Note: Descriptions are shown in the official language in which they were submitted.
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RESILIENT ABSORBENT COMPOSITE MATERIAL
FIELD OF INVENTION
The present invention generally relates to an absorbent composite material and
an
absorbent article including such absorbent composite material. More
particularly, the
present invention relates to an absorbent composite material for use in
sanitary absorbent
articles such as sanitary napkins, pantiliners, diapers, adult incontinence
products, and the
like.
BACKGROUND OF THE INVENTION
Lofty, resilient, non-woven webs, that is nonwoven webs that have a high
degree
of loft and the tendency to retain such loft in both the dry and wet state,
are well known.
In addition, it is well known that such lofty, resilient, nonwoven webs may be
used in
disposable sanitary products such as sanitary napkins, pantiliners, tampons,
diapers, adult
incontinence products, and the like. A perceived benefit of such lofty,
resilient,
nonwoven webs is that such materials may deliver enhanced comfort to a user of
such
disposable sanitary products since the lofty, resilient, nonwoven webs may
tend to
conform to, and move with, the user's body during use.
A problem with lofty, resilient, nonwoven webs is that due to the loft of such
materials (i.e. their low density) such webs are not particularly absorbent.
In addition,
such materials may exhibit poor rewet properties. That is, such materials may
release or
"wet back" fluid when subjected to an external pressure.
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In view of the foregoing there is a need for an absorbent composite material
that
includes an exceptionally soft, cushiony, nonwoven web and simultaneously
provides
superior fluid handling characteristics.
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SUMMARY OF THE INVENTION
In view of the foregoing, the present invention provides, according to a first
aspect of the invention, an absorbent composite material including a fibrous
material
including a plurality of individual fibers forming a fiber matrix and a binder
material present
in an amount from 20% to 60% by weight of the fibrous material, the fibrous
material having
first and second opposed surfaces, superabsorbent polymer dispersed within the
fiber matrix,
an absorbent mixture arranged adjacent to the first surface of the fibrous
material, the
absorbent mixture including superabsorbent polymer and adhesive.
The present invention provides, according to a second aspect of the invention,
an absorbent article including a liquid permeable cover layer, a liquid
impermeable barrier
layer, and an absorbent composite material arranged between the cover layer
and the barrier
layer, wherein the absorbent composite material includes a fibrous material
including a
plurality of individual fibers forming a fiber matrix and a binder material
present in an amount
from 20% to 60% by weight of the fibrous material, the fibrous material having
first and
second opposed surfaces, superabsorbent polymer dispersed within the fiber
matrix, and an
absorbent mixture arranged adjacent to the first surface of the fibrous
material, the absorbent
mixture including superabsorbent polymer and adhesive.
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BRIEF DESCRIPTION OF THE DRAWINGS
Examples of embodiments of the present invention will now be described with
reference to the drawings, in which:
Fig. 1 is a sectional schematic view of an absorbent composite material
according to a first embodiment of the present invention;
Fig. 2 is a schematic view of an apparatus for making the absorbent composite
material shown in Fig. 1;
Fig. 3 is a sectional schematic view of an absorbent composite material
according to a second embodiment of the present invention;
Fig. 4 is a schematic view of an apparatus for making the absorbent composite
material shown in Fig. 3;
Fig. 5 is a schematic view of the encircled portion of the apparatus shown in
Fig. 4 depicting a needle employed in the apparatus, a top surface of a
fibrous material, and
absorbent fibers arranged on the top surface of the fibrous material;
Fig. 6 is a detailed view of the encircled portion of the needle shown in Fig.
5;
Figs. 7-10 depict the manner in which the needle impregnates the absorbent
fiber within the fibrous material;
Fig. 11 is a perspective view of an absorbent article according to the present
invention;
Fig. 12 is an exploded perspective view of the article shown in Fig. 11
revealing the constituent layers thereof;
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Fig. 13 is sectional view taken along line x-x in Fig. 11 showing one
embodiment
of the absorbent article shown in Fig 11; and
Fig. 14 is sectional view taken along line x-x in Fig. 11 showing an alternate
embodiment of the absorbent article shown in Fig. 11.
