WO2006132470A1

WO2006132470A1 - Method of manufacturing continuous mats by electrospinning and mats manufactured thereby

Info

Publication number: WO2006132470A1
Application number: PCT/KR2006/000957
Authority: WO
Inventors: Hak-Yong Kim
Original assignee: Industrial Cooperation Foundation Chonbuk National University
Priority date: 2005-06-10
Filing date: 2006-03-16
Publication date: 2006-12-14

Abstract

Disclosed are a method of manufacturing a continuous mat by electrospinning, and a mat manufactured thereby. Electrospun nano fibers are collected on a collector (3) by electrically spinning a polymer spinning dope in a spinning dope main tank 4 onto the collector (3), which is a cylindrical conductive material with a high voltage applied thereto and which rotates with one side covered by a nozzle block (2), the nozzle block (2) having a high voltage thereto and two or more unit blocks combined in a C-shape, and arranged in a given direction, through nozzles (2a) in the unit blocks of the nozzle block (2), such that the electrospun nano fibers are collected on the collector 3, and the collected nano fibers are separated from the collector (3) in the form of a continuous mat (5) by a feed roller (6) and wound on a winding machine (7). It is possible to prepare a continuous mat having various physical properties because the orientation of the nano fibers can be freely and variously adjusted in a mat axis direction according to a rotational velocity of the collector, and a large quantity of nozzles can be arranged in a given direction of the nozzle block (2) within a narrow space, thereby increasing productivity, making it easy to control a spinning amount, and improving fiber forming properties.

Description

METHOD OF MANUFACTURING CONTINUOUS MATS BY ELECTROSPINNING AND MATS MANUFACTURED THEREBY

TECHNICAL FIELD The present invention relates to a method of manufacturing a continuous mat, nonwoven fabric, or sheet (hereinafter, commonly referred to as a "mat") by electrospinning and a continuous mat manufactured thereby, and more particularly, to a method of manufacturing a continuous mat, which achieves a high yield per unit time even in a very narrow place since a large quantity of nozzles can be arranged within a unit space, and which makes it easy to adjust mechanical properties of the mat because the orientation angle of nano fibers relative to a mat axis can be freely adjusted, by using a nozzle block, which is made by combining two or more unit blocks, arranged in a given direction, in a C-shape.

In the present invention, the nano fiber refers to a fiber having a fiber diameter 1,000 nm or less, and more preferably, 500 nm or less.

A mat composed of a nano fiber can be utilized for artificial leather, filters, diapers, sanitary pads, sutures, antisetting agents, wiping cloths, artificial vessels, bone fixing devices and the like, and in particular, it is very useful for the production of the artificial leather.

BACKGROUND ART As conventional techniques for preparing an ultra fine fiber or

nano fiber suitable for the production of artificial leather, there are

known a sea-island type conjugated spinning method, a division type conjugated spinning method, a blend spinning method and so on.

However, in case of the sea-island type conjugated spinning

method or the blend spinning method, one of two polymer components comprising a fiber must be dissolved and removed for making the ultra

fine fiber. In order to produce artificial leather from the fiber prepared by

these methods, a complex process must be carried out, including melt spinning, nano fiber production, non-woven fabric production, urethane

impregnation and single component dissolution. Nevertheless, it has been impossible to produce a fiber with a diameter 1 ,000 nm or less by the above two methods.

In case of the spit type conjugate spinning method, it has been

problematic in that since two polymer components (for example,

polyester and polyamide) with different dyeing properties co-exist in a fiber, uneven dyeing occurs and an artificial leather production process is complicated. In addition, it has been difficult to produce a fiber with a diameter 2,000 nm or less by the above method. As another conventional technique for preparing a nano fiber, an electrospinning method is suggested in U.S. Patent No. 4,323,525.

In the electrospinning method, a polymer spinning dope in a spinning dope main tank is continuously and constantly fed into a plurality of nozzles, which has a high voltage applied, through a metering

pump. Subsequently, the spinning dope fed to the nozzles is spun and

collected through the nozzles on a collector of an endless belt type having a high voltage, more than 5 kV, thereby producing a fiber web. In the conventional electrospinning method, a spinning distance

(distance between the nozzle and the collector) is so short in an electrospinning process that a method capable of drawing by applying a physical force is restrictive, and thus the mechanical properties are very low. Further, the aforementioned method has been problematic in that the orientation angle of nano fibers relative to a mat axis direction cannot be adjusted, and the yield per unit time is low because it is not possible to arrange a large quantity of nozzles within a narrow space.

