CN109097849B

CN109097849B - Nanofiber generating device

Info

Publication number: CN109097849B
Application number: CN201811143049.7A
Authority: CN
Inventors: 林童; 牛海涛; 颜贵龙
Original assignee: Shanghai Yuntong New Material Technology Co Ltd
Current assignee: Shanghai Yuntong New Material Technology Co., Ltd
Priority date: 2018-09-28
Filing date: 2018-09-28
Publication date: 2021-05-04
Anticipated expiration: 2038-09-28
Also published as: CN109097849A

Abstract

The invention discloses a nanofiber generating device, comprising: the rotatable spinning solution storage device is provided with at least one spinning channel for guiding the spinning solution stored in the internal liquid storage cavity to the outside; a fiber collection device; the airflow generating device guides the high-speed airflow to the outlet of the spinning channel and transfers the spinning liquid jet flow flowing out of the outlet or spinning formed by the spinning liquid jet flow to the fiber collecting device in an auxiliary manner; the internal electrode is arranged in the liquid storage cavity and is in contact with the spinning solution, the external electrode is arranged outside the spinning solution storage device, and a potential difference is formed between the internal electrode and the external electrode; the internal electrode and the external electrode rotate synchronously with the spinning solution storage device.

Description

Nanofiber generating device

Technical Field

The invention relates to a novel nanofiber generating device.

Background

Electrospun nanofibers have diameters predominantly between 50-1000nm, continuous lengths and large specific surface area to volume ratios. The non-woven fabric formed by the electrostatic spinning nano-fibers has the advantages of large specific surface area, high porosity, small pore diameter, good permeability and the like, and has wide application prospect in various fields of biological medical treatment, environment, energy, chemical industry, clothing, materials and the like.

The traditional electrostatic spinning technology mainly uses hollow needles as spinning nozzles, the spinning capacity is very limited, each spinning needle can only produce one polymer spinning, and the amount of fibers produced by each needle per hour is less than 0.3 g. Such low nanofiber production efficiency greatly limits the industrial application of the conventional electrospinning technique. In order to improve the electrostatic spinning yield, a needleless spinning nozzle design is mostly adopted in the high-efficiency electrostatic spinning technology. Formhals (US1975504) used a serrated rotating wheel as a nanofiber generator, prepared cellulose fibers and cellulose acetate fibers, and designed a collection device for dry and wet spinning. Lucas et al (WO2005024101) use a conductive cylinder as the fiber generator, in which a portion of the conductive cylinder is immersed in a viscous liquid polymer, and the cylinder is rotated to cover the viscous liquid and enter an electric field, when the electric field is strong enough, the liquid on the surface of the cylinder forms a taylor cone and generates a large number of solution jets, and finally nanofibers are obtained on a collector. Lin et al (WO2010043002) disclose a needle-free electrospinning apparatus comprising a helical spinning electrode (or spinneret) partially submerged in a polymer solution container, with a counter electrode on a collector at a distance from the helical electrode. The polymer solution in the container forms a layer of film on the surface of the spiral structure, and enters an electric field between the spinning electrode and the receiving electrode. When the electrostatic field between the electrodes is strong enough to pull the solution into the taylor cone, nanofibers form on the surface of the helix. Other needleless spinning nozzles comprise a deformed round through nozzle (WO2006131081), a metal wire (WO2011015161), a thin plate (WO2006131081), a screw (CN103774250), a step (CN 103572388) and the like which are provided with small curvature radius for spinning, so that the electric field intensity can be obviously increased, and the fiber yield can be improved.

On the other hand, centrifugal spinning is a spinning process that relies on the centrifugal force generated by a rotating spinning head to shear a polymer solution/melt to form fibers, as it was first presented in US patent (US 3358323). Centrifugal spinning is a new way for preparing nano fibers, and various different centrifugal spinning technologies appear through development, such as preparing core-shell structure composite nano-micro fibers (CN104928774B) by using a centrifugal electrostatic spinning process; the centrifugal spinning process produces the nano-fiber and directly collects the nano-fiber into twisted yarn (CN 105386167B); the melt jet is drawn twice under the action of inertial force and high-speed airflow by using an airflow-assisted melt centrifugal spinning device (CN 104674360B).

