U.S. patent application number 14/443706 was filed with the patent office on 2015-11-19 for composite spinneret, multicomponent fiber, and method of producing multicomponent fiber.
This patent application is currently assigned to Toray Industries, Inc.. The applicant listed for this patent is TORAY INDUSTRIES, INC.. Invention is credited to Joji FUNAKOSHI, Masato MASUDA, Masaomi MIYASHITA.
Application Number | 20150329991 14/443706 |
Document ID | / |
Family ID | 50731268 |
Filed Date | 2015-11-19 |
United States Patent
Application |
20150329991 |
Kind Code |
A1 |
MASUDA; Masato ; et
al. |
November 19, 2015 |
COMPOSITE SPINNERET, MULTICOMPONENT FIBER, AND METHOD OF PRODUCING
MULTICOMPONENT FIBER
Abstract
A multicomponent fiber includes a sea component and an island
component, wherein in cross-section observation of the
multicomponent fiber, the multicomponent fiber includes a
sea-island region with the plurality of island components arranged
in the sea component; and one or more sea component regions formed
only of the sea component between the sea-island region, and a
width (H) of the sea component region is larger than a maximum
value of a distance (W) between island components existing in the
sea-island region and neighboring each other.
Inventors: |
MASUDA; Masato; (Mishima,
JP) ; MIYASHITA; Masaomi; (Otsu, JP) ;
FUNAKOSHI; Joji; (Otsu, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TORAY INDUSTRIES, INC. |
Chuo-ku, Tokyo |
|
JP |
|
|
Assignee: |
Toray Industries, Inc.
Chuo-ku, Tokyo
JP
|
Family ID: |
50731268 |
Appl. No.: |
14/443706 |
Filed: |
November 15, 2013 |
PCT Filed: |
November 15, 2013 |
PCT NO: |
PCT/JP2013/080891 |
371 Date: |
May 19, 2015 |
Current U.S.
Class: |
428/374 ;
425/131.5 |
Current CPC
Class: |
D10B 2331/04 20130101;
D01D 4/025 20130101; Y10T 428/2931 20150115; D01F 8/14 20130101;
D01D 5/082 20130101; D01F 8/00 20130101; D01D 5/36 20130101 |
International
Class: |
D01D 4/02 20060101
D01D004/02; D01D 5/08 20060101 D01D005/08; D01F 8/14 20060101
D01F008/14 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 2012 |
JP |
2012-253208 |
Claims
1.-21. (canceled)
22. A multicomponent fiber comprising a sea component and an island
component, wherein, in cross-section observation of the
multicomponent fiber, the multicomponent fiber comprises: a
sea-island region with the plurality of island components arranged
in the sea component; and one or more sea component regions formed
only of the sea component between the sea-island region, and a
width (H) of the sea component region is larger than a maximum
value of a distance (W) between island components existing in the
sea-island region and neighboring each other.
23. The multicomponent fiber according to claim 22, wherein the sea
component region extends inwardly from a surface layer of the
multicomponent fiber.
24. The multicomponent fiber according to claim 23, wherein the
island components in the sea-island region are regularly
arranged.
25. The multicomponent fiber according to claim 22, wherein in
cross-section observation of the sea-island multicomponent fiber, a
ratio (L/D) of a length (L) of the sea component region to a
diameter (D) of the multicomponent fiber is 0.25 or more.
26. The multicomponent fiber according to claim 22, wherein in
cross-section observation of the sea-island multicomponent fiber,
the width (H) of the sea component region is larger than the
maximum diameter (d) of the island component.
27. The multicomponent fiber according to claim 26, wherein in
cross-section observation, there exists at least one sea component
region where the width (H) of the sea component region is larger
than the maximum diameter (d) of the island component, and the
length (L1) of the sea component region is equal to or larger than
1/4 of the diameter (D) of the multicomponent fiber.
28. The multicomponent fiber according to claim 27, wherein in
cross-section observation, the cross-section area (Ac) of the
multicomponent fiber and the sum of areas (As) of sea component
regions satisfy: 0.05.ltoreq.As/Ac.ltoreq.0.35.
29. The multicomponent fiber according to claim 22, wherein in
cross-section observation, the sea component region is
cruciform.
30. A composite spinneret that discharges a composite polymer
composed of an island polymer and a sea polymer, the composite
spinneret satisfying (1) and (2): (1) the composite spinneret
comprises: a distribution device that distributes polymers; a
nozzle plate situated on a downstream side of the distribution
device in a polymer spinning passage direction and which has a
plurality of sea discharge holes, and at least one kind of
discharge holes selected from a plurality of island discharge holes
and a plurality of composite polymer discharge holes; and a flow
contraction plate situated on the downstream side of the nozzle
plate in the polymer spinning passage direction and which has a
introducting hole communicating with discharge holes in a
combination of discharge holes selected from the combinations of:
the sea discharge holes and the island discharge holes; the sea
discharge holes and the composite polymer discharge holes; and the
sea discharge holes, the island discharge holes and the composite
polymer discharge holes; and (2) the nozzle plate has a nozzle hole
collection including a plurality of discharge holes, and the nozzle
hole collection includes a sea component region forming hole group
including the sea discharge holes, and at least one sea-island
discharge hole group including any of (i) to (v): (i) the sea
discharge holes and the island discharge holes; (ii) the composite
polymer discharge holes; (iii) the sea discharge holes and the
composite polymer discharge holes; (iv) the island discharge holes
and the composite polymer discharge holes; and (v) the sea
discharge holes, the island discharge holes and the composite
polymer discharge holes.
31. The composite spinneret according to claim 30, wherein the
composite spinneret further satisfies (3): (3) the sea component
region forming hole group is continuously arranged inwardly from an
outer periphery of the nozzle hole collection with a part of the
sea-island discharge hole group held between both sides.
32. The composite spinneret according to claim 30, wherein the
distribution device has a plurality of composite polymer discharge
holes, and comprises: a plurality of pipes that supply the island
polymer to the polymer discharge hole, the pipes arranged at
positions corresponding to the composite polymer discharge holes of
the nozzle plate on a one-to-one basis; a sea polymer introduction
channel that supplies the sea polymer; and a sea polymer
distribution chamber provided to communicate with the sea polymer
introduction channel and surround the plurality of pipes, and the
composite polymer discharge hole of the nozzle plate communicates
with the pipe and the sea polymer distribution chamber.
33. The composite spinneret according to claim 31, wherein the sea
component region forming hole group is continuously arranged from
an outer periphery of a circumscribed circle of the nozzle hole
collection having a radius of R to the inside of a circle having a
radius of 0.5R or less from the center with the sea component
region forming hole group held between both sides of the sea-island
discharge hole group.
34. The composite spinneret according to claim 30, wherein the
composite spinneret is used for production of a multicomponent
fiber including a sea component and an island component, wherein,
in cross-section observation of the multicomponent fiber, the
multicomponent fiber includes: a sea-island region with the
plurality of island components arranged in the sea component; and
one or more sea component regions formed only of the sea component
between the sea-island region, and width (H) of the sea component
region is larger than the maximum value of distance (W) between
island components existing in the sea-island region and neighboring
each other.
35. A multicomponent fiber including a sea component and an island
component, wherein, in cross-section observation of the
multicomponent fiber, the multicomponent fiber includes: a
sea-island region with a plurality of island components arranged in
the sea component; and more than one sea component region formed
only of the sea component between the sea-island region, and a
width (H) of the sea component region is larger than a maximum
value of a distance (W) between island components existing in the
sea-island region and neighboring each other.
36. The multicomponent fiber according to claim 35, wherein the sea
component region extends inwardly from a surface layer of the
multicomponent fiber.
37. The multicomponent fiber according to claim 36, wherein the
island components in the sea-island region are regularly
arranged.
38. The multicomponent fiber according to claim 35, wherein, in
cross-section observation of the sea-island multicomponent fiber, a
ratio (L/D) of a length (L) of the sea component region to a
diameter (D) of the multicomponent fiber is 0.25 or more.
39. The multicomponent fiber according to claim 35, wherein, in
cross-section observation of the sea-island multicomponent fiber,
the width (H) of the sea component region is larger than the
maximum diameter (d) of the island component.
40. The multicomponent fiber according to claim 39, wherein, in
cross-section observation, there exists at least one sea component
region where the width (H) of the sea component region is larger
than the maximum diameter (d) of the island component, and a length
(L1) of the sea component region is equal to or larger than 1/4 of
the diameter (D) of the multicomponent fiber.
41. The multicomponent fiber according to claim 40, wherein, in
cross-section observation, a cross-section area (Ac) of the
multicomponent fiber and a sum of areas (As) of sea component
regions satisfy: 0.05.ltoreq.As/Ac.ltoreq.0.35.
Description
TECHNICAL FIELD
[0001] This disclosure relates to a composite spinneret that
discharges a composite polymer flow composed of two or more
polymers, a multicomponent fiber obtained by performing melt
spinning by a composite spinning machine using the composite
spinneret, and a method of producing a multicomponent fiber.
BACKGROUND
[0002] By combining two or more polymers, performance which is not
sufficient with a single-component polymer has been complemented,
and various multicomponent fibers having novel functions have been
developed with diversification of applications.
[0003] A sea-island multicomponent fiber, one of multicomponent
fibers, is a fiber in which in cross-section observation, two or
more polymers having different compositions are phase-separated,
some kind of polymer is dispersed in another polymer, and the
former polymer looks like islands while the latter polymer looks
like sea. Hereinafter, the former polymer is referred to as an
"island polymer," and the latter polymer is referred to as a "sea
polymer" in some cases.
[0004] After sea-island multicomponent fibers are produced by
performing melt-spinning, a sea polymer as an easily soluble
component is removed to leave only an island polymer as a hardly
soluble component so that ultrafine fibers with each single fiber
having a thread diameter in a nanometer order can be obtained. In
applications of clothes, those fibers can be applied to artificial
leathers and new-touch textiles since soft touch and fineness that
cannot be achieved with common fibers are realized. Further, those
fibers can be expanded to applications of sports wear required to
have windbreaking performance and water repellency as high-density
fabrics because they have reduced fiber gaps. In applications of
industrial materials, those fibers can be applied to
high-performance filters in view of increasing the specific surface
area to improve dust collecting performance, and to wiping cloths
and precise polishing cloths for precision equipment in view of
wiping out contaminants with ultrafine fibers entering very small
grooves.
[0005] Generally, a method of forming a composite polymer flow in a
composite spinneret, and producing a multicomponent fiber therefrom
is referred to as a composite spinning method, and a method of
producing a multicomponent fiber by melting and kneading polymers
is referred to as a polymer alloy method.
[0006] In the polymer alloy method, ultrafine fibers can be
produced similarly to the composite spinning method, but control of
the fiber diameter is limited so that it is difficult to obtain
uniform ultrafine fibers. On the other hand, the composite spinning
method is capable of forming a composite polymer flow composed of
two or more polymers in a composite spinneret, and precisely
controlling a composite structure. Therefore, the composite
spinning method is superior to the polymer alloy method in that a
thread cross-section form with high accuracy can be uniformly
formed.
[0007] To make it possible to stably control the thread
cross-section form in the composite spinning method, a composite
spinneret technique is important. Therefore, various proposals have
been heretofore made.
[0008] Composite spinneret techniques related to sea-island
multicomponent fibers may be classified broadly into two
techniques: a pipe type spinneret technique and a distribution type
spinneret technique.
[0009] A typical example of the pipe type spinneret is disclosed in
Japanese Patent Laid-open Publication No. 2001-192924. FIG. 15
shows a partial enlarged longitudinal sectional view of the
composite spinneret disclosed in Japanese Patent Laid-open
Publication No. 2001-192924. In the drawings, explanations may be
omitted when there exists a member with the same reference symbol
as that corresponding to a drawing that has already been
explained.
[0010] The pipe type spinneret shown in FIG. 15 includes a
distribution device 1 provided with sea polymer introduction
channels 21, an island polymer introduction channel 22, pipes 20
and a sea polymer distribution chamber 23; a nozzle plate 2
provided with composite polymer discharge holes 15; and a flow
contraction plate 3 provided with a spinneret discharge hole 6.
[0011] In that spinneret, a sea polymer as an easily soluble
component is guided from the sea polymer introduction channels 21
to the sea polymer distribution chamber 23, and fills the outer
periphery of each of the pipes 20. On the other hand, an island
polymer as a hardly soluble component is guided from the island
polymer introduction channel 22 to the pipes 20, and discharged
from the pipes 20. The island polymer discharged from the pipes 20
is put in the sea polymer filling the sea polymer distribution
chamber 23 so that a composite polymer flow with the island polymer
covered with the sea polymer is formed. Thereafter, the composite
polymer flow merges with another composite polymer flow by passing
through the composite polymer discharge holes 15, and is discharged
from the spinneret discharge hole 6 to form a multicomponent fiber
having a sea-island cross section.
[0012] In a pipe type spinneret as described above, when the number
of the pipes 20 per unit area is increased to a working limit, the
number of island components increases, the number of ultrafine
fibers after sea removal can be increased, and the fiber diameter
of the ultrafine fiber can be reduced on the cross section of the
sea-island multicomponent fiber. However, when the number of the
pipes 20 is increased, the distance between pipes decreases so that
the sea polymer cannot infiltrate into the central part of the
pipes 20, and thus distributivity of the sea polymer is
deteriorated. Therefore, in some portions, the island polymer is
not covered with the sea polymer, and particularly when spinning is
performed at a high island polymer ratio, island polymers may merge
with each other. To solve this problem, the arrangement of the
pipes 20 should be optimized to improve distributivity of the sea
polymer, and a typical example of the solution is disclosed in each
of Japanese Patent Laid-open Publication No. 2009-91680 and
National Publication of International Patent Application No.
2012-518100 (US Publication No. 2010/205926).
[0013] FIG. 17 is a partial enlarged plan view of a nozzle plate
employed in each of Japanese Patent Laid-open Publication No.
2009-91680 and National Publication of International Patent
Application No. 2012-518100 (US Publication No. 2010/205926).
[0014] The nozzle plate in FIG. 17 has composite polymer discharge
holes 15, and is provided with a sea polymer admission channel 11
(which has no discharge hole) in which pipes 20 are not arranged.
Thus, even when the number of discharge holes increases,
distribution of the sea polymer is kept satisfactory so that the
sea polymer can be evenly supplied to the whole of a composite
polymer discharge hole group. Therefore, even at the central part
of the composite polymer discharge hole group, the sea polymer
exists between island polymers so that merging of island polymers
can be suppressed. Accordingly, in the spinneret technique in
Japanese Patent Laid-open Publication No. 2009-91680 or National
Publication of International Patent Application No. 2012-518100 (US
Publication No. 2010/205926), a sea-island multicomponent fiber
having a relatively large number of islands can be obtained even in
a pipe type spinneret.
[0015] On the other hand, the distribution type spinneret is an
effective technique in view of increasing the number of islands. A
typical example thereof is a technique disclosed in Japanese Patent
Laid-open Publication No. 2011-208313. FIG. 16 is a partial
enlarged plan view of a nozzle plate having a shape disclosed in
Japanese Patent Laid-open Publication No. 2011-208313.
[0016] In FIG. 16, discharge holes are arranged such that at least
some of sea discharge holes 12 exist in a region surrounded by two
common circumscribing lines 30 of an island discharge hole 13
provided in the nozzle plate and an island discharge hole 13a
neighboring the island discharge hole 13 with the shortest
center-to-center distance, the island discharge hole 13 being
considered as a reference. Therefore, in the nozzle plate in FIG.
