U.S. patent application number 15/952871 was filed with the patent office on 2018-08-16 for disposable absorbent article.
The applicant listed for this patent is The Procter & Gamble Company. Invention is credited to Carsten Heinrich KREUZER, Udo Friedel SCHOENBORN, Maja Wciorka.
Application Number | 20180228674 15/952871 |
Document ID | / |
Family ID | 40848490 |
Filed Date | 2018-08-16 |
United States Patent
Application |
20180228674 |
Kind Code |
A1 |
Wciorka; Maja ; et
al. |
August 16, 2018 |
DISPOSABLE ABSORBENT ARTICLE
Abstract
A disposable absorbent article is provided having an absorbent
core located in a chassis and including absorbent particulate
polymer material defining at least one cavity. The absorbent core
may be substantially cellulose free or comprise a combination of
particulate absorbent polymer material and wood pulp. Methods for
making such an absorbent core and corresponding disposable
absorbent article are also disclosed.
Inventors: |
Wciorka; Maja;
(Braunschweig, DE) ; KREUZER; Carsten Heinrich;
(Hofheim, DE) ; SCHOENBORN; Udo Friedel; (Bad
Soden, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Procter & Gamble Company |
Cincinnati |
OH |
US |
|
|
Family ID: |
40848490 |
Appl. No.: |
15/952871 |
Filed: |
April 13, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14700188 |
Apr 30, 2015 |
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15952871 |
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12416383 |
Apr 1, 2009 |
9044359 |
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14700188 |
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61048668 |
Apr 29, 2008 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 13/495 20130101;
A61F 2013/53908 20130101; A61F 2013/5307 20130101; A61F 13/496
20130101; A61F 13/539 20130101; A61F 13/536 20130101 |
International
Class: |
A61F 13/539 20060101
A61F013/539; A61F 13/496 20060101 A61F013/496 |
Claims
1. An absorbent article, comprising: a. a topsheet; b. a backsheet;
c. an absorbent core disposed between the topsheet and the
backsheet, the absorbent core comprising absorbent particulate
polymer material and wood pulp; and d. an acquisition layer
disposed between the absorbent core and the topsheet, the
acquisition layer comprising an aperture therethrough; e. wherein a
first region of the absorbent core underlying the aperture
comprises a thickness that is substantially equal to that of a
second region of the absorbent core that does not underlie the
aperture.
2. The absorbent article of claim 1, wherein the acquisition layer
comprises a nonwoven.
3. The absorbent article of claim 1, wherein the acquisition layer
comprises a meltblown layer.
4. The absorbent article of claim 1, wherein the acquisition layer
comprises a spunbonded layer.
5. The absorbent article of claim 1, wherein the acquisition layer
comprises a meltblown layer and a spunbonded layer.
6. The absorbent article of claim 1, wherein the acquisition layer
comprises synthetic fibers.
7. The absorbent article of claim 1, wherein the acquisition layer
comprises a hydrophilic coating.
8. The absorbent article of claim 1, wherein the article is a
feminine hygiene product.
9. An absorbent article, comprising: a. a topsheet; b. a backsheet;
c. an absorbent core disposed between the topsheet and the
backsheet, the absorbent core comprising absorbent particulate
polymer material and wood pulp; d. a first acquisition layer
disposed between the absorbent core and the topsheet, the
acquisition layer comprising an aperture therethrough; and e. a
second acquisition layer disposed between the first acquisition
layer and the absorbent core.
10. The absorbent article of claim 9, wherein the second
acquisition layer comprises a second aperture therethrough.
11. The absorbent article of claim 10, wherein the second aperture
is substantially aligned with the first aperture.
12. The absorbent article of claim 9, wherein a first region of the
core underlying the aperture comprises a thickness that is
substantially equal to that of a second region of the core that
does not underlie the aperture.
13. The absorbent article of claim 9, wherein the first acquisition
layer comprises a nonwoven.
14. The absorbent article of claim 9, wherein the first acquisition
layer comprises a PET fibers.
15. The absorbent article of claim 9, wherein each of the first
acquisition layer and the second acquisition layer comprises
synthetic fibers.
16. The absorbent article of claim 9, wherein at least one of the
first acquisition layer and the second acquisition layer comprises
a hydrophilic coating.
17. The absorbent article of claim 9, wherein the article is a
feminine hygiene product.
18. An absorbent article, comprising: a. a topsheet; b. a
backsheet; c. an absorbent core disposed between the topsheet and
the backsheet, the absorbent core comprising absorbent particulate
polymer material and wood pulp; d. an acquisition layer disposed
between the absorbent core and the topsheet, the acquisition layer
comprising an aperture therethrough; and e. a
longitudinally-extending cavity; f. wherein the cavity is defined
by the aperture in the acquisition layer; and g. wherein the
absorbent core is substantially planar underneath the aperture.
19. The absorbent article of claim 18, wherein the acquisition
layer comprises a hydrophilic coating.
20. The absorbent article of claim 18, wherein the article is a
feminine hygiene product.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
14/700,188, filed Apr. 30, 2015, which is a continuation of
application Ser. No. 12/416,383, filed Apr. 1, 2009 (now U.S. Pat.
No. 9,044,359, issued Jun. 2, 2015), which claims the benefit of
U.S. Provisional Application No. 61/048,668, filed Apr. 29, 2008,
the substance of which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to an absorbent
article, and more particularly to a disposable absorbent garment,
such as a taped diaper or training pant, comprising absorbent
particulate polymer material.
BACKGROUND OF THE INVENTION
[0003] Absorbent articles, such as disposable diapers, training
pants, and adult incontinence undergarments, absorb and contain
body exudates.
[0004] Fecal material is often difficult to remove from the skin of
the user (e.g., wearer) of the absorbent article, in particular on
sensitive skin such as that of young babies. Moreover, it is known
that fecal material on the skin can cause irritation and redness of
the skin and sometimes even dermatitis. Hence it desirable to
reduce the fecal material on the skin, to provide a means to
isolate the fecal material immediately after discharge, away from
the skin. Conventional approaches toward this isolation include
providing a diaper with a top sheet with one or more openings,
through which the feces can pass for storage underneath this top
sheet, away from the skin. However, this approach may not always be
effective, particularly when the baby is in a sitting position or
when the diaper is already highly urine-loaded, both of which
diminish the void volume available to receive the feces.
[0005] There is also a desire to improve the comfort and fit of
absorbent articles such as diapers, for example to make them
thinner and more flexible while preserving or enhancing the
article's ability to absorb and hold one or more gushes of liquid,
to minimize uncontrolled bowel movement spreading, and to capture
bowel movements so as to lead to cleaner skin for the wearer, with
consequently less skin irritation and easier clean up.
SUMMARY OF THE INVENTION
[0006] The present invention addresses one or more technical
problems described above and provides a disposable absorbent
article, which may comprise a chassis and an absorbent core, which
may be substantially cellulose free. The chassis may include a top
sheet and a back sheet. The absorbent core may be located between
the top sheet and the back sheet and may comprise an absorbent
particulate polymer material. The absorbent core includes at least
one cavity, which may be defined at least about its perimeter by
the absorbent particulate polymer material. The at least one cavity
may be substantially free of the absorbent particulate polymer
material. In one embodiment, the void volume of the cavity may be
from about 2 ml to about 70 ml.
[0007] In one embodiment, the absorbent particulate polymer
material present in the absorbent core may have a basis weight that
varies across the absorbent core in a direction substantially
perpendicular to the central longitudinal axis, in a direction
substantially parallel to the central longitudinal axis, or in both
directions.
[0008] In one embodiment, the disposable absorbent article may have
a central longitudinal axis extending from a first end to a second
end, and the at least one cavity may include (i) a first channel
elongated in a direction substantially parallel to and located
about the central longitudinal axis, and (ii) a second channel
elongated in a direction substantially perpendicular to the central
longitudinal axis. The first and second channels of the cavity
together may form a T-shape.
[0009] In certain embodiments, the first channel may have a width
from about 5% to about 60% of the width of the absorbent core and a
length from about 2% to about 50% of the length of the absorbent
core. The second channel may have a width from about 25% to about
90% of the width of the absorbent core and a length from about 2%
to about 40% of the length of the absorbent core. In one
embodiment, the first channel of the cavity may have a width
between about 10 mm and about 40 mm, and a length between about 10
mm and about 130 mm. In another embodiment, the second channel of
the cavity may have a width between about 30 mm and about 110 mm,
and a length between about 10 mm and about 100 mm. Combinations of
the first and second channels with these dimension ratios and
values are contemplated.
[0010] In one embodiment, the absorbent core may comprise a core
cover and a dusting layer adhered to one another about the
periphery of the absorbent core to form an envelope about the
absorbent particulate polymer materials to hold the absorbent
particulate polymer material within the absorbent core. The core
cover and the dusting layer may be adhered to one another about an
area defining the bottom of the at least one cavity.
[0011] In one embodiment, the disposable absorbent article may
further include an acquisition system located between the absorbent
core and the top sheet. In one embodiment, the acquisition system
may include an upper acquisition layer, which faces the top sheet,
and a lower acquisition layer, which faces the absorbent core. In
one case, the lower acquisition layer does not cover the at least
one cavity. In one case, the upper acquisition layer does not
completely cover the at least one cavity. The at least one cavity
may further be defined about its perimeter by interior edges of an
aperture in the acquisition system.
[0012] In a certain embodiment, the top sheet of the disposable
absorbent article is an elasticized top sheet having at least one
opening. At least a portion of the opening may be substantially
aligned with the first channel of the cavity in the absorbent
core.
[0013] In certain embodiments, the disposable absorbent article may
be a diaper or a pant. In one example, the first channel of the
cavity is located in the absorbent core along the central
longitudinal axis of the diaper or pant at a position which, when
the diaper or pant is worn by a wearer, will be in alignment with a
predetermined region about the anus of the wearer.
[0014] In another aspect, a method is provided for making an
absorbent core for use in a disposable absorbent article. The
method may comprise depositing an absorbent particulate polymer
material on a first substrate to form an absorbent core having a
central longitudinal axis extending from a first end to a second
end, such that the absorbent core is substantially cellulose free
and comprises at least one cavity defined at least about its
perimeter by the absorbent particulate polymer material. The at
least one cavity may be substantially free of absorbent particulate
polymer material.
[0015] In one embodiment, the step of depositing may comprise
placing the first substrate on a porous forming surface and
depositing the absorbent particulate polymer material to the
substrate while applying a vacuum to the substrate through the
porous forming surface. In one example, the forming surface may
have recesses for receiving the substrate and the absorbent
particulate polymer material and the recesses may be sized and
arranged to vary the basis weight of the absorbent particulate
polymer material across the substrate. In another example, the
vacuum applied to the substrate may vary across the forming surface
so as to vary the basis weight of the absorbent particulate polymer
material across the substrate.
[0016] In another embodiment, the step of depositing may further
comprise pneumatically delivering the absorbent particulate polymer
material to the substrate and varying the pneumatic delivery to the
forming surface so as to vary the amount of absorbent particulate
polymer material across the substrate. In one embodiment, the
method may further include adhering the first substrate to a second
substrate about their peripheries to form an envelope about the
absorbent particulate polymer material to hold the absorbent
particulate polymer material within the absorbent core.
[0017] In one embodiment, the first substrate and the second
substrate may be adhered to one another about an area defining the
bottom of the at least one cavity. In one embodiment, the at least
one cavity may be stamped into the absorbent core.
[0018] In still another aspect, a method is provided for making a
disposable absorbent article. The method may comprise depositing an
absorbent particulate polymer material on a substrate to form an
absorbent core which is substantially cellulose free; forming at
least one cavity in the absorbent core, said at least one cavity
being defined at least about its perimeter by the absorbent
particulate polymer material; and locating the absorbent core
between a top sheet and a back sheet of a chassis. In one
embodiment, the method may further include adhering a core cover
and a dusting layer to one another about a periphery of the
absorbent core to form an envelope about the absorbent particulate
polymer materials to hold the absorbent particulate polymer
material within the absorbent core. In one case, the method may
further include adhering the core cover and the dusting layer to
one another at an area about the bottom of the at least one cavity.
In one embodiment, the method may further include locating an
acquisition system between the top sheet and the absorbent
core.
[0019] Features and advantages of the invention may be apparent
from the following detailed description, drawings, and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a plan view of a diaper in accordance with an
embodiment of the present invention.
[0021] FIG. 2 is a cross sectional view of the diaper shown in FIG.
1 taken along the sectional line 2-2 of FIG. 1.
[0022] FIG. 3 is a partial cross sectional view of an absorbent
core layer in accordance with an embodiment of this invention
wherein more absorbent particulate polymer material is present
toward lateral edges of the diaper than in a central zone of the
diaper.
[0023] FIG. 4 is a partial cross sectional view of an absorbent
core layer in accordance with another embodiment of this
invention.
[0024] FIG. 5 is a plan view of the absorbent core layer
illustrated in FIG. 3.
[0025] FIG. 6 is a plan view of a second absorbent core layer in
accordance with an embodiment of this invention wherein more
absorbent particulate polymer material is present toward lateral
edges of the diaper than in a central zone of the diaper.
[0026] FIG. 7 is a partial sectional view of an absorbent core
comprising a combination of the first and second absorbent core
layers illustrated in FIGS. 5 and 6.
[0027] FIG. 8 is a plan view of the absorbent core illustrated in
FIG. 7.
[0028] FIG. 9 is a plan view of an absorbent core wherein more
absorbent particulate polymer material is present toward ends of
the diaper than in a central zone of the diaper.
[0029] FIG. 10 is a plan view of an absorbent core wherein more
absorbent particulate polymer material is present toward lateral
edges and ends of the diaper than in a central zone of the
diaper.
[0030] FIG. 11. is a plan view of an absorbent core in accordance
with an embodiment of the present invention.
[0031] FIG. 12 is a cross-sectional view, taken along line 12-12 of
the absorbent core illustrated in FIG. 11.
