Airflow assisted multi-stage electrostatic field convergent spinning device and method

Abstract

The application discloses a kind of airflow assisted multi-stage electrostatic field convergence spinning device and method, including sequentially designed: injection pump, multi-stage spinning convergence device and collection device;The injection pump is connected with the inner needle of needle, the outer tube of the needle is connected with auxiliary gas supply device, and the needle is connected with high voltage power supply, and the collection device is grounded connection;The multi-stage spinning convergence device includes: three parallelly arranged insulating plates with holes, and the opening of the insulating plate from injection pump to collection device side decreases sequentially.The application sets multi-stage spinning convergence device, the opening aperture of three insulating plates decreases sequentially, so that the passing radius of charged jet when initially entering the device is large enough, and the normal electric field force suffered by charged jet increases sequentially, while ensuring the yield, to maximize the beneficial effect.

Description

TECHNICAL FIELD

[0001] The application discloses an airflow-assisted multi-stage electrostatic field converging spinning device and method, and relates to the technical field of electrospinning. BACKGROUND

[0002] Electrospinning is a nanometer preparation technology, which converts a high polymer fiber solution into superfine fibers with a diameter of about 10-1000 nm by using electrostatic force. It is generally considered to be one of the most effective nanofiber preparation methods due to its simple preparation device, adjustable fiber diameter, good size consistency, and the ability to prepare fibers with high specific strength and gradient structure.

[0003] A Chinese invention patent with the publication number CN113417015A discloses a multi-directional linkage electrospinning method based on controllable electric field. The key point is that the solution for electrospinning is sprayed out through a nozzle and then enters the superimposed electric field. The device performs third-stage adjustment, and the three superimposed electric fields at the nozzle and other positions act on the falling electrospun fibers. This method can control the stability of the jet to a certain extent, but the device structure is complex, and the active electric field between the multi-stage superimposed electric field generating devices may interfere with each other, which has limited effect on the stability of the jet. Moreover, the superimposed electric field outside the nozzle may affect the formation of the Taylor cone and thus affect the normal electrospinning.

[0004] A Chinese invention patent with the publication number CN113388899B discloses a magnetic lens electrospinning device. The key point is that an electromagnetic lens is composed of two mutually buckled magnetic yokes and an excitation coil between the two magnetic yokes. A direct current power supply supplies power to the excitation coil through a wire to generate a magnetic focusing effect, and the electrospinning is completed under the cooperation of the magnetic field and the electric field. This method can make the prepared nanofibers finer and more uniform in thickness to a certain extent, but the position of the magnetic lens is relatively fixed in this method, and the generation of the magnetic field may affect the collection of the fibers on the receiving device.

[0005] However, the electrospun fiber membranes produced at the present stage are difficult to meet the requirements and form large-scale industrial production. One of the main reasons is that it is difficult to effectively control the electrospinning jet in the non-uniform high-voltage electric field between the needle and the collection plate, causing unstable oscillation of the jet during the spinning process. In addition, due to the charge repulsion between nanofibers, the obtained fiber membrane has a relatively thick fiber diameter and a low fiber alignment degree. However, there is no mature solution to effectively improve the stability of the electrospinning jet and simultaneously thin the fibers and achieve high orientation arrangement. SUMMARY

[0006] The present application aims at the defects in the prior art, and provides an airflow-assisted multi-stage electrostatic field converging spinning device and method, which improves the stability of electrospinning jet, so that the electrospinning is more accurate and controllable, and the spun fiber has better performance.

[0007] To achieve the above object, the present application adopts the technical scheme as follows: an airflow-assisted multi-stage electrostatic field converging spinning device, comprising sequentially designed injection pump, multi-stage spinning converging device and collecting device;

[0008] The injection pump is connected with the inner needle of the needle head, the outer tube sleeve of the needle head is connected with the auxiliary gas supply device, the needle head is connected with the high-voltage power supply, and the collecting device is grounded.

[0009] The multi-stage spinning converging device comprises three sequentially parallel arranged hole-insulating plates, and the hole diameters of the hole-insulating plates sequentially decrease from the injection pump to the collecting device.

[0010] Further, the center of the hole of the needle head is collinear with the center of the hole of the three hole-insulating plates, if the centers of the holes of the three hole-insulating plates are not collinear, the eccentricity is not more than 5mm.

