U.S. patent application number 17/429623 was filed with the patent office on 2022-01-20 for drawn composite fiber, non-woven fabric, and method of producing drawn composite fiber.
The applicant listed for this patent is UBE EXSYMO CO., LTD.. Invention is credited to Satoshi KUSAKA, Kotaro TOMITA.
Application Number | 20220018044 17/429623 |
Document ID | / |
Family ID | |
Filed Date | 2022-01-20 |
United States Patent
Application |
20220018044 |
Kind Code |
A1 |
KUSAKA; Satoshi ; et
al. |
January 20, 2022 |
DRAWN COMPOSITE FIBER, NON-WOVEN FABRIC, AND METHOD OF PRODUCING
DRAWN COMPOSITE FIBER
Abstract
Embodiments relate to a drawn composite fiber having a low
thermal shrinkage, and a high single yarn strength, a non-woven
fabric using the same, and a method of producing the same. The
drawn composite fiber has a fineness of 0.6 dtex or less, a ratio
between the cross-sectional areas of a sheath material and a core
material (sheath material/core material) of 50/50 to 10/90, and a
single yarn elastic modulus of 70 cN/dtex or more. The drawn
composite is obtained by melt-spinning and a drawing treatment of
an undrawn fiber having a sheath-core structure, in which the core
material includes a resin containing a crystalline propylene-based
polymer and having a melt flow rate of 10 to 30 g/10 min at a load
of 21.18 N at 230.degree. C., and the sheath material includes a
resin containing an olefinic polymer where the melting point is
lower than that of the core material.
Inventors: |
KUSAKA; Satoshi; (Tokyo,
JP) ; TOMITA; Kotaro; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UBE EXSYMO CO., LTD. |
Tokyo |
|
JP |
|
|
Appl. No.: |
17/429623 |
Filed: |
March 18, 2020 |
PCT Filed: |
March 18, 2020 |
PCT NO: |
PCT/JP2020/011925 |
371 Date: |
August 9, 2021 |
International
Class: |
D01F 8/06 20060101
D01F008/06; D01D 5/34 20060101 D01D005/34; D01D 5/08 20060101
D01D005/08; D01D 5/16 20060101 D01D005/16; D04H 1/541 20060101
D04H001/541 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2019 |
JP |
2019-068001 |
Claims
1. A drawn composite fiber comprising a sheath-core structure in
which a resin containing a crystalline propylene-based polymer as a
main component is a core material, and a resin containing, as a
main component, an olefinic polymer of which a melting point is
lower than that of the core material is a sheath material, wherein
the drawn composite fiber has a fineness of 0.6 dtex or less, a
melt flow rate of the core material at a load of 21.18 N at
230.degree. C. is 10 to 30 g/10 min, a ratio between
cross-sectional areas of the sheath material and the core material
(sheath material/core material) is 50/50 to 10/90, and the drawn
composite fiber has a single yarn elastic modulus of 70 cN/dtex or
more.
2. The drawn composite fiber according to claim 1, wherein a ratio
between a melt flow rate of the core material at a load of 21.18 N
at 230.degree. C. and a melt flow rate of the sheath material at a
load of 21.18 N at 230.degree. C. (core material/sheath material)
is 0.3 to 1.
3. A non-woven fabric formed using the drawn composite fiber
according to claim 1.
4. A method of producing a drawn composite fiber, comprising: a
spinning step of obtaining, by melt-spinning, an undrawn fiber
including a sheath-core structure in which a resin containing a
crystalline propylene-based polymer as a main component is a core
material, and a resin containing, as a main component, an olefinic
polymer of which a melting point is lower than that of the core
material is a sheath material; and a drawing step of obtaining a
drawn composite fiber of 0.6 dtex or less by drawing treatment of
the undrawn fiber, wherein the undrawn fiber has a fineness of 4.0
dtex or less, and has a ratio between cross-sectional areas of the
sheath material and the core material (sheath material/core
material) of 50/50 to 10/90, the core material has a melt flow rate
of 10 to 30 g/10 min at a load of 21.18 N at 230.degree. C., and
the spinning step and the drawing step are consecutively
performed.
5. The method of producing a drawn composite fiber according to
claim 4, wherein a ratio between a melt flow rate of the core
material at a load of 21.18 N at 230.degree. C. and a melt flow
rate of the sheath material at a load of 21.18 N at 230.degree. C.
(core material/sheath material) is 0.3 to 1.
6. The method of producing a drawn composite fiber according to
claim 4, wherein the undrawn fiber is drawn at a draw magnification
of 2 to 7 times in the drawing step.
7. The method of producing a drawn composite fiber according to
claim 5, wherein the undrawn fiber is drawn at a draw magnification
of 2 to 7 times in the drawing step.
8. The non-woven fabric according to claim 3, wherein a ratio
between a melt flow rate of the core material at a load of 21.18 N
at 230.degree. C. and a melt flow rate of the sheath material at a
load of 21.18 N at 230.degree. C. (core material/sheath material)
is 0.3 to 1.
Description
RELAYED APPLICATIONS
[0001] The present application is a National Phase of International
Application No. PCT/JP2020/011925 filed Mar. 18, 2020, which claims
priority to Japanese Application No. 2019-068001, filed Mar. 29,
2019.
