* DESCRIPTION
TITLE OF INVENTION: SPUNBONDED NONWOVEN FABRICS
TECHNICAL FIELD
5 [OOOl]
The present invention relates to spunbonded nonwoven
fabrics formed of thermoplastic resin hollow fibers,
preferably propylene polymer hollow fibers, which exhibit
excellent strength, lightweight properties, flexibility,
10 dispersion properties, shielding properties and forming
properties and are suitable as sanitary materials.
BACKGROUND ART
[0002]
15 Nonwoven fabrics of thermoplastic resin fibers,
typically polypropylene nonwoven fabrics, have excellent
breathability, flexibilityandlightweightproperties andhave
recently been used widely in various applications. Thus, the
nonwoven fabrics require specific properties in accordance
20 with the applications, and demands have been placed on the
improvements of such properties.
In particular, disposable diapers have recently come to
be heavily used in emerging countries, most typically China,
due to population growth and have good market potentials in
* these countries. On the other hand, an increase in C02
emissions associated with the large consumption of disposable
diapers is becoming a serious environmental problem. In order
to suppress the worldwide increase in C02 emissions,
5 plant-derived materials have been studied. However, the
results are unsuccessful in terms of quality, costs and
productivity. Meanwhile, manufacturers of disposable diapers
have worked on saving COz emissions by reducing the weight of
nonwoven fabrics and packages, achieving onlylimited effects.
10 [0003]
As an approach to substantially reducing the weight of
nonwoven fabrics, nonwoven fabrics composed of hollow fibers
have been proposed in various processes. For example, Patent
Literature 1 proposes polypropylene nonwoven fabrics suitable
15 as sanitary materials having a fiber diameter of not more than
20pmandahollowness of5to 70%. Tablelin Patent Literature
1 describes a nonwoven fabric with a fiber diameter of 22.2
p, a hollowness of 13% and a basis weight of 22.2 g/m2.
[0004]
2 0 Further, Patent Literature 2 proposes nonwoven fabrics
that include continuous hollow fibers of a propylene polymer
having a ratio (Mz/Mw) of Z average molecular weight (Mz) to
weight average molecular weight (Mw) in the range from 1.5 to
1.9. Example 1 of this literature describes a spunbonded
0
nonwoven fabric with a fiber diameter of 21.5 pm, a hollowness
of 28.5% and a basis weight of 30 g/m2.
[0005]
Spunbonded nonwoven fabrics with excellent lightweight
5 properties can be obtained according to the methods for the
production of spunbonded nonwoven fabrics described in these
patent literatures. In the case where the hollow fibers
forming the spunbonded nonwoven fabrics are made finer to a
fiber diameter of not more than 20 pm and a basis weight of
10 not more than 20 g/m2 in order to further reduce the weight of
the spunbonded nonwoven fabrics, however, it has been found
that the obtainable nonwoven fabrics are so nonuniform that
they cannot be suitably used as sanitary materials.
Citation List
15 Patent Literature
[0006]
Patent Literature 1: U.S. Patent No. 6,368,990
Patent Literature 2: WO 2010/024268
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0007]
It is an object of the present invention to obtain
spunbonded nonwoven fabrics having excellent uniformity and
exhibiting high strength and flexibility even in the case where
the fiber diameter of hollow fibers forming the spunbonded
nonwoven fabrics is reduced as well as the basis weight of the
spunbonded nonwoven fabrics is reduced in order to obtain
5 excellently lightweight spunbonded nonwoven fabrics. The
present inventors carried out studies in order to achieve the
object. As a result, the present inventors have found that
spunbonded nonwoven fabrics with excellent uniformity can be
obtained by controlling the C-axis orientation of propylene
10 polymer hollow fibers to be not less than 0.85. The present
invention has been accomplished based on the finding.
SOLUTION TO PROBLEM
[0008]
An aspect of the invention is directed to a spunbonded
nonwoven fabricincludinghollow fibers ofapropylenepolymer,
the hollow fibers satisfying the following requirements (a)
to (c) :
(a) the C-axis orientation is at least 0.85,
(b) the average fiber diameter is 5 to 20 pm, and
(c) the hollowness is 5 to 30%.
ADVANTAGEOUS EFFECTS OF INVENTION
The spunbonded nonwoven fabrics according tothe present
invention exhibit excellent uniformity, high strength and
flexibility even in the case where the fiber diameter of hollow
fibers is reduced to 20 pm or less as well as where the basis
5 weight is reduced. Sufficient strength can be ensured even if
thebasis weight is decreasedto alowerlevelthan conventional.
Thus, the weight reduction of nonwoven fabrics is feasible.
[OOlO]
In anembodiment, the spunbondednonwoven fabric includes
10 hollow fibers with an eccentric hollow. Because such hollow
fibers are crimped, improvements in flexibility and bulkiness
are obtained in addition to the above advantageous effects.
BRIEF DESCRIPTION OF DRAWINGS
15 [OOll]
[Fig. 11 Fig. 1 is a view illustrating a configuration
of nozzle pores used for the formation of hollow fibers
according to the invention.
[Fig. 21 Fig. 2 is a view illustrating a cross section
20 of a fiber extruded from the nozzle pores depicted in Fig. 1
duringthe formation of a spunbonded nonwoven fabric according
to the invention.
[Fig. 31 Fig. 3 is a view illustrating another
configuration of nozzle pores used for the formation of hollow
fibers according to the invention.
[Fig. 41 Fig. 4 is a view illustrating a cross section
of a fiber extruded from the nozzle pores depicted in Fig. 3
duringthe formation of a spunbonded nonwoven fabric according
5 to the invention.
[Fig. 51 Fig. 5 is a schematic view illustrating an
apparatus for producing spunbonded nonwoven fabrics used in
Examples of the invention.
[Fig. 61 Fig. 6 is a schematic view illustrating an
10 apparatus for producing spunbonded nonwoven fabrics used in
Comparative Examples of the invention.
DESCRIPTION OF EMBODIMENTS
[0012]
15 (Thermoplastic resins)
Hollow fibers constituting spunbonded nonwoven fabrics
according tothe invention are formed of thermoplastic resins.
Various known thermoplastic resins may be used. Examples
include homopolymers and copolymers of a-olefins such as
20 ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene
and 1-octene. Specific examples include ethylene polymers
such as high-pressure low-density polyethylenes, linear
1 low-density polyethylenes (LLDPE) and high-density
polyethylenes (HDPE); propylene polymers such as
\ -
polypropylenes (propylene homopolymers), propylene/a-olefin
random copolymers and propylene block copolymers; polyolefins
such as poly(1-butene), poly(4-methyl-1-pentene),
ethylene/propylene random copolymers, ethylene/l-butene
5 random copolymers and propylene/l-butene random copolymers;
polyesters (such as polyethylene terephthalates, polybutylene
terephthalates and polyethylene naphthalates); polyamides
(such as nylon-6, nylon-66 and poly(meta-xylene adipamide);
polyvinyl chlorides, polyimides, ethylene/vinyl acetate
10 copolymers, ethylene/vinyl acetate/vinyl alcohol copolymers,
ethylene/(meth)acrylic acid copolymers,
ethylene/acrylate/carbon monoxide copolymers,
polyacrylonitriles, polycarbonates, polystyrenes andionomers.
Of these, ethylene polymers, propylene polymers, polyethylene
15 terephthalates and polyamides are more preferable.
[0013]
The above thermoplastic resins maybe used singly, or two
or more kinds of the thermoplastic resins may be used as a
mixture.
20 [0014]
Oftheabovethermoplasticresins, propylenepolymersare
particularly preferable from the viewpoints of spinning
stability during spinning as well as stretch workability of
nonwoven fabrics.
(Propylene polymers)
The propylene polymer forming t h e hollow f i b e r s of
spunbonded nonwoven f a b r i c s according t o t h e i n v e n t i o n is a
5 homopolymer o f p r o p y l e n e o r a random copolymer ( a
p r o p y l e n e / a - o l e f i n random copolymer) o f p r o p y l e n e and one, o r
two o r more k i n d s o f a - o l e f i n s having 2 o r more carbon atoms,
and p r e f e r a b l y 2 t o 8 carbon atoms such a s e t h y l e n e , 1-butene,
1-pentene, 1-hexene, 1-octene and 4-methyl-1-pentene. The
10 propylene polymer u s u a l l y has a melting p o i n t (Tm) of not l e s s
than 125Oc, and p r e f e r a b l y i n t h e range from 125 t o 165°C. The
amount of t h e a - o l e f i n s copolymerized is not p a r t i c u l a r l y
l i m i t e d a s long a s t h e o b t a i n a b l e propylene polymer e x h i b i t s
a melting p o i n t (Tm) i n t h e above range. However, t h e amount
15 is u s u a l l y not more than 10 mol%, and p r e f e r a b l y not more than
6 mol%.