[0032] FIG. 13 is a perspective view of an absorbent article in
accordance with an embodiment of the present invention, including
an elasticized top sheet having an opening for receiving fecal
matter.
[0033] FIG. 14 is a cross-sectional, perspective view of the
absorbent article illustrated in FIG. 13.
[0034] FIG. 15 is a schematic representation of a rheometer.
[0035] FIG. 16 is a schematic illustration of a process for making
an absorbent core in accordance with an embodiment of this
invention.
[0036] FIG. 17 is a partial sectional view of an apparatus for
making an absorbent core in accordance with an embodiment of this
invention.
[0037] FIG. 18 is a perspective view of the printing roll
illustrated in FIG. 17.
[0038] FIG. 19 is a partial sectional view of the printing roll
illustrated in FIG. 18 showing absorbent particulate polymer
material reservoirs.
[0039] FIG. 20 is a perspective view of the supporting roll
illustrated in FIG. 16.
[0040] FIG. 21 is a perspective view of a printing roll for making
an absorbent core wherein more absorbent particulate polymer
material is present toward ends of the diaper than in a central
zone of the diaper.
[0041] FIG. 22 is a partial sectional view of the printing roll
illustrated in FIG. 21 showing absorbent particulate polymer
material reservoirs.
[0042] FIG. 23 is a perspective view of a printing roll for making
an absorbent wherein more absorbent particulate polymer material is
present toward lateral edges and ends of the diaper than in a
central zone of the diaper.
[0043] FIG. 24 shows plan views of twenty different absorbent cores
with different possible geometric designs of cavities, according to
certain embodiments of the invention.
[0044] FIGS. 25A-C are cross-sectional views of various
constructions of a cavity in an absorbent core, according to
certain embodiments of the invention.
[0045] FIGS. 26A-C are cross-sectional views (FIGS. 26A-B) and a
plan view (FIG. 26C) of various constructions of a cavity defined,
at least in part, by an acquisition system, according to another
embodiment of the invention.
[0046] FIGS. 27A-K are plan views of several absorbent cores having
cavities and different acquisition system designs, according to
certain embodiments of the invention.
[0047] FIG. 28A is a plan view and FIG. 28B is a cross-sectional
view, taken along sectional line B-B, of an absorbent core having a
gradient of absorbent particulate polymer material around the
cavity and an acquisition layer which augments the cavity,
according to one embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0048] A disposable absorbent article has been developed which
comprises a chassis, which may include a top sheet and a back
sheet, and an absorbent core which may be located between the top
sheet and the back sheet and may comprise an absorbent particulate
polymer material. The absorbent core may include one or more
cavities, for accommodating a bowel movement, defined at least
about its perimeter by the absorbent particulate polymer material
redistributed (versus cavity-less core) whilst maintaining overall
liquid containment capacity. In a certain embodiment, the
disposable absorbent article may have a central longitudinal axis
extending from a first end to a second end, and the cavity may
include (i) a first channel elongated in a direction substantially
parallel to and located about the central longitudinal axis, and
(ii) a second channel elongated in a direction substantially
perpendicular to the central longitudinal axis. The disposable
absorbent article optionally may further include an elasticized top
sheet located adjacent the top sheet and having at least one
opening, a portion of which may be substantially aligned with the
first channel of the cavity in the absorbent core. Embodiments of
such disposable absorbent articles are described hereinbelow along
with embodiments of apparatuses and methods for making such
disposable absorbent articles.
Definitions
[0049] "Absorbent article" refers to devices that absorb and
contain body exudates, and, more specifically, refers to devices
that are placed against or in proximity to the body of the wearer
to absorb and contain the various exudates discharged from the
body. Absorbent articles may include diapers, training pants, adult
incontinence undergarments, feminine hygiene products, breast pads,
care mats, bibs, wound dressing products, and the like. As used
herein, the term "body fluids" or "body exudates" includes, but is
not limited to, urine, blood, vaginal discharges, breast milk,
sweat and fecal matter.
[0050] "Absorbent core" means a structure typically disposed
between a top sheet and cover sheet of an absorbent article for
absorbing and containing liquid received by the absorbent article
and may comprise one or more substrates, absorbent polymer material
disposed on the one or more substrates, and a thermoplastic
composition on the absorbent particulate polymer material and at
least a portion of the one or more substrates for immobilizing the
absorbent particulate polymer material on the one or more
substrates. In a multilayer absorbent core, the absorbent core may
also include a cover layer. The one or more substrates and the
cover layer may comprise a nonwoven. Further, the absorbent core
may be substantially cellulose free. The absorbent core does not
include an acquisition system, a top sheet, or a back sheet of the
absorbent article. In a certain embodiment, the absorbent core
would consist essentially of the one or more substrates, the
absorbent polymer material, the thermoplastic composition, and
optionally the cover layer. In another embodiment, the amount of
absorbent particulate polymer material present in the absorbent
core may vary across the absorbent core.
[0051] "Absorbent polymer material," "absorbent gelling material,"
"AGM," "super absorbent," and "super absorbent material" are used
herein interchangeably and refer to cross linked polymeric
materials that can absorb at least 5 times their weight of an
aqueous fluid such as 0.9% saline as measured using the Centrifuge
Retention Capacity test.
[0052] "Absorbent particulate polymer material" is used herein to
refer to an absorbent polymer material which is in particulate form
so as to be flowable in the dry state.
[0053] "Airfelt" is used herein to refer to comminuted wood pulp,
which is a form of cellulosic fiber.
[0054] "Basis weight" means weight of a material per unit area of
the material.
[0055] "Comprise," "comprising," and "comprises" are open ended
terms, each specifies the presence of what follows, e.g., a
component, but does not preclude the presence of other features,
e.g., elements, steps, components known in the art, or disclosed
herein.
[0056] "Consisting essentially of" is used herein to limit the
scope of subject matter, such as that in a claim, to the specified
materials or steps and those that do not materially affect the
basic and novel characteristics of the subject matter.
[0057] "Disposable" is used in its ordinary sense to mean an
article that is disposed or discarded after a limited number of
usage events over varying lengths of time, such as less than about
20 events, or less than about 10 events, or less than about 5
events, or less than about 2 events.
[0058] "Diaper" refers to an absorbent article generally worn by
infants and incontinent persons about the lower torso so as to
encircle the waist and legs of the wearer and that is specifically
adapted to receive and contain urinary and fecal waste. As used
herein, term "diaper" also includes "pants" which is defined
below.
[0059] "Fiber" and "filament" are used interchangeably.
[0060] "Hydrophilic" describes fibers or surfaces of fibers, which
are wettable by aqueous fluids (e.g. aqueous body fluids) deposited
on these fibers. Hydrophilicity and wettability are typically
defined in terms of contact angle and the strike through time of
the fluids, for example through a nonwoven fabric. This is
discussed in detail in the American Chemical Society publication
entitled "Contact angle, wettability and adhesion", edited by
Robert F. Gould (Copyright 1964). A fiber or surface of a fiber is
said to be wetted by a fluid (i.e. hydrophilic) when either the
contact angle between the fluid and the fiber, or its surface, is
less than 90.degree., or when the fluid tends to spread
spontaneously across the surface of the fiber, both conditions are
normally co-existing. Conversely, a fiber or surface of the fiber
is considered to be hydrophobic if the contact angle is greater
than 90.degree. and the fluid does not spread spontaneously across
the surface of the fiber.
[0061] A "nonwoven" is a manufactured sheet, web or batt of
directionally or randomly orientated fibers, bonded by friction,
and/or cohesion and/or adhesion, excluding paper and products which
are woven, knitted, tufted, stitch-bonded incorporating binding
yarns or filaments, or felted by wet-milling, whether or not
additionally needled. The fibers may be of natural or man-made
origin and may be staple or continuous filaments or be formed in
situ. Commercially available fibers have diameters ranging from
less than about 0.001 mm to more than about 0.2 mm and they come in
several different forms: short fibers (known as staple, or
chopped), continuous single fibers (filaments or monofilaments),
untwisted bundles of continuous filaments (tow), and twisted
bundles of continuous filaments (yarn). Nonwoven fabrics can be
formed by many processes such as meltblowing, spunbonding, solvent
spinning, electrospinning, and carding. The basis weight of
nonwoven fabrics is usually expressed in grams per square meter
(gsm).
[0062] "Pant" or "training pant", as used herein, refer to
disposable garments having a waist opening and leg openings
designed for infant or adult wearers. A pant may be placed in
position on the wearer by inserting the wearer's legs into the leg
openings and sliding the pant into position about a wearer's lower
torso. A pant may be preformed by any suitable technique including,
but not limited to, joining together portions of the article using
refastenable and/or non-refastenable bonds (e.g., seam, weld,
adhesive, cohesive bond, fastener, etc.). A pant may be preformed
anywhere along the circumference of the article (e.g., side
fastened, front waist fastened). While the terms "pant" or "pants"
are used herein, pants are also commonly referred to as "closed
diapers," "prefastened diapers," "pull-on diapers," "training
pants," and "diaper-pants". Suitable pants are disclosed in U.S.
Pat. No. 5,246,433, issued to Hasse, et al. on Sep. 21, 1993; U.S.
Pat. No. 5,569,234, issued to Buell et al. on Oct. 29, 1996; U.S.
Pat. No. 6,120,487, issued to Ashton on Sep. 19, 2000; U.S. Pat.
No. 6,120,489, issued to Johnson et al. on Sep. 19, 2000; U.S. Pat.
No. 4,940,464, issued to Van Gompel et al. on Jul. 10, 1990; U.S.
Pat. No. 5,092,861, issued to Nomura et al. on Mar. 3, 1992; U.S.
Patent Publication No. 2003/0233082 A1, entitled "Highly Flexible
And Low Deformation Fastening Device", filed on Jun. 13, 2002; U.S.
Pat. No. 5,897,545, issued to Kline et al. on Apr. 27, 1999; U.S.
Pat. No. 5,957,908, issued to Kline et al on Sep. 28, 1999.
[0063] "Substantially cellulose free" is used herein to describe an
article, such as an absorbent core, that contains less than about
10% by weight cellulosic fibers, less than about 5% cellulosic
fibers, less than about 1% cellulosic fibers, no cellulosic fibers,
or no more than an immaterial amount of cellulosic fibers. An
immaterial amount of cellulosic material would not materially
affect the thinness, flexibility, or absorbency of an absorbent
core.
[0064] "Substantially continuously distributed", as used herein,
refers to absorbent particulate polymer material that is arranged
across the absorbent particulate polymer material area. Optionally,
the absorbent particulate polymer material may be arranged such
that the substrate layers do not touch in zones 122 and 124. In one
embodiment, the substrate layers may touch in the peripheral areas
outside the absorbent particulate polymer material area. It is
important to note that the thermoplastic material used in the
presently described disposable absorbent articles does not
interrupt the substantially continuously distributed absorbent
particulate polymer material. Thus, the substantially continuously
distributed absorbent particulate polymer material includes the
thermoplastic material.
[0065] "Substantially free of absorbent particulate polymer
material", as used herein, refers to the one or more cavities of
the absorbent core having an area (in plan view) in which the
absorbent particulate polymer material is present in an amount not
exceeding 10% of the basis weight of absorbent particulate polymer
material in the area of the absorbent core surrounding the one or
more cavities.
[0066] "Thickness" and "caliper" are used herein
interchangeably.
Absorbent Articles
[0067] FIG. 1 is a plan view of a diaper 10 according to a certain
embodiment of the present invention. The diaper 10 is shown in its
flat out, uncontracted state (i.e., without elastic induced
contraction) and portions of the diaper 10 are cut away to more
clearly show the underlying structure of the diaper 10. A portion
of the diaper 10 that contacts a wearer is facing the viewer in
FIG. 1. The diaper 10 generally may comprise a chassis 12 and an
absorbent core 14 disposed in the chassis.
[0068] The chassis 12 of the diaper 10 in FIG. 1 may comprise the
main body of the diaper 10. The chassis 12 may comprise an outer
covering 16 including a top sheet 18, which may be liquid pervious,
and/or a back sheet 20, which may be liquid impervious. The
absorbent core 14 may be encased between the top sheet 18 and the
back sheet 20. The chassis 12 may also include side panels 22,
elasticized leg cuffs 24, and an elastic waist feature 26.
[0069] The leg cuffs 24 and the elastic waist feature 26 may each
typically comprise elastic members 28. One end portion of the
diaper 10 may be configured as a first waist region 30 of the
diaper 10. An opposite end portion of the diaper 10 may be
configured as a second waist region 32 of the diaper 10. An
intermediate portion of the diaper 10 may be configured as a crotch
region 34, which extends longitudinally between the first and
second waist regions 30 and 32. The waist regions 30 and 32 may
include elastic elements such that they gather about the waist of
the wearer to provide improved fit and containment (elastic waist
feature 26). The crotch region 34 is that portion of the diaper 10
which, when the diaper 10 is worn, is generally positioned between
the wearer's legs.
[0070] The diaper 10 is depicted in FIG. 1 with its central
longitudinal axis 36 and its transverse axis 38. The periphery 40
of the diaper 10 is defined by the outer edges of the diaper 10 in
which the longitudinal edges 42 run generally parallel to the
longitudinal axis 36 of the diaper 10 and the end edges 44 run
between the longitudinal edges 42 generally parallel to the
transverse axis 38 of the diaper 10. The chassis 12 may also
comprise a fastening system, which may include at least one
fastening member 46 and at least one stored landing zone 48.
[0071] The diaper 10 may also include such other features as are
known in the art including front and rear ear panels, waist cap
features, elastics and the like to provide better fit, containment
and aesthetic characteristics. Such additional features are well
known in the art and are e.g., described in U.S. Pat. No. 3,860,003
and U.S. Pat. No. 5,151,092.
[0072] In order to keep the diaper 10 in place about the wearer, at
least a portion of the first waist region 30 may be attached by the
fastening member 46 to at least a portion of the second waist
region 32 to form leg opening(s) and an article waist. When
fastened, the fastening system carries a tensile load around the
article waist. The fastening system may allow an article user to
hold one element of the fastening system, such as the fastening
member 46, and connect the first waist region 30 to the second
waist region 32 in at least two places. This may be achieved
through manipulation of bond strengths between the fastening device
elements.