[0011] Further, the hole diameter of the hole-insulating plate ranges from 50mm to 150mm.

[0012] Further, the hole-insulating plate is slidingly connected on the workbench, the workbench is provided with a sliding groove, the bottom of the hole-insulating plate is connected with a sliding block, and the two ends of the sliding block are slidingly connected in the sliding groove.

[0013] Further, when the planes of the three hole-insulating plates are not parallel to each other, the deviation angle of the three hole-insulating plates is less than ±1.5°.

[0014] Further, the distance between the hole-insulating plates is equal, and the distance ranges from 25mm to 75mm.

[0015] Further, the hole-insulating plate can be made of 3240 epoxy resin plate or PP / PE plate, and the thickness of the hole-insulating plate ranges from 1.0mm to 3.0mm.

[0016] Further, the airflow of the auxiliary gas supply device ranges from 100ml / min to 120ml / min.

[0017] A spinning method based on the above-mentioned airflow-assisted multi-stage electrostatic field converging spinning device, comprising the following steps:

[0018] The core layer solution of the injection pump is selected from polyurethane solution with a mass concentration of 18%;

[0019] The airflow provided by the auxiliary gas supply device connected to the outer tube sleeve of the needle is 110 ml / min; the high-voltage power supply voltage is set to 20 kv, and the distance between the receiving device and the needle is set to 15 cm;

[0020] The positions of the three hole insulating plates in the multi-stage spinning convergence device are adjusted, and the initial separation distances are all set to 3 cm. The starting end of the device is on the side of the injection pump, and the insulating plates are arranged in the order of 150 mm, 100 mm, and 50 mm, with the largest hole diameter being 3 cm away from the needle.

[0021] The spinning speed of the injection pump is 50 ml / h. Under the propulsion of the injection pump, the core layer solution is pushed out at the needle, forms a Taylor cone under the action of the high-voltage electric field, and emits a charged jet. The unstable jet passes through the openings of the three insulating plates in turn under the convergence of the shell auxiliary airflow, and gradually accumulates electric charges on the surface until a stable charge arrangement is formed. The stable charge arrangement forms a normal electric field, which acts on the charged jet to make the jet stable, and finally obtains electrospun fibers with a diameter of 100-200 nm. Advantages

[0022] The guiding workbench is arranged, the horizontal positions of the three insulating plates can be independently adjusted, the corresponding separation distances between the insulating plates can be adjusted according to different hole diameters, product convergence is facilitated, and the quality of the product is improved.

[0023] The auxiliary airflow is arranged to improve the stability of the outflow of the spinning solution. First, the flow rate of the auxiliary airflow arranged in the shell layer of the needle is higher than the outflow rate of the inner layer spinning solution, the outflow is stable, and the directionality is strong, which plays a stabilizing role when the spinning solution forms a Taylor cone at the needle. Second, during the initial stage of spinning, when the charges at the openings of the insulating plates are stably distributed, the auxiliary airflow can guide the charged jet to pass through the inside of the opening of the insulating plate, reduce the influence of the repulsion of the unstable electric field on the charged jet, and make more charged jets pass through the inside of the opening of the insulating plate, thereby reducing the loss.

[0024] The multi-stage spinning convergence device is arranged, the hole diameters of the three insulating plates are gradually reduced, the passing radius of the charged jet when it initially enters the device is large enough, and the normal electric field force acting on the charged jet is gradually increased, so that the yield is ensured and the stretching is sufficient, and the charged jet has sufficient stretching effect. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present application;

[0026] Figure 2 It is a schematic diagram of the multi-stage electrostatic field convergence device in the present application;

[0027] Figure 3A schematic diagram of a traditional needle-plate electrospinning device and its jet region;

[0028] Figure 4 In order to be in Figure 3 Based on this, a schematic diagram of the spinning path and jet region of a small-aperture perforated insulating plate (d1=50mm) is introduced;

[0029] Figure 5 In order to be in Figure 3 Based on this, a schematic diagram of the spinning path and jet region of a large-aperture perforated insulating plate (d2=150mm) is introduced;

[0030] Figure 6 In order to be in Figure 2 A schematic diagram of the spinning path and jet region based on the introduction of a multi-stage spinning convergence device;

