U.S. patent application number 17/087853 was filed with the patent office on 2021-03-11 for absorbent pant with advantageously channeled absorbent core structure and bulge-reducing features.
The applicant listed for this patent is The Procter & Gamble Company. Invention is credited to Gary Dean LaVON, Masaharu NISHIKAWA.
Application Number | 20210069030 17/087853 |
Document ID | / |
Family ID | 1000005226208 |
Filed Date | 2021-03-11 |
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United States Patent
Application |
20210069030 |
Kind Code |
A1 |
NISHIKAWA; Masaharu ; et
al. |
March 11, 2021 |
Absorbent Pant With Advantageously Channeled Absorbent Core
Structure And Bulge-Reducing Features
Abstract
A disposable absorbent pant having a belt structure that
encircles the wearer's waist, with front and rear belt portions,
and a longitudinally channeled absorbent core structure, is
disclosed. The channels are extended so as to underlie at least one
of the front and rear belt portions, thereby providing added
structural support to restrain the absorbent core and reduce the
likelihood of undesirable bulging in the front and/or rear of the
pant while it is worn, after the core has absorbed liquid and
stiffened longitudinally as a result of the channeled
structure.
Inventors: |
NISHIKAWA; Masaharu;
(Cincinnati, OH) ; LaVON; Gary Dean; (Liberty
Township, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Procter & Gamble Company |
Cincinnati |
OH |
US |
|
|
Family ID: |
1000005226208 |
Appl. No.: |
17/087853 |
Filed: |
November 3, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15722012 |
Oct 2, 2017 |
10849799 |
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17087853 |
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14598783 |
Jan 16, 2015 |
10376428 |
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15722012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 13/49011 20130101;
A61F 13/51108 20130101; A61F 13/49017 20130101; A61F 2013/530868
20130101; A61F 13/532 20130101; A61F 13/496 20130101; A61F 13/49001
20130101; A61F 13/533 20130101 |
International
Class: |
A61F 13/511 20060101
A61F013/511; A61F 13/49 20060101 A61F013/49; A61F 13/496 20060101
A61F013/496; A61F 13/532 20060101 A61F013/532; A61F 13/533 20060101
A61F013/533 |
Claims
1. An absorbent article comprising: a central lateral axis, a
central longitudinal axis extending in a direction perpendicular to
the central lateral axis; a front region, rear region and crotch
region between the front and rear regions; a topsheet, a backsheet
and an absorbent structure positioned at least partially between
the topsheet and backsheet; the absorbent structure having an
absorbent layer comprising a length M, a width N, and opposing
transverse edges and longitudinal edges; wherein the absorbent
layer comprises an absorbent material; and wherein the absorbent
material defines: at least two longitudinal main channels each
extending over a distance L that is at least 15% of the length of
the absorbent layer M, and a transverse channel, wherein the
transverse channel connects two of the at least two longitudinal
main channels, wherein the transverse channel and/or at least one
of the longitudinal main channels comprises a temporary
portion.
2. The absorbent article of claim 1 wherein the longitudinal main
channels each comprise one or more permanent portions.
3. The absorbent article of claim 2 wherein at least one
longitudinal main channel comprises a permanent portion that
overlaps the central lateral axis.
4. The absorbent article of claim 1 wherein one of the at least two
longitudinal main channels is disposed a first side of the central
longitudinal axis and another of the at least two longitudinal main
channels is disposed on a second side of the central longitudinal
axis.
5. The absorbent article of claim 1 wherein at least two
longitudinal main channels do not extend to the longitudinal edges
or transverse edges of the absorbent layer.
6. The absorbent article of claim 1 wherein the transverse channel
does not extend to the longitudinal edges or transverse edges of
the absorbent layer.
7. The absorbent article of claim 1 wherein the at least two
longitudinal main channels are curved.
8. The absorbent article of claim 1 wherein the transverse channel
is curved.
9. The absorbent article of claim 1 wherein the transverse channel
is present in the rear region.
10. The absorbent article of claim 1 wherein two of the at least
two longitudinal main channels are separated in the crotch region
by a distance D that is at 10% of the width of the absorbent layer
N.
11. The absorbent article of claim 1 wherein two of the at least
two longitudinal main channels are separated in the crotch region
by a distance D of at least 15 mm.
12. The absorbent article of claim 1 wherein the transverse channel
extends a transverse distance of at least 15% or the width of the
absorbent layer N.
13. The absorbent article of claim 1 wherein the absorbent material
comprises absorbent polymer particles and cellulose fibers.
14. The absorbent article of claim 1 wherein the temporary portion
reduces in size upon wetting.
15. The absorbent article of claim 1 wherein the absorbent material
layer is disposed between a first substrate and a second substrate
and wherein in the temporary portion, the first and second
substrates are bonded together in an article dry state and wherein
the first substrate releases from the second substrate in an
article wet state.
16. The absorbent article of claim 1 further comprising an
acquisition/distribution layer and wherein at least one of the
topsheet and the acquisition/distribution layer is generally planar
in nature such that the topsheet and the acquisition/distribution
layer bridges over the channels.
17. An absorbent article comprising: a) a top sheet; b) a
backsheet; c) an absorbent structure disposed between the topsheet
and the backsheet, the absorbent structure comprising a first
substrate, a second substrate, and an absorbent material layer
disposed between the first substrate and the second substrate and
comprising a combination of absorbent polymer particles and wood
pulp fibers; d) a channel defined in the absorbent material layer
that is substantially free of the combination of absorbent polymer
particles and wood pulp fibers; e) wherein the channel comprises at
least two permanent portions; f) wherein the channel comprises a
temporary portion; and g) wherein the temporary portion resides
between two of the at least two permanent portions.
18. The absorbent article of claim 17 wherein the channel is
curved.
19. The absorbent article of claim 17 further comprising an
acquisition/distribution layer between the topsheet and the
absorbent structure.
20. The absorbent article of claim 19 wherein at least one of the
topsheet and the acquisition/distribution layer is generally planar
in nature such that the topsheet and the acquisition/distribution
layer bridges over the channel.
21. The absorbent article of claim 17 wherein the at least two
permanent portions overlap the central lateral axis.
22. The absorbent article of claim 17 wherein the temporary portion
reduces in size upon wetting.
23. The absorbent article of claim 1 wherein in the permanent
portion, the first substrate is bonded to the second substrate in
both an article dry state and wet state, and in the temporary
portion, the first and second substrates are bonded together in the
article dry state but the first substrate releases from the second
substrate in the article wet state.
Description
BACKGROUND OF THE INVENTION
[0001] In order to maintain or grow their market share,
manufacturers of disposable absorbent articles such as disposable
diapers and absorbent pants must continue to discover and develop
improvements to materials, components and features that affect
aspects such as containment, absorbency, comfort, fit and
appearance. Absorbent pants are manufactured in smaller sizes to be
used as, e.g., pull-on diapers and toilet training pants for young
children, and in larger sizes to be used as, e.g., undergarments
for persons such as adults or older children suffering from
incontinence. In some applications the consumer and/or wearer may
prefer that the article have an appearance and feel resembling
ordinary underwear when worn.
[0002] A particular type of absorbent pant design currently
marketed is sometimes called the "balloon" pant. The balloon pant
design usually includes a central absorbent chassis including the
absorbent core and an elastic belt. The elastic belt is usually
relatively wide (in the longitudinal direction) and elastically
stretchable in the lateral direction. It entirely encircles the
wearer's waist, and thereby covers a relatively large amount of the
wearer's skin, and also makes up a relatively large portion of the
visible outside surfaces of the pant. The belt is often formed of
two layers of nonwoven web sandwiching one or more elastic members
such as a plurality of laterally-oriented strands or strips of
elastomeric material, or a section of elastomeric film, elastomeric
scrim or elastomeric nonwoven. It is common among such designs
that, in manufacture, the elastic member(s) are sandwiched between
the nonwoven web layers while in a strained condition.