Meanwhile, as a method for arranging nano fibers in a fiber axis direction when preparing a mat composed of nano fibers, it has been already explained that fibers are arranged between conductive lines by placing the conductive lines on both sides of a nonconductive material such as quartz and then performing electrospinning thereon [Dan Li, Yuliang Wang, and Younan Xia, Advanced Materials VoI 16(4), pp361-366, 2004]. However, this method has a low possibility of industrialization, and any drawing force cannot be applied to this method .

In the conventional method, it is very difficult to achieve physical properties of 10 MPa from the electrically spun mat.

{] As seen from above, it is impossible to arbitrarily adjust the

arrangement of nano fibers in a mat axis direction by the prior art techniques known up to now, especially, it is very difficult to produce a mat in which nano fibers are arranged at over 30^° in a mat axis direction, and the yield per unit time is low since a large quantity of nozzles cannot be arranged within a narrow space.

Subsequently, in the conventional method, it is not possible to solve the problems of electrospinning, such as a low yield per unit time and low mechanical properties of a product.

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL PROBLEMS

The present invention provides a method of manufacturing a

continuous mat composed of nano fibers by electrospinning, which offers a high yield per unit time and allows easy adjustment of the orientation angle of nano fibers relative to a mat axis direction because a large quantity of nozzles can be arranged even in a narrow space.

Furthermore, the present invention provides a method of manufacturing a continuous mat in which two or more types of nano fibers are arranged in a given direction in an alternating manner by alternately spinning two or more types of polymer spinning dopes soluble in different solvents.

Additionally, the present invention is intended to provide a

A continuous mat of a nano fiber which is superior in physical properties

composed of one or two or more types of nano fibers and is suitable for various industrial materials, such as a filter, diaper, sanitary pad, artificial vessel and so on, as well as artificial leather. ,)

TECHNICAL SOLUTIONS

To solve the above-described problems, there is provided a method of manufacturing a continuous mat by electrospinning, wherein electrospun nano fibers are collected on a collector 3 by electrically spinning a polymer spinning dope in a spinning dope main tank 4 onto the collector 3, which is a cylindrical conductive material with a high voltage applied thereto and which rotates with one side covered by a nozzle block 2, the nozzle block 2 having a high voltage applied thereto and two or more unit blocks combined in a C-shape, and arranged in a given direction, through nozzles 2a in the unit blocks of the nozzle block 2, and then the collected nano fibers are separated from the collector 3 in the form of a continuous mat 5 by a feed roller 6 and wound on a winding machine 7.

Furthermore, the continuous mat of the present invention is manufactured by the above method and composed of nano fibers, and shows a necking stress or a partial /complete stretched stress- strain curve on a stress-strain graph.

Furthermore, the continuous mat of the present invention has nano fibers produced by the above method and composed of different polymers, arranged in an alternating manner in either a transverse, longitudinal, or diagonal direction.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, in the present invention, as shown in FIG. l, electrospun nano fibers are collected on a collector 3 by electrically spinning a polymer spinning dope in a polymer spinning main tank 4 onto the collector 3, which is a cylindrical conductive material and which rotates with one side covered by a nozzle block 2, the nozzle block 2 having a high voltage applied thereto and two or more unit blocks combined in a C-shape, and arranged in a given direction, through nozzles 2a in the unit blocks of the nozzle block 2.

FIG.1 is a schematic process view of the present invention. As shown in FIGS.2 and 3, the nozzle block 2 has a high voltage applied thereto and has one or more unit blocks combined in a C-shape, arranged in an alternating manner in either a transverse, longitudinal, or diagonal direction.

FIGS.2 and 3 are perspective views of the C-shaped nozzle block 2 used in the present invention.

The C-shaped nozzle block 2 is provided with two or more spinning dope storage plates 2d and 2e as shown in FIG.5, and thus distributes and feeds two or more different types of polymer spinning dopes to the

R nozzles 2a in an alternating manner. FIG.5 is a schematic cross sectional view of the C- shaped nozzle block 2. The spinning dope storage plates are separated by a nozzle plate 2c.

Meanwhile, the collector 3 is a cylindrical conductive material, which rotates with one side covered by the nozzle block 2 and which has a high voltage applied thereto.

