Hydrophobic and oleophobic dry powder extinguishing agent and preparation method thereof

Abstract

The invention discloses a hydrophobic and oleophobic dry powder extinguishing agent and a preparation method thereof. The method comprises the following steps: modifying the dry powder extinguishing agent by using a silane coupling agent in a solution through a sol-gel method to obtain a preliminarily modified dry powder extinguishing agent rich in silicon hydroxyl on the surface, and then adding the preliminarily modified dry powder extinguishing agent into a fluorine solvent containing long-chain perfluoropolyether silane for stirring modification to obtain the hydrophobic and oleophobic dry powder extinguishing agent. The preparation process is simple, and compared with a conventional hydrophobic and oleophobic dry powder extinguishing agent, the prepared hydrophobic and oleophobic dry powder extinguishing agent not only has hydrophobic and oleophobic effects, but also has the characteristics of no toxicity, harmlessness, environmental protection and degradability.

Description

Technical Field

[0001] The invention belongs to the technical field of ultrafine dry powder fire extinguishing agents and relates to a hydrophobic and oleophobic dry powder fire extinguishing agent and a preparation method thereof. Background Art

[0002] Dry powder fire extinguishing agent has high fire extinguishing efficiency, wide fire extinguishing range, and is environmentally friendly. Its ozone depletion potential (ODP) is 0, global warming potential (GWP) is 0, and atmospheric lifetime value (ALT) is 0. As one of the halon substitutes, it has been widely used in national production. Ultrafine dry powder fire extinguishing agent is based on ordinary dry powder fire extinguishing agent, and the particle size is ultra-fine, which significantly improves the fire extinguishing efficiency.

[0003] After the dry powder fire extinguishing agent is ultra-finely treated, the specific surface area increases, the surface energy is higher, and it is very easy to absorb moisture and agglomerate. Therefore, the ultra-fine dry powder fire extinguishing agent must be hydrophobic to prevent the powder from absorbing moisture. When extinguishing oil fires, ordinary dry powder fire extinguishing agents have strong lipophilicity. When the dry powder particles reach the oil surface, they will quickly sink below the oil surface, making the dry powder fire extinguishing agent unable to exert ideal fire extinguishing efficiency. Due to the sedimentation of the dry powder fire extinguishing agent in the oil, the dry powder fire extinguishing agent cannot cover the burning surface. There is still heat and material exchange of combustibles generated by fuel evaporation or decomposition in the upper and lower areas of the burning surface. Combustibles continue to accumulate above the burning surface, so the remaining small flames can easily cause the flame to reignite. Giving the dry powder fire extinguishing agent oleophobic properties can improve the fire extinguishing efficiency and anti-reignition performance of the dry powder fire extinguishing agent.

[0004] However, the hydrophobic and oleophobic modifiers currently used for dry powder fire extinguishing agents are mainly long-chain fluorocarbon compounds (fluorocarbon compounds with fluorine carbon atoms C ≥ 8). Long fluorocarbon chain compounds have become one of the most difficult to degrade organic pollutants in the world, with extremely high bioaccumulation and multiple toxicities. For example, patent CN 108314063 A discloses a method for preparing a hydrophobic and oleophobic BC-type dry powder fire extinguishing agent base material carbonate. The perfluorodecyl triethoxysilane modifier used can make the bicarbonate dry powder achieve excellent hydrophobic and oleophobic effects, but perfluorodecyl triethoxysilane is very difficult to degrade in nature and has extremely high bioaccumulation and toxicity. Although short-chain fluorocarbon compounds (C < 8) have biodegradable characteristics and are relatively easy to degrade, the oleophobic effect of their modified dry powder fire extinguishing agents is far inferior to that of long-chain fluorocarbon compounds. For example, patent CN 109078288A discloses an anti-reignition BC dry powder fire extinguishing agent and its preparation method, which uses sodium perfluorononenyloxybenzenesulfonate and silane coupling agent to modify the BC dry powder fire extinguishing agent, but the modified dry powder has average oleophobicity. Therefore, it is of great significance to find a modifier that can make the dry powder fire extinguishing agent have excellent hydrophobic and oleophobic effects while being easy to degrade.

