U.S. patent application number 10/470308 was filed with the patent office on 2004-04-08 for non-woven fabrics of wind-shrink fiber and laminate thereof.
Invention is credited to Kishine, Masahiro, Morimoto, Hisashi, Takesue, Kunihiko.
Application Number | 20040067709 10/470308 |
Document ID | / |
Family ID | 26608423 |
Filed Date | 2004-04-08 |
United States Patent
Application |
20040067709 |
Kind Code |
A1 |
Kishine, Masahiro ; et
al. |
April 8, 2004 |
Non-woven fabrics of wind-shrink fiber and laminate thereof
Abstract
The invention provides a nonwoven fabric of crimped conjugate
fibers comprising (1) a first propylene-based polymer component and
(2) a second propylene-based polymer component, and a laminate of
the nonwoven fabric and other nonwoven fabrics or porous films, in
which the melting point of the component (1) is higher by at least
20.degree. C. than that of the component (2) a ratio of the two
components in melt flow rate (component (2)/component (1)) is in
the range of 0.8 to 1.2, and the component ratio expressed by
(1)/(2) (by weight) is 50/50 to 5/95. The nonwoven fabric has an
excellent bulkiness and softness, is excellent in terms of
spinnability and fuzzing resistance, and can be spun by a
conventional melt spinning. The laminate has further improved water
impermeability and surface smoothness. The nonwoven fabric and the
laminate using the same may both be used for disposable diapers or
sanitary napkins.
Inventors: |
Kishine, Masahiro; (Tokyo,
JP) ; Takesue, Kunihiko; (Yokkaichi-shi, JP) ;
Morimoto, Hisashi; (Yokkaichi-shi, JP) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Family ID: |
26608423 |
Appl. No.: |
10/470308 |
Filed: |
July 29, 2003 |
PCT Filed: |
January 28, 2002 |
PCT NO: |
PCT/JP02/00585 |
Current U.S.
Class: |
442/327 ;
442/334 |
Current CPC
Class: |
B32B 5/26 20130101; D04H
3/018 20130101; Y10T 442/641 20150401; Y10T 428/2922 20150115; Y10T
428/2913 20150115; Y10T 428/2929 20150115; Y10T 428/2915 20150115;
Y10T 442/629 20150401; Y10T 442/608 20150401; Y10T 428/2931
20150115; Y10T 442/627 20150401; Y10T 442/60 20150401; D04H 3/007
20130101; D04H 3/14 20130101; Y10T 442/637 20150401; D01F 8/06
20130101; Y10T 428/2924 20150115 |
Class at
Publication: |
442/327 ;
442/334 |
International
Class: |
D04H 005/00; D04H
013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 29, 2001 |
JP |
019734/2001 |
Jul 18, 2001 |
JP |
217995/2001 |
Claims
What is claimed is:
1. A nonwoven fabric of a crimped conjugate fiber comprising a
first propylene-based polymer component and a second
propylene-based polymer component, in which said first and second
propylene-based polymer components are arranged to have
substantially different zones in the cross-section of the crimped
conjugate fiber and are extended continuously along the
longitudinal direction of the crimped conjugate fiber, said second
propylene-based polymer component forms at least a part of the
peripheral surface continuously along the longitudinal direction of
the crimped conjugate fiber, the melting point of said first
propylene-based polymer component is higher by at least 20.degree.
C. than the melting point of said second propylene-based polymer
component as determined by a differential scanning calorimeter
(DSC), and the ratio of said first/second propylene-based polymer
components (by weight) is in the range of 50/50 to 5/95.
2. The nonwoven fabric composed of the crimped conjugate fiber
according to claim 1, wherein the ratio of said second to first
propylene-based polymer components in the melt flow rate (MFR:
measurement temperature at 230.degree. C. under a load of 2.16 kg),
as determined in accordance with ASTM D1238, is in the range of 0.8
to 1.2 (the second component/the first component).
3. The nonwoven fabric composed of the crimped conjugate fiber
according to claims 1 or 2, wherein the crimped conjugate fiber
constituting the nonwoven fabric has at least two melting point
peaks for the crimped conjugate fiber as determined by DSC on the
first run, and the area for the lowest melting point peak is not
smaller than the area for each of the other higher melting point
peaks.
4. The nonwoven fabric composed of the crimped conjugate fiber
according to any one of claims 1 to 3, wherein the first or second
propylene polymer is a propylene homopolymer or a
propylene-ethylene random copolymer, having 0 to 10 mol % of the
ethylene unit and MFR of 20 to 200 g/10 min.
5. The nonwoven fabric composed of the crimped conjugate fiber
according to any one of claims 1 to 4, wherein the crimped
conjugate fiber is an eccentric core/sheath type conjugate fiber
comprising the core composed of the first propylene-based polymer
component and the sheath composed of the second propylene-based
polymer component.
6. The nonwoven fabric composed of the crimped conjugate fiber
according to any one of claims 1 to 4, wherein the crimped
conjugate fiber is a side-by-side type conjugate fiber comprising
the first propylene-based polymer component and the second
propylene-based polymer component.
7. The nonwoven fabric composed of the crimped conjugate fiber
according to any one of claims 1 to 6, wherein the nonwoven fabric
is heat fused by an emboss processing.
8. The nonwoven fabric composed of the crimped conjugate fiber
according to claim 7, wherein said emboss processing is conducted
under conditions of an emboss area percentage of 5 to 20% and a
non-emboss unit area of at least 0.5 mm.sup.2.
9. The nonwoven fabric composed of the crimped conjugate fiber
according to any one of claims 1 to 8, wherein the nonwoven fabric
of the crimped conjugate fiber is a spun-bonded nonwoven fabric
produced by a spun-bonding process.
10. A nonwoven fabric laminate comprising at least two-layer
structure, at least one of which is the nonwoven fabric composed of
the crimped conjugate fiber according to any one of claims 1 to
9.
11. The nonwoven fabric laminate according to claim 10, wherein a
plurality of the nonwoven fabrics composed of said crimped
conjugate fiber different in the degree of crimps are
laminated.
12. The nonwoven fabric laminate according to claim 10, wherein at
least one other layer constituting the laminate is a layer of a
melt-blown nonwoven fabric produced by a melt-blowing process.
13. The nonwoven fabric laminate according to claim 10, wherein at
least one other layer constituting the laminate is a layer of a
spun-bonded nonwoven fabric composed of microfibers produced by a
spun-bonding process.
14. The nonwoven fabric laminate according to claim 10, wherein at
least one other layer constituting the laminate is an air permeable
film layer.
15. A disposable diaper using the nonwoven fabric of the crimped
conjugate fiber or the nonwoven fabric laminate according to any
one of claims 1 through 14.
16. A sanitary napkin using the nonwoven fabric of the crimped
conjugate fiber or the nonwoven fabric laminate according to any
one of claims 1 through 14.
Description
TECHNICAL FIELD
[0001] The present invention relates to a nonwoven fabric
comprising crimped conjugate fibers. More particularly, the
invention relates to a nonwoven fabric composed of crimped
conjugate fibers, which has excellent bulkiness and softness as
well as excellent spinnability and fuzzing resistance, and to a
nonwoven fabric laminate using the same.
TECHNICAL BACKGROUND
[0002] In recent years, nonwoven fabrics are used for a wide
variety of applications because of their excellent gas permeability
and softness and are finding an increasing number of applicable
fields. Reflecting this background, nonwoven fabrics are being
called on to have a variety of properties satisfying the
requirements depending upon respective applications and to have
improved properties.
[0003] For example, nonwoven fabrics used as substrates of sanitary
goods such as disposable diapers, sanitary napkins, or poultice
materials, etc. are required to have water impermeability and
possess excellent permeability. In addition, nonwoven fabrics are
further required to have excellent extensibility, depending upon
place to be used.
[0004] More specifically, sanitary goods such as disposable diapers
have such a structure that an absorbing material for absorbing and
retaining body fluid is covered with a top sheet located inside an
absorbable article and a back sheet outside the absorbable article
and enclosed therein. The top sheet, which is in contact with skin,
is required to have the function of permeating discharged body
fluid therethrough and absorbing/retaining it in the absorbing
material inside and at the same time, causing no backflow. On the
other hand, the back sheet is required to have water impermeability
to prevent leakage of body fluid absorbed in the absorbing material
inside and have appropriate moisture permeability to prevent from
getting stuffy, permeate the inner moisture of absorbable article
therethrough and get scattered outside. Furthermore, the back sheet
forms the outer surface of sanitary goods and is thus required to
have excellent feeling and good touch.