As above, in the present invention, at the time of electrospinning, the above-explained C-shaped nozzle block 2 and the rotating cylindrical collector 3 are used at the same time. At the time of electrospinning, it is preferable that the nozzle block

2 reciprocates bilaterally in order to uniformly collect nano fibers on the collector 3.

Next, the collected nano fibers are separated from the collector 3 in the form of a continuous mat 5 by using a feed roller 6, and then the nano fibers are wound around a winding machine 7.

The continuous mat 5 separated from the collector 3 may be embossed, dried or drawn before being wound around the winding machine.

Each of the C-shaped nozzle block 2 and the collector 3, which are a cylindrical conductive material, may be in a multilayer form which is divided into two or more layers by a dividing plate which is a non-conductive material.

In a case where the C-shaped nozzle block 2 and the collector 3 are in a multilayer form, they are a dividing type or an integral type, and the length (height) of each of the layers of them may be different from each other.

Meanwhile, in the present invention, as shown in FIG.4, it is also possible to prepare two or more mats simultaneously by using two or more C-shaped nozzle blocks 2 and two or more collectors 3, respectively.

In this case, the same polymer spinning dope may be fed into each of the two or more C-shaped nozzle blocks 2, and it is also possible to prepare mats of different kinds by feeding different polymer spinning dopes.

It is possible to prepare a hybrid mat by laminating the mats of different kinds manufactured simultaneously before winding them.

FIG.4 is a schematic view of a process of preparing a continuous mat using two nozzle blocks and two collectors according to the present invention. Reference numerals in the drawing are omitted.

Moreover, it is also possible to prepare a hybrid mat by laminating the two layers of mats, prepared simultaneously, on both sides of a fiber base before winding them.

The two or more C-shaped nozzle blocks 2 and the two or more collectors 3 may be the same or different from each other in diameter.

The nozzles 2a arranged in the C-shaped nozzle blocks and the collectors 3 are connected to a high voltage generator 1 and have a high voltage applied thereto. Moreover, a non-conductive plate serving to support the collectors

and preventing a current flow are attached onto the upper surface of the

collectors 3. If a certain space is formed at a center portion of the

non-conductive plate for use in order to reduce the weight, a good result

can be obtained.

The non-conductive plate is made of polypropylene, polyethylene,

Teflon, or a combination thereof, i.e., polymer. It is advantageous that

the non-conductive plate has an empty space so as to make rotation

smooth through a motor.

The collector 3 rotates by a rotary motor. If it is desired to

construct the collector in multilayers, it is more preferable to install a

dividing plate (partition), which is a non-conductive material, between

each layer of the collector in order to prevent dispersion of nano fibers

during electrospinning and eliminate the phenomenon of adhesion of

electrospun fibers onto the other layers of the collector.

The height of the collector 3 is properly adjusted according to the

width of the mat to be prepared.

The present invention can solve the limit of mass production,

which is a demerit of general electrospinning, because a large quantity of

nozzles can be arranged within a narrow space. Generally, in case of electrospinning using one nozzle, the discharge amount is 0.6 to 2.0

mg/min, which is very small. Therefore, for mass production, it is very

important to increase production efficiency by arranging a large quantity of nozzles within a narrow space. In this respect, the present invention

has a great advantage.

Meanwhile, the mat prepared in the prior art electrospinning

method is very weak in terms of physical properties. The strength of the

properties of the prior art mat is about 10MPa, which is very low. Due to this, there are restrictions on the use of parts requiring strong properties. The present invention can solve such a problem by adjusting the rotational velocity of the collector 3. Specifically, since the orientation

angle of nano fibers relative to a mat axis can be adjusted by adjusting

the rotational velocity of the collector 3, properties required for various uses can be obtained. For instance, if electrospinning is performed on the collector rotating at 5 m/sec, the orientation angle of nano fibers relative to a mat axis [traveling direction (machine direction) of the mat] is controlled to 3" or less, thereby greatly improving the physical properties

of the mat.

Moreover, in the present invention, it is possible to prepare an isotropic composite mat by manufacturing two or more layers of mats having a different orientation angle of nano fibers relative to a mat axis, respectively, and then laminating them. Within the C-shaped nozzle block 2, the nozzles 2a are arranged linearly in either a transverse, longitudinal, or diagonal direction.

