TWM457736U - Screw fiber producer and static screw spinning device - Google Patents

Description

Screw fiber generator and electrostatic screw spinning equipment

The present invention relates to a spinning apparatus, in particular an electrospinning apparatus.

Conventional electrospinning equipment typically includes a hollow needle spinning head, a transmission for conveying the spinning solution, a collector, and a high voltage electric generator. High piezoelectricity is typically applied to the spinneret and collector (also called "counter electrode"). In the electrospinning process, a high voltage is applied to the spinning solution through the spinning head while also forming a high voltage electric field between the spinning head and the receiving device. Due to the action of the high voltage electric field, the spinning solution is drawn into a tapered structure (also called "Taylor cone") at the top end of the spinneret. When the electric field force is high to a certain extent, the spinning solution overcomes its surface tension and is ejected from the tip of the Taylor cone to form a "jet". The charged jet is then subjected to a high voltage electric field and rapidly drafted and thinned. The repulsive force created between the same charge inside the jet also accelerates the jet drafting and swinging. At the same time, the volatilization of the solvent causes the jet to solidify and eventually deposits on the counter electrode collector to form a network of nonwoven-like nanofibers.

Needle electrospinning nanofiber equipment technology can only provide very limited production capacity. Because each spinning head can only produce up to three hundred grams of nanofiber per hour. Due to the high voltage concentration, when the voltage is higher than 30,000 volts, the tip of the needle spinning head forms a "glow discharge", thus terminating the spinning process. For this reason, the needle electrospun nanofiber device has a voltage of less than 30,000 volts, and the nanofibers produced at low operating voltages are coarse and uneven (as shown in Annex 2).

Increasing the liquid area will greatly increase the productivity of the electrostatic field nanofibers. E.g International patent WO2005024101 provides a needleless electrospinning device. The apparatus includes a roller-shaped electrode (fiber generator) partially immersed in a polymer solution, and a fiber collector (counter electrode) at a distance from the fiber generator. The rotation of the roller electrode causes the polymer solution to be uniformly loaded onto the entire surface of the drum. When the loaded polymer solution is located in an electric field formed by the roller electrode and the fiber collector, and the electric field is strong enough to cause the liquid on the surface of the drum to form a Taylor cone, the surface of the drum can be spun out of the nanofiber.

In such an electrospinning system, the formation of nanofibers is highly dependent on the electric field strength and electric field distribution in the vicinity of the spinning head and throughout the electrospun region. Since the strength of the electric field in the middle portion of the drum is much smaller than the both ends of the drum, when the voltage is lower than the critical value, the middle portion of the drum loses the spinning ability. Only the ends of the drum can be spun out of the nanofibers. Even if the operating voltage is higher than the critical value, the diameter of the nanofibers produced at different roller portions will be greatly different. Therefore, the fineness of the manufactured nanofibers is very uneven. It is necessary to improve the quality of nanofibers by improving the spinning head.

The present invention provides a new coaxial screw fiber generator and an electrostatic screw spinning device comprising the coaxial screw fiber generator for processing various viscous liquids into nanofibers in an electrostatic field.

According to an aspect of the present invention, there is provided a screw fiber generator for producing a nanofiber from a viscous liquid by an electrospinning principle, the screw fiber generator comprising a spiral blade and a shaft, the spiral blade and the shaft connection.

Importantly, the average radius of the spiral blades is between 5 and 1000 mm.

Importantly, the helical blade contains single or multiple coaxial blades.

It is important that when the spiral blade contains more than three blades, the radius of the blades near the ends is smaller than the radius of the intermediate blades.

Importantly, the length of the screw fiber generator is between 20 and 6000 mm.

Importantly, the thickness of the spiral blade is between 0.5 and 50 mm.

Importantly, the screw fiber generator consists of one or more rows of screw fiber generators with a distance between the rows and the rows of greater than 20 mm.

Importantly, the screw fiber generator includes a liquid container.

It is important that the liquid container is used to store viscous liquids.

It is important that at least one surface of the screw fiber generator is connected to the viscous liquid in the liquid container.

What is important is that the spiral blade is a hollow structure having holes distributed on the surface of the blade, and a passage inside the blade is connected to the hollow drive shaft.

Importantly, the hollow passage inside the blade is connected to the liquid container to provide a viscous liquid therein.

