A nano-modified silicone foam fire extinguishing agent

Abstract

The present invention provides a nano-modified silicone foam fire extinguishing agent for extinguishing liquid fires, belonging to the technical field of fire-fighting foam extinguishing. The foam fire extinguishing agent includes components such as silicone surfactants, hydrocarbon surfactants, foam stabilizers, nano-modified particles, and antifreeze agents. Through comparative experiments, polyether-modified heptamethyltrisiloxane is selected as the silicone surfactant, sodium α-olefin sulfonate as the hydrocarbon surfactant, modified silicone resin polyether emulsion as the foam stabilizer, modified nano-silica as the nano-modified particles, and calcium chloride as the antifreeze agent. The addition amounts of the five components are 1wt% - 3wt%, 0.2wt% - 0.8wt%, 0.6wt% - 1.8wt%, 0.5wt% - 1.5wt%, and 1wt% - 3wt% in sequence. At the optimal addition ratio, the foaming multiple of the foam fire extinguishing agent is 11.5, and the 25% liquid drainage time is 278.6 s. The addition of nano-particles enables the foam not to separate out a large amount of foam liquid during use, thereby better isolating the fuel from contact with oxygen and reducing the fluidity of the fuel. The present invention can improve the fire extinguishing efficiency of liquid fires and solve the environmental protection problems of traditional foam fire extinguishing agents.

Description

Technical Field

[0001] The present invention relates to the technical field of foam fire extinguishing agents, and particularly to a nano-modified silicone foam fire extinguishing agent that is good at extinguishing liquid fires. Background Art

[0002] For liquid fires, traditional water extinguishing is difficult to play a role and may even easily cause secondary disasters. Foam fire extinguishing agents have good effects on extinguishing liquid fires. Foam fire extinguishing agents can be divided into chemical foam fire extinguishing agents, air foam fire extinguishing agents, alcohol-resistant foam fire extinguishing agents, fluoroprotein foam fire extinguishing agents, aqueous film-forming foam fire extinguishing agents, etc. The types of fire extinguishing foams are very rich, but not all of them are suitable for extinguishing liquid fires. Among them, aqueous film-forming foam fire extinguishing agents can quickly extinguish most liquid fires, so they are widely used in places with a high incidence of flammable liquid fires. However, some recent studies have shown that aqueous film-forming foam fire extinguishing agents can cause serious damage to the natural environment. Although some newly developed short-chain fluorocarbon surfactants have improvements over long-chain fluorocarbon surfactants, they have not been widely used. The fluorine-free foam fire extinguishing agents prepared from silicone surfactants or hydrocarbon surfactants reduce environmental damage, but their fire extinguishing performance and storage stability are not good. Therefore, in order to solve the environmental protection problems of most aqueous film-forming foam fire extinguishing agents and the performance problems of new fluorine-free foam fire extinguishing agents, and improve the fire extinguishing efficiency of liquid fires, it is of great practical significance and application prospects to study more environmentally friendly and efficient foam fire extinguishing agents based on existing liquid fire foam fire extinguishing agents. Summary of the Invention

[0003] The present invention aims to develop a nano-modified silicone foam fire extinguishing agent for extinguishing liquid fires by combining environmentally friendly surfactants and nanoparticles. Using polyether-modified heptamethyltrisiloxane, α-olefin sulfonate, modified silicone resin polyether emulsion, modified nano-silica, calcium chloride and other materials to produce a foam fire extinguishing agent with excellent fire extinguishing performance and environmental protection performance, which can effectively isolate the contact between liquid fuel and oxygen, improve the fire extinguishing efficiency, and the material is harmless to the environment, has a low cost, and can adapt to various complex liquid fire environments.

