U.S. patent application number 14/775222 was filed with the patent office on 2016-02-04 for nonwoven fabric and fiber product.
This patent application is currently assigned to IDEMITSU KOSAN CO., LTD.. The applicant listed for this patent is IDEMITSU KOSAN CO., LTD.. Invention is credited to Yohei KOORI, Yutaka MINAMI, Tomoaki TAKEBE.
Application Number | 20160032504 14/775222 |
Document ID | / |
Family ID | 51536970 |
Filed Date | 2016-02-04 |
United States Patent
Application |
20160032504 |
Kind Code |
A1 |
KOORI; Yohei ; et
al. |
February 4, 2016 |
NONWOVEN FABRIC AND FIBER PRODUCT
Abstract
Provided is a spunbonded nonwoven fabric comprising a
core-sheath composite fiber having a core part composed of a core
component containing a propylene-based resin (A) satisfying the
following (a) to (e) and a sheath part composed of a sheath
component containing an ethylene-based resin. (a) [mmmm]=20 to 60
mol %, (b) [mm].times.[rr]/[mr].sup.2.ltoreq.2.0, (c) weight
average molecular weight (Mw)=10,000 to 200,000, (d) molecular
weight distribution (Mw/Mn)<4.0, and (e) a melting point (Tm-D),
as defined as a peak top of a peak observed on the highest
temperature side of a melting endothermic curve which is obtained
by holding under a nitrogen atmosphere at -10.degree. C. for 5
minutes and then increasing the temperature at a rate of 10.degree.
C./min with a differential scanning calorimeter (DSC), is from 0 to
120.degree. C.
Inventors: |
KOORI; Yohei; (Ichihara-shi,
JP) ; TAKEBE; Tomoaki; (Chiba-shi, JP) ;
MINAMI; Yutaka; (Chiba-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IDEMITSU KOSAN CO., LTD. |
Chiyoda-ku, Tokyo |
|
JP |
|
|
Assignee: |
IDEMITSU KOSAN CO., LTD.
Chiyoda-ku, Tokyo
JP
|
Family ID: |
51536970 |
Appl. No.: |
14/775222 |
Filed: |
March 14, 2014 |
PCT Filed: |
March 14, 2014 |
PCT NO: |
PCT/JP2014/056979 |
371 Date: |
September 11, 2015 |
Current U.S.
Class: |
442/364 |
Current CPC
Class: |
C08L 23/14 20130101;
D10B 2321/021 20130101; D04H 1/4382 20130101; D04H 1/724 20130101;
D04H 3/033 20130101; D01F 8/06 20130101; D10B 2501/00 20130101;
D04H 3/147 20130101; C08L 2203/12 20130101; D04H 3/007 20130101;
D04H 1/4291 20130101; D10B 2509/02 20130101; C08L 23/14 20130101;
C08L 23/14 20130101; C08L 2205/025 20130101; D10B 2321/022
20130101 |
International
Class: |
D04H 1/4291 20060101
D04H001/4291; D04H 3/007 20060101 D04H003/007; D04H 1/724 20060101
D04H001/724; D04H 3/033 20060101 D04H003/033; D04H 3/147 20060101
D04H003/147; D04H 1/4382 20060101 D04H001/4382 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 15, 2013 |
JP |
2013-054291 |
Claims
1. A spunbonded nonwoven fabric comprising a core-sheath composite
fiber having a core part composed of a core component containing a
propylene-based resin (A) satisfying the following (a) to (e) and a
sheath part composed of a sheath component containing an
ethylene-based resin: (a) [mmmm]=20 to 60 mol, (b)
[mm].times.[rr]/[mr].sup.2.ltoreq.2.0, (c) weight average molecular
weight (Mw)=10,000 to 200,000, (d) molecular weight distribution
(Mw/Mn)<4.0, and (e) a melting point (Tm-D), as defined as a
peak top of a peak observed on the highest temperature side of a
melting endothermic curve which is obtained by holding under a
nitrogen atmosphere at -10.degree. C. for 5 minutes and then
increasing the temperature at a rate of 10.degree. C./min with a
differential scanning calorimeter (DSC), is from 0 to 120.degree.
C.
2. The spunbonded nonwoven fabric according to claim 1, wherein a
content of the propylene-based resin (A) in the core component is 1
to 50% by mass.
3. The spunbonded nonwoven fabric according to claim 1, wherein the
core component further contains a propylene-based resin (B) in
which a melting point (Tm-D), as defined as a peak top of a peak
observed on the highest temperature side of a melting endothermic
curve which is obtained by holding under a nitrogen atmosphere at
-10.degree. C. for 5 minutes and then increasing the temperature at
a rate of 10.degree. C./min with a differential scanning
calorimeter (DSC), is higher than 120.degree. C.
4. The spunbonded nonwoven fabric according to claim 3, wherein a
content of the propylene-based resin (B) in the core component is
50 to 99% by mass.
5. The spunbonded nonwoven fabric according to claim 1, wherein a
content of the ethylene-based resin in the sheath component is 50
to 100% by mass.
6. The spunbonded nonwoven fabric according to claim 1, wherein the
propylene-based resin (A) satisfies the following (f) and (g): (f)
rrrr/(1-mmmm).ltoreq.0.1, and (g) [rmrm]>2.5 mol %.
7. The spunbonded nonwoven fabric according to claim 1, wherein a
total content of the propylene-based resin (A) in the core-sheath
composite fiber as calculated according to the following expression
is 0.5 to 47.5% by mass: [Total content of propylene-based resin
(A)]=Wc.times.Xc/100 Wc: Mass fraction of the core part Xc: Mass
fraction of the propylene-based resin (A) in the core component
constituting the core part.
8. The spunbonded nonwoven fabric according to claim 1, wherein the
propylene-based resin (A) is a propylene homopolymer or a copolymer
in which a copolymerization ratio of a propylene unit is 90 mol %
or more.
9. The spunbonded nonwoven fabric according to claim 3, wherein the
propylene-based resin (B) is a propylene homopolymer or a copolymer
in which a copolymerization ratio of a propylene unit is 50 mol %
or more.
10. The spunbonded nonwoven fabric according to claim 1, wherein
the ethylene-based resin is an ethylene homopolymer or a copolymer
in which a copolymerization ratio of an ethylene unit is more than
50 mol %.
11. A multilayered nonwoven fabric comprising a laminate of at
least two or more layers of nonwoven fabric, at least one layer of
the nonwoven fabric constituting an outer layer of the multilayered
nonwoven fabric being composed of the spunbonded nonwoven fabric
according to claim 1.
12. A fiber product using the spunbonded nonwoven fabric according
to claim 1.
13. A fiber product using the multilayered nonwoven fabric
according to claim 11.
14. The spunbonded nonwoven fabric according to claim 2, wherein
the core component further contains a propylene-based resin (B) in
which a melting point (Tm-D), as defined as a peak top of a peak
observed on the highest temperature side of a melting endothermic
curve which is obtained by holding under a nitrogen atmosphere at
-10.degree. C. for 5 minutes and then increasing the temperature at
a rate of 10.degree. C./min with a differential scanning
calorimeter (DSC), is higher than 120.degree. C.
