CON ( 3-P',` ' 1D 3.' AND NON-WOVE COMPRISING THE
TECHNICAL FIELD
[0001]
The present invention relates to crimped conjugated
fibers and a non-woven fabric comprising the fibers.
10 BACKGROUND ART
[0002]
Polypropylene non-woven fabrics have excellent
properties such as breathability and softness and are used as
sanitary materials including disposable diapers and sanitary
15 napkins. However, further improvements in their properties
have been required. For example, polypropylene non-woven
fabrics improved in softness, bulkiness and mechanical
strengtia are desired.
[0003]
20 To obtain non-woven fabrics having excellent softness and
bulkiness, various methods have been proposed in which
nonwoven fabrics are formed of crimped polypropylene fibers.
For example, Patent Document 1 discloses non-woven fabrics that
comprise conjugated fibers having a crimpable cross-sectional
SF- 2365
configuration wherein the conjugated fibers comprise a first
component comprising propylene polymer and a second component
comprising polypropylene with different physical properties
from the first component. The second polypropylene is selected
5 from the group consisting of high MFR polypropylenes, low
polydispersity polypropylenes, amorphous polypropylenes and
elastic (elastomeric) polypropylenes. According to the
disclosure, by melt. spinning the first component and the second
component having different physical properties from each other,
10 the resultant conjugated fibers give crimped fibers capable
of forming non---woven fabrics with excellent softness and
elastic properties.
[0004]
Patent Document 2 discloses non-woven fabrics that
15 comprise parallel type crimped conjugated fibers comprising
ethylene/propylene random copolymer and polypropylc-^7.e.
[0005]
Patent Document 1, crimped conjugated fibers are
obtained from a combination of polypropylenes having
20 dissimilar properties. In detail, Example 1, discloses a
combination of polypropylenes having differing MFR and
molecular weight distribution in which parallel type
conjugated fibers are formed from a first polypropylene having
an MFR of 35 and a polydispersity number of 3 and a second
SF---2365
polypropylene having an MFR of 25 and a polydispersity number
of 2.
[0006]
The conjugated fibers obtained by combining
ethylene/propylene random copolymer and polypropylene that
differ in crystallization rate, as described in Patent Document
2, is excellent in crimp properties. However, depending on
applications, non-woven fabrics further excellent in crimp
properties and bulkiness are desired.
10
CITATION LIST
PATENT DOCUMENTS
[0007]
Patent Document 1. US Patent No, 6,454,989
15 Patent Document 20 JP-A-H07-197367
UMW Y OF THE INVENTION
TECHNICAL PROBLEM
[0008]
20 It is an object of the present invention to obtain crimped
conjugated fibers having further excellent crimp properties
compared with conventional crimped fibers.
SF--2365
[0009]
4
TECHNI CAL SOLUTION
The present inventors studied diligently and have found
that more highly crimped conjugated fibers, for example
5 conjugated fibers having an eccentric core-sheath
configuration, are obtained from two kinds of propylene
polymers differing in melting point by constituting the core
from a propylene polymer with a high melting point having a
larger Mz/Mw than that of a propylene polymer with a low melting
10 point that constitutes the sheath. The present invention has
been completed based on the finding.
[0010]
An aspect of the present invention is crimped conjugated
fibers having a crimpable cross-sectional configuration
15 wherein a cross section of the fibers comprises at least two
portions: a portion (a) and a portion (b),
the mass ratio of the portion (a) to the portion (b)
[(a):(br)] is in the range of 10:90 to 60:40,
the portion (a) comprises a propylene polymer (A) and the
20 portion (b) comprises a propylene/aT-olefin random copolymer
(B),
the propylene polymer (A) has Mz/Mw(A) and the
propylene/a-olefin random copolymer (B) has Mz/Mw(B) wherein
the difference thereof [Mz/Mw(A) - Mz/Mw(B) : AMz/Mw] is in the
SF--2365
5
range of 0.10 to 2.2, and.
the propylene polymer (A) has a melting point [Tm (A) ] and
the propylene/a-olefin random copolymer (B) has a melting point
[Tm(B)] wherein the difference thereof exceeds 10°C.
ADVANTAGEOUS EFFECT OF THE INVENTION
[0011]
The crimped conjugated fibers of the present invention
have further excellent crimp properties compared with
10 conventional crimped conjugated fibers composed of a propylene
homopolymer and a propylene/a--olefin random copolymer, and
therefore a non-woven fabric excellent in bulkiness and
softness can be provided.
15 BRIEF DESCRIPTION OF THE DRAWINGS
[0012]
Fig. 1 is a perspective view showing an embodiment of a
crimped- conjugated fiber according to the present invention.
Fig. 2 is a view for explaining a softness test for a
20 non-woven fabric.
Fig. 3 is a cross-sectional view of a crimped conjugated
fiber according to the present invention.
Fig. 4 is a cross-sectional view of a crimped conjugated
fiber according to the present invention.
SF--2365
10
Fig. 5 is a cross---sectional view of a crimped conjugated
fiber according to the present invention.
Fig. 6 is a cross-sectional view of a crimped conjugated
fiber according to the present invention.
Fig. 7 is a cross-sectional view of a crimped conjugated
fiber according to the present invention.
Fig. 8 is a cross-sectional view of a crimped conjugated
fiber according to the present invention.
DESCRIPTION OF EMBODIKEINTS
[0013]
(Propylene polymer (A))
In the crimped conjugated fibers of the present invention
having a crimpable cross-sectional configuration wherein a
15 cross section of the fibers comprises at least two portions:
a portion (a) and a portion (b) (hereinafter, also referred
to as the "crimped conjugated fibers"), the propylene polymer
(A) for-forming the portion (a) usually has a melt flow rate
(MFR) (ASTM D-1238, 230°C, 2160 g load) of 20 to 100 g/10 min,
20 preferably 30 to 80 g/10 min. If MFR of the propylene polymer
is less than 20 g/10 min, the melt viscosity is high and the
spinnability is poor. If MFR of the propylene polymer exceeds
100 g/10 min, an obtainable non---woven fabric may have poor
tensile strength.
SF'--2365
[0014]
7
The propylene polymer (A) according to the present
invention has a higher melting point than the melting point
of the propylene/a-olefin random copolymer (B) for forming the
5 portion (b) of the crimped conjugated fibers, wherein the
difference thereof exceeds 10°C, preferably in the range of
12 to 40°C, By making the difference of the melting point
larger, the conjugated fibers have further excellent crimp
properties.