Furthermore, the combination of electrostatic spinning and centrifugal spinning is an important way for improving the production capacity of the nano-fiber. Centrifugal electrostatic spinning refers to the process of forming fibers under the combined action of centrifugal force and high-voltage electrostatic force. Centrifugal force enhances jet flow and fiber drafting in the spinning process, and the high-speed movement along the circumference accelerates the volatilization of the solvent in the fibers. The centrifugal electrostatic spinning technology combines the advantages of a centrifugal spinning process and an electrostatic spinning process, and has the advantages of uniform fiber, small diameter, high yield and the like. Chinese patent CN104328514B discloses a technique for preparing nanofibers with higher performance and higher quality more stably by using jet flow without disturbance in vacuum environment of a vacuum centrifugal electrostatic spinning device. CN105755557B discloses a magnetic suspension type centrifugal electrostatic spinning device, which can overcome the dependence of centrifugal spinning on the motor, simplify the spinning device and make the operation simpler. CN105568403B discloses a centrifugal electrostatic spinning device with a rotary air suction device, in which a fan is disposed at the top of a centrifugal nozzle, the fan can rotate synchronously with the centrifugal nozzle, and blows external air into a liquid storage cavity to generate an air flow blown to a receiving device from a filament outlet pore. The formation and further stretching of the auxiliary spinning jet flow form the nanofibers which are collected by a collecting device.

In the prior art, the production speed of the nano-fiber and the adjustment capability of the nano-fiber to the fineness of the fiber are low, and the requirement of the fiber produced in the production process on a deposited base material is high.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a spinning fiber with large, fine and uniform yield and greatly improved fiber diameter adjusting range; in the continuous spinning, a special collecting device is not needed, and the fibers can be directionally deposited to a nanofiber generating device on any surface.

The technical problem to be solved can be implemented by the following technical scheme.

A nanofiber generating device comprising:

the rotatable spinning solution storage device is provided with at least one spinning channel for guiding the spinning solution stored in the internal liquid storage cavity to the outside;

a fiber collection device;

the airflow generating device guides the high-speed airflow to the outlet of the spinning channel and transfers the spinning liquid jet flow flowing out of the outlet or spinning formed by the spinning liquid jet flow to the fiber collecting device in an auxiliary manner; and

the spinning solution storage device comprises an internal electrode and an external electrode, wherein the internal electrode is arranged in a liquid storage cavity and is in contact with spinning solution, the external electrode is arranged outside the spinning solution storage device, and a potential difference is formed between the internal electrode and the external electrode; the internal electrode and the external electrode rotate synchronously with the spinning solution storage device.

As a further improvement of the technical scheme, the internal electrode is a high-voltage positive electrode, and the external electrode is a negative electrode; or, the built-in electrode is a high-voltage end electrode, and the external electrode is a counter electrode.

Also as a further improvement of the technical scheme, the internal electrode is connected with the output end of an external high voltage generator through a spinning channel, the external electrode is a grounding electrode, and the external electrode is fixed on the external surface of the spinning solution storage device through an insulator.

As a further improvement of the technical scheme, the rotating speed of the spinning solution storage device is 1000-6000 rpm.

As a further improvement of the technical scheme, the voltage range of the high-voltage electric field formed between the spinning solution and the external electrodes is 5-40 KV.

Furthermore, the high voltage generator is a high voltage electrostatic direct current generator or a high voltage alternating current electrostatic generator.

As a preferred embodiment of the invention, the external electrodes are positioned in front of the corresponding spinning channels along the rotation direction of the spinning solution storage device.

Preferably, the number of the spinning channels is even.

As a further improvement of the technical scheme, the spinning solution storage device comprises a liquid storage tank, wherein the liquid storage tank is provided with a shielding part for preventing the spinning solution from being thrown out along other channels or outlets outside the spinning channel; the outlet of the spinning channel is in a hole shape or a slit shape.

Preferably, the tank body of the liquid storage tank is in an axisymmetric structure or a central symmetric structure.

