CN113913954B - A device and method for preparing ultrafine nanofibers based on solution atomization and electrostatic-airflow alternate drafting - Google Patents

Abstract

The invention discloses a device and a method for preparing superfine nano-fibers based on solution atomization and electrostatic-airflow take-over drafting. The method comprises the steps of firstly atomizing a spinning solution into ultra-fine liquid drops by using an atomization technology, then pre-drafting the atomized liquid drops into fine jet flows by using an electrostatic drafting technology, and finally drafting the pre-drafted jet flows into ultra-fine nano fibers by using an electric field attenuated by air flow instead. The invention adopts the spinning method that the spinning solution is atomized into super-micro liquid drops and then directly drafted to form the superfine nano fiber, changes the mode that the Taylor cone splits to form jet flow in the conventional electrostatic spinning, and provides a new mechanism for the formation of the electrostatic spinning nano fiber; meanwhile, the electrostatic-airflow take-over drafting can remarkably enhance the jet drafting force, so that the micro atomized liquid drops can be thinned to be below 100 nm. The extremely fine diameter of the nanofiber enables the nano effect to be more remarkable, and the nanofiber has more outstanding performance advantages when being applied to the fields of filtration, sensing and the like.

Description

A kind of ultra-fine nanofiber preparation based on solution atomization and electrostatic-airflow relay drafting device and method

technical field

The invention belongs to the field of textiles, and relates to a method for forming nanofibers, in particular to a device and method for preparing ultrafine nanofibers based on solution atomization and electrostatic-airflow alternate drafting, which are applied to fields such as filtration and sensing.

Background technique

As a class of fiber materials, nanofibers have broad application prospects in many fields such as filtration, biology, and sensing due to their advantages such as small diameter, large specific surface area, and high porosity. At present, the methods for preparing nanofibers mainly include self-assembly method, phase separation method, stretching method, template method and electrospinning method, etc., and electrospinning is considered to be the simplest and most effective method for industrialized preparation of nanofibers. The polymer solution/melt is drawn and thinned into nanofibers by electric field force. During the COVID-19 epidemic, many domestic companies such as Ju Nada, Jiangxi Xiancai, and Jiangsu Nafien have successfully developed electrospun nanofiber masks, protective clothing and other products, and their filtration efficiency is significantly better than that of meltblown fiber products, showing a huge market development potential.

Although electrospun nanofibers have good market prospects and application value, the current academic and commercial electrospun nanofibers refer to fibers with a diameter of less than 1 μm, and most electrospun nanofibers that can be stably applied directly They are all in the hundreds of nanometers, belonging to the submicron level. Existing studies have shown that ultra-fine nanofibers with a size below 100 nm have more significant nanoeffects, and can show more prominent performance advantages when used in filtration, sensing and other fields. Therefore, it is of great significance to develop a preparation method of ultra-fine nanofibers and give full play to the performance advantages endowed by nano-effects to fiber materials to enhance the competitiveness of my country's nanofibers in the international market.

Contents of the invention

Aiming at the market demands and technical bottlenecks of preparation of ultrafine nanofibers, the present invention proposes a preparation device and method for ultrafine nanofibers based on solution atomization and electrostatic-airflow alternate drafting. First, use the bubble atomization technology to atomize the spinning solution into super tiny droplets, then use the electrostatic drafting technology to pre-draw the atomized droplets into fine jets, and finally use the airflow to replace the attenuated electric field to finally draw the pre-drawn jets Stretched into extremely fine nanofibers. The excellent nano-effect of the ultra-fine nanofiber shows outstanding performance advantages in the fields of filtration and sensing, and has a good application prospect.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A spinning device for extremely fine nanofibers based on solution atomization and electrostatic-airflow alternate drafting, including a liquid supply device, a spinning unit, an air supply device, an air nozzle, a high-voltage generator, a receiving device, a negative pressure fan, Guide roller and winding device, the liquid supply device is connected with the spinning unit, the spinning unit has two, the two spinning units are placed horizontally opposite each other, and the spinning unit and the air nozzle are respectively connected with the air supply device; The positive and negative poles of the high-voltage generating device are respectively connected to the two spinning units; the air nozzle and the receiving device are respectively placed directly above and directly below the central axes of the two spinning units, and the receiving device is connected to a negative pressure fan.