[0005] In order to improve the feeling or touch of nonwoven
fabrics, it is effective to make nonwoven fabrics bulky. One
measure of the improvement includes crimping fibers, from which
nonwoven fabrics are made. Nonwoven fabrics made from crimped
fibers are excellent also in extensibility. For example, Japanese
Patent Laid-Open Application No. 9-78436 discloses extensible
nonwoven fabrics made from eccentric core-sheath type crimped
conjugate fibers, which are composed of polyethylene resin A having
a melt flow rate (MFR) of 5 to 20 g/10 min and polyolefin resin B
having a larger MFR by approximately 10 to 20 g/10 min than that of
polyethylene resin A and these resins are blended in a weight ratio
(A/B) of 10/90 to 20/80.
[0006] Also, Japanese Patent Laid-Open Application No. 11-323715
discloses spun-bonded nonwoven fabrics of eccentric core-sheath
type crimped conjugate fiber filaments, which are composed of the
core comprising a propylene-based polymer (A) having a melt flow
rate (MFR A, as determined at a load of 2.16 kg at 230.degree. C.
in accordance with ASTM D1238) of 0.5 to 100 g/10 min and the
sheath comprising a propylene-based polymer (B) having a melt flow
rate (MFR B, as determined at a load of 2.16 kg at 230.degree. C.
in accordance with ASTM D1238) that satisfies the relationship of
MFR A/MFR B.gtoreq.1.2 or MFR A/MFR B.ltoreq.0.8, indicating that
the nonwoven fabrics are used as the top sheet for absorbable
articles having excellent softness, bulkiness and body fluid
absorbability.
[0007] These nonwoven fabrics proposed above are prepared by
conjugate melt spinning of polymers having different MFR values,
i.e., different melt viscosities, but unfortunately these fabrics
involve a problem of unstable spinnability since filaments
discharged through a spinning nozzle tend to slant.
[0008] On the other hand, Japanese Patent Laid-Open Application No.
6-65849 discloses a process for preparing nonwoven fabrics which
involves the steps of melt spinning multi-component fibers of first
and second polymer components, elongating the spun fibers, cooling
the fibers so as to produce latent crimps, activating the latent
crimps and forming the crimped fibers in nonwoven webs. In this
process, a heat treatment is necessary during spinning for
activating the latent crimps. Furthermore, though use of polymers
having different melting points as the first and second polymer
components is disclosed, its specific disclosure is merely on the
combination use of different polymers of a higher melting
polypropylene as the first polymer component and a low melting
polyethylene as the second polymer component. In this combination,
at least only a part of the surface of multi-component fibers is
constructed with a low-melting polyethylene so that stable
spinnability, resistance to fuzzing of nonwoven fabrics, etc. tend
to be lost.
[0009] Japanese Patent Laid-Open Application No. 9-24196 further
discloses a nonwoven fabric for area fasteners, in which fibers
forming the nonwoven fabric are parallel conjugate fibers with
fiber components of different thermal shrinkage rates arranged in
parallel along the longitudinal thread direction or eccentric
core-sheath type conjugate fibers with the core component shifted
off-center. According to this proposal, the desired nonwoven
fabrics are prepared by making a nonwoven fabric web of latent
crimped fiber filament and then subjecting the filament to a
relaxation heat treatment at a temperature lower than the melting
point of the lowest melting point component in the longer
fiber-constituting polymer components thereby to activate the
latent crimps. This technique also requires a special apparatus for
the heat treatment to prepare a nonwoven fabric composed of crimped
conjugate fibers at a high speed in a large scale.
[0010] An object of the present invention is to provide a nonwoven
fabric comprising crimped conjugate fibers having excellent
bulkiness and softness as well as excellent spinnability and
fuzzing resistance, which can be produced by a conventional melt
spinning. Another object of the present invention is to provide a
nonwoven fabric laminate using said nonwoven fabric, to which water
impermeability and surface smoothness are further imparted.
DISCLOSURE OF THE INVENTION
[0011] According to the present invention, there is provided a
nonwoven fabric of a crimped conjugate fiber comprising a first
propylene-based polymer component and a second propylene-based
polymer component, in which
[0012] the first and second propylene-based polymer components are
arranged to have substantially different zones in the cross-section
of the crimped conjugate fiber and are extended continuously along
the longitudinal direction of the crimped conjugate fiber,
[0013] the second propylene-based polymer component forms at least
a part of the peripheral surface continuously along the
longitudinal direction of the crimped conjugate fiber,
[0014] the melting point of the first propylene-based polymer
component is higher by at least 20.degree. C. than the melting
point of the second propylene-based polymer component as determined
by a differential scanning calorimeter (DSC), and
[0015] the ratio of the first/second propylene-based polymer
components (by weight) is in the range of 50/50 to 5/95.
[0016] The ratio of the second to first propylene-based polymer
components described above in the melt flow rate (MFR: measurement
temperature at 230.degree. C. under a load of 2.16 kg), as
determined in accordance with ASTM D1238, is preferably in the
range of 0.8 to 1.2 (the second component/the first component).
[0017] It is also preferred that the crimped conjugate fiber
constituting the nonwoven fabric has at least two melting point
peaks for the crimped conjugate fiber as determined by DSC on the
first run, and the area for the lowest melting point peak is not
smaller than the area for each of the other higher melting point
peaks.
[0018] According to the present invention, it is a preferred
embodiment of the invention that the propylene polymer described
above is a propylene homopolymer or a propylene-ethylene random
copolymer, having 0 to 10 mol % of ethylene unit and MFR of 20 to
200 g/10 min.
[0019] According to the present invention, it is also a preferred
embodiment of the invention that the crimped conjugate fiber
described above is an eccentric core-sheath conjugate fiber
comprising the first propylene-based polymer component as the core
and the second propylene-based polymer component as the sheath.
[0020] According to the present invention, it is also a preferred
embodiment of the invention that the crimped conjugate fiber
described above is a side-by-side type conjugate fiber comprising
the first propylene-based polymer component and the second
propylene-based polymer component.
[0021] In the present invention, the nonwoven fabrics composed of
the crimped conjugate fibers are preferably fused by heat
embossing.
[0022] Preferably, the embossing above is carried out under
conditions of an emboss area percentage from 5 to 20% and a
non-emboss unit area of at least 0.5 mm.sup.2.
[0023] It is more preferred that the nonwoven fabric of the crimped
conjugate fibers is a spun-bonded nonwoven fabric prepared by
spun-bonding process.
[0024] According to the present invention, there is provided a
nonwoven fabric laminate of at least two-layer structure, at least
one of which layers is a nonwoven fabric of the crimped conjugate
fibers described above.
[0025] In the present invention, a preferred embodiment is that the
nonwoven fabric laminate comprises a nonwoven fabric composed of
the crimped conjugate fibers, in which a plurality of nonwoven
fabrics having different crimping degrees are laminated.
[0026] According to the present invention, it is a preferred
embodiment of the invention that in the nonwoven fabric laminate at
least one other layer making the laminate is a layer of a
melt-blown nonwoven fabric prepared by a melt-blowing process.
[0027] According to the present invention, it is also a preferred
embodiment of the invention that in the nonwoven fabric laminate at
least one other layer making the laminate is a layer of a
spun-bonded nonwoven fabric comprising microfibers prepared by a
spun-bonding process.
[0028] According to the present invention, it is also a preferred
embodiment of the invention that in the nonwoven fabric laminate at
least one other layer making the laminate is a permeable film
layer.
[0029] According to the present invention, there is provided a
disposable diaper using the nonwoven fabric of crimped conjugate
fibers or the nonwoven fabric laminate described above.
[0030] According to the present invention, there is provided a
sanitary napkin using the nonwoven fabric of crimped conjugate
fibers or the nonwoven fabric laminate described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a part of the emboss pattern used in EXAMPLES 1
through 6 and COMPARATIVE EXAMPLES 1 through 5, which will be later
described.
[0032] FIG. 2 is a part of the emboss pattern used in EXAMPLE 7
later described.
[0033] FIG. 3 is a part of the emboss pattern used in EXAMPLE 8
later described.
[0034] FIG. 4 is a melting point measurement curve determined by
DSC on the first run, with respect to the crimped conjugate fiber
obtained in EXAMPLE 2, which will be later described.
