DESCRIPTION
TITLE OF INVENTION
MELT-BLOWN NONWOVEN FABRIC, AND PRODUCTION PROCESS AND
APPARATUS FOR THE SAME
5
Technical Field
[ O O O l ]
The present invention r e l a t e s t o amelt-blown nonwoven f a b r i c
which comprises u l t r a f i n e f i b e r s , is f l e x i b l e , has excellent
10 uniformity and is favorably used f o r f i l t e r s , s a n i t a r y materials and
b a t t e r y separators, and a production process and an apparatus f o r
the same.
Background A r t
15 [OOOZ]
Sincemelt-blownnonwoven f a b r i c s canbe composedof u l t r a f i n e
f i b e r s as compared with spun bonded nonwoven f a b r i c s , they have
excellent f l e x i b i l i t y and are used not only f o r f i l t e r s but also f o r
s a n i t a r y m a t e r i a l s , clothes, packagingmaterials,batteryseparators,
20 etc. byusing themsinglyor laminating themonto others such as nonwoven
f a b r i c s .
[0003]
For producing the melt-blown nonwoven f a b r i c s , a molten r e s i n
is subjected t o drawing and thinning by means of a f l u i d of high
temperature and high velocity, and therefore, b a l l - l i k e substances
(shots) and fly-like substances are l i a b l e t o be formed, and various
methods t o solve them have been proposed.
[0004]
5 For example, there have been proposed various methods, such
as a method in which a shape of a die nose t i p of a melt-blowing die,
the distance between a die nose t i p and a l i p p l a t e t i p , etc. are
set in t h e s p e c i f i c ranges (patent l i t e r a t u r e 1: Japanese Patent
Laid-OpenPublicationNo.1979-103466), amethodinwhichadiehaving
10 a l i p plate t i p width ( i n t e r v a l between a i r knives) of 0.4 t o 0.8
m i s u s e d ( p a t e n t l i t e r a t u r e 2 : JapanesePatentLaid-OpenPublication
No. 1992-91267), a method in which a melt-blown nonwoven fabric is
produced under the conditions of a nozzle o r i f i c e diameter of 0.1
t o 0.5 m and a discharge rate per single hole of 0.05 t o 0.8 g/min,
15 preferably 0 . 1 t o 0.5 g/min (patent l i t e r a t u r e 3: Japanese Patent
Laid-Open PublicationNo. 1993-295645), amethodinwhichthe spacing
( a i r gap) of a drawing f l u i d flow path, the distance between a die
nose t i p and a l i p p l a t e t i p , and the r a t i o between them are s e t in
the specific ranges (patent l i t e r a t u r e 4: Japanese Patent Laid-Open
20 Publication No. 2009-200135) and a method in which the mean f i b e r
diameter is set in the range of 0 . 1 t o 5.0 pm (patent l i t e r a t u r e 5:
Japanese Patent Laid-Open Publication No. 1992-163353).
[0005]
As amethod t o obtain amelt-blownnonwoven fabric of thin f i b e r s ,
a method in which secondary blowing air having a temperature of not
lower than 50°cis blownagainstspun filamentstransverselyto delay
cooling and solidification of the spun filaments, whereby thinning
is carried out (patent literature 6: Japanese Patent Laid-Open
5 Publication No. 2006-83511) has been proposed.
[0006]
In the existing circumstances, melt-blown nonwoven fabrics
having a little narrower fiber diameter distribution can be produced
by the above methods proposed, but formation of thick fibers each
10 havinga fiberdiameteroftwiceormorethemeanfiberdiametercaused
by fusion bonding of fibers during the melt extrusion cannot be
completely prevented.
[0007]
In the method in which the mean fiber diameter is set in the
15 range of 0.1to 5.0 pm (patent literature 5: Japanese Patent Laid-Open
Publication No. 1992-163353), a melt-blown nonwoven fabric wherein
the coefficient of variation (CV) of fiber diameter was not more than
30% was obtained, but when the melt-blown nonwoven fabric obtained
by the method described in the patent literature 5 was evaluated by
20 the evaluation method described in the examples of the present
invention, the coefficient of variation (CV) of fiber diameter was
90%.
Citation List
Patent Literature
[0008]
P a t e n t l i t e r a t u r e l : Japanese Patent Laid-Open PublicationNo.
1979-103466
5 P a t e n t l i t e r a t u r e 2 : Japanese Patent Laid-Open PublicationNo.
1992-91267
Patent l i t e r a t u r e 3: Japanese Patent Laid-OpenPublicationNo.
1993-295645
Patent l i t e r a t u r e 4: Japanese Patent Laid-Open PublicationNo.
10 1999-200135
Patent l i t e r a t u r e 5: Japanese Patent Laid-OpenPublicationNo.
1992-163353
Patent l i t e r a t u r e 6: Japanese Patent Laid-OpenPublicationNo.
2006-83511
15
Summary of Invention
Technical Problem
[0009]
In the l i g h t of such actual circumstances i n the p a s t a s above,
20 i t i s a n o b j e c t o f t h e p r e s e n t i n v e n t i o n t o o b t a i n a p r o c e s s f o r stably
producing a melt-blown nonwoven f a b r i c comprising t h i n f i b e r s and
having extremely few thick f i b e r s [number of fusion-bonded f i b e r s ]
fomedbyfusionbondingofthemoplasticresinfiberstooneanother,
a production apparatus for the melt-blown nonwoven f a b r i c , and the
melt-blown nonwoven fabric.
Solution to Problem
[ OOlO]
5 The present invention relates to:
amelt-blownnonwoven fabric comprisingpolyolefin fibers and
having :
(i) a mean fiber diameter of not more than 2.0 pm,
(ii) a fiber diameter distribution CV value of not more than
10 60%, and
(iii) 15 or less fusion-bonded fibers based on 100 fibers; and
a production process for a melt-blown nonwoven fabric,
comprising spinningoutamoltenthermoplastic resinthroughanozzle
havingalargenumberofsmallholeslinedup, saidmoltenresinhaving
15 been forcedly fed to a melt-blowing die, and accumulating fibers on
a moving collection plate, said fibers being obtained by drawing and
thinningthemoltenresinbyhigh-temperaturehigh-velocityairgushed
out from slits provided so as to interpose a line of the small holes
therebetween, wherein:
20 a cooling fluid of not higher than 3 0 " p~re~f erably cooling
air, is fed fromboth side surfaces of outlets ofthe slits fromwhich
the high-temperature high-velocity air is gushed out, to cool the
spun thermoplastic resin fibers; and
a production apparatus for a melt-blown nonwoven fabric, in
which an attachment to introduce a cooling fluid for cooling the spun
thermoplastic resin fibers has been removably mounted on the tip of
the melt-blowing die.
5 Advantageous Effects of Invention
[OOll]
Themelt-blownnonwovenfabricofthepresentinventioncontains
extremely few thick fibers formed by fusion bonding of fibers to one
another, and therefore, for example, a filter using the melt-blown
10 nonwoven fabric has a feature that the fine particle collection
efficiency is extremely high.
[0012]
According to the production process and the apparatus for a
melt-blown nonwoven fabric of the present invention, a melt-blown
15 nonwovenfabriccomprisingthinfibersandveryrarelysufferingfusion
bonding of thin fibers can be stably produced.
[0013]
The production apparatus ofthe present invention has a simple
and compact structure and can be made up without largely changing
20 design of a general purpose production apparatus.
Brief Description of Drawings
[0014]
[Fig.l] Fig.1isaschematicperspectiveviewofaconventional
production apparatus for a melt-blown nonwoven fabric, which has the
same basic constitution as that of the production apparatus for a
melt-blown nonwoven fabric of the present invention.
[Fig. 21 Fig. 2isaschematicperspectiveviewofamelt-blowing
5 dieoftheproductionapparatusforamelt-blownnonwovenfabricshown
in Fig. 1, said melt-blowing die being seen from the lower surface
side.
[Fig. 31 Fig. 3 is a schematic sectional view showing an e s s e n t i a l
part of a production apparatus for a melt-blown nonwoven fabric in
10 one working example of the present invention.
[Fig. 41 Fig. 4 is a schematic view showing a flow of a i r in
aproductionapparatus foramelt-blownnonwovenfabricinoneworking
example of the present invention.
[Fig. 51 Fig. 5isaviewshowingadistancebetweenneighboring
15 small holes 1 4 .
Description of Embodiments
[0015]

20 As the thermoplastic resins t h a t become raw materials of
u l t r a f i n e f i b e r s f o r forming the melt-blown nonwoven fabric of the
present invention, a variety of publicly known thermoplastic resins
can be used.