TECHNICAL FIELD
[0002] The present invention relates to a drawn composite fiber
having a sheath-core structure, a non-woven fabric, and a method of
producing the drawn composite fiber. More specifically, the present
invention relates to a drawn composite fiber having a thin fineness
of 0.6 dtex or less, a method of producing the drawn composite
fiber, and a non-woven fabric using the drawn composite fiber
having the thin fineness.
BACKGROUND ART
[0003] Composite fibers with a sheath-core structure, formed using
two olefinic resins having different characteristics, are utilized
in various fields because of having a thermal adhesion property and
excellent chemical resistance. For example, such composite fibers
with a sheath-core structure can be produced by drawing treatment
of undrawn fibers with a sheath-core structure, formed by
melt-spinning.
[0004] It is demanded that functional non-woven fabrics used in
various filter materials, separators for batteries, and the like
are thin films and have a high mechanical strength. The thinner
fineness and improved single yarn strength of raw material fibers
in comparison with conventional ones are required for achieving
such a non-woven fabric that is a thin film and has a high
mechanical strength. Common examples of methods of increasing the
single yarn strength and elastic modulus of drawn composite fibers
include an increase in draw magnification. However, such an
increase in draw magnification has problems of resulting in yarn
breakage in drawing, the deterioration of non-woven fabric
processability, caused by an increase in the thermal shrinkage of
drawn fibers, and the deterioration of the appearance of a
processed non-woven fabric.
[0005] Thus, technologies of producing drawn composite fibers
having a high strength and a thin fineness by methods other than an
increase in draw magnification have been conventionally proposed
(see, for example, Patent Literatures 1 and 2). For example, in a
composite fiber described in Patent Literature 1, the higher
strength of the composite fiber is intended to be achieved by
specifying the ratio between the weight-average molecular weights
of a crystalline propylene-based polymer which is a core material
and an olefinic polymer which is a sheath material, the melt flow
rates (MFR) of the sheath material and the core material, and the
like.
[0006] In a method of producing a composite fiber described in
Patent Literature 2, the melt flow rate of a core material
discharged from a spinneret is specified, and the ratio between the
melt flow rate of the core material discharged from the spinneret
and the melt flow rate of a sheath material discharged from the
spinneret (=core material MFR/sheath material MFR) is specified, in
order to obtain the composite fiber that has high strength and thin
fineness.
CITATION LIST
Patent Literature
[0007] Patent Literature 1: Japanese Patent Laid-Open No.
2007-107143
[0008] Patent Literature 2: International Publication No. WO
2015/012281
SUMMARY OF INVENTION
Technical Problem
[0009] In production of a non-woven fabric, a raw material fiber
having a suitable fineness is selected and used depending on
intended characteristics such as a thickness, a basis weight, a
filling rate, a pore diameter, and strength. In such a case, the
non-woven fabric may be produced from one raw material fiber;
however, an ultrafine fiber having a fineness of around 0.1 dtex
and a thin fineness fiber having a fineness of around 0.2 to 0.6
dtex may be kneaded to obtain the non-woven fabric having two
characteristics such as a fine pore diameter and a non-woven fabric
strength. Enhancement of the physical properties such as a single
yarn strength and an elastic modulus of both the ultrafine fiber
and the thin-fineness fiber which are raw materials is required for
improving the strength of such a non-woven fabric. In the
above-described technology described in the Patent Literature 1,
however, the composite fiber having a fineness of around 1 dtex is
targeted, and, in addition, the obtained composite fiber has a high
thermal shrinkage of 10% or more.
[0010] In contrast, in the production method described in Patent
Literature 2, the drawn composite fiber having a single yarn
strength of 5 cN/dtex or more, a Young's modulus of 50 cN/dtex or
more, and a thermal shrinkage of 8% or less at 120.degree. C. can
be obtained. However, the technology targets an ultrafine composite
fiber having a fineness of 0.3 dtex or less, and it is difficult to
obtain the equivalent characteristics of a thin-fineness composite
fiber that is thicker than the composite fiber. While further
improvement in the physical properties of single yarn and a
non-woven fabric is desired, there is a limit to the further
improvement in the physical properties such as a single yarn
strength and an elastic modulus even in the case of drawing at a
high magnification in a drawing step in the production by the
method disclosed in the conventional technology.
[0011] Thus, an objective of the present invention is to provide a
drawn composite fiber having a fineness of 0.6 dtex or less, a low
thermal shrinkage, and a high single yarn strength, a non-woven
fabric, and a method of producing the drawn composite fiber.
Solution to Problem
[0012] A drawn composite fiber according to the present invention
is a drawn composite fiber including a sheath-core structure in
which a resin containing a crystalline propylene-based polymer as a
main component is a core material, and a resin containing, as a
main component, an olefinic polymer of which a melting point is
lower than that of the core material is a sheath material, wherein
the drawn composite fiber has a fineness of 0.6 dtex or less, a
melt flow rate of the core material at a load of 21.18 N at
230.degree. C. is 10 to 30 g/10 min, a ratio between
cross-sectional areas of the sheath material and the core material
(sheath material/core material) is 50/50 to 10/90, and the drawn
composite fiber has a single yarn elastic modulus of 70 cN/dtex or
more.