According to another aspect of the present invention, there is provided an electrostatic screw spinning apparatus, An electrostatic screw spinning apparatus produces nanofibers from a viscous liquid in an electric field, the electrostatic screw spinning apparatus comprising: a screw fiber generator according to the first aspect of the present invention; a distance from the screw fiber generator a counter electrode nanofiber collector; a liquid container for storing the viscous liquid for spinning; and a high voltage generating device, the electrodes of the high voltage generating device being respectively connected to the screw fiber generator and the counter electrode nanofiber collector.

It is important that the counter electrode nanofiber collector and the screw fiber generator are axially parallel.

Importantly, the length of the counter electrode nanofiber collector is comparable to the length and width of the screw fiber generator.

Importantly, the counter electrode nanofiber collector is a flat plate, roller or a driveable ribbon receiving device.

Importantly, the surface of the counter electrode nanofiber collector is a porous structure to improve air convection in the receiving area with a dry gas of a certain temperature.

Importantly, the electrostatic screw spinning apparatus produces a voltage difference of more than 30,000 volts for the screw fiber generator and the counter electrode nanofiber collector.

It is important that the distance between the screw fiber generator of the electrostatic screw spinning apparatus and the counter electrode nanofiber collector is between 100 and 600 mm.

It is important that the viscous liquid of the electrostatic screw spinning device is a viscous liquid capable of producing nanofibers.

It is important that the screw fiber generator of the electrostatic screw spinning apparatus is immersed in the viscous liquid, and the screw fiber generator is designed to be rotatable along the central axis so that the viscous liquid can be loaded on the surface.

Importantly, the nanofibers produced by the electrostatic screw spinning equipment are nonwoven fabrics or oriented nanofiber membranes.

The screw fiber generator provided by the present invention and the electrostatic screw spinning device including the screw fiber generator are suitable for mass production of nanofibers, and the fibers produced are finer and more uniform.

01‧‧‧Spiral blade spinning head

01-1‧‧‧Drive shaft

01-2‧‧‧Spiral blades

02‧‧‧Counter collector

03‧‧‧Spinning fluid storage tank

04‧‧‧High voltage power supply

05a, 05b‧‧‧electrode connection

【annex】

Attachment 1 is an electron micrograph of a nanofiber produced by an electrostatic screw spinning apparatus according to the present invention.

Attachment 2 is an electron micrograph of a nanofiber produced by a conventional needle electrospinning device.

Annex 3 shows the electric field intensity distribution of the spiral blade surface in the electrostatic screw spinning apparatus according to the present invention, wherein the right half of the figure is an enlarged blade, and the number is the electric field strength of the equal voltage line (unit: kilovolt/cm).

Annex 4 shows the electric field strength distribution of a conventional needle electrospinning device, with the right half of the figure being an enlarged needle. The number is the electric field strength of the equal voltage line (unit: kilovolts/cm).

1 is a spiral blade type needle-free electrospun nanofiber production apparatus according to the present invention.

Figure 2 depicts in more detail the shape and configuration of a spiral blade spinneret in accordance with the present teachings.

At present, the present invention provides a novel spiral type needle-free electrostatic nanofiber production equipment, also known as an electrostatic screw spinning equipment, which is mainly used for processing various viscous liquids into nanofibers under the action of an electrostatic field. The core of the nanofiber production equipment is a nanofiber generator (also called a "spinning head") consisting of one or a group of spiral blades. The coaxial screw fiber generator includes a spinning spiral blade and a rotatable drive shaft, wherein the spiral blade is mainly fixed to the drive shaft. The diameter ratio of the blade to the drive shaft is greater than 1:3, more preferably greater than 1:5, and most preferably greater than 1:10.

Spiral blades are primarily used to concentrate electrostatic fields at the edges of the blades and to reduce or eliminate the effects of blade shape and size on the electrostatic field. Such a device causes a high electric field to be uniformly and concentratedly distributed on the surface of the fiber formation region of the blade. In electrospinning, when the electrostatic field strength is sufficient to pull the spinning liquid into a "Taylor cone", a jet forming the nanofiber is produced in the edge region of the blade. When multiple spiral blades are used, the electric field interference of adjacent blades can be reduced or completely avoided by optimizing the distance between the blades. Such a device produces finer and more uniform nanofibers than a roller-shaped needleless electrospinning head.

The spiral blade of the spinneret can be composed of a single blade or a plurality of blades. When used in large-scale nanofiber production, the spiral blade of the spinneret preferably comprises a plurality of blades and is distributed in a helical configuration along the central axis because a plurality of blades provide a larger area of nanofiber production, and The axial distribution of the blades causes the produced nanofibers to be uniformly deposited on the surface of the collecting electrode.

