Note: Descriptions are shown in the official language in which they were submitted.
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HIGHLY ABSORBENT PAD WITH INTEGRITY AND DURABILITY
BACKGROUND OF THE INVENTION
[0001] Absorbent articles for absorption of body fluids are available in a
number of different
designs. For absorption of urine and excrement, use is generally made of
diapers or
incontinence guards. There are other types of absorbent articles, such as
feminine hygiene
products. These products typically include a top sheet facing the body of the
user, a back
sheet facing the garment of a user, and an absorbent layer sandwiched between
the inner, top
sheet and outer, back sheet.
[0002] With prior art hygiene products, the absorbent core has been made of
bulky fluff
pulp material. As such, there has been a movement towards the use of thinner,
higher SAP
content cores. However, a drawback to these types of cores is a lack of
integrity. In some
situations, the typical mat formed absorbent cores are totally replaced by
highly compressed
air laid structures. For example, U.S. Patent Publication No. 2005/0045296
describes an
airlaid composite core with pulp, superabsorbent material and bicomponent
binder fibers.
[0003] However, one drawback to using airlaids in moderate to heavy absorbency
incontinence pads is that these pads tend to be very stiff when the basis
weight is increased
and the thickness is decreased. In addition, because airlaids tend to be
thinner and more
compact, airlaid cores have sometimes a higher liquid penetration and
absorption time.
Accordingly, there is a need in the art for a material that allows for
improved liquid
distribution, yet also allows the material to retain its shape/thinness while
being pliable.
SUMMARY
[0004] According to a first aspect of the invention, there is provided an
absorbent article
comprising a back sheet, a top sheet, and an absorbent core therebetween. The
absorbent
core passes a tumbling test, and the article has a thickness when compressed
laterally and
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released in a core resiliency test of less than 7 mm for an article having a
Rothwell value
from about 260 to about 399 g.
[0005] According to a second aspect of the invention, there is provided an
absorbent
article comprising a back sheet, a top sheet, and an absorbent core
therebetween. The
absorbent core passes a tumbling test and the article has a thickness when
compressed
laterally and released in a core resiliency test of less than 11 mm for an
article having a
Rothwell value from about 400 to about 800 g.
[0006] According to a third aspect, there is provided an absorbent article
comprising a
back sheet, a top sheet, and an absorbent core therebetween. The absorbent
core is an airlaid
material including two or more layers, and is made from a superabsorbent
polymer, pulp, and
bicomponent fibers, wherein the bicomponent fibers are disposed adjacent a top
surface and
bottom surface of the absorbent core.
[0007] A further feature of the first and second aspects is that the absorbent
core is made
of an airlaid material.
[0008] Yet a further feature of the first and second aspects is that the
airlaid material
includes two or more layers.
[0009] Yet a further feature of the second aspect is that the article has a
Rothwell value
from about 400 to about 600 g.
[0010] Yet a further feature of the first, second and third aspects is that
the airlaid
material comprises 0-10% by weight of a tissue or nonwoven layer, 20-65% by
weight of
pulp, 30-60% by weight of a superabsorbent polymer, 0-5% by weight polymer
dispersion
binder, and 2-10% by weight of bicomponent fibers.
[0011] Yet a further feature of the first, second and third aspects is that
the airlaid
material comprises 2.5%-4.5% by weight the tissue or nonwoven layer, 35-55% by
weight of
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pulp, 40-50% by weight of the superabsorbent polymer, 1-3% by weight polymer
dispersion
binder, and 4-7% by weight of bicomponent fibers.
[0012] Yet a further feature of the first, second and third aspects is that
the airlaid
material comprises 40-50% by weight of pulp.
[0013] Yet a further feature of the first, second and third aspects is that a
top surface and
a bottom surface of the airlaid material is treated with a polymer dispersion
binder.
[0014] Yet a further feature of the first, second and third aspects is that
the absorbent core
is an airlaid having a first layer, a second layer, and a third layer and the
second layer is
interposed between the first and third layers, the first and third layer being
made from pulp
and bicomponent fibers, and optionally superabsorbent polymers, the second
layer is made
from pulp and superabsorbent polymer.
[0015] Yet a further feature of the first, second and third aspects is that
the first, third and
an optional fourth layer contain bicomponent fibers, and optionally a polymer
dispersion
binder.
[0016] Yet a further feature of the first, second and third aspects is that
the absorbent core
includes an inner line and an outer line on each side of a longitudinal
centerline, each the
inner lines and outer lines including a plurality of slits having spaces
therebetween.
[0017] Yet a further feature of the first, second and third aspects is that
one or both of the
outer line and the inner line are shaped as crescents.
[00181 Yet a further feature of the first, second and third aspects is that
the absorbent
article is an incontinence pad or a sanitary napkin.
BRIEF DESCRIPTION OF THE DRAWINGS
[00191 The patent or application file contains at least one drawing executed
in color.
Copies of this patent or patent application publication with color drawings
will be provided
by the Office upon request and payment of the necessary fee.
