Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02593885 2014-04-01
ABSORBENT ARTICLE WITH EMBOSSING
BACKGROUND OF THE INVENTION
According to the present invention, an absorbent article is described having
improved absorbency
characteristics and a method of making the same. More particularly, the
present invention describes an
absorbent core of an airlaid material having an embossed pattern on its top
surface. The use of absorbent
articles has become quite prevalent in today's world.
They have been improved and modified so as to have varying shapes, sizes, and
characteristics as
per the particular application. For example, baby diapers are large smooth
articles with high absorbent
capacity, thus making it possible for the baby to wear the article for a long
period of time. At the same
time, sanitary pads or pantiliners worn by females are relatively small
articles that are not noticeable from
the outside, thus avoiding the wearer any embarrassment.
One of the areas in this field where a significant amount of research has been
done is in the
construction of the absorbent core of the article. The absorbent core,
generally, absorbs and retains body
fluids so that they can be easily disposed of.
In order to improve the absorbency, retention and other desired properties of
the core, various
natural and synthetic materials have been introduced in its construction. The
objective being that the core
should be an optimized result of the weight of its constituents and the
absorbency and retention it offers.
In the most simplistic construction of an absorbent article, this core is
disposed between a liquid
permeable body facing top sheet and a liquid impermeable garment facing back
sheet. However since
this portion forms the bulk of the article, it contributes significantly to
the comfort factor when the article
is worn. More so, when the article is worn, this portion is disposed in the
crotch region of the wearer,
where even a slight amount of discomfort is least desirable.
Furthermore, since a combination of natural and man made fibers and other
materials are used in
making an efficient absorbent core, it is important to bind the materials
together so as to provide
uniformity as well as strength. In order to provide the desired amount of
strength, softness, as well as
looks, one common approach in the field is to bind the absorbent core fibers
by embossing the core.
The embossing also achieves a combination of high density embossed regions
and/or lines along
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with low-density non-embossed regions. This combination creates lines, or
depressions, in the absorbent
core that aid in an efficient absorption of the body-released fluids.
U. S. Patent No. 4,518,451, issued to Luceri et al., discloses an embossed
pantiliner where the
body facing side is imposed with a relatively deep pattern of depressed areas,
and the longitudinal edges
are imposed with a pattern of relatively shallow depressed areas. This results
in a pantiliner that has
aesthetically effective embossing while providing comfortable longitudinal
edges.
U. S. Patent No. 4,623,340, issued to Luceri, discloses an absorbent
pantiliner provided with a
pattern of depressed areas. The outer cover of the pantiliner is made from a
relatively light opaque sheet
material and the interior layer is at least partially thermoplastic and
relatively dark colored. When the
cover is embossed, the depressed areas appear darker than the un-embossed
areas.
U. S. Patent No. 5,514,104 issued to Cole et al., discloses an absorbent
article comprising an
absorbent core having a body-facing side and a garment-facing side. The
garment facing side of the
absorbent core, i.e. bottom layer, is embossed to form a pattern of areas of
differing density. The
embossed pattern on the bottom layer of the absorbent core improves the
removal of urine or other fluids
from the discharge zone to be ready for the next void.
U. S. Patent Publication No. 2004/0267220 of Raymond, describes an absorbent
article having an
embossing pattern defined as a raised portion on an upper layer. The embossing
pattern of a type letter,
word, mark, hatch line, number, logo, etc, is applied. However, the embossing
pattern with diamond or
square edges is observed to be stiff to the wearer.
Owing to the nature of the embossing procedure and the embossed design
pattern, the absorbent
core is not very smooth or comfortable when worn close to the body. If the
pattern is polygonal, it makes
the whole core very rigid. Sometimes the edges of the polygon also add to the
discomfort of the wearer.
Furthermore because of the polygonal nature of the pattern, narrow channels
are formed thereby
limiting the storage capacity for the liquid that is yet to be absorbed by the
core.
It is therefore desirable to have a configuration of the absorbent core that
is comfortable to be
worn as well as offering enhanced absorption properties.
It is an objective of the present invention to provide an improved core that
is smooth to the body
and comfortable to wear.
It is a further objective of the invention to provide a core with increased
fluid storage and
retention capacity.
It is yet another objective of the present invention to have desired rigidity
in the absorbent core.
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SUMMARY OF THE INVENTION
To achieve the aforementioned objectives, and to overcome the drawbacks of the
prior art, the
present invention provides for an absorbent core that is embossed with a
circular or oval pattern. Such a
configuration of an embossing pattern results in a smoother top surface as
well as increased spacing
between individual tufted areas, and provides more space for the body exudates
to accumulate until they
get absorbed by the core.
The present invention describes an absorbent article comprising a top sheet, a
back sheet, an
absorbent core disposed between the top sheet and the back sheet, and a fluid
transfer layer disposed
between the top sheet and the absorbent core. The absorbent core of the
absorbent article is made of an
airlaid material. Alternatively, the absorbent core may also be provided with
an airlaid material having
from about 45% to about 95% by weight of superabsorbent polymeric material.