[0016]
arehomopolymersorcopolymersofa-olefinssuchasethylene,propylene,
1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene, e.g.,
high-pressure low-density polyethylene, linear low-density
5 polyethylene (so-called LLDPE), high-density polyethylene,
polypropylene (propylene homopolymer), polypropylene random
copolymer, poly-1-butene, poly-4-methyl-1-pentene,
ethylene/propylene random copolymer, ethylene/l-butene random
copolymer and propylene/l-butene random copolymer; polyesters
10 (polyethylene terephthalate, polybutylene terephthalate,
polyethylene naphthalate, etc. ) , polyamides (nylon 6, nylon 66,
polymetaxylene adipamide, etc.), polyvinyl chloride, polyimide,
ethylene/vinylacetatecopolymer,polyacrylonitrile,polycarbonate,
polystyrene, ionomer, andmixturesthereof. Of these, high-pressure
15 low-densitypolyethylene,linearlow-densitypolyethylene (so-called
LLDPE), high-density polyethylene, propylene-based polymers, such
as polypropylene and polypropylene random copolymer, polyethylene
terephthalate, polyamides, etc. are preferable.
[0017]
20
Oftheabovethemoplasticresins,thepropylene-basedpolymer
is preferable because the resulting melt-blown nonwoven fabric has
The propylene-based polymer is a homopolymer of propylene or
a copolymer of propylene and an extremely small amount of one or more
a-olefins having 2 or more carbon atoms, preferably 2 t o 8 carbon
atoms, suchas ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene and
5 4-methyl-1-pentene, said homopolymer and copolymer having a melting
point (Tm) of not lower than 1 5 5 ' ~p~re ferably 157 t o 165OC, and
preferable is a propylene homopolymer.
[0019]
The melt flow rate (MFR: ASTM D 1238, 230°C, load of 2160 g)
10 ofthepropylene-basedpolymeris not s p e c i f i c a l l y r e s t r i c t e d a s f a r
as the propylene-based polymer can be subjected t o melt spinning,
but the melt flow r a t e is usually in the range of 1 t o 1000 9/10 min,
preferably 5 t o 500 9/10 min, more preferably 10 t o 100 9/10 min.
[0020]
15
The productionprocess for amelt-blownnonwoven fabric o f t h e
present invention is a production process for a melt-blown nonwoven
fabric, comprising spinningoutamoltenthermoplastic resin (molten
resin) through a nozzle having a large number of small holes lined
20 up, saidmoltenresinhavingbeen forcedly fed t o amelt-blowingdie,
and accumulating f i b e r s on a moving c o l l e c t i o n p l a t e , said f i b e r s
being obtained by drawing and thinning the molten resin by
high-temperature high-velocity a i r gushed out from slits provided
so as t o interpose a l i n e of the small holes therebetween, wherein
a cooling fluid of not higher than 30°c, preferably 5 to 2 5 " m~or~e
preferably 5 to 20°C, is fed from both side surfaces of outlets of
the slits fromwhichthehigh-temperaturehigh-velocityairisgushed
out, to cool the spun thermoplastic resin fibers.
5 [0021]
Examples of the cooling fluids include water and air, but if
water is used, there is a fear that moisture remains in the nonwoven
fabric to thereby mildew the nonwoven fabric. Moreover, a minute
amount of a metal component derived from water adheres to the fibers,
10 and therefore, such a fabric is undesirable as a nonwoven fabric for
microfilter usedinthe semiconductor industry or a nonwoven fabric
for separator.
[0022]
On this account, the cooling fluid is preferably cooling air.
15 [0023]
According tothe production process for amelt-blown nonwoven
fabric of the present invention, the temperature of the
high-temperaturehigh-velocityair flow is loweredtonot higherthan
a given temperature by being joined with a cooling fluid when the
20 spun thermoplastic resin fibers are drawn and thinned by the
high-temperature high-velocity air, whereby fusion bonding of the
fibers to one another can be prevented, and thereby, thick fibers
[number of fusion-bonded fibers] formed by fusion bonding of the fibers
to one another can be decreased.
[0024]

The production apparatus for a melt-blown nonwoven fabric of
the present invention is a production apparatus for a melt-blown
5 nonwoven fabric, which performs spinning of a molten thermoplastic
resin through a nozzle having a large number of small holes lined
up, saidmolten resinhavingbeen forcedly fed to amelt-blowingdie,
and accumulating of fibers on a moving collection plate, said fibers
being obtained by drawing and thinning the molten resin by
10 high-temperature high-velocity air gushed out from slits provided
so as to interpose a line of the small holes therebetween, wherein
an attachment to introduce a cooling fluid, preferably cooling air,
for cooling the spun thermoplastic resin fibers has been removably
mounted on the tip of the melt-blowing die.
15 [0025]
Here, the attachment has been preferably mounted on the tip
of the melt-blowing die without any space.
[0026]
The expression "without any space" means that an air passage
20 to introduce external air is not formed.
[0027]
According to such constitution, a cooling air flow is given
along the nozzle surface, and even when a cooling fluid, preferably
cooling air, for cooling the fibers obtained by drawing and thinning
the resin by high-temperature high-velocity air is introduced, no
swirling flow occurs, and a mixture of the high-temperature
high-pressure air andthe cooling fluidcanbe leddownwardinorder.
By virtue of this, the resin fibers can be guided downward while
5 preventing twisting or fusion bonding of the fibers.
[0028]

The production process and the production apparatus for a
10 melt-blown nonwoven fabric using the propylene-based polymer are
further described below referring to the drawings.
[0029]
Fig. 1 and Fig. 2 are each a schematic view showing a conventional
productionapparatus foramelt-blownnonwovenfabric, whichhasbeen
15 used in the past.
[0030]
Inthisproductionapparatus2foramelt-blownnonwovenfabric,
a collection plate composed of a mesh conveyer 6 is arranged below
a melt-blowing die 4, and below this mesh conveyer 6, a suction box
20 8 the interior of which can be sucked by a pressure reducing means
(suction) is arranged.
[0031]
On the lateral side of the suction box 8, a roller 9 to move
(rotate) the mesh conveyer 6 is arranged, and above the downstream
SF-2441
13
side thereof, a wind-up roller (not shown) to wind up the melt-blown
nonwoven fabric is arranged.
[0032]
AsshowninFig. 2, onthelower surfacesideofthemelt-blowing
5 die 4, a die nose 12 having a sectional shape of an isosceles triangle
is arranged, and at the central part of this die nose 12, a nozzle
16 having plural small holes 14 disposed in a line is arranged. The
molten resin having been fed into a resin passage 18 is pushed out
downward from the small holes 14 of the nozzle 16. In Fig. 2, one
10 fiber 10 pushed out is only shown. On the other hand, slits 31 and
31 are formed so that they may interpose the line of the small holes
14 of the nozzle 16 from both sides of the line, and these slits 31
and 31 constitute air passages 20a and 20b. When the molten resin
is pushed out, the high-temperature high-pressure air fed through
15 the air passages 20a and 20b is gushed out in the obliquely downward
direction.
[0033]
Inusual, thediameter ofthe small hole14 formedinthenozzle
16 is preferably 0.05 mm to 0.4 mm. If the diameter of the small
20 hole 14 is less than 0.05 mm, the resulting fibers have non-uniform
shapes from the viewpoint of processing accuracy, and the CV ( % ) of
the fiber diameter becomes larger, so that such a diameter is
undesirable. Moreover, a problem that the holes are liable to be
clogged in the long-term operation because of deterioration of the
polymer, etc. occurs, so t h a t such a diameter is undesirable. On
the other hand, i f the diameter is l a r g e r than 0.4 mm, it becomes
d i f f i c u l t t o obtain u l t r a f i n e f i b e r s , so t h a t such a diameter is
undesirable.
5 [0034]
The single hole discharge r a t e of the molten r e s i n is usually
0.05 g/min t o 3.0 g/min, preferably 0.1 g/min t o 2.0 g/min. I f the
discharge r a t e is less than 0.05 g/min, not only is the productivity
loweredbut also broken f i b e r called f l y tends t o occur, so t h a t clogging
I 10 of holes is l i a b l e t o take place during the continuous operation.
On the other hand, i f the discharge r a t e is more than 3.0 g/min, there
is a fear t h a t s u f f i c i e n t thinning is not performed.