Wherein, the liquid storage tank is cylindrical; the outer diameter of the needle-shaped part excluding the filament outlet is 20-1000 mm; the axial thickness of the liquid storage tank is 10-500 mm.

As another preferred embodiment of the invention, the outlet of the spinning channel is in the shape of a slit, the length direction of the slit forms an included angle of 0-70 degrees with the rotating shaft, the length of the slit along the rotating shaft direction is less than the external thickness of the liquid storage tank, and the width of the slit is 0.1-5 mm.

Also as a preferred form of the present invention, when the outlet of the spinning channel is in a hole shape, the top end of the external electrode is a pointed end; when the outlet of the spinning channel is in a slit shape, the external electrode is in a slender structure.

As another preferred embodiment of the invention, the external electrodes and the corresponding spinning channels are in the same plane.

As another preferred embodiment of the invention, the external electrodes and the corresponding spinning channels are in different planes, and the included angle formed by the projection of the external electrodes and the corresponding spinning channels on the vertical plane of the rotating shaft is 0-90 degrees.

Wherein, when the outlet of the spinning channel is in a slit shape, the distance between the slit spinning hole and the counter electrode is 5mm-100 mm.

As a further improvement of the technical solution, the device comprises more than one spinning channel, the internal electrode is connected with the output end of an external high voltage generator through the more than one spinning channel, and each spinning channel corresponds to one external electrode.

Also as a further improvement of the present invention, the apparatus may provide an air flow generating means for interfering with an air flow in the fiber deposition direction from the spinning solution storage means to the fiber collecting means at an air flow rate of 0.1 to 5 m/s.

Wherein the gas of the gas flow is air, nitrogen, carbon dioxide or argon.

In addition, the spinning solution is a viscous liquid with the viscosity of 1-100000mPa s.

Further, the viscous liquid is selected from a solution of a polymer, a sol-gel solution or a suspension of particles.

Still further, the spinning dope is a molten polymer solution comprising at least one polymer and at least one volatile solvent.

The nano-generator adopting the technical scheme has the following characteristics:

1. the spinning process is completed under the combined action of three force fields of electrostatic force, centrifugal force and airflow, wherein any one force field is independently used;

for example, if only the liquid tank is rotated without adding high-voltage electrostatic field and air flow in the spinning process, the spinning liquid can be only drawn into thicker micro fibers or uniform nano fiber products cannot be formed because the generated centrifugal force is small; if only a high voltage electrostatic field is used, the solution does not flow to the outside of the fine holes or slits, and thus spinning cannot be formed. The fluid cannot be processed into fibers using the air flow effect alone. Likewise, the combination of the two force fields does not allow for mass production and directional deposition of nanofibers. When the three force fields act together, the nano-fiber can be effectively prepared, the yield is high, the nano-fiber is fine and uniform, and the adjustment range of the fiber diameter is greatly improved; in continuous spinning, the fibers can be directionally deposited on any surface without a special collecting device.

2. The generating device does not need an external collecting electrode, can deposit the generated fibers on the surface of any material in real time, and is not influenced by the conductivity of the material.

Compared with the prior nanofiber generator, the generating device has obvious differences in design principle, filamentation process and fiber collection mode, and is characterized in that:

1. the electric field force is generated by two electrodes rotating synchronously, and because the distance between the two high-voltage electrodes is far smaller than the conventional electrostatic spinning distance, the two high-voltage electrodes can generate a higher-strength electric field under the condition of lower voltage to draft the solution jet;

2. the centrifugal force increases the drafting of the solution jet flow in the normal direction, so that the formed fiber is thinner and more uniform;

3. the airflow is generated from the high-speed rotation of the liquid tank, and the generated airflow field not only increases the drafting in the normal direction, but also effectively prevents the deposition of the fibers on the counter electrode, and simultaneously guides the formed fibers to move to the collector;

4. the collection device need not be in electrical association with the fiber generation device, and may be an insulator or conductor, and neither shape nor distance affects fiber formation and collection.

Drawings

FIG. 1 is a schematic diagram of the structure and operation of the nanofiber generating device of the present invention.

FIG. 2 is a schematic structural view of a pinhole type disk fiber generator;

FIG. 3 is a cross-sectional view of a pinhole type disk fiber generator.