[0073] According to certain embodiments, the diaper 10 may be
provided with a re-closable fastening system or may alternatively
provided in the form of a pant-type diaper. When the absorbent
article is a diaper, it may comprise a re-closable fastening system
joined to the chassis for securing the diaper to a wearer. When the
absorbent article is a pant-type diaper, the article may comprise
at least two side panels joined to the chassis and to each other to
form a pant. The fastening system and any component thereof may
include any material suitable for such a use, including but not
limited to plastics, films, foams, nonwoven webs, woven webs,
paper, laminates, fiber reinforced plastics and the like, or
combinations thereof. In certain embodiments, the materials making
up the fastening device may be flexible. The flexibility may allow
the fastening system to conform to the shape of the body and thus,
reduce the likelihood that the fastening system will irritate or
injure the wearer's skin.
[0074] For unitary absorbent articles, the chassis 12 and absorbent
core 14 may form the main structure of the diaper 10 with other
features added to form the composite diaper structure. While the
top sheet 18, the back sheet 20, and the absorbent core 14 may be
assembled in a variety of well-known configurations, certain diaper
configurations are described generally in U.S. Pat. No. 5,554,145
to Roe et al.; U.S. Pat. No. 5,569,234 to Buell et al.; and U.S.
Pat. No. 6,004,306 to Robles et al. on Dec. 21, 1999.
[0075] The top sheet 18 in FIG. 1 may be fully or partially
elasticized or may be foreshortened to provide a void space between
the top sheet 18 and the absorbent core 14. Exemplary structures
including elasticized or foreshortened top sheets are described in
more detail in U.S. Pat. No. 5,037,416 to Allen et al.; and U.S.
Pat. No. 5,269,775 to Freeland et al.
[0076] The back sheet 20 may be joined with the top sheet 18. The
back sheet 20 may prevent the exudates absorbed by the absorbent
core 14 and contained within the diaper 10 from soiling other
external articles that may contact the diaper 10, such as bed
sheets and undergarments. In certain embodiments, the back sheet 20
may be substantially impervious to liquids (e.g., urine) and
comprise a laminate of a nonwoven and a thin plastic film such as a
thermoplastic film having a thickness of about 0.012 mm (0.5 mil)
to about 0.051 mm (2.0 mils). Suitable back sheet films include
those manufactured by Tredegar Industries Inc. (Terre Haute, Ind.)
and sold under the trade names X15306, X10962, and X10964. Other
suitable back sheet materials may include breathable materials that
permit vapors to escape from the diaper 10 while still preventing
exudates from passing through the back sheet 10. Exemplary
breathable materials may include materials such as woven webs,
nonwoven webs, composite materials such as film-coated nonwoven
webs, and microporous films such as manufactured by Mitsui Toatsu
Co. (Japan) under the designation ESPOIR NO and by EXXON Chemical
Co. (Bay City, Tex.) under the designation EXXAIRE.
[0077] Suitable breathable composite materials comprising polymer
blends are available from Clopay Corporation (Cincinnati, Ohio)
under the name HYTREL blend P18-3097. Such breathable composite
materials are described in PCT Application No. WO 95/16746,
published Jun. 22, 1995 in the name of E.I. DuPont. Other
breathable back sheets including nonwoven webs and apertured formed
films are described in U.S. Pat. No. 5,571,096 to Dobrin et al.
[0078] FIG. 2 shows a cross section of FIG. 1 taken along the
sectional line 2-2 of FIG. 1. Starting from the wearer facing side,
the diaper 10 may comprise the top sheet 18, the components of the
absorbent core 14, and the back sheet 20. According to a certain
embodiment, diaper 10 may also comprise an acquisition system 50
disposed between the liquid permeable top sheet 18 and a wearer
facing side of the absorbent core 14. The acquisition system 50 may
be in direct contact with the absorbent core. The acquisition
system 50 may comprise a single layer or multiple layers, such as
an upper acquisition layer 52 facing the towards the wearer's skin
and a lower acquisition 54 layer facing the garment of the wearer.
According to a certain embodiment, the acquisition system 50 may
function to receive a surge of liquid, such as a gush of urine, and
quickly absorb the liquid and distribute it across the absorbent
core 14 so that the absorbent core absorbs the liquid before the
liquid flows beyond the absorbent layer 14 and out of the diaper
10. In other words, the acquisition system 50 may serve as a
temporary reservoir for liquid until the absorbent core 14 can
absorb the liquid.
[0079] In a certain embodiment, the acquisition system 50 may
comprise chemically cross-linked cellulosic fibers. Such
cross-linked cellulosic fibers may have desirable absorbency
properties. Exemplary chemically cross-linked cellulosic fibers are
disclosed in U.S. Pat. No. 5,137,537 which is incorporated herein
by reference. In certain embodiments, the chemically cross-linked
cellulosic fibers have between about 0.5 mole % and about 10.0 mole
% of a C.sub.2 to C.sub.9 polycarboxylic cross-linking agent or
between about 1.5 mole % and about 6.0 mole % of a C.sub.2 to
C.sub.9 polycarboxylic cross-linking agent. Citric acid is an
exemplary cross-linking agent. In other embodiments, polyacrylic
acids may be used. Further, according to certain embodiments, the
cross-linked cellulosic fibers have a water retention value of
about 25 to about 60, or about 28 to about 50, or about 30 to about
45. A method for determining water retention value is disclosed in
U.S. Pat. No. 5,137,537. According to certain embodiments, the
cross-linked cellulosic fibers may be crimped, twisted, or curled,
or a combination thereof including crimped, twisted, and
curled.
[0080] In a certain embodiment, one or both of the upper and lower
acquisition layers 52 and 54 may comprise a non-woven, which may be
hydrophilic. Further, according to a certain embodiment, one or
both of the upper and lower acquisition layers 52 and 54 may
comprise the chemically cross-linked cellulosic fibers, which may
or may not form part of a nonwoven material. According to an
exemplary embodiment, the upper acquisition layer 52 may comprise a
nonwoven, without the cross-linked cellulosic fibers, and the lower
acquisition layer 54 may comprise the chemically cross-linked
cellulosic fibers. Further, according to an embodiment, the lower
acquisition layer 54 may comprise the chemically cross-linked
cellulosic fibers mixed with other fibers such as natural or
synthetic polymeric fibers. According to exemplary embodiments,
such other natural or synthetic polymeric fibers may include high
surface area fibers, thermoplastic binding fibers, polyethylene
fibers, polypropylene fibers, PET fibers, rayon fibers, lyocell
fibers, and mixtures thereof. According to a one embodiment, the
lower acquisition layer 54 has a total dry weight, the cross-linked
cellulosic fibers are present on a dry weight basis in the first
acquisition layer in an amount from about 30% to about 95% by
weight of the lower acquisition layer 54, and the other natural or
synthetic polymeric fibers are present on a dry weight basis in the
lower acquisition layer 54 in an amount from about 70% to about 5%
by weight of the lower acquisition layer 54. According to another
embodiment, the cross-linked cellulosic fibers are present on a dry
weight basis in the first acquisition layer in an amount from about
80% to about 90% by weight of the lower acquisition layer 54, and
the other natural or synthetic polymeric fibers are present on a
dry weight basis in the lower acquisition layer 54 in an amount
from about 20% to about 10% by weight of the lower acquisition
layer 54.
[0081] According to a certain embodiment, the lower acquisition
layer 54 desirably has a high fluid uptake capability. Fluid uptake
is measured in grams of absorbed fluid per gram of absorbent
material and is expressed by the value of "maximum uptake." A high
fluid uptake corresponds therefore to a high capacity of the
material and is beneficial, because it ensures the complete
acquisition of fluids to be absorbed by an acquisition material.
According to exemplary embodiments, the lower acquisition layer 54
has a maximum uptake of about 10 g/g.
[0082] A relevant attribute of the lower acquisition layer 54 is
its Medium Desorption Pressure (MDP) which is related to
acquisition speed. The MDP is a measure of the capillary pressure
that is required to dewater the lower acquisition layer 54 to about
50% of its capacity at 0 cm capillary suction height as derived
from the Capillary Sorption test. Generally, a relatively lower MDP
may be useful. The lower MDP may allow the lower acquisition layer
54 to more efficiently drain the acquisition material and utilize
more of its capillary suction to distribute liquid to the absorbent
core 14. Without wishing to be bound by theory, a given
distribution material may have a definable capillary suction. The
ability of the lower acquisition layer 54 to move liquid vertically
via capillary forces will be directly impacted by the opposing
capillary forces associated desorption. Minimizing these capillary
forces may positively impact the performance of the lower
acquisition layer 54. However, in a certain embodiment the lower
acquisition layer 54 may also have adequate capillary absorption
suction in order to drain the layers above (upper acquisition layer
52 and top sheet 18, in particular) and to temporarily hold liquid
until the liquid can be partitioned away by the absorbent core
components. Therefore, in a certain embodiment, the lower
acquisition layer 54 may have a minimum MDP which should correspond
to a height of greater than 5 cm. Further, according to exemplary
embodiments, the lower acquisition layer 54 has an MDP value of
less than about 20.5 cm H.sub.2O, or less than about 19 cm
H.sub.2O, or less than about 18 cm H.sub.2O to provide for fast
acquisition.
[0083] The methods for determining MDP and maximum uptake are
disclosed in U.S. Patent Application Publication No. 2007/0118087
A1 (Flohr et al.), the disclosure of which is incorporated herein
by reference.
[0084] For example, according to one embodiment, the lower
acquisition layer 54 may comprise 7 about 0% by weight of
chemically cross-linked cellulose fibers, about 10% by weight
polyester (PET), and about 20% by weight untreated pulp fibers.
According to a second embodiment, the lower acquisition layer 54
may comprise about 70% by weight chemically cross-linked cellulose
fibers, about 20% by weight lyocell fibers, and about 10% by weight
PET fibers. According to a third embodiment, the lower acquisition
layer 54 may comprise about 68% by weight chemically cross-linked
cellulose fibers, about 16% by weight untreated pulp fibers, and
about 16% by weight PET fibers.
[0085] Suitable non-woven materials for the upper and lower
acquisition layers 52 and 54 include, but are not limited to SMS
material, comprising a spunbonded, a melt-blown and a further
spunbonded layer. In certain embodiments, permanently hydrophilic
non-wovens, and in particular, nonwovens with durably hydrophilic
coatings are desirable. Another suitable embodiment comprises a
SMMS-structure. In certain embodiments, the non-wovens are
porous.
[0086] In certain embodiments, suitable non-woven materials may
include, but are not limited to, synthetic fibers, such as PE, PET,
and PP. As polymers used for nonwoven production may be inherently
hydrophobic, they may be coated with hydrophilic coatings. One way
to produce nonwovens with durably hydrophilic coatings, is via
applying a hydrophilic monomer and a radical polymerization
initiator onto the nonwoven, and conducting a polymerization
activated via UV light resulting in monomer chemically bound to the
surface of the nonwoven as described in U.S. Patent Application
Publication No. 2004/0097895 A1 (Busam et al.). Another way to
produce nonwovens with durably hydrophilic coatings is to coat the
nonwoven with hydrophilic nanoparticles as described in U.S. Pat.
No. 7,112,621 to Rohrbaugh et al. and PCT Application Publication
WO 02/064877.
[0087] Typically, nanoparticles have a largest dimension of below
750 nm. Nanoparticles with sizes ranging form 2 to 750 nm may be
economically produced. An advantage of nanoparticles is that many
of them can be easily dispersed in water solution to enable coating
application onto the nonwoven, they typically form transparent
coatings, and the coatings applied from water solutions are
typically sufficiently durable to exposure to water. Nanoparticles
can be organic or inorganic, synthetic or natural. Inorganic
nanoparticles generally exist as oxides, silicates, carbonates.
Typical examples of suitable nanoparticles are layered clay
minerals (e.g., LAPONITE.TM. from Southern Clay Products, Inc.
(USA), and Boehmite alumina (e.g., Disperal P2.TM. from North
American Sasol. Inc.). According to a certain embodiment, a
suitable nanoparticle coated non-woven is that disclosed in U.S.
Patent Application Publication No. 2004/0158212 (Ponomarenko et
al.).
[0088] Further useful non-wovens are described in U.S. Pat. No.
6,645,569 to Cramer et al., U.S. Pat. No. 6,863,933 to Cramer et
al., U.S. Pat. No. 7,112,621 to Rohrbaugh et al., U.S. Patent
Application Publication No. 2003/0148684 (Cramer et al.), and U.S.
Patent Application Publication No. 2005/0008839 (Cramer et al.)
[0089] In some cases, the nonwoven surface can be pre-treated with
high energy treatment (corona, plasma) prior to application of
nanoparticle coatings. High energy pre-treatment typically
temporarily increases the surface energy of a low surface energy
surface (such as PP) and thus enables better wetting of a nonwoven
by the nanoparticle dispersion in water.
[0090] Notably, permanently hydrophilic non-wovens are also useful
in other parts of an absorbent article. For example, top sheets and
absorbent core layers comprising permanently hydrophilic non-wovens
as described above have been found to work well.
[0091] According to a certain embodiment, the upper acquisition
layer 52 may comprise a material that provides good recovery when
external pressure is applied and removed. Further, according to a
certain embodiment, the upper acquisition layer 52 may comprise a
blend of different fibers selected, for example from the types of
polymeric fibers described above. In some embodiments, at least a
portion of the fibers may exhibit a spiral-crimp which has a
helical shape. In some embodiments, the upper acquisition layer 52
may comprise fibers having different degrees or types of crimping,
or both. For example, one embodiment may include a mixture of
fibers having about 8 to about 12 crimps per inch (cpi) or about 9
to about 10 cpi, and other fibers having about 4 to about 8 cpi or
about 5 to about 7 cpi. Different types of crimps include, but are
not limited to, a 2D crimp or "flat crimp" and a 3D or
spiral-crimp. According to a certain embodiment, the fibers may
include bi-component fibers, which are individual fibers each
comprising different materials, usually a first and a second
polymeric material. It is believed that the use of side-by-side
bi-component fibers is beneficial for imparting a spiral-crimp to
the fibers.
