U.S. patent application number 12/554784 was filed with the patent office on 2009-12-31 for method of manufacturing a continuous filament by electrospinning and continuous filament manufactured thereby.
Invention is credited to Hak-Yong KIM.
Application Number | 20090324950 12/554784 |
Document ID | / |
Family ID | 37481809 |
Filed Date | 2009-12-31 |
United States Patent
Application |
20090324950 |
Kind Code |
A1 |
KIM; Hak-Yong |
December 31, 2009 |
METHOD OF MANUFACTURING A CONTINUOUS FILAMENT BY ELECTROSPINNING
AND CONTINUOUS FILAMENT MANUFACTURED THEREBY
Abstract
Disclosed are a method of manufacturing a continuous filament by
electrospinning, and a continuous filament manufactured thereby.
Electrospun nano fibers 4 are collected on a collector 7 by
electrically spinning a polymer spinning dope in a spinning dope
main tank 1 onto the collector 7, which is a disk-shaped conductive
material with a high voltage applied thereto and which rotates at a
rotational linear velocity of 5 m/sec or more, through nozzles 2
having a high voltage applied thereto, and then the nano fiber 4
collected on the collector 7 are prepared in the form of a
continuous filament by use of a collecting roller 11, and then the
nano fibers 4 are (I) put in a canvas 14 through a traverse 13, or
(II) dried, drawn, and wound consecutively. The continuous filament
is superior in terms of drawing properties because nano fibers are
arranged well in a filament axis direction, the continuous filament
composed of nano fibers can be prepared by a continuous procedure,
and the prepared continuous filament is useful as materials for
various industrial fields, such as artificial leather, filters, and
so on.
Inventors: |
KIM; Hak-Yong; (Jeonju-si,
KR) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
37481809 |
Appl. No.: |
12/554784 |
Filed: |
September 4, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11916639 |
Dec 5, 2007 |
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PCT/KR2006/000963 |
Mar 16, 2005 |
|
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12554784 |
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Current U.S.
Class: |
428/400 |
Current CPC
Class: |
D01D 5/16 20130101; D01D
7/00 20130101; D01D 5/0076 20130101; Y10T 428/2978 20150115 |
Class at
Publication: |
428/400 |
International
Class: |
D02G 3/22 20060101
D02G003/22 |
Foreign Application Data
Date |
Code |
Application Number |
May 2, 2005 |
KR |
10-2005-036733 |
May 10, 2005 |
KR |
10-2005-038894 |
Claims
1. A continuous filament which has a stress of 100 MPa or more
because nano fibers comprising the continuous filament are arranged
at an angle of 10.degree. or less in the axis direction of the
continuous filament.
2. The continuous filament of claim 1, wherein the nano fibers
comprising the continuous filament have a hollow shape or have
pores formed on the surfaces.
3. The continuous filament of claim 1, wherein the nano fibers
comprising the continuous filament are arranged at an angle of
5.degree. or less in the axis direction of the continuous
filament.
4. The continuous filament of claim 1, wherein a necking stress or
a partial/complete stretched stress-strain curve is shown on a
stress-strain graph.
Description
[0001] This application is a Divisional of co-pending application
Ser. No. 11/916,639, filed on Dec. 5, 2007 and for which priority
is claimed under 35 U.S.C. .sctn. 120. application Ser. No.
11/916,639 is the national phase of PCT International Application
No. PCT/KR2006/000963 filed on Mar. 16, 2009 under 35 U.S.C. .sctn.
371. The entire contents of each of the above-identified
applications are hereby incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to a method of manufacturing a
continuous filament or yarn (hereinafter, commonly referred to as a
"filament") by an electrospinning method and a continuous filament
manufactured thereby, and more particularly, to a method of
manufacturing a continuous filament which is superior in physical
properties and composed of a nano fiber by a continuous procedure
by continuously producing a filament superior in drawing properties
because of nano fibers well arranged in the filament axis
direction, and then putting them in canvas through a traverse
movement or continuously drying, drawing, and winding them.
