A method for preparing fire extinguishing microcapsules with organic-inorganic hybrid wall layers

Abstract

This invention relates to the field of fire extinguishing materials and discloses a method for preparing fire extinguishing microcapsules with an organic-inorganic hybrid wall layer, comprising: S1: mixing and stirring a fire extinguishing agent, an emulsifier, and an inorganic silicon source and / or an inorganic titanium source; adding the resulting mixed oil phase to water and stirring to obtain a homogeneous emulsion; S2: adding a polymer prepolymer solution to the emulsion, adjusting the system to acidity, stirring the reaction, and then filtering, washing, and drying to obtain fire extinguishing microcapsules with a fire extinguishing agent as the core material and an inorganic nanoparticle-polymer as the wall material. The fire extinguishing microcapsules prepared by this invention, with a fire extinguishing agent as the core material and an inorganic nanoparticle-polymer as the wall material, have the characteristics of fast response speed and good storage stability.

Description

Technical Field

[0001] This invention relates to the field of fire extinguishing materials, and more particularly to a method for preparing fire extinguishing microcapsules with an organic-inorganic hybrid wall layer. Background Technology

[0002] Microencapsulation technology is a technique that uses organic or inorganic substances to encapsulate liquid or solid internal materials to create capsules. Microencapsulation can protect the internal material from external environmental stimuli such as humidity, pressure, or temperature, or selectively release the internal material based on changes in these external environmental factors. Methods for preparing microcapsules include agglomeration, interfacial polymerization, and in-situ methods, and the appropriate method is selected based on the physical and chemical properties of the internal material or its interaction with the outer wall material.

[0003] Microcapsules offer numerous advantages, including protecting sensitive substances from deterioration and serving as a controlled-release mechanism for active substances. They are widely used in pharmaceuticals, fire protection, cosmetics, coatings, printed electronics, and adhesives. In the fire protection field, a known fire extinguishing composition utilizes microcapsules containing an outer wall made of polymers such as gelatin and a core material of a fire extinguishing agent.

[0004] However, according to existing technologies, microcapsules based on polymer outer walls, such as gelatin, suffer from low mechanical strength and low thermal conductivity. This low thermal conductivity delays heat transfer during a fire, becoming a significant factor hindering rapid fire suppression, thus requiring improvement. While adding inorganic components can increase shell rigidity to some extent, it necessitates additional support materials, such as polymer sheets, and has the disadvantage of being difficult to use alone.

[0005] In summary, existing fire extinguishing microcapsules have drawbacks such as slow response speed and poor storage stability. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for preparing fire extinguishing microcapsules with an organic-inorganic hybrid wall layer. The fire extinguishing microcapsules prepared by this method use a fire extinguishing agent as the core material and inorganic nanoparticles-polymers as the wall material, exhibiting characteristics of rapid response and good storage stability.

[0007] The specific technical solution of this invention is as follows:

[0008] In a first aspect, the present invention provides a method for preparing fire extinguishing microcapsules with an organic-inorganic hybrid wall layer, comprising:

[0009] S1: Mix the extinguishing agent, emulsifier and inorganic silicon source and / or inorganic titanium source, add the resulting mixed oil phase to water and stir to obtain a uniform emulsion.

[0010] S2: Add the polymer prepolymer solution to the emulsion, adjust the system to be acidic, stir the reaction, and after filtration, washing and drying, obtain fire extinguishing microcapsules with fire extinguishing agent as core material and inorganic nanoparticle-polymer as wall material.

[0011] In S1, the present invention first mixes the extinguishing agent, emulsifier and inorganic silicon source and / or inorganic titanium source into a uniform emulsion. The hydrophobic chain of the emulsifier encapsulates the extinguishing agent, inorganic silicon source and / or inorganic titanium source inside, and the hydrophilic end combines with water molecules, so that the mixed system gradually forms a stable oil-in-water emulsion.

[0012] In step S2, the present invention adds a polymer prepolymer solution to an emulsion. The polymer prepolymer aggregates on the surface of the emulsion droplets and undergoes in-situ polymerization to transform into a polymer, thereby forming a polymer-encapsulated microcapsule of the emulsion droplets. During this process, the inorganic silicon source and / or inorganic titanium source in the emulsion droplets gradually diffuse into the polymer shell and hydrolyze into inorganic nanoparticles under acidic conditions, thereby forming an organic-inorganic hybrid wall layer. Finally, a fire extinguishing microcapsule with a fire extinguishing agent as the core material and inorganic nanoparticle-polymer as the wall material is produced.