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DETAILED DESCRITION OF THE INVENTION
The present invention generally relates to an absorbent composite material for
use
in disposable absorbent articles such as sanitary napkins, pantiliners,
absorbent products
for incontinence, and other disposable sanitary absorbent articles worn close
to a wearer's
body. Although the absorbent composite material according to the present
invention will
be described herein with reference to a sanitary napkin, the absorbent
composite material
may be utilized in other disposable sanitary absorbent articles.
The absorbent composite material according to the present invention, as
described
in detail below, is structured and arranged such that it provides superior
fluid absorbing
properties and at the same time is "resilient". The term "resilient" as used
herein means
that the absorbent composite material tends to retain its shape both in the
dry and wet
states and when subjected to a compression force tends to recover its original
shape when
such force is removed. Absorbent articles according to the present invention
including
the inventive absorbent composite material are thin, flexible, resilient in
the x, y and z
directions, and exhibit superior fluid handling characteristics. "Resilient in
the x, y and z
direction" as used herein means the absorbent article exhibits resiliency
properties in the
transverse direction of the article, in the longitudinal direction of the
article, and the
direction extending into the article.
Reference is made to Fig. 1 which illustrates a sectional view of an absorbent
composite material 10 according to a first embodiment of the present
invention. As
shown, the absorbent composite material 10 includes, in part, a fibrous
material 12
including a plurality of individual fibers 14 that form a fiber matrix 16. The
fibrous
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material 12 generally includes a top (or first) surface 18 and an opposed
bottom (or
second) surface 20.
The fibrous material 12 is preferably a fibrous nonwoven material made by a
known nonwoven manufacturing technique such as an airlaid process, a card and
bind
process or a resin and adhesive bond process. Preferably the nonwoven material
is a
"high loft" nonwoven. Specifically, the nonwoven preferably has a density
lower than
0.05 g/cc, and preferably between about 0.01 g/cc and 0.03 glee. The
individual fibers 14
forming the fibrous nonwoven material may be selected from fibers including
synthetic,
nonabsorbent fibers that may or may not be wettable. Specific fiber types
include, but
are not limited to, polyester, nylon, co-polyester, polyethylene,
polypropylene, polylactic
acid, and bicomponent fibers including these materials. Of course the fibrous
nonwoven
material may be formed from a single nonabsorbent fiber type listed above or
alternatively may be formed from a mixture of the fiber types listed above.
The surface of the nonabsorbent fibers 14 forming the fibrous material 12 may
be
rendered wettable by treating such fibers with a suitable surface treatment,
such as a
surfactant or like. The fibrous material 12 preferably further includes a
binder material,
such as a latex binder. The binder material is preferably present in the
fibrous material
12 in an amount that corresponds to between about 20% by weight to about 60%
by
weight of the fibrous material 12. The individual fibers 14 forming the
fibrous material
preferably have a denier in the range from about 5 to about 25, preferably
from about 6 to
about 10. Each of the fibers 14 forming the fibrous material preferably has a
fiber
diameter within the range of 11 p.m and 100 iLtm. In preferred embodiments of
the
invention, the fibrous material 12 is completely free of cellulosic material.
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The fibrous material 12 preferably has a basis weight in the range of about 50
gsm
(g/m2) to about 150 gsm, preferably from about 60 gsm to about 90 gsm
(including the
binder material). The fibrous material 12 preferably has a thickness of
between about 2
mm to about 6 mm as measured by a Ames Micrometer (Ames Waltman Mass., Model
ADP1132, 175 g on the 1 1/8" foot = 0.384 psi). A fibrous material 12
particularly
suitable for use in the present invention is a material made from a randomized
web
sprayed with binder from both sides of the web, having a basis weight of 86
gsm, formed
from 100% 6 denier polyester fibers, having a thickness of about 3 mm, and
including
about 40% latex binder by weight, commercially available under product code
SCNO9-
038 from Kern-Wove, Inc., Charlotte, NC.