Further, an important
aspect of the present invention is that the absorbent core is embossed,
preferably with a circular pattern
along its entire top surface.
The invention also includes a method of making an absorbent article that
includes providing a top
sheet material and a back sheet material. The method also includes preparing
an absorbent core having a
circular embossed pattern, and disposing the absorbent core between the top
sheet material and the back
sheet a material. The method further includes preparing a fluid transfer layer
comprised of three
dimensional aperture film, and disposing the transfer layer between the top
sheet material and the
absorbent core. The transfer layer can be a loft, non woven, or any other
material known in the art. The
core can be made of an airlaid material containing SAP.
In one embodiment, the absorbent article has a top sheet, a fluid transfer
layer disposed
underneath the top sheet, a back sheet, and an absorbent core disposed between
the fluid transfer layer
and the back sheet. The absorbent core is made of an airlaid material and can
be devoid of any
superabsorbent polymeric material. Further, the absorbent core is embossed
with a circular pattern on its
top surface. The fluid transfer layer is provided with a longitudinal length
and lateral width of a smaller
dimension as compared to the absorbent core. Preferably, the fluid transfer
layer is a strip which does not
cover the entire crotch region of the absorbent article.
In another embodiment of the present invention, the absorbent core is embossed
with an oval
shaped pattern.
The invented absorbent article preferably has a third insult strikethrough
time of less than about
80 seconds, more preferably less than about 75 seconds, even more preferably
less than about 70 seconds,
and most preferably less than about 65 seconds. Further, the absorbent article
preferably has a third insult
rewet value of less than about 1.25 grams, more preferably less than about 1.1
grams, and most preferably
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less than about 1.0 grams.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a partially cut away top view of an absorbent article of the 30
invention.
FIG. 2 is a cross sectional view of the absorbent article depicted in FIG. 1.
FIG. 3 shows a conventional absorbent article having a diamond-shaped
embossing pattern on an
absorbent core.
FIG. 4 shows the invented absorbent article having a circular embossing
pattern on the absorbent
core according to an embodiment of the invention.
FIG. 5 shows the invented absorbent article having an oval embossing pattern
on the absorbent
core according to another embodiment of the invention.
FIG. 6 shows yet another embodiment of the invented absorbent article.
FIG. 7 shows an alternate embodiment of the invented absorbent article.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to an absorbent article having improved
absorbance characteristics
and a method of making the same. More particularly, the present invention
discloses an absorbent core of
an airlaid material having a circular embossed pattern on its top surface. The
present invention provides
an absorbent article having superior properties of absorbency, leakage
protection, and/or skin wellness, as
well as being aesthetically pleasing.
As used herein, the terms "absorbent article", "absorbent garment", or simply
"article" or
"garment" refer to devices that absorb and contain body fluids and other body
exudates. More
specifically, these terms refer to garments that are placed against or in
proximity to the body of a wearer
to absorb and contain the various exudates discharged from the body. A non-
exhaustive list of examples
of absorbent garments includes pantiliners, sanitary napkins, feminine hygiene
products, protective
underwear, diapers, diaper covers, disposable diapers, training pants, and
adult incontinence products.
Such garments may be intended to be discarded or partially discarded after a
single use ("disposable"
garments). Such garments may comprise essentially a single inseparable
structure ("unitary" garments),
or they may comprise replaceable inserts or other interchangeable parts.
The present invention may be used with all of the foregoing classes of
absorbent articles, without
limitation, whether disposable or otherwise. The absorbent article of the
present invention is optionally a
pantiliner, sanitary napkin, feminine hygienic garment, protective underwear,
diaper, incontinent brief,
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training pant, diaper holder, diaper liner, or combinations thereof. In the
embodiments described herein,
an exemplary structure of a pantiliner is provided. However this is not
intended to limit the claimed
invention. The invention will be understood to encompass, without limitation,
all classes, and types of
absorbent articles, including those exemplified herein.
The term "longitudinal", as used herein, refers to an axis or direction in the
plane of the absorbent
article that is generally aligned with a vertical plane which bisects a
standing wearer into left and right
body halves when the absorbent article is worn. The term "lateral" refers to
the line, axis, or direction
perpendicular to the longitudinal direction, which lies within the plane of
the absorbent article. The
length in the longitudinal axis and lateral axis represent the length and
width of an absorbent article.
Throughout this description, the term "disposed" and the expressions "disposed
on," "disposing
on," "disposed in," "disposed between" and variations thereof (e.g., a
description of the article being
"disposed" is interposed between the words "disposed" and "on") are intended
to mean that one element
can be integral with another element, or that one element can be a separate
structure bonded to or placed
with or placed near another element. Thus, a component that is "disposed on"
an element of the absorbent
article can be formed or applied directly or indirectly to a surface of the
element, formed or applied
between layers of a multiple layer element, formed or applied to a substrate
that is placed with or near the
element, formed or applied within a layer of the element or another substrate,
or other variations or
combinations thereof.