[0013] To address the drawbacks of microcapsules prepared with a single organic shell, such as poor solvent resistance, poor weather resistance, low mechanical properties, and poor responsiveness (low thermal conductivity), and microcapsules prepared with a single inorganic shell, such as poor responsiveness (high response temperature) and difficulty in controlling the reaction, this invention employs an in-situ generation method to prepare fire extinguishing microcapsules with an organic-inorganic hybrid wall material. The presence of the polymer ensures that the microcapsule wall material can rupture rapidly upon heating, while the introduction of inorganic nanoparticles enhances the mechanical properties of the wall material and prevents leakage of the internal fire extinguishing agent. Furthermore, the appropriate amount of inorganic nanoparticles dispersed within the polymer wall material can increase the thermal conductivity of the wall material without significantly raising the response temperature (inorganic nanoparticles have higher thermal conductivity than polymers, but their response temperature is also higher). Therefore, the method of this invention can significantly improve the response speed and storage stability of fire extinguishing microcapsules.

[0014] Preferably, the emulsifier is a nonionic or cationic emulsifier with HLB=8-18, specifically selected from one or more of polyvinyl alcohol, polyoxyethylene ether, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide and octadecylamine polyoxyethylene ether bisquaternary ammonium salt; more preferably, the emulsifier is a cationic emulsifier.

[0015] During the preparation process of this invention, it was found that anionic emulsifiers cannot exist stably under acidic conditions. Therefore, nonionic or cationic emulsifiers are preferred. Cationic emulsifiers are even more preferred because inorganic silicon sources and / or inorganic titanium sources produce negatively charged weakly acidic silicic acid and / or titanic acid intermediates during hydrolysis. Cationic emulsifiers can stabilize these intermediates in the shell through charge action and further undergo condensation reactions to form silica and / or titanium dioxide nanoparticles. Therefore, the inorganic silicon sources and / or inorganic titanium sources in the shell are enriched in the shell through diffusion, which can prevent a large amount of inorganic silicon sources and / or inorganic titanium sources from remaining in the core material and thus failing to generate inorganic nanoparticles.

[0016] Preferably, the polymer is one or more selected from polyurethane, epoxy resin, phenolic resin, acrylic resin, furan resin, resorcinol-formaldehyde resin, xylene-formaldehyde resin, melamine-formaldehyde resin, unsaturated polyester resin, and urea-formaldehyde resin. More preferably, it is waterborne unsaturated polyester resin, sulfonated melamine-formaldehyde resin, and sulfonated urea-formaldehyde resin.

[0017] Because the prepolymers of the aforementioned resins have good water solubility and require no additional curing agent, they can spontaneously cure under acidic conditions. Furthermore, when a cationic emulsifier is preferred, and prepolymers of waterborne unsaturated polyester resin, sulfonated melamine-formaldehyde resin, and sulfonated urea-formaldehyde resin are simultaneously preferred, the prepolymers, due to the presence of sulfonic acid groups, are electronegative. This allows them to rapidly aggregate and anchor to the emulsion surface via charge interaction with the cationic emulsifier, resulting in cross-linking and curing, thus achieving even better results.

[0018] Preferably, the extinguishing agent is selected from one or more of perfluorohexanone, heptafluoropropane, perfluorohexane, tetrafluorodibromoethane, trifluorodichloroethane, and perfluorobutyl methyl ether.

[0019] Preferably, the inorganic silicon source is ethyl silicate, and the inorganic titanium source is tetrabutyl titanate; the inorganic nanoparticles are silicon dioxide and / or titanium dioxide formed by hydrolysis of the inorganic silicon source and / or the inorganic titanium source.

[0020] Preferably, in the above preparation method, the fire extinguishing agent is 100 parts by weight, the emulsifier is 1-10 parts by weight, the inorganic silicon source and / or inorganic titanium source is 1-5 parts by weight, the water is 100-500 parts by weight, and the polymer prepolymer is 10-20 parts by weight.

[0021] This invention reveals that, in the aforementioned raw materials, the amount of emulsifier in step S2 has a crucial impact on whether the inorganic silicon source or inorganic titanium source can sufficiently diffuse into the polymer shell. If the emulsifier is excessively applied, its coating effect on the inorganic silicon source and / or inorganic titanium source is too strong, hindering the diffusion of the inorganic silicon source or inorganic titanium source. Consequently, the inorganic silicon source or inorganic titanium source cannot fully contact the acid to form inorganic nanoparticles.