As shown in Fig. 1, the absorbent composite material 10 further includes
superabsorbent polymer 22 dispersed within the fiber matrix 16. The
superabsorbent
polymer 22 is preferably present in the fibrous material 12 in an amount that
corresponds
to between about 100% to about 150% by weight of the fibrous material 12, e.g.
between
about 80 gsm and about 120 gsm.
For the purposes of the present invention, the term "superabsorbent polymer"
(or
"SAP") refers to materials which are capable of absorbing and retaining at
least about 10
times their weight in body fluids under a 0.5 psi pressure. The superabsorbent
polymer
particles of the invention may be inorganic or organic crosslinked hydrophilic
polymers,
such as polyvinyl alcohols, polyethylene oxides, crosslinked starches, guar
gum, xanthan
gum, and the like. The particles may be in the form of a powder, grains,
granules, or
fibers. Preferred superabsorbent polymer particles for use in the present
invention are
crosslinked polyacrylates, such as the products offered by Sumitomo Seika
Chemicals
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Co., Ltd. of Osaka, Japan, under the designation of SA70 and BA40B. The
superabsorbent polymer 22 present in the absorbent composite 10 may consist of
a single
superabsorbent such as SA70 or alternatively the superabsorbent polymer 22 may
consist
of a mixture of superabsorbent polymers such as a mixture of SA70 and BA40B.
In
addition, different superabsorbent polymers may be arranged in a layered
arrangement,
for example the faster rate BA40B may be arranged above the SA70.
Referring again to Fig. 1, the absorbent composite material 10 further
includes an
absorbent mixture 24 arranged adjacent to the top surface 18 of the fibrous
material 12.
The absorbent mixture 24 includes superabsorbent polymer 26 and adhesive 28.
Preferably the absorbent mixture 24 consists of a mixture of superabsorbent
polymer 26
and adhesive 28. The mixture 24 preferably includes between about 90% and
about 98%
superabsorbent by weight and between 10% and about 2% adhesive by weight.
Preferred
superabsorbents for use in the mixture include Sumitomo SA70 and Sumitomo
BA40B,
commercially available from Sumitomo Seika Chemicals, Co., Ltd., Osaka, Japan.
Preferably a hot melt adhesive is used as the adhesive in the mixture 24. A
particularly
suitable adhesive is HB Fuller NW1023 hot melt adhesive, commercially
available from
HB Fuller Company, St. Paul, MN. The mixture 24 is preferably applied to the
top
surface 18 of the fibrous material 12 in an add on amount of between about 80
gsm and
100 gsm. This add on amount of the mixture 24 corresponds to between about
100% to
150% by weight of the fibrous material 12.
In lieu of the absorbent mixture 24 described above, a simple layer of
adhesive
could alternatively be applied adjacent to the top surface 18 of the fibrous
material 12. In
such an embodiment the adhesive would not provide additional absorbency to the
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composite material 10 but would rather simply help prevent the superabsorbent
polymer
22 from "dusting out" of the fiber matrix 16.
Referring again to Fig. 1, the absorbent composite material 10 further
includes a
superabsorbent retention layer 30. As shown in Fig, 1, the superabsorbent
retention layer
.. 30 is arranged adjacent to a top surface 32 of the mixture 24 and is held
in place by the
'mixture 24. The superabsorbent retention layer 30 functions to prevent the
superabsorbent polymer 22 from "dusting out" of the fiber matrix 16.
The superabsorbent retention layer 30 may also be adapted to wick fluid in a
longitudinal and transverse direction of the composite material 10 so that the
composite
material 10 can fully utilize its absorbent attributes.
