Perfluorohexanone double-capsule microcapsules, methods of making and using the same

Abstract

This invention relates to the field of fire extinguishing agent application technology, specifically to perfluorohexanone double-shell microcapsules, their preparation method, and applications. The perfluorohexanone double-shell microcapsule comprises a core and a capsule shell encapsulating the core; the core contains perfluorohexanone; the capsule shell comprises an inner shell and an outer shell encapsulating the inner shell; the inner shell comprises a first polymer material, which includes at least one selected from polyurea, polyurethane, and polylactic acid; the outer shell comprises a second polymer material, which includes at least one selected from silicone resin, modified epoxy resin, and cross-linked polyvinyl alcohol. The perfluorohexanone microcapsules provided by this invention exhibit excellent mechanical strength, electrolyte resistance, and fire extinguishing performance.

Description

Technical Field

[0001] This invention relates to the field of fire extinguishing agent application technology, specifically to perfluorohexanone double-shell microcapsules, their preparation methods, and applications. Background Technology

[0002] Perfluorohexanone (chemical name: perfluoro(2-methyl-3-pentanone), CAS No.: 756-13-8) is a highly efficient and environmentally friendly clean fire extinguishing agent. It has an ODP (ozone depletion potential) of 0 and an extremely low GWP (global warming potential) (100-year GWP≈1). Its fire extinguishing efficiency is superior to traditional halon fire extinguishing agents and some hydrofluorocarbon fire extinguishing agents. Furthermore, it is non-corrosive to electronic components and metal materials, giving it irreplaceable advantages in fire protection in sensitive scenarios such as data centers, new energy batteries, and aerospace precision equipment. However, perfluorohexanone has key problems including high volatility, easy loss at room temperature, and poor storage stability. Its boiling point is approximately 49°C, and its saturated vapor pressure at room temperature is relatively high. Direct filling or spraying can easily lead to loss of the effective components due to volatilization, reducing the effective fire extinguishing period. Simultaneously, perfluorohexanone has poor compatibility with most polymer materials. When in direct contact with plastics, rubber, and other substrates, it is prone to penetration and migration, further exacerbating its loss.

[0003] To address the aforementioned issues, existing technologies often employ microencapsulation to immobilize perfluorohexanone (PFH): PFH is encapsulated into solid microparticles using a shell material, suppressing its volatilization and improving storage stability. However, most existing PFH microcapsules are single-shell structures, exhibiting significant drawbacks: 1. Insufficient shell strength: Single shells (such as polymethyl methacrylate and gelatin-gum arabic complexes) have low mechanical strength, making them prone to rupture during transportation and mixing processes (such as blending with coatings and plastics), leading to core material leakage; 2. Poor sustained-release performance: Single shells have limited ability to control the release of the core material, easily experiencing "sudden release" under high temperature or humidity changes, failing to achieve precise and continuous release during fire extinguishing; 3. Weak environmental resistance: Single shells have poor temperature resistance (<100℃) and solvent resistance, easily degrading or swelling in the warm environment of electronic equipment operation or when exposed to oil or cleaning agents, losing their encapsulation effect.

[0004] Therefore, developing a perfluorohexanone microcapsule structure with high mechanical strength, excellent sustained-release performance, and resistance to temperature and environment has become a core requirement for solving its application bottlenecks. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of uncontrollable release behavior and temperature and environmental resistance in the current perfluorohexanone microcapsule technology, and to provide a perfluorohexanone double-shell microcapsule, its preparation method and application.

[0006] In a first aspect, the present invention provides a perfluorohexanone double-shell microcapsule, comprising a core and a capsule shell covering the core; The capsule core contains perfluorohexanone; the capsule shell includes an inner shell and an outer shell covering the inner shell; the inner shell includes a first polymer material, which includes at least one of polyurea, polyurethane, and polylactic acid; the outer shell includes a second polymer material, which includes at least one of silicone resin, modified epoxy resin, and cross-linked polyvinyl alcohol.

[0007] The perfluorohexanone double-shell microcapsules of this invention encapsulate perfluorohexanone by constructing an inner shell and an outer shell, giving the perfluorohexanone double-shell microcapsules excellent mechanical properties, heat resistance, and resistance to environmental media (such as electrolytes). They also have long-term storage stability (evaporation rate ≤5% after 6 months of storage at room temperature), resistance to mechanical damage (vibration breakage rate ≤3%), and reliability in complex environments. This invention can solve the key problems of existing single-layer microcapsules, such as easy leakage, easy breakage, and limited functionality.

[0008] As a preferred embodiment of the present invention, the polyurea is formed by polymerization of a prepolymer of isophorone diisocyanate and polyethylene glycol 400 with ethylenediamine. Preferably, the mass ratio of isophorone diisocyanate to polyethylene glycol 400 is (4-8):1, and the mass ratio of isophorone diisocyanate to ethylenediamine is 1:(0.1-0.5).

[0009] As a preferred embodiment of the present invention, the polyurethane is formed by polymerization of toluene diisocyanate and 1,4-butanediol, preferably with a mass ratio of (2-5):1, and more preferably 3:1.

[0010] As a preferred embodiment of the present invention, the inner shell further includes nanoparticles.

[0011] As a preferred embodiment of the present invention, the mass ratio of the nanoparticles to the first polymer material is 1:(10-20), for example, 1:10, 1:13, 1:15, 1:18, or 1:20.