[0022] Preferably, in S2, the pH is adjusted to 3.0-6.0.

[0023] Preferably, in S2, the reaction temperature is 30-50℃ and the reaction time is 4.0-8.0h.

[0024] Secondly, the present invention provides fire extinguishing microcapsules with organic-inorganic hybrid wall layers obtained by the above preparation method, which have a response speed of less than or equal to 5 seconds, a mass loss of less than 5% within 30 days, and a mass loss of less than 8% within 60 days.

[0025] Preferably, the particle size of the above-mentioned fire extinguishing microcapsules is 10-200μm, and the fire extinguishing trigger temperature is 80-180℃.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) The present invention uses an in-situ generation method to prepare fire extinguishing microcapsules with fire extinguishing agent as core material and inorganic nanoparticle-polymer as wall material, which can significantly improve the response speed and storage stability of fire extinguishing microcapsules.

[0028] (2) By optimizing the type / amount of emulsifier and reaction conditions, this invention can further improve the response speed and storage stability of fire extinguishing microcapsules. Attached Figure Description

[0029] Figure 1 This is a SEM image of the fire extinguishing microcapsules prepared in Example 1 of the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to embodiments.

[0031] General Implementation Examples

[0032] A method for preparing fire extinguishing microcapsules with an organic-inorganic hybrid wall layer includes:

[0033] S1: Mix the extinguishing agent, emulsifier and inorganic silicon source and / or inorganic titanium source, add the resulting mixed oil phase to water and stir to obtain a uniform emulsion.

[0034] In some specific embodiments, the emulsifier is a nonionic emulsifier or a cationic emulsifier with HLB=8-18, specifically selected from one or more of polyvinyl alcohol, polyoxyethylene ether, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide and octadecylamine polyoxyethylene ether bisquaternary ammonium salt; more preferably, the emulsifier is a cationic emulsifier.

[0035] In some specific embodiments, the extinguishing agent is selected from one or more of perfluorohexanone, heptafluoropropane, perfluorohexane, tetrafluorodibromoethane, trifluorodichloroethane, and perfluorobutyl methyl ether.

[0036] In some specific embodiments, the inorganic silicon source is ethyl silicate, and the inorganic titanium source is tetrabutyl titanate.

[0037] In some specific embodiments, in S1, the stirring rate is 1000-10000 r / min.

[0038] S2: Add the polymer prepolymer solution to the emulsion, adjust the system to be acidic, stir the reaction, and after filtration, washing and drying, obtain fire extinguishing microcapsules with fire extinguishing agent as core material and inorganic nanoparticle-polymer as wall material.

[0039] In some specific embodiments, the polymer is one or more selected from polyurethane, epoxy resin, phenolic resin, acrylic resin, furan resin, resorcinol-formaldehyde resin, xylene-formaldehyde resin, melamine-formaldehyde resin, unsaturated polyester resin, and urea-formaldehyde resin; more preferably, water-soluble unsaturated polyester resin, sulfonated melamine-formaldehyde resin, and sulfonated urea-formaldehyde resin; the inorganic nanoparticles are silicon dioxide and / or titanium dioxide formed by hydrolysis of inorganic silicon source and / or inorganic titanium source.

[0040] In some specific embodiments, in the above preparation method, the fire extinguishing agent is 100 parts by weight, the emulsifier is 1-10 parts by weight, the inorganic silicon source and / or inorganic titanium source is 1-5 parts by weight, the water is 100-500 parts by weight, and the polymer prepolymer is 10-20 parts by weight.

[0041] In some specific implementations, in S2, the pH is adjusted to 3.0-6.0.

[0042] In some specific embodiments, in S2, the reagent for adjusting pH includes one or more of hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, and citric acid.

[0043] In some specific implementations, in S2, the reaction temperature is 30-50°C and the reaction time is 4.0-8.0 h.

[0044] The fire extinguishing microcapsules with organic-inorganic hybrid wall layers obtained by the above preparation method have a particle size of 10-200 μm, a fire extinguishing trigger temperature of 80-180℃, a response speed of less than or equal to 5 seconds, a mass loss of less than 5% within 30 days, and a mass loss of less than 8% within 60 days.