15. The spunbonded nonwoven fabric according to claim 2, wherein a
total content of the propylene-based resin (A) in the core-sheath
composite fiber as calculated according to the following expression
is 0.5 to 47.5% by mass: [Total content of propylene-based resin
(A)]=Wc.times.Xc/100 Wc: Mass fraction of the core part Xc: Mass
fraction of the propylene-based resin (A) in the core component
constituting the core part.
16. The spunbonded nonwoven fabric according to claim 3, wherein a
total content of the propylene-based resin (A) in the core-sheath
composite fiber as calculated according to the following expression
is 0.5 to 47.5% by mass: [Total content of propylene-based resin
(A)]=Wc.times.Xc/100 Wc: Mass fraction of the core part Xc: Mass
fraction of the propylene-based resin (A) in the core component
constituting the core part.
17. The spunbonded nonwoven fabric according to claim 4, wherein a
total content of the propylene-based resin (A) in the core-sheath
composite fiber as calculated according to the following expression
is 0.5 to 47.5% by mass: [Total content of propylene-based resin
(A)]=Wc.times.Xc/100 Wc: Mass fraction of the core part Xc: Mass
fraction of the propylene-based resin (A) in the core component
constituting the core part.
18. The spunbonded nonwoven fabric according to claim 5, wherein a
total content of the propylene-based resin (A) in the core-sheath
composite fiber as calculated according to the following expression
is 0.5 to 47.5% by mass: [Total content of propylene-based resin
(A)]=Wc.times.Xc/100 Wc: Mass fraction of the core part Xc: Mass
fraction of the propylene-based resin (A) in the core component
constituting the core part.
19. The spunbonded nonwoven fabric according to claim 6, wherein a
total content of the propylene-based resin (A) in the core-sheath
composite fiber as calculated according to the following expression
is 0.5 to 47.5% by mass: [Total content of propylene-based resin
(A)]=Wc.times.Xc/100 Wc: Mass fraction of the core part Xc: Mass
fraction of the propylene-based resin (A) in the core component
constituting the core part.
Description
TECHNICAL FIELD
[0001] The present invention relates to a spunbonded nonwoven
fabric composed of a core-sheath composite fiber.
BACKGROUND ART
[0002] In recent years, polyolefin based fibers and nonwoven
fabrics are used for various applications, such as a disposable
diaper, a sanitary product, a hygienic product, a clothing
material, a bandage, a packaging material, etc. The fibers and
nonwoven fabrics are often used for applications in which they come
into direct contact with the body, and thus, in recent years, a
required performance regarding good wear feeling to the body and
hand touch feeling are being more increased. For this reason, with
respect to the nonwoven fabrics, technological development related
to an improvement of texture for good wear feeling, reduction in
basis weight for weight reduction of products, and the like is
demanded. In order to improve these performances, optimization of a
structure or composition of fibers constituting the nonwoven
fabric, improvement of spinnability, and improvement of flexibility
and high strengthening of the nonwoven fabric are demanded.
[0003] In a nonwoven fabric to be used for members coming into
direct contact with the body, for the purpose of improving its wear
feeling, an improvement in smoothness or softness of the surface is
demanded. At present, examples of means for solving this problem
include a method in which a fiber constituting a nonwoven fabric is
constructed of a core-sheath type composite fiber structure
composed of a core component and a sheath component, and
polypropylene is used for the core component, whereas polyethylene
(e.g., HDPE, LLDPE, etc.) is used for the sheath component. By
using polyethylene for the sheath component, as compared with
fibers composed of only polypropylene, the fiber surface becomes
smooth, and it becomes possible to produce a nonwoven fabric having
a very pleasant texture.
[0004] But, the use of polyethylene for the sheath component
encounters a problem that end breakage occurs frequently on the
spinning line in nonwoven fabric molding, so that spinnability and
moldability are not stable. In addition, the fibers become rigid,
and therefore, an improvement of flexibility of the nonwoven fabric
is demanded, too.
[0005] PTL 1 discloses an elastic nonwoven fabric composed of a
sheath-core type composite fiber in which a composition composed of
a low-crystalline polypropylene and a high-crystalline
polypropylene is used for a sheath component, and a low-crystalline
polypropylene is used for a core component. However, in the fiber
disclosed in the above-cited PTL 1, a weight ratio of the
low-crystalline polypropylene is large, so that end breakage is
easy to occur. Thus, the spinnability and moldability are required
to be improved.
CITATION LIST
Patent Literature
[0006] PTL 1: JP-A-2009-209506
SUMMARY OF INVENTION
Technical Problem
[0007] In view of the foregoing circumstances, the present
invention has been made, and its object is to provide a spunbonded
nonwoven fabric composed of a core-sheath composite fiber, which
exhibits improved spinning stability of the fiber and flexibility
of the nonwoven fabric.
Solution to Problem
[0008] The present inventors made extensive and intensive
investigations. As a result, it has been found that the
above-described object is achieved by a spunbonded nonwoven fabric
comprising a core-sheath type composite fiber in which a core part
contains a propylene-based resin, a sheath component contains an
ethylene-based resin, and a specified propylene-based resin is
added to a core component. The present invention has been
accomplished on the basis of such finding.
