Device and method for preparing perfluorohexanone microcapsules

Abstract

The invention relates to the field of microcapsule preparation equipment, and discloses a perfluorohexanone microcapsule preparation device and method.The perfluorohexanone microcapsule preparation device comprises a micro-fluidic chip, a core material supply unit, a wall material supply unit and a microcapsule collection unit, and the micro-fluidic chip is provided with a micro-channel; the core material supply unit and the wall material supply unit are communicated with the input end of the microchannel, the microcapsule collection unit is communicated with the output end of the microchannel, and the microcapsule collection unit is used for collecting microcapsules output from the output end of the microchannel. The wall material fluid is supplied to the micro-channel through the wall material supply unit, the core material fluid comprises the perfluorohexanone, in the micro-channel, the core material fluid is wrapped by the wall material fluid to form the microcapsule, the preparation of the perfluorohexanone microcapsule is realized by adopting the micro-fluidic chip, the wall thickness uniformity of the perfluorohexanone microcapsule is relatively good, and the production quality is relatively high.

Description

Technical Field

[0001] This invention belongs to the field of microcapsule preparation equipment, and more specifically, relates to an apparatus for preparing perfluorohexanone microcapsules. Background Technology

[0002] Perfluorohexanone (PFH), as a novel clean fire extinguishing agent, boasts advantages such as high extinguishing efficiency, non-conductivity, no solid residue after extinguishing, and zero ozone depletion potential, making it suitable for protecting critical objects such as data centers, electrical cabinets, and lithium-ion battery compartments. However, PFH has a low boiling point and high vapor pressure, making it prone to volatilization and leakage at room temperature. This leads to problems such as loss of active ingredients and poor stability during storage. Therefore, microencapsulation technology is commonly used to encapsulate PFH to improve its storage stability. Currently, the preparation of PFH microcapsules is usually achieved using a stirring device, which uses the shear force generated by mechanical stirring to disperse materials and form capsules. However, due to the uneven distribution of the shear force generated by mechanical stirring within the reaction system, the resulting PFH microcapsules have poor wall thickness uniformity, leading to low production quality. Summary of the Invention

[0003] The main objective of this invention is to provide an apparatus for preparing perfluorohexanone microcapsules, which produces perfluorohexanone microcapsules with high quality.

[0004] According to a first aspect of the present invention, an apparatus for preparing perfluorohexanone microcapsules is provided, comprising a microfluidic chip, a core material supply unit, a wall material supply unit, and a microcapsule collection unit. The microfluidic chip has a microchannel. The core material supply unit and the wall material supply unit are connected to the input end of the microchannel, and the microcapsule collection unit is connected to the output end of the microchannel. The core material supply unit is used to input a core material fluid, which includes perfluorohexanone, into the microchannel. The wall material supply unit is used to input a wall material fluid into the microchannel. The microchannel is used to encapsulate the core material fluid with the wall material fluid to form microcapsules. The microcapsule collection unit is used to collect the microcapsules output from the output end of the microchannel.

[0005] In a specific embodiment of the present invention, the wall material supply unit includes a first supply module and a second supply module. The first supply module and the second supply module are connected to the input end of the microchannel. The first supply module is used to input a first wall material fluid into the microchannel to form the inner shell layer of the microcapsule, and the second supply module is used to input a second wall material fluid into the microchannel to form the outer shell layer of the microcapsule.

[0006] In a specific embodiment of the present invention, the microchannel includes a first input subchannel, a second input subchannel, a third input subchannel, a curing subchannel, and an output subchannel. The input end of the first input subchannel is connected to the core material supply unit. The output end of the first input subchannel is inserted along a first direction and connected to the second input subchannel. The input end of the second input subchannel is connected to the first supply module. The output end of the second input subchannel is inserted along the first direction and connected to the third input subchannel. The input end of the third input subchannel is connected to the second supply module. The output end of the third input subchannel is connected to the curing subchannel. The curing subchannel is connected to the output subchannel. The output subchannel is connected to the microcapsule collection unit.

[0007] In one specific embodiment of the present invention, the curing subchannel is serpentine.

[0008] In a specific embodiment of the present invention, the microfluidic chip has an observation window, which is set corresponding to the output sub-channel.

[0009] In a specific embodiment of the present invention, the invention further includes a housing and a volatile matter condensation and collection unit. The housing has an inert atmosphere chamber, and an inlet pipe and an outlet pipe communicating with the inert atmosphere chamber. The inlet pipe is used to input inert gas, and the outlet pipe is connected to the volatile matter condensation and collection unit, which is used to condense the volatilized perfluorohexanone.

[0010] The microfluidic chip and the microcapsule collection unit are located in the inert atmosphere cavity.

