U.S. patent application number 12/954349 was filed with the patent office on 2011-06-02 for spinning apparatus, apparatus and process for manufacturing nonwoven fabric, and nonwoven fabric.
This patent application is currently assigned to JAPAN VILENE COMPANY, LTD.. Invention is credited to Masahiro AMAGASA, Kenji KIMURA, Yukio KOJIMA, Yasuko MATSUBAYASHI.
Application Number | 20110130063 12/954349 |
Document ID | / |
Family ID | 43533224 |
Filed Date | 2011-06-02 |
United States Patent
Application |
20110130063 |
Kind Code |
A1 |
MATSUBAYASHI; Yasuko ; et
al. |
June 2, 2011 |
SPINNING APPARATUS, APPARATUS AND PROCESS FOR MANUFACTURING
NONWOVEN FABRIC, AND NONWOVEN FABRIC
Abstract
Provided are a spinning apparatus capable of stably spinning
fibers having a small fiber diameter with a high productivity, an
apparatus comprising the same for manufacturing a nonwoven fabric,
a process for manufacturing a nonwoven fabric using the nonwoven
fabric manufacturing apparatus, and a nonwoven fabric produced by
the process. The spinning apparatus of the present invention
comprises one or more exits for extruding liquid, which are capable
of extruding a spinning liquid, and one or more exits for ejecting
gas, which extend linearly and are located upstream of each of the
exits for extruding liquid and which are capable of ejecting a gas,
wherein a shearing force by the gas and its accompanying airstream
can be single-linearly exerted on the spinning liquid extruded. The
apparatus of the present invention for manufacturing a nonwoven
fabric comprises a fibers collection means as well as the spinning
apparatus. The process of the present invention for manufacturing a
nonwoven fabric is a process using the apparatus for manufacturing
a nonwoven fabric. The nonwoven fabric of the present invention is
a nonwoven fabric produced by the process.
Inventors: |
MATSUBAYASHI; Yasuko;
(Ibaraki, JP) ; AMAGASA; Masahiro; (Ibaraki,
JP) ; KOJIMA; Yukio; (Tochigi, JP) ; KIMURA;
Kenji; (Ibaraki, JP) |
Assignee: |
JAPAN VILENE COMPANY, LTD.
Tokyo
JP
|
Family ID: |
43533224 |
Appl. No.: |
12/954349 |
Filed: |
November 24, 2010 |
Current U.S.
Class: |
442/400 ;
264/210.2; 425/72.2 |
Current CPC
Class: |
D01D 5/0069 20130101;
D01D 4/025 20130101; D01D 5/14 20130101; Y10T 442/68 20150401; D04H
1/56 20130101; D01D 5/0985 20130101; D04H 3/02 20130101 |
Class at
Publication: |
442/400 ;
425/72.2; 264/210.2 |
International
Class: |
D04H 3/16 20060101
D04H003/16; D01D 5/08 20060101 D01D005/08 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 27, 2009 |
JP |
2009-270011 |
Claims
1. A spinning apparatus comprising one or more exits for extruding
liquid, which are capable of extruding a spinning liquid, and one
or more exits for ejecting gas, which extend linearly and are
located upstream of each of the exits for extruding liquid and
which are capable of ejecting a gas, wherein (1) the spinning
apparatus comprises a columnar hollow for liquid (Hl), in which the
exit for extruding liquid forms one end of the columnar hollow for
liquid, (2) the spinning apparatus comprises a columnar hollow for
gas (Hg) of which one end is the exit for ejecting gas, (3) a
virtual column for liquid (Hvl) which is extended from the columnar
hollow for liquid (Hl) is located adjacent to a virtual column for
gas (Hvg) which is extended from the columnar hollow for gas (Hg),
(4) a central axis of an extruding direction in the columnar hollow
for liquid (Hl) is parallel to a central axis of an ejecting
direction in the columnar hollow for gas (Hg), and (5) when the
columnar hollow for gas and the columnar hollow for liquid are
cross-sectioned with a plane perpendicular to the central axis of
the columnar hollow for gas (Hg), there exists only one straight
line having the shortest distance between an outer boundary of the
cross-section of the columnar hollow for gas (Hg) and an outer
boundary of the cross-section of the columnar hollow for liquid
(Hl).
2. An apparatus for manufacturing a nonwoven fabric, comprising the
spinning apparatus according to claim 1 and a fibers collection
means.
3. A process for manufacturing a nonwoven fabric, using the
apparatus according to claim 2.
4. A nonwoven fabric produced by the process according to claim 3.
Description
TECHNICAL FIELD
[0001] The present invention relates to a spinning apparatus, an
apparatus comprising the same for manufacturing a nonwoven fabric,
a process for manufacturing a nonwoven fabric using the nonwoven
fabric manufacturing apparatus, and a nonwoven fabric produced by
the process.
BACKGROUND ART
[0002] Fibers having a small fiber diameter can impart various
excellent properties, such as a separating property, a
liquid-holding capacity, a wiping property, a shading property, an
insulating property, or flexibility, to a nonwoven fabric, and
therefore, it is preferable that fibers which form a nonwoven
fabric have a small fiber diameter. As a process for manufacturing
such fibers having a small fiber diameter, electrospinning is
known. In this process, a spinning liquid is extruded from a
nozzle, and at the same time, an electrical field is applied to the
extruded spinning liquid to thereby draw the spinning liquid and
thin the diameter of the spinning liquid, and fibers are directly
collected on a fibers collection means to form a nonwoven fabric.
According to the electrospinning, a nonwoven fabric consisting of
fibers having an average fiber diameter of 1 .mu.m or less can be
produced. However, the electrospinning is a method with a poor
productivity, because the amount of spinning liquid extruded is
limited.
[0003] To improve the productivity, patent literature 1 proposes
"an apparatus for forming a non-woven mat of nanofibers by using a
pressurized gas stream includes parallel, spaced apart first (12),
second (22), and third (32) members, each having a supply end (14,
24, 34) and an opposing exit end (16, 26, 36). The second member
(22) is adjacent to the first member (12). The exit end (26) of the
second member (22) extends beyond the exit end (16) of the first
member (12). The first (12) and second (22) members define a first
supply slit (18). The third member (32) is located adjacent to the
first member (12) on the opposite side of the first member (12)
from the second member (22). The first (12) and third (32) members
define a first gas slit (38), and the exit ends (16, 26, 36) of the
first (12), second (22) and third (32) members define a gas jet
space (20). A method for forming a nonwoven mat of nanofibers by
using a pressurized gas stream is also included.", as shown in FIG.
2. This apparatus does not require the application of a high
voltage, and therefore, can be expected to improve the
productivity. However, because flat-shaped first, second, and third
members are arranged parallel to each other in the apparatus, and
the sheet-like pressurized gas stream is applied to a sheet-like
spinning liquid, it is considered that the spinning liquid is
difficult to have a fibrous form and the nonwoven fabric contains a
lot of droplets, and that, if fibers can be obtained, the diameter
of the fibers would become thick.
[0004] As a similar spinning apparatus, patent literature 2
proposes "an apparatus for forming nanofibers by using a
pressurized gas stream comprising a center tube, a first supply
tube that is positioned concentrically around and apart from the
center tube, a middle gas tube positioned concentrically around and
apart from the first supply tube, and a second supply tube
positioned concentrically around and apart from the middle gas
tube, wherein the center tube and first supply tube form a first
annular column, the middle gas tube and the first supply tube form
a second annular column, the middle gas tube and second supply tube
form a third annular column, and the tubes are positioned so that
first and second gas jet spaces are created between the lower ends
of the center tube and first supply tube, and the middle gas tube
and second supply tube, respectively". This apparatus also does not
require the application of a high voltage, and can be expected to
improve the productivity. However, because the columnar or annular
pressurized gas stream is applied to a spinning liquid annularly
extruded, spinning cannot be stably performed, and the spinning
liquid is difficult to have a fibrous form and the nonwoven fabric
contains a lot of droplets.
CITATION LIST
Patent Literature
[0005] [patent literature 1] Japanese Translation Publication
(Kohyo) No. 2005-515316 (Abstract, Table 1, and the like) [patent
literature 2] U.S. Pat. No. 6,520,425 (Abstract, FIG. 2, and the
like)
SUMMARY OF INVENTION
Technical Problem
[0006] An object of the present invention is to solve the above
problems, that is, to provide a spinning apparatus capable of
stably spinning fibers having a small fiber diameter with a high
productivity, an apparatus for manufacturing a nonwoven fabric
comprising this spinning apparatus, a process for manufacturing a
nonwoven fabric using this apparatus for manufacturing a nonwoven
fabric, and a nonwoven fabric produced by the process.
Solution to Problem
[0007] The present invention relates to:
[1] a spinning apparatus comprising one or more exits for extruding
liquid, which are capable of extruding a spinning liquid, and one
or more exits for ejecting gas, which extend linearly and are
located upstream of each of the exits for extruding liquid and
which are capable of ejecting a gas, wherein (1) the spinning
apparatus comprises a columnar hollow for liquid (Hl), in which the
exit for extruding liquid forms one end of the columnar hollow for
liquid, (2) the spinning apparatus comprises a columnar hollow for
gas (Hg) of which one end is the exit for ejecting gas, (3) a
virtual column for liquid (Hvl) which is extended from the columnar
hollow for liquid (Hl) is located adjacent to a virtual column for
gas (Hvg) which is extended from the columnar hollow for gas (Hg),
(4) a central axis of an extruding direction in the columnar hollow
for liquid (Hl) is parallel to a central axis of an ejecting
direction in the columnar hollow for gas (Hg), and (5) when the
columnar hollow for gas and the columnar hollow for liquid are
cross-sectioned with a plane perpendicular to the central axis of
the columnar hollow for gas (Hg), there exists only one straight
line having the shortest distance between an outer boundary of the
cross-section of the columnar hollow for gas (Hg) and an outer
boundary of the cross-section of the columnar hollow for liquid
(Hl), [2] an apparatus for manufacturing a nonwoven fabric,
comprising the spinning apparatus of [1] and a fibers collection
means, [3] a process for manufacturing a nonwoven fabric, using the
apparatus of [2], and [4] a nonwoven fabric produced by the process
of [3].