In one embodiment of the invention, the superabsorbent retention layer 30 may
consist of a wetlaid tissue having a basis weight in the range of about 10 gsm
to about 20
gsm, such as a 17 gsm wetlaid tissue commercially available as Little Rapids
type 2004
wetlaid tissue, Little Rapids Corp., Green Bay, Wisconsin.
In another embodiment of the invention, the superabsorbent retention layer 30
may consist of fibrous material including wood pulp fibers, polyester fibers,
rayon fibers,
or combinations thereof. The superabsorbent retention layer 30 may also
comprise
thermoplastic fibers for the purpose of stabilizing the layer and maintaining
its structural
integrity. Examples of materials suitable for the superabsorbent retention
layer 30 are
through air bonded pulp sold by Buckeye Technologies, Inc. of Memphis, Tenn.
under
TM TM
the designation Vizorb 3008 which has a basis weight of 100 gsm and Vizorb
3010
which has a basis weight of 90 gsm.
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Another example of a material suitable for use as the superabsorbent retention
layer 30 is a calendared airlaid material of the type commercially available
from EAM
Corporation, Jessup, GA under the designation Novathin. When calendared
airlaid
materials are used as the superabsorbent retention layer 30 such materials
preferably have
a basis weight in the range of about 40 gsm to about 90 gsm. The
superabsorbent
retention layer 30 is preferably free of superabsorbent polymer.
Another example of a materials suitable for use as the superabsorbent
retention
layer 30 are commercially available paper towel materials.
A method of making the absorbent composite material 10 will now be described
with reference to Fig. 2 which depicts a schematic representation of an
apparatus 40 for
making the absorbent composite material 10. As shown in Fig. 2, a web of
fibrous
material 12 is fed from a supply roll 42 and conveyed in a machine direction
by a
plurality of rolls 44, 46 and 48 to a superabsorbent application station 50.
The
superabsorbent application station 50 comprises a metering device 52
structured and
arranged to apply a selected amount of superabsorbent polymer 22 to a top
surface 18 of
the fibrous material 12. Metering devices for applying particulate material to
a substrate
are well known to those of skill in the art. Of course, any suitable means
known to those
of skill in the art, such as a pressure fed nozzle, a brush metering roll, or
the like, may be
used to apply the superabsorbent polymer material 22 to the top surface 18 of
the fibrous
material 12. After the superabsorbent polymer material 22 is applied to the
top surface
18 of the fibrous material 12, the fibrous material 12 is conveyed over a high
frequency
vibrator 54 that functions to mechanically force the superabsorbent polymer 22
into the
fibrous matrix 16 of the fibrous material 12. Alternatively, a vacuum arranged
below the
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bottom surface 20 of the fibrous material 12 may be used to draw the
superabsorbent
polymer 22 into the fibrous matrix 16.
Thereafter, the fibrous material 12 is further conveyed in a machine direction
by a
plurality of rolls 56, 58 and 60 to an absorbent mixture application station
62. The
absorbent mixture application station 62 includes a metering device 64 for
applying a
stream of superabsorbent polymer 26 to the top surface 18 of the fibrous
material 12.
The absorbent mixture application station 62 further includes a hot melt
adhesive
applicator 66 which is directed at the fibrous material 12 and adapted to
apply a stream of
adhesive 28 to the top surface 18 of the fibrous material 12. Preferably the
adhesive 28
stream and superabsorbent polymer 26 stream mix in mid air, thereby forming
the
absorbent mixture 24, and then the absorbent mixture 24 is deposited on the
top surface
18 of the fibrous material 12.
Thereafter, the fibrous material 12 is further conveyed in a machine direction
by a
plurality of rolls 66, 68 and 70. The superabsorbent retention layer 30 is
then arranged
adjacent to the top surface 32 of the mixture 24 by means of rolls 72 and 74.