Throughout this description, the terms "top sheet" and "back sheet" denote the
relationship of
these materials or layers with respect to the absorbent core. It is understood
that additional layers may be
present between the absorbent core and the top sheet and back sheet, and that
additional layers and other
materials may be present on the side opposite the absorbent core from either
the top sheet or the back
sheet.
The phrases "target", "target point", "target region" or "target area" are
each used synonymously
and refer to the area or location on an absorbent article where an insult is
normally delivered by a wearer,
or a nozzle or other device in an experimental method.
The term "strikethrough" is used herein to denote the amount of time it takes
for a liquid to pass
through the material being tested. Strikethrough is a measure of the fluid
acquisition properties of the
material, and can be referred to as the rate of absorbency. Strikethrough is
measured in accordance with
the test procedures defmed hereinafter. Unless indicated otherwise,
strikethrough values are reported
herein in seconds.
The term "rewet" is used herein to mean the retransmission of liquid from the
absorbent core to
the body or wearer side of the top sheet when the disposable absorbent article
is in use. Rewet therefore
is a measure of the absorbent article's fluid retention capabilities under
load. Low rewet means low
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retransmission of liquid from the fluid transport layer and /or absorbent core
to the body or wearer side of
the top sheet. The rewet property of an absorbent article is determined by the
procedure outlined in the
test procedures section below. Unless indicated otherwise, rewet values are
reported herein in grams.
The present invention relates to the construction and configuration of the
absorbent core that is
present in absorbent articles such as diapers, training pants, sanitary pads,
and pantiliners. The invention
improves the absorbent core so as to make it a better absorbent article in
terms of absorbent capacity as
well as its feel to the portions of the body it comes in contact with. The
configuration of the rest of the
absorbent article, such as its shape and size, do not pertain to the invention
and do not directly affect the
performance of the invention. However they may be ancillary features that add
to the final result of
absorption capacity and feel of the core.
More particularly, the present invention relates to absorbent articles, and in
particular to an
absorbent article that contains a top sheet, a back sheet, an absorbent core
disposed at least partially
between the top sheet and the back sheet, and a fluid transfer layer disposed
between the top sheet and the
absorbent core. The absorbent core is comprised of an airlaid material. The
airlaid material may be
provided without superabsorbent polymer, or may be provided with from about
45% to about 95% by
weight of superabsorbent polymer. The fluid transfer layer can be prepared
with a three dimensional
aperture film. The absorbent article of the invention has a third insult
strikethrough time of less than
about 80 seconds, and a third insult rewet value of less than about 1.25
grams.
The invention also relates in general to a method of making an absorbent
article that includes
providing a top sheet material and a back sheet material. The method also
includes preparing an
absorbent core of an airlaid material having a circular embossed pattern and
disposing the absorbent core
between the top sheet and the back sheet. The method further includes
preparing a fluid transfer layer
comprising a three dimensional aperture film, and disposing the fluid transfer
layer between the top sheet
and the absorbent core to form an absorbent article that has a third insult
strikethrough time of less than
about 80 seconds, and a third insult rewet value of less than about 1.25
grams.
The absorbent article of the invention preferably has two longitudinal edges,
an anterior end and a
posterior end, and two lateral edges. Those skilled in the art will recognize
that "anterior" and "posterior"
in the context of the invention denote for clarity purposes only the front and
rear of a user, and that the
absorbent article could be reversed whereby the previously described
"anterior" portion becomes the
"posterior" portion, and vice versa.
hi the present invention, the absorbent article preferably has a third insult
strikethrough of less
than about 80 seconds, and a third insult rewet of less than about 1.25 grams.
More preferably, the
absorbent article has a third insult strikethrough of less than about 75
seconds, and a third insult rewet of
less than about 1.20 grams, and even more preferably, a third insult
strikethrough of less than about 70
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seconds, and a third insult rewet of less than about 1.10 grams. Most
preferably, the absorbent article has
a third insult strikethrough of less than about 65 seconds, and a third insult
rewet of less than about 1.0
grams. Although described together, the preferred absorbent articles need not
have the same combination
of preferred strikethrough and rewet, thus enabling an absorbent article
having, say, a third insult
strikethrough of less than about 75 seconds, and a third insult rewet of less
than about 1.0 grams.
It is preferred in the present invention to characterize the absorbent
articles by their third insult
strikethrough and rewet values. This is believed to be because many materials
will have comparable first
insult strikethrough and rewet values, but materials that prevent leakage will
be differentiated from the
other materials at the second and third insult values. In addition, first
insult strikethrough and rewet data
do not provide much information about an absorbent article in a stressed
condition. Thus, first insult
strikethrough and rewet values are not necessarily good predictors of
materials that will have good third
insult strikethrough and rewet. In addition, it is not practical to change an
absorbent article after the first
insult, and in the evening, three or more insults typically occur prior to
changing the absorbent article.
