DESCRIPTION
TITLE OF INVENTION: FIBER, NONWOVEN FABRIC AND USES THEREOF
5 TECHNICAL FIELD
[0001]
The present invention relates to fibers which suppress
the growth of harmful bacteria and reduce the occurrence of
skin rashes and which are suitably used in products such as
10 top sheets of hygiene materials such as disposable diapers and
sanitaryitems, and to nonwoven fabrics including such fibers.
BACKGROUND ART
[0002]
15 Nonwoven fabrics obtained from olefin polymers,
typically polypropylene, have excellent breathability,
flexibility and lightweight properties and have been used
I
widely in various applications including hygiene materials.
I
I
i Thus, the nonwoven fabrics require specific properties in
i
20 accordance with the applications, and demands have been placed
on the improvements of such properties.
[0003]
For example, nonwoven fabrics used in hygiene materials
such as disposable diapers require skin-friendly flexibility,
quickurine absorption, breathabilityto release humidity, and
antimicrobial properties to prevent skin rashes and foul odor
due to bacteria and the like. In particular, skin rashes are
very stressful to users. Thus, various remedies have been
5 studied to suppress the growth of bacteria responsible for
rashes as well as the occurrence of foul odor. In particular,
it has been recently found that because skin is weakly acidic,
rendering the skin environment mildly acidic promotes the
growth of skin-friendlybacteria and can consequently suppress
10 the growth of bacteria harmful to the skin, thereby reducing
the occurrence of bacterial skin rashes.
[0004]
For example, JP-A-2003-516778 (Patent Literature 1)
discloses an approach inwhich a nonwoven fabric is impregnated
15 with citric acid or sodium citrate as a pH control agent to
maintain a pH environment similar to the pH of skin in contact
with the nonwoven fabric. Because citric acid described in
Patent Literature 1 is water soluble, however, the pH control
agent such as citric acid is eluted and migrates toward an
20 absorbent upon contact with urine. Thus, maintaining the pH
is difficult. Further, for example, JP-A-2004-176225 (Patent
Literature 2) discloses an approach which utilizes a deodorant
fiber having a fiber treatment agent attached to the fiber,
the fiber treatment agent including an amphoteric betaine
compound, an adduct of a nonionic surfactant with an alkylene
oxide, and/or an anionic surfactant such as a carboxylate salt.
Because the fiber treatment agent in Patent Literature 2 is
attached onto the fiber by application, a contact with urine
5 results in the fiber treatment agent being partially eluted
and migrating toward an absorbent. Thus, similarly to Patent
Literature 1, this approach is not satisfactory in terms of
the durability of effects.
[0005]
10 Othervariousapproacheshavebeenproposed. Forexample,
JP-A-2005-530857 (Patent Literature 3) proposes a method
utilizing an antimicrobial composition comprising an
antimicrobial active and an anionic surfactant, and
JP-A-2002-505918 (Patent Literature 4) proposes an approach
15 utilizing a skin care composition comprising a proton donating
active component. However, any of these remedies have a
problemin that effects aredecreasedwithtime. Whileamethod
utilizing an antimicrobial composition can reduce the
bacterial growth temporarily by antimicrobial effects, the
20 antimicrobial agents suppress not only the growth of harmful
bacteria but also the growth of beneficial bacteria, resulting
in the proliferation of harmful bacteria. Thus, the
suppressive effects for diaper skin rashes in the art have been
unsatisfactory and are to be improved.
CITATION LIST
PATENT LITERATURE
[0006]
5 P a t e n t L i t e r a t u r e 1: JP-A-2003-516778
P a t e n t L i t e r a t u r e 2: JP-A-2004-176225
P a t e n t L i t e r a t u r e 3: JP-A-2005-530857
P a t e n t L i t e r a t u r e 4: JP-A-2002-505918
10 SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0007]
The p r e s e n t i n v e n t o r s c a r r i e d out s t u d i e s i n o r d e r t o
developfiberswhichcansuppressthegrowthofharmfulbacteria
15 and can c o n t i n u o u s l y s u p p r e s s t h e occurrence of s k i n r a s h e s
and which a r e s u i t a b l y used i n t o p s h e e t s o r second s h e e t s of
h y g i e n e m a t e r i a l s s u c h 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 i t e m s ,
a s well a s t o develop nonwoven f a b r i c s i n c l u d i n g such f i b e r s .
As a r e s u l t , t h e p r e s e n t i n v e n t o r s have found t h a t t h e above
20 o b j e c t can be accomplished with f i b e r s o b t a i n e d from an o l e f i n
polymer composition i n c l u d i n g an a c i d - f o r m a n i o n i c s u r f a c t a n t ,
and with nonwoven f a b r i c s i n c l u d i n g such f i b e r s .
SOLUTION TO PROBLEM
The present invention provides a fiber which includes an
olefin polymer composition including 100 parts by weight of
an olefin polymer and 0.1 to 30 parts by weight of an acid-form
5 anionic surfactant, the acid-form anionic surfactant having
been melt kneaded in the fiber.
ADVANTAGEOUS EFFECTS OF INVENTION
[0009]
10 Fibers of the invention and nonwoven fabrics including
the fibers suppress the growth of harmful bacteria when used
in hygiene materials such as diapers, and exhibit high
durability of suppressive effects for skin rashes.