[0003] The absorbent core structure that is part of the central
chassis portion plays an important role in containment and
absorbency of exudates, as well as in comfort, fit and appearance
of the article when worn. In recent years, absorbent core designs
have progressed toward structures with relatively higher
proportions by weight of absorbent polymer particles and lower
proportions of absorbent fiber (e.g., cellulose fiber), resulting
in structures that are thinner than absorbent core designs of
earlier years and enabling manufacture of products that are less
bulky and more closely-fitting (e.g., more underwear-like) when
dry. The latter structures, however, can be slower in liquid
acquisition rate, and because of their greater proportions of
absorbent polymer particles, can become saggy, bulky and gelatinous
when wetted. To address these issues, absorbent structures
including longitudinally-oriented channels have been developed.
Appropriately located and structured longitudinal channels can help
distribute liquid along deposits of absorbent polymer particles
along the length of the absorbent core, and thereby help improve
acquisition rate. They also can help reduce chances of a saggy and
bulky appearance of the article when wetted, by providing
longitudinal structural rigidity through the crotch region of the
article resulting from pressure within the wetted absorbent polymer
particle deposits between the channels.
[0004] However, it has been discovered that this structural
rigidity may have undesirable effects on appearance, fit and and/or
comfort. In particular, the longitudinal structural rigidity can
cause the front and/or rear regions of the absorbent core to tend
to bulge outwardly from the wearer's body in the front and/or rear,
resulting in bulky protrusion(s) that can create an unsightly
appearance and adversely impact comfort.
[0005] Thus, there continues to be room for improvements in
absorbent pant design that enable realization of the benefits of
various developments to date while mitigating adverse effects of
these features, both when the pant is dry, and after it is
wetted.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] In the drawings, the same features are numbered consistently
throughout the various views and depictions of examples.
[0007] FIG. 1 is a front perspective view of an example of a
balloon pant.
[0008] FIG. 2A is a schematic plan view of a balloon pant precursor
structure, prior to joining of the front and rear belt portions at
side seams, wearer-facing surfaces facing the viewer.
[0009] FIG. 2B is a schematic plan view of a balloon pant precursor
structure, prior to joining of the front and rear belt portions at
side seams, wearer-facing surfaces facing the viewer.
[0010] FIG. 2C is a schematic plan view of a balloon pant precursor
structure, prior to joining of the front and rear belt portions at
side seams, wearer-facing surfaces facing the viewer.
[0011] FIG. 3 is a schematic, exploded perspective view of
components of a belt portion.
[0012] FIG. 4 is a schematic, close-up plan view of an area of a
belt portion.
[0013] FIG. 5 is a schematic cross section of the area of the belt
portion shown in FIG. 4.
[0014] FIG. 6A is a schematic side view of a pant.
[0015] FIG. 6B is a schematic side view of a pant.
[0016] FIG. 7 is a schematic side view of a pant, shown in one
configuration as loaded with absorbed liquid.
[0017] FIG. 8 is a schematic perspective view of an absorbent
structure including an absorbent layer with two longitudinal main
channels in accordance with one non-limiting example.
[0018] FIG. 9 is a schematic perspective view of an absorbent layer
with four longitudinal main channels in accordance with one
non-limiting example.
[0019] FIG. 10A is a schematic top/plan view of an absorbent
structure including an absorbent layer with four longitudinal main
channels in accordance with one non-limiting example.
[0020] FIG. 10B is a schematic perspective view of the absorbent
structure of FIG. 10A, shown in a flexed position.
[0021] FIGS. 11A to 11E are schematic plan view representations of
channel configurations in accordance with various non-limiting
examples.
[0022] FIG. 12 is a schematic perspective view of an absorbent
layer including two longitudinal main channels in the crotch region
and two secondary channels in the front region in accordance with
one non-limiting example.
[0023] FIG. 13 is a schematic perspective view of an absorbent
layer including two longitudinal main channels in the crotch
region, two secondary channels in the front region and two
secondary channels in the back region in accordance with one
non-limiting example.
[0024] FIG. 14 is a schematic top/plan view of an absorbent
structure with absorbent layer including two longitudinal main
channels in the crotch region, and two secondary channels at front
and rear, in accordance with one non-limiting example.
[0025] FIG. 15A is a schematic lateral cross-section view of an
absorbent structure with longitudinal channels in accordance with
one non-limiting example.
[0026] FIG. 15B is a schematic lateral cross-section view of an
absorbent structure in accordance with one non-limiting
example.
[0027] FIG. 16A is a schematic plan view of a non-limiting example
of a balloon pant precursor structure, prior to joining of the
front and rear belt portions at side seams, wearer-facing surfaces
facing the viewer, shown with a configuration of longitudinal main
channels.
[0028] FIG. 16B is a schematic plan view of an alternate balloon
pant precursor structure, prior to joining of the front and rear
belt portions at side seams, wearer-facing surfaces facing the
viewer, shown with a configuration of longitudinal main
channels.
[0029] FIG. 16C is a schematic plan view of an alternate balloon
pant precursor structure, prior to joining of the front and rear
belt portions at side seams, wearer-facing surfaces facing the
viewer, shown with another configuration of longitudinal main
channels.
[0030] FIG. 16D is a schematic, exploded longitudinal cross section
view of a portion of the structure depicted in FIG. 16A.
[0031] FIG. 17 is a schematic plan view of an alternate balloon
pant precursor structure, prior to joining of the front and rear
belt portions at side seams, wearer-facing surfaces facing the
viewer, shown with another configuration of longitudinal main
channels and secondary channels.
[0032] FIG. 18 is a schematic plan view of an alternate balloon
pant precursor structure, prior to joining of the front and rear
belt portions at side seams, wearer-facing surfaces facing the
viewer, shown with another configuration of longitudinal main
channels and secondary channels.
[0033] FIG. 19 is a schematic plan view of an alternate balloon
pant precursor structure, prior to joining of the front and rear
belt portions at side seams, wearer-facing surfaces facing the
viewer, shown with another configuration of longitudinal main
channels and secondary channels.
[0034] FIG. 20 is a schematic plan view of a balloon pant precursor
structure, prior to joining of the front and rear belt portions at
side seams, garment-facing surfaces facing the viewer, shown with a
configuration of longitudinal main channels and non-elasticized
zones in front and rear belt portions.
DETAILED DESCRIPTION OF THE INVENTION
[0035] As used herein "absorbent core" refers to a component of an
absorbent article disposed between a topsheet and backsheet of an
absorbent article. The absorbent core of an absorbent article may
include one or more absorbent structures and optionally further
layers, such as, for example, a cover layer.
[0036] "Absorbent polymer particles" as used herein refers to
substantially water-insoluble polymer particles that can absorb at
least 10 times their weight of a 0.9% saline solution in
de-mineralized water as measured using the Centrifuge Retention
Capacity test (EDANA 441.2-01).
[0037] As used herein "absorbent structure" refers to a three
dimensional structure useful to absorb and contain liquids, such as
urine. The absorbent structure may be the absorbent core of an
absorbent article or may be part of the absorbent core of an
absorbent article, i.e. an absorbent component of the absorbent
core, as will be further described herein.
[0038] The term "basis weight" as used herein refers to the mass of
a material per unit surface area it occupies when laid out on a
flat surface, e.g. the mass of absorbent polymer particles
deposited per unit surface area of a supporting substrate,
expressed in, e.g., grams per square meter (gsm).
[0039] Referring to FIGS. 2A-2C, the "crotch region" of a pant is
the portion through which the lateral axis (herein, axis x) passes,
and which extends longitudinally one-sixth of the overall length of
the pant frontward and rearward of the lateral axis. Accordingly,
the front region includes the front one-third of the overall length
of the pant; the crotch region includes the middle one-third of the
length of the pant; and the rear region includes the rear one-third
of the overall length of the pant.
[0040] As used herein "diapers" refers to devices which are
intended to be placed against the skin of a wearer to absorb and
contain the various exudates discharged from the body. Diapers are
generally worn by infants and incontinent persons about the lower
torso so as to encircle the waist and legs of the wearer. Examples
of diapers include infant or adult diapers and disposable absorbent
pants such as training pants and adult-incontinence pants.