Consequently, absorbent articles having good third insult strikethrough and
rewet will be more suitable
for extended use absorbent articles. Moreover, it is believed that absorbent
garments that have low third
insult rewet values keep the skin drier immediately after use, and since dry
skin helps keep the skin
healthy, consumers recognize low rewet as a benefit. Finally, it is believed
that absorbent garments
having low third insult strikethrough can improve the leakage performance of
the absorbent article.
The present invention will now be described with reference to the accompanying
drawings. The
drawings are being used to illustrate the inventive concept, and do not intend
to limit the invention to the
embodiments shown therein.
Referring to the figures, FIG. 1 is a partially cut away depiction of an
exemplary embodiment of
an absorbent article 10 of the present invention as shown. The embodiment
shown in FIG. 1 is a feminine
hygiene product, such as a pantiliner, pad, or sanitary napkin. However, this
depiction is not intended to
limit the invention. The absorbent article 10 has a longitudinal axis 100 and
a lateral axis 102 extending
along the length and width of the absorbent article. The absorbent article 10
has a first longitudinal end
12, a second longitudinal opposed end 14, and an intermediate region 16
located between the first
longitudinal end 12 and the second longitudinal end 14.
The absorbent article 10 comprises a top sheet 22, a back sheet 28, a fluid
transfer layer 24 and an
absorbent core 26 disposed between the top sheet 22 and the fluid transfer
layer 24. When the absorbent
article 10 is being worn, the top sheet 22 faces the wearer's body, and the
back sheet 28 faces away from
the wearer. The fluid transfer layer 24 is disposed underneath the top sheet
22. Preferably, the fluid
transfer layer 24 is provided in the vicinity of the target region.
FIG. 2 depicts a cross sectional view of the absorbent article 10 described in
FIG. 1. The
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absorbent article is provided with the top sheet 22, back sheet 28, absorbent
core 26, and the fluid transfer
layer 24. The fluid transfer layer is disposed underneath the top sheet 22,
and the absorbent core 26 is
disposed between at least a portion of the back sheet 28 and the fluid
transfer layer 24.
The top sheet 22 and back sheet 28 may be constructed from a wide variety of
materials known in
the art. The invention is not intended to be limited to any specific materials
for these components. The
top sheet 22 and back sheet 28 can be shaped and sized according to the
requirements of each of the
various types of absorbent articles, or to accommodate various user sizes. In
one of the configurations of
the invented absorbent article, such as a pantiliner or feminine hygiene
product, the top sheet 22, back
sheet 28, or both, may have an oval or rectangular shape. Alternatively, in
another configuration of the
invented absorbent article, such as a diaper or adult incontinence brief, the
top sheet 22, back sheet 28, or
both may have a rectangular, trapezoidal, "T" shape, or other shape.
The moisture-pervious top sheet 22 may be made of any suitable relatively
liquid-pervious
material currently known in the art or later discovered that permits passage
of a liquid there through.
Examples of suitable top sheet materials include non-woven spun-bonded or
carded webs of
polypropylene, polyethylene, nylon, polyester, and blends of these materials,
and the like. Non-woven
materials are exemplary because such materials readily allow the passage of
liquids to the underlying
absorbent core 26.
The top sheet 22 preferably comprises a single-ply non-woven material that may
be made of
carded fibers, either adhesively or thermally bonded, spun-bonded fibers, or
water entangled fibers, which
generally weigh from 0.3-0.7 oz./sq. yd. (10-24 gsm), and have appropriate and
effective machine
direction and cross-machine (transverse) direction strength suitable for use
as a top sheet material for the
given application. The present invention is not intended to be limited to any
particular material for the
top sheet 22, and other top sheet materials will be readily apparent to those
skilled in the art.
The top sheet 22 may further comprise several regions having different
properties. In one
embodiment of the present invention, the laterally distal portions of the top
sheet 22 are preferably
substantially fluid impervious and hydrophobic, while the remainder of the top
sheet 22 is hydrophilic
and fluid pervious. Different top sheet properties, such as fluid porosity and
hydrophobicity, may be
imparted upon the top sheet 22 by treating the top sheet 22 with adhesives,
surfactants, or other
chemicals, using a composite of different materials, or by other means.
Alternatively, the different
properties can be achieved by making the top sheet from three separate
components, i.e. a central, fluid
pervious portion, and two lateral fluid impervious portions that can also
serve to form standing leg
gathers. The top sheet 22 also may be treated in specific areas like the
crotch region, with skin weLlness
ingredients like aloe and vitamin E.