[0011] In a particular embodiment of the present invention, a recovery pipe is further included, which connects the volatile matter condensation and collection unit to the core material supply unit.

[0012] In one specific embodiment of the present invention, a temperature control unit is further included, which is connected to the housing and is used to control the temperature of the microfluidic chip.

[0013] In a specific embodiment of the present invention, the core material supply unit includes a first container, a first delivery pipe and a first plunger pump. The first container is used to store core material fluid, the first delivery pipe connects the first container and the input end of the microchannel, and the first plunger pump is connected to the first delivery pipe.

[0014] In a specific embodiment of the present invention, the first supply module includes a second container, a second delivery pipe and a second plunger pump. The second container is used to store the first wall material fluid. The second delivery pipe connects the second container and the input end of the microchannel. The second plunger pump is connected to the second delivery pipe.

[0015] The second supply module includes a third container, a third delivery pipe, and a third plunger pump. The third container is used to store the second wall material fluid. The third delivery pipe connects the third container and the input end of the microchannel. The third plunger pump is connected to the third delivery pipe.

[0016] The second technical solution provided by this invention is as follows:

[0017] A method for preparing perfluorohexanone microcapsules, using the perfluorohexanone microcapsule preparation apparatus described in the first technical solution as a reactor, the specific method is as follows:

[0018] 1) Place the microfluidic chip and microcapsule collection unit in a sealed inert atmosphere chamber, continuously introduce nitrogen into the chamber to maintain the inert environment, and connect the chamber exhaust port to a condensation recovery unit with a set temperature of -5℃ to recover volatiles.

[0019] 2) Prepare the core material fluid by using perfluorohexanone as the main material, adding hydrophobic fumed silica as a porous carrier, and dissolving isophorone diisocyanate as the inner shell reaction monomer. After uniform dispersion, place it in an ice bath for later use.

[0020] The first wall material fluid was prepared by using deionized water as the dispersion medium, adding polyvinyl alcohol as a dispersant and additive, dissolving diethylenetriamine as a water-soluble crosslinking chain extender, and then performing vacuum degassing treatment.

[0021] To prepare the second wall material fluid, polyethylene glycol diacrylate, photoinitiator Irgacure2959, and nano titanium dioxide were added to deionized water.

[0022] 3) Activate the temperature control unit, set the temperature of the droplet generation area of ​​the microfluidic chip to 15°C to suppress volatilization, set the inner shell formation temperature of the first reaction channel to 30°C, set the outer shell formation temperature of the second input sub-channel to 30°C, and set the curing and aging channel temperature to 35°C.

[0023] 4) Adjust the system back pressure regulator to stabilize the pressure inside the microfluidic chip at 0.25 MPa;

[0024] 5) Start the feed pump and inject the sample simultaneously at the following flow rates: core material fluid flow rate is 20 μL / min, first wall material fluid flow rate is 400 μL / min, and second wall material fluid flow rate is 300 μL / min;

[0025] The core material and the first wall material form perfluorohexanone droplets in the droplet generation area and undergo interfacial polymerization in the first input sub-channel to form a polyurea inner shell. Subsequently, it merges with the second wall material in the second input sub-channel to cover the outer layer. When flowing through the curing sub-channel, it is photocured by ultraviolet light source.

[0026] The product is discharged through a back pressure regulator into a capsule collection unit. After solid-liquid separation and washing with deionized water, it is freeze-dried under vacuum to obtain perfluorohexanone microcapsules with a double-shell structure.

[0027] Furthermore, the above-mentioned method for preparing perfluorohexanone microcapsules uses the fluorohexanone microcapsule preparation apparatus described in the first technical solution as a reactor, and the specific method is as follows:

[0028] 1) Place the microfluidic chip and microcapsule collection unit in a sealed inert atmosphere chamber, continuously introduce nitrogen into the chamber to maintain the inert environment, and connect the chamber exhaust port to a condensation recovery unit with a set temperature of -5℃ to recover volatiles.

[0029] 2) Prepare the core material fluid by weighing 45 g of perfluorohexanone as the main material, adding 1.0 g of hydrophobic fumed silica as a porous carrier, and dissolving 4.0 g of isophorone diisocyanate as the inner shell reaction monomer. After ultrasonic dispersion, place it in an ice bath for later use.

[0030] To prepare the first wall material fluid, 96 mL of deionized water was measured as the dispersion medium, 2.0 g of polyvinyl alcohol was added as a dispersant and additive, and 2.0 g of diethylenetriamine was dissolved as a water-soluble crosslinking chain extender. The fluid was then subjected to vacuum degassing.