Advantageous Effects of Invention
[0008] In the spinning apparatus of [1] according to the present
invention, the spinning liquid extruded from each exit for
extruding liquid is close and parallel to the gas ejected from each
exit for ejecting gas, and a shearing force by the gas and its
accompanying airstream can be single-linearly exerted on each
spinning liquid, and thus, fibers of which the fiber diameter is
thinned can be stably spun. Further, because the fibers are spun by
the action of the gas, the amount of spinning liquid extruded can
be increased, and as a result, the fibers can be spun with a high
productivity.
[0009] Because the apparatus for manufacturing a nonwoven fabric of
[2] according to the present invention comprises the fibers
collection means, in addition to the spinning apparatus, a nonwoven
fabric containing fibers having a small fiber diameter can be
stably produced with a high productivity, by capturing the fibers
spun by the spinning apparatus.
[0010] Because the process of [3] according to the present
invention uses the apparatus for manufacturing a nonwoven fabric, a
nonwoven fabric containing fibers having a small fiber diameter can
be stably produced with a high productivity.
[0011] The nonwoven fabric of [4] according to the present
invention is produced by the process, and thus, is a nonwoven
fabric containing fibers having a small fiber diameter.
BRIEF DESCRIPTION OF DRAWINGS
[0012] [FIG. 1]
(a) FIG. 1(a) is a partial perspective view schematically showing
an embodiment of the spinning apparatus of the present invention.
(b) FIG. 1(b) is a partial cross-sectional view taken along plane C
in FIG. 1(a).
[0013] [FIG. 2] FIG. 2 is a cross-sectional view showing a
conventional spinning apparatus.
[0014] [FIG. 3] FIG. 3 is a cross-sectional plane view showing the
arrangement of a conventional nozzle.
[0015] [FIG. 4] FIG. 4 is a partial cross-sectional view showing
another embodiment of the spinning apparatus of the present
invention.
[0016] [FIG. 5] FIG. 5 is a partial cross-sectional view showing
still another embodiment of the spinning apparatus of the present
invention.
[0017] [FIG. 6] FIG. 6 is a partial cross-sectional view showing
still another embodiment of the spinning apparatus of the present
invention.
[0018] [FIG. 7] FIG. 7 is a cross-sectional view schematically
showing an embodiment of the apparatus of the present invention for
manufacturing a nonwoven fabric.
[0019] [FIG. 8] FIG. 8 is a partial cross-sectional view
schematically showing a die for a melt blowing apparatus used in
Comparative Example 2.
DESCRIPTION OF EMBODIMENTS
[0020] The spinning apparatus of the present invention will be
explained with reference to FIG. 1(a) that is a perspective view
schematically showing an embodiment of the spinning apparatus of
the present invention, and FIG. 1(b) that is a cross-sectional view
taken along plane C in FIG. 1(a).
[0021] The spinning apparatus shown in FIG. 1 contains multiple
nozzles for extruding liquid (Nl.sub.1, Nl.sub.2, Nl.sub.3 . . . )
which are arranged in a single and straight line and which have, at
one end thereof, exits for extruding liquid (El.sub.1, El.sub.2,
El.sub.3 . . . ) capable of extruding a spinning liquid, and a
plate for ejecting gas (Pg) having, at one end thereof, an exit for
ejecting gas (Eg) which is capable of ejecting a gas and extends in
a single and straight line; each of the nozzles is directly
contacted with the outer wall of one side of the plate (Pg); and
the exit for ejecting gas (Eg) of the plate for ejecting gas (Pg)
is located upstream of all the exits for extruding liquid
(El.sub.1, El.sub.2, El.sub.3 . . . ) of the nozzles for extruding
liquid (Nl.sub.1, Nl.sub.2, Nl.sub.3 . . . ). The nozzles for
extruding liquid (Nl.sub.1, Nl.sub.2, Nl.sub.3 . . . ) have
columnar hollows for liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . )
containing the exits for extruding liquid (El.sub.1, El.sub.2,
El.sub.3 . . . ) at one end, respectively, and the plate for
ejecting gas (Pg) has a columnar hollow for gas (Hg) of which one
end is the exit for ejecting gas (Eg). Virtual columns for liquid
(Hvl.sub.1, Hvl.sub.2, Hvl.sub.3 . . . ) which are extended from
the columnar hollows for liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . .
), respectively, are located adjacent to a virtual column for gas
(Hvg) which is extended from the columnar hollow for gas (Hg), and
the distance between each virtual column for liquid and the virtual
column for gas corresponds to the sum of the wall thickness of each
nozzle for extruding liquid and the wall thickness of the plate for
ejecting gas (Pg). All the central axes of the extruding direction
(Al.sub.1, Al.sub.2, Al.sub.3 . . . ) of the columnar hollows for
liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ) are parallel to the
central axis of the ejecting direction (Ag) of the columnar hollow
for gas (Hg). When the columnar hollow for gas (Hg) and the
columnar hollows for liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . )
are cross-sectioned with plane C perpendicular to the central axis
of the columnar hollow for gas (Hg), the outer shape of the
cross-section of the columnar hollow for gas (Hg) is rectangular,
and the outer shape of the cross-section of each columnar hollow
for liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ) is circular, and
only a single straight line (L.sub.1, L.sub.2, L.sub.3 . . . )
having the shortest distance between the outer boundary of the
cross-section of the columnar hollow for gas (Hg) and the outer
boundary of the cross-section of each columnar hollow for liquid
(Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ), respectively, can be drawn
at any combination thereof (see FIG. 1(b)).
[0022] In this spinning apparatus as shown in FIG. 1, when a
spinning liquid is supplied to each of the nozzles for extruding
liquid (Nl.sub.1, Nl.sub.2, Nl.sub.3 . . . ) and a gas is supplied
to the plate for ejecting gas (Pg), the spinning liquid flows
through each of the columnar hollows for liquid (Hl.sub.1,
Hl.sub.2, Hl.sub.3 . . . ) and is extruded from each of the exits
for extruding liquid (El.sub.1, El.sub.2, El.sub.3 . . . ) in the
axis directions (Al.sub.1, Al.sub.2, Al.sub.3 . . . ) of the
columnar hollows for liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ),
respectively, and simultaneously, the gas flows through the
columnar hollow for gas (Hg) and is ejected from the exit for
ejecting gas (Eg) in the axis direction of the columnar hollow for
gas (Hg). The ejected gas is adjacent to each extruded spinning
liquid, the central axis of the ejected gas (Ag) is parallel to the
central axis (Al.sub.1, Al.sub.2, Al.sub.3 . . . ) of each extruded
spinning liquid at the closest range of each exit for extruding
liquid (El.sub.1, El.sub.2, El.sub.3 . . . ), and there exists only
a single point having the shortest distance between the ejected gas
and each of the extruded spinning liquids on plane C at any
combination, that is, each spinning liquid is single-linearly
subjected to the shearing action of the gas and the accompanying
airstream, and therefore, each spinning liquid is spun in each axis
direction (Al.sub.1, Al.sub.2, Al.sub.2 . . . ) of each columnar
hollow for liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ) while the
diameter thereof is thinned, and simultaneously, the spinning
liquid is fiberized.
[0023] Each of the nozzles for extruding liquid (Nl.sub.1,
Nl.sub.2, Nl.sub.2 . . . ) may be any nozzle capable of extruding a
spinning liquid, and the outer shape thereof is not particularly
limited. The outer shape may be, for example, circular, oval,
elliptical, or polygonal (such as triangular, quadrangular, or
hexagonal), and is preferably circular, because the shearing action
of the gas and the accompanying airstream can be single-linearly
exerted on each of the spinning liquids, and generation of droplets
can be avoided. That is to say, when the nozzles have a circular
outer shape, and the columnar hollow for gas (Hg) and the columnar
hollows for liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ) are
cross-sectioned with plane C perpendicular to the central axis (Ag)
of the columnar hollow for gas (Hg), it is easy to be arranged that
only one straight line (L.sub.1, L.sub.2, L.sub.3 . . . ) having
the shortest distance between the outer boundary of the
cross-section of the columnar hollow for gas (Hg) and the outer
boundary of the cross-section of each columnar hollow for liquid
(Hl.sub.1, Hl.sub.2, Hl.sub.2 . . . ), at any combination of the
columnar hollow for gas and each of the columnar hollows for
liquid, can be drawn, and as a result, the shearing action of the
gas and the accompanying airstream is single-linearly exerted on
each of the extruded spinning liquids, and generation of droplets
can be avoided. The outer shape of each exit for extruding liquid
(El.sub.1, El.sub.2, El.sub.2 . . . ) in the nozzles for extruding
liquid (Nl.sub.1, Nl.sub.2, Nl.sub.3 . . . ) may be the same as, or
different from, those of the others, but it is preferable that all
the outer shapes are circular.
[0024] When the exits for extruding liquid in the nozzles for
extruding liquid have a polygonal shape, it is preferable that
these exits are arranged so that one vertex of each polygon is at
the side of the plate for ejecting gas, because the shearing action
of the gas and the accompanying airstream is single-linearly
exerted on each spinning liquid, and generation of droplets can be
avoided. That is to say, in a case where the nozzles for extruding
liquid are arranged so that, when the columnar hollow for gas (Hg)
and the columnar hollows for liquid (Hl.sub.11, Hl.sub.12,
Hl.sub.13 . . . , Hl.sub.21, Hl.sub.22, Hl.sub.23 . . . ) are
cross-sectioned with plane C perpendicular to the central axis (Ag)
of the columnar hollow for gas (Hg) (see FIG. 6), only one straight
line (L.sub.11, L.sub.12, L.sub.13 . . . , L.sub.21, L.sub.22,
L.sub.23 . . . ) having the shortest distance between the outer
boundary of the cross-section of the columnar hollow for gas (Hg)
and the outer boundary of the cross-section of each of the columnar
hollows for liquid (Hl.sub.11, Hl.sub.12, Hl.sub.13 . . . ,
Hl.sub.21, Hl.sub.22, Hl.sub.23 . . . ), respectively, can be
drawn, the shearing action of the gas and the accompanying
airstream is single-linearly exerted on each of the spinning
liquids, and as a result, stable spinning can be performed, and
generation of droplets can be avoided.
