Note: Descriptions are shown in the official language in which they were submitted.
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Al~,SORE~ lT ARTICLE WITH INTF:RMAL WICKING MEANS
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Background o the Invention
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The use of superabsorbents in absorbent articles permits a
substantial reduction in the bulk of the absorbent
article. However, attempts to utilize superabsorbent
materials in absorbent structures such as diapers and
sanitary napkins have met with limited success. It is
often difficult ,to "fix in place~ or secure super-
absorbents within the absorbent article. U.S. Patent
3,971,379 discloses absorbent articles wherein a layer of
super-absorbent is folded or rolled with another absorbent
component of the absorbent article. Secondly, super-
absorbent materials absorb and retain hundreds of times~ 83
; their weight of fluids,bt~ey do not easily wick fluids.
In an absorbent article, rapid swelling of the
superabsorbent together with its lack of wicking ability
can create a fluid "block", preventing the utilization o
the remainder of the superabsorbent, or other absorbent
materials in the absorbent article.
New methods of utilizing superabsorbents into absorbent
articles focus on methods of incorporating the
superabsorbent into a fibrous structure so as to avoid the
blocking problem~. U.S. Patent 4,105,033 discloses
method of incorporating a superabsorbent into a fibrous
structure, and U,S. Patent 4,226,237 discloses a more
elaborate fibrous structure of absorbent fibers and peat
moss, into which superabsorbent may be distributed.
The present invention involves a new approach to the use
of superabsorbents in an absorbent article. ~ather than
attempt to create new fibrous structures wherein the
superabsorbent is so dispersed as to prevent blocking, the
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present invention may use known fibrous materials
containing superabsorbents which materials when used
alone may block. In the absorbent article of -the present
invention, the superabsorbent may be dispersed within a
fibrous structure or cellular foam or may be present in
a film, alone or together with other ingredients.
According to the present invention, an internal wicking
means is provided within the absorbent article to bring
the fluid to the superabsorbent. The wicking means is
wrapped or folded about discrete layers containing the
superabsorbent.
Methods of folding absorbent fibrous materials to form
absorbent articles are shown in U.S. Patent 2,952,259.
However, there is no teaching of superabsorbents or
internal wicking means.
The present invention, in one of its broad aspects,
comprises an absorbent article having discrete super-
absorbent layers. The absorbent article has a wicking
means which is wound about and between the superabsorbent
layers.
The wicking means comprises a wicking layer, and a fluid
transfer means between the wicking layer and the super-
absorbent layers. The superabsorbent layers ~ay comprise
superabsorbent ingredients dispersed within a fibrous
layer or upon a ,fibrous layer, or superabsorbent dispersed
within a cellular foam material, or films made partially
or entirely of superabsorbent materials. Orlon (Registered
Trademark) fabric, peat moss, or wood pulp tissue material
may be used as the wicking layer. The fluid transfer
layer may comprise pulp tissu~ material. A partial outer
wrap of fluid impermeable material may be disposed about all
but one major surface of the absorbent article. In a dispos-
able diaper the plastic film partial outer wrap may be sealed
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to the outer surface of the disposable diaperl reinforcing
- the diaper and enhancing the repositionability of adhesive
tape tabs thereto.
Brief Description of the Drawings
Figure l shows a schematic cross-section of one embodiment
of the absorbent article of the present invention.
Figure 2 shows a cross-section of a one embodiment of the
absorbent article shown schematically in Figure 1.
Figure 2A shows a cross-section of another embodiment of
the absorbent article shown schematically in Figure 1
Figure 3 shows a cross-section of another preferred
embodiment of the absorbent article of the present
invention.
Figure 4 shows a cross-section of a disposable diaper
incorporating the absorbent article of the present
invention.
Figure 5 shows a preferred embodiment of a disposable
diaper incorporating the absorbent article of the present
invention.
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Figure 6 shows a perspective view of the diaper of Figure5.
Detailed Descri tion of the Invention
The present invention comprises an absorbent article
which utilizes superabsorbent materials in a novel way.
According to the present invention, an internal wicking
means is utilized to move fluid within an absorbent
article that contains superabsorbent materials.
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As shown schematically in Figure 1, one em,bodiment of the ~ m
absorbent article of the present invention~generally at 10
comprises at least two discrete layers 12 having a
superabsorbent material incorporated therein. The
absorbent article further comprises a wicking means 14
which extends in an S-shape wound about and between the
superabsorbent layers. The present invention does not
rely on the form or construction of the superabsorbent
layer, and many varieties of materials incorporating
superabsorbent agents may be utilized. For instance, the
superabsorbent lay~r may comprise superabsorbent material
incorporate~ within a fibrous layer, or a cellular foam
layer. The method of incorporating the superabsorbent
in~o the fibrous layer or cellular foam is not critical as
it is not required that fluid pass throuyh the
superabsorbent layer, but only that the surfaces of the
superabsorbent layers absorb. Indeed, according to the
present invention, the superabsorbent layers may comprise
films made wholly or in part of superabsorbent materials.