Then the
substrate 12 and superabsorbent retention layer 30 are passed through nip
rolls 75 and 76
to thereby adhere the superabsorbent retention layer 30 to the absorbent
mixture 24.
Thereafter the completed absorbent composite material 10 is further conveyed
in a
machine direction by rolls 77 and 78 and may be arranged in a rolled form for
storage or
may be further conveyed for incorporation into a disposable sanitary absorbent
product
such as a sanitary napkin, pantiliner, tampon, diaper, adult incontinence
product, or the
like.
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Reference is made to Fig. 3 which illustrates a sectional view of an absorbent
composite material 10a according to a second embodiment of the present
invention.
Absorbent composite material 10a includes the same features as described above
with
regard to composite material 10, however absorbent composite material 10a
further
includes a plurality of absorbent fibers 17. As shown, the absorbent fibers 17
are
impregnated within the fiber matrix 16. The absorbent fibers 17 are preferably
present in
the fibrous material 12 in an amount between 5% to about 100% by weight of the
fibrous
material 12, corresponding to about 3 gsm to about 60 gsm. The absorbent
fibers 17 are
preferably selected from cellulosic fiber types, such as, but not limited to,
hard wood
pulp, soft wood pulp, rayon, and cotton. The absorbent material 10 may include
a single
absorbent fiber type of those listed above or in the alternative may include
multiple fiber
types of those listed above (i.e. a mixture of absorbent fibers). Each of the
absorbent
fibers 17 preferably has fiber diameter within the range of 10 p.m and 40 pm.
The
individual fibers 14 forming the fibrous material 12 and the absorbent fibers
17 are
selected such that each of the individual fibers 14 has a fiber diameter that
is at least 1
1.11n greater than a fiber diameter of each of the absorbent fibers 17.
A method of making the absorbent composite material 10a will now be described
with reference to Fig. 4 which depicts a schematic representation of an
apparatus 40a for
making the absorbent composite material 10. As shown in Fig. 4, a web of
fibrous
.. material 12 is fed from a supply roll 42 and conveyed in a machine
direction by a
plurality of rolls 44, 46 and 48 to a superabsorbent application station 50.
The
superabsorbent application station 50 comprises a metering device 52
structured and
arranged to apply a selected amount of superabsorbent polymer 22 to a top
surface 18 of
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the fibrous material 12. Metering devices for applying particulate material to
a substrate
are well known to those of skill in the art. Of course, any suitable means
known to those
of skill in the art, such as a pressure fed nozzle, a brush metering roll, or
the like, may be
used to apply the superabsorbent polymer material 22 to the top surface 18 of
the fibrous
material 12. After the superabsorbent polymer material 22 is applied to the
top surface
18 of the fibrous material 12, the fibrous material 12 is conveyed over a high
frequency
vibrator 54 that functions to mechanically force the superabsorbent polymer 22
into the
fibrous matrix 16 of the fibrous material 12. Alternatively, a vacuum arranged
below the
bottom surface 20 of the fibrous material 12 may be used to draw the
superabsorbent
.. polymer 22 into the fibrous matrix 16.
Thereafter the fibrous material is further conveyed in a machine direction by
rolls
100, 102 and 104 to a gravity fed hopper 106, or the like, that is utilized to
apply a
selected amount of absorbent fibers 17 to a top surface 18 of the fibrous
material 12. If
required, the material forming the absorbent fibers may be fed through a
lickerin or a
hammermill prior to the absorbent fibers being fed into the gravity fed hopper
(not shown
in the drawings). Thereafter, the fibrous material 12 is further conveyed in a
machine
direction and passed through a conventional needlepunch apparatus 108 of the
type
known to those of skill in the art. The needlepunch apparatus 108 functions to
impregnate the absorbent fibers 17 within the fibrous material 12 by means of
a plurality
of needles 110.