[0005] Perfluoropolyether is a special polymer with only three elements, C, O, and F, in its molecular structure. Compared with perfluoroalkyl polymers, the insertion of oxygen atoms in the CC bond main chain structure of perfluoropolyether can create gaps in the shielding effect of fluorine atoms, making it easy for small molecules to enter, thus leading to the degradation of the fluoroether chain, and compounds containing fluoroether chains have no potential carcinogenic and teratogenic hazards. At the same time, due to the presence of fluorocarbon chains, the structure of perfluoropolyether is similar to that of perfluoroalkyl, so that perfluoropolyether still retains the advantages of low surface energy, high heat resistance and high chemical stability. Summary of the invention

[0006] The object of the present invention is to provide a hydrophobic and oleophobic dry powder fire extinguishing agent and a preparation method thereof.

[0007] The technical solution for achieving the purpose of the present invention is as follows:

[0008] The preparation method of a hydrophobic and oleophobic dry powder fire extinguishing agent comprises the following steps: reacting K-type perfluoropolyether acyl fluoride or perfluoropolyether methyl ester with aminosilane to synthesize a silane containing a relatively long perfluoropolyether chain segment, i.e., a long-chain perfluoropolyether silane; firstly modifying the dry powder fire extinguishing agent with a silane coupling agent in a solution by a sol-gel method to obtain a preliminarily modified dry powder fire extinguishing agent with a surface rich in silanol groups; and then adding the preliminarily modified dry powder fire extinguishing agent into a fluorine solvent containing a long-chain perfluoropolyether silane and stirring and modifying the preliminarily modified dry powder fire extinguishing agent to obtain a hydrophobic and oleophobic dry powder fire extinguishing agent. The specific steps are as follows:

[0009] Step 1, Synthesis of long-chain perfluoropolyether silane:

[0010] A fluorinated solvent, perfluoropolyether acyl fluoride and an acid binding agent are mixed, the temperature is raised to 45-60° C., and aminosilane in a molar amount of 1-1.1 times that of perfluoropolyether acyl fluoride is slowly added dropwise, and the mixture is stirred for reaction. After the reaction is completed, the mixture is cooled to room temperature, washed with water, and the organic phase is separated and distilled under reduced pressure to obtain a long-chain perfluoropolyether silane;

[0011] Or a fluorinated solvent, perfluoropolyether methyl ester and aminosilane in a molar amount of 1 to 1.1 times that of perfluoropolyether acyl fluoride are mixed, condensed and refluxed at 45 to 60° C. and stirred for reaction, cooled to room temperature after the reaction is completed, the product is purified by methanol precipitation, unreacted aminosilane is washed away, and vacuum distillation is performed to obtain a long-chain perfluoropolyether silane;

[0012] Step 2, preparation of hydrophobic and oleophobic dry powder fire extinguishing agent:

[0013] Based on 100 parts by total weight, the composition of the dry powder fire extinguishing agent includes: 75-90 parts by weight of a main component, 2-5 parts by weight of dry mica powder, 2-5 parts by weight of activated clay, 2-5 parts by weight of artificial zeolite, 2-5 parts by weight of nano calcium carbonate and 2-5 parts by weight of talcum powder. The main component, dry mica powder, activated clay, artificial zeolite, nano calcium carbonate and talcum powder are mixed and crushed until the D90 of the mixed powder is less than 10 μm, and the crushed mixed powder is mixed evenly to obtain an unmodified dry powder fire extinguishing agent;

[0014] Step 3, preliminary modification:

[0015] The amount of the silane coupling agent added is 8% to 10% of the unmodified dry powder fire extinguishing agent, the unmodified dry powder fire extinguishing agent and the silane coupling agent are added to a mixed solution consisting of water and an organic solvent, and the mixture is preliminarily modified at 40° C. to 60° C. under stirring conditions, washed, and dried to obtain a preliminarily modified dry powder fire extinguishing agent, wherein the silane coupling agent is tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, or tetraisopropyl orthosilicate;

[0016] Step 4, secondary modification:

[0017] After diluting the long-chain perfluoropolyether silane with a fluorine-containing solvent, the preliminarily modified dry powder fire extinguishing agent is added, and secondary modification is performed at 40-60° C. under stirring conditions. After suction filtration, washing, drying and sieving, a hydrophobic and oleophobic dry powder fire extinguishing agent is obtained.

[0018] Preferably, in step 1, the weight average molecular weight M of the perfluoropolyether acyl fluoride or perfluoropolyether methyl ester is w =1000~5000g / mol, more preferably M w =3000~4000g / mol.

[0019] Preferably, in step 1, the acid binding agent is triethylamine, pyridine, sodium carbonate, potassium carbonate, sodium acetate or potassium acetate, more preferably triethylamine or pyridine.

