Aerogel fire extinguishing agent and preparation method thereof

Abstract

An aerogel fire extinguishing agent is disclosed, comprising modified silica aerogel and silica sol; the aerogel is prepared by the following method: the silica aerogel is added to a polyethyleneimine aqueous solution with a pH of 5 and dispersed evenly to obtain a modified silica aerogel solution; the silica sol and cellulose hydroxyethyl ether are added successively and dispersed evenly. The fire extinguishing agent has higher fire extinguishing efficiency and better ignition prevention effect.

Description

Technical Field

[0001] The invention belongs to the field of surface functional materials and fire protection technology, and in particular relates to an aerogel fire extinguishing agent and a preparation method thereof. Background Art

[0002] As a natural fire extinguishing agent, water is widely used in fire fighting at various fire scenes. However, due to the strong fluidity of water, most of the water used for fire fighting is quickly lost the moment it comes into contact with the fire, and cannot really play a role in fire fighting. Studies have shown that the fire fighting efficiency of such fire extinguishing agents generally does not exceed 30%.

[0003] To this end, researchers at home and abroad have been committed to improving the jet morphology of water, such as blooming water, spray water, water vapor, etc., to enhance the fire extinguishing efficiency of water; at the same time, the fire extinguishing efficiency of water is also improved by adding antifreeze, wetting agents, enhancers, viscosity enhancers, etc. to water.

[0004] In the article “Flow Characteristics and Effects of Water Mist Fire Extinguishing Agents after Thickening and Modification by Nano-SiO2” (Chemical Industry Progress, 2009, 28, P199), Xi Yuqin added a thickener consisting of 60-70% nano-SiO2, 25% polyvinyl alcohol and 5% silicone oil to prepare an adhesive fire extinguishing agent. Under similar flow rates, the fire extinguishing time of the adhesive fire extinguishing agent is about a quarter of that of water extinguishing.

[0005] Suzhou Tongxuan New Materials Co., Ltd. disclosed a high-efficiency liquid composition fire extinguishing agent containing aerogel materials, its preparation method and application in Chinese patent application CN106310577A. The high-efficiency liquid composition fire extinguishing agent contains aerogel powder, water, surfactant, fire extinguishing enhancer, stabilizer and other components. The invention applies aerogel powder to the fire extinguishing agent. During the fire extinguishing, the aerogel powder and the fire extinguishing enhancer interact with each other and cover the surface of the substrate, effectively blocking heat transfer and preventing the spread of flames and heat. However, the aerogel powder used in the fire extinguishing agent is a hydrophobic powder, which is difficult to disperse evenly in the fire extinguishing agent, resulting in poor synergistic effect with the fire extinguishing enhancer.

[0006] Therefore, in view of the above-mentioned defects of the prior art, it is necessary to find an aerogel fire extinguishing agent with higher fire extinguishing efficiency and anti-ignition effect and a preparation method thereof. Summary of the invention

[0007] In view of the above problems, the present invention aims to provide an aerogel fire extinguishing agent and a preparation method thereof. Compared with the prior art, the aerogel fire extinguishing agent has higher fire extinguishing efficiency and better ignition prevention effect.

[0008] To achieve the above objectives, on the one hand, the present invention adopts the following technical scheme: an aerogel fire extinguishing agent, characterized in that it includes modified silica aerogel and silica sol.

[0009] According to the fire extinguishing agent of the present invention, the average pore size of the silica aerogel is 28 nm and the density is 0.043 g / cm 3 ;The thermal conductivity is 0.018W / (mK).

[0010] According to the fire extinguishing agent of the present invention, the modified silica aerogel is obtained by adding silica aerogel into a polyethyleneimine aqueous solution with a pH of 5 and dispersing the aerogel uniformly.

[0011] According to the fire extinguishing agent of the present invention, the content of the modified silica aerogel is 4-8wt%, which is calculated based on the ratio of the sum of the dry matter mass of the silica aerogel and polyethyleneimine to the mass of the fire extinguishing agent.

[0012] According to the fire extinguishing agent of the present invention, the preparation method of the silica aerogel is as follows: a sodium silicate solution is adjusted to pH ≥ 9 by dripping a 2M sulfuric acid solution until a gel phenomenon occurs, and aged at 55°C for 24 hours; washed with water three times, and then placed in anhydrous ethanol for solvent replacement, wherein the mass ratio of anhydrous ethanol to sodium silicate is 5:1; filtered and dried at normal pressure, dried at programmed temperature, and finally naturally cooled to obtain.