[0031] To prepare the second wall material fluid, measure 80 mL of deionized water, dissolve 20.0 g of polyethylene glycol diacrylate as a photocurable monomer, add 1.0 g of photoinitiator Irgacure 2959, and disperse 1.0 g of nano titanium dioxide as an inorganic filler to enhance the heat resistance of the shell.

[0032] 3) Activate the temperature control unit, set the temperature of the droplet generation area of ​​the microfluidic chip to 15°C to suppress volatilization, set the inner shell formation temperature of the first reaction channel to 30°C, set the outer shell formation temperature of the second input sub-channel to 30°C, and set the curing and aging channel temperature to 35°C.

[0033] 4) Adjust the system back pressure regulator to stabilize the pressure inside the microfluidic chip at 0.25 MPa;

[0034] 5) Start the feed pump and inject the sample simultaneously at the following flow rates: core material fluid flow rate is 20 μL / min, first wall material fluid flow rate is 400 μL / min, and second wall material fluid flow rate is 300 μL / min;

[0035] The core material and the first wall material form perfluorohexanone droplets in the droplet generation area and undergo interfacial polymerization in the first input sub-channel to form a polyurea inner shell. Subsequently, it merges with the second wall material in the second input sub-channel to cover the outer layer. When flowing through the curing sub-channel, it is photocured by ultraviolet light source.

[0036] The product is discharged through a back pressure regulator into a capsule collection unit. After solid-liquid separation and washing with deionized water, it is freeze-dried under vacuum to obtain perfluorohexanone microcapsules with a double-shell structure.

[0037] One of the above-described technical solutions of the present invention has at least one of the following advantages or beneficial effects:

[0038] In practical applications, the apparatus for preparing perfluorohexanone microcapsules of the present invention supplies core material fluid to the microchannel through a core material supply unit and wall material fluid to the microchannel through a wall material supply unit. The core material fluid includes perfluorohexanone. In the microchannel, the wall material fluid encapsulates the core material fluid to form microcapsules. The preparation of perfluorohexanone microcapsules is achieved by using a microfluidic chip. The perfluorohexanone microcapsules have good wall thickness uniformity and high production quality. Attached Figure Description

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0040] Figure 1 This is a structural diagram of the apparatus for preparing perfluorohexanone microcapsules according to an embodiment of the present invention;

[0041] Figure 2 This is a structural diagram of the microfluidic chip according to an embodiment of the present invention.

[0042] The figure labels for each figure are as follows:

[0043] 1. Microfluidic chip; 10. Microchannel; 101. First input subchannel; 102. Second input subchannel; 103. Third input subchannel; 104. Curing subchannel; 105. Output subchannel; 11. Observation window;

[0044] 2. Core material supply unit; 21. First container; 22. First delivery pipe; 23. First plunger pump;

[0045] 3. Wall material supply unit; 31. First supply module; 311. Second container; 312. Second delivery pipe; 313. Second plunger pump; 32. Second supply module; 321. Third container; 322. Third delivery pipe; 323. Third plunger pump;

[0046] 4. Microcapsule collection unit;

[0047] 5. Enclosure; 501. Inert atmosphere chamber; 502. Inlet pipe; 503. Outlet pipe;

[0048] 6. Volatile matter condensation and collection unit;

[0049] 7. Recycling pipe;

[0050] 8. Temperature control unit;

[0051] 9. Back pressure regulator;

[0052] X. First direction.

[0053] Figure 3 These are scanning electron microscope images of perfluorohexanone microcapsules provided in Example 2 and Comparative Example 1. Detailed Implementation

[0054] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0055] Example 1

[0056] Reference Figures 1 to 2 As shown, a preferred embodiment of the present application discloses an apparatus for preparing perfluorohexanone microcapsules, comprising a microfluidic chip 1, a core material supply unit 2, a wall material supply unit 3, and a microcapsule collection unit 4. The microfluidic chip 1 has a microchannel 10. The core material supply unit 2 and the wall material supply unit 3 are connected to the input end of the microchannel 10, and the microcapsule collection unit 4 is connected to the output end of the microchannel 10. The core material supply unit 2 is used to input a core material fluid, which includes perfluorohexanone, into the microchannel 10. The wall material supply unit 3 is used to input a wall material fluid into the microchannel 10. The microchannel 10 is used to encapsulate the core material fluid with the wall material fluid to form microcapsules. The microcapsule collection unit 4 is used to collect the microcapsules output from the output end of the microchannel 10.