10 [0015]
The propylene polymer (A) according to the present
invention usually has a melting point of not lower than 155 °C,
preferably in the range of 157 to 165°C. In the case of a
propylene polymer having a melting point of lower than 155°C,
15 it may be difficult for the difference with the melting point
of the propylene/(Y- olefin random copolymer (B) to exceed 10°C.
[0016]
The propylene polymer (A) according to the present
invention is a propylene polymer containing propylene as a main
20 component, with examples including a propylene homopolyiner and
a propylene/a-olefin random copolymer of propylene and a small
amount, e.g., not more than 2 mol%, preferably not more than
1 mol%, of one or more a-olefins such as ethylene, 1-butene,
1--pentene, 1-hexene, 1--octene, 1-decene, 3---methyl --butene,
S'--2365
8
3--methyl-l -pentene, 3-ethyl---1---pentene, 4---methyl---1---pentene
and 4-methyl-l-hexene, for example a propylene/ethylene random
copolymer and a propylene /ethylene/1-butene random copolymer.
The propylene polymer (A) according to the present invention
is preferably a propylene homopolymer.
[0017]
The ratio [Mz/Mw(A)] of Z-average molecular weight (Mz)
to weight average molecular weight (Mw) of the propylene polymer
(A) according to the present invention is not particularly
10 limited as long as the difference with Mz/Mw(B) of the
propylene/a-olefin random copolymer (B), described later, i.e.,
[ (Mz/Mw ( A ) ) - (Mz/Mw ( B ) ) : AMz/Mw] is in the range of 0 . 1 0 to 2. 2
The ratio Mz/Mw(A) is usually 2.0 or more, preferably in the
range of 2. 1 to 4 . 5 , more preferably 2. 1 to 3. 0 n The propylene
15 polymer having [Mz/Mw(A)] of more than 4.5 may have poor
spinnability.
[0018]
When the propylene polymer (A) has Mz/Mw(A) within the
above range, it is easy to make a combination of the propylene
20 polymer (A) and the propylene/n-olefin random copolymer (B)
such that the difference between Z-average molecular weight
(Mz) to weight average molecular weight (Mw) ratio [Mz/Mw(A)]
of the propylene polymer (A) , and Z-average molecular weight
(Mz) to weight average molecular weight (Mw) ratio [Mz/Mw(B)]
SP'--2365
of the propylene/e olefin random copolymer (B), i.e.,
[(Mz/Mw ( A)) (Mz/MW ( B))o A(Mz /Mw)is in the range of 0.10
to 2.2.
[0019]
The propylene polymer (A) according to the present
invention usually has Mw in the range of 150,000 to 250,000,
and Mz in the range of 300,000 to 600,000.
[0020]
The propylene polymer (A) according to the present
10 invention usually has a ratio of weight average molecular weight
(Mw) to number average molecular weight (Mn), i.e., molecular
weight distribution [Mw/Mn (A)], in the range of 200 to 4a0,
preferably 202 to 3.54
[0021]
15 In the present invention, Mz, Mw, Mn, Mz/Mw(A) and
Mw/Mn (A) of the pt-opylene polymer (A) may be determined by GPC
(gel permeation chromatography) as will be described later.
[0022] -
The propylene polymer (A) according to the present
20 invention may be obtained by homopolymerizing propylene or
copolymerizing propylene and a small amount of aryolef_in by
slurry polymerization, gas-phase polymerization or bulk
polymerization using a Ziegler-Natta catalyst that contains
a titanium containing solid transition metal component and an
SF-2365
10
organometallic component or a metallocene catalyst that
contains a transition metal compound of Group IV to VI of
periodic table with at least one cyclopentadienyl skeleton and
a cocatalyst component. At this time, propylene polymers
5 differing in MFR, in particular a propylene polymer having an
MFR and a small amount of a propylene polymer having an MFR
lower than the other propylene polymer may be mixed together
or produced by multistage polymerization so that Mz, Mw and
Mz/Mw will be in the above-described ranges; alternatively,
10 a propylene polymer having the above Mz, Mw and Mz/Mw may be
produced directly.
[0023]
The Mw/Mn(A) and Mz/Mw(A) of the propylene polymer (A)
may be controlled by using specific catalysts and adjusting
15 the polymerization conditions, or by decomposing the polymer
with peroxides or the like, or by mixing two or more kinds of
polymers differing in molecular weight.
[0024]
As the propylene polymer (A) according to the present
20 invention, a commercially available propylene polymer may be
used, with examples including NOVATEC PP SA06A manufactured
and sold by Japan Polypropylene Corporation.
[0025]
The propylene polymer (A) according to the present
SF---2365
II
invention may be blended with known additives or other polymers
as required while still achieving the objects of the present
invention. Exemplary additives are antioxidants, weathering
stabilizers, light stabilizers, antistatic agents,
5 anti-fogging agents, anti-blocking agents, lubricants,
nucleating agents and pigments.
[0026]
(Propylene/a-olefin random copolymer (B))
The propylene/amolefin random copolymer (B) for forming
10 the portion (b) of the crimped conjugated fibers of the present
invention usually has a melt flow rate (MFR) (ASTM D-1238, 230°C,
2160 g load) of 20 to 100 g/10 min, preferably 30 to 80 g/10
mine If MFR of the propylene polymer is less than 20 g/10 min,
the melt viscosity is high and the spinnability is poor. If
15 MFR of the propylene polymer exceeds 100 g/10 min, an obtainable
nonwoven fabric may have poor tensile strength.
[0027]
The propylene/a-olefin random copolymer (B) according to
the present invention has a lower melting point than the melting
20 point of the propylene polymer (A) for forming the portion (a)
of the crimped conjugated fibers of the present invenLion,
wherein the difference thereof exceeds 10°C, preferably in the
range of 12 to 40°C,
[0028]
SF--2365
12.
The propylene/a-olefin random copolymer (B) according to
the present invention usually has a melting point in the range
of 120 to 155°C, preferably 125 to 150°C. The copolymer having
a melting point of lower than 120 °C may have poor heat resistance.
5 On the other hand, in the case of the propylene polymer having
a melting point of higher than 155°C, it may be difficult for
the difference with the melting point of the propylene polymer
(A) toexceed 10°C.
