U.S. patent application number 13/755772 was filed with the patent office on 2013-06-06 for extensible absorbent layer and absorbent article.
This patent application is currently assigned to Kimberly-Clark Worldwide, Inc.. The applicant listed for this patent is Kimberly-Clark Worldwide, Inc.. Invention is credited to Franz Aschenbrenner, Maria Raidel, Jan Ullmann.
Application Number | 20130139666 13/755772 |
Document ID | / |
Family ID | 37946273 |
Filed Date | 2013-06-06 |
United States Patent
Application |
20130139666 |
Kind Code |
A1 |
Raidel; Maria ; et
al. |
June 6, 2013 |
Extensible Absorbent Layer And Absorbent Article
Abstract
The present invention provides a method of preparing an
absorbent layer from an absorbent nonwoven web having a first
plurality of slits with a first orientation and a second plurality
of slits with a second orientation, wherein the first orientation
is different from the second orientation. The first plurality of
slits and the second plurality of slits are at least partially
through the absorbent nonwoven web, and the second plurality of
slits at least partially intersects the first plurality to form
apertures in the absorbent nonwoven web.
Inventors: |
Raidel; Maria; (Fuerth,
DE) ; Aschenbrenner; Franz; (Kastl, DE) ;
Ullmann; Jan; (Nuernberg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kimberly-Clark Worldwide, Inc.; |
Neenah |
WI |
US |
|
|
Assignee: |
Kimberly-Clark Worldwide,
Inc.
Neenah
WI
|
Family ID: |
37946273 |
Appl. No.: |
13/755772 |
Filed: |
January 31, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12696637 |
Jan 29, 2010 |
8387497 |
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13755772 |
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11302719 |
Dec 14, 2005 |
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12696637 |
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Current U.S.
Class: |
83/300 |
Current CPC
Class: |
Y10T 83/4696 20150401;
B26F 1/44 20130101; B26F 1/22 20130101; B26F 1/14 20130101; Y10T
83/0481 20150401; A61F 13/512 20130101; A61F 13/15707 20130101;
Y10T 83/889 20150401; Y10T 83/04 20150401; A61F 13/15723 20130101;
B26F 1/20 20130101; B26F 2001/4481 20130101; A61F 13/53
20130101 |
Class at
Publication: |
83/300 |
International
Class: |
A61F 13/15 20060101
A61F013/15 |
Claims
1. An apparatus for aperturing a web comprising an anvil roll, a
first cutting roll and a second cutting roll, wherein the first
cutting and second cutting rolls are in communication with the
anvil roll, each cutting roll comprises a series of protrusions
that are capable of forming slits in a web passed between the anvil
and each cutting roll; at least some of the protrusions of the
first cutting roll and some of the protrusions of the second
cutting roll are aligned on the anvil such that at least a portion
of slits cut in the first cutting roll overlap at least a portion
of the slits cut by the second cutting roll, and where the slits
overlap one another the area of said web between the overlapping
slits is cut free from the web, thereby forming at least one
aperture in the web.
2. The apparatus according to claim 1 further comprising at least
one additional cutting roll, wherein the additional cutting rolls
are in communication with the anvil roll and has a series of
protrusions that are capable of forming slits in a web passed
between the anvil and each cutting roll.
3. The apparatus according to claim 1 wherein the first cutting
roll has a series of protrusions which are non-linear and the first
plurality of slits are non-linear.
4. The apparatus according to claim 1 wherein the second cutting
roll has a series of protrusions which are non-linear and the
second plurality of slits are non-linear.
5. The apparatus according to claim 1 wherein the first cutting
roll and the second cutting roll are driven in unison with the
anvil roll.
Description
RELATED APPLICATION
[0001] This application is a continuation of Ser. No. 12/696,637,
entitled "Extensible Absorbent Layer And Absorbent Article" and
filed in the U.S. Patent and Trademark Office on Jan. 29, 2010
which is a divisional of application Ser. No. 11/302,719, entitled
"Extensible Absorbent Layer and Absorbent Article" and filed in the
U.S. Patent and Trademark Office on Dec. 14, 2005.
FIELD OF THE INVENTION
[0002] The present invention relates to disposable absorbent
articles such as sanitary napkins, pantiliners or incontinence pads
and absorbent layers used therein. The present invention further
relates to a process of manufacturing an absorbent layer or
absorbent article.
BACKGROUND OF THE INVENTION
[0003] Disposable absorbent articles, such as sanitary napkins worn
by women, must fulfill numerous requirements in order to be
considered satisfactory for use. From the standpoint of the
consumer using the disposable absorbent article, efficient
absorption and retention of liquid and other discharges from the
human body must be provided, and possible soiling of the wearer's
body or the wearer's garment should be avoided. In addition, the
absorbent article should be comfortable for a user to wear. The
absorbent article should therefore be able to individually conform
to the shape of the wearer's body, so that the wearer is not
hindered by the absorbent article. Ideally, the absorbent article
should not be perceived by the wearer at all when worn. On the
other hand, the absorbent article should not be too soft and
deformable, otherwise bunching, twisting or roping of the absorbent
article or lumping of the absorbent layer may occur, when the
article is worn. This would seriously deteriorate the performance
of the absorbent article and influence negatively the wearing
comfort. Furthermore, the absorbent article and especially the
absorbent layer must have sufficient structural integrity to
withstand the forces exerted onto the absorbent article when worn.
At the same time, the absorbent article should be thin so that the
absorbent article may be worn in an inconspicuous manner. From the
manufacturer's point of view, the materials used to produce the
absorbent article must be suitable for mass production at very high
production rates. The materials used to produce the absorbent
article must therefore be easily obtained and be of relatively low
cost. Furthermore, the materials must be easily processed at high
speeds, which often include considerable forces and tensions being
applied to the material, especially in the machine direction.
[0004] In order to increase the wearing comfort of sanitary napkins
it has been suggested in the art to provide these articles with
stretchability or increased flexibility. One method suggested in
the art is to provide slits in the materials used to form the
absorbent article. Excessive extensibility of an absorbent layer in
the longitudinal direction, which is generally the machine
direction, will make it very difficult to prepare such an absorbent
layer on a production line designed for very high production rates
(high speeds). Furthermore, for the absorbent article to be able to
conform to the body of the wearer, the absorbent layer should be
sufficiently extensible in both the longitudinal and lateral
direction, while maintaining sufficient strength in both
directions. At the same time, care must be taken not to
significantly reduce the flexural resistance of the absorbent
article. If the flexural resistance is reduced too much, the
absorbent article will bunch, twist or rope or form lumps when the
article is worn. Additionally, the articles might not be accepted
by the consumer if the absorbent article feels too flexible, i.e.
flimsy or flabby, thereby creating the impression that the article
will not provide sufficient protection against the soiling of the
garment to be protected. Furthermore, care should be taken that the
formation of slits in the absorbent layer does not impair the
efficiency of liquid intake, liquid distribution and liquid
retention, due to the quick passage of liquid through the absorbent
layer via the cuts or apertures formed therein.
[0005] A current trend in feminine hygiene products is to provide
these products with aesthetic features such as colors, apertures
and embossing to provide the consumer with a sense that the
feminine hygiene products will be effective in absorbing bodily
fluids. Color can be used to show the consumer or user that the
product has new features, absorbency, and leakage protection.
[0006] There is a need in the art to provide an absorbent article
which is extensible and highly conformable to the body of the
wearer, while at the same time maintaining sufficient structural
strength to avoid bunching, twisting or roping and the formation of
lumps. In addition, there is a need in the art to make efficient
usage of the absorbent capacity of the absorbent layer, and having
the ability to produce the absorbent layer at high production rates
(high speeds) at relatively reasonable or low cost. In addition,
there is a need to provide additional color or features to
absorbent products and to provide a way to convey these additional
features to the consumer or user of these products.
SUMMARY OF THE INVENTION
[0007] The present invention provides an absorbent article which is
extensible and highly conformable to the body of the wearer.
Furthermore, the present invention provides an extensible and
highly conformable absorbent layer for an absorbent article which
efficiently utilizes the absorbent capacity of the absorbent layer.
The present invention solves the above outlined problems by
providing an absorbent article, an absorbent layer for use in an
absorbent article, and a process for manufacturing the absorbent
layer. Further embodiments and features of the different aspects of
the present invention become apparent in the detailed description
and the figures appended thereto.