16, the sea polymer is forcibly arranged between island polymers so
that merging of island polymers discharged from the island
discharge hole 13 and the island discharge hole 13a can be
suppressed. Accordingly, even when the distance between neighboring
island discharge holes 13 is reduced to a working limit level,
merging of island polymers can be prevented so that the number of
discharge holes, through which the island polymer is discharged,
can be made larger per cross-section area of the introducting
hole.
[0017] As described above, even in conventional spinneret
techniques, sea-island multicomponent fibers having a large number
of islands can be produced by making various modifications.
Currently, by dividing the island polymer into multiple segments
according to the number of islands, even nanofibers having a fiber
diameter in a nanometer order can be obtained, as described above.
However, when the hole packing density is simply increased in the
techniques described in Japanese Patent Laid-open Publication No.
2001-192924, Japanese Patent Laid-open Publication No. 2009-91680,
National Publication of International Patent Application No.
2012-518100 (US Publication No. 2010/205926), and Japanese Patent
Laid-open Publication No. 2011-208313, the distance between island
components existing on the cross section of the sea-island
multicomponent fiber decreases. Therefore, in a step of removing
with a solvent a sea polymer for production of ultrafine fibers,
the sea polymer dissolved in the solvent is not efficiently
discharged from between island polymers or ultrafine fibers, and
thus the efficiency of sea removal may be reduced. Accordingly,
there is the problem that the time for the sea polymer to be
completely removed increases, and particularly when nanofibers or
the like are to be obtained, functions expected of nanofibers
cannot be obtained due to degradation of nanofibers, aggregation of
nanofibers, and so on.
[0018] As described above, a method of producing a sea-island
multicomponent fiber by a composite spinneret in which the hole
packing density of an island discharge hole is increased has been
highly desired. However, failure to remove the sea polymer occurs
during a sea removal treatment as described above, and this remains
as a problem to be alleviated, causing an obstruction to production
of ultrafine fibers. Therefore, solving this problem is of
importance from an industrial point of view. Accordingly, it could
be helpful to provide a sea-island multicomponent fiber with a sea
component that can be soluble with high efficiency, and to provide
a composite spinneret suitable for production of the sea-island
multicomponent fiber.
SUMMARY
[0019] We thus provide:
[0020] (1) A multicomponent fiber including a sea component and an
island component, wherein
[0021] in cross-section observation of the multicomponent fiber,
the multicomponent fiber includes:
[0022] a sea-island region with the plurality of island components
arranged in the sea component; and
[0023] one or more sea component regions formed only of the sea
component between the sea-island region, and
[0024] the width (H) of the sea component region is larger than the
maximum value of the distance (W) between island components
existing in the sea-island region and neighboring each other.
[0025] (2) The multicomponent fiber according to (1), wherein the
sea component region extends inward from a surface layer of the
multicomponent fiber.
[0026] (3) The multicomponent fiber according to (1) or (2),
wherein the island components in the sea-island region are
regularly arranged.
[0027] (4) The multicomponent fiber according to any one of (1) to
(3), wherein in cross-section observation of the sea-island
multicomponent fiber, the ratio (L/D) of the length (L) of the sea
component region to the diameter (D) of the multicomponent fiber is
0.25 or more.
[0028] (5) The multicomponent fiber according to any one of (1) to
(4), wherein in cross-section observation of the sea-island
multicomponent fiber, the width (H) of the sea component region is
larger than the maximum diameter (d) of the island component.
[0029] (6) The multicomponent fiber according to (5), wherein in
cross-section observation, there exists at least one sea component
region where the width (H) of the sea component region is larger
than the maximum diameter (d) of the island component, and the
length (L1) of the sea component region is equal to or larger than
1/4 of the diameter (D) of the multicomponent fiber.
[0030] (7) The multicomponent fiber according to any one of (1) to
(6), wherein in cross-section observation, the width (H) of the sea
component region and the diameter (D) of the multicomponent fiber
satisfy the following formula:
0.001<H/D<0.2.
[0031] (8) The multicomponent fiber according to any one of (1) to
(7), wherein in cross-section observation, the cross-section area
(Ac) of the multicomponent fiber and the sum of areas (As) of sea
component regions satisfy the following formula:
0.05.ltoreq.As/Ac.ltoreq.0.35.
[0032] (9) The multicomponent fiber according to any one of (1) to
(8), wherein in cross-section observation, the sea region is
cruciform.
[0033] (10) A method of producing an ultrafine fiber, including the
step of: removing a sea component from the multicomponent fiber
according to any one of (1) to (9).
[0034] (11) A fiber product including the fiber according to any
one of (1) to (9).
[0035] (12) A fiber product including an ultrafine fiber obtained
by the method according to (10).
[0036] (13) A composite spinneret for discharging a composite
polymer composed of an island polymer and a sea polymer, the
composite spinneret satisfying the requirements <1> and
<2>:
[0037] <1> the composite spinneret includes:
[0038] a distribution device for distributing polymers;
[0039] a nozzle plate which is situated on the downstream side of
the distribution device in a polymer spinning passage direction and
which has a plurality of sea discharge holes, and at least one kind
of discharge holes selected from a plurality of island discharge
holes and a plurality of composite polymer discharge holes; and
[0040] a flow contraction plate which is situated on the downstream
side of the nozzle plate in the polymer spinning passage direction
and which has a introducting hole communicating with discharge
holes in a combination of discharge holes that is selected from the
combinations of: [0041] the sea discharge holes and the island
discharge holes; [0042] the sea discharge holes and the composite
polymer discharge holes; and [0043] the sea discharge holes, the
island discharge holes and the composite polymer discharge holes;
and
[0044] <2> the nozzle plate has a nozzle hole collection
including a plurality of discharge holes, and the nozzle hole
collection includes a sea component region forming hole group
including the sea discharge holes, and at least one sea-island
discharge hole group including any of (i) to (v): [0045] (i) the
sea discharge holes and the island discharge holes; [0046] (ii) the
composite polymer discharge holes; [0047] (iii) the sea discharge
holes and the composite polymer discharge holes; [0048] (iv) the
island discharge holes and the composite polymer discharge holes;
and [0049] (v) the sea discharge holes, the island discharge holes
and the composite polymer discharge holes.
[0050] (14) The composite spinneret according to (13), wherein the
composite spinneret further satisfies the requirement
<3>:
[0051] <3> the sea component region forming hole group is
continuously arranged inward from an outer periphery of the nozzle
hole collection with a part of the sea-island discharge hole group
held between both sides.
[0052] (15) The composite spinneret according to (13) or (14),
wherein the distribution device has a plurality of composite
polymer discharge holes, and is formed by stacking one or more
distribution plates provided with a distribution hole and/or a
distribution groove, and the distribution hole or the distribution
groove communicates with at least one kind of discharge hole
selected from the sea discharge hole, the island discharge hole and
the composite polymer discharge hole.
[0053] (16) The composite spinneret according to any one of (13) to
(15), wherein the distribution device has a plurality of composite
polymer discharge holes, and includes:
[0054] a plurality of pipes for supplying the island polymer to the
polymer discharge hole, the pipes arranged at positions
corresponding to the composite polymer discharge holes of the
nozzle plate on a one-to-one basis;
[0055] a sea polymer introduction channel for supplying the sea
polymer; and
[0056] a sea polymer distribution chamber provided to communicate
with the sea polymer introduction channel and surround the
plurality of pipes, and
[0057] the composite polymer discharge hole of the nozzle plate
communicates with the pipe and the sea polymer distribution
chamber.
[0058] (17) The composite spinneret according to any one of (13) to
(16), wherein a sea discharge hole that forms a part of the nozzle
hole collection is arranged at each apex of an n-gonal lattice, an
island discharge hole that forms a part of the nozzle hole
collection is arranged at the gravity center position of the
n-gonal lattice, m or less of the island discharge holes are
arranged on an imaginary circumference, the radius of which is a
center-to-center distance between the sea discharge hole that forms
the sea component region forming hole group and the sea discharge
hole or the island discharge hole closest to the sea discharge hole
of the sea component region forming hole group, and n and m satisfy
any of the requirements (x) to (xii):
(x) n=6 and m=2 (xi) n=4 and m=3 (xii) n=3 and m=5
[0059] (18) The composite spinneret according to any one of (13) to
(17), wherein the sea component region forming hole group is
continuously arranged from the outer periphery of a circumscribed
circle of the nozzle hole collection having a radius of R to the
inside of a circle having a radius of 0.5R or less from the center
with the sea component region forming hole group held between both
sides of the sea-island discharge hole group.
[0060] (19) The composite spinneret according to any one of (13) to
(18), wherein the composite spinneret is used for production of the
multicomponent fiber according to any one of (1) to (9).
[0061] (20) A method of producing a multicomponent fiber, including
the step of: putting an island polymer and a sea polymer in the
composite spinneret of a spinning machine using the composite
spinneret according to any one of (13) to (18), and discharging the
island polymer and the sea polymer from the composite spinneret to
perform spinning.
[0062] (21) The method of producing a multicomponent fiber
according to (20), wherein a multicomponent fiber to be produced is
the multicomponent fiber according to any one of (1) to (9).
[0063] The meanings of terms used herein are as follows.
[0064] The "distribution hole" means a hole formed by combination
of a plurality of distribution plates, the hole serving to
distribute a polymer in a polymer spinning passage direction.
[0065] The "distribution groove" means a groove formed by
combination of a plurality of distribution plates, the groove
serving to distribute a polymer in a direction perpendicular to a
polymer spinning passage direction. The distribution groove may be
a long and narrow hole, or may be formed by digging a long and
narrow groove.
[0066] The "polymer sinning passage direction" means a main
direction in which each polymer passes from a distribution device
to a nozzle hole of a spinneret.
[0067] The "composite polymer discharge hole" means a discharge
hole through which a composite polymer is discharged, the composite
polymer having an island polymer and a sea polymer merged with each
other in a sheath-core form, a side-by-side form, a layered form, a
sea-island form or a circumferential form.
[0068] The "hole packing density" means a value determined by
dividing the sum of the number of island discharge holes and the
number of composite polymer discharge holes by the sum of
cross-section areas of introducting holes. Only island discharge
holes may exist, or only composite polymer discharge holes may
exist. The "diameter" in fiber cross-section observation when a
diagram, the diameter of which is to be defined, is not a circle,
means the diameter of a circle having an area equal to the area of
the diagram. It is to be noted that the "diameter" means the
diameter of a circumscribed circle of a fiber cross section for a
fiber from which a sea component has been removed to leave only an
island polymer.
[0069] The "center" of a diagram in fiber cross-section observation
means the gravity center position.
[0070] The "sea removal" means that a sea polymer of a
multicomponent fiber is removed with a solvent.
[0071] According to our multicomponent fibers, even when the number
of island components per cross-section area of the multicomponent
fiber is large, a sea component can be easily removed with a
solvent efficiently so that an extremely thin ultrafine fiber can
be obtained. According to the composite spinneret, the
multicomponent fiber can be easily produced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0072] FIG. 1 is a schematic longitudinal sectional view of a
composite spinneret that is used in an example.
[0073] FIG. 2 is a schematic longitudinal sectional view of a
composite spinneret that is used in the example, a spinning pack
and a cooler, and a periphery thereof.
[0074] FIG. 3 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0075] FIG. 4 is a plan view of a nozzle plate that is used in the
example.
[0076] FIG. 5 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0077] FIG. 6 is a partial enlarged longitudinal sectional view of
a nozzle plate that is used in the example.
[0078] FIG. 7 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0079] FIG. 8 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0080] FIG. 9 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0081] FIG. 10 is a schematic longitudinal sectional view of a
composite spinneret that is used in the example.
[0082] FIG. 11 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0083] FIG. 12 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0084] FIG. 13 is a sectional view of a multicomponent fiber as one
example.
[0085] FIG. 14 is a sectional view of a multicomponent fiber as one
example.
[0086] FIG. 15 is a partial enlarged longitudinal sectional view of
a composite spinneret in a conventional example.
[0087] FIG. 16 is a partial enlarged plan view of a nozzle plate in
a conventional example.
[0088] FIG. 17 is a partial enlarged plan view of a nozzle plate in
a conventional example.
[0089] FIG. 18 is a partial enlarged plan view of a nozzle plate
that is used in another example.
[0090] FIG. 19 is a partial enlarged plan view of a cross section
of a multicomponent fiber.
[0091] FIG. 20 is a sectional view of a multicomponent fiber as one
example.
[0092] FIG. 21 is a sectional view of a multicomponent fiber as one
example.
[0093] FIG. 22 is a sectional view of a multicomponent fiber as one
example.
[0094] FIG. 23 is a sectional view of a multicomponent fiber as one
example.
[0095] FIG. 24 is a sectional view of a multicomponent fiber as one
example.
[0096] FIG. 25 is a sectional view of a multicomponent fiber as one
example.
[0097] FIG. 26 is a sectional view of a multicomponent fiber as one
example.
[0098] FIG. 27 is a sectional view of one example of a conventional
multicomponent fiber.
[0099] FIG. 28 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0100] FIG. 29 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0101] FIG. 30 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0102] FIG. 31 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0103] FIG. 32 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0104] FIG. 33 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0105] FIG. 34 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0106] FIG. 35 is a partial enlarged plan view of a nozzle plate
that is used in the example.
[0107] FIG. 36 is a partial enlarged plan view of a nozzle plate
that is used in the example.
DESCRIPTION OF REFERENCE SIGNS
[0108] 1: Distribution device [0109] 2: Nozzle plate [0110] 3: Flow
contraction plate [0111] 4: Introducting hole [0112] 5: Flow
contraction hole [0113] 6: Spinneret discharge hole [0114] 7:
Composite spinneret [0115] 8: Spinning pack [0116] 9: Cooler [0117]
10: Spin block [0118] 11: Nozzle plate [0119] 12: Sea discharge
hole [0120] 13: Island discharge hole [0121] 15: Composite polymer
discharge hole [0122] 16: Measuring plate [0123] 17: Distribution
plate [0124] 18: Nozzle hole collection [0125] 19: Sea-island
discharge hole group [0126] 20: Pipe [0127] 21: Sea polymer
introduction channel [0128] 22: Island polymer introduction channel
[0129] 23: Sea polymer distribution chamber [0130] 30: common
circumscribing line [0131] 40: Multicomponent fiber [0132] 41: Sea
component [0133] 42: Sea-island region [0134] 43: Island component
[0135] 44: Sea component region [0136] 51: Distribution groove
[0137] 52: Distribution hole [0138] 61: Sea polymer introduction
channel [0139] 62: Pipe [0140] 63: Sea polymer distribution chamber
[0141] 64: Distribution device [0142] 65: Sea discharge hole [0143]
66: Composite polymer discharge hole 66 [0144] 67: Nozzle plate
DETAILED DESCRIPTION
[0145] Our spinnerets, fibers, and methods will be specifically
described below along with desirable examples.
[0146] A multicomponent fiber includes a sea-island region 42 with
an island component 43 arranged in a sea component 41, and a sea
component region 44 formed only of the sea component 41 as
illustrated in FIG. 13.
[0147] The sea component region 44 means a region formed only of a
sea polymer as shown in FIG. 13, the sea component region having a
width (H) larger than the maximum value of a distance between
island components existing in the sea-island region and neighboring
each other. In the multicomponent fiber, the sea component region
is between the sea-island region of the multicomponent fiber, and
in cross-section observation, there are one or more sea component
regions.
[0148] As described above, one of the purposes of the
multicomponent fiber is production of an ultrafine fiber, and this
structure is intended to ensure that the efficiency of the sea
removal treatment is not reduced even if the island packing density
is increased. In the cross section of a conventional multicomponent
fiber with a large number of island components arranged in a sea
component, the treatment with a solvent naturally proceeds from the
outer layer of the multicomponent fiber gradually. Even island
components are affected by the solvent before the sea removal
treatment reaches the inner part of the multicomponent fiber.