15 DESCRIPTION OF EMBODIMENTS
[OOlO]
(Olef in polymers)
Olefin polymers which form the inventive fibers and
nonwoven fabrics including the fibers are homopolymers or
20 copolymers ofa-olefins such as ethylene, propylene, 1-butene,
1-hexene, 4-methyl-1-pentene and 1-octene. Specific examples
include ethylene polymers, for example, ethylene homopolymers
or ethylene/a-olefin copolymers such as high-pressure
low-density polyethylenes, linear low-density polyethylenes
(LLDPE), high-density polyethylenes, ethylene/propylene
random copolymers and ethylene/l-butene random copolymers;
propylene polymers such as propylene homopolymers
(polypropylenes), propylene/ethylene random copolymers,
5 propylene/ethylene/l-butene random copolymers (random
polypropylenes), propylene block copolymers and
propylene/l-butene random copolymers; 1-butene polymers such
as 1-butene homopolymers, 1-butene/ethylene copolymers and
1-butene/propylene copolymers; and poly(4-methyl-1-pentene).
10 [OOll]
Of these olefin polymers, propylene polymers are
preferable because of excellent spinning stability during
forming and good workability of nonwoven fabrics as well as
because the obtainable nonwoven fabrics exhibit excellent
15 breathability, flexibility, lightweight properties and heat
resistance.
The olefin polymers in the invention may be blended with
common additives or polymers other than the olefin polymers
20 as required while still achieving the object of the invention.
Exemplary additives include hydrophilicity enhancing or
suppressing auxiliaries, antioxidants, weathering stabilizers,
light stabilizers, antiblocking agents, lubricants,
nucleating agents, pigments, softeners, water repellants,
I fillers and antimicrobial agents.
I I
(Propylene polymers)
A preferred propylene polymer in the present invention
5 is a propylene homopolymer or a copolymer of propylene and a
small amount of one, or two or more kinds of a-olefins having
2 or more carbon atoms (except the C3 olefin), and preferably
2 to 8 carbon atoms (except the C3 olefin) such as ethylene,
1-butene, 1-pentene, 1-hexene, 1-octene and
10 4-methyl-1-pentene, and usually has a melting point (Tm) of
notle~sthan125~an~d,p referablyinthe range of130t0165~~.
[0014]
The melt flow rate (MFR: ASTM D-1238, 230°C, 2160 g load)
of the propylene polymer in the invention is not particularly
15 limited as long as melt spinning is feasible. The melt flow
rate, however, is usually in the range of 1 to 1000 g/10 min,
preferably 5 to 500 g/10 min, and more preferably 10 to 100
g/10 min.
[0015]
2 0 Ofthe propylene polymers in the invention, particularly
preferable are propylene/a-olefin random copolymers of
propylene and a small amount of one, or two or more kinds of
a-olefins having 2 or more carbon atoms, and preferably 2 to
8 carbonatoms suchas ethylene, 1-butene, 1-pentene, 1-hexene,
1-octene and 4-methyl-1-pentene, with a melting p o i n t (Tm) i n
t h e range of 125 t o 155OC. and p r e f e r a b l y 130 t o 147°C. The
use of such copolymers r e s u l t s i n nonwoven f a b r i c s e x h i b i t i n g
e x c e l l e n t f l e x i b i l i t y and i n i t i a l h y d r o p h i l i c i t y .
5 [0016]
I n t h e p r o p y l e n e / a - o l e f i n randomcopolymers, t h e c o n t e n t
o f a - o l e f i n s is n o t p a r t i c u l a r l y l i m i t e d as long a s t h e m e l t i n g
p o i n t (Tm) is i n t h e above range, but is u s u a l l y i n t h e range
of 1 t o 10 mol%, and more p r e f e r a b l y 1 t o 5 mol%.
10 [0017]
(Acid-form a n i o n i c s u r f a c t a n t s )
An acid-form a n i o n i c s u r f a c t a n t i n t h e p r e s e n t i n v e n t i o n
i s a n a n i o n i c s u r f a c t a n t which c a n a c t as a n a c i d i n t h e p r e s e n c e
of water or moisture. In p a r t i c u l a r , a n acid-form a n i o n i c
15 s u r f a c t a n t having weak a c i d i t y i s p r e f e r a b l e a s t h e acid-form
anionicsurfactantbecauseithasabufferingcapacitytoreduce
a change i n pH. In d e t a i l , f a t t y a c i d s andacid-formphosphate
e s t e r s u r f a c t a n t s a r e p r e f e r a b l e . As long a s t h e s u r f a c t a n t s
a r e of acid-form, i n c o m p l e t e l y n e u t r a l i z e d s a l t s , f o r example,
20 p a r t i a l l y n e u t r a l i z e d s a l t s such a s monoalkyl phosphate e s t e r
s a l t s may b e u s e d .
[0018]
The acid-form a n i o n i c s u r f a c t a n t s i n t h e i n v e n t i o n a r e
a n i o n i c s u r f a c t a n t s having a n a l i p h a t i c hydrocarbon group i n
which a hydrophobic group u s u a l l y h a s n o t less than 8 carbon
atoms, and i n o r d e r t o achieve b e t t e r m e l t kneading p r o p e r t i e s
and s t a b l e o p e r a t i o n p r o p e r t i e s during e x t r u s i o n , p r e f e r a b l y
not less than 9 carbon atoms, more p r e f e r a b l y not l e s s than
5 12 carbon atoms, and s t i l l more p r e f e r a b l y not less than 13
carbon atoms, and p a r t i c u l a r l y p r e f e r a b l y a n i o n i c s u r f a c t a n t s
having an a l i p h a t i c hydrocarbon group with 18 t o 28 carbon
atoms; o r p r e f e r a b l y f a t t y a c i d s having not l e s s than 9 carbon
atoms, p r e f e r a b l y n o t l e s s t h a n 1 2 carbonatoms,morepreferably
10 not l e s s than 13 carbon atoms, and p a r t i c u l a r l y p r e f e r a b l y 18
t o 28 carbon atoms; o r phosphate e s t e r s u r f a c t a n t s i n which
ahydrophobicgrouppreferablyhasnotlessthan 9 carbonatoms,
more p r e f e r a b l y not less than 12 carbon atoms, s t i l l more
p r e f e r a b l y not l e s s than 13 carbon atoms, and p a r t i c u l a r l y
15 p r e f e r a b l y 18 t o 28 carbon atoms. Examples of t h e phosphate
e s t e r s u r f a c t a n t s i n c l u d e a l k y l phosphate e s t e r s which a r e
esters formed between a l i p h a t i c a l c o h o l s and phosphoric a c i d ;
a l k y l e t h e r phosphate e s t e r s which a r e e s t e r s formed between
adducts of a l i p h a t i c a l c o h o l s with a l k y l e n e oxides and
20 phosphoric a c i d ; and a l k y l p h e n y l e t h e r phosphate e s t e r s which
a r e e s t e r s formed between adducts of aromatic a l c o h o l s with
a l k y l e n e oxides and phosphoric a c i d .
