US20080102145A1

US20080102145A1 - Conjugate Electrospinning Devices, Conjugate Nonwoven and Filament Comprising Nanofibers Prepared by Using the Same

Info

Publication number: US20080102145A1
Application number: US11/722,873
Authority: US
Inventors: Hak-yong Kim; Jong-Cheol Park
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-09-26
Filing date: 2005-09-26
Publication date: 2008-05-01
Also published as: JP4769871B2; WO2007035011A9; JP2009510272A; EP1929074A4; WO2007035011A1; EP1929074A1

Abstract

Discloses are a conjugate electrospinning devices for preparing fibers (nanofibers) having a nano-level thickness, and nanofibers prepared using the same. The conjugate electrospinning devices comprises: spinning dope main tanks (1); metering pumps (2); a nozzle block (4); nozzles (5) aligned on the nozzle block; a collector (7) for collecting fibers spun from the nozzle block; and a voltage generator (9) for applying a voltage to the nozzle block and the collector (7), wherein [I] nozzles for spinning two or more different kinds of spinning dope are aligned on a nozzle block (4) regularly or in random order in repetitive units at the same ratio or in different ratios, aligned in random order at a predetermined ratio, or aligned thereon in random order at a predetermined ratio, or aligned thereon repetitively; [II] the number of the spinning dope main tanks (1) is two or more; and [III] a spinning dope drop device (3) is arranged between the spinning dope main tanks (1) and the nozzle block (4). Since two or more different kinds of spinning dopes are combined and electrospun, and thus the physical properties (features) of a non-woven fabric and a filament can be easily managed by a simple process. Nanofibers and their non-woven fabrics can be mass produced because the fiber formation effects are maximized.

Description

TECHNICAL FIELD

The present invention relates to an conjugate electrospinning devices which can mass-produce two or more kinds of fibers having a nano level thickness (hereinafter, “nanofibers”) at a time by simultaneously electrospinning two or more different kinds of polymer spinning dope through nozzles aligned on one nozzle block.
Moreover, the present invention relates to a conjugate non-woven fabric (herainfter, “conjugate nanofiber non-woven fabric) which is prepared by the aforementioned conjugate electrospinning devices and has two or more kinds of nanofibers mixed with each other.
Moreover, the present invention relates to a continuous filament (herainfter, “conjugate nanofiber filament) which is prepared by the aforementioned conjugate electrospinning devices and has two or more kinds of nanofibers mixed with each other.
Products, such as non-woven fabrics, membranes, braids, etc., composed of nanofibers are widely used for commodities, agricultural applications, apparel, industrial applications, etc. Specifically, they are used in various fields such as artificial leather, artificial suede, hygienic band, clothing, diapers, packing material, miscellaneous goods, a variety of filter material, medical materials for gene carriers, military material like bulletproof vests and so on.

BACKGROUND ART

A conventional electrospinning devices and a process for preparing nanofibers using the same have been disclosed in U.S. Pat. No. 4,044,404. The conventional electrospinning devices includes; a spinning dope main tank for storing a spinning dope; a metering pump for quantitatively supplying the spinning dope; a nozzle block having a plurality of nozzles aligned for discharging the spinning dope; a collector positioned at the lower end of the nozzles, for collecting the spun fibers; and a voltage generator for generating a voltage.
The conventional process for preparing the nanofibers using the electronic spinning devices will now be described in detail. The spinning dope from the spinning dope main tank is consecutively quantitatively provided to the plurality of nozzles supplied with a high voltage through the metering pump.
Continuously, the spinning dope supplied to the nozzles is spun and collected on the collector supplied with the high voltage through the nozzles, thereby forming a single fiber web.
Continuously, the single fiber web is embossed or needle-punched to prepare the non-woven fabric.
However, the conventional electrospinning devices and process for preparing the non-woven fabric using the same have a disadvantage in that an effect of electric force is reduced because the spinning dope is consecutively supplied to the nozzles having the high voltage.
In more detail, the electric force transmitted to the nozzles is dispersed to the whole spinning dope, and thus fails to overcome interface or surface tension of the spinning dopes. As a result, fiber formation effects by the electric force are deteriorated and the spinning dope is dropped in the form of drops (hereinafter, referred to as “droplet”), which deteriorates the quality of the product and hardly achieves mass production of the fiber.
Moreover, in the conventional art, spinning is done at the one-hole level in most cases, and thus mass production and commercialization are not possible.
Moreover, the conventional electrospinning devices can electrospin only one kind of polymer spinning dope through the nozzles aligned in one nozzle block, and thus cannot effectively satisfy various physical properties (features) of a nanofiber non-woven fabric required according to purpose.
To solve the above problems, there have been proposed methods, which prepare a conjugate nanofiber non-woven fabric by installing several conventional electospinning devices in a row and electrospinning two or more different kinds of polymer spinning dope in each of the electrospinning devices, or which prepare a conjugate nanofiber non-woven fabric by stacking two or more kinds of nanofiber non-woven fabrics prepared in-the respective electrospinning devices upon needle punching.
However, the above-described methods are problematic in that the production facilities and production process are complicated and the production cost increases.
It is therefore, an object of the present invention to provide a conjugate electronic spinning devices which can mass-produce nano fibers by enhancing fiber formation effects by maximizing an electric force supplied to a nozzle block in electronic spinning, namely maintaining the electric force higher than interface or surface tension of a spinning dope, and which can mass-produce nanofibers of high quality by effectively preventing a droplet phenomenon.
It is another object of the present invention to provide a conjugate electrospinning devices which can prepare a conjugate nanofiber non-woven fabric and a conjugate nanofiber filament by simple facilities and process because two ore more different kinds of polymer spinning dope can be simultaneously electrospun through nozzles aligned on one spinning block.