As is known to those of skill in the art, a conventional needlepunch apparatus
includes a plurality of needles that are normally adapted to mechanically
orient and
interlock the fibers of a spunbonded or carded web. In the present invention,
the needles
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110 of the needlepunch apparatus 108 are used to impregnate absorbent fibers
17 within
the fibrous material 12. A needle 110 suitable for use in the method described
herein is
depicted in Fig. 5 and Fig. 6. As shown in Fig. 6, the needle 110 generally
includes a
blade 112, a barb 114, and a throat section 116. The total barb depth of the
barb 114 is
indicated by letter "d" in the Fig. 6.
For purposes of the present invention, it is critical that the barb depth "d"
is
selected such that a radius of each of the absorbent fibers 17 is smaller than
the barb
depth "d". The radius of each absorbent fiber 17 is at least 0.5 1,trn
smaller, for example 1
1.im smaller than the barb depth. In addition the barb depth "d" should be
selected such
that each of the individual fibers 14 of the fibrous material 12 has a radius
that is larger
than the barb depth "d". The radius of each individual fiber 14 of the fibrous
material 12
is at least 0.5 1AM larger, for example 1 tirn larger than the barb depth. If
you have a
multiple denier fibrous material 12, the diameter of the smallest diameter
fiber 14 must
be larger than the diameter of each of the absorbent fibers 17.
By selecting barb depth "d" as described above, the plurality of needles 110
in the
needlepunch apparatus effectively grasp the absorbent fibers 17 and thus can
impregnate
such absorbent fibers 17 within the fibrous material 12, as shown in Figs 7-
10. On the
other hand, the plurality of needles 110 will not grasp the individual fibers
14 of the
fibrous material 12 and thus will not destroy the "high loft" properties of
the fibrous
material 12. In this manner the final absorbent composite material 10 is
provided with
superior fluid handling properties while still retaining the high loft
properties of the
fibrous material 12. Needles particularly useful in the present method are
commercially
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available from the Foster Needle Co., Inc., Manatowoc, Wisconsin, under
product
designation "The Foster Formed Barb".
Thereafter, the fibrous material 12 is further conveyed in a machine direction
by a
plurality of rolls 56, 58 and 60 to an absorbent mixture application station
62. The
absorbent mixture application station 62 includes a metering device 64 for
applying a
stream of superabsorbent polymer 26 to the top surface 18 of the fibrous
material 12.
The absorbent mixture application station 62 further includes a hot melt
adhesive
applicator 66 which is directed at the fibrous material 12 and adapted to
apply a stream of
adhesive 28 to the top surface 18 of the fibrous material 12. Preferably the
adhesive 28
stream and superabsorbent polymer 26 stream mix in mid air, thereby forming
the
absorbent mixture 24, and then the absorbent mixture 24 is deposited on the
top surface
18 of the fibrous material 12.
Referring again to Fig. 4, the fibrous material 12 is further conveyed in a
machine
direction by a plurality of rolls 66, 68 and 70. The superabsorbent retention
layer 30 is
then arranged adjacent to the top surface 32 of the mixture 24 by means of
rolls 72 and
74. Then the substrate 12 and superabsorbent retention layer 30 are passed
through nip
rolls 75 and 76 to thereby adhere the superabsorbent retention layer 30 to the
absorbent
mixture 24. Thereafter the completed absorbent composite material 10 is
further
conveyed in a machine direction by rolls 77 and 78 and may be arranged in a
rolled form
for storage or may be further conveyed for incorporation into a disposable
sanitary
absorbent product such as a sanitary napkin, pantiliner, tampon, diaper, adult
incontinence product, or the like.
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Absorbent composite materials 10 according to the to the present invention, as
described herein above, are thin, lofty and exhibit superior resiliency
properties in both
the dry and wet state. Surprisingly, absorbent composite materials 10
according to the
present invention exhibit the above properties while at the same time
exhibiting superior
fluid handling characteristics.