[0057] In practical applications, the core material fluid is supplied to the microchannel 10 through the core material supply unit 2, and the wall material fluid is supplied to the microchannel 10 through the wall material supply unit 3. The core material fluid includes perfluorohexanone. In the microchannel 10, the wall material fluid encapsulates the core material fluid to form microcapsules. The preparation of perfluorohexanone microcapsules is achieved by using the microfluidic chip 1. The perfluorohexanone microcapsules have good wall thickness uniformity and high production quality.

[0058] Furthermore, the wall material supply unit 3 includes a first supply module 31 and a second supply module 32. The first supply module 31 and the second supply module 32 are connected to the input end of the microchannel 10. The first supply module 31 is used to input a first wall material fluid into the microchannel 10 to form the inner shell layer of the microcapsule, and the second supply module 32 is used to input a second wall material fluid into the microchannel 10 to form the outer shell layer of the microcapsule. Thus, the microcapsule has an inner shell layer and an outer shell layer, which can better protect the perfluorohexanone as the core material, and the microcapsule has higher stability.

[0059] In this embodiment, the microchannel 10 includes a first input subchannel 101, a second input subchannel 102, a third input subchannel 103, a curing subchannel 104, and an output subchannel 105. The input end of the first input subchannel 101 is connected to the core material supply unit 2, and the output end of the first input subchannel 101 is inserted along the first direction and connected to the second input subchannel 102. The input end of the second input subchannel 102 is connected to the first supply module 31, and the output end of the second input subchannel 102 is inserted along the first direction and connected to the third input subchannel 105. Channel 103, the input end of the third input sub-channel 103 is connected to the second supply module 32, the output end of the third input sub-channel 103 is connected to the curing sub-channel 104, the curing sub-channel 104 is connected to the output sub-channel 105, and the output sub-channel 105 is connected to the microcapsule collection unit 4. Specifically, the output port of the first input sub-channel 101 is at a distance from the inner wall surface of the second input sub-channel 102. Thus, when the core material supply unit 2 inputs core material fluid to the second input channel 102 via the first input sub-channel 101, the first supply... After the first wall material fluid is input into the second input sub-channel 102 by module 31, the first wall material fluid can encapsulate the core material fluid to form a first fluid structure. Similarly, the output port of the second input sub-channel 102 is also at a distance from the inner wall surface of the third input sub-channel 103. Therefore, after the second supply module 32 inputs the second wall material fluid into the third input sub-channel 103, the second wall material fluid can encapsulate the aforementioned first fluid structure to form microcapsules. The microcapsules are then solidified in the solidification sub-channel 104 and output from the output sub-channel 105 to the microcapsules. In the collection unit 4; the output port of the first input sub-channel 101 is circular, and the inner wall of the second input sub-channel 102 forms a cylindrical structure. The output port of the first input sub-channel 101 and the inner wall of the second input sub-channel 102 are equidistant in the circumferential direction to ensure uniform thickness of the inner shell layer; the output port of the second input sub-channel 102 is circular, and the inner wall of the third input sub-channel 103 forms a cylindrical structure. The output port of the second input sub-channel 102 and the inner wall of the third input sub-channel 103 are equidistant in the circumferential direction to ensure uniform thickness of the outer shell layer.

[0060] It should be noted that the core material fluid includes perfluorohexanone, and may also include porous inorganic carriers, free radical initiators or stabilizers, etc., which are not limited in this application; while the first wall material fluid includes film-forming polymers or their monomers / prepolymers, crosslinking agents, dispersion media and additives; the second wall material fluid includes second shell material monomers or prepolymers, inorganic filler dispersions, photoinitiators or other curing additives.

[0061] In this embodiment, the curing sub-channel 104 is serpentine and has a long path, which ensures the curing effect and makes the structure of the microfluidic chip 1 relatively compact.

[0062] In this embodiment, the microfluidic chip 1 has an observation window 11, which is set to correspond to the output sub-channel 105. The transparent window refers to a transparent structure, not to expose the output sub-channel 105. In practical applications, an optical acquisition module can be arranged facing the observation window 11, and the optical acquisition module acquires image information of the microcapsules at the observation window 11.

[0063] In this embodiment, the preparation device for perfluorohexanone microcapsules further includes a housing 5 and a volatile matter condensation and collection unit 6. The housing 5 has an inert atmosphere chamber 501 and an inlet pipe 502 and an outlet pipe 503 connected to the inert atmosphere chamber 501. The inlet pipe 502 is used to input inert gas, which can be nitrogen or argon. The outlet pipe 503 is connected to the volatile matter condensation and collection unit 6, which is used to condense the volatilized perfluorohexanone. The microfluidic chip 1 and the microcapsule collection unit 4 are disposed in the inert atmosphere chamber 501. Specifically, inert gas is supplied to the inlet pipe 502 through an inert gas supply device so that the inert gas enters the inert atmosphere chamber 501, thereby forming an inert atmosphere. The presence of the inert atmosphere can ensure the stability of the preparation process.