[0016]
W h e n a p r o p y l e n e / a - o l e f i n randomcopolymer is u s e d a s t h e
propylenepolymer, it is p r e f e r a b l e t o u s e a p r o p y l e n e / a - o l e f i n
20 random copolymer having a melting p o i n t (Tm) of not more than
1 5 3 " ~an~d more p r e f e r a b l y i n t h e range from 125 t o 1 5 0 " ~ .
[0017]
The m e l t flow r a t e (MFR) (ASTM D-1238, 2 3 0 " ~21~60 g l o a d )
of t h e propylene polymer i n t h e i n v e n t i o n is not p a r t i c u l a r l y
r
limited as long as the polymer can form spunbonded nonwoven
fabrics. The melt flow rate, however, is usually in the range
from 10 to 100 g/10 min, and preferably 20 to 70 g/10 min. If
the MFR is less than 10 g/10 min, the propylene polymer tends
5 to exhibit highmelt viscosity and poor spinnability, possibly
failing to form thin hollow fibers. If the melt flow rate of
the propylene polymer exceeds 100 g/10 min, the obtainable
spunbonded nonwoven fabric may exhibit poor properties such
as tensile strength.
10 [0018]
The propylene polymers in the invention may be blended
withcommonadditives or other polymers as requiredwhile still
achieving the objects of the invention. Exemplary additives
include antioxidants, weathering stabilizers, light
15 stabilizers, antistatic agents, hydrophilic agents,
antifogging agents, antiblocking agents, lubricants,
nucleating agents and pigments.
[0019]
(Spunbonded nonwoven fabrics)
2 0 A spunbonded nonwoven fabric according to the invention
includes hollow fibers of the above propylene polymer, the
hollow fibers having (a) a C-axis orientation of at least 0.85,
preferably not less than 0.90, (b) an average fiber diameter
of 5 to 20 pm, preferably 5 to 17 pm, and (c) a hollowness of
0 5 t o 30%, p r e f e r a b l y 10 t o 30%, more p r e f e r a b l y 1 4 t o 30%.
[0020]
I f t h e f i b e r s h a v e a h o l l o w n e s s o f l e s s t h a n 5 % , t h e C - a x i s
o r i e n t a t i o n becomes less than 0.85 and t h e u n i f o r m i t y of t h e
5 o b t a i n a b l e spunbonded nonwoven f a b r i c may be d e t e r i o r a t e d .
[0021]
The p r e s e n t i n v e n t i o n p r o v i d e s t h a t t h e hollowness i s
c o n t r o l l e d t o b e i n t h e range from 5 t o 30% a s w e l l a s t h e C-axis
o r i e n t a t i o n t o be not less than 0.85. This c o n f i g u r a t i o n
10 advantageously e n s u r e s t h a t nonwoven f a b r i c s can be produced
while t h e o c c u r r e n c e o f r e s i n masses ( s h o t s ) is prevented even
i n t h e case where t h e o u t p u t r a t e is i n c r e a s e d t o improve
p r o d u c t i v i t y while t h e amount of c o o l i n g a i r i s r e l a t i v e l y
s m a l l .
15 [0022]
I f t h e average f i b e r d i a m e t e r exceeds 20 pm, such f i b e r s
a r e e x c e s s i v e l y t h i c k and w i l l not be d i s p e r s e d s u f f i c i e n t l y .
As a r e s u l t , t h e o b t a i n a b l e spunbonded nonwoven f a b r i c may be
unsatisfactoryintermsofuniformityevenifthefibersachieve
20 a C-axis o r i e n t a t i o n of not less than 0.85. F u r t h e r , such a
spunbonded nonwoven f a b r i c is poor i n f l e x i b i l i t y and i s not
s u i t a b l y used a s s a n i t a r y m a t e r i a l s .
[0023]
The above average f i b e r and hollowness ensure t h a t t h e
9 inventive spunbonded nonwoven fabrics exhibit excellent
properties such as lightweight properties and tensile
strength.
[0024]
5 The hollow fibers forming the inventive spunbonded
nonwoven fabrics may have an eccentric hollow. In the
invention, such hollow fibers having an eccentric hollow
(hereinafter, also referred to as "eccentric hollow fibers")
are hollow fibers in which the center of the hollow is found
10 at a different position from the center of the hollow fiber
in a cross section of the fiber.
[0025]
In the case where the inventive spunbonded nonwoven
fabric is formed of the eccentric hollow fibers, the C-axis
15 orientation (a) is not necessarily limited, but the average
fiber diameter (b) is usually in the range from 5 to 50 pm,
preferably 5 to 30 pm, more preferably 5 to 20 pm, and most
preferably5to17 pm. Inapreferredembodiment, the eccentric
hollow fibers may satisfy the aforementioned C-axis
20 orientation (a) and hollowness (c).
[0026]
When the inventive spunbonded nonwoven fabric is formed
of eccentrichollow fibers, thehollow fibers are crimped. The
term "crimped" means that the fibers have three or more crimps.
The inventive spunbonded nonwoven fabric formed such
eccentric hollow fibers exhibit excellent flexibility and
bulkiness because of the crimps of the hollow fibers.
5 The number of crimps of the inventive hollow fibers may
be determined in accordance with JIS L 1015. The number of
crimps is usually not less than 3, preferably not less than
5, and more preferably not less than 7 per 25 mm of the fiber.
The upper limit is not particularly specified. Few crimps may
10 fail to provide properties such as bulkiness which are
attributed to the three dimensional helical structures of
fibers.
[0028]
The spunbonded nonwoven fabrics of the invention
15 preferably have a basis weight in the range from 5 to 20 g/m2,
and more preferably 5 to 15 g/m2. The spunbonded nonwoven
fabrics having this basis weight exhibit excellent properties
such as lightweight properties, flexibility and tensile
strength.
20 [0029]
The spunbonded nonwoven fabrics of the invention
preferably have a uniformity (a degree of uniformity) in the
range from 0.01 to 0.85, and more preferably 0.01 to 0.7. The
spunbonded nonwoven fabrics having this uniformity exhibit
9
excellent properties such as tensile strength and water
resistance.
[0030]
Depending on applications, the spunbonded nonwoven
5 fabrics of the invention may be entangled by various known
entangling methods, for example, by needle punching, water
j e t t i n g o r u l t r a s o n i c a t i n g o r b y p a r t i a l t h e r m a l f u s i o n b o n d i n g
through hot embossing with an embossing roll or by blowing of
hot air through the fibers. These entangling methods may be
10 used singly, or a plurality of these methods may be used in
combination.
[0031]
Whenthe spunbondednonwoven fabrics arethermallyfusion
bonded by hot embossing, the emboss area percentage is usually
15 in the range from 3 to 20%, preferably 3 to lo%, and the
non-emboss unit area is not less than 0.5 mm2, preferably in
the range from 4 to 40 mm2. The non-emboss unit area is the
maximumarea ofatetragoninscribedinbosses amongtheminimum
units of non-embossing sections surrounded by bosses. These
20 embossing configurations ensure that the obtainable spunbonded
nonwoven fabrics exhibit excellent strength and flexibility.
[0032]
In the case where the entangling treatment is carried out
by needle punching, spunbonded nonwoven fabrics exhibiting
Q
e x c e l l e n t s t r e n g t h and f l e x i b i l i t y may b e o b t a i n e d by using
a known needle punching machine while c o n t r o l l i n g c o n d i t i o n s
such a s needle d e n s i t y , needle type, n e e d l e d e p t h and punch
c o u n t s i n a c c o r d a n c e w i t h t h e n a t u r e o r p r o p e r t i e s o f t h e f i b e r s .
5 In some c a s e s , entanglementeffectsmaybe o p t i m i z e d b y p a s s i n g
t h e spunbonded nonwoven f a b r i c s t h r o u g h a p l u r a l i t y of needle
punching machines.