[0035]
When the melt-blown nonwoven f a b r i c is used f o r a s a n i t a r y
15 material, low cost is desired from the viewpoint of properties of
the manufactured a r t i c l e , and therefore, production a t a r e l a t i v e l y
high discharge r a t e is required. In t h i s case, the single hole
discharge r a t e is usually not l e s s than 0.2 g/min, preferably not
l e s s than 0.3 g/min. I f the discharge r a t e is less than 0.2 g/min,
20 there is a f e a r of low productivity.
[0036]
Thedistancebetweenthe smallholes14 (distancebetweenouter
peripheries oftheneighboringsmallholes, as showninFig. 5),though
depending upon the desired f i b e r diameter, is usually 0.01 t o 6.0
e
mm, preferably 0.15 to 4.0 mm. If the distance between the holes
is less than the lower limit of the above range, there is a fear of
occurrenceofbundle-like fibers formedbyfusionbondingortwisting
of plural fibers. The reason is thought to be that the probability
5 of contact of neighboring fibers with each other is increased, and
the fibers are liable to be fusion-bonded or twisted and become
bundle-like fibers. On the other hand, if the distance between the
holes exceeds the upper limit of the above range, entanglement of
the resulting fibers with one another is markedly lowered, and
10 dimensional stability of the melt-blown nonwoven fabric is lowered,
so that problems of lowering of strength of the nonwoven fabric and
formation of a nappy nonwoven fabric are liable to occur.
[0037]
In order to obtain amelt-blownnonwoven fabric of thin fibers,
15 e.g., a melt-blown nonwoven fabric having a fiber diameter of 0.1
to 0.8 pm, the distance between the holes is usually in the range
of 1.0 mm to 6.0 mm, preferably 1.5 mm to 4.0 mm, more preferably
2.0 mrn to 3.0 mm.
[0038]
20 When the melt-blown nonwoven fabric is used for a sanitary
material, low cost is desired from the viewpoint of properties of
the manufactured article, and therefore, production at a relatively
high discharge rate is required. In this case, low cost is desired
from the viewpoint of properties of the manufactured article, and
so that the amount of fibers is desired to be relatively increased.
On this account, the distance between the small holes 14 is usually
in the range of 0.1 mm to 2.0 nun, preferably 0.15 mm to 1.8 nun, more
5 preferably 0.21 mrn to 1.6 mm.
The air flow rate of the high-temperature high-pressure air
gushed out from the slit 31 is usually in the range of 200 ~m~/hr/m
to 1000 ~m~/hr/m.I f the air flow rate is less than 200 Nm3/hr/m,
10 thinning of the spun fibers is liable to become insufficient. On
the other hand, if the air flow rate exceeds 1000 Nm3/hr/m, the drawing
air velocity becomes an ultrasonic flow velocity, and an unsteady
state of the flow is liable to become high.
[0040]
15 The conventional production apparatus 2 for a melt-blown
nonwoven fabric roughly has such constitution as above. In such a
production apparatus 2 for a melt-blown nonwoven fabric, the fibers
10 obtained by drawing and thinning the molten resin by means of the
high-temperature high-velocity air, said molten resin having been
20 spun out through the nozzle 16 together with the high-temperature
high-pressure air, are bonded by means of self fusion bonding on the
mesh conveyer 6, and thereafter, they are wound up in order by a nonwoven
fabric wind-up roller (not shown) on the downstream side.
[0041]
In the production apparatus for a melt-blown nonwoven fabric
of the present invention, an attachment 32 to introduce cooling air
is newly removably mounted on the melt-blowing die 30 in addition
to such general purpose constitution as above, as shown in Fig. 3.
5 [0042]
That is to say, in the production apparatus of the present
invention, the high-temperature high-pressure air, such as
high-temperature high-pressure air of not lower than 2 8 0 " ~is~ f ed
throughthe airpassages 20aand20bI andinaddition, a cooling fluid
10 of not higher than 30°c, preferably cooling air, is horizontally fed
through the attachment 32. This makes it possible to produce a
melt-blownnonwovenfabriccomprisingthinfibersandhavingfewthick
fibers formed by fusion bonding of the fibers, that is, having 15
or less fusion-bonded fibers, preferably 12 or less fusion-bonded
15 fibers, more preferably 10 or less fusion-bonded fibers, based on
100 fibers in the present invention.
[0043]
Here, it is preferable that the attachment 32 is a member
separated from the melt-blowing die 30 and is removably mounted on
20 the melt-blowing die 30.
[0044]
The melt-blowing die 30 is usually heated up to about 280"~
by, for example, a heater, and therefore, it is necessary to mount
the attachment 32 for feeding cooling air having a large temperature
difference so t h a t heat propagation between the attachment 32 and
the melt-blowing die 30 should not occur. On that account, it is
preferable t o place, for example, a heat insulating material on the
5 a l i t t l e space between the melt-blowing die 30 and the attachment
However, when a l i t t l e space is l e f t between the melt-blowing
die 30 and the attachment 32 as above, it is necessary t o place a
10 shielding plate or the l i k e between the outer end surfaces of them
t o thereby stop up the space between t h e d i e 30 and the attachment
32 hermetically.
[0046]
If the attachment 32 is removably mounted on the melt-blowing
15 die 30 in such amanner as above, the cooling a i r fed from the attachment
32 is not irnmediatelymixed with the high-temperature high-pressure
a i r that is fed through the a i r passages 21a and 20b as described
l a t e r , butcanbeguideddownwardinthetemporarilyindependentstate
along the flow of the high-temperature high-pressure a i r , as shown
20 i n F i g . 4.
[0047]
if themelt-blowing die 30 and the attachment 32 are connected
toeachotherwithoutanyspaceasabove, that is, iftheyareconnected
s o t h a t anairpassage t o introduce external a i r shouldnot be formed,
any swirling flow does not occur above the attachment 32. By virtue
of this, the flow of the high-temperature high-pressure air in the
direction of an arrow A shown in Fig. 3 is not disturbed. Hence,
spinning and stretching are performed so as to give fibers having
5 desired fiber diameters.
[0048]
In the present invention, further, when the cooling air is
horizontally given in the direction of the arrow B, the
high-temperature high-pressure air and the cooling air are not mixed
10 immediately but mixed at a position a little lower than the position
at which they impinge on each other, as shown in Fig. 4. Hence, the
fibers 10 are not only drawn and thinned into desired fiber diameters
by means of the high-temperature high-pressure air but also cooled
rapidly.
15 [0049]
According to the present invention, therefore, the fibers are
cooledrapidlyafterthecoolingairismixedwiththehigh-temperature
air, whereby fusion bonding of the fibers to one another can be prevented
as much as possible.
20 [0050]

By the use of the production process and the production apparatus
for a melt-blown nonwoven fabric of the present invention and by the
useofpolyolefinamongtheaforesaidthermoplasticresinsthatbecome
raw materials, a melt-blown nonwoven fabric having the following
properties can be produced.
[0051]
That is to say, the melt-blown nonwoven fabric of the present
5 inventionisamelt-blownnonwovenfabriccomprisingpolyolefinfibers
and having:
(i) a mean fiber diameter of not more than 2.0 pm,
(ii) a fiber diameter distribution CV value of not more than
60%, preferably not more than 50%, and
10 (iii) 15 or less fusion-bonded fibers, preferably 12 or less
fusion-bondedfibers,morepreferably10orlessfusion-bondedfibers,
based on 100 fibers.
[0052]
By the use of the production process and the production apparatus
15 for a melt-blown nonwoven fabric of the present invention and by the
use of a propylene-based polymer among the aforesaid thermoplastic
resinsthat become rawmaterials, amelt-blownnonwoven fabrichaving
the following properties can be produced.
[0053]
20 That is to say, the melt-blown nonwoven fabric of the present
inventionis amelt-blownnonwoven fabric comprisingpropylene-based
polymer fibers and having:
(i) a mean fiber diameter of not more than 2.0 pm,
(ii) a fiber diameter distribution CV value of not more than
60%, preferably not more than 50%, and
( i v ) an a c r y s t a l fraction of l e s s than 0.9.
[0054]
Whentheaboveproperties (i),( ii)a nd (iii)a renot s a t i s f i e d ,
5 or when the above properties (i), (ii) and (iv) are not s a t i s f i e d ,
cooling of the f i b e r s obtained by drawing and thinning is not
s u f f i c i e n t l y e f f e c t e d , andpluralfibersarefusion-bondedortwisted
tobring aboutmanybundle-like f i b e r s . On t h i s account, large voids
are l i a b l e t o be formed in the nonwoven fabric t o thereby lower functions
10 of the nonwoven fabric, such as f i l t e r i n g performance and water
r e s i s t i n g performance.