[0019]
Amixture o f t h e a c i d - f o r m a n i o n i c s u r f a c t a n t s m a y b e u s e d
in the invention. For example, fatty acids or acid-form
phosphate ester surfactants with 18 to 28 carbon atoms may be
alkyl phosphate esters which are esters formed between
aliphatic alcohols having 18 to 28 carbon atoms and phosphoric
5 acid; alkyl ether phosphate esters which are esters formed
between adducts of aliphatic alcohols having 18 to 28 carbon
atoms with alkylene oxides and phosphoric acid; alkyl phenyl
ether phosphate esters which are esters formed between adducts
of aromatic alcohols having18 to 28 carbon atoms with alkylene
10 oxides and phosphoric acid; or mixtures thereof. Fatty acids
with 9 or more carbon atoms, acid-form phosphate ester
surfactants with 9 or more carbon atoms, or mixtures thereof
are preferable because better melt kneading properties can be
obtained as well as because the acid-form anionic surfactants
15 are suppressed from being eluted from nonwoven fabrics and the
durability of effects is improved.
[0020]
Specific examples of the fatty acids in the invention
include saturated fatty acids such as myristic acid, palmitic
20 acid, stearic acid and montanic acid, and unsaturated fatty
acids such as oleic acid, linolenic acid and nervonic acid.
[0021]
Specific examples of the acid-form phosphate ester
surfactants in the invention include alkyl phosphate esters
such as monostearylphosphate ester, distearylphosphate ester,
monobehenyl phosphate ester, dibehenyl phosphate ester,
monocetylphosphate ester, dicetylphosphate ester, monolauryl
phosphate ester, dilaurylphosphate ester, monooctylphosphate
5 e s t e r a n d d i o c t y l p h o s p h a t e e s t e r ; a l k y l e t h e r p h o s p h a t e e s t e r s
such as mono (polyoxyethylene stearyl ether) phosphate ester,
di(polyoxyethy1ene stearyl ether) phosphate ester,
mono(polyoxyethylene lauryl ether) phosphate ester and
di(polyoxyethy1ene lauryl ether) phosphate ester; and
10 alkylphenyl ether phosphate esters such as
mono(polyoxyethylene stearylphenyl ether) phosphate ester,
di(polyoxyethy1ene stearylphenyl ether) phosphate ester,
mono(polyoxyethylene laurylphenyl ether) phosphate ester and
di(polyoxyethy1ene laurylphenyl ether) phosphate ester.
15 [0022]
Of these acid-form anionic surfactants, the acid-form
phosphate ester surfactants are particularly preferable.
[0023]
(Nonionic surfactants)
20 Various known nonionic surfactants may be used as the
nonionic surfactants in the invention without limitation as
long as the addition of such nonionic surfactants results in
fibers exhibiting hydrophilicity on the surface. Specific
examples of the nonionic surfactants include fatty acid
glycerides, alkoxylated alkylphenols, polyoxyalkylene fatty
acid esters, alkylpolyoxyethylene alcohols, fatty acid amides,
polyoxyalkylene sorbitan fattyacidesters, sucrose fattyacid
esters, sorbitan fatty acid esters, fatty acid alkanolamides,
5 polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl
ethers, alkyl polyglucosides, fatty acid diethanolamides and
alkyl monoglyceryl ethers.
[0024]
(Olefin polymer compositions)
10 An olefin polymer composition in the invention includes
100 parts by weight of the olefin polymer and 0.1 to 30 parts
by weight, preferably 1 to 15 parts by weight, and more
preferably 1.5 to 10 parts by weight of the acid-form anionic
surfactant.
15 [0025]
If the amount of the acid-form anionic surfactantis less
than O.lpartbyweight, the environment around the fibers will
not be adequately rendered weakly acidic. As a result,
nonwoven fabrics including such fibers may fail to reduce the
20 occurrence of rashes when used in hygiene materials such as
sanitary items and diapers. The upper limit of the amount is
not particularly limited. However, any amount exceeding 30
parts by weight results in the saturation of the effects of
rendering the environment around the fibers weakly acidic as
well a s i n an i n c r e a s e i n t h e amount of t h e acid-form a n i o n i c
s u r f a c t a n t exuding t o t h e s u r f a c e of t h e o b t a i n a b l e f i b e r s and
nonwoven f a b r i c s i n c l u d i n g t h e f i b e r s , t h u s d e t e r i o r a t i n g
forming p r o c e s s a b i l i t y .