[0013] In the drawn composite fiber, a ratio between a melt flow
rate of the core material at a load of 21.18 N at 230.degree. C.
and a melt flow rate of the sheath material at a load of 21.18 N at
230.degree. C. (core material/sheath material) is, for example, 0.3
to 1.
[0014] A non-woven fabric according to the present invention is
formed using the drawn composite fiber described above.
[0015] A method of producing a drawn composite fiber according to
the present invention includes: a spinning step of obtaining, by
melt-spinning, an undrawn fiber including a sheath-core structure
in which a resin containing a crystalline propylene-based polymer
as a main component is a core material, and a resin containing, as
a main component, an olefinic polymer of which a melting point is
lower than that of the core material is a sheath material; and a
drawing step of obtaining a drawn composite fiber having a fineness
of 0.6 dtex or less by drawing treatment of the undrawn fiber,
wherein the undrawn fiber has a fineness of 4.0 dtex or less, and
has a ratio between cross-sectional areas of the sheath material
and the core material (sheath material/core material) of 50/50 to
10/90, the core material has a melt flow rate of 10 to 30 g/10 min
at a load of 21.18 N at 230.degree. C., and the spinning step and
the drawing step are consecutively performed.
[0016] In the method of producing a drawn composite fiber, a ratio
between a melt flow rate of the core material at a load of 21.18 N
at 230.degree. C. and a melt flow rate of the sheath material at a
load of 21.18 N at 230.degree. C. (core material/sheath material)
may be set in a range of 0.3 to 1.
[0017] The draw magnification of the undrawn fiber in the drawing
step is, for example, 2 to 7 times.
[0018] A value of a melt flow rate in the present invention is a
value measured under conditions of a temperature of 230.degree. C.
and a load of 21.18 N according to A-method in JIS K7210, and the
same applies in the following description unless otherwise
specified.
Advantageous Effects of Invention
[0019] In accordance with the present invention, in a drawn
composite fiber having a fineness of 0.6 dtex or less, a single
yarn strength can be enhanced without increasing a thermal
shrinkage.
BRIEF DESCRIPTION OF DRAWINGS
[0020] FIG. 1 is a view schematically illustrating an example of
the cross-section structure of a drawn composite fiber of an
embodiment of the present invention.
[0021] FIG. 2 is a flow chart illustrating a method of producing a
drawn composite fiber of an embodiment of the present
invention.
[0022] FIG. 3 is a schematic view illustrating a configuration
example of an apparatus in the case of consecutively performing
each step illustrated in FIG. 2.
[0023] FIGS. 4A and 4B are schematic views illustrating apparatus
configurations in the case of separately performing each step
illustrated in FIG. 2, FIG. 4A illustrates the spinning step, and
FIG. 4B illustrates the drawing step.
DESCRIPTION OF EMBODIMENTS
[0024] Embodiments for carrying out the present invention will be
described in detail below with reference to the accompanying
drawings. The present invention is not limited to the embodiments
described below FIG. 1 is a view schematically illustrating an
example of the cross-section structure of a drawn composite fiber
of the present embodiment. As illustrated in FIG. 1, a drawn
composite fiber of the present embodiment is a sheath-core
composite fiber including a core portion 1 and a sheath portion 2
formed in the periphery thereof, and has a fineness of 0.6 dtex or
less, and preferably 0.2 to 0.6 dtex.
[0025] [Core Portion 1]
[0026] The core portion 1 contains a crystalline propylene-based
polymer as a main component, and is formed of a resin having a melt
flow rate (MFR) of 10 to 30 g/10 min at a load of 21.18 N at
230.degree. C. (hereinafter referred to as "core material"). In a
case in which the MFR of the core material is less than 10 g/10
min, the melt tension of the molten resin is prone to be higher, it
is difficult to obtain an undrawn fiber having an intended
fineness, and, in addition, drawing of an undrawn fiber at a high
magnification tends to result in an increase in the frequency of
occurrence of yarn breakage.
[0027] In a case in which the MFR of the core material is more than
30 g/10 min, the melt tension of the molten resin is lower, and
therefore, the orientation crystallinity degree of an undrawn fiber
is decreased, whereby it is impossible to sufficiently enhance the
single yarn strength and elastic modulus of the drawn composite
fiber, and it is difficult to obtain intended single yarn physical
properties. The MFR of the core material is preferably set at 15 to
25 g/10 min, and the setting of the MFR in this range enables the
strength of the drawn composite fiber to be expressed while
decreasing the fineness of the undrawn fiber.
[0028] As the crystalline propylene-based polymer which is the main
component of the core material, for example, an isotactic propylene
homopolymer having crystallinity, an ethylene-propylene random
copolymer having a low ethylene unit content, a propylene block
copolymer including a homo portion including a propylene
homopolymer and a copolymerization portion including an
ethylene-propylene random copolymer having a relatively high
ethylene unit content, in addition, a crystalline
propylene-ethylene-.alpha.-olefin copolymer in which each homo
portion or copolymerization portion in a propylene block copolymer
includes a substance obtained by copolymerization of an
.alpha.-olefin such as butene-1, or the like can be used, and
isotactic polypropylene is particularly preferred from the
viewpoint of drawability, fiber physical properties, and
suppression of thermal shrinkage. These crystalline propylene-based
polymers may be used singly, or in combination of two or more kinds
thereof.