[0031] Figure 7 A schematic diagram illustrating the principle of generating an electric field by accumulating charge on the surface of an insulating board. Detailed Implementation

[0032] The implementation of the technical solution will be further described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0033] like Figure 1 The embodiment shown in Example 1 provides an airflow-assisted multi-stage electrostatic field converging spinning device, which includes, in sequence: an injection pump 1, a multi-stage spinning converging device 6, and a collecting device 9;

[0034] The injection pump 1 is connected to the inner needle of the needle 2, the outer tube of the needle 2 is connected to the auxiliary gas supply device 3, and the needle 2 is connected to the high voltage power supply 4. The collecting device 9 is connected to the ground 10.

[0035] like Figure 2 As shown, the multi-stage spinning and gathering device 6 includes three perforated insulating plates 5 arranged in parallel in sequence, with the openings of the insulating plates 5 decreasing sequentially from the injection pump 1 to the collecting device 9.

[0036] The center of the needle 2 is collinear with the center of the opening of the three perforated insulating plates 5. If the center of the opening of the three perforated insulating plates 5 is not collinear, the eccentricity shall not exceed 5mm.

[0037] The perforated insulating plate 5 has a hole diameter range of 50~150mm.

[0038] The perforated insulating plate 5 is slidably connected to the workbench 7. A sliding groove is provided on the workbench 7. A slider is connected to the bottom of the perforated insulating plate 5, and the two ends of the slider are slidably connected in the sliding groove.

[0039] When the planes of the three insulating plates 5 are not parallel to each other, the deviation angle of the three is less than ±1.5°.

[0040] The distance between the insulating plates 5 is equal, and the distance is 25-75 mm.

[0041] The hole insulating plate 5 can use 3240 epoxy resin plate or PP / PE plate.

[0042] The thickness of the hole insulating plate 5 is 1.0-3.0 mm.

[0043] The gas flow of the auxiliary gas supply device 3 is 100-120 ml / min.

[0044] The spinning method of the above-mentioned gas flow assisted multi-stage electrostatic field convergent spinning device includes the following steps:

[0045] Step 1: the core layer solution selects a polyurethane PU solution with a mass concentration of 18%, and

[0046] Step 2: the gas flow provided by the auxiliary gas supply device 3 connected by the outer sleeve of the needle 2 is 110 ml / min; the voltage of the high-voltage power supply 4 is set to 20 kv, and the distance between the receiving device and the needle 2 is set to 15 cm,

[0047] Step 3: the three hole insulating plates 5 in the multi-stage spinning convergent device 6 all use 3240 epoxy resin plates, the three hole centers are adjusted to be collinear with the needle 2, the plate planes are parallel to each other, and the initial distance is set to 3 cm; the side of the injection pump 1 is the starting end of the device, and the hole diameters are arranged in the order of 150 mm, 100 mm, and 50 mm, and the largest side of the hole diameter is 3 cm away from the needle 2.

[0048] Step 4: the spinning speed of the injection pump 1 is 50 ml / h, and under the propulsion of the injection pump 1, the core layer solution is pushed out at the needle 2, forms a Taylor cone and emits a charged jet under the action of the high-voltage electric field, and in the initial stage of spinning, the unstable jet is collected under the convergence of the shell auxiliary gas flow, passes through the openings of the three insulating plates 5 in turn, and gradually accumulates charges on the surface until a stable charge arrangement is formed. The stable charge arrangement will form a normal electric field, which will exert a normal electric field force on the charged jet, making the jet stable and forming a first jet region 8. The electrospun fibers obtained by the above method have a diameter mainly distributed between 100-200 nm. Example 2

[0049] The difference between the two is that:

[0050] The core layer solution selects a polyurethane (PU) solution with a mass concentration of 10%, and the spinning speed is set to 40 ml / h; the gas flow provided by the auxiliary gas supply device 3 is 90 ml / min. Example 3

[0051] The difference between the example 1 and the example 3 is that:

[0052] The core layer solution is selected as a polyurethane (PU) solution with a mass concentration of 5%, and the spinning speed is 25 ml / h.

[0053] The airflow provided by the auxiliary gas supply device 3 is 75 ml / min.