[0041] "Disposable" is used herein to describe articles that are
generally not adapted to be laundered or otherwise cleaned,
restored or reused (i.e., they are only adapted to be durable
enough to be used once, and then discarded, and may be recycled,
composted or otherwise disposed of).
[0042] Throughout the present description, a material or composite
of materials is considered to be "elastic" or "elastomeric" if,
when a biasing force is applied to the material, the material or
composite may be extended to an elongated length of at least 150%
of its original relaxed length (i.e. can extend at least 50%),
without rupture or breakage which substantially damages the
material or composite, and when the force is removed from the
material or composite, the material or composite recovers at least
40% of such elongation. In various examples, when the force is
removed from an elastically extensible material, the material or
composite may recover at least 60% or even at least 80% of its
elongation.
[0043] "Elongation," used herein to quantify and express an amount
of strain imparted to an elastic strand in the direction of its
longitudinal axis, means: [(strained length of the strand-length of
the strand before straining)/(length of the strand before
straining)], x 100%. Where the term "pre-strain" is used to refer
to elongation imparted to an elastic strand during manufacture of a
belt structure or pant, it refers to elongation, expressed in the
same manner.
[0044] "Film" means a macroscopically continuous skin-like or
membrane-like layer of material formed of one or more polymers.
"Film" is distinguished from "nonwoven web" or "nonwoven" in that
the latter has a form consisting of a web-like structure of
consolidated but predominately individually distinct fibers.
[0045] "Hot melt adhesive" as used herein refers to adhesives
conforming with the description given in "Adhesion and Adhesives
Technology: An Introduction" by Alphonsus V. Pocius (Hanser
publishers Munich, 1997). Therein a hot melt is defined as an
adhesive applied from the melt and gaining strength upon
solidification.
[0046] "Lateral"--with respect to a pant and its wearer, refers to
the direction generally perpendicular to the wearer's standing
height, i.e., the horizontal direction when the wearer is standing.
"Lateral" and "transverse" (and forms thereof) also refer to the
direction perpendicular to the longitudinal direction. With respect
to certain of the figures herein in which it is shown, the x-axis
lies along the lateral and/or transverse direction.
[0047] "Longitudinal"--with respect to a pant and its wearer,
refers to the direction generally parallel to the wearer's standing
height, i.e., the vertical direction when the wearer is standing.
"Longitudinal" is also the direction generally parallel to a line
extending from the midpoint of the front waist edge, between the
leg openings, to the midpoint of the rear waist edge of the pant,
when the pant structure is separated at the side/hip seams and laid
out unfolded, extended and flat. With respect to certain of the
figures herein in which it is shown, the y-axis lies along the
longitudinal direction.
[0048] Used to describe a feature, "longitudinally-oriented" means
that the largest dimension of the feature has a
longitudinal-direction vector component that is greater than its
lateral-direction vector component. Conversely,
"laterally-oriented" means that the largest dimension of the
feature has a lateral-direction vector component that is greater
than its longitudinal-direction vector component.
[0049] With respect to a pant, relative positional terms such as
"lower," "lowest", "above," "below," "bottom," etc., and forms
thereof, are expressed with respect to the vertically lowermost
extent (in the crotch region) and uppermost extent (at the waist
edges) of the pant structure along a vertical direction, when worn
by a standing wearer. With respect to a precursor structure to the
pant, the lowest portion is at the lateral axis (axis x depicted in
the figures) and the highest portions are at the waist edges.
[0050] A "nonwoven" is a manufactured sheet or web of directionally
or randomly oriented fibers which are first deposited and
accumulated onto a moving surface (such as a conveyor belt) and
then consolidated and bonded together by friction, cohesion,
adhesion or one or more patterns of bonds and bond impressions
created through localized compression and/or application of
pressure, heat, ultrasonic or heating energy, or a combination
thereof. The term does not include fabrics which are woven,
knitted, or stitch-bonded with yarns or filaments. The fibers may
be of natural and/or man-made origin and may be staple and/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). Nonwovens may be formed by many processes including but not
limited to meltblowing, spunbonding, spunmelting, solvent spinning,
electrospinning, carding, film fibrillation, melt-film
fibrillation, airlaying, dry-laying, wetlaying with staple fibers,
and combinations of these processes as known in the art. The basis
weight of a nonwoven is usually expressed in grams per square meter
(gsm).
[0051] "Pant," as used herein, refers to a disposable absorbent
garment having a waist opening, leg openings and an absorbent
structure at least in the crotch region, adapted for wear by an
infant, child or adult wearer. A pant may be placed in position on
the wearer by inserting the wearer's feet into and through the
waist opening and into the leg openings and sliding the pant up the
wearer's legs into position about the 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).
[0052] In the following description, a surface of a wearable
absorbent article, or of a component thereof, which faces the
wearer when worn, is called the "wearer-facing surface."
Conversely, the surface facing away from the wearer is called the
"garment-facing surface." Accordingly, a wearable absorbent
article, and every sheet or web component thereof has a
wearer-facing surface and a garment-facing surface.
[0053] "z-direction," with respect to a web, means generally
orthogonal or perpendicular to the plane approximated by the web
along the machine and cross direction dimensions.
[0054] Although examples of the structure of the invention are
described herein as used to form the belt of a balloon-type
absorbent pant, it will be appreciated that examples may be used to
form other components of absorbent pants, diapers and other
wearable articles (including disposable forms thereof), and other
products as well.
[0055] FIG. 1 depicts an example of balloon-type absorbent pant 10.
FIGS. 2A-2C depict examples of the precursor structures of pants in
an open configuration laid out flat and stretched out laterally
against elastic-induced contraction, wearer-facing surfaces facing
the viewer, prior to final assembly in which front belt portion 22
is joined to rear belt portion 23 at seams 24. To form pant 10, the
precursor structure may be folded at or about lateral axis x
(located at the longitudinal midpoint of the precursor structure)
with the topsheet 33 facing inward, and the longitudinal edges of
the front 22 and rear 23 belt portions may be joined at seams 24,
forming a pant structure having leg openings 15, front waist edge
34 and rear waist edge 35.
[0056] The pant structure may include a belt 20 and a central
chassis 30. Central chassis 30 may include any combination of
components found in the absorbent structures of disposable diapers
and absorbent pants, including but not limited to a liquid
impermeable backsheet 31 formed at least in part of liquid
impermeable web material, a liquid permeable topsheet 33, an
absorbent core structure (described below), and elasticized barrier
cuffs 32. Examples and descriptions of components and
configurations of a central chassis may be found in U.S. Pat. App.
Pub. No. 2013/0211355, as well as in the other references cited
herein, to the extent not inconsistent herewith, wherein the
chassis described includes components and features that may be
included in central chassis 30. In the example shown in FIG. 1, the
front portion of belt 20 stops short of the crotch region 12 of the
pant, at lower edge 21. Central chassis 30 may overlie front and
rear belt portions 22, 23 to the inside (wearer-facing side)
thereof. The outer perimeter 41 of the central chassis 30 may be
defined by the outer perimeter of the liquid impermeable web
material.
[0057] In the examples suggested in FIGS. 2A and 2B, front and rear
belt portions 22, 23 may be the outermost structures forming the
front and rear regions of the pant. In the example suggested in
FIG. 2C (also as shown in FIG. 16B), the pant may include an outer
wrap 19 wrapping the entirety of the front, crotch and rear
regions, and forming an outermost pant-shaped/profiled structure.
Additional layer(s) and elastic members to form front and rear belt
portions 22, 23 may be disposed to the inside of outer wrap 19, and
be suitably affixed thereto by adhesive lamination, bonding or any
other suitable mechanism. An outer wrap 19 may be formed of one or
more sections of nonwoven web, and as reflected in FIG. 2C, may be
cut to a profile providing suitably tailored leg opening edge
profiles as desired.