[0029] The core material can be blended with an additive such as a
nucleating agent or an antioxidant at an appropriate rate. In a
relationship with the resin containing the crystalline
propylene-based polymer as the main component, the additive blended
into the core material is preferably an additive which is melted
together to develop an affinity, or an additive which is not
completely melted and of which part adapts to the resin.
[0030] [Sheath Portion 2]
[0031] The sheath portion 2 is formed of a resin containing, as a
main component, an olefinic polymer of which the melting point is
lower than that of the core material (hereinafter referred to as
"sheath material"). As the olefinic polymer which is the main
component of the sheath material, for example, an ethylene polymer
such as a high-density polyethylene, medium-density polyethylene,
low-density polyethylene and a linear low-density polyethylene, a
copolymer of propylene and another .alpha.-olefin, specifically,
propylene-butene-1-random copolymer, propylene-ethylene-butene-1
random copolymer, or an amorphous propylene-based polymer such as
soft polypropylene, poly 4-methylpentene-1, or the like can be
used, and a high-density polyethylene is particularly preferred in
view of fiber physical properties. These olefinic polymers may be
used singly, or in combination of two or more kinds thereof.
[0032] The sheath material can be blended with an additive such as
a nucleating agent or an antioxidant at an appropriate rate. In a
relationship with the resin containing the olefinic polymer as the
main component, the additive blended into the sheath material is
preferably an additive which is melted together to develop an
affinity, or an additive which is not completely melted and of
which part adapts to the resin.
[0033] [Sheath-Core Ratio]
[0034] The drawn composite fiber of the present embodiment has a
sheath-core ratio, i.e., an area ratio between the core portion 1
and the sheath portion 2 in a cross section (cross section
perpendicular to lengthwise direction) (sheath material/core
material) of 50/50 to 10/90. In a case in which the ratio of the
core portion 1 in the cross section is less than 50%, the single
yarn strength and elastic modulus of the drawn composite fiber are
insufficient, and, in addition, a thermal shrinkage is also
increased. In a case in which the ratio of the core portion 1 in
the cross section is more than 90%, the sheath material
contributing to thermal fusion is insufficient, and the strength of
a processed product such as a non-woven fabric is decreased. In a
case in which the ratio of the core portion 1 in the cross section
is too high, a draw magnification is decreased, whereby yarn
breakage is prone to occur, in the drawing step.
[0035] [Core Material MFR/Sheath Material MFR]
[0036] The drawn composite fiber of the present embodiment
preferably has a ratio the MFR of the core material (pellet) at a
load of 21.18 N at 230.degree. C. and the MFR of the sheath
material (pellet) at a load of 21.18 N at 230.degree. C. (core
material MFR/sheath material MFR) of 0.3 to 1. In a case in which
core material MFR/sheath material MFR is less than 0.3, the melt
tension of a molten resin is prone to be higher, and it may be
impossible to produce an undrawn fiber having an intended fineness.
In a case in which core material MFR/sheath material MFR is more
than 1, the melt tension of the molten resin is too low, the single
yarn strength and elastic modulus of the drawn composite fiber are
decreased, and it may be impossible to obtain intended single yarn
physical properties.
[0037] [Single Yarn Elastic Modulus]
[0038] The drawn composite fiber of the present embodiment has a
single yarn elastic modulus of 70 cN/dtex or more. In a case in
which the drawn composite fiber has a single yarn elastic modulus
of less than 70 cN/dtex, the mechanical strength of a thin-film
non-woven fabric is insufficient, and rupture or poor appearance is
prone to occur, when the drawn composite fiber is processed into
the thin-film non-woven fabric.
[0039] [Production Method]
[0040] A method of producing a drawn composite fiber of the present
embodiment will now be described. FIG. 2 is a flow chart
illustrating the method of producing a drawn composite fiber of the
present embodiment, and FIG. 3 is a schematic view illustrating a
configuration example of an apparatus in the case of consecutively
performing each step illustrated in FIG. 2. As illustrated in FIG.
2, the spinning step (step S1) of obtaining an undrawn fiber having
a sheath-core structure by melt-spinning, and the drawing step
(step S2) of obtaining a drawn composite fiber by drawing treatment
of the undrawn fiber are consecutively performed in the method of
producing a drawn composite fiber of the present embodiment.
[0041] <Spinning Step S1>
[0042] In the spinning step S1, an undrawn fiber with a sheath-core
structure having a fineness of 4.0 dtex or less, preferably 0.35 to
4.0 dtex and a sheath-core ratio (sheath material/core material) of
50/50 to 10/90 is melt-spun. In such a case, a resin containing a
crystalline propylene-based polymer as a main component, and having
a melt flow rate of 10 to 30 g/10 min at a load of 21.18 N at
230.degree. C. is used in the core material, and a resin
containing, as a main component, an olefinic polymer of which the
melting point is lower than that of the core material is used in
the sheath material. Moreover, core material MFR/sheath material
MFR is preferably set in a range of 0.3 to 1 for the reason
described above.