[0033]
In an embodiment, t h e spunbonded nonwoven f a b r i c of t h e
10 i n v e n t i o n i n c l u d e s t h e r m o p l a s t i c r e s i n hollow f i b e r s with an
e c c e n t r i c hollow.
[0034]
Such hollow f i b e r s with an e c c e n t r i c hollow according t o
t h e i n v e n t i o n a r e e c c e n t r i c hollow f i b e r s o b t a i n e d by spinning
15 a t h e r m o p l a s t i c r e s i n a s one component through a p l u r a l i t y of
asymmetricallyshapedslits of o r i f i c e s ( n o z z l e s ) s u c h a s t h o s e
i l l u s t r a t e d i n Fig. 3. Such e c c e n t r i c hollow f i b e r s a r e
distinguishedfromso-calledeccentric c o n j u g a t e h o l l o w f i b e r s
o b t a i n e d by s p i n n i n g d i f f e r e n t k i n d s o f t h e r m o p l a s t i c r e s i n s
20 from r e s p e c t i v e s l i t s .
[0035]
The p h r a s e " t h e r m o p l a s t i c r e s i n a s one component" means
t h a t a t h e r m o p l a s t i c r e s i n f o r making t h e f i b e r s forms one
component n o t o n l y a s an i n d i v i d u a l t h e r m o p l a s t i c r e s i n o r as
amixture of two ormore kinds of thermoplastic resins described
above.
[0036]
(Methods for producing spunbonded nonwoven fabrics)
5 The spunbonded nonwoven fabrics of the invention may be
produced by closed spunbonding processes such as those
disclosed in JP-A-S60(1985)-155765, Japanese Patent No.
3442896 and Japanese Patent No. 3883818.
[0037]
10 In detail, an exemplary process will be described. An
apparatus forproducingspunbondisusedwhichincludesaclosed
cooling chamber illustrated in Fig. 5 that is equipped with
a spinneret (die) having a large number of orifices (nozzles)
illustrated in Fig. 1 that are capable of forming hollow fibers
15 cross-sectionally illustrated in Fig. 2. The propylene
polymer is melt spun through the large number of orifices
(nozzles), and the resultant continuous hollow fibers of the
propylene polymer are cooled with cooling air introduced into
the cooling chamber. The fibers are then passed through a
20 narrow aisle (a drawing section) downstream from the cooling
chamber in which the cooling air that has been used for cooling
is utilized as drawing air. After being drawn (attenuated)
with the drawing air, the continuous fibers are dispersed with
a diffuser disposed downstream and are deposited onto a moving
0
collection surface (a mesh belt).
The production is also possible with an apparatus for
producing spunbond which includes a closed cooling chamber
5 illustrated in Fig. 5 that is equipped with a spinneret (die)
havingalarge number of orifices (nozzles) illustratedin Fig.
3 that are capable of forming hollow fibers cross-sectionally
illustratedin Fig. 4. In this case, the obtainable spunbonded
nonwoven fabrics are composed of hollow fibers having an
10 eccentric hollow.
[0039]
The temperature for melting the propylene polymer is not
particularly limited as long as the hollow fibers are
sufficiently oriented about the C axis, but may be usually set
15 at a temperature in the range from 180 to 2 8 0 " ~pr~ef erably
190 to 270°c, and more preferably 200 to 260"~.
[0040]
The temperature of the cooling air is not particularly
limited as long as the propylene polymer is solidified at the
I
I 20 temperature. However, the cooling air temperature is usually
!
I in the range from 5 to 50°c, preferably 10 to 40°c, and more
i
preferably 15 to 30"~. The cooling air that has travelled to
the diffuser functions as a dispersingmedium for sufficiently
dispersing the fibers. In order to ensure uniformity that is
is u s u a l l y i n t h e range from 30 t o 100 Nm3/min/m, p r e f e r a b l y
35 t o 80 Nm3/min/m, and more p r e f e r a b l y 40 t o 60 Nm3/min/m. he
v e l o c i t y of t h e drawing a i r is u s u a l l y i n t h e range from 100
5 t o 10,000 m/min, and p r e f e r a b l y 500 t o 10,000 m/min.
[0041]
In o r d e r t o o b t a i n propylene polymer f i b e r s w i t h a hollow
c r o s s s e c t i o n having an average f i b e r diameter of 5 t o 20 pm
and a hollowness of 5 t o 30%, i n p a r t i c u l a r an average f i b e r
10 diameter of 5 t o 15 pm and a hollowness of 1 4 t o 30%, it is
p r e f e r a b l e t o use a s p i n n e r e t provided with o r i f i c e s ( n o z z l e s )
with an o u t e r diameter of 0.5 t o 5.0 mm, a s l i t width o f 0.05
t o 0.5 mm, a number of s l i t s of 2 t o 10, p r e f e r a b l y 3 t o 6,
an i n t e r v a l between s l i t s , namely, a c a n a l w i d t h o f 0.04 t o
15 0.15 mm, and a n o z z l e pore a r e a of 0.1 t o 0.5 mm2. In o r d e r
t o o b t a i n nonwoven f a b r i c s having high u n i f o r m i t y t h a t is an
advantageous effectachievedbytheinvention, it is p r e f e r a b l e
t o u s e a s p i n n e r e t provided with o r i f i c e s i n which t h e value
of t h e c a n a l width d i v i d e d by t h e n o z z l e p o r e a r e a ( c a n a l
20 w i d t h / n o z z l e pore a r e a ) is p r e f e r a b l y not l e s s than 0.35 mm-l,
and more p r e f e r a b l y not l e s s than 0.40 mm-l.
I
r In t h e i n v e n t i o n , t h e c a n a l width i n t h e o r i f i c e s i s a
width (an i n t e r v a l ) between s l i t s ( n o z z l e p o r e s ) i l l u s t r a t e d
-
in, for example, Fig. 1 or Fig. 3 through which a melt such
as the propylene polymer is extruded. The nozzle pore area is
the total of the areas of all the slits (nozzle pores).
[0043]
5 If the outer diameter of the orifices exceeds 5.0 mm, it
may be difficult to obtain continuous fibers with a fiber
diameter of not more than 20 pm. If the slit width of the
orifices exceeds 0.5 mm, it may be difficult to obtain
continuous fibers with a hollowness in excess of 5%. If the
10 number of slitsis 2 or less, or is10 ormore, itmaybedifficult
to obtain continuous fibers with a hollowness in excess of 5%.
[0044]
Even if conventional spunbonded nonwoven fabrics
(spunbonded nonwoven fabrics of solid continuous fibers) are
15 manufactured using a spunbonding apparatus equipped with a
similar closed cooling device so as to obtain fiber diameters
of not more than 20 pm, the obtained (solid) fibers do not have
a C-axis orientation of not less than 0.85. On the other hand,
even if hollow fibers with a hollowness of 5 to 30% are
20 manufactured using a spunbonding apparatus equipped with an
open cooling device, the C-axis orientation is as low as about
0.7 and the obtainable spunbonded nonwoven fabrics tend to be
poor in uniformity.
[0045]
(Spunbonded nonwoven f a b r i c laminate)
Otherlayersmaybelaminatedtothe i n v e n t i v e spunbonded
nonwoven f a b r i c s i n accordance with v a r i o u s a p p l i c a t i o n s .
Such a d d i t i o n a l l a y e r s laminated t o t h e spunbonded nonwoven
5 f a b r i c s a r e not p a r t i c u l a r l y l i m i t e d , and v a r i o u s k i n d s o f
l a y e r s may be laminated depending on a p p l i c a t i o n s .
[0046]
S p e c i f i c examples i n c l u d e k n i t t e d f a b r i c s , woven f a b r i c s ,
nonwoven f a b r i c s and f i l m s . Such a d d i t i o n a l l a y e r s may be
10 laminated (stacked/bonded) t o t h e spunbonded nonwoven f a b r i c s
of t h e i n v e n t i o n by any known methods, f o r example, thermal
f u s i o n bonding methods such a s hot embossing and u l t r a s o n i c
f u s i o n bonding, mechanical e n t a n g l i n g methods such a s needle
I punchingandwaterjetting, bondingmethodswithadhesives such
I 15 a s hot m e l t adhesives and u r e t h a n e a d h e s i v e s , and e x t r u s i o n
l a m i n a t i o n .