In the absorbent article of the present invention, the
superabsorbent layers need not wick or transport fluid as
the internal wick of the absorbent article brings the
fluid to the superabsorbent material. Hence, when the
superabsorbent material within the layers swell, it cannot
block the movement of the fluid through the absorbent
article. If the superabsorbent at any particular part of
the absorbent article swells or reaches saturation, the
internal wicking means merely moves the fluid to be
absorbed on to the next available superabsorbent
material.
~he following test da~a demonstrate the superiority of
Applicant's absorbent article having internal wicking
means. The absorbent capacity of three diaper structures
incorporating the absorbent article of the present
invention as described in Figure 1 was tested. In the
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test procedure used, which is intended to simulate diaper
use, the diapers are fastene~ around a lifesize doll and
test solution is poured through the doll into the diaper
in 150 milliliter aliquats, with a twenty minute wait
between aliquats. The test is stopped at the first
indication of a leak. The diapers are weighed beore and
after the test so that the amount of liquid absorbed by
the diaper can be determined. Each of the diapers had a
co-extruded Visqueen polypropylene film backing (17 1/2" X
12") and a similarly sized facing m~terial of 100 percent~
embossed polypropylene 0.7 oz/yd.2~ ~ The superabsorbent ~'
layers comprise 8 gr/ft2 Henkel fabric S6P manufactured by
the Henkel Corporation. The Henkel fabric comprises S6P-
147, a ceric ion catalyzed starch acrylonitrile graft
polymer in powder form, sandwiched between two layers of
tissue. In diaper No. 1, the absorbent body of the
diaper, contained between the facing and backing sheet,
comprised two layers of the ~enkel superabsorbent fibrous
layer S6P and had no internal wick. The absorbent capacity
was 72.8 grams. In diaper No. 2, the absorbent article
incorporated between the backing and the facing comprised
two layers of the same Henkel fabric with an S-shaped
wicking layer of tissue. The absorbent capacity of diaper
No. 2 was 165.9 grams. In diaper No. 3, the absorbent
article contained between the backing sheet and the facing
comprised two layers of the same Henkel superabsorbent
fibrous layer, a~d an S-shaped internal wicking layer of
Orlon~ fabric. The absorbent capacity of diaper No. 3 was
179.1 grams.
Figure 2 disc1oses one embodiment of the absorbent article
of the present invention shown schematically in Figure 1.
In this embodiment, the absorbent article shown at 20
comprises superabsorbent layers 22 and an internal wicking
means 24 which comprises a wicking layer 26 and a fluid
transfer means 2~. The ~icking layer 26 may comprise ~ny
material which has good wicking properties. It is not
-required that this material have good absorbent capacity
or be able to retain fluids under stress. Suitable
materials ~or use as the wicking layer are Orlon~ fabric,
pulp tissue material or peat moss. Fluid transfer means
may be present between the wicking layer and at least the
major surfaces of the superabsorbent layers. In the
examples listed above, the tissue layers of the Henkel
fabric ser~e as the fluid transfer means. The fluid
transfer means 28 effects the transfer of the fluid from
the wicking layer~to the superabsorbent layer. The use of
the intermediate fluid transfer means aids in keeping the
internal wicking means or pathway open at all times and
allows the wicking layer to wick while the fluid transfer
means holds the fluid for absorption in the superabsorbent
layers.
The absorbent article 20 has major surfaces 32a and 32b,
side e~ges 34/ and erd edges, not shown. The absorbent
article may have a partial outer wrap 30 of a fluid
impervious material, which covers at least one major
surface 32a and the side edges 34 of the absorbent
article, and may also cover the end edges. This partial
outer wrap comprises a preferred construction of the
absorbent article, as the fluid impermeable layer retains
the fluid in the absorbent article, allowing time for the
fluid to be absorbed by the superabsorbent la~ers. In
addition, in an absorbent article utilizing this wrapped
construction, the fluid impervious layer hides the off
color appearance or texture of other absorbent materials
e.g., reground pulp used in the absorbent article and
encapsulates and hides the gel-like nature o~ the
superabsorbent when wetted. This preferred absorbent
article may also be provided with a facing layer 36
on the other major surace 32b not covered by the partial
outer wrap.