DISCLOSURE OF THE INVENTION

Technical Problem

The present invention provides a conjugate nanofiber non-woven fabric and a conjugate nanofiber filament which have physical properties suitable for purpose by simple facilities and process by electrospinning two or more different kinds of polymer spinning dope through nozzles aligned on one nozzle block.
Moreover, the present invention mass-produces two or more kinds of nanofibers of high quality at a time by maximizing an electric force in electrospinning and effectively preventing a droplet phenomenon.

Technical Means to Solve the Problem

In order to achieve the above-described objects, there is provided a conjugate electrospinning devices according to the present invention, comprising: [I] nozzles for spinning two or more different kinds of spinning dope aligned on a nozzle block 4 regularly or in random order in repetitive units at the same ratio or in different ratios, aligned in random order at a predetermined ratio, or aligned thereon in random order at a predetermined ratio, or aligned thereon repetitively; [II] two or more spinning dope main tanks 1; and [III] a spinning dope drop device 3 installed between the spinning dope main tanks 1 and the nozzle block 4.
The present invention will now be described in detail with reference to the accompanying drawings.
As shown in FIGS. 1 and 2, the conjugate electrospinning devices of the present invention includes two or more spinning dope main tanks 1 for storing two or more different spinning dopes; a metering pump 2 for quantitatively supplying the spinning dope; a nozzle block 4 having block-type nozzles 5 composed of a plurality of pins, and discharging the spinning dope in a fiber shape; a collector 7 positioned at the upper or lower part of the nozzle block 4, for collecting spun single fibers; a voltage generator 9 for generating a high voltage; and a spinning dope discharger 12 connected to the top part of the nozzle block.
FIG. 1 is a schematic view illustrating a process of preparing a conjugate nanofiber non-woven fabric using the conjugate electrospinning devices in accordance with the present invention. FIG. 2 is a schematic view illustrating a process of preparing a conjugate nanofiber non-woven filament using the conjugate electrospinning devices in accordance with the present invention.
In the present invention, the nozzles for spinning two or more different kinds of polymer spinning dope are aligned on the nozzle block 4 regularly or in random order in repetitive units at the same ratio or in different ratios. Preferably, the nozzles are repetitively aligned on the nozzle block alternately in a row in either transverse, longitudinal or diagonal direction.
FIG. 3 is a pattern diagram illustrating nozzles for spinning two or more different kinds of polymer spinning dope aligned on a nozzle block alternately in a row in a diagonal direction. FIG. 4 is a pattern diagram illustrating nozzles for spinning two or more different kinds of polymer spinning dope aligned on a nozzle block regularly in repetitive units at the same ratio or in different ratios in accordance with the present invention. FIG. 5 is a pattern diagram illustrating nozzles for spinning two or more different kinds of polymer spinning dope, being aligned alternately in a row in a longitudinal direction and supplying the spinning dope.
Moreover, in the present invention, as shown in FIGS. 1 and 2, the number of spinning dope main tanks 1 and 1′ for storing and supplying different polymer spinning dopes are two or more, and the spinning dope drop device 3 is arranged between the spinning dope main tanks and the nozzle blocks 4.
In the present invention, it is more preferable for mass production that the outlets of the nozzles 5 installed on the nozzle block 4 are formed in an upward direction, though they may be formed in an upward direction as well as downward direction or horizontal direction. It is more preferable for mass production that the collector 7 is installed at an upper part of the nozzle block 4, though they may be installed at an upper part as well as lower part or horizontal position thereof.
Hereinafter, among the conjugate electrospinning devices of the present invention, description will be made with respect to a bottom up type electrospinning devices in which the outlets of nozzles 5 installed on a nozzle block 4 are formed in an upward direction, and a collector 7 is positioned at an upper part of the nozzle block 4. However, the present invention is not limited to the bottom up type electrospinning devices.
As shown in FIG. 6, the nozzle block 4 of the present invention includes: [I] a nozzle plate 4 f on which nozzles 5 for spinning different spinning dopes are aligned regularly or in random order in repetitive units in the same ratio or in different ratios and two or more spinning dope supply plates 4 h and 4 h′ positioned at the lower end of the nozzle plate and for supplying the spinning dope to the nozzles; [II] overflow removal nozzles 4 a surrounding the nozzles 5, an overflow temporary storage plate 4 g connected to the overflow removal nozzles and positioned at the right upper end of the nozzle plate and an overflow removal nozzle supporting plate 4 e positioned at the right upper end of the overflow temporary storage plate and supporting the overflow removal nozzles; [III] air supply nozzles 4 b surrounding the nozzles 5 and the overflow removal nozzles 4 a, an air supply nozzle supporting plate 4 c positioned at the top end of the nozzle block and supporting the air supply nozzles, and an air storage plate 4 d positioned at the right lower end of the air supply nozzle supporting plate and supplying air to the air supply nozzles; [IV] a conductor plate 4 i having pins aligned in the same way as the nozzles and positioned at the right lower end of the nozzle plate; and [V] a heating plate 4 j positioned at the right lower end of the spinning dope supply plate.
As shown in FIG. 6, the overflow removal nozzles 4 a for removing unspun spinning dope and the air supply nozzle 4 b for supplying air in order to increase the cumulative distribution of nanofibers are sequentially arranged around the nozzles 5 for electrospinning spinning dopes on the collector, thereby forming a triple tube shape.
Moreover, the nozzles 5 for spinning different spinning dopes are aligned on the nozzle block 4 of FIG. 6 alternately in a row in a diagonal direction.
As shown in FIGS. 8 and 10, the outlets of the nozzles 5 for electrospinning the spinning dopes on the collector are enlarged in the shape of one or more flared tubes. At this time, the angle θ of the nozzle 90 to 175°, more preferably, 95 to 150°, is preferable so that the outlets of the nozzles 5 can form spinning dope drops of the same shape in the outlets of the nozzles 5.