[0035] FIG. 5 is a melting point measurement curve determined by
DSC on the first run, with respect to the crimped conjugate fiber
obtained in EXAMPLE 4, which will be later described.
[0036] FIG. 6 is a melting point measurement curve determined by
DSC on the first run, with respect to the crimped conjugate fiber
obtained in COMPARATIVE EXAMPLE 4, which will be later
described.
BEST MODE FOR CARRYING OUT THE INVENTION
[0037] The nonwoven fabric of the crimped conjugate fibers
(hereinafter sometimes merely referred to as conjugate fibers) in
accordance with the present invention and the nonwoven fabric
laminate using the same will be described below in detail.
[0038] The crimped conjugate fibers used in the present invention
comprise a first propylene-based polymer component and a second
propylene-based polymer component. The first and second
propylene-based polymer components are arranged to have
substantially different zones in the cross-section of the crimped
conjugate fibers and are extended continuously along the
longitudinal direction of the crimped conjugate fibers; the second
propylene-based polymer component forms at least a part of the
peripheral surface, preferably at least 50% of the peripheral
surface, continuously along the longitudinal direction of the
crimped conjugate fibers.
[0039] Such a conjugate fiber specifically includes a core-sheath
type conjugate fiber, a side-by-side type conjugate fiber, a
sandwich type conjugate fiber and the like. Of these fibers,
preferred embodiments include a core-sheath type comprising the
first propylene-based polymer as the core part and the second
propylene-based polymer as the sheath part, preferably an eccentric
core-sheath conjugate fiber with the core/sheath shifted off-center
in the cross section of the fiber, and a side-by-side conjugate
fiber comprising the first propylene-based polymer part and the
second propylene-based polymer part. Herein, the eccentric
core-sheath conjugate fiber with the core shifted off-center
includes an eccentric type in which the core and sheath parts are
off-center and the core part is enclosed in the sheath part, and a
parallel type in which the core shifted off-center is not enclosed
in the sheath part.
[0040] The melting point of the first propylene-based polymer
component as determined by a differential scanning calorimeter
(DSC) is higher by at least 20.degree. C., preferably 20 to
60.degree. C., than the melting point of the second propylene-based
polymer component and the ratio of the first/second propylene-based
polymer components (by weight) is in the range of 50/50 to 5/95,
preferably 40/60 to 10/90, more preferably 30/70 to 10/90, which
are important requirements. Furthermore, the ratio of the two
components (the second component/the first component) described
above in the melt flow rate (MFR: measurement temperature at
230.degree. C. under a load of 2.16 kg) is preferably in the range
of 0.8 to 1.2, more preferably 0.9 to 1.1, as determined in
accordance with ASTM D1238.
[0041] In the present invention, the area ratio of the first
propylene-based polymer to the second propylene-based polymer in
the cross section of the conjugate fiber is almost equal to the
weight ratio in general.
[0042] By satisfying the conditions above, the conjugate fiber
becomes crimped and the nonwoven fabric composed of the fiber
provides an excellent bulky feeling. A preferred number of the
crimps is at least 10 crimps/25 mm, more preferably at least 20
crimps/25 mm, as measured in accordance with JIS L1015.
[0043] A small difference in MFR between the two components results
in good spinnability. A preferred spinnability in the present
invention refers to such a property that upon spinning the molten
polymers through a spinning nozzle, spun filaments are free from
fusion and filament break and can be spun stably.
[0044] In the present invention, the measurement of a melting point
by DSC is performed as follows. Using a device manufactured by
Perkin-Elmer Inc., the melting point is measured by filling a
sample in a measuring pan, heating once from 30.degree. C. to
200.degree. C. at a rate of 10.degree. C./min, holding the sample
at 200.degree. C. for 10 minutes, lowering the temperature to
30.degree. C. at a rate of 10.degree. C./min and then elevating the
temperature from 30.degree. C. to 200.degree. C. at a rate of
10.degree. C./min (measurement on the second run).
[0045] In the measurement of the conjugate fiber by DSC, the
melting point is measured on the first run using the same device by
filling a sample in a measuring pan, and elevating the temperature
from 30.degree. C. to 200.degree. C. at a rate of 10.degree.
C./min.
[0046] According to this method for measurement, the melting point
is obtained as the peak on the endothermic curve, whereby both the
melting point and the melting point peak area can be determined. In
the present invention, it is preferred that at least two melting
point peaks are present for the conjugate fiber determined by the
latter method on the first run and the area for the lowest melting
point peak is not smaller than the area for the other higher
melting point peaks. When the two melting point peaks overlap one
another, a peak excluding the affect of the other peak is estimated
from the figure of the highest peak to determine the area and the
estimated area can be compared to the area for the other peak.
[0047] Examples of the first and second propylene-based polymers
which constitute the conjugate fiber of the present invention
include a homopolymer of propylene and a copolymer of propylene as
a main structural unit component and one or more .alpha.-olefins
having 2 to 20 carbon atoms, preferably 2 to 8, such as ethylene,
1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc.
Of these polymers, preferred are a propylene homopolymer and a
propylene-ethylene random copolymer, containing 0 to 10 mol % of
ethylene unit and MFR of 20 to 200 g/10 min.
[0048] A combination of a propylene homopolymer as the first
propylene-based polymer and a random copolymer of propylene and a
small amount of ethylene as the second propylene-based polymer
containing not greater than 10 mol %, more preferably 2 to 10 mol %
of ethylene units, is advantageous especially because the nonwoven
fabric composed of the conjugate fibers having excellent bulkiness
and good softness can be obtained. The content of the ethylene
units can be determined by a conventional method for measuring
.sup.13C-NMR spectrum.
[0049] Preferably, the melting point of the first propylene-based
polymer is in the range of 120 to 175.degree. C. and the melting
point of the second propylene-based polymer is in the range of 110
to 155.degree. C. A difference in the melting point between the two
polymers is at least 20.degree. C., preferably 20.degree. C. to
60.degree. C., as stated above.
[0050] The propylene-based polymers described above can be produced
using a highly stereospecific polymer catalyst.
[0051] The nonwoven fabric composed of the crimped conjugate fiber
described above may be obtained by conventional conjugate melt
spinning without requiring any special device, and in particular,
it is preferable that said nonwoven fabric is a spun-bonded
nonwoven fabric produced by a spun-bonding process because of its
excellent productivity.
[0052] The spun-bonded nonwoven fabric can be produced as follows.
The first propylene-based polymer, which forms one zone of the
conjugate fiber, and the second propylene-based polymer, which
forms another zone of the conjugate fiber, are molten separately in
extruders. Each molten polymer is discharged from a spinneret with
bi-component fiber spinning nozzles constructed to discharge each
molten polymer so as to form a desired fiber structure. The
filaments thus spun are cooled with a cooling air. Then the
filaments are given tension by means of stretching air to have a
desired fineness. Next, the spun-filaments are collected on a
collection belt to deposit on a determined thickness and then
subjected to the processing of tangling. Examples of the tangling
processing include a method in which the fibers are entangled by
means of a needle punch, water jet, ultrasonic wave, etc.; a method
in which the fibers are fused by heat embossing or by passing hot
air through them.
[0053] In the present invention, the nonwoven fabric is preferably
prepared by heat fusion through the processing of embossing. The
emboss processing is carried out preferably under the conditions of
an emboss area percentage of 5 to 20%, more preferably 5 to 10%,
and a non-emboss unit area of at least 0.5 mm.sup.2, more
preferably 4 to 40 mm. Herein, the non-emboss unit area is used to
mean the largest area of a square which inscribes the emboss parts
at the smallest unit of the non-emboss part which is entirely
surrounded by the embossed parts. When the nonwoven fabric is
embossed under the conditions set forth above, the nonwoven fabric
can be made more bulky while maintaining its strength required. The
emboss area percentage and the non-emboss unit area can be varied
by changing an emboss pattern.
[0054] The fineness and basis weight of the nonwoven fabric are
appropriately chosen depending upon use but it is generally
preferred that the fineness is in the range of 0.5 to 5.0 deniers,
especially 0.5 to 3.0 deniers, and the basis weight is in the range
of 3 to 100 g/m.sup.2, especially 7 to 30 g/m.sup.2.