[0008] The absorbent article of the present invention has a
longitudinal direction and a lateral direction. In addition, the
absorbent article has a top layer, a backing layer, and an
absorbent layer positioned between the top layer and the backing
layer. The absorbent layer is prepared from an absorbent nonwoven
web having a first plurality of slits with a first orientation and
a second plurality of slits with a second orientation, wherein the
first orientation is different from the second orientation. The
first plurality of slits and the second plurality of slits are at
least partially through the absorbent nonwoven web, and the second
plurality of slits at least partially intersects the first
plurality of slits in a manner such that where the first and second
plurality of slits intersect the first and second plurality of
slits combine to form apertures in the absorbent nonwoven web. The
first plurality of slits may be non-linear and the second plurality
of slits may also be non-linear.
[0009] In further embodiments of the present invention, the top
layer of the absorbent article may be a liquid-permeable material
and the bottom layer may be a liquid-impermeable material. In
addition, the basis weight of the absorbent nonwoven web may be
between about 20 g/m.sup.2 and 1000 g/m.sup.2. Further, the basis
weight of the absorbent nonwoven web may be between about 50
g/m.sup.2 and 500 g/m.sup.2 and generally between about 70
g/m.sup.2 and 250 g/m.sup.2.
[0010] In yet a further embodiment of the present invention, the
first plurality of slits may be non-linear. Likewise, the second
plurality of slits may also be non-linear. Each non-linear slit has
an effective length in longitudinal direction in the range between
about 2 mm and about 20 mm and an effective length in lateral
direction in the range between about 0.5 mm and about 10 mm.
[0011] In another embodiment of the present invention, provided is
an absorbent nonwoven web having a first plurality of slits with a
first orientation and a second plurality of slits with a second
orientation, wherein the first orientation is different from the
second orientation. The first plurality of slits and the second
plurality of slits are at least partially through the absorbent
nonwoven web, and the second plurality of slits at least partially
intersects the first plurality of slits in a manner such that where
the first and second plurality of slits intersect the first and
second plurality of slits combine to form apertures in the
absorbent nonwoven web.
[0012] In another embodiment of the present invention, provided is
a process for preparing a web, in particular the absorbent nonwoven
web of the absorbent layer of the present invention. In this
embodiment, the process has the steps of a) providing a web; b)
providing a slitting apparatus having anvil roll, a first cutting
roll and a second cutting roll; c) passing the web between the
first cutting roll and the anvil to form a first plurality of slits
in the absorbent nonwoven web; and d) passing the web between the
second cutting roll and the anvil to form a second plurality of
slits in the absorbent nonwoven web, wherein at least one slit in
the second plurality of slits intersects at least one slit from the
first plurality of slits such that an aperture is formed in the
web. In the process of the present invention, both the first and
second cutting rolls are positioned adjacent the same anvil roll.
That is, the first cutting roll and the second cutting roll place
slits in the absorbent nonwoven web against the same anvil roll.
The absorbent nonwoven web of the present invention is brought into
contact with the anvil roll, cut with the first cutting roll. Once
cut or slitted with the first cutting roll, the web remains in
contact with the anvil roll and is cut or slit with the second
cutting roll. The first and second cutting rolls may be run in
unison to register the first and second slits cut into the web.
[0013] In another embodiment of the present invention, provided is
an apparatus for aperturing a web. The apparatus has an anvil roll,
a first cutting roll and a second cutting roll, wherein the first
cutting and second cutting rolls are in communication with the
anvil roll. Each cutting roll has a series of protrusions that are
capable of forming slits in a web passed between the anvil and each
cutting roll. At least some of the protrusions of the first cutting
roll and some of the protrusions of the second cutting roll are
aligned on the anvil such that at least a portion of slits cut by
the first cutting roll overlap at least a portion of the slits cut
by the second cutting roll in the area where the slits overlap one
another. In a further embodiment of the apparatus of the present
invention, there may be at least one additional cutting roll in
communication with the anvil. Each additional cutting roll has a
series of protrusions that are capable of forming slits in a web
passed between the anvil and each cutting roll. Each cutting roll
may be run in unison with the anvil roll.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is an exploded view of a first embodiment of an
absorbent article according to the present invention.
[0015] FIG. 2 is an exploded view of a second embodiment of an
absorbent article according to the present invention.
[0016] FIGS. 3A-F show possible arrangements for a plurality of
slits in a pattern or orientation.
[0017] FIG. 4 shows an absorbent layer of the present invention
with slits in a first orientation and slits in a second orientation
that combine to form apertures.
[0018] FIG. 5 shows an absorbent layer of the present invention
with slits in a first orientation and slits in a second orientation
that combine to form apertures.
[0019] FIGS. 6A and 6B show a configuration of three slits which
combine to form an aperture.
[0020] FIG. 7 shows a schematic representation of a section of a
pattern of slits usable in the absorbent layer.
[0021] FIG. 8A shows a schematic representation of an apparatus of
the present invention with two slitting rolls
[0022] FIG. 8B shows a schematic representation of an apparatus of
the present invention with more than two slitting rolls.
[0023] FIG. 9A shows a slitting roll usable in the process of the
present invention.
[0024] FIG. 9B shows a magnified view of the encircled region of
the slitting roll of FIG. 9A.
[0025] FIG. 10 shows a schematic representation of selected steps
of the process for forming an absorbent article according to the
present invention.
DEFINITIONS
[0026] As used herein with reference to the present invention, the
term "disposable" includes being disposed after use and not
intended to be washed and reused.
[0027] As used herein with reference to the present invention, the
term "layer" when used in the singular can have the dual meaning of
a single element or a plurality of elements.
[0028] As used herein with reference to the present invention, the
term "liquid" means a non-particulate substance and/or material
that flows and can assume the interior shape of a container into
which it is poured or placed.
[0029] As used herein with reference to the present invention, the
term "longitudinal" means having the longitudinal axis in the plane
of the article and is generally parallel to a vertical plane that
bisects a standing wearer into left and right body halves when the
article is worn. The "lateral" axis lies in the plane of the
article generally perpendicular to the longitudinal axis, i.e., so
that a vertical plane bisects a standing wearer into front and back
body halves when the article is worn.
[0030] As used herein, the term "machine direction" or "MD" means
the length of a fabric in the direction in which it is produced.
This direction as a rule essentially corresponds to the above
defined longitudinal direction.
[0031] The term "cross machine direction", "cross direction" or
"CD" means the width of fabric, i.e. a direction generally
perpendicular to the MD. In line with the above definitions, the
cross machine direction as a rule essentially corresponds with the
lateral direction of the absorbent layer.
[0032] As used herein with reference to the present invention, the
term "conjugate fibers" refers to fibers that have been formed from
at least two polymers extruded from separate extruders but spun
together to form one fiber. Conjugate fibers are also sometimes
referred to as multicomponent or bicomponent fibers. The polymers
are usually different from each other though conjugate fibers may
be monocomponent fibers. The polymers are arranged in substantially
constantly positioned distinct zones across the cross-section of
the conjugate fibers and extend continuously along the length of
the conjugate fibers. The configuration of such a conjugate fiber
may be, for example, a sheath/core arrangement wherein one polymer
is surrounded by another or may be a side by side arrangement, a
pie arrangement or an "islands-in-the-sea" arrangement. Conjugate
fibers are taught in U.S. Pat. No. 5,108,820 to Kaneko et al., U.S.
Pat. No. 5,336,552 to Strack et al., and U.S. Pat. No. 5,382,400 to
Pike et al., each of which is hereby incorporated by reference. For
two component fibers, the polymers may be present in ratios of
75/25, 50/50, 25/75 or any other desired ratios. The fibers may
also have shapes such as those described in U.S. Pat. No. 5,277,976
to Hogle et al., and U.S. Pat. Nos. 5,069,970 and 5,057,368 to
Largman et al., each of which is hereby incorporated by reference,
hereby incorporated by reference in their entirety, which describe
fibers with unconventional shapes.
[0033] As used herein with reference to the present invention, the
term "biconstituent fibers" refers to fibers that have been formed
from at least two polymers extruded from the same extruder as a
blend. Biconstituent fibers do not have the various polymer
components arranged in relatively constantly positioned distinct
zones across the cross-sectional area of the fiber and the various
polymers are usually not continuous along the entire length of the
fiber, instead usually forming fibrils or protofibrils which start
and end at random. Biconstituent fibers are sometimes also referred
to as multiconstituent fibers. Fibers of this general type are
discussed in, for example, U.S. Pat. No. 5,108,827 to Gessner,
which is hereby incorporated by reference. Bicomponent and
biconstituent fibers are also discussed in the textbook Polymer
Blends and Composites by John A. Manson and Leslie H. Sperling,
copyright 1976 by Plenum Press, a division of Plenum Publishing
Corporation of New York, IBSN 0-306-30831-2, at pages 273 through
277.