Fig. 4 is a schematic structural view of a slit-type disk fiber generator.

FIG. 5 is a schematic diagram of a rod-shaped fiber generator.

Fig. 6 is a schematic structural diagram of a symmetrical nanofiber generator.

Fig. 7 is a scanning electron microscope image of nanofibers.

FIG. 8 is a schematic diagram of a nanofiber generating device of the present invention; wherein figure 8a illustrates a front view angle of the receiver and the fluid bath and figure 8b illustrates a top view angle of the fluid bath.

FIG. 9 is a schematic view of a conventional centrifugal electrospinning principle; wherein figure 9a illustrates a front view angle of the receiver and the fluid bath and figure 9b illustrates a top view angle of the fluid bath.

In the figure: 1-high speed motor 2-airflow 3-spinning head 4-grounding electrode 5-fiber 6-DC high voltage power supply 7-step 8 on upper part of liquid tank-liquid tank 81-inner container 82-steps 10, 12-spinning head 11-grounding electrode 13, 14-liquid tank

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

The invention provides a novel nanofiber generating device, which is used for processing viscous fluid into nanofibers by combining the synergistic effect of three force fields of electrostatic force, centrifugal force and airflow. The centrifugal force generated when the liquid tank rotates enables the solution in the liquid tank to be extruded out of the spinneret orifice; the extruded solution is drawn into nano-fibers under the combined action of an external electric field and centrifugal force; the nanofibers are moved downward by the gas stream and collected on a collection device.

Specifically, as shown in fig. 1, the nanofiber generator according to the present invention comprises a rotatable liquid tank 8, a pair of electrodes consisting of a high voltage electrode (the output end of an external high voltage generator is connected to the inside of the liquid tank through a spinning head 3) and a counter electrode (a grounding electrode 4), a set of rotary power driving device (comprising a high speed motor 1, a controller, a connecting accessory, etc.), and a high speed air flow source (air flow 2).

The inside of the liquid tank 8 is of a hollow structure and is used for storing spinning liquid. The inner container of the liquid tank is communicated with the outer surface through a fine hole or a slit (see the different embodiments provided in fig. 2 to 4 at the same time), so that the spinning liquid can be conveyed to the outer surface through the fine hole (slit). The high-voltage electrode and the counter electrode are both arranged on the rotary liquid tank, one of the high-voltage electrode and the counter electrode is arranged inside the liquid tank and connected with the spinning solution to play a role in polarizing the spinning solution, and the other electrode is arranged outside the liquid tank and synchronously rotates with the liquid tank in the spinning process.

During spinning, the spinning solution in the liquid tank reaches the outlet of the spinning head 3 through the fine hole (or slit) by the centrifugal force of the rotation of the liquid tank, and forms a jet flow (fiber 5). The jet is charged due to the polarization of the internal high voltage electrode and is attracted by the external electrode (i.e., the ground electrode 4); under the action of the electric field force, the jet flow migrates to an external electrode; however, due to the action of the gas flow 2, the jet is re-routed before reaching the external electrode, leaves the rotating spinning generator, and is deposited onto an external collector, guided by the gas flow 2, forming solid nanofibres. The high-speed airflow source is used as an external auxiliary device, and can obtain required high-speed airflow by utilizing a pipeline, a fan and the like to assist and transfer the fibers 5 produced by jet flow to a fiber collecting device.

The shape of the liquid bath 8 may be a disc, sphere or cylinder equiaxed or centrosymmetric structure. The liquid tank is provided with an inner container, the inner container is communicated with the outer surface through a pore or a slit, so that the spinning solution can be conveyed to the outer surface through the pore (slit). Through the shape control of the liquid tank, two functions can be played: 1) changing the flow direction, the speed and the distribution of the self-generated gas flow, thereby changing the involved path and the migration direction of the nano-fiber; 2) and adjusting the yield: the effective spinning area is adjusted by changing the shape, thereby adjusting the fiber production rate. The rotating diameter of the liquid tank is 20mm to 1000 mm; the axial thickness is from 10mm to 500mm (the diameter and thickness here refer to the diameter and height of the cylindrical profile of the tank). Wherein the axial thickness is preferably 1/2 of the diameter of revolution. The larger the axial thickness, the larger the corresponding rotating diameter, and the larger the axial thickness, the more the contained spinning solution. The liquid bath is integrally rotated. The rotating diameter directly determines the centrifugal force, the larger the diameter is, the larger the centrifugal force is, the more easily the solution is extruded from the spinning head to form a solution jet. At the same rotational speed, the larger the rotational diameter, the finer the fibers produced.