[0058] Referring to FIGS. 3-5, one or both of front and rear belt
portions 22, 23 may be formed of layers of nonwoven web 25a, 25b,
which respectively form inner and outer layers. Suitable nonwoven
web materials that may be useful in the present invention also
include, but are not limited to spunbond, spunlaid, meltblown,
spunmelt, solvent-spun, electrospun, carded, film fibrillated,
melt-film fibrillated, air-laid, dry-laid, wet-laid staple fibers,
and other nonwoven web materials formed in part or in whole of
polymer fibers, as known in the art. The nonwoven web may be formed
predominately of polymeric fibers. In some examples, suitable
non-woven fiber materials may include, but are not limited to
polymeric materials such as polyolefins, polyesters, polyamide, or
specifically, polypropylene (PP), polyethylene (PE), poly-lactic
acid (PLA), polyethylene terephthalate (PET) and/or blends thereof.
In some examples, the fibers may be formed of PP/PE blends such as
described in U.S. Pat. No. 5,266,392. Nonwoven fibers may be formed
of, or may include as additives or modifiers, components such as
aliphatic polyesters, thermoplastic polysaccharides, or other
biopolymers. Further useful nonwovens, fiber compositions,
formations of fibers and nonwovens and related methods are
described in U.S. Pat. Nos. 6,645,569; 6,863,933; and 7,112,621;
and in U.S. patent application Ser. Nos. 10/338,603; 10/338,610;
and Ser. No. 13/005,237.
[0059] The individual fibers of which nonwoven layers 25a and 25b
are formed may be monocomponent or multicomponent (including
bicomponent). The multicomponent fibers may be bicomponent, with
differing polymeric components in, e.g., a core-and-sheath or
side-by-side arrangement. The individual components may include
polyolefins such as polypropylene or polyethylene, or their
copolymers, or polyesters, thermoplastic polysaccharides or other
biopolymers.
[0060] According to one example, the nonwoven may include a
material that provides good recovery when external pressure is
applied and removed. Further, according to one example, the
nonwoven may include a blend of different fibers selected, for
example from the types of polymeric fibers described above. In some
examples, at least a portion of the fibers may exhibit a spiral
curl which has a helical shape. According to one example, the
fibers may include bicomponent fibers, which are individual fibers
each including 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 curl to
the fibers. Examples of potentially suitable curled or "crimped"
bicomponent fibers and nonwovens formed from them are described in
U.S. Pat. Nos. 5,382,400; 5,418,045; 5,707,468; 6,454,989;
6,632,386; 5,622,772 and 7,291,239. For purposes herein, use of a
nonwoven formed of crimped bicomponent or multicomponent fibers
such as, for example, described in the patents and/or patent
applications cited immediately above, may be desired as one both
layers 25a, 25b used to form the belt portions, because they can
feel particularly soft to the touch (for wearer comfort on the
inside and aesthetically pleasing feel on the outside) and are
generally quite pliable, making them easily drawn laterally at the
lower rear leg edges as will be described below.
[0061] Referring to FIGS. 3-5, layers of nonwoven web 25a, 25b may
sandwich one or more elastic members such as a plurality of elastic
strands 26. Elastic strands may be formed of an elastomeric
material, such as an elastane (for example, LYCRA HYFIT fiber, a
product of Invista, Wichita, Kans.). Layers of nonwoven web 25a,
25b may be joined together about elastic strands 26 by adhesive
deposited between the layers, by thermal bonds, by compression
bonds, or by a combination thereof. In other examples, the one or
more elastic members may be strips or a section of film formed of
elastomeric material. Where the elastic member is elongate, it may
be desirable that the longer dimension be laterally oriented, or
even substantially aligned with the lateral direction, as strands
26 are depicted in the figures.
[0062] The elastic members can also be formed from various other
materials, such as but not limited to, rubbers, styrene
ethylbutylene styrene, styrene ethylene propylene styrene, styrene
ethylene ethylene propylene styrene, styrene butadiene styrene,
styrene isoprene styrene, polyolefin elastomers, elastomeric
polyurethanes, and other elastomeric materials known in the art,
and combinations thereof. In some examples, the elastic members may
be extruded strand elastics with any number of strands (or
filaments). The elastic members can have a decitex ranging from 50
to 2000, or any integer value for any decitex value in this range,
or any range formed by any of these integer values. The elastic
members may be in a form of film. Examples of films have been
described in prior patent applications (see, for example, U.S. Pat.
App. Pub. No. 2010/0040826). The film may be created with a variety
of resins combined in at least one of several sublayers, the latter
providing different benefits to the film.
[0063] Still referring to FIGS. 3-5, during manufacture of the belt
structure, the elastic members such as elastic strands 26 may be
pre-strained lengthwise by a desired amount as they are being
incorporated into the belt structure. Upon subsequent relaxation of
the belt, the elastic members such as elastic strands 26 will
contract laterally toward their unstrained lengths. This causes the
layers of nonwoven material 25a, 25b to gather and form ruffles or
rugosities 27 having ridges 28 and valleys 29 generally transverse
to the lengths of the elastic strands 26, and extending in the
z-direction.
[0064] In another example, to adhere the components of the belt
laminate, the elastic strands 26 themselves may be individually
coated with adhesive ("strand coated") prior to incorporation into
the belt laminate. Various coating methods and techniques,
including strand coating methods and techniques, are shown for
example in U.S. Pat. Nos. 5,340,648; 5,501,756; 5,507,909;
6,077,375; 6,200,635; 6,235,137; 6,361,634; 6,561,430; 6,520,237;
6,582,518; 6,610,161; 6,613,146, 6,652,693, 6,719,846 and
6,737,102. The adhesive used may be a hot-melt type adhesive having
elasticity and flexibility making it suitable for attaching
pre-strained elastic materials to substrates, such as OMNIMELT
BLOCKS 22 H2401F, or ZEROCREEP brands such as AVANCE, available
from Bostik, Inc., Wauwatosa, Wis.
[0065] Referring to FIG. 2A, the rear belt portion 23 may have a
greater longitudinal dimension (i.e., greater length) than the
front belt portion 22. This may help provide greater coverage of
the wearer's buttocks area in the rear while providing greater
comfort in front, via better conformity with wearer anatomy and
natural body movement. In the example of FIG. 2A, when the two
portions 22, 23 are joined at side seams with their respective
waist edges 34, 35 substantially aligned, however, the rear leg
edges 18 will lie below the front leg edges to form a stepped leg
edge profile at the seams. If deemed undesirable, this effect may
be mitigated by selecting, disposing and/or varying pre-strain
levels among the elastic members as suggested and described in, for
example, U.S. Pat. App. Ser. No. 62/042,387, to laterally draw the
lower rear corners of the rear belt portion inward toward the
longitudinal axis y. A potential desirable result of such practice
is schematically suggested in FIG. 6A.
[0066] Alternatively, the lower rear corners of the rear belt
portion may be trimmed off as suggested in FIGS. 2B and 6B. The
lower rear corners may be trimmed off along straight lines as
suggested in FIGS. 2B and 6B, or may be trimmed off along trim
paths (not shown) that are curved and either concave or convex with
respect to the remaining area of the rear belt portion 23, as may
be desired to impart a particular curved rear leg edge profile. In
conjunction with such trimming and the configuration of elastic
strands described above, it may be desired to impart bonding 40
between layers 25a, 25b along edges 18 of rear belt portion 23.
Such bonding may serve to prevent any separation of the layers
along edges 18 that may contribute to creating a ragged appearance,
and may also help the rear belt portion more effectively draw
inward laterally toward the central chassis 30, under the
contractive force of the elastic strands below seams 24. Bonding 40
may be effected by mechanical/compression bonds as described in,
for example, U.S. Pat. Nos. 4,854,984 and 4,919,738, by thermal
bonds or welds, or by deposits of adhesive between layers 25a, 25b.
As suggested in FIG. 2B, such bonding may form a pattern along
edges 18. Such bonding may be supplemental to any bonding between
layers 25a, 25b generally holding rear belt portion 23 together as
a laminate structure.