[0029]
10 The propylene/c olefin random copolymer (B) according to
the present invention is a random copolymer of propylene with
an a-olefin, specifically, one or more a-olefins (excluding
propylene) such as ethylene, l-butene, 1--pentene, 1-hexene,
l-octene, l-decen.e, 3-methyl-l-butene, 3-methyl-l--pentene,
15 3-ethyl-l-pentene, 4-methyl-1-pentene and 4 methyl-l-hexene,
the copolymer having a melting point falling within I lie above
range and usually containing the acolefi_n in an amount of 2
to 10 mol .
[0030]
20 The propylene/a--olefin random copolymer (B) according to
the present invention preferably has a ratio [Mz/Mw(B)] of
Z-average molecular weight (Mz) to weight average molecular
weight (Mw) of not more than 2. 5, more preferably not more than
2.3.
SF-2365
[0031]
13
The propylene/a-olefin random copolymer (B) according to
the present invention usually has Mw in the range of 150,000
to 250,000, and Mz in the range of 300,000 to 600,000.
[0032]
The propylene/a-olefin random copolymer (B) according to
the present invention usually has a ratio of weight average
molecular weight (Mw) to number average molecular weight (Mn)
idea, molecular weight distribution [Mw/Mn(B)], in the range
10 of 200 to 4.0, and preferably 2.2 to 3.5,
[0033]
In the present invention, Mz, Mw, Mn, Mz/Mw(B) and
Mw/Mn(B) of the propylene/a-olefin random copolymer (B) may
be determined by GPC (gel permeation chromatography) as will
15 be described later.
[0034]
The propylene/a-olefin random copolymer (B) according to
the pre-sent invention may be produced in a polymerization
process similar to that for the propylene polymer (A) At this
20 time, a propylene/a-olefin random copolymer having an MFR and
a small amount of a propylene/a-olefin random copolymer having
an MFR differing from the other propylene/a-=olefin random
copolymer may be mixed together or produced by multistage
polymerization so that Mz, Mw and Mz/Mw will be in the
SF---2365
1!I
above--described ranges; alternatively, a propylene/a--olefin
random copolymer having the above Mz, Mw and Mz/Mw may be
produced directly.
[0035]
5 The Mw/Mn(B) and Mz/Mw(B) of the propylene/a-olefin
random copolymer (B) may be controlled by using specific
catalysts and adjusting the polymerization conditions, or by
decomposing the polymer with peroxides or the like, or by mixing
two or more kinds of polymers differing in molecular weight.
10 [0036]
As the propylene/a-olefin random copolymer (B) according
to the present invention, a commercially available propylene
polymer may be used, with examples including Prime Polypro S119
manufactured and sold by Prime Polymer Co., Ltd.
15 [0037]
The propylene/a-=olefin random copolymer (B) according to
the present invention may be blended with known additives or
other polymers as required while still achieving the objects
the present invention. Exemplary additives are
20 antioxidants , weathering stabilizers, light stabilizers,
antistatic agents , anti-- fogging agents , anti-blocking agents,
lubricants, nucleating agents and pigments.
[0038]
(Crimped conjugated fibers)
SF- 2 3 65
15
The crimped conjugated fibers of the present invention
comprise the propylene polymer (A) and the propylene/a--olefin
random copolymer (B) and have a crimpable cross-sectional
configuration wherein a cross section of the fibers comprises
5 at least two portions: a portion (a) and a portion (b),
the mass ratio of the portion (a) to the portion (b)
[(a):(b)] is in the range of 10:90 to 60090,
the portion (a) comprises the propylene polymer (A) and
the portion (b) comprises the propylene/a-olefin random
10 copolymer (B),
the difference between Mz/Mw(A) of the propylene polymer
(A) and Mz/Mw(B) of the propylene/a--olefin random copolymer
(B), [Mz/Mw(A) e Mz/Mw(B)o L1Mz/Mw], is in the range of 0.10
to 202, and
15 the difference between the melting point [Tm(A)] of the
propylene polymer (A) and the melting point [Tm(B)] of the
propylene/a-olefin random copolymer (B), [L1Tm = Tm (A) - Tm (B) ] ,
exceeds-10°C.
[0039]
20 In an embodiment, the crimpable cross-sectional
configuration may be an eccentric core-sheath configu:i.ation
in which the core is the portion (a) formed of the propylene
polymer (A) with larger Mz/Mw, and the sheath is the portion
(b) formed of the propylene/e-olefin random copolymer (B) with
SFe.-2365
16
smaller Mz/Mwe The core (the portion (a)) may be completely
covered with the sheath of the propylene/u-olefin random
copolymer (B) with smaller Mz/Mw, or part of the core may be
exposed on the surface of the crimped conjugated fibers. The
5 joint between the core and the sheath may be straight or curved.
In an embodiment, the joint between the core and the sheath
may be straight and part of the core may be exposed on the surface
of the crimped conjugated fibers, a configuration known as a
side-by-side configuration.
10 [0040]
(Mass ratio of the portion (a) to the portion (b))
In the crimped conjugated fibers of the present invention,
the mass ratio of the portion (a) to the portion (b) [ (a) o (b) ]
is in the range of 10:90 to 60:40, preferably 10.90 to 50°50,
15 more preferably 20:80 to 40:60. If the mass ratio of the
portion (a) to the portion (b) is in excess of or below the
above range, crimp properties are deteriorated.
[0041]
(®Mz/Mw)
20 The difference between Mz/Mw(A) of the propylene polymer
(A) for forming the portion (a) and Mz/Mw(B) of the
propylene/a-olefin random copolymer (B) for forming the
portion (b), [Mz/Mw(A) - Mz/Mw(B): OMz/Mw], is in the range
of 0010 to 202, preferably 0020 to 2.2, more preferably 0025
SF--2365
1.7
to 2 e O. If a propylene polymer and a propylene/a-olefin. random
copolymer are used wherein AMz/Mw is less than 0.10, crimp
properties may be deteriorated. If a propylene polymer and a
propylene/a-olefin random copolymer are used wherein /\Mz/Mw
exceeds 202, the spinnability may be deteriorated. Herein, Mz
is known as Z-average molecular weight and is defined by
Equation (1) below:
[0042]
10 [0043]
In Equation (1) , Mi is the molecular weight of the polymer
(the propylene polymer (A) and the propylene/a-olefin random
copolymer polymer (B); hereinafter, referred to as the
"propylene polymer" when these two polymers are comb_i tied) and
15 Ni is the number of moles of the polymer (propylene polyme_r)
[0044]
In general, Mz is considered to reflect more precisely
high-molecular weight components in a polymer. Therefore, the
Mz/Mw indicates a molecular weight distribution reflecting
20 more precisely high-molecular weight components than the usual
molecular weight distribution Mw/Mn. The molecular weight
distribution Mz/Mw affects fiber crimp properties.