[0003] 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.
[0004] A filament 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
[0005] 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.
[0006] 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.
[0007] 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.
[0008] As another conventional technique for preparing a nano
fiber, an electrospinning method is suggested in U.S. Pat. No.
4,323,525.
[0009] 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.
[0010] The conventional electrospinning method can produce only a
web or non-woven fabric composed of a nano fiber 1,000 nm or less.
Thus, it is difficult to prepare a continuous filament using the
conventional electrospinning method. Hence, to prepare a continuous
filament, the produced nano fiber web has to be cut to a
predetermined length to produce a staple fiber and this staple
fiber has to be blown and undergone an additional spinning process,
which makes the process complicated.
[0011] 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.
[0012] Meanwhile, as a method for arranging nano fibers in a fiber
axis direction when preparing a filament 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 Vol 16(4), pp 361-366, 2004]. However, this
method has a low possibility of industrialization, and any drawing
force cannot be applied to this method.
[0013] Meanwhile, Korean Patent Application No. 2004-6402 discloses
a process of preparing a filament composed of a nano fiber by
preparing a ribbon-like nano fiber web by electrically spinning a
nano fiber on a roller, twisting it while passing it through an air
twisting machine, and then drawing it. However, this conventional
process is problematic in that the strength of the prepared
filament is low due to poor arrangement of nano fibers in the fiber
axis direction.
[0014] As seen from above, there is a problem that it is not
possible to mass-produce a continuous filament composed of a nano
fiber which is superior in drawing properties due to poor
arrangement of nano fibers in the fiber axis direction by the
conventional techniques known so far.
DETAILED DESCRIPTION OF THE INVENTION
Technical Problems
[0015] The present invention is intended to mass-produce a
continuous filament composed of a nano fiber which is superior in
physical properties with a simple and continuous procedure by
preparing an undrawn filament composed of a nano fiber which is
superior in drawing properties using an electrospinning method, and
then performing a drawing procedure. Additionally, the present
invention is intended to provide a continuous filament of a nano
fiber without any additional spinning process.
[0016] Additionally, the present invention is intended to provide a
continuous filament of a nano fiber which is superior in physical
properties 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
[0017] To solve the above-described problems, there is provided a
method of manufacturing a continuous filament by electrospinning
method, wherein electrospun nano fibers 4 are collected on a
collector 7 by electrically spinning a polymer spinning dope in a
spinning dope main tank 1 onto the collector 7, which is a
disk-shaped conductive material with a high voltage applied thereto
and which rotates at a rotational linear velocity of 5 m/sec or
more, through nozzles 2 having a high voltage applied thereto, and
then the nano fiber 4 collected on the collector 7 are prepared in
the form of a continuous filament by use of a collecting roller 11,
and then the nano fibers 4 are (I) put in a canvas 14 through a
traverse 13, or (II) dried, drawn, and wound consecutively.
[0018] Furthermore, the continuous filament of the present
invention is prepared by the above method, has nano fibers of the
continuous filament arranged at an angle of 10.degree. or less in
the axis direction of the continuous filament, and thus have a
stress of 100 MPa or more.
[0019] Hereinafter, the present invention will be described in
detail with reference to the accompanying drawings.
[0020] First, in the present invention, as shown in FIGS. 1 to 4,
electrospun nano fibers 4 are collected on a collector 7 by
electrically spinning a polymer spinning dope onto the collector 7,
which is a disk-shaped conductive material with a high voltage
applied thereto and which rotates at a rotational linear velocity
of 5 m/sec or more, through nozzles 2 having a high voltage applied
thereto.
[0021] FIGS. 1 to 4 are schematic process diagrams of the present
invention.
[0022] If the rotational linear velocity of the collector is less
than 5 m/sec, the nano fibers collected on the collector are nor
oriented well in the filament (fiber) axis direction, thus
deteriorating the drawing properties of an undrawn filament, and
accordingly deteriorating the physical properties of a final
product.
