Induction electrode assisted multi-needle liquid jet spinning device, method and application

Abstract

The application discloses an inductive electrode auxiliary multi-needle liquid spray spinning device, method and application, relates to the technical field of multi-needle liquid spray spinning, and the device comprises an air compressor, a liquid spray die head, a syringe and a dispensing needle; the air compressor is connected with the liquid spray die head through an air pipe; the dispensing needle is provided with at least two, the syringe is connected with the dispensing needle in correspondence through a Teflon pipe; the device further comprises a metal hollow cylindrical barrel, a high-voltage static generator and a metal receiving electrode plate; the metal hollow cylindrical barrel is connected with the high-voltage static generator through a wire, the metal receiving electrode plate is connected with the ground through a wire, and the dispensing needle is connected with the ground through a wire. In the application, each polymer jet flow carries the same charge, so that the polymer jet flows do not produce the mutual entanglement phenomenon between traditional multi-jet liquid spray nanofibers due to the reason that the same kind repels each other. The spacing between the dispensing needles in the application can reach 1.5-2 mm, and the extremely small needle spacing can effectively improve the needle planting density and thus improve the yield of nanofibers.

Description

Technical Field

[0001] This invention belongs to the field of multi-needle liquid jet spinning technology, and particularly relates to the device, method and application of induction electrode-assisted multi-needle liquid jet spinning. Background Technology

[0002] Nanofibers are fibers with a diameter of less than 1000 nanometers. Due to their excellent properties such as ultra-high aspect ratio and ultra-large specific surface area, they are widely used in many fields such as drug controlled release, tissue engineering, wound repair, filtration, personal protection, sensors, catalysts, and energy storage materials. The mass production technology of nanofibers has thus become one of the hot topics in scientific research.

[0003] Currently, common technologies for mass production of nanofibers include electrospinning, liquid-jet spinning, and centrifugal spinning. Electrospinning nanofiber mass production technology is divided into two types: multi-needle preparation technology and needleless preparation technology. ① For multi-needle preparation technology, patent (CN101586288B) discloses an array multi-nozzle electrospinning device, which is a method of preparing nanofibers by arranging multiple needles in an array according to certain rules and then performing multi-jet electrospinning. Although this method can effectively increase nanofiber yield, electric field interference will occur between the needles. This interference not only affects the quality of nanofibers but also dictates that the spacing between the needles cannot be too small, thus limiting the increase in nanofiber yield. ② For needleless preparation technology, various methods are used to generate multiple Taylor cones on the surface of the polymer solution, with each Taylor cone forming a jet, thereby achieving multi-jet electrospinning. This method has disadvantages such as unstable solution concentration, easy accumulation of polymer on the electrodes, and uneven electrode electric field.

[0004] Regarding the mass production technology of centrifugal spinning nanofibers, a centrifugal spinning device is disclosed in patent (CN110295403B). Although this device can increase the yield of nanofibers, the nanofibers formed by centrifugal force have the disadvantages of being relatively thick and having a wide diameter distribution.

[0005] Regarding the mass production technology of liquid jet spinning nanofibers, patent (CN103882535B) discloses a solution jet spinning die that utilizes airflow to stretch a polymer solution for multi-jet spinning. Liquid jet spinning technology itself has the advantage of high yield, so multi-jet liquid jet spinning makes it easier to achieve high-yield, large-scale preparation of nanofibers. However, nanofibers prepared by multi-jet liquid jet spinning have large diameters, uneven diameters, and are prone to entanglement, adhesion, and filament agglomeration. These defects significantly affect the quality of the nanofibers. In addition, multi-jet liquid jet spinning suffers from the problem that the needle spacing cannot be too small due to the fusion of adjacent jets. This problem restricts the needle density of the dispensing needles and the improvement of nanofiber yield.

[0006] Nanosphere / fiber membranes, composed of 0-dimensional nanospheres and 1-dimensional nanofibers, are also a current research focus. These membrane materials have been extensively studied and widely applied in fields such as nanogenerators, water purification, anti-biofouling, electronic skin, and membrane distillation. Existing methods for preparing nanosphere / fiber membranes can be categorized into two-step and one-step methods based on the number of steps.

[0007] For the two-step preparation method, micro / nanospheres and fiber membranes are prepared sequentially. Although nanospheres / fiber membranes can be obtained, the preparation process is complicated, which not only wastes time, but also makes it easier for operational deviations to occur due to the long preparation process, resulting in fluctuations in product quality.

[0008] Regarding the one-step preparation method: Chinese invention patent (CN106237717B) uses a combination of electrospinning and electrospraying to achieve one-step preparation of nanospheres / fiber membranes. Although this method effectively reduces the number of preparation steps, it suffers from drawbacks due to the use of needle-free electrospinning technology, such as larger nanofiber diameters, poor fiber diameter uniformity, unstable solution concentration, easy accumulation of polymers on the electrodes, and uneven electrode electric field.