5 [0026]
In a d d i t i o n t o t h e acid-form a n i o n i c s u r f a c t a n t , t h e
o l e f i n polymer c o m p o s i t i o n o f t h e i n v e n t i o n may c o n t a i n t h e
nonionic s u r f a c t a n t i n an amount of 0 . 1 t o 30 p a r t s by weight,
and p r e f e r a b l y 0.5 t o 15 p a r t s by weight with r e s p e c t t o 100
10 p a r t s by weight of t h e o l e f i n polymer. This c o n f i g u r a t i o n can
improve t h e h y d r o p h i l i c i t y of t h e o b t a i n a b l e f i b e r s and can
prevent a r a p i d change i n pH due t o t h e acid-form a n i o n i c
s u r f a c t a n t .
[0027]
In t h e p r e p a r a t i o n of t h e i n v e n t i v e o l e f i n polymer
composition, masterbatch p e l l e t s may be formed which c o n t a i n
t h e acid-form a n i o n i c s u r f a c t a n t a t a h i g h c o n c e n t r a t i o n
exceeding5wt%, f o r example, 1 0 t o 4 O w t % . T h i s m a s t e r b a t c h i n g
advantageously f a c i l i t a t e s t h e a d d i t i o n of t h e acid-form
20 a n i o n i c s u r f a c t a n t and t h e mixing t h e r e o f with t h e o l e f i n
polymer i n t h e production of f i b e r s and nonwoven f a b r i c s . An
o l e f i n polymer mixed with t h e acid-form a n i o n i c s u r f a c t a n t t o
g i v e t h e m a s t e r b a t c h m a y b e any o f t h e o l e f i n p o l y m e r s d e s c r i b e d
above o r any of o t h e r o l e f i n polymers. The MFR of t h e o l e f i n
polymer used in the masterbatch may be selected appropriately
in accordance with the target fibers and nonwoven fabrics
including the fibers.
[0028]
5 The inventive olefin polymer composition may contain
usual additives or polymers other than the olefin polymers as
required while still achieving the object of the invention.
Exemplary additives include antioxidants, weathering
stabilizers, light stabilizers, antiblocking agents,
10 lubricants, nucleating agents and pigments.
[0029]
(Fibers and nonwoven fabrics)
Fibers of the invention and nonwoven fabrics including
I
1 the fibers are formed of the olefin polymer composition I
I
I 15 containing the olefin polymer, the acid-form anionic
surfactant, and preferably the nonionic surfactant.
[0030]
In particular, fibers in which the acid-form anionic
surfactant has been melt kneaded in the olefin polymer
20 advantageously exhibit prolonged effects of reducing the
occurrence of skin rashes. When the nonionic surfactant is
used, this surfactant may be melt kneaded together with the
acid-form anionic surfactant. This configuration improves
melt kneading properties and allows the nonionic surfactant
and the acid-form anionic surfactant to be dispersed uniformly
on the surface of fibers.
[0031]
The inventive fibers usually have a fineness in the range
5 of 0.5to 5 d. The inventive fibersmaybediscontinuous fibers,
or may be preferably continuous fibers due to advantages such
as no fiber detachment from the nonwoven fabrics.
100321
The inventive fibers may have a circular cross section
10 or a modified cross section such as a V-shaped, X-shaped or
T-shaped cross section.
[0033]
The fibers of the invention may be side-by-side crimped
fibers which are formed of olefin polymer compositions
15 including at least two or more components. Preferred
configurations include side-by-side crimped fibers formed of
a propylene homopolymer and a propylene/ethylene random
copolymer as the olefin polymers.
[0034]
20 Alternatively, the fibers of the invention may be
concentric or eccentric fibers. In such cases, the acid-form
anionic surfactant and preferably the nonionic surfactant may
be added to both or one of the core and the sheath.
[0035]
S t i l l a l t e r n a t i v e l y , t h e i n v e n t i v e f i b e r s may be mixed
with o t h e r f i b e r s t o form mixed f i b e r nonwoven f a b r i c s . For
example, t h e i n v e n t i v e f i b e r s such a s t h e above crimped f i b e r s
may be mixed with o t h e r uncrimped f i b e r s t o form mixed f i b e r
5 nonwoven f a b r i c s .
Thenonwoven f a b r i c s oftheinventionusuallyhave a b a s i s
weight i n t h e r a n g e o f 10 t o 30 g/m2, and p r e f e r a b l y 15 t o 25
g/m2.
Depending on a p p l i c a t i o n s , t h e nonwoven f a b r i c s of t h e
i n v e n t i o n m a y b e e n t a n g l e d b y v a r i o u s known e n t a n g l i n g m e t h o d s ,
f o r 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 by p a r t i a l thermal f u s i o n bonding through
15 hot embossing w i t h a n embossing r o l l o r by blowing of hot a i r
through t h e f i b e r s . These e n t a n g l i n g methods may be used
s i n g l y , o r a p l u r a l i t y of t h e s e e n t a n g l i n g methods may be used
i n combination.
2 0 When t h e nonwoven f a b r i c s a r e t h e r m a l l y f u s i o n bonded by
hot embossing, t h e emboss a r e a p e r c e n t a g e is u s u a l l y i n t h e
range of 3 t o 30%. and p r e f e r a b l y 5 t o 20%. Exemplary shapes
of t h e bosses i n c l u d e round shapes, e l l i p t i c a l shapes, oval
shapes, square shapes, rhombic shapes, r e c t a n g u l a r shapes,
quadrangular shapes, quilt shapes, grid shapes, tortoiseshell
shapes, and continuous shapes based on these shapes.
[0039]
Depending on various applications, the nonwoven fabrics
5 of the invention may be used singly or as laminates (stacks)
in combination with other layers.