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[0020] The accompanying drawings provide visual representations which will be
used to
more fully describe the representative embodiments disclosed herein and can be
used by
those skilled in the art to better understand them and their inherent
advantages. In these
drawings, like reference numerals identify corresponding elements and:
[0021] FIG. 1 illustrates a perspective view of an exemplary absorbent article
according
to the features of the present invention.
[0022] FIG. 2 illustrates an exploded view of an exemplary absorbent article
according to
the features of the present invention.
[0023] FIG. 3 is a schematic showing a cross section of an exemplary absorbent
article
according to the features of the present invention.
[0024] FIG. 4 is a cross sectional view of an airlaid absorbent core according
to features
of the present invention.
[0025] FIG. 5 is a perspective view of a base structure of a dosing apparatus
used to test
features of the present invention.
[0026] FIG. 6 is a perspective view of a funnel of the dosing apparatus used
to test
features of the present invention
[0027] FIG. 7 is a perspective view of the dosing apparatus used to test
features of the
present invention
[0028] FIG. 8 is a side elevational view of the clamping apparatus used to
test features of
the present invention.
[0029] FIG. 9 is a top plan view of the clamping apparatus used to test
features of the
present invention.
[0030] FIG. 10 is a top plan view of the absorbent article secured by one
clamp according
to testing methods described herein.
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[0031] FIG. 11 is a top plan view of the absorbent article secured by two
clamps
according to testing methods described herein.
[0032] FIG. 12 is a perspective view of the dosing apparatus positioned on an
absorbent
article between side walls of the clamping apparatus.
[0033] FIG. 13 is a perspective view of the absorbent article in a clamped
position.
[0034] FIG. 14 is a perspective view of the absorbent article after being
released from the
clamping apparatus for measurement of the thickness of the absorbent article.
[0035] FIG. 15 is a perspective view of the dosing apparatus on the absorbent
article.
[0036] FIG. 16 is a photograph of an absorbent article according to the prior
art showing
cracks after being run in a pilling box.
[0037] FIG. 17 is a photograph of an absorbent article according to the prior
art showing
cracks after being run in a pilling box.
[0038] FIG. 18 is a photograph of an absorbent article according to the prior
art showing
cracks after being run in a pilling box.
[0039] FIG. 19 is a photograph of an absorbent article according to the prior
art showing
cracks after being run in a pilling box.
[0040] FIG. 20 is a photograph of an absorbent article according to the prior
art showing
cracks after being run in a pilling box.
[0041] FIG. 21 is a photograph of an absorbent article according to features
of the
invention having no cracks after being run in a pilling box.
[0042] FIG. 22 is a photograph of an absorbent article according to features
of the
invention having no cracks after being run in a pilling box.
[0043] FIG. 23 is a photograph of an absorbent article according to features
of the
invention having no cracks after being run in a pilling box.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] The present invention pertains to an absorbent article. An absorbent
article is
defined as an article or garment used for the absorption of body fluids,
including but not
limited to, infant diapers and training pants, adult incontinence products,
feminine hygiene
products, gender specific absorbent products, and pet training absorbent
articles. While the
preferred embodiment illustrates an incontinence pad, it should be understood
that the present
invention pertains to all types absorbent articles.
[0045] With reference to FIGS. 1 and 2, an absorbent article 2 includes a back
sheet 4 and
a top sheet 6 which sandwich an absorbent core 8 therebetween. The top sheet 6
can be
joined together with the back sheet 4 and the absorbent core 8, for example by
means of
adhesive, ultrasonic joining or by means of some form of thermal bonding.
[0046] Preferably, the absorbent core 8 is appropriately manufactured from a
suitable
fiber material in the form of natural or synthetic fibers having absorbent
properties, or a
mixture of natural fibers and synthetic fibers or other absorbent materials of
a previously
disclosed kind that are suitable for use in sanitary towels, incontinence pads
and panty
liners, for example.
[0047] The absorbent core 8 may also contain a predetermined proportion of
superabsorbent polymers (SAP). SAP materials are in the form of particles,
fibers, flakes or
similar, and have the capacity to absorb and to chemically bind liquid
equivalent to several
times their own weight while forming an aqueous gel. This provides a very high
water-
absorbent capacity in the finished product. The absorbent core 8 can exhibit
different forms,
for example an essentially elongated and rectangular form, or alternatively
some other more
irregular form, for example hourglass or triangular form.
[0048] Preferably, the absorbent core 8 includes 30-90% SAP, with a basis
weight of
about between 350 to 1000 g/m, and most preferably between about 400 to 1000
g/m2. The
2
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absorbent core 8 may have a thickness of between about 2 mm to 10 mm and a
density of
between about 0.04 g/cm3 to 0.50 g/cm3.
100491 In addition, the airlaid may be perforated according to the features
described in U.S.
Serial No. 12/695,840, the entire disclose of which is incorporated by
reference herein. For
example, as shown in FIG. 2, the absorbent core 8 may include an inner line 14
and an outer
line 16 on each side of a longitudinal centerline 18, each of the inner lines
14 and outer lines
16 including a plurality of slits 17 therebetween.