Reference is made to Figs. 11-14 which depict an absorbent article, and in
particular a sanitary napkin 80, in accordance with the present invention. As
shown in
Fig. 12, the sanitary napkin 80 generally includes a liquid permeable cover
layer 82, a
liquid impermeable barrier layer 84 and the absorbent composite material 10
arranged
therebetween. The sanitary napkin 80 may further optionally include a fluid
distribution
layer 85 arranged between the cover layer 82 and the absorbent composite
material 10.
The cover layer 82 may be a relatively low density, bulky, high-loft non-woven
web material. The cover layer 82 may be composed of only one type of fiber,
such as
polyester or polypropylene or it may include a mixture of more than one fiber.
The cover
may be composed of bi-component or conjugate fibers having a low melting point
component and a high melting point component. The fibers may be selected from
a
variety of natural and synthetic materials such as nylon, polyester, rayon (in
combination
with other fibers), cotton, acrylic fiber and the like and combinations
thereof. Preferably,
the cover layer 82 has a basis weight in the range of about 10 gsm to about 75
gsm.
Bi-component fibers may be made up of a polyester layer and a polyethylene
sheath. The use of appropriate bi-component materials results in a fusible non-
woven
fabric. Examples of such fusible fabrics are described in U.S. Pat. No.
4,555,430 issued
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Nov. 26, 1985 to Chicopee. Using a fusible fabric increases the ease with
which the cover
layer may be mounted to the absorbent layer and/or to the barrier layer.
The cover layer 82 preferably has a relatively high degree of wettability,
although
the individual fibers comprising the cover may not be particularly
hydrophilic. The cover
material should also contain a great number of relatively large pores. This is
because the
cover layer 82 is intended to take-up body fluid rapidly and transport it away
from the
body and the point of deposition. Therefore, the cover layer contributes
little to the time
taken for the napkin to absorb a given quantity of liquid (penetration time).
Advantageously, the fibers which make up the cover layer 82 should not lose
their
physical properties when they are wetted, in other words they should not
collapse or lose
their resiliency when subjected to water or body fluid. The cover layer 82 may
be treated
to allow fluid to pass through it readily. The cover layer 82 also functions
to transfer the
fluid quickly to the underlying layers of the napkin. Thus, the cover layer 82
is
advantageously wettable, hydrophilic and porous. When composed of synthetic
hydrophobic fibers such as polyester or bi-component fibers, the cover layer
82 may be
treated with a surfactant to impart the desired degree of wettability.
Nonwoven cover materials particularly suitable for use in the present
invention
are hot-through air bonded cover materials commercially available from
Shalag Industries, Ltd., Upper Galilee, Israel, under product codes STA4ETW27,
STA5ETW27, STAFEPW27, STA5EPW27, STAPPER22 and STAFETW22.
Alternatively, the cover layer 82 can also be made of polymer film having
large
pores. Because of such high porosity, the film accomplishes the function of
quickly
transferring body fluid to the inner layers of the underlying absorbent
layers.
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The cover layer 82 may be attached to the underlying absorbent composite
material 10
and/or the barrier layer 84, by adhesion and/or other suitable means know to
those of skill
in the art. The cover layer 82 may also be attached to the underlying fluid
distribution
layer 85 if such layer is employed.
Underlying the cover layer 82 is the optional fluid distribution layer 85. The
fluid
distribution layer 85 functions to receive body fluid from the cover layer 82
and hold the
same until the absorbent composite 10 has an opportunity to absorb the fluid.
The fluid
distribution layer 85 is preferably more dense than and has a larger
proportion of smaller
pores than the cover layer 82. These attributes allow the fluid distribution
layer 85 to
contain the body fluid and hold it away from the outer side of the cover layer
82, thereby
preventing fluid from rewetting the cover layer 82.