Further, the distance between the two spinning units is 2-50 cm, the distance between the receiving device and the air nozzle is 20-100 cm, and the distance between the air nozzle and the horizontal line where the two spinning units are located is 1-10 cm.

Further, the spinning unit is composed of a liquid inlet, a liquid chamber, an air inlet, an air chamber and a spinning nozzle; the diameter of the air chamber is 2-10 cm, the diameter of the liquid chamber is 1-9 cm, and the diameter of the liquid chamber A certain number of round holes are opened on the wall along the circumferential direction, the diameter of the round holes is 0.1-5 mm, the hole spacing is 0.1-5 mm, and the diameter of the spinning nozzle is 0.1-9 mm.

Further, the air nozzle is a hollow circular tube with a shrinking and expanding structure, and the shrinking and expanding structure is composed of three stages, namely the entrance section, the middle section and the exit section, the diameter of the middle section is smaller than the entrance section and the exit section, and the diameter of the middle section is 1- 10 mm.

Further, the receiving device is a round tube with round holes on the surface, with a diameter of 1-1000 mm, the diameter of the round holes on the surface is 1-20 mm, and the hole spacing is 1-10 mm.

Further, the diameter of the guide roller is 1-1000 mm, and the diameter of the winding device is 1-1000 mm.

The device of the invention is used to prepare ultra-fine nanofibers based on solution atomization and electrostatic-airflow alternate drawing, which is formed by direct drawing of atomized liquid droplets. Specifically, the spinning solution is firstly atomized into ultra-small droplets by using the bubble atomization technology, and then the atomized droplets are pre-drawn into fine jets by using the electrostatic drafting technology, and finally the pre-drawn jet is taken over by the airflow to replace the attenuated electric field. Finally, it is drawn into extremely fine nanofibers.

The present invention is a method for preparing ultra-fine nanofibers based on solution atomization and electrostatic-airflow alternate drafting, which is prepared by the following steps:

(1) Dissolve any one or more polymers capable of electrospinning in a single or mixed organic solvent, and stir for several hours at a certain temperature to obtain a polymer with a mass fraction of 2%-30% spinning solution;

(2) The liquid supply device delivers the spinning solution to the liquid chamber of the spinning unit at a constant speed and quantitatively, and the gas supply device delivers the gas to the air chamber of the spinning unit according to a certain pressure, and the gas enters the liquid chamber through the round hole on the wall of the liquid chamber . The solution flow rate is 10-1000ml/h, and the gas pressure is 0.001-1 MPa. Gas and solution are mixed in the liquid chamber to form a gas-liquid mixture containing a large number of bubbles, and then flow out through the spinning nozzle under the push of the solution. After the gas-liquid mixture flows out of the spinning nozzle, due to the pressure difference between the inside and outside of the spinning nozzle, a large number of bubbles contained in the gas-liquid mixture burst, crushing the solution to atomize it to form a large number of tiny droplets;

(3) Turn on the high-voltage generating device, and apply positive and negative voltages to the two spinning units respectively, so that a conjugate electric field is formed between the two spinning units. Positive voltage is 0-50 kV and negative voltage is -50-0 kV. The ultra-many tiny droplets ejected from the two spinning units are respectively charged with positive and negative charges in the conjugate electric field, and at the same time are pre-drawn by the electric field force to form a fine jet, and move to the central axis of the two spinning units place. When the fine jets meet at the central axis, the charges are neutralized;

(4) The gas supply device delivers the gas to the gas nozzle at a constant speed and quantitatively, and enters from the inlet section and sprays out from the outlet section. After the transported gas passes through the three-stage structure change of the gas nozzle, the gas velocity is significantly increased, and the inlet gas velocity is greater than 5 m/s. The ejected high-speed gas meets the pre-drawn fine jets at the central axis of the two spinning units, attracting and driving these fine jets to move along the flow direction of the high-speed gas, and drawing and refining the fine jets into ultra-fine nanofibers, Fiber diameter less than 100 nm;

(5) Turn on the negative pressure fan to form negative pressure suction on the surface of the receiving device, so that the ultra-fine nanofibers formed in step (4) are deposited on the surface of the receiving device under the combined action of negative pressure suction and high-speed gas drafting force to form nano The fiber film is then conveyed to the winding device under the action of guide rollers to obtain continuous nanofiber packages. The flow rate of the negative pressure fan is greater than 1000ml/h. The speed of the receiving device is greater than 0.1 m/h, the speed of the guide roller is greater than 0.1 m/h, and the speed of the winding device is greater than 0.1 m/h.