[0045] Specific embodiments and comparative examples

[0046] Example 1

[0047] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g hexadecyltrimethylammonium bromide and 1.0g tetraethyl orthosilicate, stir evenly and add to 400g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0048] (2) Preparation of sulfonated urea-formaldehyde resin prepolymer: Weigh 18.0g urea, 24.3g formaldehyde solution, 31.2g sodium bisulfite and 127.7g deionized water and add them to a three-necked flask. Add triethanolamine to adjust the pH of the solution to 8.5 and heat to 70℃ and keep it at that temperature for 1h. Dilute with 100g deionized water to obtain a 10% sulfonated urea-formaldehyde resin prepolymer solution.

[0049] (3) Preparation of microcapsules: 100g of sulfonated urea-formaldehyde resin prepolymer solution was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with hydrochloric acid, and stirring was continued at 30℃ for 6h. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the obtained microcapsules were dried to obtain the final product. The SEM image is shown below. Figure 1 As shown.

[0050] Example 2

[0051] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g hexadecyltrimethylammonium bromide and 1.0g tetraethyl orthosilicate, stir evenly and add to 300g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0052] (2) Preparation of microcapsules: 200g of a 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with hydrochloric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0053] Example 3

[0054] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g cetyltrimethylammonium bromide and 5.0g tetraethyl orthosilicate, stir evenly and add to 400g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0055] (2) Preparation of microcapsules: 100g of a 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with hydrochloric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0056] Example 4

[0057] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g dodecyltrimethylammonium chloride and 5.0g tetraethyl orthosilicate, stir evenly and add to 300g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0058] (2) Preparation of microcapsules: 200g of 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with sulfuric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0059] Example 5

[0060] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g dodecyltrimethylammonium chloride and 5.0g tetraethyl orthosilicate, stir evenly and add to 300g deionized water, stir at 5000r / min for 30min to form a uniform emulsion.

[0061] (2) Preparation of microcapsules: 200g of 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with sulfuric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0062] Example 6

[0063] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g dodecyltrimethylammonium chloride and 5.0g tetraethyl orthosilicate, stir evenly and add to 300g deionized water, stir at 10000r / min for 30min to form a uniform emulsion.

[0064] (2) Preparation of microcapsules: 200g of 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with sulfuric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0065] Example 7

[0066] (1) Emulsion preparation: Take 100g heptafluoropropane, 5.0g octadecyltrimethylammonium bromide and 5.0g tetraethyl orthosilicate, stir evenly and add to 300g deionized water, stir at 10000r / min for 30min to form a uniform emulsion.

[0067] (2) Under a nitrogen atmosphere, 10.4 g of methylene succinic acid, 4.7 g of sodium methyl succinate-5-sulfonate, 9.5 g of 1,4-dihydroxybutane and 0.02 g of stannous chloride were weighed and reacted at 180 °C for 2 h. Then, a polycondensation reaction was carried out at a pressure of -0.1 MPa for 5 h. After the reaction was completed, the mixture was cooled and extracted with a mixture of deionized water and anhydrous ethanol. Finally, the product was dissolved in 221.4 g of deionized water, and 0.01 g of ammonium persulfate and 0.01 g of sodium bisulfite were added to prepare a 10% aqueous unsaturated polyester prepolymer solution.

[0068] (3) Preparation of microcapsules: 200g of 10% aqueous unsaturated polyester prepolymer solution was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 4.0 with sulfuric acid, and the mixture was stirred at 40℃ for 4h. Finally, heating and stirring were stopped, the resulting solution was filtered, washed with water 3 times, and the resulting microcapsules were dried to obtain the final product.

[0069] Example 8

[0070] (1) Emulsion preparation: Take 100g heptafluoropropane, 5.0g octadecyltrimethylammonium bromide and 5.0g tetrabutyl titanate, stir evenly and add to 300g deionized water, stir at 10000r / min for 30min to form a uniform emulsion.

[0071] (2) Preparation of microcapsules: 200g of a 10% aqueous unsaturated polyester prepolymer solution (prepared by the same method as in Example 7) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 4.0 with sulfuric acid, and the mixture was stirred at 40°C for 4 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0072] Example 9

[0073] (1) Emulsion preparation: Take 100g perfluorohexane, 5.0g octadecyltrimethylammonium bromide and 5.0g tetrabutyl titanate, stir evenly and add to 300g deionized water, stir at 10000r / min for 30min to form a uniform emulsion.