If the angle θ of the nozzle outlet exceeds 175°, bigger drops are formed in the nozzle regions, thereby increasing the surface tension. As a result, in order to form nanofibers, a higher voltage is required. As spinning begins not at the center regions of drops, but at the edge parts of drops, the center regions of the drops are solidified, and this may block the nozzles.
Meanwhile, if the angle θ of the nozzle outlet is less than 90°, drops formed at the nozzle outlet regions becomes very smaller. Therefore, when an electric field becomes instantaneously irregular, or an electric field is slightly irregularly supplied to the nozzle outlet regions, fibers cannot be formed because drop forms are not normal, thereby bringing about a droplet phenomenon.
In the present invention, a nozzle length (L, L₁, L₂) is not specifically limited.
However, it is preferred that the nozzle inner diameter (Di) is 0.01 to 5 mm and the nozzle outer diameter Do is 0.01 to 5 mm. If the nozzle inner diameter or nozzle outer diameter is less than 0.01 mm, the droplet phenomenon frequently occurs, and if the nozzle inner diameter or nozzle outer diameter exceeds 5 mm, fiber formation may be impossible.
FIGS. 8 and 9 illustrate the lateral side and plane of a nozzle having one enlarged part (angle) formed at a nozzle outlet, and FIGS. 10 and 11 illustrate the lateral side and plane of a nozzle having two enlarged parts (angle) formed at a nozzle outlet. That is, θ₁as illustrated in FIG. 10 is the angle of a first nozzle outlet which is a part for spinning the spinning dope, and θ₂is the angle of a second nozzle outlet which is a part for supplying the spinning dope.
The nozzles 5 in the nozzle block 4 are aligned in plural number on the nozzle plate 4 f, and the overflow removal nozzles 4 a surrounding them and the air supply nozzles 4 b are sequentially installed outside of the nozzles 5.
The overflow removal nozzles 4 a are provided for the purpose of preventing a droplet phenomenon, which occurs in the event that not every spinning dope formed in excessive amount at the outlets of the nozzles 5 is fiberized, and recovering an overflowing spinning dope, and it serves to collect an unfiberized spinning dope at the nozzle outlets and feed it to the overflow temporary storage plate 4 g positioned at the right lower end of the nozzle plate 4 f.
Of course, the overflow removal nozzles 4 a have a larger diameter than the nozzles 5, and are preferably made of insulating material.
The overflow temporary storage plate 4 g is made of insulating material, and serves to temporally store a residual spinning dope introduced through the overflow removal nozzles 4 a and then feed it to the spinning dope supply plate 4 h.
The air storage plate 4 d for supplying air is positioned at the upper end of the overflow temporary storage plate 4 g, and supplies air to the air supply nozzles 4 b surrounding the nozzles 5 and the overflow removal nozzles 4 a. The air supply nozzle supporting plate 4 c is installed on the top layer of the nozzle block 4 having the air supply nozzles 4 b aligned thereon, and the supporting plate 4 c is composed of non-conductive material. The air supply nozzle supporting plate 4 c is positioned at the nozzle block, and thus an electric force applied between the collector 7 and the nozzles 5 is only concentrated on the nozzles 5 so that spinning can be done smoothly only in the nozzle 5 regions.
The distance h from the upper tip of the nozzles 5 to the upper tip of the air supply nozzles 4 b is 1 to 20 mm, preferably, 2 to 15 mm. In other words, the height of the air supply nozzles 4 b is set 1 to 20 mm, preferably, 2 to 15 mm, greater than that of the nozzles 5. If h is 0, that is, the air supply nozzles 4 b are positioned at the same height as the nozzles 5, jet streams are not effectively formed in the nozzle 5 regions, thereby reducing the area of nanofibers attached on the collector 7. Meanwhile, if h exceeds 20 mm, electric force becomes weaker due to a high voltage applied between the collector and the nozzles, thereby deteriorating the formation performance of nanofibers and making the length or formation pattern of jet streams unstable. Concretely, a Taylor cone disturbs the stability of a jet stream forming region. Consequently, it is difficult to spin nanofibers smoothly.
The speed of air in the air supply nozzles 4 b is 0.05 to 50 m/sec, more preferably, 1 to 30 m/sec. If the air speed is less than 0.05 m/sec, the dispersibility of nanofibers collected on the collector is low, and thus the collecting area is not increased much. If the air speed exceeds 50 m/sec, the area of nanofibers collected on the collector is decreased due to a too high air speed, and thus the collection uniformity of the nanofibers is deteriorated.
The conductor plate 4 i having pins aligned in the same way as the nozzles is installed at the right lower end of the nozzle plate 4 f, and the voltage generator 9 is connected to the conductor plate 4 i.
An indirect heating type heater (not shown) is installed at the right lower end of the spinning dope supply plate 4 h.
The conductor plate 4 i serves to apply a high voltage to the nozzles 5, and the spinning dope storage plate 4 h serves to store the spinning dope introduced to the nozzle block 4 from the spinning dope drop device 3 and then supply it to the nozzles 5. At this time, it is preferable that the spinning dope supply tube 4 h is made with a minimum space so as to minimize the storage quantity of the spinning dope.
Meanwhile, the spinning dope drop device 3 of the present invention is designed to have an overally sealed cylindrical shape as shown in FIGS. 12( a) and 12(b), and serves to supply the spinning dope continuously inlet from the spinning dope main tank 1 to the nozzle block 4 in the form of drops.
The spinning dope drop device 3 is designed to have an overally sealed cylindrical shape as shown in FIGS. 12( a) and 12(b). FIG. 12( a) is a cross sectional view of the spinning dope drop device. FIG. 12( b) is a perspective view of the spinning dope drop device. A spinning dope inducing tube 3 c for inducing the spinning dope to the nozzle block and a gas inletting tube 3 b are arranged side by side at the upper end of the spinning dope drop device 3. Here, the spinning dope inducing tube 3 c is formed slightly longer than the gas inletting tube 3 b.
The gas inlets from the lower end of the gas inletting tube, and an initial gas inletting portion of the gas inletting tube is connected to a filter 3 d. A spinning dope discharge tube 3 d for discharging the dropped spinning dope to the nozzle block 4 is formed at the lower end of the spinning dope drop device 3. The center portion of the spinning dope drop device 3 is hollow shape so that the spinning dope can be dropped from the end of the spinning dope inducing tube 3 c.
