Double-shell fire extinguishing microcapsule and preparation method thereof

Abstract

The invention discloses a double-shell-layer fire extinguishing microcapsule. The double-shell-layer fire extinguishing microcapsule comprises a core material, a first shell layer and a second shell layer, wherein the core material is coated with the first shell layer, and the first shell layer is coated with the second shell layer. By optimizing the components of the core material, reducing the volatility of the core material, improving the coating rate and arranging the double-layer microcapsule structure, the first shell layer can be formed under the low-temperature condition and is excellent in compactness, escape of the core material in the reaction can be effectively reduced, the coating rate and the yield of the microcapsule are further improved, and after full crosslinking, the product yield is improved. The second shell layer can further improve the mechanical performance of the microcapsule, the hydrophobicity and compactness of the second shell layer are beneficial for preventing polyurea and melamine resin from absorbing water and deliquescing and preventing formaldehyde harmful substances from being continuously released, the safety of the microcapsule is improved, and the microcapsule has a wider application scene and can quickly respond to the fire temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of fire extinguishing agents, and in particular, to a double-shell fire extinguishing microcapsule and a preparation method thereof. Background Art

[0002] All kinds of fires occur in our country every year, causing huge economic losses. Among various fire situations, electrical fires account for the highest proportion. Among the fire sites, residential fires occur relatively frequently. For places with centralized monitoring, the traditional independent fire monitoring and extinguishing system is sufficient, but for distributed and flammable items such as vehicle-mounted batteries, household appliances, and distribution cabinets, centralized management is impossible. If a fire breaks out and cannot be detected and handled in time, it will cause greater disasters. Therefore, it is necessary to develop a new type of independent fire extinguisher, which must have the ability to respond independently and immediately deal with scattered fires for effective control. Coating items prone to fire with a coating having flame retardant and fire extinguishing functions is an effective method. Among them, compounding microcapsules with fire extinguishing functions into the coatings of the above products has been a research hotspot in recent years.

[0003] For example, the Russian patent RU2162520 in the prior art introduces a microcapsule preparation technology with gelatin material as the outer shell and perfluoromethylcyclohexanone and other fluorine-containing reagents as the core material. Another example is that the US patent US9968813, the Chinese patents CN109453491 and CN113230577A introduce embedding new type of halon replacement fire extinguishing agents such as perfluoromethylcyclohexanone and heptafluoropropane into urea-formaldehyde or melamine resin. However, the conventional preparation temperature of urea-formaldehyde and melamine resin is relatively high, which will cause the volatilization of the core material. In addition, due to the use of formaldehyde as a cross-linking agent, the shell material will contain a part of formaldehyde that is easy to free and release, which is harmful to life and health. In addition to the traditional single-shell fire extinguishing microcapsules, for example, the patent RU2899168A discloses a preparation method of a microcapsule with a double-layer coating of a halogenated hydrocarbon fire extinguishing agent, using a gelatin-modified amino resin composite material as the first layer of the capsule wall and an acrylate polymer as the second layer of the capsule wall. The patent RU2015133303A discloses a preparation method of a fire extinguishing agent, using gelatin as the first layer of the shell and resorcinol and formaldehyde as the second layer of the shell. The double shell makes the microcapsule have better mechanical strength and compactness, but the use of raw materials such as gelatin also leads to an increase in cost.

[0004] The commercial application of fire-extinguishing microcapsules requires consideration of various aspects such as cost, environmental protection, and substrate compatibility. Using materials such as gelatin has the advantage of environmental safety, but it also causes the problem of high cost; choosing traditional urea-formaldehyde resin and melamine resin has a lower cost, but formaldehyde toxic substances are continuously released during long-term storage, which is not conducive to safety requirements. Moreover, fire-extinguishing microcapsules are added to the substrate as an auxiliary agent, and while meeting the requirements of low cost and environmental protection, they should also have good compatibility. Since most substrates contain some chemical substances that are extremely likely to react chemically with the shell layer such as amino groups and hydroxyl groups, this causes the microcapsules to agglomerate in the substrate and destroys their stability. In addition, when the self-density of the microcapsules differs greatly from the density of the substrate, phase separation will occur, which is not conducive to the uniform distribution of the microcapsules in the substrate and affects the aesthetics of the substrate and the fire-extinguishing performance of the microcapsules. Therefore, developing a double-shell microcapsule that can be well compatible with the substrate is of great significance for preventing various sudden fires. Summary of the Invention