[0047]
The nonwoven f a b r i c s l a m i n a t e d t o t h e spunbondednonwoven
f a b r i c s o f t h e i n v e n t i o n m a y b e any known nonwoven f a b r i c s such
20 a s usual spunbonded nonwoven f a b r i c s , meltblown nonwoven
f a b r i c s , wet nonwoven f a b r i c s , dry nonwoven f a b r i c s , dry pulp
nonwoven f a b r i c s , flash-spun nonwoven f a b r i c s and s p l i t - f i b e r
nonwoven f a b r i c s .
The f i l m s laminated t o t h e spunbonded nonwoven f a b r i c s
of t h e i n v e n t i o n a r e p r e f e r a b l y b r e a t h a b l e ( m o i s t u r e
permeable) filmsinordertotakeadvantageofthebreathability,
f l e x i b i l i t y and l i g h t w e i g h t p r o p e r t i e s t h a t a r e
5 c h a r a c t e r i s t i c s of t h e i n v e n t i v e spunbonded nonwoven f a b r i c s .
Various known b r e a t h a b l e f i l m s may be used, with examples
i n c l u d i n g m o i s t u r e permeable f i l m s of t h e r m o p l a s t i c e l a s t o m e r s
such a s polyurethane e l a s t o m e r s , p o l y e s t e r e l a s t o m e r s and
polyamide e l a s t o m e r s ; and porous f i l m s o b t a i n e d by drawing
10 t h e r m o p l a s t i c r e s i n f i l m s c o n t a i n i n g i n o r g a n i c o r o r g a n i c f i n e
p a r t i c l e s t o c r e a t e pores i n t h e f i l m s . P r e f e r r e d
t h e r m o p l a s t i c r e s i n s used f o r t h e porous f i l m s a r e p o l y o l e f i n s
such a s h i g h - p r e s s u r e low-density p o l y e t h y l e n e s , l i n e a r
low-densitypolyethylenes (LLDPE), high-densitypolyethylenes,
15 p o l y p r o p y l e n e s , p o l y p r o p y l e n e random copolymers and
compositions t h e r e o f .
[0049]
Laminates i n c l u d i n g b r e a t h a b l e f i l m s c a n b e c l o t h - l i k e
composite m a t e r i a l s t h a t m a i n t a i n f l e x i b i l i t y i n h e r e n t t o t h e
20 i n v e n t i v e spunbonded nonwoven f a b r i c s a s w e l l a s e x h i b i t very
h i g h w a t e r r e s i s t a n c e .
[0050]
The i n v e n t i v e spunbonded nonwoven f a b r i c and a meltblown
nonwoven fabricmaybelaminatedtogetherby anymethodwithout
limitation as long as the method is capable of combining the
two into a laminate. Examples of suchmethods include amethod
in which meltblown fibers are directly deposited onto the
spunbonded nonwoven fabric to form a meltblown nonwoven fabric
5 and the spunbonded nonwoven fabric and the meltblown nonwoven
fabric are fusion bonded with each other; a method in which
the spunbonded nonwoven fabric and a meltblown nonwoven fabric
are placed one on top of the other and the two nonwoven fabrics
are fusion bonded with each other by thermal pressing; and a
10 method in which the spunbonded nonwoven fabric and a meltblown
nonwoven fabric are bonded together via an adhesive such as
a hot melt adhesive or a solvent adhesive.
A meltblown nonwoven fabric may be directly formed on the
15 spunbonded nonwoven fabric by a meltblowing method in which
a thermoplastic resin melt is sprayed onto a surface of the
spunbonded nonwoven fabric to deposit the fibers. During
meltblowing, air is suctioned from the backside of the
spunbonded nonwoven fabric so as to attract meltblown fibers
20 sprayed onto the front side. In this manner, the spunbonded
nonwoven fabric is combined with a meltblown nonwoven fabric
simultaneously with the deposition of fibers, resulting in a
laminated nonwoven fabric having a spunbonded nonwoven fabric
layer andameltblown nonwoven fabric layer. In the case where
0
the attachment between the twononwoven fabricsisinsufficient,
thelaminatemaybe sufficientlyunitedby, forexample, thermal
pressing with embossing rolls.
[0052]
5 Exemplary methods for thermally fusion bonding the
spunbonded nonwoven fabric with a meltblown nonwoven fabric
include a method in which the spunbonded nonwoven fabric and
a meltblown nonwoven fabric are fusion bonded at the entirety
of their surfaces in contact with each other, and a method in
10 which the spunbonded nonwoven fabric and a meltblown nonwoven
fabric are fusion bonded at portions of their surfaces in
contact with each other. In the present invention, it is
preferable that the spunbonded nonwoven fabric and a meltblown
nonwoven fabric be fusion bonded together by hot embossing.
15 In this case, the fusion bonding area is 3 to 30%, preferably
3 to 20%, and more preferably 3 to 10% of the area of contact
between the spunbonded nonwoven fabric and the meltblown
nonwoven fabric. This fusion bonding area ensures that the
laminated nonwoven fabric exhibits excellent balance between
20 peel strength and flexibility.
[0053]
Examples of the hot melt adhesives used to bond the
spunbonded nonwoven fabrics and meltblown nonwoven fabrics
include resin adhesives such as vinyl acetate adhesives and
polyvinyl alcohol adhesives, and rubber adhesives such as
styrene/butadiene adhesives and styrene/isoprene adhesives.
Examples of the solvent adhesives include organic solvent or
aqueous emulsion adhesives based on rubber adhesives such as
5 styrene/butadiene adhesives, styrene/isoprene adhesives and
urethane adhesives, and adhesives based on resin such as vinyl
acetate and vinyl chloride. Of the adhesives, rubber hot melt
adhesives such as styrene/isoprene adhesives and
styrene/butadiene adhesives are preferable because the
10 characteristic texture of the spunbonded nonwoven fabrics is
not deteriorated.
[0054]
((Meltblown nonwoven fabrics))
A preferred meltblown nonwoven fabric laminated to the
15 inventive spunbonded nonwoven fabric includes polyolefin
fibers and has (i) an average fiber diameter of not more than
2 pm, (ii) a coefficient of variation of fiber diameter (CV)
of not more than 60%, preferably not more than 50%, and (iii)
a number of fusion bonding per 100 fibers of not more than 15,
20 preferably not more than 12, more preferably not more than 10.
[0055]
Another preferredmeltblown nonwoven fabriclaminatedto
the inventive spunbonded nonwoven fabric includes propylene
polymer fibers and has (i) an average fiber diameter of not
m0rethan2p.m~ (ii) acoefficientofvariationoffiberdiameter
(CV) of not more than 60%, p r e f e r a b l y not more than 50%, and
( i v ) an a - c r y s t a l f r a c t i o n of less than 0.9.
[0056]
5 Meltblown nonwoven f a b r i c s having t h e above p r o p e r t i e s
may be produced by, f o r example, a method d e s c r i b e d i n
(Applications)
10 The spunbondednonwoven f a b r i c s o b t a i n e d a c c o r d i n g t o t h e
p r e s e n t i n v e n t i o n , and t h e nonwoven f a b r i c laminate i n c l u d i n g
t h e i n v e n t i v e spunbondednonwovenfabricsmaybeusedinvarious
a p p l i c a t i o n s .
[0058]
15 For example, t h e s e nonwoven f a b r i c s may be widely used
, i n medical m a t e r i a l s , i n d u s t r i a l m a t e r i a l s , c i v i l e n g i n e e r i n g
and b u i l d i n g m a t e r i a l s , a g r i c u l t u r a l and gardening m a t e r i a l s ,
and d a i l y l i f e m a t e r i a l s , i n d e t a i l , s u r g i c a l gowns, bandages,
I b e d c l o t h e s such a s bed s h e e t s and p i l l o w c a s e s , and s u b s t r a t e s
20 f o r c a r p e t s and a r t i f i c i a l l e a t h e r s
[0059]
Because t h e spunbonded nonwoven f a b r i c s o r t h e nonwoven
I
I f a b r i c l a m i n a t e a c c o r d i n g t o t h e i n v e n t i o n a r e l i g h t w e i g h t and
have good f l e x i b i l i t y and t e x t u r e , they may be p a r t i c u l a r l y
s u i t a b l y used i n d i s p o s a b l e d i a p e r s , s o l i d g a t h e r s h e e t s and
s a n i t a r y napkins.