[00501 In addition, the absorbent core 8 may be made from two or more layers
of
material. For example, with reference to FIG. 4, the absorbent core 8 may
include a first
layer 24, a second layer 26, a third layer 28, and a tissue or other air
permeable or nonwoven
30. Preferably, the first layer 24 and third layer 28 are made from pulp,
bicomponent fibers,
and optionally SAP. The bicomponent fibers may be made of polyethylene and
polyethylene
terephthalate (PE/PET). The bicomponent fibers act as a bonding agent, giving
the airlaid its
integrity, especially in the wet state. The second layer 26 is preferably made
from pulp and
SAP, and preferably does not include bicomponent fibers. A tissue or other air
permeable or
nonwoven layer 30 may also be included which acts as a carrier during the
manufacturing
process. However, any number of layers and materials may be used depending on
application
and design preference.
[0051] In addition, a polymer dispersion binder may be added to the top
surface 32 and
bottom surface 34 of the absorbent core 8. The polymer dispersion binder helps
reduce dust
and fiber loss. The polymer dispersion binder may be, for example, a latex
binder. The
various layers and materials create a complex shape retention network. As
such, an improved
liquid handling structure is created that distributes liquid evenly and
therefore an even
swelling of the superabsorbent polymer. This in turn allows the material to
retain its
shape/thinness while still delivering in absorbency.
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[0052] Preferably, the airlaid material is made from 0-10% by weight of a
tissue or
nonwoven layer, most preferably about 2.5-4.5% by weight of a tissue or
nonwoven layer,
20-65% by weight pulp, more preferably 35-55% by weight pulp, and most
preferably 40-
50% by weight pulp (preferably either treated or untreated cellulose), 30-60%
by weight of a
superabsorbent polymer, and most preferably about 40-50% by weight of
superabsorbent
polymer, 0-5% by weight polymer dispersion binder, and most preferably 1-3% by
weight
polymer dispersion binder, and 2-10% by weight bicomponent fibers, and most
preferably 4-
7% by weight of bicomponent fibers. It should be understood that all weight %
refer to
weight of the airlaid material.
[0053] The liquid-permeable top sheet 6 may include one or more layers of one
or
more of the following materials: a fibrous material, for example a soft
nonwoven material,
plastic film, mesh, open-celled foam, material laminate, etc. The top sheet 6
may include a
perforated plastic film, for example, a thermoplastic plastic material such as
polyethylene
or polypropylene, or a mesh-like layer of synthetic or textile material.
Synthetic mono-,
bi-, or multi-component fibers, made of polymers such as polyethylene,
polypropylene,
polyester, nylon or the like, are preferably used as a nonwoven material.
Also, natural
fibers can be used in the top sheet, examples of natural fibers are cotton,
regenerated
cellulose, such as rayon, viscose, and silk. Mixtures of different types of
fibers can also be
used for the aforementioned nonwoven material.
[0054] The back sheet 4 is preferably liquid-impermeable (or at least
possesses high resistance
to penetration by liquid) and is thus so arranged as to prevent any leakage of
excreted fluid from
the product. The back sheet 4 may also be vapor-permeable. The back sheet 4
may be
manufactured from a liquid-impermeable material which includes a thin and
liquid-proof plastic
film. For example, plastic films of polyethylene, polypropylene or polyester
can be used for this
purpose. Alternatively, a laminate of nonwoven and plastic film or other
suitable layers of
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material can be used as a liquid-proof back sheet 4. In a previously disclosed
manner, the clothing
side of the back sheet 4 can be provided with beads of adhesive or some other
previously
disclosed attachment means, which can then be utilized for the application of
the product to an
item of clothing.
[0055] The absorbent article can also be provided with wings, that is to say
folding flaps
which are arranged along the sides of the product and can be utilized in
conjunction
with the application of the product.
[0056] With reference to FIGS. 2 and 3, the layers of an exemplary embodiment
of the
absorbent article 2 of the present invention are illustrated. In particular,
an
acquisition/distribution layer 10 may be disposed between the top sheet 6 and
the absorbent core
8, and elastics 12 (not shown in FIG. 3) may be preferably disposed between
the top sheet 6 and
the back sheet 4 along longitudinal sides of the absorbent article 2.
[0057] The acquisition/distribution layer 10 may be in the form of a wadding
material having
an appropriately specified thickness and resilience. The
acquisition/distribution layer 10 may
be made materials other than wadding material, such as an airlaid material,
high loft material, or
perforated films. The acquisition/distribution layer 10 may also incorporate
fibrous materials in
order to impart an appropriately balanced rigidity to it. The
acquisition/distribution layer 10 can
also incorporate an appropriate quantity of thermoplastic fibers in order to
permit ultrasonic
welding.
[0058] For feminine hygiene products and incontinence pads, an adhesive 20 may
be
provided on the garment facing side of the back sheet 4 for securing the
absorbent article 2 onto a
garment of a user. A release paper 22 may be provided adjacent the adhesive 20
layer.
[0059] The absorbent article 2 may be made from numerous other layers, as is
known in
the art. However, the specific layers used may vary, depending on design
preference and
application. For example, other layers not shown may be used, such as an
additional back
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sheet, or any other intervening layer, such as SMS (Spunbond MeltBlown
Spunbond), SSS
(three layers of Spunbond), Carded NW, Hydroentangled, and the like. Likewise,
the
particular number and order of layers is optional, depending on application
and design
preference.