[0012] In this invention, it was found that introducing nanoparticles into the inner shell and controlling their mass ratio with the first polymer material within the range of 1:(10-20) can better improve the mechanical and barrier properties of the inner shell. It is speculated that this is because the nanoparticles can be uniformly dispersed in the matrix of the first polymer material as a reinforcing phase. On the one hand, they can effectively hinder the chain segment movement of the polymer through physical filling and interface effects, thereby improving the rigidity, hardness and deformation resistance of the shell. On the other hand, the nanoparticles can form a tortuous "maze" barrier path in the shell, which greatly prolongs the channel for perfluorohexanone molecules to diffuse outward.

[0013] As a preferred embodiment of the present invention, the nanoparticles include one-dimensional nanoparticles and two-dimensional nanoparticles.

[0014] Further research in this invention has revealed that using both one-dimensional and two-dimensional nanoparticles as nanoparticles can better improve the performance of perfluorohexanone double-shell microcapsules. This is presumably because one-dimensional nanoparticles can significantly improve the tensile strength and toughness of the shell, while two-dimensional nanoparticles can be layered in the first polymer matrix. The combination of the two can better increase the mechanical properties of the material and inhibit the permeation of perfluorohexanone.

[0015] As a preferred technical solution of the present invention, the one-dimensional nanoparticles include at least one of zinc oxide nanorods, barium titanate nanorods, and alumina nanofibers, preferably alumina nanofibers, and preferably the alumina nanofibers have an average tube diameter of 3-10 nm and an average length of 200-300 nm.

[0016] As a preferred technical solution of the present invention, the two-dimensional nanoparticles include at least one of molybdenum disulfide, tungsten disulfide, tungsten diselenide, organic hydrotalcite, and organic montmorillonite, preferably organic montmorillonite, and the average particle size of organic montmorillonite is preferably 300-500 nm.

[0017] As a preferred embodiment of the present invention, the mass ratio of the one-dimensional nanoparticles to the two-dimensional nanoparticles is 1:(1-3), preferably 1:1.5.

[0018] As a preferred technical solution of the present invention, the organosilicon resin is obtained by polymerization of silane monomers, wherein the silane monomers include methyltrimethoxysilane and γ-aminopropyltriethoxysilane, and preferably the mass ratio of methyltrimethoxysilane to γ-aminopropyltriethoxysilane is (4-8):1, for example 4:1, 5:1, 6:1, 7:1, 8:1.

[0019] As a preferred embodiment of the present invention, the outer shell further includes disulfide bonds.

[0020] In this invention, the introduction of disulfide bonds into the outer shell can better improve the product's thermal stability and fire extinguishing response. It is speculated that this is because the exchange reaction of dynamic disulfide bonds has a certain temperature threshold, which allows the cured epoxy network to remain stable at temperatures below this threshold (such as normal battery operating temperature or non-fire localized overheating), significantly reducing the leaching of perfluorohexanone at certain temperatures. When the temperature reaches the triggering condition, the rapid breaking of disulfide bonds promotes the rapid rupture of the outer shell, thereby allowing for the rapid release of perfluorohexanone.

[0021] As a preferred embodiment of the present invention, the silane monomer further includes bis-[3-(triethoxysilane)propyl] disulfide, preferably the mass ratio of bis-[3-(triethoxysilane)propyl] disulfide to methyltrimethoxysilane is (0.3-0.8):1, more preferably 0.6:1.

[0022] As a preferred embodiment of the present invention, the modified epoxy resin is formed by reacting epoxy resin and amine curing agent, wherein the amine compound includes DETA curing agent and / or 4,4'-diaminodiphenyl disulfide; the epoxy resin may be epoxy resin E-51, and preferably the mass ratio of the epoxy resin to the amine compound is 1:(0.1-0.5).

[0023] As a preferred embodiment of the present invention, the average thickness of the inner shell is 5-20 μm, preferably 10-15 μm.

[0024] As a preferred embodiment of the present invention, the average thickness of the outer shell is 15-30 μm, preferably 20-25 μm.

[0025] As a preferred embodiment of the present invention, the perfluorohexanone double-shell microcapsules have an average particle size of 100-200 μm and a uniform particle size distribution with a coefficient of variation (CV) ≤ 10%, preferably ≤ 5%.

[0026] In a second aspect, the present invention provides a method for preparing the perfluorohexanone double-shell microcapsules described in the first aspect of the present invention, the method comprising the following steps: S1: Emulsify perfluorohexanone, the inner shell material used to form the inner shell, and an aqueous solution containing an emulsifier to form an emulsion, and then carry out the first polymerization reaction to obtain the inner core material; S2: Add an aqueous solution containing a dispersant to the obtained inner core material, then add the outer shell monomer for forming the outer shell, adjust the pH to 7.5-9, then carry out the second polymerization reaction, add an anti-blocking agent and mix, then carry out post-treatment to obtain perfluorohexanone double shell microcapsules. The inner shell material includes an inner shell monomer, which includes a monomer for forming at least one of polyurea, polyurethane, and polylactic acid, and the outer shell monomer includes a monomer for forming at least one of silicone resin, modified epoxy resin, and cross-linked polyvinyl alcohol.

[0027] The purity of the perfluorohexanone used in this invention is generally ≥99.5 wt%.

[0028] The perfluorohexanone double-shell microcapsules prepared by the above preparation method of the present invention can achieve a coating rate of over 90%.