The spiral blade can be designed in any shape. For example, the cross section may be circular, elliptical, rectangular, conical, 稜鏡 or other. The spiral blades can be distributed around the central axis. The radius of the blade can be between 5 and 1000 mm. The thickness of the blade can be between 0.5 and 200 mm, preferably It is between 0.7 and 50 meters. When a set of blades is used, the blades can be arranged relatively independently. The length of the entire spinneret can be between 20 and 6000 mm.

When a set of identical blades is used, the electric field strength of the blades at both ends of the spiral blade of the spinneret tends to be higher than that of the blade in the middle portion. When the radius of the blades at both ends is small, the electric field generated by the spiral blades in the axial direction can be equally distributed to each of the blades. Therefore, the blades at both ends are preferably designed to have a gradually smaller radius.

There must be a certain spacing between the blades and the blades to reduce the interaction between the blades. The blade thickness, diameter and structure can be adjusted along the axial distance between the blades. The distance between adjacent blades of the spiral blade is preferably between 5 and 800 mm.

The spiral blade can be of any material, conductive or insulating material. It may be metallic copper, iron, or aluminum, or it may be engineering plastics, resins, ceramics, wood, or composite materials. The main requirement for spiral blade materials is that they cannot dissolve or degrade in the spinning solution.

The spiral blade may be a hollow structure having a passage connected to a hollow drive shaft for conveying the spinning solution. In this case, the surface of the blade should have openings. The spinning solution can be transported through the interior of the blade and drive shaft to the surface of the blade that produces the fiber.

The needle-free electrostatic nanofiber production equipment for producing nanofibers from a viscous liquid (ie, "spinning fluid") in an electric field, also referred to as an electrostatic screw spinning apparatus, mainly includes the following parts: a screw fiber generator as described above (ie, a "spiral blade spinner"); a counter electrode nanofiber receiver (also referred to as a "counter electrode collector") spaced apart from the nanofiber generating device; a container for spinning a viscous liquid (spinning liquid); And high voltage generating devices.

The electrodes of the high voltage generating device are connected to the spiral blade spinneret and the counter electrode collector, respectively, to generate a high voltage difference.

The nanofibers produce a spinning solution for covering the surface of the spiral blade spinneret. The high voltage generating device produces a high voltage difference between the screw fiber generator and the counter electrode nanofiber collector. When the voltage difference between the surface of the spinning liquid and the counter collector is higher than a certain value (e.g., 30,000 volts), the jet is generated from the surface of the blade and eventually forms a nanofiber. The critical electric field strength at which the nanofibers are produced is related to a number of factors, including the shape and size of the spiral blade spinner and the counter electrode collector, the distance between them (also called "spinning distance" or "collection distance"), and The chemical nature of the spinning solution. In general, the production of nanofibers requires at least 40,000 volts of high voltage. In most cases, it is better than 60,000 volts.

The distance between the spiral blade spinneret and the counter electrode collector affects the electric field strength and the quality of the nanofibers. Of course, the effects will also come from the shape of the spiral blade spinner and counter electrode collector, and the properties of the spinning solution. Generally, the counter electrode nanofiber collector and the screw fiber generator are axially parallel. The length of the counter electrode nanofiber collector is comparable to the length and width of the screw fiber generator. The spinneret is separated from the counter electrode by a distance of 100 to 600 mm.

The spinning solution may be any liquid capable of producing nanofibers, such as a polymer solution, a sol gel, a particle suspension, or a molten polymer liquid. In most cases, the spinning solution consists of at least one polymer and a volatile solvent. High molecular polymers, such as synthetic polymers, natural polymers and biomacromolecules, thermoplastic polymers or reactive polymers. The use of solvents depends primarily on the type and nature of the polymer. They may be volatile solvents including water, ethanol, chloroform (chloroform), dimethylformamide, and the like. Volatilization of the solvent during electrospinning is beneficial Curing and forming of nanofibers.

A number of methods are available for loading the spinning solution onto the surface of the spiral blade spinneret. For example, the screw fiber generator of the electrostatic screw spinning apparatus is immersed in a viscous liquid, and the screw fiber generator is designed to be rotatable along a central axis, so that a viscous liquid can be loaded on the surface. The rotation of the spiral vanes causes the spinning solution to cover the entire surface of the blade. In this case, at least one surface of the screw fiber generator is connected to the viscous liquid in the liquid container. The counter electrode collector is preferably located directly above the spiral blade spinneret and parallel to the drive shaft of the helical blade spinneret. In electrospinning, the nanofibers are spun from the top surface of the blade edge and deposited onto the counter electrode receiver.