[0064] The aforementioned volatile matter condensation and collection unit 6 is capable of condensing condensable components in waste gas containing perfluorohexanone vapor, thereby reducing core material loss and emissions. The portion condensed and recovered includes perfluorohexanone.

[0065] Furthermore, the apparatus for preparing perfluorohexanone microcapsules also includes a recovery pipe 7, which is connected to the volatile matter condensation and collection unit 6 and the core material supply unit 2. Thus, the recovered perfluorohexanone can be transported to the core material supply unit 2 via the recovery pipe 7 for recycling.

[0066] In this embodiment, the volatile matter condensation and collection unit 6 includes a condenser, a collection container, and a recovery pump. The recovery pump can be a plunger pump. The condenser is connected to the outlet pipe 503, the collection container is connected to the condenser, and the recovery pipe 7 connects the collection container to the core material supply unit 2. The recovery pump is connected to the recovery pipe 7. The collection container is used to collect the perfluorohexanone recovered by condensation. The function of the recovery pump is to transport the perfluorohexanone in the collection container to the core material supply unit 2 through the recovery pipe 7, thereby realizing the recovery and utilization of perfluorohexanone. The working temperature of the condenser is controlled at -20~10℃ to condense and recover the vapor containing perfluorohexanone.

[0067] In this embodiment, the apparatus for preparing perfluorohexanone microcapsules further includes a temperature control unit 8, which is connected to the housing 5. The temperature control unit 8 is used to control the temperature of the microfluidic chip 1 so that the microfluidic chip 1 is at a suitable operating temperature. The temperature control unit 8 can be a high-low temperature integrated machine. The housing 5 is provided with temperature control channels corresponding to the microfluidic chip 1. The high-low temperature integrated machine is connected to the temperature control channels, and the temperature of the microfluidic chip 1 is controlled through the temperature control channels. Furthermore, there can be multiple high-low temperature integrated machines and temperature control channels. The channels correspond to different sub-channels of the microfluidic chip 1. Multiple high and low temperature integrated machines and multiple temperature control channels are connected one by one. In this way, the temperature of different sub-channels of the microfluidic chip 1 can be controlled, which is conducive to ensuring the stable preparation of microcapsules. For example, the temperature of the area where the output end of the first input sub-channel 101 is located is controlled at 15°C to suppress the volatilization of the core material and improve the droplet formation stability. The temperature of the area where the output end of the second input sub-channel 102 is located is controlled at 30°C, while the temperature of the area where the curing sub-channel 104 is located is controlled at 35°C to promote curing.

[0068] In this embodiment, the core material supply unit 2 includes a first container 21, a first delivery pipe 22, and a first plunger pump 23. The first container 21 is used to store the core material fluid, the first delivery pipe 22 connects the first container 21 and the input end of the microchannel 10, and the first plunger pump 23 is connected to the first delivery pipe 22. The first supply module 31 includes a second container 311, a second delivery pipe 312, and a second plunger pump 313. The second container 311 is used to store the first wall material fluid, and the second delivery pipe 312 connects the second container 311 and the microchannel 10. The second plunger pump 313 is connected to the input end of the microchannel 10 and the second delivery pipe 312. The second supply module 32 includes a third container 321, a third delivery pipe 322 and a third plunger pump 323. The third container 321 is used to store the second wall material fluid. The third delivery pipe 322 connects the third container 321 and the input end of the microchannel 10. The third plunger pump 323 is connected to the third delivery pipe 322. The core material supply unit 2, the first supply module 31 and the second supply module 32 of this structure are simple in structure and easy to install.

[0069] The microcapsule collection unit 4 includes a fourth container and a fourth delivery pipe. The fourth container is connected to the output sub-channel 105 through the fourth delivery pipe. The fourth container collects the perfluorohexanone microcapsules that are output through the output sub-channel 105 and the fourth delivery pipe. Then, the perfluorohexanone microcapsules collected in the fourth container are dried at low temperature to obtain the finished perfluorohexanone microcapsules. The fourth container can be a sealed collection bottle, a continuous separator, or a collection container with a cooling jacket.

[0070] Furthermore, a back pressure regulator 9 is connected to the fourth delivery pipe to ensure that the pressure of the output sub-channel 105 is continuously higher than the saturated vapor pressure of perfluorohexanone at the operating temperature, thereby suppressing vaporization and bubble generation and improving droplet stability and particle size consistency.