[0013] According to the fire extinguishing agent of the present invention, the programmed temperature rising mechanism is 80°C / 2h+100°C / 2h+120°C / 2h; the heating rate is 2°C / min.

[0014] According to the fire extinguishing agent of the present invention, the number average molecular weight Mn of the polyethyleneimine is 1800; the amine value is 19 mmol / g; the primary amine content is 35 mol%; the secondary amine content is 35 mol%; the tertiary amine content is 30 mol%; and / or the weight ratio of the polyethyleneimine to the silica aerogel is 1:(8-12).

[0015] According to the fire extinguishing agent of the present invention, the content of SiO2 in the silica sol is 10-30wt%; and / or the content of SiO2 in the silica sol is 10-20wt%.

[0016] According to the fire extinguishing agent of the present invention, the fire extinguishing agent further comprises cellulose hydroxyethyl ether.

[0017] According to the fire extinguishing agent of the present invention, the content of the cellulose hydroxyethyl ether is 1-3wt%; and / or the viscosity of a 2% aqueous solution of the cellulose hydroxyethyl ether at 20° C. is 2600-3300 mPa.s.

[0018] On the other hand, the present invention also provides a method for preparing the above-mentioned fire extinguishing agent, comprising:

[0019] The silica aerogel is added into a polyethyleneimine aqueous solution with a pH of 5 and dispersed uniformly to obtain a modified silica aerogel solution;

[0020] The silicon dioxide sol and cellulose hydroxyethyl ether are successively added thereto and dispersed evenly to obtain the fire extinguishing agent.

[0021] The beneficial effect of the present invention is that compared with the prior art, the fire extinguishing agent of the present invention not only has higher fire extinguishing efficiency, but also has better ignition prevention effect.

[0022] Without wishing to be bound by any theory, the present invention increases the above-mentioned beneficial effects of silica sol by using specific modified silica aerogel and cellulose hydroxyethyl ether. DETAILED DESCRIPTION

[0023] The following examples are intended only to provide a person of ordinary skill in the art with a complete disclosure and description of how to make and evaluate the compounds, compositions, articles, devices and / or methods described and claimed herein, and are intended to be exemplary only and not intended to limit the scope of the inventor's invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperatures, etc.), but some errors and deviations should be taken into account.

[0024] Unless otherwise indicated, parts are by weight, and the parts by weight are calculated based on the gross weight of the fire extinguishing agent. Temperatures are expressed in ° C or are at ambient temperature, and pressures are atmospheric pressure or near atmospheric pressure. There are multiple variations and combinations of reaction conditions (such as component concentrations, required solvents, solvent mixtures, temperature, pressure and other reaction ranges) and conditions that can be used to optimize the product purity and yield obtained by the method. Only reasonable routine experiments will be required to optimize such method conditions.

[0025] Example 1

[0026] Silica aerogel was prepared according to the following method: sodium silicate solution was adjusted to pH ≥ 9 by adding 2M sulfuric acid solution until gelation occurred, and aged at 55°C for 24h; washed with water 3 times, and then placed in anhydrous ethanol for solvent replacement, with the mass ratio of anhydrous ethanol to sodium silicate being 5:1; filtered, dried at normal pressure, dried at programmed temperature, and finally cooled naturally. The programmed temperature mechanism was 80°C / 2h+100°C / 2h+120°C / 2h; the heating rate was 2°C / min.

[0027] The average pore size of the silica aerogel is 28 nm, the density is 0.043 g / cm3, and the thermal conductivity is 0.018 W / (mK).

[0028] The silica aerogel is added to a polyethyleneimine aqueous solution with a pH of 5 and dispersed uniformly to obtain a modified silica aerogel solution; the polyethyleneimine has a number average molecular weight Mn of 1800; an amine value of 19 mmol / g; a primary amine content of 35 mol%; a secondary amine content of 35 mol%; and a tertiary amine content of 30 mol%. The weight ratio of the polyethyleneimine to the silica aerogel is 1:10; and the content of the modified silica aerogel is 6 wt%, calculated based on the total weight of the fire extinguishing agent.