Therefore, there has been the problem that the resulting ultrafine
fiber has significantly poor quality, or sea removal is not
completed.
[0149] Thus, we provided a sea component region composed only of a
sea polymer in cross-section observation as in the multicomponent
fiber. That is, in the multicomponent fiber, the sea polymer in the
sea component region is removed before the solvent dissolves the
sea polymer existing in the sea-island region at the time of
removing the sea polymer of the multicomponent fiber. Therefore,
the solvent reaches the center of the multicomponent fiber early so
that the elution time of the sea polymer can be reduced.
[0150] The distance between neighboring island components
(inter-island component distance: W) in the sea-island region and
the width (H) of the sea component region can be determined in the
following manner.
[0151] The multicomponent fiber is embedded in an embedding medium
such as an epoxy resin, and cut along the cross section by a
microtome, and the cut surface is then photographed by a scanning
electron microscope (SEM) at a magnification that allows the entire
cross section to be observed. When the cross section is stained
with a metal compound, a contrast difference between the island
component and the sea component can be made clear. From
cross-section images of 10 or more randomly selected multicomponent
fibers, the width of the sea component region can be measured using
image processing software. The inter-island component distance and
width of the sea component region herein mean a distance between
island components and width of the sea component region as
expressed on an image of a cut surface where the cut surface is a
cross section in a vertical direction with respect to the fiber
axis from the image. The inter-island component distance refers to
the minimum value between an island component and another island
component for two island components neighboring each other in the
sea-island region. The width of the sea component is calculated in
the following manner. A boundary line between the sea component
region and the sea-island component region is assumed. Points that
form the boundary line are assumed, and the shortest distance
between each point and a boundary line between the sea-island
component and the sea-island region in the opposite direction is
determined.
[0152] The inter-island component distance and the width of the sea
component region are each measured in a unit of .mu.m to the second
decimal place, and rounded off to the first decimal place. The
above procedure is carried out for each of 10 or more randomly
extracted spots. For the island component distance, an average of
the measured values is employed.
[0153] In cross-section observation as described above, when the
sea component region exists with a large width, cracks are formed
from the side surface to the central part of the multicomponent
fiber in the early stage of the sea removal treatment so that a
solvent easily infiltrates into the inner part of the
multicomponent fiber. The formed cracks significantly propagate to
the inner part of the multicomponent fiber so that the
multicomponent fiber can be divided. Division of the multicomponent
fiber into a plurality of fibers as described above is preferred
because the specific surface area of the multicomponent fiber
exposed to the solvent at the time of performing the sea removal
treatment increases, leading to an increase in elution speed of the
sea polymer. The specific surface area herein means the surface
area per fiber mass.
[0154] As a criterion for development of such a phenomenon, the
width (H) of the sea component region and the diameter (D) of the
multicomponent fiber preferably satisfy the relationship of
0.001<H/D<0.2. When the above-mentioned relationship is
satisfied, the multicomponent fiber is physically stimulated by a
liquid flow during the sea removal treatment when the treatment is
performed in a flow liquid in a jet dyeing machine or the like so
that cracks that are once formed are expanded as the sea removal
treatment proceeds. Further, a force is applied to the
multicomponent fiber in the compression direction due to the effect
of the liquid flow, and the multicomponent fiber is physically
divided. In view of infiltration of a solvent into the inner part
of the multicomponent fiber and ease of crack formation, H/D is
preferably as large as possible, and H/D is preferably 0.01 or
more, further preferably 0.03 or more. On the other hand, H/D is
preferably 0.2 or less from the viewpoint of homogeneity of
cross-section forms (e.g. diameter and shape) of the multicomponent
fiber and a plurality of existing island components and ease of
quality control by cross-section observation or the like.
[0155] To disseminate formation of cracks throughout the
multicomponent fiber, it is desirable that the cross-section area
(As) of the sea component region be in a certain ratio to the
cross-section area (Ac) of the multicomponent fiber, and the
relationship of 0.05.ltoreq.As/Ac is preferably satisfied. Further,
the relationship of As/Ac.ltoreq.0.35 is preferably satisfied. Sea
removal efficiency is improved as the parameter of As/Ac becomes
larger. However, when the above-mentioned relationship is
satisfied, the amount of the sea polymer used to form the sea
component region is small, and also the sea polymer in an amount
sufficient to form a sea-island cross section can be supplied to
the sea-island region so that the sea-island multicomponent fiber
can be produced with a high island component ratio. In addition to
the homogeneity of island components and ease of quality control,
the necessity to unduly increase the difficulty degree of design of
a spinneret is eliminated.
[0156] The sea-island region existing in the multicomponent fiber
refers to a region with a plurality of island components existing
in a sea component as described above, and it is preferred that
island components are regularly arranged in the sea-island
region.
[0157] Preferably, the regular arrangement herein means that in
four island components close to one another, straight lines
connecting the centers of two neighboring island components (45-(a)
(straight line connecting the centers of two island components) and
45-(b) (straight line connecting the centers of other two island
components) in FIG. 19) are in parallel relationship with each
other as illustrated in FIG. 19. The parallel relationship herein
means that the angle formed by the two straight lines is not less
than 0.degree. and not more than 5.degree.. In evaluation for the
parallel relationship of island components, similarly to the case
of the width of the sea component region, the following
determination is made. That is, as described above, angles formed
by two straight lines are measured to the first decimal place at 20
randomly selected spots in cross-section images of the
multicomponent fiber, and when the value determined by rounding off
the average of the measured values to an integer is in the
above-mentioned range, it is determined that the island components
are in parallel relationship with each other.
[0158] When island components are regularly arranged in the
sea-island region in the multicomponent fiber, there is developed
an effect of sustaining tension, which is applied to the
multicomponent fiber in spinning and post processing, equally by
the whole cross section of the multicomponent fiber so that
spinning stability and post processability are significantly
improved. In the sea-island multicomponent fibers, it is generally
difficult to perform spinning at a high spinning velocity, but in
the sea-island multicomponent fiber, spinning can be performed even
at a high spinning velocity because island components are regularly
arranged. Stress is not concentrated on a part of the fiber cross
section and, therefore, the multicomponent fiber has excellent
quality.
[0159] To enhance the effect of improving soluble efficiency of the
sea component, the ratio (L/D) of the length (L) of the sea
component region to the diameter (D) of the multicomponent fiber in
the multicomponent fiber is preferably 0.25 or more (see, for
example, FIG. 13). When the ratio (L/D) is in the above-mentioned
range, cracks are generated in the sea component region in the
early stage of the sea removal treatment, and a solvent infiltrates
into the cracks to increase the specific surface area of the sea
polymer exposed to the solvent so that the sea component can be
efficiently removed. This is because the sea component is
progressively removed by a treatment with a solvent. This effect
results in embrittlement of the sea polymer, and since the sea
component region is formed of the sea polymer which is easily
dissolved, the sea component region is removed in the early stage
of the elution treatment, and when the sea removal treatment is
performed in a jet dyeing machine or the like, the sea component
region is physically stimulated by a liquid flow so that cracks are
easily formed.
[0160] Such crack formation due to embrittlement of the sea
component region occurs when the ratio of the diameter of the
composite cross section to the width of the sea component region is
0.25 or more, but L/D is preferably 0.50 or more. When the ratio
(L/D) is in the above-mentioned range, cracks are formed over 1/2
or more of the multicomponent fiber diameter in the early stage of
the elution treatment, and transversely propagate across the cross
section of the multicomponent fiber as the sea removal treatment
proceeds and further the fiber is physically stimulated, and
ultimately the multicomponent fiber is divided into two halves. In
this case, the specific surface area treated with the solvent
increases in proportion to the square of the division number of the
multicomponent fiber. Therefore, the sea removal efficiency is
further improved. From this point of view, the length (L) of the
sea component region is preferably as large as possible, the
maximum viable value of the above-mentioned ratio is 1, and this
value may be particularly preferred.
[0161] The width (H) of the sea component region is preferably
larger than the maximum diameter (d) of the island component. This
is because the effect of improving sea removal efficiency by
arranging the sea component region essentially depends on the width
(H) of the sea component region, but a width being larger than the
maximum diameter (d) of the island component is preferred because
infiltration of the solvent and crack formation properly proceed
without being hindered by influences of island components.
[0162] Further, it is preferable that there exists at least one sea
component region where the width (H) of the sea component region is
larger than the maximum diameter (d) of the island component, and
the length (L1) of the sea component region is equal to or larger
than 1/4 of the diameter (D) of the multicomponent fiber.
[0163] The method of evaluating the island component diameter is as
follows. The cross section of the sea-island multicomponent fiber
is photographed similarly to the case of the width of the sea
component region, and an image is photographed at a magnification
that allows 150 or more island components to be observed in
multifilaments of the multicomponent fiber. Diameters of 150 island
components randomly extracted from the photographed image are
measured. The island component diameter herein means a diameter of
an imaginary circle circumscribed to a cut surface at three or more
points where the cut surface is a cross section in a vertical
direction with respect the fiber axis from the image that is
two-dimensionally photographed. The value of the island component
diameter is measured to the first decimal place in a unit of nm,
and rounded off to an integer. The diameters of the 150
photographed island components are measured, and the maximum value
thereof is defined as the maximum diameter (d) of the island
component.
[0164] The maximum diameter (d) of the island component is
preferably smaller than the width (H) of the sea component region,
and from the viewpoint of suppressing hindrance to crack formation
as described above, H/d is more preferably 2.0 or more. The island
component diameter is preferably 100 to 5000 nm. When the island
component diameter is in this range, an effect of improving sea
removal efficiency is obtained and, further, the ultrafine fiber
subjected to the sea removal treatment has high quality and
excellent characteristics. When the fiber diameter is 100 to 5000
nm, the effect of the sea component region becomes more remarkable
without hindering the sea removal treatment, and also ultrafine
fibers having extreme thinness unable to be achieved by a single
spinning technique can be obtained.
[0165] Ultrafine fibers generated from the multicomponent fiber,
when having a diameter of 5 .mu.m or less, have soft touch and
fineness that cannot be achieved with common fibers (several tens
.mu.m). By taking advantage of these characteristics, the ultrafine
fibers can be used, for example, as a material for artificial
leathers and high-texture apparels. In addition, by taking
advantage of reduced fiber gaps, the ultrafine fibers can be formed
into a high-density fabric, and used for sports wear required to
have windbreaking performance and water repellency. Extremely
thinned fibers enter fine grooves, and the specific surface area
increases and contaminants are caught in fine voids between fibers.
Therefore, high absorptivity and dust collecting performance are
exhibited. By taking advantage of these characteristics, the
ultrafine fibers can be used for wiping cloths and precise
polishing cloths for precision equipment in applications of
industrial materials. Since a high level of wiping performance and
the like is required particularly when the ultrafine fibers are to
be used for polishing and wiping for IT, the diameter of the
ultrafine fiber is preferably as small as possible. A range of 100
to 1000 nm may be a more preferred range. The island component
diameter thereof may be less than 100 nm, but the island component
diameter is preferably 100 nm or more from the viewpoint of
handling characteristics during the sea removal treatment.
[0166] The multicomponent fiber is suitably used for production of
the above-mentioned ultrafine fibers and fiber products composed of
the ultrafine fibers. Therefore, improvement of basic
characteristics of ultrafine fibers such as mechanical properties,
which has been difficult heretofore, can be achieved, and by
improving homogeneity of the resulting ultrafine fiber bundles,
fiber products composed thereof can be improved in quality.
[0167] In multicomponent fibers intended to generate ultrafine
fibers, generally the island polymer is a hardly soluble component
and the sea polymer is an easily soluble component. For example,
the island polymer may be a polyethylene terephthalate (PET), and
the sea polymer may be a copolymerized PET to form an easily
soluble component. In this case, the copolymerized PET as the sea
polymer has a higher solubility with a solvent as compared to the
island polymer. However, when efficiency of the sea removal
treatment is poor so that it takes a long time for the sea polymer
to be completely removed, even the island polymer may be treated
with a solvent. Particularly when the island component diameter is
small, this effect is very significant. Particularly when the
island component diameter is in the order of .mu.m, the specific
surface area thereof increases so that the quality may be degraded,
for example, mechanical properties of ultrafine fiber bundles are
deteriorated, or the island component arranged on the outermost
layer and the island component arranged on the inner layer in the
multicomponent fiber have different diameters.
[0168] The sea component region is arranged, and thus the inner
part of the multicomponent fiber is affected by the treatment with
a solvent in the early stage of the sea removal treatment so that
degradation in quality which has been the problem with conventional
multicomponent fibers is extremely small. Even if the island
packing density is increased, ultrafine fibers composed of the
island polymer can be produced with a high yield with respect to
multicomponent fibers as a raw material by increasing the ratio of
the island polymer to the sea polymer. Further, by increasing the
island polymer ratio, stress in a process for producing fiber
(spinning and drawing) can be efficiently propagated to island
components, and therefore the fiber structure of the island
component can be highly generated. Therefore, mechanical properties
of ultrafine fibers can be improved, and also orientation
crystallization of the island component proceeds so that its
resistance to a solvent can be improved.
[0169] As described above, owing to existence of the sea component
region as a requirement, reduction in sea removal efficiency, which
has raised a problem heretofore, can be avoided even if the island
packing density is increased. Therefore, fibers can be extremely
thinned by increasing the number of islands and, further, by
increasing the ratio of the island component, ultrafine fibers
having excellent basic characteristics such as mechanical
properties can be stably produced with high productivity. The sea
component region having the above-mentioned effect exhibits the
effects including those illustrated in FIGS. 13, 14 and 20 to 26
when our range is satisfied. Particularly, it is effective that the
sea component region is arranged inward from the surface of the
multicomponent fiber. When the sea component region exists with a
certain degree of cross-section area ratio, division of the
multicomponent fiber due to crack formation efficiently proceeds.
Further, to advance the concept of division of the multicomponent
fiber due to crack formation, it is preferred that the sea-island
component region is widely arranged on the cross section of the
multicomponent fiber. Particularly, it is preferred that the sea
component region is cruciformly arranged as shown in FIG. 13.
[0170] The sea-island multicomponent fiber preferably has a
strength at break of 0.5 to 10.0 cN/dtex and an elongation of 5 to
700%. The strength herein is a value obtained by determining a
load-extension curve of multifilaments under conditions as shown in
JIS L 1013 (1999), and dividing the load value at rupture by the
initial fineness, and the elongation is a value obtained by
dividing the extension at rupture by the initial test length. The
initial fineness means a value obtained by calculating the mass per
10000 m from the simple average of a plurality of measurements of
the mass of the fiber per unit length. The strength at break of the
sea-island multicomponent fiber is preferably 0.5 cN/dtex or more
in view of passage through the post processing step and
endurability of the fiber in actual use. The upper limit of the
strength at break of fibers that can be produced is about 10.0
cN/dtex. The elongation is preferably 5% or more in view of passage
through the post processing step. An upper limit value of the
elongation of fibers that can be produced is generally 700%. The
strength at break and elongation can be adjusted by controlling
conditions in the production process according to the intended
application.
[0171] When ultrafine fibers obtained from the sea-island
multicomponent fiber are used in applications of general clothes
such as inner and outer clothes, it is preferred that the strength
at break is 1.0 to 4.0 cN/dtex and the elongation is 20 to 40%. In
applications of sports wear and the like in which use conditions
are relatively severe, it is preferred that the strength at break
is 3.0 to 5.0 cN/dtex and the elongation is 10 to 40%. In
applications other than those of clothes, the ultrafine fibers may
be used for wiping cloths and polishing cloths. In these
applications, a fiber product is rubbed against an object while
being pulled under weight. Thus, it is preferred that the strength
at break is 1.0 cN/dtex or more and the elongation is 10% or more.
