Microencapsulated perfluorohexanone as well as preparation method and application thereof

Abstract

The invention discloses microencapsulated perfluorohexanone as well as a preparation method and application thereof. Perfluorohexanone serving as a core material is embedded in a core part of a microcapsule; the shell layer I is formed by carrying out polymerization reaction on isophorone diisocyanate, trimethylolpropane and 1, 4-butanediol; the shell layer II is formed by interface bonding of the shell layer I subjected to surface modification through a silane coupling agent and polyurethane propionate, chemical bonding of the microcapsule and a secondary embedding layer is enhanced through modification of the silane coupling agent, PUA and nano-silica form double barriers, leakage is reduced, thermal degradation is delayed, and the microcapsule has the advantages of being good in stability, good in stability, good in stability and the like. The heat stability of the nano silicon dioxide and the mechanical strength of the PUA jointly improve the control capacity of release of the fire extinguishing agent, the steps or components are omitted, and the core functions (embedding, heat stability and fire extinguishing) of the microcapsule are remarkably reduced due to structural defects and insufficient interface bonding.

Description

Technical Field

[0001] The invention belongs to the technical field of perfluorohexanone microencapsulation, and particularly relates to microencapsulated perfluorohexanone and a preparation method and application thereof. Background Art

[0002] Perfluorohexanone, a new fluorinated fire extinguishing agent that is liquid at room temperature, is considered the most ideal alternative to halon fire extinguishing agents due to its high fire extinguishing efficiency and excellent environmental performance. Its non-conductive, volatile nature and the fact that it leaves no residue after extinguishing a fire give perfluorohexanone significant advantages in the field of electrical fire safety protection.

[0003] Microencapsulation technology, as an advanced encapsulation technique, can encapsulate small solid particles, liquids, or gases within polymer materials, creating microscopic packages ranging in size from 1 to 5000 μm. This technology not only protects the core material from external interference but also enables slow or on-demand release of the core material. Therefore, microencapsulation of perfluorohexanone can further enhance its performance and applicability.

[0004] However, the research on perfluorohexanone microencapsulation is still in its early stages. At present, there are some related patents and technical reports at home and abroad, but they all have technical defects to varying degrees, such as:

[0005] Shell material density issues: For example, the gelatin shell recommended in Russian patent RU2162520 achieves a certain microencapsulation effect, but the gelatin shell has poor density and cannot effectively protect the core material. This can cause perfluorohexanone to leak during storage or use, thereby reducing fire extinguishing effectiveness.

[0006] High production costs: Using high-grade materials such as gelatin as shell materials not only increases production difficulty but also leads to high production costs of microcapsules, which limits the widespread application of perfluorohexanone microencapsulation technology.

[0007] Core material stability issues: Perfluorohexanone, a highly volatile liquid fire extinguishing agent, is easily lost due to volatilization during the microencapsulation process, resulting in insufficient core material content. In addition, the rupture of microcapsules at high temperatures can also lead to leakage of the core material and a decrease in stability.

[0008] Shell material limitations: For example, U.S. Patent No. 9968813 embeds a halogenated hydrocarbon fire extinguishing agent within a polyurea or polyurethane shell. While this improves the core material's stability, the halogenated hydrocarbon fire extinguishing agent's inherent ozone depletion and toxic effects on humans and the environment limit its application. Meanwhile, Chinese Patent No. CN109453491 embeds a fire extinguishing agent such as perfluorohexanone within a urea-formaldehyde or melamine resin. While this method offers superior mechanical and permeability properties, the toxic formaldehyde gas produced during the preparation process poses a health risk.

[0009] Complex preparation process: The preparation process for perfluorohexanone microencapsulation is generally complex and requires precise control of reaction conditions and parameters. This not only increases production difficulty but may also affect the quality and performance of the microcapsules.

[0010] In summary, while perfluorohexanone microencapsulation technology has broad application prospects, it still faces many technical drawbacks and challenges. Therefore, further research and development is needed to explore more efficient, environmentally friendly, and economical microencapsulation methods and materials to meet the needs of practical applications. Summary of the Invention

[0011] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0012] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0013] Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing microencapsulated perfluorohexanone.