[0029] As an example, the monomers used to form polyurea include isophorone diisocyanate, a prepolymer of polyethylene glycol 400, and ethylenediamine, preferably with a mass ratio of isophorone diisocyanate to polyethylene glycol 400 of (4-8):1 and a mass ratio of isophorone diisocyanate to ethylenediamine of 1:(0.1-0.5).

[0030] As a preferred embodiment of the present invention, the inner shell material further includes nanoparticles, preferably with a mass ratio of nanoparticles to inner shell monomers of 1:(10-20). The nanoparticles may be the nanoparticles of the inner shell material described above.

[0031] As a preferred embodiment of the present invention, the mass ratio of perfluorohexanone to the inner shell material is 1:(0.2-0.4), for example, 1:0.2, 1:0.26, 1:0.28, 1:0.3, 1:0.35, or 1:0.4.

[0032] As a preferred embodiment of the present invention, the emulsifier comprises a compound of Span-80 and Tween-80, preferably with a mass ratio of Span-80 to Tween-80 of 2:1.

[0033] As a preferred technical solution of the present invention, in step S1, the mass content of the emulsifier in the water is 0.5%-2%.

[0034] As a preferred technical solution of the present invention, in step S1, the mass content of the inner shell monomer in water is 2%-20%.

[0035] In step S1 of this invention, perfluorohexanone can be mixed with oil-soluble monomers and optionally nanoparticles in the inner shell monomer to obtain an oil phase. An emulsifier, water and water-soluble oil-soluble monomers in the inner shell monomer are mixed to form an aqueous phase. Then, the oil phase is slowly added to the aqueous phase to form an emulsion.

[0036] As a preferred technical solution of the present invention, in step S1, the conditions for the first polymerization reaction include: 30-45℃, stirring at 60-100rpm for 2-6 hours.

[0037] As an example, the method in step S1 includes: pre-reacting isophorone diisocyanate with polyethylene glycol 400 and optionally nanoparticles at 30-40°C for 20-40 minutes to obtain a prepolymer; then taking perfluorohexanone, adding it to the prepolymer, and mixing it evenly to form an oil phase; taking deionized water, adding Span-80 and Tween-80 and a water-soluble monomer (e.g., ethylenediamine), and stirring to dissolve it to form an aqueous phase; slowly adding the oil phase to the aqueous phase, and stirring at 5-15°C and 3000-5000 rpm for 10-20 minutes to form an emulsion; heating to 30-45°C and stirring at 60-100 rpm for 2-6 hours to obtain the inner capsule core material.

[0038] In a preferred embodiment of the present invention, the dispersant comprises at least one selected from polyvinylpyrrolidone, polyhexamethylene biguanide, block copolymer P123, and sodium carboxymethyl cellulose. Polyvinylpyrrolidone is used as an example dispersant, and polyhexamethylene biguanide and block copolymer P123 are used in a 1:1 mass ratio as an example dispersant. In this invention, using both polyhexamethylene biguanide and block copolymer P123 as dispersants enables the final product to have superior overall performance.

[0039] As a preferred embodiment of the present invention, the mass content of the dispersant in the aqueous solution containing the dispersant is 1%-3%.

[0040] As a preferred embodiment of the present invention, the mass ratio of the outer shell material to the perfluorohexanone is 1:(5-20).

[0041] As a preferred embodiment of the present invention, the mass ratio of the inner core material to the aqueous solution containing the dispersant is 1:(0.01-10), for example, 1:0.01, 1:0.1, 1:0.5, 1:1, 1:2, 1:3, 1:5, 1:7, or 1:10. Controlling the amount of the aqueous solution containing the dispersant within the aforementioned range ensures sufficient dispersion and wetting of the inner core material, providing a good foundation for uniform coating of the outer shell, while also maintaining a suitable consistency of the reaction system, which is beneficial for subsequent separation and post-processing operations.

[0042] As an example, the shell monomer used to form the organosilicon resin includes a silane monomer comprising methyltrimethoxysilane and γ-aminopropyltriethoxysilane, preferably in a mass ratio of (4-8):1. Further, the silane monomer also includes bis-[3-(triethoxysilane)propyl]disulfide, preferably in a mass ratio of (0.3-0.8):1 of bis-[3-(triethoxysilane)propyl]disulfide and methyltrimethoxysilane.

[0043] As an example, the outer shell monomer used to form the modified epoxy resin includes an epoxy resin and an amine compound, wherein the amine compound includes a blend of polyetheramine D230 and / or 4-aminophenyl disulfide; the epoxy resin may be epoxy resin E-51, and preferably the mass ratio of the epoxy resin to the amine compound is 1:(0.2-0.3).

[0044] As a preferred technical solution of the present invention, the mass ratio of perfluorohexanone to the outer shell monomer is 1:(0.05-0.5), for example, 1:0.05, 1:0.1, 1:0.16, 1:0.18, 1:0.2, 1:0.25, 1:0.3, 1:0.5.

[0045] In step S2 of the present invention, the pH can be adjusted to 7.5-9 using conventional pH adjusters in the art, including but not limited to NaOH aqueous solution with a concentration of 0.1 mol / L.

[0046] As a preferred technical solution of the present invention, in step S2, the conditions for the second polymerization reaction include: reacting at pH 7.5-9 and 25-45°C for 2-10 hours.

[0047] As a preferred embodiment of the present invention, the anti-blocking agent comprises nano-silica and / or talc.