[0043] (Undrawn Fiber)
[0044] Like a drawn composite fiber, the sheath material/core
material of an undrawn fiber is also set at 50/50 to 10/90 because
the sheath-core ratio of the undrawn fiber is the sheath-core ratio
of the drawn composite fiber. In a case in which the fineness of
the undrawn fiber is set at 4.0 dtex or more, the enhancement of a
draw magnification is required for setting the fineness of the
drawn composite fiber at 0.6 dtex or less, yarn breakage is prone
to occur in drawing, and the thermal shrinkage of the drawn fiber
is prone to be deteriorated. Therefore, in the drawn composite
fiber of the present embodiment, the fineness of the undrawn fiber
is set at 4.0 dtex or less.
[0045] When a resin with an MFR of 10 to 30 g/10 min (at
230.degree. C. and a test load of 21.18 N), used as the core
material in the drawn composite fiber of the present embodiment, is
allowed to be a molten resin, the resin is prone to result in a
higher tension, and therefore, it is difficult to stably spin an
undrawn fiber having a fineness of less than 0.35 dtex. Therefore,
the fineness of the undrawn fiber is preferably set in a range of
0.35 to 4.0 dtex.
[0046] <Drawing Step S2>
[0047] In the drawing step S2, the drawn composite fiber having a
fineness of 0.6 dtex or less, preferably 0.2 to 0.6 dtex, is
obtained by drawing treatment of the undrawn fiber. In such a case,
when the draw magnification is less than 2 times, the single yarn
strength and elastic modulus of the obtained drawn composite fiber
may be decreased, and intended single yarn physical properties may
be prevented from being obtained. When the draw magnification is
more than 7 times, a frequency at which yarn breakage occurs may be
increased, and productivity may be deteriorated. Thus, the draw
magnification in the drawing step S2 is preferably set at 2 to 7
times.
[0048] <Direct Spinning Drawing Method>
[0049] The drawn composite fiber of the present embodiment is
produced by a direct spinning drawing method (spin-draw method) in
which the spinning step S1 and the drawing step S2, described above
are consecutively performed. For example, in the case of an
apparatus illustrated in FIG. 3, an undrawn fiber 10 with a
sheath-core structure, discharged from a spinneret 11 is introduced
into a vapor drawing bath 13 through an introduction roller 12, and
drawn at a predetermined magnification, and a drawn composite fiber
20 is then delivered by a delivery roller 14, and wound by a winder
15.
[0050] When a spinning step and a drawing step are separately and
inconsecutively performed like a two-stage drawing method, it is
difficult to draw an undrawn fiber having a thin fineness at a high
magnification, and it is impossible to obtain a drawn composite
fiber having an intended strength and an elastic modulus at a
magnification at which the undrawn fiber can be drawn. In contrast,
in the direct spinning drawing method (spin-draw method) in which
the spinning step and the drawing step are consecutively performed,
an undrawn fiber can be stably and immediately transferred to the
drawing step, even an undrawn fiber with a thin fineness, which is
easily cut due to drawing, can be drawn in the state of being
homogeneous and easily stretched, and a drawn composite fiber with
excellent single yarn physical properties is obtained. As a result,
a drawn composite fiber having a fineness of 0.6 dtex or less, a
high single yarn strength, a high single yarn elastic modulus, and
a low thermal shrinkage can be produced from an undrawn fiber
having a fineness of 4.0 dtex or less.
[0051] The drawn composite fiber produced by the method described
above can be allowed to be in the form of a long-fiber filament
used for a woven fabric through oil solution treatment and drying
treatment. To be in a form used for a non-woven fabric, the drawn
composite fiber may also be allowed to be a staple fiber through
oil solution treatment, crimping processing treatment, and drying
treatment subsequently to the drawing step. Further, the drawn
composite fiber may also be cut into short fibers through or
without through drying treatment after oil solution treatment, and
allowed to be chopped fibers.
[0052] As described in detail above, the drawn composite fiber of
the present embodiment has the MFR of the core material, the
sheath-core ratio, and the single yarn elastic modulus, set in the
specific ranges, and can therefore have a single yarn strength of 6
cN/dtex or more and a bundle thermal shrinkage at 120.degree. C.,
reduced to 8% or less, despite having a thin fineness of 0.6 dtex.
As described above, the drawn composite fiber of the present
embodiment has a high strength and a low thermal shrinkage, and can
be therefore preferably used in various applications for non-woven
fabrics, and applications such as battery separators and filters. A
thin-film non-woven fabric formed using the drawn composite fiber
of the present embodiment has a high mechanical strength and
suppressed thermal shrinkage in processing, and can therefore
result in elimination of occurrence of poor processing, such as
rupture, and poor appearance.
EXAMPLES
[0053] The effects of the present invention will be specifically
described below with reference to Examples and Comparative
Examples. In the examples, the drawn composite fibers of Examples
and Comparative Examples were produced by a method described below,
and the performance thereof was evaluated.
[0054] [Raw Materials]
[0055] (1) Core Material
[0056] A: Isotactic polypropylene "Y2005GP" manufactured by Prime
Polymer Co., Ltd.
[0057] (MFR=20 g/10 min, Q value=4.7)
[0058] B: Isotactic polypropylene "Y2000GV" manufactured by Prime
Polymer Co., Ltd.
[0059] (MFR=18 g/10 min, Q value=3.0)
[0060] C: Isotactic polypropylene "S119" manufactured by Prime
Polymer Co., Ltd.