[0060]
(Solid g a t h e r s h e e t s )
5 D i s p o s a b l e d i a p e r s a c c o r d i n g t o t h e i n v e n t i o n u t i l i z e t h e
i n v e n t i v e spunbonded nonwoven f a b r i c s , or t h e nonwoven f a b r i c
laminatesincludingtheinventive spunbondednonwoven f a b r i c s .
The i n v e n t i v e nonwoven f a b r i c s can form members f o r s o l i d
g a t h e r s i n products such a s d i s p o s a b l e d i a p e r s and s a n i t a r y
10 napkins.
[0061]
S o l i d g a t h e r s a r e r e q u i r e d t o e x h i b i t e x c e l l e n t
b r e a t h a b i l i t y , prevent t h e leakage of l o o s e s t o o l , and have
c o m f o r t a b l e t o u c h . In view of t h e s e requirements, t h e
15 i n v e n t i v e spunbonded nonwoven f a b r i c s , o r t h e nonwoven f a b r i c
laminates i n c l u d i n g t h e i n v e n t i v e spunbonded nonwoven f a b r i c s
a r e s u i t a b l y used i n such a p p l i c a t i o n s .
[0062]
i
!
(Back s h e e t s )
2 0 T h e d i s p o s a b l e d i a p e r s a c c o r d i n g t o t h e i n v e n t i o n u t i l i z e
t h e i n v e n t i v e spunbonded nonwoven f a b r i c s , o r t h e nonwoven
f a b r i c laminates i n c l u d i n g t h e i n v e n t i v e spunbonded nonwoven
f a b r i c s . The i n v e n t i v e nonwoven f a b r i c s can form members f o r
back s h e e t s i n p r o d u c t s such a s d i s p o s a b l e d i a p e r s a n d s a n i t a r y
napkins.
Back sheets are required to exhibit excellent
breathability, be hollow to provide high shieldingproperties,
5 andhave comfortable touch. Inview of these requirements, the
inventive spunbonded nonwoven fabrics, or the nonwoven fabric
laminates including the inventive spunbonded nonwoven fabrics
are suitably used in such applications.
10 EXAMPLES
[0064]
The present invention will be described in detail
hereinbelow based on examples without limiting the scope of
the invention to such examples.
15 [0065]
I In examples and comparative examples, properties and
characteristics were measured by the following methods.
[0066]
(1) Measurement of C-axis orientation
I
i
I 20 A wide-angle X-ray diffractometer (RINT 2550
manufactured by Rigaku Corporation, attachment: fiber sample
table, X-ray source: CuKa, output: 40 kV 370 mA, detector:
scintillation counter) was used. Sample fibers were arranged
alonga fiber axial directionandwere fixedon the sample holder.
0 Intensities were measured which indicated the azimuths of a
peak of a crystal planes [(110) planes], and an azimuthal
distribution curve (an X-ray interference diagram) was
obtained. Based on the half-width (a) of the peak, the
5 orientation (the C-axis orientation) ofthe hollow fibers with
respect to the fiber axial direction was calculated according
to the following equation.
Orientation (F) = (180" - a)/180°
(a is the half-width of the peak in the azimuthal
10 distribution curve.)
[0067]
(2) Fiber diameter (pm)
Aspunbondednonwoven fabricwas observedwith an optical
microscope (ECLIPSE E-400 manufactured by Nikon). Fiber
15 diameters were measured with respect to randomly selected 100
filaments formingthe spunbondednonwoven fabric on the screen.
The average was obtained as the fiber diameter of the nonwoven
fabric.
[0068]
20 (3) Fineness [dl
The fineness of the spunbonded nonwoven fabric was
calculated according to the following equation.
Fineness [dl = 0.00225 x n: x p [g/cm3] x D* [pm] x (1 -
hollowness [%I )
Here, p [g/cm3] is the melt density of the resin at the
service temperature, and D is the fiber diameter.
[0069]
(4) Single filament strength [gf /dl
5 I n a c c o r d a n c e w i t h J I S L 1 9 0 5 (7.5.lmethod), 60 filaments
were collectedandsubjectedto atensiletestinathermostatic
chamber at a temperature of 20+2"~a nd a humidity of 65+2% in
accordance with JIS Z 8703 (standard conditions at testing
sites) using a tensile tester (Instron 5564 manufactured by
10 Instron Japan Co., Ltd.) with a chuck distance of 20 mm and
at a stress rate of 20 mm/min, thereby determining the tensile
loads of the 60 filament test pieces. The average of the
maximum loads was obtained as the single filament strength.
[0070]
15 (5) Hollowness [%I
A spunbondednonwoven fabric was buriedin an epoxy resin
and was cut with a microtome to give a sample piece. The sample
piece was observed with an electron microscope (scanning
electron microscope S-3500N manufactured by Hitachi, Ltd.).
20 In the obtained cross sectional image of the fibers, the cross
sectional area of the entire fiber and that of the hollow were
obtained. The hollowness was calculated from the following
equation.
[0071]
L
Hollowness [%I = ( c r o s s s e c t i o n a l a r e a of h o l l o w / c r o s s
s e c t i o n a l a r e a of e n t i r e f i b e r ) x 100
An average of 100 f i b e r s was o b t a i n e d a s t h e hollowness.
[0072]
5 ( 6 ) F l e x i b i l i t y ( F l e x u r a l r i g i d i t y ) [45" c a n t i l e v e r method]
In accordance with JIS L 1096 ( 6 . 1 9 . 1 A method), a
spunbonded nonwoven f a b r i c was c u t i n a t h e r m o s t a t i c chamber
a t a t e m p e r a t u r e of 2 0 f 2 " ~a n d a h u m i d i t y o f 65+2%i n accordance
with JIS Z 8703 ( s t a n d a r d c o n d i t i o n s a t t e s t i n g s i t e s ) t o give
10 5 t e s t p i e c e s , 20 mmx 150mm, along e a c h o f t h e m a c h i n e d i r e c t i o n
(MD) and t h e c r o s s d i r e c t i o n (CD) . Each t e s t p i e c e was placed
o n a h o r i z o n t a l , smooth-surfacetablehavinga 45" s l o p e s u r f a c e ,
with t h e s h o r t e r s i d e of t h e test p i e c e a l i g n e d a t t h e s c a l e
b a s e l i n e . Next, t h e test p i e c e wasmanually s l i d s l o w l y t o w a r d
15 t h e s l o p e s u r f a c e . When t h e c e n t r a l p o i n t a t one end of t h e
t e s t p i e c e touched t h e s l o p e s u r f a c e , t h e l e n g t h by which t h e
o t h e r end had moved was measured by r e a d i n g t h e s c a l e s . The
f l e x i b i l i t y ( f l e x u r a l r i g i d i t y ) was i n d i c a t e d i n l e n g t h (mm)
of t h e movement of t h e t e s t p i e c e . Each of t h e 5 test p i e c e s
1 I 20 was t e s t e d with r e s p e c t t o both t h e f r o n t and back s i d e s . The
average i n machine d i r e c t i o n (MD) and t h a t i n c r o s s d i r e c t i o n
(CD) were o b t a i n e d .
[0073]
( 7 ) T e n s i l e s t r e n g t h ( S t r e n g t h )
0
I n a c c o r d a n c e w i t h J I S L 1 9 0 6 (6.12.1Amethod), anonwoven
f a b r i c was c u t i n a t h e r m o s t a t i c chamber a t a temperature of
2 0 f 2 " ~a nd a humidity of 65+2% i n accordance with JIS Z 8703
( s t a n d a r d c o n d i t i o n s a t t e s t i n g s i t e s ) t o give 3 test p i e c e s
5 25 cm i n machine d i r e c t i o n (MD) and 2.5 cm i n c r o s s d i r e c t i o n
( C D ) . The t e s t p i e c e s were s u b j e c t e d t o a t e n s i l e t e s t with
a t e n s i l e t e s t e r ( I n s t r o n 5564 manufactured by I n s t r o n Japan
Co., L t d . ) with a chuck d i s t a n c e of 30 mm and a t a s t r e s s r a t e
of 3 0 m m / m i n t o d e t e r m i n e t h e t e n s i l e l o a d s o f t h e 3 t e s t p i e c e s .
10 The average of t h e maximum l o a d s was o b t a i n e d a s t h e t e n s i l e
s t r e n g t h .