[0048] As a preferred embodiment of the present invention, the mass of the anti-blocking agent is 0.1%-0.5% of the mass of the aqueous solution containing the dispersant.

[0049] As a preferred technical solution of the present invention, in step S2, the post-processing conditions include: centrifugation, centrifugal washing, and freeze drying. The preferred freeze drying conditions include: temperature of -50~-40℃, vacuum degree of 1-10Pa, and time of 12-24h.

[0050] As an example, the specific method in step S2 includes: adding deionized water containing a dispersant to the inner core material and ultrasonically dispersing it at 0-10℃ for 10-20 min; adding the outer shell monomer and adjusting the pH to 7.5-9 with 0.1 mol / L NaOH aqueous solution, and reacting at pH 7.5-9 and 25-45℃ for 2-10 h; cooling to room temperature, adding an anti-adhesion agent, stirring for 10-20 min, centrifuging (1000-5000 rpm, 10-20 min), washing with deionized water after centrifugation, freeze-drying, and then freeze-drying again (temperature -50~-40℃, vacuum degree 1-10 Pa, time 12-24 h) to obtain perfluorohexanone double-shell microcapsules.

[0051] Thirdly, the present invention provides applications of the perfluorohexanone double-shell microcapsules described in the first aspect of the present invention, the applications including at least one of self-extinguishing materials for electronic devices, flame-retardant sheaths for cables, flame retardants for new energy batteries, and clean fire extinguishing agents for precision instruments.

[0052] When the perfluorohexanone double-shell microcapsules of this invention are used in self-extinguishing materials for electronic devices, the outer shell ruptures when the device overheats or catches fire, and the inner shell slowly releases perfluorohexanone, achieving precise fire extinguishing.

[0053] When the perfluorohexanone double-shell microcapsules of this invention are used for flame-retardant cable sheaths, the perfluorohexanone double-shell microcapsules can be combined with polyvinyl chloride or polyethylene to prepare flame-retardant cable sheaths. During combustion, the microcapsules release perfluorohexanone, which inhibits the spread of cable flames and reduces the release of toxic smoke.

[0054] When the perfluorohexanone double-shell microcapsules of this invention are used for flame retardancy in new energy batteries, the perfluorohexanone double-shell microcapsules can be combined with battery separator substrates (such as polyethylene) to form a flame-retardant separator. When the battery experiences thermal runaway, the capsules release perfluorohexanone to inhibit the spread of flames. Moreover, the raw materials are biodegradable, reducing pollution from waste batteries.

[0055] The perfluorohexanone double-shell microcapsules of this invention can be formulated into a clean fire extinguishing agent for use in fire fighting of precision instruments, such as data center servers and aerospace instruments, thus avoiding corrosion of equipment by fire extinguishing agent residue.

[0056] Compared with the prior art, the present invention has at least the following beneficial effects: 1. Significantly improved storage stability: The double-shell structure of the perfluorohexanone double-shell microcapsules in this invention can synergistically inhibit the volatilization of perfluorohexanone—the inner shell has excellent compatibility with perfluorohexanone, which can reduce the permeation of the core material; the outer shell is temperature resistant (long-term operating temperature -40℃ to 120℃) and solvent resistant, and isolates it from the influence of the external environment. According to the test, after 6 months of storage at 25℃, the volatilization rate of perfluorohexanone is ≤5% (the volatilization rate of single-shell microcapsules is ≥25%). 2. High mechanical strength and resistance to breakage: The outer shell (such as organosilicon resin) of the perfluorohexanone double-shell microcapsule in this invention has a tensile strength ≥30MPa and a hardness (Shore D) ≥70. After oscillation at 1000rpm for 30min, the microcapsule breakage rate is ≤3% (single shell breakage rate ≥15%). 3. Controllable sustained-release performance: The degradation rate of the inner shell of the perfluorohexanone double-shell microcapsule in this invention can be controlled by adjusting the monomer ratio. During fire extinguishing (temperature ≥150℃), the perfluorohexanone release cycle is 5-10 minutes, ensuring continuous and effective fire extinguishing and avoiding waste of extinguishing agent caused by "sudden release". 4. Simple preparation process: It adopts a two-step in-situ polymerization method, which does not require complex equipment. The reaction conditions are mild (temperature ≤80℃, atmospheric pressure), which is suitable for continuous industrial production. The production cost is only 10%-15% higher than that of single-shell microcapsules. Attached Figure Description

[0057] Figure 1 The image shown is a physical picture of the finished product of the double-shell microcapsule in Example 1.

[0058] Figure 2 The image shown is a physical picture of the finished product of the double-shell microcapsule in Example 2.

[0059] Figure 3 The image shown is an enlarged view of the finished product of the double-shell microcapsule in Example 1. Detailed Implementation

[0060] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0061] In the following embodiments: Average particle size test: obtained by laser particle size analyzer, CV = (standard deviation / average particle size) × 100%.

[0062] Thickness test: obtained by scanning electron microscopy.

[0063] Coating rate test: obtained by gas chromatography.

[0064] Storage stability test: After storing the double-shell microcapsules at 25°C for 6 months, the volatilization rate of perfluorohexanone was tested by gas chromatography.