The spinning dope induced into the spinning dope drop device 3 is flown through the spinning dope inducing tube 3 c, but dropped at the end thereof. Therefore, flowing of the spinning dope is intercepted at least one time.
The principle of dropping the spinning dope will now be explained in detail. When the gas inlets into the upper end of the spinning dope drop device 3 through the filter 3 d and the gas inletting tube 3 b, a pressure of the spinning dope inducing tube 3 c becomes irregular due to gas eddy. Such a pressure difference drops the spinning dope.
An inert gas such as nitrogen or air can be used as the gas.
The entire parts of the nozzle block 4 of the present invention reciprocates in a direction perpendicular to the traveling direction of nanofibers electrospun by a nozzle block bilateral reciprocating device 10 in order to make uniform the dispersion of electrospun nanofibers.
An agitator 11 c for agitating the spinning dope stored in the nozzle block 4 is installed in the nozzle block 4, more specifically, in the spinning dope supply plate 4 h in order to prevent the spinning dope from gelation.
The agitator 11 c is connected to an agitator motor 11 a by a non-conductive insulating rod 11 b.
As the agitator 11 c is located in the nozzle block 4, it can effectively prevent the spinning dope in the nozzle block 4 from gelation when spinning a dope containing inorganic metal or electrospinning a spinning dope dissolved using a mixed solvent for a long time.
A spinning dope discharger 12 for forcibly feeding the spinning dope excessively supplied to the nozzle block to the spinning dope main tank 1 is connected to the top part of the nozzle block 4.
The spinning dope discharger 12 forcibly feeds the spinning dope excessively supplied into the nozzle block to the spinning dope main tank 1 by suction air.
A heater (not shown) of direct heating type or indirect heating type is installed (attached) to the collector 7 of the present invention, and the collector is fixed or continuously rotates.
Next, the process of preparing a conjugate nanofiber non-woven fabric using the conjugate electrospinning devices of the present invention will be described with reference to FIG. 1.
Firstly, two kinds of thermoplastic or thermosetting resin spinning dope respectively stored in the two main tanks 1 and 1′ are measured by the respective metering pumps 2 and 2′, and quantitatively supplied to the respective spinning dope drop devices 3 and 3′. Exemplary thermoplastic or thermosetting resins used to prepare the spinning dopes include polyester resins, acryl resins, phenol resins, epoxy resins, nylon resins, poly(glycolide/L-lactide) copolymers, poly(L-lactide) resins, polyvinyl alcohol resins and polyvinyl chloride resins. A resin molten solution or resin solution may be used as the spinning dopes.
When the spinning dopes supplied to the spinning dope drop devices 3 and 3′ passes through the spinning dope drop devices 3 and 3′, flowing of the spinning dopes is dropped at least once in the mechanism described above. Thereafter, the spinning dopes are supplied to the spinning dope supply plate 4 h of the nozzle block 4 having a high voltage and having the agitator tic installed thereto. The spinning dope drop devices 3 and 3′ serve to prevent electricity from flowing in the spinning dope main tanks 1 and 1′ by intercepting flowing of the spinning dopes.
The nozzle block 4 discharges the respective spinning dopes in a bottom-up fashion through the nozzles aligned alternately in a row in a diagonal direction. The spinning dopes are collected by the collector 7 supplied with the high voltage to prepare a non-woven fabric web.
The spinning dopes fed to the spinning dope supply tube 4 h are discharged to the upper part of the collector 7 through the nozzles 5 to form fibers. At this time, the nanofibers electrospun from the nozzles 5 are widely spread by air sprayed from the air supply nozzles 4 b and collected on the collector 7, and thus the collection area becomes wider and the cumulative density becomes uniform. The excessive spinning dope not fiberized in the nozzles 5 is collected in the overflow removal nozzles 4 a, passes through the overflow temporary storage plate 4 g, and is moved back to the spinning dope supply plate 4 h.
Moreover, the spinning dope excessively supplied to the top part of the nozzle block is forcibly fed to the spinning dope main tanks 1 and 1′ by the spinning dope dischargers 12 and 12′.
Here, to facilitate fiber formation by the electric force, a voltage over 1 kV, more preferably 20 kV is generated by the voltage generator 6 and transmitted to the conductor plate 4 i and the collector 7 installed at the lower end of the nozzle block 4. It is advantageous in productivity to use an endless belt as the collector 7. It is preferable that the collector 7 reciprocates a predetermined distance to the left and right in order to make uniform the density of the non-woven fabric.
The nanofiber web 5 formed on the collector 7 is consecutively processed by an web supporting roller 14, and the prepared non-woven fabric winds on a winding roller 16. Thus, the preparation of the non-woven fabric is finished.
The conjugate nanofiber non-woven fabric prepared by the devices of the present invention can easily satisfy the physical properties suitable for various purposes by adjusting the type and ratio of spinning dope. As a result, the conjugate nanofiber non-woven fabric of the present invention is used for various purposes including artificial leather, medical materials such as hygienic band, filter, artificial blood vessel, etc., winter vest, semiconductor wipers, non-woven fabrics for batteries and so on.
Next, the process of preparing a conjugate nanofiber filament using the conjugate electrospinning devices of the present invention will now be described with reference to FIG. 2.
As shown in FIG. 2, a conjugate nanofiber filament is prepared by firstly preparing a nanofiber web 15 in the same way as in the preparation of the above-described conjugate nanofiber non-woven fabric, twisting the prepared nanofiber web 15 while passing it though an air twisting machine 18, drawing it while sequentially passing it through a first roller 19, a second roller 20 and a third roller 22, and then winding it on a winding roller 16.
Optionally, the prepared nanofiber web may be drawn by a thermosetting machine 21 between the drawing and winding steps.
At this time, the above nanofiber web 15 is in a ribbon form.
In order to prepare a ribbon shaped nanofiber web 15, there is used a method (I) in which the nanofiber web 15 is electrospun at a large width which is the same as the entire width of the collector 7 and then the nanofiber web having the large width is cut by a web cutting machine, or a method (II) in which the nanofiber web 15 is divided at small widths which are the same as the width of the nozzle block 4.

