U.S. patent application number 10/037438 was filed with the patent office on 2003-07-17 for method of forming composite absorbent members.
This patent application is currently assigned to Kimberly-Clark Worldwide, Inc.. Invention is credited to Ceman, Glory Framary, Falls, Maureen M., Krautkramer, Patsy A., Makolin, Robert John, Reeves, Willaim, Woltman, Garry Ronald.
Application Number | 20030131457 10/037438 |
Document ID | / |
Family ID | 21894336 |
Filed Date | 2003-07-17 |
United States Patent
Application |
20030131457 |
Kind Code |
A1 |
Krautkramer, Patsy A. ; et
al. |
July 17, 2003 |
Method of forming composite absorbent members
Abstract
A method for forming a composite absorbent member is provided
that includes: a) extruding a first fibrous component through a
first meltblowing die and intermingling pulp fibers with the first
fibrous component to form a first admixture; b) extruding a second
fibrous component through a second meltblowing die and
intermingling pulp fibers with the second fibrous component to form
a second admixture; and c) codepositing the first and second
admixtures on a collecting surface so as to form a composite
structure having a first layer and a second layer. The second layer
has a higher weight percentage of pulp fibers than the first layer,
and the average diameter of the pores within the second layer is
smaller than the average diameter of the pores within the first
layer.
Inventors: |
Krautkramer, Patsy A.;
(Omro, WI) ; Falls, Maureen M.; (Neenah, WI)
; Makolin, Robert John; (Neenah, WI) ; Ceman,
Glory Framary; (Appleton, WI) ; Reeves, Willaim;
(Appleton, WI) ; Woltman, Garry Ronald;
(Greenville, WI) |
Correspondence
Address: |
DORITY & MANNING, P.A.
POST OFFICE BOX 1449
GREENVILLE
SC
29602-1449
US
|
Assignee: |
Kimberly-Clark Worldwide,
Inc.
|
Family ID: |
21894336 |
Appl. No.: |
10/037438 |
Filed: |
December 21, 2001 |
Current U.S.
Class: |
28/153 ;
28/158 |
Current CPC
Class: |
A61F 13/534 20130101;
A61F 2013/15504 20130101 |
Class at
Publication: |
28/153 ;
28/158 |
International
Class: |
D06G 001/00 |
Claims
What is claimed is:
1. A method of forming a composite absorbent member, said method
comprising: a) extruding a first fibrous component through a first
meltblowing die and intermingling pulp fibers with said first
fibrous component to form a first admixture; b) extruding a second
fibrous component through a second meltblowing die and
intermingling pulp fibers with said second fibrous component to
form a second admixture, wherein said second admixture contains a
higher weight percentage of pulp fibers than said first admixture;
and c) codepositing said first and second admixtures on a
collecting surface so as to form a composite structure having a
first layer and a second layer, wherein said second layer has a
higher weight percentage of pulp fibers than said first layer, and
wherein the average diameter of the pores within said second layer
is smaller than the average diameter of the pores within said first
layer.
2. A method as defined in claim 1, wherein the weight percentage of
pulp fibers within said second layer is at least about 10% greater
than the weight percentage of pulp fibers present within said first
layer.
3. A method as defined in claim 1, wherein the weight percentage of
pulp fibers within said second layer is at least about 25% greater
than the weight percentage of pulp fibers present within said first
layer.
4. A method as defined in claim 1, wherein the average pore size
within said second layer is at least about 10% smaller than the
average pore size within said first layer.
5. A method as defined in claim 1, wherein the average pore size
within said second layer is at least about 25% smaller than the
average pore size within said first layer.
6. A method as defined in claim 1, wherein the average pore size
within said second layer is at least about 50% smaller than the
average pore size within said first layer.
7. A method as defined in claim 1, wherein the composite absorbent
member has an Edge Compression value of greater than about 100
grams.
8. A method as defined in claim 1, wherein the composite absorbent
member has an Edge Compression value of between about 150 grams to
about 800 grams.
9. A method as defined in claim 1, wherein the composite absorbent
member has an Edge Compression value of between about 300 grams to
about 600 grams
10. A method as defined in claim 1, wherein the basis weight of
said composite absorbent member is from about 150 grams per square
meter to about 250 grams per square meter.
11. A method as defined in claim 1, wherein the basis weight of
said composite absorbent member is from about 150 grams per square
meter to about 200 grams per square meter.