[0092] The upper acquisition layer 52 may be stabilized by a latex
binder, for example a styrene-butadiene latex binder (SB latex), in
a certain embodiment. Processes for obtaining such lattices are
known, for example, from EP 149 880 (Kwok) and U.S. Patent
Application Publication No. 2003/0105190 (Diehl et al.). According
to a certain embodiment, SB lattices may be obtained using more
than about 10 weight % of a mono-, or bi-carboxylic acid, and will
herein be referred to as having a carboxylation level of more than
about 10%. Further, according to a certain embodiment, SB lattices
may have a carboxylation level from about 10% to about 25%, for
example about 10% to about 20%. In certain embodiments, the binder
may be present in the upper acquisition layer 52 in excess of about
12%, about 14% or about 16% by weight. For certain embodiments, SB
latex is available under the trade name GENFLO.TM. 3160 (OMNOVA
Solutions Inc.; Akron, Ohio).
[0093] The absorbent core 14 in FIGS. 1-10 generally is disposed
between the top sheet 18 and the back sheet 20 and comprises two
layers, a first absorbent layer 60 and a second absorbent layer 62.
As best shown in FIG. 3, the first absorbent layer 60 of the
absorbent core 14 comprises a substrate 64, an absorbent
particulate polymer material 66 on the substrate 64, and a
thermoplastic composition 68 on the absorbent particulate polymer
material 66 and at least portions of the first substrate 64 as an
adhesive for covering and immobilizing the absorbent particulate
polymer material 66 on the first substrate 64. According to another
embodiment illustrated in FIG. 4, the first absorbent layer 60 of
the absorbent core 14 may also include a cover layer 70 on the
thermoplastic composition 68. The absorbent core 14 may also
include another layer 69 of thermoplastic composition on the first
substrate 64 for anchoring the absorbent particulate polymer
material 66 to the first substrate 64.
[0094] Likewise, as best illustrated in FIG. 2, the second
absorbent layer 62 of the absorbent core 14 may also include a
substrate 72, a thermoplastic composition 73 on the substrate, an
absorbent particulate polymer material 74 adhered to the second
substrate 72 with the thermoplastic composition, and a
thermoplastic composition 68 on the absorbent particulate polymer
material 74 and at least a portion of the second substrate 72 or
first layer of thermoplastic composition for immobilizing the
absorbent particulate polymer material 74 on the second substrate
72. Although not illustrated, the second absorbent layer 62 may
also include a cover layer such as the cover layer 70 illustrated
in FIG. 4.
[0095] The substrate 64 of the first absorbent layer 60 may be
referred to as a dusting layer and has a first surface 78 which
faces the back sheet 20 of the diaper 10 and a second surface 80
which faces the absorbent particulate polymer material 66.
Likewise, the substrate 72 of the second absorbent layer 62 may be
referred to as a core cover and has a first surface 82 facing the
top sheet 18 of the diaper 10 and a second surface 84 facing the
absorbent particulate polymer material 74. The first and second
substrates 64 and 72 may be adhered to one another with adhesive
about the periphery to form an envelope about the absorbent
particulate polymer materials 66 and 74 to hold the absorbent
particulate polymer material 66 and 74 within the absorbent core
14.
[0096] According to a certain embodiment, the substrates 64 and 72
of the first and second absorbent layers 60 and 62 may be a
non-woven material, such as those nonwoven materials described
above. In certain embodiments, the non-wovens are porous and in one
embodiment has a pore size of about 32 microns.
[0097] As illustrated in FIGS. 1-8, the absorbent particulate
polymer material 66 and 74 may be deposited on the respective
substrates 64 and 72 of the first and second absorbent layers 60
and 62 in small and large clusters 90 and 91 of particles to form a
grid pattern 92 comprising land areas 94 and junction areas 96
between the land areas 94. The junction areas 96 in the grid
pattern 92 contain little or no absorbent particulate polymer
material 66 and 74. The land areas 94 and junction areas 96 can
have a variety of shapes including, but not limited to, circular,
oval, square, rectangular, triangular, and the like.
[0098] The small clusters 90 of absorbent particulate polymer
material 66 and 74 are thinner than the large clusters 91 of
absorbent particulate polymer material 66 and 74 and impart a lower
basis weight of absorbent particulate polymer material 66 and 74 to
the area of the absorbent core 14 in which the small clusters 90
are located. Likewise, the large clusters 91 of absorbent
particulate polymer material 66 and 74 are thicker than the small
clusters 90 of absorbent particulate polymer material 66 and 74 and
impart a higher basis weight of absorbent particulate polymer
material 66 and 74 to the area of the absorbent core 14 in which
the large clusters 91 are located. This creates a varied profile of
absorbent particulate polymer material across the absorbent core
14. At least one cavity can be created in the absorbent core by a
combination of machine direction profiling and cross-machine
direction profiling, so as to create at least one region having
relatively little or no absorbent particulate polymer material
(e.g., a low basis weight region) bounded by a region of relatively
more absorbent particulate polymer material (i.e., a high basis
weight region).
[0099] As shown in FIG. 8, the absorbent core 14 has a longitudinal
axis 100 extending from a rear end 102 to a front end 104 and a
transverse axis 106 perpendicular to the longitudinal axis 100
extending from a first edge 108 to a second edge 110. The grid
pattern 92 of absorbent particulate polymer material clusters 90
and 91 is arranged on the substrates 64 and 72 of the respective
absorbent layers 60 and 62 such that the grid pattern 92 formed by
the arrangement of land areas 94 and junction areas 96 forms a
pattern angle 112. While the pattern angle 112 may be such that the
grid pattern 92 is parallel with the first and second edges 108 and
110 of the absorbent core 14, the pattern angle 112 may be greater
than 0, or 15 to 30 degrees, or from about 5 to about 85 degrees,
or from about 10 to about 60 degrees, or from about 15 to about 30
degrees from the longitudinal axis 100 of the absorbent core
14.
[0100] As best seen in FIGS. 7 and 8, the first and second layers
60 and 62 may be combined to form the absorbent core 14. The
absorbent core 14 has an absorbent particulate polymer material
area 114 bounded by a pattern length 116 and a pattern width 118.
The extent and shape of the absorbent particulate polymer material
area 114 may vary depending on the desired application of the
absorbent core 14 and the particular absorbent article in which it
may be incorporated. In a certain embodiment, however, the
absorbent particulate polymer material area 114 may extend
substantially entirely across the absorbent core 14, such as is
illustrated in FIG. 8.
[0101] The size of the land areas 94 in the grid patterns 92 may
vary. According to certain embodiments, the width of the land areas
94 in the grid patterns 92 ranges from about 8 mm to about 12 mm.
In a certain embodiment, the width of the land areas 94 is about 10
mm. The junction areas 96, on the other hand, in certain
embodiments, have a width or larger span of less than about 5 mm,
less than about 3 mm, less than about 2 mm, less than about 1.5 mm,
less than about 1 mm, or less than about 0.5 mm.
[0102] The first and second absorbent layers 60 and 62 may be
combined together to form the absorbent core 14 such that the grid
patterns 92 of the respective first and second absorbent layers 62
and 64 are offset from one another along the length and/or width of
the absorbent core 14. The respective grid patterns 92 may be
offset such that the absorbent particulate polymer material 66 and
74 is substantially continuously distributed across the absorbent
particulate polymer area 114. In a certain embodiment, absorbent
particulate polymer material 66 and 74 is substantially
continuously distributed across the absorbent particulate polymer
material area 114 despite the individual grid patterns 92
comprising absorbent particulate polymer material 66 and 74
discontinuously distributed across the first and second substrates
64 and 72 in clusters 90 and 91. In a certain embodiment, the grid
patterns may be offset such that the land areas 94 of the first
absorbent layer 60 face the junction areas 96 of the second
absorbent layer 62 and the land areas of the second absorbent layer
62 face the junction areas 96 of the first absorbent layer 60. When
the land areas 94 and junction areas 96 are appropriately sized and
arranged, the resulting combination of absorbent particulate
polymer material 66 and 74 is a substantially continuous layer of
absorbent particular polymer material across the absorbent
particulate polymer material area 114 of the absorbent core 14. In
a certain embodiment, respective grid patterns 92 of the first and
second absorbent layer 60 and 62 may be substantially the same.
[0103] In a certain embodiment as illustrated in FIGS. 1-8, the
amount of absorbent particulate polymer material 66 and 74 may vary
along the width 118 of the grid pattern 92 substantially
perpendicularly to the longitudinal axis 36 of disposable absorbent
diaper 10. In a certain embodiment, the grid pattern may be divided
into absorbent zones 120, 121 and 122, or another number of zones,
in which the amount of absorbent particulate polymer material 66
and 74 per unit area of the absorbent core 14 varies from zone to
zone. The amount of absorbent particulate polymer material 66 and
74 may, in a certain embodiment, gradually transition from one of
the plurality of absorbent zones 120, 121, and 122 to another. This
gradual transition in amount of absorbent particulate polymer
material 66 and 74 may reduce the possibility of cracks forming in
the absorbent core 14.
[0104] In the embodiment illustrated in FIGS. 1-8 the first and
second side absorbent zones 120 and 122 are spaced from one another
and extend substantially parallel to the longitudinal axis 36 of
the diaper 10 and the central absorbent zone 121 extends
substantially along the longitudinal axis and between the first and
second side absorbent zones 120 and 122. The absorbent particulate
polymer material 66 and 74 present in the first and second side
absorbent zones 120 and 122 of the absorbent core 14 has a basis
weight greater than the basis weight of the absorbent particulate
polymer material 66 and 74 present in the central absorbent zone
121 of the absorbent core 14.
[0105] In alternative embodiments, the absorbent particulate
polymer material 66 and 74 in the central absorbent zone 121 of the
absorbent core 14 has a higher basis weight than in the first and
second side absorbent zones 120 and 122 of the absorbent core 14.
When the absorbent core 14 according to this embodiment is
subjected to a flush of liquid directed at the central absorbent
zone 121, liquid that flows over and past the central absorbent
zone 121 contacts the side absorbent zones 120 and 122. The first
and second side absorbent zones 120 and 122 have more absorbent
particulate polymer material and have greater capacity to absorb
such liquid and deter flow of the liquid beyond the side absorbent
zones 120 and 122 to prevent leakage.
[0106] Although the embodiment illustrated in FIGS. 1-8 has only
three absorbent zones 120, 121, and 122, the absorbent diaper 10
may include any number of absorbent zones having varying basis
weights of absorbent particulate polymer. Furthermore, in other
embodiments, the absorbent particulate polymer material 66 and 74
may be varied in different patterns such as by placing more
absorbent particulate polymer material in the central absorbent
zone 121 than in the side absorbent zone 120 and 122 or alternating
areas of greater and lesser amounts of absorbent particulate
polymer material per unit area of the absorbent core.
[0107] Another embodiment of an absorbent core 14' is illustrated
in FIG. 9 and the basis weight of the absorbent particulate polymer
material 66 and 74 varies across the absorbent core 14' in a
direction substantially parallel to the longitudinal axis 36. This
absorbent core 14' comprises first and second end absorbent zones
123 and 124, spaced form one another and extending substantially
perpendicular to the longitudinal axis of the absorbent core, and a
central absorbent zone 125, extending substantially along the
longitudinal axis 36 and between the first and second end absorbent
zones 123 and 124. The basis weight of the absorbent particulate
polymer material in the absorbent end zones 123 and 124 of the
absorbent core 14' is greater than in the central absorbent zone
125 of the absorbent core 14'. When the absorbent core 14'
illustrated in FIG. 9 is subjected to a flush of liquid directed at
the central absorbent zone 125, liquid that flows past the central
absorbent zone 125 encounters end absorbent zones 123 and 124 which
have greater capacity to absorb and hold such liquid.
[0108] Although the absorbent core 14' illustrated in FIG. 9 has
only three absorbent zones 123, 124, and 125, the absorbent core
14' may include any number of absorbent zones arranged in a variety
of different patterns of varying absorbent particulate polymer
material basis weights. In other embodiments, the basis weight of
the absorbent particulate polymer material 66 and 74 in the central
absorbent zone 125 may be greater than in the end absorbent zones
123 and 124 or the absorbent core 14' may include a multitude of
alternating absorbent zones of varying absorbent particulate
polymer material basis weights.
[0109] Another embodiment of an absorbent core 14'' is illustrated
in FIG. 10 and comprises first and second side absorbent zones 120'
and 122' spaced from one another and extending substantially
parallel to the longitudinal axis 36, first and second end
absorption zones 123' and 124' spaced from one another and
extending substantially perpendicularly to the longitudinal axis
36, and a central portion 121' and 125' extending substantially
along the longitudinal axis 36 and between the first and second
side absorbent zones 120' and 122' and between the first and second
end absorbent zones 123' and 124'. The basis weight of the
absorbent particulate polymer material 66 and 74 in the first and
second side portions 120' and 122' of the absorbent core 14'' is
greater than the basis weight of the absorbent particulate polymer
material 66 and 74 in the central portion 121' and 125' of the
absorbent core 14'' and the basis weight of the absorbent
particulate polymer material 66 and 74 in the first and second end
portions 123' and 124' of the absorbent core 14'' is greater than
the basis weight of the absorbent particulate polymer material 66
and 74 in the central portion 121' and 125' of the absorbent core
14''. When the absorbent core 14'' illustrated in FIG. 10 is
subjected to a rush of liquid directed at the central absorbent
zone 121' and 125', liquid that flows past the central absorbent
zone 121' and 125' encounters and may be absorbed by the side
absorbent zones 120' and 122' and the end absorbent zones 123' and
124' which all have greater absorbent particulate polymer material
basis weights. As with the other embodiments described hereinabove,
it should be understood that the absorbent particulate polymer
material 66 and 74 may be arranged in a variety of different
patterns of varying absorbent particulate polymer material basis
weights. In one such embodiment, the central absorbent zone 121'
and 125' may have a higher absorbent particulate polymer material
basis weight than the side absorbent zones 120' and 122' and the
end absorbent zones 123' and 124'.