[0034] As used herein with reference to the present invention, the
term "spunbonded fibers" refers to small diameter fibers which are
formed by extruding molten thermoplastic material as filaments from
a plurality of fine, usually circular capillaries of a spinneret
with the diameter of the extruded filaments then being rapidly
reduced as by, for example, in U.S. Pat. No. 4,340,563 to Appel et
al., and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No.
3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394
to Kinney, U.S. Pat. No. 3,502,763 to Hartman, and U.S. Pat. No.
3,542,615 to Dobo et al, each of which is hereby incorporated by
reference Spunbond fibers are generally not tacky when they are
deposited onto a collecting surface. Spunbond fibers are generally
continuous and have average diameters (from a sample of at least
10) larger than 7 microns, more particularly, between about 10 and
35 microns. The fibers may also have shapes such as those described
in U.S. Pat. No. 5,277,976 to Hogle et al., U.S. Pat. No. 5,466,410
to Hills and U.S. Pat. Nos. 5,069,970 and 5,057,368 to Largman et
al., each of which is hereby incorporated by reference and describe
fibers with unconventional shapes.
[0035] As used herein with reference to the present invention, the
term "meltblown fibers" means fibers formed by extruding a molten
thermoplastic material through a plurality of fine, usually
circular, die capillaries as molten threads or filaments into
converging high velocity, usually hot, gas (e.g. air) streams which
attenuate the filaments of molten thermoplastic material to reduce
their diameter, which may be to microfiber diameter. Thereafter,
the meltblown fibers are carried by the high velocity gas stream
and are deposited on a collecting surface to form a web of randomly
dispersed meltblown fibers. Such a process is disclosed, for
example, in U.S. Pat. No. 3,849,241 to Butin et al, which is hereby
incorporated by reference. Meltblown fibers are microfibers that
may be continuous or discontinuous, are generally smaller than 10
microns in average diameter, and are generally tacky when deposited
onto a collecting surface.
[0036] "Airlaying" is a known process by which a fibrous nonwoven
layer can be formed. In the airlaying process, bundles of small
fibers having typical lengths ranging from about 3 to about 52
millimeters are separated and entrained in an air supply and then
deposited onto a forming screen, usually with the assistance of a
vacuum supply. The randomly deposited fibers then are bonded to one
another using, for example, hot air, a spray adhesive, or a binder.
Examples of airlaying technology can be found in U.S. Pat. Nos.
4,494,278 to Kroyer; 5,527,171 to Soerensen; and 4,640,810 to
Laursen, each of which is hereby incorporated by reference. The
term "airlaid fiber layer" as used herein with reference to the
present invention relates to layers obtained by means of an
airlaying process.
[0037] As used herein with reference to the present invention, the
term "coform" means a process in which at least one meltblown die
head is arranged near a chute through which other materials are
added to the web while it is forming. Such other materials may be
pulp, superabsorbent or other particles, natural polymers (for
example, rayon or cotton fibers) and/or synthetic polymers (for
example, polypropylene or polyester) fibers, for example, where the
fibers may be of staple length. Coform processes are shown in
commonly assigned U.S. Pat. No. 4,818,464 to Lau and U.S. Pat. No.
4,100,324 to Anderson et al. each of which is hereby incorporated
by reference. Webs produced by the coform process are generally
referred to as coform materials.
[0038] "Carded web" refers to webs that are made from staple fibers
that are sent through a combing or carding unit, which opens and
aligns the staple fibers in the machine direction to form a
generally machine direction-oriented fibrous nonwoven web. The web
is then bonded by one or more of several known bonding methods.
Bonding of nonwoven webs may be achieved by a number of methods;
powder bonding, wherein a powdered adhesive or a binder is
distributed through the web and then activated, usually by heating
the web and adhesive with hot air; pattern bonding, wherein heated
calendar rolls or ultrasonic bonding equipment are used to bond the
fibers together, usually in a localized bond pattern, though the
web can be bonded across its entire surface if so desired;
through-air bonding, wherein air which is sufficiently hot to
soften at least one component of the web is directed through the
web; chemical bonding using, for example, latex adhesives that are
deposited onto the web by, for example, spraying; and consolidation
by mechanical methods such as needling and hydroentanglement.
[0039] "Superabsorbent" refers to a water-swellable,
water-insoluble organic or inorganic material capable, under the
most favorable conditions, of absorbing at least about 10 times its
weight and, more desirably, at least about 15 times its weight in
an aqueous solution containing 0.9 weight percent sodium chloride.
The superabsorbent materials can be natural, synthetic, and
modified natural polymers and materials. In addition, the
superabsorbent materials can be inorganic materials, such as silica
gels, or organic compounds such as cross-linked polymers. A
material is "absorbent" if it absorbs at least five times its
weight of the aqueous solution under these conditions.
[0040] "Personal care product" means diapers, training pants,
absorbent underpants, adult incontinence products, swim wear,
bandages and other wound dressings, and feminine hygiene
products.
[0041] "Feminine hygiene products" means sanitary napkins, pads,
and pantiliners.
[0042] "Target area" refers to the area or position on a personal
care product where an insult is normally delivered by a wearer.
DETAILED DESCRIPTION OF THE INVENTION
[0043] In the following the present invention will be described
especially with reference to sanitary napkins but is not limited to
sanitary napkins. It is also applicable to other absorbent articles
such as personal care products, including diapers, incontinence
pads, pantiliners, disposable swimwear, training pants and the
like.
[0044] FIG. 1 and FIG. 2 show two embodiments of the absorbent
article 10 according to the present invention. It is to be
understood within the present application that all figures show
selected embodiments comprising one or more aspects of the present
invention and that the embodiments shown in these figures are
non-limiting embodiments by means of which selected properties or
selected components or features of the absorbent articles are
demonstrated. The absorbent article according to the present
invention has a longitudinal direction, corresponding to the
machine direction MD, and a lateral direction, corresponding to the
cross machine direction CD. The cross machine direction is
perpendicular to the machine direction. The absorbent articles 10
comprise a top layer 12, wherein the top layer 12 may optionally
have extensibility in lateral direction of at least 30% to 70% at
4N/50 mm. The tensile strength of the top layer material can be
determined following the procedures outlined in the tensile test on
strips of textile fabrics of DIN 53 857 on a strip of material
having a width of 50 mm and measured without a pre-load force. The
top layer 12 is the layer facing the wearer's body when the
absorbent article is in use. Desirably, the top layer 12 is a
liquid permeable material. The top layer 12 can be made of a
material that permits the passage of fluid without drawing the
fluid horizontally in parallel to the top layer to any great
extent. In addition, the top layer should retain little or no fluid
in the structure, so that a relatively dry surface is provided next
to the wearer's skin. In general, the top layer is a single layer
of a material with a width sufficient to cover the surface of an
absorbent layer positioned underneath it. The top layer 12
preferably extends to the longitudinal edges of the absorbent
article and is bonded to a backing layer 30. The top layer 12 may
be bonded to the backing layer 30 using any known method which does
not leave any hard or uncomfortable residues that would annoy the
wearer. Those skilled in the art are familiar with methods of
bonding the various materials and for bonding other possible
materials in the absorbent article according to the present
invention, including the use of pressure-sensitive adhesives,
hot-melt adhesives, two-sided adhesive sheets, ultrasonic welding
and heat sealing, to name but a few. Adhesives such as hot-melt
adhesives may be used uniformly or in the form of a continuous or
non-continuous layer.
[0045] The top layer 12 may be manufactured from materials known in
the art. Known materials include, for example, card weaves and
spunbonded nonwovens made of polyester, polypropylenes,
polyethylenes, nylon or other heat-bonded fibers. Other polyolefins
such as copolymers of polypropylene and polyethylene, linear,
low-density polyethylene fiber nonwovens which are finely
perforated or mesh-like materials are also suitable. Other suitable
materials include composite materials of polymers and nonwoven
material. The composite layers are usually formed by extrusion of
the polymer on a layer of spunbonded nonwoven to form an integral
layer. These materials may contain pigments, such as titanium
dioxide to improve the masking properties of the top layer 12 or
other additives to improve the properties of the material, like
substances improving the hydrophilic properties of the top layer,
e.g. surfactants.
