A method for preparing fire extinguishing microcapsules

Abstract

The invention relates to the technical field of manufacturing fire extinguishing microcapsules or microspheres, and specifically to a method for preparing fire extinguishing microcapsules, comprising the following steps: S1: injecting a liquid fire extinguishing capsule core and a liquid capsule material into a coaxial flow focusing component respectively; S2: the liquid capsule material fluid is sheared by the liquid fire extinguishing capsule core fluid in a convergence area and forms a jet structure; S3: the jet structure enters a necking section and breaks into microdroplets or microspheres; S4: the length of the necking section is optimized and adjusted to accurately control the size of the microdroplets and improve the uniformity of the microdroplets to meet the requirements of microdroplet forming of different fire extinguishing capsule cores and capsule materials; S5: the microdroplets enter a curing channel, and an ultraviolet light component performs photocuring on the capsule material; in S2, it also includes: a two-phase angle controller is designed in the coaxial flow focusing component, and the outer phase liquid capsule material and the inner phase liquid fire extinguishing capsule core converge at the two-phase angle to form a jet. The invention can improve the stability and uniformity of the jet and the microdroplets, and improve the manufacturing quality of the fire extinguishing microcapsules.

Description

Technical Field

[0001] The invention relates to the technical field of fire extinguishing microcapsules or microspheres manufacturing, in particular to a method for preparing fire extinguishing microcapsules. Background Art

[0002] Fire extinguishing microcapsules are an innovative firefighting technology that uses microcapsules to encapsulate fire extinguishing agents in polymer shells. These microcapsules will automatically burst when heated in the early stages of a fire, releasing the fire extinguishing agent to quickly extinguish the flames. Its advantages are automatic response, efficient fire extinguishing, and environmental safety.

[0003] In the prior art, fire-extinguishing microcapsules generally use micro-controlled flow technology, namely coaxial flow focusing, so that the outer phase liquid wraps the inner phase liquid and focuses into a jet structure. The jet breaks into droplets or capsules in an unstable environment, and then the outer phase liquid is hardened or solidified to make it a capsule shell that wraps the inner phase liquid. However, in the process of coaxial flow focusing, the length or size of the necking section is limited, which will limit the flexibility of droplet generation and lead to instability in droplet size and production frequency. Summary of the invention

[0004] The invention provides a method for preparing fire extinguishing microcapsules, which can improve the stability and uniformity of jets and microdroplets and enhance the manufacturing quality of the fire extinguishing microcapsules.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing fire-extinguishing microcapsules, comprising:

[0007] S1: injecting the liquid fire extinguishing capsule core and the liquid capsule material into the coaxial flow focusing assembly respectively;

[0008] S2: The liquid capsule fluid will be sheared by the liquid fire extinguishing capsule core fluid in the convergence area and form a jet structure;

[0009] S3: The jet structure enters the necking section and breaks into micro-droplets or micro-spheres;

[0010] S4: The length of the necking section is optimized and adjusted to accurately control the size of the micro-droplets and improve the uniformity of the micro-droplets to meet the micro-droplet forming requirements of different fire extinguishing capsule cores and capsule materials;

[0011] S5: The microdroplets enter the curing channel, and the UV light component performs photocuring on the capsule material.

[0012] Optionally, S2 also includes:

[0013] A two-phase angle controller is designed in the coaxial flow focusing component. The outer phase liquid capsule material and the inner phase liquid fire extinguishing capsule core converge through the two-phase angle to form a jet. The two-phase angle controller can adjust the range of the two-phase angle to form a stable flow pattern.

[0014] Optionally, the coaxial flow focusing assembly includes an external phase tube and a capillary located on its axis, the top opening of the capillary tube is associated with the internal phase pump source of the output liquid fire extinguishing bag core, the top opening of the external phase tube is associated with the external phase pump source of the output liquid bag material, the convergence area is located below the external phase tube, a bearing seat is installed at the bottom of the external phase tube, the two-phase angle controller is assembled inside the bearing seat, an assembly tube is integrally formed at the bottom of the bearing seat, a flexible sealing part is fixedly installed at the bottom of the assembly tube, the necking section includes a necking bucket slidably assembled on the outer wall of the bearing seat, the conical inner wall of the necking bucket is tightly fitted with the bottom end of the flexible sealing part, the flexible sealing part will be deformed when squeezed by external force, and the upward displacement of the necking bucket will shorten its axial length below the flexible sealing part.