[0074] (2) Preparation of microcapsules: 200g of a 10% aqueous unsaturated polyester prepolymer solution (prepared by the same method as in Example 7) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 4.0 with sulfuric acid, and the mixture was stirred at 40°C for 4 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0075] Example 10

[0076] (1) Emulsion preparation: Take 100g perfluorohexane, 5.0g octadecyl polyoxyethylene ether quaternary ammonium salt and 5.0g tetrabutyl titanate, stir evenly and add to 300g deionized water, stir at 5000r / min for 30min to form a uniform emulsion.

[0077] (2) Preparation of microcapsules: 200g of 10% aqueous unsaturated polyester prepolymer solution (preparation method as in Example 7) was slowly added dropwise to the emulsion. The pH was adjusted to 4.0 with sulfuric acid, and the mixture was stirred at 40°C for 8 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0078] Example 11

[0079] (1) Emulsion preparation: Take 100g tetrafluorodibromoethane, 10.0g octadecyl polyoxyethylene ether bisquaternary ammonium salt and 5.0g tetrabutyl titanate, stir evenly and add to 300g deionized water, stir at a rate of 5000r / min for 30min to form a uniform emulsion.

[0080] (2) Preparation of sulfonated melamine-formaldehyde resin prepolymer: Weigh 18.0g urea, 24.3g formaldehyde solution, 31.2g sodium bisulfite and 305.9g deionized water and add them to a three-necked flask. Add triethanolamine to adjust the pH of the solution to 8.5 and heat to 70℃ and keep it at that temperature for 1h. Dilute with 100g deionized water to obtain a 10% sulfonated melamine-formaldehyde resin prepolymer solution.

[0081] (3) Preparation of microcapsules: 200g of 10% sulfonated melamine-formaldehyde resin prepolymer solution was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 5.0 with phosphoric acid, and the mixture was stirred at 50℃ for 8 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0082] Example 12

[0083] (1) Emulsion preparation: Take 100g trifluorodichloroethane, 10.0g octadecyl polyoxyethylene ether bisquaternary ammonium salt and 1.0g tetrabutyl titanate, stir evenly and add to 400g deionized water, stir at 5000r / min for 30min to form a uniform emulsion.

[0084] (2) Preparation of microcapsules: 100g of a 10% sulfonated melamine-formaldehyde resin prepolymer solution (preparation method as in Example 11) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 5.0 with phosphoric acid, and the mixture was stirred at 50°C for 8 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0085] Example 13

[0086] (1) Emulsion preparation: Take 100g perfluorobutyl methyl ether, 10.0g octadecyl polyoxyethylene ether bisquaternary ammonium salt and 1.0g tetrabutyl titanate, stir evenly and add to 500g deionized water, stir at a rate of 5000r / min for 30min to form a uniform emulsion.

[0087] (2) Preparation of microcapsules: 100g of a 10% sulfonated melamine-formaldehyde resin prepolymer solution (preparation method as in Example 11) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 5.0 with phosphoric acid, and the mixture was stirred at 50°C for 8 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0088] Comparative Example 1 (Hybrid wall layer without the introduction of inorganic nanoparticles)

[0089] (1) Emulsion preparation: Take 100g perfluorohexanone and 1.0g cetyltrimethylammonium bromide, stir evenly and add to 400g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0090] (2) Preparation of microcapsules: 100g of a 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with hydrochloric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0091] Comparative Example 2 (No Polymer)

[0092] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g cetyltrimethylammonium bromide and 10g tetraethyl orthosilicate, stir evenly and add to 500g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0093] (2) Preparation of microcapsules: The pH of the emulsion was adjusted to 3.0 with hydrochloric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the microcapsules were dried to obtain the final product.

[0094] Comparative Example 3 (using inorganic nanoparticles directly)

[0095] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g hexadecyltrimethylammonium bromide and 1.0g silica powder, stir evenly and add to 400g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0096] (2) Preparation of microcapsules: 100g of a 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with hydrochloric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0097] Comparative Example 4 (using anionic emulsifier)

[0098] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g sodium dodecylbenzenesulfonate and 1.0g tetraethyl orthosilicate, stir evenly and add to 400g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0099] (2) Preparation of microcapsules: 100g of a 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with hydrochloric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0100] Comparative Example 5 (using emulsifier with HLB value = 4.3)

[0101] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g Span 80 (HLB=4.3) and 1.0g tetraethyl orthosilicate, stir evenly and add to 400g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0102] (2) Preparation of microcapsules: 100g of a 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with hydrochloric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0103] Comparative Example 6 (reaction pH = 2.0)