[0014] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising:

[0015] isophorone diisocyanate and perfluorohexanone are mixed in a mass volume ratio of 1:4 to 6 to obtain an oil phase;

[0016] The composite emulsion and the oil phase are mixed in a volume ratio of 4 to 8:1, and emulsified to obtain emulsion I;

[0017] Trimethylolpropane, crosslinking agent I, and initiator are added to emulsion I to carry out a first polymerization reaction. After the reaction is completed, the reaction is filtered and washed to obtain a primary microcapsule product;

[0018] The primary microcapsule product was modified with γ-aminopropyltriethoxysilane to obtain surface-modified microcapsules;

[0019] Polyurethane acrylate is dissolved in an organic solvent, and nanomaterials are added thereto to obtain a wall material solution;

[0020] The surface-modified microcapsules are dispersed in a wall material solution, to which a crosslinking agent II is added for a second polymerization reaction. After the reaction is completed, the microcapsulated perfluorohexanone is obtained by filtering, washing, and drying.

[0021] As a preferred embodiment of the method for preparing microencapsulated perfluorohexanone according to the present invention, the nonionic emulsifier includes one or more of sorbitan monooleate, polyoxyethylene sorbitan monooleate, and polydimethylsiloxane; and the anionic emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, and sodium methyl isobutyl sulfosuccinate.

[0022] As a preferred embodiment of the method for preparing microencapsulated perfluorohexanone according to the present invention, the mass ratio of the trimethylolpropane to the isophorone diisocyanate in the emulsion I is 3 to 4:5, the mass ratio of the crosslinking agent I to the isophorone diisocyanate in the emulsion I is 0.4 to 1:5, and the crosslinking agent I is 1,4-butanediol.

[0023] As a preferred embodiment of the method for preparing microencapsulated perfluorohexanone of the present invention, the temperature of the first polymerization reaction is 35-45° C., the reaction time is 2.5-3.5 h, and the reaction speed is 200-400 rpm.

[0024] As a preferred embodiment of the method for preparing microencapsulated perfluorohexanone of the present invention, the wall material solution comprises a polyurethane acrylate concentration of 10-20%, a nanomaterial concentration of 1-5%, and the nanomaterial comprises one of nano zinc oxide or nano silicon oxide.

[0025] As a preferred embodiment of the method for preparing microencapsulated perfluorohexanone according to the present invention, the mass concentration of the surface-modified microcapsules relative to the wall material solution is 8-12%, the amount ratio of the crosslinking agent II to the polyurethane acrylate in the wall material solution is 1-5:10, and the crosslinking agent II is ethylenediamine.

[0026] As a preferred embodiment of the method for preparing microencapsulated perfluorohexanone of the present invention, the second polymerization reaction is divided into two stages, firstly reacting at 30-35°C for 0.5-1h, and then reacting at 40-50°C for 1.5-2.5h.

[0027] Another object of the present invention is to provide a microencapsulated perfluorohexanone.

[0028] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising: perfluorohexanone as a core material embedded in the core part of the microcapsule;

[0029] Shell I is formed by polymerization of isophorone diisocyanate, trimethylolpropane, and 1,4-butanediol;

[0030] The shell layer II is formed by interfacial bonding of the shell layer I surface-modified with a silane coupling agent and polyurethane propionate.

[0031] Another object of the present invention is to provide a use of microencapsulated perfluorohexanone as a fire extinguishing agent.

[0032] Beneficial effects of the present invention:

[0033] The present invention provides a microencapsulated perfluorohexanone. The perfluorohexanone serves as a fire extinguishing agent and is embedded in the core portion of the microcapsule. The first shell layer is formed by polymerization of IPDI, trimethylolpropane (TMP) and ethylene glycol. The isocyanate group (-NCO) of IPDI reacts with the hydroxyl groups (-OH) of TMP and 1,4-butanediol to generate a dense polyurethane / polyurea cross-linked network. The cross-linked network has high mechanical strength and density, can effectively embed the perfluorohexanone, prevent its leakage, and thus improve the embedding rate.

[0034] The silane coupling agent reacts with the polyurethane / polyurea shell on the surface of the microcapsule through its amino group (-NH2) to form a stable chemical bond. In addition, the introduction of the silane coupling agent enhances the reactivity of the microcapsule surface, provides a good interface binding site for secondary encapsulation, and forms a stronger interface bond with polyurethane acrylate PUA.