Advantageous Effects

The present invention can mass-produce two or more kinds of high quality nanofibers, and can produce a conjugate nanofiber non-woven fabric and a conjugate nanofiber filament suitable for the physical properties required for each purpose by simple facility and process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a process of preparing a conjugate nanofiber non-woven fabric using the conjugate electrospinning devices in accordance with the present invention;

FIG. 2 is a schematic view illustrating a process of preparing a discontinuous filament composed of conjugate nanofibers using the conjugate electrospinning devices in accordance with the present invention;

FIG. 3 is a pattern diagram illustrating nozzles for spinning two or more different kinds of polymer spinning dope aligned on a nozzle block alternately in a row in a diagonal direction in accordance with the present invention (◯: one spinning dope component, : another spinning dope component);

FIG. 4 is a pattern diagram illustrating nozzles for spinning two or more different kinds of polymer spinning dope aligned on a nozzle block regularly in repetitive units at the same ratio or in different ratios in accordance with the present invention (◯: one spinning dope component, : another spinning dope component);

FIG. 5 is a pattern diagram illustrating nozzles for spinning two or more different kinds of polymer spinning dope, being aligned on a nozzle block alternately in a row in a longitudinal direction and supplying the spinning dope in accordance with the present invention (◯: one spinning dope component, : another spinning dope component);

FIG. 6 is a pattern diagram of the nozzle block 4 in accordance with the present invention;

FIG. 7 is a cross sectional diagram of the nozzle block 4 in accordance with the present invention;

FIG. 8 and FIG. 10 are pattern diagrams illustrating a side of the nozzle 5;

FIG. 9 and FIG. 11 are exemplary views of a plane of the nozzle 5;

FIG. 12( a) is a cross sectional view of a spinning dope drop device 3 in the present invention;

FIG. 12( b) is a perspective view of the spinning dope drop device 3 in the present invention;

FIG. 13 is a strength-elongation graph for each kind (type) of nanofiber non-woven fabric;

FIG. 14 is a tear strength graph for each kind (type) of nanofiber non-woven fabric.