[0023] The nozzles 2 and the collector 7 are connected to a high
voltage generator 3, and thus have a high voltage applied
thereto.
[0024] The collector 7 may be of a single-layer structure
consisting of one disk-shaped conductive material as shown in FIGS.
1 and 2, or a multi-layer structure consisting of two or more
disk-shaped conductive materials as shown in FIGS. 3 and 4.
[0025] The multi-layer collector 7 has such a structure in which
two or more disk-shaped conductive materials rotating at a
rotational linear velocity of 5 m/sec or more on the same
rotational axis are coupled in an integral or division type.
[0026] Additionally, a nonconductive separating plate 9 is
installed between the disk-shaped conductive materials so that, at
the time of spinning a polymer spinning dope onto the multi-layer
collector 7, nano fibers are not scattered but effectively
collected at lateral sides (h parts) of the respective disk-shaped
conductive materials. A nonconductive plate 6 is attached to the
top surface of the multi-layer collector 7.
[0027] The height (h of FIG. 6) of the disk-shaped conductive
materials comprising the collector 7 is 1 to 100 mm, and more
preferably, 5 to 60 mm.
[0028] If the height (h) of the disk-shaped conductive materials is
less than 1 mm, it is difficult for electrospun nano fibers to be
collected on the disk-shaped conductive materials. If the height
(h) of the disk-shaped conductive materials exceeds 100 mm, the
range of collection of the nano fibers is too wide, which makes it
difficult to draw the nano fibers collected on the disk-shaped
conductive materials in the form of a filament, and which causes
the nano fibers not to be arranged well in the rotary direction of
the disk-shaped conductive materials, thereby deteriorating the
physical properties of the filament.
[0029] Additionally, it is preferable that the nonconductive plate
6 serving to cut off a current flow simultaneously while supporting
the collector is attached to the top surface of the multi-layer
collector 7, and a linear or rod-like conductive material 5 is
installed in the outer circumferential direction from the center
point of the disk-shaped conductive materials comprising the
multi-layer collector 7 in order to improve the orientation of the
nano fibers.
[0030] Additionally, it is preferable that the nonconductive plate
6 serving to cut off a current flow simultaneously while supporting
the collector is attached to the top surface of the multi-layer
collector 7, and a linear or rod-like conductive material 5 is
installed in the outer circumferential direction from the center
point of the multi-layer collector 7 in order to improve the
orientation of the nano fibers.
[0031] The nonconductive material 6 is made of polypropylene,
polyethylene, Teflon, or a polymer which is a mixture thereof.
[0032] The collector 7 rotates by being connected to a rotary motor
10 by connecting rods 8 and 9.
[0033] The polymer spinning dope includes polyester resin, nylon
resin, polysulfone resin, polylactic acid, chitosan, collagen,
cellulose, fibrinogen, a copolymer thereof, a mixture thereof, or a
sol-gel containing a metal component.
[0034] The gist of the present invention is to prepare a filament
composed of nano fibers having superior mechanical properties by
improving the drawing properties of an undrawn filament by
arranging electrospun nano fibers in the fiber axis direction using
the centrifugal force of the collector, which is a rotary body
rotating at a high velocity.
[0035] Generally, it is difficult for the nonwoven fabric or
filament 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 30 cm
or less, which is very slight, it is very difficult to apply a
mechanical force to a narrow space. Hence, the only method of
applying a drawing force is to use air or a centrifugal force.
[0036] In the present invention, nano fibers are arranged side by
side on the collector 7 by electrically spinning a polymer spinning
dope onto the collector 7 rotating at a high velocity, thereby
preparing a filament having superior physical properties.