By setting the mechanical properties in the above-mentioned range,
for example, the ultrafine fiber is prevented from being cut to
come off during wiping or the like.
[0172] The sea-island multicomponent fiber can be formed into a
variety of intermediates such as fiber winding packages and tows,
cut fibers, cotton, fiber balls, cords, piles, fabrics and nonwoven
fabrics, and subjected to a sea polymer elution treatment to
generate ultrafine fibers, from which various fiber products are
obtained. The sea-island multicomponent fiber can be used in an
untreated state, partially freed of a sea polymer, or subjected to
a treatment for removal of an island polymer to obtain a fiber
product.
[0173] The fiber products may be used in applications of livingware
such as common clothes such as jackets, skirts, pants and
underclothes, sports wear, clothing materials, interior products
such as carpets, sofas and curtains, vehicle interiors such as car
seats, cosmetics, cosmetic masks, wiping cloths and health
equipment; applications of environmental/industrial materials such
as polishing cloths, filters, harmful substance removal products
and separators for batteries; and applications of medical products
such as sutures, scaffolds, artificial blood vessels and blood
filters.
[0174] A method of producing the multicomponent fiber and a
composite spinneret that can be used in production of the
multicomponent fiber will be described in detail below with
reference to the drawings.
[0175] FIG. 1 is a schematic sectional view of a composite
spinneret as one example. FIG. 2 is a schematic sectional view of a
composite spinneret 7, a spinning pack 8 that is used along with
the composite spinneret 7, a cooler 9, and a periphery thereof.
FIG. 4 is a plan view of a nozzle plate that is used as one of our
examples, and FIG. 5 is a partial enlarged plan view of FIG. 4.
FIGS. 3, 7, 8, 9, 11, 12, 18 and 27 to 35 are partial enlarged plan
views of nozzle plates that are used in various examples. They are
schematic views and depictions in the drawings are simplified. In
the composite spinneret, the number of holes and grooves, their
dimension ratios and so on are not limited to those shown in the
drawings, and can be changed in accordance with the examples.
[0176] The composite spinneret 7 used in the example is mounted in
the spinning pack 8, and fixed in a spin block 10 as shown in FIG.
2. The cooler 9 is provided below the composite spinneret 7. The
composite spinneret 7 is formed by stacking a distribution device 1
for distributing polymers, a nozzle plate 2 and a flow contraction
plate 3 in order as shown in FIG. 1. As shown in FIG. 5, the nozzle
plate 2 is provided with island discharge holes 13 for discharging
an island polymer, or sea discharge holes 12 for discharging a sea
polymer, and sea-island discharge hole groups with the island
discharge holes 13 and the sea discharge holes 12 forming a group,
and sea component region forming hole groups with only the sea
discharge holes 12 forming a group form a nozzle hole collection
18.
[0177] A polymer of each component distributed by a distribution
device (not illustrated) is discharged from the island discharge
holes 13 or the sea discharge holes 12 shown in FIG. 5, and a
polymer of each component merges with each other to form a
composite polymer flow. Thereafter, the composite polymer flow
passes through introducting holes 4 and flow contraction holes 5 of
the flow contraction plate shown in FIG. 1, and is discharged from
spinneret discharge holes 6. The composite polymer flow is
discharged from the spinneret discharge holes 6 shown in FIG. 2,
and then cooled and solidified by an air flow jetted from the
cooler 9. Thereafter, an oil is supplied to the composite polymer
flow, and then the composite polymer flow is wound as a sea-island
multicomponent fiber. In FIG. 2, a circular cooler 9 that jets an
air flow circularly and inward, but a cooler that jets an air flow
in one direction may be used.
[0178] Means for making it possible to reduce the sea removal time
by improving sea removal efficiency during sea removal treatment
will now be described.
[0179] As illustrated in FIG. 5, the nozzle plate used in the
composite spinneret in the example has a sea component region
forming hole group including a plurality of sea discharge holes 12,
and at least one discharge hole group for forming a sea-island
region (hereinafter, referred to as a "sea-island discharge hole
group"), the discharge hole group including any of the following
(i) to (v), and these discharge holes are combined to form one
nozzle hole collection. The sea component region forming hole group
is continuously arranged with being between the sea-island
discharge hole group. An arrangement of the sea-island discharge
hole group including the combination (i) is illustrated in FIG. 5,
an arrangement of the sea-island discharge hole group including the
discharge holes (ii) is illustrated in FIG. 3, an arrangement of
the sea-island discharge hole group including the combination (iii)
is illustrated in FIG. 9, an arrangement of the sea-island
discharge hole group including the combination (iv) is illustrated
in FIG. 11, and an arrangement of the sea-island discharge hole
group including the combination (v) is illustrated in FIG. 18.
[0180] (i) the sea discharge holes 12 and the island discharge
holes 13
[0181] (ii) the composite polymer discharge holes 15
[0182] (iii) the sea discharge holes 12 and the composite polymer
discharge holes 15
[0183] (iv) the island discharge holes 13 and the composite polymer
discharge holes 15
[0184] (v) the sea discharge holes 12, the island discharge holes
13 and the composite polymer discharge holes 15
[0185] Thus, the polymers discharged from the sea-island discharge
hole group and the sea component region forming hole group of the
nozzle plate merge with each other in the introducting hole, and
are then discharged from the spinneret discharge hole to form a
multicomponent fiber having a sea component region and a sea-island
region.
[0186] As one example, a principle that a sea component region can
be formed where the arrangement of the sea-island discharge hole
group corresponds to (i) will be described in accordance with the
flow of the polymer.
[0187] The island polymer and the sea polymer are simultaneously
discharged to the downstream side from the nozzle plate 2 shown in
FIG. 1. The discharged polymers flow along a polymer spinning
passage direction, and are widened in a direction vertical to the
polymer spinning passage direction so that neighboring polymers
merge with each other to form a composite polymer flow. To produce
a multicomponent fiber having the sea component region 44 as shown
in FIG. 13, it is effective that the nozzle plate is provided with
a sea-island discharge hole group including only the sea discharge
holes 12 as shown in FIG. 5. However, the discharged polymer moves
to be widened to fill a channel space and, therefore, it is
difficult to form the sea component region 44 on the cross section
of the multicomponent fiber merely by increasing the distance
between sea-island discharge hole groups as shown in FIG. 17. In a
nozzle plate as shown in FIG. 17, widening of the polymer is
enlarged. Therefore, the cross section of the fiber is destabilized
due to deviation of the arrangement of the island polymer and the
like so that island components are not uniformly formed in the
multicomponent fiber.
[0188] It is effective that the sea-island discharge hole group is
arranged on the composite spinneret to be separated into four
parts, and the sea discharge holes 12 are provided in the resulting
gap as shown in FIG. 5. In the nozzle plate shown in FIG. 5, sea
discharge holes 12a for the sea component region exist in the gap
formed by separation of the sea-island discharge hole group, and
thus the widening of the sea-island region can be suppressed to
inhibit destabilization of the fiber cross section.
[0189] In FIG. 5, two or less island discharge holes 13 are
arranged on an imaginary circumference with the sea discharge hole
12a as a center, the radius of which is a center-to-center distance
between the sea discharge hole 12a and a discharge hole closest to
the sea discharge hole 12a among the sea discharge holes 12 or the
island discharge holes 13 close to the sea discharge hole 12a so
that a sea component region forming hole group including a
plurality of sea discharge holes 12a is formed. The sea component
region forming hole group is continuously arranged with a part of
the sea-island discharge hole group held between both sides as
shown in FIG. 5 so that a multicomponent fiber having the sea
component region 44 as shown in FIG. 3 is obtained. In the nozzle
plate shown in FIG. 5, the sea discharge hole 12 is arranged at
each apex of a hexagonal lattice as an arrangement pattern of holes
in the sea-island discharge hole group, and the island discharge
hole 13 is arranged at the gravity center position of the hexagon
that forms the lattice. The hole arrangement shown in FIG. 5
satisfies n=6 and m=2, with the sea discharge holes 12 surrounding
the periphery of the island discharge hole 13. Therefore, even when
the island polymer ratio increases, the sea polymer necessarily
exists between island polymers so that merging of polymers from
neighboring island discharge holes can be suppressed.
[0190] As other arrangement patterns of the sea-island discharge
hole group, a tetragonal lattice is shown in FIG. 7, and a trigonal
lattice is shown in FIG. 8.
[0191] The arrangement shown in FIG. 7 satisfies n=4 and m=3. In
this case, as compared to the hexagonal lattice shown in FIG. 5,
the distance between neighboring island discharge holes can be
reduced and, therefore, the hole packing density can be further
increased. The arrangement shown in FIG. 8 satisfies n=3 and m=5.
In this case, as compared to the tetragonal lattice shown in FIG.
7, neighboring island discharge holes 13 can be made closer to each
other. Therefore, the hole packing density can be further
increased. Thus, in terms of an arrangement pattern of the
sea-island discharge hole group, the hole packing density can be
increased in the order of a trigonal lattice, a tetragonal lattice
and a hexagonal lattice. However, spinning conditions such as the
island polymer ratio may be restricted and, therefore, it is
preferred to determine the arrangement pattern of holes in
accordance with the cross-section form of an intended
multicomponent fiber.
[0192] Next, the distribution device will be described with
reference to FIG. 6. FIG. 6 is a partial enlarged longitudinal
sectional view of a nozzle plate. The distribution device is formed
by stacking one or more thick plates called measuring plate(s) 16
and one or more thin plates called distribution plate(s) 17. The
measuring plate 16 and the distribution plate 17 are placed by a
positioning pin to align with the center position (core) of the
composite spinneret 7. The measuring plate 16 and the distribution
plate 17 can also be fixed by a screw or a bolt. Also, it is
preferred that the plates are metal-bonded (diffusion-bonded) by
thermocompression bonding or the like for suppressing leakage of a
polymer from a gap between members.
[0193] The measuring plate 16 in FIG. 6 is processed to have a
channel groove and a channel hole for distributing the island
polymer and the sea polymer and supplying the polymers to the
distribution plate 17. The channel hole applies a constant channel
pressure loss to the polymer so that the polymer can be uniformly
supplied to an inflow channel of the distribution plate 17
positioned on the top part.
[0194] The distribution plate 17 is provided with a distribution
groove 51 and/or a distribution hole 52 to distribute the island
polymer and the sea polymer. The distribution groove 51 serves to
guide the polymer in a direction vertical to the polymer spinning
passage direction (leftward arrows and rightward arrows in FIG. 6),
and the distribution hole 52 serves to guide the polymer in the
polymer spinning passage direction (downward arrows in FIG. 6).
When the distribution plate 17 having the distribution hole 52 and
the distribution plate 17 having the distribution groove 51 are
alternately stacked, one distribution groove 51 communicating with
one distribution hole 52 at a position on the downstream side in
the polymer spinning passage direction is formed. Therefore, a
tournament type channel that forms a plurality of distribution
holes 52 each communicating with the end of the distribution groove
51 is formed so that the polymer of each component distributed by
the measuring plate 16 can be evenly divided into smaller quantity
polymers.
[0195] Then, as another example, the arrangement corresponding to
(ii) will be described with reference to FIG. 3 that is a partial
enlarged plan view of the nozzle plate and FIG. 10 that is a
schematic longitudinal sectional view of the composite spinneret.
The nozzle plate shown in FIG. 3 shows that the sea-island
discharge hole group includes composite polymer discharge holes.
The nozzle plate shown in FIG. 3 is generally called a pipe type
spinneret, with the sea-island discharge hole group including
composite polymer discharge holes 15. As shown in FIG. 10, a
distribution device 64 is provided with pipes 62 to supply the
island polymer, sea polymer introduction channels 61 to supply the
sea polymer, and a sea polymer distribution chamber 63
communicating with the sea polymer introduction channels 61. The
pipes 62 of the distribution device 64 are formed to communicate
with composite polymer discharge holes 66 of the sea-island
discharge hole group on a one-to-one basis. The sea polymer
distribution chamber 63 is formed to communicate with composite
polymer discharge holes 66 and a sea discharge hole 65 of the sea
component region forming hole group. The island polymer discharged
from the pipes 62 of the sea-island discharge hole group and the
sea polymer discharged from the sea polymer distribution chamber 63
merge with each other in the composite polymer discharge hole 66.
The resulting composite polymer flow has a sheath-core structure in
which the island polymer forms a core and the sea polymer forms a
sheath.
[0196] On the other hand, the sea polymer is supplied from the sea
polymer distribution chamber 63 to the sea discharge hole 65 of the
sea component region forming hole group. The composite polymer
discharged from the sea-island discharge hole group and the sea
polymer discharged from the sea component region forming hole group
merge with each other on the lower surface of a nozzle plate 67.
Since the sea polymer discharged from the sea component region
forming hole group exists between composite polymer flows, a
multicomponent fiber with a sea component region formed on our
cross section can be produced.
[0197] Then, as another example, a case where the arrangement of a
sea-island discharge hole group 19 corresponds to (iii) will be
described with reference to FIG. 9. In the nozzle plate in FIG. 9,
the sea-island discharge hole group includes composite polymer
discharge holes 15 and sea discharge holes 12. Each polymer
supplied from a distribution device (not illustrated) is
distributed, and supplied to each hole of the nozzle plate. In the
composite polymer discharge hole 15 of the sea-island discharge
hole group shown in FIG. 9, the sea polymer and the island polymer
merge with each other to form a composite polymer flow, and the
composite polymer flow is discharged. In the sea discharge hole 12,
only the sea polymer is discharged. The polymers are discharged
from the composite polymer discharge holes 15 and the sea discharge
holes 12 of the sea-island discharge hole group, and the polymers
merge with each other to form a composite polymer flow having a
sea-island form. The feature of the form shown in FIG. 9 is that
the sea-island discharge hole group is provided with the sea
discharge holes 12 in addition to the composite polymer discharge
holes 15. Therefore, the sea polymer is arranged on the periphery
of the composite polymer flow in a sheath-core form (core: island
polymer and sheath: sea polymer), which is formed by the composite
polymer discharge holes 15. Accordingly, in the multicomponent
fiber shown in FIG. 13, the distance between the island components
43 can be increased. Therefore, a solvent easily infiltrates
between the island components 43 in the sea removal treatment so
that the sea removal time of the sea polymer can be reduced. In
such a form, generally island polymers may merge with each other as
the ratio of the island component is increased, but this form is
preferred from the viewpoint of suppressing merging of island
polymers because the sea polymer exists in a large amount between
island polymers.
[0198] Then, as another example, a case where the arrangement of
the sea-island discharge hole group 19 corresponds to (iv) will be
described. FIG. 11 is a partial enlarged plan view of a nozzle
plate. In the nozzle plate in FIG. 11, the sea-island discharge
hole group includes composite polymer discharge holes 15 and island
discharge holes 13. Each polymer supplied from a distribution
device (not illustrated) is distributed, and supplied to each hole
of the nozzle plate. In the composite polymer discharge hole 15 of
the sea-island discharge hole group, the sea polymer and the island
polymer merge with each other, and the resulting composite polymer
flow is discharged. In the island discharge hole 13, only the
island polymer is discharged. The feature of the form shown in FIG.
11 is that the island discharge hole group is provided with the
island discharge holes 13 in addition to the composite polymer
discharge holes 15. Therefore, a composite polymer flow with the
island polymer existing on the periphery of a polymer flow in a
sheath-core form (core: island polymer and sheath: sea polymer) can
be formed. As a result, as compared to the arrangement (ii) shown
in FIG. 3, the hole packing density can be increased so that a
larger number of island components can be arranged on the cross
section of the multicomponent fiber.