SF-2365
1 8
K Mw/Mn)
As long as AMz/Mw is in the range described above, an
absolute value of the difference between Mw/Mn(A) of the
propylene polymer (A) and Mw/Mn(B) of the propylene/a-olefin
5 random copolymer (B) [Mw/Mn (A) - Mw/Mn (B) . OMw/Mn] may be 1. 5
or below, in which case obtainable conjugated fibers still have
excellent crimps properties. Even when an absolute value of
AMw/Mn is in the range of 0.3 to 1.0, crimps are developed.
The ratio Mw/Mn is usually known as the molecular weight
10 distribution (polydispersity degree) indicating the degree of
molecular weight distribution of a polymer. If AMw/Mn is
excessively large, flow properties and crystallization
behaviors greatly differ between one material (the portion (a))
and another material (the portion (b)), possibly resulting in
15 deteriorated fiber spinnability. In the present invention,
the numerical ranges indicated with "to" include the numbers
at the sides of the "to".
[0045]
OMz/Mw and AMw/Mn are obtained by determining, by GPC
20 analysis, the ratios Mz/Mw and the ratios Mw/Mn each for the
propylene polymer (A) and the propylene/u-olefin random
copolymer (B) that form the portion (a) and the portion (b)
respectively, and calculating an absolute value of the
difference thereof.
SF-2365
[0046]
19
In the present invention, GPC. analysis is performed under
the following conditions.
[0047]
(1) 30 mg of the propylene polymer is completely dissolved
in 20 mL of o®dichlorobenzene at 145°C.
[0048]
(2) The solution is filtered through a sintered filter
having a pore size of 1.0 Eim to provide a sample.
10 [0049]
(3) The sample is analyzed by GPC and the average molecular
weight and molecular weight distribution curve are obtained
with reference to polystyrene (PS) standard.
[0050]
15 The measurement apparatus and conditions are as follows.
[0051]
Measurement apparatus. Gel permeation chromatograph
Allianc-e GPC 2000 (manufactured by Waters)
Analyzer: Data processing software Empower 2
20 (manufactured by Waters)
Columns: Two TSK gel GMH6-HT columns -I- two TSK gel GM1I6-HTL
columns (each 7,5 mm in inner diameter x 30 cm, manufactured
by TOSOH CORPORATION)
Column temperature: 140°C
SF--2365
20
Mobile phase: o--,dichlorobenzerie (containing 0.025% of
butylated hydroxytoluene (BHT))
Detector: Differential refractometer
Flow rate: 1 mL/min
5 Sample concentration: 30 mg/20 mL
Injection amount: 500 μL
Sampling time intervals: 1 sec
Column calibration: Monodisperse polystyrenes
(manufactured by TOSOH CORPORATION)
10 Molecular weight conversion: PS conversion/standard
conversion methods
KOTm)
The difference between the melting point of the propylene
polymer (A) for forming the portion (a) of the present invention
15 and the melting point of the propylene/(Y-olefin random
copolymer (B) for forming the portion (b) of the present
invention exceeds 10°C. The difference is preferably in the
range of 12 to 40°C.
[0052]
20 The value of ATm is obtained by determining the melting
points of the propylene polymer (A) and the propylene/a-olefin
random copolymer (B) that are raw materials for the portion
(a) and the portion (b) respectively and calculating an absolute
value of the difference thereof.
SF-2365
[0053]
21
In the present invention, the melting point is measured
as follows.
[0054]
5 (1) The propylene polymer is set in a pan of a differential
scanning calorimeter (DSC) manufactured by PerkinElmer Co,,
Ltd. The pan is heated from 30 to 200°C at a rate of 10°C/min,
held at 200°C for 10 minutes, and cooled to 30°C at a rate of
10°C/min.
10 [0055]
(2) The pan is heated again from 30 to 200°C at a rate
of 10°C/min, and the melting point is obtained from the peak
recorded during this second heating process.
[0056]
15 (MFR ratio)
The ratio of the MFR of the propylene polymer (A) for
forming the portion (a) of the present invention to the MFR
of the propylene/a-olefin random copolymer (B) for forming the
portion (b) of the present invention (hereinafter, also the
20 MFR ratio), which is not particularly limited, is usually in
the range of 0 0 8 to 1 a 2 . In the present invention, conjugated
fibers having excellent crimp properties are obtained even when
the MFR ratio is within the above range. The MFR of the
propylene polymer (A) and the propylene/a--olefin random
SF--2365
22
copolymer (B) according to the present invention are preferably
in the range of 20 to 100 g/10 min.
[0057]
In the present invention, MFR is determined at 230°C under
5 2160 g load in accordance with ASTM D 1238.
[0058]
(Crimp number and other properties of crimped conjugated fibers)
The number of crimps of the crimped conjugated fibers of
the present invention is determined in accordance with JIS L
10 1015. The number of crimps is usually 19 or more, preferably
20 to 50, per 25 mm of the fiber. If the number of crimps is
less than the lower limit, the crimped fibers may not achieve
characteristics such as bulkiness by the three dimensional
helical structure. If the number of crimps is larger than the
15 upper limit, uniform distribution of the fibers is difficult
and an obtainable non woven fabric may have deteriorated
texture or mechanical strength.
[0059]
The diameter of the crimped conjugated fibers of the
20 present invention is not particularly limited, but is usually
in the range of 0.5 to 5 denier, preferably 005 to 3 denier.
This fineness ensures excellent spinnability and crimp
properties, and mechanical strength of an obtainable non-woven
fabric.
SF-2365
[0060]
23
Fig. 1 is a perspective view showing an embodiment of the
crimped conjugated fibers according to the present invention.
In the figure, 10 indicates the portion (a) and 20 indicates
the portion (b)a
[0061]
The crimped conjugated fibers of the present invention
have a crimpable cross-sectional configuration wherein a cross
section of the fibers comprises at least two portions: the
10 portion (a) and the portion (b)a In the cross section of the
crimped conjugated fibers, the proportions of the portion (a)
and the portion (b) are such that the mass ratio [(a):(b)] is
in the range of 10:90 to 60:40, preferably 10:90 to 50:50, more
preferably 20:80 to 40:60.