[0074]
( 8 ) Uniformity (Degree of u n i f o r m i t y )
I
I A nonwoven f a b r i c was c u t i n a t h e r m o s t a t i c chamber a t
1
I 15 a temperature of 2 0 f 2 " ~an d a h u m i d i t y o f 65k28 i n accordance
with JIS Z 8703 ( s t a n d a r d c o n d i t i o n s a t t e s t i n g sites) t o give
a t e s t p i e c e 25 cm i n machine d i r e c t i o n (MD) and 20 cm i n c r o s s
d i r e c t i o n (CD) . The weight t h e r e o f was o b t a i n e d a s an average
b a s i s weight ( g / m 2 ) . Next, t h i s nonwoven f a b r i c was punched
w i t h a punch ( a p u n c h i n g j i g ) 1 3 m m i n i n n e r d i a m e t e r a t r a n d o m l y
s e l e c t e d 15 p o i n t s i n t h e MD and a t randomly s e l e c t e d 10 p o i n t s
i n t h e CD. In t h i s manner, a t o t a l of 150 test p i e c e s were
sampled from t h e nonwoven f a b r i c . The w e i g h t s o f a l l t h e t e s t
p i e c e s were measured. O f t h e t e s t p i e c e s , t h e 5 h e a v i e s t t e s t
0
pieces and the 20 lightest test pieces were selected as thicker
portions and thinner portions, respectively. The respective
averages were obtained, and the degree of uniformity was
determined from the following equation.
5 [0075]
Degree of uniformity = (average basis weight of thicker
portions - average basis weight of thinner portions) /average
basis weight
The nonwoven fabric is more uniform with decreasing
10 degree of uniformity.
[0076]
(9) FUKURAMI value (Evaluation of bulkiness)
A nonwoven fabric was tested with KES-FB system
manufactured by KATO TECH CO., LTD. in terms of tension, shear,
15 compression, surface friction and bending under highly
sensitive conditions for knitted fabrics. The measurement
results were analyzed under knitted underwear (summer)
conditionstoobtaina FUKURAMI value. Thelargerthe FUKURAMI
value, the bulkier and the more flexible.
20 [0077]
(10) Water pressure resistance (mm Aqua)
I n a c c o r d a n c e w i t h J I S L 1 0 9 2 (Amethod), anonwovenfabric
laminate as a water treatment filter was cut in a thermostatic
chamber at a temperature of 20+2"~a nd a humidity of 65+2% in
0
accordance with JIS Z 8703 (standard conditions at testing
sites) to give 10 test pieces, each 15 x 15 cm. The test pieces
were tested using a water pressure resistance tester to
determinethepressurewhichcausedwaterleakage. The results
5 were averaged.
[0078]
(11) Number of crimps
The number of crimps was counted in accordance with JIS
L 1015.
10 Compartment lines having a spatial distance of 25 mm were
drawn on smooth and gloss paper.
[0079]
Next, before a nonwoven fabric of continuous fibers was
thermally pressed with embossing rolls, fibers were carefully
15 collected fromthe nonwoven fabric while paying attention not
to relax the crimps. Both ends of each collected fiber were
bonded onto the paper via an adhesive while allowing 25+5%
looseness relative to the spatial distance. Each of such
sample fibers was analyzed in the following manner to count
20 the crimps. The individual fiber was attached to chucks of a
crimp tester. After the paper was cut, an initial load (0.18
mN x tex) was applied to the sample and the distance between
the chucks (the spatial distance) (mm) was read. Inthat state,
the crimps were counted, thereby determining the number of
crimps per 25mm. The crimps were countedin such amannerthat
all the peaks and valleys were counted and the sum was halved.
[0080]
The above measurement was performed with respect to 20
5 fibers. The average was rounded to one decimal place, thus
determining the number of crimps of eccentric hollow conjugate
fibers. The number of crimps was measured under conditions in
accordance with JIS Z 8703 (standard conditions at testing
sites), namely, in a thermostatic chamber at a temperature of
10 20+2"~ and a humidity of 65k28.
[0081]
[Example 11
A propylene homopolymer (PP-1) was used which had a MFR
of 60 g/10 min as measured under 2160 g load at 230°C. This
15 propylene polymer was molten in an extruder (screw diameter:
75 mm) at a forming temperature of 240°C. A nonwoven fabric
production apparatus (a spunbonding apparatus, the length of
the collection surface in the direction perpendicular to the
machine direction: 320 mm) illustrated in Fig. 5 was equipped
20 with a spinning spinneret having nozzles at pitches of 4.5 mm
in the longitudinal direction and 4.0 mm in the traverse
direction as well as having a canal width/pore area of 0.41
mm-l. This spinneret had an orifice configuration illustrated
in Fig. 1 and was capable of forming hollow fibers with a cross
section illustrated in Fig. 2. The PP-1 melt was spun at an
output rate per orifice of 0.52 g/min and a filament speed of
4367 m/min while blowing cooling air ( 2 5 " ~fl~ow rate: 42
~m~/min/m).T he fibers were deposited onto a collection belt,
5 and the web was thermally compressed with embossing rolls
(emboss area percentage: 18%, embossing temperature: 132"~)
to give a spunbonded nonwoven fabric having a basis weight of
15 g/m2.
[0082]
10 In Fig. 5, the reference signs are extruder 1, spinning
spinneret 2, hollow fibers 3, cooling air 4, diffuser 5,
collection device 6, suction device 7, and web (spunbonded
nonwoven fabric) 8.
[0083]
15 The hollow fibers and the spunbonded nonwoven fabric
obtained were tested to evaluate the C-axis orientation, the
average fiber diameter, the fineness, the single filament
strength, the hollowness and the number of crimps of the hollow
fibers, as well as the flexural rigidity, the tensile strength
20 and the FUKURAMI value of the spunbonded nonwoven fabric. The
results are described in Table 1.
[0084]
[Example 21
A spunbonded nonwoven fabric having a basis weight of 15
g/m2 was obtained in the same manner as in Example 1, except
that the PP-1 was spun at an output rate per orifice of 0.6
g/min and a filament speed of 4338 m/min.
[0085]
5 The filaments andthe spunbondednonwoven fabricobtained
were tested to evaluate the C-axis orientation, the average
fiber diameter, the fineness, the single filament strength,
the hollowness and the number of crimps of the hollow fibers,
as well as the flexural rigidity, the tensile strength and the
10 FUKURAMI value of the spunbondednonwoven fabric. The results
are described in Table 1.
[0086]
[Example 31
A spunbonded nonwoven fabric having a basis weight of 15
15 g/m2 was obtained in the same manner as in Example 2, except
that the forming temperature in the extruder (screw diameter:
75 mrn) was changed to 220'~ and the melt was spun at a filament
speed of 3013 m/min.
[0087]
2 0 The filaments and the spunbondednonwoven fabric obtained
were tested to evaluate the C-axis orientation, the average
fiber diameter, the fineness, the single filament strength,
the hollowness and the number of crimps of the hollow fibers,
as well as the flexural rigidity, the tensile strength and the
-
FUKURAMI value ofthe spunbondednonwoven fabric. The results
are described in Table 1.
[0088]
[Example 41
5 (Production of spunbonded nonwoven fabric)
A spunbonded nonwoven fabric was produced in the same
manner as in Example 2, except that the basis weight of the
spunbonded nonwoven fabric was changed to 6.15 g/m2.
[0089]
10 (Production of nonwoven fabric laminate)
Apropylene homopolymer (PP-2, MFR: 850 g/lOmin, melting
point: 159"~)wa s supplied to a die of a meltblowing apparatus.
The die temperature was set to 280"~. The polymer was extruded
through meltblowing nozzles (diameter: 0.32 mm, pore to pore
15 distance in the nozzles: 0.20 mm) at an output rate per nozzle
orifice of 0.52 g/min while simultaneously blowing
high-temperature high-speed air (280°c, 600 m3/hr) from both
sides of the nozzles. The DCD (the die to collector distance)
was 120 mm. In this manner, a meltblown nonwoven fabric having
20 a basis weight of 0.7 g/m2 was deposited onto one surface of
the spunbonded nonwoven fabric obtained above, thereby
producing a laminate including the spunbonded nonwoven fabric
andthemeltblownnonwovenfabric. Next, a spunbondednonwoven
fabric was laminated onto the meltblown nonwoven fabric under
the same conditions as described above. Thus, a nonwoven
fabric laminate having a total basis weight of 13.0 g/m2
(spunbonded nonwoven fabric/meltblown nonwoven
fabric/spunbonded nonwoven fabric = 6.15/0.7/6.15 g/m2) was
5 obtained.