[0009] Specifically, the present invention provides the following
inventions. [0010] [1] A spunbonded nonwoven fabric comprising a
core-sheath composite fiber having a core part composed of a core
component containing a propylene-based resin (A) satisfying the
following (a) to (e) and a sheath part composed of a sheath
component containing an ethylene-based resin:
[0011] (a) [mmmm]=20 to 60 mol %,
[0012] (b) [mm].times.[rr]/[mr].sup.2.ltoreq.2.0,
[0013] (c) weight average molecular weight (Mw)=10,000 to
200,000,
[0014] (d) molecular weight distribution (Mw/Mn)<4.0, and
[0015] (e) a melting point (Tm-D), as defined as a peak top of a
peak observed on the highest temperature side of a melting
endothermic curve which is obtained by holding under a nitrogen
atmosphere at -10.degree. C. for 5 minutes and then increasing the
temperature at a rate of 10.degree. C./min with a differential
scanning calorimeter (DSC), is from 0 to 120.degree. C. [0016] [2]
The spunbonded nonwoven fabric according to the above item [1],
wherein a content of the propylene-based resin (A) in the core
component is 1 to 50% by mass. [0017] [3] The spunbonded nonwoven
fabric according to the above item [1] or [2], wherein the core
component further contains a propylene-based resin [B] in which a
melting point (Tm-D), as defined as a peak top of a peak observed
on the highest temperature side of a melting endothermic curve
which is obtained by holding under a nitrogen atmosphere at
-10.degree. C. for 5 minutes and then increasing the temperature at
a rate of 10.degree. C./min with a differential scanning
calorimeter (DSC), is higher than 120.degree. C. [0018] [4] The
spunbonded nonwoven fabric according to any one of the above items
[1] to [3], wherein a content of the propylene-based resin (B) in
the core component is 50 to 99% by mass. [0019] [5] The spunbonded
nonwoven fabric according to any one of the above items [1] to [4],
wherein a content of the ethylene-based resin in the sheath
component is 50 to 100% by mass. [0020] [6] The spunbonded nonwoven
fabric according to any one of the above items [1] to [5], wherein
the propylene-based resin (A) satisfies the following (f) and
(g):
[0021] (f) rrrr/(1-mmmm).ltoreq.0.1, and
[0022] (g) [rmrm]>2.5 mol %. [0023] [7] The spunbonded nonwoven
fabric according to any one of the above items [1] to [6], wherein
a total content of the propylene-based resin (A) in the core-sheath
composite fiber as calculated according to the following expression
is 0.5 to 47.5% by mass:
[0023] [Total content of propylene-based resin
(A)]=Wc.times.Xc/100
[0024] Wc: Mass fraction of the core part
[0025] Xc: Mass fraction of the propylene-based resin (A) in the
core component constituting the core part [0026] [8] The spunbonded
nonwoven fabric according to any one of the above items [1] to [7],
wherein the propylene-based resin (A) is a propylene homopolymer or
a copolymer in which a copolymerization ratio of a propylene unit
is 90 mol % or more. [0027] [9] The spunbonded nonwoven fabric
according to any one of the above items [1] to [8], wherein the
propylene-based resin (B) is a propylene homopolymer or a copolymer
in which a copolymerization ratio of a propylene unit is 50 mol %
or more. [0028] [10] The spunbonded nonwoven fabric according to
any one of the above items [1] to [9], wherein the ethylene-based
resin is an ethylene homopolymer or a copolymer in which a
copolymerization ratio of an ethylene unit is more than 50 mol %.
[0029] [11] A multilayered nonwoven fabric comprising a laminate of
at least two or more layers of nonwoven fabric, at least one layer
of the nonwoven fabric constituting an outer layer of the
multilayered nonwoven fabric being composed of the spunbonded
nonwoven fabric according to any one of the above items [1] to
[10]. [0030] [12] A fiber product using the spunbonded nonwoven
fabric according to any one of the above items [1] to [10] or the
multilayered nonwoven fabric according to the above item [11].
Advantageous Effects of Invention
[0031] According to the present invention, in the spunbonded
nonwoven fabric composed of a core-sheath composite fiber, spinning
stability of the fiber and flexibility of the nonwoven fabric can
be improved.
DESCRIPTION OF EMBODIMENTS
[0032] The spunbonded nonwoven fabric of the present invention
comprises a core-sheath composite fiber having a core part composed
of a core component containing a propylene-based resin (A)
satisfying the following (a) to (e) and a sheath part composed of a
sheath component containing an ethylene-based resin:
[0033] (a) [mmmm]=20 to 60 mol %,
[0034] (b) [mm].times.[rr]/[mr].sup.2.ltoreq.2.0,
[0035] (c) weight average molecular weight (Mw)=10,000 to
200,000,
[0036] (d) molecular weight distribution (Mw/Mn)<4.0, and
[0037] (e) a melting point (Tm-D), as defined as a peak top of a
peak observed on the highest temperature side of a melting
endothermic curve which is obtained by holding under a nitrogen
atmosphere at -10.degree. C. for 5 minutes and then increasing the
temperature at a rate of 10.degree. C./min with a differential
scanning calorimeter (DSC), is from 0 to 120.degree. C.
[Propylene-Based Resin (A)]
[0038] The propylene-based resin (A) which is used in the present
invention has properties shown in the following (a) to (e), and
these properties can be regulated according to selection of a
catalyst or reaction conditions on the occasion of producing the
propylene-based resin (A). [0039] (a) Mesopentad fraction [mmmm]=20
to 60 mol %
[0040] If the mesopentad fraction [mmmm] is less than 20 mol %,
spinnability becomes instable, and reducing the fiber diameter is
difficultly achieved. In addition, if the mesopentad fraction
[mmmm] is more than 60 mol %, flexibility of the nonwoven fabric is
impaired. This mesopentad fraction [mmmm] is preferably 30 to 50
mol %, and more preferably 40 to 50 mol %. [0041] (b)
[mm].times.[rr]/[mr].sup.2.ltoreq.2.0
[0042] The [mm].times.[rr]/[mr].sup.2 indicates an index of random
properties of the polymer, and when the [mm].times.[rr]/[mr].sup.2
is closer to 0.25, the random properties become higher, and the
nonwoven fabric is excellent in flexibility. When this value is 2.0
or less, sufficient flexibility is obtained in fibers obtained by
means of spinning.
[0043] From the viewpoint of obtaining sufficient flexibility as
described above, the [mm].times.[rr]/[mr].sup.2 is preferably 0.25
to 1.8, and more preferably 0.25 to 1.5. [0044] (c) Weight average
molecular weight (Mw)=10,000 to 200,000
[0045] In the above-described propylene-based resin (A), when the
weight average molecular weight is 10,000 or more, the viscosity of
the propylene-based resin (A) is not excessively low but is
appropriate, and therefore, end breakage on the occasion of
spinning is suppressed. In addition, when the weight average
molecular weight is 200,000 or less, the viscosity of the
above-described propylene-based resin (A) is not excessively high,
and spinnability is improved. This weight average molecular weight
is preferably 30,000 to 150,000, and more preferably 50,000 to
150,000. [0046] (d) Molecular weight distribution
(Mw/Mn)<4.0
[0047] In the above-described propylene-based resin (A), when the
molecular weight distribution (Mw/Mn) is less than 4.0, the
generation of stickiness in the fibers obtained by spinning is
suppressed. This molecular weight distribution is preferably 3.0 or
less. [0048] (e) Melting point (Tm-D)
[0049] In the above-described propylene-based resin (A), the
melting point (Tm-D), as defined as a peak top of a peak observed
on the highest temperature side of a melting endothermic curve
which is obtained by holding under a nitrogen atmosphere at
-10.degree. C. for 5 minutes and then increasing the temperature at
a rate of 10.degree. C./min with a differential scanning
calorimeter (DSC), is 0 to 120.degree. C., and preferably 40 to
120.degree. C.
[0050] As the above-described propylene-based resin (A), a
propylene-based resin further satisfying the following (f) and (g)
is preferably used. [0051] (f) rrrr/(1-mmmm).ltoreq.0.1
[0052] A value of rrrr/(1-mmmm) is an index indicating the
uniformity of regularity distribution of the propylene-based resin
(A). In the above-described propylene-based resin (A), when the
rrrr/(1-mmmm) is more than 0.1, the regularity distribution is
widened, and a mixture of atactic polypropylene is formed, thereby
likely causing stickiness. From such a viewpoint, the rrrr/(1-mmmm)
is preferably 0.05 or less, and more preferably 0.04 or less.