In the present invention, a yield per unit time can be increased by arranging a large quantity of nozzles within a narrow space. The C-shaped nozzle block 2 consists of two or more unit blocks, and the unit

blocks are combined, such that they are arranged in either a transverse,

longitudinal, or diagonal direction as shown in FIGS.2 and 3. Due to this, it is convenient to replace the nozzles, it is easy to do cleaning if it is desired to change the polymer to be used, and at the time of electrospinning, a tailor cone at the tip of the nozzles can be formed stably, thereby improving the nano fiber forming properties.

Meanwhile, the nozzles 2a are arranged on the C-shaped nozzle

block 2 as shown in FIGS.2 and 3, and the length or diameter thereof are

variously adjustable according to a desired width, thickness, etc. of the

mat. Further, the length or diameter of the collector 3 can be freely- selected according to a desired width or thickness of the mat. The C-shaped nozzle block 2 and the collector 3 can be constructed in multilayers as explained above. By dividing the C-shaped nozzle block 2

into more than two layers and feeding polymer spinning dopes having a

different concentration to each layer, mats having a different type of polymer or different thickness of nano fibers can be prepared simultaneously. Further, by laminating them before winding, a hybrid

mat can be prepared easily. Moreover, it is possible to prepare a hybrid mat by a method of feeding polymer spinning dopes, different in kind or concentration, to the unit blocks of the nozzle block 2, respectively.

It is better to place the C-shaped nozzle block 2 on a given frame so as to arbitrarily adjust the distance between the nozzles 2a and the collector 3.

Further, the distance (spinning distance) between the nozzle block 2 and the collector 3 can be adjusted by adjusting the diameter of the nozzle block 2 and of the collector 3.

The polymer spinning dope includes components selected from the group consisting of polyester resin, nylon resin, polysulfone resin, polylactic acid, chitosan, collagen, cellulose, fibrinogen, a copolymer thereof, a sol-gel containing a metal component, a copolymer thereof and a mixture thereof.

The gist of the present invention is to easily control physical properties of the mat by freely adjusting the orientation angle of nano fibers relative to a mat axis direction according to the rotational linear velocity of the nozzle block 2 and of the cylindrical collector 3, the nozzle block 2 having two or more unit blocks, combined in a C-shape, such that they are arranged in an alternating manner in either a transverse, longitudinal, or diagonal direction, and the cylindrical collector 3 rotating with one side covered by the nozzle block 2.

Generally, it is difficult for the mat prepared by electrospinning to have a system capable of applying a physical force during an electrospinning process. Because the distance between the nozzles and the collector is 30cm or less, which is very slight, it is very difficult to apply a mechanical force to a narrow space. In the present invention, nano fibers are arranged in a mat axis direction using a centrifugal force of the collector 3 which is rotating.

In the present invention, a partially or completely drawn mat is prepared by electrically spinning a polymer spinning dope onto a rotating collector 3 through a plurality of nozzles arranged in a C-shaped nozzle block 2 and arranging nano fibers side by side on the collector 3.

As for a fiber prepared by electrospinning, it is a general phenomenon that crystallization is performed to a considerable extent

according to the characteristics of the material. Additionally, the orientation degree of nano fibers relative to a mat axis is very low, thus the mechanical properties are very low and it is very difficult to increase the physical properties through a separate drawing process. The reason of which is because the drawing properties are substantially deteriorated due to formed crystalline and the mechanical properties are very low due to a low orientation degree relative to the mat axis direction. Therefore, it is possible to prepare a mat which suppresses the crystalline formation during an electrospinning process, and which is very superior in physical properties by arranging fibers electrospun at regular intervals in the mat axis direction. If the nano fibers formed in the electrospinning process are collected on the collector 3, which is a cylindrical rotating body, crystalline formation can be suppressed and the nano fibers can be arranged in a row relative to the mat axis, thereby enabling it to prepare a mat which has superior physical properties. If the rotational linear velocity of the collector is too low, it is difficult to suppress crystalline formation, and it is impossible to orient electrospun nano fibers in a row

relative to the mat axis. In the present invention, depending on material, it is possible to obtain a mat having a low crystallinity or having

5 partially/ completely drawn nano fibers oriented well relative to the mat

axis. Therefore, mechanical properties superior than properties obtained by a melt-blown or spun bonding method can be obtained, and if drawing is required, if necessary, a mat composed of nano fibers having

superior mechanical properties can be prepared by performing drawing

10 using a difference in the linear velocity of a roller.