- Explanation of Reference Numerals for Main Parts in the Drawings
1,1′: spinning dope main tank 2,2′: metering pump 3,3′: spinning dope drop device
3 a: filter of spinning dope drop device 3 b: air inletting tube 3 c: spinning dope inducing tube
3 d: spinning dope discharge tube 4: nozzle block 4 a: overflow removal nozzle
4 b: air supply nozzle 4 c: air supply nozzle supporting plate (non-conductive material)
4 d: air storage plate 4 e: overflow removal nozzle supporting plate
4 f: nozzle plate 4 g: overflow temporary storage plate
4 h, 4 h′: spinning dope supply plate 4 i: conductor plate 4 j: heating plate
5: nozzle 6: nanofiber 7: collector (conveyer belt)
8 a, 8 b: collector supporting roller 9: voltage generator 9 b: discharge device
10: nozzle block bilateral reciprocating device 11 a: motor for agitator 11 c
11 b: non-conductive insulating rod 11 c: agitator 12,12′: spinning dope discharger
13: feed pipe 14: web supporting roller 15: nanofiber web
16: winding roller 17: web feed roller 18: air twisting machine
19: first roller 20: second roller 21: thermosetting machine (heater)
22: third roller W: conjugate nanofiber non-woven fabric prepared by Example 1
X: conjugate nanofiber non-woven fabric prepared by Example 2
Y: nanofiber non-woven fabric prepared by Comparative Example 1
Z: nanofiber non-woven fabric prepared by Comparative Example 2
θ: nozzle outlet angle
L: nozzle length Di: nozzle inner diameter Do: nozzle outer diameter
h: distance from upper tip of nozzles to upper tip of air supply nozzles

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is now understood more concretely by comparison between examples of the present invention and comparative examples. However, the present invention is not limited to such examples.

EXAMPLE 1

Poly (ε-caprolactone) polymer (product of Aldrich, USA) having a number average molecular weight of 80,000 was dissolved in a mixed solvent of methylene chloride and N,N-dimethyl formamide (volume ratio: 75/25) at a concentration of 13 wt %, to prepare a spinning dope. The surface tension of the polymer spinning dope was 35 mN/m, the spinning dope viscosity was 35 centipoises at a room temperature, the electric conductivity was 0.02 mS/m, and the permittivity was 90.
Polyurethane resin (Pellethane 2103-80AE of Dow Chemical Company) having a number average molecular weight of 80,000 was dissolved in N,N dimethyl formamide at 8 wt. %.
The two kinds of spinning dopes were stored in the main tanks 1 and 1′, quantitatively measured by the metering pumps 2 and 2′, and supplied to the spinning dope drop devices 3 and 3′, thereby discontinuously changing the flow of the spinning dopes. Thereafter, the spinning dopes were supplied to the nozzle block 4 as shown in FIG. 6, and electrospun in a bottom-up fashion in a fiber shape through the nozzles 5. The spun fibers were collected on the collector 7, to prepare a nanofiber web 15. The prepared nanofiber web 15 passed through the web supporting roller 14, and wound on the winding roller 16, to prepare a conjugate nanofiber non-woven fabric. The nozzles for spinning the two kinds of spinning dopes are aligned on the nozzle block 4 as shown in FIG. 4. Thus, the percentage of the number of nozzles for spinning the poly (ε-caprolactone) spinning dope to the total number of nozzles was 66.7%, and the percentage of the number of nozzles for spinning the polyurethane resin spinning dope was 33.3%. Here, each nozzle block included 9,720 nozzles, and four nozzle blocks were employed, the total number of nozzles was 38,880, the spinning distance was 15 cm, and the nozzle block 4 reciprocates at 2 m/min. An electric heater was installed on the collector 7 and thus the surface temperature of the collector was 35° C. when performing electrospinning. The spinning dope overflowing the top part of the nozzle block 4 during the spinning process was forcibly fed to the spinning dope main tank 1 by using the spinning dope discharger 12 using suction air. The angle θ of the nozzle outlets was 120°, the inner diameter Di of the nozzles was 0.9 mm, and the outer diameter thereof was 1 mm. The inner diameter of the air supply nozzles was 20 mm, the outer diameter thereof was 23 mm, and the distance h from the upper tip of the nozzles 5 to the upper tip of the air supply nozzles 4 b was 8 mm. The air speed was 10 m/ sec. Model CH 50 of Symco Corporation was used as the voltage generator. The strength-elongation graph of the conjugate nanofiber non-woven fabric W thus prepared was shown in FIG. 13, and the tear strength graph thereof was shown in FIG. 14.