The spinning solution can also be loaded from the inside of the spiral blade to the surface of the blade. In this case, the spiral blade has a hollow structure and has a passage connected to the external reservoir. The openings in the surface of the blade allow the spinning solution to be uniformly loaded into the fiber-generating region of the spinneret. In this case, the liquid tank below the spiral blade spinner is mainly used to collect excess spinning solution.

Different structures can also be used for the electrode collector. In addition to the fixed plate receiving device, a rotating drum, or a continuous collecting device similar to a conveyor belt, collects the nanofibers more efficiently. In some cases, in order to facilitate solvent evaporation and solidification of the nanofibers, a porous network structure may be used for the counter electrode fiber receiving surface of the electrode collector, and air convection and solvent diffusion in the collection region are accelerated by dry air at a certain temperature.

The nanofiber produced by the electrostatic screw spinning device is a non-woven fabric or an oriented nanofiber film.

In order to produce nanofibers on a larger scale, the needle-free nanofiber spinning apparatus may include a plurality of rows of spiral blade spinning heads parallel to each other. In this case, the multi-row spiral blades can share a large reservoir or use multiple separate reservoirs. In order to avoid adjacent spiral leaves The influence of the film, the distance between the row and the row is more than 20 亳 meters, preferably more than 50 亳 meters.

An example of an electrostatic screw spinning apparatus according to the present invention will be specifically described below with reference to the accompanying drawings.

1, the electrostatic screw spinning device is composed of a spiral blade spinning head 01, a counter electrode collector 02, a spinning solution reservoir 03, and a high voltage power source 04. The spiral blade spinning head 01 includes a drive shaft 01-1 and a spiral blade 01-2. The electrodes of the high voltage generator are connected to the spiral blade spinning head 01 and the counter electrode collector 02 via electrode wires 05a and 05b, respectively. The spinning solution is stored inside the spinning solution tank 03. The liquid level of the spinning solution has a certain connection with the spiral blade 01-2. When the blade is slowly rotated (e.g., at a rotational speed of 40 rpm), the spinning solution is uniformly applied to the surface of the spiral blade due to the wetting action of the liquid.

Figure 2 shows a more detailed spiral blade spinneret structure. The metal spiral blade extends along the axial direction. When the spiral blade contains more than three blades, the blade radius near the ends is smaller than the radius of the intermediate blade. The spiral blade is partially immersed in the spinning solution.

As a typical example, the above apparatus is used to produce polyacrylonitrile nanofibers. The spinning solution was a 9% polyacrylonitrile (PAN)-dimethylformamide (DMF) solution. In the electrospinning process, nanofibers are produced in the edge regions of the blade surface.

In contrast, conventional needle electrospinning equipment is used to process the same spinning solution.

Experimental results: During the electrospinning process, the viscous PAN solution is evenly loaded on the surface of the blade due to the rotation of the spiral blade. When a high voltage electric field is applied, a large number of jets are formed at the edge of the blade. The minimum application voltage is 60,000 volts. The photographs of Annex 1 and Annex 2 show the spun fiber morphology. It can be seen under the electron microscope that the photo of Annex 1 shows that the nanofibers produced by the needleless equipment are very uniform. uniform. The average diameter is about 150 nm. As shown in Annex 2, it is known that the average diameter of the needle electrospun fibers is greater than 200 nm. Compared to conventional needle electrospinning, the needle-free electrospinning equipment produces nanofibers that are much finer and have a more uniform diameter distribution. Among them, the operating conditions corresponding to Annex 1 are as follows: operating voltage: 60,000 volts; collection distance: 150 亳 m; spinning solution: 9% polyacrylonitrile-dimethylformamide solution. The operating conditions corresponding to Annex 2 are as follows: operating voltage 20,000 volts; collection distance: 150 亳m; spinning solution: 9% polyacrylonitrile-dimethylformamide solution. Annexes 3 and 4 show the distribution of electric field strength. It is not difficult to see that the high electric field is mainly concentrated in the top end region of the blade edge. Moreover, the electric field strength is large. This area actually coincides with the area produced by the fiber. That is to say, the nanofibers are mainly formed in the electric field gathering region on the surface of the blade. Although a conventional needle electrospinning device also forms an agglomerated electric field at the end of the spinneret, the value of the electric field strength is much smaller.