[0199] Then, as another example, a case where the arrangement of
the sea-island discharge hole group corresponds to (v) will be
described. FIG. 18 is a partial enlarged plan view of a nozzle
plate. In the nozzle plate in FIG. 18, the sea-island discharge
hole group includes composite polymer discharge holes 15, sea
discharge holes 12 and island discharge holes 13. Each polymer
supplied from a distribution device (not illustrated) is
distributed, and supplied to each hole of the nozzle plate. In the
composite polymer discharge hole 15 of the sea-island discharge
hole group, the sea polymer and the island polymer merge with each
other, and the resulting composite polymer flow is discharged. In
the island discharge hole 13, only the island polymer is
discharged, and in the sea discharge hole 12, only the sea polymer
is discharged. The feature of the nozzle plate shown in FIG. 18 is
that the island discharge hole group is provided with the island
discharge holes 12 and the sea discharge holes 13 in addition to
the composite polymer discharge holes 15. Therefore, a composite
polymer flow with a sea polymer surrounding a sheath-core (core:
island polymer and sheath: sea polymer) polymer and an island
polymer can be formed. Accordingly, the number of island components
in the multicomponent fiber is larger as compared to the
arrangement (iv) shown in FIG. 11, and smaller as compared to the
arrangement (iii) shown in FIG. 9. On the other hand, the distance
between island components is larger as compared to the arrangement
(iii) shown in FIG. 9, and smaller as compared to the arrangement
(iv) shown in FIG. 11. Therefore, the effect of increasing the
number of islands and improving the sea removal efficiency of the
sea polymer is not lower as compared to the arrangement (iii) and
not higher as compared to the arrangement (iv).
[0200] FIGS. 9, 11 and 18 in which a pipe type spinneret is used
show an example in which a composite polymer flow formed by the
composite polymer discharge holes 15 has a sheath-core structure of
an island polymer and a sea polymer, but this disclosure is not
limited to the example. The composite polymer flow may be a
side-by-side form, a multi-layered form or a sea-island form, and
can be formed diversely according to the state of distribution or
merging of the polymers in the distribution device.
[0201] Also, when the sea component region forming hole group is
continuously arranged from the outer circumference of a
circumscribed circle of the nozzle hole collection 18 to a region
with a radius of 0.5R or less where R is the radius of the
circumscribed circle of the nozzle hole collection 18, with a part
of the sea-island discharge hole group surrounding both sides of
the sea component region forming hole group as shown in FIG. 12,
good fibers can be achieved. A removing discharge hole group is not
necessarily cruciformly arranged, and may be arranged in a radial
form, a latticed form, or in the form of three parallel lines, and
the important point here is that the sea component region forming
hole group is arranged with a part of the sea-island discharge hole
group being in contact with both sides.
[0202] Next, in common with the composite spinnerets and nozzle
plates shown in FIGS. 1-8, 10 and 12, shapes and the like of the
members will be described in detail.
[0203] The shape of the composite spinneret 7 shown in FIG. 1, when
seen from above, is not limited to a circular shape, and may be a
tetragonal shape or a polygonal shape. The arrangement of the
spinneret discharge holes 6 in the composite spinneret 7 shown in
FIG. 1 or the nozzle hole collection 18 shown in FIG. 4 may be
changed in accordance with the number of sea-island multicomponent
fibers, the number of yarn threads and a cooler. When the cooler 9
shown in FIG. 2 is a circular cooler, it is preferred to circularly
arrange the spinneret discharge holes or the nozzle hole collection
over one line or a plurality of lines. When the cooler 9 shown in
FIG. 2 is a unidirectional cooler, it is preferred to arrange the
spinneret discharge holes or the nozzle hole collection in
zigzags.
[0204] Each channel hole to discharge the polymer of each component
may have any shape such as a circular shape, a polygonal shape or a
star shape. Depending on the example, each channel hole may be made
variable such that, for example, the cross section is changed along
the polymer spinning passage direction.
[0205] The introducting hole 4 shown in FIG. 1 is provided with a
definite approach zone extending from the lower surface of the
nozzle plate 2 in the polymer spinning passage direction, and thus
serves to stabilize the composite polymer flow by reducing the flow
rate difference immediately after the island polymer and the sea
polymer merge with each other. It is preferred that the hole
diameter of the introducting hole 4 is larger than the diameter of
a circumscribed circle of the nozzle hole collection provided on
the nozzle plate 2, and that the ratio of the cross-section area of
the circumscribed circle of the nozzle hole collection to the
cross-section area of the introducting hole 4 is as small as
possible. When the introducting hole 4 is formed as described
above, widening of each polymer discharged from the nozzle plate 2
is suppressed so that the composite polymer flow can be
stabilized.
[0206] When the reduction angle .alpha. of a channel extending from
the introducting hole 4 to the spinneret discharge hole 6 in the
flow contraction hole 5 shown in FIG. 1 is set to fall in the range
of 50 to 90.degree., the composite spinneret 7 can be downsized,
and an instable phenomenon such as draw resonance of the composite
polymer flow can be suppressed to stably supply the composite
polymer flow.
[0207] Next, in common with the composite spinneret of the example,
a method of producing a multicomponent fiber will be described in
detail.
[0208] The method of producing a multicomponent fiber can be
carried out using a known composite spinning machine, and it is
preferred to use the composite spinneret 7 shown in FIG. 1 from the
viewpoint of controlling our unique composite cross section.
[0209] We produce a sea-island multicomponent fiber to generate
ultrafine fibers and, therefore, examples of the island polymer and
sea polymer include melt-moldable polymers such as polyethylene
terephthalate or copolymers thereof, polyethylene naphthalate,
polybutylene terephthalate, polytrimethylene terephthalate,
polypropylene, polyolefins, polycarbonate, polyacrylate, polyamide,
polylactic acid and thermoplastic polyurethane. Particularly,
polycondensation-based polymers represented by polyester and
polyamide are preferred because they have a high melting point. The
melting point of the polymer is preferably 165.degree. C. or more
in view of high heat resistance. The polymer may contain various
kinds of additives such as an inorganic material such as titanium
oxide, silica or barium oxide, a colorant such as carbon black, a
dye or a pigment, a flame retardant, a fluorescent brightening
agent, an antioxidant and an ultraviolet absorber. When considering
a sea removal treatment or an island removal treatment, the polymer
can be selected from melt-moldable polymers which are more easily
soluble than other components, such as polyester and copolymers
thereof, polylactic acid, polyamide, polystyrene and copolymers
thereof, polyethylene and polyvinyl alcohol. The easily soluble
component is preferably copolymerized polyester, polylactic acid,
polyvinyl alcohol or the like which is easily soluble in an aqueous
solvent or hot water, and in particular, polyester and polylactic
acid copolymerized with polyethylene glycol and/or sodium
sulfoisophthalic acid alone or in combination are preferable from
the viewpoint of spinnability and solubility in low-concentration
aqueous solvents. Polyester copolymerized with sodium
sulfoisophthalic acid alone is particularly preferable from the
viewpoint of the ease of sea removal and fiber openability of the
resulting ultrafine fibers.
[0210] To identify an appropriate combination of a hardly soluble
component and an easily soluble component as described above, it is
practical to select an appropriate hardly soluble component
suitable for the intended use and then select an appropriate easily
soluble component that can be spun at the same spinning
temperature, on the basis of the melting point of the hardly
soluble component. When the molecular weight and the like of each
component is adjusted with the above-mentioned melt viscosity ratio
taken into consideration, homogeneity of island components of the
sea-island multicomponent fiber in terms of fiber diameter and
cross-sectional shape can be improved. When ultrafine fibers are to
be generated from the sea-island multicomponent fiber, a difference
in speed of dissolution between the hardly soluble component and
the easily soluble component in a solvent used for sea removal is
preferably large from the viewpoint of stability of the
cross-sectional shape and retention of mechanical properties of
ultrafine fibers, and a combination should be selected from the
above-mentioned polymers based on a dissolution speed ratio ranging
from 10 to 3000. From the viewpoint of their melting points,
preferred combinations of polymers for obtaining ultrafine fibers
from the sea-island multicomponent fiber include, for example,
combinations of polyethylene terephthalate copolymerized with 1 to
10 mol % of 5-sodium sulfoisophthalic acid as a sea polymer and
polyethylene terephthalate or polyethylene naphthalate as an island
polymer; and combinations of polylactic acid as a sea polymer and
nylon 6, polytrimethylene terephthalate or polybutylene
terephthalate as an island polymer.
[0211] The spinning temperature in spinning of the sea-island
multicomponent fiber is equal to or higher than a temperature at
which one of two or more polymers that has the highest melting
point or viscosity is flowable. The temperature at which the
polymer is flowable, although it depends on the molecular weight,
is indicated by the melting point of the polymer, and may be set at
up to 60.degree. C. above the melting point. Such a temperature is
preferable because thermal decomposition of polymers in a spinning
head or a spinning pack is prevented to suppress a decrease in
molecular weight. The through-put rate of the polymer in the
production method may be 0.1 g/min/hole to 20.0 g/min/hole per
nozzle hole as a range that allows the polymer to be stably
discharged. It is preferable that at this time the pressure loss in
the nozzle hole, which can ensure discharge stability, is taken
into consideration. It is preferred that, with the pressure loss
herein considered to be 0.1 MPa to 40 MPa, the through-put rate is
selected from the above-mentioned range in relation to the melt
viscosity of the polymer, the nozzle hole diameter and the nozzle
hole length. In the production method, the ratio of the island
component (hardly soluble component) to the sea component (easily
soluble component) can be selected from 10/90 to 95/5 in terms of
the ratio of sea component/island component on the basis of the
mass of each polymer through-put rate. It is preferred that the
ratio of the island component is increased in the ratio of sea
component/island component from the viewpoint of productivity of
ultrafine fibers. The ratio of sea component/island component is
more preferably 20/80 to 50/50 for producing multicomponent fibers
and ultrafine fibers efficiently while maintaining stability by the
production method from the viewpoint of long-term stability of the
cross section of the sea-island multicomponent fiber. The
sea-island composite polymer flow thus discharged from the
composite spinneret is cooled and solidified, supplied with a
spinning oil, and taken up by a roller, the circumferential speed
of which is controlled, to form a sea-island multicomponent fiber.
While the spinning velocity may be determined from the through-put
rate and the intended fiber diameter, the spinning velocity is
preferably 100 to 7000 m/min in the production method. The fiber
can be made to have not only a circular shape, but also a shape
other than a circular shape, such as a trigonal shape or a flat
shape, or hollowed by changing the shape of the spinneret discharge
hole 6. Further, the multicomponent fiber may have one yarn thread
as a monofilament, or two or more yarn threads as a multifilament.
The spun multicomponent fiber may be wound up and then drawn from
the viewpoint of improving mechanical properties by enhancing
orientation, or may be subsequently drawn without being wound up.
As the drawing conditions, for example, in a drawing machine
including at least one pair of rollers, a fiber composed of a
thermoplastic polymer that is generally capable of being melt-spun
is well drawn out in a fiber axis direction in response to the
circumferential speed ratio of a first roller set at a temperature
that is not lower than the glass transition temperature and not
higher than the melting point to a second roller set at a
temperature equivalent to the crystallization temperature, and the
fiber is subjected to heat-setting and wound up so that the
multicomponent fiber having a sea-island multicomponent fiber cross
section as shown in FIG. 7 can be obtained.
[0212] In a polymer exhibiting no glass transition, the dynamic
elasticity (tans) of the multicomponent fiber is measured, and a
temperature equal to or higher than the peak temperature on the
high-temperature side of the obtained tans may be selected as a
preheating temperature. It is also preferred to perform the drawing
step in multiple stages from the viewpoint of increasing the
stretch ratio to improve mechanical properties.
[0213] To obtain ultrafine fibers from the thus obtained sea-island
multicomponent fiber, the multicomponent fiber is immersed in a
solvent or the like in which an easily soluble component can be
removed so that the easily soluble component is removed, i.e. a sea
removal step is performed, and thus ultrafine fibers composed of a
hardly soluble component can be obtained. When the easily soluble
component is copolymerized PET, polylactic acid (PLA) or the like
copolymerized with 5-sodium sulfoisophthalic acid or the like, an
aqueous alkali solution such as an aqueous sodium hydroxide
solution can be used. As a method of treating the multicomponent
fiber with an aqueous alkali solution, for example, the
multicomponent fiber or a fiber structure formed thereof may be
immersed in an aqueous alkali solution. Heating the aqueous alkali
solution to 50.degree. C. or more is preferable because hydrolysis
can be accelerated. The use of a fluid dyeing machine or the like
for the treatment is preferable from an industrial point of view
because a large batch can be processed at a time to achieve high
productivity. Thus, the method of producing the ultrafine fiber is
described above on the basis of a common melt spinning technique,
but needless to say, meltblowing and spunbonding can be used for
its production, and further, a wet or a dry-wet solution spinning
technique can also serve for its production.
EXAMPLES
[0214] The ultrafine fiber will be described in detail below by way
of examples. For examples and comparative examples, evaluations
were performed as described below.
A. Intrinsic Viscosity (IV)
[0215] The measurement was performed at 25.degree. C. using
ortho-chlorophenol as a solvent.
B. Melt Viscosity of Polymers
[0216] Chips of a polymer were dried in a vacuum dryer down to a
moisture content of 200 ppm or less, and subjected to melt
viscosity measurement in Capilograph 1B manufactured by Toyo Seiki
Seisaku-sho, Ltd. in which the strain speed was changed in stages.
The measuring temperature was set to about the spinning
temperature, and the melt viscosity at 1,216 s.sup.-1 was shown in
examples and comparative examples. The measurement was started 5
minutes after feeding a sample into a heating furnace and performed
in a nitrogen atmosphere.
C. Fineness
[0217] In a sea-island multicomponent fiber, the mass per 100 m was
measured and multiplied by 100 to calculate the fineness. In an
ultrafine fiber obtained by removing 99% or more of a sea component
from the multicomponent fiber, the mass per 10 m was measured and
multiplied by 1000 to calculate the fineness. Weighing of these
samples was performed in an atmosphere at a temperature of
25.degree. C. and a humidity of 55% RH.
[0218] The same procedure was repeated 10 times, and the simple
average thereof was rounded off to the first decimal place in a
unit of dtex to determine the fineness. Removal sea is evaluated
based on the weight reduction rate of the sample on the premise
that the sea removal rate of the sea polymer and the weight
reduction rate of the sample (equation described below) are the
same value.
Weight reduction rate (%)=(1-weight of sample after elution
treatment/weight of sample before elution treatment).times.100
D. Mechanical Properties of Fibers
[0219] A tensile tester "Tensilon" (registered trademark) Model
UCT-100 manufactured by Orientec Co., Ltd. was used to obtain a
stress-strain curve of each of the multicomponent fiber and the
ultrafine fiber under the conditions of a sample length of 20 cm
and a tension speed of 100%/min. The load at rupture was measured,
and the load was divided by the initial fineness to calculate the
strength. The strain at rupture was measured, and divided by the
sample length to calculate the elongation. Evaluations were
performed with a unit of cN/dtex for the strength and a unit of %
for the elongation. For each of the strength and elongation, the
above-mentioned procedure was repeated 5 times for each level, and
the simple average of the obtained results was determined. The
strength was rounded off to the first decimal place, and the
elongation was rounded off to an integer.
[0220] E. Parameters
[0221] (multicomponent fiber diameter D, multicomponent fiber
cross-section area Ac, island component maximum diameter d,
inter-island component distance W, sea component region width H,
sea component region length L, sea component region total
cross-section area As, and neighboring island component
parallelization degree .theta.) in cross-section observation of
multicomponent fiber.