EXAMPLE 2

Poly (ε-caprolactone) polymer (product of Aldrich, USA) having a number average molecular weight of 80,000 was dissolved in a mixed solvent of methylene chloride and N,N-dimethyl formamide (volume ratio: 75/25) at a concentration of 13 wt %, to prepare a spinning dope. The surface tension of the polymer spinning dope was 35 mN/m, the spinning dope viscosity was 35 centipoises at a room temperature, the electric conductivity was 0.02 mS/m, and the permittivity was 90.
Polyurethane resin (Pellethane 2103-80AE of Dow Chemical Company) having a number average molecular weight of 80,000 was dissolved in N,N dimethyl formamide at 8 wt. %.
The two kinds of spinning dopes were stored in the main tanks 1 and 1′, quantitatively measured by the metering pumps 2 and 2′, and supplied to the spinning dope drop devices 3 and 3′, thereby discontinuously changing the flow of the spinning dopes. Thereafter, the spinning dopes were supplied to the nozzle block 4 as shown in FIG. 6, and electrospun in a bottom-up fashion in a fiber shape through the nozzles. The spun fibers were collected on the collector 7, to prepare a nanofiber web 15. The prepared nanofiber web 15 passed through the web supporting roller 14, and wound on the winding roller 16, to prepare a conjugate nanofiber non-woven fabric. The nozzles for spinning the two kinds of spinning dopes are aligned on the nozzle block 4 as shown in FIG. 4. Thus, the percentage of the number of nozzles for spinning the poly (ε-caprolactone) spinning dope to the total number of nozzles was 33.3%, and the percentage of the number of nozzles for spinning the polyurethane resin spinning dope was 66.7%. Here, each nozzle block included 9,720 nozzles, and four nozzle blocks were employed, the total number of nozzles was 38,880, the spinning distance was 15 cm and the nozzle block 4 reciprocates at 2 m/min. An electric heater was installed on the collector 7 and thus the surface temperature of the collector was 35° C. when performing electrospinning. The spinning dope overflowing the top part of the nozzle block 4 during the spinning process was forcibly fed to the spinning dope main tank 1 by using the spinning dope discharger 12 using suction air. The angle θ of the nozzle outlets was 120°, the inner diameter Di of the nozzles was 0.9 mm, and the outer diameter thereof was 1 mm. The inner diameter of the air supply nozzles was 20 mm, the outer diameter thereof was 23 mm, and the distance h from the upper tip of the nozzles 5 to the upper tip of the air supply nozzles 4 b was 8 mm. The air speed was 10 m/sec. Model CH 50 of Symco Corporation was used as the voltage generator. The strength-elongation graph of the conjugate nanofiber non-woven fabric X thus prepared was shown in FIG. 13, and the tear strength graph thereof was shown in FIG. 14.

COMPARATIVE EXAMPLE 1

Poly (ε-caprolactone) polymer (product of Aldrich, USA) having a number average molecular weight of 80,000 was dissolved in a mixed solvent of methylene chloride and N,N-dimethyl formamide (volume ratio: 75/25) at a concentration of 13 wt %, to prepare a spinning dope. The surface tension of the polymer spinning dope was 35 mN/m, the spinning dope viscosity was 35 centipoises at a room temperature, the electric conductivity was 0.02 mS/m, and the permittivity was 90.
The spinning dope was stored in the main tank 1 of a typical bottom up type electrospinning devices, quantitatively measured by the metering pump 2, and supplied to the nozzle block 4 having a voltage of 35 kV, and electrospun in a bottom-up fashion in a fiber shape through the nozzles 5. The spun fibers were collected on the collector 7, to prepare a nanofiber web 15. The prepared nanofiber web 15 passed through the web supporting roller 14, and wound on the winding roller 16, to prepare a conjugate nanofiber non-woven fabric. The nozzles for spinning the one kind of spinning dope are diagonally aligned on the nozzle block 4. Here, each nozzle block included 9,720 nozzles, and four nozzle blocks were employed, the total number of nozzles was 38,880, the spinning distance was 15 cm and the discharge amount of one nozzle was 1.2 mg/min, and the nozzle block 4 reciprocates at 2 m/min An electric heater was installed on the collector 7 and thus the surface temperature of the collector was 35° C. when performing electrospinning. The spinning dope overflowing the top part of the nozzle block 4 during the spinning process was forcibly fed to the spinning dope main tank 1 by using the spinning dope discharger 12 using suction air. The angle θ of the nozzle outlets was 120°, the inner diameter Di of the nozzles was 0.9 mm, and the outer diameter thereof was 1 mm. The inner diameter of the air supply nozzles was 20 mm, the outer diameter thereof was 23 mm, and the distance h from the upper tip of the nozzles 5 to the upper tip of the air supply nozzles 4 b was 8 mm. The air speed was 10 m/ sec. Model CH 50 of Symco Corporation was used as the voltage generator. The strength-elongation graph of the conjugate nanofiber non-woven fabric Y thus prepared was shown in FIG. 13, and the tear strength graph thereof was shown in FIG. 14.