[0055] In the conjugate fiber of the present invention, other
components may also be incorporated, in addition to the
propylene-based polymers, as needed to the extent not impairing the
objects of the invention. Examples of these components include
known heat resistant stabilizers, weatherproof stabilizers, various
other stabilizers, antistatic agents, slip agents, anti-blocking
agents, anti-fogging agents, lubricants, dyes, pigments, natural
oil, synthetic oil, waxes, etc.
[0056] Examples of stabilizers include anti-aging agents such as
2,6-di-t-butyl-4-methylphenol (BHT), etc.; phenol type antioxidants
such as
tetrakis[methylene-3-(3,5-di-t-butyl4-hydroxyphenyl)propionate]methane-
, an alkyl ester of
.beta.-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid,
2,2'-oxamidobis
[ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, etc.; fatty
acid metal salts such as zinc stearate, calcium stearate, calcium
1,2-hydroxystearate, etc.; polyvalent alcohol fatty acid esters
such as glycerin monostearate, glycerin distearate, pentaerythritol
monostearate, pentaerythritol distearate, pentaerythritol
tristearate, etc.; and the like. These stabilizers may also be used
in combination.
[0057] Examples of lubricants are oleic amide, erucic amide,
stearic amide, etc.
[0058] The conjugate fiber may also contain fillers such as silica,
diatomite, alumina, titanium oxide, magnesium oxide, pumice
powders, pumice baltoons, aluminum hydroxide, magnesium hydroxide,
basic magnesium carbonate, dolomite, calcium sulfate, potassium
titanate, barium sulfate, calcium sulfite, talc, clay, mica,
asbestos, calcium silicate, montmorillonite, bentonite, graphite,
aluminum powders, molybdenum sulfide, etc.
[0059] The propylene-based polymers and the other optional
components used depending on necessity can be blended by known
methods.
[0060] The nonwoven fabrics composed of the crimped conjugate
fibers obtained as described above are excellent in bulkiness and
softness. In addition, the nonwoven fabrics have excellent
spinnability and good resistance to fuzzing, since polyethylene is
not used as the second component for constituting at least a part
of the fiber surface. For this reason, the nonwoven fabrics provide
excellent productivity, especially with less fuzzing in emboss
processing, which enables high speed processing.
[0061] The nonwoven fabric laminate in accordance with the present
invention comprises at least two-layer structure and at least one
of the layers is made of the nonwoven fabric composed of the
crimped conjugate fiber. The layers that constitute the laminate
may all be composed of the crimped conjugate fiber nonwoven fabric
alone, or may be composed of one or more layers of the crimped
conjugate fiber nonwoven fabric of the invention and one or more of
the other layers. Such a laminate can be produced by in-line
laminating the layers prior to the entangling processing of the
nonwoven fabric, or by off-line laminating after the entangling
processing.
[0062] In the in-line lamination, a nonwoven fabric layer is
preferred as the other layer to be laminated. Examples of the other
layer include layers composed of a spun-bonded nonwoven fabric, a
melt-blown nonwoven fabric, a nonwoven fabric obtained by carding
process, etc. Preferably, these layers are piled on the nonwoven
fabric of the crimped conjugate fiber prior to the processing of
entangling and heat fused under the embossing conditions described
above to integrally form a laminate. Accordingly, various polymers
can be employed as materials for the nonwoven fabrics to be
laminated in-line, so long as nonwoven fabrics are heat fusible
with the nonwoven fabric composed of the crimped conjugate fiber.
Of course, a nonwoven fabric composed of the crimped conjugate
fibers having different crimping degrees may also be laminated in a
similar manner.
[0063] Examples of the polymer that can be used for materials of
the nonwoven fabric as the other layer above in the nonwoven fabric
laminate of the present invention include polyolefin, polyester,
polyamide, polyurethane, etc.
[0064] Specifically, fibers of polypropylene, polyethylene or a
blend thereof are preferred as the polyolefin that are usable as
materials for the nonwoven fabric. It is particularly preferred to
use polypropylene fibers, in terms of spinnability, heat resistance
and heat fusion to the nonwoven fabric composed of the crimped
conjugate fiber.
[0065] Specifically, those similar to the first or second
propylene-based polymer, which constitutes the crimped conjugate
fiber, can be used as the polypropylene. Particularly when using
melt-blown nonwoven fabrics, it is preferred to use those having a
melt flow rate of 30 to 3000 g/10 min, especially about 400 to
about 1500 g/10 min. It is also preferred to use those having the
ratio Mw/Mn of a weight average molecular weight to a number
average molecular weight in the range of 2 to 6.
[0066] As the polyethylene that is usable as a nonwoven fabric
material for the other layer of the laminate described above, there
are, for example, a homopolymer of ethylene (which can be prepared
either by the high pressure process or by the low pressure process)
and a copolymer of ethylene and other .alpha.-olefin. Examples of
the other .alpha.-olefin in the copolymer include an .alpha.-olefin
having 2 to 20 carbon atoms such as propylene, 1-butene, 1-pentene,
1-hexene, 1-octene, 1-decene, 3-methyl-1-butene,
3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene,
4-methyl-1-hexene, etc. These other .alpha.-olefins may be
copolymerized alone or at least two of them.
[0067] Preferably, the polyethylene described above has a density
of 880 to 970 kg/m.sup.3, more preferably 910 to 965 kg/m.sup.3.
Furthermore, its melt flow rate is preferably in the range of 10 to
400 g/10 min, more preferably 15 to 250 g/10 min, as determined at
190.degree. C. under a load of 2160 g. Also, its ratio of the
weight average molecular weight to the number average molecular
weight, i.e. , Mw/Mn is preferably in the range of 1.5 to 4.
[0068] As the polyester nonwoven fabric material that is usable as
the other layer in the laminate described above, there are, for
example, an aromatic polyester having excellent strength, rigidity,
etc. and a biodegradable aliphatic polyester. Specific examples of
the aromatic polyester include polyethylene terephthalate,
polytrimethylene terephthalate, polytetramethylene terephthalate,
etc. Specific examples of the aliphatic polyester include
polycondensates of polyvalent carboxylic acids such as malonic
acid, succinic acid, glutaric acid, adipic acid, sebacic acid,
dodecanoic acid, malic acid, tartaric acid, citric acid, etc. and
polyvalent alcohols such as ethylene glycol, propylene glycol,
butanediol, hexanediol, glycerin, trimethylolpropane, etc.;
ring-opening polymers of lactides or caprolactones, etc.;
polycondensates of hydroxy acids such as lactic acid,
hydroxybutyric acid, hydroxyvaleric acid, etc.
[0069] Where the nonwoven fabric laminate of the present invention
is produced off-line, other layers to be laminated are not
particularly restricted, and layers composed of a knitted fabric, a
woven fabric, a nonwoven fabric, a film, etc. may be employed. Any
materials can be used for these other layers as long as they can be
laminated by the following lamination techniques. Such lamination
techniques include heat fusion such as emboss processing, fusion by
ultrasonic wave, etc., mechanical tangling such as a needle punch
or water jet, etc., a technique using adhesives such as a hot melt
adhesive, etc., and extrusion lamination when the other layer is in
the form of a film.
[0070] A preferred embodiment of the nonwoven fabric laminate of
the present invention comprises the aforesaid nonwoven fabric (a
spun-bonded nonwoven fabric is preferred) of the present invention,
which is composed of the crimped conjugate fiber, and a melt-blown
nonwoven fabric laminated thereon. According to this layer
structure, the nonwoven fabric laminate having both bulky feeling
and water impermeability can be obtained. Examples of the layer
structure in this case are a two layer structure of spun-bonded
nonwoven fabric (crimped conjugate fiber)/melt-blown nonwoven
fabric, a three layer structure of spun-bonded nonwoven fabric
(crimped conjugate fiber)/melt-blown nonwoven fabric/spun-bonded
nonwoven fabric (crimped conjugate fiber), and the like.
Preferably, the basis weight of the nonwoven fabric in each layer
to be laminated is in the range of 2 to 25 g/m.sup.2. In the
melt-blown nonwoven fabric described above, a diameter of the
constituent fiber is preferably in the range of 1 to 5 .mu.m.