[0060] The absorbent article 2 of the present application has improved
properties over the
prior art absorbent articles. The following testing methods were used to
ascertain the greatly
improved core integrity over prior art absorbent articles.
Inventive Product 1 - Moderate
[0061] The product has, starting from the user facing side , a topsheet, and
acquisition/distribution layer below the topsheet followed by an airlaid core
and finally at the
clothing facing side a backsheet. The topsheet is made of a carded nonwoven
from
Suominen, Finland having a basis weight of 23g/m2. The
acquisition/distribution layer is
made of a through air bonded nonwoven called Paratherm Loft 211 from TWE
Dierdorf,
having a basis weight of 50 g/m2. The core is a three layered core built on a
fourth tissue
layer. The core is supplied from Glatfelter Falkenhagen GmbH in Germany. The
first layer,
facing the user side of the product is made of pulp, bicomponent fibres,
superabsorbent
particles and a latex binder. The second layer is made of pulp and
superabsorbent material.
The third layer is made of pulp, bicomponent fibres and a latex binder. The
fourth layer
closest to the backsheet is a tissue layer. The core has a basis weight of 460
g/m2. The core
is provided with crescent formed rows of slits in the crotch area. There are
two rows on each
side of the longitudinal centre line. These kinds of crescents made of slits
are described in
copending application US 12/395,840. The backsheet is made of a polyethylene
film called
DH-284 PE Microflex from Clopay having a basis weight of 21 g/m2. The
different layers
are glued together.
Inventive Product 2 - Heavy
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The product has, starting from the user facing side , a topsheet, and
acquisition/distribution
layer below the topsheet followed by an airlaid core and finally at the
clothing facing side a
backsheet. The topsheet is made of a carded nonwoven from Suominen, Finland
having a
basis weight of 23g/m2. The acquisition/distribution layer is made of a
through air bonded
nonwoven called Paratherm Loft 211 from TWE Dierdorf, having a basis weight of
50 g/m2.
The core is a three layered core built on a fourth tissue layer. The core is
supplied from
Glatfelter Falkenhagen GmbH in Germany. The first layer, facing the user side
of the
product is made of pulp, bicomponent fibres, superabsorbent particles and a
latex binder.
The second layer is made of pulp and superabsorbent material. The third layer
is made of
pulp, bicomponent fibres and a latex binder. The fourth layer closest to the
backsheet is a
tissue layer. The core has a basis weight of 600 g/m2. The core is provided
with crescent
formed rows of slits in the crotch area. There are two rows on each side of
the longitudinal
centre line. These kinds of crescents made of slits are described in copending
application US
12/395,840. The backsheet is made of a polyethylene film called DH-284 PE
Microflex from
Clopay having a basis weight of 21 g/m2. The different layers are glued
together.
Core Resiliency Test
[00621 A core resiliency test of the present invention determines the
absorbent core
resiliency by way of vertical side compression. Essentially, an absorbent
article is dosed with
a certain amount of liquid. Thereafter, vertical side compression is applied,
and then
released. The thickness of the product after release is measured. A lower
thickness value
correlates to an absorbent core having an improved resiliency. The core
resiliency test was
generated to simulate the compression between the legs on an absorbent
product. It is used to
see how much the product deforms, and then returns to its original position.
100631 The core resiliency test described herein is most useful for absorbent
articles
having a Rothwell value range of between about 260 g to 800 g. A Rothwell
value is defined
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as the total absorption capacity as determined by the International Standard
ISO 11948-
1:1996(E).
[00641 With reference to FIGS. 5-7, a dosing apparatus 40 includes a funnel 42
(shown in
FIGS. 6 and 7) and a base support 44 (shown in FIGS. 5 and 7). As shown in
FIG. 7, the
base structure 44 supports the funnel 42 at a distance above the top surface
of an absorbent
article (not shown) that is placed underneath the base support 44 with the
user side facing up.
[00651 As shown in FIG. 5, the base support 44 includes an upper hollowed
cylindrical
support 46 and a lower hollowed cylindrical support 48. The supports 46 and 48
are
preferably made from stainless steel, and are separated by a distance H of
about 45 mm. The
upper hollowed cylindrical support 46 has an inner diameter of about 12 mm, an
outer
diameter of about 20 mm and a height of about 14 mm. The lower hollowed
cylindrical
support 48 has an inner diameter of about 46 mm, an outer diameter of about 54
mm, and a
height of about 14 mm. Three cylindrical rods 50, also made from metal,
connect the
supports 46 and 48 and are spaced equidistant about the circumference of the
supports 46 and
48. That is, the rods 50 are placed at 0 , 120 , and at 240 . Each rod 50 is
preferably about
48 mm long. The weight of the dosing stand is about 115-125 g.
[00661 With reference to FIG. 6, the dosing apparatus 40 includes a funnel 42.