Beneficial effects of the present invention: the present invention adopts the spinning method in which the spinning solution is first atomized into ultra-many tiny liquid droplets, and then directly drawn to form ultra-fine nanofibers, which changes the conventional electrospinning process of forming jets by Taylor cone splitting. This method provides a new mechanism for the formation of electrospun nanofibers; at the same time, the electrostatic-airflow relay drafting can significantly enhance the jet drafting force, so that the tiny atomized droplets can be refined to below 100 nm, which is very promising for the development of nanofibers. Fine nanofiber preparation technology provides reliable theoretical guidance and technical support. The ultra-fine diameter of the nanofiber makes the nano-effect more significant, and it has more outstanding performance advantages in the fields of filtration and sensing.

Description of drawings

Figure 1 is a schematic diagram of a very fine nanofiber forming device based on solution atomization and electrostatic-airflow alternate drafting;

Fig. 2 is the structural representation of spinning unit;

Fig. 3 is a schematic diagram of the gas nozzle structure;

Figure 4 is an electron micrograph of ultrafine polyacrylonitrile nanofibers.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments. It should be understood that the following examples are only used to illustrate the present invention rather than limit the scope of the present invention, and those skilled in the art can make some non-essential improvements and adjustments based on the content of the above invention.

Example 1

As shown in Figure 1, a spinning device of the present embodiment based on solution atomization and electrostatic-air flow to take over the drafted ultra-fine nanofibers includes a liquid supply device 1, a spinning unit 2, an air supply device 3, an air Nozzle 4, high pressure generating device 5, receiving device 6, negative pressure fan 7, guide roller 8 and winding device 9, the liquid supply device 1 is connected with the spinning unit 2, and the spinning unit 2 has two, two Two spinning units 2 are horizontally placed opposite each other with a distance of 2-50 cm. The spinning unit 2 and the air nozzle 4 are connected to the air supply device 3 respectively; connected; the air nozzle 4 and the receiving device 6 are placed directly above and directly below the central axis of the two spinning units 2, the distance between the receiving device 6 and the air nozzle 4 is 20-100 cm, and the air nozzle 4 and the The horizontal distance between the two spinning units 2 is 1-10 cm, and the receiving device 6 is connected with a negative pressure fan 7 .

As shown in Figure 2, the spinning unit 2 is composed of a liquid inlet 14, a liquid chamber 15, an air inlet 16, an air chamber 17 and a spinning nozzle 20; the diameter of the air chamber 17 is 2-10 cm, and the The liquid chamber 15 has a diameter of 1-9 cm, and the wall of the liquid chamber 15 has a certain number of round holes 18 along the circumferential direction. The diameter of the round holes 18 is 0.1-5 mm, and the hole spacing is 0.1-5 mm. The diameter of the spinning nozzle 20 is 0.1-9mm.

As shown in Figure 3, the air nozzle 4 is a hollow circular tube with a shrinking and expanding structure, and the shrinking and expanding structure is composed of three stages, which are respectively an inlet section 21, a middle section 22 and an outlet section 23, and the diameter of the middle section 22 is smaller than that of the entrance section. 21 and outlet section 23, middle section 22 diameter 1-10 mm.

The receiving device 6 is a round tube with round holes on the surface, with a diameter of 1-1000 mm, the diameter of the round holes on the surface is 1-20 mm, and the hole spacing is 1-10 mm. The diameter of the guide roller 8 is 1-1000 mm. The winding device 9 has a diameter of 1-1000 mm.

Example 2

The preparation steps of ultra-fine nanofibers based on solution atomization and electrostatic-airflow relay drafting in this embodiment are as follows:

(1) Dissolve polyacrylonitrile (PAN) powder in N,N dimethylformamide solvent and stir at 80°C for 6 hours to obtain a PAN spinning solution with a mass fraction of 4%;

(2) The liquid supply device 1 delivers the PAN spinning solution to the liquid chamber 15 of the spinning unit 2 at a constant speed and quantitatively, and the solution flow rate is 300 ml/h. The gas supply device 3 delivers the gas to the air chamber 17 of the spinning unit 2 according to a certain pressure, and the gas enters the liquid chamber through the round hole 18 on the wall of the liquid chamber 15, and the gas pressure is 0.3 MPa. The gas and the PAN spinning solution are mixed in the liquid chamber to form a gas-liquid mixture 19 containing a large number of bubbles, and then flow out through the spinning nozzle 20 under the push of the PAN spinning solution. After the gas-liquid mixture flows out of the spinning nozzle, due to the pressure difference between the inside and outside of the spinning nozzle, a large number of bubbles contained in the gas-liquid mixture burst, crushing the solution and atomizing it to form super many tiny droplets10.

(3) Turn on the high-voltage generating device 5, and apply positive and negative voltages to the two spinning units respectively, so that a conjugate electric field is formed between the two spinning units. Positive voltage is 35 kV and negative voltage is -35 kV. The ultra-many tiny droplets ejected from the two spinning units are respectively charged with positive and negative charges in the conjugate electric field, and at the same time are pre-drawn by the electric field force to form a fine jet 11, and move to the center of the two spinning units axis. When the fine jets meet at the central axis, the charges are neutralized.

(4) The gas supply device 3 delivers the gas to the gas nozzle 4 at a constant speed and quantitatively, and enters from the inlet section and sprays out from the outlet section. After the transported gas passes through the three-stage structure change of the gas nozzle, the gas velocity is significantly increased, and the inlet gas velocity is 100 m/s. The ejected high-speed gas meets the pre-drawn fine jets at the central axis of the two spinning units, attracting and driving these fine jets to move along the flow direction of the high-speed gas, and drawing and refining the fine jets into ultra-fine nanofibers 12 .

(5) Turn on the negative pressure fan 7 to form negative pressure suction on the surface of the receiving device, so that the ultrafine nanofibers 12 formed in step (4) are deposited on the surface of the receiving device under the combined action of negative pressure suction and high-speed gas drafting force, The nanofiber film 13 is formed, and then transported to the winding device 9 under the action of the guide roller 8 to obtain a continuous package. Negative pressure fan flow rate 3000 ml/h. The speed of the receiving device is 2 m/h, the speed of the guide roller is 2 m/h, and the speed of the winding device is 2 m/h.

Example 3

The preparation steps of ultra-fine nanofibers based on solution atomization and electrostatic-airflow relay drafting in this embodiment are as follows:

(1) Dissolve polyacrylonitrile (PAN) powder in N,N dimethylformamide solvent and stir at 80°C for 6 hours to obtain a PAN spinning solution with a mass fraction of 12%;

(2) The liquid supply device transports the PAN spinning solution to the liquid chamber of the spinning unit at a constant speed and quantitatively, and the solution flow rate is 300ml/h. The gas supply device delivers the gas to the air chamber of the spinning unit according to a certain pressure, and the gas enters the liquid chamber through the round hole on the wall of the liquid chamber, and the gas pressure is 0.3 MPa. The gas and the PAN spinning solution are mixed in the liquid chamber to form a gas-liquid mixture containing a large number of bubbles, and then flow out through the spinning nozzle under the push of the PAN spinning solution. After the gas-liquid mixture flows out of the spinning nozzle, due to the pressure difference between the inside and outside of the spinning nozzle, a large number of bubbles contained in the gas-liquid mixture burst, crushing the solution and atomizing it to form super many tiny droplets.

(3) Turn on the high-voltage generating device, and apply positive and negative voltages to the two spinning units respectively, so that a conjugate electric field is formed between the two spinning units. Positive voltage is 35 kV and negative voltage is -35 kV. The ultra-many tiny droplets ejected from the two spinning units are respectively charged with positive and negative charges in the conjugate electric field, and at the same time are pre-drawn by the electric field force to form a fine jet, and move to the central axis of the two spinning units place. When the fine jets meet at the central axis, the charges are neutralized.

(4) The gas supply device delivers the gas to the gas nozzle at a constant speed and quantitatively, and enters from the inlet section and sprays out from the outlet section. After the transported gas passes through the three-stage structure change of the gas nozzle, the gas velocity is significantly increased, and the inlet gas velocity is 100 m/s. The ejected high-speed gas meets the pre-drawn fine jets at the central axis of the two spinning units, attracting and driving these fine jets to move along the flow direction of the high-speed gas, and drawing and refining the fine jets into ultra-fine nanofibers.

(5) Turn on the negative pressure fan to form negative pressure suction on the surface of the receiving device, so that the ultra-fine nanofibers formed in step (4) are deposited on the surface of the receiving device under the combined action of negative pressure suction and high-speed gas drafting force to form nano The fiber film is then conveyed to the winding device under the action of guide rollers to obtain continuous packages. Negative pressure fan flow rate 3000 ml/h. The speed of the receiving device is 2 m/h, the speed of the guide roller is 2 m/h, and the speed of the winding device is 2 m/h.

Example 4

The preparation steps of ultra-fine nanofibers based on solution atomization and electrostatic-airflow relay drafting in this embodiment are as follows:

(1) Dissolve polyacrylonitrile (PAN) powder in N,N dimethylformamide solvent and stir at 80°C for 6 hours to obtain a PAN spinning solution with a mass fraction of 8%;

(2) The liquid supply device transports the PAN spinning solution to the liquid chamber of the spinning unit at a constant speed and quantitatively, and the solution flow rate is 300ml/h. The gas supply device delivers the gas to the air chamber of the spinning unit according to a certain pressure, and the gas enters the liquid chamber through the round hole on the wall of the liquid chamber, and the gas pressure is 0.5 MPa. The gas and the PAN spinning solution are mixed in the liquid chamber to form a gas-liquid mixture containing a large number of bubbles, and then flow out through the spinning nozzle under the push of the PAN spinning solution. After the gas-liquid mixture flows out of the spinning nozzle, due to the pressure difference between the inside and outside of the spinning nozzle, a large number of bubbles contained in the gas-liquid mixture burst, crushing the solution and atomizing it to form super many tiny droplets.

(3) Turn on the high-voltage generating device, and apply positive and negative voltages to the two spinning units respectively, so that a conjugate electric field is formed between the two spinning units. Positive voltage is 35 kV and negative voltage is -35 kV. The ultra-many tiny droplets ejected from the two spinning units are respectively charged with positive and negative charges in the conjugate electric field, and at the same time are pre-drawn by the electric field force to form a fine jet, and move to the central axis of the two spinning units place. When the fine jets meet at the central axis, the charges are neutralized.

(4) The gas supply device delivers the gas to the gas nozzle at a constant speed and quantitatively, and enters from the inlet section and sprays out from the outlet section. After the transported gas passes through the three-stage structure change of the gas nozzle, the gas velocity is significantly increased, and the inlet gas velocity is 150 m/s. The ejected high-speed gas meets the pre-drawn fine jets at the central axis of the two spinning units, attracting and driving these fine jets to move along the flow direction of the high-speed gas, and drawing and refining the fine jets into ultra-fine nanofibers.

(5) Turn on the negative pressure fan to form negative pressure suction on the surface of the receiving device, so that the ultra-fine nanofibers formed in step (4) are deposited on the surface of the receiving device under the combined action of negative pressure suction and high-speed gas drafting force to form nano The fiber film is then conveyed to the winding device under the action of guide rollers to obtain continuous packages. Negative pressure fan flow rate 3000 ml/h. The speed of the receiving device is 2 m/h, the speed of the guide roller is 2 m/h, and the speed of the winding device is 2 m/h.

Example 5

The preparation steps of ultra-fine nanofibers based on solution atomization and electrostatic-airflow relay drafting in this embodiment are as follows:

(1) Dissolve polyamide (PA) powder in formic acid solvent and stir at 60°C for 6 h to obtain a PA spinning solution with a mass fraction of 8%;

(2) The liquid supply device transports the PA spinning solution to the liquid chamber of the spinning unit at a constant speed and quantitatively, and the solution flow rate is 200 ml/h. The gas supply device delivers the gas to the air chamber of the spinning unit according to a certain pressure, and the gas enters the liquid chamber through the round hole on the wall of the liquid chamber, and the gas pressure is 0.3 MPa. The gas and the PA spinning solution are mixed in the liquid chamber to form a gas-liquid mixture containing a large number of bubbles, and then flow out through the spinning nozzle under the promotion of the PA spinning solution. After the gas-liquid mixture flows out of the spinning nozzle, due to the pressure difference between the inside and outside of the spinning nozzle, a large number of bubbles contained in the gas-liquid mixture burst, crushing the solution and atomizing it to form super many tiny droplets.

(3) Turn on the high-voltage generating device, and apply positive and negative voltages to the two spinning units respectively, so that a conjugate electric field is formed between the two spinning units. Positive voltage is 20 kV and negative voltage is -20 kV. The ultra-many tiny droplets ejected from the two spinning units are respectively charged with positive and negative charges in the conjugate electric field, and at the same time are pre-drawn by the electric field force to form a fine jet, and move to the central axis of the two spinning units place. When the fine jets meet at the central axis, the charges are neutralized.

(4) The gas supply device delivers the gas to the gas nozzle at a constant speed and quantitatively, and enters from the inlet section and sprays out from the outlet section. After the transported gas passes through the three-stage structure change of the gas nozzle, the gas velocity is significantly increased, and the inlet gas velocity is 100 m/s. The ejected high-speed gas meets the pre-drawn fine jets at the central axis of the two spinning units, attracting and driving these fine jets to move along the flow direction of the high-speed gas, and drawing and refining the fine jets into ultra-fine nanofibers.

(5) Turn on the negative pressure fan to form negative pressure suction on the surface of the receiving device, so that the ultra-fine nanofibers formed in step (4) are deposited on the surface of the receiving device under the combined action of negative pressure suction and high-speed gas drafting force to form nano The fiber film is then conveyed to the winding device under the action of guide rollers to obtain continuous packages. Negative pressure fan flow rate 3000 ml/h. The speed of the receiving device is 1 m/h, the speed of the guide roller is 1 m/h, and the speed of the winding device is 1 m/h.

In the present invention, the spinning solution is firstly atomized into ultra-many tiny droplets by atomization technology, and then the atomized droplets are pre-drawn into fine jets by electrostatic drafting technology, and finally the pre-drawn jets are drawn by the airflow to replace the attenuated electric field. Stretched into extremely fine nanofibers. The present invention adopts the spinning method of first atomizing the spinning solution into ultra-small liquid droplets, and then directly stretching to form ultra-fine nanofibers, which changes the way of jet flow formed by Taylor cone splitting in conventional electrospinning, and is an electrospinning nanofiber. Fiber forming provides a new mechanism; at the same time, the electrostatic-airflow relay drafting can significantly enhance the jet drafting force, so that the tiny atomized droplets can be refined to less than 100 nm, and the extremely fine diameter of the nanofiber makes it The nano effect is more significant, and it has more outstanding performance advantages in the fields of filtration and sensing.

The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments. What are described in the above-mentioned embodiments and the description only illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have Variations and improvements all fall within the scope of the claimed invention. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (6)