[0071] It should be noted that the first container 21 can be one of the following: a fluorine-resistant sealed storage bottle, a pressure-resistant storage tank with a stirring or circulation structure, or a syringe-type storage cylinder; the first delivery pipe 22 is a fluorine-resistant PFA / FEP pipe; and the microfluidic chip 1 can be made of fluorinated polymer, polyether ether ketone, glass, ceramic, or a combination structure of the above materials with a fluorine-resistant and anti-permeability coating on the surface. This application does not impose any restrictions on this.

[0072] Example 2

[0073] Perfluorohexanone microcapsules were prepared using the apparatus provided in Example 1. The specific experimental preparation method is as follows:

[0074] First, the microfluidic chip 1 and the microcapsule collection unit 4 are placed in a sealed inert atmosphere chamber 501. Nitrogen gas is continuously introduced into the chamber to maintain the inert environment, and the chamber outlet pipe is connected to the volatile condensation and collection unit 6 with a set temperature of -5℃ to recover volatiles.

[0075] To prepare the core material fluid, weigh 45 g of perfluorohexanone as the main material, add 1.0 g of hydrophobic fumed silica as a porous carrier, and dissolve 4.0 g of isophorone diisocyanate (IPDI) as the inner shell reaction monomer. After ultrasonic dispersion, place it in an ice bath for later use.

[0076] Prepare the first wall material fluid (inner shell precursor), measure 96 mL of deionized water as the dispersion medium, add 2.0 g of polyvinyl alcohol (PVA-1788) as a dispersant and additive, dissolve 2.0 g of diethylenetriamine (DETA) as a water-soluble crosslinking chain extender (which reacts with IPDI in the core material at the interface to form a polyurea reaction), and perform vacuum degassing treatment;

[0077] To prepare the second wall material fluid (shell precursor), measure 80 mL of deionized water, dissolve 20.0 g of polyethylene glycol diacrylate (PEG-DA, Mn=700) as a photocurable monomer, add 1.0 g of photoinitiator Irgacure 2959, and disperse 1.0 g of nano titanium dioxide as an inorganic filler to enhance the heat resistance of the shell.

[0078] Start the temperature control unit 8 and set the temperature of the droplet generation area of ​​the microfluidic chip 1 to 15°C to suppress volatilization. Set the temperature of the first reaction channel (inner shell formation) to 30°C, the temperature of the second input sub-channel (outer shell formation) to 30°C, and the temperature of the curing and aging channel to 35°C.

[0079] The back pressure regulator 9 of the adjustment system stabilizes the pressure inside the microfluidic chip at 0.25 MPa (approximately 0.2 MPa higher than the saturated vapor pressure of perfluorohexanone at its operating temperature).

[0080] Start the feed pump and inject the sample simultaneously at the following flow rates: core material fluid flow rate is 20 μL / min, first wall material fluid flow rate is 400 μL / min, and second wall material fluid flow rate is 300 μL / min.

[0081] The core material and the first wall material form perfluorohexanone droplets in the droplet generation area and undergo interfacial polymerization in the first input sub-channel 101 to form a polyurea inner shell. Subsequently, it merges with the second wall material in the second input sub-channel 102 to cover the outer layer. When it flows through the curing sub-channel 104, it is photocured by ultraviolet light source.

[0082] The product is discharged through the back pressure regulator 9 into the capsule collection unit. After solid-liquid separation and washing with deionized water, it is freeze-dried under vacuum (-50℃, 24 hours) to obtain perfluorohexanone microcapsules with a double-shell structure and an average particle size of about 20-40 μm.

[0083] Comparative Example 1 (prepared using a conventional mechanical stirring device)

[0084] 1. The experimental setup consisted of a 500 mL three-necked flask equipped with a mechanical stirrer, a reflux condenser (cooling water temperature 10℃), and a thermometer. The apparatus did not have a closed pressurization system, and the reaction was carried out at atmospheric pressure.

[0085] 2. Preparation steps

[0086] (1) Core material preparation: Same as in Example 1, weigh 45 g of perfluorohexanone, add 4.0 g of isophorone diisocyanate (IPDI) and 1.0 g of fumed silica, disperse evenly by ultrasonication, and place in an ice bath (5°C) for later use.

[0087] (2) Aqueous phase preparation: Take 200 mL of an aqueous solution containing 2.0 wt% polyvinyl alcohol (PVA-1788) as the continuous phase and add 2.0 g of diethylenetriamine (DETA).

[0088] (3) Emulsification (high shear process): Add the core material solution to the aqueous phase and stir for 5 minutes at 3000 rpm using a high shear dispersion emulsifier.

[0089] Phenomenon description: Due to shear heat generation and the low boiling point of perfluorohexanone (49℃), even with an ice bath, a distinct fluorinated liquid odor can still be smelled during the emulsification process, and bubbles escape from the liquid surface.