[0035] By adding nano-silica, on the one hand, the mechanical strength and thermal stability of the wall material are enhanced; on the other hand, nano-silica forms physical and chemical bonds with PUA and silane coupling agent, further improving the overall performance of the microcapsules;

[0036] Ethylenediamine is used as a cross-linking agent to react with the acrylate groups in PUA to form a cross-linked network, which enhances the density and mechanical strength of the secondary embedding layer. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0038] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0039] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0040] Unless otherwise specified, the raw materials used in the present invention are all commercially available in the art, wherein the polyurethane acrylate is aliphatic polyurethane acrylate oligomer CN9001 NS.

[0041] The performance test of the prepared microcapsule material in the present invention refers to the following method:

[0042] In the present invention, the embedding efficiency of the product microcapsules is determined by a high-temperature heat loss method;

[0043] The storage stability of the capsules was characterized by the mass loss rate. The product microcapsules were placed in a constant temperature oven at 70°C for 10 hours, and the mass loss rate after drying was used to characterize the storage stability of the microcapsules.

[0044] The fire extinguishing effect of the capsule is characterized by the fire extinguishing time. Specifically, with an 800°C flame as the fire source, the microcapsules are fixed on the surface of a steel plate at a distance of 10 cm from the fire source, and the fire extinguishing time is recorded.

[0045] Example 1

[0046] This embodiment provides a method for preparing microencapsulated perfluorohexanone, specifically:

[0047] 1) mixing isophorone diisocyanate and perfluorohexanone in a mass volume ratio of 1:5 to obtain an oil phase;

[0048] Sorbitol monooleate, polyoxyethylene sorbitan monooleate and sodium lauryl sulfate are compounded in a mass ratio of 5:5:1 to obtain a composite emulsifier, and the composite emulsifier is dissolved in deionized water to obtain an emulsion with a concentration of 20%;

[0049] The emulsion and the oil phase were mixed in a volume ratio of 6:1 and emulsified at a rotation speed of 2000 rpm for 15 min to obtain emulsion I;

[0050] Trimethylolpropane, 1,4-butanediol, and dibutyltin dilaurate were added to emulsion I, wherein the mass ratio of trimethylolpropane to isophorone diisocyanate in emulsion I was 7:10, the mass ratio of 1,4-butanediol to isophorone diisocyanate in emulsion I was 1:10, and the amount of dibutyltin dilaurate used as an initiator was 5% of the polymerization system. The first polymerization reaction was carried out at 40° C. for 3 hours. After the reaction was completed, the mixture was filtered and washed to obtain a primary microcapsule product.

[0051] 2) The microcapsule product was dispersed in anhydrous ethanol to form a uniform suspension, to which γ-aminopropyltriethoxysilane (KH-540) was added at a concentration of 3% by weight relative to the mass of the microcapsule product. The suspension was stirred at 300 rpm at 40° C. for 2 h to allow the silane coupling agent to fully react with the surface of the microcapsules. After the reaction was complete, the suspension was filtered and washed three times with anhydrous ethanol to remove unreacted silane coupling agent. The suspension was then dried under vacuum at 40° C. to obtain surface-modified microcapsules.

[0052] 3) polyurethane acrylate is dissolved in propanol, and nano-silica is added thereto to obtain a wall material solution, wherein the concentration of polyurethane acrylate is 15% and the concentration of nano-silica is 3%;

[0053] The surface-modified microcapsules are dispersed in a wall material solution, to which ethylenediamine is added to form a uniform suspension, wherein the mass concentration of the surface-modified microcapsules is 10%, and the amount of ethylenediamine is 1:5 of the surface-modified microcapsules. A second polymerization reaction is carried out, first at 30°C for 1 hour, then at 45°C for 2 hours. After the reaction is completed, the solution is filtered and washed, and freeze-dried for 12 hours to obtain microencapsulated perfluorohexanone.