[0055]
Themelt-blownnonwovenfabricofthepresentinventionismost
preferably a melt-blown nonwoven fabric comprising the
15 propylene-based polymer f i b e r s and s a t i s f y i n g t h e properties (i),
(ii), (iii)a nd ( i v ) a t the same time.
(i) Mean f i b e r diameter
The mean fiber diameter is usually not more than 2.0 p. In
the use for sanitary materials, the mean fiber diameter is not more
20 than 2 pm, preferably not more than 1.8 pm. I n t h e use for f i l t e r s ,
the mean f i b e r diameter is not more than 0.8 pm, preferably 0.3 t o
0.6 p.
[0056]
The a c r y s t a l fraction in the propylene-based polymer f i b e r s
obtained by the melt-blowing process is less than 0.9, preferably
less than 0.7, more preferably less than 0.6. If the a crystal fraction
exceeds 0.9, cooling of the fibers obtained by drawing and thinning
I is not sufficiently effected, and plural fibers t are fusion-bonded
P
5 or twisted to bring about many bundle-like fibers. On this account,
I
large voids are liable to be formed in the nonwoven fabric to thereby
lower functions ofthenonwoven fabric, suchas filteringperformance
I and water resisting performance. It is most preferable that the
melt-blown nonwoven fabric of the present invention composed of the
1a 10 propylene-based polymer fibers has a crystallinity of less than 40% I
in addition to the a crystal fraction of the above range.
1 The a crystal fraction in the propylene-based polymer fibers,
i
I that is, crystalline property, is described below in detail.
X
I
2 15 Evaluation of crystalline property and orientation property by the
I
use of X rays has been introduced by many publicly known literatures
I E in the past, andat present, this is an evaluationmethodestablished
I
as an analysis of polymer structures. This evaluation method is
described in, for example, the Society of Polymer Science, Japan,
20 ed., "KobunshiJikken-gakuKozaDai-2-kan (PolymerExperimentCourse,
Vol. 2) ", Kyoritsu Shuppan Co., Ltd. (1958) , Isamu Nitta ed., "X-sen
Kessho-gaku, Jo (X-ray Crysatallography, the first volume) ", Maruzen
Co., Ltd. (1959), Kakudo, Kawai and Saito ed., "Kobunshi no Kozo to
Bussei (Structures and Properties of Polymers)", Yukichi Kure and
Kiichiro Kubo: "Koka", 39, 929 (1939) , etc. Evaluation of crystalline
property in the present invention was carried out in accordance with
the evaluation method of these publicly known literatures, and
specifically, thecrystallinepropertywas evaluatedinthe following
5 manner. The total scattering intensity curve of X rays in the wide
angleX-raydiffractionprofilewasseparatedintoacrystallineregion
due to scattering contribution and a non-crystalline region due to
scattering contribution, and the ratio of each area tothe total area
was evaluated as a crystalline property index value. For example,
10 it is known that a propylene-based polymer (polypropylene) has
diffraction peaks of crystalline property in the vicinities of 28:
14", 17", 18", 21" and 22"; polyethylene has diffraction peaks of
crystalline property in the vicinities of 28: 21°, 24" and 30";
polylactic acidhas diffractionpeaks of crystalline property in the
15 vicinities of 28: 16"and 18"; polyethylene terephthalate has
diffraction peaks of crystalline property in the vicinities of 28:
17", 18" and26";polytrimethyleneterephthlatehasdiffractionpeaks
of crystalline property in the vicinities of 28: go, 15", 17", 19",
23", 25", 28" and29"; andpolybutyleneterephthalatehas diffraction
20 peaks of crystalline property in the vicinities of 28: go, 16", 17",
20°, 2 3 " , 25" and 29". The evaluation is carried out by regarding
the region to which these crystalline property diffraction peaks
contribute, as the crystalline region, and separating this region
from the non-crystalline region.
[0058]
In the propylene-based polymer, two kinds of crystals of a
crystal and smectic crystal coexist in some cases, and from the
characteristic relationship between their peak intensities, the a
5 crystal and the smectic crystal are separated, and thereby, the a
crystal fraction is evaluated. By feeding the cooling fluid
(preferablycoolingair) havingaternperatureofnothigherthan3O0C,
preferably 5 to 25'~a~nd thereby cooling the spun molten resin, the
a crystal fraction of the nonwoven fabric of the present invention
10 can be set in the above range.
[0059]
On the melt-blown nonwoven fabric of the present invention,
other layers can be laminated according to various use purposes.
[0060]
15 Specific examples of other layers include layers of knitted
fabrics, woven fabrics, nonwoven fabrics and films. When the
melt-blown nonwoven fabric ofthe present invention and other layers
are laminated (bonded) on each other, a variety of publicly known
methods, e.g., thermalfusionbondingmethods, suchasheat embossing
20 method and ultrasonic fusion bonding method, mechanical entangling
methods, such as needle punch method and water jet method, methods
usingadhesivessuchashotmeltadhesivesandurethane-basedadhesives,
and extrusion laminating, can be adopted.
[0061]
Examples of the nonwoven fabrics laminated on the melt-blown
nonwovenfabricofthepresentinventionincludeavarietyofpublicly
known fabrics, such as spunbondednonwoven fabric, wet type nonwoven
fabric, drytypenonwoven fabric, drytypepulpnonwoven fabric, flash
5 spun nonwoven fabric and spread-fiber nonwoven fabric.
[0062]

The f i l t e r of the present invention is a f i l t e r containing a
layer composed of the melt-blown nonwoven fabric, and has a 0.5 mm
10 diameter fine p a r t i c l e c o l l e c t i o n e f f i c i e n c y of not l e s s than 99%
in the case of a basis weight of 90 g/cm2.
100631
The f i l t e r of the present invention may be a f i l t e r of a single
layerofthemelt-blownnonwovenfabricormaybeafilterofalaminate
1 15 structure of two or more layers. Further, the f i l t e r of the present
I
invention may be used by laminating it t o other f i l t e r materials,
I
such as dry type nonwoven fabric and porous membrane, depending upon
the use purpose.
[0064]
20
Thenonwovenfabriclaminatestructureofthepresentinvention
isanonwovenfabriclaminatestructurehavingthemelt-blownnonwoven
fabric on a t l e a s t one surface of which a spun bonded nonwoven fabric
is laminated, and the r a t i o of a basis weight (g/m2) of the melt-blown
nonwoven fabric layer t o a basis weight (g/m2) of the whole laminate
is not more than 0.050, preferably not more than 0.040.
[0065]
~nonwovenfabrichavingabasisweightratioofmorethan0.050
5 is l i a b l e t o have poor f l e x i b i l i t y and poor a i r permeability because
the basis weight of the melt-blown nonwoven fabric is high.

The battery separator of the present invention is a separator
containing a layer composed of the melt-blown nonwoven fabric, and
10 is desired t o have a mean fiber diameter of 0.1 t o 2.0 pm, preferably
0.2 t o 1.5 pm, more preferably 0.3 t o 1.0 pm, and a basis weight of
3 t o 30 g/m2, preferably 4 t o 25 cg/m2, more preferably 5 t o 15 g/m2.
Amean fiber diameter of sucha range is preferablebecause anonwoven
fabric having extremely fine pores can be produced, and f i b e r formation
15 by the melt-blowing process and production of a nonwoven f a b r i c a r e
smoothly carried out with high productivity. A basis weight of t h i s
range is preferable because when the separator is used for a battery,
thebatteryisfreefromshortcircuitandhaslowinternalresistance.
[0066]
i 20 In the lithiumionbatteryseparators o f t h e p r e s e n t invention,
I
a separator obtained by press forming of such a melt-blown nonwoven
fabric is included. The means for the press forming used for producing
the lithium ion battery separator of the present invention is not
s p e c i f i c a l l y r e s t r i c t e d , and any press forming means capable of
applying a pressure i n the thickness direction of the melt-blown
nonwoven fabric can be used. However, a press forming means in which
a p a r t coming into contact withat l e a s t one surface ofthemelt-blown
nonwoven fabric during pressing is formed from a material having
5 e l a s t i c i t y and having a high coefficient of f r i c t i o n is preferably
used. In such a press formingmeans, the elasticmodulus of the contact
part having e l a s t i c i t y is preferably 20 t o 600 kg/cm2, more preferably
20 t o 300 kg/cm2. Examples of the materials having e l a s t i c i t y and
having a high coefficient of f r i c t i o n include paper, cotton, wood,
10 rubberandfoamedplastic. Examplesoftherubbersamongtheminclude
urethane rubber, styrene/butadiene rubber, olefin-based elastomer,
thermoplastic elastomer and s i l i c o n rubber.