[0053] (g) [rmrm]>2.5 mol %
[0054] When a racemic-meso-racemic-meso pentad fraction [rmrm] of
the above-described propylene-based resin (A) is 2.5 mol % or less,
random properties of the propylene-based resin (A) are reduced, a
degree of crystallization is increased, and flexibility of the
nonwoven fabric is lowered. The [rmrm] is preferably 2.6 mol % or
more, and more preferably 2.7 mol % or more. An upper limit thereof
is usually about 10 mol %.
[0055] The stereoregularity of the foregoing (a), (b), (f) and (g)
is determined by means of NMR.
[0056] In the present invention, the mesopentad fraction [mmmm],
the racemic pentad fraction [rrrr], and the
racemic-meso-racemic-meso pentad fraction [rmrm] are measured in
conformity with the method proposed by A. Zambelli, et al.,
"Macromolecules, 6, 925 (1973)" and are a meso fraction, a racemic
fraction, and a racemic-meso-racemic-meso fraction, respectively in
the pentad units of the polypropylene molecular chain that are
measured based on a signal of the methyl group in the .sup.13C-NMR
spectrum. As the mesopentad fraction [mmmm] increases, the
stereoregularity increases, too. In addition, the triad fractions
[mm], [rr], and [mr] were also calculated by the above-described
method.
[0057] The .sup.13C-NMR spectrum is measured with the following
device under the following conditions according to the peak
assignment proposed by A. Zambelli, et al., "Macromolecules, 8, 687
(1975)".
[0058] Device: .sup.13C-NMR device, JNM-EX400 series, manufactured
by JEOL, Ltd.
[0059] Method: Proton complete decoupling method
[0060] Concentration: 220 mg/mL
[0061] Solvent: Mixed solvent of 1,2,4-trichlorobenzene and
deuterated benzene in a ratio of 90/10 (volume ratio)
[0062] Temperature: 130.degree. C.
[0063] Pulse width: 45.degree.
[0064] Pulse repetition time: 4 seconds
[0065] Accumulation: 10,000 times
<Calculating Expressions>
[0066] M=m/S.times.100
R=.gamma./S.times.100
S=P.beta..beta.+P.alpha..beta.+P.alpha..gamma.
[0067] S: Signal intensity of carbon atoms in side chain methyl of
all the propylene units
[0068] P.beta.62 : 19.8 to 22.5 ppm
[0069] P.alpha..beta.: 18.0 to 17.5 ppm
[0070] P.alpha..gamma.: 17.5 to 17.1 ppm
[0071] .gamma.: Racemic pentad chain, 20.7 to 20.3 ppm
[0072] m: Mesopentad chain, 21.7 to 22.5 ppm
[0073] The above-described (c) weight average molecular weight (Mw)
and (d) molecular weight distribution (Mw/Mn) are determined by
means of a gel permeation chromatography (GPC) measurement. The
weight average molecular weight of the present invention is a
weight average molecular weight as converted into polystyrene, as
measured by using the following device under the following
conditions, and the molecular weight distribution is a value
calculated from a number average molecular weight (Mn) as measured
similarly and the above-described weight average molecular
weight.
<GPC Measuring Device>
[0074] Column: TOSO GMHHR-H(S)HT
[0075] Detector: RI detector for liquid chromatography, WATERS
150C
<Measurement Conditions>
[0076] Solvent: 1,2,4-trichlorobezene
[0077] Measurement temperature: 145.degree. C.
[0078] Flow rate: 1.0 mL/min
[0079] Sample concentration: 2.2 mg/mL
[0080] Injection amount: 160 .mu.L
[0081] Calibration curve: Universal Calibration
[0082] Analysis program: HT-GPC (ver. 1.0)
[0083] The propylene-based resin (A) may be either a propylene
homopolymer or a copolymer. In the case where the propylene-based
resin (A) is a copolymer, a copolymerization ratio of a propylene
unit is 50 mol % or more, preferably 60 mol % or more, more
preferably 70 mol % or more, still more preferably 90 mol % or
more, and especially preferably 95 mol % or more. Examples of a
copolymerizable monomer include a-olefins having 2 or 4 to 20
carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene,
1-octene, 1-decene, etc., acrylic acid esters, such as methyl
acrylate, etc., vinyl acetate, and the like. A propylene
homopolymer is preferred from the viewpoint of moldability.
[0084] As for the propylene-based resin (A), its initial elastic
modulus is preferably 5 MPa or more and less than 500 MPa, more
preferably 10 to 400 MPa, and still more preferably 20 to 300 MPa.
The initial elastic modulus as referred to in this description is
one measured by the following measuring method.
[Measuring Method of Initial Elastic Modulus]
[0085] A press sheet having a thickness of 1 mm is fabricated. A
test piece is sampled from the resulting press sheet in conformity
with JIS K7113 (2002) No. 2-1/2. Using a tensile tester (AUTOGRAPH
AG-1, manufactured by Shimadzu Corporation), the test piece is set
at an initial length L0 of 40 mm, stretched at a tensile speed of
100 mm/min, and measured for a strain and a load in the stretching
process, and the initial elastic modulus is calculated according to
the following expression.
Initial elastic modulus (N)=(Load(N) at a strain of 5%)/0.05
[0086] The above-described propylene-based resin (A) can be
produced by using a metallocene-based catalyst as described in, for
example, WO2003/087172. In particular, a metallocene-based catalyst
using a transition metal compound in which a ligand forms a
crosslinked structure via a crosslinking group is preferred. Above
all, a metallocene-based catalyst obtained by combining a
transition metal compound in which a crosslinked structure is
formed via two crosslinking group with a promoter is preferred.
[0087] Specifically, examples thereof include a polymerization
catalyst containing (A) a transition metal compound represented by
the general formula (I) and (B) a component selected from (B-1) a
compound capable of reacting with the transition metal compound
that is the component (A) or a derivative thereof to form an ionic
complex and (B-2) an aluminoxane.
##STR00001##
[0088] [In the formula, M represents a metal element belonging to
any one of the Groups 3 to 10 or the lanthanoid series in the
periodic table; each of E.sup.1 and E.sup.2 represents a ligand
selected from a substituted cyclopentadienyl group, an indenyl
group, a substituted indenyl group, a heterocyclopentadienyl group,
a substituted heterocyclopentadienyl group, an amide group, a
phosphide group, a hydrocarbon group, and a silicon-containing
group, and forms a crosslinked structure via A.sup.1 and A.sup.2,
and may be the same as or different from each other; X represents a
.sigma.-bonding ligand, and when a plurality of Xs are present, the
plurality of Xs may be the same as or different from each other,
and each X may crosslink with any other X, E.sup.1, E.sup.2, or Y;
Y represents a Lewis base, and when a plurality of Ys are present,
the plurality of Ys may be the same as or different from each
other, and each Y may crosslink with any other Y, E.sup.1, E.sup.2,
or X; each of A.sup.1 and A.sup.2 represents a divalent
crosslinking group that bonds two ligands and represents a
hydrocarbon group having 1 to 20 carbon atoms, a halogen-containing
hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing
group, a germanium-containing group, a tin-containing group, --O--,
--CO--, --S--, --SO.sub.2--, --Se--, --NR.sup.1--, --PR.sup.1--,
--P(O)R.sup.1--, --BR.sup.1--, or --AlR.sup.1--, wherein R.sup.1
represents a hydrogen atom, a halogen atom, a hydrocarbon group
having 1 to 20 carbon atoms, or a halogen-containing hydrocarbon
group having 1 to 20 carbon atoms, and may be the same as or
different from each other; q represents an integer of 1 to 5 and
corresponds to [(valence of M)-2]; and r represents an integer of 0
to 3.]