[0071] Moreover, a preferred embodiment of the nonwoven fabric
laminate of the present invention comprises said nonwoven fabric (a
spun-bonded nonwoven fabric is preferred) of the present invention,
which is composed of the crimped conjugate fiber, and a spun-bonded
nonwoven fabric produced by a spun-bonding process laminated
thereon as a surface layer, which spun-bonded nonwoven fabric is
composed of microfibers (preferably having fineness of 0.8 to 2.5
deniers, more preferably 0.8 to 1.5 deniers). According to this
construction, the nonwoven fabric laminate having excellent
bulkiness and surface smoothness and improved water impermeability
can be obtained. Examples of the layer structure of the laminate in
this case include a two layer structure comprising spun-bonded
nonwoven fabric (microfibers)/spun-bonded nonwoven fabric (crimped
conjugate fiber); a three layer structure comprising spun-bonded
nonwoven fabric (microfibers)/spun-bonded nonwoven fabric (crimped
conjugate fiber)/spun-bonded nonwoven fabric (microfibers),
comprising spun-bonded nonwoven fabric (microfibers)/spun-bonded
nonwoven fabric (crimped conjugate fiber)/melt-blown nonwoven
fabric, etc.; a four or five layer structure comprising spun-bonded
nonwoven fabric (microfibers)/spun-bonded nonwoven fabric (crimped
conjugate fiber)/melt-blown nonwoven fabric/spun-bonded nonwoven
fabric (microfibers), comprising spun-bonded nonwoven fabric
(microfibers)/spun-bonded nonwoven fabric (crimped conjugate
fiber)/melt-blown nonwoven fabric/spun-bonded nonwoven fabric
(crimped conjugate fiber)/spun-bonded nonwoven fabric
(microfibers), and the like. Preferably, the basis weight of the
nonwoven fabric in each layer to be laminated is in the range of 2
to 25 g/m.sup.2. The spun-bonded nonwoven fabric made from
microfibers described above is obtained by controlling the
manufacturing conditions in the spun-bonding process.
[0072] A preferred embodiment of the nonwoven fabric laminate of
the invention further includes a laminate comprising the nonwoven
fabric composed of the crimped conjugate fiber described above and
an air permeable film layer laminated thereon. The air permeable
film includes a film composed of a thermoplastic elastomer having
moisture permeability, e.g., polyurethane elastomer, polyester
elastomer, polyamide elastomer, etc. Also, a polyolefin-based
porous film, made by stretching the polyolefin added with a
fillers, etc., may be employed. As such an air permeable film, it
is preferred to use a film having a basis weight of approximately 2
to 40 g/m.sup.2. Such a nonwoven fabric laminate can be obtained as
a cloth-like conjugate material that has extremely high water
impermeability and also has air permeability (moisture
permeability), bulky feeling, etc.
[0073] The nonwoven fabric composed of the crimped conjugate fiber
of the present invention which can be spun by conventional melt
spinning techniques can provide an excellent bulkiness, softness
and extensibility as well as excellent spinnability and fuzzing
resistance. To the nonwoven fabric laminate using said nonwoven
fabric, various properties, e.g., water impermeability, surface
smoothness, fluid flow handling properties, etc., can be imparted
depending upon a nonwoven fabric to be laminated. Therefore, said
nonwoven fabric can be advantageously used alone or in a form of
laminate with other materials, as side gathering, back sheets, top
sheets or waist materials for disposable diapers or sanitary
napkins, and may also be preferably applicable to household
materials such as wipers, etc. and to industrial materials such as
an oil blotter, etc.
EXAMPLES
[0074] Hereinafter the present invention will be described in more
detail with reference to EXAMPLES below but is not deemed to be
limited thereto.
[0075] Measurement and evaluation of physical properties in
EXAMPLES and COMPARATIVE EXAMPLES are as follows.
[0076] (1) Number of Crimps
[0077] The number of crimps was measured in accordance with JIS
L1015.
[0078] (2) Porosity (Evaluation of Bulkiness)
[0079] Porosity of a nonwoven fabric was calculated by the
following equation, wherein the basis weight and thickness of the
nonwoven fabric are W [g/m.sup.2] and L [.mu.m] and the density of
its material is d [g/cm.sup.3]:
Porosity [vol %]={(L-(W/d))/L}.times.100
[0080] In the equation, the thickness of the nonwoven fabric is a
value obtained by putting a load of 20 g/cm.sup.2 on 10-ply sheet
of the nonwoven fabric, allowing to stand for 10 seconds, then
measuring the thickness and dividing the thickness obtained by 10;
and the density of the material is a density of the molded article
obtained by compression molding of the nonwoven fabric at 200 to
230.degree. C. (in accordance with ASTM D1505).
[0081] (3) KOSHI (Stiffness) Value (Evaluation of Softness)
[0082] The tensile, shear, compression, surface wear and bending
tests were conducted by use of the KES-FB system available from
Kato Tech Co., Ltd. using knit high-sensitivity test conditions.
The KOSHI value was determined by performing a calculation using
the results of the tests as parameters under knit underwear
(summer) conditions. The KOSHI value indicates that as the value
decreases, softness improves.
[0083] (4) FUKURAMI Value (Evaluation of Bulkiness)
[0084] The tensile, shear, compression, surface wear and bending
tests were conducted by use of the KES-FB system available from
Kato Tech Co., Ltd. using knit high-sensitivity test conditions.
The FUKURAMI value was determined by performing a calculation using
the results of the tests as parameters under knit underwear
(summer) conditions. The FUKURAMI value indicates that as the value
increases, the thickness increases.
[0085] (5) Tensile Elongation
[0086] The tensile test was performed with a nonwoven fabric test
piece of 25 mm in width at a distance of 100 mm between chucks
under the conditions of a stress rate of 100 mm/min. A rate of the
test piece elongated at the maximum tensile load was made its
tensile elongation (%).
[0087] (6) Fuzzing (Brushing Test) (Evaluation of Abrasion
Resistance)
[0088] In accordance with JIS L1076, 3 pieces were prepared from
nonwoven fabric in a size of 25 cm in the machine direction (MD) of
the nonwoven fabric and 20 cm in the cross direction (CD), mounted
on sample holders of a brush and sponge tester, pressed against a
felt instead of the brush and sponge, and rubbed for 5 minutes at a
speed of 58 min.sup.-1 (rpm). After rubbing, the samples were
visually observed for evaluation. The results of the evaluation
were expressed by the following criteria, indicating that as the
numerical value increases, fuzzing becomes less.
[0089] 5: no fuzzing
[0090] 4: fuzzing was little observed
[0091] 3: some fuzzing was observed
[0092] 2: fuzzing was intensely observed
[0093] 1: fuzzing was intense and rips were observed
[0094] (7) Water Impermeability
[0095] The water impermeability was measured in accordance with JIS
L1072A (low water pressure method). Four test pieces, each having a
size of approximately 15.times.15 cm, were prepared and mounted on
a waterproof tester (manufactured by Tester Sangyo K.K.) in such a
manner that water was in contact with the surface of the test
piece. A level device charged with water at ambient temperature was
elevated at a rate of 60.+-.3 cm/min to apply a hydraulic pressure
to the test piece. The water level when water leaked from 3 places
at the back surface of the test piece was measured and the pressure
was determined at that time to be water impermeability.
Example 1
[0096] Using a propylene homopolymer having the melting point of
162.degree. C. and MFR of 60 g/10 min (as measured at a temperature
of 230.degree. C. under a load of 2.16 kg in accordance with ASTM
D1238; hereinafter the same unless otherwise indicated) as the
first propylene-based polymer and as the second propylene-based
polymer a propylene-ethylene random copolymer having the melting
point of 142.degree. C., MFR of 60 g/10 min and the ethylene unit
content of 4.0 mol %, conjugate melt-spinning was carried out by a
spun-bonding process to deposit an eccentric core-sheath type
conjugate fiber having the core made from the propylene homopolymer
and the sheath made from the propylene-ethylene random copolymer
(the ratio of the core to the sheath was 20/80 by weight) on the
collection surface. The conjugate fiber was then subjected to
emboss processing at an emboss temperature of 110.degree. C. with
an emboss pattern (emboss area percentage: 18.2%, non-emboss unit
area: 0.74mm.sup.2) shown in FIG. 1. Thus, a nonwoven fabric
composed of crimped conjugate fibers having the basis weight of 25
g/m.sup.2 and the fineness of the constituent fiber of 2.5 deniers
was produced. The details of the propylene-based polymer components
are shown in TABLE 1 and the measurement/evaluation results on the
nonwoven fabric obtained are shown in TABLE 2.