[0067]
Specificexamples o f t h e p r e s s formingmethodsincludeamethod
in which the melt-blown nonwoven fabric is pressed using a pressing
machine with a pressing surface having e l a s t i c i t y t h a t is made of
a rubber or the l i k e and a pressing surface made of a metal such as
s t a i n l e s s s t e e l , a method i n which the melt-blown nonwoven fabric
is calendered by calender r o l l s including a r o l l having e l a s t i c i t y
that is made of a rubber o r t h e l i k e and a r i g i d r o l l made of a metal
or the l i k e or including a pair of e l a s t i c r o l l s , and a method in
which the melt-blown nonwoven fabric is interposed between rubber
sheets o r t h e l i k e and then pressed or rolled.
[0068]
When one pressing part coming into contact with one surface
of the melt-blown nonwoven fabric is formed from a material having
e l a s t i c i t y and having a high coefficient of f r i c t i o n and the other
is formed from a r i g i d material, it is preferable t h a t the thermal
5 conductivity of the pressing part formed from a material having
e l a s t i c i t y is low and the thermal conductivity of the pressing part
composed of a rigidmaterial is high. Examples of such rigidmaterials
include metals such as s t a i n l e s s s t e e l . It is i n d u s t r i a l l y
advantageous t o carry out the press forming forproducingthebattery
10 separator of the present invention by the use of calender r o l l s
including a r o l l formed from a material having e l a s t i c i t y and a r o l l
formed from a r i g i d material, because the process is simple and a
battery separator in the form of a long sheet is e a s i l y obtained.
In order t o improve r e l e a s a b i l i t y from r o l l s , it is preferable t o
15 subject the s u r f a c e o f t h e r i g i d r o l l toTeflon (registeredtrademark)
processing.
[0069]
The press formingis preferablycarriedoutwhile heating, and
can be carried out by selectingtemperature conditions and pressure
20 conditionsunderwhichthefiberstoconstitutethemelt-blownnonwoven
fabricareatleastpartiallyfusion-bondedtoobtainanonwovenfabric
sheet having a desired pore diameter. It is enough just t o properly
select the pressure/temperature conditions in the press forming
processbasedonthe knowledgeofapersonskilledintheartaccording
to the material of the surface of the pressing means such as a roll,
and for example, the conditions can be selected so that the pressing
part coming into contact with at least one surface of the melt-blown
nonwovenfabricmayhaveatemperatureofabout8Oto230"~, preferably
5 about 150 to 200"~. When a pressing means in which a pressing part
comingintocontactwithonesurfaceofthemelt-blownnonwovenfabric
is formed from a metal and a pressing part coming into contact with
the other surface is formed from a rubber is used, the temperature
of the metal pressing part can be set to about 120 to 200°C, and the
10 temperature of the rubber pressing part can be set to about 90 to
170°C. When the pressing is carried out with rolls, the surface
temperatures of the rolls have only to be in this range.
[0070]
Inthe case where the temperature andthe pressure inthe press
15 fomingprocessaretoohigh,thefibersareexcessivelyfusion-bonded
to one another to make the pores of the nonwoven fabric clogged, so
that such a case is undesirable. Further, the resulting battery
separatorcannotbeusedinsomecasesbecausetheinternalresistance
is extremely increased. In the case where the temperature and the
20 pressure are too low, extremely fine pores are not sufficiently formed,
and the resulting separator has low extension resistance and poor
strength, sothat sucha case is undesirable. Themean fiber diameter
and the basis weight of the nonwoven fabric before the press forming
and those after the press forming are almost the same as each other.
The void r a t i o of the lithium ion battery separator of the present
invention is not less than 30%, preferably not less than 40%. Although
the thickness thereof is not s p e c i f i c a l l y r e s t r i c t e d , it is usually
10 t o 60 pm, preferably about 15 t o 45 pm. When the void r a t i o is
5 intheaboverange,thebatteryseparatorhaslowinternalresistance,
andthere i s n o fear of shortcircuitcausedbypassingofanelectrode
material, s o t h a t suchavoid r a t i o is preferable. When the thickness
is intheabove range, t h i s separatorcanbeusedalsoasasmall-sized
battery separator.
10
Examples
[0071]
The present invention is further described with reference t o
the following examples, but it should be construed that the present
15 invention is i n no way limited t o those examples.
Property values, etc. in the examples and the comparative
examples were measured by the following methods.
[0072]
(1) Mean fiber diameter (pm) , number of fusion-bonded f i b e r s
20 (fusion-bonded fibers/100 f i b e r s )
Themagnification of an electronmicroscope (HITACHI S-3500N)
was adjusted so that the number of f i b e r s of a melt-blown nonwoven
fabric observed on the screen might be in the range of 10 t o 20, and
a surfacemicrophotographwastakenbythe electronmicroscope. The
widths (diameters) of all the fibers having a length of 10 times or
more the diameter, observed on the screen, were measured. This
measurement was repeated so that the total number of the measured
fibers might become 100, and a mean of the results of the diameter
5 measurements was taken as amean fiber diameter. When the total number
of the measured fibers exceeded 100, a mean fiber diameter was
calculated from the following formula.
[0073]
Mean fiber diameter = mean of diameter measurement results x
10 100/total number of measured fibers
The ratio (Dd/Da) of the standard deviation (Dd) of the
measurement results to the mean fiber diameter (Da) was taken as a
fiber diameter CV value.
[0074]
15 Of the above 100 fibers, a fiber having a fiber diameter of
twice the mean fiber diameter was judged to be a fusion-bonded fiber,
andthenumberofsuchfiberswastakenasthenumberof fusion-bonded
fibers.
[0075]
20 When the total number of measured fibers exceeded 100, the number
of fusion-bonded fibers was calculated fromthe following formula.
[0076]
number offusion-bondedfibers=totalnumberof fusion-bonded
fibers x 100/total number of measured fibers
(2) Maximum pore diameter (pm) , minimum pore diameter (pm) and
mean pore diameter (pm) measured in the case of basis weight of 90
g/m2
A melt-blown nonwoven fabric having a basis weight of 90 g/m2
5 wasprepared, anda specimenobtainedfromanonwovenfabriclaminate
structurebecomingafiltermaterialforwatertreatmentinaconstant
temperature room having a temperature of 20+2"~an d a humidity of
65+2% defined by JIS 28703 (standard condition in the t e s t place)
wasimmersedinafluorine-basedinertliquid(manufacturedbySumitomo
10 3MLimited,tradename: F l u o r i n e r t ) . Usingacapillaryflowporometer
"Model: CFP-1200AE"manufacturedbyPorousMaterials, Inc., amaximum
pore diameter (p,) am inimumpore diameter (pm)a nd ameanpore diameter
(pm) in the case of a basis weight of 90 g/m2 (shown as "maximum pore
diameter", "minimum pore diameter" and " mean pore diameter",
15 respectively, in t h e t a b l e s ) were measured.
[0077]
(3) Inhibition r a t i o (%) and flow rate (l/min)
A melt-blown nonwoven fabric having a basis weight of 90 g/m2
wasprepared. Usingatestliquidobtainedbydispersingpolystyrene
20 latex p a r t i c l e s having a spherical p a r t i c l e diameter of 1.00 pm in
a 60vol%isopropylalcohol (IPA) aqueous s o l u t i o n i n a concentration
of 0.01% by weight, a f i l t r a t e having passed through the melt-blown
nonwoven fabric ( f i l t e r for liquids) under a pressure of 3.0 MPa in
a f i l t r a t i o n device (ADVANTEC TSU-90B) was obtained, and a
test liquidweremeasured. Then, an inhibition ratio was determined
by the following formula.
The concentrations of the test liquid and the filtrate were
5 each determined from a calibration curve having been obtained in
advance by measuring absorbance at a wavelength of 500 nm by the use
of a spectophotometer (SHIMADZU UV3100).
[0078]
Inhibition ratio = [ (Co-C1/)C o]x 100 (%)
10 Further, usingpolystyrene latex particles having a spherical
particle diameter of 3.00 pm and those having a spherical particle
diameter of 0.47 p, the inhibition ratios were determined by the
above method.
The flowrate (l/min) wasdeterminedbymeasuringtimenecessary
, 15 for a 60 vol% IPAaqueous solution of 500 cc topass through themelt-blown
nonwoven fabric (filter for liquids) under a pressure of 0.3 MPa in
the above filtration device.