[0089] The transition metal compound that is the above-described
component (A) is preferably a transition metal compound in which
the ligand is of a (1,2')(2,1') double crosslinking type, and
examples thereof include
(1,2'-dimethylsilylene)(2,1'-dimethylsilylene)-bis(3-trimethylsilylmethyl-
indenyl)zirconium dichloride.
[0090] As specific examples of the compound that is the
above-described component (B-1), there can be exemplified
triethylammonium tetraphenylborate, tri-n-butylammonium
tetraphenylborate, trimethylammonium tetraphenylborate,
tetraethylammonium tetraphenylborate, methyl(tri-n-butyl)ammonium
tetraphenylborate, benzyl(tri-n-butyl) ammonium tetraphenylborate,
dimethyldiphenylammonium tetraphenylborate,
triphenyl(methyl)ammonium tetraphenylborate, trimethylanilinium
tetraphenylborate, methylpyridinium tetraphenylborate,
benzylpyridinium tetraphenylborate, methyl(2-cyanopyridinium)
tetraphenylborate, triethylammonium
tetrakis(pentafluorophenyl)borate, tri-n-butylammonium
tetrakis(pentafluorophenyl)borate, triphenylammonium
tetrakis(pentafluorophenyl)borate, tetra-n-butylammonium
tetrakis(pentafluorophenyl)borate, tetraethylammonium
tetrakis(pentafluorophenyl)borate, benzyl(tri-n-butyl) ammonium
tetrakis(pentafluorophenyl)borate, methyldiphenylammonium
tetrakis(pentafluorophenyl)borate, triphenyl(methyl)ammonium
tetrakis(pentafluorophenyl)borate, methylanilinium
tetrakis(pentafluorophenyl)borate, dimethylanilinium
tetrakis(pentafluorophenyl)borate, trimethylanilinium
tetrakis(pentafluorophenyl)borate, methylpyridinium
tetrakis(pentafluorophenyl)borate, benzylpyridinium
tetrakis(pentafluorophenyl)borate, methyl(2-cyanopyridinium)
tetrakis(pentafluorophenyl)borate, benzyl(2-cyanopyridinium)
tetrakis(pentafluorophenyl)borate, methyl(4-cyanopyridinium)
tetrakis(pentafluorophenyl)borate, triphenylphosphonium
tetrakis(pentafluorophenyl)borate, dimethylanilinium
tetrakis[bis(3,5-ditrifluoromethyl)phenyl]borate, ferrocenium
tetraphenylborate, silver tetraphenylborate, trityl
tetraphenylborate, tetraphenylporphyrinmanganese tetraphenylborate,
ferrocenium tetrakis(pentafluorophenyl)borate,
(1,1'-dimethylferrocenium) tetrakis(pentafluorophenyl)borate,
decamethylferrocenium tetrakis(pentafluorophenyl)borate, silver
tetrakis(pentafluorophenyl)borate, trityl
tetrakis(pentafluorophenyl)borate, lithium
tetrakis(pentafluorophenyl)borate, sodium
tetrakis(pentafluorophenyl)borate, tetraphenylporphyrinmanganese
tetrakis(pentafluorophenyl)borate, silver tetrafluoroborate, silver
hexafluorophosphate, silver hexafluoroarsenate, sliver perchlorate,
silver trifluoroaceate, silver trifluoromethanesulfonate, and the
like.
[0091] Examples of the aluminoxane that is the above-described
component (B-2) include known chain aluminoxanes and cyclic
aluminoxanes.
[0092] In addition, the propylene-based resin (A) may also be
produced by jointly using an organoaluminum compound, such as
trimethylaluminum, triethylaluminum, triisopropylaluminum,
triisobutylaluminum, dimethylaluminum chloride, diethylaluminum
chloride, methylaluminum dichloride, ethylaluminum dichloride,
dimethylaluminum fluoride, diisobutylaluminum hydride,
diethylaluminum hydride, ethylaluminum sesquichloride, etc.
[0093] A content of the above-described propylene-based resin (A)
in the core component is preferably 1 to 50% by mass, more
preferably 3 to 50% by mass, still more preferably 5 to 50% by
mass, especially preferably 5 to 40% by mass, and most preferably 5
to 30% by mass. When the content of the propylene-based resin (A)
is 50% by mass or less, the degree of crystallization on the
spinning line does not become extremely slow, and the spinnability
becomes stable. When the content of the propylene-based resin (A)
in the core component is 1% by mass or more, it becomes possible to
achieve the reduction of diameter of fibers, and the flexibility of
the nonwoven fabric is improved with a decrease of the elastic
modulus of fiber.
[0094] The above-described core component may further contain a
propylene-based resin (B) as described below.
[Propylene-Based Resin (B)]
[0095] The propylene-based resin (B) which is used in the present
invention is not particularly limited so long as its melting point
(Tm-D), as defined as a peak top of a peak observed on the highest
temperature side of a melting endothermic curve which is obtained
by holding under a nitrogen atmosphere at -10.degree. C. for 5
minutes and then increasing the temperature at a rate of 10.degree.
C./rain with a differential scanning calorimeter (DSC), is higher
than 120.degree. C., and PP3155 (a trade name, manufactured by
ExxonMobil Chemical), Y2000GP (a trade name, manufactured by Prime
Polymer Co., Ltd.), and the like can be used.
[0096] The propylene-based resin (B) may be either a propylene
homopolymer or a copolymer. In the case where the propylene-based
resin (B) is a copolymer, a copolymerization ratio of a propylene
unit is 50 mol % or more, preferably 60 mol % or more, more
preferably 70 mol % or more, still more preferably 90 mol % or
more, and especially preferably 95 mol % or more. Examples of a
copolymerizable monomer include a-olefins having 2 or 4 to 20
carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene,
1-octene, 1-decene, etc., acrylic acid esters, such as methyl
acrylate, etc., vinyl acetate, and the like. A propylene
homopolymer is preferred from the viewpoint of moldability.