[0046] In a non-limiting embodiment of the absorbent article
according to the present invention, the top layer 12 is made of a
carded nonwoven web made of polypropylene fibers, which generally
has a basis weight of from about 18 to about 40 g/m.sup.2. In a
specific embodiment, the basis weight is 27 g/m.sup.2.
Alternatively, the top layer 12 may be made of a spunbonded
nonwoven made of polypropylene fibers and generally having a basis
weight of from about 18 to about 40 g/m.sup.2. Top layer 12 may
comprise a multitude of perforations 14, which may be oval shaped,
square shaped or circular shaped, or of any other suitable shape,
in order to facilitate the uptake of liquid through the top layer,
especially highly viscous components of such a liquid. The top
layer may be completely perforated or may only be perforated in
selected areas thereof. In the specific embodiment shown in FIG. 1,
the perforations are formed throughout the surface of the top layer
12. In the embodiment shown in FIG. 2, the perforations 14 are only
situated in the central area of the top layer 12, corresponding to
the target area of the absorbent article. Generally, the
perforations 14 could also be present within a central strip
extending along the complete length of the absorbent article or
uniformly distributed over the whole area of the top layer 12. The
perforations may be arranged randomly or regularly in a
pattern.
[0047] Alternatively, the liquid-permeable top layer 12 may also
consist of a perforated film made from a liquid-impermeable
material, such as polyethylene or polypropylene.
[0048] The top layer 12 may further comprise embossing lines 11, as
shown in FIG. 2, for adapting the shape of the absorbent article to
the shape of the wearer's body and to improve its conformability to
the body of the wearer. Such embossing lines 11 can be formed using
conventional techniques. If embossing lines 11 are present in the
top layer 12, the underlying absorbent layer 16 will usually also
comprise corresponding embossing lines because such embossing lines
are usually formed in a single embossing step during the
manufacturing of the absorbent article.
[0049] The absorbent articles 10 shown in FIGS. 1 and 2 further
comprise a backing layer 30 laminated to the top layer 12, wherein
the backing layer 30 may have a higher extensibility in lateral
direction than in longitudinal direction. The extensibility in
lateral direction may have a value of between at least 5% and 40%
at 4N/50 mm as determined following the procedures of the tensile
test on strips of textile fabrics outlined in DIN 53 857 on a strip
of material having a width of 50 mm and measuring without a
pre-load force. In an embodiment of the present invention, the
backing layer is prepared from a liquid-impermeable material. The
backing layer 30 may be made of any suitable material that is
sufficiently liquid-impermeable and exhibits the required
extensibility. The backing layer may for instance consist of a
polymeric film having the desired extensibility. The backing layer
30 may allow atmospheric vapor and moisture to pass through the
absorbent article while preventing body fluid from passing through.
Suitable extensible materials are for instance mentioned in U.S.
Pat. No. 4,166,464 to Korpman, the disclosure of which is fully
incorporated herewith. Suitable polymer materials for use as the
backing layer are, for instance, Kraton 1107, a thermoplastic
elastomeric A-B-A (styrene-isoprene-styrene, S-I-S) copolymer or
Solprene 420, which is also a S-I-S copolymer or mixtures thereof.
Furthermore, a layer made of different types of polyethylene having
different densities may be used. Additionally, microembossed
polyethylene or polypropylene films or films of polyolefin foams
may be used. The backing layer may also be a layer which may be
prepared from a mixture of polyethylenes having different
densities. In an alternative embodiment of the present invention,
the backing layer may be liquid permeable, if the absorbent article
is used in conjunction with another liquid impermeable material,
such as, liquid impermeable pants.
[0050] Both the top layer 12 and the backing layer 30 may comprise
wing sections (not shown) located at the longitudinal sides of the
absorbent article. Such wing sections are commonly used in the art
for attachment of sanitary napkins to the wearer's undergarment.
Wings or flaps are known in the art and are described in U.S. Pat.
No. 4,589,876 to Van Tilburg, which is hereby incorporated by
reference. Flaps are also shown in other patents, for example, U.S.
Pat. No. 6,387,084 issued to VanGompel et al., which is hereby
incorporated by reference for its discussion of the flaps and flap
attachment means and in its entirety. In one embodiment (not
shown), one or more elastic elements are disposed along the sides
to form a gasket with the body of the user. Elastic sides are known
in the art, as is shown in U.S. Pat. No. 6,315,765 issued to Datta
et al., which is hereby incorporated by reference for its
discussion of the elastic sides and in its entirety. In one
embodiment, the elastic elements are disposed between the top layer
and the backing layer.
[0051] The absorbent articles according to the present invention
further have an absorbent layer 16 positioned between the top layer
12 and the backing layer 30. The absorbent layer 16 is generally
made of one or more materials which together are essentially
absorbent, hydrophilic, compressible, adaptable and non-irritating
for the skin of the wearer. Suitable materials are well known in
the art and include, for example, various natural or synthetic
fibers, cellulose fibers, regenerated cellulose or cotton fibers or
a blend of cellulose and other fibers or polyethylene or
polypropylene fibers, or biconstituent fibers. In a specific
embodiment, polypropylene fibers may be used.
[0052] The absorbent structure 16 may also include superabsorbent
material. Superabsorbent materials suitable for use in the present
invention are known to those skilled in the art, and may be in any
operative form, such as particulate form, fibers and mixtures
thereof. Generally stated, the superabsorbent material can be a
water-swellable, generally water-insoluble, hydrogel-forming
polymeric absorbent material, which is capable of absorbing at
least about 15, suitably about 30, and possibly about 60 times or
more its weight in physiological saline (e.g. saline with 0.9 wt %
NaCl). The superabsorbent material may be biodegradable or bipolar.
The hydrogel-forming polymeric absorbent material may be formed
from organic hydrogel-forming polymeric material, which may include
natural material such as agar, pectin, and guar gum; modified
natural materials such as carboxymethyl cellulose, 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, 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 isobutylene maleic anhydride copolymers
and mixtures thereof. The hydrogel-forming polymers may be lightly
crosslinked to render the material substantially water insoluble.
Crosslinking may, for example, be by irradiation or covalent,
ionic, Van der Waals, or hydrogen bonding. Suitable materials are
available from various commercial vendors such as The Dow Chemical
Company and Stockhausen, Inc. The superabsorbent material may
suitably be included in an appointed storage or retention portion
of the absorbent system, and may optionally be employed in other
components or portions of the absorbent article. The superabsorbent
material may be included in the absorbent layer or other fluid
storage layer of the absorbent article of the present invention in
an amount up to about 60% by weight. Typically, the superabsorbent
material, when present, will be included in an amount of about 5%
to about 40% by weight, based on the total weight of the absorbent
layer.
[0053] Typically, the absorbent layer is an absorbent nonwoven web.
Suitable nonwoven webs are those nonwoven webs which are moisture
stable and wettable. By "moisture stable", it is meant a nonwoven
web which does not lose its integrity when the nonwoven web becomes
wetted by a fluid. Exemplary absorbent nonwoven webs include, for
example, nonwoven webs of airlaid fiber layers, coform fiber
layers, tissue layer meltblown fiber layers or laminates thereof
and laminates of airlaid fiber layers, tissue layers, coform fiber
layers or meltblown fiber layers or laminates thereof with a
nonwoven support. In one embodiment of the present invention, the
absorbent nonwoven web is an airlaid web or a coform web, or a
laminate of an airlaid web or a coform web with a support nonwoven
web. The absorbent layer 16 material will have a basis weight of
between about 20 g/m.sup.2 to about 1000 g/m.sup.2. In another
embodiment of the present invention, the basis weight of the
absorbent layer may be between 50 g/m.sup.2 and 500 g/m.sup.2 and
generally between about 70 g/m.sup.2 and 250 g/m.sup.2.
[0054] The nonwoven support used in the absorbent layer material
may be a spunbond fiber layer made of polypropylene fibers and
having a basis weight in the range of 10 to 40 g/m.sup.2, desirably
10 to 25 g/m.sup.2.
[0055] In a further embodiment of the present invention, the
absorbent layer material may be a laminate of an airlaid fiber
layer or coform fiber layer with a basis weight of 70 g/m.sup.2 to
250 g/m.sup.2 and a spunbond fiber layer with a basis weight in the
range of 10 to 40 g/m.sup.2, specifically 10 to 25 g/m.sup.2. When
using a laminated absorbent layer, the absorbent layer is usually
arranged in the absorbent layer in such a manner that the support
layer faces in the direction of the top layer, i.e. towards the
wearer.