The
funnel may be either glass or plastic with a capacity of about 100 ml with a
+1-5% weight
tolerance. The funnel 42 preferably has an inner top diameter of about 61 mm
and an outer
top diameter of about 66 mm. The funnel 42 includes a dosing tube 54 at its
lower end to
funnel the liquid to a predetermined location on the absorbent article. The
dosing tip 56 of
the dosing tube is preferably cut at a 45 angle, so that a total length L1 of
the dosing tube is
preferably about 64 mm and the length L2 of the tube from its transition point
58 to the
beginning of the cut portion 60 of the dosing tip 56 is about 55 mm. The
dosing tip 56
preferably has an inner diameter of approximately I 1 mm. Preferably, the
distance between
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the end of the dosing edge of the funnel and the absorbent article should be
between about
10-20 mm.
[0067] With reference to FIGS. 8-12, the clamping apparatus 62 of the core
resiliency test
will be described in more detail. The clamping apparatus 62 includes a pair of
clamps 64A
and 64B, as shown in FIGS. 8 and 9. The clamp 64A is stationary, while the
clamp 64B is
movable. The movable clamp 64B has the ability to slide and be fixed securely
in place. The
clamps 64A and 64B are preferably made of stainless steel, but may be made of
other rigid
and durable materials.
[0068] As shown in FIGS. 8 and 9, the clamps 64A and 64B are secured on a
clamp base
66. Preferably, the clamp base 66 is made from plastic (but may be made of
other materials),
and has a dimension of about 300mm x 400mm. However, other dimensions are
possible, so
long as the absorbent article fits thereon. In addition, at least two pieces
of cork board 68
may be attached to the clamp base 66 so that the absorbent article may be
secured on the
clamping apparatus by pins 70 (see FIG. 9), or the like, during the mounting
procedure. A
clamp base ruler 72 may be disposed along one edge of the clamp base 66 so
that the width of
the absorbent article may be measured, as shown in FIG. 9. In addition, clamp
rulers 74 are
placed on the side vertical surfaces 76 of the clamps 64A and 64B (see FIGS.
10 and 11), so
that the thickness of the absorbent article may be measured before and after
the testing.
[0069] Prior to running the core resiliency test described herein, the
specimens should be
conditioned to room temperature of about (23 +/- 2 oC) with a relative
humidity of about (50
+/- 2%) for at least 24 hours. During the preparation stage, the absorbent
articles should be
removed from their bags and individual wrappings. Once the specimens are
properly
conditioned, release paper should be removed from the specimen (if present)
and baby
powder spread over the adhesive to remove its tackiness, and to prevent the
specimen from
sticking onto itself during the compression period.
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14
[0070] After conditioning, the absorbent articles should be assessed. If an
absorbent
article includes a crack, an unpurposeful partial split/break, or is missing a
section of its
absorbent core, the product should be rejected. In total, thirty absorbent
articles shall be
tested per product variant. The absorbent articles should look identical
taking into
consideration minor process variations. If there is an obvious difference, the
outlier should
be rejected and replaced by another sample.
[0071] Once the absorbent articles are properly prepared, they are ready for
testing. The
first step is to measure the length and width of the absorbent article 2 so
that the center of the
product can be marked. Preferably, the absorbent articles' center line 80 is
marked using a
permanent marker, as shown for example in FIG. 10. That is, absorbent article
2 is marked
along its width at the center of the absorbent article. Preferably, the
thickness of the center
line 80 should be between about 2-5mm in width.
[0072] With reference to FIG. 10, the absorbent article 2 is mounted on the
clamping
apparatus 62 so that the user side of the absorbent article 2 is facing up. A
first side of the
article is clamped using the stationary clamp 64A. A pin 70 may be used to
secure the
absorbent article 2 onto the clamp base 66 while lowering the stationary clamp
64A onto the
absorbent article 2. Preferably, the clamp 64A should cover approximately 10
mm of
material, or sufficient material such that the pad is secured and the edge of
the clamp is in
side contact with the absorbent core. However, the absorbent core should not
be clamped in
the active clamp area during the initial clamping stage.
[0073] With further reference to FIG. 10, the center line 80 of the absorbent
article 2 is
centered on the clamp base 66. The movable clamp 64B is then moved and secured
to the
other side of the absorbent article, as shown in FIG. 11. Preferably, the
clamp 64B should
cover approximately 10 mm of material, or sufficient material such that the
pad is secured
CA 02729532 2011-01-26
and the edge of the clamp is in side contact with the absorbent core. However,
the absorbent
core should not be clamped in the active clamp area during the initial
mounting stage.
[00741 With reference to FIG. 12, the dosing apparatus 40 is placed on top of
the
absorbent article 2 so that the tip 56 of the dosing tube 54 is directly above
the center of the
absorbent article 2 at a distance of between about 10-20 mm. Once the dosing
apparatus 40 is
placed on the top sheet, any wrinkles on the top sheet should be smoothed out.
The absorbent
article 2 is dosed with the appropriate dosing amount. In the present
application, the
absorbent articles 2 are dosed with about 75m1 of 0.9% saline solution (at
room temperature,
i.e., about 23 +/- 2 C) for products with an average Rothwell value range of
260g -800 g.
[00751 The fluid should be dosed at a substantially constant and relatively
slow flow rate.