The fluid distribution layer 85 may consist of fibrous material including wood
pulp fibers, polyester fibers, rayon fibers, or combinations thereof. The
fluid distribution
layer may also comprise thermoplastic fibers for the purpose of stabilizing
the layer and
maintaining its structural integrity. Examples of materials suitable for the
fluid
distribution layer 85 are through air bonded pulp materials sold by Buckeye
Technologies, Inc. of Memphis, Tenn. under the designation Vizorb 3008 which
has a
basis weight of 100 gsm and Vizorb 3010 which has a basis weight of 90 gsm.
Another example of a material suitable for use as the fluid distribution layer
85 is
a calendared airlaid material of the type commercially available from EAM
Corporation,
Jessup, GA under the designation Novathin. The fluid distribution layer 85 is
preferably
free of superabsorbent polymer.
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CA 02790297 2012-09-19
PPC-5364-USNP
Underlying absorbent composite material 10 is a barrier layer 84 comprising a
liquid-impervious film material so as to prevent liquid that is entrapped in
the absorbent
composite layer 10 from egressing the sanitary napkin and staining the
wearer's
undergarment. The barrier layer 84 is preferably made of polymeric film,
although it
may be made of liquid impervious, air-permeable material such as repellent-
treated non-
woven or micropore films or foams.
The barrier layer 84 may be breathable, i.e., permits vapor to transpire.
Known
materials for this purpose include nonwoven materials and microporous films in
which
microporosity is created by, inter alia, stretching an oriented film. Single
or multiple
layers of permeable films, fabrics, melt-blown materials, and combinations
thereof that
provide a tortuous path, and/or whose surface characteristics provide a liquid
surface
repellent to the penetration of liquids may also be used to provide a
breathable backsheet.
The cover layer 82 and the barrier layer 84 are preferably joined along their
marginal
portions so as to form an enclosure or flange seal that maintains the
absorbent composite
layer 10 captive. The joint may be made by means of adhesives, heat-bonding,
ultrasonic
bonding, radio frequency sealing, mechanical crimping, and the like and
combinations
thereof.
Positioning adhesive may be applied to a garment facing surface of the barrier
layer 84 for securing the napkin 80 to a garment during use. The positioning
adhesive
may be covered with removable release paper so that the positioning adhesive
is covered
by the removable release paper prior to use.
Absorbent articles of this invention may or may not include wings, flaps or
tabs
for securing the absorbent article to an undergarment. Wings, also called,
among other
81661533
things, flaps or tabs, and their use in sanitary protection articles is
described in U.S.
Patent. No. 4,687,478 to Van Tilburg; U.S. Patent No. 4,589,876 also to Van
Tilburg,
U.S. Patent No. 4,900,320 to McCoy, and U.S. Patent No. 4,608,047 to
Mattingly. As
disclosed in the above documents, wings are generally speaking flexible and
configured
to be folded over the edges of the underwear so that the wings are disposed
between the
edges of the underwear.
Reference is now made to Figs. 13 and 14 which depict sectional views taken
along line x-x in Fig. 11 and depict alternative embodiments of the sanitary
napkin 80
shown in Fig. 11. As shown in Fig. 13, the absorbent composite material 10 may
be
arranged in the sanitary napkin 80 such that the superabsorbent retention
layer 30 is
arranged in adjacent surface to surface contact with the barrier layer 84. The
embodiment of the napkin 80 shown in Fig. 13 includes a fluid distribution
layer 85. Of
course, however the fluid distribution layer 85 could be omitted such that the
second
surface 20 of the fibrous material 12 is arranged in surface to surface
contact with the
cover layer 82.
Alternatively, as shown in Fig. 14, the absorbent composite material 10 may be
arranged in the sanitary napkin 80 such that the superabsorbent retention
layer 30 is
arranged in adjacent surface to surface contact with the cover layer 82.
Absorbent articles according to the present invention, as described above, are
thin,
cushiony, soft, exhibit superior resiliency properties in both the dry and wet
state, and
also exhibit superior fluid handling characteristics.
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CA 2790297 2018-11-23