[0061] (MFR=60 g/10 min, Q value=2.8)
[0062] D: Isotactic polypropylene "S137L" manufactured by Prime
Polymer Co., Ltd.
[0063] (MFR=30 g/10 min, Q value=3.2)
[0064] (2) Sheath Material
[0065] a: High-density polyethylene "S6932" manufactured by KEIYO
POLYETHYLENE CO., LTD.
[0066] (MFR=40 g/10 min, Q value=5.1)
[0067] b: High-density polyethylene "J300" manufactured by Asahi
Kasei Chemicals Corp.
[0068] (MFR=70 g/10 min, Q value=4.3)
[0069] [Evaluation/Measurement Methods]
[0070] (1) Fineness
[0071] The finenesses of an undrawn fiber and a drawn composite
fiber were measured in conformity with JIS L1015.
[0072] (2) MFR
[0073] The MFR of each material pellet used in the core material
and the sheath material was measured according to A-method in JIS
K7210 under conditions of a test temperature of 230.degree. C. and
a test load of 21.18 N.
[0074] (3) Single Yarn Physical Properties of Drawn Composite
Fiber
[0075] The single yarn strength and elastic modulus of a drawn
composite fiber were measured by a method in conformity with JIS
L1015.
[0076] (4) Bundle Physical Properties of Drawn Composite Fiber
[0077] The thermal shrinkage of a fiber bundle (bundle) was
measured by a method in conformity with JIS L1015. In such a case,
the number of filaments was set at 12018, heat treatment
temperature was set at 120.degree. C., and heat treatment time was
set at 10 minutes.
Example 1
[0078] The spinning step and the drawing step were consecutively
performed using the apparatus illustrated in FIG. 3, to produce a
drawn composite fiber having a sheath-core structure.
[0079] (1) Spinning Step
[0080] An undrawn fiber with a sheath-core structure having a
fineness of 1.88 dtex was produced by melt-spinning using a core
material A and a sheath material a. In such a case, a
sheath-core-type composite spinneret was used, and a sheath-core
ratio (sheath material/core material) was set at 35/65. As spinning
conditions, extruder cylinder temperature was set at 255.degree.
C., spinneret temperature was set at 270.degree. C., and a spinning
speed was set at 180 m/min.
[0081] (2) Drawing Step
[0082] The drawing step was performed subsequently to the spinning
step. Specifically, the undrawn fiber 10 obtained in the spinning
step was introduced into the introduction roller 12 at a speed of
180 m/min, the speed of the drawn fiber delivery roller 14 was
increased, and the undrawn fiber 10 was drawn in the vapor drawing
bath 13 with ordinary pressure vapor at 100.degree. C.
[0083] As a result, the speed of the drawn fiber delivery roller 14
and a draw magnification, at which yarn breakage did not occur in
the spinning step and the drawing step, and it was possible to
perform industrially stable drawing, were 910 m/min and 5.10 times,
respectively. Moreover, the fineness of the drawn composite fiber
of Example 1 produced under such conditions was 0.4 dtex.
Example 2
[0084] An undrawn fiber having a fineness of 1.72 dtex was
melt-spun by a method and under conditions similar to those in
Example 1 except that a core material B was used instead of the
core material A, and a sheath-core ratio (sheath material/core
material) was set at 25/75, and the undrawn fiber was drawn by a
method and under conditions similar to those in Example 1.
[0085] As a result, the speed of a drawn fiber delivery roller 14
and a draw magnification, at which yarn breakage did not occur in a
spinning step and a drawing step, and it was possible to perform
industrially stable drawing, were 841 m/min and 4.67 times,
respectively. Moreover, the fineness of a drawn composite fiber of
Example 2 produced under such conditions was 0.4 dtex.
Example 3
[0086] An undrawn fiber having a fineness of 1.60 dtex was
melt-spun by a method and under conditions similar to those in
Example 1 except that a sheath-core ratio (sheath material/core
material) was set at 50/50, and the undrawn fiber was drawn by a
method and under conditions similar to those in Example 1.
[0087] As a result, the speed of a drawn fiber delivery roller 14
and a draw magnification, at which yarn breakage did not occur in a
spinning step and a drawing step, and it was possible to perform
industrially stable drawing, were 781 m/min and 4.34 times,
respectively. Moreover, the fineness of a drawn composite fiber of
Example 3 produced under such conditions was 0.4 dtex.
Example 4
[0088] An undrawn fiber having a fineness of 0.80 dtex was
melt-spun by a method and under conditions similar to those in
Example 1 except that a core material D was used instead of the
core material A, and a sheath-core ratio (sheath material/core
material) was set at 50/50, and the undrawn fiber was drawn by a
method and under conditions similar to those in Example 1.
[0089] As a result, the speed of a drawn fiber delivery roller 14
and a draw magnification, at which yarn breakage did not occur in a
spinning step and a drawing step, and it was possible to perform
industrially stable drawing, were 781 m/min and 4.34 times,
respectively. Moreover, the fineness of a drawn composite fiber of
Example 4 produced under such conditions was 0.2 dtex.
Example 5
[0090] An undrawn fiber having a fineness of 0.80 dtex was
melt-spun by a method and under conditions similar to those in
Example 1 except that the core material D and a sheath material b
were used, and a sheath-core ratio (sheath material/core material)
was set at 50/50, and the undrawn fiber was drawn by a method and
under conditions similar to those in Example 1.