That is, the dosing liquid should not overflow the lower hollowed cylindrical
support 48 of
the dosing apparatus 40, and the dosing liquid should all be absorbed by the
absorbent article
2 in less than 1 minute. Once all the liquid has been absorbed, the dosing
apparatus 40 is
removed from the absorbent article 2. Using a timer, the absorbent article is
allowed to rest
for precisely 2 minutes.
[00761 Once the product is dosed, the width WI of the absorbent article 2 in
the active
clamping area is measured (see FIG. 12). The movable clamp 64B is then slid
towards the
stationary clamp 64A at a distance of (W1)/2 rounded down to the nearest whole
number.
Once the clamp 64B is slid into position, it is secured at this location (see
FIG. 13).
[00771 Once the clamp 64B is secured in its clamping position, the absorbent
article
remains clamped for two minutes. After two minutes has passed, the clamp 64B
is
disengaged from its holding position by creating a small gap (i.e. 5 mm), and
then, the clamp
64B is moved away from the absorbent product so that it is no longer in
contact with the
absorbent article 2. Before moving the clamp 64B, the absorbent article 2
should not be
CA 02729532 2011-01-26
16
adhered thereto to avoid dragging of the absorbent article when the sliding
clamp 64B is
released.
[0078] Once the absorbent article 2 is released from the clamp 64B, the
absorbent article
2 is allowed to "regain" its original shape for approximately one minute.
After one minute
has passed, the highest thickness of the absorbent article 2 is measured at
its centerline 80, as
shown for example, in FIG. 14 by way of a straight edge 84. The straight edge
84 is placed
on the top surface of the absorbent article without applying pressure to the
sample, so that it
can read the thickness of the absorbent article from the clamp ruler 74 placed
on the vertical
wall 76 of the clamp 64A. The thickness of the straight edge 84 should be
about 0.5mm. The
thickness release is recorded for each of thirty samples, and an average
thickness release is
obtained from the thirty absorbent articles.
[0079] Various testing was performed to verify the increased core integrity.
In particular,
thirty samples of a first inventive product ("Inventive Product 1- Moderate")
were compared
to various prior art absorbent articles, each having a Rothwell value of
between about 260 g
to 399 g. In particular, the Inventive Product 1- Moderate was compared to a
product sold
under the trademark POISE Moderate which is manufactured by Kimberly-Clark,
Inc. The
POISE Moderate includes a top sheet, back sheet, and an absorbent core
therebetween. The
absorbent core includes a small core adjacent the back sheet, and a larger
core on the top side
of the small absorbent core. A highloft material is disposed beneath the top
sheet, and a
tissue layer is disposed between the big core and high loft material.
[0080] Similar comparative testing was performed on several prior art
absorbent articles
including the TENA Moderate Regular manufactured by SCA Hygiene Products, and
the
OPTIONS Moderate manufactured by First Quality and distributed by Walmart,
Inc. Using
the core resiliency test described above, the following data was collected. A
summary of the
results in provided below in Table 1.
CA 02729532 2011-01-26
17
TABLE 1
PRODUCT THICKNESS RELEASE (mm)
INVENTIVE PRODUCT 1- MODERATE 5.03
POISE MODERATE 14.83
OPTIONS MODERATE 12.97
TENA MODERATE REGULAR 8.97
[00811 As demonstrated by the results above, the thickness release of the
Inventive
Product 1 was significantly lower than the prior art absorbent products, such
as POISE
Moderate, OPTIONS Moderate and TENA Moderate Regular, demonstrating a
significant
improvement in product resiliency.
[00821 Similar comparative testing was performed on "HEAVY" type products to
confirm the increased core resiliency of the inventive absorbent articles
described herein. In
particular, thirty samples of a second inventive product ("Inventive Product 2-
Heavy") were
compared to various prior art absorbent articles. In particular, the Inventive
Product 2-
Heavy was compared to the POISE Maximum (manufactured by Kimberly-Clark), the
TENA Heavy Regular (manufactured by SCA Hygiene Products), and the OPTIONS
Maximum (manufactured by First Quality and distributed by Walmart, Inc.). All
of the
products tested have a Rothwell value of between about 400 g to 600 g. Using
the core
resiliency test described above, the following data was collected. A summary
of the results in
provided below in Table 2.
TABLE 2
PRODUCT THICKNESS RELEASE (mm)
INVENTIVE PRODUCT 2- HEAVY 7.13
CA 02729532 2011-01-26
18
POISE MAXIMUM 14.83
OPTIONS MAXIMUM 19.23
TENA HEAVY REGULAR 12.30
[0083] As demonstrated by the results above, the thickness release of the
Inventive
Product 2 was significantly lower than the prior art absorbent products, such
as POISE
Maximum, OPTIONS Maximum, and TENA Heavy Regular, demonstrating a
significant
improvement in product resiliency.
TUT Tumbling Test
[0084] A tumbling test is useful for assessing absorbent products with an
average
Rothwell value range of between about 260g to 800g. The equipment used is
described in the
ISO 12945-1 method, section 5.1. Such a pilling box is available through SDL
Atlas, located
in Rock Hill, South Carolina, model M227.