15 [0062]
The crimped conjugated fibers may have any shapes without
limitation as long as they have a crimpable cross-sectional
configuration. Exemplary shapes include side-by-side
(parallel) crimped conjugated fibers in which the portion (a)
20 and the portion (b) are arranged adjacent to each other, and
core-sheath crimped conjugated fibers in which the portion (a)
forms a core (a') and the portion (b) forms a sheath (b')e
[0063]
Figs. 3 to 8 show other cross--sectional views of crimped
SF-2365
24
conjugated fibers according to the present invention. In the
figures, 10 indicates the portion (a) and 20 indicates the
portion (b)o
[0064]
5 The term "core-sheath crimped conjugated fibers" refers
to fibers which have a core and a sheath and are crimped. The
core (a') is arranged with at least part thereof being
surrounded by a polymer different from the core (a') in the
fiber cross section and extends along the length of the fiber.
10 The sheath (b') is arranged so as to surround at least part
of the core (a') in the fiber cross section and extends along
the length of the fiber e In an eccentric core-sheath crimped
conjugated fiber, the core (a' ) and the sheath (b' ) are located
non-concentrically in the cross section of the fiber. The
15 eccentric core-sheath crimped conjugated fibers include an
exposed type in which the side of the core (a') is exposed,
and a non-exposed type in which the core (a' ) is fully occluded.
In the present invention, eccentric core-sheath crimped
conjugated fibers of the exposed type are preferred because
20 they show excellent crimp properties. The cross sectional
joint between the core (a' ) and the sheath (b' ) may be straight
or curved. The core'may be circular, elliptical or square in
cross section.
[0065]
SF--2365
25
The crimped conjugated fibers of the present invention
may be staple fibers or continuous fibers. Continuous fibers
are preferable because an obtainable non woven fabric does not
have loss of the crimped conjugated fibers and excellent fuzzing
5 resistance is achieved.
[0066]
(Non-woven fabric)
The non-woven fabric of the present invention i, made of
the above crimped conjugated fibers. The non woven fabric
10 usually has a basis weight (mass per unit area of the non-woven
fabric) of 3 to 100 g/m2, preferably 7 to 60 g/m2.
[006'7]
The non-woven fabric of the present invention preferably
comprises the crimped conjugated fibers that are continuous
15 fibers. In view of productivity, the non-woven fabric is
particularly preferably spunbonded non-woven fabric of such
fibers,
[0068]
In the non-woven fabric of the present invention,
20 preferable that the crimped conjugated fibers are thermally
fusion bonded by embossing, whereby the fibers maintain
stability and strength.
[0069]
(Non-woven fabric laminate)
SF- 2365
26
The non-woven fabric comprising the crimped conjugated
fibers of the present invention (hereinafter, also referred
to as the crimped conjugated fiber non-woven fabric to be
distinguished from a usual non-woven fabric) may be laminated
with various layers depending on use.
[0070]
In detail, the crimped conjugated fiber non-woven fabric
may be laminated with knitted fabrics, woven fabrics, non-woven
fabrics, films and the like. The crimped conjugated fiber
10 non-woven fabric may be laminated. (joined) with such other
layers by known methods including thermal fusion bonding
methods such as heat embossing and ultrasonic fusion bonding,
mechanical entanglement methods such as needle punching and
water jetting, adhesive bonding methods with hot melt adhesives
15 or urethane adhesives, and extrusion laminating methods.
[0071]
The non woven fabrics laminated with the crimped
conjugated fiber non-woven fabric include various known
non-woven fabrics such as spunbonded non-woven fabrics,
20 meltblown non woven fabrics, wet non-woven fabrics, dry
non-woven fabrics, dry pulp non-woven fabrics, flash-:pun
non-woven fabrics and spread-fiber non-woven fabrics.
[0072]
The materials for such non-woven fabrics may be
SF---2365
27
conventional thermoplastic resins. Examples thereof include
homopolymers and copolymers of a -olefins such as ethylene,
propylene, l-butene, 1-hexen.e, 4-methyl-yl-pentene and
1-octene, namely, polyolefins such as high-pressure
5 low-density polyethylenes, linear low-density polyethylenes
(LLDPE), high-density polyethylenes, polypropylenes,
polypropylene random copolymers, poly-1-butene,
poly-4,-methyl-l pentene, ethylene/propylene random
copolymers, ethylene/l-butene random copolymers and
10 propylene/l-butene random copolymers; polyesters such as
polyethylene terephthalate, polybutylene terephthalate and
polyethylene naphthalate; polyamides such as nylon-6, nylon-66
and polymethaxyleneadipamide; polyvinyl chloride, polyamides,
ethylene/vinyl acetate copolymers, polyacrylonitriles,
15 polycarbonates, polystyrenes, ionomers and thermoplastic
polyurethanes; and mixtures of these resins. Of th se,
high-pressure low-density polyethylenes, linear low-density
polyethylenes (LLDPE), high-density polyethylenes,
polypropylenes, polypropylene random copolymers, polyethylene
20 terephthalate and polyamides are preferred.
[0073]
In a preferred embodiment of the present invention, the
crimped conjugated fiber non-woven fabric is laminated with
a spunbonded nonwoven fabric made of an ultrafine fiber
SF--2365
28
(fineness: 0.8 to 2.5 denier, more preferably 0.8 to 1.5 denier)
and/or a meltblown non woven fabric. Specific examples
include:
two-=layer laminates such as spunbonded non-woven fabric
5 (ultrafine fiber)/crimped conjugated fiber non-woven fabric,
and meltblown nonwoven fabric/crimped conjugated fiber
nonwoven fabric;
three-layer laminates such as spunbonded non---woven
fabric (ultrafine fiber)/crimped conjugated fiber non woven
10 fabric/spunbonded non woven fabric (ultrafine fiber),
spunbonded non woven fabric (ultrafine fiber)/crimped
conjugated fiber nonwoven fabric/meltblown nonwoven fabric,
and spunbonded non-woven fabric (ultrafine fiber)/meltblown
non woven fabric/crimped conjugated fiber nonwoven fabric;
15 and
laminates hai.ving four or more layers such as )nnbonded
nonwoven fabric (ultrafine fiber)/crimped conjugated fiber
non -woven fabric/meltblown non woven fabric/spunbonded
nonwoven fabric (ultrafine fiber) , and spunbonded non-woven
20 fabric (ultrafine fiber)/crimped conjugated fiber nonwoven
fabric/meltblown non woven fabric/crimped conjugated F=iber
non woven fabric/spunbonded non-woven fabric (ultrafine
fiber).