[0222] The obtained sea-island multicomponent fiber was embedded in
an epoxy resin, the embedded sample was frozen by Cryosectioning
System Model FC-4E manufactured by Reichert, and cut by
Reichert-Nissei Ultracut N equipped with a diamond knife, and the
cross section of the multicomponent fiber was then photographed
using a scanning electron microscope (SEM) Model VE-7800
manufactured by KEYENCE CORPORATION.
[0223] The multicomponent fiber diameter D, the island component
maximum diameter d, the inter-island component distance W, the sea
component region width H, the sea component region length L and
neighboring island component parallelization degree .theta.) were
evaluated from randomly selected images using image processing
software (WINROOF).
[0224] For the island component maximum diameter d, an image was
photographed at a magnification allowing 150 or more island
components to be observed, and island component diameters of 150
island components randomly extracted from the photographed image
were measured. The value of the island component diameter is
measured to the first decimal place in a unit of nm, and rounded
off to an integer. The diameters of the 150 photographed island
components were measured, and the maximum value thereof was defined
as the island component maximum diameter d.
[0225] The multicomponent fiber diameter D, the inter-island
component distance W, the sea component region width H and the sea
component region length L were each measured to the second decimal
place in a unit of .mu.m from the cross-section image for randomly
selected 10 or more multicomponent fibers in multifilaments, and
the measured value was rounded off to the first decimal place. The
above procedure was carried out for 10 or more spots, and the
simple number average thereof was determined. From the thus
obtained multicomponent fiber diameter D, sea component region
width H and sea component region length L, the multicomponent fiber
cross-section area Ac and the sea component region total
cross-section area As per multicomponent fiber were determined.
[0226] The neighboring island component parallelization degree is
an index showing the regularity of arrangement of island
components. An angle .theta. formed by straight lines connecting
the centers of two neighboring island components (45-(a) (straight
line 1 connecting the centers of two island components) and 45-(b)
(straight line 2 connecting the centers of other two island
components) in FIG. 19) in four island components close to one
another as illustrated in FIG. 19 was defined as the neighboring
island component parallelization degree. Measurement was performed
for 10 or more spots for each of randomly selected 10 or more
multicomponent fibers in multifilaments, and the simple number
average thereof was determined.
F. Sea Polymer Solubility
[0227] This item is intended to evaluate an effect of existence of
a sea component region. The multicomponent fiber obtained under
each of the spinning conditions was woven, and the obtained woven
fabric was immersed for 15 minutes in a sea removal bath filled
with a 3 wt % aqueous sodium hydroxide solution of 80.degree. C.
(bath ratio: 1:100 (woven fabric:solvent)) so that a sea polymer
was removed. The bath ratio herein means the mass ratio of the
sample to the solvent, and the bath ratio of 1:100 means that the
removal treatment is performed using a solvent with a mass that is
100 times as large as the mass of a sample.
[0228] After the sea polymer was removed, water was removed, and
the sample subjected to the removal treatment was dried in a hot
air dryer at 60.degree. C. The mass of the sample was measured at a
temperature of 25.degree. C. and a humidity of 55% RH before and
after the elution treatment, and the weight reduction rate (%) was
calculated in accordance with the equation described below. From
the calculated weight reduction rate, sea polymer solubility of the
multicomponent fiber was evaluated in three ranks as described
below.
Weight reduction rate (%)=(1-weight of sample after elution
treatment/weight of sample before elution treatment).times.100
Evaluation of Sea Polymer Solubility
[0229] Very Good: The weight reduction rate is in the range of the
sea polymer ratio (%).+-.5(%).
[0230] Good: The weight reduction rate is in the range of -5(%) to
-10(%) of the sea polymer ratio (%).
[0231] Poor: The weight reduction rate is not more than -10(%) of
the sea polymer ratio (%).
G. Evaluation of Coming-Off of Ultrafine Fiber (Island Component)
During Sea Removal Treatment
[0232] The multicomponent fiber obtained under each of the spinning
conditions was woven, 10 g of the obtained knitted fabric was
prepared, and 99% or more of the sea polymer was removed in a
removal bath filled with a 3 wt % aqueous sodium hydroxide solution
of 80.degree. C. (bath ratio: 1:100).
[0233] The bath ratio herein means the mass ratio of the sample to
the solvent, and the bath ratio of 1:100 means that the sea removal
treatment is performed using a solvent with a mass that is 100
times as large as the mass of a sample. Removal of the sea
component is evaluated based on the weight reduction rate of the
sample on the premise that the removal rate of the sea component
and the weight reduction rate of the sample (equation described
below) are the same value.
Weight reduction rate (%)=(1-weight of sample after elution
treatment/weight of sample before elution treatment).times.100
[0234] To evaluate the degree of coming-off of the ultrafine fiber,
evaluation was performed as described below.
[0235] A 100 ml portion was sampled from the solution used for the
sea removal treatment, and this solution was passed through glass
fiber filter paper with a retained particle diameter of 0.5 .mu.m.
Based on the difference in dry mass of the filter as measured in an
atmosphere at a temperature of 25.degree. C. and a humidity of 55%
RH between before and after the treatment, the degree of coming-off
of the ultrafine fiber was evaluated in four ranks as described
below.
Evaluation of Coming-Off of Ultrafine Fiber
[0236] Very Good: The mass difference is less than 3 mg.
[0237] Good: The mass difference is not less than 3 mg and less
than 7 mg.
[0238] Fair: The mass difference is not less than 7 mg and less
than 10 mg.
[0239] Bad: The mass difference is not less than 10 mg.
Example 1
[0240] Polyethylene terephthalate (PET, melt viscosity: 120 Pas)
with an intrinsic viscosity (IV) of 0.63 dl/g as an island polymer,
and PET (hereinafter referred to as "copolymer PET 1," melt
viscosity: 140 Pas) with an IV of 0.58 dl/g, which was
copolymerized with 5.0 mol % of 5-sodium sulfoisophthalic acid, as
a sea polymer were separately melted at 290.degree. C., then
weighed, and fed into a spinning pack containing a composite
spinneret 7 of the example as shown in FIG. 2 so that a sea-island
composite polymer flow was melt-discharged. The sea-island
component ratio based on the mass of the fed polymer per unit time
was 50/50. The discharged composite polymer flow was cooled and
solidified, then supplied with an oil, and wound up at a spinning
velocity of 1500 m/min to obtain an as-spun fiber of a 150 dtex-15
filament (single hole through-put rate: 2.25 g/min).
[0241] The wound-up as-spun fiber was drawn at a ratio of 3.0
between rollers heated to 90.degree. C. and 130.degree. C.,
respectively, to form a multicomponent fiber of a 50 dtex-15
filament. In Example 1, a distribution type spinneret as shown in
FIG. 6 was used. In a nozzle plate 2, holes corresponding to the
condition (i) were arranged to form a hexagonal lattice as
illustrated in FIG. 28 so that the hole packing density was 1.5
(holes/mm.sup.2). The radius of a circumscribed circle of a nozzle
hole collection was defined as "radius R". (The "radius R" has the
same meaning hereinafter.)
[0242] In the nozzle plate used in Example 1, sea component region
forming hole groups were arranged from the outer periphery of the
circumscribed circle of the nozzle hole collection to the
circumference with a radius of 0.7R such that four sea component
region forming hole groups were between sea-island discharge hole
groups.
[0243] As shown in Table 1, four sea component regions 44 as
illustrated in FIG. 14 were formed on the cross section of the
obtained multicomponent fiber. The result of the cross-section
observation showed that a multicomponent fiber was obtained as
shown in Table 1. The obtained multicomponent fiber had mechanical
properties acceptable in terms of high-order processability, with
the strength being 2.5 cN/dtex and the elongation being 34%. Sea
polymer solubility was satisfactory (Good). Since the efficiency
during sea removal processing was improved as described above, the
ultrafine fiber had excellent mechanical properties (strength: 2.4
cN/dtex and elongation: 45%) so that the degree of coming-off of
the ultrafine fiber during sea removal was low (evaluation of
coming-off: Good). Spinning conditions and results of evaluation of
the multicomponent fiber and the ultrafine fiber are shown in Table
1.
Example 2
[0244] The same procedure as in Example 1 was carried out except
that a composite spinneret was used which included a nozzle plate
in which as illustrated in FIG. 29, island discharge holes 13 and
sea discharge holes 12 were arranged to form a tetragonal lattice,
the hole packing density was 2.0 (holes/mm.sup.2), and similarly to
Example 1, some of sea-island discharge hole groups between four
sea component region forming hole groups.
[0245] In Example 2, sea component regions were formed on the
composite cross section similarly to Example 1, and thus sea
component solubility was satisfactory (sea component solubility:
Good) so that the degree of coming-off of the ultrafine fiber
during sea removal was low (evaluation of coming-off: Good).
Spinning conditions and results of evaluation of the multicomponent
fiber and the ultrafine fiber are shown in Table 1.
Example 3
[0246] Except that a composite spinneret was used which included a
nozzle plate as illustrated in FIG. 30 in which island discharge
holes 13 were arranged to form a trigonal lattice, sea discharge
holes 12 were arranged, the hole packing density was 3.0
(holes/mm.sup.2), and similarly to Example 1, four sea component
region forming hole groups were arranged to surround some of
sea-island discharge hole groups on both sides, the same procedure
as in Example 1 was carried out to obtain a multicomponent
fiber.
[0247] The cross section of the multicomponent fiber of Example 3
had four sea component regions as illustrated in FIG. 14. In
cross-section observation, these sea component regions extended
toward the center from the upper side, the right side, the lower
side and the left side on the surface of the fiber, but did not
reach the center. The shape thereof was almost rectangular. The
cross-sectional parameter of the multicomponent fiber was as shown
in Table 1, and satisfied the requirement of the multicomponent
fiber. In Example 3, satisfactory sea component solubility
comparable to sea component solubility in Examples 1 and 2 (sea
component solubility: Good) was achieved although the island
packing density was further increased and, further, the degree of
coming-off of the ultrafine fiber during sea removal was also low
(evaluation of coming-off: Good) although the diameter of the
ultrafine fiber was reduced. Spinning conditions and results of
evaluation of the multicomponent fiber and the ultrafine fiber are
shown in Table 1.
Example 4
[0248] Except that a composite spinneret used in Example 4 was a
pipe type spinneret as shown in FIG. 10, and included a nozzle
plate as shown in FIG. 31, and the hole packing density was 1.2
(holes/mm.sup.2), the same procedure as in Example 1 was carried
out to obtain a multicomponent fiber.
[0249] The multicomponent fiber of Example 4 had four sea component
regions formed on the cross section as illustrated in FIG. 14. The
cross-sectional parameter of the multicomponent fiber was as shown
in Table 1, and satisfied the requirement of the multicomponent
fiber. In Example 4, the fiber had satisfactory sea component
solubility (sea polymer solubility: Good), but island components in
the sea-island region were arranged in closest packing, and thus it
took a little longer time to complete sea removal as compared to
Example 1. Therefore, the degree of coming-off of the ultrafine
fiber during sea removal tended to slightly increase, but remained
at an acceptable level (evaluation of coming-off: Fair). Probably
due to this, mechanical properties of the ultrafine fiber were
slightly poorer as compared to Example 1, but remained at a
practically acceptable level (strength 1.8 cN/dtex and elongation:
37%). Spinning conditions and results of evaluation of the
multicomponent fiber and the ultrafine fiber are shown in Table
1.
Example 5
[0250] Except that a composite spinneret was used which included a
nozzle plate in which as shown in FIG. 12, sea component region
forming hole groups were arranged to reach the circumference with a
radius of 0.5R, and the hole packing density was 1.4
(holes/mm.sup.2), the same procedure as in Example 1 was carried
out to obtain a multicomponent fiber.
[0251] The multicomponent fiber of Example 5 had four sea component
regions on the cross section as illustrated in FIG. 14. The
cross-sectional parameter of the multicomponent fiber was as shown
in Table 1, and satisfied the requirement of the multicomponent
fiber. In Example 5, sea component region forming hole groups were
arranged to reach the circumference with a radius of 0.5R and,
therefore, as compared to Example 1, the sea component region
extended to the inner part of the multicomponent fiber so that sea
component solubility was extremely excellent (sea component
solubility: Very Good) although the ratio (H/D) of the
multicomponent fiber diameter D to the sea component region width H
was 0.03, a value comparable to that in Example 1. The sample of
Example 5 was treated for 5 minutes under the same sea removal
treatment conditions as in the evaluation of sea polymer
solubility, an ultrafine fiber bundle of the treated sample was
observed, and the result of the observation showed that the
multicomponent fiber was divided into a plurality of parts due to
formation of cracks in the multicomponent fiber. This effect is
ascribable to improvement of sea component solubility. Since the
treatment time required for completing sea removal was shortened,
coming-off of the ultrafine fiber hardly occurred (evaluation of
coming-off: Very Good), and the ultrafine fiber had excellent
strength characteristics (strength: 2.6 cN/dtex and elongation:
57%). Spinning conditions and results of evaluation of the
multicomponent fiber and the ultrafine fiber are shown in Table
1.
Example 6
[0252] Except that the island polymer ratio was 80%, the same
procedure as in Example 1 was carried out to obtain a
multicomponent fiber.
[0253] The multicomponent fiber of Example 6 had four sea component
regions on the cross section as illustrated in FIG. 14. The
cross-sectional parameter of the multicomponent fiber was as shown
in Table 1, and satisfied the requirement of the multicomponent
fiber. In Example 6, the mechanical properties of the
multicomponent fiber were significantly improved (strength: 3.3
cN/dtex and elongation: 31%) as compared to Example 1 by increasing
the island polymer ratio. In Example 6, fiber breakage did not
occur during a Spinning step such as spinning and drawing, and a
step of processing the fiber into a fabric, and thus excellent
quality was achieved. Although the island polymer ratio was
increased to 80%, sea polymer solubility was satisfactory (sea
polymer solubility: Good) owing to the effect of the sea component
region as a feature. Besides such satisfactory sea polymer
solubility, the fiber structure of the island component was highly
formed in the Spinning step so that coming-off of the ultrafine
fiber during sea removal did not occur (evaluation of coming-off:
Very Good), and the ultrafine fiber had excellent mechanical
properties (strength: 3.1 cN/dtex and elongation: 40%). Spinning
conditions and results of evaluation of the multicomponent fiber
and the ultrafine fiber are shown in Table 1.
Example 7
[0254] Except that the island polymer ratio was 20%, the same
procedure as in Example 1 was carried out to obtain a
multicomponent fiber.
[0255] The multicomponent fiber of Example 7 had four sea component
regions on the cross section as illustrated in FIG. 14. The
cross-sectional parameter of the multicomponent fiber was as shown
in Table 1, and satisfied our requirement of the multicomponent
fiber. In Example 7, the island polymer ratio was reduced, and thus
the ratio (H/D) of the multicomponent fiber diameter D to the sea
component region width H increased to 0.25 so that sea component
solubility was extremely excellent (sea component solubility: Very
Good). Similarly to Example 5, the sample was treated for 5 minutes
under the same elution treatment conditions as in the evaluation of
sea component solubility, an ultrafine fiber bundle of the treated
sample was observed, and the result of the observation showed that
the multicomponent fiber was already divided into a plurality of
parts, and ultrafine fibers were already generated at many parts.
On the other hand, probably due to insufficient formation of the
fiber structure of the island component because the island polymer
ratio was set a low value in the ultrafine fiber, the degree of
coming-off of the ultrafine fiber slightly increased as compared to
Example 1, but remained at a practically acceptable level
(evaluation of coming-off: Fair). Spinning conditions and results
of evaluation of the multicomponent fiber and the ultrafine fiber
are shown in Table 1.
Comparative Example 1
[0256] Except that a composite spinneret was used which included a
nozzle plate in which island discharge holes and sea discharge
holes were arranged to form a hexagonal lattice similarly to
Example 1, and a sea component region forming hole group was not
arranged, the same procedure as in Example 1 was carried out to
obtain a multicomponent fiber.