[0104] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g hexadecyltrimethylammonium bromide and 1.0g tetraethyl orthosilicate, stir evenly and add to 400g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0105] (2) Preparation of microcapsules: 100g of a 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 2.0 with hydrochloric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0106] Comparative Example 7 (reaction temperature 20℃)

[0107] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g hexadecyltrimethylammonium bromide and 1.0g tetraethyl orthosilicate, stir evenly and add to 400g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0108] (2) Preparation of microcapsules: 100g of a 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with hydrochloric acid, and stirring was continued at 20°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0109] Comparative Example 8 (emulsifier dosage: 15.0g)

[0110] (1) Emulsion preparation: Take 100g perfluorohexanone, 15.0g hexadecyltrimethylammonium bromide and 1.0g tetraethyl orthosilicate, stir evenly and add to 400g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0111] (2) Preparation of microcapsules: 100g of a 10% sulfonated urea-formaldehyde resin prepolymer solution (preparation method as in Example 1) was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with hydrochloric acid, and the mixture was stirred at 30°C for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed three times with water, and the resulting microcapsules were dried to obtain the final product.

[0112] Comparative Example 9 (non-sulfonated resin)

[0113] (1) Emulsion preparation: Take 100g perfluorohexanone, 1.0g hexadecyltrimethylammonium bromide and 1.0g tetraethyl orthosilicate, stir evenly and add to 400g deionized water, stir at 1000r / min for 30min to form a uniform emulsion.

[0114] (2) Preparation of urea-formaldehyde resin prepolymer: Weigh 18.0g of urea, 24.3g of formaldehyde solution and 127.7g of deionized water and add them to a three-necked flask. Add triethanolamine to adjust the pH of the solution to 8.5 and heat to 70℃ and keep it at that temperature for 1h. Dilute with 100g of deionized water to obtain a 10% urea-formaldehyde resin prepolymer solution.

[0115] (3) Preparation of microcapsules: 100g of 10% urea-formaldehyde resin prepolymer solution was slowly added to the emulsion at a rate of 10g / min. The pH was adjusted to 3.0 with hydrochloric acid, and the mixture was stirred at 30℃ for 6 hours. Finally, heating and stirring were stopped, the resulting solution was filtered, washed with water 3 times, and the resulting microcapsules were dried to obtain the final product.

[0116] Performance testing

[0117] The testing methods for each performance aspect are as follows:

[0118] (1) The particle size of the fire extinguishing microcapsules prepared in the examples and comparative examples was determined by a particle size analyzer. The results are shown in Table 2.

[0119] (2) The loading rate of the fire extinguishing microcapsules prepared in the examples and comparative examples was determined by GC-MS. The results are shown in Table 2.

[0120] (3) The response temperature of the fire extinguishing microcapsules prepared by the TGA test examples and comparative examples is shown in Table 2.

[0121] (4) Ignite 5g of gasoline in the crucible, add 2.0g of the fire extinguishing microcapsule prepared in the example or comparative example, and record the time it takes for the flame to extinguish as the response time. See Table 2 for the results.

[0122] (5) The weight of the fire extinguishing microcapsules prepared in the examples or comparative examples after being stored at 50°C for 30 days and 60 days is recorded as M2. The mass loss of the fire extinguishing microcapsules is calculated according to the formula (mass loss = (M1-M2) / M1×100%). The results are shown in Table 2.

[0123] Table 1: Summary of solutions for each embodiment and comparative example

[0124]

[0125]

[0126] Table 2: Performance test results of fire extinguishing microcapsules prepared in each embodiment and comparative example

[0127]

[0128]

[0129] As can be seen from the data in Table 2:

[0130] The fire extinguishing microcapsules obtained in Examples 1-13 and Comparative Examples 6-7 of this invention all have a fast response speed, and therefore have the effect of quickly suppressing flames.

[0131] In Comparative Example 1, the fire extinguishing microcapsule wall material had poor mechanical properties and weather resistance due to the lack of inorganic nanoparticles, resulting in poor storage stability. In Comparative Example 2, the fire extinguishing microcapsule wall material did not have polymers introduced. Although the pure inorganic nanomaterial wall material had a high thermal conductivity, its response temperature was too high, thus it did not have the ability to extinguish fires quickly (response speed).