[0110] A certain embodiment of an absorbent core 214 is illustrated
in FIGS. 11-12. Absorbent core 214 may be constructed like
absorbent cores 14, 14', or 14'' described herein. The absorbent
core 214 comprises at least one cavity 215, which is sized and
positioned to receive fecal matter, for example to contain and
direct the fecal matter away from the skin of a person wearing a
disposable absorbent article which comprises the absorbent core
214. In certain embodiments, the void volume of the cavity (or
total volume of multiple cavities) may be from 2 ml to about 20 ml
when the absorbent core 214 is in a dry state. When the absorbent
core 214 becomes wet, expansion of the absorbent particulate
polymer material 66 and 74 swells, causing the cavity volume to
increase. For example, the void volume of the cavity may be from
about 25 ml to 35 ml (in use, when fluid is present), e.g., about
30 ml. In one embodiment, the cavity volume may be from about 50 to
about 70 ml when the absorbent core is in a saturated state.
[0111] The cavity may be defined at least about its perimeter by
the absorbent particulate polymer material 66 and 74 (with
associated first and second substrates 64 and 72 and thermoplastic
material 68 and 76). For example, the cavity may be formed by CD
and MD profiling of the core, creating an area with a lower basis
weight absorbent particulate polymer material, or no absorbent
particulate polymer material, as compared to surrounding areas of
the absorbent core. Generally, the greater the basis weight
difference between the regions, the greater the depth of the
cavity. The volume of the cavity may increase upon swelling of the
absorbent particulate polymer material, i.e., after at least one
gush of liquid occurs and is taken up by the absorbent particulate
polymer material.
[0112] In a particular embodiment, the region defining the cavity
may be substantially free of absorbent particulate polymer material
66 and 74. In one embodiment, the absorbent particulate polymer
material that would have been located in the region of the cavity
may be redistributed in the absorbent core in the region about the
walls or perimeter of the cavity. In this way, the total capacity
of the absorbent core is substantially maintained as compared to an
absorbent core without such a cavity. One embodiment of such an
absorbent core is illustrated in FIG. 28, as detailed below.
[0113] In one embodiment, the first channel of the cavity is
located in the absorbent core along the central longitudinal axis
of the diaper or pant at a position which is positioned at the
so-called "poo point." That is, when the diaper or pant is worn by
a wearer, the cavity will be in alignment with a predetermined
region about the anus of the wearer. In one embodiment, the cavity
is located about 10 mm from the anus position, which may work to
direct the bowel movement into the cavity.
[0114] In a certain embodiment, the cavity 215 may include a first
channel 219 elongated in a direction substantially parallel to and
located about the central longitudinal axis 100, and (ii) a second
channel 217 elongated in a direction substantially perpendicular to
the central longitudinal axis 100. In one embodiment, the first and
second channels of the cavity together may form a T-shape, as
illustrated in FIG. 11. In other embodiments, the first and second
channels of the cavity together may form a cross shape, or a
Y-shape. The dimensions of the first channel generally should
create a stable valley between the buttocks, yet provide a channel
for fecal matter; if too wide then the first channel loses
stability and if too narrow then it does not adequately accommodate
the bowel movement. In various embodiments, the first channel 219
of the cavity 215 may have a width from about 10 mm to about 40 mm
and a length from about 10 mm to about 130 mm. In one example, the
first channel 219 of the cavity 215 may have a width of about 20 mm
and may have a length of about 70 mm. The second channel generally
should be dimensioned to provide distribution of the bowel movement
in the cross direction once it has been directed to the back of the
diaper. In other various embodiments, the second channel 217 of the
cavity 215 may have a width from about 10 mm to about 40 mm and a
length from about 10 mm to about 100 mm. In another example, the
second channel of the cavity may have a width of about 30 mm and a
length of about 50 mm. In this T-shaped cavity embodiment, channel
length refers to dimensions in the machine direction, and channel
width refers to dimensions in the cross-machine direction.
[0115] The one or more cavities in the absorbent core may have a
variety of different geometric shapes. Combinations of different
geometric shapes may be used together. The shapes may be connected
or may be discrete from one another. The cavities generally are
sized and located in the absorbent core in a position to facilitate
reception and storage of body exudates, such as fecal matter. The
shapes generally may straddle the longitudinal axis. FIG. 24
illustrates various examples of possible shapes and designs of
cavities 215 in the absorbent core 214, including T-shaped,
triangular, diamond, Y-shaped, combination of semi-circle and
rectangle, oval, trapezoidal, combination of rectangle and
triangle, array of discrete rectangles, array of rectangles
connected with perpendicular bar, circular elliptical, V-shaped,
X-shaped, triangular, array of circles connected with bar,
interrupted triangular, U-shaped, and star-shaped.
[0116] In addition to the basis weight variation, e.g., the CD and
MD profiling, to define the at least one cavity of the absorbent
core, the absorbent particulate polymer material present in the
remaining part of the absorbent core (other than the at least one
cavity) may have a basis weight that varies across other areas of
the absorbent core in a direction substantially perpendicular to
the central longitudinal axis, in a direction substantially
parallel to the central longitudinal axis, or in both directions.
Generally, the absorbent particulate polymer material is
redistributed away from the cavity area, so that the liquid loading
capacity is substantially maintained (versus a conventional flat
absorbent core). In one embodiment, illustrated with reference to
FIG. 11, the absorbent core 214 includes back end and front end
absorbent zones 220a and 220b, respectively. The cavity 215 is
defined in and bounded by central absorbent zones 226 and 224, and
rear transitional absorbent zone 225 disposed therebetween. The
central absorbent zone 226 and front end absorbent zone 220b front
end have a front transitional zone 222 disposed therebetween.
[0117] In an embodiment, the basis weight of absorbent particulate
polymer material in back end and front end absorbent zones 220a and
220b is from about 200 g/cm.sup.2 to about 300 g/cm.sup.2, for
example between about 220 g/cm.sup.2 and 250 g/cm.sup.2, such as
about 233 g/cm.sup.2. In an embodiment, the basis weight of
absorbent particulate polymer material in central absorbent zone
224 is from about 450 g/cm.sup.2 to about 650 g/cm.sup.2, for
example, between about 530 g/cm.sup.2 and 600 g/cm.sup.2, such as
about 568 g/cm.sup.2. In an embodiment, the basis weight of
absorbent particulate polymer material in central absorbent zones
226 is from about 200 g/cm.sup.2 to about 400 g/cm.sup.2, for
example, between about 250 g/cm.sup.2 and 350 g/cm.sup.2, such as
about 284 g/cm.sup.2. In an embodiment, the rear transitional
absorbent zone 225 has a basis weight of absorbent particulate
polymer material between about 300 g/cm.sup.2 and 400 g/cm.sup.2,
such as about 333 g/cm.sup.2. In an embodiment, the front
transitional absorbent zone 222 has a basis weight of absorbent
particulate polymer material between about 200 g/cm.sup.2 and 300
g/cm.sup.2, for example between about 240 g/cm.sup.2 and 280
g/cm.sup.2. Transition zones are optional, and each transition zone
may comprise further gradation within the transition zone.
[0118] The absorbent core 214 may comprise a core cover 72 and a
dusting layer 64 adhered to one another about the periphery of the
absorbent core 214 to form an envelope about the absorbent
particulate polymer materials 66/74 to hold the absorbent
particulate polymer material within the absorbent core 214.
[0119] The cavity may be formed with various constructions. For
example, FIG. 25A illustrates one embodiment in which some of the
absorbent particulate polymer materials 66/74 is present in the
cavity 215, but at a lower basis weight relative to the surrounding
region of the absorbent core 214. In another embodiment, as
illustrated in FIG. 25B, substantially none of the absorbent
particulate polymer materials 66/74 is present in the cavity
215.
[0120] In a particular embodiment, the core cover 72 and the
dusting layer 64 may be adhered to one another about an area
defining the bottom of the at least one cavity 215, as illustrated
in FIG. 25C. In this embodiment, there is no absorbent particulate
polymer material in the bottom of the cavity; however, the
sidewalls of the cavity are still defined by the absorbent
particulate polymer material. This embodiment may aid cavity
shape/volume retention when the absorbent particulate polymer
materials swells and takes additional volume, as it would be
undesirable for the absorbent particulate polymer materials to
swell and thereby reduce the cavity volume available for receiving
and holding a bowel movement. In a certain sub-embodiment, most or
all of layers of the absorbent article construction about the
cavity are connected to the dusting layer, in order to sustain the
cavity. These layers can be glued or bonded by application of heat
and/or pressure.
[0121] In one embodiment, the disposable absorbent article 10 may
further include an acquisition system 50 located between the
absorbent core 214 and the top sheet 18. In one embodiment, the
acquisition system 50 may include an upper acquisition layer 52,
which faces the top sheet 18, and a lower acquisition layer 54,
which faces the absorbent core 214. The upper acquisition layer 52
may or may not cover the at least one cavity 215. The lower
acquisition layer 54 may or may not cover the at least one cavity
215. In another embodiment, the lower acquisition layer may be
omitted. Various constructions of absorbent core and acquisition
layers are possible; examples are illustrated in FIGS. 26-28.
[0122] In one embodiment, the at least one cavity 215 may further
be defined about its perimeter by interior edges of an aperture 216
in the acquisition system 50 and absorbent core 214, as illustrated
in FIG. 26A. In an alternative embodiment, the absorbent core is
substantially planar and the cavity is defined substantially by
interior edges of an aperture 216 in the acquisition system 50, as
illustrated in FIGS. 26B-C. In this embodiment, the void volume
achieved is a function of the thickness of the acquisition system.
In one embodiment, the aperture 216 in the acquisition system 50,
which defines the shape of the cavity, may be made by a stamping
process, adapted from stamping equipment and processes known in the
art. The borders of the acquisition layer may be sealed.
[0123] FIGS. 27A-E illustrate some of the possible configurations
of the acquisition system 50 and absorbent core 214. In FIG. 27A,
the cavity 215 is not covered at all by the acquisition system 50,
which is offset toward the front end of the absorbent core (e.g.,
toward the pee point). In FIG. 27B, the cavity 215 is partially
covered by the acquisition system 50. In FIG. 27C, the cavity 215
is completely covered by the acquisition system 50. In FIG. 27D, a
majority of the (smaller) acquisition system 50 is positioned over
the cavity 215. In FIG. 27E, the acquisition system 50 is shaped to
surround part of, but not cover, the cavity 215.
[0124] The upper and lower acquisition layers 52 and 54 may, but
need not, cover identical areas of the absorbent core 214. In
various embodiments, the upper and lower acquisition layers 52 and
54 may have different sizes and/or positions relative to the
absorbent core. In FIG. 27F, the upper acquisition layer 52 covers
part of the cavity 215, and the lower acquisition layer 54 covers
none of the cavity. In FIG. 27G, the upper acquisition layer 52
covers part of the cavity 215, and the lower acquisition layer 54
is shaped to surround part of but not cover the cavity 215. In FIG.
27H, the upper acquisition layer 52 covers all of the cavity 215,
and the lower acquisition layer 54 is shaped to surround part of
but not cover the cavity 215. In FIG. 27I, the upper and lower
acquisition layers 52 and 54 are approximately coextensive and
include an aperture surrounding all of the cavity 215 in the
absorbent core 214. In FIG. 27J, the upper acquisition layer 52
covers all of the cavity 215, and the lower acquisition layer 54,
which is smaller than the upper acquisition layer 52 and does not
cover the cavity 215. In FIG. 27K, the cavity 215 is covered by a
single (upper) acquisition layer 52.
[0125] In another alternative embodiment, an absorbent core is
provided with a cavity that is a through hole extending all the way
through the core cover, absorbent particulate polymer materials,
and dusting layer. For instance the cavity may be formed by a
stamping process, and then the borders/edges of the cavity may be
sealed, for example, by use of an adhesive and/or a heating or
pressure process. In such an embodiment, the back sheet, and/or
another layer, of the absorbent article may serve as the
back/bottom of the cavity to contain the bowel movement.
[0126] The acquisition system may augment the caliper of the cavity
of the absorbent article. In one embodiment, shown in FIGS. 28A-B,
the absorbent core 214 includes a cavity 215, which is partially
covered by an acquisition layer 52. The basis weight (and
thickness) of the absorbent particulate polymer material in the
absorbent core 214 varies in the regions about the cavity 215. The
basis weight in region 232 is higher than the basis weight in
region 234. Region 233 may provide a smooth gradient of basis
weight between regions 232 and 234. The acquisition layer 52 may
supplement the caliper of region 234 to approach, meet, or exceed
the caliper of region 232.
[0127] In another embodiment, which is illustrated in FIGS. 13 and
14, an absorbent core 214 is part of a disposable absorbent article
302 that comprises an elasticized top sheet 311, which includes an
opening 314 and that in use forms a void 355 for fecal matter
encapsulation. This opening 314 is an area completely circumscribed
by the top sheet 311, but where the top sheet material is not
present, and which is large enough to receive fecal material, for
example, being at least 2 cm long or wide, or having a surface area
of at least 2 cm.sup.2. In a certain embodiment, the elasticized
top sheet 314 generally is located adjacent the cavity 215, such
that at least a portion of the opening 314 may be substantially
aligned with the first channel 219 of the cavity 215 in the
absorbent core 214.