[0054] Example 2

[0055] 1) mixing isophorone diisocyanate and perfluorohexanone in a mass volume ratio of 1:4 to obtain an oil phase;

[0056] Sorbitol monooleate, polyoxyethylene sorbitan monooleate and sodium lauryl sulfate are compounded in a mass ratio of 5:5:1 to obtain a composite emulsifier, and the composite emulsifier is dissolved in deionized water to obtain an emulsion with a concentration of 20%;

[0057] The emulsion and the oil phase were mixed in a volume ratio of 4:1 and emulsified at a rotation speed of 2000 rpm for 15 min to obtain emulsion I;

[0058] Trimethylolpropane, 1,4-butanediol, and dibutyltin dilaurate were added to emulsion I, wherein the mass ratio of trimethylolpropane to isophorone diisocyanate in emulsion I was 3:5, the mass ratio of 1,4-butanediol to isophorone diisocyanate in emulsion I was 1:10, and the amount of dibutyltin dilaurate used as an initiator was 5% of the polymerization system. The first polymerization reaction was carried out at 45° C. for 2.5 hours. After the reaction was completed, the mixture was filtered and washed to obtain a primary microcapsule product.

[0059] 2) The microcapsule product was dispersed in anhydrous ethanol to form a uniform suspension, to which γ-aminopropyltriethoxysilane (1% by weight relative to the mass of the microcapsule product) was added, and the suspension was stirred at 300 rpm at 40° C. for 2 h to allow the silane coupling agent to fully react with the surface of the microcapsules. After the reaction was complete, the suspension was filtered and washed three times with anhydrous ethanol to remove unreacted silane coupling agent, and then dried in vacuo at 40° C. to obtain surface-modified microcapsules.

[0060] 3) polyurethane acrylate is dissolved in propanol, and nano-silica is added thereto to obtain a wall material solution, wherein the concentration of polyurethane acrylate is 10% and the concentration of nano-silica is 1%;

[0061] The surface-modified microcapsules are dispersed in a wall material solution, to which ethylenediamine is added to form a uniform suspension, wherein the mass concentration of the surface-modified microcapsules is 8%, and the amount of ethylenediamine is 1:5 of the surface-modified microcapsules. A second polymerization reaction is carried out, first at 30°C for 0.5h, then at 40°C for 3h. After the reaction is completed, the solution is filtered and washed, and freeze-dried for 12h to obtain microencapsulated perfluorohexanone.

[0062] Example 3

[0063] 1) mixing isophorone diisocyanate and perfluorohexanone in a mass volume ratio of 1:6 to obtain an oil phase;

[0064] Sorbitol monooleate, polyoxyethylene sorbitan monooleate and sodium lauryl sulfate are compounded in a mass ratio of 5:5:1 to obtain a composite emulsifier, and the composite emulsifier is dissolved in deionized water to obtain an emulsion with a concentration of 20%;

[0065] The emulsion and the oil phase were mixed in a volume ratio of 8:1 and emulsified at a rotation speed of 2000 rpm for 15 min to obtain emulsion I;

[0066] Trimethylolpropane, 1,4-butanediol, and dibutyltin dilaurate were added to emulsion I, wherein the mass ratio of trimethylolpropane to isophorone diisocyanate in emulsion I was 4:5, the mass ratio of 1,4-butanediol to isophorone diisocyanate in emulsion I was 1:10, and the amount of dibutyltin dilaurate used as an initiator was 5% of the polymerization system. The first polymerization reaction was carried out at 45° C. for 2.5 hours. After the reaction was completed, the mixture was filtered and washed to obtain a primary microcapsule product.

[0067] 2) The microcapsule product was dispersed in anhydrous ethanol to form a uniform suspension, to which γ-aminopropyltriethoxysilane (5% by weight relative to the mass of the microcapsule product) was added, and the suspension was stirred at 300 rpm at 40° C. for 2 h to allow the silane coupling agent to fully react with the surface of the microcapsules. After the reaction was complete, the suspension was filtered and washed three times with anhydrous ethanol to remove unreacted silane coupling agent, and then dried in vacuo at 40° C. to obtain surface-modified microcapsules.

[0068] 3) polyurethane acrylate is dissolved in propanol, and nano-silica is added thereto to obtain a wall material solution, wherein the concentration of polyurethane acrylate is 20% and the concentration of nano-silica is 5%;

[0069] The surface-modified microcapsules are dispersed in a wall material solution, to which ethylenediamine is added to form a uniform suspension, wherein the mass concentration of the surface-modified microcapsules is 12%, and the amount of ethylenediamine is 1:10 of the surface-modified microcapsules. A second polymerization reaction is carried out, first at 30°C for 1.5 hours and then at 45°C for 2 hours. After the reaction is completed, the solution is filtered and washed, and freeze-dried for 12 hours to obtain microencapsulated perfluorohexanone.