Example 2
[0097] A nonwoven fabric composed of crimped conjugate fibers
having the basis weight of 25 g/m.sup.2 and the fineness of the
constituent fiber of 2.4 deniers was produced in a manner similar
to EXAMPLE 1, except that a propylene-ethylene random copolymer
having the melting point of 138.degree. C., MFR of 60 g/10 min and
the ethylene unit content of 5.0 mol % was used as the second
propylene-based polymer and the emboss temperature was changed to
100.degree. C. The details of the propylene-based polymer
components are shown in TABLE 1 and the measurement/evaluation
results on the nonwoven fabric obtained are shown in TABLE 2.
[0098] The melting point peaks of the thus obtained conjugate
fibers by DSC in the first run were observed at 141.5.degree. C.,
156.2.degree. C. and 164.8.degree. C., and the peak area
percentages were 80%, 10% and 10%, respectively. The measurement
curve by DSC is shown in FIG. 4.
Example 3
[0099] A nonwoven fabric composed of crimped conjugate fibers
having the basis weight of 25 g/m.sup.2 and the fineness of the
constituent fiber of 2.4 deniers was produced in a manner similar
to EXAMPLE 2, except that the eccentric core-sheath type conjugate
fiber had the core/sheath=30/70 (by weight ratio). The details of
the propylene-based polymer components are shown in TABLE 1 and the
measurement/evaluation results on the nonwoven fabric obtained are
shown in TABLE 2.
Example 4
[0100] A nonwoven fabric composed of crimped conjugate fibers
having the basis weight of 25 g/m.sup.2 and the fineness of the
constituent fiber of 2.4 deniers was produced in a manner similar
to EXAMPLE 2, except that the eccentric core-sheath type conjugate
fiber had the core/sheath=50/50 (by weight ratio). The details of
the propylene-based polymer components are shown in TABLE 1 and the
measurement/evaluation results on the nonwoven fabric obtained are
shown in TABLE 2.
[0101] The melting point peaks of the thus obtained conjugate
fibers by DSC in the first run were observed at 141.0.degree. C.,
157.5.degree. C. and 164.7.degree. C., and the peak area
percentages were 40%, 40% and 20%, respectively. The measurement
curve by DSC is shown in FIG. 5.
Example 5
[0102] A nonwoven fabric composed of crimped conjugate fibers
having the basis weight of 25 g/m.sup.2 and the fineness of the
constituent fiber of 2.5 deniers was produced in a manner similar
to EXAMPLE 1, except that a propylene-ethylene random copolymer
having the melting point of 124.degree. C., MFR of 60 g/10 min and
the ethylene unit content of 8.5 mol % was used as the second
propylene-based polymer and the emboss temperature was changed to
95.degree. C. The details of the propylene-based polymer components
are shown in TABLE 1 and the measurement/evaluation results on the
nonwoven fabric obtained are shown in TABLE 2.
Example 6
[0103] A nonwoven fabric composed of crimped conjugate fibers
having the basis weight of 25 g/m.sup.2 and the fineness of the
constituent fiber of 2.4 deniers was produced in a manner similar
to EXAMPLE 2, except that the emboss pattern shown in FIG. 1 and
having the emboss area percentage of 10.2% and the non-emboss unit
area of 1.04 mm.sup.2 was used. The details of the propylene-based
polymer components are shown in TABLE 1 and the
measurement/evaluation results on the nonwoven fabric obtained are
shown in TABLE 2.
Example 7
[0104] A nonwoven fabric composed of crimped conjugate fibers
having the basis weight of 25 g/m.sup.2 and the fineness of the
constituent fiber of 2.4 deniers was produced in a manner similar
to EXAMPLE 2, except that the emboss pattern shown in FIG. 2 and
having the emboss area percentage of 6.9% and the non-emboss unit
area of 4.56 mm.sup.2 was used. The details of the propylene-based
polymer components are shown in TABLE 1 and the
measurement/evaluation results on the nonwoven fabric obtained are
shown in TABLE 2.
Example 8
[0105] A nonwoven fabric composed of crimped conjugate fibers
having the basis weight of 25 g/m.sup.2 and the fineness of the
constituent fiber of 2.4 deniers was produced in a manner similar
to EXAMPLE 2, except that the emboss pattern shown in FIG. 3 and
having the emboss area percentage of 9.7% and the non-emboss unit
area of 26.40 mm.sup.2 was used. The details of the propylene-based
polymer components are shown in TABLE 1 and the
measurement/evaluation results on the nonwoven fabric obtained are
shown in TABLE 2.
Comparative Example 1
[0106] Using a propylene homopolymer having the melting point of
162.degree. C. and MFR of 30 g/10 min and a medium density
polyethylene having the melting point of 120.degree. C. and MFR of
27 g/10 min (as measured at a temperature of 190.degree. C. under a
load of 2.16 kg by a modification of ASTM D1238), conjugate
melt-spinning was carried out by a spun-bonding process to deposit
an eccentric core-sheath type conjugate fiber having the core made
from the propylene homopolymer and the sheath made from the medium
density polyethylene (the ratio of the core to the sheath was 50/50
by weight) on the collection surface. The conjugate fiber was then
subjected to emboss processing at an emboss temperature of
115.degree. C. with an emboss pattern (emboss area percentage:
18.2%, non-emboss unit area: 0.74 mm.sup.2) shown in FIG. 1 to
produce a spun-bonded nonwoven fabric composed of conjugate fibers
having the basis weight of 25 g/m.sup.2 and the fineness of the
constituent fiber of 2.4 deniers. The spinnability of the conjugate
fibers was not good and fused or snapped filaments were observed.
The details of the propylene-based polymer components are shown in
TABLE 1 and the measurement/evaluation results on the nonwoven
fabric obtained are shown in TABLE 2.
Comparative Example 2
[0107] Using a propylene homopolymer (PP-1) having the melting
point of 162.degree. C. and MFR of 30 g/10 min and a propylene
homopolymer (PP-2) having the melting point of 162.degree. C. and
MFR of 60 g/10 min, conjugate melt-spinning was carried out by a
spun-bonding process to deposit an eccentric core-sheath type
conjugate fiber having the core made from the propylene homopolymer
(PP-1) and the sheath made from the propylene homopolymer (PP-2)
(the ratio of the core to the sheath was 10/90 by weight) on the
collection surface. The conjugate fiber was then subjected to
emboss processing at an emboss temperature of 125.degree. C. with
an emboss pattern (emboss area percentage: 18.2%, non-emboss
unit-area: 0.74 mm.sup.2) shown in FIG. 1 to produce a spun-bonded
nonwoven fabric composed of conjugate fibers having the basis
weight of 25 g/m.sup.2 and the fineness of the constituent fiber of
2.5 deniers. The spinnability of the conjugate fibers was not good
and fused or snapped filaments were observed. The details of the
propylene-based polymer components are shown in TABLE 1 and the
measurement/evaluation results on the nonwoven fabric obtained are
shown in TABLE 2.
Comparative Example 3
[0108] A nonwoven fabric composed of conjugate fibers having the
basis weight of 25 g/m.sup.2 and the fineness of the constituent
fiber of 2.5 deniers was produced in a manner similar to EXAMPLE 1,
except that the eccentric core-sheath type conjugate fiber had the
core/sheath=80/20 (by weight ratio) and the emboss temperature was
changed to 120.degree. C. The details of the propylene-based
polymer components are shown in TABLE 1 and the
measurement/evaluation results on the nonwoven fabric obtained are
shown in TABLE 2.
Comparative Example 4
[0109] A nonwoven fabric composed of conjugate fibers having the
basis weight of 25 g/m.sup.2 and the fineness of the constituent
fiber of 2.5 deniers was produced in a manner similar to EXAMPLE 2,
except that the eccentric core-sheath type conjugate fiber had the
core/sheath=80/20 (by weight ratio) and the emboss temperature was
changed to 120.degree. C. The details of the propylene-based
polymer components are shown in TABLE 1 and the
measurement/evaluation results on the nonwoven fabric obtained are
shown in TABLE 2.
[0110] The melting point peaks of the thus obtained conjugate
fibers by DSC in the first run were observed at 141.2.degree. C.,
158.3.degree. C. and 166.5.degree. C., and the peak area
percentages were 15%, 55% and 30%, respectively. The measurement
curve by DSC is shown in FIG. 6.