[0025] The size of each of the exits for extruding liquid
(El.sub.1, El.sub.2, El.sub.3 . . . ) in the nozzles for extruding
liquid (Nl.sub.1, Nl.sub.2, Nl.sub.3 . . . ) is not particularly
limited, but is preferably 0.01 to 20 mm.sup.2, more preferably
0.01 to 2 mm.sup.2 in all the exits. When the size is less than
0.01 mm.sup.2, it tends to become difficult to extrude a spinning
liquid having a high viscosity. When the size is more than 20
mm.sup.2, it tends to become difficult to single-linearly exert the
action of the gas and the accompanying airstream on the spinning
liquid, and therefore, it tends to become difficult to be stably
spun. The size of each exit for extruding liquid (El.sub.1,
El.sub.2, El.sub.3 . . . ) may be the same as, or different from,
those of the others. When all the sizes thereof are the same,
fibers of which the fiber diameter is uniform can be easily
spun.
[0026] Each of the nozzles for extruding liquid (Nl.sub.1,
Nl.sub.2, Nl.sub.3 . . . ) may be formed of any material such as a
metal or a resin, and a resin or metal tube may be used as the
nozzles. When the nozzles are formed of a metal, an electrical
field may be applied to the spinning liquid by applying a voltage
to part or the whole of nozzles for extruding liquid. Although FIG.
1 shows cylindrical nozzles for extruding liquid (Nl.sub.1,
Nl.sub.2, Nl.sub.3 . . . ), a nozzle having an acute-angled edge in
which a tip portion is slantingly cut away with a plane may be used
as the nozzles. This nozzle having an acute-angled edge is
advantageous to a spinning liquid having a high viscosity. When the
nozzles having an acute-angled edge are used so that the
acute-angled edge is arranged at the side of the plate for ejecting
gas, each spinning liquid may be effectively subjected to the
shearing action of the gas and the accompanying airstream, and
therefore, may be stably fiberized.
[0027] Although the nozzles for extruding liquid (Nl.sub.1,
Nl.sub.2, Nl.sub.3 . . . ) are arranged so that they are directly
contacted with the outer wall of only one side of the plate for
ejecting gas (Pg) in FIG. 1, further nozzles for extruding liquid
may be arranged, in addition to the nozzles, so that they are
directly contacted with the outer wall of the opposite side of the
plate for ejecting gas (see FIG. 5). This arrangement results in an
increased amount of spinning liquid extruded, and spinning can be
carried out with a higher productivity.
[0028] FIG. 1 shows the plate for ejecting gas (Pg) in which an
exit for ejecting gas (Eg) extends in a single and straight line,
but it is not necessary that the exit for ejecting gas extends in a
single and straight line. The same effects are obtained when the
exit for ejecting gas linearly extends in, for example, a curved
line, a wavy line, a circular line, an X-shaped line, a U-shaped
line, a spiral line, a triangular line, a quadrangular line, and a
combination thereof. FIG. 1 shows the plate for ejecting gas (Pg)
with only one exit for ejecting gas (Eg), but a plate for ejecting
gas (Pg) with two or more exits for ejecting gas, or two sets of
plates for ejecting gas (Pg), may be used, so long as these exits
for ejecting gas extend linearly. The plate for ejecting gas (Pg)
may be a member which surrounds the columnar hollow for gas (Hg),
as shown in FIG. 1, or may be formed by combining two plane member
with a spacer capable of forming a slit (columnar hollow for gas
(Hg)) between the plane members. The latter has an excellent
flexibility, because the width of the slit (the distance in the
direction perpendicular to the direction that the slit extends
linearly) may be freely changed by appropriately selecting the size
of the spacer.
[0029] The length in the direction that the slit (exit for ejecting
gas Eg) extends linearly is not particularly limited, but is
preferably 3 cm or more in terms of the productivity, and is
preferably 4 m or less in terms of the uniformity of the amount of
gas ejected in the length direction. The width of the slit is not
particularly limited, but is preferably 10 mm or less, more
preferably 2 mm or less, and most preferably 0.5 mm or less, so
that the spinning can be carried out using a smaller amount of gas.
The length in the gas-ejecting direction of the columnar hollow for
gas (Hg) in the plate for ejecting gas (Pg) (the length in the
vertical direction in FIG. 1(a)) is not particularly limited, but
is preferably 0.5 mm or more, more preferably 1 mm or more, and
most preferably 5 mm or more, in terms of a stable ejection of gas.
The structure upstream of the columnar hollow for gas (Hg) is not
particularly limited. FIG. 1 shows that the exit for ejecting gas
of the plate for ejecting gas (Pg) forms a plane perpendicular to
the center axis of ejecting direction of gas (Ag) of the plate for
ejecting gas (Pg), but the plane may be inclined.
[0030] The plate for ejecting gas (Pg) may be formed of any
material such as a metal or a resin, and the material is not
particularly limited.
[0031] Because the plate for ejecting gas (Pg) is arranged so that
the exit for ejecting gas (Eg) is located upstream (i.e., at the
side where a spinning liquid is supplied) of each of the exits for
extruding liquid (El.sub.1, El.sub.2, El.sub.3 . . . ) of the
nozzles for extruding liquid (Nl.sub.1, Nl.sub.2, Nl.sub.3 . . . ),
each spinning liquid can be prevented from rising around each
nozzle for extruding liquid. As a result, the exits for extruding
liquid (El.sub.1, El.sub.2, El.sub.3 . . . ) are not soiled with
the spinning liquid, and spinning may be carried out over a long
period. The distance between the exit for ejecting gas (Eg) and
each of the exits for extruding liquid (El.sub.1, El.sub.2,
El.sub.3 . . . ) is not particularly limited, but is preferably 10
mm or less, more preferably 5 mm or less. When this distance is
more than 10 mm, the shearing action of the gas and the
accompanying airstream is not sufficiently exerted on the extruded
spinning liquid, and it tends to become difficult to be fiberized.
The lower limit of the distance between the exit for ejecting gas
(Eg) and each of the exits for extruding liquid (El.sub.1,
El.sub.2, El.sub.3 . . . ) is not particularly limited, so long as
the exit for ejecting gas (Eg) does not accord with each of the
exits for extruding liquid (El.sub.1, El.sub.2, El.sub.3 . . .
).
[0032] The distance between the exit for ejecting gas (Eg) and each
of the exits for extruding liquid (El.sub.1, El.sub.2, El.sub.3 . .
. ) may be the same as, or different from, those of the others.
When this distance is the same, the shearing action can be equally
exerted on each spinning liquid to perform stable spinning, and
therefore, it is preferable.
[0033] The columnar hollows for liquid (Hl.sub.1, Hl.sub.2,
Hl.sub.3 . . . ) in the nozzles for extruding liquid are passages
which the spinning liquid flows through, and form the shape of each
spinning liquid when extruded. The columnar hollow for gas (Hg) is
a passage which the gas flows through, and forms the shape of the
gas when ejected.
[0034] The virtual columns for liquid (Hvl.sub.1, Hvl.sub.2,
Hvl.sub.3 . . . ), which are extended from the columnar hollows for
liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ), respectively, are
flight routes of the spinning liquids immediately after being
extruded from the exits for extruding liquid (El.sub.1, El.sub.2,
El.sub.3 . . . ), respectively. The virtual column for gas (Hvg),
which is extended from the columnar hollow for gas (Hg), is an
ejection route of the gas immediately after being ejected from the
exit for ejecting gas (Eg). The distance between each of the
virtual columns for liquid (Hvl.sub.1, Hvl.sub.2, Hvl.sub.3 . . . )
and the virtual column for gas (Hvg) corresponds to the sum of the
wall thickness of each nozzle for extruding liquid and the wall
thickness of the plate for ejecting gas (Pg). These distances are
preferably 2 mm or less, more preferably 1 mm or less. When the
distance is more than 2 mm, the shearing action of the gas and the
accompanying airstream is not sufficiently exerted on the spinning
liquid, and it tends to become difficult to be fiberized.
[0035] Because each of the central axes of the extruding directions
(Al.sub.1, Al.sub.2, Al.sub.3 . . . ) of the columnar hollows for
liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ) is parallel to the
central axis of the ejecting direction (Ag) of the columnar hollow
for gas (Hg), the gas and the accompanying airstream can be
single-linearly exerted on each of the extruded spinning liquids,
and thus, fibers can be stably formed. When these central axes
coincide with each other, for example, in a case where a
cylindrical hollow portion for liquid is covered with a
hollow-cylindrical hollow portion for gas, or in a case where a
cylindrical hollow portion for gas is covered with a
hollow-cylindrical hollow portion for liquid, the shearing action
of the gas and the accompanying airstream cannot be single-linearly
exerted on the spinning liquid, and as a result, the spinning
liquid is not sufficiently fiberized, and a lot of droplets occur.
Alternatively, when these central axes are skew, or intersect with
each other, the shearing action of the gas and the accompanying
airstream is not exerted, or is not uniform if exerted, and thus,
each spinning liquid is not stably fiberized. The term "parallel"
means that the central axes of the extruding directions (Al.sub.1,
Al.sub.2, Al.sub.3 . . . ) of the columnar hollows for liquid
(Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ) and the central axis of the
ejecting direction (Ag) of the columnar hollow for gas (Hg) are
coplanar and parallel. The term "central axis of the extruding (or
ejecting) direction" means a line perpendicular to the centroid of
a cross-section taken along a plane perpendicular to the outer wall
of a virtual column.
[0036] In the spinning apparatus of the present invention, when the
columnar hollow for gas (Hg) and the columnar hollows for liquid
(Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ) are cross-sectioned with
plane C perpendicular to the central axis (Ag) of the columnar
hollow for gas (Hg), only a single straight line (L.sub.1, L.sub.2,
L.sub.3 . . . ) having the shortest distance between the outer
boundary of the cross-section of the columnar hollow for gas (Hg)
and the outer boundary of the cross-section of each of the columnar
hollows for liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ) can be
drawn, at any combination. Because the gas ejected from the
columnar hollow for gas (Hg) and the accompanying airstream
single-linearly act on each of the spinning liquids extruded from
the columnar hollows for liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . .
), the shearing action is single-linearly exerted on each of the
spinning liquids to thereby perform stable spinning without
generation of droplets. For example, when two straight lines can be
drawn, because the shearing action is not stably exerted, for
example, on one point and on another point by turns, droplets occur
and stable spinning cannot be carried out.
[0037] Although not shown in FIG. 1, in a case where the spinning
liquid is prepared by dissolving a polymer in a solvent, the
nozzles for extruding liquid (Nl.sub.1, Nl.sub.2, Nl.sub.3 . . . )
are connected to a reservoir for a spinning liquid (for example, a
syringe, a stainless steel tank, a plastic tank, or a bag made of a
resin, such as a vinyl chloride resin or a polyethylene resin), and
the plate for ejecting gas (Pg) is connected to a gas supply
equipment (for example, a compressor, a gas cylinder, or a blower).
In a case where the spinning liquid is prepared by heat-melting a
polymer, the nozzles for extruding liquid (Nl.sub.1, Nl.sub.2,
Nl.sub.3 . . . ) are connected to a supply equipment such as an
extruder, or a metal syringe heated by a heater, and the plate for
ejecting gas (Pg) is connected to a gas supply equipment (for
example, a compressor, a gas cylinder, or a blower) which is
connected to a heater.
[0038] Although FIG. 1 shows a set of spinning apparatus, two or
more sets of spinning apparatus can be arranged in series or
parallel. The productivity can be improved by arranging two or more
sets of spinning apparatus. FIG. 1 shows the use of the nozzles for
extruding liquid (Nl.sub.1, Nl.sub.2, Nl.sub.3 . . . ), but it is
not necessary to use two or more nozzles for extruding liquid in
the present invention, the present invention includes an embodiment
using one nozzle for extruding liquid. In terms of the
productivity, it is preferable to use 8 or more of the nozzles for
extruding liquid. The distance between adjacent nozzles for
extruding liquid (the distance between the central axes of the
extruding direction of adjacent nozzles for extruding liquid) is
not particularly limited, because it is dependent on the outer
shape of each nozzle for extruding liquid, but it is preferably 30
mm or less, more preferably 5 mm or less, and most particularly 2.5
mm or less, in terms of the productivity. When adjacent nozzles for
extruding liquid are too close to each other, there is a
possibility that a sufficient spinnability cannot be obtained
because the extruded spinning liquids are contacted with each
other, and thus, the distance between the outer walls of adjacent
nozzles for extruding liquid is preferably 0.1 mm or more. Each
distance between adjacent nozzles for extruding liquid may be
regular or irregular, but it is preferable that the nozzles for
extruding liquid are arranged at regular intervals because fibers
can be spun in a uniformly dispersed state and, as a result, a
nonwoven fabric having an excellent uniformity can be produced.
[0039] FIG. 1 shows an embodiment in which the nozzles for
extruding liquid (Nl.sub.1, Nl.sub.2, Nl.sub.3 . . . ) are fixed on
the plate for ejecting gas (Pg), but the present invention may
comprises a means capable of freely adjusting the positions of the
nozzles for extruding liquid (Nl.sub.1, Nl.sub.2, Nl.sub.2 . . . ),
so long as these nozzles comply with the relations as described
above. As shown in FIG. 4 which is a cross-sectional view taken
along a plane perpendicular to the central axis of the columnar
hollow for gas (Hg), a plate for extruding liquid in which holes
for extruding liquid (Hl.sub.1, Hl.sub.2, Hl.sub.3 . . . ) are
bored may be used, instead of the nozzles for extruding liquid
(Nl.sub.1, Nl.sub.2, Nl.sub.3 . . . ) as shown in FIG. 1.
[0040] As shown in FIG. 5 which is a cross-sectional view taken
along a plane perpendicular to the central axis of the columnar
hollow for gas (Hg), the first nozzles for extruding liquid
(Nl.sub.11, Nl.sub.12, Nl.sub.13 . . . ) and the second nozzles for
extruding liquid (Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ) can be
directly contacted to each of both outer walls, respectively, of
the plate for ejecting gas (Pg). As shown in FIG. 6 which is a
cross-sectional view taken along a plane perpendicular to the
central axis of the columnar hollow for gas (Hg), the shapes of the
first exits for extruding liquid (El.sub.11, El.sub.12, El.sub.13 .
. . ) of the first nozzles for extruding liquid (Nl.sub.11,
Nl.sub.12, Nl.sub.13 . . . ) and the second exits for extruding
liquid (El.sub.21, El.sub.22, El.sub.23 . . . ) of the second
nozzles for extruding liquid (Nl.sub.21, Nl.sub.22, Nl.sub.23 . . .
) are not necessary to be circular, but may be polygonal, such as
triangular or quadrangular. As described above, it is not necessary
that all the exits for extruding liquid (El.sub.11, El.sub.12,
El.sub.13 . . . , El.sub.21, El.sub.22, El.sub.23 . . . ) have the
same shape, and nozzles for extruding liquid having extruding exits
with different shapes may be regularly or irregularly arranged. In
the spinning apparatus shown in FIG. 5 or FIG. 6, each of the first
nozzles for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . .
) are opposite to each of the second nozzles for extruding liquid
(Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ), respectively, but it is
not particularly limited to this arrangement, and the first nozzles
and the second nozzles may be regularly or irregularly arranged in
a staggered format. When the nozzles for extruding liquid are
arranged in a staggered format, the fibers spun from the first
nozzles for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . .
) do not completely overlap with those spun from the second nozzles
for extruding liquid (Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ), and
thus, the fibers can be easily spun in a more dispersed state and,
as a result, a nonwoven fabric having a more excellent uniformity
can be easily produced.
[0041] The apparatus of the present invention for manufacturing a
nonwoven fabric comprises a fibers collection means as well as the
spinning apparatus as described above, and thus, a nonwoven fabric
can be produced by collecting fibers. The apparatus of the present
invention manufacturing a nonwoven fabric will be explained with
reference to FIG. 7 which is a cross-sectional view schematically
showing an embodiment thereof.
[0042] The apparatus for manufacturing a nonwoven fabric shown in
FIG. 7 contains a spinning apparatus (1), as shown in FIG. 5, in
which the first nozzles for extruding liquid (Nl.sub.11, Nl.sub.12,
Nl.sub.13 . . . ) and the second nozzles for extruding liquid
(Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ) are arranged on both outer
walls of the plate for ejecting gas (Pg), a fibers collection means
(3) capable of capturing fibers spun from the spinning apparatus,
and a suction apparatus (4) which is located downstream of the
fibers collection means (3) and which is capable of suctioning the
fibers spun from the spinning apparatus. To the spinning apparatus
(1), a first supply equipment for spinning liquid capable of
supplying a spinning liquid to the first nozzles for extruding
liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . . ) and a second supply
equipment for spinning liquid capable of supplying a spinning
liquid the same as or different from the first spinning liquid to
the second nozzles for extruding liquid (Nl.sub.21, Nl.sub.22,
Nl.sub.23 . . . ), as well as a gas supplying equipment capable of
supplying a gas to the plate for ejecting gas (Pg), are
connected.
[0043] In this apparatus for manufacturing a nonwoven fabric, each
spinning liquid is supplied from the first supply equipments for
spinning liquid and the second supply equipment for spinning liquid
to the first nozzles for extruding liquid (Nl.sub.11, Nl.sub.12,
Nl.sub.13 . . . ) and the second nozzles for extruding liquid
(Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ), respectively, and
simultaneously, a gas is supplied from the gas supplying equipment
to the plate for ejecting gas (Pg). Each spinning liquid extruded
from the first nozzles for extruding liquid (Nl.sub.11, Nl.sub.12,
Nl.sub.13 . . . ) and the second nozzles for extruding liquid
(Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ) is drawn and fiberized by
the shearing action of the gas ejected from the plate for ejecting
gas (Pg), and simultaneously, these fibers are flown to the fibers
collection means (3) while being uniformly mixed, and directly
accumulated on the fibers collection means (3) to form a nonwoven
fabric.
[0044] In the apparatus for manufacturing a nonwoven fabric shown
in FIG. 7, because many nozzles for extruding liquid are arranged
with respect to one plate for ejecting gas (Pg), the amount of the
ejected gas can be reduced, the scattering of the accumulated
fibers can be avoided, and a nonwoven fabric having an excellent
uniformity can be produced with a high productivity. Further, this
apparatus is energy-efficient, because the amount of the gas can be
reduced, and a high-capacity suction apparatus (4) is not
required.
[0045] When the fibers are accumulated, because the suction
apparatus (4) is arranged downstream of the fibers collection means
(3), the gas ejected from the plate for ejecting gas (Pg) is
rapidly exhausted, and thus, a nonwoven fabric is not disturbed by
the action of the gas.
[0046] Although the fibers collection means (3) shown in FIG. 7 is
a conveyor, the fibers collection means (3) may be any support
capable of directly accumulating fibers thereon, for example, a
nonwoven fabric, a woven fabric, a knitted fabric, a net, a drum, a
belt, or a flat plate. Because the gas is ejected in the present
invention, it is preferable that an air-permeable fibers collection
means (3) is used and a suction apparatus (4) is arranged on the
opposite side of the fibers collection means (3) from the spinning
apparatus, so that fibers are easily accumulated and the collected
fibers are not disturbed by suction of the gas. In a case where the
suction apparatus (4) is not used, it is not necessary that the
fibers collection means is air-permeable.
[0047] FIG. 7 shows that the fibers collection means (3) is
arranged downstream in the extruding direction of the first nozzles
for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . . ) and
the second nozzles for extruding liquid (Nl.sub.21, Nl.sub.22,
Nl.sub.23 . . . ) (i.e., the direction of gravity), and that the
extruding direction of each spinning liquid is perpendicular to the
surface for capturing fibers of the fibers collection means (3). In
the present invention, however, the extruding direction of the
first nozzles for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13
. . . ) and the second nozzles for extruding liquid (Nl.sub.21,
Nl.sub.22, Nl.sub.23 . . . ) may be parallel to the surface for
capturing fibers of the fibers collection means (3), or may
intersect with the surface for capturing fibers of the fibers
collection means (3). The extruding direction of the first nozzles
for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . . ) and
the second nozzles for extruding liquid (Nl.sub.21, Nl.sub.22,
Nl.sub.23 . . . ) is not particularly limited, and may be the same
as, opposite to, or perpendicular to, the direction of gravity, or
may intersect with the direction of gravity.