In the present invention, there is prepared a hybrid mat which can show various physical properties by feeding different types of polymer spinning dopes in an alternating manner to nozzles 2a installed at each of unit blocks of a nozzle block 2, and as shown in FIGS.6 and 7, repeating i n nano fibers composed of different types of polymers in an alternating

manner in either a transverse, longitudinal, or diagonal direction of the

mat.

FIGS.6 and 7 are schematic plane views of a continuous mat prepared in the present invention. 0 If it is desired to prepare a mat of a hybrid type being composed of polymers of various width or two or more types, it can be prepared easily by using the above-explained multilayered C-shaped nozzle blocks and

multilayered cylindrical collectors. In the present invention, two or more types of mats having a

different mat width can be prepared by differentiating the length (height)

of each of the layers of the mυltilayered C -shaped nozzle block and of the

multilayered cylindrical collectors, and various types of mats can be prepared by embossing these mats. Additionally, a hybrid mat

composed of mats having a different nano fiber diameter can be prepared

by using two or more types of polymers. As the most representative one,

it is possible to prepare a hybrid mat composed of two types of different

polymers and nano fibers by simultaneously spinning polyurethane onto one layer and nylon onto another layer in the collector 3 and combining

them by use of an embossing roller or the like.

Meanwhile, in the present invention, as shown in FIG.4, a hybrid mat can be prepared by simultaneously preparing two or more sheets of a continuous mat using two or more C-shaped nozzle blocks 2 and two or more collectors 3 and then laminating them. FIG.4 is a schematic

process view according to the above method.

At this time, if a polymer spinning dope of a different polymer type

or concentration is fed to the C-shaped nozzle blocks 2, respectively, it makes it easier to prepare a hybrid mat. If a spinning dope of the same polymer having a different concentration is fed to two or more C-shaped nozzle blocks 2, respectively, a mat composed of nano fibers of two or more types having a different thickness can be prepared. Additionally, if a spinning dope of a different polymer type is fed to

them, respectively, the diameter of nano fibers is varied due to a difference in the type of polymers, thereby enabling preparation of a mat

composed of nano fibers of two or more types having a different diameter and a different polymer type.

For example, in case of nylon 6, the diameter of generally prepared nano fibers is 100 to 300 nm, and in case of polyure thane, the diameter

thereof is 200 to 500 nm. Hence, this makes it very easy to prepare two types of hybrid mats having a different diameter and type of nano fibers.

Furthermore, in the present invention, there is included a process

of preparing a hybrid mat of a side-by-side type in which different polymers are arranged in a regular, repeating manner by supplying two

or more types of polymer spinning dopes to respective nozzles within the same nozzle block in an alternating manner and then electrospinning

them.

The nozzles 2 may be of a dual core-shell structure or a triple or more core- shell structure.

The number of the nozzles 2 is one or more, and more preferably, 100 or more. When electrically spinning a polymer spinning dope onto the cylindrical collector 3 which is rotating, it is more preferable to feed a nano fiber separating solution to the collector 3.

The nano fiber separating solution is one or two or more types of mixtures selected from water, an organic solvent, surfactant, and silicon

oil.

Next, as shown in FIG. l , the nano fibers 2b collected on the

cylindrical collector 3 are separated in the form of a continuous mat 5 by

using a feed roller 6, and then wound around a winding machine 7.

Before winding the separated mat, it may be dried by a drier, drawn in multiple stages by another drawing roller having a different rotational

linear velocity, or heated. A thermoplastic resin or thermosetting resin may be impregnated in the prepared mat.

The continuous mat of the present invention prepared by the

above-described method according to the present invention is composed of nano fibers, and shows a necking stress or a partial/ complete stretched stress-strain curve on a stress-strain graph.

In the continuous mat of the present invention, the nano fibers

composed of different polymers are arranged in an alternating manner in either a transverse, longitudinal, or diagonal direction of the mat.

The nano fibers of the mat of the present invention may have a hollow shape or have pores formed on the surfaces.

Particularly, the continuous mat of the present invention is very superior in physical properties because the nano fibers are arranged at an orientation angle of 10° or less in the mat axis direction.

ADVANTAGEOUS EFECTS The present invention is able to easily adjust the orientation angle of nano fibers relative to a mat axis direction, and offers a high yield per

unit time because a large quantity of nozzles can be arranged even in a narrow space. Accordingly, the present invention can mass produce a nano fiber mat having various physical properties in a continuous process.