[0020] Preferably, in step 1, the fluorine-containing solvent is trichlorotrifluoroethane, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, perfluorocyclic ether, perfluorohexane or dichlorodifluoroethane, more preferably methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, perfluorocyclic ether or perfluorohexane.

[0021] Preferably, in step 1, the aminosilane is γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane or γ-aminopropylmethyldiethoxysilane.

[0022] Preferably, in step 1, the reaction time is 4 to 6 hours.

[0023] Preferably, in step 2, the main component is a main component commonly used in dry powder fire extinguishing agents, selected from sodium bicarbonate, potassium bicarbonate, diammonium phosphate or ammonium polyphosphate.

[0024] Preferably, in step 2, in the mixed solution consisting of water and the organic solvent, the volume ratio of water to the organic solvent is 1:20; the organic solvent is ethanol, n-propanol, isopropanol or ethylene glycol, more preferably ethanol or ethylene glycol.

[0025] Preferably, in step 3, the initial modification time is 4 to 6 hours.

[0026] Preferably, in step 4, the fluorine-containing solvent is trichlorotrifluoroethane, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether or perfluorohexane, more preferably methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether or perfluorohexane.

[0027] Preferably, in step 4, the secondary modification time is 10 h.

[0028] The present invention firstly performs preliminary modification on the dry powder fire extinguishing agent by using a silane coupling agent such as tetraethyl orthosilicate to obtain a silica-coated dry powder fire extinguishing agent having a shell-core structure, the surface of which is rough and has silanol groups, providing reaction binding sites for the surface modification of perfluoropolyether silane in the next step. The preliminarily modified dry powder fire extinguishing agent is modified by using perfluoropolyether silane, and the siloxane groups on the surface of the perfluoropolyether silane can undergo a condensation reaction with the silanol groups on the surface of the dry powder fire extinguishing agent, and finally an oleophobic and hydrophobic dry powder fire extinguishing agent with a surface grafted perfluoropolyether silane is obtained.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] (1) The present invention can obtain a hydrophobic and oleophobic dry powder fire extinguishing agent by a sol-gel method at 40-60° C. The modification method is simple and easy, and is suitable for expanded production and industrial application;

[0031] (2) The modifier used in the present invention is a long-chain perfluoropolyether silane, which can give the dry powder fire extinguishing agent relatively excellent hydrophobic and oleophobic properties, with high modification efficiency. In addition, the long-chain perfluoropolyether silane has no bioaccumulation, is biodegradable, and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a scanning electron microscope image of the hydrophobic and oleophobic dry powder fire extinguishing agent prepared in Example 1.

[0033] Figure 2 This is a test diagram of the hydrophobic angle of the hydrophobic and oleophobic dry powder fire extinguishing agent prepared in Example 2.

[0034] Figure 3 This is a test diagram of the oleophobic angle of the hydrophobic and oleophobic dry powder fire extinguishing agent prepared in Example 2.

[0035] Figure 4 This is a diagram of the hydrophobic and oleophobic dry powder fire extinguishing agent prepared in Example 5 extinguishing aviation kerosene fire.

[0036] Figure 5 This is a diagram of the hydrophobic and oleophobic dry powder fire extinguishing agent prepared in Example 5 extinguishing aviation kerosene fire.

[0037] Figure 6 This is a diagram of the hydrophobic and oleophobic dry powder fire extinguishing agent prepared in Example 5 extinguishing aviation kerosene fire. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments and drawings. The described embodiments are only 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.

[0039] In the following examples, perfluoropolyether acyl fluoride and perfluoropolyether methyl ester were purchased from Suzhou Cangmu New Materials Co., Ltd., and long-chain perfluoropolyether silane was prepared according to patent CN 114369412 A.

[0040] Example 1

[0041] (1) Synthesis of long-chain perfluoropolyether silane

[0042] According to perfluoropolyether fluoride (PFPE-COF, M w =3000g / mol), γ-aminopropyltriethoxysilane (KH550) and triethylamine (TEA) in a ratio of 1:1.1:1.1, weigh 3g PFPE-COF, 0.244g KH550, 0.111g TEA and 6g trichlorotrifluoroethane, then slowly add trichlorotrifluoroethane, PFPE-COF and TEA into a dry three-necked flask in sequence, stir magnetically to mix thoroughly and heat to 45°C, slowly add KH550 dropwise, and stir to react for 4h. After the reaction is completed, cool to room temperature, wash away the generated salt and other impurities with deionized water, then separate the organic phase, and distill the solution under reduced pressure to obtain perfluoropolyether silane PFPE-1, the structural formula of which is as follows:

[0043]

[0044] (2) Preparation of hydrophobic and oleophobic dry powder fire extinguishing agent

[0045] Sodium bicarbonate, dry mica powder, activated clay, artificial zeolite, nano calcium carbonate and talc are mixed in a mass ratio of 85%:4%:3%:2%:3%:3%, the mixture is crushed in a jet mill so that D90 of the mixed powder is less than 10 μm, and the crushed mixed powder is mixed at high speed in a high-speed mixer to obtain an unmodified dry powder fire extinguishing agent.