The back sheet 28 generally is made of any suitable pliable liquid impervious
material known in
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the art or later discovered. Typical back sheet materials include films of
polyethylene, polypropylene,
polyester, nylon, and polyvinyl chloride and blends of these materials. For
example, the back sheet 28
may be made of a polyethylene film having a thickness in the range of 0.02-
0.04 nun (0.8-1.2 mils). The
back sheet 28 may be pigmented with, for example, titanium dioxide, calcium
carbonate, and other white
pigments, to provide the absorbent article 10 with a pleasing color or to
render the back sheet 28 opaque
enough that exudates being contained by the absorbent article 10 are not
visible from outside the garment.
The backsheet 28 could also be tinted with different color pigments, such as,
for example, pink, blue,
peach, and other colors. In addition, back sheet 28 may be formed in such a
manner that it is opaque, for
example, by using various inert components in the polymeric film and then
biaxially stretching the film.
Other back sheet materials will be readily apparent to those skilled in the
art. The back sheet 28
preferably should have sufficient liquid imperviousness to prevent any leakage
of fluids through the back
sheet 28. The required level of liquid imperviousness may vary between
different locations on the
absorbent article 10.
The back sheet 28 may further comprise separate regions having different
properties. In a
preferred embodiment, portions of the back sheet 28 are air-permeable to
improve the breathability, and
therefore comfort, of the absorbent article 10. The different regions may be
formed by malcing the back
sheet 28 from a composite of different sheet materials, chemical treatment,
heat treatment, or other
processes or methods known in the art. Some regions of the back sheet 28 may
be fluid pervious. In one
embodiment of the invention, the back sheet 28 is fluid impervious in the
intermediate region 16, but is
fluid pervious in portions of the first and second longitudinal ends 12, 14.
The back sheet 28 may also be
made from a laminate of overlaid sheets of material.
In an embodiments described in FIG. 1, the top sheet 22 and back sheet 28 are
substantially
coterminous, or they may have different shapes and sizes. The particular
design of the top sheet and back
sheet may be dictated by manufacturing considerations, cost considerations,
and performance
considerations. Preferably, the top sheet 22 is large enough to completely
cover the absorbent core 26,
and the back sheet 28 is large enough to prevent leakage from the absorbent
article 10. The design of top
sheets 22 and back sheets 28 is known in the art, and a skilled artisan will
be able to produce an
appropriate top sheet 22 and an appropriate back sheet 28 without undue
experimentation, using the
guidelines provided herein.
The top sheet 22 and the back sheet 28 may be associated with one another
using a variety of
methods known in the art. For example, they may be thermally, ultrasonically,
chemically, or thermal
mechanically bonded to one another. They also may be joined using lines of hot
melt adhesive or
mechanical fasteners, such as thread, clips, or staples. In one embodiment, a
hydrophilic adhesive, such
as CYCLOFLEX (National Starch, Bridgewater, N.J.), is used to join the top
sheet 22 to the back sheet
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28. The particular joining method may be dictated by the types of materials
selected for the top sheet 22
and back sheet 28.
The absorbent core 26 preferably is disposed between the top sheet 22 and the
back sheet 28 in at
least the crotch region 16. The absorbent core 26 may extend into either or
both of the first and second
longitudinal ends 12, 14. Although the absorbent core 26 depicted in FIG. 1
has a substantially oval
shape, other shapes may be used, such as a "T" shape, an hourglass shape, or a
rectangular shape. The
shape of the absorbent core 26 may be selected to provide the greatest
absorbency with a reduced amount
of material. The size and capacity of the absorbent material may correspond to
the desired end use of the
absorbent article, for example, an incontinent brief for an adult may require
a larger absorbent core than a
diaper for a child. The absorbent core may be associated with the top sheet
22, back sheet 28, or any
other suitable part of the absorbent article 10 by any method known in the
art, in order to fix the absorbent
core 26 in place.
The absorbent core 26 of the present invention is suitably constructed from an
airlaid material.
Various types and sources of the airlaid materials are known to a person of
ordinary skill in the art. An
example of the airlaid material used to prepare the absorbent core of the
present invention is obtained
from the EAM Company. The present invention is not restricted to a particular
type of the airlaid
material.
Preferably, the absorbent core 26 further comprises a super absorbent polymer
distributed within
the airlaid material. The types of superabsorbent materials suitable for use
in the present invention are
known to those skilled in the art, and may be in any operative shape, form,
and size, such as particulates,
fibers, particles coated with fibers or other additives, or films, for
example. The superabsorbent material
can be a hydrogel-forming polymeric absorbent material which may be formed
from organic hydrogel-
forming polymeric materials, and may include natural material such as agar,
pectin, and guar gum;
modified natural materials such as carboxymethyl cellulose and other
biodegradable superabsorbent
materials, carboxyethyl cellulose, and hydroxypropyl cellulose; and synthetic
hydrogel-forming polymers.