[0090]
The nonwoven fabric laminate obtained was tested to
evaluate the C-axis orientation, the average fiber diameter,
the fineness, the single filament strength, the hollowness and
10 the number of crimps of the hollow fibers, as well as the
flexural rigidity, the tensile strength and the water pressure
resistance ofthe spunbondednonwoven fabric. The results are
described in Table 1.
[0091]
15 [Example 51
A nonwoven fabric laminate having a total basis weight
of 13.0 g/m2 (spunbonded nonwoven fabric/meltblown nonwoven
fabric/spunbonded nonwoven fabric = 6.15/0.7/6.15 g/m2) was
obtained in the same manner as in Example 4, except that the
20 meltblown nonwoven fabric was produced in such a manner that
the extruded fibers were cooled and dispersed with cooling air
(temperature 1 5 ' ~a~ir volume: 6000 m3/hr).
[0092]
The nonwoven fabric laminate obtained was tested to
0
evaluate the C-axis orientation, the average fiber diameter,
the fineness, the single filament strength, the hollowness and
the number of crimps of the hollow fibers, as well as the
flexural rigidity, the tensile strength and the water pressure
5 resistance ofthe spunbondednonwoven fabric. The results are
described in Table 1.
[0093]
[Example 61
A spunbonded nonwoven fabric having a basis weight of 15
10 g/m2 was obtained in the same manner as in Example 2, except
that a propylene/a-olefin random copolymer (PP-3) was used as
the propylene polymer which had a MFR of 60 g/10 min as measured
under 2160 g load at 2 3 0 " ~an d a melting point of 1 4 3 " ~as~
well as that this polymer was molten in the extruder (screw
15 diameter: 75 mm) at a forming temperature of 220°C and was spun
at a filament speed of 3013 m/min onto the collection belt,
and the web was thermally compressed with embossing rolls
(emboss area percentage: 18%, embossing temperature: 115°C) .
[0094]
20 The hollow fibers and the spunbonded nonwoven fabric
obtained were tested to evaluate the C-axis orientation, the
average fiber diameter, the fineness, the single filament
strength, the hollowness and the number of crimps ofthe hollow
fibers, as well as the flexural rigidity, the tensile strength
0
and the FUKURAMI value of the spunbonded nonwoven fabric. The
results are described in Table 1.
[0095]
[Example 71
5 A spunbonded nonwoven fabric having a basis weight of 15
g/m2 was obtained in the same manner as in Example 2, except
that the spinning spinneret used in Example 2 was replaced by
a spinning spinneret with a canal width/pore area of 0.41 mm-'
which had an orifice configuration illustrated in Fig. 3 and
10 was capable of forming eccentric hollow fibers with a cross
section illustrated in Fig. 4, as well as that the melt was
spun at a filament speed of 4390 m/min.
[0096]
The filaments andthe spunbondednonwoven fabric obtained
15 were tested to evaluate the C-axis orientation, the average
fiber diameter, the fineness, the single filament strength,
the hollowness and the number of crimps of the hollow fibers,
as well as the flexural rigidity, the tensile strength and the
FUKURAMI value ofthe spunbondednonwoven fabric. The results
20 are described in Table 1.
[0097]
[Example 81
A spunbonded nonwoven fabric having a basis weight of 15
g/m2 was obtained in the same manner as in Example 6, except
that the spinning spinneret used in Example 6 was replaced by
a spinning spinneret with a canal width/pore area of 0.41 mm-I
which had an orifice configuration illustrated in Fig. 3 and
was capable of forming eccentric hollow fibers with a cross
5 section illustrated in Fig. 4, as well as that the melt was
spun at a filament speed of 3048 m/min.
[0098]
The filaments andthe spunbondednonwovenfabricobtained
were tested to evaluate the C-axis orientation, the average
10 fiber diameter, the fineness, the single filament strength,
the hollowness and the number of crimps of the hollow fibers,
as well as the flexural rigidity, the tensile strength and the
FUKURAMI value ofthe spunbondednonwoven fabric. The results
are described in Table 1.
15 [0099]
[Table 11
SF-2466
Table 1
Nonwoven
[Comparative Example 11
A spunbonded nonwoven fabric having a basis weight of 15
g/m2 was obtained in the same manner as in Example 1, except
that the spinning spinneret for hollow fiber production used
in Example 1 was replaced by a spinning spinneret with circular
pores 0.6 mm in diameter (for solid fiber production), as well
as that the melt was spun at a filament speed of 4283 m/min.
[OlOO]
The filaments andthe spunbondednonwoven fabricobtained
were tested to evaluate the C-axis orientation, the average
fiber diameter, the fineness, the single filament strength and
thenumber of crimps ofthe solid fibers, aswell as the flexural
rigidity, the tensile strength and the FUKURAMI value of the
spunbondednonwovenfabric. The results aredescribedinTable
2.
[OlOl]
[Comparative Example 21
A spunbonded nonwoven fabric having a basis weight of 15
g/m2 was obtained in the same manner as in Example 2, except
that the polymer was molten in the extruder (screw diameter:
75 mm) at a forming temperature of 260"~an d the melt was spun
at a filament speed of 4100 m/min while blowing cooling air
( 2 5 " ~fl~ow rate: 35 ~m~/min/m).
[0102]
The f i l a m e n t s a n d t h e spunbondednonwovenfabricobtained
were t e s t e d t o e v a l u a t e t h e C-axis o r i e n t a t i o n , t h e average
f i b e r d i a m e t e r , t h e f i n e n e s s , t h e s i n g l e f i l a m e n t s t r e n g t h ,
t h e hollowness and t h e number of crimps of t h e hollow f i b e r s ,
5 a s w e l l a s t h e f l e x u r a l r i g i d i t y , t h e t e n s i l e s t r e n g t h and t h e
FUKURAMI value o f t h e spunbondednonwoven f a b r i c . The r e s u l t s
a r e d e s c r i b e d i n Table 2.
[Comparative Example 31
A spunbonded nonwoven f a b r i c having a b a s i s weight of 15
10 g/m2 was o b t a i n e d by a spunbonding method i n t h e same manner
a s i n Comparative Example 2, except t h a t t h e polymer was molten
i n t h e e x t r u d e r (screw d i a m e t e r : 75mm) a t a formingtemperature
o f 2 0 0 ~ ~ a n d t h e m e l t wsapsu n a t a f i l a m e n t s p e e d o f 2 2 9 6 m / m i n .
[0103]
15 The f i l a m e n t s a n d t h e spunbondednonwoven f a b r i c o b t a i n e d
I were t e s t e d t o e v a l u a t e t h e C-axis o r i e n t a t i o n , t h e average
f i b e r d i a m e t e r , t h e f i n e n e s s , t h e s i n g l e f i l a m e n t s t r e n g t h ,
t h e hollowness and t h e number of crimps of t h e s o l i d f i b e r s ,
a s well a s t h e f l e x u r a l r i g i d i t y , t h e t e n s i l e s t r e n g t h and t h e
20 FUKURAMI v a l u e o f t h e spunbondednonwoven f a b r i c . The r e s u l t s
a r e d e s c r i b e d i n Table 2.
[0104]
[Comparative Example 41
A spunbonded nonwoven f a b r i c having a b a s i s weight o f 15
g/m2 was obtained in the same manner as in Example 1, except
that an open nonwoven fabric production apparatus (an open
spunbonding apparatus, the length of the collection surface
in the direction perpendicular to the machine direction: 320
5 mm) illustrated in Fig. 6 was used.
[0105]
In Fig. 6, the reference signs are extruder 1, spinning
spinneret 2, hollow fibers 3, cooling air 4, collection device
6, suction device 7, and web (spunbonded nonwoven fabric) 8.
10 [0106]
The filaments andthe spunbondednonwoven fabric obtained
were tested to evaluate the C-axis orientation, the average
fiber diameter, the fineness, the single filament strength,
the hollowness and the number of crimps of the solid fibers,
I 15 as well as the flexural rigidity, the tensile strength and the
FUKURAMI value ofthe spunbonded nonwoven fabric. The results
are described in Table 2.