Comparative Example 5
[0111] Melt-spinning was carried by the spun-bonding process in a
manner similar to EXAMPLE 1, except for using the propylene
homopolymer alone, which was used as the first propylene-based
polymer in EXAMPLE 1, to form a spun-bonded nonwoven fabric web
having the fineness of 2.5 deniers and the basis weight of 25
g/m.sup.2 on the collection surface. The nonwoven fabric web was
subjected to emboss processing under the same conditions as in
EXAMPLE 1 to prepare a spun-bonded nonwoven fabric. The details of
the propylene-based polymer components are shown in TABLE 1 and the
measurement/evaluation results on the nonwoven fabric obtained are
shown in TABLE 2.
1 TABLE 1 Melting Emboss pattern First component (1) Second
component (2) point Emboss Non- Melting MFR Ethylene Melting MFR
Ethylene difference MFR Weight area emboss point (g/ content point
(g/ content [(1) - (2)] ratio ratio percentage unit area Polymer
(.degree. C.) 10 min) (mol %) Polymer (.degree. C.) 10 min) (mol %)
(.degree. C.) (1)/(2) (1)/(2) (%) (mm.sup.2) Ex. 1 Homo 162 60 0
Random 142 60 4.0 20 1 20/80 18.2 0.74 PP PP Ex. 2 Homo 162 60 0
Random 138 60 5.0 24 1 20/80 18.2 0.74 PP PP Ex. 3 Homo 162 60 0
Random 138 60 5.0 24 1 30/70 18.2 0.74 PP PP Ex. 4 Homo 162 60 0
Random 138 60 5.0 24 1 50/50 18.2 0.74 PP PP Ex. 5 Homo 162 60 0
Random 124 60 8.5 38 1 20/80 18.2 0.74 PP PP Ex. 6 Homo 162 60 0
Random 138 60 5.0 24 1 20/80 10.2 1.04 PP PP Ex. 7 Homo 162 60 0
Random 138 60 5.0 24 1 20/80 6.9 4.56 PP PP Ex. 8 Homo 162 60 0
Random 138 60 5.0 24 1 20/80 9.7 26.40 PP PP Comp. Homo 162 30 0
MDPE 120 27 -- 42 0.9 50/50 18.2 0.74 Ex. 1 PP Comp. Homo 162 30 0
Homo PP 162 60 0 0 2 10/90 18.2 0.74 Ex. 2 PP Comp. Homo 162 60 0
Random 142 60 4.0 20 1 80/20 18.2 0.74 Ex. 3 PP PP Comp. Homo 162
60 0 Random 138 60 5.0 24 1 80/20 18.2 0.74 Ex. 4 PP PP Comp. Homo
162 60 0 -- -- -- -- -- -- 100/0 18.2 0.74 Ex. 5 PP Homo PP:
Propylene homopolymer, Random PP: Propylene-ethylene random
copolymer, MDPE: Middle density polyethylene
[0112]
2 TABLE 2 Number of Basis Tensile Fineness crimps weight Thickness
Density Porosity KOSHI elongation (denier) (No./25 mm) (g/m.sup.2)
(.mu.m) (g/cm.sup.3) (vol. %) value (MD) (%) Fuzzing Spinnability
Ex. 1 2.5 11 25 230 0.91 88 10.3 70 5 Excellent Ex. 2 2.4 70 25 270
0.91 90 8.5 120 5 Excellent Ex. 3 2.4 55 25 260 0.91 89 9 110 5
Excellent Ex. 4 2.4 12 25 250 0.91 89 10 90 5 Excellent Ex. 5 2.5
65 25 230 0.91 88 7.5 130 5 Excellent Ex. 6 2.4 70 25 260 0.91 89
8.2 110 5 Excellent Ex. 7 2.4 70 25 300 0.91 91 8.1 130 5 Excellent
Ex. 8 2.4 70 25 330 0.91 92 8 130 5 Excellent Comp. 2.4 10 25 200
0.91 87 9 150 1 No good Ex. 1 Comp. 2.5 80 25 350 0.91 92 10.5 180
5 No good Ex. 2 Camp. 2.5 6 25 240 0.91 89 12 100 5 Excellent Ex. 3
Comp. 2.5 5 25 230 0.91 88 11.5 80 5 Excellent Ex. 4 Comp. 2.5
5> 25 200 0.91 87 13 50 5 Excellent Ex. 5
[0113] In COMPARATIVE EXAMPLE 1, polyethylene was used as the
second component and as a result, the spinnability was not good and
fuzzing resistance decreased. In COMPARATIVE EXAMPLE 2, the
propylene homopolymers having no difference in the melting point
between the first and second components but having greatly
different MFR values were used so that crimped fibers were obtained
but the spinnability was not good. In COMPARATIVE EXAMPLES 3 and 4,
the content of the first component was larger than that of the
second component so that the KOSHI value increased to make softness
worse and the number of crimps also decreased.
Example 9
[0114] Using a propylene homopolymer having MFR of 60 g/10 min as a
lower layer of a nonwoven fabric laminate, melt-spinning was
carried out by a spun-bonding process to form a spun-bonded
nonwoven fabric web having the fineness of 2.4 deniers and the
basis weight of 8 g/m.sup.2 on the collection surface. Then, using
a propylene homopolymer having the melting point of 162.degree. C.
and MFR of 60 g/10 min as the first propylene-based polymer and as
the second propylene-based polymer a propylene-ethylene random
copolymer having the melting point of 138.degree. C., MFR of 60
g/10 min and the ethylene unit content of 5.0 mol %, conjugate
melt-spinning was carried out by a spun-bonding process to deposit
as an upper layer a nonwoven fabric web composed of the eccentric
core-sheath type crimped conjugate fiber (fineness of 2.4 deniers)
of 16 g/m.sup.2 in the basis weight, having the core made from the
propylene homopolymer and the sheath made from the
propylene-ethylene random copolymer (the ratio of the core to the
sheath was 20/80 by weight) in-line on the spun-bonded nonwoven
fabric web described above, which was then subjected to emboss
processing at an emboss temperature of 110.degree. C. with an
emboss pattern (emboss area percentage: 9.7%, non-emboss unit area:
26.4 mm.sup.2) shown in FIG. 3. Thus, a nonwoven fabric laminate
(the total basis weight of 24 g/m.sup.2) was produced. The
measurement results of the nonwoven fabric laminate obtained are
shown in TABLE 3.
Example 10
[0115] A nonwoven fabric laminate was produced in a manner similar
to EXAMPLE 9, except that the melt-spinning was carried out by a
spun-bonding process using a propylene homopolymer having MFR of 60
g/10 min as a lower layer of a nonwoven fabric laminate to form a
spun-bonded nonwoven fabric web having the fineness of 1.2 deniers
and the basis weight of 8 g/m.sup.2 on the collection surface. The
measurement results of the nonwoven fabric laminate obtained are
shown in TABLE 3.
Example 11
[0116] The same spun-bonded nonwoven fabric web as that of EXAMPLE
9 was formed on the collection surface as a lower layer of a
nonwoven fabric laminate. Then, using the same propylene
homopolymer and the propylene ethylene random copolymer as those of
EXAMPLE 9, a nonwoven fabric web composed of the same crimped
conjugate fiber as that of EXAMPLE 9 except the basis weight of 8
g/m.sup.2, was deposited in-line on the spun-bonded nonwoven fabric
web as an intermediate layer. A spun-bonded nonwoven fabric web was
further deposited in-line on the nonwoven fabric web composed of
the crimped conjugate fibers described above as an upper layer
under the same conditions as those of the lower layer. The laminate
was subjected to emboss processing under the same conditions as in
EXAMPLE 9 to produce the nonwoven fabric laminate (the total basis
weight of 24 g/m.sup.2). The measurement results of the nonwoven
fabric laminate obtained are shown in TABLE 3.
Example 12
[0117] The same spun-bonded nonwoven fabric web as that of EXAMPLE
10 was formed on the collection surface as a lower layer in a
nonwoven fabric laminate. Then, using the same propylene
homopolymer and the propylene ethylene random copolymer as those of
EXAMPLE 9, a nonwoven fabric web composed of the same crimped
conjugate fiber as that of EXAMPLE 9 except the basis weight of 8
g/m.sup.2, was deposited in-line on the spun-bonded nonwoven fabric
web as an intermediate layer. A spun-bonded nonwoven fabric web was
further deposited in-line on the nonwoven fabric web composed of
the crimped conjugate fibers described above as an upper layer
under the same conditions as those of the lower layer. The laminate
was subjected to emboss processing under the same conditions as in
EXAMPLE 9 to produce the nonwoven fabric laminate (the total basis
weight of 24 g/m.sup.2). The measurement results of the nonwoven
fabric laminate obtained are shown in TABLE 3.