[0005] Based on this, in order to solve the problems in the prior art that the core material of the fire-extinguishing microcapsule is prone to volatilization when heated, the reaction temperature of the shell layer is limited, resulting in low cross-linking degree of the shell material; polyurea and melamine resin release toxic substances such as formaldehyde, which is not conducive to environmental protection; and the shell layer of the microcapsule contains a large number of groups such as hydroxyl groups and amino groups, which are prone to agglomeration in the substrate and affect the performance, the present invention provides a double-shell fire-extinguishing microcapsule and its preparation method. The specific technical solutions are as follows:

[0006] A double-shell fire-extinguishing microcapsule, the double-shell fire-extinguishing microcapsule includes a core material, a first shell layer covering the core material, and a second shell layer wrapping the first shell layer;

[0007] Among them, the preparation raw materials of the core material are at least one of perfluoromethyl hexanone, 1,2-tetrafluorodibromoethane, methyl nonafluorobutyl ether, and 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl) pentane;

[0008] The first shell layer is at least one of urea-formaldehyde resin, melamine resin, and urea-melamine resin copolymer;

[0009] The preparation raw materials of the second shell layer include at least one of polymethyl methacrylate and polysulfone.

[0010] In addition, the present invention also provides a preparation method of a double-shell fire-extinguishing microcapsule, and the preparation method includes the following steps:

[0011] Prepare a prepolymer;

[0012] Add an emulsifier to water, heat and dissolve it, and adjust the pH to obtain an emulsifier solution;

[0013] Add the raw materials for preparing the core material to the prepolymer, then add the emulsifier solution, and carry out stirring treatment under the first stirring condition to obtain a mixture;

[0014] Formation of the first shell layer: Add an auxiliary agent to the mixture, add a pH regulator, slowly raise the temperature of the system, after the reaction, filter the microcapsules, adjust the pH to neutral, wash with water multiple times, and then fully dry to form the first shell layer coating the core material;

[0015] Formation of the second shell layer: Disperse the dried material forming the first shell layer coating the core material in water containing a dispersant, and slowly add it to a solution containing polymethyl methacrylate and / or polysulfone under stirring conditions, and keep stirring at room temperature until the solvent volatilizes completely to form the second shell layer coating the first shell layer.

[0016] Furthermore, the mass ratio of the first shell layer to the core material is (0.5 - 1):1; the mass ratio of the second shell layer to the first shell layer is 1:(10 - 20).

[0017] Furthermore, the molar ratio of aldehyde group to amino group is 1.8:1 - 2.2:1.

[0018] Furthermore, the reaction time in the step of preparing the prepolymer is 60 min - 90 min.

[0019] Furthermore, the emulsifier is at least one of sodium dodecylbenzenesulfonate, gum arabic, polyvinyl maleic anhydride, polystyrene maleic anhydride, and polyvinyl alcohol.

[0020] Furthermore, the concentration of the emulsifier solution is 0.8 wt% - 2 wt%.

[0021] Furthermore, the rotation speed under the first condition is 100 r / min - 800 r / min, the temperature is 0 - 25 °C, and the time is 10 min - 30 min.

[0022] Furthermore, in the step of forming the first shell layer, add a pH regulator to control the initial pH at 3 - 4, the reaction temperature is programmed heating, the temperature range is 0 - 50 °C, the total reaction duration is 6 h, and the rotation speed is 300 - 600 r / min.

[0023] Furthermore, in the step of forming the second shell layer, the dispersant is at least one of polyacrylamide, carboxymethyl cellulose, polyvinylpyrrolidone, and polyvinyl alcohol.

[0024] In the above solution, by optimizing the composition of the core material, the high-boiling fire extinguishing agent composition, reducing the volatility of the core material, and improving the coating rate, and then by setting a double-layer microcapsule structure, the urea-formaldehyde and melamine resin of the first shell layer can be formed under low-temperature conditions, and have excellent compactness, which can effectively reduce the escape of the core material during the reaction, thereby improving the coating rate and the yield of microcapsules. After sufficient cross-linking, it is insoluble and infusible and has significant flame retardant properties. The second shell layer is wrapped on the first shell layer with raw materials of polymethyl methacrylate and polysulfone, which can further improve the mechanical properties of the microcapsules. Its hydrophobicity and compactness help prevent the polyurea and melamine resin from absorbing water and deliquescing, and prevent the continuous release of harmful substances such as formaldehyde, improving the safety of the microcapsules.

[0025] In the present invention, the second shell layer covers the hydroxyl and amino groups containing active hydrogen in the first shell layer, which is beneficial to the compounding of the microcapsules with various substrates, enabling it to have a wider range of application scenarios, such as being widely used in fire protection scenarios of furniture, electrical cabinets, wires, and batteries, etc.

[0026] The double-layer fire extinguishing microcapsules of the present invention can quickly respond to the fire temperature. When the ambient temperature reaches 95 °C, the microcapsules quickly rupture, release the fire extinguishing agent, and can quickly extinguish the fire autonomously within 20 s without reigniting.

[0027] The overall process for preparing the double-layer fire extinguishing microcapsules of the present invention is simple, has strong repeatability, and the overall raw material price is low, which helps to reduce the production cost. Description of the Drawings

[0028] Figure 1 It is a schematic diagram of the electron microscope scan of the double-shell fire extinguishing microcapsules prepared in Example 1. Detailed Embodiments

[0029] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further details the present invention in conjunction with its embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the protection scope of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0031] A double-shell fire extinguishing microcapsule in an embodiment of the present invention, the double-shell fire extinguishing microcapsule includes a core material, a first shell layer covering the core material, and a second shell layer wrapping the first shell layer;

[0032] Among them, the raw materials for preparing the core material are at least one of perfluoropentanone, 1,2-tetrafluorodibromoethane, methyl nonafluorobutyl ether, and 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl) pentane;

[0033] The first shell layer is at least one of urea-formaldehyde resin, melamine resin, and urea-melamine resin copolymer;

[0034] The raw materials for preparing the second shell layer include at least one of polymethyl methacrylate and polysulfone.

[0035] In addition, the present invention also provides a method for preparing the double-shell fire-extinguishing microcapsules, and the preparation method includes the following steps:

[0036] Prepare a prepolymer;

[0037] Add an emulsifier to water, heat and dissolve it, and adjust the pH for the third time to obtain an emulsifier solution;

[0038] Add the raw materials for preparing the core material to the prepolymer, then add the emulsifier solution, and carry out stirring treatment under the first stirring condition to obtain a mixture;

[0039] Formation of the first shell layer: Add an auxiliary agent to the mixture, then add a pH regulator, slowly raise the temperature of the system, after the reaction, filter the microcapsules, adjust the pH to neutral, wash with water multiple times, and then dry thoroughly to form the first shell layer covering the core material;

[0040] Formation of the second shell layer: Disperse the dried material forming the first shell layer covering the core material in water containing a dispersant, and slowly add it to a solution containing polymethyl methacrylate and / or polysulfone under the second stirring condition, and keep stirring at room temperature until the solvent volatilizes completely to form the second shell layer covering the first shell layer.

[0041] In one embodiment, the prepolymer is at least one of urea-formaldehyde resin, melamine resin, and urea-melamine resin copolymer.

[0042] In one embodiment, the raw materials for preparing the urea-formaldehyde resin include urea and formaldehyde.

[0043] In one embodiment, the raw materials for preparing the melamine resin include melamine and formaldehyde.

[0044] In one embodiment, the raw materials for preparing the urea-melamine resin copolymer include urea, melamine, and formaldehyde.

[0045] In one embodiment, in the step of preparing the prepolymer, the reaction temperature is 70 °C and the time is 60 min to 90 min.

[0046] In one embodiment, during the preparation of the emulsifier solution, the temperature for heating and dissolving is 80 °C.

[0047] In one embodiment, the mass ratio of the first shell layer to the core material is (0.5 - 1):1; the mass ratio of the second shell layer to the first shell layer is 1:(10 - 20).

[0048] In one embodiment, the molar ratio of aldehyde group to amino group is 1.8:1 - 2.2:1.

[0049] In one embodiment, the emulsifier is at least one of sodium dodecylbenzenesulfonate, gum arabic, polyvinyl maleic anhydride, polystyrene maleic anhydride, and polyvinyl alcohol.

[0050] In one embodiment, the concentration of the emulsifier solution is 0.8wt% - 2wt%.

[0051] In one embodiment, the rotation speed of the first condition is 100 r / min - 800 r / min, the temperature is 0 - 25 °C, and the time is 10 min - 30 min.

[0052] In one embodiment, in the step of forming the first shell layer, a pH regulator is added to control the initial pH at 3 - 4, the reaction temperature is programmed to rise, the temperature range is 0 - 50 °C, the total reaction duration is 6 h, and the rotation speed is 300 - 600 r / min.

[0053] In one embodiment, the auxiliary agent is resorcinol, ammonium chloride, and an antifoaming agent.

[0054] In one embodiment, in the step of forming the second shell layer, the dispersant is at least one of polyacrylamide, carboxymethyl cellulose, polyvinylpyrrolidone, and polyvinyl alcohol.

[0055] In one embodiment, the rotation speed of the second stirring condition is 200 r / min - 800 r / min.

[0056] The core material of the double-shell fire-extinguishing microcapsules prepared by the above solution is not easily volatilized by heat, the shell material has a high degree of crosslinking, excellent denseness, excellent compatibility with the substrate, and has a wider application scenario.

[0057] The following will describe in detail the implementation scheme of the present invention in combination with specific embodiments.

[0058] Example 1:

[0059] A preparation method of double-shell fire-extinguishing microcapsules, the preparation method comprising the following steps:

[0060] (1) Preparation of prepolymer: 7.84 g of urea, 20.05 g of 37.5 wt % formaldehyde aqueous solution and 10 mL of water were uniformly mixed, the pH was adjusted to 9 with a Na2CO3 aqueous solution, the mixture was reacted at 70° C. for 90 min, and the mixture was cooled for standby use to obtain a prepolymer;

[0061] (2) Preparation of emulsifier: 1.4 g of polystyrene maleic anhydride and 70 mL of water were added with 0.6 g of NaOH, and the mixture was heated at 80° C. until completely dissolved, and then the pH was adjusted to 7 with citric acid aqueous solution, and the mixture was cooled for standby use to obtain an emulsifier solution;

[0062] (3) Emulsification: 20 g of perfluorohexanone and 10 g of methyl nonafluorobutyl ether as raw materials for preparing the core material are added to the prepolymer, and then an emulsifier solution is added. The system is emulsified at room temperature at a speed of 500 r / min for 15 min to obtain a mixture;

[0063] (4) Formation of the first shell layer: 0.78 g of resorcinol, 0.78 g of ammonium chloride and 0.2 g of a defoaming agent were added to the mixture, and then a citric acid aqueous solution was added to adjust the pH to 3, and then the temperature was raised to 45° C. at a heating rate of 1° C. / min and reacted for 4 h. After the reaction was completed, the microcapsules were filtered out, washed with water for multiple times, and the pH was adjusted to 7 with a Na2CO3 aqueous solution. The microcapsules were dried at room temperature for 48 h to form a first shell layer covering the core material;

[0064] (5) The dried material for forming the first shell layer covering the core material is dispersed in 30 g of an aqueous solution containing 1 wt% polyvinyl alcohol, and then 6 g of a 5 wt% dichloromethane solution of polymethyl methacrylate is slowly added dropwise under stirring to mix evenly. The system is stirred at a speed of 300 r / min until the dichloromethane is completely volatilized, and the microcapsules are filtered out and fully dried at room temperature to form a second shell layer covering the first shell layer, thereby obtaining double-shell fire-extinguishing microcapsules.

[0065] The yield of the double-shell fire-extinguishing microcapsules prepared in Example 1 was 42%, the content of the core material was 47%, and the fire-extinguishing response temperature was 94°C.

[0066] Embodiment 2:

[0067] A method for preparing double-shell fire-extinguishing microcapsules, the preparation method comprising the following steps:

[0068] (1) Preparation of prepolymer: 7.84 g of urea, 20.05 g of 37.5 wt % formaldehyde aqueous solution and 10 mL of water were uniformly mixed, the pH was adjusted to 9 with a Na2CO3 aqueous solution, the mixture was reacted at 70° C. for 90 min, and the mixture was cooled for standby use to obtain a prepolymer;

[0069] (2) Preparation of emulsifier: Take 1.4 g of polystyrene maleic anhydride and 70 mL of water, add 0.6 g of NaOH, heat at 80 °C until completely dissolved, then adjust the pH = 7 with citric acid aqueous solution, cool for later use to obtain an emulsifier solution;

[0070] (3) Emulsification: Add 30 g of the raw material for preparing perfluorhexanone as the core material to the prepolymer, then add the emulsifier solution, and emulsify the system at a rotation speed of 500 r / min at room temperature for 15 min to obtain a mixture;

[0071] (4) Formation of the first shell layer: Add 0.78 g of resorcinol, 0.78 g of ammonium chloride and 0.2 g of defoamer to the mixture, then add citric acid aqueous solution to adjust the pH = 3, and then heat at a rate of 1 °C / min to 45 °C and react for 4 h. After the reaction is completed, filter out the microcapsules, wash them with water multiple times, and adjust the pH = 7 with Na2CO3 aqueous solution. The microcapsules are dried at room temperature for 48 h to form the first shell layer coating the core material;

[0072] (5) Disperse the dried material forming the first shell layer coating the core material in 30 g of an aqueous solution containing 1 wt% of polyvinyl alcohol, and then slowly dropwise add 6 g of a dichloromethane solution of polysulfone with a concentration of 5 wt% under stirring to mix evenly. Stir the system at a rotation speed of 300 r / min until the dichloromethane completely volatilizes, filter out the microcapsules, and dry them thoroughly at room temperature to form the second shell layer coating the first shell layer, that is, double-shell fire-extinguishing microcapsules are obtained.

[0073] The yield of the double-shell fire-extinguishing microcapsules prepared in Example 2 is 36%, the content of the core material is 44%, and the fire-extinguishing response temperature is 97 °C.

[0074] Example 3:

[0075] A preparation method of double-shell fire-extinguishing microcapsules, the preparation method comprising the following steps:

[0076] (1) Preparation of prepolymer: Uniformly mix 3.92 g of urea, 5.48 g of melamine, 20.05 g of 37.5 wt% formaldehyde aqueous solution and 10 mL of water, use Na2CO3 aqueous solution to adjust the pH = 9, react at 70 °C for 90 min, cool for later use to obtain a prepolymer;

[0077] (2) Preparation of emulsifier: Take 0.8 g of sodium dodecylbenzenesulfonate and 0.6 g of gum arabic and add them to 70 mL of water, dissolve them fully to obtain an emulsifier solution;

[0078] (3) Emulsification: Add 30 g of the raw materials for preparing the perfluorhexanone as the core material to the prepolymer, then add the emulsifier solution. The system is emulsified at a speed of 500 r / min at room temperature for 15 min to obtain a mixture;

[0079] (4) Formation of the first shell layer: Add 0.93 g of resorcinol, 0.93 g of ammonium chloride, and 0.2 g of defoamer to the citric acid aqueous solution in the mixture, adjust the pH = 3, react at room temperature for 0.5 h, then increase the temperature at a rate of 1 °C / min to 30 °C and react for 6 h. After the reaction is completed, filter out the microcapsules, wash them with water multiple times, and adjust the pH = 7 with Na2CO3 aqueous solution. The microcapsules are dried at room temperature for 48 h to form the first shell layer coating the core material;

[0080] (5) Disperse the dried material forming the first shell layer coating the core material in 30 g of a saturated saline solution containing 1 wt% of polyvinyl alcohol, and then slowly drop 6 g of a tetrahydrofuran solution of polymethyl methacrylate with a concentration of 5 wt% under stirring and mix evenly. The system is stirred at a speed of 300 r / min until the dichloromethane completely volatilizes, filter out the microcapsules, and dry them thoroughly at room temperature to form the second shell layer coating the first shell layer, that is, double-shell fire-extinguishing microcapsules are obtained.

[0081] The yield of the double-shell fire-extinguishing microcapsules prepared in Example 3 is 33%, the content of the core material is 40%, and the fire-extinguishing response temperature is 90 °C.

[0082] Example 4:

[0083] A preparation method of double-shell fire-extinguishing microcapsules, the preparation method comprising the following steps:

[0084] (1) Preparation of prepolymer: Uniformly mix 3.92 g of urea, 5.48 g of melamine, 20.05 g of 37.5 wt% formaldehyde aqueous solution and 10 mL of water, adjust the pH = 9 with Na2CO3 aqueous solution, react at a temperature of 70 °C for 90 min, cool and set aside to obtain the prepolymer;

[0085] (2) Preparation of emulsifier: Take 0.8 g of sodium dodecylbenzenesulfonate and 0.6 g of gum arabic and add them to 70 mL of water, fully dissolve to obtain the emulsifier solution;

[0086] (3) Emulsification: Add 20 g of perfluorhexanone and 10 g of methyl nonafluorobutyl ether as the raw materials for the core material to the prepolymer, then add the emulsifier solution. The system is emulsified at a speed of 500 r / min at room temperature for 15 min to obtain a mixture;

[0087] (4) Formation of the first shell layer: To the said mixture, add 0.93 g of resorcinol, 0.93 g of ammonium chloride and 0.2 g of defoamer. Add citric acid aqueous solution, adjust the pH to 3, react at room temperature for 0.5 h, then increase the temperature at a rate of 1 °C / min to 30 °C and react for 6 h. After the reaction ends, filter out the microcapsules, wash them with water multiple times, and adjust the pH to 7 with Na2CO3 aqueous solution. The microcapsules are dried at room temperature for 48 h to form the first shell layer coating the core material;

[0088] (5) Disperse the dried material forming the first shell layer coating the core material in 30 g of an aqueous solution containing 1 wt% of polyvinyl alcohol, and then slowly dropwise add 6 g of a dichloromethane solution of polymethyl methacrylate with a concentration of 5 wt% under stirring and mix evenly. The system is stirred at a rotation speed of 300 r / min until the dichloromethane completely volatilizes. Filter out the microcapsules and dry them thoroughly at room temperature to form the second shell layer coating the first shell layer, that is, double-shell fire-extinguishing microcapsules are obtained.

[0089] The yield of the double-shell fire-extinguishing microcapsules prepared in Example 4 is 32%, the content of the core material is 42%, and the fire-extinguishing response temperature is 95 °C.

[0090] In order to further verify that the double-shell fire-extinguishing microcapsules of the present invention have wide applications, the following only provides an example of applying the double-shell fire-extinguishing microcapsules to the preparation of coatings, but is not limited to the application in coatings and can also be applied to other substrates, which will not be elaborated here.

[0091] Application example:

[0092] Respectively add 5 g of the double-shell fire-extinguishing microcapsules prepared in Examples 1 to 4 to 20 g of the coating, heat at 50 °C for 7 days, and use the microcapsules only coated with the first shell layer as the application comparative example. The double-shell fire-extinguishing microcapsules prepared in Application Example 1 are denoted as Application Example 1, those prepared in Application Example 2 are denoted as Application Example 2, those prepared in Application Example 3 are denoted as Application Example 3, and those prepared in Application Example 4 are denoted as Application Example 4. The results are shown in Table 1 below.

[0093] Table 1: Application performance

[0094] Microcapsule Coating Application Example 1 No gel formed, emulsion stable Application Example 2 No gel formed, emulsion stable Application Example 3 No gel formed, emulsion stable Application Example 4 No gel formed, emulsion stable Application Comparative Example Gel formed

[0095] It can be seen from Table 1 that by optimizing the preparation raw materials of the first shell layer and the second shell layer in this application, the double-shell fire-extinguishing microcapsules have better compatibility and more stable application performance.

[0096] Figure 1SEM schematic diagram of the double-shell fire-extinguishing microcapsules prepared in Example 1. It can be seen from the figure that the particle size of the double-shell fire-extinguishing microcapsules prepared in Example 1 is 40 μm to 100 μm.

[0097] The double-shell fire-extinguishing microcapsules prepared in Examples 2 to 4 are similar to those in Example 1 and will not be elaborated here.

[0098] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0099] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A double-shell fire-extinguishing microcapsule, characterized in that, The double-shell fire-extinguishing microcapsule includes a core material, a first shell layer coating the core material, and a second shell layer wrapping the first shell layer; Among them, the raw materials for preparing the core material are at least one of perfluoromethyl hexanone, 1,2-tetrafluorodibromoethane, methyl nonafluorobutyl ether, and 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl) pentane; The first shell layer is at least one of urea-formaldehyde resin, melamine resin, and urea-melamine resin copolymer; The raw materials for preparing the second shell layer include at least one of polymethyl methacrylate and polysulfone.

2. A preparation method of a double-shell fire-extinguishing microcapsule, characterized in that, The preparation method is used to prepare the fire-extinguishing microcapsule as described in claim 1, and the preparation method includes the following steps: Prepare a prepolymer; Add an emulsifier to water, heat and dissolve it, adjust the pH to obtain an emulsifier solution; Add the raw materials for preparing the core material to the prepolymer, then add the emulsifier solution, and perform stirring treatment under the first stirring condition to obtain a mixture; Formation of the first shell layer: Add an auxiliary agent to the mixture, add a pH regulator, slowly raise the temperature of the system, after the reaction, filter the microcapsules, adjust the pH to neutral, wash with water multiple times, and then dry thoroughly to form the first shell layer coating the core material; Formation of the second shell layer: Disperse the dried material forming the first shell layer coating the core material in water containing a dispersant, slowly add it to a solution containing polymethyl methacrylate and / or polysulfone under stirring conditions, and keep stirring at room temperature until the solvent volatilizes completely to form the second shell layer coating the first shell layer.

3. The preparation method according to claim 2, characterized in that, The mass ratio of the first shell layer to the core material is (0.5 - 1):1; the mass ratio of the second shell layer to the first shell layer is 1:(10 - 20).

4. The preparation method according to claim 2, wherein, The molar ratio of aldehyde group to amino group is 1.8:1 - 2.2:

1.

5. The preparation method according to claim 2, wherein The reaction time in the step of preparing the prepolymer is 60 min - 90 min.

6. The preparation method according to claim 2, characterized in that, The emulsifier is at least one of sodium dodecyl benzene sulfonate, gum arabic, polyvinyl maleic anhydride, polystyrene maleic anhydride, and polyvinyl alcohol.

7. The preparation method according to claim 6, characterized in that, The concentration of the emulsifier solution is 0.8 wt% - 2 wt%.

8. The preparation method according to claim 2, characterized in that, The rotation speed under the first condition is 100 r / min - 800 r / min, the temperature is 0 - 25 °C, and the time is 10 min - 30 min.

9. The preparation method according to claim 2, wherein In the step of forming the first shell layer, add a pH regulator to control the initial pH at 3 - 4, the reaction temperature is programmed heating, the temperature range is 0 - 50 °C, the total reaction duration is 6 h, and the rotation speed is 300 - 600 r / min.

10. The preparation method according to claim 2, characterized in that, In the step of forming the second shell layer, the dispersant is at least one of polyacrylamide, carboxymethyl cellulose, polyvinylpyrrolidone, and polyvinyl alcohol.

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