[0048] When the fibers collection means (3) is arranged so that the
surface thereof for capturing fibers is opposite to (in particular,
perpendicular to) the exit for ejecting gas (Eg) of spinning
apparatus (1), the distance between the fiber-capturing surface of
the fibers collection means (3) and each of the exits for extruding
liquid (El.sub.11, El.sub.12, El.sub.13 . . . ) of the first
nozzles for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . .
) and the exits for extruding liquid (El.sub.21, El.sub.22,
El.sub.23 . . . ) of the second nozzles for extruding liquid
(Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ) in the spinning apparatus
(1) varies in accordance with the amount of a spinning liquid
extruded or the gas velocity, and is not particularly limited. Each
distance is preferably 50 to 1000 mm in a case where the spinning
liquid is prepared by dissolving a polymer in a solvent, and each
distance is preferably 10 to 1000 mm in a case where the spinning
liquid is prepared by heat-melting a polymer. In the case where the
spinning liquid is prepared by dissolving a polymer in a solvent
and the distance is less than 50 mm, a nonwoven fabric sometimes
cannot be obtained, because fibers are accumulated, while the
solvent contained in the spinning liquid does not completely
evaporate and remains, and the shape of each fiber accumulated
cannot be maintained. In the case where the spinning liquid is
prepared by heat-melting a polymer and the distance is less than 10
mm, the heated gas or the like sometimes affects the fibers
accumulated on the fibers collection means, and thus the fibers is
liable to be melted or fused with each other. In the case where the
spinning liquid is prepared by dissolving a polymer in a solvent or
by heat-melting a polymer and the distance is more than 1000 mm,
the gas flow is liable to be disturbed, and therefore, the fibers
are liable to be broken and scattered.
[0049] The suction apparatus (4) is not particularly limited, but
it is preferable that the gas velocity conditions can be controlled
in accordance with the amount of the gas supplied from a gas supply
equipment or the thickness of a nonwoven fabric to be produced.
[0050] The first or second supply equipment for spinning liquid may
be, for example, a syringe, a stainless steel tank, a plastic tank,
or a bag made of a resin, such as a vinyl chloride resin or a
polyethylene resin in the case where the spinning liquid is
prepared by dissolving a polymer in a solvent, and may be, for
example, an extruder, or a metal syringe heated by a heater in the
case where the spinning liquid is prepared by heat-melting a
polymer. The gas supply equipment may be, for example, a
compressor, a gas cylinder, or a blower in the case where the
spinning liquid is prepared by dissolving a polymer in a solvent,
and may be, for example, a compressor, a gas cylinder, or a blower
of which each is connected to a heater in the case where the
spinning liquid is prepared by heat-melting a polymer.
[0051] Although a set of spinning apparatus (1) is arranged in the
apparatus for manufacturing a nonwoven fabric shown in FIG. 7, the
spinning apparatus arranged is not limited to one set, and two or
more sets of spinning apparatus can be arranged. The productivity
can be improved by arranging two or more sets of spinning
apparatus. In the apparatus for manufacturing a nonwoven fabric
shown in FIG. 7, the spinning apparatus (1) in which the first
nozzles for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . .
) and the second nozzles for extruding liquid (Nl.sub.21,
Nl.sub.22, Nl.sub.23 . . . ) are arranged on both outer walls of
the plate for ejecting gas (Pg), respectively, is used, but a
spinning apparatus in which the nozzles for extruding liquid are
arranged on either of the outer walls of the plate for ejecting gas
(Pg) may be used.
[0052] The apparatus for manufacturing a nonwoven fabric shown in
FIG. 7 does not contain an apparatus for bonding fibers in a
nonwoven fabric, but such an apparatus for bonding fibers in a
nonwoven fabric, for example, an apparatus for adding a binder to a
nonwoven fabric and drying the nonwoven fabric, an apparatus for
heat treatment capable of fusing fibers to each other, or an
apparatus for entangling fibers, may be arranged.
[0053] In the apparatus for manufacturing a nonwoven fabric shown
in FIG. 7, the spinning liquid is fiberized only by the action of
gas ejected from the plate for ejecting gas (Pg), but the
fiberization may be promoted by applying an electrical field to the
spinning liquid, as well as the action of gas. For example, when a
voltage is applied to the first nozzles for extruding liquid
(Nl.sub.11, Nl.sub.12, Nl.sub.13 . . . ) and the second nozzles for
extruding liquid (Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ) and the
fibers collection means (3) is grounded, to generate an electrical
field between the first nozzles for extruding liquid (Nl.sub.11,
Nl.sub.12, Nl.sub.13 . . . ) and the second nozzles for extruding
liquid (N.sub.21, Nl.sub.22, Nl.sub.23 . . . ) and the fibers
collection means (3), the spinning liquid which is liable to become
droplets without extension by the shearing action of gas may be
drawn and fiberized by the action of the electrical field. Further,
the fibers are electrified by the action of the electrical field
and the fibers repel each other, and, as a result, no fiber bundles
in which fibers are adhered to each other are formed and the fibers
can be captured in a state where each fiber is dispersed, and thus,
a nonwoven fabric composed of fibers having a uniform fiber
diameter can be easily produced. When a voltage is applied to the
first nozzles for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13
. . . ) and the second nozzles for extruding liquid (Nl.sub.21,
Nl.sub.22, Nl.sub.23 . . . ), a nonwoven fabric which is bulkier
than that formed by electrospinning can be produced, because a
lower voltage may be used in comparison with conventional
electrospinning.
[0054] As a power supply capable of applying a voltage to the first
nozzles for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . .
) and the second nozzles for extruding liquid (Nl.sub.21,
Nl.sub.22, Nl.sub.23 . . . ), for example, a DC high voltage
generator or a Van De Graaff generator, may be used. The applied
polarity may be positive or negative. The voltage may be applied
to, instead of the first nozzles for extruding liquid (Nl.sub.11,
Nl.sub.12, Nl.sub.13 . . . ) and the second nozzles for extruding
liquid (Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ), wires or the like
which are inserted into each nozzle for extruding liquid. The
voltage may be applied to the fibers collection means (3), and the
first nozzles for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13
. . . ) and the second nozzles for extruding liquid (Nl.sub.21,
Nl.sub.22, Nl.sub.23 . . . ) may be grounded. The voltage may be
applied to both the first nozzles for extruding liquid (Nl.sub.11,
Nl.sub.12, Nl.sub.13 . . . ) and the second nozzles for extruding
liquid (Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ) and the fibers
collection means (3) so that an electrical field may be generated
between the first and second nozzles and the fibers collection
means. A counter electrode may be arranged downstream of the
opposite side of the conveyor from the exit for ejecting gas (Eg),
and the counter electrode may be grounded or a voltage may be
applied to the counter electrode, and an electrical field may be
generated between the counter electrode and the first nozzles for
extruding liquid (Nl.sub.11. Nl.sub.12, Nl.sub.13 . . . ) and the
second nozzles for extruding liquid (Nl.sub.21, Nl.sub.22,
Nl.sub.23 . . . ).
[0055] The electric potential difference between the first nozzles
for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . . ) and
the second nozzles for extruding liquid (Nl.sub.21, Nl.sub.22,
Nl.sub.23 . . . ) and the fibers collection means (3) varies in
accordance with spinning conditions, such as the type of spinning
liquid, the distance between the first nozzles for extruding liquid
(Nl.sub.11, Nl.sub.12, Nl.sub.13 . . . ) and the second nozzles for
extruding liquid (Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ) and the
fibers collection means (3), and the like, and thus, is not
particularly limited, but is preferably 0.05 to 1.5 kV/cm. In a
case where the potential difference is higher than 1.5 kV/cm, a
spinning by the electrical field similar to electrospinning is
dominant to a spinning by the shearing action of gas, but the
uniformity of the nonwoven fabric tends to become poor due to the
action of gas. In a case where the potential difference is lower
than 0.05 kV/cm, the nonwoven fabric tends to contain many
component other than fibers, such as balls of fiber, fiber bundles,
shots, particles, or the like, because the fibers are
insufficiently or weakly electrified.
[0056] Although the apparatus for manufacturing a nonwoven fabric
shown in FIG. 7 is an open system, the apparatus of the present
invention for manufacturing a nonwoven fabric may be a closed
system, for example, by housing the spinning apparatus (1), the
fibers collection means (3), and the suction apparatus (4) in a
spinning container. In a case where the spinning liquid is prepared
by dissolving a polymer in a solvent and the solvent is evaporated
during spinning, the closed system can avoid the diffusion of the
solvent, and the solvent can be sometimes recycled.
[0057] In this case where the members are housed in a spinning
container, it is preferable that a ventilator capable of exhausting
a gas in the spinning container is connected to the spinning
container. In a case where the spinning liquid is prepared by
dissolving a polymer in a solvent, the solvent vapor concentration
in the spinning container becomes progressively higher during
spinning and results in an inhibition of evaporation of the
solvent, and as a result, the unevenness of fiber diameters is
easily generated and it tends to become difficult to be fiberized.
The ventilator is not particularly limited, but may be a fan
located at an exhaust vent. In a case where a gas is supplied from
a gas supply equipment for a container to the spinning container,
such a ventilator is not necessarily required, because the same
amount of gas as the amount supplied can be exhausted only by
arranging an exhaust vent. In a case where a gas is exhausted by a
ventilator, it is preferable that the same amount of gas as the
total amount of gas supplied from the gas supply equipment and the
gas supply equipment for container is exhausted. When the total
amount supplied is different from the amount exhausted, a change in
pressure in the spinning container affects the evaporation rate of
the solvent, and the unevenness of fiber diameters is easily
generated. The suction apparatus (4) may be used as the ventilator,
as well as the suction apparatus.