1. A spinning device for ultra-fine nanofibers based on solution atomization and electrostatic-airflow relay drafting, characterized in that it includes a liquid supply device (1), a spinning unit (2), and an air supply device (3) , air nozzle (4), high pressure generating device (5), receiving device (6), negative pressure fan (7), guide roller (8) and winding device (9), the liquid supply device (1) and spinning There are two spinning units (2), and the two spinning units (2) are placed horizontally opposite each other. The spinning unit (2) and the air nozzle (4) are respectively connected with the air supply device ( 3) are connected; the positive and negative poles of the high-voltage generating device (5) are respectively connected to the two spinning units (2); the gas nozzle (4) and the receiving device (6) are respectively placed in the two spinning units ( 2) Directly above and directly below the central axis, the receiving device (6) is connected to a negative pressure fan (7); The distance between the two spinning units (2) is 2-50 cm, the distance between the receiving device (6) and the air nozzle (4) is 20-100 cm, the distance between the air nozzle (4) and the two spinning units (2) The distance between the horizontal lines is 1-10 cm; The air nozzle (4) is a hollow circular tube with a shrinking and expanding structure, and the shrinking and expanding structure consists of three stages, namely the inlet section (21), the middle section (22) and the outlet section (23), the middle section (22) The diameter is smaller than the inlet section (21) and the outlet section (23), and the diameter of the middle section (22) is 1-10 mm; The spinning unit (2) is composed of a liquid inlet (14), a liquid chamber (15), an air inlet (16), an air chamber (17) and a spinning nozzle (20); the air chamber (17) 2-10 cm in diameter, the liquid chamber (15) has a diameter of 1-9 cm, and a certain number of round holes (18) are opened on the wall of the liquid chamber (15) along the circumferential direction, and the diameter of the round holes (18) is 0.1-5 cm mm, the hole spacing is 0.1-5 mm, and the diameter of the spinning nozzle (20) is 0.1-9 mm; Positive and negative voltages are applied to the two spinning units respectively, so that a conjugate electric field is formed between the two spinning units, and the super many tiny droplets ejected from the two spinning units are respectively positively charged in the conjugate electric field and negative charges, at the same time, it is pre-drawn by the electric field force to form a fine jet, and moves to the central axis of the two spinning units. When the fine jet meets the central axis, the charge is neutralized, and then the air supply device is uniformly and quantitatively The gas is transported to the gas nozzle, enters from the inlet section and is ejected from the outlet section. The ejected high-speed gas meets the pre-drawn fine jets at the central axis of the two spinning units, attracting and driving these fine jets along the direction of the high-speed gas. The flow direction moves, and the fine jet is drawn and refined into extremely fine nanofibers. 2. The spinning device according to claim 1, characterized in that: the receiving device (6) is a round tube with round holes on the surface, the diameter is 1-1000 mm, the diameter of the round holes on the surface is 1-20 mm, and the hole spacing is 1-10mm. 3. The spinning device according to claim 1, characterized in that: the guide roller (8) has a diameter of 1-1000 mm, and the winding device (9) has a diameter of 1-1000 mm. 4. Utilize the spinning device described in any one of claims 1-3 to prepare the method based on solution atomization and electrostatic-air flow to take over the extremely fine nanofiber of drafting, it is characterized in that: first utilize bubble atomization technology to spin solution Atomize into ultra-small droplets, then use electrostatic drawing technology to pre-draw the atomized droplets into fine jets, and finally use airflow to replace the attenuated electric field to finally draw the pre-drawn jets into ultra-fine nanofibers. 5. the preparation method of ultrafine nanofiber according to claim 4 is characterized in that adopting the following steps to carry out: (1) Dissolving any one or more polymers capable of electrospinning in a single or mixed organic solvent to obtain a polymer spinning solution with a mass fraction of 2%-30%; (2) The liquid supply device delivers the spinning solution to the liquid chamber of the spinning unit at a constant speed and quantitatively, and the gas supply device delivers the gas to the air chamber of the spinning unit. The gas enters the liquid chamber through the round hole on the wall of the liquid chamber, and the solution flow rate 10-1000 ml/h, gas pressure 0.001-1 MPa; gas and solution are mixed in the liquid chamber to form a gas-liquid mixture (19) containing a large number of bubbles, and then flow out through the spinning nozzle under the push of the solution; the gas-liquid mixture flows out After the spinning nozzle, due to the pressure difference between the inside and outside of the spinning nozzle, a large number of bubbles contained in the gas-liquid mixture burst, crushing the solution to atomize it to form a large number of tiny droplets (10); (3) Turn on the high-voltage generating device, and the two spinning units are respectively applied with positive and negative voltages to form a conjugate electric field between the two spinning units. The positive voltage is 0-50 kV, and the negative voltage is -50-0 kV. , the ultra-many tiny droplets ejected from the two spinning units are respectively charged with positive and negative charges in the conjugate electric field, and at the same time are pre-drawn by the electric field force to form a fine jet (11), and move to the two spinning units. At the central axis of the unit; when the fine jets meet at the central axis, the charges are neutralized; (4) The gas supply device transports the gas to the gas nozzle at a constant speed and quantitatively, enters from the inlet section and sprays out from the outlet section. After the gas delivered passes through the three-stage structure change of the gas nozzle, the gas velocity is significantly increased, and the inlet gas velocity is greater than 5 m/s, the ejected high-speed gas meets the pre-drawn fine jets at the central axis of the two spinning units, attracting and driving these fine jets to move along the flow direction of the high-speed gas, and drawing the fine jets into extremely thin Fine nanofibers (12), very fine nanofibers (12) having a diameter of less than 100 nm; (5) Turn on the negative pressure fan to form negative pressure suction on the surface of the receiving device, so that the ultra-fine nanofibers formed in step (4) are deposited on the surface of the receiving device under the combined action of negative pressure suction and high-speed gas drafting force to form nano The fiber film (13) is then transported to a winding device under the action of guide rollers to obtain continuous nanofiber packages. 6. The preparation method of ultra-fine nanofibers according to claim 5, characterized in that: in the step (5), the flow rate of the negative pressure fan is greater than 1000 ml/h, the speed of the receiving device is greater than 0.1 m/h, and the speed of the guide roller is Greater than 0.1 m/h, the speed of the winding device is greater than 0.1 m/h.

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