[0056] The absorbent layer material may be an airlaid material,
comprising a mixture of at least 70 wt.-% cellulose fibers, from
about 2 to 6 wt-% polyethylene powder, 5 to 25 wt-% bicomponent or
conjugate fibers, and optionally up to 2 wt-% of a latex binder,
wherein the sum of the weight percentages of the different
components present in the material adds up to 100 wt-%.
Alternatively, the absorbent layer material may be a coform
material containing between 30 and 50 wt-% polypropylene and
between 50 and 70 wt-% cellulose, wherein the sum of the weight
percentages of the different components present in the material
adds up to 100 wt-%. Specifically, the coform material may contain
between 30 and 40 wt-% polypropylene and between 60 and 70 wt-%
cellulose. In a further embodiment, the coform material contains 40
wt-% polypropylene and 60 wt-% cellulose. The absorbent material
may further comprise additives to improve its properties, such as
surfactants or the superabsorbent materials described above to
improve the intake or overall absorbent capacity of the absorbent
article, respectively.
[0057] The absorbent layer of the present invention is provided
with a first plurality of slits 18 having a first orientation and a
second plurality of slits 19 with a second orientation, wherein the
first orientation is different from the second orientation. By
"different orientation" it is meant that the pattern of the first
plurality of slits is different in some aspect than the second
plurality of slits, whether length, width, spacing, direction,
shape, configuration, or location on the slitted surface or a
combination of these properties, such that the pattern generated by
the first plurality of slits is different from the pattern
generated by the second plurality of slits. In addition, the first
plurality of slits 18 and the second plurality of slits 19 are at
least partially through the absorbent layer 16, and the second
plurality of slits 19 at least partially intersects the first
plurality of slits 18 in a manner such that where the first and
second plurality of slits intersect the first and second plurality
of slits combine to form apertures 20 in the absorbent layer
16.
[0058] The first plurality of slits may be linear or non-linear and
the second plurality of slits may also be linear or non-linear. The
only requirement is that the first and second plurality of slits
must intersect, and the area of the absorbent layer where they
intersect must have an aperture formed in the absorbent layer. In
another embodiment of the present invention, there may be at least
one additional plurality of slits having an orientation different
from the first and second plurality of slits. Each of the
additional plurality of slits intersects at least one of the first
and second pluralities of slits, and where the pluralities of slits
with different orientations intersect, there is at least one
aperture formed in the absorbent layer. Generally, when there are
just two pluralities of slits with different orientations, at least
one of the pluralities of slits will need to be non-linear to form
an aperture. However, where there are more than two pluralities of
slits with different orientations, each of the pluralities of slits
may be linear.
[0059] The orientation of the slits may vary greatly, as long as
the slits have an effective component extending in the longitudinal
direction and an effective component extending in the lateral
direction. The non-linear slits of each plurality of slits may
therefore be curved, for instance in the form of waves or arcs, as
is shown in FIGS. 3A, 3B and 3C, or may have two or more linear
sections extending in different directions, as is shown in FIGS. 3D
and 3E or may be a combination of different curved slits and slits
having two or more linear sections extending in different
directions, as shown in FIG. 3F. In addition, the pattern of slits
may have linear slits (not shown). In the present invention, the
pattern of slits will be considered non-linear if one or more slits
in the pattern are non-linear. The pattern of slits may be a
repeating pattern, as shown in FIGS. 3A-3F, or may be a random
pattern. Also, as shown in FIGS. 3A, 3B, 3D, 3E and 3F, not all of
the slits in a plurality of slits need to have the configuration,
orientation or shape. However, the second or any additional pattern
of slits on the absorbent layer must intersect at least one of the
first pattern of slits, such that an aperture is placed in the
absorbent layer. This will be described in more detail below.
[0060] Referring to FIG. 4, the first pattern of slits 18 in the
absorbent layer 16 may be regularly arranged along a plurality of
spaced apart lines 22 which extend in the direction parallel to the
longitudinal direction, wherein these lines are spaced apart at a
distance e. Two adjacent slits 18 arranged on one of these parallel
lines are spaced apart by a distance c. Each slit 18 has an
effective length a in longitudinal direction and an effective
length d in lateral direction. The sum of the distance a and the
distance c gives the length b along the longitudinal direction at
which the slit-pattern along one parallel line 22 is repeated. The
pattern of slits may either extend essentially over the complete
surface of the absorbent layer or only selected sections thereof,
for instance the central area of the absorbent layer or peripheral
sections such as front and back sections and/or side sections.
Generally, the effective length a of a slit in longitudinal
direction can be selected to lie in the range between about 2 mm
and about 20 mm. The effective length in cross direction d can be
selected to lie in the range between about 0.5 mm and about 10 mm,
specifically between about 1 mm and 6 mm. The ratio of the
effective length a and the effective length d can be selected to
lie in the range between 15:1 and 2:1, and, more specifically, in
the range between 6:1 and 3:1. The distance e between each of the
spaced apart parallel lines 22 can be selected to lie in the range
between 4 mm and 8 mm, more specifically between 5 mm and 6 mm. The
distance c between two adjacent slits in longitudinal direction can
be selected to have a value in the range between 1 mm and 10 mm,
specifically between 1 mm and 5 mm, more specifically between 1 mm
and 3 mm. In addition the second plurality of slits and any
additional plurality of slits cut into the absorbent layer may have
these general dimensions.
[0061] A second plurality of slits 19 is cut into the absorbent
layer 16, wherein at least one of the slits of the second plurality
of slits 19 intersects at least one of the slits in the first
plurality of slits 18. When the second plurality of slits 19 are
cut into the absorbent layer and intersect the at least one of the
first plurality of slits 18, the area of the absorbent layer
between the intersecting slits is cut free from the absorbent
layer, thereby forming an aperture 20 in the absorbent layer. In
this regard, attention is directed to FIGS. 4 and 5, which show
details of the intersecting slits from the first plurality of slits
and the second plurality of slits. In FIG. 4, the second plurality
of slits 19 may have the same or similar pattern with one or more
aspects of the pattern being changed to form the apertures. For
example the first and second plurality of slits may have the same
shape or configuration but the second plurality of slits is out of
phase or offset from the first plurality of slits 18. Other
features of the slits may be changed to provide apertures in the
absorbent layer 16. In the case of FIG. 4, as shown in the second
plurality of slits 19, have a smaller arc radius than the arc of
the first plurality of slits 18. In FIG. 5, the second plurality of
slits 19 has the same general shape as the first plurality of slits
18, but is mirror images of one another.
[0062] The intersection of the first and second pluralities of
slits in FIGS. 4 and 5 are shown to be similar or inverted from one
another, and this is not required by the present invention. One of
or both of the plurality of slits may be linear; one may be arced
and the other two linear lines together which form a non-linear
slit and any other combination which allows for an aperture to be
formed into the absorbent layer. In addition, more than two
pluralities of slits that intersect can be used to form the
apertures in the absorbent layer. For example, two possible
configurations for forming an aperture using more than two
intersecting pluralities of slits are shown in FIGS. 6A and 6B. For
example, in FIG. 6A, three intersecting non-linear slits 18', 19'
and 21' form the aperture 20. In FIG. 6B, three intersecting linear
slits 18', 19' and 21' form the aperture 20. Any combination of
linear and non-linear slits may be used to form the apertures in
the absorbent layer 16.
[0063] The slitted and apertured absorbent layer used in the
present invention should maintain a sufficient flexural resistance
to avoid bunching of the absorbent layer, or formation of lumps
therein when worn, or for it to be considered to be too flexible
(flabby, flimsy) by the consumers. In specific embodiments of the
present invention, the flexural resistance of the slitted absorbent
layer is selected to have a value in the range of about 0.5 N to 1
N as determined by the circular bending procedure described, for
instance, in European Patent EP 0336578 corresponding to U.S. Pat.
No. 4,950,264 to Osborn, Ill., which is hereby incorporated by
reference. Therein, the absorbent layer comprises a plurality of
slits and apertures therethrough, and the ratio of the tensile
strength of the absorbent layer in longitudinal direction and the
tensile strength of the absorbent layer in lateral direction has a
value in the range from 3.5:1 to 6:1. In specific embodiments of
the present invention this ratio is selected to be in the range
between 4.5:1 to 5.6:1.