[0040]
Specific examples ofthe additional layers laminatedwith
the inventive nonwoven fabrics include knitted fabrics, woven
10 fabrics, nonwoven fabrics, films and paper products. Such
additional layers may be laminated (bonded) to the nonwoven
fabrics of the invention by any of various known methods, for
example, thermal fusion bonding methods such as hot embossing
and ultrasonic fusion bonding, mechanical entangling methods
15 such as needle punching andwater jetting, bondingmethods with
adhesives such as hot melt adhesives and urethane adhesives,
and extrusion lamination. The nonwoven fabrics of the
invention maintain rash suppressive effects even after
subjected to steps bringing the nonwoven fabrics into contact
20 with high-temperature substances such as hot melt adhesives
or during extrusion lamination. Thus, high convenience canbe
obtained in controlling product quality.
[0041]
The nonwoven fabrics laminated to the nonwoven fabrics
of the invention may be any of various known nonwoven fabrics
such as spunbonded nonwoven fabrics, meltblown nonwoven
fabrics, wet nonwoven fabrics, dry nonwoven fabrics, dry pulp
nonwoven fabrics, flash-spun nonwoven fabrics and split-fiber
5 nonwoven fabrics.
[0042]
Exemplary materials for such nonwoven fabrics include
various known thermoplastic resins, for example, polyolefins
which are homopolymers and copolymers of a-olefins such as
10 ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene
and 1-octene, with specific examples including high-pressure
low-density polyethylenes, linear low-density polyethylenes
(LLDPE), high-density polyethylenes, polypropylenes,
polypropylene random copolymers, poly(1-butene),
15 poly(4-methyl-1-pentene), ethylene/propylene random
copolymers, ethylene/l-butene random copolymers and
propylene/l-butene random copolymers, polyesters (such as
polyethylene terephthalates, polybutylene terephthalates and
polyethylene naphthalates), polyamides (such as nylon-6,
20 nylon-66 andpoly(meta-xylene adipamide), polyvinyl chlorides,
polyimides, ethylene/vinyl acetate copolymers,
polyacrylonitriles, polycarbonates, polystyrenes, ionomers,
thermoplasticpolyurethanes, andmixtures of these resins. Of
these, preferred resins include high-pressure low-density
I polyethylenes, linear low-density polyethylenes (LLDPE),
high-density polyethylenes, polypropylenes, polypropylene
random copolymers, polyethylene terephthalates and
polyamides.
5 [0043]
When spunbonded nonwoven fabrics of crimped fibers are
laminated to the inventive nonwoven fabrics, the obtainable
laminates exhibit excellent flexibility, bulkiness and touch.
When stretched nonwoven fabrics composed of mixed fibers of
10 continuous thermoplastic resin fibers and continuous
thermoplastic elastomer fibers are laminated to the inventive
nonwoven fabrics, the obtainable laminates exhibit excellent
stretchability in addition to the above properties.
[0044]
15 Whenthe inventivenonwoven fabrics areusedintop sheets,
second sheets or absorbent-wrapping sheets (core wraps) in
absorptive articles, for example, disposable diapers, it is
preferable that the fineness be in the range of 0.5 to 3 d and
the basis weight be in the range of 7 to 50 g/m2.
20 [0045]
In the case where the inventive nonwoven fabrics are used
in absorbent-wrapping sheets (core wraps) in absorptive
articles, the inventive nonwoven fabrics may be used as
laminates in combination with the above-described meltblown
nonwoven fabrics.
[0046]
The films laminated to the nonwoven fabrics of the
invention arepreferablybreathable (moisturepermeable) films
5 in order to better take advantage of rash suppressive effects
that are characteristics of the inventive nonwoven fabrics.
Various known breathable films may be used, with examples
includingmoisture permeable films of thermoplastic elastomers
such as polyurethane elastomers, polyester elastomers and
10 polyamide elastomers; and porous films obtained by drawing
thermoplastic resin films containinginorganic or organic fine
particles to create pores in the films. Preferred
thermoplastic resins used forthe porous films are polyolefins
such as high-pressure low-density polyethylenes, linear
15 low-densitypolyethylenes (LLDPE), high-densitypolyethylenes,
polypropylenes, polypropylene random copolymers, and
compositions of these resins.
[0047]
The inventive nonwoven fabrics may be subjected to
20 secondary processing such as gear processing, printing,
coating, lamination, heat treatment or shaping processing
while still achieving the object of the invention.
[0048]
(Processes for producing nonwoven fabrics)
In t h e case where d i s c o n t i n u o u s f i b e r s a r e used a s
m a t e r i a l s f o r t h e nonwoven f a b r i c s , t h e nonwoven f a b r i c s may
be produced by any of v a r i o u s known p r o c e s s e s such a s wet
p r o c e s s e s and dry p r o c e s s e s ( c a r d i n g ) .
5 [0049]
(Processes f o r producing continuous f i b e r nonwoven f a b r i c s )
Continuous f i b e r nonwoven f a b r i c s according t o t h e
p r e s e n t i n v e n t i o n may be produced by any of v a r i o u s known
nonwoven fabricproducingprocesses. A s p u n b o n d i n g p r o c e s s i s
10 p r e f e r a b l e b e c a u s e o f e x c e l l e n t p r o d u c t i v i t y .