COMPARATIVE EXAMPLE 2

Polyurethane resin (Pellethane 2103-80AE of Dow Chemical Company) having a number average molecular weight of 80,000 was dissolved in N,N dimethyl formamide at 8 wt. %.
The spinning dope was stored in the main tank 1 of a typical bottom up type electrospinning devices, quantitatively measured by the metering pump 2, and supplied to the nozzle block 4 having a voltage of 35 kV, and electrospun in a bottom-up fashion in a fiber shape through the nozzles 5. The spun fibers were collected on the collector 7, to prepare a nanofiber web 15. The prepared nanofiber web 15 passed through the web supporting roller 14, and wound on the winding roller 16, to prepare a conjugate nanofiber non-woven fabric. The nozzles for spinning the one kind of spinning dope are diagonally aligned on the nozzle block 4. Here, each nozzle block included 9,720 nozzles, and four nozzle blocks were employed, the total number of nozzles was 38,880, the spinning distance was 15 cm and the discharge amount of one nozzle was 1.2 mg/min, and the nozzle block 4 reciprocates at 2 m/min. An electric heater was installed on the collector 7 and thus the surface temperature of the collector was 35° C. when performing electrospinning. The spinning dope overflowing the top part of the nozzle block 4 during the spinning process was forcibly fed to the spinning dope main tank 1 by using the spinning dope discharger 12 using suction air. The angle θ of the nozzle outlets was 120°, the inner diameter Di of the nozzles was 0.9 mm, and the outer diameter thereof was 1 mm. The inner diameter of the air supply nozzles was 20 mm, the outer diameter thereof was 23 mm, and the distance h from the upper tip of the nozzles 5 to the upper tip of the air supply nozzles 4 b was 8 mm. The air speed was 10 m/ sec. Model CH 50 of Symco Corporation was used as the voltage generator. The strength-elongation graph of the conjugate nanofiber non-woven fabric Z thus prepared was shown in FIG. 13, and the tear strength graph thereof was shown in FIG. 14.

INDUSTRIAL APPLICABILITY

The present invention can be utilized for producing a conjugate nanofiber non-woven fabric and a conjugate nanofiber filament which are used as commodities such as artificial leather, air cleaning filter, wiping cloth, golf glove, wig, etc. and various industrial materials such as artificial filter for dialysis, artificial blood vessel, anti-adhesion agent, artificial bone, etc. because it has physical properties required for each purpose.

Claims

1. A conjugate electrospinning devices, comprising: spinning dope main tanks 1; metering pumps 2; a nozzle block 4; nozzles 5 aligned on the nozzle block; a collector 7 for collecting fibers spun from the nozzle block; and a voltage generator 9 for applying a voltage to the nozzle block and the collector 7, wherein

[I] nozzles for spinning two or more different kinds of spinning dope are aligned on a nozzle block 4 regularly or in random order in repetitive units at the same ratio or in different ratios, aligned in random order at a predetermined ratio, or aligned thereon in random order at a predetermined ratio, or aligned thereon repetitively;

[II] the number of the spinning dope main tanks 1 is two or more; and

[III] a spinning dope drop device 3 is arranged between the spinning dope main tanks 1 and the nozzle block 4.

2. The devices of claim 1, wherein the nozzles for spinning two or more different kinds of polymer spinning dope are aligned on the nozzle block 4 alternately in a row in either transverse, longitudinal or diagonal direction.

3. The devices of claim 1, wherein the outlets of the nozzles 5 aligned on the nozzle block 4 are formed in an upward direction, and the collector 7 is positioned at an upper part of the nozzle block 4.

4. The devices of claim 1, wherein the entire part of the nozzle block 4 reciprocates to the left and right.

5. The devices of claim 1, wherein a heater is installed in the collector 7.

6. The devices of claim 1, wherein an agitator 11 c is installed in the nozzle block 4.

7. The devices of claim 1, wherein a spinning dope discharger 12 for forcibly feeding the spinning dope not spun in the nozzle regions to the spinning dope main tank 1 is formed on the upper part of the nozzle block 4.

8. The devices of claim 1, wherein the collector 7 is fixed or continuously rotates.

9. The devices of claim 1, wherein the outlets of the nozzles 5 are formed in the shape of one or more flared tubes having an angle θ of 90 to 175°.

10. The devices of claim 1, wherein the nozzle block 4 includes: [I] a nozzle plate 4 f on which nozzles 5 for spinning different spinning dopes are aligned regularly or in random order in repetitive units in the same ratio or in different ratios and two or more spinning dope supply plates 4 h and 4 h′ positioned at the lower end of the nozzle plate and for supplying the spinning dope to the nozzles; [II] overflow removal nozzles 4 a surrounding the nozzles 5, an overflow temporary storage plate 4 g connected to the overflow removal nozzles and positioned at the right upper end of the nozzle plate and an overflow removal nozzle supporting plate 4 e positioned at the right upper end of the overflow temporary storage plate and supporting the overflow removal nozzles; [III] air supply nozzles 4 b surrounding the nozzles 5 and the overflow removal nozzles 4 a, an air supply nozzle supporting plate 4 c positioned at the top end of the nozzle block and supporting the air supply nozzles and an air storage plate 4 d positioned at the right lower end of the air supply nozzle supporting plate and supplying air to the air supply nozzles; [IV] a conductor plate 4 i having pins aligned in the same way as the nozzles and positioned at the right lower end of the nozzle plate; and [V] a heating plate 4 j positioned at the right lower end of the spinning dope supply plate.

11. The devices of claim 10, wherein the nozzles for spinning two or more different kinds of polymer spinning dope are aligned on the nozzle block 4 alternately in a row in either transverse, longitudinal or diagonal direction.

12. A conjugate nanofiber non-woven fabric prepared using the conjugate electrospinning devices of claim 1.

13. A discontinuous conjugate nanofiber filament prepared using the conjugate electrospinning devices of claim 1.