[0065] Fire extinguishing performance test: 1m 3 Fire extinguishing performance was tested in a confined space using commercial-grade n-heptane as fuel. The extinguishing time was measured with a stopwatch. The double-shell microcapsules were fixed to the surface of a stamped steel plate and placed 1.5 cm below the outer flame of the flame with the double-shell microcapsules facing downwards. The extinguishing time at 6 points on the double-shell microcapsules was measured, and the average value was taken to represent the fire extinguishing performance. The extinguishing time and 24-hour reignition status were recorded.

[0066] Heat resistance test: After heating the double-shell microcapsules at 100℃ for 1 hour, the volatilization rate of perfluorohexanone was tested by gas chromatography.

[0067] Electrolyte resistance test: The double-shell microcapsules were immersed in 1.0M LiPF6 EC / DMC / EMC (1:1:1 volume ratio) standard electrolyte, sealed and placed in a 60°C oven for 90 days. The perfluorohexanone release rate was then tested by gas chromatography.

[0068] Vertical burning test: The fire rating of the cable sheath prepared by blending double-shell microcapsules (addition amount 5wt%) with polyethylene was tested to UL94. Example 1

[0069] 10g of isophorone diisocyanate (IPDI) and 2g of polyethylene glycol 400 (PEG400) were pre-reacted at 35°C for 30 minutes to obtain a prepolymer; Take 50g of perfluorohexanone with a purity of 99.8wt%, add it to the above prepolymer, and mix well to form the oil phase; take 200mL of deionized water, add 2g of Span-80, 1g of Tween-80 and 3g of ethylenediamine (EDA), and stir to dissolve to form the aqueous phase; slowly add the oil phase to the aqueous phase, and stir at 15℃ and 5000rpm for 15min to form an emulsion; heat to 40℃ and stir at 80rpm for 4h to react and obtain the inner capsule core material; Add 150 mL of deionized water containing 2 g of PVP to the above-mentioned inner capsule core material, and sonicate at 5 °C for 15 min; add 8 g of methyltrimethoxysilane (MTMS) and 1.2 g of γ-aminopropyltriethoxysilane (KH550), adjust the pH to 8.5 with 0.1 mol / L NaOH aqueous solution, heat to 40 °C, and stir at 80 rpm for 6 h; cool to room temperature, add 0.3 g of nano-silica (average particle size 20 nm), stir for 12 min, centrifuge (1000 rpm, 12 min), centrifuge (1000 rpm, 12 min), wash three times with deionized water, and freeze-dry (-45 °C, vacuum degree 5 Pa, drying for 18 h) to obtain the double-shell microcapsule product.

[0070] A picture of the finished product of the double-shell microcapsule is shown below. Figure 1 As shown.

[0071] The average particle size of the double-shell microcapsules was 126 μm, with a CV of 4.8%.

[0072] The average thickness of the inner shell in the double-shell microcapsule is 12 μm, and the average thickness of the outer shell is 22 μm.

[0073] The encapsulation rate of the double-shell microcapsules was 92.3 wt%.

[0074] After being stored at 25°C for 6 months, the perfluorohexanone volatilization rate of the double-shell microcapsules was 4.2 wt%.

[0075] In the fire extinguishing performance test, the fire extinguishing time was 5.24 seconds, and there was no reignition after 24 hours.

[0076] The release rate of perfluorohexanone in the heat resistance test was 12.7 wt%.

[0077] The perfluorohexanone release rate was 6.1 wt% in the electrolyte resistance test. Example 2

[0078] 14g of isophorone diisocyanate (IPDI) and 2g of polyethylene glycol 400 (PEG400) were pre-reacted at 35°C for 30 minutes to obtain a prepolymer; Take 60g of perfluorohexanone with a purity of 99.8wt%, add it to the above prepolymer, and mix well to form the oil phase; take 200mL of deionized water, add 2g of Span-80, 1g of Tween-80 and 3g of ethylenediamine (EDA), and stir to dissolve to form the aqueous phase; slowly add the oil phase to the aqueous phase, and stir at 15℃ and 5000rpm for 15min to form an emulsion; raise the temperature to 34℃ and stir at 80rpm for 4h to carry out the reaction, and obtain the inner capsule core material; Add 180 mL of deionized water containing 3 g of PVP to the above-mentioned inner capsule core material, and ultrasonically disperse at 5 °C for 20 min; add 10 g of E-51 epoxy resin, stir at 60 rpm for 10 min, then slowly add 2 g of DETA curing agent, adjust the pH to 8.2 with 0.1 mol / L NaOH aqueous solution, heat to 40 °C, and stir at 60 rpm for 5 h; cool to room temperature, add 0.5 g of nano silica (average particle size 20 nm), stir for 15 min, centrifuge (1000 rpm, 12 min), centrifuge (1000 rpm, 12 min), wash three times with deionized water, and freeze-dry (-45 °C, vacuum degree 5 Pa, drying for 18 h) to obtain the double-shell microcapsule product.

[0079] A picture of the finished product of the double-shell microcapsule is shown below. Figure 2 As shown in the enlarged image Figure 3 As shown.

[0080] The average particle size of the double-shell microcapsules is 175 μm, and the CV is 4%.

[0081] The average thickness of the inner shell in the double-shell microcapsule is 15 μm, and the average thickness of the outer shell is 24 μm.

[0082] The encapsulation rate of the double-shell microcapsules was 91.5 wt%.

[0083] After being stored at 25°C for 6 months, the perfluorohexanone volatilization rate of the double-shell microcapsules was 4.6 wt%.

[0084] In the fire extinguishing performance test, the fire extinguishing time was 5.18 seconds, and there was no reignition after 24 hours.

[0085] The release rate of perfluorohexanone in the heat resistance test was 15 wt%.

[0086] The perfluorohexanone release rate was 8.4 wt% in the electrolyte resistance test.

[0087] The vertical burning test achieved the UL94 V-0 rating. Example 3

[0088] 0.4g of alumina nanofibers (average diameter 6nm, average length 250nm, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.), 0.6g of organomontmorillonite (purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., average particle size 400nm, model: I.31PS) and 10g of isophorone diisocyanate (IPDI) were ultrasonically treated for 30 minutes to form a uniform suspension. Then, 2g of polyethylene glycol 400 (PEG400) was added and pre-reacted at 35℃ for 30 minutes to obtain a prepolymer. Take 50g of perfluorohexanone with a purity of 99.8wt%, add it to the above prepolymer, and mix well to form the oil phase; take 200mL of deionized water, add 2g of Span-80, 1g of Tween-80 and 3g of ethylenediamine (EDA), and stir to dissolve to form the aqueous phase; slowly add the oil phase to the aqueous phase, and stir at 15℃ and 5000rpm for 15min to form an emulsion; heat to 40℃ and stir at 80rpm for 4h to react and obtain the inner capsule core material; Add 150 mL of deionized water containing 1 g of polyhexamethylene biguanide and 1 g of block copolymer P123 to the above-mentioned inner capsule core material, and sonicate at 5 °C for 15 min; add 5 g of methyltrimethoxysilane (MTMS), 1 g of γ-aminopropyltriethoxysilane (KH550) and 3 g of bis-[3-(triethoxysilyl)propyl] disulfide, adjust the pH to 8.5 with 0.1 mol / L NaOH aqueous solution, stir at room temperature for 8 h, then raise the temperature to 70 °C and stir for 2 h; cool to room temperature, add 0.3 g of nano silica (average particle size 20 nm), stir for 12 min, centrifuge (1000 rpm, 12 min), centrifuge again (1000 rpm, 12 min), wash three times with deionized water, and freeze-dry (-45 °C, vacuum degree 5 Pa, drying for 18 h) to obtain the double-shell microcapsule product.

[0089] The average particle size of the double-shell microcapsules is 154 μm, and the CV is 3.2%.

[0090] The average thickness of the inner shell in the double-shell microcapsule is 10 μm, and the average thickness of the outer shell is 24 μm.

[0091] The encapsulation rate of the double-shell microcapsules was 94.8 wt%.

[0092] After being stored at 25°C for 6 months, the perfluorohexanone volatilization rate of the double-shell microcapsules was 1.52 wt%.

[0093] In the fire extinguishing performance test, the fire extinguishing time was 3.64 seconds, and there was no reignition after 24 hours.

[0094] The perfluorohexanone release rate in the heat resistance test was 5.2 wt%.

[0095] The perfluorohexanone release rate in the electrolyte resistance test was <0.5wt%. Example 4

[0096] 0.4g of alumina nanofibers (average diameter 6nm, average length 250nm, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.), 0.6g of organomontmorillonite (purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., average particle size 400nm, model: I.31PS) and 14g of isophorone diisocyanate (IPDI) were ultrasonically treated for 30 minutes to form a uniform suspension. Then, 2g of polyethylene glycol 400 (PEG400) was added and pre-reacted at 35℃ for 30 minutes to obtain a prepolymer. Take 60g of perfluorohexanone with a purity of 99.8wt%, add it to the above prepolymer, and mix well to form the oil phase; take 200mL of deionized water, add 2g of Span-80, 1g of Tween-80 and 3g of ethylenediamine (EDA), and stir to dissolve to form the aqueous phase; slowly add the oil phase to the aqueous phase, and stir at 15℃ and 5000rpm for 15min to form an emulsion; raise the temperature to 34℃ and stir at 80rpm for 4h to carry out the reaction, and obtain the inner capsule core material; Add 180 mL of deionized water containing 1 g of polyhexamethylene biguanide and 1 g of block copolymer P123 to the above-mentioned inner capsule core material, and ultrasonically disperse for 20 min; add 10 g of E-51 epoxy resin, stir at 60 rpm for 10 min, then slowly add 2 g of 4,4'-diaminodiphenyl disulfide, adjust the pH to 8.2 with 0.1 mol / L NaOH aqueous solution, heat to 40℃, and stir at 60 rpm for 5 h; cool to room temperature, add 0.5 g of nano-silica (average particle size 20 nm), stir for 15 min, centrifuge (1000 rpm, 12 min), centrifuge (1000 rpm, 12 min), wash three times with deionized water, and freeze-dry (-45℃, vacuum degree 5 Pa, drying for 18 h) to obtain the double-shell microcapsule product.

[0097] The average particle size of the double-shell microcapsules is 147 μm, and the CV is 3.6%.

[0098] The average thickness of the inner shell in the double-shell microcapsule is 8 μm, and the average thickness of the outer shell is 22 μm.

[0099] The encapsulation rate of the double-shell microcapsules was 93.5 wt%.

[0100] After being stored at 25°C for 6 months, the perfluorohexanone volatilization rate of the double-shell microcapsules was 1.8 wt%.

[0101] In the fire extinguishing performance test, the fire extinguishing time was 4.12 seconds, and there was no reignition after 24 hours.

[0102] The release rate of perfluorohexanone in the heat resistance test was 6 wt%.