[0050]
In t h e case of a spunbonding p r o c e s s , an i n v e n t i v e
continuous f i b e r nonwoven f a b r i c i n c l u d i n g monofilaments o f
t h e o l e f i n polymer compositionmaybe p r o d u c e d i n t h e following
15 manner. The composition is molten i n a s i n g l e e x t r u d e r a t 180
t o 250°c, p r e f e r a b l y 190 t o 230°c, and is extruded through a
s p i n n e r e t w i t h s p i n n i n g n o z z l e s t h a t has been s e t a t 180 t o
250°c, p r e f e r a b l y 190 t o 230°c, a t a throughput per o r i f i c e
of 0.4 t o 1 . 5 g/min, p r e f e r a b l y 0.5 t o 0.8 g/min, t h e r e b y
20 s p i n n i n g f i b e r s . The f i b e r s t h a t havebe enspun a r e c o o l e d w i t h
c o o l i n g a i r a t 10 t o 40°c, p r e f e r a b l y 20 t o 40°c, and a r e
a t t e n u a t e d t o a d e s i r e d f i n e n e s s with high v e l o c i t y a i r a t 2 0 0 0
t o 7000 m/min, p r e f e r a b l y 3000 t o 6000 m/min. The f i b e r s a r e
t h e n d e p o s i t e d o n t o a c o l l e c t i o n b e l t t o a d e s i r e d t h i c k n e s s
(basis weight) and are entangled by an entangling method such
as needle punching, water jetting or ultrasonicating, or by
partial thermal fusion bonding through hot embossing with an
embossing roll or by blowing of hot air through the fibers.
[0051]
(Absorptive articles)
Absorptive articles according to the invention utilize
the aforementioned nonwoven fabrics, preferably continuous
fiber nonwoven fabrics, in top sheets and/or second sheets,
or absorbent-wrapping sheets (core wraps). Examples of the
inventive absorptive articles include disposable diapers,
underwear or sanitary items, urine collection pads, and pet
sheets.
[0052]
In particular, when the nonwoven fabrics including
fibers ofthe olefinpolymer compositionareusedintop sheets,
second sheets or absorbent-wrapping sheets (core wraps) in
disposable diapers, the olefin polymer composition preferably
includes 0.5 to 30 parts by weight of the acid-form anionic
surfactant, or 0 . 5 t o 3 0 p a r t s b y w e i g h t o f t h e a c i d - f o r m a n i o n i c
surfactant plus 0.5 to 30 parts by weight of the nonionic
surfactant, with respect to 100 parts by weight of the olefin
polymer.
EXAMPLES
[0053]
The present invention will be describedin greater detail
based on examples hereinbelow without limiting the scope of
5 the invention to such examples.
[0054]
The degree of rash suppressive effects in examples and
comparative examples was evaluated by the following method.
[0055]
10 [Rash evaluation method]
The extent of rashes was evaluated in the following
manner.
Stool sampled from a healthy three year old child (male)
15 was diluted to 1% with distilled water and was centrifuged at
3000 rpm for 15 minutes using cooling high-speed centrifuge
H-201FR manufactured by KOKUSAN Co., Ltd. The supernatant
liquid was collected as an evaluation liquid. To the
evaluation liquid, a nonwoven fabric sample produced in any
20 of the following examples and comparative examples was soaked
for 1 minute or 30 minutes and was thereafter attached to the
skin of three rabbits provided in accordance with IS0 10993-10
(Tests forirritationanddelayed-typehypersensitivity). The
skin condition after 48 hours was observed.
[Evaluation criteria]
1 point: Substantially no changes were observed on the
skin of all the three rabbits.
5 [0058]
2 points: Slight edema and spots were found on one or two
rabbits.
[0059]
3 points: Slight edema and spots were found on all the
10 three rabbits.
[0060]
4 points: Edema andspots were foundonone or two rabbits.
[0061]
5 points: Edema and spots were found on all the three
15 rabbits.
6 points: Marked edema and spots were found on all the
three rabbits.
[0063]
20 [Extrudability]
1 point: The composition was excellently engaged with an
extruder screw.
[0064]
2 points: The composition was engaged with an extruder
screw with d i f f i c u l t i e s . V a r i a t i o n s i n nozzle p r e s s u r e
occurred.
LO0651
[Example 11
5 A composition was prepared a s d e s c r i b e d below which
contained100 p a r t s byweight of an o l e f i n p o l y m e r andan amount
d e s c r i b e d i n Table 1 of an acid-form a n i o n i c s u r f a c t a n t or a
nonionic s u r f a c t a n t . 10 P a r t s by weight o f s t e a r i c a c i d
(product name: LUNAC S-90V manufactured by Kao Corporation)
10 as an acid-form a n i o n i c s u r f a c t a n t , and 10 p a r t s by weight of
anadduct of stearylalcoholwithethylene oxide (IRGASURFHL560
manufactured by BASF (former Ciba) ) a s a nonionic s u r f a c t a n t
were m e l t kneaded and extruded a t 2 3 0 " ~t o g e t h e r with 79.95
p a r t s b y w e i g h t o f a p r o p y l e n e / e t h y l e n e randomcopolymer (PP-1)
15 having a melting p o i n t (Tm) of 1 4 2 " ~an d a MFR of 60 9/10 min
and 0.05 p a r t s by weight o f a n a n t i o x i d a n t (product name:
IRGAFOS168manufacturedbyBASF ( f o r m e r c i b a ) ) . Thus, p e l l e t s
of a masterbatch (MB-1) were p r e p a r e d .
[0066]
20 Next, 40 p a r t s by weight of t h e MB-1 was admixed with 60
p a r t s by weight of t h e PP-1 t o give a propylene polymer
composition (a composition 1).
[0067]
In o r d e r t o e v a l u a t e e x t r u s i o n performance, t h e
composition 1 was placed into a single screw extruder (screw
diameter 30 mm, L/D = 30) and was molten by heating with a
throughput of 4.4 kg/hr at a resin temperature of 200°C. The
composition 1 was engaged with the screw of the extruder as
5 excellently as when the surfactants were not added.