[0004] The nano-modified silicone foam fire extinguishing agent includes a silicone surfactant, a hydrocarbon surfactant, a foam stabilizer, nanoparticles, an antifreeze and water. Among them, by mass ratio, the silicone surfactant accounts for 1wt% - 3wt%, the hydrocarbon surfactant accounts for 0.2wt% - 0.8wt%, the foam stabilizer accounts for 0.6wt% - 1.8wt%, the nanoparticles account for 0.5wt% - 1.5wt%, the antifreeze accounts for 1wt% - 3wt%, and the balance is water.

[0005] Further, the silicone surfactant is polyether-modified heptamethyltrisiloxane.

[0006] Further, the hydrocarbon surfactant is sodium α-olefin sulfonate.

[0007] Further, the foam stabilizer is a modified silicone resin polyether emulsion.

[0008] Further, the nanoparticles are modified nano-silica.

[0009] Further, the antifreeze is calcium chloride.

[0010] Further, polyether-modified heptamethyltrisiloxane, sodium α-olefin sulfonate and calcium chloride are mixed in proportion to form Component A. The modified silicone resin polyether emulsion is mixed with water in proportion and stirred. After it is fully dissolved, a certain amount of modified nano-silica is added and stirred to make it uniformly dispersed to form Component B. Component A and Component B are fully mixed and poured into a pore plate foaming device for foaming to prepare a nano-modified silicone foam fire extinguishing agent. The preparation process is as Figure 1 shown.

[0011] By adding nanoparticles, the structural stability and thermal stability of the foam fire extinguishing agent are improved, and problems such as the relatively fast foam liquid drainage rate of ordinary aqueous film-forming foam fire extinguishing agents and the decline in oxygen isolation and temperature reduction effects under high-temperature conditions are improved, thereby improving the fire extinguishing efficiency of liquid fires.

[0012] The present invention first determines the selection of various component materials such as silicone surfactants, environmentally friendly hydrocarbon surfactants, foam stabilizers, nano-modified particles, and antifreezes, and then designs an experimental scheme using the response surface analysis method to conduct foaming experiments and liquid drainage experiments. The addition ratios of each component are optimized and verified using a quadratic polynomial model, and finally the optimal addition ratios of each component are obtained.

[0013] A foam fire extinguishing agent sample is prepared according to the optimal ratio, and its fire extinguishing performance test and environmental protection performance test are carried out. The fire extinguishing effect is analyzed through the fire extinguishing time and afterburning time, which proves the high fire extinguishing effect of the foam fire extinguishing agent. Through gas product analysis and the analysis of the effects of the foam fire extinguishing agent and fire extinguishing residues on soil and water quality, the good environmental protection of the foam is proved.

[0014] The beneficial effects of the above technical solutions of the present invention are as follows:

[0015] When the present invention extinguishes liquid fires, a large amount of foam liquid will not be separated out, so that it can better isolate the fuel from oxygen and prevent the liquid fuel from flowing. While meeting the requirements of efficient fire extinguishing, it also takes into account environmental protection characteristics, which can provide ideas for the development of foam fire extinguishing agents applied to liquid fires and has certain significance for the research and progress of liquid fire fighting. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the preparation flow chart of the present invention;

[0017] Figure 2 This is the thermogravimetric curve of the present invention during the programmed temperature rise process;

[0018] Figure 3 This is the infrared spectrum of the gas product after the programmed temperature rise of the present invention. Detailed implementation manners

[0019] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] The present invention provides a nano-modified silicone foam fire extinguishing agent for extinguishing liquid fires.

[0021] The foam includes a silicone surfactant, an environmentally friendly hydrocarbon surfactant, a foam stabilizer, nano-modified particles, an antifreeze and water. Among them, by mass ratio, the silicone surfactant accounts for 1wt%-3wt%, the hydrocarbon surfactant accounts for 0.2wt%-0.8wt%, the foam stabilizer accounts for 0.6wt%-1.8wt%, the nano-particles account for 0.5wt%-1.5wt%, calcium chloride accounts for 1wt%-3wt%, and the balance is water.