[0128] The top sheet 311 and the opening 314 each have a front
region 321 and a back region 322. The diaper 302, illustrated in
FIGS. 13-14, includes a back waist band with ears with fasteners
318 and a front waist band 359 with receiving areas for the
fasteners. In some configurations, the fasteners comprise hooks
and/or adhesive and the receiving areas may be formed from
loop-containing material. The diaper 302 further may include
elasticated bands along the longitudinal side edges of the diaper
302, so called leg cuffs 320. Leg cuffs may also be referred to as
leg bands, side flaps, barrier cuffs, or elastic cuffs, as
described in; U.S. Pat. No. 3,860,003; U.S. Pat. No. 4,808,178 and
U.S. Pat. No. 4,909,803; U.S. Pat. No. 4,695,278 and U.S. Pat. No.
4,795,454.
[0129] The disposable absorbent article 302 may also include a
sub-layer (which may be part of the absorbent core) disposed
between the top sheet 311 and the absorbent core 214, capable of
accepting, and/or immobilizing bodily exudates, typically fecal
material. For example as shown in FIG. 14, the absorbent core 214
may comprise a specific sub-layer 324, which comprises means to
immobilize fecal material, for example, a layer with vertically
extending (z-direction) fibers, or an apertured web or film, as
described herein. Suitable materials for use as the sub-layer may
include large cell open foams, macro-porous compression resistant
non woven highlofts, large size particulate forms of open and
closed cell foams (macro and/or microporous), highloft non-wovens,
polyolefin, polystyrene, polyurethane foams or particles,
structures comprising a multiplicity of vertically oriented, which
may be looped, strands of fibers, and/or apertured formed films.
(As used herein, the term "microporous" refers to materials that
are capable of transporting fluids by capillary action, but having
a mean pore size of more than 50 microns. The term "macroporous"
refers to materials having pores too large to effect capillary
transport of fluid, generally having pores greater than about 0.5
mm (mean) in diameter and more specifically, having pores greater
than about 1.0 mm (mean) in diameter, but typically less than 10 mm
or even less than 6 mm (mean).
[0130] The top sheet 311 with at least one opening 314 may be made
as described in U.S. Patent Application Publication No.
2007/0197992 A1 to Martynus et al., which is incorporated herein by
reference. The top sheet may further comprise, in one embodiment, a
genital coversheet as described in the same published
application.
[0131] The exact shape of the opening 314 may vary, depending on
the size of the top sheet 311 and/or the absorbent article 302. For
example, in one embodiment the opening is in the form of a slit
opening with substantially parallel longitudinal side edges, which
are connected in the front and back by V-shaped or rounded
V-shaped, as shown in FIG. 13, front and back edges, wherein both
the front and back V-shaped edges comprise two angled edges. In
some embodiments, the back V-shaped edges may have a larger angle
than the front V-shaped edges. The front V-shaped edges may have an
angle of 20.degree. to 100.degree. or, alternately, from 45.degree.
to 65.degree., as shown in FIG. 14. The slit opening may optionally
extend into an additional cut-out area which is, for example,
diamond shaped. In an embodiment, best illustrated in FIG. 14, the
opening 314 comprises a front end portion 336, which is curved,
disposed between longitudinal side edges 316 of the opening.
[0132] The dimensions the opening 314 may also vary, depending on
the size of the top sheet 311 and/or the absorbent article 302. In
some embodiments, the top sheet 311 may have a slit opening having
a longitudinal dimension (length) substantially parallel to the
longitudinal axis of the top sheet 311 and of the diaper 302. In a
stretched state, the opening 314 (or openings) of the top sheet may
be configured such that from 20% to 40% or from 20% to 30% of the
length of the opening (or total length of the openings) extends
from the transverse axis of the top sheet toward the front edge of
the top sheet, and the remaining percentage extends towards the
back edge of the top sheet. In some embodiments, the maximum length
of the slit opening may be about 40% to 90%, about 50% to 80%, or
about 60% to 70% of the total length L of the absorbent article. In
one example, a size 4 diaper may have a maximum top sheet length of
between 45 cm and 55 cm or between 48 cm and 52 cm. In some
embodiments, the length of the single slit opening, when the diaper
is in stretched state, may be from 20 cm to 40 cm; from 25 cm to 35
cm; or from 28 cm to 32 cm. In some embodiments, the average width
of the opening, in stretched state, may be from 5% to 30% or 10% to
25% of the average width of the top sheet (including opening
width). In one example, a size 4 diaper may have an average width
of the opening of from 15 mm to 60 mm or from 20 mm to 40 mm.
[0133] As shown in FIG. 13, the top sheet 311 may include a primary
elasticated area 331 adjacent to or in close proximity with each
longitudinal side edge 316 of the opening 314 to form a pair of
opposing, elasticated areas. In some embodiments, the primary
elasticated areas may extend from the side edges 316 of the opening
314 towards or completely to the front and back edge of the top
sheet 311. Thus, the primary elasticated areas may be longer than
the opening 314. The elasticated area may be positioned over the
full length of the top sheet, or at least the part of the top sheet
which in use is intended to receive body exudates (e.g., the top
sheet minus the parts thereof which form (part of) the waist
bands). An elasticated area in the top sheet may be formed from a
multitude of thin strands of elastic material or, for example, from
a single band of elastic material. The absorbent article may also
include secondary elasticated areas in each crotch side portion
(i.e., the portion of the top sheet between the longitudinal side
edge of the top sheet 311 and the longitudinal side edge of the
opening 314). Each secondary elasticized area may have an overall
curvature, curving away from the primary elasticated area of the
same crotch side portion.
[0134] As shown in FIG. 13, the primary elasticated areas 331 may
be positioned along the longitudinal side edges 316 of the opening
314. The top sheet 311 may also have secondary elasticated areas
332, or even tertiary elasticated areas (not shown). The primary
elasticated areas 331 have each a central region with a length
L.sub.2, the central regions being substantially parallel to one
another, whereby L.sub.2 may be about 30% to 70% of the total
length L.sub.1 of the primary elasticated areas 331. In an
embodiment, L.sub.2 is about 40% to 80% of the maximum length of
the opening 314. The primary elasticated areas 331 may have an
X-shape, whereby the front end portions 336 bend away from one
another and the back end portions 338 bend away from one another.
The primary elasticated areas may also be parallel, such as
described in EP Application Publication EP-A-1201212.
[0135] The primary elasticated area may be shaped such that it has
a central portion that is substantially parallel to the central
portion of the opposing primary elasticated area. In an embodiment,
the central portion has a length L.sub.2 which may be 30% to 70% of
the total length L.sub.1 of a corresponding elasticated area, and
may be about 40% to 80% of the maximum length of the opening. In
some embodiments, the total length of the elasticated area may be
about 70% to 90%, about 80% to 90%, or about 85% of maximum length
of the top sheet 311. The length of the primary elasticated area
may also depend on the size of the top sheet 311 and/or the article
302. For example, for a size 4 diaper as described above the
average length of the elasticated area in stretched state, may be
at least 35 cm, or from 35 cm to 45 cm. The width of the
elasticated areas on the top sheet may also vary, depending on the
exact dimensions of the top sheet 311 and/or the article 302. For
example, for size 4 diapers as described above, a primary
elasticated area, in stretched state, may be an elastic band, or a
multitude of elastic strands, that has an average width of about 3
mm to 50 mm, about 3 mm to 40 mm, about 3 mm to 20 mm, or about 5
mm to 20 mm.
[0136] The front end portions of two opposing primary elasticated
areas may bend away from one another (in the plane of the top
sheet), so that the distance between the end edges of the opposing
front end portions of two opposing elastic areas is larger than the
distance between the central portions of two opposing elastic
areas, and equally, the distance between the end edges of the
opposing back end portions of two opposing elastic areas is larger
that the distance between the central portions of two opposing
elastic areas. For example, as shown in FIG. 14, the primary
elasticated areas 331 may be in the shape of an X, whereby each
front end portion 336 of the elasticated area has an angle .alpha.
with the longitudinal line 335 parallel to the longitudinal axis of
the top sheet 311 and through that part of the elasticated area
that is (directly) adjacent a longitudinal side edge 316 of the
opening. In one embodiment, this angle .alpha. may be about
17.degree. to 30.degree. in stretched state. In one embodiment,
each back end portion 338 of the elasticated area also may have an
angle which may be about 17.degree. to 30.degree. in stretched
state.
[0137] In some embodiments, the front end portion of a primary
elasticated area may have an angle with a longitudinal line through
the central portion of the elasticated area and parallel to the
longitudinal axis of the top sheet, the angle may be between
10.degree. and 40.degree., between 17.degree. to 35.degree., or
between 20.degree. and 35.degree.. In other embodiments, the back
end portion of each of the primary elasticated areas may have an
angle with a longitudinal line through the central portion of the
elasticated area and parallel to the longitudinal axis of the top
sheet. In some embodiments, the angle may be between 10.degree. and
40.degree., between 17.degree. to 35.degree., or between 20.degree.
and 35.degree.. When both front end portions and both back end
portions have an angle as above, the primary elasticated areas
have, as is herein referred to, an X-shape, and a suitable X-shape
is exemplified in FIG. 13.
[0138] In some embodiments, the front end and/or the back end
and/or the central portion of an elasticated area may be curved
rather than straight. In such an embodiment, the angles above may
be determined by the angle of the tangent line through the center
point of the front end and/or back end, with the line parallel to
the longitudinal axis of the top sheet and tangent to the center
point of the central portion of the elasticated area.
[0139] The elasticated areas herein may be formed by attaching an
elasticated material in stretched state or in a partial stretched
state to the top sheet or to one or more carrier materials that are
then subsequently attached to the top sheet. The elastic materials
may be in the form of a multitude of strands or a single band with
an average thickness (e.g., gauge) of at least 20 microns, at least
40 microns, or at least 60 microns. In some embodiments, the
elastic material has an average thickness up to about 300 microns,
up to 200 microns, or up to 150 microns. Suitable materials may
have an average thickness of about 70 to 100 microns. Suitable
elastic materials used herein may include VFE-CD, available from
Tredegar, and L-86, L-89, or L-90, available from Fulflex
(Limerick, Ireland).
[0140] The absorbent article 302 may be sag-tolerable and may
include a top sheet 311 that is sag-tolerable. This means that the
top sheet does not sag when the back sheet and absorbent core sag
due to increased weight of the body exudates received by the
article. In addition, the top sheet keeps its z-direction alignment
with the anal region and genitals of the wearer, and may also keep
its x and y direction alignment. The absorbent article (e.g.,
diaper or training pants) may include a means to ensure that the
top sheet stays in about the same contact or close proximity with
the wearer's anal and/or genital region when the back sheet and
core sag, compared to just after application of the article to the
wearer, when the back sheet and core do not yet sag. In some
embodiments, the top sheet is sag-tolerable such that when the
geometrical center point of the back sheet is pulled down 4 cm, (i)
the top sheet does not move down more than 0.5 cm, more than 0.25
cm, or does not move down at all, and/or (ii) the longitudinal side
edges of the opening do not move in the x and y direction more than
0.5 cm, more than 0.25 cm, or do not move at all.
[0141] In some embodiments, the top sheet 311 may be sag-tolerable
and thereto non-elastically extendable and may have thereto one or
more transverse folds and/or longitudinal folds 357, as shown in
FIGS. 13-14, in a non-elasticated area 334. In some configurations,
the average width of the top sheet 311, including the width of the
opening 314, may be larger than the average distance between the
longitudinal attachment areas of the top sheet 311 to the back
sheet 312. In other configurations, the average width of the top
sheet, including the width of the opening, may be larger than the
average width of the back sheet. As such, the top sheet may, for
example, have one or more transverse and/or longitudinal folds,
which can unfold in use and allow sagging of the core and back
sheet, while the top sheet remains in place. In some embodiments,
the top sheet 311 with the longitudinal folds 357 is not attached
to the absorbent core 214, but directly to the back sheet 312 with
longitudinal attachment lines 323, to ensure that the diaper 302
and the top sheet 311 thereof are sag-tolerable.
[0142] In one embodiment, the absorbent article 10 may include one
more top sheets that facilitate passage of bowel movement through
the top sheets and into the at least one cavity 215. Examples of
such top sheets are described in U.S. Patent Application
Publication No. 2004/0092900, U.S. Pat. No. 5,342,338, European
Patent Application Publication No. 1201212. As described in U.S.
Pat. No. 5,342,338 to Roe, the absorbent article 10 may include a
first top sheet with apertures large enough for low-viscosity fecal
material to pass through it.
[0143] The amount of absorbent particulate polymer material 66 and
74 present in the absorbent core 14 (or 214) may vary, but in
certain embodiments, is present in the absorbent core in an amount
greater than about 80% by weight of the absorbent core, or greater
than about 85% by weight of the absorbent core, or greater than
about 90% by weight of the absorbent core, or greater than about
95% by weight of the core. In a particular embodiment, the
absorbent core 14 (or 214) consists essentially of the first and
second substrates 64 and 72, the absorbent particulate polymer
material 66 and 74, and the thermoplastic adhesive composition 68
and 76. In an embodiment, the absorbent core 14 (or 214) may be
substantially cellulose free.
[0144] In certain embodiments which are not substantially cellulose
free, the absorbent core 14 (or 214) can include some amount of
cellulosic fiber material, such as airfelt. A relatively low amount
of cellulosic material is used, in certain embodiments, which may
be less than about 40 weight percent, or about 20 weight percent of
cellulosic material, as compared to the weight of absorbent
core.
[0145] According to certain embodiments, the basis weight of
absorbent particulate polymer material 66 and 74 in at least one
freely selected first square measuring 1 cm.times.1 cm in a zone of
greater absorbent particulate polymer material basis weight may be
at least 10%, or 20%, or 30%, 40% or 50% higher than the basis
weight of absorbent particulate polymer material 66 and 74 in at
least one freely selected second square measuring 1 cm.times.1 cm
in a zone of lesser absorbent particulate polymer material basis
weight. In a certain embodiment, the first and the second square
are centered about the longitudinal axis.