[0067] Side seams 24 may be permanent or refastenable. Permanent
seams may be formed between the front belt portion and the rear
belt portion by any bonding mechanism wherein the front and rear
belt portions may not be forcibly separated without substantial
damage to one or both of the front and rear belt portions, or
without any included mechanism by which substantial reattachment or
refastening may be effected. Bonding forming permanent seams may
include compression bonding, thermal bonding/welds, ultrasonic
bonding or adhesive bonding. Refastenable seams may be formed
between the front belt portion and the rear belt portion by any
mechanism configured to permit substantially non-destructive
forcible separation of the front and rear belt portions, and
subsequent substantial reattachment or refastening at the same
locations. One example of such mechanism is a hook-and-loop
fastening system, for example, a VELCRO fastening system. A
suitably sized and shaped hooks component may be bonded to one of
the front or rear belt portions along the longitudinal edges
thereof, and a suitably sized and shaped loops component may be
bonded to the other of the front or rear belt portions along the
longitudinal edges thereof, in positions in which they may be
brought together and engaged to form seams 24. Examples are
depicted in U.S. Pat. App. Ser. Nos. 61/787,416; 61/787,332;
61/666,065.
[0068] Absorbent Structure
[0069] The absorbent structure 115 is a three-dimensional structure
including a substrate layer 116 and an absorbent layer 117
including absorbent polymer particles, and optionally cellulose,
supported by, and immobilized on, said substrate layer 116.
Examples of absorbent structures 115 are illustrated in FIGS. 8,
10A, 10B, 14, 15A and 15B.
[0070] The substrate layer 116 of the absorbent structure may be
any material capable of supporting the absorbent polymer particles.
It may be a web or sheet material, such as foam, film, woven and/or
nonwoven material.
[0071] Nonwoven materials and processes for making them are
generally known in the art. Generally, processes for making
nonwoven materials include two steps: depositing and accumulating
fibers to the desired basis weight onto a forming surface, and
consolidating and bonding the accumulated fibers to form a coherent
web. The first step may include spunlaying, meltblowing, carding,
airlaying, wetlaying, coforming and combinations thereof. The
bonding step may include hydroentanglement, cold calendering, hot
calendering, through air thermal bonding, chemical bonding, needle
punching, and combinations thereof.
[0072] The nonwoven material may be a laminate. The laminate may
include spunbond layer(s) (S), and/or meltblown layer(s) (M),
and/or carded layer(s) (C). Suitable laminates include, but are not
limited to, SS, SSS, SMS or SMMS. The nonwoven material may have a
basis weight from about 5 to 100 gsm, or from about 8 to 40 gsm, or
from about 8 to 30 gsm. Woven or nonwoven materials may include
natural fibers or synthetic fibers or combinations thereof. The
substrate layer 116 and the absorbent layer 117 may be coextensive
or the substrate layer 116 may be slightly longer and wider than
the absorbent layer 117 (as suggested in FIGS. 8, 10A, 10B, 14 and
15.
[0073] The absorbent layer 117 may include absorbent polymer
particles 150, and optionally cellulose. The absorbent layer may
include absorbent polymer in other forms such as absorbent polymer
fibers. Absorbent polymer particles will be described in further
detail below. The absorbent polymer particles may be used alone or
in combination with other materials. In some examples, the
absorbent layer includes absorbent polymer particles combined with
cellulose. "Cellulose" as used herein refers to comminuted wood
pulp in the form of fibers, sometimes also referred in the art as
"air-felt". In some examples, the absorbent layer includes more
than 70%, or more than 80%, or more than 90%, or more than 95% or
even 100% by weight of absorbent polymer particles. In some other
examples, the absorbent layer includes absorbent polymer particles
and less than 5% by weight of cellulose, or less than 2% by weight
of cellulose, or even substantially no cellulose. In examples
wherein the absorbent layer is cellulose free, the only absorbent
material in the absorbent layer is the absorbent polymer
(particles, fibers, etc.). The resulting absorbent structures have
a reduced thickness in the dry state compared to conventional
absorbent structure including cellulosic fibers. The reduced
thickness helps to improve the fit and comfort of the absorbent
article for the wearer.
[0074] The absorbent layer 117 may include at least two main
channels 126. Referring to FIGS. 2A, 2B and 8-14, "channels" as
used herein refers to troughs or other identifiable elongate
passageways through the deposit of absorbent polymer particles of
the absorbent layer, partially or entirely extending through the
z-direction thickness of the absorbent layer 117 and characterized
by areas of comparatively reduced mass per unit spatial volume
density of absorbent polymer particles in the space occupied by the
absorbent structure, or even by areas that are substantially free
of absorbent polymer particles, i.e. substantially no absorbent
polymer particles are present in such volume (longitudinal channel
or secondary channel) of an absorbent structure. The channels may
have two shorter boundaries 128 (in the shortest dimension) at
their ends and two longer boundaries 127 (in the longest dimension)
along their sides, connecting the shorter boundaries. The shorter
boundaries may be straight (e.g., perpendicular to the longer
boundaries), or angled, or curved. The channels may have an average
width w of at least 3 mm (the average width of a channel is defined
as the average distance between the longer boundaries), or of at
least 4% of the transverse width N of the absorbent layer.
[0075] The channels may be permanent. By permanent, it is meant
that the integrity of the channels is substantially maintained both
in dry state and wet state, i.e. the channels are substantially
resistant to the effects of wetting (e.g., structure is maintained
by materials that are insoluble in water), and substantially
withstand mechanical stresses in the materials caused by swelling
of absorbent polymer particles, pressure within the structure
resulting therefrom, and the wearer's body movements. Permanent
channels may be formed by immobilizing the absorbent polymer
particles on the substrate layer, such as by applying a
thermoplastic adhesive material over the absorbent layer. The
absorbent layer of the present disclosure may also include
permanent channels formed by permanently bonding of a first
substrate layer (116) and a second substrate layer (116') together
along the channels, thereby, in one example, forming chambers that
separate and contain absorbent polymer particle deposits and
thereby define the channels therethrough. Adhesive may be used to
bond the substrate layers 116, 116' together along the channels,
but it is possible to bond the substrate layers together via other
means, for example, ultrasonic bonding, pressure bonding or thermal
bonding. The supporting layers may be continuously bonded or
intermittently bonded along the channels.
[0076] The absorbent layer may have two channels 126 located in the
absorbent layer 117 such that the absorbent layer is divided by
channels into three sections in the crotch region 123. As shown in
FIGS. 2A, 2B and 8-10, the channels may be present in the crotch
region of the absorbent layer. In some examples, the two channels
may extend longitudinally along at least 15%, or at least 20% or at
least 30% and up to 50%, or up to 70% or up 90% of the length M of
the absorbent layer (i.e. they may extend over a distance L which
is at least 15% and up to 50%, or up to 70% or up 90% of the length
M of the absorbent layer). In some examples, the channels may be
present only in the crotch region 123. When present only in the
crotch region, the channels may extend over the whole longitudinal
dimension of the crotch region, e.g. 50% of the length M of the
absorbent layer, or they may extend in only part of the crotch
region, i.e. from at least 15%, or at least 20% or at least 30% to
40%, or to 45% or to less than 50% of the length of the absorbent
layer. In some examples, the channels 126 may be present in the
crotch region, or part thereof, and part of the front region and/or
part of the back region (such as shown in FIGS. 8-10). In some
examples, the channels may be present in the front and crotch
regions, i.e. the channels extend from the crotch region (or part
thereof) into the front region. In some examples, the channels may
be present in the back and crotch regions, i.e. the channels extend
from the crotch region (or part thereof) into the back region. The
channels 126 may be mirror images of one another with respect to
the longitudinal axis y of the absorbent layer 117, i.e. the
channel in one longitudinal region 120 may be mirror image of the
longitudinal main channel in the other longitudinal region of the
absorbent layer 117.
[0077] In some examples, it may be desired that the channels 126 do
not extend all of the way to one or both of the transverse edges
119 (front and back) of the absorbent layer 117, i.e. from one
transverse edge to the other. The absorbent layer may include,
along each transverse edge and adjacent to said edge, an end
deposit of absorbent polymer particles free of channels which
extends in the transverse dimension of the absorbent layer from one
longitudinal edge 118 of the absorbent layer 117, to the other.