The liquid tank 8 is made of high-insulation materials, polytetrafluoroethylene, polyolefin, polyimide, polyamide, polycarbonate, polyether, polysulfone, polyether ether ketone, ceramic and the like can be selected, the materials used in the liquid tank have high stability in spinning solution, and the physical and chemical properties and the shape of the liquid tank are not influenced by the spinning solution.

The spinning generator liquid tank has a rotating function. During spinning, the spinning machine is driven by an external motor to rotate in a single direction. The rotation speed is 1000-.

As shown in figure 3, the spinneret holes (slits) on both sides of the inner container 81 of the liquid tank are provided with steps 82 of 0-5mm on the outer edge to prevent the spinning solution from spreading to the outer wall of the liquid tank before forming the jet. The number of the spinning holes (i.e., the spinning nozzles 4) is even and they are arranged symmetrically about the center to prevent the eccentric force from being generated.

The built-in high-voltage electrode is made of corrosion-resistant stainless steel or alloy materials, and can be of a linear, flat or net structure and is uniformly arranged in the liquid tank to ensure effective contact with spinning liquid. The built-in high voltage electrode is located inside the spinning head 4 and connected to an external high voltage generator through a connection line, thereby applying a high voltage to the spinning solution.

Meanwhile, an external electrode (grounding electrode 4) is fixed outside the rotary liquid tank by an insulating material and is connected with an external high-voltage generator. The electrode is made of a corrosion resistant stainless steel or alloy material and has a small radius of curvature at its tip (typically the diameter of the electrode tip is less than 1mm to ensure that a smaller radius of curvature will create a stronger local electric field at the spinning head). In operation, the electrodes rotate in synchronism with the fluid bath.

Because the high voltage electrode is connected into the liquid tank to apply high voltage to the solution, the grounding electrode is arranged outside the liquid tank. The liquid tank is made of insulating materials, so that the spinning solution of the spinning nozzle and the outer electrode of the liquid tank form a local high-pressure field to play an effective drafting role on the spinning solution. Namely, two electrodes are arranged on the rotary liquid tank, one of the two electrodes is arranged in the liquid tank and connected with the spinning solution to play a role in polarizing the spinning solution, and the other electrode is arranged outside the liquid tank; during the spinning process, the two electrodes and the liquid groove rotate synchronously.

As shown in FIG. 4, the spin slit has an angle of 0-70 degrees along the axis of rotation (the angle formed by the length of the slit and the axis of rotation) to facilitate the formation of the fibers. The axial length is less than the height of the liquid in the liquid groove, and the width of the slit is 0.1-5 mm. The slits are arranged in pairs in an even number and are axially symmetrical with the rotating shaft of the liquid tank. FIG. 4 includes two slit orifices and two elongated ground electrodes, the orifices and ground electrodes being insulated from each other to provide a high voltage.

Each of the externally-arranged ground electrodes is located at the front end in the rotational direction with respect to its corresponding spinning head 3 (filament outlet). Wherein, the external electrode can be parallel to the spinneret orifice (also can be understood as a spinneret channel) or in the same plane; or in a different plane. When the two are in different planes, the clamping formed by the projection of the two in the vertical plane of the rotating shaft is not more than 90 degrees.

Also, referring to FIG. 2, the electrode tip is maintained at a distance from the orifice (slit), preferably 5mm to 100mm (referring to the distance from the orifice to the ground electrode).

When the slot spinning adopts the hole shape as shown in fig. 2 and fig. 5, the top structure of the external electrode is preferably a sharp point structure; when the slit-like shape shown in fig. 4 and 6 is adopted, the external electrode is preferably of an elongated structure. The corresponding external electrode structure design is convenient for generating stronger electric field, thereby generating stronger drafting effect on the spinning solution and being beneficial to forming thinner fibers.