[0009] A one-step preparation of nanospheres / fiber membranes can also be achieved using multi-needle liquid-jet spinning technology. Liquid-jet spinning offers advantages such as high yield and stable solution concentration. However, this method also suffers from drawbacks, including large nanofiber diameter, poor diameter uniformity, and the tendency for adjacent jets to merge, which limits the needle spacing. Patent (CN109023554B) proposes a novel liquid-jet spinning device and method. This patent introduces cylindrical electrodes into the traditional liquid-jet device, and the addition of an electric field makes the jet finer. The method in this patent improves the shortcomings of large and uneven nanofiber diameters in traditional liquid-jet spinning to some extent while maintaining high yield. However, the method in this patent still needs further improvement in reducing nanofiber diameter and diameter uniformity, and it does not consider application in multi-needle liquid-jet spinning technology.

[0010] In summary, existing mass production technologies for nanofibers all have certain shortcomings. Therefore, it is essential to develop a novel mass production technology for nanofibers that can also be applied to the one-step preparation of nanospheres / fiber membranes, thereby improving the quality and yield of nanospheres / fiber membranes. Summary of the Invention

[0011] The purpose of this invention is to provide an induction electrode-assisted multi-needle liquid-jet spinning device, method, and application to solve the following problems in the prior art: the needle spacing in multi-needle electrospinning preparation technology is too large; the needleless electrospinning preparation technology has problems such as unstable solution concentration, easy accumulation of polymer on electrodes, and uneven electrode electric field; the nanofibers prepared by centrifugal spinning nanofiber mass production technology have the disadvantages of large diameter and wide diameter distribution; and the liquid-jet spinning nanofiber mass production technology has problems such as large nanofiber diameter, uneven diameter, large needle spacing, and easy entanglement, adhesion, and filamentation between nanofibers.

[0012] To achieve the above objectives, the present invention employs the following technical solution:

[0013] The induction electrode-assisted multi-needle liquid jet spinning device includes an air compressor, a liquid jet die head, a syringe, and a dispensing needle; the air compressor is connected to the liquid jet die head via an air pipe;

[0014] The dispensing needles are provided in at least two parts, and the distance between the dispensing needles can be 1.5-2 mm; the syringe is filled with polymer solution and is mounted on the injection pump; the syringe is connected to the dispensing needles through Teflon tubing; the dispensing needles are all mounted on the liquid spraying head.

[0015] It also includes a hollow metal cylinder, a high-voltage electrostatic generator, and a metal receiving electrode plate;

[0016] The hollow metal cylinder is located on the side of the dispensing needle away from the liquid spray nozzle. The hollow metal cylinder is connected to a high-voltage electrostatic generator via a wire. The metal receiving electrode is connected to the ground via a wire. All dispensing needles are connected to the ground via wires.

[0017] Preferably, the tip of the dispensing needle is directly opposite the airflow outlet of the liquid spraying die, and the distance between the tip of the dispensing needle and the airflow outlet of the liquid spraying die is equidistant.

[0018] Preferably, the dispensing needles are arranged horizontally.

[0019] Preferably, the syringe is equipped with at least one polymer solution loaded with at least one polymer solution. Different solutions can be loaded into the syringe for spinning multicomponent nonwoven fabrics.

[0020] Preferably, the Teflon tubing is one or both of multi-channel and single-channel Teflon tubing. The multi-channel Teflon tubing has a one-in-two-out or one-in-multiple-out product structure. One syringe can be connected to multiple dispensing needles through a multi-channel Teflon tubing, or two syringes can be connected to a coaxial needle through a single Teflon tubing to prepare a core-sheath structure fiber. Similarly, multiple syringes can be connected one-to-one with dispensing needles through single-channel Teflon tubing.

[0021] Preferably, the injection pump is a multi-channel injection pump, and at least one multi-channel injection pump is provided. The multi-channel injection pump maintains the same control speed or different control speeds. The injection control speeds of the injection pumps can be different to prepare nonwoven fabrics with coexisting fibers of different thicknesses.

[0022] The induction electrode-assisted multi-needle liquid-jet spinning method using the above-mentioned device includes the following steps:

[0023] S1. Weigh polymer particles or powder into a solvent, stir, and let stand to prepare a polymer solution;

[0024] S2. Extract the polymer solution for loading;

[0025] S3. Set parameters and start the device;

[0026] S4. High-pressure airflow pulls the polymer solution to form a polymer spinning jet, and a polymer spinning jet is formed at the tip of each dispensing needle; the polymer spinning jet flies over the internal cavity of the metal hollow cylinder under the pulling action of the high-pressure airflow.

[0027] S5. A high-voltage electrostatic field is formed near the hollow metal cylinder, and the dispensing needle and the metal receiving plate are grounded to form a zero potential; the polymer spinning jet carries the same charge with opposite polarity to that output by the high-voltage electrostatic generator inside the jet, the polymer jet breaks to form nanofibers, and the polymer spinning jets formed by each dispensing needle repel each other.

[0028] S6. Nanofibers pass through a hollow metal cylinder and are deposited on a metal receiving electrode.