[0015] Optionally, the two-phase angle controller includes a basic cone sleeve fixedly mounted on the bottom end of the outer phase tube, the conical inner wall of the basic cone sleeve being equipped with a conical ring-shaped flexible functional part, the interior of the flexible functional part is filled with a polymer, and the polymer will expand or contract under the control of an external driver, and the flexible functional part can expand and extend equidistantly toward the annular outer wall of the capillary to drive the taper of the inner cone surface of the flexible functional part to increase.

[0016] Optionally, the capillary is fixedly installed inside the external phase tube, and a spiral component is fixedly installed between the outer wall of the capillary and the inner wall of the external phase tube, and multiple spiral guide grooves are formed between the spiral component and the inner wall of the external phase tube. After the external phase liquid capsule enters the external phase tube, it will spiral forward under the guidance of the spiral component.

[0017] Optionally, a collecting portion is fixedly installed at the bottom of the necking bucket, and a raised portion is integrally formed on the inner wall of the collecting portion, and a accommodating cavity is formed between the raised portion and the annular inner wall of the collecting portion, and a correct channel communicating with the interior of the necking bucket is opened through the raised portion, and the correct channel is colinear with the axis of the capillary.

[0018] Optionally, a microhole penetrating the outer wall of the collection portion is opened inside the accommodating cavity, and the microhole is associated with an external photoelectric sensor. The light signal emitted by the photoelectric sensor will pass through the microhole into the accommodating cavity, and the liquid capsule material will absorb the light signal.

[0019] Optionally, the necking bucket includes a necking portion and a transition portion, the transition portion is designed to be a straight cylinder, and the bottom of the transition portion is connected to the correct channel.

[0020] Optionally, a liquid outlet pipe connected to the correct channel is fixedly installed at the bottom of the raised portion, the liquid outlet pipe is designed to be light-transmissive, a spherical lamp mold is fixedly installed inside the liquid outlet pipe, the spherical inner wall of the spherical lamp mold is paved with a light-curing lamp source, the curing channel is opened from the top to the bottom of the spherical lamp mold, and the curing channel is colinear with the capillary axis.

[0021] Optionally, the liquid capsule material is a light-curing resin composite material, and the liquid fire-extinguishing capsule core is a perfluoroacetone mixture to which a surfactant is added.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. By adjusting the length of the necking section, the size of the micro-droplets can be controlled. Generally, a longer necking section usually generates smaller micro-droplets, while a shorter necking section generates larger micro-droplets. By adjusting and optimizing the length of the necking section, the size uniformity of the micro-droplets can be improved, the fluctuation of the size distribution can be reduced, and more stable flow conditions can be provided for the jet to ensure the flow morphology.

[0024] 2. The annular outer wall of the flexible functional part facing the capillary is the deformable part. The polymer is deformed under the control of an external driver. Due to the limitation of the deformable part, the annular outer wall of the flexible functional part facing the capillary can expand and extend equidistantly, thereby adjusting the two-phase angle, improving the adaptability of the coaxial flow focusing component, making the jet generation more stable, and the appropriate two-phase angle can avoid excessive shear or insufficient shear.

[0025] 3. By designing spiral parts, in the process of coaxial flow focusing, the spiral advancement of the external phase liquid has certain benefits for the coating. The spiral advancement can enhance the mixing effect of the fluid, thereby improving the uniformity and stability of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the coaxial flow focusing assembly in the present invention;

[0027] Figure 2 For the present invention Figure 1 Internal section view of

[0028] Figure 3 For the present invention Figure 2 The enlarged structural diagram at B in the middle;

[0029] Figure 4 For the present invention Figure 2 The enlarged structural diagram at C in the middle;

[0030] Figure 5 It is a schematic diagram of the state of the change of the two-phase angle in the present invention;

[0031] Figure 6 It is a schematic diagram of the internal three-dimensional structure of the coaxial flow focusing assembly in the present invention;

[0032] Figure 7 The figure is a process flow chart for preparing the fire extinguishing microcapsules in the present invention.

[0033] In the figure: 1. capillary; 2. external phase tube; 3. spiral member; 4. bearing seat; 5. basic cone sleeve; 6. flexible functional part; 7. assembly tube; 8. flexible sealing part; 9. necking bucket; 11. collecting part; 12. liquid outlet pipe; 13. spherical lamp mold; 15. accommodating cavity; 16. correct channel; 17. photoelectric sensor. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] See also Figures 1 to 7 The present invention provides a technical solution: a method for preparing fire extinguishing microcapsules, comprising:

[0036] S1: injecting the liquid fire extinguishing capsule core and the liquid capsule material into the coaxial flow focusing assembly respectively;

[0037] S2: The liquid capsule fluid will be sheared by the liquid fire extinguishing capsule core fluid in the convergence area and form a jet structure;

[0038] S3: The jet structure enters the necking section and breaks into micro-droplets or micro-spheres;

[0039] S4: The length of the necking section is optimized and adjusted to accurately control the size of the micro-droplets and improve the uniformity of the liquid to meet the micro-droplet forming requirements of different fire extinguishing capsule cores and capsule materials;

[0040] S5: The microdroplets enter the curing channel, and the UV light component performs photocuring on the capsule material.

[0041] In the existing microfluidic technology, the length of the neck section usually refers to the length of the section where the inner and outer phase liquids gradually narrow from a wide section to a narrow section after they merge. This length is the area where the inner and outer phase liquids work together, affecting the generation and stability of droplets, and also affecting the droplet generation and flow characteristics. In the present invention, when the specifications, concentrations or masses of the same liquid capsule core are different, or when different types of liquid capsule cores are used to manufacture fire extinguishing microcapsules, it is necessary to optimize and adjust the length of the neck section so as to improve the generation quality of microdroplets or microspheres. Secondly, adjusting the length of the neck section can optimize the generation cycle of microdroplets, reduce blockage and improve stability. Thirdly, the adjustable length of the neck section can adapt to different experimental conditions or production conditions.

[0042] Among them, the stability and uniformity of the microdroplets are improved, which is beneficial to the subsequent photocuring process.

[0043] A more preferred embodiment, in S2, further includes:

[0044] A two-phase angle controller is designed in the coaxial flow focusing component. The outer phase liquid capsule material and the inner phase liquid fire extinguishing capsule core converge through the two-phase angle to form a jet. The two-phase angle controller can adjust the range of the two-phase angle to form a stable flow pattern. In the prior art, the two-phase angle refers to the angle formed when the inner and outer phase liquids converge in the microchannel. In this embodiment, in the process of coaxial flow focusing of the inner and outer phase liquids to form a jet, the two-phase angle has a greater influence on the generation of microdroplets. A suitable two-phase angle can improve the stability of droplet production and reduce the fluctuation of droplet size. Among them, a smaller angle usually leads to faster droplet generation, while a larger angle may generate more uniform droplets. Therefore, it is necessary to make adaptive adjustments according to the use environment or raw materials.

[0045] Among them, a more preferred embodiment is that the coaxial flow focusing component includes an external phase tube 2 and a capillary tube 1 located on its axis, the top opening of the capillary tube 1 is associated with the internal phase pump source of the output liquid fire extinguishing bag core, the top opening of the external phase tube 2 is associated with the external phase pump source of the output liquid bag material, the convergence area is located below the external phase tube 2, a bearing seat 4 is installed at the bottom of the external phase tube 2, a two-phase angle controller is assembled inside the bearing seat 4, an assembly tube 7 is integrally formed at the bottom of the bearing seat 4, a flexible sealing part 8 is fixedly installed at the bottom of the assembly tube 7, the necking section includes a necking bucket 9 slidably assembled on the outer wall of the bearing seat 4, the conical inner wall of the necking bucket 9 is tightly fitted with the bottom end of the flexible sealing part 8, the flexible sealing part 8 will be deformed when squeezed by external force, and the upward displacement of the necking bucket 9 will shorten its axial length below the flexible sealing part 8, please refer to Figures 2 to 3In this embodiment, the capillary 1 and the external phase tube 2 form a coaxial flow, wherein the flexible sealing portion 8 and the necking bucket 9 constitute an adjustable necking section, and the jet will break into micro-droplets or micro-spheres only after leaving the necking section. Before that, the external phase fluid will wrap the internal phase fluid and enter the necking section. After the jet leaves the necking section, it will continue to extend under the action of the external phase fluid, and then break under the condition of Rayleigh-Pratt instability. By adjusting the length of the necking section, the size of the micro-droplets can be controlled. Generally, a longer necking section usually generates smaller micro-droplets, while a shorter necking section generates larger micro-droplets. By adjusting and optimizing the length of the necking section, the size uniformity of the micro-droplets can be improved, the fluctuation of the size distribution can be reduced, and more stable flow conditions can be provided for the jet to ensure the flow morphology.

[0046] In a preferred embodiment, the two-phase angle controller includes a basic cone sleeve 5 fixedly mounted at the bottom end of the outer phase tube 2, and a conical ring-shaped flexible functional part 6 is mounted on the conical inner wall of the basic cone sleeve 5. The interior of the flexible functional part 6 is filled with a polymer, and the polymer expands or contracts under the control of an external driver. The flexible functional part 6 can expand and extend equidistantly toward the annular outer wall of the capillary 1 to increase the taper of the inner cone of the flexible functional part 6. Please refer to Figure 2 and Figure 5 In this embodiment, the annular outer wall of the flexible functional part 6 facing the capillary 1 is the deformation part. The polymer is deformed under the control of an external driver. Due to the limitation of the deformation part, the annular outer wall of the flexible functional part 6 facing the capillary 1 can expand and extend equidistantly, thereby adjusting the two-phase angle, improving the adaptability of the coaxial flow focusing component, and making the jet generation more stable. In this process, the outer phase liquid capsule material will flow shear the inner phase liquid fire extinguishing capsule core. Therefore, a suitable two-phase angle can avoid excessive shearing or insufficient shearing.

[0047] Furthermore, the capillary 1 is fixedly installed inside the external phase tube 2, and a spiral member 3 is fixedly installed between the outer wall of the capillary 1 and the inner wall of the external phase tube 2. A plurality of spiral guide grooves are formed between the spiral member 3 and the inner wall of the external phase tube 2. After the external phase liquid capsule enters the external phase tube 2, it will spiral forward under the guidance of the spiral member 3. Please refer to Figure 1 and Figure 2In this embodiment, a guide groove is used to make the pumped external phase liquid capsule material spiral in the process of advancing. In the process of coaxial flow focusing, the spiral advancement of the external phase liquid has certain benefits for the coating. The spiral advancement can enhance the mixing effect of the fluid, thereby improving the uniformity and stability of the coating. In detail, the spiral advancement can increase the contact area and contact time between the fluids, so that the internal and external phase liquids can be more fully mixed, which is very important for forming a uniform coating layer. Secondly, the spiral advancement can help stabilize the cone-jet structure in the flow focusing process and reduce instability, thereby forming a more stable coating. Therefore, the external phase liquid capsule material with spiral advancement can meet the packaging requirements of high precision and high uniformity.

[0048] On the basis of the embodiment of the coaxial flow focusing assembly, a collecting portion 11 is fixedly installed at the bottom of the necking bucket 9, and a ridge is integrally formed on the inner wall of the collecting portion 11. A receiving cavity 15 is formed between the ridge and the annular inner wall of the collecting portion 11. A correct channel 16 communicating with the interior of the necking bucket 9 is opened through the ridge, and the correct channel 16 is colinear with the axis of the capillary 1. Please refer to Figure 4 In coaxial flow focusing, if the flow rate or pressure of the inner or outer phase liquid is unstable, it may cause jet turbulence, thereby affecting the generation and quality of droplets. In the present embodiment, when the jet is turbulently sputtered, the jet will collide with the inner wall of the necking bucket 9. The change in the jet path will avoid the failure error of the micro-droplets and fail to maintain a stable wrapping state. At this time, these useless micro-droplets will enter the accommodating cavity 15 along the inner wall of the necking bucket 9 for collection, avoiding most of the micro-droplets from being solidified and mixed into the finished fire-extinguishing microcapsules. It can be extended to determine whether there is a large amount of or continuous jet turbulence by observing the collected data until the correct position is adjusted.

[0049] Furthermore, a micro-hole is provided inside the accommodating cavity 15 and passes through the outer wall of the collecting part 11. The micro-hole is associated with the external photoelectric sensor 17. The light signal emitted by the photoelectric sensor 17 will pass through the micro-hole and enter the accommodating cavity 15. The liquid capsule material will absorb the light signal. Figure 4 In this embodiment, through the cooperation of the photoelectric sensor 17, the micropores and the liquid capsule material, the photoelectric sensor 17 can detect whether useless micro-droplets appear inside the accommodating cavity 15, which can be used as an early warning judgment in turn to monitor the steady state of the jet in real time.

[0050] Furthermore, the necking bucket 9 includes a necking portion and a transition portion, the transition portion is designed to be a straight cylinder, and the bottom of the transition portion is connected to the correct channel 16.

[0051] Furthermore, a liquid outlet pipe 12 connected to the correct channel 16 is fixedly installed at the bottom of the raised portion. The liquid outlet pipe 12 is designed to be light-transmissive. A spherical lamp mold 13 is fixedly installed inside the liquid outlet pipe 12. A light curing light source is laid on the spherical inner wall of the spherical lamp mold 13. The curing channel is opened from the top to the bottom of the spherical lamp mold 13. The curing channel is colinear with the axis of the capillary 1. Please refer to Figure 2 and Figure 6 In the prior art, the light sources are generally designed on both sides, and the light intensity received by the upper and lower parts of the falling micro-droplets will be less than the light intensity of the surrounding areas. In the present embodiment, by designing the coordination of the spherical lamp mold 13 and the light-curing light source, when the micro-droplets enter the curing channel, the spherical lamp mold 13 can perform more uniform and comprehensive light curing on the micro-droplets, thereby improving the curing quality of the capsule material.

[0052] Furthermore, the liquid capsule material is a light-curing resin composite material, and the use of a surfactant can reduce the interfacial tension of the inner phase liquid, so that the outer phase liquid capsule material can stably wrap the inner phase liquid fire extinguishing capsule core.

[0053] The necking bucket 9 is slidably mounted on the outer wall of the bearing seat 4, and the present invention does not show the structure related to the sliding relationship.

[0054] The size of the necking section is adjusted according to demand, and the present invention only shows a specific adjustment scheme for the length of the necking section.

[0055] By utilizing the above structures, the stability and uniformity of the jet and micro-droplets can be improved, and the manufacturing quality of the fire-extinguishing microcapsules can be improved.

[0056] The standard parts used in this embodiment can be purchased directly from the market, and the non-standard structural components recorded in the specification and the drawings can also be directly processed according to the existing technical common sense without any doubt. At the same time, the connection method of each component adopts the mature conventional means in the prior art, and the machinery, parts and equipment all adopt the conventional models in the prior art, so no specific description will be given here.

[0057] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing fire extinguishing microcapsules, characterized in that: include: S1: injecting the liquid fire extinguishing capsule core and the liquid capsule material into the coaxial flow focusing assembly respectively; S2: The liquid capsule fluid will be sheared by the liquid fire extinguishing capsule core fluid in the convergence area and form a jet structure; S3: The jet structure enters the necking section and breaks into micro-droplets or micro-spheres; S4: The length of the necking section is optimized and adjusted to accurately control the size of the micro-droplets and improve the uniformity of the micro-droplets to meet the micro-droplet forming requirements of different fire extinguishing capsule cores and capsule materials; S5: The microdroplets enter the curing channel, and the UV light component performs light curing on the capsule material; In S2, it also includes: A two-phase angle controller is designed in the coaxial flow focusing assembly. The outer phase liquid capsule material and the inner phase liquid fire extinguishing capsule core converge through the two-phase angle to form a jet. The two-phase angle controller can adjust the range of the two-phase angle to form a stable flow pattern. The coaxial flow focusing assembly comprises an external phase tube (2) and a capillary tube (1) located on its axis, the top opening of the capillary tube (1) is associated with an internal phase pump source of a liquid fire extinguishing capsule core, the top opening of the external phase tube (2) is associated with an external phase pump source of a liquid capsule material, the convergence area is located below the external phase tube (2), a bearing seat (4) is installed at the bottom of the external phase tube (2), the two-phase angle controller is installed inside the bearing seat (4), an assembly tube (7) is integrally formed at the bottom of the bearing seat (4), a flexible sealing portion (8) is fixedly installed at the bottom of the assembly tube (7), the necking section comprises a necking bucket (9) slidably mounted on the outer wall of the bearing seat (4), the conical inner wall of the necking bucket (9) is tightly fitted with the bottom end of the flexible sealing portion (8), the flexible sealing portion (8) is deformed when squeezed by an external force, and the upward displacement of the necking bucket (9) shortens its axial length below the flexible sealing portion (8); The two-phase angle controller comprises a basic cone sleeve (5) fixedly mounted on the bottom end of the outer phase tube (2); a conical ring-shaped flexible functional part (6) is mounted on the conical inner wall of the basic cone sleeve (5); the interior of the flexible functional part (6) is filled with a polymer, and the polymer expands or contracts under the control of an external driver; the flexible functional part (6) can expand and extend equidistantly toward the annular outer wall of the capillary tube (1) to drive the taper of the inner cone surface of the flexible functional part (6) to increase.

2. The method for preparing the fire extinguishing microcapsules according to claim 1, characterized in that: The capillary tube (1) is fixedly mounted inside the external phase tube (2); a spiral member (3) is fixedly mounted between the outer wall of the capillary tube (1) and the inner wall of the external phase tube (2); a plurality of spiral guide grooves are formed between the spiral member (3) and the inner wall of the external phase tube (2); after the external phase liquid capsule material enters the external phase tube (2), it will spirally advance under the guidance of the spiral member (3).

3. The method for preparing the fire extinguishing microcapsules according to claim 1, characterized in that: A collecting portion (11) is fixedly mounted on the bottom of the necking bucket (9); a raised portion is integrally formed on the inner wall of the collecting portion (11); a receiving cavity (15) is formed between the raised portion and the annular inner wall of the collecting portion (11); a correct passage (16) is formed through the raised portion and communicates with the interior of the necking bucket (9); the correct passage (16) is colinear with the axis of the capillary (1).

4. The method for preparing the fire extinguishing microcapsules according to claim 3, characterized in that: A microhole penetrating the outer wall of the collection portion (11) is provided inside the accommodating cavity (15), and the microhole is associated with an external photoelectric sensor (17). A light signal emitted by the photoelectric sensor (17) passes through the microhole and enters the accommodating cavity (15), and the liquid capsule material absorbs the light signal.

5. The method for preparing the fire extinguishing microcapsules according to claim 4, characterized in that: The necking bucket (9) comprises a necking portion and a transition portion, the transition portion is designed to be a straight cylinder, and the bottom of the transition portion is connected to the correct channel (16).

6. The method for preparing the fire extinguishing microcapsules according to claim 4, characterized in that: A liquid outlet pipe (12) connected to the correct channel (16) is fixedly installed at the bottom of the raised portion, the liquid outlet pipe (12) is designed to be light-transmissive, a spherical lamp mold (13) is fixedly installed inside the liquid outlet pipe (12), a light-curing lamp source is laid on the spherical inner wall of the spherical lamp mold (13), the curing channel is opened from the top to the bottom of the spherical lamp mold (13), and the curing channel is colinear with the axis of the capillary (1).

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