For an electrostatic screw spinning machine with a length of 20 cm, the nanofiber production capacity is 20 grams per hour. When the length of the device is one meter and 10 rows of the same spiral spinning device are used, the production capacity of the nanofiber is 1 kg per hour. In contrast, for conventional needle electrospinning equipment, a single needle device requires an area of 20 x 10 square centimeters and a nanofiber production capacity of no more than 0.3 grams per hour. The multi-needle electrospinning equipment has about 100 spinning needles within 1 square meter, and its nanofiber production capacity is 30 grams per hour.

Further experiments have also shown that the size of the blade has little effect on the electric field and fiber diameter, but has a great influence on the production speed.

01‧‧‧Spiral blade spinning head

01-1‧‧‧Drive shaft

01-2‧‧‧Spiral blades

02‧‧‧Counter collector

03‧‧‧Spinning fluid storage tank

04‧‧‧High voltage power supply

05a, 05b‧‧‧electrode connection

Claims (23)

A screw fiber generator for manufacturing a nanofiber from a viscous liquid by using an electrospinning principle, characterized in that the screw fiber generator comprises a spiral blade and a shaft, and the spiral blade and the shaft connection. A screw fiber generator according to claim 1, wherein the spiral blade has an average radius of between 5 mm and 1000 mm. The screw fiber generator of claim 1, wherein the spiral blade comprises a single or a plurality of coaxial blades. A screw fiber generator according to claim 3, wherein when the spiral blade contains three or more blades, the radius of the blades near the both ends is smaller than the radius of the intermediate blade. The screw fiber generator of claim 3, wherein the screw fiber generator has a length of between 20 mm and 6000 mm. The screw fiber generator of claim 1, wherein the spiral blade has a thickness of between 0.5 mm and 50 mm. The screw fiber generator of claim 3, wherein a distance between adjacent blades of the spiral blade is between 5 mm and 800 mm. The screw fiber generator according to claim 1, wherein the screw fiber generator is composed of one or more rows of screw fiber generators, and the distance between the rows and the rows is greater than 20 mm. The screw fiber generator of claim 1, wherein the screw fiber generator comprises a liquid container. A screw fiber generator according to claim 9, wherein the liquid container Used to store viscous liquids. A screw fiber generator according to claim 10, wherein at least one surface of the screw fiber generator is connected to a viscous liquid in the liquid container. The screw fiber generator according to claim 11, wherein the spiral blade is a hollow structure having a hole distributed on a surface of the blade, and a channel inside the blade is connected to the hollow drive shaft. A screw fiber generator according to claim 12, wherein a hollow passage inside the vane is connected to the liquid container to provide the viscous liquid therein. An electrostatic screw spinning apparatus for producing nanofibers from a viscous liquid in an electric field, wherein the electrostatic screw spinning apparatus comprises the following parts: as in claim 1-13 The screw fiber generator; a counter electrode nanofiber collector spaced apart from the screw fiber generator; a liquid container for storing the viscous liquid for spinning; and a high voltage generating device The electrodes of the high voltage electricity generating device are connected to a screw fiber generator and a counter electrode nanofiber collector, respectively. The electrostatic screw spinning apparatus according to claim 14, wherein the counter electrode nanofiber collector and the screw fiber generator are axially parallel. The electrostatic screw spinning apparatus according to claim 14, wherein the length of the counter electrode nanofiber collector is equivalent to the length and width of the screw fiber generator. The electrostatic screw spinning apparatus according to claim 16, wherein the counter electrode nanofiber collector is a flat plate, a drum or a driveable belt-shaped receiving device. An electrostatic screw spinning apparatus according to claim 16, wherein the counter electrode The surface of the nanofiber collector is a porous structure to improve air convection in the receiving area with a dry gas of a certain temperature. The electrostatic screw spinning apparatus according to claim 14, wherein the electrostatic screw spinning device causes the screw fiber generator and the counter electrode nanofiber collector to generate a voltage difference higher than 30,000 volts. . The electrostatic screw spinning apparatus according to claim 14, wherein a distance between the screw fiber generator of the electrostatic screw spinning device and the counter electrode nanofiber collector is 100 mils. To 600 meters. The electrostatic screw spinning apparatus according to claim 14, wherein the viscous liquid of the electrostatic screw spinning apparatus is a viscous liquid capable of producing nanofibers. The electrostatic screw spinning apparatus according to claim 14, wherein the screw fiber generator of the electrostatic screw spinning apparatus is immersed in the viscous liquid, and the screw fiber generator is designed The rotation can be rotated along the central axis so that the viscous liquid can be loaded on the surface. The electrostatic screw spinning apparatus according to claim 14, wherein the nanofiber produced by the electrostatic screw spinning device is a nonwoven fabric or an oriented nanofiber film.