[0022] Polyether-modified heptamethyltrisiloxane is a silicone surfactant. Polyether-modified heptamethyltrisiloxane can greatly reduce the surface tension of the solution, enhance the wetting, adhesion and spreading ability of the liquid. At the same time, this surfactant has lower toxicity and environmental hazards. The addition range was determined to be 1wt%-3wt% by single-factor experiments, and the optimal addition ratio was obtained as 2.33wt% by response surface optimization experiments.

[0023] Sodium α-olefin sulfonate is a hydrocarbon surfactant. Sodium α-olefin sulfonate has excellent foaming ability, hard water resistance and solubility. Many research results show that it is safe for humans and the environment. Therefore, its environmental friendliness and high foaming property are the main reasons for considering its application in foam fire extinguishing agents. The addition range was determined to be 0.2wt%-0.8wt% by single-factor experiments, and the optimal addition ratio was obtained as 0.64wt% by response surface optimization experiments.

[0024] The modified silicone polyether emulsion is used as a foam stabilizer. The modified silicone polyether emulsion is a semi-transparent viscous liquid or gel-like substance, which has good dispersibility in water. It can make the molecules of some linear anionic surfactants (such as sodium dodecyl ether sulfate, sodium dodecyl sulfate, and sodium α-olefin sulfonate, etc.) be orderly distributed in the bubble liquid film, and can endow the foam with good viscosity and self-healing ability. At the same time, it can change the internal arrangement order of the molecules inside the foam, making the bubbles generated by the surfactant be arranged neatly and closely between bubbles, so as to form a dense inner layer film between the gas phase and the liquid phase, enhancing the overall compressive ability and controlling the structural stability of the bubble liquid film, thereby achieving excellent foam stabilizing effect. The addition range is determined to be 0.6wt% - 1.8wt% by single-factor experiment, and the optimal addition ratio is obtained as 1.34wt% by response surface optimization experiment.

[0025] The modified nano-silica is a nano-modified particle. Nano-silica is a commonly used nano-modified material. After being modified by silane coupling agent KH-570 and washed with absolute ethanol, its agglomeration phenomenon is significantly improved, and it can play a better role. The addition of modified nano-silica can improve the heat resistance and thermal stability of the foam fire extinguishing agent. The addition range is determined to be 0.5wt% - 1.5wt% by single-factor experiment, and the optimal addition ratio is obtained as 0.98wt% by response surface optimization experiment.

[0026] Calcium chloride is used as an antifreeze agent, which can meet the antifreeze requirements of the foam fire extinguishing agent during storage, transportation, and use, so that the state and performance of the foam fire extinguishing agent will not be damaged under low-temperature conditions. After calcium chloride antifreeze is dissolved in water, it can fill the gaps between water molecules and affect the arrangement of water molecules under low-temperature conditions, thus playing an antifreeze role. The addition ratio of calcium chloride is 1wt% - 3wt%, and the dosage can be adjusted within this range according to requirements.

[0027] In specific experiments and applications,

[0028] First, according to the actual situation of extinguishing liquid fires, considering various factors such as experimental effects and economic costs, various component materials are screened through experiments. Then, the response surface analysis method is used to design the experimental scheme, and foaming experiments and drainage experiments are carried out. According to the experimental results, the optimal addition ratios of polyether-modified heptamethyltrisiloxane, α-olefin sulfonate, modified silicone polyether emulsion, and nano-silica are 2.33wt%, 0.64wt%, 1.34wt%, and 0.98wt% respectively. The foam sample prepared with this optimal ratio has a foaming multiple of 11.5 and a 25% drainage time of 278.6s, with excellent effects.

[0029] Then, the fire extinguishing performance test was carried out. First, three kinds of samples, namely ordinary foam fire extinguishing agent, silicone foam fire extinguishing agent and nano-modified silicone foam fire extinguishing agent, were subjected to programmed temperature rise treatment using a thermogravimetric analyzer to obtain the thermogravimetric curves of the samples varying with temperature. The experimental results proved that among the three, the nano-modified silicone foam fire extinguishing agent had a slower mass loss rate and the smallest total mass loss, demonstrating its good stability under high temperature conditions. In the small-scale fire extinguishing experiment, the fire extinguishing time of the nano-modified silicone foam fire extinguishing agent was 27 s, and the anti-rekindling time was much longer than the national standard requirement of 10 min, proving its excellent fire extinguishing performance and anti-burning performance.