Additionally, the present invention can easily produce a hybrid mat composed of nano fibers having a different type of polymer or a different diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG.1 is a schematic view of a process of preparing a continuous mat according to the present invention;

FIGS.2 and 3 are perspective views of a C-shaped nozzle block consisting of a plurality of unit blocks;

FIG.4 is a schematic view of a process of preparing a continuous mat using two nozzle blocks and two collectors according to the present invention;

FIG.5 is a schematic cross sectional view of one of C-shaped nozzle blocks;

FIGS.6 and 7 are schematic plane views of a continuous mat prepared in the present invention;

FI G.8 is an electron micrograph of the surface of the continuous mat prepared by Example 1 ; and

FIG.9 is an electron micrograph of the surface of the continuous mat prepared by Example 2.

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

A polymer spinning dope was prepared by dissolving nylon 66 resin, which has a relative viscosity of 3.0 in a 96% sulfuric acid solution, in formic acid /acetic acid at a concentration of 15% by weight. The polymer spinning dope had a surface tension of 37 mN/m, a solution viscosity of 420 centipoise at an ambient temperature and an electrical conductivity of 340 mS/m.

Then, as shown in FIG. l , the prepared spinning dope was electrically spun onto a cylindrical (stainless steel) collector 3, which is a cylindrical conductive material with a high voltage applied thereto and which rotates at a rotational linear velocity of 10 m/min, with one side covered by a nozzle block 2, the nozzle block 2 having a high voltage applied thereto and 128 unit blocks combined in a C- shape, and arranged in a transverse direction, through nozzles 2a in the unit blocks of the nozzle block 2, such that the electrospun nano fibers were collected

on the collector 3.

The collector rotates by being connected to a rotary motor by a

connecting rod, and the length thereof was 200 cm and the radius thereof

was 185 cm. The radius of the nozzle block 2 was 200 cm, and the

length (mat width direction) thereof was 180 cm. 72 nozzles were arranged in a transverse direction in one unit block of the nozzle block 2,

thus the total number of nozzles in the nozzle block 2 was 12,090. At

the time of electrospinning, the nozzle block 2 was reciprocated

bilaterally at a velocity of 2m/min, thereby making the lamination

density of the nano fibers uniform. The diameter of the nozzles was lmm, the voltage thereof was 35 kV, and the spinning distance thereof was 13 cm.

Additionally, at the time of electrospinning, water (nano fiber

separating solution) was fed to the collector.

Next, the nano fibers collected on the collector were separated in a mat form by using a feed roller 6 and wound on a winding machine 7, thereby preparing a mat having a weight of 0.81 g/m² and a width of 1.6m. A result obtained by taking an electron micrograph of the surface of the prepared mat is as in FIG.8.

Example 2 A polymer spinning dope was prepared by dissolving a polyvinyl alcohol (manufactured by Dongyang Chemical) having a number average molecular weight of 65,000 at a concentration of 6% by weight, which is hereinafter referred to as a "spinning dope A". The spinning dope A had a r> solution viscosity of 240 centipoise at an ambient temperature and an electrical conductivity of 17.6 mS/m.

Another polymer spinning dope (hereinafter, referred to as a "spinning dope B") was prepared by dissolving a poly(ε-caprolactone)

polymer (purchased from Aldrich Chemical Company) having a number

10 average molecular weight of 80,000 in a mixed solvent of methylene chloride/ N, N-dimethyl form amide (volume ratio: 75/25) at a concentration of 13% by weight. The spinning dope B had a surface tension of 35 mN/m, a solution viscosity of 35 centipoise at an ambient temperature, an electrical conductivity of 0.02 mS/m and a permittivity

I h constant of 90.

Then, as shown in FIG. l, the prepared spinning dope A and spinning dope B were fed in an alternating manner to unit blocks within a nozzle block 2, the nozzle block 2 having a high voltage applied thereto and 224 unit blocks combined in a C-shape, and arranged in a diagonal 0 direction, through nozzles 2a in the unit blocks of the nozzle block 2, and then electrically spun onto a cylindrical (stainless steel) collector 3, which is a cylindrical conductive material with a high voltage applied thereto and which rotates at a rotational linear velocity of 10 m/min, with one side covered by the nozzle block 2, through nozzles 2a in each of the unit

blocks, such that the electrospun nano fibers were collected on the

collector 3.