[0257] In the multicomponent fiber of Comparative Example 1, the
cross section thereof was not provided with a sea component region
as a feature because a sea component region forming hole group was
not arranged, and thus the same sea-island multicomponent fiber as
conventional one as illustrated in FIG. 27 was obtained.
[0258] In Comparative Example 1, mechanical properties were almost
comparable to those in Example 1 (strength: 2.3 cN/dtex and
elongation: 32%), but since elution of the sea polymer gradually
proceeded from the outermost layer of the multicomponent fiber, sea
component solubility was considerably reduced (sea component
solubility: Poor). Similarly to Example 5, the sample of
Comparative Example 1 was treated for 5 minutes under the same
elution treatment conditions as in the evaluation of sea component
solubility, an ultrafine fiber bundle of the treated sample was
observed, and the result of the observation showed that only the
sea component on the surface layer of the multicomponent fiber was
removed, and sea removal hardly proceeded. Accordingly, for the
sample of Comparative Example 1, it was required to considerably
extend the time to complete sea removal, and resultantly island
components arranged in the vicinity of the outermost layer of the
multicomponent fiber were also treated with a solvent so that
coming-off of the ultrafine fiber frequently occurred (evaluation
of coming-off: Bad). Therefore, the ultrafine fiber had much lower
mechanical properties (strength: 1.8 cN/dtex and elongation: 16%)
as compared to Example 1, and observation of the resulting
ultrafine fiber bundle showed small pieces of fuzzed ultrafine
fiber, and thus the ultrafine fiber was not satisfactory in
quality. Spinning conditions and results of evaluation of the
multicomponent fiber and the ultrafine fiber are shown in Table
1.
TABLE-US-00001 TABLE 1 Compar- ative Exam- Exam- Exam- Exam- Exam-
Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 ple 1
Spinning Sea component PET PET PET PET PET PET PET PET conditions
Island component Coplymer Coplymer Coplymer Coplymer Coplymer
Coplymer Coplymer Coplymer PET1 PET1 PET1 PET1 PET1 PET1 PET1 PET1
Ratio of sea [%] 50 50 50 50 50 20 80 50 Ratio of island [%] 50 50
50 50 50 80 20 50 n-gonal lattice 6 4 3 -- 6 6 6 6 Hole packing
density [Holes/mm.sup.2] 1.5 2.0 3.0 1.2 1.4 1.5 1.5 1.5 Spinning
velocity [m/min] 1500 1500 1500 1500 1500 1500 1500 1500 Stretch
ratio [--] 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Result of Existence of
sea Yes Yes Yes Yes Yes Yes Yes No cross-section component region
observation D: Diameter of [.mu.m] 68 68 68 68 68 68 68 68 of
multi- multicomponent fiber component d: Maximum diameter [nm] 784
679 555 877 812 992 496 784 fiber of island compone W: Maximam
distance [nm] 90 70 50 120 100 30 190 100 of neighboring isla L/D
[--] 0.15 0.15 0.15 0.15 0.25 0.15 0.15 -- H/D [--] 0.03 0.025 0.01
0.015 0.03 0.001 0.25 -- As/Ac [--] 0.023 0.019 0.008 0.011 0.038
0.000 0.191 -- .theta.: Neighboring [.degree.] 2 3 1 22 0 2 5 1
island component parallelization degree Property of Fineness [dtex]
50 50 50 50 50 50 50 50 multi- Strength [cN/dtex] 2.5 2.4 2.2 1.9
2.7 3.3 2.0 1.9 component Elongation [%] 34 31 35 28 43 30 21 32
fiber Sea polymer solubility [--] Good Good Good Good Very Good
Very Poor Good Good Evaluated coming-off [--] Good Good Good Fair
Very Very Fair Bad Good Good Ultrafine Fineness [dtex] 25 25 25 25
25 40 10 25 fiber Strength [cN/dtex] 2.4 2.3 2.1 1.8 2.6 3.1 1.9
1.8 Elongation [%] 45 41 46 37 57 40 27 16 indicates data missing
or illegible when filed
Comparative Example 2
[0259] Except that a composite spinneret was used which included a
nozzle plate in which island discharge holes and sea discharge
holes were arranged to form a hexagonal lattice similarly to
Example 1, a sea component region forming hole group was not
arranged, and the hole packing density was 3.0 (holes/mm.sup.2),
and the island polymer ratio was 80%, the same procedure as in
Example 1 was carried out to obtain a multicomponent fiber.
[0260] In the multicomponent fiber of Comparative Example 2, the
cross section thereof was not provided with a sea component region
as a feature because a sea component region forming hole group was
not arranged, and the number of islands increased by a factor of 2
as compared to Comparative Example 1 so that the multicomponent
fiber had a cross-section structure in which the whole cross
section thereof was closely packed with the island component.
[0261] In Comparative Example 2, the multicomponent fiber had
relatively satisfactory mechanical properties (strength: 3.3
cN/dtex and elongation: 33%), but the fiber had a structure in
which the island component was densely arranged so that elution of
the sea polymer was extremely hard to proceed, leading to extremely
low sea component solubility (sea component solubility: Poor).
Similarly to Example 5, the sample of Comparative Example 2 was
treated for 5 minutes under the same elution treatment conditions
as in the evaluation of sea component solubility, a fiber bundle of
the sample was observed, and the result of the observation showed
that elution of the sea polymer hardly proceeded, and the state of
the multicomponent fiber was almost unchanged from the state before
the treatment. Since ultrafine fibers were in part generated in
Comparative Example 1, the sea component solubility of the sample
of Comparative Example 2 was further reduced as compared to
Comparative Example 1.
[0262] Accordingly, for the sample of Comparative Example 2, only a
multicomponent fiber with a sea polymer remaining therein was
obtained although the sea removal time was extended, and thus the
treatment with an aqueous sodium hydroxide solution was stopped 2
hours after the start of the treatment. Coming-off of the ultrafine
fiber was examined, and the result of the examination showed that
coming-off frequently occurred (evaluation of coming-off: Bad). The
mechanical properties of the sample treated for 2 hours were
examined for reference, and the result of the examination showed
that the sample had very low mechanical properties and was not
satisfactory in quality. Spinning conditions and results of
evaluation of the multicomponent fiber and the ultrafine fiber are
shown in Table 2.
Comparative Example 3
[0263] Except that a pipe type spinneret as illustrated in FIG. 10
was used which included a nozzle plate in which a sea component
region forming hole group was not arranged, the same procedure as
in Example 1 was carried out to obtain a multicomponent fiber.
[0264] The multicomponent fiber of Comparative Example 3 was not
provided with a sea component region as a feature similarly to
Comparative Example 1, had the island component arranged
concentrically from the center of the multicomponent fiber as
compared to Example 1, and had a neighboring island component
parallelization degree .theta. of 25.degree..
[0265] The multicomponent fiber of Comparative Example 3 had no
particular problem in the spinning step, but suffered frequent
thread breakage in the drawing step. On the other hand, the
mechanical properties of the multicomponent fiber, although varied,
were satisfactory (strength: 2.5 cN/dtex and elongation: 38%), and
due to a large inter-island component distance, sea component
solubility was acceptable (sea component solubility: Good).
However, as described above, since the quality of the
multicomponent fiber was not satisfactory, and also the arrangement
of the island component was not a regular arrangement as in our
fibers, there was a limit on enhancement of the fiber structure of
the island component, and coming-off of the ultrafine fiber
frequently occurred at the time when sea removal was completed
(evaluation of coming-off: Bad). Therefore, the ultrafine fiber had
much lower mechanical properties (strength: 1.5 cN/dtex and
elongation: 13%) as compared to Example 1, and was poor in quality.
Spinning conditions and results of evaluation of the multicomponent
fiber and the ultrafine fiber are shown in Table 2.
Comparative Example 4
[0266] Except that the same pipe type spinneret as that in
Comparative Example 3, which included a nozzle plate in which a sea
component region forming hole group was not arranged, was used, and
the island polymer ratio was 70%, the same procedure as in Example
1 was carried out to obtain a multicomponent fiber. In Comparative
Example 4, spinning was performed with the island polymer ratio set
to 80%, but island components were fused together to collapse the
composite cross section and, therefore, spinning was performed with
the island polymer ratio reduced to 70%.
[0267] The multicomponent fiber of Comparative Example 4 was not
provided with a sea component region as a feature similarly to
Comparative Example 3, and had the island component densely
arranged on the cross section of the multicomponent fiber because
the island polymer ratio was increased as compared to Comparative
Example 3. The neighboring island component parallelization degree
.theta. was 17.degree..
[0268] The mechanical properties of the multicomponent fiber of
Comparative Example 4, although varied similarly to Comparative
Example 3, were relatively satisfactory (strength: 2.8 cN/dtex and
elongation: 31%), but since the island component was densely
arranged, the sea removal did not efficiently proceed, and even as
compared to Example 6 where the island polymer ratio was higher by
10%, sea component solubility was reduced (sea component
solubility: Poor). Therefore, in the multicomponent fiber of
Comparative Example 4, the time required for the sea removal
treatment was twice or more as long as that in Example 6, and
coming-off of the ultrafine fiber frequently occurred (evaluation
of coming-off: Bad). Therefore, the ultrafine fiber had reduced
quality with the fiber having fuzzes and also had much lower
mechanical properties (strength: 1.7 cN/dtex and elongation: 18%)
as compared to Example 6. The results are shown in Table 2.
Comparative Example 5
[0269] A composite spinneret was used which included a nozzle plate
11 in which island component pipe groups were arranged to form an
equilateral-triangular lattice, and as illustrated in FIG. 17,
composite polymer discharge holes 15 existed, and sea polymer
admission channels (having no discharge holes) were provided, the
composite spinneret being the same pipe type spinneret as that in
Comparative Example 3 in which a sea component region forming hole
group was not arranged. Further, the island polymer ratio was 80%.
This condition was based on the method disclosed in Japanese Patent
Laid-open Publication No. 2009-91680. Except that the
above-described condition was employed, the same procedure as in
Example 1 was carried out to obtain a multicomponent fiber.
[0270] In Comparative Example 5, spinning was performed with the
island polymer ratio set to 80%, but fusing of island components
was suppressed so that a sea-island composite cross section was
successfully formed.
[0271] However, in Comparative Example 5, a sea component region
forming hole group as we use is not provided. Therefore, a sea
component region as a feature was not formed, and the island
component was densely formed over the entire region of the
composite cross section. The neighboring island component
parallelization degree .theta. was 23.degree..
[0272] However, in the multicomponent fiber of Comparative Example
5, the sea removal did not proceed probably because the island
component was densely arranged, and sea polymer solubility was much
lower as compared to Example 6 (sea polymer solubility: Poor).
Therefore, in Comparative Example 5, similarly to Comparative
Example 4, the time required for the sea removal treatment was
twice or more as long as that in Example 6, and coming-off of the
ultrafine fiber frequently occurred. In observation of the sample
after sea removal, a sea polymer portion partially existed at the
central part of the multicomponent fiber, and thus removal sea was
not completed in some parts. The ultrafine fiber bundle of
Comparative Example 5 had a poor texture with the fiber having
fuzzes In Comparative Example 5, mechanical properties were also
much lower as compared to Example 6 (strength: 1.9 cN/dtex and
elongation: 12%). Spinning conditions and results of evaluation of
the multicomponent fiber and the ultrafine fiber are shown in Table
2.
TABLE-US-00002 TABLE 2 Comparative Comparative Comparative
Comparative Example 2 Example 3 Example 4 Example 5 Spinning Sea
component PET PET PET PET conditions Island component Coplymer
Coplymer Coplymer Coplymer PET1 PET1 PET1 PET1 Ratio of sea [%] 20
50 30 20 Ratio of island [%] 80 50 70 80 n-gonal lattice 6 -- -- --
Hole packing density [Holes/mm.sup.2] 3.0 1.5 1.5 1.5 Spinning
velocity [m/min] 1500 1500 1500 1500 Stretch ratio [--] 3.0 3.0 3.0
3.0 Result of Existence of sea No No No No cross-section component
region observation D: Diameter of [.mu.m] 68 68 68 68 of multi-
multicomponent fiber component d: Maximum diameter [nm] 701 784 928
928 of island components fiber W: Maximam distance [nm] 20 100 50
20 of neighboring islands L/D [--] -- -- -- -- H/D [--] -- -- -- --
As/Ac [--] -- -- -- -- .theta.: Neighboring [.degree.] 0 25 17 23
island component parallelization degree Property of Fineness [dtex]
50 50 50 50 multi- Strength [cN/dtex] 3.6 2.5 2.8 3.3 component
Elongation [%] 33 38 31 35 fiber Sea polymer solubility [--] Poor
Good Poor Poor Evaluated coming-off [--] Bad Bad Bad Bad Ultrafine
Fineness [dtex] 40 25 35 35 fiber Strength [cN/dtex] 1.1 1.5 1.7
1.9 Elongation [%] 13 13 18 12
Examples 8 to 10
[0273] A composite spinneret was used which included a nozzle plate
in which the number of holes in the sea component region forming
hole group in the nozzle plate illustrated in FIG. 28 and used in
Example 6 was increased by a factor of 3 (Example 8), by a factor
of 10 (Example 9) and by a factor of 40 (Example 10) in the shaded
regions in FIG. 28 to change the sea component region width H.
Further, the island polymer ratio was changed as shown in Table 3
to adjust the inter-island component distance. Except that the
above-described changes were made, the same procedure as in Example
6 was carried out to obtain a multicomponent fiber.
[0274] In each of the multicomponent fibers of Examples 8 to 10,
four sea component regions were formed as illustrated in FIG. 14,
but since the number of holes in the sea component region forming
hole group was changed, the sea component region width H increased
as compared to Example 6.
[0275] In each of the examples, the multicomponent fiber had
excellent mechanical properties with the strength being 3.2 cN/dtex
or more and the elongation being 29% or more. In not only the
Spinning step but also woven fabric processing to evaluate sea
component solubility, thread breakage and fuzzing did not occur,
and thus the fabric had excellent quality.
[0276] As compared to Example 6, sea component solubility tended to
be improved as the size of the sea component region increased, and
particularly in Examples 9 and 10, the multicomponent fiber had
extremely excellent performance, and similarly to Example 5,
ultrafine fibers were already generated in a sample obtained
through the treatment performed for 5 minutes.
[0277] Therefore, in the multicomponent fiber of each of Examples 8
to 10, the time required for completely removing the sea polymer
was reduced. Therefore, the degree of coming-off of the ultrafine
fiber was low (evaluation of coming-off: Very Good), and the
ultrafine fiber had excellent mechanical properties. The results
are shown in Table 3.
Examples 11 and 12
[0278] A composite spinneret was used which included, in place of
the nozzle plate used in Example 5, a nozzle plate provided with
eight sea component region forming hole groups which extended
inward from the outer layer and which were absent at the center.
The island polymer ratio was 70%. Except that the above-described
changes were made, the same procedure as in Example 5 was carried
out to obtain a multicomponent fiber (Example 11).
[0279] In Example 12, spinning was carried out at a stretch ratio
of 1.7 under the same spinning conditions as in Example 11 except
that the spinning velocity was changed to 3000 m/min.
[0280] In each of Examples 11 and 12, eight sea component regions
were formed as illustrated in FIG. 20. From comparison with the
cross section in Example 5, it was confirmed that a composite cross
section was formed in which the number of sea component regions was
increased from 4 to 8 while the size of the sea component region
was comparable (L/D: 0.25 and H/D: 0.03). In each of Examples 11
and 12, there was no problem in the Spinning step, and particularly
in Example 12, thread breakage was not noticeable although the
spinning velocity was increased by a factor of 2 to 3000 m/min.