Also, the number of external electrodes (here, ground electrodes) is the same as the number of orifices (slits). So as to ensure that each wire outlet is provided with a corresponding grounding electrode.

And when an external high-voltage generator applies high voltage between the external electrode and the internal electrode, a high-voltage electric field is formed between the surface of the spinning solution and the external electrode. The desired high voltage ranges between 5kV and 40 kV.

Moreover, the external high-voltage generator can be a high-voltage static DC generator or a high-voltage alternating current static generator. When a dc generator is used, the high voltage terminal may be connected to an internal or external electrode.

In addition, the external grounding electrode 4 can be designed to be similar to the spinneret orifice/spinneret channel (the spinneret 3) in shape, and mainly aims to realize control of electric field distribution, the point electrode corresponds to the point electrode, and the slit electrode corresponds to the slender electrode. The two electrodes are not communicated with each other and have respective paths.

The spin generator may be simultaneously attached (with respect to the autogenous flow) to an external gas flow field for controlling the fiber deposition direction. The direction of the air flow is from the liquid tank to the fiber collector, so as to assist in preventing the jet from depositing on the external electrode after being thrown out from the spinning nozzle, enhance the drafting of the jet and control the movement direction of the fiber. The fiber collecting device is mainly used for adjusting the migration direction of fibers and is beneficial to fiber collection.

In fact, although the rotation of the generator generates an air field, the air field is often not consistent with the drafting direction of the fiber, and the normal phase part of the air field applies shearing force to the drafting, which is beneficial to the drafting and thinning of the fiber. The direction of the rotating airflow field can be adjusted through the shape of the generator, the drafting direction of the fibers can be adjusted through the relative position of the two electrodes, and the shearing force can be adjusted through optimizing the shape of the liquid groove and the position of the electrodes, so that the diameter of the fibers can be adjusted. The rotation of the fluid bath may disturb the airflow, the outer shape having an effect on the direction of the rotating airflow. The flow velocity and the flow direction of the surrounding air flow can be controlled by adjusting the external shape and the rotating speed of the liquid groove, so that the fiber diameter can be adjusted by matching with spinning.

The gas stream may be air, nitrogen, carbon dioxide or argon. They are directly guided by pipelines or/and fans, and the gas flow rate is controlled between 0.1 m/s and 5 m/s.

The spinning generator is mainly used for processing viscous liquid, including solution or melt. When the spinning solutions are solutions, they include polymer solutions, sol-gels, particle suspensions, and the like. The viscosity of the viscous liquid is 1 mPas to 100000 mPas. The viscous liquid is preferably in the form of a polymer solution, typically comprising at least one polymer and at least one volatile solvent. When molten, they include a variety of materials that can be melted at a certain temperature, including polymers, small molecules, inorganic materials, metals, and the like.

The fiber collection device can be in a variety of different forms, for example, a roller, a plate belt drive, a rotatable roller; or base cloth including woven cloth, non-woven cloth, paper and plastic film.

The present invention will be described in further detail with reference to examples.

Example 1:

the electrospinning apparatus used is shown in FIG. 1. The electrostatic spinning device comprises a pinhole type disc fiber generator, a direct current high-voltage power supply, a flat plate collector and a fan. The rotating speed of the liquid tank is 3000 r/min, the voltage is 2 ten kilovolts (the internal electrode is connected with a high-voltage output end, and the external electrode is grounded), and the wind speed is 1 m/min. The nanofibers were prepared using an 8% aqueous PVA solution formulated with sigma aldrich polyvinyl alcohol (PVA, average molecular weight 146,000-186,000, degree of hydrolysis 96%). In the spinning process, spinning solution is added into a rotary solution tank, and the solution tank is driven by a motor to rotate at a high speed. When the solution reaches the spinning nozzle, the direct-current high-voltage power supply is started, the voltage of 20kV is applied, and the airflow is started, so that the nano fibers are uniformly deposited on the external collector. The yield of the nano-fiber can reach 200 g/h, and the average diameter of the fiber is 150 nanometers. FIG. 6 is a scanning electron micrograph of PVA nanofibers produced in this example.