Synthetic hydrogel-forming polymers include, for example, alkali metal salts
of polyacrylic acid,
polyacrylamides, polyvinyl alcohol, polyalkylene oxide, ethylene maleic
anhydride copolymers,
polyvinyl ethers, polyvinyl morpholinone, polymers, and copolymers of vinyl
sulfonic acid,
polyacrylates, polyacrylamides, polyvinyl pyridine, and the like. Other
suitable hydrogel-forming
polymers include hydrolyzed acrylonitrile grafted starch, acrylic acid grafted
starch, and hydrolyzed
isobutylene maleic anhydride copolymers and mixtures thereof. The hydrogel-
forming polymers are
preferably lightly cross linked to render the material substantially water
insoluble. Cross linking may, for
example, be by irradiation or covalent, ionic, Van der Waals, or hydrogen
bonding. Suitable materials are
available from various commercial vendors. One suitable superabsorbent
material for the present
CA 02593885 2014-04-01
invention is BASF-3900, available from BASF, a company having offices located
in Ludwigshafen,
Germany.
Other superabsorbent materials include multicomponent superabsorbent
particulate gels. One
such material is BASF E1231-99, also available from BASF. Multicomponent
superabsorbent gel
particles and methods to prepare them are described in the patent literature,
such as, for example, U. S.
Patent. Nos. 5,981,689; 6,072,101; 6,087,448; 6,121,409; 6,159,591; 6,194,631;
6,222,091; 6,235,965;
6,342,298; 6,376,072; 6,392,116; 6,509,512; and 6,555,502; U. S. Patent
Publications 2001/01312;
2001/07064; 2001/29358; 2001/44612; 2002/07166; 2002/15846; and 2003/14027;
and PCT Publications
WO 99/25393; WO 99/25745; WO 99/25748; WO 00/56959; WO 00/63295; WO 02/10032;
WO
03/18671; and WO 03/37392.
It is an important aspect of the present invention is that the absorbent core
26 is further provided
with a plurality of embossing patterns on its top surface. These patterns are
generally formed in
curvilinear shapes. By "curvilinear" is generally meant rounded shapes devoid
of any hard angles.
Embossing is performed, generally, minimally without affecting the fluff of
the core. It is usually
performed in lined patterns in which the embossed lines have high density and
the area enclosed by these
lines is slightly raised and is less dense. Usually the line pattern is chosen
in such a manner so as to form
an overall patterned design on the surface of the absorbent core. Embossing
improves the integrity of the
product.
FIG. 3 shows an absorbent article in which an absorbent core 26 is embossed
with diamond
pattern 40 on its top surface. However due to the presence of edges in
diamonds and other polygon
shapes, such as square, rectangle and trapezoid, etc., the surface of the
article is rigid and may cause
discomfort to the wearer. Furthermore the high-density region formed by these
lines creates a very
narrow depression in which the liquid can flow and collect, until the time it
is absorbed by the absorbent
core.
The absorbent article according to the present invention can solve this
problem by embossing the
absorbent core with a shape that does not have edges and corners, such as, a
circle, an oval, a clover
shape, a "club" shape, an undulation, or any combination thereof. The
embossing pattern in the absorbent
core of the present invention is used to maintain a sufficient flexural
resistance to avoid bunching of the
absorbent core or formation of lumps therein when worn, or for it to be
considered to be too flexible,
flabby, and flimsy by consumers.
Referring to FIG. 4, a top view of an embodiment of the absorbent article of
the invention is
shown. The absorbent article is provided with a top sheet (not shown), a back
sheet 28, an absorbent core
26, and a fluid transfer layer 24. In this embodiment, a circular embossing
pattern is applied on the top
11
CA 02593885 2007-07-16
surface of the absorbent core 26. The circular embossing pattern 30 punched
into the absorbent core 26
improves the extensibility and maintains sufficient flexural resistance of the
absorbent material into the
absorbent core. The circular shape allows an airlaid absorbent core to be soft
and comfortable to the
wearer. The circular embossing pattern is provided on the top surface of the
absorbent core.
The circular pattern 30 in the absorbent core 26 may be randomly arranged or
may be arranged in
a regular fashion throughout the surface. The circular patterns do not
intersect each other and are
considerably spaced apart from each other. This forms a line, or depression,
between two consecutive
high density periphery sections of any two circles. These lines, or
depressions, act as miniature reservoirs
that hold onto the liquid, until it is absorbed by the core. The circumference
of the circles and the
distance between them is dictated by the desired property of softness and
absorbency of the core.
Alternatively, the geometry of the embossing pattern may vary depending upon
the specific
desires of the wearer and the utility of the article. The embossing pattern
may either extend essentially
over the complete surface of the absorbent core or only selected sections
thereof: for instance, the central
area of the absorbent core or peripheral sections such as front and back
sections and/or side sections.