[0090] (4) Reaction and curing: The emulsion was transferred to a three-necked flask, and mechanical stirring was started (300 rpm). The mixture was heated in a water bath to 40°C (simulating the reaction temperature of Example 2) for 2 hours to carry out interfacial polymerization. Then the shell prepolymer (PEG-DA and photoinitiator) was added, and stirring was continued and the mixture was cured under UV light for 1 hour.

[0091] (5) Post-processing: filtration, washing, and vacuum freeze drying.

[0092] Test Project Example 2 Comparative Example 1 analyze Perfluorohexanone feed amount 45.0 g 45.0 g - Perfluorohexanone content in the final product 43.2 g 28.5 g Key data: Atmospheric pressure stirring leads to significant core material loss. Core material utilization 96% 63.3% Increase by more than 30% Weight loss rate during 30 days of storage at 70℃ <8% >25% Performance differences due to variations in shell density

[0093] Effect Analysis:

[0094] Comparing Example 2 with Comparative Example 1, it can be seen that the utilization rate of perfluorohexanone core material using the microfluidic device and method described in this invention is as high as 96.0%, while the utilization rate using the conventional mechanical stirring method is only 63.3%.

[0095] The reason for this significant difference is as follows:

[0096] Pressure control mechanism: Perfluorohexanone has a boiling point of only 49°C. Under the normal pressure and 40°C reaction conditions of Comparative Example 1, its saturated vapor pressure is relatively high, making it easy to penetrate the incompletely solidified shell and volatilize. However, this invention maintains the system pressure at 0.25 MPa (higher than the saturated vapor pressure) through a back pressure valve, which physically inhibits the vaporization of liquid perfluorohexanone.

[0097] Closed-loop system and condensation recovery: Although Comparative Example 1 used reflux condensation, it could not completely capture the highly volatile fluorinated gas in an open system; the present invention forms a double protection by enclosing condensation recovery in an inert gas chamber, which minimizes the loss during the processing.

[0098] For the integrity of the microstructure, please refer to Figure 3 Because the core material in Comparative Example 1 continuously volatilizes during the shell formation process, the resulting microcapsules have uneven particle size and collapsed shells, which seriously affects their sealing performance and leads to a high storage weight loss rate (25%).

[0099] In summary, the device of the present invention not only realizes the continuous preparation of microcapsules, but also solves the technical problems of low coating rate and low utilization rate of low-boiling-point volatile core materials (such as perfluorohexanone) through the pressure and inert atmosphere control system, which has significant economic and environmental benefits.

[0100] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An apparatus for preparing perfluorohexanone microcapsules, characterized in that, The device includes a microfluidic chip (1), a core material supply unit (2), a wall material supply unit (3), and a microcapsule collection unit (4). The microfluidic chip (1) has a microchannel (10). The core material supply unit (2) and the wall material supply unit (3) are connected to the input end of the microchannel (10). The microcapsule collection unit (4) is connected to the output end of the microchannel (10). The core material supply unit (2) is used to input a core material fluid into the microchannel (10). The core material fluid includes perfluorohexanone. The wall material supply unit (3) is used to input a wall material fluid into the microchannel (10). The microchannel (10) is used to encapsulate the core material fluid with the wall material fluid to form microcapsules. The microcapsule collection unit (4) is used to collect the microcapsules output from the output end of the microchannel (10).

2. The apparatus for preparing perfluorohexanone microcapsules according to claim 1, characterized in that, The wall material supply unit (3) includes a first supply module (31) and a second supply module (32). The first supply module (31) and the second supply module (32) are connected to the input end of the microchannel (10). The first supply module (31) is used to input a first wall material fluid into the microchannel (10) to form the inner shell of the microcapsule, and the second supply module (32) is used to input a second wall material fluid into the microchannel (10) to form the outer shell of the microcapsule.

3. The apparatus for preparing perfluorohexanone microcapsules according to claim 2, characterized in that, The microchannel (10) includes a first input subchannel (101), a second input subchannel (102), a third input subchannel (103), a curing subchannel (104), and an output subchannel (105). The input end of the first input subchannel (101) is connected to the core material supply unit (2). The output end of the first input subchannel (101) is inserted along the first direction (X) and connected to the second input subchannel (102). The input end of the second input subchannel (102) is connected to the first supply module (31). The output end of the second input subchannel (102) is inserted along the first direction (X) and connected to the third input subchannel (103). The input end of the third input subchannel (103) is connected to the second supply module (32). The output end of the third input subchannel (103) is connected to the curing subchannel (104). The curing subchannel (104) is connected to the output subchannel (105). The output subchannel (105) is connected to the microcapsule collection unit (4).