[0064] To improve the extensibility of the absorbent layer while
maintaining sufficient flexural resistance of the absorbent
material, a pattern of non-linear slits and/or linear slits is cut
or punched into the absorbent layer. The pattern of slits and
apertures or linear slits which are at an acute angle relative to
the longitudinal direction of the absorbent article should
significantly decrease the tensile strength of the absorbent
material in both the longitudinal direction (corresponding to the
MD) and lateral direction (corresponding to the CD) while still
maintaining sufficient stability and durability for the absorbent
material to be processed at high speeds in a production line. At
the same time, as already outlined above, the flexural resistance
should not be decreased too much, otherwise the possibility of
formation of lumps or bunching exists, or the absorbent article
might be perceived by the consumer as being too flexible (flimsy,
flabby). A reduction of the flexural resistance by between 40 and
70%, and more specifically by between 60 and 70%, compared to the
non-slit material, is considered to be suitable.
[0065] In the present invention, the pattern formed by the first
plurality of slits 18 may define a first and a second patterned
area. The arrangement of the slits 18 in the second pattern area
may be a mirror inverted image of the arrangement of the slits in
the first pattern area. Such a pattern may for instance arise if
one imagines a mirror plane extending along the middle of the
absorbent layer in longitudinal direction and perpendicular to the
surface of the flat absorbent layer and the pattern formed by the
slits on one half of the absorbent layer being mirrored onto the
second half of the absorbent layer. In a similar manner, the slits
may be mirrored along the lateral center line in the lateral
direction separately or in addition to the mirroring in the
longitudinal direction. This is shown in FIGS. 4 and 5.
[0066] In the present invention, the second or optional additional
pluralities of slits are cut in the absorbent layer, these second
and optional additional plurality of slits are generally only cut
in a portion of the absorbent layer where it is desired to have
apertures on the absorbent layer. Stated another way, the second
and additional slits are only provided in the absorbent layer to
provide apertures and all of the remaining slits are part of the
first plurality of slits. In the alternative, the first plurality
of slits could be cut into the absorbent layer such that all of the
slits having the exact same orientation or configurations. The
second plurality of could be slits cut into the absorbent layer
which mirror the first plurality of slits and intersect the first
plurality of slits to form the apertures. The manner in which the
slits are cut into the absorbent layer is not critical to the
present invention, provided that the slits and apertures have the
configurations described herein. It is noted, however, that the
process of the present invention is highly advantageous for forming
the slitted and apertured absorbent layer.
[0067] If the slits are nonlinear slits which are at an acute angle
relative to the longitudinal direction of the absorbent article,
the acute angle is generally an angle .omega., shown in FIG. 7
between about 10.degree. and 80.degree.. More specifically, the
acute angle is about 20-30.degree..
[0068] The removed area of the absorbent nonwoven web forms
apertures in the absorbent nonwoven web. The apertures formed by
the first and second plurality of slits has an effective length in
longitudinal direction in the range between about 2 mm and about 20
mm, generally about 5 mm to about 12 mm and an effective width in
lateral direction in the range between about 0.5 mm and about 10
mm, and generally about 1 mm to about 6 mm.
[0069] By providing the slitted and apertured absorbent layer in an
absorbent personal care product, functional and aesthetical
enhancements are provided to the absorbent personal care article.
Functional enhancements include improved fluid distribution of an
insulting fluid as compared to a non-slitted and non-apertured
absorbent layer made from the same. In a further embodiment of the
absorbent layer according to the present invention, the formation
of the slits and apertures in the absorbent layer increases the
distribution of defibrinated sheep blood in the longitudinal
direction of the absorbent layer by 1.5 to 2 times, compared to an
identical absorbent layer, but without a pattern of cuts
corresponding to the pattern of slits and apertures, as measured by
observing the distribution of 3 ml of defibrinated sheep blood,
which have been brought into contact with the absorbent layer after
10 minutes. Although not wishing to be bound by theory, it is
believed that the slits and apertures in the absorbent layer allow
the absorbent layer to quickly intake and transport an insulting
fluid from the top layer into the absorbent layer by the
capillaries and void space created by the combination of slits and
apertures and by the increase in the surface area of the absorbent
layer provided by the apertures.
[0070] Other function enhancements include that the resulting
absorbent article has multidirectional extensibility in the lateral
and diagonal axes. As a result, the absorbent article tends to move
with the user, providing a comfortable to wear absorbent article.
The absorbent article, in particular, a feminine sanitary napkin or
incontinence pad, will respond to the movements of a user, for
example, when walking or other body motions, making the absorbent
article less noticeable to a user.
[0071] From an aesthetic standpoint, by having apertures and slits
in the absorbent layer, additional layer under the absorbent layer
may be viewed by the user, if the additional layers are of a
different color. This could convey a message to a user that the
absorbent article has improved absorbency, intake capacity,
comfort, breathability, protection or fit. In addition, the
apertures could be used to provide color or aesthetic designs in an
absorbent article in which the absorbent layer is used.
[0072] The absorbent layer may contain other additives to help
control odor, such as zeolites, baking soda or other conventional
odor control agents. By having the apertures and slits in the
absorbent layer, the surface area of the odor control agent may be
increased, thereby effectively increasing the odor control
properties of the absorbent layer. Other layers of the absorbent
article may also contain odor control agents. If the odor control
agents are in a layer below the absorbent layer, the odors may be
able to more effectively come into contact with the odor control
agent due to the presence of the slits and apertures. Further, the
slits and apertures may also provide a means for improving the
breathability of the absorbent article and the absorbent layer,
allowing air to more readily pass through the absorbent layer.
[0073] The absorbent article according to the present invention may
further comprise a garment attachment system, which in one
embodiment may consist of at least one adhesive strip on the
surface of the liquid-impermeable backing layer 30 facing away from
the wearer's body, and covering means for covering the at least one
adhesive strip 32. The adhesive may be, for instance, a hot-melt
adhesive or pressure sensitive adhesive. The covering means may be,
for instance, a release tape, which may be made of a silicone
paper. In a further embodiment of the absorbent article according
to the present invention, the garment attachment system consists of
two separate adhesive strips extending in the longitudinal
direction of the absorbent article and either two corresponding
release tapes or a single release tape comprising a dividing line
formed by perforations, which allows the release tape to be easily
divided into two separate release tapes, for covering the adhesive
strips. The absorbent article comprising such a garment attachment
system is also extensible when the perforated release tape or the
two release tapes are still attached to the absorbent article. In
the case of the perforated release tape, the application of tension
will divide the release tape into two separate release tapes. This
allows the user to perceive the extensibility of the absorbent
article even without having to remove the release tape from the
absorbent article.
[0074] As shown in FIG. 2, the absorbent article 10 according to
the present invention may comprise additional layers positioned
between the absorbent layer and the backing layer 30. The absorbent
article 10 may, for instance, further comprise a transfer layer 26
for further enhancing the distribution of liquid in the horizontal
direction of the absorbent article. The transfer layer 26 may, for
instance, be a meltblown material, an airlaid material, a spunbond
or carded web material or any other material which has been used as
a transfer layer in absorbent articles. Typically, the transfer
layer will have a basis weight of between 20 to 200 g/m.sup.2, and
generally between 70 to 110 g/m.sup.2.
[0075] Additionally or instead of the transfer layer 26, the
absorbent article 10 may further comprise an additional absorbent
layer 28, also referred to as a storage layer, which may be
prepared from cellulose fluff pulp and, optionally, superabsorbent
particles or superabsorbent fibers and/or odor controlling
additives. The additional absorbent layer may be in the shape of an
oval pillow, shown in FIG. 2, to further increase the absorbent
capacity of the absorbent article and at the same time providing
wearing comfort for the user. In the alternative, the additional
absorbent layer may be coextensive with the first absorbent layer
16, or slightly smaller than the first absorbent layer 15 (not
shown).