[0097] In addition, as for the propylene-based resin (B), its
melting point (Tm-D), as defined as a peak top of a peak observed
on the highest temperature side of a melting endothermic curve
which is obtained by holding under a nitrogen atmosphere at
-10.degree. C. for 5 minutes and then increasing the temperature at
a rate of 10.degree. C./min with a differential scanning
calorimeter (DSC), is preferably higher than 120.degree. C. and
170.degree. C. or lower, and more preferably 125 to 167.degree.
C.
[0098] As for the propylene-based resin (B), its initial elastic
modulus is preferably 500 to 2,000 MPa, more preferably 600 to
2,000 MPa, and still more preferably 700 to 1,800 MPa.
[0099] A content of the above-described propylene-based resin (B)
in the core component is preferably 50 to 99% by mass, more
preferably 50 to 97% by mass, still more preferably 50 to 95% by
mass, especially preferably 60 to 95% by mass, and most preferably
70 to 90% by mass.
[Ethylene-Based Resin]
[0100] The ethylene-based resin which is contained in the sheath
component that forms the sheath part of the core-sheath composite
fiber may be either a homopolymer or a copolymer. In the case where
the ethylene-based resin is a copolymer, a copolymerization ratio
of an ethylene unit is more than 50 mol %, preferably 60 mol % or
more, more preferably 70 mol % or more, still more preferably 90
mol % or more, and especially preferably 95 mol % or more. Examples
of a copolymerizable monomer include a-olefins having 3 to 20
carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene,
1-octene, 1-decene, etc., acrylic acid esters, such as methyl
acrylate, etc., vinyl acetate, and the like.
[0101] A melting point of the ethylene-based resin is preferably 50
to 155.degree. C., and more preferably 60 to 150.degree. C.
[0102] A content of the ethylene-based resin in the sheath
component is preferably 85 to 100% by mass, and more preferably 90
to 100% by mass.
[0103] In addition, the sheath component can also be compounded
with a conventionally known additive in addition to the
above-described ethylene-based resin. Examples of the additive
include a foaming agent, a crystal nucleating agent, a
weatherability stabilizer, a UV absorber, a light stabilizer, a
heat resistance stabilizer, an antistatic agent, a release agent, a
flame retardant, a synthetic oil, a wax, an electric
property-improving agent, a slip inhibitor, an anti-blocking agent,
a viscosity-controlling agent, a coloring inhibitor, a defogging
agent, a lubricant, a pigment, a dye, a plasticizer, a softening
agent, an age resistor, a hydrochloric acid-absorbing agent, a
chlorine scavenger, an antioxidant, an antitack agent, and the
like.
[0104] The sheath component may further contain an internal release
agent. The internal release agent as referred to herein means an
additive for improving release properties of the nonwoven fabric
upon being added to the resin raw material. Specifically, examples
thereof include high-melting point polymers, organic carboxylic
acids or metal salts thereof, aromatic sulfonic acids or metal
salts thereof, organic phosphoric acid compounds or metal salts
thereof, dibenzylidene sorbitol or derivatives thereof, rhodinic
acid partial metal salts, inorganic fine particles, imides, amides,
quinacridones, quinones, and mixtures thereof, and the like.
[0105] Examples of the high-melting point polymer include
polyolefins, such as polyethylene, polypropylene, etc., and the
like.
[0106] Examples of the organic carboxylic acid include fatty acids,
such as octylic acid, palmitic acid, lauric acid, stearic acid,
behenic acid, montanic acid, 12-hydroxystearic acid, oleic acid,
isostearic acid, ricinoleic acid, etc., and aromatic acids, such as
benzoic acid, p-t-butyl-benzoic acid, etc. Examples of the metal
salt of an organic carboxylic acid include salts of Li, Ca, Ba, Zu,
Mg, Al, Pb, and the like of the above-described organic carboxylic
acids, and metallic soaps that are a metal salt of a carboxylic
acid. Specifically, examples thereof include aluminum benzoate,
aluminum p-t-butylbenzoate, sodium adipate, sodium
thiophenecarboxylate, sodium pyrrolecarboxylate, and the like.
[0107] Examples of the aromatic sulfonic acid include a linear
alkylbenzenesulfonic acid, a branched alkylbenzenesulfonic acid,
naphthalenesulfonic acid, dodecylbenzenesulfonic acid, and the
like. Examples of the metal salt of an aromatic sulfonic acid
include salts of Li, Ca, Ba, Zu, Mg, Al, Pb, and the like of the
above-described aromatic sulfonic acids.
[0108] Examples of the organic phosphoric acid compound include
trimethyl phosphate, triethyl phosphate, tributyl phosphate,
2-ethylhexyl phosphate, butoxyethyl phosphate, triphenyl phosphate,
tricresyl phosphate, trixylenyl phosphate, cresyldiphenyl
phosphate, 2 -ethylhexyldiphenyl phosphate, cresyldi-2,6-xylenyl
phosphate, resorcinoldiphenol phosphate, various aromatic condensed
phosphate esters, 2-chloroethyl phosphate, chloropropyl phosphate,
dichloropropyl phosphate, tribromoneopentyl phosphate, a
halogen-containing condensed phosphoric acid, bis-2-ethylhexyl
phosphate, diisodecyl phosphate, 2-methacryloyloxyethyl acid
phosphate, diphenyl-2-methacryloyloxyethyl phosphate, methyl acid
phosphate, butyl acid phosphate, monoisodecyl phosphate,
2-butylhexyl acid phosphate, isodecyl acid phosphate, triphenyl
phosphate, dibutyl hydrogen phosphate, dibutyl hydrogen phosphate,
polyoxyethylene lauryl ether phosphoric acid, polyoxyalkyl ether
phosphoric acid, polyoxyethylene alkyl phenyl ether phosphoric
acid, polyoxyethylene dialkyl phenyl ether phosphoric acid, and the
like; and examples of the metal salt of an organic phosphoric acid
compound include metal salts of Li, Ca, Ba, Zu, Mg, Al, Pb, and the
like of the above-described organic phosphoric acid compounds.
Examples of commercially available products thereof include ADEKA
STAB NA-11 and ADEKA STAB NA-21, all of which are manufactured by
ADEKA Corporation, and the like.
[0109] Examples of dibenzylidene sorbitol or its derivative include
dibenzylidene sorbitol,
1,3:2,4-bis(o-3,4-dimethylbenzylidene)sorbitol,
1,3;2,4-bis(o-2,4-dimethylbenzylidene)sorbitol,
1,3:2,4-bis(o-4-ethylbenzylidene)sorbitol,
1,3:2,4-bis(o-4-chlorobenzylidene)sorbitol, 1,3:2,4-dibenzylidene
sorbitol, and the like. Examples of commercially available products
thereof include GEL ALL MD and GEL ALL MD-R, all of which are
manufactured by New Japan Chemical Co., Ltd., and the like.
[0110] Examples of the rhodinic acid partial metal salt include
PINECRYSTAL KM1600, PINECRYSTAL KM1500, and PINECRYSTAL KM1300, all
of which are manufactured by Arakawa Chemical Industries, Ltd., and
the like.