[0037] As for a fiber prepared by electrospinning, it is a general
phenomenon that crystallization is performed to a considerable
extent. Hence, 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. Therefore, the only method of
suppressing crystalline formation during an electrospinning
procedure is to collect nano fibers prepared by electrospinning on
a collector 7, which is a rotary body rotating at a high velocity,
within a very short time. If the rotational linear velocity of the
collector is low, it is impossible to suppress crystalline
formation. As there occurs a phenomenon that fibers are arranged
side by side in the rotary direction of the collector 7, these
fibers are collected to thus consecutively prepare a filament. The
filament thus-prepared has superior drawing properties because it
has a crystallinity of the undrawn yarn level. If necessary, a
filament composed of nano fibers having superior mechanical
properties can be prepared by performing drawing using a difference
in the linear velocity of a roller.
[0038] Meanwhile, the nozzles 2 are arranged along the
circumferential direction of the collector 7 as shown in FIG.
5.
[0039] FIG. 5 is a plane view of the portion where nozzles are
arranged in FIG. 1.
[0040] Additionally, as shown in FIG. 6, the angle (.theta.)
between the collector 7, which is a disk-shaped conductive
material, and the nozzles 2 is no more than 90.degree. in the
longitudinal direction, i.e., +90 to -90.degree., and more
preferably, no more than 85.degree. in the longitudinal direction,
i.e., +85 to -85.degree..
[0041] If the angle exceeds +90.degree., it is difficult to
electrically spin nano fibers onto the rotating collector 7. If the
angle is less than -90.degree., the spun nano fibers are not
collected well on the collector 7, which may increase scattered
nano fibers.
[0042] As shown in FIG. 6, the nozzles 2 may be arranged
longitudinally in two or more rows at a different angle
(.theta.).
[0043] FIG. 6 is a side view of the collector and the nozzles
showing the nozzles 2 being arranged longitudinally on the
collector in three rows at a different angle (.theta.).
[0044] Furthermore, in the present invention, there is included a
method for preparing a hybrid filament by electrically spinning two
or more types of polymer spinning dopes to respective nozzles
arranged longitudinally in two or more rows.
[0045] The nozzles 2 may be of a dual core-shell structure or a
triple or more core-shell structure.
[0046] The number of the nozzles 2 is one or more, and more
preferably, 100 or more.
[0047] When electrically spinning a polymer spinning dope onto the
disk-shaped collector 7 which is rotating, it is more preferable to
feed a nano fiber isolating solution to the collector 7.
[0048] The nano fiber isolating solution is one or two or more
layers of mixtures selected from water, an organic solvent,
surfactant, and silicon oil.
[0049] Next, as shown in FIGS. 1 to 4, the nano fibers collected on
the collector 7 are prepared in the form of a continuous filament
by use of a collecting roller 11, and then they are (I) put in a
canvas 14 through a traverse 13 as shown in FIG. 1, or (II) dried,
drawn, and wound consecutively, thereby preparing a continuous
filament composed of nano fibers.
[0050] The method as in FIG. 1 is proper for when it is difficult
to perform continuous drawing because the rotational linear
velocity of the collector 7 is too fast, while the method as in
FIG. 2 is suitable for when the degree of elongation of a nano
fiber undrawn filament is high because of the material.
[0051] In case of separate type drawing as in FIG. 2, the nano
fibers collected on the collector 7 are drawn in the form of a
continuous undrawn filament by the collecting roller 11,
unvaporized solvents are vaporized while passing through a drier
15, and then the nano fibers are firstly drawn between a first
drawing roller 16 and a second drawing roller 17.
[0052] At this time, the first drawing roller 16 may be heated if
necessary.
[0053] Continuously, the first drawn filament is secondly drawn
between the second drawing roller 17 and a third drawing roller 19,
and thereafter wound on a winding machine 20, thereby preparing a
continuous filament composed of a nano fiber.
[0054] At this time, thermosetting may be carried by installing a
heater 18 within the second drawing section, or the drawing
procedure may be performed in three or more stages.
[0055] It is possible that nano fiber filaments having a different
component may be prepared, respectively, by electrically spinning
different polymer spinning dopes onto the disk-shaped conductive
materials comprising the multi-layer collector 7, and thereafter,
as shown in FIG. 4, they may be doubled in the collecting roller
11, thereby easily preparing a hybrid filament.