The basis weight of each nonwoven fabric layer in the
S2365
29
laminate is preferably in the range of 2 to 25 g/m2. The
spunbonded non-=woven fabric made of the ultrafine fibers
described above may be obtained by controlling (selecting)
spunbonding conditions. The nonwoven fabric laminates
5 benefit from the bulkiness and softness of the crimped
conjugated fiber non-woven fabric of the present invention and
also achieve excellent surface smoothness and improved water
resistance.
[0074]
10 The films laminated with the crimped conjugated fiber
non woven fabric of the present invention are preferably
breathable (moisture permeable) films in order to take
advantage of the breathability of the crimped conjugated fiber
nonwoven fabric. Various known breathable films may be used,
15 with examples including films of moisture permeable
thermoplastic elastomers such as polyurethane elaslomers,
polyester elastomers and polyamide elastomers; and porous
films obtained by stretching thermoplastic resin films
containing inorganic or organic fine particles to create pores
20 in the films. Preferred thermoplastic resins for the porous
films are high-pressure low-density polyethylenes, linear
low density polyethylenes (LLDPE) , high-density polyethylenes,
polypropylenes, polypropylene random copolymers and
compositions containing these polyolefins.
SF- 2 3 65
[0075]
30
The laminates with the breathable films are cloth-like
composite materials having bulkiness and softness of the
crimped conjugated fiber nonwoven fabric of the present
5 invention and very high water resistance.
[0076]
Process for producing non-woven fabric)
The non-woven fabric of the present invention may be
produced by any known process while still achieving the
10 advantageous effects of the present invention. A preferred
production process is described below.
[0077]
The non woven fabric of the present invention is
preferably produced through..
15 (1) a step in which the propylene polymer (A) and the
propylene/a-olef_Ln random copolymer (B) that are raw materials
for the portion (a) and the portion (b) respectively are
separately molten in at least two extruders and are spun from
a composite spinning nozzle into conjugated fibers;
20 (2) a step in which the conjugated fibers are quenched,
then drawn and attenuated to develop crimps, and the ci_imped
conjugated fibers are deposited on a collecting belt to a
desired thickness; and
(3) a step in which the deposited conjugated fibers are
S1 ---2365
entangled.
31.
This process is called a spunbonding process.
[0078]
Step (1)
5 In this step, known extruders and composite spinning
nozzles may be used. The melting temperature is not
particularly limited but is preferably higher by approximately
50°C than the melting point of the propylene polymer. The
spinnability in this step is evaluated based on the presence
10 or absence of fiber breakage within a predetermined time.
[0079]
Step (2)
In this step, the molten fibers are preferably quenched
by blowing air. The air temperature may be 10 to 40°C. The
15 quenched fibers may be controlled to a desired diameter by the
tensile force of blowing air. The quenched fibers develop
crimps. The collecting belt may be conventional but is
prefera-bly one that is capable of conveying the crimped fibers,
for example a belt conveyer.
20 [0080]
Step (3)
The entanglement treatment in this step may be performed
for example by applying water jet or ultrasonic wave to the
deposited crimped conjugated fibers (hereinafter, also
2365
32
referred to simply as "fibers") or by thermally fusion bonding
the fibers by embossing or hot air.
[0081]
In the present invention, it is particularly preferable
5 that the crimped conjugated fibers are embossed, whereby a
non-woven fabric having excellent strength is obtained. The
embossing is carried out under conditions such that the embossed
area percentage is 5 to 30%. The embossed area percentage
represents the total area of emboss relative to the total area
10 of the non-woven fabric. Reducing the embossed area provides
a non woven fabric with excellent softness. Increasing the
embossed area gives a non woven fabric having excellent
rigidity and mechanical strength.
[0082]
15 The embossing temperature is preferably controlled
depending on the melting points of the portions (a) tend (b)
For the propylene polymer, the embossing temperature is usually
in the range of 100 to 150°C.
20
[0083
The present invention will be described in greater detail
by examples hereinbelow without limiting the scope of the
invention.
SF-- 2 3 6 5
[0084]
3 3
The propylene polymers used in Examples and Comparative
Examples of the present invention are listed below.
(1) Propylene polymer (A) [propylene homopolymer]
5 (1-1) NOVATEC PP SA06A manufactured by Japan Polypropylene
Corporation.
(1°2) Prime Polypro S119 manufactured by Prime Polymer Co.,
Ltd.
(1-3) Prime Polypro HS135 manufactured by Prime Polymer Co.,
10 Ltd.
(2) Propylene/a-olefin random copolymer (B)
[Propylene/ethylene random copolymer]
(2°1) Prime Polypro S229R manufactured by Prime Polymer Co.,
Ltd o ; melting point: 143'C, ethylene content: 3 0 0 wt o (4 0 5 mot o )
15 (2®2) A prototype manufactured by Prime Polymer Co., Ltd.
(copolymer obtained by thermally degrading a
propylene/ethylene random copolymer having an MFR of 7 with
a peroxide in order for the copolymer to have an MFR of 60)
melting point: 146°C, ethylene content: 2.3 wt% (3m3 mol%)
20 (Sample 8)
(2-3) ,A prototype manufactured by Prime Polymer Co., Ltd.
(copolymer obtained by thermally degrading a
propylene/ethylene random copolymer having an MFR of 7 with
a peroxide in order for the copolymer to have an MFR of 61);
SF--2365
34
melting point: 143°C, ethylene content: 2.8 wt% (401 moi%)
(Sample 9)
(2-4) A prototype manufactured by Prime Polymer Co., Ltd.
(copolymer obtained by thermally degrading a
5 propylene/ethylene random copolymer having an MFR of 7 with
a peroxide in order for the copolymer to have an MFR of 55);
melting point: 140°C, ethylene content: 302 wt% (4a6 mol%)
(Sample 10)
(2®5) A prototype manufactured by Prime Polymer Co., Ltd.
10 (copolymer obtained by thermally degrading a
propylene/ethylene random copolymer having an MFR of 305
polymerized by using a metallocene catalyst, with a peroxide
in order for the copolymer to have an MFR of 40) ; melting point:
128°C, ethylene content: 3.6 wt% (503 mol%) (Sample 11)
15 [0085]
[Example 1]
A propylene polymer (A) for forming a core was SA06Ao A
propyle-n.e/a-olefin random copolymer (B) for forming a sheath
was S229R. The polymers were melt spun by spunbonding method.