[0091] As a result, the speed of a drawn fiber delivery roller 14
and a draw magnification, at which yarn breakage did not occur in a
spinning step and a drawing step, and it was possible to perform
industrially stable drawing, were 781 m/min and 4.34 times,
respectively. Moreover, the fineness of a drawn composite fiber of
Example 5 produced under such conditions was 0.2 dtex.
Comparative Example 1
[0092] An undrawn fiber having a fineness of 1.60 dtex was
melt-spun by a method and under conditions similar to those in
Example 1 except that the core material C and the sheath material b
were used, and a sheath-core ratio (sheath material/core material)
was set at 50/50, and the undrawn fiber was drawn by a method and
under conditions similar to those in Example 1.
[0093] As a result, the speed of a drawn fiber delivery roller 14
and a draw magnification, at which yarn breakage did not occur in a
spinning step and a drawing step, and it was possible to perform
industrially stable drawing, were 781 m/min and 4.34 times,
respectively. Moreover, the fineness of a drawn composite fiber of
Comparative Example 1 produced under such conditions was 0.4
dtex.
Comparative Example 2
[0094] An undrawn fiber having a fineness of 1.60 dtex was
melt-spun by a method and under conditions similar to those in
Example 1 except that a sheath-core ratio (sheath material/core
material) was set at 60/40, and the undrawn fiber was drawn by a
method and under conditions similar to those in Example 1.
[0095] As a result, the speed of a drawn fiber delivery roller 14
and a draw magnification, at which yarn breakage did not occur in a
spinning step and a drawing step, and it was possible to perform
industrially stable drawing, were 781 m/min and 4.34 times,
respectively. Moreover, the fineness of a drawn composite fiber of
Comparative Example 2 produced under such conditions was 0.4
dtex.
Comparative Example 3
[0096] A spinning step and a drawing step were inconsecutively
performed using apparatuses illustrated in FIGS. 4A and 4B, to
produce a drawn composite fiber having a sheath-core structure.
[0097] (1) Spinning Step
[0098] Undrawn fibers 110 having a fineness of 2.95 dtex were
melt-spun using a melt spinning apparatus including a spinneret
101, rollers 102 and 103, and a winding device 104 illustrated in
FIG. 4A under conditions similar to those in Comparative Example
1.
[0099] (2) Drawing Step
[0100] The undrawn fibers 110 were drawn using a two-stage drawing
apparatus in which a preliminary drawing bath 112 performing
heating in warm water and a main drawing bath 114 performing
heating with heated saturated vapor were arranged between three
rollers 111, 113, and 115 illustrated in FIG. 4B, to obtain a drawn
composite fiber 120. Specifically, the speed of the introduction
roller 111 was set at 10 m/min, the speed of the preliminary
drawing delivery roller 113 was set at 29 m/min, and a bundle
(fiber bundle) in which the undrawn fibers 110 obtained in the
spinning step were tied was subjected to preliminary drawing
treatment in warm water at 93.degree. C. in the preliminary drawing
bath 112. Subsequently, the speed of the drawn fiber delivery
roller 115 was increased, main drawing was performed in
pressurization saturated vapor at 124.degree. C. in the main
drawing bath 114, and the obtained drawn composite fiber 120 was
wound by a winder 116.
[0101] As a result, the speed of the drawn fiber delivery roller
115 and a draw magnification, at which yarn breakage did not occur
in a spinning step and a drawing step, and it was possible to
perform industrially stable drawing, were 80 m/min and 8.0 times,
respectively. Moreover, the fineness of a drawn composite fiber of
Comparative Example 3 produced under such conditions was 0.4
dtex.
Comparative Example 4
[0102] An undrawn fiber having a fineness of 2.95 dtex was
melt-spun by a method and under conditions similar to those in
Comparative Example 3 except that the core material A and the
sheath material a were used. The undrawn fiber was drawn, in a step
other than the spinning step, by a method and under conditions
similar to those in Comparative Example 3.
[0103] As a result, the speed of the drawn fiber delivery roller
115 and a draw magnification, at which yarn breakage did not occur
in a spinning step and a drawing step, and it was possible to
perform industrially stable drawing, were 80 m/min and 8.0 times,
respectively. Moreover, the fineness of a drawn composite fiber of
Comparative Example 4 produced under such conditions was 0.4
dtex.
Comparative Example 5
[0104] An undrawn fiber having a fineness of 3.98 dtex was
melt-spun by a method and under conditions similar to those in
Comparative Example 4 except that the rotation number of a gear
pump was adjusted as appropriate so that an intended fineness was
achieved. The undrawn fiber was drawn, in a step other than the
spinning step, by a method and under conditions similar to those in
Comparative Example 3.
[0105] As a result, the speed of the drawn fiber delivery roller
115 and a draw magnification, at which yarn breakage did not occur
in a spinning step and a drawing step, and it was possible to
perform industrially stable drawing, were 54 m/min and 5.4 times,
respectively. Moreover, the fineness of a drawn composite fiber of
Comparative Example 5 produced under such conditions was 0.8
dtex.
Comparative Example 6
[0106] (1) Spinning Step
[0107] An undrawn fiber having a fineness of 1.88 dtex was
melt-spun by a method and under conditions similar to those in
Example 1 except that a sheath-core ratio was set at 35/65.