[0085] According to the method described therein, all of the internal surfaces
of the box
are lined with cork jointing material. Calibration and maintenance of pilling
box given in
Annex A of the ISO 12945-1 method should be followed. The pilling box is
rotated about a
horizontal axis passing through the centers of two opposites faces. Five
polyurethane
specimen tubes are used, which function to compress the absorbent article
during rotation.
The pilling test method according to ISO 12945-1 is a standardized test used
throughout the
textile industry.
[0086] In order to determine whether the absorbent products have maintained
their core
resiliency, a light box is used to assess cracks in the product. Preferably,
the light box should
be large enough to provide uniform illumination throughout the length and
width of the pad.
More preferably, the product should cover less than 40% of the total light
surface of the lamp.
Such a light box is available through a company called UVP located in Upland,
California-
Model TW-43.
CA 02729532 2011-01-26
19
[0087] Prior to administering the tumbling test according to features of the
present
invention, the specimens should be conditioned to room temperature of about
(21+/-2 C)
with a relative humidity of about (65+/-2%) for at least 24 hours. During the
preparation
stage, the absorbent articles should be removed from their bags and individual
wrappings.
Once the specimens are properly conditioned, release paper is removed from the
specimen (if
present) and baby powder is spread over the adhesive to remove its tackiness,
and to prevent
the specimen from sticking on itself during the compression period.
[0088] Before testing the absorbent articles, the absorbent articles should be
assessed. If
an absorbent article includes a crack, an unpurposeful partial split/break, or
is missing a
section of its absorbent core, the product should be rejected. In total, ten
absorbent articles
shall be tested per product variant. The absorbent articles should look
identical taking into
consideration minor process variations. If there is an obvious difference, the
outlier should
be rejected and replaced by another sample.
[0089] Once the absorbent articles are properly prepared, they are ready for
testing. The
first step is to determine the center of the product, and to mark it at its
center point, as shown
in FIG. 15. Like the core resiliency test described above, numerous products
should be tested
per product variant. These products should look identical taking into
consideration minor
process variation.
[0090] The products are placed on the light box prior to administering the
tumbling test.
Preferably, there should be a relatively uniform amount of light shinning
through the
absorbent core. However, it is not uncommon to find small darker areas of pulp
in the core.
These areas occur as a result of improper defiberization of the pulp in the
mill. These small
unfiberized clumps will not interfere with the test results. If there is an
obvious difference,
the outlier should be rejected and replaced by another sample.
CA 02729532 2011-01-26
100911 The product is placed on a light box with the user side facing the
light box's
surface for inspection. That is, the specimen should be placed on the light
table with the top
sheet facing down. The vertical distance between the camera and the light
table should be
about 300 mm, and the vertical distance between the technician doing the test
and the light
table should be about 400-800 mm. Because the analysis compares individual
products
before and after tumbling, process irregularities or design characteristics
should be taken into
consideration. For example, where a particular concentration exists prior to
tumbling, that
concentration should be negligible when considering whether there is a crack
or failure of the
product.
[00921 A picture of the sample product should be taken when it is on the light
box. After
the picture is taken, the sample product is dosed. With reference to FIG. 15,
the dosing
apparatus 100 is similar to the dosing apparatus 40 described above, and
includes a funnel
102 supported on a base support 104. The particular sample is dosed according
to its
Rothwell value. For example, for products with a Rothwell value of between
about 260 g to
399 g, 50m1 of 0.9% saline solution (21+/-2 C) is used, and for products
having an average
Rothwell value of between about 400 g to 800g, 75ml of 0.9% saline solution
(21+/-2 C) is
used.
[00931 Similar to the core resiliency test, liquid is dosed onto the absorbent
article at a
constant slow flow rate. The flow rate may be adjusted based on how slow or
fast the
product is absorbing the liquid. However, the liquid should not overflow the
circular base of
the dosing apparatus 100, and the liquid should all be absorbed by the
absorbent article in less
than 1 minute. Once all the liquid has been absorbed, the dosing apparatus 100
can be
removed from the absorbent product 2.
[00941 After the product is dosed, 10 minutes is allowed to lapse. The
untumbled, dosed
product should be place on the light box top sheet facing down and
photographed, prior to
CA 02729532 2011-01-26
21
tumbling. The sample is then placed into the pilling box chamber with five
polyurethane
tubes. For products that are longer than 235 mm, the products may be placed at
an angle or
folded onto themselves to fit within the box. The pilling box is set to rotate
for 1800 cycles,
for about 15-20 minutes. Once the equipment has stopped, the specimen is
gently removed
and placed on the light box for determining whether the sample has cracked or
been
damaged.
[00951 Core cracks or damage is defined as areas where the absorbent core
matrix has
ruptured due to the strain of the tumbling. As a result, the absorbent
material has severely
shifted creating areas of high and low density not caused by the absorption of
the test liquid.
100961 The tumbled sample is compared to the picture of the undosed sample to
determine if there is a crack by way of obvious differences in light shining
through the
product.
100971 A total of ten products should be tumbled and compared under the light
box. A
product fails the tumbling test when at least one sample blows out in the
pilling box, or if
three or more products have a crack. A product blow out is when the samples'
top sheet and
back sheet seal is ruptured so that the absorbent material is exposed.