20 [0086]
Single-screw extruders were used and the propylene
polymer (A) and the"propylene/a-olefin random copolymer (B)
were molten at 200°C.
[0087]
SF--2 365
35
The polymers were spun into continuous fibers in which
the mass ratio of a core hl to a sheath h2 was 20:80. The
fineness was 2.3 denier.
[0088]
5 The resultant eccentric core-=sheath crimped conjugated
continuous fibers that were melt-spun were deposited on a
collecting surface to form a nonwoven fabric. The non-woven
fabric was embossed at 125°C, The embossed area percentage was
18%. The embossed nonwoven fabric had a basis weight of 25
10
g/m a o The resultant crimped conjugated continuous fibers and
non-woven fabric were evaluated for properties by the following
methods.
[0089]
(1) Number of crimps
15 The number of crimps was measured in accordance with JIS
L 1015.
The crimp properties were evaluated AA when the number
of crimps was 20 or more per 25 mm, BB when the number of crimps
was from 5 to less than 20 per 25 mm, and CC when the number
20 of crimps was from 0 to less than 5 per 25 mm.
[0090]
(2) 2% tensile elongation strength
A test piece 600 mm in MD x 100 mm in CD was prepared.
The test piece was wound around an iron rod 10 mm in
SF'-2365
36
diameter and 700 mm in length arid was formed into a tubular
sample having a length of 600 mm. The sample was tensile tested
with a chuck distance of 500 mm at a tension rate of 500 mm/min,
and the load at 105% elongation and at 205% elongation was
5 measured. The 2% tensile elongation strength was obtained from
the following equation:
2% tensile elongation strength (N/cm) = (load at 2.5%
elongation W load at 1.5% elongation)/10 cm x 100
A nonwoven fabric having a higher value of 2% tensile
10 elongation strength were evaluated to have higher rigidity,
and a non-woven fabric having a lower value were evaluated to
have higher softness.
[0091]
(3) Softness
15 The softness was evaluated by a cantilever method in
accordance with JIS L 1096. In detail, the evaluation was made
as follows.
I j A 2 x 15 cm test piece 30 was prepared and was placed
on a test table 40 as illustrated in Fig. 2.
20 2) The test piece 30 was slowly pushed in the direction
of arrow until it bent, and a distance 50 was measured.
3) The above testing was carried out along each of MD and
CD of the test pieces.
A non-woven fabric having a higher value of this testing
SF---2365
37
was evaluated to have higher rigidity, and a non--woven fabric
having a lower value was evaluated to have higher softness.
[0092]
(4) Thickness
5 Five test pieces (100 mm x 100 mm) were sampled from a
test sample. With respect to each test piece, the thickness
was measured at arbitrary three points with a constant pressure
thickness gauge (manufactured by OZAKI MFG. CO. LTD.,) The
gauge head had a diameter of 16 mm, and the load was 3. 6 g/cm2.
10 The value was read after 30 ± 5 seconds after the gauge head
completely contacted the test piece. The results of the five
test pieces were averaged to determine the thickness. A
non-woven fabric having a higher value of thickness was
evaluated to have higher bulkiness.
15 [0093]
The measurement results are set forth in Table 2.
[0094]
[Exampl-e 2]
Crimped conjugated continuous fibers and a non-woven
20 fabric were obtained in the same manner as in Example 1, except
that the propylene polymer (A) used in Example 1 was changed
to a composition (blend) of propylene homopolymers S119 /HS135
96/4 (mass ratio) o The measurement results for the crimped
conjugated continuous fibers and the nonwoven fabric are set
SF--2365
3 ;
forth in Table 1.
[0095]
[Example 3]
Crimped conjugated continuous fibers and a non-woven
5 fabric were obtained in the same manner as in Example 2, except
that the mass ratio of the propylene polymer (A) to the
propylene/a-olefin random copolymer (B) used in Example 2 was
500500 The measurement results for the crimped conjugated
continuous fibers and the non woven fabric are set forth in
10 Table 1.
[0096]
[Example 4]
Crimped conjugated continuous fibers and a nonwoven
fabric were obtained in the same manner as in Example 1, except
15 that using the propylene polymer (A) and the propylene/a-olefin
random copolymer (B) that were polymers as indicated In Table
1, the mass ratio of a core h3 to a sheath h4 in the continuous
fibers was 30:70. The measurement results for the crimped
conjugated continuous fibers and the nonwoven fabric are set
20 forth in Table 1.
[0097],
[Example 5]
Crimped conjugated continuous fibers were obtained in
such a manner that the propylene polymer (A) was S119, the
S1. ---2365
39
propylene /n olefin random copolymer ( B) was a polymer as
indicated i n Table 1 , and the mass ratio of a core h3 to a sheath
h4 in the continuous fibers was 20.80. The measurement results
for the crimped conjugated continuous fibers are set forth in
5 Table 1.
[0098]
[Comparative Example 1]
Conjugated continuous fibers and a non-woven fabric were
obtained in the same manner as in Example 1, except that the
10 propylene polymer ( A) used for the core in Example 1 was changed
to S119 and this was used for the core. The measurement results
for the conjugated continuous fibers and the non-woven fabric
are set forth in Table 1.
[0099]
15 [Comparative Example 2]
Conjugated continuous fibers and a nonwoven fabric were
obtained in the same manner as in Example 3, except that the
propylene polymer (A) and the propylene / a-olefin random
copolymer ( B) used for the core and the sheath in Example 3
20 were both changed to S229R and this was used for the core and
the sheath, and the embossing temperature was changed to 120°C.
The conjugated continuous fibers d i d not develop crimps. The
measurement results for the conjugated continuous fibers and
the non--woven fabric are set forth in Table 1
SL'--2365
40
[0100]
[Comparative Example 3]
Conjugated continuous fibers were obtained in the same
manner as in Example 3, except that the propylene/a-olefin
5 random copolymer (B) used for the sheath in Example 5 was changed
to Sample 8 and this was used for the sheath. The conjugated
continuous fibers did not develop crimps. The measurement
results for the conjugated continuous fibers are set forth in
Table 1.