[0108] (2) Drawing Step
[0109] Undrawn fibers were drawn in a step other than the spinning
step using a drawing apparatus in which a warm water drawing bath
was arranged between two rollers. Specifically, a bundle (fiber
bundle) in which the undrawn fibers obtained in the spinning step
were tied was subjected to drawing treatment in warm water at
93.degree. C. in the warm water drawing bath under conditions of an
introduction roller speed of 10 m/min and a drawn fiber delivery
roller speed of 51 m/min.
[0110] As a result, yarn breakage occurred in the drawing step at a
drawn fiber delivery roller speed of 51 m/min, and it was
impossible to obtain a drawn composite fiber at a draw
magnification set at 5.1 times.
[0111] The evaluation results of the drawn composite fibers of
Examples and Comparative Examples, produced by the methods
described above, are set forth in Tables 1 and 2 described
below.
TABLE-US-00001 TABLE 1 Exam- Exam- Exam- Exam- Exam ple 1 ple 2 ple
3 ple 4 ple 5 Produc- Sheath-core 35/65 25/75 50/50 50/50 50/50
tion ratio [sheath condi- material/core tions material] Core
material 20 18 20 30 30 MFR (g/10 min) Sheath 40 40 40 40 70
material MFR (g/10 min) Core material 0.5 0.45 0.50 0.75 0.43
MFR/sheath material MFR Spinning Consec- Consec- Consec- Consec-
Consec- drawing utive utive utive utive utive method Fineness 1.88
1.72 1.60 0.80 0.80 of undrawn fiber (dtex) Draw 5.10 4.67 4.34
4.34 4.34 magnification (times) Eval- Fineness 0.4 0.4 0.4 0.2 0.2
uation of drawn composite fiber (dtex) Single yarn 7 7 6 7 6
maximum strength (cN/dtex) Single yarn 75 90 70 75 73 elastic
modulus (cN/dtex) Bundle 6.6 7.1 6.8 6 to 7 7.5 thermal shrinkage
(%) [120.degree. C.]
TABLE-US-00002 TABLE 2 Compar- Compar- Compar- Compar- Compar-
Compar- ative ative ative ative ative ative Exam- Exam- Exam- Exam-
Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 Produc- Sheath-core
50/50 60/40 50/50 50/50 50/50 35/65 tion ratio [sheath condi-
material/core tions material] Core material 60 20 60 20 20 20 MFR
(g/10 min) Sheath material 70 40 70 40 40 40 MFR (g/10 min) Core
material 0.86 0.50 0.86 0.50 0.50 0.50 MFR/sheath material MFR
Spinning Consec- Consec- Inconsec- Inconsec- Inconsec- Inconsec-
drawing utive utive utive utive utive utive method Fineness of 1.60
1.60 2.95 2.95 3.98 1.88 undrawn fiber (dtex) Draw 4.34 4.34 8.0
8.0 5.4 5.1 magnification (set (times) value) Eval- Fineness 0.4
0.4 0.4 0.4 0.8 -- uation of drawn composite fiber (dtex) Single
yarn 4 5 5 to 6 7 5 to 6 -- maximum strength (cN/dtex) Single yam
50 60 60 80 50 -- elastic modulus (cN/dtex) Bundle thermal 9.2 9 5
10 5 -- shrinkage (%) [120.degree. C.]
[0112] As set forth in Table 2 above, the drawn composite fibers of
Comparative Examples 1 and 3, in which resins having MFRs of more
than 30 g/10 min were used in the core materials, had low single
yarn strengths and low elastic moduli. The drawn composite fiber of
Comparative Example 2, having a sheath-core ratio (sheath
material/core material) of 60/40 and a small content of core
material, had a low single yarn strength and a low elastic modulus.
The drawn composite fiber of Comparative Example 4, in which the
spinning step and the drawing step were performed as separate
steps, was drawn at a high magnification of 8 times, was able to
result in enhancement of a single yarn strength and an elastic
modulus, and also resulted in an increase in bundle thermal
shrinkage.
[0113] In contrast, the drawn composite fiber of Comparative
Example 5, in which the spinning step and the drawing step were
performed as separate steps, and a low draw magnification was
further set at 5.4 times, resulted in prevention of an increase in
bundle thermal shrinkage but resulted in a low single yarn strength
and a low elastic modulus. In Comparative Example 6, in which an
undrawn fiber of which the fineness was equal to that in Example 1
was spun in a step other than the drawing step, and the undrawn
fiber was subjected only to warm water drawing without preliminary
drawing, yarn breakage occurred in the drawing step before
achieving at a needed draw magnification, and it was impossible to
produce a fiber for evaluation.
[0114] In contrast, the drawn composite fibers of Examples 1 to 5,
produced in the scope of the present invention, had a bundle
thermal shrinkage of 8% or less at 120.degree. C. and a single yarn
strength of 6 cN/dtex or more although having a fineness of 0.6
dtex or less, as set forth in Table 1 above.
[0115] On the basis of the results, it was confirmed that a drawn
composite fiber having a fineness in a range of 0.6 dtex or less, a
low thermal shrinkage, and a high single yarn strength is obtained
according to the present invention.
* * * * *