[0029] The method for preparing nanosphere / fiber membranes using the above-described apparatus includes the following steps:

[0030] S1. Weigh polymer particles or powder into a solvent, stir, and let stand to prepare polymer solution A;

[0031] S2. Weigh the polymer particles or powder into the solvent, stir, and let stand to prepare polymer solution B;

[0032] S3. Extract polymer solution A and polymer solution B separately for loading;

[0033] S4. Set parameters and start the device;

[0034] S5. High-pressure airflow pulls polymer solution A and polymer solution B to form a polymer jet. The two polymer jets fly over the internal cavity of the metal hollow cylinder under the pulling action of the high-pressure airflow.

[0035] S6. A high-voltage electrostatic field is formed near the hollow metal cylinder, and the dispensing needle and the metal receiving plate are grounded to form a zero potential. Under the action of electrostatic induction, the two polymer jets carry the same charge with opposite polarity to the output of the high-voltage electrostatic generator inside their respective jets. The polymer jets break down to form nanospheres or nanofibers.

[0036] S7. Two polymer jets pass through a hollow metal cylinder and are received on a metal receiving electrode plate to form a nanosphere / fiber membrane.

[0037] Preferably, the specific steps of S4 are as follows:

[0038] S401. Connect two syringes loaded with polymer solution A and polymer solution B to a dispensing needle through Teflon tubing, that is, connect the two ends of the two Teflon tubing to a syringe and a dispensing needle respectively.

[0039] S402. Fix two dispensing needles to the liquid spraying mold head, and make the needle tips of the two dispensing needles equidistant from the center point of the airflow outlet of the mold head, and the needle tips of the dispensing needles are within the effective range of the high-pressure airflow.

[0040] S403. Connect the two dispensing needles to the metal receiving plate in sequence to ground.

[0041] S404. Select a metal hollow cylinder of appropriate shape (length, diameter, etc.);

[0042] S405. Turn on the air compressor and adjust its output air pressure to an appropriate value;

[0043] S406. If two syringes are mounted on two injection pumps, turn on both injection pumps and set the injection speed of each injection pump separately; if two syringes are mounted on the same multi-channel injection pump, turn on the injection pump and set the injection speed of that single injection pump.

[0044] S407. Turn on the high-voltage electrostatic generator and set the output voltage;

[0045] S408. Set other process parameters (such as the distance between the dispensing needle and the hollow metal cylinder, the distance between the dispensing needle and the metal receiving electrode plate, etc.).

[0046] Preferably, in step S5, the high-pressure airflow pulls polymer solution A and polymer solution B to form a polymer jet, and the specific steps are as follows:

[0047] S501: The high-pressure airflow generated by the air compressor is delivered to one side of the liquid spray head through the air pipe, and then sprayed out from the other side of the liquid spray head through the internal channel of the liquid spray head.

[0048] S502. Two syringes are loaded with polymer solution A and polymer solution B respectively. The syringes are pushed forward by the injection pump to output the solution. Polymer solution A and polymer solution B are delivered to two dispensing needles through Teflon tubes and squeezed out from the needle tips of the dispensing needles.

[0049] S503, the tips of the two dispensing needles are directly opposite the airflow outlet of the liquid spray nozzle. The high-pressure airflow ejected from the liquid spray nozzle pulls polymer solution A and polymer solution B to form a polymer jet.

[0050] Compared with the prior art, the beneficial effects of the present invention are:

[0051] (1) In this invention, each polymer jet carries the same charge, so that the repulsion between like charges prevents the formation of nanofibers or entanglement between jets, which is common in traditional multi-jet liquid spraying. Therefore, the spacing between dispensing needles can be reduced, thereby increasing needle density and nanofiber yield.

[0052] Furthermore, in this invention, the initial driving force for forming the jet is a high-speed airflow, and each dispensing needle is not directly connected to the high-voltage electrostatic generator. Therefore, the amount of charge carried by each dispensing needle is much less than that in multi-needle electrospinning, effectively reducing the interference of the electric field between the needles in the multi-needle electrospinning process. Thus, the spacing between the dispensing needles can be reduced, thereby effectively increasing the arrangement density of the dispensing needles and improving the yield of nanofibers.

[0053] The dispensing needle spacing of this invention can reach 1.5-2mm. The extremely small needle spacing can effectively increase the needle density and thus increase the yield of nanofibers.

[0054] (2) In this invention, since each polymer jet carries the same charge, the repulsive force between the charges helps the jet itself to split and refine, thus it is possible to prepare nanofibers that are finer than those produced by traditional multi-jet liquid-jet spinning.

[0055] Furthermore, grounding the dispensing needle tip is employed, which allows for more effective transfer of charge in the jet, thereby enhancing the induced charging effect of the jet and exacerbating the breakage caused by the repulsive force between charges, thus enabling the fabrication of finer nanofibers.

[0056] (3) The needle-based preparation technology used in this invention can effectively prevent the disadvantages of needle-free technology, such as unstable solution concentration and polymer accumulation on electrodes.