[0146] According to an embodiment, a suitable absorbent particulate
polymer material 66 and 74, even in the swollen state, i.e., when
liquid has been absorbed, does not substantially obstruct the
liquid flow throughout the material, especially when the material
has a permeability, as expressed by the saline flow conductivity of
the absorbent polymer material, of greater than about 10, 40, 80,
100, 110, 120, 150, or 200.times.10.sup.-7 cm.sup.3sec/g and a
centrifuge retention capacity (CRC) of greater than about 20 g/g,
greater than about 25 g/g, or less than about 40 g/g, less than
about 35 g/g. Saline flow conductivity is a parameter well
recognized in the art and is to be measured in accordance with the
test disclosed in U.S. Patent Application Publication No.
2007/0219521. Centrifuge retention capacity is another parameter
well recognized in the art and is to be measured in accordance with
the test disclosed hereinbelow. According to a certain embodiment,
the absorbent polymer material has an Absorption Against Pressure
(AAP) of at least about 20 g/g, greater than about 23 g/g, or
greater than about 25 g/g as measured according to the test
described below. Absorbent polymer materials for use in certain
embodiments have a basis weight of at least about 200 g/m.sup.2, at
least about 400 g/m.sup.2, or at least about 600 g/m.sup.2. To
maintain flexibility the basis weight is desirably less than about
2000 g/m.sup.2.
[0147] In certain embodiments wherein the absorbent core 14 (or
214) is substantially cellulose free, the absorbent core 14 (or
214) has a density greater than about 0.4 g/m.sup.3, greater than
about 0.5 g/m.sup.3, or greater than about 0.6 g/m.sup.3.
[0148] According to an embodiment, the absorbent particulate
polymer material 66 and 74 may be present in the diaper 10 so as to
impart an average basis weight of more than about 50, 100, 200,
300, 400, 500, 600, 700, 800 or 900 g/m.sup.2. The diaper 10 (or
302), according to an exemplary embodiment, may have a relatively
narrow crotch width for increased wearing comfort. The diaper 10
(or 302) may have a crotch width of less than about 100 mm, 90 mm,
80 mm, 70 mm, 60 mm or even less than about 50 mm. Hence, the
absorbent core 14 (or 214), according to an embodiment, may have a
crotch width as measured along a transversal line which is
positioned at equal distance to the front edge and the rear edge of
the core which is less than about 100 mm, 90 mm, 80 mm, 70 mm, 60
mm or even less than about 50 mm, as measured along a transversal
line which is positioned at equal distance to the front edge and
the rear edge of the core. It has been found that, for most
absorbent articles such as diapers, the liquid discharge occurs
predominately in the front half of the diaper. The front half of
the absorbent core 14 may therefore comprise most of the absorbent
capacity of the core. Thus, according to certain embodiments, the
front half of said absorbent core 14 (or 214) may comprise more
than about 60% of the absorbent capacity, or more than about 65%,
70%, 75%, 80%, 85%, or 90% of the absorbent capacity.
[0149] In certain embodiments, the absorbent core 14 (or 214) may
further comprise any absorbent material that is generally
compressible, conformable, non-irritating to the wearer's skin, and
capable of absorbing and retaining liquids such as urine and other
certain body exudates. In such embodiments, the absorbent core 14
(or 214) may comprise a wide variety of liquid-absorbent materials
commonly used in disposable diapers and other absorbent articles
such as comminuted wood pulp, which is generally referred to as
airfelt, creped cellulose wadding, melt blown polymers, including
co-form, chemically stiffened, modified or cross-linked cellulosic
fibers, tissue, including tissue wraps and tissue laminates,
absorbent foams, absorbent sponges, or any other known absorbent
material or combinations of materials. The absorbent core 14 (or
214) may further comprise minor amounts (typically less than 10%)
of non-liquid absorbent materials, such as adhesives, waxes, oils
and the like.
[0150] Exemplary absorbent structures for use as the absorbent
assemblies are described in U.S. Pat. No. 4,610,678 (Weisman et
al.); U.S. Pat. No. 4,834,735 (Alemany et al.); U.S. Pat. No.
4,888,231 (Angstadt); U.S. Pat. No. 5,260,345 (DesMarais et al.);
U.S. Pat. No. 5,387,207 (Dyer et al.); U.S. Pat. No. 5,397,316
(LaVon et al.); and U.S. Pat. No. 5,625,222 (DesMarais et al.).
[0151] In a certain embodiment best illustrated in FIG. 2, the
elasticized leg cuffs 24 may comprise absorbent particulate polymer
material 66 which may be laid down directly of the elasticized legs
cuffs 24 in the same manner as the absorbent particulate polymer
material 66 is laid down on first substrate 64 (described below) or
may be formed on a separate substrate and added later.
[0152] The thermoplastic material 68 and 76 may serve to cover and
at least partially immobilize the absorbent particulate polymer
material 66 and 74. In one embodiment of the present invention, the
thermoplastic material 68 and 76 can be disposed essentially
uniformly within the absorbent particulate polymer material 66 and
74. However, in a certain embodiment, the thermoplastic material 68
and 76 may be provided as a fibrous layer which is at least
partially in contact with the absorbent particulate polymer
material 66 and 74 and partially in contact with the substrate
layers 64 and 72 of the first and second absorbent layers 60 and
62. FIGS. 3, 4, and 7 show such a structure, and in that structure,
the absorbent particulate polymer material 66 and 74 is provided as
a discontinuous layer, and a layer of fibrous thermoplastic
material 68 and 76 is laid down onto the layer of absorbent
particulate polymer material 66 and 74, such that the thermoplastic
material 68 and 76 is in direct contact with the absorbent
particulate polymer material 66 and 74, but also in direct contact
with the second surfaces 80 and 84 of the substrates 64 and 72,
where the substrates are not covered by the absorbent particulate
polymer material 66 and 74. This imparts an essentially
three-dimensional structure to the fibrous layer of thermoplastic
material 68 and 76, which in itself is essentially a
two-dimensional structure of relatively small thickness, as
compared to the extension in length and width directions. In other
words, the thermoplastic material 68 and 76 undulates between the
absorbent particulate polymer material 68 and 76 and the second
surfaces of the substrates 64 and 72.
[0153] Thereby, the thermoplastic material 68 and 76 may provide
cavities to cover the absorbent particulate polymer material 66 and
74, and thereby immobilizes this material. In a further aspect, the
thermoplastic material 68 and 76 bonds to the substrates 64 and 72
and thus affixes the absorbent particulate polymer material 66 and
74 to the substrates 64 and 72. Thus, in accordance with certain
embodiments, the thermoplastic material 68 and 76 immobilizes the
absorbent particulate polymer material 66 and 74 when wet, such
that the absorbent core 14 achieves a wet immobilization of more
than about 50%, or more than about 60%, 70%, 80% or 90% according
to the Wet Immobilization Test. The Wet Immobilization Test is
described in U.S. Patent Application Publication No. 2004/0162536,
the disclosure of which is expressly incorporated herein by
reference. Some thermoplastic materials will also penetrate into
both the absorbent particulate polymer material 66 and 74 and the
substrates 64 and 72, thus providing for further immobilization and
affixation. According to certain embodiments, the thermoplastic
material 68 and 76 may have an effective mesh size less than 300
microns.
[0154] Of course, while the thermoplastic materials disclosed
herein provide a much improved wet immobilization (i.e.,
immobilization of absorbent material when the article is wet or at
least partially loaded), these thermoplastic materials may also
provide a very good immobilization of absorbent material when the
absorbent core 14 (or 214) is dry.
[0155] According to certain embodiments, the thermoplastic material
68 and 76 can comprise any thermoplastic material, including, but
not limited to adhesive thermoplastic materials, also referred to
as hot melt adhesives. Some initially thermoplastic materials may
later lose their thermoplasticity due to a curing step, e.g.,
initiated via heat, UV radiation, electron beam exposure or
moisture or other means of curing, leading to the irreversible
formation of a crosslinked network of covalent bonds. Those
materials having lost their initial thermoplastic behavior are
herein also understood as thermoplastic materials.
[0156] Without wishing to be bound by theory, it has been found
that those thermoplastic materials which are most useful for
immobilizing the absorbent particulate polymer material 66 and 74
combine good cohesion and good adhesion behavior. Good adhesion may
promote good contact between the thermoplastic material 68 and 76
and the absorbent particulate polymer material 66 and 74 and the
substrates 64 and 72. Good cohesion reduces the likelihood that the
adhesive breaks, in particular in response to external forces, and
namely in response to strain. When the absorbent core 14 (or 214)
absorbs liquid, the absorbent particulate polymer material 66 and
74 swells and subjects the thermoplastic material 68 and 76 to
external forces. In certain embodiments, the thermoplastic material
68 and 76 may allow for such swelling, without breaking and without
imparting too many compressive forces, which would restrain the
absorbent particulate polymer material 66 and 74 from swelling.
[0157] In accordance with certain embodiments, the thermoplastic
material 68 and 76 may comprise, in its entirety, a single
thermoplastic polymer or a blend of thermoplastic polymers, having
a softening point, as determined by the ASTM Method D-36-95 "Ring
and Ball", in the range between 50.degree. C. and 300.degree. C.,
or alternatively the thermoplastic material may be a hot melt
adhesive comprising at least one thermoplastic polymer in
combination with other thermoplastic diluents such as tackifying
resins, plasticizers and additives such as antioxidants. In certain
embodiments, the thermoplastic polymer has typically a molecular
weight (Mw) of more than 10,000 and a glass transition temperature
(Tg) usually below room temperature or 0.degree.
C.<T.sub.g<20.degree. C. In certain embodiments, typical
concentrations of the polymer in a hot melt are in the range of
about 20 to about 40% by weight. In certain embodiments,
thermoplastic polymers may be water insensitive. Exemplary polymers
are (styrenic) block copolymers including A-B-A triblock
structures, A-B diblock structures and (A-B)n radial block
copolymer structures wherein the A blocks are non-elastomeric
polymer blocks, typically comprising polystyrene, and the B blocks
are unsaturated conjugated diene or (partly) hydrogenated versions
of such. The B block is typically isoprene, butadiene,
ethylene/butylene (hydrogenated butadiene), ethylene/propylene
(hydrogenated isoprene), and mixtures thereof.
[0158] Other suitable thermoplastic polymers that may be employed
are metallocene polyolefins, which are ethylene polymers prepared
using single-site or metallocene catalysts. Therein, at least one
comonomer can be polymerized with ethylene to make a copolymer,
terpolymer or higher order polymer. Also applicable are amorphous
polyolefins or amorphous polyalphaolefins (APAO) which are
homopolymers, copolymers or terpolymers of C.sub.2 to C.sub.8
alphaolefins.
[0159] In exemplary embodiments, the resin has typically a Mw below
5,000 and a Tg usually above room temperature, typical
concentrations of the resin in a hot melt are in the range of about
30 to about 60%, and the plasticizer has a low Mw of typically less
than 1,000 and a Tg below room temperature, with a typical
concentration of 0-15%.
[0160] In certain embodiments, the thermoplastic material 68 and 76
is present in the form of fibers. In some embodiments, the fibers
will have an average thickness of about 1 to about 50 micrometers
or about 1 to about 35 micrometers and an average length of about 5
mm to about 50 mm or about 5 mm to about 30 mm. To improve the
adhesion of the thermoplastic material 68 and 76 to the substrates
64 and 72 or to any other layer, in particular any other non-woven
layer, such layers may be pre-treated with an auxiliary
adhesive.
[0161] In certain embodiments, the thermoplastic material 68 and 76
will meet at least one, or several, or all of the following
parameters:
[0162] An exemplary thermoplastic material 68 and 76 may have a
storage modulus G' measured at 20.degree. C. of at least 30,000 Pa
and less than 300,000 Pa, or less than 200,000 Pa, or between
140,000 Pa and 200,000 Pa, or less than 100,000 Pa. The storage
modulus G' at 20.degree. C. may be a measure for the permanent
"tackiness" or permanent adhesion of the thermoplastic material
used. In a further aspect, the storage modulus G' measured at
35.degree. C. may be greater than 100,000 Pa. In a further aspect,
the storage modulus G' measured at 60.degree. C. may be less than
300,000 Pa and more than 18,000 Pa, or more than 24,000 Pa, or more
than 30,000 Pa, or more than 90,000 Pa. The storage modulus
measured at 60.degree. C. may be a measure for the form stability
of the thermoplastic material at elevated ambient temperatures.
This value is particularly important if the absorbent product is
used in a hot climate where the thermoplastic material would lose
its integrity if the storage modulus G' at 60.degree. C. is not
sufficiently high.
[0163] G' is typically measured using a rheometer as schematically
shown in FIG. 11 for the purpose of general illustration only. The
rheometer 127 is capable of applying a shear stress to the adhesive
and measuring the resulting strain (shear deformation) response at
constant temperature. The adhesive is placed between a
Peltier-element acting as lower, fixed plate 128 and an upper plate
129 with a radius R of e.g., 10 mm, which is connected to the drive
shaft of a motor to generate the shear stress. The gap between both
plates has a height H of e.g., 1500 micron. The Peltier-element
enables to control the temperature of the material (+0.5.degree.
C.).
[0164] In a further embodiment, the thermoplastic material 68 and
76 may have a deformation resistance strain in % between about 20
and about 90.
[0165] In a further aspect, the loss angle tan Delta of the
adhesive at 60.degree. C. may be below the value of 2, or below the
value of 1, or below the value of 0.5. The loss angle tan Delta at
60.degree. C. is correlated with the liquid character of an
adhesive at elevated ambient temperatures. The lower tan Delta, the
more an adhesive behaves like a solid rather than a liquid, i.e.,
the lower its tendency to flow or to migrate and the lower the
tendency of an adhesive superstructure as described herein to
deteriorate or even to collapse over time. This value is hence
particularly important if the absorbent article is used in a hot
climate.
[0166] In a further embodiment, the thermoplastic material 68 and
76 may have a glass transition temperature T.sub.g of less than
25.degree. C., or less than 22.degree. C., or less than 18.degree.
C., or less than 15.degree. C. A low glass transition temperature
T.sub.g is beneficial for good adhesion. In a further embodiment, a
low glass transition temperature T.sub.g ensures that the adhesive
thermoplastic material does not become too brittle.