[0056] Additionally, in the present invention, it is also possible
that nano fiber filaments having a different thickness may be
prepared, respectively, by differentiating the height (h) of the
disk-shaped conductive materials comprising the multi-layer
collector 7, and thereafter they may be doubled in the collecting
roller 11.
[0057] At this time, if different polymer spinning dopes are
electrically spun onto the respective disk-shaped conductive
materials, nano fiber filaments having a different thickness and a
different component may be prepared, respectively, and if
necessary, they may be doubled by the collecting roller 11.
[0058] The continuous filament of the present invention prepared in
the above-described process according to the present invention
shows a stress of 100 MPa or more because nano fibers of the
continuous filament are arranged at an angle of 10.degree. or less
in the axis direction of the continuous filament, and shows a
necking stress or a partial/complete stretched stress-strain curve
on a stress-strain graph.
[0059] It is more preferable that the nano fibers of the filament
are arranged at an angle of 5.degree. or less in the axis direction
of the continuous filament.
[0060] The continuous filament of the present invention may have a
hollow shape or have pores formed on the surfaces.
[0061] Particularly, the continuous filament of the present
invention is very superior in physical properties because it is
drawn well.
ADVANTAGEOUS EFFECTS
[0062] The present invention is very superior in terms of physical
properties because the continuous filament is composed of an
aggregate of well-arranged nano fibers. The continuous filament
prepared in the present invention is greatly improved in terms of
physical properties.
BRIEF DESCRIPTION OF THE DRAWINGS
[0063] FIGS. 1 to 4 are schematic views of a process of preparing a
continuous filament according to the present invention;
[0064] FIG. 5 is a plane view of the portion where nozzles are
arranged along the circumferential direction of a collector of FIG.
1;
[0065] FIG. 6 is a side view of the collector and the nozzles
showing three nozzles, each having a different angle .theta.
relative to the horizontal axis of the collector, being arranged
longitudinally in three rows;
[0066] FIG. 7 is an electron micrograph of the surface of the
continuous filament prepared by Example 1;
[0067] FIG. 8 is an electron micrograph of the surface of the
continuous mat prepared by Example 2;
[0068] FIG. 9 is stress-strain curve graphs of the continuous
filaments prepared by Examples 1 and 2 (in which a is a
stress-strain curve graph of the continuous filament prepared by
Example 1, and b is a stress-strain curve graph of the continuous
filament prepared by Example 2);
[0069] FIG. 10 is an electron micrograph of the surface of the
continuous filament prepared by Example 3;
[0070] FIG. 11 is an electron micrograph of the surface of the
continuous mat prepared by Example 5;
[0071] FIG. 12 is an electron micrograph of the surface of the
continuous mat prepared by Example 6;
[0072] FIG. 13 is an electron micrograph of the surface of the
continuous mat prepared by Comparative Example 1;
[0073] FIG. 14 is X-ray wide angle graphs of the continuous
filament depending on a change in the rotational linear velocity of
the collector (in which graph a is an X-ray wide angle graph of the
continuous filament prepared when the collector is not rotated,
graph b is an X-ray wide angle graph of the continuous filament
prepared by Comparative Example 1, graph c is an X-ray wide angle
graph of the continuous filament prepared by Example 3, and graph d
is an X-ray wide angle graph of the continuous filament prepared by
Example 4); and
[0074] FIG. 15 is stress-strain graphs of the filament prepared
according to the rotational velocity of the collector (in which
graph a is a stress-strain graph of the continuous filament
prepared when the collector is not rotated, graph b is a
stress-strain graph of the continuous filament prepared by
Comparative Example 1, and graph c is a stress-strain graph of the
continuous filament prepared by Example 3.