[0046] 30g of unmodified dry powder fire extinguishing agent and 2.4g of tetraethyl orthosilicate were added to a mixture containing 5ml of deionized water and 100ml of ethanol, and magnetically stirred for 6h at 40°C. After the reaction was completed, the solution was washed and dried to obtain a preliminarily modified dry powder fire extinguishing agent.

[0047] Weigh 1g of PFPE-1 and add it to 80g of trichlorotrifluoroethane, then add the preliminarily modified dry powder fire extinguishing agent, and stir mechanically at 40°C for 10h. After the reaction is completed, most of the solvent is distilled off, and the dry powder fire extinguishing agent is dried at 60°C for 10h after filtration and washing, and then sieved to obtain a hydrophobic and oleophobic dry powder fire extinguishing agent.

[0048] Weigh 2g of the hydrophobic and oleophobic dry powder fire extinguishing agent obtained in Example 1, pour it into a beaker filled with deionized water / aviation kerosene, stir for 1 minute, recover the fire extinguishing agent floating on the water / oil surface and attached to the beaker wall, put it into an oven for drying, and weigh its mass m (g). The hydrophobicity / oleophobicity is calculated according to the following formula:

[0049] Hydrophobicity (oil) rate = (m / 2) × 100%

[0050] After testing and calculation, the hydrophobicity and oleophobicity dry powder fire extinguishing agent obtained in Example 1 has a hydrophobicity of 80.6% and an oleophobicity of 63.1%.

[0051] Example 2

[0052] (1) Synthesis of long-chain perfluoropolyether silane

[0053] According to perfluoropolyether fluoride (PFPE-COF, M w=3000g / mol), N-(β-aminoethyl)-γ-aminopropyltriethoxysilane and triethylamine (TEA) in a ratio of 1:1:1, weigh 3g PFPE-COF, 0.265g N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, 0.102g TEA and 10g trichlorotrifluoroethane, then slowly add trichlorotrifluoroethane, PFPE-COF and TEA into a dry three-necked flask in sequence, stir magnetically to mix thoroughly and heat to 60°C, slowly drop N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, and stir to react for 6h. After the reaction is completed, cool to room temperature, wash away the generated salt and other impurities with deionized water, then separate the organic phase, and distill the solution under reduced pressure to obtain perfluoropolyether silane PFPE-2, the structural formula of which is as follows:

[0054]

[0055] (2) Preparation of hydrophobic and oleophobic dry powder fire extinguishing agent

[0056] Sodium bicarbonate, dry mica powder, activated clay, artificial zeolite, nano calcium carbonate and talc are mixed in a mass ratio of 85%:4%:3%:2%:3%:3%, the mixture is crushed in a jet mill so that D90 of the mixed powder is less than 10 μm, and the crushed mixed powder is mixed at high speed in a high-speed mixer to obtain an unmodified dry powder fire extinguishing agent.

[0057] 30g of unmodified dry powder fire extinguishing agent and 3g of tetraethyl orthosilicate were added to a mixture containing 5ml of deionized water and 100ml of ethanol, and magnetically stirred for 6h at 40°C. After the reaction, the solution was washed and dried to obtain a preliminarily modified dry powder fire extinguishing agent (rich in silanol groups on the surface).

[0058] Weigh 2g of PFPE-2 and add it to 80g of trichlorotrifluoroethane, then add the preliminarily modified dry powder fire extinguishing agent, and stir mechanically at 40°C for 10h. After the reaction is completed, distill off most of the solvent, filter and wash, then dry the dry powder fire extinguishing agent at 60°C for 10h, and sieve to obtain a hydrophobic and oleophobic dry powder fire extinguishing agent.

[0059] After testing and calculation, the hydrophobicity and oleophobicity dry powder fire extinguishing agent obtained in Example 2 has a hydrophobicity of 92.3% and an oleophobicity of 76.6%.

[0060] Example 3

[0061] (1) Synthesis of long-chain perfluoropolyether silane

[0062] The raw materials and methods required for the synthesis are exactly the same as those in Example 2, and perfluoropolyether silane PFPE-2 is obtained.