[00981 With reference to FIGS. 16-23, photographs of samples with and without
cracks
are shown. The contrast and the brightness have been changed on all
photographs to enhance
the possibility to see the cracks. With reference to FIGS. 16-20, each of
these samples
represent prior art absorbent articles after being run in the pilling box,
each of the samples
exhibiting "cracks". FIG. 16 represents a prior art article having a printed
top sheet. As
shown in FIG. 16, large amounts of the absorbent material fluctuated to ends
of the products.
However, as observed during the testing, the shaded area in the middle of the
product
occurred due to the printed top sheet and not due to the presence of absorbent
material. This
CA 02729532 2011-01-26
22
observation is readily determined by the human eye, and not as easily
discernible from
photographs.
[0099] With reference to FIGS. 17 and 18 (representing prior art articles with
a printed
top sheet and white transfer layer), large amounts of the absorbent material
fluctuated to ends
of the products. As observed during the testing, the shaded area in the middle
of the product
occurred due to the printed top sheet and white highloft present, and not due
to the presence
of absorbent material.
[00100] With reference to FIG. 19 (representing prior art article with a white
top sheet and
white transfer layer), large amounts of the absorbent material fluctuated to
ends of the
products. As observed during the testing, the shaded area in the middle of the
product
occurred due to the colored transfer layer and not due to the presence of
absorbent material.
[00101] With reference to FIG. 20 (representing prior art article with a white
top sheet and
colored transfer layer, large amounts of the absorbent material fluctuated to
ends of the
products. However, as observed during the testing, the shaded area observed
occurred due to
the colored transfer layer and not due to the presence of absorbent material.
[00102] With reference to FIGS. 21-23, the inventive products of the present
invention are
illustrated. In particular, each of the three products shown in FIGS. 21-23
demonstrated no
cracks after being run in the pilling box. However, with reference to FIGS. 22-
23, the
products shown therein, which are modified to maximize the contrast and has
purposeful
perforations, have no rupture of the absorbent core matrix, only minor
migration of the
absorbent material. In particular, there is no defined area where no absorbent
material is
present so as to impede the wicking of liquid from one end point to another.
Accordingly, the
product shown in FIGS. 22-23 would be determined to have "no cracks".
[00103] Although photographs have been taken to help demonstrate the presence
or
absence of cracks, it should be understood that the human eye with normal eye
sight and
CA 02729532 2011-01-26
23
human perception is the best tool to evaluate if there is a crack or not. The
determination of a
crack or no crack is made by looking at the physical products, and not at
photographs. As
such, depth perception plays a part in discerning whether there is a crack or
not. To further
distinguish cracks, a weak colorant may be added to the testing saline
solution.
[001041 Tests were performed by Specialized Technology Resources, Inc. located
in
Enfield, Connecticut. Tests were performed on the Inventive Product 1-
Moderate and the
Inventive Product I- Heavy, described above. With regard to the Inventive
Product 2-
Heavy, all ten products tested were found to have no cracks. With regard to
the Inventive
Product 1- Moderate, all but one of the ten products were found to have no
cracks. Only one
product was found to have a single crack. The Inventive Product 1- Moderate
and the
Inventive Product 2- Heavy were the only products to pass the tumbling test
described herein.
This is due in part to the use of an airlaid absorbent core having a network
of bicomponent
fibers in the outer layers.
[001051 The tumbling test as described in the present invention was also
performed on the
TENA Moderate, TENA Heavy, POISE Moderate, POISE Maximum, and OPTIONS
Maximum and OPTIONS Moderate. For TENA Moderate, the first two products
tested
had a single crack and the third sample tested blew out. The testing was
stopped due to the
product failure. For the TENA Heavy, every specimen tested had either one or
two cracks.
For POISE Moderate, two products had one crack, seven products had two cracks
and one
product had no cracks. For POISE Maximum, three specimens had one crack, five
specimens had two cracks, one specimen had three cracks, and one specimen had
no cracks.
For the OPTIONS Maximum, the first two specimens tested had one crack and a
slight
blowout. The second two specimens tested had one crack and a big blowout. The
testing
was then stopped due to the product failure. For the OPTIONS Moderate, six of
the products
had a single crack, three of the products had two cracks, and one product blew
out. Each of
CA 02729532 2011-01-26
24
these prior art absorbent articles had three or more products present with
cracks, thereby
failing the tumbling test.
[001061 The core resiliency test and tumbling test confirm that the absorbent
article
described herein have superior qualities when compared to prior art absorbent
articles. This
is due in part to the particular make up of the absorbent core. The various
layers and
materials create a complex shape retention network. As such, an improved
liquid handling
structure is created that distributes liquid evenly while maintaining its
shape/thinness.
Further, the even distribution of the liquid handling and addition of
bicomponent fibers can
result in a product that better withstands stress forces.
[001071 Although the present invention has been described in connection with
preferred
embodiments thereof, it will be appreciated by those skilled in the art that
additions,
deletions, modifications, and substitutions not specifically described may be
made without
department from the spirit and scope of the invention as defined in the
appended claims.