[0058] In a case where a gas supply equipment for container capable
of supplying a gas of which the temperature and humidity are
controlled is connected to the spinning container, the solvent
vapor concentration in the spinning container can be stabilized,
and fibers in which the unevenness of fiber diameters is small can
be spun. As the gas supply equipment for container, for example, a
propeller fan, a sirocco fan, an air compressor, or a blower, may
be used.
[0059] The process of the present invention for manufacturing a
nonwoven fabric is a process using the above-mentioned apparatus
for manufacturing a nonwoven fabric. In particular, it is
preferable that a gas having a gas velocity of 100 m/sec. or more
is ejected from the exit for ejecting gas (Eg) of the spinning
apparatus (1). Generation of droplets can be avoided, and a
nonwoven fabric containing fibers of which the diameter is uniform
and thinned can be efficiently produced by ejecting the gas having
a gas velocity of 100 m/sec. or more from the exit for ejecting gas
(Eg). The gas is ejected at a gas velocity of, preferably 150
m/sec. or more, more preferably 200 m/sec. or more. The upper limit
of the gas velocity is not particularly limited, so long as
spinning can be stably carried out.
[0060] A gas having such a gas velocity can be ejected by, for
example, supplying the gas to the columnar hollow for gas (Hg) from
a compressor. The gas is not particularly limited, but air, a
nitrogen gas, an argon gas, or the like may be used, and use of air
is economical. The temperature of the gas varies in accordance with
the type of spinning liquid, and is not particularly limited. In a
case where the spinning liquid is prepared by dissolving a polymer
in a solvent, ordinary temperature is economically preferable. In a
case where the spinning liquid is prepared by heat-melting a
polymer, the temperature of the gas at the space where the spinning
liquid is contacted with the gas is preferably from a temperature
100.degree. C. lower than the temperature of the heat-melted
polymer to a temperature 100.degree. C. higher than the temperature
of the heat-melted polymer. When the gas has a temperature lower
than that of the heat-melted polymer, the solidification of the
fibers can be promoted by the cooling action. When the gas has a
temperature higher than that of the heat-melted polymer, the
solidification of the polymer can be inhibited, and the shearing
action of the gas can be applied to the spinning liquid over a long
distance in the flight space (2).
[0061] To the flight space of fibers (2) between the first nozzles
for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . . ) and
the second nozzles for extruding liquid (Nl.sub.21, Nl.sub.22,
Nl.sub.23 . . . ) and the fibers collection means (3), a cooling
gas or the like may be supplied to cool the fibers, and as a
result, the solidification of the fibers may be promoted. To the
flight space of fibers (2) between the first nozzles for extruding
liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . . ) and the second
nozzles for extruding liquid (Nl.sub.21, Nl.sub.22, Nl.sub.23 . . .
) and the fibers collection means (3), a heated gas may be supplied
to heat the fibers or maintain their temperature, and as a result,
the solidification of the fibers may be inhibited.
[0062] A spinning liquid which may be used in the process of the
present invention is not particularly limited, and may be any
liquid prepared by dissolving a desired polymer in a solvent or by
heat-melting a desired polymer.
[0063] For example, as the spinning liquid prepared by dissolving a
polymer in a solvent, a liquid prepared by dissolving one polymer,
or two or more polymers selected from, for example, polyethylene
glycol, partially saponified polyvinyl alcohol, completely
saponified polyvinyl alcohol, polyvinylpyrrolidone, polylactic
acid, polyester, polyglycolic acid, polyacrylonitrile,
polyacrylonitrile copolymer, polymethacrylic acid,
polymethylmethacrylate, polycarbonate, polystyrene, polyamide,
polyimide, polyethylene, polypropylene, polyethersulfone,
polysulfone, fluorocarbon resins (polyvinylidene fluoride,
polyvinylidene fluoride copolymer, and the like), polyurethane,
para- or meta-aramid, or celluloses, in one solvent, or two or more
solvents selected from, for example, water, acetone, methanol,
ethanol, propanol, isopropanol, tetrahydrofuran, dimethylsulfoxide,
1,4-dioxane, pyridine, N,N-dimethylformamide,
N,N-dimethylacetamide, N-methyl-2-pyrrolidone, acetonitrile, formic
acid, toluene, benzene, cyclohexane, cyclohexanone, carbon
tetrachloride, methylene chloride, chloroform, trichloroethane,
ethylene carbonate, diethyl carbonate, or propylene carbonate, may
be used.
[0064] The viscosity (when spinning is carried out) of the spinning
liquid prepared by dissolving a polymer in a solvent is preferably
10 to 10000 mPas, more preferably 20 to 8000 mPas. When the
viscosity is less than 10 mPas, the spinning liquid exhibits a poor
spinnability due to a low viscosity, and it tends to become
difficult to have a fibrous form. When the viscosity is more than
10000 mPas, the spinning liquid is difficult to be drawn, and it
tends to become difficult to have a fibrous form. Therefore, even
if the viscosity at room temperature is more than 10000 mPas, such
a spinning liquid may be used, provided that the viscosity falls
within the preferable range by heating the spinning liquid per se
or the columnar hollows for liquid (Hl.sub.11, Hl.sub.12, Hl.sub.13
. . . , Hl.sub.21, Hl.sub.22, Hl.sub.23 . . . ). By contrast, even
if the viscosity at room temperature is less than 10 mPas, such a
spinning liquid may be used, provided that the viscosity falls
within the preferable range by cooling the spinning liquid per se
or the columnar hollows for liquid (Hl.sub.11, Hl.sub.12, Hl.sub.13
. . . , Hl.sub.21, Hl.sub.22, Hl.sub.23 . . . ). The term
"viscosity" as used herein means a value measured at the
temperature same as that when spinning is carried out, using a
viscometer, when the shear rate is 100 s.sup.-1.
[0065] As a polymer which may compose the spinning liquid prepared
by heat-melting a polymer, for example, polyolefins (polypropylene,
polyethylene, polypropylene-polyethylene copolymer,
polymethylpentene, and the like), polyesters (aliphatic polyesters
and aromatic polyesters), acrylic resins (polyacrylonitrile and
polyacrylonitrile copolymer), celluloses, polyvinyl alcohol,
ethylene-vinyl alcohol copolymer, polyvinyl chloride,
polyvinylidene chloride, polycarbonate, polystyrene, polyurethane,
polylactic acid, polyamides (nylon 6, nylon 66, nylon 12, and nylon
610), polyacetal, aramids, polyether sulfone, polysulfone,
fluorocarbon resins (polyvinylidene fluoride, polyvinylidene
fluoride copolymer, and the like), polyphenylene sulfide, poly
ether ether ketone, or the like, may be used alone, or as a
combination of two or more of these polymers.
[0066] The temperature of the spinning liquid prepared by
heat-melting a polymer when spinning is preferably from the melting
point of the polymer to a temperature 200.degree. C. higher than
the melting point, more preferably from a temperature 20.degree. C.
higher than the melting point to a temperature 100.degree. C.
higher than the melting point. With respect to a
temperature-dependent polymer, when the temperature is higher than
a temperature 200.degree. C. higher than the melting point, a
thermal decomposition of polymer occurs, and the spinning becomes
difficult. The shearing rate to the polymer when spinning is
preferably 1 to 10000 s.sup.-1, more preferably 50 to 5000
s.sup.-1. With respect to a pressure-dependent polymer, when the
shearing rate is less than 1 s.sup.-1, stable extrusion is
difficult, and when the shearing rate is more than 10000 s.sup.-1,
it tends to become difficult to extrude the polymer because a high
extrusion pressure is required. Within the temperature range and
the shearing rate range, the viscosity of the spinning liquid when
spinning of the polymer is preferably 10 to 10000 mPas, more
preferably 20 to 8000 mPas. When the viscosity is less than 10
mPas, the spinning liquid exhibits a poor spinnability due to a low
viscosity, and it tends to become difficult to have a fibrous form.
When the viscosity is more than 10000 mPas, the spinning liquid is
difficult to be drawn, and it tends to become difficult to have a
fibrous form. Therefore, even if the viscosity in melting is more
than 10000 mPas, such a spinning liquid may be used, provided that
the viscosity falls within the preferable range by heating the
spinning liquid per se or the columnar hollows for liquid
(Hl.sub.11, Hl.sub.12, Hl.sub.13 . . . , Hl.sub.21, Hl.sub.22,
Hl.sub.23 . . . ). By contrast, even if the viscosity in melting is
less than 10 mPas, such a spinning liquid may be used, provided
that the viscosity falls within the preferable range by cooling the
spinning liquid per se or the columnar hollow for liquid
(Hl.sub.11, Hl.sub.12, Hl.sub.13 . . . , Hl.sub.21, Hl.sub.22,
Hl.sub.23 . . . ).
[0067] The amount of each spinning liquid extruded from the exits
for extruding liquid (El.sub.11, El.sub.12, El.sub.13 . . . ) of
the first nozzles for extruding liquid (Nl.sub.11, Nl.sub.12,
Nl.sub.13 . . . ) and the exits for extruding liquid (El.sub.21,
El.sub.22, El.sub.23 . . . ) of the second nozzles for extruding
liquid (Nl.sub.21, Nl.sub.22, Nl.sub.23 . . . ) is not particularly
limited, because it varies depending on the viscosity of each
spinning liquid or the gas velocity. Each amount is preferably 0.1
to 100 cm.sup.3/hour. The amount of the spinning liquid extruded
from each nozzle for extruding liquid may be the same as, or
different from, that of the other nozzles for extruding liquid.
When the amounts are the same, fibers having a more uniform fiber
diameter may be spun.
[0068] In the process of the present invention, a nonwoven fabric
in which different types of fibers are mixed can be produced by
extruding spinning liquids from the exits for extruding liquid
(El.sub.11, El.sub.12, El.sub.13 . . . ) of the first nozzles for
extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . . ) and the
exits for extruding liquid (El.sub.21, El.sub.22, El.sub.23 . . . )
of the second nozzles for extruding liquid (Nl.sub.21, Nl.sub.22,
Nl.sub.23 . . . ) under two or more different extruding conditions
to be fiberized. Because the extruding conditions of the first
nozzles for extruding liquid (Nl.sub.11, Nl.sub.12, Nl.sub.13 . . .