The collector rotates by being connected to a rotary motor by a 5 connecting rod, and the length thereof was 200 cm and the radius thereof was 185 cm. The radius of the nozzle block 2 was 200 cm, and the length (mat width direction) thereof was 180 cm. 20 to 72 nozzles were arranged in a transverse direction in one unit block of the nozzle block 2, thus the total number of nozzles in the nozzle block 2 was 12,000. At

10 the time of electrospinning, the nozzle block 2 was reciprocated bilaterally at a velocity of 2m/min, thereby making the lamination density of the nano fibers uniform. The diameter of the nozzles was lmm, the voltage thereof was 35 kV, and the spinning distance thereof was 13 cm.

1.0 Additionally, at the time of electrospinning, water (nano fiber separating solution) was fed to the collector.

Next, the nano fibers collected on the collector were separated in a mat form by using a feed roller 6 and wound on a winding machine 7, thereby preparing a mat having a weight of 1.02 g/m² and a width of 0 1.6m.

A result obtained by taking an electron micrograph of the surface of the mat in which nano fibers made from the spinning dope A (polyvinyl alcohol) and the spinning dope B (poly caprolactone) were mixed is as in FIG.9.

Example 3

A polymer spinning dope was prepared by dissolving nylon 66 5 resin, which has a relative viscosity of 3.0 in a 96% sulfuric acid solution,

in formic acid/acetic acid at a concentration of 15% by weight. The

polymer spinning dope had a surface tension of 37 mN/m, a solution viscosity of 420 centipoise at an ambient temperature and an electrical

conductivity of 340 mS/m.

10 Then, as shown in FIG. l , the prepared spinning dope was

electrically spun onto a nonwoven fabric (weight: 15 g/m²) passing at a

velocity of 18 m/min over a cylindrical (stainless steel) collector 3, which is a cylindrical conductive material with a high voltage applied thereto and which rotates at a rotational linear velocity of 18 m/min, with one

I f) side covered by a nozzle block 2, the nozzle block 2 having a high voltage

thereto and 160 unit blocks, having a length of 5 cm, combined in a

C-shape, and arranged in a transverse direction, through nozzles 2a in

the unit blocks of the nozzle block 2, such that the electrospun nano

fibers were collected on the collector 3. 0 The collector rotates by being connected to a rotary motor by a connecting rod, and the length thereof was 1.8 m and the radius thereof was 1.85 m. The radius of the nozzle block 2 was 2.0 m, and the length

(mat width direction) thereof was 1.80 m. 160 nozzles were arranged in a transverse direction in one unit block of the nozzle block 2, thus the total number of nozzles in the nozzle block 2 was 1 1 ,520. At the time of

electrospinning, the nozzle block 2 was reciprocated bilaterally at a

velocity of 3m/min, thereby making the lamination density of the nano

fibers uniform. The diameter of the nozzles was lmm, the voltage

thereof was 35 kV, and the spinning distance thereof was 15 cm.

Next, the nonwoven fabric coated with nano fibers is wound on a

winding machine 7 by a feed roller 6, thereby preparing a mat having a

width of 1.6m

As a result of evaluating various physical properties of the prepared mat, the air permeability was 1 1.5 cc/cm²/sec, the pressure drop was 6.2 mmføO, and the filtration efficiency was 99.999%.

In the present invention, various physical properties of the mat (coating mat) coated with nano fibers were evaluated by the following method.

* Air Permeability (cc/ cm² /sec)

It was measured according to the KSK 0570 method.

As the measuring instrument, a Fx 330 tester from Textest was used. The pressure was 125 Pa, and the area measured was 38 cm². • Pressure Drop (mmlibO)

It was measured by a TSI 8110 measuring device from TST.

When passing a flow amount of 32(J per minute through the

surface area of 100cm² of samples, the difference between the pressure before passing through the samples and after passing through the

samples was expressed as a pressure drop.

INDUSTRIAL APPLICABILITY

The nano fiber mat prepared according to the present invention is

useful as materials for various industrial fields, such as an artificial dialyzing filter, artificial vessel, anti-adhesion agent, artificial bone, bottom decoration material, compound material and so on, as well as

daily necessities, such as artificial leather, air cleaning filters, wiping

cloths, golf gloves, wigs and so on.