[0054] Comparative Example 1

[0055] As shown in the figure, compared with the airflow-assisted multi-stage electrostatic field converging spinning device disclosed, other parameters remain unchanged, and in the electrospinning device disclosed in the comparative example 1, only a conventional needle plate type electrospinning device is used and no auxiliary airflow is used for electrospinning experiment, and the second jet flow area 11 is shown by the collection device. Figure 3 Figure 1 Figure 3

[0056] Comparative Example 2

[0057] As shown in the figure, compared with the airflow-assisted multi-stage electrostatic field converging spinning device disclosed, other parameters remain unchanged, and in the electrospinning device disclosed in the comparative example 2, only a small aperture (d1=50mm) perforated insulating plate 5 is used to replace the multi-stage converging device and no auxiliary airflow is used for electrospinning experiment, and the third jet flow area 12 is shown by the collection device. Figure 4 Figure 1 Figure 4

[0058] Comparative Example 3

[0059] As shown in the figure, compared with the airflow-assisted multi-stage electrostatic field converging spinning device disclosed, other parameters remain unchanged, and in the electrospinning device disclosed in the comparative example 3, only a large aperture (d2=150mm) perforated insulating plate 5 is used to replace the multi-stage converging device and no auxiliary airflow is used for electrospinning experiment, and the fourth jet flow area 13 is shown by the collection device. Figure 5 Figure 1 Figure 5

[0060] Comparative Example 4

[0061] As shown in the figure, compared with the airflow-assisted multi-stage electrostatic field converging spinning device disclosed, other parameters remain unchanged, and in the electrospinning device disclosed in the comparative example 4, no auxiliary airflow is used for electrospinning experiment, and the fifth jet flow area 14 is shown by the collection device. Figure 6 Figure 1 Figure 6

[0062] Comparative Example 5​​​​​​​​​​​​

[0063] Basically the same as Example 1, except that:

[0064] The order of the insulating plates in the multi-stage spinning and gathering device 6 is changed.

[0065] With the injection pump 1 side as the starting end of the device, the hole diameters of the insulating plate are arranged in the order of 150mm, 50mm, and 100mm.

[0066] Comparative Example 6

[0067] Basically the same as Example 1, except that:

[0068] The order of the insulating plates in the multi-stage spinning and gathering device 6 is changed.

[0069] With the injection pump 1 side as the starting end of the device, the hole diameters of the insulating plate are arranged in the order of 50mm, 150mm, and 100mm.

[0070] Comparative Example 7

[0071] Basically the same as Example 1, except that:

[0072] The order of the insulating plates in the multi-stage spinning and gathering device 6 is changed.

[0073] With the injection pump 1 side as the starting end of the device, the insulating plates are arranged in the order of 50mm, 100mm, and 150mm.

[0074] like Figure 7 As shown, when the charged jet 15 passes through the opening in the insulating plate, the charge 16 carried by the jet continuously accumulates on the surface of the insulating plate. As the accumulated charge 18 on the insulating plate continuously increases and is stably arranged, a stable normal electric field—electric field line 19—is formed near the opening in the insulating plate. The electric field formed by the accumulated charge 18 has a centripetal repulsive effect on the charged jet with the same charge, which has the effect of converging and focusing the charged jet—the phenomenon of charged jet convergence 17.

[0075] Performance testing of the above embodiments

[0076] The electrospun film materials prepared in the above embodiments and comparative examples were characterized at the microstructure, and the test results are shown in Table 1:

[0077] Table 1

[0078] ;

[0079] As shown in Table 1, under the same conditions... Figure 1 The fiber obtained by electrospinning through the airflow-assisted multi-stage electrostatic field focusing method has the smallest average diameter, the smallest jet area, and the smallest diameter standard deviation.

[0080] The application sets the guide workbench, the workbench can independently adjust the horizontal position of three insulating plates, can adjust the corresponding distance between the insulating plates according to different aperture combinations, facilitates product gathering, and improves the quality of products.