) and the second nozzles for extruding liquid (Nl.sub.21,
Nl.sub.22, Nl.sub.23 . . . ) in the spinning apparatus (1) as shown
in FIG. 7 are different, and the gas that acts on these extruded
spinning liquid is the same, different types of fibers can be spun,
and as a result, a nonwoven fabric having an excellent uniformity
in which different types of fibers are mixed can be produced.
[0069] The term "two or more different extruding conditions" as
used herein means that each condition is not completely the same as
the other condition(s), that is, each condition is different from
the other condition(s) in one condition, or two or more conditions.
For example, the shape of the exit for extruding liquid, the size
of the exit for extruding liquid, the distance between the exit for
extruding liquid and the exit for ejecting gas, the amount of a
spinning liquid extruded, the concentration of a spinning liquid,
polymers contained in a spinning liquid, the viscosity of a
spinning liquid, solvents contained in a spinning liquid, the ratio
of polymers contained in a spinning liquid when the spinning liquid
contains two or more polymers, the ratio of solvents contained in a
spinning liquid when the spinning liquid contains two or more
solvents, the temperature of a spinning liquid, the method for
preparing a spinning liquid (for example, a spinning liquid
prepared by dissolving a polymer in a solvent and a spinning liquid
prepared by heat-melting), or the type and/or the amount of an
additive contained in a spinning liquid.
[0070] In the present invention, in addition to the production of a
nonwoven fabric by spinning fibers using the spinning apparatus (1)
as described above and accumulating the fibers, one or more
functions can be imparted to the nonwoven fabric by adding powder,
fibers, and/or a fiber aggregate to fibers which are spun and flown
and mixing them.
[0071] Examples of the powder include activated carbon (for
example, steam activated carbon, alkali-treated activated carbon,
acid-treated activated carbon, or the like), inorganic particles
(for example, manganese dioxide, iron oxide, copper oxide, nickel
oxide, cobalt oxide, zinc oxide, titanium-containing oxide,
zeolite, catalyst supported with ceramics, silica, or the like),
ion exchange resins, and plant seeds.
[0072] Examples of the fibers include regenerated fibers such as
rayon, polynosic, and cupra; semi-synthetic fibers such as acetate
fibers; synthetic fibers such as nylon fibers, vinylon fibers,
vinylidene fibers, polyvinyl chloride fibers, polyester fibers,
acrylic fibers, polyethylene fibers, polypropylene fibers, and
polyurethane fibers; inorganic fibers such as glass fibers and
carbon fibers; plant fibers such as cotton and hemp; and animal
fibers such as wool and silk.
[0073] Examples of the fiber aggregate include any aggregate
containing the same or different types of these fibers. The
aggregation state of the fiber aggregate is not particularly
limited, but may be a state in which fibers are entangled, a state
in which fibers are adhered to each other, a state in which fibers
are fused to each other, a state of strands produced by twisting
fibers, or the like.
[0074] The nonwoven fabric of the present invention is a nonwoven
fabric prepared by the process as described above. Therefore, its
fiber diameter is small and it can be stably produced with a high
productivity. The average fiber diameter of fibers which form the
nonwoven fabric is not particularly limited, but may be 50 to 5000
nm. The average fiber diameter as used herein is the arithmetic
mean of the fiber diameters of 200 fibers. Each fiber diameter is
determined from photographic images of the surface of a nonwoven
fabric, taken using a scanning electron microscope (SEM), with
reference to the scale.
[0075] The mass per unit area of the nonwoven fabric of the present
invention may be 0.1 to 100 g/m.sup.2, and the thickness thereof
may be 1 to 1000 .mu.m. The mass per unit area as used herein means
a value obtained by converting the weight of a nonwoven fabric
sample of 10 cm square into the weight per 1 m.sup.2. The thickness
as used herein means a value measured using a compressive
elasticity thickness gauge, more particularly, a value when 100 gf
of load is applied to 5 cm.sup.2 of load area at a rate of 3
mm/s.
EXAMPLES
[0076] The present invention now will be further illustrated by,
but is by no means limited to, the following Examples.
Example 1
(Preparation of Spinning Liquid)
[0077] Polyacrylonitrile (manufactured by Aldrich) was dissolved in
N,N-dimethylformamide so as to become a concentration of 10 mass %
to prepare a spinning liquid (viscosity (temperature: 25.degree.
C.): 970 mPas).
(Preparation of Apparatus for Manufacturing Nonwoven Fabric)
[0078] A manufacturing apparatus as shown in FIG. 1 comprising the
following parts was prepared.
(1) Supply equipment for spinning liquid: syringe (2) Gas supply
equipment: compressor (3) Nozzles for extruding liquid (Nl.sub.1 to
Nl.sub.19): metal nozzle (3)-1 Exits for extruding liquid (El.sub.1
to El.sub.19): circular, 0.3 mm in diameter (cross-sectional area:
0.07 mm.sup.2) (3)-2 Columnar hollows for liquid (Hl.sub.1 to
Hl.sub.19): cylindrical, 0.3 mm in diameter (3)-3 Outer diameter of
nozzles: 0.55 mm each (3)-4 Number of nozzles: 19 (4) Plate for
ejecting gas (Pg): metal plate (4)-1 Exit for ejecting gas (Eg):
rectangular, 0.5 mm in width and 50 mm in length (4)-2 Columnar
hollow for gas (Hg): rectangular parallelepiped, 0.5 mm in width,
50 mm in length, and 20 mm in height (4)-3 Thickness of plate
members which form the plate for ejecting gas (Pg): 1 mm (4)-4
Number of plate for ejecting gas (Pg): 1 set (4)-5 Positions: All
the exits for extruding liquid (El.sub.1 to El.sub.19) were located
2.5 mm downstream of the exit for ejecting gas (Eg), each outer
wall of the nozzles for extruding liquid was directly contacted
with the outer wall of one side of the plate for ejecting gas (Pg),
and the nozzles for extruding liquid were arranged at regular
intervals so that the distance between adjacent nozzles (distance
between the central axes of an extruding direction) was 2.5 mm. (5)
Distance between each of virtual columns for liquid (Hvl.sub.1 to
Hvl.sub.19) and virtual column for gas (Hvg): 1.125 mm each (6)
Central axes of extruding direction of liquid (Al.sub.1 to
Al.sub.19) and central axis of ejecting direction of gas (Ag):
parallel to each other (7) Number of straight lines having the
shortest distance between the outer boundary of the cross-section
of the columnar hollow for gas (Hg) and each outer boundary of the
cross-sections of the columnar hollows for liquid (Hl.sub.1 to
Hl.sub.19) when the columnar hollow for gas and the columnar
hollows for liquid are cross-sectioned with a plane perpendicular
to the central axis of the columnar hollow for gas (Hg): 1 each (8)
Fibers collection means: net (30 mesh), which was arranged so that
the surface thereof for capturing fibers was perpendicular to the
center axis of the ejecting direction of gas (Ag). (8)-1 Distance
between each of the exits for extruding liquid (El.sub.1 to
El.sub.19) and the surface for capturing fibers: 300 mm (9) Suction
apparatus: suction box (size of suction opening: 80 mm.times.350
mm) (10) Container for spinning: acrylic case having a volume of 1
m.sup.3 (10)-1 Gas supply equipment: precision air generator
(manufactured by Apiste, 1400-HDR)
(Manufacture of Nonwoven Fabric)
[0079] Fibers were accumulated on the fibers collection means (net)
under the following conditions to produce a nonwoven fabric having
a mass per unit area of 5 g/m.sup.2 and a thickness of 50 .mu.m.
The average fiber diameter of the fibers which formed this nonwoven
fabric was 300 nm, and the nonwoven fabric composed of such thin
fibers could be stably produced with a high productivity without
generation of droplets.
(a) Amount of spinning liquid extruded from each nozzle for
extruding liquid (Nl.sub.1 to Nl.sub.19): 3 cm.sup.3/hour/nozzle
(b) Air velocity of air ejected: 250 m/sec. (c) Moving speed of
net: 10 mm/sec. (d) Conditions for suctioning fibers: 30 cm/sec.
(e) Conditions for supplying gas: 25.degree. C., 27% RH, 1
m.sup.3/min.
Comparative Example 1
(Preparation of Spinning Liquid)
[0080] The same spinning liquid as that described in Example 1 was
prepared.
(Preparation of Apparatus for Manufacturing Nonwoven Fabric)
[0081] A spinning apparatus comprising the following parts, which
had the arrangement of a nozzle for extruding liquid (Nl) and a
nozzle for ejecting gas (Ng) as shown in FIG. 3, was prepared.
(1) Supply equipment for spinning liquid: syringe (2) Gas supply
equipment: compressor (3) Nozzle for extruding liquid (Nl): metal
nozzle (3)-1 Exit for extruding liquid (El): circular, 0.3 mm in
diameter (cross-sectional area: 0.07 mm.sup.2) (3)-2 Columnar
hollow for liquid: cylindrical, 0.3 mm in diameter (3)-3 Outer
diameter of nozzle: 0.55 mm (3)-4 Number of nozzles: 1 (4) Nozzle
for ejecting gas (Ng): metal nozzle (4)-1 Exit for ejecting gas
(Eg): circular, 0.8 mm in diameter (cross-sectional area: 0.27
mm.sup.2) (4)-2 Columnar hollow for gas: Cylindrical, 0.8 mm in
diameter (4)-3 Outer diameter of nozzle: 1.0 mm (4)-4 Number of
nozzles: 1 (4)-5 Positions: The nozzles were arranged so that the
exit for ejecting gas was located 5 mm upstream of the exit for
extruding liquid, and the nozzle for ejecting gas and the nozzle
for extruding liquid were concentrically located. As a result, the
exit for ejecting gas has an annular shape having an inner diameter
of 0.55 mm and an outer diameter of 0.8 mm (see FIG. 3). (5)
Distance between virtual column for liquid and virtual column for
gas: 0.125 mm (6) Central axis of extruding direction of liquid and
central axis of ejecting direction of gas: coaxial (7) Number of
straight lines having the shortest distance between the inner
boundary of the cross-section of the columnar hollow for gas and
the outer boundary of the cross-section of the columnar hollow for
liquid when the columnar hollows are cross-sectioned with a plane
perpendicular to the central axis of the columnar hollow for gas:
infinite (8) Fibers collection means: net (30 mesh), arranged so
that the surface thereof for capturing fibers was perpendicular to
the center axis of the ejecting direction of gas (8)-1 Distance
from exit for extruding liquid (El): 300 mm (9) Suction apparatus:
suction box (size of suction opening: 80 mm.times.350 mm) (10)
Container for spinning: acrylic case having a volume of 1 m.sup.3
(10)-1 Gas supply equipment: precision air generator (manufactured
by Apiste, 1400-HDR)
(Manufacture of Nonwoven Fabric)
[0082] Spinning was carried out under the following conditions to
produce a nonwoven fabric, but almost all of extruded spinning
liquids did not have a fibrous form, and a nonwoven fabric was not
obtained.