I
[0079]
(4) Water pressure resistance (mrn Aqua)
20 10 Specimens (each 15x15 cm) obtained from a nonwoven fabric
laminate structure becoming a filter material for water treatment
in a constant temperature room having a temperature of 20+2"~an d
a humidity of 65+_2%d efined by JIS 28703 (standard condition in the
testplace) wereprepared. Usingawaterpressureresistancetesting
machine, pressures at which water leaked from the specimens were
measured in accordance with JIS L1092A, and a mean value thereof was
determined.
[0080]
(5) a crystal fraction of propylene-based polymer fiber
A wide angle X-ray diffraction apparatus (RIGAKU RINT2500,
attachment: rotary sample table, X-ray source: CuKa, output: 50 kV
300 mA, detector: scintillation counter) was used. A sample holder
was filled with a nonwoven fabric, and with rotating the sample, a
10 diffraction profile was measuredby a wide angle transmissionx-ray
diffraction method.
Fromthediffractionprofileresultobtainedbythemeasurement,
the peak intensity in the vicinity of 28=14" showing (110) plane of
a propylene-based polymer was regarded as a peak intensity of a crystal,
15 and the peak intensity in the vicinity of 28=15" was regarded as a
peak intensity of smectic crystal, and the a crystal fraction was
determined by the following formula. In the case where a peak in
the vicinity of 28=15" was not confirmed, it was judged that the
propylene-based polymer was constituted of only a crystal, and the
20 a crystal fraction was taken as 1.0.
[a crystal fraction] = [peak intensity of a crystal]/[peak
intensity of a crystal + peak intensity of smectic crystal]
[0081]
(6) Evaluation of flexibility
1 Evaluation of touch was carried out by 10 evaluators. The
evaluation results based on the following criteria are shown.
AA: Of the 10 evaluators, 10 evaluators felt that the specimen
was smooth to the touch.
5 BB: Of the 10 evaluators, 9 to 7 evaluators felt that the specimen
was smooth to the touch.
CC: Of the 10 evaluators, 6 to 3 evaluators felt that the specimen
was smooth to the touch.
DD: Of the 10 evaluators, 2 or less evaluators felt that the
10 specimen was smooth to the touch.
[0082]
Example 1

Using a spun bonded nonwoven fabric production apparatus (the
15 length of the collection surface in the direction perpendicular to
the machine direction: 500 mm) , a propylene homopolymer (PP-1, MFR:
60 9/10 min, melting point: 157"~)wa s melted at 240°C to prepare
a spun bonded nonwoven fabric having a basis weight of 7 g/m2 and
a fiber diameter of 14 pm.
20 [0083]

Apropylenehomopolymer (PP-2,MFR: 850g/lOmin,meltingpoint:
159"~)wa s fed to a die of a melt-blown nonwoven fabric production
apparatus, and onto one surface of the spun bonded nonwoven fabric
obtained by the above method, the homopolymer melt was discharged
from the die havingapreset temperature of 280°C through amelt-blowing
nozzle (diameter: 0.32 mm, distance between small holes of nozzle:
0.20 mm) a t a discharge r a t e of 0.52 g/min per nozzle single hole
5 while gushing out high-temperature high-velocity a i r (280°c, 600
m3/hr) from both sides of the nozzle. Thereafter, cooling and
dispersing were carried out by means of cooling a i r (temperature:
15O~, a i r flow rate: 6000 m3/hr) t o blow the f i b e r s against the spun
bonded nonwoven fabric a t DCD (distance between the surface of
10 spinneret and the collector) of 120 mm so that t h e b a s i s weight of
the resultingmelt-blown nonwoven f abricmight become 0.7 g/m2, whereby
alaminateofthespunbondednonwovenfabricandamelt-blownnonwoven
fabricwasobtained. Subsequently, onthemelt-blownnonwovenfabric
of the laminate structure, a spun bonded nonwoven fabric produced
15 under the sameconditionsasabovewaslaminated, toobtainanonwoven
fabric laminate structure having a t o t a l basis weight of 14.7 g/m2
(spunbondednonwoven fabric/melt-blownnonwoven fabric/spunbonded
nonwoven fabric = 7.0/0.7/7.0 g/m2).
[0084]
Properties o f t h e resultingnonwoven fabric laminate structure
were measured by the methods previously described. The r e s u l t s a r e
s e t forth in Table 1.
[0085]
Example 2
Anonwovenfabriclminatestructurehavingatotalbasisweight
of 14.5 g/m2 (spun bonded nonwoven fabric/melt-blown nonwoven
fabric/spun bonded nonwoven fabric = 7.0/0.5/7.0 g/m2) was obtained
in the same manner as in Example 1, except that a melt-blown nonwoven
5 fabric having a basis weight of 0.5 g/m2, which had been produced
by the use of amelt-blowingnozzle (diameter: O.32mm, distance between
small holes of nozzle: 1.59 mm) at a discharge rate of 1.27 g/min
per nozzle single hole, was used as a melt-blown nonwoven fabric to
be laminated on the spun bonded nonwoven fabric instead of the
10 melt-blown nonwoven fabric produced in Example 1.
[0086]
Propertiesoftheresultingnonwovenfabriclaminatestructure
were measured by the methods previously described. The results are
set forth in Table 1.
15 [0087]
Exam~le 3
A propylene homopolymer (MFR: 1500 g/10 min) was fed to a die
of a melt-blown nonwoven fabric production apparatus, and the
homopolymer melt was discharged from the die having a preset
temperature of 280"~th rough a melt-blowing nozzle (diameter: 0.2
mrn, distance between small holes of nozzle: 2.62 mrn) at a discharge
rate of 0.08 g/min per nozzle single hole while gushing out
high-temperature high-velocity air (280 "C, 600 m3/hr) from both sides
of the nozzle. Thereafter, cooling and dispersing were carried out
by means of cooling air (temperature: 1 5 "a~ir~ f low rate: 6000 m3/hr)
to blow the fibers against a collector at DCD (distance between the
surface of spinneret and the collector) of 120 mm, whereby a melt-blown
nonwoven fabric having a basis weight of 15 g/m2 was obtained.
5 [0088]
Subsequently, 6 of the resulting melt-blown nonwoven fabrics
weresuperposedupononeanothertoprepareafilterforliquidshaving
a basis weight of 90 g/m2. The results are set forth in Table 2.
[0089]
10 Example 4
Anonwovenfabriclaminatestructurehavingatotalbasisweight
of 13.0 g/m2 (spun bonded nonwoven fabric/melt-blown nonwoven
fabric/spun bonded nonwoven fabric = 6.15/0.7/6.15 g/m2) was obtained
in the same manner as in Example 1, except that a melt-blown nonwoven
15 fabric having a basis weight of 0.7 g/m2, which had been produced
by theuse of amelt-blowingnozzle (diameter: O.32mmI distance between
small holes of nozzle: 1.02 mm) at a discharge rate of 1.26 g/min
per nozzle single hole, was used as a melt-blown nonwoven fabric to
be laminated on the spun bonded nonwoven fabric instead of the
20 melt-blown nonwoven fabric produced in Example 1, the flow rate of
the high-temperature high-velocity air was changed to 1400 m3/hr,
and the DCD was changed to 150 mm.
[0090]
Propertiesoftheresultingnonwovenfabriclaminate structure
were measured by the methods previously described. The results are
set forth in Table 1.
[0091]
5 Anonwovenfabriclaminatestructurehavingatotalbasisweight
of 13.0 g/m2 (spun bonded nonwoven f abric/melt-blown nonwoven
fabric/spun bonded nonwoven fabric = 6.15/0.7/6.15 g/m2) was obtained
in the same manner as in Example 4, except that a melt-blown nonwoven
fabric having a basis weight of 0.7 g/m2, which had been produced
10 bytheuseofamelt-blowingnozzle (diameter:O.32mm,distancebetween
small holes of nozzle: 0.33 mm) at a discharge rate of 0.63 g/min
per nozzle single hole, was used as a melt-blown nonwoven fabric to
be laminated on the spun bonded nonwoven fabric, and the flow rate
of the high-temperature high-velocity air was changed to 1500 m3/hr.
15 [0092]
Propertiesoftheresultingnonwovenfabriclaminatestructure
were measured by the methods previously described. The results are
set forth in Table 1.