[0107]
[Comparative Example 51
2 0 A spunbonded nonwoven fabric having a basis weight of 15
g/m2 was obtained in the same manner as in Comparative Example
4, except that the spinning spinneretwas replacedbya spinning
spinneret with circular pores 0.6 mm in diameter (for solid
fiber production), as well as that the melt was spun at a
f i l a m e n t speed of 3731 m/min.
The f i l a m e n t s a n d t h e spunbondednonwoven f a b r i c o b t a i n e d
were t e s t e d t o e v a l u a t e t h e C-axis o r i e n t a t i o n , t h e average
5 f i b e r d i a m e t e r , t h e f i n e n e s s , t h e s i n g l e f i l a m e n t s t r e n g t h and
thenumber o f crimps o f t h e s o l i d f i b e r s , a s well a s t h e f l e x u r a l
r i g i d i t y , t h e t e n s i l e s t r e n g t h and t h e FUKURAMI value of t h e
spunbondednonwovenfabric. T h e r e s u l t s a r e d e s c r i b e d i n T a b l e
1 0 [0109]
[Comparative Example 61
A spunbonded nonwoven f a b r i c having a b a s i s weight o f 15
g/m2 was o b t a i n e d i n t h e same manner a s i n Example 6, except
I t h a t t h e s p i n n i n g s p i n n e r e t f o r hollow f i b e r production used
15 i n Example 6 was r e p l a c e d b y a s p i n n i n g s p i n n e r e t w i t h c i r c u l a r
pores 0.6 rnm i n diameter ( f o r s o l i d f i b e r p r o d u c t i o n ) , a s well
a s t h a t t h e m e l t was spun a t a f i l a m e n t speed of 2591 m/min.
[ O l l O ]
The f i l a m e n t s a n d t h e spunbondednonwoven f a b r i c o b t a i n e d
20 were t e s t e d t o e v a l u a t e t h e C-axis o r i e n t a t i o n , t h e average
f i b e r d i a m e t e r , t h e f i n e n e s s , t h e s i n g l e f i l a m e n t s t r e n g t h and
thenumber of crimps o f t h e s o l i d f i b e r s , a s well a s t h e f l e x u r a l
r i g i d i t y , t h e t e n s i l e s t r e n g t h and t h e FUKURAMI value of t h e
spunbondednonwoven f a b r i c . The r e s u l t s a r e d e s c r i b e d i n T a b l e
[Comparative Example 71
A spunbonded nonwoven fabric having a basis weight of 15
5 g/m2 was obtained in the same manner as in Example 2, except
that the spinning spinneret used in Example 2 was replaced by
a spinning spinneretforhollowfiberproductionasillustrated
in Fig. 1 which had a canal width/pore area of 0.28 mm-l, as
well as that themelt was spun at a filament speed of 3807 m/min.
i lo [0112]
I The filaments andthe spunbondednonwoven fabric obtained
were tested to evaluate the C-axis orientation, the average
I fiber diameter, the fineness, the single filament strength,
I the hollowness and the number of crimps of the solid fibers,
15 as well as the flexural rigidity, the tensile strength and the
FUKURAMI value ofthe spunbondednonwoven fabric. The results
are described in Table 2.
[0113]
[Comparative Example 81
20 A nonwoven fabric laminate having a total basis weight
of 13.0 g/m2 (spunbonded nonwoven fabric/meltblown nonwoven
fabric/spunbonded nonwoven fabric = 6.15/0.7/6.15 g/m2) was
obtained in the same manner as in Example 4, except that the
spinning spinneret for hollow fiber production usedin Example
4 was r e p l a c e d by a s p i n n i n g s p i n n e r e t with c i r c u l a r pores 0.6
mm i n diameter ( f o r s o l i d f i b e r p r o d u c t i o n ) , a s w e l l a s t h a t
t h e m e l t was spun a t a f i l a m e n t speed of 2591 m/min.
[0114]
5 The nonwoven f a b r i c l a m i n a t e o b t a i n e d was t e s t e d t o
e v a l u a t e t h e C-axis o r i e n t a t i o n , t h e average f i b e r d i a m e t e r ,
t h e f i n e n e s s , t h e s i n g l e f i l a m e n t s t r e n g t h and t h e number of
crimps of t h e hollow f i b e r s , a s well a s t h e f l e x u r a l r i g i d i t y ,
t h e t e n s i l e s t r e n g t h and t h e water p r e s s u r e r e s i s t a n c e of t h e
1 0 spunbondednonwovenfabric. The r e s u l t s a r e d e s c r i b e d i n T a b l e
2.
[0115]
[Table 21
Table 2
Basis weight
Nonwoven
INDUSTRIAL APPLICABILITY
The spunbonded nonwoven fabrics according tothe present
invention exhibit excellent uniformity, high strength and
5 flexibility even in the case where the fiber diameter of hollow
fibers is reduced to 20 pm or less as well as where the basis
weight is reduced. Sufficient strength can be ensured even if
thebasis weight is decreasedto alowerlevelthan conventional.
Thus, the nonwoven fabrics can be made advantageously
10 lightweight and can be suitably used in materials such as
medicalmaterials, industrialmaterials, civil engineering and
building materials, agricultural and gardening materials, and
daily life materials, in detail, can be widely used in products
such as surgical gowns, bandages, bedclothes including bed
15 sheets and pillowcases, and substrates for carpets and
artificial leathers.
[0117]
The nonwoven fabric laminates including the inventive
spunbonded nonwoven fabrics are lightweight, and also have
20 flexibility and good texture. Thus, such nonwoven fabric
laminates may be particularly suitably used in sanitary
materials such as disposable diapers, solid gather sheets and
sanitary napkins.
REFERENCE SIGNS LIST
1 . . . EXTRUDER
2 . . . SPINNING SPINNERET
3 . . . HOLLOW FIBERS
5 4 . . . COOLING AIR
5 . . . DIFFUSER
6 . . . COLLECTION DEVICE
7 . . . SUCTION DEVICE
8 . . . SPUNBONDED NONWOVEN FABRIC

CLAIMS
[Claim 11
A spunbonded nonwoven fabric comprising hollow fibers of
apropylene polymer, the hollow fibers satisfying the following
5 requirements (a) to (c) :
(a) the C-axis orientation is at least 0.85,
(b) the average fiber diameter is 5 to 20 pm, and
(c) the hollowness is 5 to 30%.
[Claim 21
10 The spunbonded nonwoven fabric according to claim 1,
wherein (d) the basis weight is 5 to 20 g/m2.
[Claim 31
The spunbonded nonwoven fabric according to claim 1,
wherein the propylene polymer is a propylene/a-olefin random
15 copolymer.
[Claim 41
A nonwoven fabric laminate comprising the spunbonded
nonwoven fabric described in any one of claims 1 to 3.
[Claim 51
A nonwoven fabric laminate comprising the spunbonded
nonwoven fabric described in any one of claims 1 to 3, and a
meltblown nonwoven fabric laminated thereto.
[Claim 61
The nonwoven fabric laminate according to claim 5,
wherein the meltblown nonwoven fabric comprises polyolefin
fibers and has (i) an average fiber diameter of not more than
2.0 pm, (ii) a coefficient of variation of fiber diameter (CV)
of not more than 60%, and (iii) a number of fusion bonding per
5 100 fibers of not more than 15.
[Claim 71
The nonwoven fabric laminate according to claim 5,
wherein the meltblown nonwoven fabric comprises propylene
polymer fibers and has (i) an average fiber diameter of not
10 more than 2.0 pm, (ii) a coefficient of variation of fiber
diameter (CV) of not more than 60%, and (iv) an a-crystal
fraction of less than 0.9.
[Claim 81
A disposable diaper utilizing the spunbonded nonwoven
15 fabric described in claim 1 or 2.
[Claim 91
A sanitary product comprising the nonwoven fabric
laminate described in any one of claims 4 to 7.
[Claim 101
The spunbonded nonwoven fabric according to claim 1,
wherein the hollow fibers have an eccentric hollow.
[Claim 111
A spunbonded nonwoven fabric comprising hollow fibers
formed from a thermoplastic resin, the hollow fibers having
SF-2466
0
an eccentric hollow.
[Claim 121
A nonwoven fabric laminate comprising the spunbonded
nonwoven fabric described in claim 11.
5 [Claim 131
A disposable diaper utilizing the spunbonded nonwoven
fabric described in claim 11.
I [Claim 141
A sanitary product comprising the nonwoven fabric
10 laminate described in claim 12.
Dated this 1 1.09.2013