[0063] (2) Preparation of hydrophobic and oleophobic dry powder fire extinguishing agent

[0064] Ammonium dihydrogen phosphate, dry mica powder, activated clay, artificial zeolite, nano calcium carbonate and talc are mixed in a mass ratio of 75%:5%:5%:5%:5%:5%, the mixture is crushed in a jet mill so that D90 of the mixed powder is less than 10 μm, and the crushed mixed powder is mixed at high speed in a high-speed mixer to obtain an unmodified dry powder fire extinguishing agent.

[0065] 30g of unmodified dry powder fire extinguishing agent and 3g of tetraethyl orthosilicate were added to a mixture containing 5ml of deionized water and 100ml of ethanol, and magnetically stirred for 4h at 60°C. After the reaction was completed, the solution was washed and dried to obtain a preliminarily modified dry powder fire extinguishing agent.

[0066] 2g PFPE-2 was added to 80g methyl nonafluorobutyl ether, and then the preliminarily modified dry powder fire extinguishing agent was added, and mechanical stirring was performed at 60°C for 10h. After the reaction was completed, most of the solvent was distilled off, and the dry powder fire extinguishing agent was dried at 60°C for 10h after filtration and washing, and then sieved to obtain a hydrophobic and oleophobic dry powder fire extinguishing agent.

[0067] After testing and calculation, the hydrophobic and oleophobic dry powder fire extinguishing agent obtained in Example 3 has a hydrophobicity of 90.1% and an oleophobicity of 74.7%.

[0068] Example 4

[0069] (1) Synthesis of long-chain perfluoropolyether silane

[0070] According to perfluoropolyether methyl ester (M w =4000g / mol), γ-aminopropyltriethoxysilane (KH550) in a ratio of 1:1.1, weigh 3g perfluoropolyether methyl ester, 0.183g KH550 and 6g methyl nonafluorobutyl ether, then add methyl nonafluorobutyl ether, perfluoropolyether methyl ester and KH550 into a dry three-necked flask in sequence, stir magnetically to mix thoroughly and heat to 45°C for 4h. After the reaction is completed, cool to room temperature, purify the product by methanol precipitation, wash off the unreacted aminosilane, and obtain long-chain perfluoropolyether silane PFPE-3 after reduced pressure distillation, the structural formula is as follows:

[0071]

[0072] (2) Preparation of hydrophobic and oleophobic dry powder fire extinguishing agent

[0073] Sodium bicarbonate, dry mica powder, activated clay, artificial zeolite, nano calcium carbonate and talc are mixed in a mass ratio of 90%:2%:2%:2%:2%:2%, the mixture is crushed in a jet mill so that D90 of the mixed powder is less than 10 μm, and the crushed mixed powder is mixed at high speed in a high-speed mixer to obtain an unmodified dry powder fire extinguishing agent.

[0074] 30g of unmodified dry powder fire extinguishing agent and 3g of tetraethyl orthosilicate were added to a mixture containing 5ml of deionized water and 100ml of ethanol, and magnetically stirred for 6h at 40°C. After the reaction was completed, the solution was washed and dried to obtain a preliminarily modified dry powder fire extinguishing agent.

[0075] Weigh 2g of PFPE-3 and add it to 70g of methyl nonafluorobutyl ether, then add the preliminarily modified dry powder fire extinguishing agent, and stir mechanically at 40°C for 10h. After the reaction is completed, most of the solvent is distilled off, and the dry powder fire extinguishing agent is dried at 60°C for 10h after filtration and washing, and then sieved to obtain a hydrophobic and oleophobic dry powder fire extinguishing agent.

[0076] After testing and calculation, the hydrophobicity and oleophobicity dry powder fire extinguishing agent obtained in Example 4 has a hydrophobicity of 93.5% and an oleophobicity of 81.2%.