[0093]
20 Example 6
Anonwovenfabriclaminatestructurehavingatotalbasisweight
of 13.0 g/m2 (spun bonded nonwoven fabric/melt-blown nonwoven
f abric/spun bonded nonwoven fabric = 6.15/0.7/6.15 g/m2) was obtained
in the same manner as in Example 4, except that a melt-blown nonwoven
fabric having a basis weight of 0.7 g/m2, which had been produced
by the use of amelt-blowingnozzle (diameter: 0.32mm1 distance between
small holes of nozzle: 0.20 mm) at a discharge rate of 0.51 g/min
per nozzle single hole, was used as a melt-blown nonwoven fabric to
5 be laminated on the spun bonded nonwoven fabric, and the flow rate
of the high-temperature high-velocity air was changed to 700 m3/hr.
[0094]
Properties ofthe resultingnonwoven fabric laminate structure
were measured by the methods previously described. The results are
10 set forth in Table 1.
1 [0095]
I Example 7
I
Anonwovenfabriclaminatestructurehavingatotalbasisweight I of 13.0 g/m2 (spun bonded nonwoven fabric/melt-blown nonwoven
15 fabric/spun bonded nonwoven fabric = 6.15/0.7/6.15 g/m2) was obtained
in the same manner as in Example 4, except that a melt-blown nonwoven
fabric having a basis weight of 0.7 g/m2, which had been produced
bytheuseofamelt-blowingnozzle (diameter: 0.4mrn, distancebetween
small holes of nozzle: 0.25 mm) at a discharge rate of 0.51 g/min
20 per nozzle single hole, was used as a melt-blown nonwoven fabric to
be laminated on the spun bonded nonwoven fabric, and the flow rate
of the high-temperature high-velocity air was changed to 1200 m3/hr.
[0096]
Propertiesoftheresultingnonwovenfabriclaminatestructure
were measured by the methods previously described. The r e s u l t s are
s e t forth in Table 1.
[0097]
Comparative Example 1
5 Anonwovenfabriclaminatestructurehavingatotalbasisweight
of 15.0 g/m2 (spun bonded nonwoven fabric/melt-blown nonwoven
f abric/spun bonded nonwoven fabric = 7.0/1.0/7.0 g/m2) was obtained
in the same manner as in Example 1, except that cooling a i r was not
used in the production of amelt-blownnonwoven fabric, and amelt-blown
10 nonwoven fabric having a basis weight of 1.0 g/m2 was used.
[0098]
Propertiesoftheresultingnonwovenfabriclaminatestructure
were measured by the methods previously described. The r e s u l t s a r e
set forth in Table 1.
15 [0099]
Comparative Example 2
A melt-blown nonwoven fabric having a basis weight of 15 g/m2
was obtained in the same manner as in Example 3, except that cooling
a i r was not used in the production of a melt-blown nonwoven fabric.
20 [ O l O O ]
Subsequently, 6 of the resulting melt-blown nonwoven fabrics
weresuperposedupononeanothertoprepareafilterforliquidshaving
a basis weight of 90 g/m2. The r e s u l t s a r e s e t forth in Table 2.
Comparative Example 3
A melt-blown nonwoven fabric having a basis weight of 15 g/m2
was obtained in the same manner as in Comparative Example 2, except
that a melt-blowing nozzle (diameter: 0.2 mm, distance between small
5 holes of nozzle: 0.68 mm) was used.
[0102]
Subsequently, 6 of the resulting melt-blown nonwoven fabrics
weresuperposedupononeanothertoprepareafilterforliquidshaving
a basis weight of 90 g/m2. The r e s u l t s a r e s e t f o r t h in Table 2.
10 [0103]
Comparative Example 4
A melt-blown nonwoven fabric having a basis weight of 15 g/m2
was obtained in the same manner as in Comparative Example 2, except
that a melt-blowing nozzle (diameter: 0.2 mm, distance between small
15 holes of nozzle: 2.62 mm) was used.
[0104]
Subsequently, 6 of t h e r e s u l t i n g melt-blown nonwoven fabrics
weresuperposedupononeanothertoprepareafilterforliquidshaving
a basis weight of 90 g/m2. The r e s u l t s a r e s e t f o r t h in Table 2.
20 [0105]
Comparative Example 5
Anonwovenfabriclaminatestructurehavingatotalbasisweight
of 1 4 . 7 g/m2 (spun bonded nonwoven fabric/melt-blown nonwoven
fabric/spun bonded nonwoven fabric = 7.0/0.7/7.0 g/m2) was obtained
in the same manner as in Comparative Example 1, except that a melt-blown
nonwoven fabric having a basis weight of 0.7 g/m2 was used.
[0106]
Properties ofthe resultingnonwoven fabriclaminate structure
5 were measuredby the methods previously described. The results are
set forth in Table 1.
[0107]
Comparative Example 6
Anonwovenfabriclaminatestructurehavingatotalbasisweight
10 of 14.7 g/m2 (spun bonded nonwoven fabric/melt-blown nonwoven
fabric/spun bonded nonwoven fabric = 7.0/0.7/7.0 g/m2) was obtained
in the same manner as in Example 1, except that in the production
of a melt-blown nonwoven fabric, air having a temperature of 5 0 " ~
and an air flow rate of 6000 m3/hr was used instead of cooling air,
15 and the DCD was changed to 150 mm.
[0108]
Properties ofthe resultingnonwovenfabriclaminate structure
were measured by the methods previously described. The results are
set forth in Table 1.
20 [0109]
Comparative Example 7
Anonwoven fabric laminate structure having a total basis weight
of 13.0 g/m2 (spun bonded nonwoven fabric/melt-blown nonwoven
fabric/spun bonded nonwoven fabric = 6.15/0.7/6.15 g/m2) was obtained
in the same manner as in Example 5, except that in the production
of a melt-blown nonwoven fabric, cooling air was not used, and the
flow rate of the high-temperature high-velocity air was changed to
1000 m3/hr.
5 [OllO]
Properties oftheresultingnonwovenfabriclaminate structure
were measured by the methods previously described. The results are
set forth in Table 1.
[Olll]
10 [Table 11
Table 1
Apparatus Distance
between small
holes -h-o les d (m)
Nozzle diameter 0
(m)
Melt-blown (g/min/hole)
nonwoven fabric (kg/hr/m)
discharge rate
Nonwoven fabric Total basis
constitution weight
(g/m2)
MB basis weight
( 9/m2
Form
Cooling air Temperature
(OC)
Air flow rate
(m3/hr)
High-temperature Temperature
high-velocity air ( "c) -
Flow rate
(m3/hr)
DCD (m)
Fiber diameter Mean (p)
CV value (%)
Number of fusion-bonded fibers
(fusion-bonded fibers/100 fibers)
Crystalline a crystal
property fraction
i i
Ex. 1 1 Ex. 2 1 Ex. 4 Ex. 5 1 Ex. 6 Ex. 7
I I I
I 1 11 1I I
0.20 1 1.59 1 / 0.33 0.20 0.25
i I 1 I 1 I 1 - j I
j i ii i
I
0.32 1 0.32 1 0.32 1 0.32 1 0.32 0.4
I i i I
I I
0.52 1 1.27 1.26 1 0.63 1 0.51 1 0.51
I i I i
61 / 43 1 60 I 60 j 60 1 48 1
I I
j I j
14.1 / 14.5 13.0 ; 13.0 1 13.0 1 13.0
- j 1, ij - iI i
I i 0.70 i
0-50 1
0.70 0.70 1 0.70 0.70
1 j
laminate i1 laminate Ii laminate I laminate 1 laminate I laminate
I
Water pressure resistance
(rnrnAgua)
Flexibility
Filterperformance Inhibition
ratio (%)
I
I 1 I
185 i 193 / 192 198 / 170 1 168 I I
I
BB BB BB BB BB BB
1
- 1 - j - - - -
1 i i
15 j 15 1 15 1 15 1 15 1 15
i ! I , I
I 1 1i iI I 6000 6000 6000 1 6000 j 6000 j 6000
1 1 1 1 I 1 i 1 i
280 i 280 i 280 1 280 j 280 280 1 1
i I i
600 600 1400 / 1500 1 700 / 1200
j i
I I I i
120 / 120 / 150 / 150 / 150 1 150
1.5 / 1.2 I 1.9 / 1.9 1 1.9 / 2.0
I i I 33 1 30 I 53 42 55 58
1 I 1 i
1 0 / 5 j 5 ~ 3 ~ 1 0 ~ 1 1 j
I i I 1 I
0.42 1 0.47 I 0.42 0.42 1 0.42 0.42
Table 1 (continued)
[Table 21
Distance Apparatus between small
-- holes d (mm-)-
Nozzle diameter 0 (m)
Melt-blown -- (g/min/hole)
nonwoven fabric (kg/hr/m)
discharge rate
Nonwoven fabric Total basis weight (g/m2)
constitution MB basis weight (g/m2)
Form
Cooling air Temperature ( OC)
Air flow rate (m3/hr)
High-temperature -T emperature ( 'C )
high-velocity air Flow rate (m3/hr)
DCD (mm)
Fiber diameter Mean (PI)
CV value (%)
Number of fusion-bonded fibers (fusion-bonded
fibers/100 fibers)
Crystalline a crystal fraction
property
Water pressure resistance (mAqua)
Flexibility
Filterperfomnce Inhibition ratio (%)
I
C-. f COT. : comp. / Comp. i I I
E x . 1 1 E x . 5 j E x . 6 1 E x . 7
1 j i !