[0030] Finally, the environmental friendliness test was carried out. From the detection results of the gas product components in the infrared part of the thermogravimetric-infrared combined experiment, it was found that the nano-modified silicone foam fire extinguishing agent did not generate gases harmful to humans and the environment under high temperature conditions. The main gas product was carbon dioxide, which not only did not damage the environment but also could reduce the oxygen concentration around the fire source to assist in extinguishing liquid fires. The detection of the impact on soil and water quality of this foam fire extinguishing agent also proved that it would not damage farmland soil and irrigation water bodies.

[0031] Thus, it was proved that the nano-modified silicone foam fire extinguishing agent showed excellent performance in foaming, fire extinguishing, anti-burning, environmental protection, etc., and had certain development prospects.

[0032] The following is illustrated with specific embodiments.

[0033] Example 1 (Response surface optimization experiment)

[0034] The response surface analysis method was used to optimize the component ratios of the nano-modified silicone foam fire extinguishing agent, and the foaming multiple and 25% drainage time were tested. The factor combinations and experimental results of the response surface analysis are shown in the following table.

[0035] Table 1 Factor combinations and experimental results of response surface analysis

[0036]

[0037]

[0038] The experimental data were fitted and analyzed using Design-Expert software, and the optimal solution was fitted through the response surface model, obtaining the optimal addition ratio of each component of the nano-modified silicone foam fire extinguishing agent: polyether-modified heptamethyl trisiloxane is 2.33wt%, α-olefin sulfonate sodium is 0.64wt%, modified silicone resin polyether emulsion is 1.34wt%, and modified nano-silica is 0.98wt%. At this time, the foaming performance and foam stability of the foam fire extinguishing agent can reach the optimal situation, with a foaming multiple of 11.2 and a 25% liquid separation time of 281.8s. Three experimental tests were carried out according to the software prediction value, and the average value was taken. The foaming multiple was 11.5 and the 25% liquid separation time was 278.6s. The predicted value was very close to the experimental value, so the optimal addition ratio obtained by software fitting is desirable.

[0039] Example 2 (fire extinguishing and anti-burning effect test)

[0040] A gasoline fire extinguishing experiment was conducted on a 0.5m×0.5m oil pan. The fire extinguishing device used a 9L handheld foam fire extinguisher, which was filled with foam fire extinguishing agent and gas. The gas type was nitrogen and the filling pressure was 1.2MPa. The experimental injection position was 2m away from the edge of the oil pan. The gasoline consumption was 2.5L. After the fuel was pre-burned for 60s and burned stably, the fire extinguishing began. The flame was small in the pre-burning stage. At the 55th second, the gasoline reached a stable combustion state and the flame height was high. At this time, nano-modified silicone foam fire extinguishing agent was used for spraying and extinguishing. The frequency of flame pulsation accelerated, and then the fire began to shrink and was gradually controlled. The thickness of the foam layer on the gasoline surface thickened with the continuous injection of the foam fire extinguishing agent, and the flame gradually decreased, and was finally completely extinguished 27 seconds after the start of the fire extinguishing.

[0041] After the fire extinguishing experiment, the anti-reignition effect of the foam fire extinguishing agent was tested. An anti-burning tank with an inner diameter of 8.9 cm, a wall thickness of 6.5 mm, and a depth of 8.5 cm was placed in the center of the oil pan, and an appropriate amount of gasoline and water were poured in and ignited. After 10 minutes, there was no obvious change on the surface of the oil pan. The anti-reignition time required in the national standard "Foam Fire Extinguishing Agent" GB15308-2006 is not less than 10 minutes, which shows that the anti-reignition effect of the foam fire extinguishing agent is excellent. Manual intervention began at 12 minutes, and the oil surface was ignited at the 14th minute. At the 22nd minute, about 25% of the oil surface was ignited, and this process took about 8 minutes. The coverage of the foam on the oil surface is very ideal, isolating the gasoline in the oil pan and the flame of the anti-burning tank, preventing the volatilization of gasoline, and making it difficult for the gasoline in the oil pan to be re-ignited.