[0076] As outlined above, the present invention provides an
absorbent layer for use in an absorbent article having a
longitudinal direction and a lateral direction, wherein the
absorbent layer is made of a nonwoven absorbent material and has a
plurality of slits formed therethrough. The slits are formed from a
first plurality of slits with a first orientation and a second
plurality of slits with a second orientation, wherein the first
orientation is different from the second orientation. The first
plurality of slits and the second plurality of slits are at least
partially through the absorbent nonwoven web, and the second
plurality of slits at least partially intersects the first
plurality of slits in a manner such that where the first and second
plurality of slits intersect the first and second plurality of
slits combine to form openings or apertures in the absorbent
nonwoven web. Each slit is formed by removing a section of the
nonwoven absorbent material from the absorbent layer and
simultaneously densifying the nonwoven absorbent material in the
areas of the absorbent layer adjacent to the edge of the opening
created by slitting the absorbent layer material, i.e. adjacent to
the removed section of the slit. In the area of the absorbent
nonwoven web where the first plurality of slits intersects a second
plurality of slits, the second plurality of slits cuts through the
absorbent nonwoven web such that a portion or at least one of the
second plurality of slits cuts the absorbent nonwoven web up to and
possibly beyond the first slits. In doing so, the portion of the
absorbent nonwoven web which is between the first slit and the
second slit is cut free from the nonwoven web, thereby causing the
area between the slits to be removed from the nonwoven web. As a
result, the nonwoven web has apertures formed therein.
[0077] The absorbent layer may be any suitable material for use in
absorbent articles such as sanitary napkins and other disposable
absorbent articles. The special slits and aperture combination in
the absorbent layer, according to the present invention, can
especially be formed in the above described absorbent layers
discussed in connection with the absorbent articles according to
the first aspect of the present invention. It should, therefore, be
understood that the absorbent articles described above as the first
aspect of the present invention may have the specially slitted and
apertured absorbent layers according to the second aspect of the
present invention and that the absorbent layers described with
references to the second aspect of the present invention may be
made of the materials described with reference to the absorbent
layers in the absorbent articles according to the first aspect of
the present application.
[0078] In another aspect of the present invention, the present
invention provides an apparatus to prepare the absorbent layer
having a first plurality of slits with a first orientation and a
second plurality of slits with a second orientation, wherein the
first orientation is different from the second orientation, the
first plurality of slits and the second plurality of slits are at
least partially through the absorbent nonwoven web, and the second
plurality of slits at least partially intersects the first
plurality of slits in a manner such that where the first and second
plurality of slits intersect the first and second plurality of
slits combine to form apertures in the absorbent nonwoven web. In
this regard, attention is directed to FIG. 8A, which shows the
apparatus of the embodiment of the present invention. The slitting
and aperturing apparatus 100 has an anvil roll 110, a first cutting
roll 50 and a second cutting roll 51, wherein the first cutting
roll 50 and second cutting roll 51 are in communication with the
anvil roll 110. By "in communication with" it is intended that the
cutting rolls are close enough to the anvil roll that the motion of
each of the anvil roll and the cutting rolls are essentially at the
same pace, taking into account the diameter of each roll. By having
the cutting rolls 50, 51 and the anvil roll 110 in communication
with one another, one of the rolls can be driven by a motor (not
shown) and the other rolls are turned due to the motion of the roll
driven by the motor. As a result, the anvil roll and the cutting
rolls can be easily driven in unison. The slitting and aperturing
apparatus may have other guide rolls 53 and other features commonly
present in an anvil slitting operation. In a further embodiment of
the apparatus of the present invention, there may be at least one
additional cutting roll 53, shown in FIG. 8B, which is also in
communication with the anvil 110. Each additional cutting roll 53
may be run in unison with the anvil roll 110 and the first and
second cutting rolls 50, 51.
[0079] In the present invention, referring to FIG. 9, each cutting
roll 50, 51 and the optional additional cutting rolls 53 has an
essentially cylindrical shape and having an outer surface 52 and
has a series of protrusions 56 that are capable of forming slits in
a web passed between the anvil and each cutting roll. Each cutting
roll of the apparatus may further have, as shown in FIG. 9, two
outer, elevated rim sections 54. The cutting roll has at least one
plurality of punching or cutting elements 56 for forming a pattern
of slits in a web passed between the anvil roll and each cutting
roll. In the case of the present invention, the web may be the
absorbent layer described above. As shown in FIG. 10, each punching
element may have a height h, which is the distance between the
outer surface 52 and the tips 58 of the punching elements 56. The
height h may be adapted for each respective web material to be cut.
Each punching element comprises a base section 60 protruding from
the outer surface 52 of the roller. In the embodiment shown in FIG.
9 and FIG. 10, the latter one showing a cross section of the area
denoted "Y" in FIG. 9, the side walls 60 of the punching element 56
are essentially linear and extend in a direction perpendicular to
the outer surface 52 of the roller 50. Extending from the base
section 60 is the blade section 62 of the punching element, which
has a trapezoidal cross section perpendicular to the direction in
which the respective slit in the pattern is formed, and a tip 58.
The trapezoidal cross section defines two parallel sides running in
parallel with the outer surface 52 and two non-parallel sides, said
two non-parallel sides enclosing an angle .beta. of between 45 to
75.degree., preferably between 55.degree. and 65.degree., and the
smaller of said two parallel sides, which represents the tip 58 of
the punching element. The tip will generally have a width of
between 0.1 mm and 0.45 mm, depending on the material to be cut,
slitted or punched. It is noted that the pattern of punching
elements shown in FIG. 9 is merely exemplary and is not intended to
be limiting. Other patterns of punching elements previously
described may also be used, as with other patterns not specifically
mentioned in the present specification that do not depart from the
intention or spirit of the present invention.
[0080] At least some of the protrusions of the first cutting roll
and some of the protrusions of the second cutting roll are aligned
on the anvil such that at least a portion of slits cut by the first
cutting roll are overlapped with at least a portion of the slits
cut by the second cutting roll. As is described above, where the
slits overlap, if the slits are properly aligned, the slits combine
to form apertures in the web. The pattern of punching elements on
the second cutting roll may be the same or different from the
punching elements of the first cutting roll, where the slits
desirably overlap one another. Each additional cutting roll has a
series of protrusions that are capable of forming slits in a web
passed between the anvil and each cutting roll.
[0081] The apparatus of the present invention provides advantages
over other dual cutting apparatus. By having each of the cutting
rolls in communication with the anvil roll, the anvil roll or
another drive roll can be used to operate all of the rolls in the
apparatus. This will ensure that the first cutting roll and the
second cutting roll will be turned in unison with each other,
keeping the slits cut by the first cutting roll aligned with the
slits cut by the second cutting roll which provide apertures in the
web. By having the cutting rolls turn in unison with a single drive
roll, a high level of precision in forming slits and apertures in
the webs passed through the apparatus will be achieved. The
apparatus provides a less complex process than processes that
conventionally form apertures, by providing a means for registering
cutting patterns between the first and second cutting rolls. In
addition, the apparatus of the present invention provides other
advantages, including a lower cost of capital, a way to cut slits
and apertures in a single apparatus, and providing a less complex
apparatus for cutting slits and apertures.
[0082] The apparatus of the present invention may be used in the
process according to the present invention to form the absorbent
article and the absorbent layer described above. All of the
materials described above, with reference to the absorbent layer of
the present invention may be formed using the apparatus of the
present invention. The process according to the present invention,
utilizes the apparatus and includes the steps of a) providing a
web; b) providing a slitting apparatus having an anvil roll, a
first cutting roll and a second cutting roll; c) passing the web
between the first cutting roll and the anvil to form a first
plurality of slits in the absorbent nonwoven web; and d) passing
the web between the second cutting roll and the anvil to form a
second plurality of slits in the absorbent nonwoven web, wherein at
least one slit in the second plurality of slits intersects at least
one slit from the first plurality of slits such that an aperture is
formed in the web. In the process of the present invention, both
the first and second cutting rolls are positioned adjacent the same
anvil roll. That is, the first cutting roll and the second cutting
roll place slits in a web which is passed through the apparatus,
including the absorbent nonwoven web of the present invention,
between the first and second cutting rolls and the anvil roll. The
absorbent nonwoven web of the present invention is brought into
contact with the anvil roll, cut with the first cutting roll. Once
cut or slitted with the first cutting roll, the web remains in
contact with the anvil roll and is cut or slit with the second
cutting roll. The first and second cutting rolls may be run in
unison to register the first and second slits cut into the web,
which can result in apertures being formed into the nonwoven
web.
[0083] In a further embodiment of the process according to the
present invention, the process may comprise the additional steps of
d) attaching the absorbent layer to a top layer material sheet, e)
laminating a backing layer material sheet to the top layer material
sheet in such a manner that the absorbent layer is positioned
between the top layer material layer and the backing material
layer, and f) cutting the laminate of top layer material sheet,
absorbent layer and backing layer material sheet into the shape of
an absorbent article.