[0070] Comparative Example 1

[0071] The difference between this comparative example and Example 1 is that steps 2) and 3) are omitted, and the remaining steps and processes are the same as those in Example 1 to obtain the microcapsules of this comparative example.

[0072] Comparative Example 2

[0073] The difference between this comparative example and Example 1 is that step 2) is omitted, and the remaining steps and processes are the same as those in Example 1 to obtain the microcapsules of this comparative example.

[0074] Comparative Example 3

[0075] The difference between this comparative example and Example 1 is that the nano-silicon dioxide in step 3) is omitted, and the remaining steps and processes are the same as those in Example 1 to obtain the microcapsules of this comparative example.

[0076] The relevant properties of the microcapsules prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were tested, and the results are shown in Table 1.

[0077] Table 1

[0078] Embedding rate / % Mass loss rate / % Fire extinguishing time / s Example 1 81.6 3.1 3.2 Example 2 75.6 4.8 3.5 Example 3 78.5 4.1 3.4 Comparative Example 1 54.4 15.4 6.2 Comparative Example 2 62.3 13.2 5.9 Comparative Example 3 67.6 8.9 6.4

[0079] As can be seen from Table 1, the microcapsules prepared by the scheme of the present invention have a high embedding rate, good thermal stability and fire extinguishing effect. In the present invention, the chemical bonding between the microcapsules and the secondary embedding layer is enhanced by modification with a silane coupling agent. PUA and nano-silica form a double barrier to reduce leakage and delay thermal degradation. The thermal stability of nano-silica and the mechanical strength of PUA jointly enhance the ability to control the release of the fire extinguishing agent. If these steps or components are omitted, the core functions of the microcapsules (embedding, thermal stability, and fire extinguishing) will be significantly reduced due to structural defects and insufficient interface bonding.

[0080] Example 4

[0081] The difference between this embodiment and embodiment 1 is that the trimethylolpropane in step 1) is replaced with pentaerythritol, glycerol, and polyethylene glycol. The remaining steps and processes are the same as those in embodiment 1. Microcapsules prepared with different polymerized monomers in this embodiment are obtained, and their relevant properties are measured and compared with those of the trimethylolpropane in embodiment 1. The results are shown in Table 2.

[0082] Table 2

[0083] Embedding rate / % Mass loss rate / % Fire extinguishing time / s Trimethylolpropane 81.6 3.1 3.2 Pentaerythritol 73.6 6.7 5.4 glycerin 69.8 5.6 5.1 polyethylene glycol 76.1 5.9 6.6

[0084] As can be seen from Table 2, the various properties of the microcapsules obtained after adjusting the type of polymerization monomer II are reduced. This is because the structure and compatibility with IDPI change after adjusting the type of polymerization monomer, and the polarity or molecular weight difference of the replacement monomer may affect the interfacial tension between the oil phase and the water phase, resulting in a wider distribution of emulsion droplet size and uneven shell thickness, which in turn affects the performance of the microcapsules.

[0085] For example, after adjusting to pentaerythritol, its crosslink density is too high. Excessive crosslinking makes the shell too rigid, which is prone to cracking due to mechanical stress during emulsification or polymerization. Glycerol's hydroxyl group has high reactivity and reacts faster with IPDI than TMP. It partially reacts before emulsification is complete, forming an incomplete or highly porous shell, which reduces the encapsulation efficiency. In addition, glycerol is a short-chain triol, and the polyurethane segments it forms are short, resulting in a shell with poor flexibility and easy cracking due to thermal expansion or mechanical impact. PEG is a long-chain polyol, and its flexible segments hinder effective crosslinking, resulting in a shell crosslink density lower than TMP, making it unable to effectively encapsulate perfluorohexanone.

[0086] Example 5

[0087] This embodiment differs from embodiment 1 in that 1,4-butanediol in step 1) is replaced with ethylene glycol, diethylene glycol, 1,6-hexanediol, and neopentyl glycol. The remaining steps and processes are the same as those in embodiment 1. Microcapsules prepared with different crosslinking agents I in this embodiment are obtained, and their relevant properties are measured and compared with those of 1,4-butanediol in embodiment 1. The results are shown in Table 3.

[0088] Table 3

[0089]

[0090]

[0091] As can be seen from Table 3, adjusting the type of cross-linker I has a significant impact on the performance of the prepared microcapsules. When ethylene glycol is used as the cross-linker, its cross-linking density is slightly lower, and it is easy to form a more rigid shell, resulting in a decrease in the embedding efficiency. Although 1,6-hexanediol can increase the hydrophobicity of the shell and thus improve the embedding effect, its long chain structure is easily softened at high temperatures, thereby affecting thermal stability. The branched structure of neopentyl glycol affects the cross-linking density, resulting in an increase in porosity, which in turn affects the embedding efficiency.

[0092] Example 6

[0093] This embodiment differs from Example 1 in that the γ-aminopropyltriethoxysilane (KH-540) in step 2) is replaced with γ-glycidoxypropyltrimethoxysilane (KH-560), γ-methacryloxypropyltrimethoxysilane (KH-570), and γ-mercaptopropyltrimethoxysilane (KH-590). The remaining steps and processes are the same as in Example 1. Microcapsules modified with different silane coupling agents in this embodiment are obtained, and their relevant properties are measured and compared with those of KH-540 in Example 1. The results are shown in Table 4.

[0094] Table 4

[0095] Embedding rate / % Mass loss rate / % Fire extinguishing time / s KH-540 81.6 3.1 3.2 KH-560 65.4 6.9 5.6 KH-570 63.9 7.5 6.2 KH-590 61.8 8.2 6.5

[0096] As can be seen from Table 4, adjusting the type of silane coupling agent has a significant impact on the performance of the prepared microcapsules. This is because the functional group characteristics of different silane coupling agents are different, resulting in defects in the overall process after replacement, insufficient surface modification, and a significant decrease in interfacial bonding strength. Unreacted silanes may become structural defects, reducing the shell density and thus affecting the overall performance of the microcapsules.

[0097] Example 7

[0098] The difference between this embodiment and embodiment 1 is that the concentration of nano-silica in step 3) is replaced with 0.5, 1, 3, 5, and 6%. The remaining steps and processes are the same as those in embodiment 1. Microcapsules with different nanomaterial concentrations in this embodiment are obtained, and their relevant properties are measured and compared with KH-540 in embodiment 1. The results are shown in Table 5.

[0099] Table 5

[0100]

[0101]

[0102] As can be seen from Table 5, the concentration of nanosilica also has a certain impact on the performance of the prepared microcapsules. At low concentrations, the nanosilica content is insufficient, and a continuous reinforcing network cannot be formed in the PUA wall material, resulting in limited improvement in mechanical strength and thermal stability. When the nanoparticles are too few, their role in filling pores and enhancing interfacial bonding is weakened, the density of the embedding layer decreases, and the risk of perfluorohexanone leakage increases. High concentrations of nanosilica are prone to agglomeration due to van der Waals forces, forming micron-sized aggregates, which become weak points in the embedding layer and reduce mechanical strength. Agglomerates hinder the movement of PUA molecular chains, resulting in increased brittleness of the embedding layer. The microcapsules are easily broken under thermal stress or mechanical impact. Excessive nanoparticles occupy reaction sites, hindering the contact between ethylenediamine and the acrylate or isocyanate groups of PUA, resulting in incomplete crosslinking. In addition, agglomerated nanosilica may cause microcracks at high temperatures due to differences in thermal expansion coefficients, which in turn accelerates thermal degradation. An appropriate amount of nanoparticles reacts with the amino groups of PUA and silane coupling agent (KH-550) through surface hydroxyl groups to form chemical bonds, thereby enhancing interfacial bonding strength. Nanoparticles act as cross-linking promoters to optimize the reaction efficiency of ethylenediamine and PUA, forming a dense and flexible embedding layer.

[0103] In summary, the present invention provides a microencapsulated perfluorohexanone, in which perfluorohexanone is used as a fire extinguishing agent and is embedded in the core part of the microcapsule. The first shell layer is formed by polymerization reaction of IPDI, trimethylolpropane (TMP) and ethylene glycol, wherein the isocyanate group (-NCO) of IPDI reacts with the hydroxyl groups (-OH) of TMP and 1,4-butanediol to form a dense polyurethane / polyurea cross-linked network. This cross-linked network has high mechanical strength and density, can effectively embed perfluorohexanone, prevent its leakage, and thus improve the embedding rate.

[0104] The silane coupling agent reacts with the polyurethane / polyurea shell on the microcapsule surface through its amino group (-NH2), forming a stable chemical bond. Furthermore, the introduction of the silane coupling agent enhances the reactivity of the microcapsule surface, providing good interfacial binding sites for secondary encapsulation and forming a stronger interfacial bond with polyurethane acrylate (PUA). The addition of nanosilica not only enhances the mechanical strength and thermal stability of the wall material, but also forms a physical and chemical bond with the PUA and silane coupling agent, further improving the overall performance of the microcapsules. Ethylenediamine, a crosslinking agent, reacts with the acrylate groups in the PUA to form a crosslinked network, enhancing the density and mechanical strength of the secondary encapsulation layer.

[0105] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing microencapsulated perfluorohexanone, characterized in that: include, isophorone diisocyanate and perfluorohexanone are mixed in a mass volume ratio of 1:4 to 6 to obtain an oil phase; The composite emulsion and the oil phase are mixed in a volume ratio of 4 to 8:1, and emulsified to obtain emulsion I; Trimethylolpropane, crosslinking agent I, and initiator are added to emulsion I to carry out a first polymerization reaction. After the reaction is completed, the reaction is filtered and washed to obtain a primary microcapsule product; The primary microcapsule product was modified with γ-aminopropyltriethoxysilane to obtain surface-modified microcapsules; Polyurethane acrylate is dissolved in an organic solvent, and nanomaterials are added thereto to obtain a wall material solution; The surface-modified microcapsules are dispersed in a wall material solution, to which a crosslinking agent II is added for a second polymerization reaction. After the reaction is completed, the microcapsulated perfluorohexanone is obtained by filtering, washing, and drying.

2. The method for preparing microencapsulated perfluorohexanone according to claim 1, wherein: The composite emulsion is obtained by dissolving a nonionic emulsifier and an anionic emulsifier in deionized water at a mass ratio of 10:1-3, wherein the concentration of the emulsifier is 15-25%.

3. The method for preparing microencapsulated perfluorohexanone according to claim 2, wherein: The nonionic emulsifier includes one or more of sorbitan monooleate, polyoxyethylene sorbitan monooleate, and polydimethylsiloxane; the anionic emulsifier includes one or more of sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, and sodium methyl isobutyl sulfosuccinate.

4. The method for preparing microencapsulated perfluorohexanone according to claim 1, wherein: The mass ratio of the trimethylolpropane to the isophorone diisocyanate in the emulsion I is 3 to 4:5, and the mass ratio of the crosslinking agent I to the isophorone diisocyanate in the emulsion I is 0.4 to 1:5, wherein the crosslinking agent I is 1,4-butanediol.

5. The method for preparing microencapsulated perfluorohexanone according to claim 4, wherein: The temperature of the first polymerization reaction is 35-45° C., the reaction time is 2.5-3.5 hours, and the reaction speed is 200-400 rpm.

6. The method for preparing microencapsulated perfluorohexanone according to claim 1, wherein: In the wall material solution, the concentration of polyurethane acrylate is 10-20%, the concentration of nano material is 1-5%, and the nano material includes one of nano zinc oxide or nano silicon oxide.

7. The method for preparing microencapsulated perfluorohexanone according to claim 1, wherein: The mass concentration of the surface-modified microcapsules compared to the wall material solution is 8-12%, and the amount ratio of the crosslinking agent II to the polyurethane acrylate in the wall material solution is 1-5:10, wherein the crosslinking agent II is ethylenediamine.

8. The method for preparing microencapsulated perfluorohexanone according to claim 7, wherein: The second polymerization reaction is divided into two stages: first, the reaction is carried out at 30-35° C. for 0.5-1 h, and then the reaction is carried out at 40-50° C. for 1.5-2.5 h.

9. The microencapsulated perfluorohexanone prepared by the method according to any one of claims 1 to 8, characterized in that: include, Perfluorohexanone is embedded in the core of the microcapsule as the core material; Shell I is formed by polymerization of isophorone diisocyanate, trimethylolpropane, and 1,4-butanediol; The shell layer II is formed by interfacial bonding of the shell layer I surface-modified with a silane coupling agent and polyurethane propionate.

10. Use of the microencapsulated perfluorohexanone as claimed in claim 9 as a fire extinguishing agent.

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