[0042] Example 3 (thermogravimetric infrared combined experiment)

[0043] The TG curves of three foam fire extinguishing agent samples, namely ordinary aqueous film-forming foam fire extinguishing agent, silicone foam fire extinguishing agent, and nano-modified silicone foam fire extinguishing agent, were obtained by using a thermogravimetric analyzer with a programmed temperature increase. At the same time, a thermo-IR combined kit transported the gas products generated during the heating process to a Fourier transform infrared spectrometer, and the types and contents of the tail gas were judged by measuring the infrared spectral absorption peaks of the gas products. The usage amount of each group of samples was 10 mg (±0.5 mg), the air flow rate was set at 100 mL / min, the heating rate was 10 °C / min, and the heating range was from room temperature to 400 °C.

[0044] The thermogravimetric curves are as Figure 2 shown. The thermogravimetric curve of the nano-modified silicone foam fire extinguishing agent has been higher than those of the other two foam fire extinguishing agents since room temperature. In the medium and low temperature stage from room temperature to 180 °C, no obvious mass loss occurred in all three samples, and the mass percentage remained above 95%. When the temperature exceeded 180 °C, the mass of the aqueous film-forming foam fire extinguishing agent and the silicone foam fire extinguishing agent dropped sharply, and some components in the foam fire extinguishing agent began to oxidize and generate gas. Until about 240 °C, these unstable components reacted completely, and the overall mass reduction rate began to slow down and reached about 60% at 400 °C. Compared with these two, the nano-modified silicone foam fire extinguishing agent began to show obvious mass loss at about 200 °C, and the mass loss rate was slower. The mass loss rate slowed down at 350 °C and the mass percentage was about 75%. Figure 3 is the infrared spectrum of the gas products. There is no significant difference among the three curves as a whole, and no obvious prominent absorption peaks appear in the high temperature stage. For CO, the absorbance is concentrated between 0.006 and 0.008 at 100 °C and 200 °C. When the temperature rises from 100 °C to 400 °C, the absorbance approaches 0.009 at a wavenumber of about 2100 cm -1 -1, with a slight increase, but its intensity is still very weak and can be almost ignored for the total amount of gas. The absorbance of SO2 gas in the three curves is only slightly higher than 0, and the difference among the three curves is extremely small, within 0.0005, indicating that no SO2 gas is generated during the heating process of the nano-modified silicone foam fire extinguishing agent. The absorption peak of CO2 is mainly between 2250 and 2400 cm -1 -1. At the high temperature of 400 °C, the intensity of the CO2 absorption peak is the largest, and CO2 gas is generated at all three temperatures. CO2 gas itself is non-flammable, non-toxic and harmless, so it will not cause damage to the environment.

[0045] Example 4 (Soil and Water Quality Impact Test)

[0046] Take two samples of dryland soil from Weibei area of ​​Shaanxi Province, each weighing 10 kg. Pour 100 mL of nano-modified silicone foam fire extinguishing agent and 5 g of foam fire extinguishing agent residue after burning on the surface of one of the soil samples, stir the foam and soil thoroughly to mix the two evenly, as sample A, and the other without foam as sample B. Then let the soil sample stand for 7 days, and add water appropriately during the standing process. After 7 days, take 1 kg of soil sample for soil quality testing. The test content mainly includes the effective phosphorus content, effective potassium content, organic matter content, pH value, etc. in the soil, as well as the content of some rare elements that may cause pollution and damage to the soil. The test standard for substances with pollution risks shall be based on the national standard "Standard for Risk Control of Soil Pollution in Agricultural Land of Soil Environmental Quality" (GB15618-2018). The test results are shown in Table 2. The results in Table 2 show that the nano-modified organosilicon foam fire extinguishing agent did not cause significant damage to the organic matter, alkaline nitrogen, available phosphorus, available potassium, salt content and other indicators of farmland soil, among which the organic matter, alkaline nitrogen, salt content and other indicators increased. For the pollutants with risk screening values ​​or risk control value restrictions such as cadmium, mercury, arsenic, lead, chromium, copper, nickel, and zinc in GB15618-2018, since the foam fire extinguishing agent does not contain these pollutants, it will not cause such pollution to farmland.