EXPLANATION OF REFERENCE NUMERALS FOR THE MAJOR PARTS IN THE
DRAWINGS
[0075] 1: polymer spinning dope main tank [0076] 2: nozzle [0077]
3: high voltage generator [0078] 4: electrospun nano fiber [0079]
5: linear or rod-like conductive material [0080] 6: nonconductive
plate [0081] 7: collector (disk-shaped conductive material) [0082]
8: nonconductive connecting rod [0083] 9: insulating connecting rod
[0084] 10: rotary motor [0085] 11: collecting roller [0086] 12:
filament [0087] 13: traverse [0088] 14: canvas [0089] 15: drier
[0090] 16: first drawing roller [0091] 17: second drawing roller
[0092] 18: heater [0093] 19: third drawing roller [0094] 20:
winding machine [0095] h: height of collector which is a
disk-shaped conductive material [0096] .theta.: angle between
nozzles and central axis of collector [0097] A, B, C: type of
polymer
BEST MODE FOR CARRYING OUT THE INVENTION
[0098] The present invention is now understood more concretely by
comparison between examples of the present invention and
comparative examples. However, the claims of the present invention
are not limited to such examples.
Example 1
[0099] A polymer spinning dope was prepared by dissolving nylon 6
resin, which has a relative viscosity of 3.2 in a 96% sulfuric acid
solution, in formic acid at a concentration of 15% by weight. The
polymer spinning dope had a surface tension of 49 mN/m, a solution
viscosity of 40 centipoise at an ambient temperature, and an
electrical conductivity of 420 mS/m.
[0100] The prepared spinning dope was electrically spun onto a
collector 7, which is a disk-shaped stainless steel plate having a
high voltage applied thereto and rotating at a rotational linear
velocity of 20 m/sec, through nozzles 2 with a high voltage applied
thereto in the electrospinning method as shown in FIG. 1, thereby
collecting electrospun nano fibers 4 on the collector 7.
[0101] The collector rotates by being connected to a rotary motor
10 by connecting rods 8 and 9, and has a diameter of 1.5 m. The
height (h) of the collector is 25 mm.
[0102] The total number of the nozzles 2 is 900. They are arranged
in 300 matrices in the outer circumference of the collector, and
three rows of three nozzles having an angle (.theta.) of
70.degree., 0.degree., and -70.degree., respectively, relative to
the central axis of the collector are arranged longitudinally in
each matrix. The diameter of the nozzles was 1 mm, and the voltage
thereof was 35 kV.
[0103] At the time of electrospinning, water (nano fiber separating
solution) was fed onto the collector.
[0104] Next, the nano fibers collected on the collector 7 were
collected by collecting roller 11 having a surface velocity of 20
m/min, to prepare a continuous filament 12, and it was put in a
canvas 14 through a traverse 13 moving at regular intervals.
[0105] As a result of evaluating the physical properties of the
prepared continuous filament, the strength was 170 MPa, the degree
of elongation was 25%, and the nano fibers were arranged at an
arrangement angle of 1.6.degree. in the axis direction of the
filament.
[0106] FIG. 7 is an electron micrograph of the surface of the
prepared continuous filament. A stress-strain curve graph of the
prepared continuous filament was as shown in a of FIG. 9.
Example 2
[0107] A continuous filament was prepared under the same procedure
and conditions as in Example 1 except that the rotational linear
velocity of the collector 7 and the surface velocity of the
collecting roller 11 were changed to 10 m/sec, respectively. As a
result of evaluating the physical properties of the prepared
continuous filament, the strength was 140 MPa, the degree of
elongation was 32%, and the nano fibers were arranged at an
arrangement angle of 2.8.degree. in the axis direction of the
filament.
[0108] FIG. 8 is an electron micrograph of the surface of the
prepared continuous filament. A stress-strain curve graph of the
prepared continuous filament was as shown in b of FIG. 9.
Example 3
[0109] A polymer spinning dope was prepared by dissolving a
poly(.epsilon.-caprolactone) polymer (purchased from Aldrich
Chemical Company) having a number 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 polymer spinning dope had a surface tension of 35 mN/m, a
solution viscosity of 250 centipoise at an ambient temperature, an
electrical conductivity of 0.02 mS/m and a permittivity constant of
90.