[0084] FIG. 10 shows a schematic representation of an embodiment of
the process according to the present invention. Except for the use
of the slitting and aperturing apparatus according to the present
invention, the process may use known apparatuses and process steps
commonly used in the art of producing absorbent articles, which are
well known to the person skilled in the art and therefore do not
require a detailed discussion.
[0085] The absorbent layer material sheet 160 is provided from
supply roll 240 and transported to slitting apparatus 200. The
slitting apparatus 200 contains the first slitting roll 50, a
second slitting roll 51 and an avil roll 110 according to the
present invention. In the slitting apparatus, patterns of slits are
formed in the absorbent layer material sheet 160. From the slitting
apparatus 200, the slitted absorbent layer material sheet 160 is
transported to the cutting station 220, which cuts absorbent layers
from the absorbent layer material sheet 160. These absorbent layers
are then transported from the cutting station 220 and attached, for
instance laminated, to a top layer material sheet 120, which is
provided from the supply roll 250. The remaining absorbent layer
material sheet can be removed separately from the cutting station
using conventional techniques (not shown). To laminate the
absorbent layer to the top layer material sheet 120, an adhesive
may be applied to the top layer material sheet 120 before the
absorbent layers are deposited on the top layer material sheet 120.
Next, a backing layer material sheet 300, which is provided from
supply roll 260 is laminated to the laminate of absorbent layers
and top layer material sheet 120 in such a manner that the
absorbent layers are positioned between top layer material sheet
120 and the backing layer material sheet 300. Again, an adhesive
may be applied to the backing layer material sheet 300 to achieve
the lamination.
[0086] From this laminate, absorbent articles comprising a top
layer 12, absorbent layer 16 and backing layer 30 can subsequently
be cut and formed. If additional layers, such as transfer layers
and fluff pads are to be incorporated into the absorbent articles,
additional conventional process steps would have to be incorporated
into the process, by means of which these components are formed in
the absorbent articles. The process may further comprise embossing
steps to provide embossing lines or patterns in the absorbent
articles. Furthermore, steps for forming garment attachment systems
on the absorbent article, either on the backing sheet or the wing
sections of the absorbent articles or both may be carried out, for
instance, by an application of adhesive strips and application of
corresponding release tapes.
Examples
[0087] To test the improved liquid transportation properties of the
absorbent layer and the mechanical properties of the absorbent
layer, an airlaid absorbent layer laminate of a spunbond support
and an airlaid nonwoven web is used. The airlaid nonwoven web has a
basis weight of 90 g/m.sup.2 and contains about 76% by weight pulp,
15.5% bicomponent fibers, 2.5% by weight latex and 6% by weight
polyethylene powder. The support layer is a 17 g/m.sup.2
polypropylene spunbond support layer, which gives the absorbent
layer laminate a total basis weight of about 107 g/m.sup.2.
[0088] The absorbent layer laminates are slitted using the process
and apparatus of the present invention described above. Two
different slitting and aperturing patterns are used. One slitting
and aperturing pattern is the pattern as shown in FIG. 4, which
results in crescent shaped apertures and arced slits in the
absorbent layer. The arced slits are about 2 mm apart in the MD and
have an effective length of about 8.5 mm and an effective width in
the CD of about 2 mm. The apertures formed in the absorbent layer
have an effective width in the CD of about 2 mm and an effective
length in the MD of about 6 mm.
[0089] A second slitting and aperturing pattern shown in FIG. 5 is
used, which results in rhombus shaped apertures and V-shaped slits
in the absorbent layer. The V-shaped slits are about 4 mm apart in
the MD and have an effective length of about 14 mm and an effective
width in the CD of about 2 mm. The apertures formed in the
absorbent layer have an effective width in the CD of about 2 mm and
an effective length in the MD of about 7 mm.
[0090] As a control in a comparative example, an identical nonwoven
web without slits or apertures is used for comparison.
[0091] 1. Fluid Handling and Wicking Properties
[0092] Each of the slitted and apertured absorbent layers and the
control are tested for wicking. Each absorbent layer is placed on a
liquid-impermeable sheet and 2 ml of defibrinated sheep blood
obtained from OXOID, Wesel, Germany, were applied onto the central
area of each absorbent layer using a pipette. After 10 minutes, an
additional 1 ml of the defibrinated sheep blood is applied as a
second insult onto the central area of the absorbent layer. The
maximum lateral and longitudinal wicking distance of the blood in
the absorbent cores is measured. Several samples of each were
tested and the range of maximum longitudinal length of the
resulting stain and the maximum lateral length of the resulting
stain were measured. For each the wicking factor, which is the
maximum longitudinal length/maximum lateral length of the stain, is
calculated. The same was done for the control. The results are
shown in Table 1.
TABLE-US-00001 TABLE 1 Calculated wicking factor ranges for each
slit/aperture pattern Range of Wicking Factors Avg. max. Avg. max
Slit and for All Samples of longitudinal lateral aperture pattern
slit/aperture pattern length length Arced 1.44-1.65 97 mm 63 mm
slits/crescent apertures V-slits and 1.61-1.87 108 mm 62 mm rhombic
apertures Control (none) 1.0-1.04 56 mm 55 mm
[0093] The above data shows that the absorbent layer having both
apertures and slits according to the present invention exhibit an
improved liquid transportation in the longitudinal direction of the
absorbent core. The absorbent cores therefore make more efficient
use of the absorbent capacity of the absorbent material. At the
same time, the liquid transportation in lateral direction is only
increased to a small extent. A too high transport rate in the
lateral direction would increase the risk of leakage at the sides
of the absorbent article. The improved liquid transportation in
longitudinal direction therefore enables that more of the absorbent
material present in the absorbent article is utilized before the
absorbent article needs to be changed.
[0094] 2. Mechanical Properties of the Absorbent Layer According to
the Present Invention.
[0095] The tensile strength and elongation at tear of the absorbent
layers described above in this Example and the Control-samples were
measured using a conventional tensile strength machine complying to
DIN 51221. The samples had a width of 50 mm and were measured with
a clearance between clamps of 50 mm and a haul-off speed of 50
mm/min. Each sample is tested in the MD, the CD and 45 degrees to
the MD and CD. The measurement followed essentially the procedure
outlined in DIN 53857 but did not use a pre-load force. The
flexural resistance of the absorbent core samples was measured
according to the above mentioned circular bend procedure.
[0096] The measured values of the samples according to the present
invention with the arced slits and crescent apertures and/or the
v-shaped slits and rhombic apertures described above are compared
below in Table 2 with those of an identical absorbent layer without
any slits or apertures formed therein and the identical absorbent
layer with only slits cut therein. All values are average values
derived from measurement of 5 samples with the exception of the
flexural resistance which compared 10 samples.
TABLE-US-00002 TABLE 2 Mechanical properties of the absorbent cores
Arced V-slits and Arced No slits slits/crescent rhombic slits
V-slits or Test specimen apertures apertures only only apetures
Tensile strength 18.8 16.2 30.0 21.9 42.6 MD (N/50 mm) Tensile
strength 3.6 2.2 4.8 3.1 24.4 CD (N/50 mm) Tensile strength 6.5 3.1
6.7 4.4 31.2 at 45.degree. (N/50 mm) Elongation at 12.5 12.2 14.5
11.3 17.5 tear MD (%) Elongation at 34.5 105 36.5 108 23.0 tear CD
(%) Elongation at 14.8 23.8 13.2 15.3 20.1 tear 45.degree. (%)
Elongation at 3 N 25.7 --* 19.2 98 0.8 CD (%) Elongation at 3 N 4.3
20.5 3.0 7.1 0.5 45.degree. (%) Flexural 0.46 0.29 0.67 0.43 0.69
resistance (N) *tore at 2.2 N.
[0097] The above data shows that the absorbent cores comprising the
slits and apertures prepared in accordance with the present
invention have an increased extensibility while maintaining a
sufficient flexural resistance and tensile strength in MD for
processing the material in a process for making absorbent articles,
as compared to absorbent layers only slitted or absorbent layers
not slitted.
[0098] While the present invention has in the above been described
with special reference to specific embodiments and examples, those
skilled in the art will readily appreciate that many modifications
are possible in the exemplary embodiments without materially
departing from the novel teachings and advantages of this
invention. Accordingly, all such modifications are intended to be
included within the scope of this invention as defined in the
following claims. It should be further noted that any patents,
applications or publications referred to herein are incorporated by
reference in their entirety.
* * * * *