[0103] The perfluorohexanone release rate was 0.8 wt% in the electrolyte resistance test.

[0104] The vertical burning test achieved the UL94 V-0 rating. Example 5

[0105] The method of Example 3 differs in that: 1g of alumina nanofibers (average diameter 6nm, average length 250nm, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.) and 10g of isophorone diisocyanate (IPDI) were ultrasonically treated for 30 minutes to form a uniform suspension. Then, 2g of polyethylene glycol 400 (PEG400) was added and pre-reacted at 35℃ for 30 minutes to obtain a prepolymer. The rest is the same as in Example 3, and double-shell microcapsules are prepared.

[0106] The average particle size of the double-shell microcapsules is 140 μm, and the CV is 6%.

[0107] The average thickness of the inner shell in the double-shell microcapsule is 18 μm, and the average thickness of the outer shell is 22 μm.

[0108] The encapsulation rate of the double-shell microcapsules was 90.2 wt%.

[0109] After being stored at 25°C for 6 months, the perfluorohexanone volatilization rate of the double-shell microcapsules was 3 wt%.

[0110] In the fire extinguishing performance test, the fire extinguishing time was 4.51 seconds, and there was no reignition after 24 hours.

[0111] The release rate of perfluorohexanone in the heat resistance test was 7.48 wt%.

[0112] The perfluorohexanone release rate was 5.83 wt% in the electrolyte resistance test. Example 6

[0113] 1g of organomontmorillonite (purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., with an average particle size of 400nm, model: I.31PS) and 10g of isophorone diisocyanate (IPDI) were ultrasonically treated for 30 minutes to form a uniform suspension. Then, 2g of polyethylene glycol 400 (PEG400) was added and pre-reacted at 35℃ for 30 minutes to obtain a prepolymer. The rest is the same as in Example 3, and double-shell microcapsules are prepared.

[0114] The average particle size of the double-shell microcapsules is 182 μm, and the CV is 5.5%.

[0115] The average thickness of the inner shell in the double-shell microcapsule is 9 μm, and the average thickness of the outer shell is 25 μm.

[0116] The encapsulation rate of the double-shell microcapsules was 93 wt%.

[0117] After being stored at 25°C for 6 months, the perfluorohexanone volatilization rate of the double-shell microcapsules was 2.2 wt%.

[0118] In the fire extinguishing performance test, the fire extinguishing time was 4.78 seconds, and there was no reignition after 24 hours.

[0119] The release rate of perfluorohexanone in the heat resistance test was 11.2 wt%.

[0120] The perfluorohexanone release rate was 1.2 wt% in the electrolyte resistance test. Example 7

[0121] The method of Example 3 differs in that: Add 150 mL of polyhexamethylene biguanide containing 2 g to the above-mentioned inner capsule core material; The rest is the same as in Example 3, and double-shell microcapsules are prepared.

[0122] The average particle size of the double-shell microcapsules is 168 μm, and the CV is 4.4%.

[0123] The encapsulation rate of the double-shell microcapsules was 92.5 wt%.

[0124] The average thickness of the inner shell in the double-shell microcapsule is 8 μm, and the average thickness of the outer shell is 25 μm.

[0125] After being stored at 25°C for 6 months, the perfluorohexanone volatilization rate of the double-shell microcapsules was 2 wt%.

[0126] In the fire extinguishing performance test, the fire extinguishing time was 5.03 seconds, and there was no reignition after 24 hours.

[0127] The release rate of perfluorohexanone in the heat resistance test was 5.8 wt%.

[0128] The perfluorohexanone release rate was 1 wt% in the electrolyte resistance test. Example 8

[0129] The method of Example 3 differs in that: Add 150 mL of deionized water containing 1 g of polyhexamethylene biguanide and 1 g of block copolymer P123 to the above-mentioned inner capsule core material, and sonicate at 5 °C for 15 min; add 8 g of methyltrimethoxysilane (MTMS) and 1.2 g of γ-aminopropyltriethoxysilane (KH550), adjust the pH to 8.5 with 0.1 mol / L NaOH aqueous solution, stir at room temperature for 8 h, then raise the temperature to 70 °C and stir for 2 h; cool to room temperature, add 0.3 g of nano-silica (average particle size 20 nm), stir for 12 min, centrifuge (1000 rpm, 12 min), centrifuge again (1000 rpm, 12 min), wash three times with deionized water, and freeze-dry (-45 °C, vacuum degree 5 Pa, drying for 18 h) to obtain the double-shell microcapsule product. The average particle size of the double-shell microcapsules was 196 μm, with a CV of 7.2%.

[0130] The average thickness of the inner shell in the double-shell microcapsule is 10 μm, and the average thickness of the outer shell is 36 μm.

[0131] The encapsulation rate of the double-shell microcapsules was 91.1 wt%.

[0132] After being stored at 25°C for 6 months, the perfluorohexanone volatilization rate of the double-shell microcapsules was 2.8 wt%.

[0133] In the fire extinguishing performance test, the fire extinguishing time was 5.23 seconds, and there was no reignition after 24 hours.

[0134] The release rate of perfluorohexanone in the heat resistance test was 8.6 wt%.

[0135] The perfluorohexanone release rate was 3.4 wt% in the electrolyte resistance test.