Example 13
[0118] A nonwoven fabric laminate (the total basis weight of 24
g/m.sup.2) was produced in a manner similar to EXAMPLE 9, except
that a propylene homopolymer having MFR of 1000 g/10 min was used
as a lower layer in a nonwoven fabric laminate and the
melt-spinning was conducted by a melt-blown process to form the
melt-blown nonwoven fabric having the mean fiber diameter of 3
.mu.m and the basis weight of 8 g/m.sup.2 on the collection
surface. The measurement results of the nonwoven fabric laminate
obtained are shown in TABLE 3.
Example 14
[0119] The same melt-blown nonwoven fabric as that of EXAMPLE 13
was formed on the collection surface as a lower layer of a nonwoven
fabric laminate. Then, using the same propylene homopolymer and the
propylene ethylene random copolymer as those of EXAMPLE 9, a
nonwoven fabric composed of the same crimped conjugate fiber as
that of EXAMPLE 9 except the basis weight of 8 g/m.sup.2, was
deposited in-line on the melt-blown nonwoven fabric as an
intermediate layer. The same spun-bonded nonwoven fabric web as the
lower layer of EXAMPLE 10 was further deposited in-line on the
nonwoven fabric composed of the crimped conjugate fibers described
above as an upper layer. The laminate was subjected to emboss
processing under the same conditions as in EXAMPLE 9 to produce the
nonwoven fabric laminate (the total weight of 24 g/m.sup.2). The
measurement results of the nonwoven fabric laminate obtained are
shown in TABLE 3.
Comparative Example 6
[0120] Using the same propylene homopolymer as the lower layer of
EXAMPLE 9, the melt-spinning was conducted by a spun-bonding
process to form the spun-bonded nonwoven fabric having the fineness
of 2.4 deniers and the basis weight of 24 g/m.sup.2 on the
collection surface. The nonwoven fabric web was then subjected to
emboss processing under the same conditions as in EXAMPLE 9 to
produce the spun-bonded nonwoven fabric. The measurement results of
the nonwoven fabric obtained are shown in TABLE 3.
Comparative Example 7
[0121] Using the same propylene homopolymer as the lower layer of
EXAMPLE 10, the melt-spinning was carried out by a spun-bonding
process to form the spun-bonded nonwoven fabric web having the
fineness of 1.2 deniers and the basis weight of 24 g/m.sup.2 on the
collection surface. The nonwoven fabric web was then subjected to
emboss processing under the same conditions as in EXAMPLE 9 to
produce the spun-bonded nonwoven fabric. The measurement results of
the nonwoven fabric obtained are shown in TABLE 3.
Example 15
[0122] Using a propylene homopolymer having the melting point of
162.degree. C. and MFR of 60 g/10 min and a propylene-ethylene
copolymer having the melting point of 138.degree. C., MFR of 60
g/10 min and the ethylene unit content of 5.0 mol %, conjugate
melt-spinning was carried out by a spun-bonding process, and the
resulting web of eccentric core-sheath type conjugate fibers
(fineness of 2.4 deniers) having the core made from the propylene
homopolymer and the sheath made from the propylene-ethylene random
copolymer (the core/sheath ratio=20/80 by weight) was then
subjected to emboss processing at an emboss temperature of
110.degree. C. with an emboss pattern (emboss area percentage:
9.7%, non-emboss unit area: 26.4 mm.sup.2) shown in FIG. 3. Thus, a
nonwoven fabric composed of crimped conjugate fibers having the
basis weight of 20 g/m.sup.2 was produced.
[0123] A mixture of 100 parts by weight of polyethylene (density of
0.920 g/cm.sup.3, MFR of 2 g/10 min) and 60 parts by weight of
calcium carbonate as a filler was formed into a film. The film was
then monoaxially stretched to form a polyethylene porous film
having the basis weight of 15 g/m.sup.2. The nonwoven fabric
described above was bonded to the porous film described above with
1.5 g/m.sup.2 of polyolefin-based hot melt adhesive to produce the
nonwoven fabric laminate (the total basis weight of 36.5
g/m.sup.2). The measurement results of the nonwoven fabric
laminate-obtained are shown in TABLE 3.
Comparative Example 8
[0124] A nonwoven fabric laminate composed of a nonwoven fabric/a
porous film was produced in a manner similar to EXAMPLE 15, except
that a propylene homopolymer having the melting point of
162.degree. C. and MFR of 60 g/10 min was used as a nonwoven fabric
instead of the nonwoven fabric of the crimped conjugate fibers in
EXAMPLE 15, the melt-spinning was carried out by a spun-bonding
process, and the web thus obtained having the fineness of 2.4
deniers was then subjected to emboss processing at an, emboss
temperature of 135.degree. C. with an emboss pattern (emboss area
percentage: 9.7%, non-emboss unit area: 26.4 mm.sup.2) shown in
FIG. 3 to produce the nonwoven fabric having the basis weight of 20
g/m.sup.2. The measurement results are shown in TABLE 3.
Comparative Example 9
[0125] A mixture of 100 parts by weight of polyethylene (density of
0.920 g/cm.sup.3, MFR of 6 g/10 min) and 60 parts by weight of
calcium carbonate as a filler was formed into a film. The film was
then monoaxially stretched to form a polyethylene porous film
having the basis weight of 20g/m.sup.2. The measurement results of
the film are shown in TABLE 3.
3 TABLE 3 Layer structure of nonwoven fabric Basis Water Upper
Intermediate Lower Bonding weight KES Fuzzing Impermeability layer
Layer layer method (g/m.sup.2) Koshi Fukurami (mg/cm.sup.2) (mm
H.sub.2O) Ex. 9 Crimped -- 2.4d fiber Heat emboss 24 10.4 0.9 5 75
fiber 8 g/m.sup.2 Area % = 16 g/m.sup.2 9.7% Ex. 10 Crimped -- 1.2d
fiber Heat emboss 24 10.2 0.8 5 80 fiber 8 g/m.sup.2 Area % = 16
g/m.sup.2 9.7% Ex. 11 2.4d fiber Crimped fiber 2.4d fiber Heat
emboss 24 12.3 0.1 5 95 8 g/m.sup.2 8 g/m.sup.2 8 g/m.sup.2 Area %
= 9.7% Ex. 12 1.2d fiber Crimped fiber 1.2d fiber Heat emboss 24
12.4 0.1 5 110 8 g/m.sup.2 8 g/m.sup.2 8 g/m.sup.2 Area % = 9.7%
Ex. 13 Crimped -- 3 .mu.m fiber Heat emboss 24 11.1 1.1 5 350 fiber
8 g/m.sup.2 Area % = 16 g/m.sup.2 9.7% Ex. 14 1.2d fiber Crimped
fiber 3 .mu.m fiber Heat emboss 24 12.1 0.5 5 360 8 g/m.sup.2 8
g/m.sup.2 8 g/m.sup.2 Area % = 9.7% Comp. 2.4d fiber -- -- Heat
emboss 24 13.7 -0.6 5 80 Ex. 6 24 g/m.sup.2 Area % = 9.7% Comp.
1.2d fiber -- -- Heat emboss 24 13.6 -0.8 5 120 Ex. 7 24 g/m.sup.2
Area % = 9.7% Ex. 15 Crimped -- Porous film PO hot melt 36.5 11.0
1.2 5 >1500 fiber 15 g/m.sup.2 1.5 g/m.sup.2 Comp. 2.4d fiber --
Porous film PO hot melt 36.5 13.9 -0.4 5 >1500 Ex. 8 20
g/m.sup.2 15 g/m.sup.2 1.5 g/m.sup.2 Comp. Porous film -- -- -- 20
4.1. -3.0 5 >1500 Ex. 9 20 g/m.sup.2
INDUSTRIAL APPLICABILITY
[0126] The nonwoven fabric composed of the crimped conjugate fiber
of the present invention has excellent bulkiness, softness and
extensibility, as well as excellent spinnability and fuzzing
resistance, and may be advantageously used for applications
including sanitary goods such as disposable diapers and sanitary
napkins.
[0127] The nonwoven fabric laminate using the nonwoven fabric
composed of the crimped conjugate fiber may be advantageously used
also for applications such as household and industrial materials,
in addition to the sanitary goods described above, since various
properties can be imparted to the laminate depending upon other
layers to be laminated thereon.
* * * * *