[0110] The prepared spinning dope was electrically spun onto a
collector 7, which is a disk-shaped stainless steel plate having a
high voltage applied thereto and rotating at a rotational linear
velocity of 10 m/sec, through nozzles 2 with a high voltage applied
thereto in the electrospinning method as shown in FIG. 1, thereby
collecting electrospun nano fibers 4 on the collector 7.
[0111] The collector rotates by being connected to a rotary motor
10 by connecting rods 8 and 9, and has a diameter of 2 m. The
height (h) of the collector is 30 mm.
[0112] The total number of the nozzles 2 is 800. They are arranged
in 400 matrices in the outer circumference of the collector, and
two rows of two nozzles having an angle (.theta.) of 70' and -70',
respectively, relative to the central axis of the collector are
arranged longitudinally in each matrix. The diameter of the nozzles
was 1 mm, and the voltage thereof was 35 kV.
[0113] At the time of electrospinning, water (nano fiber separating
solution) was supplied to the collector.
[0114] Next, the nano fibers collected on the collector 7 were
collected by collecting roller 11 having a surface velocity of 10
m/sec, to prepare a continuous filament, and it was put in a canvas
14 through a traverse 13 moving at regular intervals. As a result
of evaluating the physical properties of the prepared continuous
filament, the strength was 105 MPa, the degree of elongation was
75%, and the nano fibers were arranged at an arrangement angle of
1.8.degree. in the axis direction of the filament. FIG. 10 is an
electron micrograph of the surface of the prepared continuous
filament. A stress-strain curve graph of the prepared continuous
filament was as shown in c of FIG. 15. In addition, an X-ray wide
angle graph of the continuous filament prepared is as shown in c of
FIG. 14. An X-ray wide angle graph of the continuous filament
prepared when the collector is not rotated is as shown in a of FIG.
14. In this case, crystalline is well-developed.
Example 4
[0115] A continuous filament was prepared under the same procedure
and conditions as in Example 3 except that the rotational linear
velocity of the collector was changed to 20 m/sec, respectively. An
X-ray wide angle graph of the prepared continuous filament is as
shown in d of FIG. 14.
[0116] The visibility of crystalline formation was very low in the
continuous filament prepared as shown in the X-ray wide angle (d of
FIG. 14).
Example 5
[0117] 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 a mixed solvent of formic acid/acetic acid (volume
ratio: 70/30) 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.
[0118] The prepared spinning dope was electrically spun onto a
8-layered collector 7, which consists of 8 disk-shaped conductive
materials (stainless steel plates) having a high voltage applied
thereto and rotating at a rotational linear velocity of 20 m/sec on
the same rotational axis, through nozzles 2 with a high voltage
applied thereto in the electrospinning method as shown in FIG. 3,
thereby collecting electrospun nano fibers 4 on the disk-shaped
conductive materials comprising the collector 7. A round dividing
plate 9 made of polypropylene, which is a nonconductive material,
was installed between the disk-shaped conductive materials. The
collector rotates by being connected to a rotary motor 10 by a
connecting rod 8, and has a diameter of 1.2 m. The height (h) of
the disk-shaped conductive materials comprising the collector is 20
mm. The nozzles allocated to each layer were arranged in three rows
in each layer using a round nozzle block. The total number of the
nozzles 2 for each layer is 900. They are arranged in 300 matrices
in the outer circumference of the collector, and three rows of
three nozzles having an angle (.theta.) of 65.degree., 0.degree.,
and -65.degree., respectively, relative to the central axis of the
disk-shaped conductive materials comprising the collector 7 are
arranged longitudinally in each matrix. The total number of the
nozzles used for the spinning apparatus of the present invention
consisting of 8 layers is 7,200. The diameter of the nozzles was 1
mm, and the voltage thereof was 35 kV, and the spinning distance
thereof was 12 cm.
[0119] At the time of electrospinning, water (nano fiber separating
solution) was supplied to the collector.