Claims

WHAT IS CLAIMED IS:

1. A method of manufacturing a continuous mat by electrospinning, wherein electrospun nano fibers are collected on a collector 3 by electrically spinning a polymer spinning dope in a spinning dope main tank 4 onto the collector 3, which is a cylindrical conductive material with a high voltage applied thereto and which rotates with one side covered by a nozzle block 2, the nozzle block 2 having a high voltage thereto and two or more unit blocks combined in a C-shape, and arranged in a given direction, through nozzles 2a in the unit blocks of the nozzle block 2, and the collected nano fibers are separated from the collector 3 in the form of a continuous mat 5 by a feed roller 6 and wound on a winding machine 7.

2. The method of claim 1 , wherein the nozzle block 2 has one or more unit blocks combined in a C-shape, arranged in an alternating manner in either a transverse, longitudinal, or diagonal direction.

3. The method of claim 1 , wherein two or more types of polymer spinning dopes stored, respectively, in different polymer spinning dope main tanks 4 are fed in an alternating manner to the unit blocks of the nozzle block 2.

4. The method of claim 1, wherein the polymer spinning dope is electrically spun on the mat, passing over the collector 3, through the nozzles 2a.

5. The method of claim 1 , wherein the continuous mat 5 separated from the collector 3 is embossed, dried or drawn before being wound.

6. The method of claim 1, wherein the nozzles 2a in the nozzle block 2 are arranged diagonally or in a row in a transverse or longitudinal direction.

7. The method of claim 1, wherein two or more unit blocks are assembled in a C-shaped frame.

8. The method of claim 1, wherein the nozzle block 2 reciprocates bilaterally.

9. The method of claim 1, wherein the nozzle block 2 is located in the lower part of the collector 3.

10. The method of claim 1 , wherein the nozzles are of a dual core-shell structure or a triple or more core-shell structure.

11. The method of claim 1 , wherein the polymer spinning dope includes components selected from the group consisting of polyester resin, nylon resin, polysulfone resin, polylactic acid, chitosan, collagen, cellulose, fibrinogen, a copolymer thereof, a sol-gel containing a metal

5 component, a copolymer thereof and a mixture thereof.

12. The method of claim 1 , wherein a nano fiber separating solution is fed onto the collector 3 which is a cylindrical conductive material.

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13. The method of claim 12, wherein the nano fiber separating solution is one or two or more types of mixtures selected from water, an organic solvent, surfactant, and silicon oil.

I f) 14. The method of claim 1 , wherein the number of the nozzles 2

is one or more.

15. The method of claim 1 , wherein the number of the nozzles 2 is 100 or more. 0

16. The method of claim 1 , wherein each of the C-shaped nozzle block 2 and the collector 3 are in a multilayer form which is divided into two or more layers by a dividing plate which is a non-conductive material.

17. The method of claim 16, wherein each of the nozzle block 2 and the collector 3 having a multilayered form are an integral type or a dividing type.

18. The method of claim 16, wherein the height of each of the layers of the nozzle block 2 and the collector 3, respectively, is different from each other.

19. The method of claim 1 , wherein two or more mats are simultaneously prepared by using two or more nozzle blocks 2 and two or more collectors 3, respectively.

20. The method of claim 19, wherein two or more different types of polymer spinning dopes are fed to the two or more nozzle blocks

2, respectively.

21. The method of claim 19, wherein the two or more prepared mats are laminated before winding the mats.

22. The method of claim 19, wherein the two or more nozzle blocks 2 are different in diameter from each other.

23. The method of claim 19, wherein the two or more collectors 3 are different in diameter from each other.

24. The method of claim 19, wherein two or more prepared 5 mats are laminated on both sides of a fiber base before winding the mats.

25. A continuous mat manufactured in the method of any one of claims 1 to 24, which is composed of nano fibers, and shows a necking stress or a partial/ complete stretched stress-strain curve on a

10 stress-strain graph.

26. The continuous mat of claim 25, wherein the nano fibers have a hollow shape or have pores formed on the surfaces.

15 27. The continuous mat of claim 25, wherein the nano fibers are arranged at an angle of 10° or less in the axis direction of the continuous mat.

28. The continuous mat of claim 25, wherein a thermoplastic 'ZO resin or thermosetting resin is contained between the nano fibers.

29. The continuous mat of claim 25, wherein the nano fibers composed of different polymers are arranged in an alternating manner in either a transverse, longitudinal, or diagonal direction of the mat.

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