[0077] Example 5

[0078] (1) Synthesis of long-chain perfluoropolyether silane

[0079] According to perfluoropolyether methyl ester (M w =4000g / mol), N-(β-aminoethyl)-γ-aminopropyltriethoxysilane in a ratio of 1:1, weigh 3g perfluoropolyether methyl ester, 0.199g N-(β-aminoethyl)-γ-aminopropyltriethoxysilane and 6g methyl nonafluorobutyl ether, then add methyl nonafluorobutyl ether, perfluoropolyether methyl ester and KH550 into a dry three-necked flask in sequence, stir magnetically to mix thoroughly and heat to 60°C for 6h. After the reaction is completed, cool to room temperature, purify the product by methanol precipitation, wash off the unreacted aminosilane, and obtain long-chain perfluoropolyether silane PFPE-4 after reduced pressure distillation, the structural formula is as follows:

[0080]

[0081] (2) Preparation of hydrophobic and oleophobic dry powder fire extinguishing agent

[0082] Sodium bicarbonate, dry mica powder, activated clay, artificial zeolite, nano calcium carbonate and talc are mixed in a mass ratio of 90%:2%:2%:2%:2%:2%, the mixture is crushed in a jet mill so that D90 of the mixed powder is less than 10 μm, and the crushed mixed powder is mixed at high speed in a high-speed mixer to obtain an unmodified dry powder fire extinguishing agent.

[0083] 30g of unmodified dry powder fire extinguishing agent and 3g of tetraethyl orthosilicate were added to a mixture containing 5ml of deionized water and 100ml of ethanol, and magnetically stirred for 6h at 40°C. After the reaction was completed, the solution was washed and dried to obtain a preliminarily modified dry powder fire extinguishing agent.

[0084] Weigh 2g of PFPE-4 and add it to 60g of methyl nonafluorobutyl ether, then add the preliminarily modified dry powder fire extinguishing agent, and stir mechanically at 40°C for 10h. After the reaction is completed, most of the solvent is distilled off, and the dry powder fire extinguishing agent is dried at 60°C for 10h after filtration and washing, and then sieved to obtain a hydrophobic and oleophobic dry powder fire extinguishing agent.

[0085] After testing and calculation, the hydrophobic and oleophobic dry powder fire extinguishing agent obtained in Example 5 has a hydrophobicity of 94.8% and an oleophobicity of 83.7%.

[0086] The fire extinguishing performance of the hydrophobic and oleophobic dry powder fire extinguishing agent obtained in Example 5 was tested by extinguishing aviation kerosene fire, specifically: three oil pans with a diameter of 4 cm were placed at different positions in a 50cm×40cm×50cm fire extinguishing box, 30g of the hydrophobic and oleophobic dry powder fire extinguishing agent was placed in a fire extinguishing bottle connected with a leather hose and pressurized to 0.8MPa with nitrogen, and the leather hose was inserted into the fire extinguishing box through the opening above the fire extinguishing box and fixed. After the aviation kerosene in the three oil pans was ignited, the fire extinguishing box door was closed, and the dry powder was sprayed after the flame was stabilized after pre-burning for 30s. The time from spraying the dry powder to the extinguishing of the fires in the three oil pans was recorded by high-speed photography, which was the fire extinguishing time. The fire extinguishing time was 0.36s (see Figure 4 , Figure 5 , Figure 6 ).

[0087] Comparative Example 1

[0088] This comparative example is an unmodified dry powder fire extinguishing agent, which is as follows:

[0089] Sodium bicarbonate, dry mica powder, activated clay, artificial zeolite, nano calcium carbonate and talc are mixed in a mass ratio of 85%:4%:3%:2%:3%:3%, the mixture is crushed in a jet mill so that D90 of the mixed powder is less than 10 μm, and the crushed mixed powder is mixed at high speed in a high-speed mixer to obtain an unmodified dry powder fire extinguishing agent.

[0090] After testing and calculation, the unmodified dry powder fire extinguishing agent in Comparative Example 1 has a hydrophobicity of 0% and an oleophobicity of 0%.

[0091] The fire extinguishing performance was tested by extinguishing the aviation kerosene fire. Three oil pans with a diameter of 4 cm were placed at different positions in a 50cm×40cm×50cm fire extinguishing box. 30g of unmodified dry powder fire extinguishing agent was placed in a fire extinguishing bottle with a leather hose and pressurized to 0.8MPa with nitrogen. The leather hose was inserted into the fire extinguishing box through the opening above the fire extinguishing box and fixed. After the aviation kerosene in the three oil pans was ignited, the fire extinguishing box door was closed. After the flame was stabilized for 30s, the dry powder was sprayed. The time from spraying the dry powder to the extinguishing of the fire in the three oil pans was recorded by high-speed photography, which was the fire extinguishing time. The fire extinguishing time was 0.51s.

[0092] Comparative Example 2

[0093] This comparative example is substantially the same as Example 2, except that no silane coupling agent is used for preliminary modification, and PFPE-2 is directly used to modify the dry powder fire extinguishing agent, specifically:

[0094] (1) Synthesis of long-chain perfluoropolyether silane

[0095] The raw materials and methods required for the synthesis are exactly the same as those in Example 2, and perfluoropolyether silane PFPE-2 is obtained.