Such end deposits may have respectively a width F' or G' which are
at least 5% of the longitudinal dimension of the absorbent layer
(i.e. a width which is at least 5% of the length of the absorbent
layer). In other words, the smallest distance F' or G' between the
edge of a channel and the transverse edge of the absorbent layer is
at least 5% of the longitudinal dimension M of the absorbent layer.
In some examples, the width F' or G' is at least from 5% to 15%, or
to 10% of the longitudinal dimension of the absorbent layer.
[0078] Furthermore, in order to reduce the risk of fluid leakage
and run-off, it may be desired that the channels do not extend to
the longitudinal edges 118 of the absorbent layer 117. The
absorbent layer may include, along each longitudinal edge, a side
deposit of absorbent polymer particles free of channels, which
extends the length M of the absorbent layer from one transverse
edge 119 to the other. Such side deposits may have respectively a
width I' or H' which is at least 5%, or at least 10%, or at least
12% to 25% of the width N of the absorbent layer in a given region
(i.e. a width I' or H' which is at least 5% of the width N of the
absorbent layer). In other words, the minimum distance I' or H'
between the edge of a channel and the longitudinal edge 118 of the
absorbent layer is at least from 5% to 25% of the transverse
dimension of the absorbent layer. For example, the distance I' or
H' in the crotch region may correspond to at least 5%, or to at
least 10% or at least 12% of the transverse dimension N of the
absorbent layer in said crotch region. In some examples, the
distance I' and/or H' is of 10 mm, or 15 mm or 20 mm.
[0079] The channels may be substantially straight, and may run
substantially parallel to the longitudinal axis y of the absorbent
layer (as shown schematically in FIGS. 10A, 10B and 11A). Straight
channels may serve as hinge structures in the absorbent structure,
which may help enable the absorbent structure to flex
longitudinally and thereby better conform to the wearer's anatomy
along the transverse direction through the crotch region, and may
also help enable the absorbent structure to form a containing shape
better suited to receiving and containing liquid exudate before it
is completely absorbed, when the pant is worn. Longitudinally
extended channels also may help improve fluid transportation and
distribution along the length of the deposits of absorbent polymer
particles within the absorbent structure, and thereby may help
speed liquid absorption.
[0080] Alternatively, the channels may be curved and/or arcuate, as
suggested in FIGS. 8, 9, 12 and 13. Longitudinally extended but
curved channels may also serve as hinge structures in the absorbent
structure which may help enable the absorbent structure to flex
longitudinally and thereby conform to the wearer's anatomy along
the transverse direction in the crotch region. Thus, the channels
may contribute to imparting a comfortable and superior fit in
addition to permitting improved liquid transportation and
distribution.
[0081] The channels 126 may include oblique channels, as suggested
in FIGS. 11C, 12 and 13, i.e., substantially straight channels
oriented at an angle .theta. of up to 30 degrees, or up to 20
degrees, or up to 10 degrees with respect to the longitudinal
central axis y of the absorbent structure.
[0082] In some other alternatives, the channels may be angled
channels, as suggested in FIG. 11D. Angled channels are channels
made of two or more portions connected under an angle .sigma. to
one another. Angled channels may be made of two portions connected
under an angle .beta. of at least 150 degrees, or at least 160
degrees or at least 170 degrees.
[0083] The channels 126 may have an average width w of from 3 mm to
15 mm, or from 4 mm to 14 mm or from 5 mm to 12 mm (the average
width of a channel is the average distance between its longer
boundaries 127). The average width of the channels may be at least
4% of the width of the absorbent layer, or at least 7% and up to
15%, or 20% or 25%. In some examples, the channels may have an
average width w of from 3 mm to 18 mm, or from 5 mm to 15 mm or
from 6 to 10 mm.
[0084] The channels 126 may be separated in the crotch region by a
distance D (illustrated in FIG. 8) of at least 5%, or at least 10%,
or at least 20%, or at least 25% of the transverse dimension
(width) of the absorbent layer in said crotch region. It is
believed that when these two channels are separated by a distance
of at least 5% of the transverse dimension of the absorbent layer
in the crotch region, the absorbent structure is more likely to
conform to the wearer's anatomy along the transverse direction and
form a containing structure in the crotch region when the pant is
worn. In some examples, the channels may be separated in the crotch
region by a distance of at least 10 mm, or at least 15 mm, or at
least 20 mm, or at least 30 mm. In some examples, the distance
separating the channels in the crotch region is from 20 to 30
mm.
[0085] Longitudinally-oriented channels formed in the absorbent
layer may help transport and distribute liquid (e.g., urine) along
the lengths of the deposits of absorbent polymer particles in the
absorbent layer, and thereby help speed acquisition and absorption.
However, the correspondingly-defined longitudinal chambers or other
structures containing or defining the deposits of absorbent polymer
particles may develop elevated internal pressure as the particles
absorb liquid, swell, and press against each other. This pressure
may have a longitudinal, structural stiffening effect on the
absorbent structure. The internal pressure causes the absorbent
layer to tend to straighten longitudinally, rather than easily
curve around and beneath the wearer's lower torso as the absorbent
structure wraps between the wearer's legs. This stiffening effect
may help prevent creation of a droopy or saggy appearance of the
article when wetted. On the other hand, it has been discovered, as
schematically illustrated in FIG. 7, this stiffening effect can
cause the frontward and rearward ends of the absorbent structure to
bulge away from the wearer's body in frontward and rearward
directions, creating noticeable, unsightly, and potentially
uncomfortable bulges 219 proximate the frontward and rearward ends
of the absorbent layer. It has been discovered that this effect may
be mitigated by one or more of several alternative configurations
in a pant structure.
[0086] As suggested in FIGS. 12 and 13, the absorbent layer may
include additional secondary channels 126' to further increase the
fluid transportation and/or fit of the absorbent article. The above
description of channels may equally apply to any of said secondary
channels 126'. However, in some examples, the secondary channels
may be shorter than the channels described above.
[0087] The longitudinal secondary channels may extend over a
distance V' of at least 10%, or at least 15%, or at least 20% of
the longitudinal dimension M of the absorbent layer (as illustrated
in FIG. 13). They may extend up to 90% of the longitudinal
dimension of the absorbent layer. The longitudinal secondary
channels may extend up to 30% or 45% of the longitudinal dimension
of the absorbent layer.
[0088] The absorbent layer may include one or more secondary
channels, such as two, three, four, five or six. Secondary channels
may be present in the front region, back region and/or crotch
region of the absorbent layer. The absorbent layer may include an
even number of secondary channels. The secondary channels may be
distributed in the absorbent layer such that each longitudinal
region of the absorbent layer includes an equal number of secondary
channels. In some examples, the longitudinal regions including the
channels (i.e. main longitudinal channels and secondary channels)
are mirror images of each other with respect to the central
longitudinal axis of the absorbent layer.
[0089] As suggested in FIGS. 14 and 17-19, in other examples the
absorbent layer also may include one or more transverse secondary
channels 129. Transverse channels 129 may have their longer
dimensions oriented predominately in the transverse direction, or
even be substantially perpendicular to the longitudinal axis y of
absorbent layer 117. Transverse channels may serve as transverse
hinge structures that can enable the absorbent structure to flex
laterally and thereby conform to the wearer's anatomy along the
longitudinal direction as it wraps around and beneath the wearer's
lower torso between the legs from front to back. This may help
mitigate the longitudinal stiffening effects of channels as
illustrated in FIG. 7.
[0090] Transverse channels may be disposed above the lower edge 21
of the belt (FIG. 17), or below it (FIG. 18), although for better
appearance and control of the shape of the loaded absorbent layer,
when only one or two transverse channels are present, it may be
preferred that one or both be disposed above the lower edge of the
belt (as suggested in FIG. 17). In alternative examples, one or
more transverse channels may be disposed between the lateral axis x
and the lower edge 21 of the front belt portion and/or the rear
belt portion.
[0091] Transversely-oriented secondary channels 129 may extend over
a distance of at least 10%, or at least 15%, or at least 20%, of
width N of the absorbent layer. They may extend up to 90% of the
transverse dimension of the absorbent layer. The transverse
secondary channels 129 may extend up to 30% or 45% of the
transverse dimension of the absorbent layer. In some examples,
transverse channels 129 may connect main channels 126, as suggested
in FIG. 19. In some examples, transverse channels 129 may be
distinct and separate from main channels 126, as suggested in FIGS.
14, 17 and 18.
[0092] The channels may be sized and located in the absorbent layer
such that a central deposit of absorbent polymer particles
extending along the central longitudinal axis of the absorbent
layer (and including said axis) from one transverse edge to the
other one, and having a width D' of at least 5%, or at least 10%
and up to 60%, or up to 70%, or up to 75% of the transverse
dimension of the absorbent layer remains free of channels. The
absorbent polymer particles may be substantially continuously
present in such a central deposit. For example, a central deposit
may have a width D' of at least 5 mm, or at least 10 mm, or at
least 15 mm or 20 mm and up to 70 mm or up to 40 mm. The absence of
channels in such a central deposit is advantageous since it at
least inhibits the diaper from taking an inverted V-shape
configuration (along the transverse direction) in the crotch region
when the pant is worn. An inverted V-shape configuration may
increase the risk of liquid leakage along the leg openings. In some
examples, the average basis weight of absorbent polymer particles
in such a central deposit is relatively high, i.e. at least 350 gsm
and up to 1000 gsm, or for example from 450 gsm to 750 gsm, and
higher than the basis weight at other locations of the absorbent
layer.
[0093] In other examples, the absorbent layer structure defining
the channels 126 and corresponding longitudinally-oriented volumes
containing deposits of absorbent polymer particles may be imparted
with features that cause the structure to change from a first
configuration when dry to a second configuration when wetted to,
e.g., one-quarter, one-third, one-half, two-thirds or more of the
total absorbent capacity (by weight of absorbed liquid) of the
absorbent layer. For example, materials used to form longitudinal
chambers or other structures containing or defining correspondingly
longitudinally-oriented deposits of absorbent polymer particles,
and defining channels among/between them, may be configured to
change structure when wetted. In one example, illustrated with
reference to FIGS. 15A and 15B, an absorbent structure 115 may have
a first configuration when dry (e.g., FIG. 15A) and a second
configuration when wetted (e.g., FIG. 15B), e.g., to more than half
of its absorbent capacity. One mechanism that may be used to enable
this may be a water soluble or otherwise releasable adhesive
affixing substrate layers 116 and 116' together along, and thereby
defining, channels 126. Upon wetting and/or outward pressure
against layers 116 and 116' from the swelling deposits of absorbent
polymer particles, the adhesive releases, and the swelling deposits
of absorbent polymer particles are permitted to expand into the
volume previously defined by the channels 126, which then may
reduce in size or even disappear as suggested in FIG. 15B. This may
have the effect of relieving pressure within the absorbent layer
117 and absorbent structure 115, which may lessen the longitudinal
stiffening effects described above. Thus, advantages of channels
(flexibility, conformability and liquid distribution enhancement)
may be enjoyed at times before the pant is substantially wetted,
while a disadvantage of channels (longitudinal stiffness) may be
mitigated at times after the pant has been substantially
wetted.
[0094] This changing channel structure may be utilized alone or may
be combined with permanent channel structures of any desired
configuration, including but not limited to any configuration
described herein.
[0095] In a further example, main channels 126 may have a length in
the longitudinal direction. The length may be divided into three,
four, five or more sublengths. The structure defining the channels
may be configured to permanently define the channels along one or
more of the sublengths, but to changeably define the channels along
other of the sublengths, such that they reduce in size or disappear
upon wetting. In one example, channels are permanently defined in
areas proximate the lateral axis x of the pant, and are
changeably/releaseably defined, e.g., as described above, in areas
further away from the lateral axis x. In some examples, one or more
sublengths at and/or proximate the ends of the channels are
changeable/releaseable upon wetting. In one particular example, one
or more longitudinal main channels 126 are divided into five
sublengths. The intermediate sublength may be permanently defined,
while the two sublengths toward each end of the channel may be
changeably/releaseably defined such that they reduce in size or
disappear upon wetting as described above. In alternative examples
including one or more longitudinally oriented channels, a portion
of the channel(s) may be permanent and a portion of the channel(s)
may be temporary or releasable. The temporary portions of the
channel(s) may be disposed between the lateral axis x and a lower
edge 21 of the belt. In some examples the temporary portion of the
channel may be disposed at one or both of the ends of the channel
and may occupy between 10 and 25% of the dry length of the channel
at one or both ends. The temporary portions of the channel may also
be disposed intermittently along the length of the channel and may
alternate with permanent portions of the channel.
[0096] In another alternative, which may if desired be combined
with any combination of the channel features described above, the
absorbent layer 117 may extend longitudinally such that one or both
ends 119 thereof are disposed beneath one or all layers of belt
portions 22, 23 when the pant is worn. Non-limiting examples are
suggested in FIGS. 16A-19. In a particular aspect, all
longitudinally-oriented main channels 126 may extend such that one
(FIGS. 16A, 16B) or both (FIG. 16C) ends thereof are disposed to
the wearer side of one or both belt portions 22, 23 when the pant
is worn. Non-limiting examples are suggested in FIGS. 16A-16D and
19. As a result, the ends of longitudinal chambers or other
structures containing or defining deposits of absorbent polymer
particles will, accordingly, be disposed to the wearer side of one
or both belt portions when the pant is worn. In such a
configuration, when the longitudinal chambers or other structures
containing or defining deposits of absorbent polymer particles
become longitudinally stiff from internal pressure as a result of
liquid absorption, one or both ends thereof will be subject to
lateral tensile forces in the belt portion(s). This may help
restrain the end(s) of absorbent layer and hold them closer to the
wearer's body, and thereby help prevent them from forming the
bulges 219 such as are schematically illustrated in FIG. 7.
[0097] The absorbent layer, absorbent structure and/or
configuration of channels may also have any features described in
U.S. Pat. App. Pub. Nos. US2014/0163511; US2014/0163503;
US2014/0163501; US2014/0163500; US2012/0316526; US2012/0316528;
US2014/0163501; and US2014/0371701.
[0098] Absorbent Layer
[0099] The absorbent layer may include absorbent polymer particles
150 alone or in combination with other materials, such as cellulose
fiber. The absorbent polymer particles may be immobilized on a
substrate layer by, for example, a thermoplastic adhesive material
140.
[0100] Absorbent polymer particles suitable for use in the
absorbent layer may include any absorbent polymer particles known
from superabsorbent literature, for example such as described in
Modern Superabsorbent Polymer Technology, F. L. Buchholz, A. T.
Graham, Wiley 1998.
[0101] The absorbent polymer particles may be spherical,
spherical-like, ellipsoid, or irregularly shaped, such as
ovoid-shaped particles of the kind that may be obtained from
inverse phase suspension polymerizations. The particles may,
optionally, be agglomerated at least to some extent to form larger
irregular agglomerations of particles.
[0102] The absorbent polymer particles may be selected from among
polyacrylates and polyacrylate based materials that are internally
and/or surface cross-linked, such as for example partially
neutralized cross-linked polyacrylates or acid polyacrylate.
Examples of absorbent polymer particles suitable in the present
disclosure are described for instance in the PCT Pat. App. Nos. WO
07/047598, WO 07/046052, WO2009/155265 and WO2009/155264.
[0103] In alternative examples, the absorbent layer may be
substantially cellulose-free. Airfelt and other cellulose fiber
have been used as absorbent fillers in absorbent cores of
disposable diapers. Such fiber possesses absorbent properties and
imparts some absorption capacity to an absorbent layer, but also
may be included to provide a structural matrix to hold dispersed
particles of absorbent polymer particles. While inclusion of such
particles enhances absorption capacity, keeping such particles
suitably dispersed may be important to prevent the particles from
"gel-blocking" in use as they swell with absorbed liquid and block
the passageways therebetween which allow liquid to move through
deposits thereof, compromising absorption capacity. The inclusion
of airfelt or other cellulose fiber as a matrix for absorbent
polymer particles can serve to reduce or prevent gel-blocking.
However, it also imparts bulk to an absorbent layer, even before
absorption of any liquids. To reduce the overall size and/or
thickness of the absorbent layer, and thereby improve wearer
comfort and reduce the bulkiness of the pant for purposes of
packaging and shipping volume efficiency, it may be desired to
construct an absorbent core using the lowest volumes of core
materials possible within performance constraints. Toward this end,
examples of suitable materials and constructions for a suitable
absorbent structure are described in, but are not limited to, U.S.
patent application Ser. Nos. 12/141,122; 12/141,124; 12/141,126;
12/141,128; 12/141,130; 12/141,132; 12/141,134; 12/141,141;
12/141,143; and Ser. No. 12/141,146; and WO2008/155699. Generally,
these applications describe absorbent layer constructions that
minimize or eliminate the need for and inclusion of airfelt or
other forms of cellulose fiber in combination with particles of
absorbent polymer particles ("substantially cellulose-free"
structures). Suitable methods for forming deposits of absorbent
polymer particles are additionally disclosed in, for example, EP
1621167 A2, EP 1913914 A2 and EP 2238953 A2.
[0104] The absorbent polymer particles may be immobilized on the
substrate layer. Immobilization may be achieved by applying a
thermoplastic adhesive material, which holds and immobilizes the
absorbent polymer particles, and cellulose when present, on the
substrate layer. Some thermoplastic adhesive material may also
penetrate into the layer of absorbent polymer particles and into
the substrate layer to provide further immobilization and
affixation. The thermoplastic adhesive material may not only help
in immobilizing the absorbent polymer particles on the substrate
layer but also may help in maintaining the integrity of the
channels. The thermoplastic adhesive material avoids that a
significant amount of absorbent polymer particles migrates into the
channels.
[0105] Thermoplastic adhesive materials suitable for use in the
present disclosure includes hot melt adhesives including at least a
thermoplastic polymer in combination with a plasticizer and other
thermoplastic diluents such as tackifying resins and additives such
as antioxidants. Example suitable hot melt adhesive materials are
described in EP 1447067 A2.
[0106] In some examples, the absorbent core may include an
acquisition system, which is disposed between the topsheet and the
wearer facing side of the absorbent structure. The acquisition
system may serve as a temporary reservoir for liquid until the
absorbent structure can absorb the liquid. The acquisition system
may include a single layer or multiple layers, such as an upper
acquisition layer facing towards the wearer's skin and a lower
acquisition layer facing the garment of the wearer. The acquisition
system may be in direct contact with the absorbent structure. In
these examples, the acquisition system may fill in the channels or
portions thereof of the absorbent structure. In some examples, the
acquisition system, or one layer thereof, may be bonded to the
substrate layer which undulates into the channels thus providing an
undulating profile to said acquisition system.
[0107] As suggested in FIG. 15, the absorbent layer of the
absorbent structure may include an acquisition/distribution layer
131. Layer 131 may have the form of, e.g., a layer, mat or other
body formed of or including, e.g., comminuted cellulose fibers, or
other hydrophilic natural, semi-synthetic or synthetic fibers or
other material that may be used to form a mat, layer or other
body.
[0108] In one example, one or both of the upper and lower
acquisition layers may include a non-woven, which may be
hydrophilic. Further, according to a certain example, one or both
of the upper and lower acquisition layers may include the
chemically cross-linked cellulosic fibers, which may or may not
form part of a nonwoven material. According to an example, the
upper acquisition layer may include a nonwoven, without the
cross-linked cellulosic fibers, and the lower acquisition layer may
include the chemically cross-linked cellulosic fibers. Further,
according to an example, the lower acquisition layer may include
the chemically cross-linked cellulosic fibers mixed with other
fibers such as natural or synthetic polymeric fibers. According to
example examples, 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, eucalyptus fibers and mixtures thereof.
Suitable non-woven materials for the upper and lower acquisition
layers include, but are not limited to SMS material, including a
spunbonded, a melt-blown and a further spunbonded layer. In certain
examples, permanently hydrophilic nonwovens, and in particular,
nonwovens with durably hydrophilic coatings are desirable. Another
suitable example includes an SMMS-structure. In certain examples,
the nonwovens are porous.
[0109] Other Belt/Chassis Features
[0110] Referring to FIG. 20, elastic members such as elastic
strands 26 may be configured within the front and/or rear belt
portion(s) 22, 23 such that they are present in lower side zones
22'', 23'' of the belt portions, but not present in part of all of
lower laterally central zones 22', 23' that overlie the chassis 30.
Thus, one or both belt portions may be configured such that one or
more of the layers that sandwich the elastic strands 26 are present
in lower central zones 22', 23' of the belt portions, such as
nonwoven layers 25a, 25b (see FIG. 3), without elastic stretch
enabled by the presence pre-strained elastic members and ruffles of
laterally gathered material. In the central zones 22', 23' that
overlie the chassis, the nonwoven layer(s) of one or both belt
portions 22, 23 may be disposed and affixed to the chassis
material(s) (such as the backsheet) such that they overlie the
chassis in laterally extended condition, i.e., they do not have
longitudinal ruffles or rugosities (e.g., ruffles or rugosities 27,
illustrated in FIGS. 4 and 5) that would otherwise be imparted by
lateral contraction of pre-strained, sandwiched lateral elastic
strands. In this configuration, the fully extended belt layer
material(s) overlying the chassis 30 in lower central zones 22',
23', being without longitudinal ruffles and thereby being unable or
less able to elastically stretch laterally as compared to the other
elasticized, ruffled zones of the belt portions, are configured to
provide greater resistance to lateral expansion, supplementing that
of the chassis materials and helping to support and restrain the
ends of absorbent layer 117. As a result, protrusion of outward
bulges 219 upon absorption of liquid by the absorbent layer 117
(such as those illustrated in FIG. 7), may be reduced. This feature
may be combined with any of the channel configurations described
above, for potentially synergistic effects in reducing protrusion
of bulges of the absorbent layer 117 as described above. Thus, in
one example illustrated in FIG. 20, the forward ends of main
longitudinal channels 126 may be disposed beneath (to the
wearer-facing side) of non-elasticized lower central zone 22' of
front belt portion 22. In some examples, the belt portions and the
chassis may be configured to have features described in
PCT/CN2014/094890, which describes additional examples of belt
configurations having non-elasticized portions overlying the
chassis.
[0111] In a further example, one or more elastic strands 26 present
in the lower side zones 22'', 23'' may be selected (e.g., by
decitex and/or tensile modulus) and/or configured (e.g., by
longitudinal numerical count/unit longitudinal dimension of the
belt, and/or amount of imparted pre-strain) to impart greater
tensile contractive force to the belt structure in one or more of
the lower side zones 22'', 23'' than in the upper zone(s) closer to
the waist edges. This latter example may help enhance comfort of
the pant, when worn, by providing for relatively lesser lateral
contractive tensile force about the waist band areas and waist
edges, and relatively greater lateral contractive tensile force
with greater support, resistance to bulging of the channeled
absorbent layer, and anchoring of the pant about the wearer's lower
hips. Thus, one or more of the elastic strands 26 in one or both of
lower side zones 22'', 23'' may have one or more of greater
decitex, greater tensile modulus, greater number of strands 26 per
unit longitudinal length of the belt portion, or greater amount of
pre-strain, than one or more of the elastic strands 26 in the upper
zone(s) closer to the waist edges in the same front or rear belt
portion. This feature may be incorporated alone, or in combination
with, the inclusion of non-elasticized central zone(s) 22', 23' of
the belt described immediately above.
[0112] 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. For example, a dimension
disclosed as "40 mm" is intended to mean "about 40 mm."
[0113] Every document cited herein, including any cross referenced
or related patent or application and any patent application or
patent to which this application claims priority or benefit
thereof, 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.
[0114] While particular examples 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 may 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.
* * * * *