[0111] Examples of the inorganic fine particle include talc, clay,
mica, asbestos, glass fiber, glass flake, glass bead, calcium
silicate, montmorillonite, bentonite, graphite, aluminum powder,
alumina, silica, diatomaceous earth, titanium oxide, magnesium
oxide, pumice powder, pumice balloon, aluminum hydroxide, magnesium
hydroxide, basic magnesium carbonate, dolomite, calcium sulfate,
potassium titanate, barium sulfate, calcium sulfite, molybdenum
sulfide, and the like. Examples of commercially available products
thereof include SYLYSIA, manufactured by Fuji Silysia Chemical
Ltd., MIZUKASIL, manufactured by Mizusawa Industrial Chemicals,
Ltd., and the like.
[0112] These internal release agents can be used solely or in
combination of two or more kinds thereof. In the present invention,
among these internal release agents, dibenzylidene sorbitol,
1,3:2,4-bis(o-3,4-dimethylbenzylidene)sorbitol,
1,3:2,4-bis(o-2,4-dimethylbenzylidene)sorbitol,
1,3:2,4-bis(o-4-ethylbenzylidene)sorbitol,
1,3:2,4-bis(o-4-chlorobenzylidene)sorbitol, and
1,3:2,4-dibenzylidene sorbitol are preferred.
[0113] A content of the internal release agent is preferably 10 to
10,000 ppm by mass, and more preferably 100 to 5,000 ppm by mass on
the basis of the composition of the sheath component. When the
content of the internal release agent is 10 ppm by mass or more,
the function as the release agent is revealed, whereas when it is
10,000 ppm by mass or less, a balance between the function as the
release agent and the economy becomes favorable.
[0114] In the core-sheath type composite fiber, a total content of
the above-described propylene-based resin (A) as calculated
according to the following expression is preferably 0.5 to 47.5% by
mass from the viewpoints of stabilizing the spinnability of fiber
and giving flexibility to the nonwoven fabric.
[Total content of propylene-based resin (A)]=Wc.times.Xc/100
[0115] Wc: Mass fraction of the core part
[0116] Xc: Mass fraction of the propylene-based resin (A) in the
core component constituting the core part
[0117] In the core-sheath type composition fiber, the mass fraction
of the core part is preferably in the range of 50 to 90% by mass
from the viewpoints of stability control of the core-sheath
structure of fiber and stabilization of spinnability.
[0118] As for the core-sheath composite fiber constituting the
spunbonded nonwoven fabric of the present invention, a fineness as
calculated by the following measuring method is preferably 0.5
deniers or more and less than 1.5 deniers, and more preferably 0.8
to 1.45 deniers from the viewpoints of a balance among texture of
the nonwoven fabric, flexibility and strength. As described above,
the spunbonded nonwoven fabric of the present invention is small in
terms of the fineness and is excellent in terms of spinning
stability even under molding conditions under which end breakage
likely occurs.
[Measurement of Fineness]
[0119] Fibers in a nonwoven fabric are observed with a polarizing
microscope, an average value (d) of diameter of randomly selected
five fibers is measured, and the fineness of the nonwoven fabric
sample is calculated from a density of the resin (.rho.=900,000
g/m.sup.3) according to the following expression [1].
Fineness (denier)=.rho..times..pi..times.(d/2).sup.2.times.9,000
[1]
[Multilayered Nonwoven Fabric]
[0120] The spunbonded nonwoven fabric of the present invention may
also be a multilayered nonwoven fabric comprising a laminate of two
or more layers. In that case, from the viewpoint of smoothness of
the surface, it is preferred that at least one layer of the
nonwoven fabric constituting an outer layer of the multilayered
nonwoven fabric is the spunbonded nonwoven fabric composed of the
core-sheath composite fiber of the present invention.
[Fiber Product]
[0121] Although the fiber product using the spunbonded nonwoven
fabric of the present invention is not particularly limited, the
following fiber products can be exemplified. That is, there can be
exemplified a member for a disposable diaper, a stretchable member
for a diaper cover, a stretchable member for a sanitary product, a
stretchable member for a hygienic product, a stretchable tape, an
adhesive bandage, a stretchable member for clothing, an insulating
material for clothing, a heat insulating material for clothing, a
protective suit, a hat, a mask, a glove, a supporter, a stretchable
bandage, a base fabric for a fomentation, a non-slip base fabric, a
vibration absorber, a finger cot, an air filter for a clean room,
an electret filter subjected to electret processing, a separator, a
heat insulator, a coffee bag, a food packaging material, a ceiling
skin material for an automobile, an acoustic insulating material, a
cushioning material, a speaker dust-proof material, an air cleaner
material, an insulator skin, a backing material, an adhesive
non-woven fabric sheet, various members for automobiles such as a
door trim, various cleaning materials such as a cleaning material
for a copying machine, the facing and backing of a carpet, an
agricultural beaming, a timber drain, members for shoes such as a
sport shoe skin, a member for a bag, an industrial sealing
material, a wiping material, a sheet, and the like.
EXAMPLES
[0122] The present invention is hereunder explained in more detail
by reference to Examples, but it should be construed that the
present invention is not limited to these Examples at all.
Example 1
(Preparation of Core Component)
[0123] 80% by mass of a propylene-based resin (B) (PP3155,
manufactured by ExxonMobil Chemical) having a melt flow rate (MFR),
as measured under conditions at a temperature of 230.degree. C. and
a load of 2.16 kg in conformity with ASTM D1238, of 36 g/10 min was
compounded with 20% by mass of a propylene-based resin (A) (L-MODU
(a registered trademark) S901, manufactured by Idemitsu Kosan Co.,
Ltd.) having a melt flow rate (MFR), as measured under conditions
at a temperature of 230.degree. C. and a load of 2.16 kg in
conformity with JIS K7210, of 50 g/10 min and a melting point of
70.degree. C., thereby preparing a core component.
(Preparation of Sheath Component)
[0124] Only an ethylene-based resin (ASPUN 6834, manufactured by
The Dow Chemical Company) having a melt flow rate (MFR), as
measured under conditions at a temperature of 190.degree. C. and a
load of 2.16 kg in conformity with ISO 1133, of 17 g/10 min and a
melting point of 130.degree. C. was used, thereby preparing a
sheath component.
(Production of Spunbonded Nonwoven Fabric)
[0125] A nonwoven fabric was molded by using a spunbond machine
(REICOFIL 4, manufactured by Reicofil GmbH). The raw materials of
the sheath component and the core component were spun in such a
manner that the materials were each separately melt extruded with a
single-screw extruder at a resin temperature of 240.degree. C. and
discharged through a core-sheath composite nozzle having a nozzle
diameter of 0.6 mm (number of holes: 6,800 holes/m) at a rate of
0.5 g/min per single hole in a mass ratio of the core component to
the sheath component of 70/30.
[0126] The fibers obtained by spinning were laminated at a
temperature of 16.degree. C. and a cabin pressure of 7,000 Pa on a
net surface moving at a line speed of 230 m/min. A fiber bundle
thus laminated on the net surface was embossed with an embossing
roll heated at 145.degree. C. at a line pressure of 70 N/mm and
then wound up around a winding roll.