The embossing pattern of a shape such as an oval, curve, undulation or any
combination thereof
may be used in the absorbent core 26 of the absorbent article of the
invention. In another embodiment of
the invention, shown in FIG. 5, the absorbent core is embossed with an oval
shaped pattern. In addition,
it would also be possible to have a multi-lobed embossing pattern, as long as
the edges of such multi-
lobed design had circular or curved edges.
The absorbent core may also be made in such a way so as to take advantage of
the rigidity
provided by the polygonal pattern embossing and the softness provided by
curvilinear patterns. As shown
in FIG. 6, the central portion of the core has a circular pattern, whereas the
extremities have lines.
The embossing pattern in the absorbent core can be produced by various means
known to a
person of ordinary skill in the art, such as, heat or ultrasonic waves, and
thermal mechanical.
The invented absorbent core may be used in one or more configurations as
required when the
desired absorbent article is produced. In the preferred embodiment, shown in
FIG. 4, the absorbent article
of the invention includes a fluid transfer layer comprised of a three
dimensional aperture film. The fluid
transfer layer 24 preferably is disposed between the top sheet (not shown) and
the absorbent core 26. The
fluid transfer layer 24 preferably extends from the first longitudinal end 12,
through the intermediate
region 16, and into the second longitudinal end 14, and typically corresponds
substantially to the shape of
the absorbent core 26. The absorbent core 26 is placed on the back sheet 28 in
the crotch region of the
absorbent article. The majority of the central portion of the core is covered
by a three dimensional fluid
transfer layer 24. On top of this layer, a top sheet (not shown) is placed.
These layers are then joined
together so as to form a single piece article. This joining can be by using
embossing, adhesives or seams,
12
CA 02593885 2007-07-16
or any other suitable means or any combination thereof.
Alternatively, the fluid transfer layer may be provided with the same
longitudinal and lateral
dimensions of the absorbent core, or may be provided with smaller or narrower
dimensions than the
absorbent core. The fluid transfer layer 24 as shown in FIGS. 1, 2, 4, and 5,
has longitudinal a length and
lateral width of smaller size than the respective width and length of the
underlying absorbent core 26.
Preferably, the fluid transfer layer 24 covers the perineum area of the
absorbent core 26, and is primarily
disposed, for example, in the crotch region of the absorbent article.
In an alternate configuration, shown in FIG. 7, the fluid transfer layer 24
may be provided with a
longitudinal length which is co-terminus with the absorbent core 26 and a
lateral width which is smaller
as compared to the lateral width of the absorbent core.
The present invention also relates to a method of making an absorbent article
that includes
providing a top sheet material 22 and a back sheet material 28. The method
also includes preparing an
absorbent core 26 having a circular embossed pattern, and disposing the
absorbent core 26 between the
top sheet 22 and the back sheet 28. The method further includes preparing a
fluid transfer layer 24
comprising a three dimensional aperture film, and disposing the transfer layer
24 between the top sheet 22
and the absorbent core 26. The embodiments illustrated in FIGS. 3,5 and 7 can
be prepared in
accordance with the method of the invention simply by providing the fluid
transfer layer 24 of different
dimensions with respect to the dimension of the absorbent core 26.
The invention will be further illustrated by the following non-limiting
examples.
EXAMPLE
The absorbent article of the present invention exhibits improved absorbency
characteristics as
demonstrated by the following Examples and Tables.
Sample Preparation: The absorbent articles were prepared for testing in
accordance with the
following procedures.
The absorbency characteristics, strikethrough and rewet, of the invented
absorbent articles are
compared with the conventional absorbent articles by using the following test
procedure.
Testing Procedure
The apparatus that were used for rewet calculations included one 4" x 4"
Lucite cylinder block
with a 1" diameter opening was used to defme the area to be tested, a flat
plate weighing 0.05 kilograms
(4" x 4" x 1/8" Lucite square), a 2.2 kilogram weight, a 25 ml capacity
cylinder and a top loading
electronic balance, accurate 0.0 lg. In addition, we used dyed 1% saline
solution (refer to STM - 2000),
13
CA 02593885 2007-07-16
VWR Filter paper, Grade #417, 9 cm in diameter or equivalent.
The test procedure was as follows:
1. Prepare product for testing by placing flat on a level surface.
2. Center the cylinder block on the coversheet of the product.
3. Pour measured amount of 1% saline solution into the cylinder block opening.
4. Measure saline amounts by product type:
a. Pantyshields --2 ml;
b. Contour Pantiliners --2 ml;
c. Minipads 5 ml;
d. Light Incontinent --10 ml; and
e. All other sanitary items -- 10 ml.
5. Remove the cylinder block and allow product to stand for 5 minutes.
6. Weigh 10 filter papers and record weight.
7. After 5 minutes, simultaneously place the weighed filter paper, clear
Lucite plate, and 2.2
kilogram weight (approx. 0.5 psi) on the center of the product. Leave in this
position for
15 seconds.
8. Remove the weight and plate and weigh the filter papers.
Calculations were determined by initially weighing the filter paper in grams
before and after
liquid insult. In addition the average was reported.