[0281] For the samples of Examples 11 and 12, sea component
solubility was satisfactory (sea component solubility: Good) due to
an increase in the number of sea component regions, and ultrafine
fibers generated from the multicomponent fibers had excellent
mechanical properties. The results are shown in Table 3.
Examples 13 and 14
[0282] In place of the spinneret used in Example 1, a composite
spinneret was used which included a nozzle plate in which sea
component region forming hole groups were arranged to extend across
the nozzle hole collection while orthogonally crossing each other
as shown in FIG. 5. Except that the above-described change was
made, the same procedure as in Example 11 was carried out to obtain
a multicomponent fiber (Example 13). In Example 14, spinning was
carried out at a stretch ratio of 1.7 under the same spinning
conditions as in Example 13 except that the spinning velocity was
changed to 3000 m/min.
[0283] In each of Examples 13 and 14, sea component regions were
formed to extend across the cross section of the multicomponent
fiber and orthogonally cross each other at the center of the
multicomponent fiber as shown in FIG. 13 (L/D: 1.00). In Examples
13 and 14, the area ratio of the sea component region increased at
the multicomponent fiber cross section with the ratio As/Ac being
0.153 while the sea component region width (H/D: 0.03) was
comparable to that in Example 11, and sea component solubility of
the multicomponent fiber was further improved as compared to
Example 11 (sea component solubility: Very Good).
[0284] In the multicomponent fibers of Examples 13 and 14, the
multicomponent fiber was observed to be divided into a plurality of
parts for samples treated with an aqueous sodium hydroxide solution
for 5 minutes similarly to Example 5. In these multicomponent
fibers, cracks were formed on sea component regions arranged to
extend across the cross section of the fiber. Therefore, the
multicomponent fiber was divided into a plurality of parts in the
initial stage of sea removal in the sea removal treatment. Owing to
this effect, the treatment time to complete sea removal was reduced
although the multicomponent fiber had a relatively high island
polymer ratio of 70% in the multicomponent fibers of Examples 13
and 14. Accordingly, coming-off of the ultrafine fiber was hardly
observed (evaluation of coming-off: Very Good). The results are
shown in Table 3.
Example 15
[0285] In place of the nozzle plate used in Example 13, a nozzle
plate was provided in which sea component region forming hole
groups continuously arranged to extend across the nozzle hole
collection 18 were added and evenly arranged as shown in FIG. 32.
Except that a composite spinneret was used which included a nozzle
plate as illustrated in FIG. 32, the same procedure as in Example
13 was carried out to spin a multicomponent fiber. In Example 15,
four sea component regions were arranged at intervals of 45.degree.
to extend across the cross section of the multicomponent fiber as
shown in FIG. 21 (H/D: 0.03 and L/D: 1.00).
[0286] In Example 15, sea component regions extended through the
cross section of the fiber to further divide the sea-island region
so that in the initial stage of sea removal, the multicomponent
fiber was easily divided into a plurality of parts, leading to an
increase in apparent surface area exposed to an aqueous sodium
hydroxide solution, and thus the multicomponent fiber had more
satisfactory sea component solubility as compared to Example 13
(sea component solubility: Very Good). As a result, the time
required to complete sea removal was reduced as compared to
comparative examples, and coming-off of the ultrafine fiber hardly
occurred (evaluation of coming-off: Very Good). The results are
shown in Table 3.
TABLE-US-00003 TABLE 3 Exam- Exam- Exam- Exam- Exam- Exam- Exam-
Exam- ple 8 ple 9 ple 10 ple 11 ple 12 ple 13 ple 14 ple 15
Spinning Sea component PET PET PET PET PET PET PET PET conditions
Island component Coplymer Coplymer Coplymer Coplymer Coplymer
Coplymer Coplymer Coplymer PET1 PET1 PET1 PET1 PET1 PET1 PET1 PET1
Ratio of sea [%] 20 25 30 30 30 30 30 30 Ratio of island [%] 80 75
70 70 70 70 70 70 n-gonal lattice 6 6 6 6 6 6 6 6 Hole packing
density [Holes/mm.sup.2] 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Spinning
velocity [m/min] 1500 1500 1500 1500 3000 1500 3000 1500 Stretch
ratio [--] 3.0 3.0 3.0 3.0 1.7 3.0 1.7 3.0 Result of Existence of
sea Yes Yes Yes Yes Yes Yes Yes Yes cross-section component region
observation D: Diameter of [.mu.m] 68 68 68 68 64 68 64 68 of
multi- multicomponent fiber component d: Maximum diameter [nm] 992
961 928 928 872 928 872 928 fiber of island compon W: Maximam
distance [nm] 30 30 20 40 40 20 20 30 of neighboring is L/D [--]
0.15 0.15 0.15 0.25 0.25 1.00 1.00 1.00 H/D [--] 0.050 0.100 0.200
0.030 0.030 0.030 0.030 0.010 As/Ac [--] 0.038 0.076 0.153 0.076
0.076 0.153 0.153 0.102 .theta.: Neighboring [.degree.] 0 1 4 0 1 0
0 2 island component parallelization degree Property of Fineness
[dtex] 50 50 50 50 44 50 44 50 multi- Strength [cN/dtex] 3.4 3.3
3.2 3.4 2.6 3.2 2.9 2.9 component Elongation [%] 29 29 33 33 22 29
31 37 fiber Sea polymer solubility [--] Good Very Very Good Good
Very Very Very Good Good Good Good Good Evaluated coming-off [--]
Very Very Very Very Good Very Very Very Good Good Good Good Good
Good Good Ultrafine Fineness [dtex] 40 38 35 35 31 35 31 35 fiber
Strength [cN/dtex] 3.2 3.1 3.0 3.2 2.5 3.0 2.8 2.8 Elongation [%]
38 38 43 44 29 38 41 49 indicates data missing or illegible when
filed
Examples 17 and 18
[0287] A nozzle plate was provided in which as shown in FIG. 33,
island discharge holes 13 and sea discharge holes 12 were arranged
to form a tetragonal lattice, and the sea component region forming
hole group was arranged over a range of 0.5R from the center of the
nozzle hole collection 18 toward the outer layer (hole packing
density: 1.5 holes/mm.sup.2). Except that a composite spinneret
including this nozzle plate was used, and the sea polymer was PET
copolymerized with 8.0 mol % of 5-sodium sulfoisophthalic acid with
an IV of 0.50 dl/g (copolymer PET 2, melt viscosity: 120 Pas), the
same procedure as in Example 6 was carried out to obtain a
multicomponent fiber (Example 17).
[0288] Except that a nozzle plate 2 was used in which the hole
packing density of the spinneret used in Example 17 was changed to
0.3 holes/mm.sup.2, the same procedure as in Example 11 was carried
out to perform spinning in Example 18. In each of Examples 17 and
18, sea component regions were formed to extend in eight directions
from the center of the multicomponent fiber as shown in FIG. 22.
Since the hole packing density was changed, the ratios H/D and
As/Ac of the multicomponent fiber were changed as shown in Table 4
while the ratio L/D was 0.50. The multicomponent fiber of each of
Examples 17 and 18 had cracks formed on the cross section thereof
through the removal treatment performed for 5 minutes in the same
manner as in Example 5 so that an aqueous sodium hydroxide solution
infiltrated into the inner part of the multicomponent fiber in the
initial stage of the sea removal treatment although the sea
component region did not reach the outermost layer of the
multicomponent fiber. Therefore, the multicomponent fiber of
Example 18 had excellent sea component solubility (sea component
solubility: Very Good) because the sea component region was widely
formed, and the multicomponent fiber of Example 17 also had
satisfactory sea component solubility (sea component solubility:
Good) owing to the effect of crack formation as described above.
The results are shown in Table 4.
Example 19
[0289] A nozzle plate was used in which removing sea discharge hole
groups were arranged such that sea component regions were formed in
a trapezoidal shape at the center of the multicomponent fiber as
shown in FIG. 34, and the hole packing density was 0.3
holes/mm.sup.2. The removing sea discharge hole groups were
continuously arranged over a range of 0.4R from the center of the
nozzle hole collection 18, with the sea component regions formed
horizontally symmetrically in the multicomponent fiber. Except that
a composite spinneret was used which included a nozzle plate as
illustrated in FIG. 34, the same procedure as in Example 17 was
carried out to obtain a multicomponent fiber.
[0290] In the multicomponent fiber of Example 19, trapezoidal sea
component regions continuously extending in the circumferential
direction (120.degree.) as shown in FIG. 23 were formed on the
cross section of the fiber depending on the arrangement of sea
component region forming hole groups. In Example 19, the sea
component region did not reach the outermost layer of the
multicomponent fiber similarly to Example 18, but from observation
of a sample similar to that of Example 5, which was subjected to a
short-time sea removal treatment (5 minutes), it was found that
cracks were formed on the cross section of the multicomponent fiber
in the initial stage of sea removal. Therefore, sea component
solubility was satisfactory (sea component solubility: Good), and
the sea removal time was reduced so that coming-off of the
ultrafine fiber at the time when sea removal was completed was
suppressed (evaluation of coming-off: Good). The results are shown
in Table 4.
Examples 20 and 21
[0291] Except that a composite spinneret was used which included a
nozzle plate in which the range over which the removing sea
discharge hole group in the nozzle plate illustrated in FIG. 34 was
continuously extended to 0.5R from the center of the nozzle hole
collection 18 to expand the sea component region formed at the
center of the multicomponent fiber in view of the results of
Example 19, the same procedure as in Example 19 was carried out to
obtain a multicomponent fiber. In Example 21, spinning was carried
out at a stretch ratio of 1.5 under the same spinning conditions as
in Example 20 except that the spinning velocity was changed to 3000
m/min.
[0292] In the multicomponent fibers of Examples 20 and 21, due to
expansion of the range over which the removing sea discharge hole
group was arranged, the sea component region formed in the
multicomponent fiber was expanded in comparison with Example 19 as
illustrated in FIG. 24. In Example 20, due to expansion of the sea
component region formed in the multicomponent fiber, crack
formation and infiltration of an aqueous sodium hydroxide solution
in the initial stage of sea removal were facilitated as compared to
Example 19 so that the multicomponent fiber had excellent sea
component solubility (sea component solubility: Very Good), and the
treatment time required for completing sea removal was reduced so
that coming-off of the ultrafine fiber was not observed (evaluation
of coming-off: Very Good).
[0293] Therefore, the ultrafine fiber after sea removal had
excellent mechanical properties, and the resulting ultrafine fiber
bundle was free from fibrillation, and thus had excellent quality.
In Example 21, thread breakage did not occur in the spinning step
and the drawing step although the spinning velocity was increased,
and thus the multicomponent fiber had satisfactory Spinning
performance. In addition, cracks were formed in the multicomponent
fiber in the initial stage of the sea removal treatment similarly
to Example 19, and thus the multicomponent fiber was confirmed to
have satisfactory sea component solubility (sea component
solubility: Good).
Example 22
[0294] Except that a composite spinneret was used which included a
nozzle plate in which removing sea discharge hole groups were
arranged such that sea component regions orthogonally crossed one
another at equal intervals on the cross section of the
multicomponent fiber as illustrated in FIG. 35, the same procedure
as in Example 11 was carried out to obtain a multicomponent
fiber.
[0295] On the cross section of the multicomponent fiber of Example
22, sea component regions were formed at equal intervals while
being between a sea-island region as illustrated in FIG. 26.
[0296] In Example 22, a plurality of cracks were apparently formed
on the composite cross section in a short-time-treated sample
similar to that of Example 5, and the sea-island region was divided
into a plurality of parts. Owing to the effect of dividing the
multicomponent fiber into a plurality of parts in the initial stage
of the sea removal treatment, the specific surface area of the sea
polymer exposed to an aqueous sodium hydroxide solution increased
so that the multicomponent fiber had extremely excellent sea
component solubility (sea component solubility: Very Good). Due to
the above-mentioned effect, the treatment time taken for the sea
polymer to be completely removed can be considerably reduced,
coming-off of the ultrafine fiber hardly occurred during sea
removal (evaluation of coming-off: Very Good), and the ultrafine
fiber was free from fuzzes, and had excellent mechanical
properties. The results are shown in Table 4.
Example 23
[0297] Except that a composite spinneret was used which included a
nozzle plate in which removing sea discharge hole groups were
arranged such that sea component regions were formed in a trigonal
shape at the center of the multicomponent fiber as illustrated in
FIG. 36, and the hole packing density was 0.3 holes/mm.sup.2, the
same procedure as in Example 19 was carried out to obtain a
multicomponent fiber.
[0298] In the multicomponent fiber of Example 23, trigonal sea
component regions as shown in FIG. 25 were formed on the cross
section of the fiber depending on the arrangement of sea component
region forming hole groups. In Example 23, the sea component region
did not reach the outermost layer of the multicomponent fiber
similarly to Example 19, but from observation of a sample similar
to that of Example 5, which was subjected to a short-time sea
removal treatment (5 minutes), we found that cracks were formed on
the cross section of the multicomponent fiber in the initial stage
of sea removal. Therefore, sea component solubility of the sample
was satisfactory (sea component solubility: Very Good), and the sea
removal time was reduced so that coming-off of the ultrafine fiber
at the time when sea removal was completed was suppressed
(evaluation of coming-off: Very Good). The results are shown in
Table 4.
TABLE-US-00004 TABLE 4 Exam- Exam- Exam- Exam- Exam- Exam- Exam-
ple 17 ple 18 ple 19 ple 20 ple 21 ple 22 ple 23 Spinning Sea
component PET PET PET PET PET PET PET conditions Island component
Coplymer Coplymer Coplymer Coplymer Coplymer Coplymer Coplymer PET2
PET2 PET2 PET2 PET2 PET1 PET2 Ratio of sea [%] 20 20 20 20 20 20 20
Ratio of island [%] 80 80 80 80 80 80 80 n-gonal lattice 4 4 4 4 4
4 4 Hole packing density [Holes/mm.sup.2] 1.5 0.3 0.3 0.3 0.3 1.5
0.3 Spinning velocity [m/min] 1500 1500 1500 1500 3000 1500 1500
Stretch ratio [--] 3.2 3.2 3.2 3.2 1.5 3.0 3.2 Result of Existence
of sea Yes Yes Yes Yes Yes Yes Yes cross-section component region
observation D: Diameter of [.mu.m] 66 66 66 66 68 68 68 of multi-
multicomponent fiber component d: Maximum diameter [nm] 961 2148
2148 2148 2218 992 2148 fiber of island component W: Maximam
distance [nm] 30 110 130 30 30 30 130 of neighboring islan L/D [--]
0.50 0.50 0.10 0.13 0.13 0.83 0.25 H/D [--] 0.005 0.010 0.030 0.038
0.038 0.005 0.050 As/Ac [--] 0.025 0.051 0.027 0.167 0.167 0.021
0.125 .theta.: Neighboring [.degree.] 3 0 4 5 4 2 3 island
component parallelization degree Property of Fineness [dtex] 47 47
47 47 50 50 50 multi- Strength [cN/dtex] 4.2 3.8 3.7 4.2 3.4 3.7
3.0 component Elongation [%] 24 29 33 25 25 33 29 fiber Sea polymer
solubility [--] Good Very Good Good Very Good Good Very Good Very
Good Evaluated coming-off [--] Very Good Very Good Good Very Good
Good Very Good Very Good Ultrafine Fineness [dtex] 38 38 38 38 40
40 40 fiber Strength [cN/dtex] 4.0 3.6 3.5 4.0 3.2 3.5 3.2
Elongation [%] 31 38 43 33 33 43 38 indicates data missing or
illegible when filed
* * * * *