[0054] Example 12

[0055] The method and steps are the same as those in Example 9, except that in step (3), 10 parts of tungsten disulfide are used instead of 1 part of tungsten disulfide, thereby preparing an agent column.

[0056] Example 13

[0057] The method and steps are the same as those in Example 9, except that in step (3), 5 parts of niobium diselenide are used instead of 1 part of tungsten disulfide, thereby preparing an agent column.

[0058] Example 14

[0059] The method and steps are the same as those in Example 9, except that in step (3), 5 parts of ethylene bis stearamide are used instead of 1 part of tungsten disulfide, thereby preparing an agent column.

[0060] Example 15

[0061] The method and steps are the same as those in Example 9, except that in step (3), 5 parts of hexagonal boron nitride are used instead of 1 part of tungsten disulfide, thereby preparing an agent column.

[0062] Comparative Example 1

[0063] (1) Take 10 parts of epoxy resin, add the epoxy resin into anhydrous ethanol (accounting for 5% of the total mass of the condensed aerosol fire extinguishing agent), and stir until completely dissolved to obtain an epoxy resin solution;

[0064] (2) Take 70 parts of potassium nitrate and 20 parts of melamine, sieve the materials by using a 100-mesh sieve for preliminary' mixing of dry materials, and mix uniformly to obtain a first material;

[0065] (3) Pour the epoxy resin solution obtained in step (1) into the first material, stir thoroughly, and mix uniformly to obtain a mixed material;

[0066] (4) Sieve the mixed material by using a 20-mesh sieve for granulation, and dry' at 50°C until the volatile content is less than l%to obtain a condensed aerosol fire extinguishing agent; and

[0067] (5) Press the condensed aerosol fire extinguishing agent obtained in step (4) at 5 MPa to form a ¢25 mm cylindrical fire extinguishing agent column.

[0068] Comparative Example 2

[0069] The method and steps are the same as those in Comparative Example 1, except that in step (2), 70 parts of strontium nitrate are used instead of 70 parts of potassium nitrate.

[0070] Comparative Example 3

[0071] (1) Take 10 parts of epoxy resin, add the epoxy resin into anhydrous ethanol (accounting for 5% of the total mass of the condensed aerosol fire extinguishing agent), and stir until completely dissolved to obtain an epoxy resin solution;

[0072] (2) Take 70 parts of potassium nitrate and 20 parts of melamine, sieve the materials by using a 100-mesh sieve for preliminary mixing of dry materials, and mix uniformly to obtain a first material;

[0073] (3) Add 5 parts of tungsten disulfide to the first material, continuously stir, and mix uniformly to obtain a second material;

[0074] (4) Pour the epoxy resin solution obtained in step (1) into the second material, stir thoroughly, and mix uniformly to obtain a mixed material;

[0075] (5) Sieve the mixed material by using a 20-mesh sieve for granulation, and dry at 50°C until the volatile content is less than l%to obtain a condensed aerosol fire extinguishing agent; and

[0076] (6) Press the condensed aerosol fire extinguishing agent obtained in step (5) at 5 MPa to form a ¢25 mm cylindrical fire extinguishing agent column.

[0077] Comparative Example 4

[0078] The method and steps are the same as those in Comparative Example 3, except that in step (2), 70 parts of strontium nitrate are used instead of 70 parts of potassium nitrate.

[0079] Comparative Example 5

[0080] (1) Take 10 parts of epoxy resin, add the epoxy resin into anhydrous ethanol (accounting for 5% of the total mass of the condensed aerosol fire extinguishing agent), and stir until completely dissolved to obtain an epoxy resin solution;

[0081] (2) Take 60 parts of strontium nitrate, 10 parts of potassium nitrate, and 20 parts of melamine, sieve the materials by using a 100-mesh sieve for preliminary mixing of dry materials, and mix uniformly to obtain a first material;

[0082] (3) Pour the epoxy resin solution obtained in step (1) into the first material, stir thoroughly, and mix uniformly to obtain a mixed material;

[0083] (4) Sieve the mixed material by using a 20-mesh sieve for granulation, and dry at 50°C until the volatile content is less than l%to obtain a condensed aerosol fire extinguishing agent; and

[0084] (5) Press the condensed aerosol fire extinguishing agent obtained in step (4) at 5 MPa to form a ¢25 mm cylindrical fire extinguishing agent column.

[0085] Result testing:

[0086] Perform demolding experiments on cylindrical fire extinguishing agent columns prepared in Examples 1-15 and Comparative Examples 1-5;

[0087] Place the obtained agents into aerosol fire extinguishing devices, and collect discharged solid residues using PVC plates and copper plates for testing electrical insulation and corrosion resistance, where during electrical insulation testing, the resistance of the solid residues was measured at 3 5 °C and 90% relative humidity for 24 h of moisture absorption; during corrosion resistance testing, tire corrosion on the copper plates was observed at 30°C and 85% relative humidity for 24 h of moisture absorption;

[0088] Determine the burning rate of the agent columns according to the height and burning time of the agent columns;

[0089] Place the demolded agent columns in an environment of 21 °C and 78% relative humidity, and detect the moisture absorption rate of the agent columns after 24 h. Tire results are shown in Table 1. Table 1: Performance of fire extinguishing agent columns prepared from various formulations Example Demolding condition Burning rate (mm / s) Moisture absorption rate Insulation resistance (MQ) Corrosivity Example 1 Normal 2.01 0.39% >2200 No obvious discoloration Example 2 Normal 2.03 0.36% >2200 No obvious discoloration Example 3 Normal 2.04 0.34% >900 Slight discoloration Example 4 Normal 2.05 0.34% >900 Slight discoloration Example 5 Normal 2.09 0.31% >100 Slight discoloration Example 6 Normal 2.03 0.33% >900 Slight discoloration Example 7 Normal 2.06 0.36% >900 Slight discoloration Example 8 Normal 1.86 0.27% >900 Slight discoloration Example 9 Normal 2.03 0.42% >900 Slight discoloration Example 10 Normal 2.01 0.40% >900 Slight discoloration Example 11 Nonnal 2.02 0.35% >900 Slight discoloration Example 12 Normal 2.04 0.32% >900 Slight discoloration Example 13 Normal 2.01 0.31% >900 Slight discoloration Example 14 Normal 2.03 0.33% >900 Slight discoloration Example 15 Normal 2.06 0.35% >900 Slight discoloration Comparative Example 1 Normal 2.08 0.48% 0 Severe discoloration Comparative Example 2 Severe mold sticking, molding failed / 1.35% / / Comparative Example 3 Normal 2.10 0.32% 0 Severe discoloration Comparative Example 4 Normal 2.07 0.35% >2200 No obvious discoloration Comparative Example 5 Severe mold sticking, molding failed / 1.32% / /

[0090] Table 1 shows that in Comparative Example 1, potassium nitrate was used as the oxidizer. Without the addition of additives, normal demolding could be achieved, but the discharged solid residues were electrically conductive and exhibited high corrosion. When additives were added (Comparative Example 3), the same problems of low electrical insulation and high corrosion occurred. In Comparative Example 2, strontium nitrate was used as the oxidizer. Without the addition of additives, the agent columns were severely stuck in molds and complete demolding could not be achieved. When additives were added (Comparative Example 4), normal demolding could be achieved, indicating that the additives could reduce the hygroscopicity of strontium nitrate and facilitate demolding. When both strontium nitrate and potassium nitrate were used as oxidizers together with additives, the prepared agent columns could be normally demolded, with a stable burning rate, low hygroscopicity, high electrical insulation, and weak corrosiveness. As the hygroscopicity gradually decreased, the electrical insulation of the discharged products was significantly reduced while the corrosiveness gradually increased. These results indicate that the type and content of oxidizers in the condensed aerosol fire extinguishing agents had a significant impact on the burning rate and hygroscopicity of the fire extinguishing agent, and the electrical insulation and corrosiveness of the discharged products. Using strontium nitrate with a relatively high content as the main oxidizer makes the agent columns easier to store and use.

Claims

1. An easily-demolded high-insulation low-corrosion condensed aerosol fire extinguishing agent, characterised by comprising 60-80 parts of an oxidizer, 5-20 parts of a reducing agent, 5-10 parts of a binder and 1-10 parts of an additive.

2. The easily-demolded high-insulation low-corrosion condensed aerosol fire extinguishing agent according to claim 1, wherein the oxidizer comprises strontium nitrate and potassium nitrate at a ratio of 6:1-2:5.

3. The easily-demolded high-insulation low-corrosion condensed aerosol fire extinguishing agent according to claim 1, wherein the reducing agent is any one of carbon, guanidine nitrate, nitroguanidine, melamine, dicyandiamide and urea.

4. The easily-demolded high-insulation low-corrosion condensed aerosol fire extinguishing agent according to claim 1, wherein the binder is any one of epoxy resin, phenolic resin, shellac, starch, and rubber.

5. The easily-demolded high-insulation low-corrosion condensed aerosol fire extinguishing agent according to claim 1, wherein the additive is any one of tungsten disulfide, molybdenum disulfide, niobium diselenide, polytetrafluoroethylene, ethylene bis stearamide, and hexagonal boron nitride.

6. A preparation method for the condensed aerosol fire extinguishing agent according to any one of claims 1 to 5, characterised by comprising the following steps:(1) weighing a binder, dissolving the binder in anhydrous ethanol, and mixing uniformly to obtain a binder solution;(2) respectively sieving the oxidizer and the reducing agent by using a sieve, performing dry mixing, and mixing uniformly to obtain a first material;(3) adding a proper amount of additive to the first material obtained in step (2) and stirring and mixing uniformly to obtain a second material;(4) adding the binder solution to the second material and mixing fully to obtain a mixed material;(5) granulating the mixed material obtained in step (4) by sieving through a sieve, and drying to obtain condensed aerosol fire extinguishing agent granules; and(6) placing the condensed aerosol fire extinguishing agent granules obtained in step (5) in a mold for pressing, and demolding to obtain a fire extinguishing agent column.

7. The preparation method according to claim 6, wherein in step (1), a mass of theanhydrous ethanol accounts for 4%-10% of a total mass of the condensed aerosol fire extinguishing agent.

8. The preparation method according to claim 6, wherein the sieve in step (2) is a 100-mesh sieve.

9. Tire preparation method according to claim 6. wherein the sieve in step (5) is a 20-mesh sieve, and a drying temperature is 50°C.

10. The preparation method according to claim 6, wherein a pressure for pressing the agent column in step (6) is 4-6 MPa, and a size of the agent column is ¢25 mm.