[0029] The fire extinguishing agent is obtained by successively adding silica sol and cellulose hydroxyethyl ether into the modified silica aerogel solution and dispersing them uniformly.

[0030] In the fire extinguishing agent, the content of the silica sol is 15wt%; the content of SiO2 in the silica sol is 20wt%; the content of cellulose hydroxyethyl ether is 2wt%; and the viscosity of a 2% aqueous solution of the cellulose hydroxyethyl ether at 20°C is 2600-3300mpa.s.

[0031] Comparative Example 1

[0032] The silica aerogel was used directly without modification, and the other conditions were the same as those in Example 1.

[0033] Comparative Example 2

[0034] The cellulose hydroxyethyl ether was not added, and the other conditions were the same as those in Example 1.

[0035] Fire extinguishing performance test

[0036] According to the test conditions of Xi Yuqin's article, the fire extinguishing agents of Example 1 and Comparative Examples 1-2 were used for testing. The ignition time (average value) of the wood strips impregnated with the fire extinguishing agents of Example 1 and Comparative Examples 1-2 when in direct contact with the flame and the fire extinguishing time when the fire extinguishing agent flow rate was 0.027 kg / s and the wood ignition time was 60 s were measured respectively. The results are shown in Table 1.

[0037] Table 1

[0038] test Ignition time(s) Fire extinguishing time(s) Example 1 372 19 Comparative Example 1 296 28 Comparative Example 2 325 26

[0039] It can be seen from Table 1 that, compared with Comparative Examples 1-2, the fire extinguishing agent of Example 1 of the present invention not only has a higher fire extinguishing efficiency, but also has a better effect of preventing ignition.

[0040] It should be understood that the specific embodiments of the present invention are only used to illustrate the spirit and principles of the present invention, and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the content of the present invention, those skilled in the art can make various changes, substitutions, deletions, corrections or adjustments to the technical solutions of the present invention, and these equivalent technical solutions also fall within the scope defined by the claims of the present invention.

Claims

1. An aerogel fire extinguishing agent, characterized in that: It is composed of modified silica aerogel solution, silica sol and cellulose hydroxyethyl ether; The modified silica aerogel solution is obtained by adding silica aerogel to a polyethyleneimine aqueous solution with a pH of 5 and dispersing the solution uniformly; the average pore size of the silica aerogel is 28 nm; the density is 0.043 g / cm 3 ; The thermal conductivity is 0.018W / (mK); the number average molecular weight Mn of the polyethyleneimine is 1800; the amine value is 19mmol / g; the primary amine content is 35mol%; the secondary amine content is 35mol%; the tertiary amine content is 30mol%; the weight ratio of the polyethyleneimine to the silica aerogel is 1:(8-12); The SiO2 content in the silica sol is 10-30wt%; The viscosity of a 2% aqueous solution of the cellulose hydroxyethyl ether at 20° C. is 2600-3300 mPa.s; The content of the silica sol is 10-20wt%; the content of the modified silica aerogel is 4-8wt%; the content of the cellulose hydroxyethyl ether is 1-3wt%; the calculation is based on the ratio of the sum of the dry matter mass of the silica aerogel and the polyethyleneimine to the mass of the fire extinguishing agent; The preparation method of the silica aerogel is as follows: adjusting the pH of the sodium silicate solution to ≥ 9 by dropping a 2M sulfuric acid solution until gelation occurs, aging at 55°C for 24 hours; washing with water three times, and then placing in anhydrous ethanol for solvent replacement, wherein the mass ratio of anhydrous ethanol to sodium silicate is 5:1; filtering, drying at normal pressure, drying at programmed temperature, and finally cooling naturally to obtain the aerogel; The programmed temperature rise mechanism is 80°C / 2h+100°C / 2h+120°C / 2h; the heating rate is 2°C / min.

2. A method for preparing the fire extinguishing agent according to claim 1, comprising: The silica aerogel is added into a polyethyleneimine aqueous solution with a pH of 5 and dispersed uniformly to obtain a modified silica aerogel solution; Add silica sol and cellulose hydroxyethyl ether successively therein, and disperse them uniformly to obtain the fire extinguishing agent according to claim 1.