[0081] The application sets the auxiliary airflow to improve the stability of the outflow of the spinning solution, first, the flow rate of the auxiliary airflow arranged on the needle head shell layer is higher than the outflow rate of the inner layer spinning solution, and the outflow is stable and directional, and plays a stabilizing role when the Taylor cone is formed at the needle head; second, in the initial stage of spinning, when the charge at the opening of the insulating plate is stably distributed, the auxiliary airflow will guide the jet flow, so that the charged jet flow passes through the inside of the opening of the insulating plate, reduces the influence of the unstable electric field on the repulsion of the charged jet flow, and makes more charged jet flow pass through the inside of the opening of the insulating plate, thereby reducing the loss.

[0082] The application sets the multi-stage spinning gathering device, the opening diameters of the three insulating plates are gradually reduced, so that the passing radius of the charged jet flow when initially entering the device is large enough, and the normal electric field force on the charged jet flow is gradually increased, so that the yield is ensured, the stretching is sufficient, and the charged jet flow has sufficient stretching effect.

[0083] The above is only the preferred embodiment of the application, and it should be pointed out that, for ordinary skilled persons in the art, without departing from the technical principles of the application, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the application.

Claims

1. An airflow-assisted multi-stage electrostatic field converging spinning device, characterized in that, It includes the following components designed sequentially: an injection pump (1), a multi-stage spinning convergence device (6), and a collection device (9). The injection pump (1) is connected to the inner needle of the needle (2), the outer tube of the needle (2) is connected to the auxiliary gas supply device (3), and the needle is connected to the high voltage power supply (4). The collection device (9) is grounded. The multi-stage spinning and gathering device (6) includes three perforated insulating plates (5) arranged in parallel in sequence, and the openings of the perforated insulating plates (5) from the injection pump (1) to the collecting device (9) side decrease in size.

2. The airflow-assisted multi-stage electrostatic field converging spinning device according to claim 1, characterized in that, The needle (2) is collinear with the center of the opening of the three perforated insulating plates (5). If the center of the opening of the three perforated insulating plates (5) is not collinear, the eccentricity shall not exceed 5 mm.

3. The airflow-assisted multi-stage electrostatic field converging spinning device according to claim 1, characterized in that, The perforated insulating plate (5) has a hole diameter range of 50~150mm.

4. The airflow-assisted multi-stage electrostatic field converging spinning device according to claim 1, characterized in that, The perforated insulating plate (5) is slidably connected to the workbench (7). A groove is provided on the workbench (7). A slider is connected to the bottom of the perforated insulating plate (5). The two ends of the slider are slidably connected to the groove.

5. The airflow-assisted multi-stage electrostatic field converging spinning device according to claim 1, characterized in that, When the planes of the three perforated insulating plates (5) are not parallel to each other, the deviation angle between them is less than ±1.5°.

6. The airflow-assisted multi-stage electrostatic field converging spinning device according to claim 1, characterized in that, The perforated insulating plates (5) are spaced at equal intervals, with a spacing of 25~75mm between each pair.

7. The airflow-assisted multi-stage electrostatic field converging spinning device according to claim 1, characterized in that, The perforated insulating board (5) can be made of 3240 epoxy resin board or PP / PE board, and the thickness of the perforated insulating board (5) ranges from 1.0 to 3.0 mm.

8. The airflow-assisted multi-stage electrostatic field converging spinning device according to claim 1, characterized in that, The auxiliary gas supply device (3) has an airflow of 100~120 ml / min.

9. A spinning method based on the airflow-assisted multi-stage electrostatic field converging spinning device according to any one of claims 1 to 8, characterized in that, Includes the following steps: The core layer solution of the injection pump (1) is a polyurethane solution with a mass concentration of 18%. The auxiliary gas supply device (3) provides an airflow of 110 ml / min to the outer tube of the needle (2); the high voltage power supply (4) is set to 20 kV, and the distance between the receiving device and the needle is set to 15 cm. Adjust the position of the three perforated insulating plates (5) in the multi-stage spinning and gathering device (6), and set the initial spacing to 3cm. Take the side of the injection pump (1) as the starting end of the device. The hole diameter of the perforated insulating plate (5) is arranged in the order of 150mm, 100mm, 50mm, and the maximum side distance of the hole diameter to the needle (2) is 3cm. The spinning speed of the injection pump is set to 50 ml / h. Under the propulsion of the injection pump (1), the core solution is pushed out at the needle tip and passes through the openings of three perforated insulating plates (5) in sequence, finally obtaining electrospun fibers with a diameter of 100-200 nm.

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