0.20 0.32 j 0.20 1 0.33
I i ___i__
0.32 ii 0.32 0.32 jI 0.32
0.52 1 0.52 ' 0.52 I 0.63
I
i
61 / 61 1 61 1 60 1
i
15.0 14.7 I 14.7 13.0
i 4-
i *------ 1.00 , 0.70 i 0.70 / 0.70
laminate / laminate / laminate / laminate
- ii - 1 5 0 1 -
I - 1 - / 6000 1 -
280 1 280 280 1 280
I j j-
600 1 600 600 1 1000
I !
120 120 1 150 i 150
I I
3.0 / 3.0 1 2.8 2.2
84 84 1 112 1 63
I 1 1
23 23 29 1 17
! a i I i i
1.00 / 1.00 / 1.00 i 1.00
1 1 I
180 / 135 / 120 / 172
I I i
CC CC I CC j CC
- 1 - f - / -
Table 2
Apparatus Distance between
small holes d (m)
Nozzle diameter 0
(mm)
Melt-blown (g/min/hole)
nonwoven fabric (kg/hr/m)
discharge rate
Nonwoven fabric Totalbasis weight
constitution (g/m2)
MB basis weight
(g/m2)
Form
Cooling air --T emperature ( OC)
Air flow rate
(m3/hr)
High-temperature -Te mperature ( OC)
high-velocity air Flow rate (m3/hr)
DCD (m)
Fiber diameter Mean (pm)
CV value (%)
Number of fusion-bonded fibers
(fusion-bonded fibers/100 fibers)
Crystalline acrystal fraction
property
Water pressure resistance (nanAqua)
Filter Inhibition ratio
performance (%
1 i
Ex. 3 1 Comp. Ex. 2 1 Comp. Ex. 3 1 Comp. Ex. 4
j I
I ! I
2.62 1 0.20 1 0.68 2.62
1 I
i , -
0.2 / 0.32 1 0.2 0.2
I I
1 !
0.08 1 0.08 / 0.08 / 0.08
2 I 9 i 6 / 2
j j
9 0
I j
1I I j 90
- . I ---- I
I 1
90.00 1 90.00 i 90.00 90.00
i 1 j
1 I
I
single 1 single 1 single 1 single
j 1 !
layer / layer j layer i layer
15- j - 1 - j -
j
6000 1 - - 1 -
/ j
I I
I
28-0 I 280 I 280 280
i
600 1I 600 1 600 1 600
1 120 120 / 120 / 120
i
0.5 1 1.8 :j 0.8 1i 0.6
i
50 j 8 0 / 120 i 60
/ I 8 i1 21 1I 33 i1j 16
i
0.44 j 0.95 1.00 / 1.00 I j
- j - - -
I
99.5 f 18.0 1 64.0 1 85.0
/ f 1
I j
Industrial Applicability
[0113]
Thepresentinventioncanprovideaprocessforstablyproducing
a melt-blown nonwoven fabric comprising t h i n f i b e r s and having
5 extremely few thick f i b e r s formed by fusion bonding of f i b e r s t o one
another, a production apparatus for the melt-blown nonwoven fabric,
and the melt-blown nonwoven fabric.
[0114]
I n t h e melt-blown nonwoven fabric of the present invention,
10 cooling of the spun molten f i b e r s is s u f f i c i e n t l y effected, and
therefore, bundle-like f i b e r s formed by fusion bonding or twisting
of plural f i b e r s a r e extremely few. On t h i s account, the melt-blown
nonwoven fabric has features t h a t voids in the nonwoven f a b r i c a r e
remarkablyuniformandtheefficiencyofcollectionof f i n e p a r t i c l e s
15 is extremely high, so that the melt-blown nonwoven fabric can be
favorably used as a f i l t e r .
[0115]
Further, since the melt-blown nonwoven fabric of the present
invention has extremely high water resistance, it can exhibit the
20 same performance as t h a t of conventional nonwoven fabrics even i f
the basis weight is lower than that of the conventional nonwoven fabrics.
In addition, themelt-blown nonwoven fabric o f t h e present invention
has excellent f l e x i b i l i t y . On t h i s account, themelt-blownnonwoven
f a b r i c i s favorablyusedforsanitarymaterials, suchaspaperdiapers
and sanitary napkins, and moreover, because of flexibility and good
feeling, itcanbewidelyusedformedicalpurposes, operating gowns,
packaging cloths, bedclothes such as bed sheets and pillowcases,
carpets, base fabrics for artificial leathers, industrialmaterials,
5 civil engineering materials, agricultural and gardening materials,
materials relevant to living, etc.
Reference Signs List
[0116]
10 2: production apparatus
4: melt-blowing die
6: mesh conveyer
8: suction box
10: fiber
12: die nose
14: small hole
16: nozzle
18: resin passage
20a, 20b: air passage
31: slit
32: attachment

CLAIMS
1. A melt-blown nonwoven fabric comprising polyolefin
fibers and having:
(i) a mean fiber diameter of not more than 2.0 pm,
(ii) a fiber diameter distribution CV value of not more than
60%, and
(iii) 15 or less fusion-bonded fibers based on 100 fibers.
2. Amelt-blownnonwovenfabriccomprisingpropylene-based
10 polymer fibers and having:
(i) a mean fiber diameter of not more than 2.0 pf
(ii) a fiber diameter distribution CV value of not more than
60%, and
(iv) an a crystal fraction of less than 0.9.
3. A filter containing a layer composed of the melt-blown
nonwoven fabric as claimedinclaimlor2 andhavinga 0.5rnmdiameter
fine particle collection efficiency of not less than 90% in the case
of a basis weight of 90 g/cm2.
4. A nonwoven fabric laminate structure having the
melt-blown nonwoven fabric as claimed in claim 1 or 2 on at least
onesurfaceofwhichaspunbondednonwovenfabricislaminated,wherein
a ratio of a basis weight (g/m2) of the melt-blown nonwoven fabric
layer to a basis weight (g/m2) of the whole laminate is not more than
0.05.
5. Sanitary goods comprising the nonwoven fabric laminate
5 structure as claimed in claim 4.
6. A battery separator containing a layer composed of the
melt-blown nonwoven fabric as claimed in claim 1 or 2.
10 7. A production process for a melt-blown nonwoven fabric,
comprisingspinningoutamoltenthermoplasticresinthroughanozzle
havingalargenumberof smallholeslinedup, saidmoltenresinhaving
been forcedly fed to a melt-blowing die, and accumulating fibers on
a moving collection plate, said fibers being obtained by drawing and
15 thinningthemoltenresinbyhigh-temperaturehigh-velocityairgushed
out from slits provided so as to interpose a line of the small holes
therebetween, wherein:
a cooling fluid of not higher than 3 0 "i~s fed from both side
surfaces of outlets of the slits from which the high-temperature
20 high-velocityairis gushedout, to cool the spun thermoplastic resin
fibers.
8. The production process for amelt-blown nonwoven fabric
as claimed in claim 7, wherein the cooling fluid is cooling air.
9. Aproductionapparatus foramelt-blownnonwovenfabric,
performing spinning of a molten thermoplastic resin through a nozzle
havingalargenumberofsmallholeslinedup, saidmoltenresinhaving
5 been forcedly fed t o a melt-blowing die, and accumulating of f i b e r s
on a moving collection plate, s a i d f i b e r s being obtained by drawing
andthinningthe molten resin by high-temperature high-velocity a i r
gushed out from slits provided so as t o interpose a l i n e of the small
holes therebetween, wherein:
anattachment t o introduce a cooling f l u i d f o r coolingthe spun
thermoplastic resin f i b e r s has been removably mounted on the t i p of
the melt-blowing die.
10. Theproductionapparatusforamelt-blownnonwovenfabric
15 as claimed in claim 9, wherein the attachment has been mounted on
the t i p of the melt-blowing die without any space.
Dated this 0 1.07.20 13
[NEHA SRIVASTAVA]
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT[SJ