12. A method of forming an absorbent article, said method
comprising: a) forming an absorbent member by a method that
includes: i) extruding a first fibrous component through a first
meltblowing die and intermingling pulp fibers with said first
fibrous component to form a first admixture; ii) extruding a second
fibrous component through a second meltblowing die and
intermingling pulp fibers with said second fibrous component to
form a second admixture, wherein said second admixture contains a
higher weight percentage of pulp fibers than said first admixture;
and iii) codepositing said first and second admixtures on a
collecting surface so as to form a composite structure having first
and second layers, wherein the weight percentage of pulp fibers in
said second layer is at least about 10% greater than the weight
percentage of pulp fibers within said first layer, and wherein the
average diameter of the pores within said second layer is smaller
than the average diameter of the pores within said first layer; and
b) positioning said absorbent member between a liquid-permeable
cover and a liquid-impermeable baffle.
13. A method as defined in claim 12, wherein the weight percentage
of pulp fibers within said second layer is at least about 25%
greater than the weight percentage of pulp fibers present within
said first layer.
14. A method as defined in claim 12, wherein the average pore size
within said second layer is at least about 25% smaller than the
average pore size within said first layer.
15. A method as defined in claim 12, wherein the average pore size
within said second layer is at least about 50% smaller than the
average pore size within said first layer.
16. A method as defined in claim 12, wherein the composite
absorbent member has an Edge Compression value of greater than
about 100 grams.
17. A method as defined in claim 12, wherein the composite
absorbent member has an Edge Compression value of between about 150
grams to about 800 grams.
18. A method as defined in claim 12, further comprising positioning
an intake member adjacent to said liquid-permeable cover.
19. A method as defined in claim 18, further comprising positioning
a transfer delay member adjacent to said intake member.
20. A method as defined in claim 19, wherein said composite
absorbent member is positioned between said transfer delay member
and said liquid-impermeable baffle.
21. A method as defined in claim 12, wherein the absorbent article
has a caliper less than about 15 millimeters.
22. A method as defined in claim 12, wherein the absorbent article
has a caliper less than about 5 millimeters.
23. A method of forming a composite absorbent member, said method
comprising: a) extruding a first fibrous component through a first
meltblowing die and intermingling pulp fibers with said first
fibrous component to form a first admixture; b) extruding a second
fibrous component through a second meltblowing die and
intermingling pulp fibers with said second fibrous component to
form a second admixture; c) extruding a third fibrous component
through a third meltblowing die and intermingling pulp fibers with
said third fibrous component to form a third admixture, wherein
said second admixture contains a higher weight percentage of pulp
fibers than said first admixture and a higher weight percentage of
pulp fiber than said third admixture; and d) codepositing said
first, second, and third admixtures on a collecting surface so as
to form a composite structure having a lower outer layer, an inner
layer, and an upper outer layer, wherein the weight percentage of
pulp fibers within said inner layer is at least about 10% greater
than the weight percentage of pulp fibers within said lower outer
layer and said upper outer layer, and wherein the average diameter
of the pores within said inner layer is smaller than the average
diameter of the pores within said lower outer layer and said upper
outer layer.
24. A method as defined in claim 23, wherein the weight percentage
of pulp fibers within said inner layer is at least about 25%
greater than the weight percentage of pulp fibers present within
said lower outer layer and said upper outer layer.
25. A method as defined in claim 23, wherein the average pore size
within said inner layer is at least about 10% smaller than the
average pore size within said first outer layer and said second
outer layer.
26. A method as defined in claim 23, wherein the average pore size
within said inner layer is at least about 25% smaller than the
average pore size within said first outer layer and said second
outer layer.
27. A method as defined in claim 23, wherein the average pore size
within said inner layer is at least about 50% smaller than the
average pore size within said first outer layer and said second
outer layer.
Description
BACKGROUND OF THE INVENTION
[0001] Absorbent articles (e.g., incontinent devices; sanitary
napkins, also referred to as catamenial or feminine pads;
pantiliners; pantishields; and the like) are devices often used by
a female to absorb the flow of body fluids, such as menses, blood,
urine, and other excrements. For instance, absorbent articles
sometimes include a liquid-permeable cover, an absorbent core, and
a liquid-impermeable baffle. The absorbent core typically contains
an airlaid cellulosic tissue disposed adjacent to the baffle that
acts as a pad-shaping layer.