10 [0101]
[Comparative Example 4]
Conjugated continuous fibers were obtained in the same
manner as in Example 3, except that the propylene/u-olefin
random copolymer (B) used for the sheath in Example 5 was changed
15 to Sample 9 and this was used for the sheath. The conjugated
continuous fibers did not develop crimps. The measurement
results for the conjugated continuous fibers are set forth in
Table 1--e
[0102]
20 [Comparative Example r
Conjugated continuous fibers and a non-woven fabrics were
obtained in the same manner as in Example 3, except that the
propylene/(Y-olefin random copolymer (B) used for the sheath
in Example 5 was changed to Sample 10 and this was used for
SF---2365
the sheath, and the embossing temperature was changed to 122°Cu
The conjugated continuous fibers did not develop crimps. The
measurement results for the conjugated continuous fibers are
set forth in Table 1.
[0103]
[Table 1]
S F-2365
Table 1
42
Ex. 1 Ex. 2 Ex_ 3 Ex. 4 Ex. 5
Propylene polymer (A): type of polymers SA06A
5119/HS135
=96/4
5119/HS135
=96/4
SA06A 5119
MFR g/10 min 59 58 58 59 63
Core
Mw/Mn - 3.01 3.30 3.30 3.01 3.28
Mz/Mw - 2.53 2.49 2.49 2.53 2.24
Melting point C 161 158 158 161 158
Propylene/a-olefin random polymer (B):
type of polymers
52298 S229R S229R S229R Sample 11
h h
MFR g/10 min 63 63 63 63 40
S eat
Mw/Mn - 2.73 2.73 2.73 2.73 2.12
Mz/Mw - 2.19 2.19 2.19 2.19 1.86
Melting point °C 143 143 143 143 128
Core:sheath ratio 20:80 20:80 50:50 30:70 20:80
tMz/Mw - 0.35 0.30 0.30 0.35 0.38
AMw/Mn - 0.27 0.27 0.27 0.27 1.16
MFR ratio - 0.94 0.92 0.92 0.94 1.58
LTm °C 18 15 15 18 30
Melting temperature °C 200 200 200 200 200
Embossed area percentage = 18 18 18 18 -
Embossing Linear pressure N/mm 60 60 60 60 -
conditions Emboss roll temperature C 125 125 125 125 -
Crown roll temperature °C 125 125 125 125
Basis weight g/m2 24.7 24.6 24.8 25.1 -
Thickness gin 310 300 290 320 -
Pro erties Porosity % 91.2 p 91.0 90.6 91.4
2% tensile elongation strength
(MD) N/cm 43 48 52 38 -
Softness in MD (distance) j mm 43 44 48 42 -
Crimp properties AA AA AA AA LA
Number of crimps
crimps/25
mm
28.0 27.0 25.0 30.0 28.0
Spinnability Sufficient Sufficient Sufficient Sufficient Sufficient
SF-2365
Table 1 (continued)
43
Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Comp. Ex. 4 Comp. Ex. 5
Propylene polymer (A): type of polymers S119 S229R S119 5119 5119
MFR g/10 min 63 63 63 63 63
Core Mw/Mn - 3.28 2.73 3.28 3.28 3.28
Mz/Mw - 2.24 2.19 2.24 2.24 2.24
Melting point °C 158 143 158 158 158
Propylene/a-olefin random polymer (B)
t ype of polymers
F S229R S229R Sample 8 Sample 9 Sample 10
MFR g/10 min 63 63 59 61 55
Sheath
Mw/Mn - 2.73 2.73 3.44 3.20 3.20
Mz/Mw - 2.19 2.19 2.77 2.65 2.71
Melting point °C 143 143 146 143 140 {
Core:sheath ratio 20:80 20:80 20:80 20:80 20:80
LMz/Mw - 0.05 0.00 -0.53 -0.41 -0.47
LMw/Mn - 0.55 0.00 -0.16 0.08 0.08
MFR ratio - 1.00 1.00 1.07 1.03 1.15
4Tm °C 15 0 12 15 18
Melting temperature °C 200 200 200 200 200
Embossed area percentage % 18 18 - - 18
Embossing Linear pressure N/mm 60 60 - - 60
conditions Emboss roll tEperature °C 125 120 - - 122
Crown roll temperature °C 125 120 - - 122
Basis weight g/m2 24.8 24.5 - - 24.2
Thickness 282 252 - - 291
P ti
Porosity o- 90.3 89.3 - - 90.9
roper es
2% tensile elongation strength
(MD)
N/cm 66 64 82
Softness in MD (distance) mm 52 54 - - 53
Crimp properties BB CC CC CC CC
Number of crimps
crimps/25
mm
18.0 0.0 0 0 0
Spinnability Sufficient Sufficient Sufficient Sufficient Sufficient
SF--2365
[0104]
44
T's! PPL'ICAB ` IVY
The nonwoven fabric according to the present invention
has excellent properties such as spinnability, strength,
softness and water resistance and is useful in side gathers,
back sheets, top sheets and waist parts of disposable diapers
or sanitary napkins.
REFERENCE SIGNS LIST
10 [0105]
10 °°° portion (a)
20 °°° portion (b)
30 °°° test piece
40 °°° test table
15 50 °°° distance
SF--2365
4 5

CLAIMS
1. A crimped conjugated fiber having a crimpable
5 cross-sectional configuration wherein a cross section of the
fiber comprises at least two portions. a portion (a) and a
portion (b),
the mass ratio of the portion (a) to the portion (b)
[(a):(b)] is in the range of 10.90 to 60.40,
10 the portion (a) comprises a propylene polymer (A) and the
portion (b) comprises a propylene/a-olefin random copolymer
(B),
the propylene polymer (A) has Mz/Mw (A) and the
propylene/a-olefin random copolymer (B) has Mz/Mw(B) wherein
15 the difference thereof [ Mz/Mw ( A) - Mz/Mw (B) . AMz/Mw] is in the
range of 0010 to 2.2, and
the propylene polymer (A) has a melting point [Tm (A) ] and
the propylene/a-olefin random copolymer (B) has a melting point
[Tm(B)] wherein the difference thereof exceeds 10°C.
20
2. The crimped conjugated fiber according to claim 1,
wherein the crimped conjugated fiber has an eccentric
core-=sheath configuration in which the portion (a) is a core
(a') and the portion (b) is a sheath (b').
SF'-2365
46
3. The crimped conjugated fiber according to claim 1
or 2, wherein the propylene polymer (A) is a propylene
homopolymer.
4. A non-woven fabric comprising the crimped
conjugated fiber described in any one of claims 1 to 3.
5. The non-woven fabric according to claim 4, wherein
10 the crimped conjugated fiber is thermally fusion bonded by
embossing.