[0068]
Next, the composition 1 was melt spun by a spunbonding
process to form a continuous fiber nonwoven fabric. After the
spinning, the nonwoven fabric was subjected to hot embossing
10 using an embossing roll with rhombic bosses having an emboss
area percentage of 18% and an emboss area (an area per boss)
of 0.41 mm2, at an embossing roll temperature and a flat roll
temperature of 125°C and a linear pressure of 60 N/mm. Thus,
a continuous fiber nonwoven fabric with a basis weight of 20
15 g/m2 was obtained. The obtained continuous fiber nonwoven
fabric was tested by the above rash evaluation method to
evaluate the extent of rashes. The results are described in
Table 1.
20 [Examples 2 to 61
Continuous fiber nonwoven fabrics were obtained in the
samemanner asinExample1, except that the following compounds
were used as the acid-form anionic surfactant and the nonionic
surfactant, as well as that the amounts were changed as
described in Table 1. The obtained continuous fiber nonwoven
fabrics were tested by the above rash evaluation method to
evaluate the extent of rashes. The results are described in
Table 1.
5 [0070]
Myristic acid (C14): LUNAC MY-98 (product name)
manufactured by Kao Corporation
Oleth-4 phosphate (C18): PHOSPHANOL RB-410 (product
name) manufactured by TOHO Chemical Industry Co., Ltd.
10 [Example 71
A composition was prepared as described below which
contained100 parts byweight of anolefinpolymer andan amount
described in Table 1 of an acid-form anionic surfactant or a
nonionic surfactant. 5 Parts by weight of dodecylphosphoric
15 acid (manufactured by TAKEMOTO OIL & FAT CO., LTD.) as an
acid-form anionic surfactant, and 14 parts by weight of
poly(oxyethy1ene) 1,6-hexanediol dilaurate (manufactured by
TAKEMOTO OIL & FAT CO., LTD.) and 1 part by weight of
poly(oxyethy1ene) sorbitan trioleate ester (manufactured by
20 TAKEMOTO OIL & FAT CO., LTD.) as nonionic surfactants were melt
kneaded and extruded at 1 8 0 " ~to gether with 79.95 parts by
weight of a propylene/ethylene random copolymer (PP-1) having
a melting point (Tm) of 1 4 2 "a~n d a MFR of 60 g/10 min and 0.05
parts by weight of an antioxidant (product name: IRGANOX 1010
manufactured by BASF (former Ciba)). Thus, pellets of a
masterbatch (MB-2) were prepared.
[0071]
Next, 20 parts by weight of the MB-2 was admixed with 80
5 parts by weight of the PP-1 to give a propylene polymer
composition (a composition 2).
[0072]
In order to evaluate extrusion performance, the
composition 2 was placed into a single screw extruder (screw
10 diameter 30 mm, L/D = 30) and was molten by heating with a
throughput of 4.4 kg/hr at a resin temperature of 200'~. The
composition 2 was engaged with the screw of the extruder as
excellently as when the surfactants were not added.
[0073]
Next, the composition 2 was melt spun by a spunbonding
process to form a continuous fiber nonwoven fabric. After the
spinning, the nonwoven fabric was subjected to hot embossing
using an embossing roll with rhombic bosses having an emboss
area percentage of 18% and an emboss area (an area per boss)
20 of 0.41 mm2, at an embossing roll temperature and a flat roll
temperature of 125°C and a linear pressure of 60 N/mrn. Thus,
a continuous fiber nonwoven fabric with a basis weight of 20
g/mZ was obtained. The obtained continuous fiber nonwoven
fabric was tested by the above rash evaluation method to
evaluate the extent of rashes. The results are described in
Table 1.
[0074]
[Examples 8 and 91
5 Continuous fiber nonwoven fabrics were obtained in the
samemanner asinExample 7, except that the following compounds
were used as the acid-form anionic surfactants while the
nonionic surfactants used in Example 7 were not changed, as
well as that the amounts were changed as described in Table
10 1. The obtained continuous fiber nonwoven fabrics were tested
by the above rash evaluation method to evaluate the extent of
rashes. The results are described in Table 1.
[0075]
Anionic surfactants
15 Octylphosphoric acid (C8): manufacturedby TAKEMOTO OIL
& FAT CO., LTD.
Octadecan-1-yl dihydrogen phosphate (C18): manufactured
by TAKEMOTO OIL & FAT CO., LTD.
Dioctadecyl hydrogen phosphate (C18): manufactured by
20 TAKEMOTO OIL & FAT CO., LTD.
[0076]
[Table 11
Extrudability
1
1
1
1
1
1
1
2
1
Rash
L U U l t :
EX.
I
2
3
4
5
6
7
8
9
1Min
2
2
2
1
1
3
I
1
1
Nonionic surfactants
I
Process
Kneading
Kneading
Kneading
Kneading
Kneading
Kneading
Kneading
Kneading
Kneading
evaluation
30Min
soak
2
2
3
1
2
3
1
2
1
Types
EO adduct of stearyl alcohol
EO adduct of stearyl alcohol
EO adduct of stearyl alcohol
Poly(oxyethy1ene) 1,6-hexanediol
dilaurate
Poly(oxyethy1ene) sorbitan
trioleate ester
~ol(yo xyethylene) 1,6-hexanediol
dilaurate
Poly(oxyethy1ene) sorbitan
trioleate ester
Poly(oxyethy1ene) 1,6-hexanediol
dilaurate
Poly(oxyethy1ene) sorbitan
trioleate ester
Acid-form anionic surfactants zk: pts - )
4
4
4
3
0.2
3
0.2
3
0.2
Amt.
(wt.
pts.)