[0136] Comparative Example 1 Take 50g of 99.8wt% perfluorohexanone as the oil phase; take 200mL of deionized water, add 12g of gelatin and 0.01g of phenyl salicylate at 60℃, stir and dissolve to form the aqueous phase; slowly add the oil phase to the aqueous phase, stir at 350rpm for 45min to form an O / W emulsion; slowly add 2mL of 20wt% glutaraldehyde aqueous solution to the emulsion as a curing agent, continue stirring at 35℃ for 2 hours to allow the gelatin to crosslink and cure. After the reaction is completed, centrifuge (1000rpm, 12min), wash three times with deionized water, and freeze-dry (-45℃, vacuum degree 5Pa, drying for 18h) to obtain the microcapsule product.

[0137] The average particle size of the microcapsules was 245 μm, and the CV was 7.2%.

[0138] The average thickness of the capsule shell in the microcapsule is 35 μm.

[0139] The encapsulation rate of the double-shell microcapsules was 88.5 wt%.

[0140] After being stored at 25°C for 6 months, the perfluorohexanone volatilization rate of the double-shell microcapsules was 8.7 wt%.

[0141] In the fire extinguishing performance test, the fire extinguishing time was 8.6 seconds, and the fire reignited after 24 hours.

[0142] The release rate of perfluorohexanone in the heat resistance test was 25.3 wt%.

[0143] The perfluorohexanone release rate was 32.1 wt% in the electrolyte resistance test.

[0144] Through the above examples and comparative examples, it can be seen that the perfluorohexanone microcapsules provided by the present invention have excellent mechanical strength, electrolyte resistance and fire extinguishing performance.

[0145] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, various different embodiments of the present invention can be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be considered as the content disclosed by the present invention.

Claims

1. A perfluorohexanone double-shell microcapsule, characterized in that, Includes a capsule core and a capsule shell covering the capsule core; The capsule core contains perfluorohexanone; the capsule shell includes an inner shell and an outer shell covering the inner shell; the inner shell includes a first polymer material, which includes at least one of polyurea, polyurethane, and polylactic acid; the outer shell includes a second polymer material, which includes at least one of silicone resin, modified epoxy resin, and cross-linked polyvinyl alcohol.

2. The perfluorohexanone double-shell microcapsule according to claim 1, characterized in that, The polyurea is formed by polymerizing isophorone diisocyanate and polyethylene glycol 400 prepolymer with ethylenediamine; the polyurethane is formed by polymerizing toluene diisocyanate and 1,4-butanediol.

3. The perfluorohexanone double-shell microcapsule according to claim 1, characterized in that, The organosilicon resin is obtained by polymerizing silane monomers, including methyltrimethoxysilane and γ-aminopropyltriethoxysilane; the modified epoxy resin includes epoxy resin and amine compounds.

4. The perfluorohexanone double-shell microcapsule according to claim 1, characterized in that, The average thickness of the inner shell is 5-20 μm; the average thickness of the outer shell is 15-30 μm; and the average particle size of the perfluorohexanone double-shell microcapsules is 100-200 μm.

5. A method for preparing perfluorohexanone double-shell microcapsules according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: S1: Emulsify perfluorohexanone, the inner shell material used to form the inner shell, and an aqueous solution containing an emulsifier to form an emulsion, and then carry out the first polymerization reaction to obtain the inner core material; S2: Add an aqueous solution containing a dispersant to the obtained inner core material, then add the outer shell monomer for forming the outer shell, adjust the pH to 7.5-9, then carry out the second polymerization reaction, add an anti-blocking agent and mix, then carry out post-treatment to obtain perfluorohexanone double shell microcapsules. The inner shell material includes an inner shell monomer, which includes a monomer for forming at least one of polyurea, polyurethane, and polylactic acid, and the outer shell monomer includes a monomer for forming at least one of silicone resin, modified epoxy resin, and cross-linked polyvinyl alcohol.

6. The method for preparing perfluorohexanone double-shell microcapsules according to claim 5, characterized in that, The emulsifier includes a compound of Span-80 and Tween-80; the emulsifier has a mass content of 0.5%-2% in water; and the inner shell monomer has a mass content of 2%-20% in water.

7. The method for preparing perfluorohexanone double-shell microcapsules according to claim 5, characterized in that, In step S1, the conditions for the first polymerization reaction include: 30-45℃, stirring at 60-100 rpm for 2-6 hours.

8. The method for preparing perfluorohexanone double-shell microcapsules according to claim 5, characterized in that, The dispersant includes at least one of polyvinylpyrrolidone, polyhexamethylene biguanide, block copolymer P123, and sodium carboxymethyl cellulose; the mass content of the dispersant in the aqueous solution containing the dispersant is 1%-3%; the mass ratio of the inner core material to the aqueous solution containing the dispersant is 1:(0.01-10).

9. The method for preparing perfluorohexanone double-shell microcapsules according to claim 5, characterized in that, In step S2, the conditions for the second polymerization reaction include: reacting at pH 7.5-9 and 25-45°C for 2-10 hours; the anti-blocking agent includes nano-silica and / or talc; the mass of the anti-blocking agent is 0.1%-0.5% of the mass of the aqueous solution containing the dispersant; in step S2, the conditions for the post-treatment include: centrifugation, centrifugal washing, and freeze drying.

10. The application of the perfluorohexanone double-shell microcapsule according to any one of claims 1-4, characterized in that, The applications include at least one of the following: self-extinguishing materials for electronic devices, flame-retardant sheaths for cables, flame-retardant materials for new energy batteries, and clean fire extinguishing agents for precision instruments.

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