[0120] Next, the nano fibers collected on the collector 7 were
collected by collecting roller 11 having a surface velocity of 900
m/min, to prepare a continuous filament, and it was put in 8
separate canvases 14 through a traverse 13 moving at regular
intervals. The stress of the prepared filament was 165 MPa, and the
degree of elongation thereof was 26%. A result obtained by taking
an electron micrograph of the surface of the nano fibers is as
shown in FIG. 11, and the arrangement angle relative to the fiber
axis was 1.2.degree..
Example 6
[0121] A polymer spinning dope was prepared by dissolving nylon 6
resin, which has a relative viscosity of 3.2 in a 96% sulfuric acid
solution, in formic acid at a concentration of 15% by weight. The
polymer spinning dope had a surface tension of 50 mN/m, a solution
viscosity of 540 centipoise at an ambient temperature, and an
electrical conductivity of 430 mS/m.
[0122] The prepared spinning dope was electrically spun onto a
8-layered collector 7, which consists of 8 disk-shaped conductive
materials (stainless steel plates) having a high voltage applied
thereto and rotating at a rotational linear velocity of 20 m/sec on
the same rotational axis, through nozzles 2 with a high voltage
applied thereto in the electrospinning method as shown in FIG. 3,
thereby collecting electrospun nano fibers 4 on the disk-shaped
conductive materials comprising the collector 7. A round dividing
plate 9 made of polypropylene, which is a nonconductive material,
was installed between the disk-shaped conductive materials. The
collector rotates by being connected to a rotary motor 10 by a
connecting rod 8, and has a diameter of 1.2 m. The height (h) of
the disk-shaped conductive materials comprising the collector is 20
mm. The nozzles allocated to each layer were arranged in three rows
in each layer using a round nozzle block. The total number of the
nozzles 2 for each layer is 900. They are arranged in 300 matrices
in the outer circumference of the collector, and three rows of
three nozzles having an angle (.theta.) of 65.degree., 0.degree.,
and -65.degree., respectively, relative to the central axis of the
disk-shaped conductive materials comprising the collector are
arranged longitudinally in each matrix. The total number of the
nozzles used for the spinning apparatus of the present invention
consisting of 8 layers is 7,200. The diameter of the nozzles was 1
mm, and the voltage thereof was 35 kV, and the spinning distance
thereof was 12 cm.
[0123] At the time of electrospinning, water (nano fiber separating
solution) was supplied to the collector.
[0124] Next, the nano fibers collected on the collector 7 were
collected by collecting roller 11 having a surface velocity of 720
m/min, to prepare a continuous filament 12, and it was put in 8
separate canvases 14 through a traverse 13 moving at regular
intervals. The stress of the prepared filament was 173 MPa, and the
degree of elongation thereof was 29%. A result obtained by taking
an electron micrograph of the surface of the nano fibers is as
shown in FIG. 12, and the arrangement angle relative to the fiber
axis was 1.3.degree..
Comparative Example 1
[0125] A continuous filament was prepared under the same procedure
and conditions as in Example 3 except that the rotational linear
velocity of the collector was changed to 3 m/sec, respectively. An
electron micrograph of the surface of the prepared filament is as
shown in FIG. 13, and the angle at which the nano fibers were
arranged in the filament axis direction was 15.degree..
[0126] An X-ray wide angle graph of the prepared continuous
filament is as shown in b of FIG. 14.
[0127] It can be seen that crystalline formation is very prominent
in the prepared continuous filament as shown in the X-ray wide
angle graph (b of FIG. 14).
[0128] The stress of the prepared continuous filament was 53 MPa,
the degree of elongation thereof was 68%, and the stress-strain
curve graph thereof was as shown in b of FIG. 15.
INDUSTRIAL APPLICABILITY
[0129] The continuous filament prepared in the present invention is
useful as materials for various industrial fields, such as an
artificial dialyzing filter, artificial vessel, anti-adhesion
agent, artificial bone and so on, as well as daily necessities,
such as artificial leather, air cleaning filters, wiping cloths,
golf gloves, wigs and so on.
* * * * *