Example 2:

the electrospinning apparatus used is shown in FIG. 1. The electrostatic spinning device comprises a pinhole type disc fiber generator, a direct current high-voltage power supply, a flat plate collector and a fan. The rotating speed of the liquid tank is 3000 r/min, the voltage is 2 ten kilovolts (the external electrode is connected with a high-voltage output end, the internal electrode is grounded), and the wind speed is 1 m/min. Nanofibers were prepared using a 10% PAN-DMF solution of sigma-aldrich polyacrylonitrile (PAN, average molecular weight 150,000). In the spinning process, spinning solution is added into a rotary solution tank, and the solution tank is driven by a motor to rotate at a high speed. A dc voltage of 22kV was applied to the solution and the airflow was started to deposit the nanofibers uniformly onto the outer collector. The nanofiber yield can be 175 g/h greater and the average fiber diameter can be 180 nm.

Example 3:

the electrospinning apparatus used is shown in FIG. 1. The electrostatic spinning device comprises a pinhole type disc fiber generator, an alternating current high-voltage power supply, a flat plate collector and a fan. The rotating speed of the liquid tank is 3000 r/min, the voltage is 2 ten thousand volts, and the wind speed is 1 m/min. Nanofibers were prepared using 15% PVDF in DMF-acetone solution formulated with sigma aldrich polyvinylidene fluoride (PVDF, average molecular weight 275,000). In the spinning process, spinning solution is added into a rotary solution tank, and the solution tank is driven by a motor to rotate at a high speed. A voltage of 16kV was applied to the solution and the gas flow was initiated to deposit the nanofibers uniformly onto the outer collector. The nanofiber yield can be 230 g/h greater with a fiber average diameter of 210 nanometers.

The biggest difference between the nanofiber generating device provided by the invention and the prior art is that the electric field is formed between the generator and the collector, for example, the grounding in CN105568403B is connected to the collector, and because the spinning distance is larger, the action of the electric field force is weak during spinning even if higher voltage is applied, the drafting on the fibers is not enough, and the fibers are thick and uneven.

In the technical scheme, the spinning electric field is realized by two electrodes which are added on the rotary liquid tank, and because the distance between the high-voltage electrode and the grounding electrode is small (the distance between the two electrodes is inversely proportional to the strength of the formed electric field), although the applied voltage is low, the strength of the actually formed electric field is very high, and fine and uniform fibers are easily formed by the drafting of the solution jet flow by the large electric field force.

As shown in fig. 8 and fig. 9, the principle comparison between the conventional centrifugal electrospinning technique and the technical solution of the present application is illustrated; for ease of illustration, only one or a pair of spinnerets are shown. In FIG. 8, the spinning head 12 is a high voltage electrode, and forms an electric field E with the grounding electrode 11, the liquid tank 13 generates centrifugal force in the rotation direction indicated by the arrow, and the fibers generate electric field force F_ECentrifugal force F_CAnd wind force F_WTowards the receiver. In the prior art, as shown in FIG. 9, the spinning head 10 is a high voltage electrode, the receiver is grounded, an electric field E is generated between the spinning head and the receiver, the liquid tank 14 generates centrifugal force in the direction of rotation indicated by the arrow, and the fibers are subjected to an electric field force F_EAnd centrifugal force F_CTowards the receiver.

Table 1 below shows the deep comparison between the prior art and the technical solutions of the present invention and the parameters of the performance, and the excellent performance of the nanofiber generating device of the present application can be laterally verified by the following table.

Table 1:

the nanofiber generating device driven by three external force fields of static, centrifugation and airflow in a coordinated mode is used for processing viscous fluid into nanofibers. The technology can not only greatly improve the production speed of the nano-fiber and the adjustment capability of the fiber fineness, but also deposit the produced fiber on any base material to form uniform nano-nonwoven fabric. The device is suitable for large-scale production of the nano fibers, and the produced fibers are thinner and more uniform.