[0047] Table 2 Nano-modified organic silicon foam fire extinguishing agent soil sample test table

[0048]

[0049]

[0050] Farmland irrigation water was used as a reference sample and comparison standard, and compared with water added with nano-modified organosilicon foam fire extinguishing agent. The test items mainly include 16 items including five-day biochemical oxygen demand, chemical oxygen demand, suspended solids, anionic surfactants, etc. The water samples used in this test were taken from Luo River in Weinan City, Shaanxi Province. A certain amount of river water sample was taken and divided into two equal parts, one of which was not treated in any way and was used as sample A. 20ml of foam liquid of foam fire extinguishing agent under normal temperature conditions and 1g of foam fire extinguishing agent residue after calcination were mixed and then added to another water sample as sample B. The water quality of the two samples was tested and compared according to the standard of farmland irrigation water. The test results are shown in Table 3. After inspection, the items tested in the two water samples all met the requirements of the National Farmland Irrigation Water Quality Standard (GB 5084-2005).

[0051] Table 3 Nano-modified organic silicon foam fire extinguishing agent water quality test report

[0052]

[0053]

[0054] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a nano-modified silicone foam fire extinguishing agent, characterized in that: The nano-modified silicone foam fire extinguishing agent comprises a silicone surfactant, a hydrocarbon surfactant, a foam stabilizer, nano-particles, and an antifreeze agent. Among them, by mass ratio, the silicone surfactant accounts for 1 wt% - 3 wt%, the hydrocarbon surfactant accounts for 0.2 wt% - 0.8 wt%, the foam stabilizer accounts for 0.6 wt% - 1.8 wt%, the nano-particles account for 0.5 wt% - 1.5 wt%, the antifreeze agent accounts for 1 wt% - 3 wt%, and the balance is water; the silicone surfactant is polyether-modified heptamethyltrisiloxane, the hydrocarbon surfactant is sodium α-olefin sulfonate, the foam stabilizer is a modified silicone resin polyether emulsion, the nano-particles are modified nano-silica, and the antifreeze agent is calcium chloride; The preparation method of the nano-modified silicone foam fire extinguishing agent is to mix polyether-modified heptamethyltrisiloxane, sodium α-olefin sulfonate and calcium chloride in proportion to form Component A. Mix the modified silicone resin polyether emulsion and water in proportion and stir. After it is fully dissolved, add a certain amount of modified nano-silica and stir to make it evenly dispersed to form Component B. Mix Component A and Component B fully and pour them into a pore plate foaming device for foaming to obtain the nano-modified silicone foam fire extinguishing agent.

2. The preparation method of the nano-modified silicone foam fire extinguishing agent according to claim 1, characterized in that: The content of each component in the nano-modified silicone foam fire extinguishing agent is that polyether-modified heptamethyltrisiloxane is 2.33 wt%, sodium α-olefin sulfonate is 0.64 wt%, the modified silicone resin polyether emulsion is 1.34 wt%, and the modified nano-silica is 0.98 wt%.

3. The preparation method of the nano-modified silicone foam fire extinguishing agent according to claim 2, characterized in that: The foaming multiple of the nano-modified silicone foam fire extinguishing agent is 11.5, and the 25% liquid separation time is 278.6 s.

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