[0096] (2) Preparation of hydrophobic and oleophobic dry powder fire extinguishing agent

[0097] Sodium bicarbonate, dry mica powder, activated clay, artificial zeolite, nano calcium carbonate and talc are mixed in a mass ratio of 85%:4%:3%:2%:3%:3%, the mixture is crushed in a jet mill so that D90 of the mixed powder is less than 10 μm, and the crushed mixed powder is mixed at high speed in a high-speed mixer to obtain an unmodified dry powder fire extinguishing agent.

[0098] Weigh 2g of PFPE-2 and add it to 80g of trichlorotrifluoroethane, then add unmodified dry powder fire extinguishing agent, and stir mechanically at 40°C for 10h. After the reaction is completed, most of the solvent is distilled off, filtered and washed, and then the dry powder fire extinguishing agent is dried at 60°C for 10h, and then sieved to obtain a hydrophobic and oleophobic dry powder fire extinguishing agent.

[0099] Through testing and calculation, the hydrophobicity and oleophobicity dry powder fire extinguishing agent obtained in Comparative Example 2 has a hydrophobicity of 73.6% and an oleophobicity of 50.3%.

[0100] Comparative Example 3

[0101] (1) Synthesis of long-chain perfluoropolyether silane

[0102] The raw materials and methods required for the synthesis are exactly the same as those in Example 4, and perfluoropolyether silane PFPE-3 is obtained.

[0103] (2) Preparation of hydrophobic and oleophobic dry powder fire extinguishing agent

[0104] Sodium bicarbonate, dry mica powder, activated clay, artificial zeolite, nano calcium carbonate and talc are mixed in a mass ratio of 90%:2%:2%:2%:2%:2%, the mixture is crushed in a jet mill so that D90 of the mixed powder is less than 10 μm, and the crushed mixed powder is mixed at high speed in a high-speed mixer to obtain an unmodified dry powder fire extinguishing agent.

[0105] 30g of unmodified dry powder fire extinguishing agent and 4g of tetraethyl orthosilicate were added to a mixture containing 5ml of deionized water and 100ml of ethanol, and magnetically stirred for 6h at 40°C. After the reaction was completed, the solution was washed and dried to obtain a preliminarily modified dry powder fire extinguishing agent.

[0106] Weigh 2g of PFPE-3 and add it to 70g of methyl nonafluorobutyl ether, then add the preliminarily modified dry powder fire extinguishing agent, and stir mechanically at 40°C for 10h. After the reaction is completed, most of the solvent is distilled off, and the dry powder fire extinguishing agent is dried at 60°C for 10h after filtration and washing, and then sieved to obtain a hydrophobic and oleophobic dry powder fire extinguishing agent.

[0107] Through testing and calculation, the hydrophobic and oleophobic dry powder fire extinguishing agent obtained in Comparative Example 3 has a hydrophobicity of 80.1% and an oleophobicity of 8.8%.

[0108] The five hydrophobic and oleophobic dry powder fire extinguishing agents obtained in Examples 1-5 and the dry powder fire extinguishing agents obtained in Comparative Examples 1-3 were prepared into a flat and uniform surface, and the contact angles of the eight powders with deionized water and aviation kerosene were measured. The relevant data obtained are shown in Tables 1 and 2 below.

[0109] Table 1 Contact angle of dry powder fire extinguishing agent obtained in each embodiment

[0110] Test Type Example 1 Example 2 Example 3 Example 4 Example 5 Water contact angle 132.31° 145.62° 143.86° 144.19° 146.77° Oil contact angle 123.01° 141.76° 140.32° 143.72° 144.67°

[0111] Table 2 Contact angle of dry powder fire extinguishing agent obtained in each comparative example

[0112] Test Type Comparative Example 1 Comparative Example 2 Comparative Example 3 Water contact angle 30.15° 130.56° 134.58° Oil contact angle 0° 121.39° 120.93°

[0113] It can be seen from Table 1 and Table 2 that after modification with an appropriate amount of silane coupling agent and long-chain perfluoropolyether silane, the hydrophobicity and oleophobicity of the dry powder fire extinguishing agent are improved; without using a silane coupling agent, the hydrophobicity and oleophobicity of the dry powder fire extinguishing agent directly modified with long-chain perfluoropolyether silane cannot achieve the optimal effect; when an excessive amount of silane coupling agent is used for modification, the oleophobicity of the dry powder fire extinguishing agent will decrease.