Claims

1. A nanofiber generating device, comprising:

a fiber collection device;

2. The nanofiber generating device according to claim 1, wherein the internal electrode is a high voltage positive electrode and the external electrode is a negative electrode; or, the built-in electrode is a high-voltage end electrode, and the external electrode is a counter electrode.

3. The nanofiber generating device as claimed in claim 1, wherein the internal electrode is connected with the output end of the external high voltage generator through the spinning channel, the external electrode is a grounding electrode, and the external electrode is fixed on the external surface of the spinning solution storage device through an insulator.

4. The nanofiber generating device as claimed in claim 1, wherein the rotation speed of the spinning solution storage device is 1000-.

5. The nanofiber generating apparatus as claimed in claim 1, 2, 3 or 4, wherein the voltage of the high voltage electric field formed between the spinning solution and the external electrodes is in the range of 5-40 KV.

6. A nanofiber generating device according to claim 3, wherein the high voltage generator is a high voltage electrostatic dc generator or a high voltage ac electrostatic generator.

7. The nanofiber generating device according to claim 3, wherein the external electrode is located in front of the corresponding spinning channel in the rotation direction of the spinning solution storage device.

8. The nanofiber generating device as claimed in claim 1 or 3, wherein the number of the spinning channels is an even number.

9. The nanofiber generating device as claimed in claim 1 or 3, wherein the spinning solution storage device comprises a liquid storage tank, and the liquid storage tank is provided with a shielding part for preventing the spinning solution from being thrown out along other channels or outlets outside the spinning channel; the outlet of the spinning channel is in a hole shape or a slit shape.

10. The nanofiber generating device according to claim 9, wherein the tank body of the liquid storage tank is in an axisymmetric structure or a central symmetric structure.

11. A nanofiber generating device as claimed in claim 10, wherein the reservoir is cylindrical; the outer diameter of the cylinder is 20-1000 mm; the axial thickness of the liquid storage tank is 10-500 mm.

12. The nanofiber generating device as claimed in claim 9, wherein when the outlet of the spinning channel is in the shape of a slit, the length direction of the slit forms an included angle of 0-70 degrees with the rotating shaft, the length of the slit is smaller than the external thickness of the liquid storage tank, and the width of the slit is 0.1-5 mm.

13. The nanofiber generating device as claimed in claim 1, 3 or 7, wherein the outlet of the spinning channel is in the shape of a hole or a slit; when the outlet of the spinning channel is in a hole shape, the top end of the external electrode is a pointed end; when the outlet of the spinning channel is in a slit shape, the external electrode is in a slender structure.

14. The nanofiber generating device according to claim 7, wherein the external electrodes and the corresponding spinning channels are in the same plane.

15. The nanofiber generating device as claimed in claim 7, wherein the external electrodes and the corresponding spinning channels are in different planes, and the included angle formed by the projection of the external electrodes and the corresponding spinning channels on the vertical plane of the rotating shaft is 0-90 degrees.

16. The nanofiber generating device as claimed in claim 2, wherein when the outlet of the spinning channel is in the form of a slit, the distance between the slit spinning hole and the counter electrode is 5mm-100 mm.

17. The nanofiber generating device as claimed in claim 3, wherein the spinning solution storage device comprises more than one spinning channel, the internal electrode is connected with the output end of an external high voltage generator through the more than one spinning channel, and each spinning channel corresponds to one external electrode.

18. The nanofiber generating apparatus as claimed in claim 1, wherein the airflow direction of the airflow generating apparatus is from the spinning solution storage means to the fiber collecting means, and the airflow velocity is 0.1-5 m/s.

19. A nanofiber generating device according to claim 18, wherein the gas of the gas stream is air, nitrogen, carbon dioxide or argon.

20. The nanofiber generating apparatus as claimed in claim 1, wherein the spinning solution is a viscous liquid having a viscosity of 1-100000 mPa-s.

21. A nanofiber generating device according to claim 20, wherein the viscous liquid is selected from a solution of a polymer, a sol-gel solution or a suspension of particles.

22. The nanofiber generating apparatus according to claim 18 or 19, wherein the spinning solution is a molten polymer solution comprising at least one polymer and at least one volatile solvent.