4
4
4
4
4
2
1
1
1
Types
Stearic acid
Stearic acid
Myristic acid
Oleth-4 phosphate
Oleth-4 phosphate
Stearic acid
Dodecyl phosphoric acid
Octyl phosphoric acid
Octadecan-1-yl
dihydrogen phosphate
Dioctadecyl hydrogen
phosphate
Number of carbon
atoms in
hydrophobic group
C18
C18
C14
C18
C18
C18
C12
C 8
C18
C18
[Comparative Example 11
A continuous fiber nonwoven fabric was obtained in the
samemanner as in Example 1, except that the nonionic surfactant
5 used in Example 1 alone was added and any acid-form anionic
surfactants were not added. The obtained continuous fiber
nonwoven fabric was tested by the above rash evaluation method
to evaluate the extent of rashes. The results are described
in Table 2.
[Comparative Examples 2 to 61
The PP-1 was melt spun by a spunbonding process to form
a continuous fiber nonwoven fabric. After the spinning, the
nonwoven fabric was subjected to hot embossing using an
15 embossing roll with rhombic bosses having an emboss area
percentage of 18% and an emboss area (an area per boss) of 0.41
mm2, at an embossing roll temperature and a flat roll
temperature of 1 2 5 " ~an d a linear pressure of 60 ~/mm. Thus,
continuous fiber nonwoven fabrics (NW-1) with a basis weight
20 of 20 g/m2 were obtained. In Comparative Examples 2 to 6
described in Table 2, the following compounds were dissolved
in an aqueous isopropyl alcohol solution with a concentration
adjusted such that the compounds would exhibit solubility in
the solution, thereby preparing coating liquids. The coating
l i q u i d s were each a p p l i e d t o t h e nonwoven f a b r i c s NW-landwere
t h e r e a f t e r d r i e d . Byrepeatingtheapplicationanddrying, t h e
dry weights were c o n t r o l l e d t o be t h e p r e s c r i b e d amounts of
t h e compounds added which a r e d e s c r i b e d i n Table 2. The
5 obtained nonwoven f a b r i c s were t e s t e d by t h e above rash
e v a l u a t i o n method t o e v a l u a t e t h e e x t e n t of r a s h e s . The
r e s u l t s a r e d e s c r i b e d i n Table 2.
[0079]
Anionic s u r f a c t a n t s
C i t r i c a c i d (C6): r e a g e n t manufactured by Wako Pure
Chemical I n d u s t r i e s , Ltd.
O c t y l i c a c i d (C8): r e a g e n t m a n u f a c t u r e d b y KHNeochemCo.,
Ltd.
S t e a r y l a l c o h o l (C18) : KALCOL 8098 (product name)
15 manufactured by Kao Corporation
Dodecyl phosphoric a c i d (C12): manufactured by TAKEMOTO
OIL & FAT CO., LTD.
Nonionic s u r f a c t a n t s
Poly (oxyethylene) 1,6-hexanediol d i l a u r a t e :
20 manufactured by TAKEMOTO OIL & FAT CO., LTD.
Poly(oxyethy1ene) s o r b i t a n t r i o l e a t e e s t e r
(manufactured by TAKEMOTO OIL & FAT CO., LTD. )
[0080]
[Table 21
INDUSTRIAL APPLICABILITY
[0081]
The f i b e r s of 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 s i n c l u d i n g t h e f i b e r s c a n b e s u i t a b l y used a s top s h e e t s
5 orsecondsheetsofhygienematerials s u c h 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 i t e m s .

[Claim 1 1
. *w2.y
CLAIMS
A f i b e r comprising a n o l e f i n polymer composition
comprising 100 p a r t s by weight of an o l e f i n polymer and 0.1
5 t o 30 p a r t s by weight of an acid-form a n i o n i c s u r f a c t a n t , t h e
acid-form a n i o n i c s u r f a c t a n t having been m e l t kneaded i n t h e
f i b e r .
[Claim 21
The f i b e r according t o claim 1, wherein t h e acid-form
10 a n i o n i c s u r f a c t a n t h a s a n a l i p h a t i c hydrocarbon group i n which
a hydrophobic group has not less than 9 carbon atoms.
[Claim 31
The f i b e r according t o claim 1, wherein t h e acid-form
a n i o n i c s u r f a c t a n t i s a fattyacidhavingnotlessthan 9 carbon
15 atoms.
[Claim 41
The f i b e r according t o claim 1, wherein t h e acid-form
a n i o n i c s u r f a c t a n t is a phosphate e s t e r s u r f a c t a n t i n which
a hydrophobic group has not l e s s than 9 carbon atoms.
20 [Claim 51
The f i b e r a c c o r d i n g t o c l a i m l , w h e r e i n t h e o l e f i n p o l y m e r
composition comprises 0.1 t o 30 p a r t s by weight of a nonionic
s u r f a c t a n t .
[Claim 61
The f i b e r a c c o r d i n g t o c l a i m l , whereinthe olefinpolymer
is a propylene polymer.'
[Claim 71
The f i b e r according t o claim 6, wherein the propylene
5 polymer i s a propylene/a-olefin random copolymer comprising
propylene and an a - o l e f i n and having a melting point (Tm) i n
t h e range of 125 t o 1 5 5 " ~ .
[Claim 81
The f i b e r according t o any of claims 1 t o 7 , wherein the
10 f i b e r is a continuous f i b e r .
[Claim 91
Anonwoven f a b r i c c o m p r i s i n g t h e f i b e r d e s c r i b e d i n claim
8.
[Claim 101 I
15 An a b s o r p t i v e a r t i c l e i n which the nonwoven f a b r i c
described i n claim 9 is used i n a top sheet and/or a second
s h e e t .
[Claim 111
An a b s o r p t i v e a r t i c l e i n which the nonwoven f a b r i c
20 described i n claim 9 is used i n an absorbent-wrapping At.
--
Dated this 2oth day of November, 20 13