(a) Amount of spinning liquid extruded from nozzle for extruding
liquid (Nl): 3 g/hour (b) Air velocity of air ejected: 250 m/sec.
(c) Moving speed of net: 0.65 mm/sec. (d) Conditions for suctioning
fibers: 30 cm/sec. (e) Conditions for supplying gas: 25.degree. C.,
27% RH, 1 m.sup.3/min.
Example 2
[0083] As a resin, a polypropylene resin [(MI=1500), Shear rate at
a temperature of 200.degree. C.: 3145 s.sup.-1, viscosity: 5000
mPas] was prepared.
[0084] A spinning apparatus comprising a plate for ejecting gas
(Pg), which contained a columnar hollow for gas (Hg), and a plate
for extruding liquid, in which columnar hollows for liquid
(Hl.sub.1 to Hl.sub.67) were bored, with the cross-section as shown
in FIG. 4 when the columnar hollows are cross-sectioned with a
plane perpendicular to the central axis of the columnar hollow for
gas (Hg), was prepared. More particularly, this spinning apparatus
contained the following members.
(1) Resin supply equipment: extruder (2) Heated gas supply
equipment: compressor (compressed air was heated by a heater) (3)
Plate for extruding liquid: a set of metal plates having a wall
thickness of 1 mm (4) Exits for extruding resin liquid (El.sub.1 to
El.sub.67): 67 circular exits (El.sub.1 to El.sub.67) having a
diameter of 0.15 mm were arranged in a single and straight line at
intervals of 5 mm, as the distance between the central axes of an
extruding direction. (5) Columnar hollows for liquid (Hl.sub.1 to
Hl.sub.67): cylindrical, 0.15 mm in diameter each (6) Plate for
ejecting gas: metal plate having a wall thickness of 10 mm (7) Exit
for ejecting gas (Eg): rectangular, 0.6 mm in width and 420 mm in
length (8) Columnar hollow for gas (Hg): rectangular
parallelepiped, 0.6 mm in width, 420 mm in length, and 5 mm in
height (9) Positions: The exit for ejecting gas (Eg) was located 5
mm upstream of all the exits for extruding liquid (El.sub.1 to
El.sub.67), and the plate for extruding liquid was directly
contacted with the plate for ejecting gas. (10) Distance between
each of virtual columns for liquid (Hvl.sub.1 to Hvl.sub.67) and
virtual column for gas (Hvg): 0.3 mm each (11) Central axes of
extruding direction of liquid (Al.sub.1 to Al.sub.67) and central
axis of ejecting direction of gas (Ag): parallel to each other (12)
Number of straight lines having the shortest distance between the
outer boundary of the cross-section of the columnar hollow for gas
(Hg) and each outer boundary of the cross-sections of the columnar
hollows for liquid (Hl.sub.1 to Hl.sub.67) when the columnar
hollows are cross-sectioned with a plane perpendicular to the
central axis of the columnar hollow for gas (Hg): 1 each (13)
Fibers collection means: suction cylinder (punch metal plate),
arranged so that the surface thereof for capturing fibers was
perpendicular to the center axis of the extruding direction of
liquid; distance between each exit for extruding resin liquid
(El.sub.1 to El.sub.67) and the surface for capturing fibers: 200
mm (14) Equipment for suctioning fibers: suction cylinder
[0085] After the polypropylene resin was melted at 200.degree. C.,
the melted resin liquid was extruded from the exits for extruding
resin liquid (El.sub.1 to El.sub.67) in the direction of gravity,
and simultaneously, heated air was ejected from the exit for
ejecting gas (Eg) to fiberize the resin liquid, and simultaneously,
the formed fibers were suctioned by the suction cylinder to fly the
fibers in the direction to the fibers collection means and to
accumulate the fibers on the fibers collection means, under the
following conditions, to produced a nonwoven fabric (mass per unit
area: 4 g/m.sup.2, thickness: 100 .mu.m, average fiber diameter:
600 nm, CV value: 0.6). The fibers which formed the nonwoven fabric
were thin, and the unevenness of fiber diameters was small.
(a) Amount of resin extruded: 2 g/hour/nozzle (b) Temperature of
plate for ejecting gas and plate for extruding liquid: 200.degree.
C. (c) Air ejected: temperature 260.degree. C., flow rate 6 N
/min., air velocity 397 m/sec. (d) Suction cylinder: rotation speed
4 m/min., amount suctioned 130 m.sup.3/min., gas velocity 28
m/sec.
Example 3
[0086] A nonwoven fabric was produced under the same conditions
described in Example 2, except that the amount of resin extruded
was 10 g/hour/nozzle. The produced nonwoven fabric had a mass per
unit area of 5 g/m.sup.2, a thickness of 150 .mu.m, an average
fiber diameter of 1100 nm, and a CV value of 0.3. The fibers which
formed the nonwoven fabric were thick, but the unevenness of fiber
diameters was very small.
Comparative Example 2
[0087] As a resin, a polypropylene resin [(MI=1500), Shear rate at
a temperature of 200.degree. C.: 3145 s.sup.-1, viscosity: 5000
mPas] was prepared.
[0088] A die for a melt blowing apparatus, of which the schematical
cross-section taken along a plane perpendicular to the columns of
the exits for extruding resin is shown in FIG. 8, was provided.
More particularly, this melt blowing apparatus contained the
following members.
(1) Resin supply equipment: extruder (2) Heated gas supply
equipment: compressor (compressed air was heated by a heater) (3)
Die for melt blowing apparatus: metal die (4) Exits for extruding
resin liquid (El.sub.1 to El.sub.31): circular exits (El.sub.1 to
El.sub.31) having a diameter of 0.2 mm were arranged in a single
and straight line. (5) Exit for ejecting gas (Eg): 0.5 mm in width
and 300 mm in length (6) Fibers collection means: suction cylinder
(punch metal plate), arranged so that the surface thereof for
capturing fibers was perpendicular to the center axis of the
extruding direction of resin liquid; distance between each exit for
extruding resin liquid and the surface for capturing fibers: 300 mm
(7) Equipment for suctioning fibers: suction cylinder
[0089] After the polypropylene resin was melted at 200.degree. C.,
the melted resin liquid was extruded from the exits for extruding
resin liquid (El.sub.1 to El.sub.31) in the direction of gravity,
and simultaneously, heated air ejected from the exit for ejecting
gas (Eg) was blown to the extruded resin liquid to fiberize the
resin liquid, and simultaneously, the formed fibers were suctioned
by the suction cylinder to fly the fibers in the direction to the
fibers collection means and to accumulate the fibers on the fibers
collection means, under the following conditions, to produced a
nonwoven fabric (mass per unit area: 10 g/m.sup.2, thickness: 100
.mu.m, average fiber diameter: 2000 nm, CV value: 0.9). The fibers
which formed the nonwoven fabric were thick, the unevenness of
fiber diameters was large, and the nonwoven fabric contained many
shots and beads.
(a) Amount of resin extruded: 0.5 g/hour/nozzle
(b) Temperature of die: 200.degree. C.
[0090] (c) Air ejected: temperature 280.degree. C., flow rate 2.5
N/min., air velocity 278 m/sec. (d) Suction cylinder: rotation
speed 4 m/min., amount suctioned 50 m.sup.3/min., gas velocity 20
m/sec.
INDUSTRIAL APPLICABILITY
[0091] The nonwoven fabric of the present invention can be
preferably used as, for example, a filtering material for filter
(such as air filter, liquid filter, or blood filter), a separator
for electrochemical device (such as battery separator or separator
for capacitor), an electrode material, a film support, a
semiconductor substrate, a substrate for flexible display, a
thermal insulating material, a sound insulating material, a carrier
for cell culture, a wound dressing material, a material for drug
delivery system, a sensor chip, or a smart fabric.
REFERENCE SIGNS LIST
[0092] Nl: Nozzle for extruding liquid [0093] Nl.sub.1, Nl.sub.2,
Nl.sub.3: Nozzle for extruding liquid [0094] Pg: Plate for ejecting
gas [0095] El, El.sub.1, El.sub.2, El.sub.3: Exit for extruding
liquid [0096] Eg: Exit for ejecting gas [0097] Hl.sub.1, Hl.sub.2,
Hl.sub.3: Columnar hollow for liquid [0098] Hg: Columnar hollow for
gas [0099] Hvl.sub.1, Hvl.sub.2, Hvl.sub.3: Virtual column for
liquid [0100] Hvg: Virtual column for gas [0101] Al.sub.1,
Al.sub.2, Al.sub.3: Central axis of the extruding direction
(liquid) [0102] Ag: Central axis of the ejecting direction (gas)
[0103] C: Plane perpendicular to the central axis of the columnar
hollow for gas [0104] L.sub.1, L.sub.2, L.sub.3: Straight line
having the shortest distance between outer boundaries [0105] 12:
First member [0106] 22: Second member [0107] 32: Third member
[0108] 14, 24, 34: Supply end [0109] 16, 26, 36: Opposing exit end
[0110] 18: First supply slit [0111] 38: First gas slit [0112] 20:
Gas jet space [0113] 1: Spinning apparatus [0114] 2: Flight space
[0115] 3: Fibers collection means [0116] 4: Suction apparatus
* * * * *