4. The apparatus for preparing perfluorohexanone microcapsules according to claim 3, characterized in that, The solidified subchannel (104) is serpentine.

5. The apparatus for preparing perfluorohexanone microcapsules according to claim 3, characterized in that, The microfluidic chip (1) has an observation window (11), which is set in relation to the output sub-channel (105).

6. The apparatus for preparing perfluorohexanone microcapsules according to claim 1, characterized in that, It also includes a housing (5) and a volatile matter condensation and collection unit (6). The housing (5) has an inert atmosphere chamber (501) and an inlet pipe (502) and an outlet pipe (503) connecting the inert atmosphere chamber (501). The inlet pipe (502) is used to input inert gas, and the outlet pipe (503) is connected to the volatile matter condensation and collection unit (6). The volatile matter condensation and collection unit (6) is used to condense the volatilized perfluorohexanone. The microfluidic chip (1) and the microcapsule collection unit (4) are disposed in the inert atmosphere cavity (501).

7. The apparatus for preparing perfluorohexanone microcapsules according to claim 6, characterized in that, It also includes a recovery pipe (7), which connects the volatile condensation and collection unit (6) and the core material supply unit (2); It also includes a temperature control unit (8), which is connected to the housing (5) and is used to control the temperature of the microfluidic chip (1).

8. The apparatus for preparing perfluorohexanone microcapsules according to claim 1, characterized in that, The core material supply unit (2) includes a first container (21), a first delivery pipe (22) and a first plunger pump (23). The first container (21) is used to store core material fluid. The first delivery pipe (22) connects the first container (21) and the input end of the microchannel (10). The first plunger pump (23) is connected to the first delivery pipe (22).

9. The apparatus for preparing perfluorohexanone microcapsules according to claim 2, characterized in that, The first supply module (31) includes a second container (311), a second delivery pipe (312), and a second plunger pump (313). The second container (311) is used to store the first wall material fluid. The second delivery pipe (312) connects the second container (311) and the input end of the microchannel (10). The second plunger pump (313) is connected to the second delivery pipe (312). The second supply module (32) includes a third container (321), a third delivery pipe (322), and a third plunger pump (323). The third container (321) is used to store the second wall material fluid. The third delivery pipe (322) connects the third container (321) and the input end of the microchannel (10). The third plunger pump (323) is connected to the third delivery pipe (322).

10. A method for preparing perfluorohexanone microcapsules, characterized in that, The apparatus for preparing perfluorohexanone microcapsules according to any one of claims 1-9 is used as the reactor, and the specific method is as follows: 1) Place the microfluidic chip and microcapsule collection unit in a sealed inert atmosphere chamber, continuously introduce nitrogen into the chamber to maintain the inert environment, and connect the chamber exhaust port to a condensation recovery unit with a set temperature of -5℃ to recover volatiles. 2) Prepare the core material fluid by using perfluorohexanone as the main material, adding hydrophobic fumed silica as a porous carrier, and dissolving isophorone diisocyanate as the inner shell reaction monomer. After uniform dispersion, place it in an ice bath for later use. The first wall material fluid was prepared by using deionized water as the dispersion medium, adding polyvinyl alcohol as a dispersant and additive, dissolving diethylenetriamine as a water-soluble crosslinking chain extender, and then performing vacuum degassing treatment. To prepare the second wall material fluid, polyethylene glycol diacrylate, photoinitiator Irgacure 2959, and nano titanium dioxide were added to deionized water. 3) Activate the temperature control unit, set the temperature of the droplet generation area of ​​the microfluidic chip to 15°C to suppress volatilization, set the inner shell formation temperature of the first reaction channel to 30°C, set the outer shell formation temperature of the second input sub-channel to 30°C, and set the curing and aging channel temperature to 35°C. 4) Adjust the system back pressure regulator to stabilize the pressure inside the microfluidic chip at 0.25 MPa; 5) Start the feed pump and inject the sample simultaneously at the following flow rates: core material fluid flow rate is 20 μL / min, first wall material fluid flow rate is 400 μL / min, and second wall material fluid flow rate is 300 μL / min; The core material and the first wall material form perfluorohexanone droplets in the droplet generation area and undergo interfacial polymerization in the first input sub-channel to form a polyurea inner shell. Subsequently, it merges with the second wall material in the second input sub-channel to cover the outer layer. When flowing through the curing sub-channel, it is photocured by ultraviolet light source. The product is discharged through a back pressure regulator into a capsule collection unit. After solid-liquid separation and washing with deionized water, it is freeze-dried under vacuum to obtain perfluorohexanone microcapsules with a double-shell structure.

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