[0127] The resulting nonwoven fabric was measured and evaluated as
follows. The results are shown in Tables 1 and 2.
[Measurement of Basis Weight]
[0128] A weight of the resulting nonwoven fabric of 5 cm.times.5 cm
was measured, thereby measuring a basis weight (g/10 m.sup.2).
[Measurement of Fineness]
[0129] Fibers in the nonwoven fabric were observed with a
polarizing microscope, an average value (d) of diameter of randomly
selected five fibers was measured, and the fineness of the nonwoven
fabric sample was calculated from a density of the resin
(.rho.=900,000 g/m.sup.3) according to the following expression
[1].
Fineness (denier)=.rho..times..pi..times.(d/2).sup.2.times.9,000
[1]
[Evaluation of Spinning Stability]
[0130] As an index of the spinning stability in molding of the
nonwoven fabric, a maximum cabin pressure at which no end breakage
occurred was shown.
[Evaluation of Breaking Strength and Breaking Strain]
[0131] A test piece having a length of 200 mm and a width of 50 mm
was sampled from the resulting nonwoven fabric in each of the
machine direction (MD) and the cross direction (CD) to the machine
direction. Using a tensile tester (AUTOGRAPH AG-1, manufactured by
Shimadzu Corporation), the test piece was set at an initial length
L0 of 100 mm, stretched at a tensile speed of 300 mm/min, and
measured for a strain and a load in the stretching process. Values
of the load and the strain at the moment at which the nonwoven
fabric was broken were defined as a breaking strength and a
breaking strain, respectively.
[Handle-O-Meter Test]
[0132] A test piece of 200 mm.times.200 mm is set on a slit having
a width of 1/4 inches in such a manner that it is rectangular to
the slit, and a position of 67 mm (1/3 of the width of the test
piece) far from the side of the test piece is pushed in a depth of
8 mm by using a blade of a penetrator. A resistance value at this
time was measured to evaluate a degree of flexibility of the test
piece. As for a characteristic feature of this measurement method,
a force in which a frictional force generated when the test piece
slightly slips on the test bench is mixed with a resisting force
(degree of flexibility) at the time of pushing is measured. It is
meant that the smaller the resistance value obtained by the
measurement, the more favorable the flexibility of the nonwoven
fabric is.
Example 2
[0133] A nonwoven fabric was molded in the same manner as that in
Example 1, except that in Example 1, a material obtained by mixing
50% by mass of the propylene-based resin (B) and 50% by mass of the
propylene-based resin (A) was used as the core component, and the
cabin pressure was changed to 7,500 Pa, and then evaluated in the
same way. The results are shown in Tables 1 and 2.
Comparative Example 1
[0134] A nonwoven fabric was molded in the same manner as that in
Example 1, except that in Example 1, 100% by mass of the
propylene-based resin (B) was used as the core component, the cabin
pressure was changed to 4,000 Pa, and the embossing roll
temperature was changed to 150.degree. C., and then evaluated in
the same way. The results are shown in Tables 1 and 2.
Comparative Example 2
[0135] A nonwoven fabric was molded in the same manner as that in
Comparative Example 1, except that in Comparative Example 1, the
cabin pressure was changed to 5,000 Pa. However, end breakage
occurred frequently, so that molding could not be achieved.
Example 3
[0136] A nonwoven fabric was molded in the same manner as that in
Example 1, except that in Example 1, the core component and the
sheath component were discharged in a mass ratio of 50/50 and spun,
and the cabin pressure was changed to 6,000 Pa, and then evaluated
in the same way. The results are shown in Tables 1 and 2.
Example 4
[0137] A nonwoven fabric was molded in the same manner as that in
Example 1, except that in Example 1, a material obtained by mixing
50% by mass of the propylene-based resin (B) and 50% by mass of the
propylene-based resin (A) was used as the core component, the core
component and the sheath component were discharged in a mass ratio
of 50/50 and spun, and the cabin pressure was changed to 6,500 Pa,
and then evaluated in the same way. The results are shown in Tables
1 and 2.
Comparative Example 3
[0138] A nonwoven fabric was molded in the same manner as that in
Example 1, except that in Example 1, 100% by mass of the
propylene-based resin (B) was used as the core component, the core
component and the sheath component were discharged in a mass ratio
of 50/50 and spun, the cabin pressure was changed to 4,200 Pa, and
the embossing roll temperature was changed to 156.degree. C., and
then evaluated in the same way. The results are shown in Tables 1
and 2.
Comparative Example 4
[0139] A nonwoven fabric was molded in the same manner as that in
Comparative Example 3, except that in Comparative Example 3, the
cabin pressure was changed to 5,000 Pa. However, end breakage
occurred frequently, so that molding could not be achieved.
TABLE-US-00001 TABLE 1 Core component Sheath Molding conditions
Propyl- Propyl- component Total content Embos- ene- ene- Ethylene-
Resin Discharge Core/ of propylene- Cabin sing Line based based
based temper- amount per sheath based pres- temper- pres- Line
Basis resin (A) resin (B) resin ature single hole mass resin (A)
sure ature sure speed weight % by mass % by mass % by mass .degree.
C. g/min ratio % Pa .degree. C. N/mm m/min gsm Example 1 20 80 100
240 0.5 70/30 14 7000 145 70 230 15 Example 2 50 50 100 240 0.5
70/30 35 7500 145 70 230 15 Comparative 0 100 100 240 0.5 70/30 0
4000 150 70 230 15 Example 1 Comparative 0 100 100 240 0.5 70/30 0
5000 150 70 230 -- Example 2 Example 3 20 80 100 240 0.5 50/50 10
6000 145 70 230 15 Example 4 50 50 100 240 0.5 50/50 25 6500 145 70
230 15 Comparative 0 100 100 240 0.5 50/50 0 4200 156 70 230 15
Example 3 Comparative 0 100 100 240 0.5 50/50 0 5000 156 70 230 --
Example 4
TABLE-US-00002 TABLE 2 Breaking strength Breaking Handle-O- Fiber
MD CD strain Meter diameter N/5 N/5 MD CD MD CD Denier cm cm % % mN
mN Example 1 1.24 37 18 116 122 61 34 Example 2 1.31 31 15 83 109
48 26 Comparative 1.50 29 16 79 89 76 43 Example 1 Comparative --
-- -- -- -- -- -- Example 2 Example 3 1.33 29 17 98 118 50 30
Example 4 1.40 29 12 88 101 48 25 Comparative 1.54 26 17 92 100 63
38 Example 3 Comparative -- -- -- -- -- -- -- Example 4
INDUSTRIAL APPLICABILITY
[0140] The nonwoven fabric of the present invention is suitably
used for a variety of fiber products, for example, a disposable
diaper, a sanitary product, a hygienic product, a clothing
material, a bandage, a packaging material, etc.
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