Figure 2A discloses another embodiment of the absorbent
article of the present invention shown schematically in
Figure 1. The absorbent article shown generally at 20a
comprises superabsorbent layers 22a and internal wicking
means 24a. The wicking means comprises a wicking layer
26a and fluid transfer means 28a. As shown in this
embodiment, the fluid transfer means may comprise a layer
coextensive with the wicking layer. In this construction,
the wicking layer may be incorporated between two layers
of fluid transfer means, and this multilayer composite
structure wound in an S-shape about and around the
superabsorbent layers. This construction of the wicXing
means and of the absorbent article o the present
invention differs from that shown in Figure 2 wherein the
fluid transfer means is disposed between the wicking layer
and the major surfaces of each superabsorbent layer. This
embodiment may also incorporate a fluid impermeable layer
30 and a facing layer 36 comparable to those described at
30 and 36 of Figure 2. When used as a sanitary napkin the
absorbent article may further comprise adhesive strips 38
for attachment to an undergarment.
Figure 3 shows another embodiment of the absorbent article
of the present invention, shown generally at 40. The
absorbent article shown here in cross-section comprises
superabsorbent layers 42 and an internal wicking means 44
which comprises a,wicking layer 46 wound about and between
the superabsorbent layers in an ~e" shape. The wicking
means comprises a wicking layer 46 and a fluid transfer
means 48. In the particular embodiment shown, each of the
superabsorbent layers has been wrapped in a fluid transfer
means such as tissue prior to the winding of the wicking
layer about and between the superabsorbent layers. When
the wrapping of the fluid transf2r means and the winding
of the wick is comple~ed, the wicking layer extends across
the major surfaces of ~he superabsorbent layers and fluid
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transfer means are disposed between the wicking layer and
each major face of the superabsorbent layers. The
juxtapositioning of the wicking layer and fluid transfer
means to this superabsorbent layer provides an internal
wicking means for the superabsorbent layers. Optionally,
this embodiment of the absorbent article of the present
invention may also incorporate a facing iayer 36 and a
partial outer wrap~ ~ as described in relation to Figures
2 and 2A.
The superabsorbent materials utilized in the present
invention comprise various hydrocolloid and hydrogel
materials which have the ability to absorb 10 to 30 times
their own dry weight and preferably many hundreds of times
their own dry weight of fluids. Many superabsorbent
materials are known in the art and the present invention
does not depend on the chemical or physical structure of
the superabsorbent, or the structure of a composite
wherein the superabsorbent is incorporated with other
materials, e.g., fibers in a fibrous layer. As
superabsorbents tend to swell quickly and block the
passage of additional fluid, in most product applications
superabsorbent materials are incorporated with other
materials such as fibers or foams to disperse the
superabsorbent materials and prevent blocking. As the
absorbent article of the present invention comprises
discrete superabsorbent layers, it avoids the "working" by
folding and bending of the fibrous layer or cellular foa~
layer which may cause the superabsorbent to become
disattached from the fibrous layer or cellular foam, and
agglomerate. In addition, tlle construction of the
absorbent article of the prèsent invention provides an
easier method of manufacture than folding of the
superabsorbent layers ~nd requires a lesser length of
wicking material in the wickiny layer than would be
utili~ed in a folded shape such as ~hat shown in U.S~
Patent 3,791,379.
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Figure 4 discloses a disposable diaper utilizing the
absorbent article of the present invention. The absorbent
article of the present invention may be utilized in many
structures such as sanitary napkins and dressings, as well
as in various diaper structures. Figure 4 discloses a
diaper structure shown generally at 50, said structure
comprising an outer layer 52, an absorbent article of the
present invention 10, attached thereto, and tape tabs 56.
The diaper may further comprise a facing layer 58
comprising the inside surface of the diaper.
As shown in Figure 5, when the absorbent artlcle of the
present invention comprises a partial outer wrap 30 of
fluid impermeable material as shown with relation to
absorbent articles 20 (or 40, not shown) in Figures 2, 2A
~or 3) above, it is not necessary that the outer layer 62
of the diaper, shown generally at 60, be fluid
impermeable. In a preferred construction, both the outer
layer 62 and the outer wrap 30 of the absorbent article
comprise ~lastic films. The securing of the absorbent
article within the diaper secures the two plastic films,
reinforcing the outer layer of the diaper. As the tape
tabs 66 can be more easily peeled from the two layer
plastic lal~inate, the diaper may be opened without tearing
the plastic film outer layer which can render the adhesive
tape tab unusahle as well as allowing the inner absorbent
material of the diaper to leak out. In addition, the
cleanly peeled adhesive tape tab is available to make a
new diaper fastening. Also with this absorbent article
construction of the present invention having an outer wrap
30, neither pulp or superabsorbent gel may leak from the
diaper.
Figure 6 shows the diaper of Figure 5 view from the outer
surface of the diaper illustrating that the region wherein
the outer layer 62 is juxtaposed to the partial outer wrap
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30, reinforcing the outer layer and enhancing the reposition-
ability of the tape tabs 66. In the preferred embodiment
shown, the diaper includes elastic gathering means 68 in the
leg regions.
The foregoing description and drawings are illustrative but
are not to be taken as limiting. Other variations and
modifica-tions are possible without departing from the spirit
and scope of the present invention.