Claims

1. A method for preparing a hydrophobic and oleophobic dry powder fire extinguishing agent, characterized in that: The specific steps are as follows: Step 1, Synthesis of long-chain perfluoropolyether silane: A fluorinated solvent, perfluoropolyether acyl fluoride and an acid binding agent are mixed, the temperature is raised to 45-60°C, and an aminosilane whose molar amount is 1-1.1 times of the perfluoropolyether acyl fluoride is slowly added dropwise, and the mixture is stirred for reaction. After the reaction is completed, the mixture is cooled to room temperature, washed with water, and the organic phase is separated and distilled under reduced pressure to obtain a long-chain perfluoropolyether silane; Or a fluorinated solvent, perfluoropolyether methyl ester and aminosilane whose molar amount is 1 to 1.1 times of perfluoropolyether acyl fluoride are mixed, condensed and refluxed at 45 to 60° C. and stirred for reaction, after the reaction is completed, cooled to room temperature, the product is purified by methanol precipitation method, unreacted aminosilane is washed away, and vacuum distillation is performed to obtain a long-chain perfluoropolyether silane; Step 2, preparation of hydrophobic and oleophobic dry powder fire extinguishing agent: Based on 100 parts by total weight, the composition of the dry powder fire extinguishing agent includes: 75-90 parts by weight of a main component, 2-5 parts by weight of dry mica powder, 2-5 parts by weight of activated clay, 2-5 parts by weight of artificial zeolite, 2-5 parts by weight of nano calcium carbonate and 2-5 parts by weight of talcum powder. The main component, dry mica powder, activated clay, artificial zeolite, nano calcium carbonate and talcum powder are mixed and crushed until the D90 of the mixed powder is less than 10 μm, and the crushed mixed powder is mixed evenly to obtain an unmodified dry powder fire extinguishing agent; Step 3, preliminary modification: The amount of the silane coupling agent added is 8% to 10% of the unmodified dry powder fire extinguishing agent, the unmodified dry powder fire extinguishing agent and the silane coupling agent are added to a mixed solution consisting of water and an organic solvent, and preliminary modification is performed at 40° C. to 60° C. under stirring conditions, followed by washing and drying to obtain a preliminary modified dry powder fire extinguishing agent, wherein the silane coupling agent is tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate or tetraisopropyl orthosilicate; Step 4, secondary modification: After the long-chain perfluoropolyether silane is diluted with a fluorine-containing solvent, the initially modified dry powder fire extinguishing agent is added, and a secondary modification is performed at 40-60° C. under stirring conditions. After suction filtration, washing, drying and sieving, a hydrophobic and oleophobic dry powder fire extinguishing agent is obtained.

2. The preparation method according to claim 1, characterized in that: In step 1, the weight average molecular weight M of the perfluoropolyether acyl fluoride or perfluoropolyether methyl ester is w =1000~5000g / mol.

3. The preparation method according to claim 1, characterized in that: In step 1, the weight average molecular weight M of the perfluoropolyether acyl fluoride or perfluoropolyether methyl ester is w =3000~4000g / mol.

4. The preparation method according to claim 1, characterized in that: In step 1, the acid binding agent is triethylamine, pyridine, sodium carbonate, potassium carbonate, sodium acetate or potassium acetate, the fluorine-containing solvent is trichlorotrifluoroethane, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, perfluorocyclic ether, perfluorohexane or dichlorodifluoroethane, and the aminosilane is γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane or γ-aminopropylmethyldiethoxysilane.

5. The preparation method according to claim 1, characterized in that: In step 1, the reaction time is 4 to 6 hours.

6. The preparation method according to claim 1, characterized in that: In step 2, the main component is selected from sodium bicarbonate, potassium bicarbonate, ammonium dihydrogen phosphate or ammonium polyphosphate.

7. The preparation method according to claim 1, characterized in that: In step 2, in the mixed solution consisting of water and an organic solvent, the volume ratio of water to the organic solvent is 1:20; the organic solvent is ethanol, n-propanol, isopropanol or ethylene glycol.

8. The preparation method according to claim 1, characterized in that: In step 4, the fluorine-containing solvent is trichlorotrifluoroethane, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether or perfluorohexane.

9. The preparation method according to claim 1, characterized in that: In step 3, the initial modification time is 4 to 6 hours; in step 4, the secondary modification time is 10 hours.

10. A hydrophobic and oleophobic dry powder fire extinguishing agent prepared according to the preparation method according to any one of claims 1 to 9.

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