Measuring Strikethrough and Rewet
The apparatus for determing strikethrough included a Burette clamp, 125 ml
separatory funnel,
Ring stand or equivalent, large beaker or bottle, at least 1 00m1 and a strike-
through plate (Absorbency
Rate Tester) 4" x 4" weight ¨ 7.81bs. In addition, a 1% Saline (STM 2000), a
stopwatch, Ahlstrom filter
papers, 2" x 4" (md x cd), stanley knife or scissors and a 4.4 lb rectangular
weight (2" x 4 "). Weight =
0.5psi.
The procedure was as follows:
1. Disassemble pad by cutting the front and back of pad.
2. Cut the pads by cutting the elastic strands (ie.Lycra) on both sides.
3. Remove top sheet and / or sublayer and replace with experimental materials.
4. Tape pad onto table with tape and stretch to make flat.
5. Place absorbency rate tester over center of product at the predicted insult
area.
14
CA 02593885 2014-04-01
6. Slide separatory funnel over center of product, so that hole in strike
through
plate is centered under funnel tip.
7. Make sure stopcock on separatory funnel is closed and stopwatch is zeroed.
8. Dispense solution from plastic beaker on to the separatory funnel.
9. The solution amounts were as follows:
a. Shields 30m1 1% saline solution
= b. Guards 30m1 1% saline solution
c. Bladder Control Pads 30m1 1% saline solution
d. Light Bladder Control Pads 10m1 1% saline solution
10. Open stopcock of separatory funnel, dispense the fluid into strike-
through plate, and start stopwatch. Take care to always open the stopcock in
the
= same direction.
11. Close stopcock.
12. Watch through transparent cylinder until fluid flows past strike-
through plate.
13. Record result to the nearest 0.01 seconds.
14. Remove absorbency rate tester and let product sit for 10 minutes.
15. Weigh 10 filter papers and record weight on filter papers.
16. After 10 minutes, place weighed filter papers and the 2.21b weight in
center of
insult area Let weight remain for 2 minutes.
17. Remove weight and filter papers. Reweigh filter papers and subtract dry
weight of
filter papers to calculate rewet.
18. Repeat 5 through 17 two more times, for a total of three insults.
The calculations were conducted by weighing the filter paper before an after
insult in grams.
Absorbency rate was measured in seconds (sec) and Rewet value in grams (g).
The experimental protocol for measuring strikethrough and rewet properties are
known to a
person of ordinary skill in the art and has been additionally described in
various patent publications, such
as, U. S. Patent No. 6,852,905 and U.S. Patent No. 6,610,391.
Table 1 below summarizes the results obtained through above test procedures on
several
examples of the article of the present invention and control absorbent
articles.
CA 02593885 2007-07-16
Table 1
Dry Wet Total Thickn
Pr. Pr. Capa ess
Strikethrough Rewet
Wt. Wt. (gm) (mm)
(gm) (gm)
1st 2 3'd
Middl 1st 2" 3rd
Rate Rate Rate
Rewet Rewet Rewet
(sec) (sec) (sec)
S 1 4.30 2.48 37.06 69.13
100.88 0.04 0.06 0.36
tia 2 4.30 2.48 33.66 55.25
78.68 0.04 0.05 0.31
g 3 4.19 2.50 31.37 54.53
92.32 0.05 0.06 0.17
E
4 4.25 2.46 35.09 63.66
84.69 0.04 0.06 0.56
7 5 4.41 2.50 34.75 55.78
73.62 0.06 0.05 0.16
C) Avg. 4.29 2.48 34.39 59.67
86.04 0.05 0.06 0.31
Std 0.08 0.02 2.09 6.45 10.84
0.01 0.01 0.16
rt 2" 3"
111 2" 3"I
Middle Rate Rate Rate
Rewet Rewet Rewet
(sec) (sec) (sec)
.E.1 1 4.58 2.44 27.08 48.43
72.37 0.06 0.06 1.83
2 4.49 2.40 30.53 47.31 72.75 0.04 0.07 2.25
^i 3 4.57
2.46 32.25 52.71 80.15 0.05 0.11 3.24
.0 4 4.50 2.43 33.65 53.92
90.85 0.04 0.12 2.72
4.)
4.56 2.44 30.32 49.97 70.65
0.04 0.08 2.23
0.4
Avg. 4.54 2.43 30.99 50.43
80.96 0.05 0.09 2.45
Std 0.04 0.03 2.65 2.77 9.13
0.01 0.03 0.54
16
CA 02593885 2014-04-01
Various other embodiments are possible, and the aforementioned examples and
embodiments
are simply meant to be for explanatory purposes, and are not intended to limit
the invention in any
manner. The articles of the invention may be made from various kinds of
materials available in the
field and known to a person skilled in the art. The embossing may be done
using various techniques
prevalent in the field.
=
17