[0132] In Comparative Example 3, silica powder was directly introduced through physical blending. As a result, a large amount of silica powder was present in the core layer and it was difficult to migrate to the polymer shell layer. Therefore, the response speed and storage stability of the resulting fire extinguishing microcapsules were not as good as those in Example 1.

[0133] Comparative Example 4 used sodium dodecylbenzenesulfonate as an anionic emulsifier, which is unstable in acidic systems, leading to demulsification and leakage of the fire extinguishing agent during the reaction, thus preventing the formation of microcapsules. Comparative Example 5 used Span 80 as an emulsifier with an HLB value of 4.3, which could not form a stable oil-in-water emulsion system, and therefore could not form microcapsules either.

[0134] In Comparative Example 6, the system pH was 2.0, and in Comparative Example 7, the reaction temperature was 20℃. Both resulted in the formation of an excessively thin microcapsule shell. Although the reaction speed was relatively fast, the storage stability was poor.

[0135] In Comparative Example 8, the excessive amount of emulsifier made it difficult for tetraethyl orthosilicate to migrate into the polymer wall material, thus preventing it from being fully hydrolyzed to form silica nanoparticles, ultimately resulting in poor response speed and storage stability.

[0136] Comparative Example 9 used non-sulfonated resin, which made it difficult for the polymer to quickly and fully aggregate and anchor to the outer layer of the emulsifier, resulting in a thinner wall material, lower microcapsule encapsulation rate, and poor storage stability.

[0137] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0138] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing fire extinguishing microcapsules with an organic-inorganic hybrid wall layer, characterized in that... include: S1: Mix the fire extinguishing agent, emulsifier and inorganic silicon source and / or inorganic titanium source to obtain a mixed oil phase. Add the obtained mixed oil phase to water and stir to obtain a uniform emulsion. S2: Add the polymer prepolymer solution to the emulsion, adjust the system to be acidic, stir the reaction, and after filtration, washing and drying, obtain fire extinguishing microcapsules with fire extinguishing agent as core material and inorganic nanoparticle-polymer as wall material; The emulsifier is a nonionic emulsifier or a cationic emulsifier with a hydrophilic-lipophilic balance value of 8-18; The polymer is one or more selected from polyurethane, epoxy resin, phenolic resin, acrylic resin, furan resin, xylene-formaldehyde resin, melamine-formaldehyde resin, unsaturated polyester resin, and urea-formaldehyde resin; The inorganic nanoparticles are silicon dioxide and / or titanium dioxide formed by hydrolysis of inorganic silicon source and / or inorganic titanium source.

2. The preparation method according to claim 1, characterized in that: The fire extinguishing agent is 100 parts by weight, the emulsifier is 1-10 parts by weight, the inorganic silicon source and / or inorganic titanium source is 1-5 parts by weight, the water is 100-500 parts by weight, and the polymer prepolymer is 10-20 parts by weight.

3. The preparation method according to claim 1 or 2, characterized in that: The extinguishing agent is selected from one or more of perfluorohexanone, heptafluoropropane, perfluorohexane, tetrafluorodibromoethane, trifluorodichloroethane, and perfluorobutyl methyl ether.

4. The preparation method according to claim 1 or 2, characterized in that: The emulsifier is one or more of polyvinyl alcohol, polyoxyethylene ether, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide and octadecylamine polyoxyethylene ether bisquaternary ammonium salt.

5. The preparation method according to claim 4, characterized in that: The emulsifier is a cationic emulsifier.

6. The preparation method according to claim 4, characterized in that: The polymer is selected from water-based unsaturated polyester resin, sulfonated melamine-formaldehyde resin, and sulfonated urea-formaldehyde resin.

7. The preparation method according to claim 1 or 2, characterized in that: In S2, adjust the pH to 3.0-6.

0.

8. The preparation method according to claim 1 or 2, characterized in that: In S2, the reaction temperature is 30-50℃ and the reaction time is 4.0-8.0h.

9. A fire extinguishing microcapsule with an organic-inorganic hybrid wall layer obtained by the preparation method according to any one of claims 1-8, characterized in that: The response time is less than or equal to 5 seconds, the quality loss is less than 5% within 30 days, and the quality loss is less than 8% within 60 days.

10. The fire extinguishing microcapsule with an organic-inorganic hybrid wall layer according to claim 9, characterized in that: The particle size is 10-200μm, and the extinguishing trigger temperature is 80-180℃.

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