[0167] In a further embodiment, the thermoplastic material 68 and
76 may have an elasticity factor from about 10 to about 20.
[0168] In yet a further embodiment, the thermoplastic material 68
and 76 may have a sufficiently high cross-over temperature. A
sufficiently high cross-over temperature T.sub.x has been found
beneficial for high temperature stability of the thermoplastic
layer and hence it ensures good performance of the absorbent
product and in particular good wet immobilization even under
conditions of hot climates and high temperatures. Therefore,
T.sub.x may be above 80.degree. C., or above 85.degree. C., above
90.degree. C., or above 95.degree. C.
[0169] As described hereinabove, the absorbent core 14 (or 214) may
also comprise an auxiliary adhesive layer 69. The auxiliary
adhesive may be deposited on the first and second substrates 64 and
72 of the respective first and second absorbent layers 60 and 62
before application of the absorbent particulate polymer material 66
and 74 for enhancing adhesion of the absorbent particulate polymer
materials 66 and 74 and the thermoplastic material 68 and 76 to the
respective substrates 64 and 72. The auxiliary glue 69 may also aid
in immobilizing the absorbent particulate polymer material 66 and
74 and may comprise the same thermoplastic material as described
hereinabove or may also comprise other adhesives including but not
limited to sprayable hot melt adhesives, such as H.B. Fuller Co.
(St. Paul, Minn.) Product No. HL-1620-B. The auxiliary glue may be
applied to the substrates 64 and 72 by any suitable means, but
according to certain embodiments, may be applied in about 0.5 to
about 1 mm wide slots spaced about 0.5 to about 2 mm apart.
[0170] The cover layer 70 shown in FIG. 4 may comprise the same
material as the substrates 64 and 72, or may comprise a different
material. In certain embodiments, suitable materials for the cover
layer 70 are the non-woven materials, typically the materials
described above as useful for the substrates 64 and 72.
[0171] In a certain embodiment not illustrated, the absorbent core
14 (or 214) may be wrapped by a core wrap material. In one
embodiment, the core wrap material comprises a top layer and a
bottom layer. The core wrap material, the top layer or the bottom
layer may be provided from a non-woven material. Such a core wrap
may be provided from two or more separate sheets of materials or
they may be alternatively provided from a unitary sheet of
material. A unitary sheet of material may be wrapped around the
storage layer 60, e.g., in a C-fold.
[0172] In a certain embodiment, the absorbent core 214 is
substantially cellulose free. In this embodiment, the cavity 215
advantageously provides a void volume for the fecal matter even
when the absorbent core is already liquid, e.g., urine) loaded.
Moreover, it provides bowel movement distribution toward the back
of the diaper, away from the wearer's genitals, providing easier
clean up. In an embodiment with an elasticized top sheet 311, the
cavity 215 advantageously works as a space between the absorbent
core 214 and the elasticized top sheet 311, so that the bowel
movement is directed underneath the top sheet. In addition, in an
embodiment where there is little or no absorbent particulate
polymer material at the bottom of the cavity, when a bowel movement
gets into the cavity, it becomes visible from the outside through
the back sheet. This advantageously may serve as a positive
signaling function for the caretaker of the wearer to check/change
the diaper or training pant.
[0173] In one embodiment, the visibility of the at least one cavity
215 is enhanced by the inclusion of a color, print, pattern, or a
combination thereof, in one or more layers of the absorbent
article. For example, in one case, the cavity may be made more
visible by including a colored (i.e., non-white) layer below the
cavity, such that the color can be seen in the cavity due to the
lower (or zero) basis weight in that region of the absorbent core.
In another embodiment, a colored layer may be added over top of the
cavity, e.g., the core cover, top sheet, or as a new, additional
layer.
[0174] Method and Apparatus for Making Absorbent Articles A
printing system 130 for making an absorbent core 14 in accordance
with an embodiment of this invention is illustrated in FIG. 16 and
may generally comprise a first printing unit 132 for forming the
first absorbent layer 60 of the absorbent core 14 and a second
printing unit 134 for forming the second absorbent layer 62 of the
absorbent core 14. It is understood throughout the following
description that this system would be equally applicable to the
making of absorbent core 214.
[0175] The first printing unit 132 may comprise a first auxiliary
adhesive applicator 136 for applying an auxiliary adhesive 69 to
the substrate 64, which may be a nonwoven web, a first rotatable
support roll 140 for receiving the substrate 64, a hopper 142 for
holding absorbent particulate polymer material 66, a printing roll
144 for transferring the absorbent particulate polymer material 66
to the substrate 64, and a thermoplastic material applicator 146
for applying the thermoplastic material 68 to the substrate 64 and
the absorbent particulate polymer 66 material thereon.
[0176] The second printing unit 134 may comprise a second auxiliary
adhesive applicator 148 for applying an auxiliary adhesive 73 to
the second substrate 72, a second rotatable support roll 152 for
receiving the second substrate 72, a second hopper 154 for holding
the absorbent particulate polymer material 74, a second printing
roll 156 for transferring the absorbent particulate polymer
material 74 from the hopper 154 to the second substrate 72, and a
second thermoplastic material applicator 158 for applying the
thermoplastic material 76 to the second substrate 72 and the
absorbent particulate polymer material 74 thereon.
[0177] The printing system 130 also includes a guide roller 160 for
guiding the formed absorbent core from a nip 162 between the first
and second rotatable support rolls 140 and 152.
[0178] The first and second auxiliary applicators 136 and 148 and
the first and second thermoplastic material applicators 146 and 158
may be a nozzle system which can provide a relatively thin but wide
curtain of thermoplastic material.
[0179] Turning to FIG. 17, portions of the first hopper 142, first
support roll 140, and first printing roll 144 are illustrated. As
also shown in FIG. 20, the first rotatable support roll 140, which
has the same structure as the second rotatable support roll 152,
comprises a rotatable drum 164 and a peripheral vented support grid
166 for receiving the first substrate 64.
[0180] As also illustrated in FIG. 18, the first printing roll 144,
which has the same structure as the second printing roll 156,
comprises a rotatable drum 168 and a plurality of absorbent
particulate polymer material reservoirs 170 and 171 in a peripheral
surface 172 of the drum 168. The reservoirs 170 and 171, best
illustrated in FIG. 19, may have a variety of shapes, including
cylindrical, conical, or any other shape. The reservoirs 170 and
171 may lead to an air passage 174 in the drum 168 and comprise a
vented cover 176 for holding adhesive particulate polymer material
66 in the reservoir and preventing the adhesive particulate polymer
material 66 from falling or being pulled into the air passage
174.
[0181] The first printing roll 144 is designed to produce a certain
embodiment like the absorbent core 14 illustrated in FIG. 5 wherein
side absorbent zones 120 and 122 have a higher basis weight of
absorbing particulate polymer material 66 and 74 than the central
absorbent zone 121. In the embodiment illustrated in FIG. 19, this
effect may be achieved by having a corresponding set of reservoirs
170 which are relatively deep and a second set 171 of reservoirs
which are relatively shallow, such that the deeper reservoirs 170
carry more absorbent particulate polymer material and deliver more
absorbent particulate polymer material 66 to the side absorbent
zones 120 and 122 and the more shallow reservoirs 171 hold less
adhesive particulate polymer material and deliver less absorbent
particulate polymer material 66 to the central zone 121 of the
absorbent core 14. The sets of deeper and shallower reservoirs 170
and 171, of course, can be arranged in any variety of patterns to
define the cavity 215 of absorbent core 214, as well as in
configurations to create an absorbent core with any corresponding
variety of varying absorbent particulate polymer material basis
weights across the absorbent core 214. FIG. 19, in particular,
illustrates the difference in volumetric sizes of first and second
sets of reservoirs 170 and 171.
[0182] Other methods of forming the cavity and delivering a varying
profile of absorbent particulate polymer basis weights to the
absorbent core 14 or 214 include, but are not limited to, applying
a higher vacuum in sections of the first and second rotatable
support rolls 140 and 152 where more absorbent particulate polymer
material is desired or, when the absorbent particulate polymer
material is delivered to the absorbent core substrate 64
pneumatically, such as when combining cellulosic fibers with
absorbent particulate polymer material, directing the air stream
carrying the absorbent particulate polymer material and cellulosic
fibers to areas of the absorbent core substrate where a higher
basis weight of absorbent particulate polymer material is
desired.
[0183] In operation, the printing system 130 receives the first and
second substrate 64 and 72 into the first and second printing units
132 and 134, respectively, the first substrate 64 is drawn by the
rotating first support roll 140 past the first auxiliary adhesive
applicator 136 which applies the first auxiliary adhesive to the
first substrate 64 in a pattern such as described hereinabove. A
vacuum (not shown) within the first support roll 140 draws the
first substrate 64 against the vertical support grid 166 and holds
the first substrate 64 against the first support roll 140. This
presents an uneven surface on the first substrate 64. Due to
gravity, or by using the vacuum means, the substrate 64 will follow
the contours of the uneven surface and thereby the substrate 64
will assume a mountain and valley shape. The absorbent particulate
polymer material 66 may accumulate in the valleys presented by the
substrate 64. The first support roll 140 then carries the first
substrate 64 past the rotating first printing roll 144 which
transfers the absorbent particulate polymer material 66 from the
first hopper 142 to the first substrate 64 in the grid pattern 92
which is best illustrated in FIGS. 5 and 6. A vacuum (not shown) in
the first printing roll 144 may hold the absorbent particulate
polymer material 66 in the reservoirs 170 until time to deliver the
absorbent particulate polymer material 66 to the first substrate
64. The vacuum may then be released or air flow through the air
passages 174 may be reversed to eject the absorbent particulate
polymer material 66 from the reservoirs and onto the first
substrate 64. The absorbent particulate polymer material 66 may
accumulate in the valleys presented by the substrate 64. The
support roll 140 then carries the printed first substrate 64 past
the thermoplastic material applicator 136 which applies the
thermoplastic material 68 to cover the absorbent particulate
polymer material 66 on the first substrate 64.
[0184] Hence, the uneven surface of the vented support grid 166 of
the support rolls 140 and 152 determines the distribution of
absorbent particulate polymeric material 66 and 74 throughout the
absorbent core 14 and likewise determines the pattern of junction
areas 96.
[0185] Meanwhile, the second rotatable support roll draws the
second substrate 72 past the second auxiliary adhesive applicator
148 which applies an auxiliary adhesive to the second substrate 72
in a pattern such as is described hereinabove. The second rotatable
support roll 152 then carries the second substrate 72 past the
second printing roll 156 which transfers the absorbent particulate
polymer material 74 from the second hopper 154 to the second
substrate 72 and deposits the absorbent particulate polymer
material 74 in the grid pattern 92 on the second substrate 72 in
the same manner as described with regard to the first printing unit
132 above. The second thermoplastic material applicator 158 then
applies the thermoplastic material 76 to cover the absorbent
particulate polymer material 74 on the second substrate 72. The
printed first and second substrates 64 and 72 then pass through the
nip 162 between the first and second support rolls 140 and 152 for
compressing the first absorbent layer 60 and second absorbent layer
62 together to form the absorbent core 14.
[0186] In an optional further process step a cover layer 70 may be
placed upon the substrates 64 and 72, the absorbent particulate
polymer material 66 and 74, and the thermoplastic material 68 and
76. In another embodiment, the cover layer 70 and the respective
substrate 64 and 72 may be provided from a unitary sheet of
material. The placing of the cover layer 70 onto the respective
substrate 64 and 72 may then involve the folding of the unitary
piece of material.
[0187] FIGS. 21-23 illustrate certain embodiments of printing rolls
144' and 144'' for making corresponding embodiments of absorbent
cores 14' and 14'' illustrated in FIGS. 9 and 10, respectively. As
shown in FIGS. 21 and 22, the printing roll 144' for making the
absorbent core 14' illustrated in FIG. 9 comprises sets of deeper
and shallower reservoirs 170' and 171' for forming the end
absorbent zones 123 and 124, which have a higher absorbent
particulate polymer material basis weight, and the central
absorbent zone 125, which has a lower absorbent particulate polymer
material basis weight, respectively. Likewise, the printing roll
144'' has sets of deeper and shallower reservoirs 170'' and 171'',
respectively, for forming the side absorbent zones 120' and 122'
and end absorbent zones 123' and 124', having a higher basis weight
of absorbent particulate polymer material, and the central zone
121' and 125' having a lower basis weight of absorbent particulate
polymer material. This technique of profiling the absorbent
particulate polymer material in both the MD and CD may be readily
adapted to form a cavity, defined at least in part by the lower
basis weight of absorbent particulate polymer material in an
elongated central region.
[0188] Absorbent articles such as the diapers 10 made in accordance
with embodiments of this invention may be folded and packaged for
distribution and sale. Absorbent articles are typically bi-folded,
but may also be tri-folded. After folding, the folded absorbent
articles may be stacked to form a stack comprising a plurality of
absorbent articles. The stack may then be compressed and encased in
a packaging material such as a bag, a pouch, a box, or the
like.
[0189] All patents and patent applications (including any patents
which issue thereon) assigned to the Procter & Gamble Company
referred to herein are hereby incorporated by reference to the
extent that it is consistent herewith.
[0190] The dimensions and values disclosed herein are not to be
understood as being strictly limited to the exact numerical values
recited. Instead, unless otherwise specified, each such dimension
is intended to mean both the recited value and a functionally
equivalent range surrounding that value.
[0191] For example, a dimension disclosed as "40 mm" is intended to
mean "about 40 mm." Every document cited herein, including any
cross referenced or related patent or application, is hereby
incorporated herein by reference in its entirety unless expressly
excluded or otherwise limited. The citation of any document is not
an admission that it is prior art with respect to any invention
disclosed or claimed herein or that it alone, or in any combination
with any other reference or references, teaches, suggests or
discloses any such invention. Further, to the extent that any
meaning or definition of a term in this document conflicts with any
meaning or definition of the same term in a document incorporated
by reference, the meaning or definition assigned to that term in
this document shall govern.
[0192] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *