U.S. patent application number 14/789056 was filed with the patent office on 2015-10-29 for disposable absorbent product with coated element and related methods.
This patent application is currently assigned to SCA Hygiene Products AB. The applicant listed for this patent is SCA Hygiene Products AB. Invention is credited to Frank Stephen GLAUG, Michael Franklin KALMON.
Application Number | 20150305949 14/789056 |
Document ID | / |
Family ID | 48536866 |
Filed Date | 2015-10-29 |
United States Patent
Application |
20150305949 |
Kind Code |
A1 |
GLAUG; Frank Stephen ; et
al. |
October 29, 2015 |
DISPOSABLE ABSORBENT PRODUCT WITH COATED ELEMENT AND RELATED
METHODS
Abstract
A disposable absorbent product includes a topsheet defining an
interior face of the disposable absorbent product configured to
face a wearer thereof during use. A backsheet overlays the
topsheet, with the backsheet defining an exterior face of the
disposable absorbent product configured to face away from the
wearer during use. An absorbent core is disposed between the
topsheet and the backsheet for storing fluid secreted by the wearer
of the disposable absorbent product. The absorbent core includes at
least one absorbent structure and a wrapping element that envelops
the at least one absorbent structure. The wrapping element has a
main substrate layer and an adhesive coating layer thereon that is
substantially adhered to the substrate layer and which defines an
impermeable film layer on the substrate.
Inventors: |
GLAUG; Frank Stephen;
(Chester Springs, PA) ; KALMON; Michael Franklin;
(Ball Ground, GA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SCA Hygiene Products AB |
Goteborg |
|
SE |
|
|
Assignee: |
SCA Hygiene Products AB
Goteborg
SE
|
Family ID: |
48536866 |
Appl. No.: |
14/789056 |
Filed: |
July 1, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13561513 |
Jul 30, 2012 |
9095479 |
|
|
14789056 |
|
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Current U.S.
Class: |
604/365 ;
156/213 |
Current CPC
Class: |
A61F 2013/5349 20130101;
A61F 13/534 20130101; A61F 13/15666 20130101; A61F 2013/53908
20130101; A61F 2013/8402 20130101; A61F 2013/15406 20130101; A61F
13/53 20130101; A61F 13/539 20130101; A61F 13/15585 20130101; A61F
2013/530481 20130101 |
International
Class: |
A61F 13/539 20060101
A61F013/539; A61F 13/53 20060101 A61F013/53; A61F 13/15 20060101
A61F013/15; A61F 13/534 20060101 A61F013/534 |
Claims
1. A disposable absorbent product comprising: a topsheet defining
an interior face of the disposable absorbent product configured to
face a wearer thereof during use; a backsheet overlaying said
topsheet, said backsheet defining an exterior face of the
disposable absorbent product configured to face away from the
wearer during use; and an absorbent core disposed between said
topsheet and said backsheet for storing fluid secreted by the
wearer of the disposable absorbent product, said absorbent core
including at least one absorbent structure and a wrapping element
enveloping said at least one absorbent structure, said wrapping
element having a main substrate layer and an adhesive coating layer
thereon substantially adhered to said main substrate layer,
substantially adhered to said at least one absorbent structure, and
defining an impermeable film layer on said main substrate
layer.
2. The disposable absorbent product of claim 1, wherein said main
substrate layer completely envelops said at least one absorbent
structure, thereby defining a wrapping element with four walls
surrounding said at least one absorbent structure, said four walls
including two side walls, a top wall adjacent said topsheet, and a
bottom wall adjacent said backsheet.
3. The disposable absorbent product of claim 1, wherein said
disposable absorbent product is free of any impermeable film layers
disposed between said bottom wall and said backsheet.
4. The disposable absorbent product of claim 2, wherein said top
wall is substantially free of said adhesive coating layer.
5. The disposable absorbent product of claim 1, wherein said main
substrate layer only partially envelops said at least one absorbent
structure, thereby defining a wrapping element with three walls
surrounding said at least one absorbent structure, said three walls
including two side walls, and a bottom wall adjacent said
backsheet, said wrapping element being substantially free of a wall
opposite said bottom wall, adjacent said topsheet.
6. The disposable absorbent product of claim 5, wherein said main
substrate layer and said adhesive coating layer have respective
pairs of lateral ends, said lateral ends of said main substrate
layer generally coinciding with said lateral ends of said adhesive
coating layer.
7. The disposable absorbent product of claim 1, wherein said at
least one absorbent structure comprises first and second absorbent
structures, said first absorbent structure being primarily
configured for acquisition and distribution of fluid secreted by
the wearer and said second absorbent structure being primarily
configured for storage of fluid secreted by the wearer.
8. The disposable absorbent product of claim 7, wherein said first
absorbent structure is substantially free of granular
components.
9. The disposable absorbent product of claim 1, wherein said
adhesive coating layer is formed from a hot-melt adhesive.
10. The disposable absorbent product of claim 1, wherein said
adhesive coating layer is tacky at room temperature.
11. The disposable absorbent product of claim 1, wherein said
adhesive coating layer has a basis weight of less than about 20
g/m2.
12. The disposable absorbent product of claim 11, wherein said
adhesive coating layer has a basis weight no greater than about 10
g/m2.
13. The disposable absorbent product of claim 12, wherein said
adhesive coating layer has a basis weight of at least about 5 g/m2
but less than about 10 g/m2.
14. The disposable absorbent product of claim 1, wherein said
backsheet is made of a nonwoven material.
15. A disposable absorbent product comprising: a hydrophilic
topsheet defining an interior face of the disposable absorbent
product configured to face a wearer thereof during use; a nonwoven
backsheet overlaying said topsheet, said backsheet defining an
exterior face of the disposable absorbent product configured to
face away from the wearer during use; and an absorbent core
disposed between said topsheet and said backsheet for storing fluid
secreted by the wearer of the disposable absorbent product,
wherein: said absorbent core includes at least one absorbent
structure and a wrapping element enveloping said at least one
absorbent structure, said wrapping element having a main substrate
layer and an adhesive coating layer thereon, said adhesive coating
layer defining an impermeable film layer on said main substrate
layer, said adhesive coating layer is substantially adhered to said
at least one absorbent structure, said adhesive coating layer is
formed from a hot-melt adhesive, is tacky at room temperature, and
has a basis weight of less than about 20 g/m2, and the disposable
absorbent product is free of any impermeable barriers disposed
between said bottom wall and said exterior face of the disposable
absorbent product.
16. A method for forming an absorbent core for use in a disposable
absorbent product, wherein the absorbent core is disposed between a
backsheet and a topsheet overlaying one another, the method
comprising: obtaining an absorbent structure primarily configured
for storage of fluid secreted by a wearer of the disposable
absorbent product; obtaining a main substrate layer; applying a
coat of adhesive material onto the main substrate layer to thereby
define an impermeable film layer on the main substrate layer; and
enveloping the absorbent structure with the adhesive-coated main
substrate layer so as to substantially adhere the coat of adhesive
material to the absorbent structure, and to thereby define the
absorbent core.
17. The method of claim 16, further comprising: dispensing the
adhesive material from a non-contact slot coating device and onto
the main substrate layer.
18. The disposable absorbent product of claim 1, wherein said
wrapping element has two side walls and a bottom wall extending
there between, said impermeable film layer extending continuously
along one of said side walls, along said bottom wall, and along the
other of said side walls.
19. The disposable absorbent product of claim 1, wherein said
adhesive coating layer includes a plasticizer.
20. The disposable absorbent product of claim 1, wherein said main
substrate layer directly contacts said at least one absorbent
structure.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 13/561,513, filed on Jul. 30, 2012. The entire
contents of U.S. application Ser. No. 13/561,513 are hereby
incorporated herein by reference in their entirety.
TECHNICAL FIELD
[0002] The present invention is generally related to absorbent
products and, more particularly, to disposable absorbent products
that are worn by humans for the containment and absorption of fluid
bodily secretions.
BACKGROUND
[0003] Disposable absorbent products for absorption of bodily
fluids are available in different types, designs, and dimensions.
For example, training pants, baby diapers, adult diapers, and
incontinence guards are products designed for the containment of
urine and excrement. There are other types of disposable absorbent
articles, such as feminine hygiene products (e.g., heavy and light
incontinence pads, pantiliners) that are designed to contain and
absorb urine and/or menses secreted by female wearers. Known
products of this type typically include a topsheet facing the body
of the wearer, a backsheet facing the garment worn by the wearer,
and an absorbent core sandwiched between the topsheet and
backsheet.
[0004] The absorbent core in products of the type described above
include a main absorbent structure that is configured to distribute
and store fluids secreted by the wearer, as well as other
components such as acquisition components and the like. The main
absorbent structure in conventional products has granular storage
components, such as Super Absorbent Particles ("SAP"), that gel-up
when placed in contact with urine or other fluids secreted by the
wearer. Prior to gelling-up, however, these granular components may
be hard, which may cause discomfort to the wearer, or even poke
through the surrounding layers of material.
[0005] In order to minimize the problems associated with the hard
granular components, manufacturers of disposable absorbent products
of this type often wrap the main absorbent structure of the
absorbent core with a thin layer of paper, which allows passage of
fluid therethrough while preventing exposure of the granular
components through the topsheet. Wrapping with a thin layer of
paper also maintains the granular components in the intended target
area within the disposable absorbent product, which enhances
containment of the secreted fluids.
[0006] But wrapped-core designs of the type described above often
require an additional barrier layer of material, such as an
impermeable polyethylene-based layer, located between the wrapped
core and the backsheet of the product. This is to prevent fluid
stored in the core from reaching the backsheet, which may be
undesirable. The presence of the additional barrier layer increases
the cost and complexity in the manufacturing of the disposable
absorbent product.
[0007] Accordingly, it is desirable to provide disposable absorbent
products that address these and other shortcomings of conventional
disposable absorbent products.
SUMMARY
[0008] In one embodiment, a disposable absorbent product is
provided that includes a topsheet defining an interior face of the
disposable absorbent product configured to face a wearer thereof
during use. A backsheet overlays the topsheet, with the backsheet
defining an exterior face of the disposable absorbent product
configured to face away from the wearer during use. An absorbent
core is disposed between the topsheet and the backsheet for storing
fluid secreted by the wearer of the disposable absorbent product.
The absorbent core includes at least one absorbent structure and a
wrapping element that envelops the at least one absorbent
structure. The wrapping element has a main substrate layer and an
adhesive coating layer thereon that is substantially adhered to the
substrate layer and which defines an impermeable film layer on the
substrate.
[0009] In specific embodiments, the main substrate layer completely
envelops the at least one absorbent structure, thereby defining a
wrapping element with four walls surrounding the at least one
absorbent structure. The four walls include two side walls, a top
wall adjacent the topsheet, and a bottom wall adjacent the
backsheet. Additionally, the disposable absorbent product may be
free of any additional impermeable film layers disposed between the
bottom wall and the backsheet. The at least one absorbent structure
comprises, in specific embodiments, first and second absorbent
structures. The first and second absorbent structures may be both
primarily configured for storage of fluid secreted by the
wearer.
[0010] The top wall may be substantially free of the adhesive
coating layer. In other embodiments, the main substrate layer only
partially envelops the at least one absorbent structure, thereby
defining a wrapping element with three walls surrounding the at
least one absorbent structure. The three walls include two side
walls, as well as a bottom wall adjacent the backsheet. The
wrapping element in those embodiments is substantially free of a
wall opposite the bottom wall, adjacent the topsheet. The main
substrate layer and the adhesive coating layer have, in some
embodiments, respective pairs of lateral ends, with the lateral
ends of the main substrate layer generally coinciding with the
lateral ends of the adhesive coating.
[0011] In embodiments having first and second absorbent structures,
the first absorbent structure may be primarily configured for
acquisition and distribution of fluid secreted by the wearer, while
the second absorbent structure may be primarily configured for
storage of fluid secreted by the wearer. The first absorbent
structure is, in specific embodiments, at least substantially free
of granular components. Additionally or alternatively, the first
absorbent structure may be at least substantially free of super
absorbent material.
[0012] The adhesive coating layer is formed, in some embodiments,
from a hot-melt adhesive. Additionally or alternatively, the
adhesive coating layer may be tacky at room temperature. The
adhesive coating layer may have a basis weight of less than about
20 g/m.sup.2. In specific embodiments, the adhesive coating layer
has a basis weight no greater than about 10 g/m.sup.2. For example,
the adhesive coating layer may have a basis weight of at least
about 5 g/m.sup.2 but less than about 10 g/m.sup.2. Additionally or
alternatively, the backsheet is made of a nonwoven material.
[0013] In another embodiment, a disposable absorbent product is
provided having a hydrophilic topsheet defining an interior face of
the disposable absorbent product configured to face a wearer
thereof during use. The product also has a nonwoven backsheet
overlaying the topsheet, with the backsheet defining an exterior
face of the disposable absorbent product configured to face away
from the wearer during use. An absorbent core is disposed between
the topsheet and the backsheet for storing fluid secreted by the
wearer of the disposable absorbent product. The absorbent core
includes at least one absorbent structure and a wrapping element
enveloping the at least one absorbent structure. The wrapping
element has a main substrate layer and an adhesive coating layer
thereon, with the adhesive coating layer being formed from a
hot-melt adhesive, being tacky at room temperature, and having a
basis weight of less than about 20 g/m.sup.2. The disposable
absorbent product in that embodiment is free of any additional
impermeable barriers disposed between the bottom wall and the
backsheet.
[0014] In yet another embodiment, a method is provided for forming
an absorbent core for use in a disposable absorbent product, in
which the absorbent core is disposed between a backsheet and a
topsheet overlaying one another. The method includes obtaining an
absorbent structure primarily configured for storage of fluid
secreted by a wearer of the disposable absorbent product, and
obtaining a main substrate layer. A coat of adhesive material is
applied onto the main substrate layer to thereby define an
impermeable film layer on the main substrate layer, and the
absorbent structure is enveloped with the coated main substrate
layer to thereby define the absorbent core. The method may
additionally include dispensing the adhesive material from a
non-contact slot coating device and onto the main substrate
layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The objectives and features of the invention will become
more readily apparent from the following detailed description taken
in conjunction with the accompanying drawings in which:
[0016] FIG. 1 is a perspective view of a disposable absorbent
product in accordance with one embodiment of the invention.
[0017] FIG. 2 is a perspective view of a disposable absorbent
product in accordance with another embodiment of the invention.
[0018] FIG. 3 is a disassembled, schematic perspective view of the
disposable absorbent product of FIG. 1 or FIG. 2.
[0019] FIG. 4 is a perspective view of an absorbent core of the
product of FIG. 3.
[0020] FIG. 5 is a cross-sectional view taken generally along line
5-5 of FIG. 1.
[0021] FIG. 6 is a cross-sectional view similar to FIG. 5, in
accordance with another embodiment of the invention.
[0022] FIG. 7 is a cross-sectional view similar to FIGS. 5 and 6,
in accordance with yet another embodiment of the invention.
DETAILED DESCRIPTION
[0023] To the extent that any meaning or definition of a term in
this written document conflicts with any meaning or definition of
the term in a document incorporated by reference, the meaning or
definition assigned to the term in this written document shall
govern. Also, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including,"
"comprising," or "having" and variations thereof herein is meant to
encompass the items listed thereafter and equivalents thereof as
well as additional items.
[0024] With reference to the figures, and more particularly to
FIGS. 1 and 2, an exemplary disposable absorbent product in the
form of a diaper 10 is illustrated. Diaper 10 could be a baby
diaper or an adult diaper ("brief") or a belted undergarment, for
example. While these and other figures refer to a disposable
absorbent product in the form of a diaper, it is contemplated that
one or more of the features described and/or illustrated herein are
applicable to other types of disposable absorbent products, and
these are therefore not limited to the exemplary diapers described
herein. For example, and without limitation, one or more of the
various features described herein may be also used in closed
pant-type products such as the exemplary training pant 10a shown in
FIG. 2. Yet other products contemplated herein include but are not
limited to adult-size disposable pads, feminine catamenial pads, or
male or female light-incontinence, medium-incontinence, or
heavy-incontinence pads.
[0025] For ease of understanding, exemplary details are described
with reference to "diaper 10," which is the embodiment illustrated
in FIG. 1, though it is understood that the features and functions
described with respect to that embodiment are similarly applicable
to the embodiment of FIG. 2 or to any other embodiments of the
types generally described herein. Diaper 10 includes a topsheet 12
and a backsheet 14 disposed opposite the topsheet 12, such that the
topsheet 12 and backsheet 14 are in an overlaying relationship with
one another. In use, the topsheet 12 at least partially defines an
interior face of the diaper 10 that faces the body of the wearer.
The backsheet 14, by contrast, faces away from the body of the
wearer and at least partially defines an exterior face of the
diaper 10. The topsheet 12 is made of a permeable, hydrophilic
material such as a hydrophilic nonwoven, and may be in the form of
a single, continuous layer across the length and/or width of the
diaper 10, or may alternatively be in the form of two or more
layers of the same material or of materials different from one
another that jointly, rather than individually, span the length
and/or width of the diaper 10.
[0026] The backsheet 14 includes an impermeable, hydrophobic
material such as a hydrophobic spunbond nonwoven or a laminate made
of one or more layers of nonwoven materials and one or more layers
of an impermeable polypropylene or polyethylene film. Backsheet 14
may be in the form of a single, continuous layer across the length
and/or width of the diaper 10, or may alternatively be in the form
of two or more layers of the same material or of materials
different from one another that jointly, rather than individually,
span the length and/or width of the diaper 10.
[0027] With continued reference to FIGS. 1-2, and further referring
to FIGS. 3-4, the diaper 10 also includes an absorbent core 16 that
is disposed between the topsheet 12 and the backsheet 14, and which
is configured to absorb and retain body fluids, such as urine
and/or menses, secreted by the wearer. The core 16 may have a
single main absorbent structure or may instead have, as in the
exemplary embodiment of FIG. 3, first and second absorbent
structures 16a, 16b, each made up of fluff pulp or a combination of
fluff pulp or some other natural or synthetic fluid management
material, and a fluid storage material such as SAP or some other
natural or synthetic fluid storage material. More specifically in
the embodiment of FIG. 3, the core 16 includes an upper absorbent
structure 16a that is supported by a larger bottom absorbent
structure 16b.
[0028] Those of ordinary skill in the art will readily appreciate
that the absorbent structures 16a, 16b may have relative dimensions
and shapes that are different from those shown in FIG. 3, and still
fall within the scope of the present disclosure. Each of the
absorbent structures 16a, 16b in that embodiment is primarily
configured for storage of fluid, such as urine, that is secreted by
the wearer of the disposable absorbent product. Alternatively, one
of the absorbent structures 16a, 16b may be primarily configured
for fluid storage, while the other of the absorbent structures 16a,
16b is primarily configured for rapid acquisition and distribution
of fluid toward other components of the core 16 that are primarily
configured for fluid storage. For example, and without limitation,
the upper absorbent structure 16a may be an airlaid-based material,
while the lower absorbent structure 16b may be have a mixture of
fluff pulp and SAP or some other granular fluid storage component.
Alternatively, the bottom (i.e., second) absorbent structure 16b
may also be an airlaid-based material.
[0029] Exemplary airlaid-based materials of the type discussed
above are known as "VH600.101.B6001" and "VH460.103.B6001," both
commercially available from Glatfelter Falkenhagen GmbH, of
Falkenhagen, Germany. Other exemplary materials for upper absorbent
structure 16a are foam-based materials such as those known as High
Internal Phase Emulsion (HIPE) foams, of the types described, for
example, in U.S. Pat. Nos. 5,387,207; 5,260,345, 5,650,222; and
5,849,805, the respective entire disclosures of which are hereby
expressly incorporated by reference herein.
[0030] Core 16, as well as the diaper 10 of which core 16 forms
part, extend along a longitudinal axis 10x (longitudinal
dimension), and along a transverse axis 10y (width dimension)
orthogonal to the longitudinal axis 10x. The core 16 could be
generally rectangular, or have an hourglass shape, or have any
other regular or irregular, symmetrical or asymmetrical shape, and
still fall within the scope of the present disclosure.
[0031] With continued reference to FIGS. 1-4, the core 16 of the
illustrated embodiment includes a thin wrapping element 26 of
permeable, hydrophilic material such as paper or a hydrophilic
nonwoven. Wrapping element 26 envelops the absorbent structures
16a, 16b so as to prevent exposure of granular components of the
core 16, such as granular SAP, to surrounding layers. Further,
wrapping element 26 maintains the different components of absorbent
structures 16a, 16b together, which enhances the dry and wet
integrity of core 16, thereby enhancing fluid containment.
[0032] With continued reference to FIGS. 1-4, and further referring
to FIG. 5, wrapping element 26 includes a main substrate layer 29
and a continuous coating 30 of a film barrier adhesive material
formed on the interior face of main substrate layer 29. More
specifically, wrapping element 26 includes a coating 30 of an
adhesive material that is also impermeable, with the impermeability
being such that it prevents the transfer of fluid secreted by the
wearer from the absorbent structures 16a, 16b onto the backsheet 14
of diaper 10. The impermeability of coating 30 makes it unnecessary
to provide an additional barrier layer adjacent the backsheet 14,
and thereby simplifies the manufacturing of diaper 10. Further, the
adhesive functionality of coating 30 also enhances the dry and wet
integrity of core 16, by virtue of the engagement of SAP, fluff
pulp and/or any other components of core 16 by the adhesive coating
30, which fixes those components in place.
[0033] The coating 30 has suitably chosen levels of tackiness and
impermeability. For example, and without limitation, coating 30 may
be a hot-melt adhesive that is generally tacky at room temperature
i.e., between about 18.degree. C. and about 23.degree. C.
Similarly, coating 30 may be substantially impermeable be virtue of
being substantially or completely free of pin-holes at basis
weights that are less than about 20 g/m.sup.2. In specific
embodiments, the coating 30 is substantially or completely free of
pin-holes at basis weights between about 10 g/m.sup.2 and about 20
g/m.sup.2, or even at basis weights that are less than about 10
g/m.sup.2, such as basis weights between about 5 g/m.sup.2 and
about 10 g/m.sup.2. Exemplary materials for coating 30 are
materials known by the names Lunatack.RTM. NW 1192 ZP.RTM.,
Lunatack.RTM. D-8370, Lunatack.RTM. D-9105, and Lunatack.RTM.
D-3964, all of which are hot-melt adhesives commercially available
from the H.B. Fuller Company, of St. Paul, Minn., United States of
America. Exemplary hot-melt adhesives suitable for coating 30
include at least one thermoplastic polymer (up to about 40% by
weight), at least one plasticizer (up to about 40% by weight), and
at least one tackifying resin (up to about 70% by weight).
[0034] These non-limiting examples of hot-melt adhesives may have a
low melting point temperature, such as in the range of about
60.degree. C. to about 110.degree. C. These relatively low melting
point temperatures facilitate application of coating 30 to
materials such as paper and thin nonwoven substrates that are
susceptible to damage when exposed to high temperatures. In
addition, the rheological properties of some of these hot-melt
adhesives facilitate the application of a continuous, moisture
and/or fluid impermeable coating at low basis weights. More
specifically, hot-melt adhesives are contemplated for coating 30 in
which the complex viscosity at high shear rates (1,000 rad/sec) is
less than about 500 poise and the complex viscosity at low shear
rates (<1 rad/sec) is between about 100 and about 1,000 poise.
Thermoplastic-containing hot-melt adhesives of this type thus
exhibit Newtonian regions at low shear rates and shear thinning at
high shear rates. These hot-melt adhesives substantially adhere to
the surface of main substrate layer 29 without deeply penetrating
into the main substrate layer 29, forming a fluid (i.e., liquid)
and/or moisture impermeable film barrier layer on main substrate
layer 29.
[0035] Coating 30 is applied to the main substrate layer 29 of
wrapping element 26 in a suitably chosen thickness, such as one
corresponding to a basis weight anywhere in the range between about
5 g/m.sup.2 and about 20 g/m.sup.2, or any other basis weight. In a
specific embodiment, the basis weight is about 15 g/m.sup.2.
Application of the coating 30 onto main substrate layer 29 is
carried out through a suitably chosen process for applying a
coating in liquid form, such as a hot-melt adhesive, so as to
define an impermeable film coating that is substantially adhered to
the main substrate layer 29. For example, and without limitation,
coating 30 may be applied onto main substrate layer 29 with a slot
coater that dispenses the coating material but which does not
contact the main substrate layer 29. This results in a
substantially uniform, continuous coating of the coating material
(e.g., hot-melt adhesive) onto the main substrate layer 29. An
exemplary process suitable to apply the coating 30 is described in
U.S. Pat. No. 7,078,075, the entire contents of which are hereby
expressly incorporated by reference herein.
[0036] The main substrate layer 29 is also suitably chosen and may,
for example, be in the form of a layer of tissue-type paper, having
a basis weight of about 18 g/m.sup.2. The main substrate layer 29
may instead be in the form of a layer of a nonwoven material and
still fall within the scope of the present disclosure. An exemplary
material for main substrate layer 29 is known as a tissue of "Grade
3253," commercially available from the Cellu Tissue Holdings, Inc.
of East Hartford, Conn., United States of America.
[0037] With particular reference to FIG. 5, the lateral extent of
main substrate layer 29 and of coating 30 are chosen so as not to
interfere with the flow of fluid into the core 16. Specifically, in
the embodiment illustrated in that figure, the lateral extent of
main substrate layer 29 is such that same completely encases the
absorbent structures 16a, 16b, with the lateral ends 31, 32 of main
substrate layer 29 overlapping one another, as illustrated at the
top of FIG. 5. As used herein, the term "lateral extent" refers to
the extent, in the width direction of diaper 10, to which a
particular folded component (e.g., layer) extends if that component
were to be laid flat rather than in its folded configuration. The
wrapping element 26 thus defines top and bottom walls 33, 34 and
side walls 35 that contain the absorbent structures 16a, 16b
therein. The coating 30 only extends partially in the width
direction of diaper 10. More specifically, the coating 30 in the
illustrated embodiment laterally extends so as to cover the bottom
wall 34 and side walls 35, while leaving the top wall substantially
free of coating 30. This design allows for the ready passage of
fluid received through the topsheet 12 into the interior 37 of core
16, while preventing fluid from escaping through the bottom wall 34
or the side walls 35. Further, the adhesive properties of coating
30 engage portions of the absorbent structures 16a, 16b therein,
which enhances integrity of core 16, thereby enhancing product
appearance and fluid containment.
[0038] With reference to FIG. 6, another embodiment is illustrated
of a core 46, similar in most respects to the core 16 of the
preceding figures, but having a single absorbent structure 16b,
rather than two such structures. In FIG. 6, like reference numerals
refer to similar features in the preceding figures, the description
of which may be referred-to for an understanding of the structure
and functional aspects of the embodiment in this figure as
well.
[0039] Referring now to FIG. 7, yet another embodiment is
illustrated of a core 56. Like reference numerals in that figure
refer to similar features in the preceding figures, the description
of which may be referred-to for an understanding of the structure
and functional aspects of the embodiment in this figure as well. In
the embodiment illustrated in FIG. 7, the lateral extent of the
main substrate layer 29 and of coating 30 are the same or at least
substantially the same, such that the lateral ends 31, 32 of main
substrate layer 29 generally coincide with the lateral ends 57a,
57b of the coating 30. Notably in this embodiment, the lateral
extents of the main substrate layer 29 and coating 30 define an
encasement for core 56 that, unlike the embodiments of FIGS. 5 and
6, is substantially free of a top wall. More specifically, core 56
has a wrapping element 52 that defines a bottom wall 58 and side
walls 60, all of which include portions of the main substrate layer
29 and coating 30. In this embodiment, the flow of fluid through
the topsheet 12 and into the interior 61 of core 56 is completely
unrestricted, while the presence of coating 30 in the bottom and
side walls 58, 60 prevents the flow of fluid through those
walls.
[0040] Still referring to the embodiment of FIG. 7, the adhesive
properties of coating 30 allow the lateral end portions 63 of
wrapping element 52 to adhere to the top surface 65 (i.e., adjacent
topsheet 12) of the upper absorbent structure 16a, as illustrated
in the figure. In specific embodiments, the upper absorbent
structure 16a is designed to contain no SAP or any other type of
granular components, which therefore obviates the need for complete
encasing of the upper and lower absorbent structures 16a, 16b. In
that regard, and as explained above, the upper absorbent structure
16a may be in the form of a layer of a material predominantly
intended for rapid acquisition and/or distribution of fluid, such
as a SAP-free airlaid-based acquisition layer, for example, which
is at least substantially, if not completely, free of SAP.
Alternatively, in another non-limiting example, the upper absorbent
structure 16a may have a zoned distribution of SAP or other
granular materials, such that any portion of the top surface 65
that is exposed to the topsheet 12 is at least substantially, if
not completely, free granular components. For example, in the
illustrated embodiment, the exposed portion of top surface 65 may
be completely free of granular components, while the unexposed
portions i.e., those portions directly under the end portions 63 of
wrapping element 52, contain granular components.
[0041] Referring generally to the embodiments of FIGS. 1-7, the
integration of an impermeable film barrier layer in the form of a
liquid coating 30 with the main substrate layer 29 of wrapping
element 26, 52 is advantageous in several different aspects. First,
this integration provides liquid and/or moisture impermeability to
the main wrapping element 26, 52, without the crackling that would
arise, for example, if the main substrate layer 29 was instead
bonded with a solid layer of impermeable film material subsequent
to forming of the film material. Crackling in diapers and other
disposable absorbent products is known to be undesirable because it
may lead to the awareness by the wearer and/or by those around
him/her, that a disposable product is being worn by the wearer. In
addition, the complete integration of the film barrier layer with
main substrate layer 29 makes the film barrier layer less
susceptible to cracking of that material, thereby contributing to
enhanced core integrity during use of the product. Avoiding the
formation of cracks in a film is also advantageous because film
cracks have been observed to define channels that increase the
likelihood of leakage of fluids (e.g., urine) in disposable
products. Core integrity could be further enhanced by using a
liquid coating 30 of an adhesive material having elastomeric
properties, due to the elasticity of the resulting film barrier
layer on the main substrate layer 29.
[0042] Another advantage is that the application of a coated
impermeable film barrier provides flexibility to manufacturers to
easily apply, control, and adjust the level and location of
impermeable zones to the wrapping element 26, 52. More
specifically, the flow of the liquid form of coating 30 can be
easily controlled and adjusted during application, as is typically
the case, for example, with hot-melt adhesive dispensing. This
facilitates adjustment of the desired level of impermeability,
which may depend, for example, on the type or thickness of the
material used for the main substrate layer 29. This also
facilitates easy adjustment of the length and/or width dimensions
of the coating 30. Further, this integration provides a method for
applying an impermeable film layer to the wrapping element 26, 52
without the need to introduce additional, complex processes and
equipment required, for example, to bond a solid layer of film
barrier material to the solid main substrate layer 29. Yet another
advantage is provided by the adhesive nature of some embodiments of
the coating 30, which permits wrapping element 26, 52 to hold the
components making up core 16, 46, 56 in place.
[0043] From the above disclosure of the general principles of the
present invention and the preceding detailed description of
exemplary embodiments, those skilled in the art will readily
comprehend the various modifications to which this invention is
susceptible. Accordingly, this invention is intended to be limited
only by the scope of the following claims and equivalents
thereof.
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