[0057] (4) The device in this invention can also be used to prepare nanosphere / fiber membranes. Under the premise of ensuring stable spinning / spray solution concentration, small and uniform diameter / size of fibers / microspheres, and high yield, the nanosphere / fiber membrane can be prepared in one step on a simple device by using the action of induction electrodes and airflow. The synchronous preparation of nanospheres and nanofibers can be achieved, thereby preparing a three-dimensional hybrid structure membrane with random distribution and interpenetration of microspheres / nanofibers. This structure membrane has better application value in the fields of biomedicine, filtration, and distillation. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the structure of the induction electrode-assisted multi-needle liquid jet spinning device in this invention;

[0059] Figure 2 The image shows a comparison of the morphology of nanofibers prepared according to Table 1 using the present invention and the multi-jet liquid spraying technology in Example 1 of the present invention, wherein: (a) multi-jet liquid spraying technology, (b) the technology of the present invention;

[0060] Figure 3 The image shows a comparison of the jet morphology during the preparation of nanofibers using the present invention and the multi-jet liquid spraying technology according to Table 1 in Example 1 of the present invention, wherein: (a) multi-jet liquid spraying technology, (b) the technology of the present invention;

[0061] Figure 4 The image shows a comparison of the morphology of nanofibers prepared according to Table 2 using the present invention and the multi-jet liquid spraying technology in Example 2 of the present invention, wherein: (a) multi-jet liquid spraying technology, (b) the technology of the present invention;

[0062] Figure 5 The image shows a comparison of the morphology of nanofibers prepared according to Table 3 using the present invention and the multi-jet liquid spraying technology in Example 3 of the present invention, wherein: (a) multi-jet liquid spraying technology, (b) the technology of the present invention;

[0063] Figure 6 This is a schematic diagram of the apparatus for preparing nanospheres / fiber membranes in Example 4 of the present invention;

[0064] Figure 7 The images show a morphological comparison between the nanosphere / fiber membrane prepared in Example 4 of this invention and the nanofibers prepared by the prior art, wherein: (a) nanofibers in patent CN109023554B, and (b) nanosphere / fiber membrane in this invention.

[0065] In the diagram: 1. Air compressor; 2. Liquid injection head; 3. Injection pump; 4. Syringe; 5. Teflon tube; 6. Dispensing needle; 7. Hollow metal cylinder; 8. High-voltage electrostatic generator; 9. Metal receiving electrode plate. Detailed Implementation

[0066] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0067] Example 1:

[0068] See Figure 1 The induction electrode-assisted multi-needle liquid-jet spinning device includes an air compressor 1, a liquid-jet die head 2, an injection pump 3, a syringe 4, a Teflon tube 5, a dispensing needle 6, a hollow metal cylinder 7, a high-voltage electrostatic generator 8, and a metal receiving electrode plate 9. A schematic diagram of the device is shown below. Figure 1 As shown.

[0069] In this embodiment, the air compressor 1 is connected to the liquid spray head 2 via its own air hose. A certain amount of polymer solution is loaded into the syringe 4. The injection pump 3 is a multi-channel injection pump, and several syringes 4 are controlled by the multi-channel injection pump to output the polymer solution at a certain injection speed. A Teflon tube 5 is connected to the outlet of each syringe 4, and the other end of each Teflon tube 5 is connected to a dispensing needle 6. The dispensing needle 6 is fixed to the clamping plate of the liquid spray head 2. The hollow metal cylinder 7 is connected to the high-voltage electrostatic generator 8 via a wire. The dispensing needle 6 and the metal receiving electrode 9 are respectively connected to the ground via wires.

[0070] The fabrication process of the induction electrode-assisted multi-needle liquid jet spinning device is as follows:

[0071] Multiple syringes 4 are filled with a polymer solution for spinning. A multi-channel injection pump extrudes the polymer solution at a controlled injection speed. Driven by the multi-channel injection pump, the polymer solution passes through a Teflon tube 5 to a dispensing needle 6 and is extruded from the tip of the dispensing needle 6. The tips of the multiple dispensing needles 6 are directly opposite the outlet of the liquid jet head 2 and are arranged horizontally, with each needle tip within the effective range of the airflow at the right outlet of the liquid jet head 2.

[0072] The high-pressure gas output from air compressor 1 is transported to liquid spray nozzle 2 via an air pipe and ejected from the right outlet of liquid spray nozzle 2 to form a high-speed airflow for stretching the polymer solution. Under the stretching action of the high-speed airflow ejected from liquid spray nozzle 2, the polymer solution forms a polymer jet at the tip of dispensing needle 6. One jet is formed at each dispensing needle 6. Multiple jets fly over the cavity of the hollow metal cylinder 7 under the stretching and pulling action of the airflow. When the high-voltage electrostatic generator 8 is working, a high-voltage electrostatic field is formed near the hollow metal cylinder 7. When the multiple polymer jets enter this high-voltage electrostatic field, they will acquire the same charge due to electrostatic induction. Finally, they reach the metal receiving plate 9 and are used to produce nanofiber nonwoven fabric.

[0073] Based on the above device, the induction electrode-assisted multi-needle liquid jet spinning method comprises the following steps:

[0074] 1. Add 5 grams of M to 95 grams of deionized water. W =10 6 A 5% polyethylene oxide solution is prepared by stirring the polyethylene oxide powder with a stirrer for 24 hours and then letting it stand for 10 hours.

[0075] 2. Take 15 syringes 4 and draw the polyethylene oxide solution prepared above. Connect a Teflon tube 5 to the outlet of each syringe 4, and connect a dispensing needle 6 to the other end of the Teflon tube 5. Install the 15 syringes 4 on two multi-channel injection pumps and set the injection rate of the multi-channel injection pumps to 0.4 ml / h.

[0076] 3. Fix the dispensing needles 6 onto the clamping plate of the liquid spray head 2, so that the tips of the 15 dispensing needles 6 are arranged horizontally and are all within the effective range of the airflow at the outlet of the liquid spray head 2, and adjust the spacing between the dispensing needles 6 to 1.5-2mm.

[0077] 4. Select a hollow metal cylinder with a length of 10cm and a diameter of 15cm.

[0078] 5. Adjust the position of the hollow metal cylinder 7 so that it is 8mm away from the dispensing needle 6.

[0079] 6. Adjust the distance between the dispensing needle 6 and the metal receiving electrode 9 to 110cm.

[0080] 7. Ground the dispensing needle 6 and the metal receiving plate 9 respectively.

[0081] 8. Set the output air pressure of air compressor 1 to 0.02MPa and the output voltage of high voltage electrostatic generator 8 to 6.5kV respectively.

[0082] 9. The preparation time is set to 8 minutes.

[0083] 10. Remove the nanofiber nonwoven fabric after the time is up.

[0084] The nanofibers prepared by the inductive electrode-assisted multi-needle liquid jet spinning method in Example 1 of the present invention were compared with the nanofibers prepared by the traditional multi-jet liquid jet spinning method under the same preparation process conditions. The performance comparison of the nanofibers prepared by the two methods is shown in Table 1.

[0085] Table 1 Comparison of the preparation process and fiber properties of this patent and multi-jet liquid spraying.

[0086]

[0087]

[0088] As shown in Table 1, under the same preparation process conditions, compared with multi-jet liquid spraying, this method can reduce the average fiber diameter by 38.3% and the standard deviation of fiber diameter by 65.6%.

[0089] Depend on Figure 2 It can be seen that, compared to multi-jet liquid jet ( Figure 2 (a) In this invention, the method ( Figure 2 (b) This effectively eliminates entanglement between nanofibers. Traditional multi-jet liquid spraying typically uses a needle spacing greater than 3 mm to reduce entanglement and fusion between nanofibers and the jet (see the literature "Industrial-Scale Solution Blowing of Soy Protein Nanofibers"). When the spacing is smaller than this distance, jet fusion and entanglement occur, such as... Figure 3 As shown in (a). This method, under the same needle spacing, does not exhibit jet fusion, as... Figure 3 As shown in (b). Therefore, this method can effectively reduce the needle spacing, thereby increasing the needle density and thus increasing the yield of nanofibers.

[0090] Example 2:

[0091] The difference from Example 1 is that the induction electrode-assisted multi-needle liquid-jet spinning method has the following steps:

[0092] 1. Add 5 grams of M to 95 grams of deionized water. W =10 6 A 5% polyethylene oxide solution is prepared by stirring the polyethylene oxide powder with a stirrer for 24 hours and then letting it stand for 10 hours.

[0093] 2. Take 12 syringes 4 and draw the polyethylene oxide solution prepared above. Connect a Teflon tube 5 to the outlet of each syringe 4, and connect a dispensing needle 6 to the other end of the Teflon tube 5. Install the 12 syringes 4 on two multi-channel injection pumps and set the injection rate of the multi-channel injection pumps to 0.4 ml / h.

[0094] 3. Fix the dispensing needles 6 onto the clamping plate of the liquid spray head 2, so that the tips of the 12 dispensing needles 6 are arranged horizontally and are all within the effective range of the airflow at the outlet of the liquid spray head 2, and adjust the spacing between the dispensing needles 6 to 1.5-2mm.

[0095] 4. Select a hollow metal cylinder with a length of 10cm and a diameter of 15cm.

[0096] 5. Adjust the position of the hollow metal cylinder 7 so that it is 8mm away from the dispensing needle 6.

[0097] 6. Adjust the distance between the dispensing needle 6 and the metal receiving electrode 9 to 110cm.

[0098] 7. Ground the dispensing needle 6 and the metal receiving plate 9 respectively.

[0099] 8. Set the output air pressure of air compressor 1 to 0.02MPa and the output voltage of high voltage electrostatic generator 8 to 6.5kV respectively.

[0100] 9. The preparation time is set to 10 minutes.

[0101] 10. Remove the nanofiber nonwoven fabric after the time is up.

[0102] The nanofibers prepared by the inductive electrode-assisted multi-needle liquid jet spinning method in Example 2 of the present invention were compared with those prepared by the traditional multi-jet liquid jet spinning method under the same preparation process conditions. The performance comparison of the nanofibers prepared by the two methods is shown in Table 2.

[0103] Table 2 Comparison of the preparation process and fiber properties of this patent and multi-jet liquid spraying.

[0104]

[0105]

[0106] Table 2 shows that, under the same preparation process conditions, compared with multi-jet liquid spraying, this method can reduce the average fiber diameter by 44.8% and the standard deviation of fiber diameter by 72.5%. Figure 4 It can be seen that, compared to multi-jet liquid jet ( Figure 4 (a) In this invention, the method ( Figure 4 (b) can effectively eliminate entanglement between nanofibers.

[0107] Example 3:

[0108] The difference from Examples 1 and 2 is that the induction electrode-assisted multi-needle liquid-jet spinning method has the following steps:

[0109] 1. Add 5 grams of M to 95 grams of deionized water. W =10 6 A 5% polyethylene oxide solution is prepared by stirring the polyethylene oxide powder with a stirrer for 24 hours and then letting it stand for 10 hours.

[0110] 2. Take nine syringes 4 and draw the polyethylene oxide solution prepared above. Connect a Teflon tube 5 to the outlet of each syringe 4, and connect a dispensing needle 6 to the other end of the Teflon tube 5. Install the nine syringes 4 on two multi-channel injection pumps and set the injection rate of the multi-channel injection pumps to 0.4 ml / h.

[0111] 3. Fix the dispensing needles 6 on the clamping plate of the liquid spray head 2, so that the tips of the nine dispensing needles 6 are arranged horizontally and are all within the effective range of the airflow at the outlet of the liquid spray head 2, and adjust the spacing between the dispensing needles 6 to 1.5-2mm.

[0112] 4. Select a hollow metal cylinder with a length of 10cm and a diameter of 15cm.

[0113] 5. Adjust the position of the hollow metal cylinder 7 so that it is 8mm away from the dispensing needle 6.

[0114] 6. Adjust the distance between the dispensing needle 6 and the metal receiving electrode 9 to 110cm.

[0115] 7. Ground the dispensing needle 6 and the metal receiving plate 9 respectively.

[0116] 8. Set the output air pressure of air compressor 1 to 0.02MPa and the output voltage of high voltage electrostatic generator 8 to 6.5kV respectively.

[0117] 9. The preparation time is set to 13 minutes.

[0118] 10. Remove the nanofiber nonwoven fabric after the time is up.

[0119] The nanofibers prepared by the inductive electrode-assisted multi-needle liquid jet spinning method in Example 3 of the present invention were compared with the nanofibers prepared by the traditional multi-jet liquid jet spinning method under the same preparation process conditions. The performance comparison of the nanofibers prepared by the two methods is shown in Table 3.

[0120] Table 3 Comparison of the preparation process and fiber properties of this patent and multi-jet liquid spraying.

[0121]

[0122]

[0123] Table 3 shows that, under the same preparation process conditions, compared with multi-jet liquid spraying, this method can reduce the average fiber diameter by 53.1% and the standard deviation of fiber diameter by 78.8%. Figure 5 It can be seen that, compared to multi-jet liquid jet ( Figure 5 (a) In this invention, the method ( Figure 5 (b) can effectively eliminate entanglement between nanofibers.

[0124] In summary, the induction electrode-assisted multi-needle liquid-jet spinning method of this invention has the following advantages compared with existing large-scale nanofiber preparation technologies:

[0125] Compared to multi-jet liquid spraying, the method in this invention can effectively reduce the diameter and standard deviation of nanofibers (Tables 1, 2, 3), and can also eliminate entanglement between nanofibers. Figure 2 , 4 5). Furthermore, the principle of like charges repelling each other can be utilized to largely eliminate the fusion of adjacent jets, thereby effectively reducing the needle spacing (which can be reduced to 1.5-2 mm), and thus increasing needle density and fiber yield. Figure 3 ).

[0126] Compared to multi-needle electrospinning, the method in this invention can effectively reduce the needle spacing. Multi-needle electrospinning suffers from electric field interference between needles, leading to jet repulsion. The minimum needle spacing that a multi-needle electrospinning device can stably produce is 100 mm (see the literature "Multinozzle high efficiency electrospinning with the constraint of sheath gas"). This invention can effectively reduce the needle spacing (to 1.5-2 mm), thereby increasing needle density and ultimately improving the yield of nanofibers.

[0127] Compared to needleless multi-jet electrospinning, this method avoids the disadvantages of unstable spinning solution, easy accumulation of polymer on electrodes, and uneven electrode electric field.

[0128] Example 4:

[0129] Nanosphere / fiber membranes were prepared using the apparatus described in Examples 1-3. The difference from Examples 1-3 is that:

[0130] See Figure 6 In this device, two syringes 4 are respectively loaded with polymer solution A and polymer solution B. The two syringes 4 can be loaded simultaneously on the same multichannel injection pump, or they can be loaded separately on two injection pumps 3.

[0131] The process of preparing nanosphere / fiber membranes using this device is as follows:

[0132] High-pressure airflow generated by air compressor 1 is delivered to the left inlet of liquid spray head 2 through an air pipe, and then ejected from the right outlet of liquid spray head 2 through the internal channel of liquid spray head 2. Injector 4, propelled forward by injection pump 3, outputs polymer solutions. The two polymer solutions are delivered to two dispensing needles 6 through Teflon tubing 5 and extruded from the needle tips of the dispensing needles 6. The needle tips of the two dispensing needles 6 are directly opposite the airflow outlet of liquid spray head 2. The high-speed airflow ejected from liquid spray head 2 pulls the two polymer solutions, forming polymer jets. Under the pull of the airflow, the two polymer jets fly over the internal cavity of the hollow metal cylinder 7, ultimately forming nanosphere / fiber membranes on the metal receiving plate 9.

[0133] A hollow metal cylinder 7 is connected to a high-voltage electrostatic generator 8. When the high-voltage electrostatic generator 8 operates, a high-voltage electrostatic field is formed near the hollow metal cylinder 7. When two jets enter this high-voltage electrostatic field, they acquire the same type of charge with opposite polarity to that output by the high-voltage electrostatic generator 8 due to electrostatic induction. The repulsive force of the like charges within the jets accelerates their breakup, forming nanospheres or nanofibers, which are ultimately collected on the metal receiving plate 9. The difference in raw materials or concentrations causes polymer solution A and polymer solution B to ultimately form nanospheres and nanofibers, respectively.

[0134] Based on the above-described apparatus, the method for preparing nanosphere / fiber membranes comprises the following steps:

[0135] 1. Take 1 gram of M W =4×10 5 Polyoxyethylene powder was dissolved in 99 grams of deionized water. The solution was stirred for 8 hours and then allowed to stand for 8 hours to prepare a 1% polyoxyethylene solution, which was denoted as solution A.

[0136] 2. Take 7 grams of M W =10 6 Polyoxyethylene powder was dissolved in 93 grams of deionized water. The solution was stirred for 24 hours and then allowed to stand for 12 hours to prepare a 7% polyoxyethylene solution, which was denoted as solution B.

[0137] 3. Use two syringes 4 to draw out solutions A and B respectively, and connect Teflon tubing 5 to the outlet of syringe 4. Connect dispensing needle 6 to the other end of Teflon tubing 5. Load the two syringes 4 onto two injection pumps 3 respectively. Set the injection speed of the injection pump 3 containing the syringe containing solution A to 1.3 ml / h, and set the injection speed of the injection pump 3 containing the syringe containing solution B to 0.5 ml / h.

[0138] 4. Fix the two dispensing needles 6 on the liquid spray head 2, so that the needle tips of the two dispensing needles 6 are equidistant from the center point of the airflow outlet of the liquid spray head 2 and ensure that the needle tips of the two dispensing needles 6 are within the effective range of the high-speed airflow.

[0139] 5. Select a hollow metal cylinder with a length of 4cm and a diameter of 15cm.

[0140] 6. Position the hollow metal cylinder 7 so that it is 1mm away from the dispensing needle 6.

[0141] 7. Adjust the distance between the dispensing needle 6 and the metal receiving electrode 9 to 110cm.

[0142] 8. Connect the two dispensing needles 6 and the metal receiving plate 9 to the ground in sequence.

[0143] 9. Set the output air pressure of air compressor 1 to 0.016MPa.

[0144] 10. Set the output voltage of the high-voltage electrostatic generator 8 to 7.8kV.

[0145] 11. Put the injection pump 3, air compressor 1 and high-voltage electrostatic generator 8 into working condition.

[0146] 12. Preparation time is 60 minutes.

[0147] 13. After the time is up, remove the prepared nanospheres / fiber membrane from the metal receiving plate 9.

[0148] The performance of the nanospheres / fiber membrane prepared by the method for preparing nanospheres / fiber membranes in Example 4 of the present invention was compared with that of the nanofibers prepared by patent CN109023554B. The performance comparison of the nanofibers prepared by the two methods is shown in Table 4.

[0149] Table 4 Comparison of preparation processes and nanofiber properties of the present invention and patent CN109023554B in Example 4

[0150]

[0151]

[0152] As shown in Table 4, under the same preparation process conditions, compared with patent CN109023554B, the average diameter of the nanofibers prepared by this patent decreased by 35.7%, and the standard deviation of the diameter decreased by 68.6%.

[0153] See Figure 7 , Figure 7 This image shows a morphological comparison of the nanofibers prepared according to the present invention and those prepared according to patent CN109023554B. Figure 7Figure a shows the morphology of the nanofiber membrane produced using the technology of patent CN109023554B according to the preparation process in Table 4. Figure 7 Figure b shows the morphology of the nanosphere / fiber membrane produced by the preparation process according to Table 4 of this invention. Figure 7 Figure a shows only nanofibers. Figure 7 Figure b shows nanospheres and fibers; this invention achieves the simultaneous preparation of nanospheres and nanofibers, producing nanosphere / fiber membranes (such as...). Figure 7 (b) shows a difference from the single nanofiber membrane prepared by patent CN109023554B (as shown in the image). Figure 7 (a) shows that it has a wider range of applications and higher use value.

[0154] In summary, compared with existing technologies using a two-step method, this invention can achieve one-step preparation of nanospheres / fiber membranes and improve yield; compared with patent CN106237717B using a one-step method, this invention does not produce problems such as unstable spinning solution and easy accumulation of polymers on electrodes; compared with patent CN109023554B, this invention has the following advantages: ① finer fibers with more uniform diameter; ② simultaneous preparation of nanospheres and nanofibers.

[0155] The above description is only for the purpose of helping to understand the method and core essence of the present invention, but the scope of protection of the present invention is not limited thereto. For those skilled in the art, any equivalent substitutions or modifications made to the technical solution and inventive concept disclosed in the present invention within the scope of the technology disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A sensing electrode-assisted multi-needle liquid jet spinning device, comprising an air compressor (1), a liquid jet die head (2), a syringe (4), and a dispensing needle (6); wherein the air compressor (1) is connected to the liquid jet die head (2) via an air pipe, characterized in that: The dispensing needle (6) is provided in at least two parts, and the distance between the dispensing needles (6) is 1.5~2mm; The syringe (4) is filled with a polymer solution and is mounted on the injection pump (3); the syringe (4) is connected to the dispensing needle (6) via a Teflon tube (5); the dispensing needle (6) is mounted on the liquid spray head (2); It also includes a hollow metal cylinder (7), a high-voltage electrostatic generator (8), and a metal receiving electrode plate (9); The hollow metal cylinder (7) is located on the side of the dispensing needle (6) away from the liquid spray head (2). The hollow metal cylinder (7) is connected to the high voltage electrostatic generator (8) through a wire. The metal receiving plate (9) is connected to the ground through a wire. The dispensing needle (6) is connected to the ground through a wire. Each dispensing needle (6) forms a polymer spinning jet at its tip. Under the pull of the high-pressure airflow, the polymer spinning jet flies over the internal cavity of the metal hollow cylinder (7). Under the action of electrostatic induction, the polymer spinning jet carries the same charge with opposite polarity to that output by the high-voltage electrostatic generator (8) inside its own jet. The polymer spinning jets formed from the tips of each dispensing needle (6) repel each other, and the polymer jet breaks down to form nanofibers. Grounding the dispensing needle (6) enables the charge in the polymer spinning jet to be transferred more effectively, improves the induced charging effect of the polymer spinning jet, and intensifies the breakage of the polymer spinning jet caused by the repulsion between charges, thus producing finer nanofibers. The tip of the dispensing needle (6) is directly opposite the airflow outlet of the liquid spraying head (2), and the distance between the tip of the dispensing needle (6) and the airflow outlet of the liquid spraying head (2) is equal. The distance between the dispensing needle and the hollow metal cylinder is 1mm or 8mm.

2. The induction electrode-assisted multi-needle liquid-jet spinning device according to claim 1, characterized in that, The dispensing needles (6) are arranged horizontally.

3. The induction electrode-assisted multi-needle liquid-jet spinning device according to claim 1, characterized in that, The syringe (4) is provided with at least one, and the syringe (4) is loaded with at least one polymer solution.

4. The induction electrode-assisted multi-needle liquid-jet spinning device according to claim 3, characterized in that, The Teflon tube (5) is one or two types of multi-channel Teflon tube or single-channel Teflon tube.

5. The induction electrode-assisted multi-needle liquid-jet spinning device according to claim 3, characterized in that, The injection pump (3) is a multi-channel injection pump, and the multi-channel injection pump is provided with at least one, and the multi-channel injection pump maintains the same control speed or different control speeds.

6. A method for induction electrode-assisted multi-needle liquid-jet spinning using the apparatus described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Weigh polymer particles or powder into a solvent, stir, and let stand to prepare a polymer solution; S2. Extract the polymer solution for loading; S3. Set parameters and start the device; S4. High-pressure airflow pulls the polymer solution to form a polymer spinning jet. Each dispensing needle (6) forms a polymer spinning jet at its tip. The polymer spinning jet flies over the internal cavity of the metal hollow cylinder (7) under the pulling action of the high-pressure airflow. S5. A high-voltage electrostatic field is formed near the metal hollow cylindrical tube (7). The dispensing needle (6) and the metal receiving plate (9) are both grounded to form zero potential. The polymer spinning jet carries the same type of charge with opposite polarity to that output by the high-voltage electrostatic generator (8) inside the jet. The polymer jet breaks to form nanofibers, and the polymer spinning jets formed by each dispensing needle (6) repel each other. S6. Nanofibers pass through a hollow metal cylinder (7) and are deposited on a metal receiving electrode (9).

7. A method for preparing nanosphere / fiber membranes using the apparatus described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Weigh polymer particles or powder into a solvent, stir, and let stand to prepare polymer solution A; S2. Weigh the polymer particles or powder into the solvent, stir, and let stand to prepare polymer solution B; S3. Extract polymer solution A and polymer solution B separately for loading; S4. Set parameters and start the device; S5. High-pressure airflow pulls polymer solution A and polymer solution B to form a polymer jet. The two polymer jets fly over the internal cavity of the metal hollow cylinder (7) under the pulling action of the high-pressure airflow. S6. A high-voltage electrostatic field is formed near the metal hollow cylindrical tube (7). The dispensing needle (6) and the metal receiving plate (9) are both grounded to form zero potential. Under the action of electrostatic induction, the two polymer jets carry the same type of charge with opposite polarity to that output by the high-voltage electrostatic generator (8) inside their respective jets. The polymer jets break down to form nanospheres or nanofibers. S7. Two polymer jets pass through the metal hollow cylinder (7) and are received on the metal receiving plate (9) to form a nanosphere / fiber membrane.

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