[0002] However, one problem with many conventional absorbent
articles is that they tend to twist and bunch when worn. For
instance, as a woman moves, many conventional absorbent articles
squeeze between the thighs and result in deformation of the
article, thereby causing the upper surface of the article to
acquire a curved or convex shape. This twisting and bunching is
often referred to as "roping" because a cylindrical profile is
imparted to the absorbent article. Roping can cause the absorbent
article to absorb less body fluid that contacts its upper surface.
Specifically, the fluid discharged from the vagina often runs off
the "roped" absorbent article before it can be absorbed, thereby
leaking onto the undergarment. This is undesired because it causes
discomfort and reduces absorbency.
[0003] As such, a need currently exists for an improved absorbent
article that can resist bunching and twisting.
SUMMARY OF THE INVENTION
[0004] In accordance with one embodiment of the present invention,
a method for forming a composite absorbent member is disclosed that
comprises forming an absorbent member by a method that
includes:
[0005] a) extruding a first fibrous component through a first
meltblowing die and intermingling pulp fibers with the first
fibrous component to form a first admixture;
[0006] b) extruding a second fibrous component through a second
meltblowing die and intermingling pulp fibers with the second
fibrous component to form a second admixture; and
[0007] c) codepositing the first and second admixtures on a
collecting surface so as to form a composite structure having a
first layer and a second layer. The second layer has a higher
weight percentage of pulp fibers than the first layer, and the
average diameter of the pores within the second layer is smaller
than the average diameter of the pores within the first layer.
[0008] In some embodiments, the amount of pulp fibers present
within the second layer is at least about 10% by weight greater,
and in some embodiments, 25% by weight greater than the amount of
pulp fibers present within the first layer. Moreover, the average
pore size within the second layer can be at least about 10%
smaller, in some embodiments at least about 25% smaller, and in
some embodiments, at least about 50% smaller than the average pore
size in the first layer. The basis weight of the absorbent member
can also vary, such as between about 50 grams per square meter to
about 350 grams per square meter, in some embodiments between about
150 grams per square meter to about 250 grams per square meter, and
in some embodiments, between about 150 grams per square meter to
about 200 grams per square meter. Moreover, in some embodiments,
the composite absorbent member can have an Edge Compression value
of greater than about 100 grams, in some embodiments between about
150 grams to about 800 grams, and in some embodiments, between
about 300 grams to about 600 grams.
[0009] In accordance with another embodiment of the present
invention, an absorbent article (e.g., incontinent device, sanitary
napkin, pantiliner, pantishield, etc.) is disclosed that includes
positioning a composite absorbent member between a liquid-permeable
cover and a liquid-impermeable baffle. If desired, the absorbent
member may be incorporated into an absorbent core that also
contains an intake member and/or a transfer delay member. For
instance, in one embodiment, the intake member may be positioned
adjacent to the liquid-permeable cover and the transfer delay
member may be positioned adjacent to the intake member. In such
embodiments, the absorbent member may, if desired, be positioned
between the transfer delay member and the liquid-impermeable
baffle.
[0010] Other features and aspects of the present invention are
discussed in greater detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A full and enabling disclosure of the present invention,
including the best mode thereof, directed to one of ordinary skill
in the art, is set forth more particularly in the remainder of the
specification, which makes reference to the appended figures in
which:
[0012] FIG. 1 illustrates a cross-section of one embodiment of a
composite absorbent member of the present invention;
[0013] FIG. 2 illustrates one embodiment of a method for forming a
composite absorbent member for use in the present invention;
[0014] FIG. 3 illustrates a cross-section of a composite absorbent
member formed according to one embodiment of the present invention;
and
[0015] FIG. 4 illustrates a perspective view of an absorbent
article formed according to one embodiment of the present
invention.
[0016] Repeat use of reference characters in the present
specification and drawings is intended to represent same or
analogous features or elements of the invention.
DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS
[0017] Reference now will be made in detail to various embodiments
of the invention, one or more examples of which are set forth
below. Each example is provided by way of explanation of the
invention, not limitation of the invention. In fact, it will be
apparent to those skilled in the art that various modifications and
variations can be made in the present invention without departing
from the scope or spirit of the invention. For instance, features
illustrated or described as part of one embodiment, can be used on
another embodiment to yield a still further embodiment. Thus, it is
intended that the present invention covers such modifications and
variations as come within the scope of the appended claims and
their equivalents.
[0018] In general, the present invention is directed to a method of
forming a composite absorbent member that can be used in or as an
absorbent article, such as an incontinent device, sanitary napkin,
etc. The composite absorbent member has a controlled pore size
distribution within one or more layers to improve the fluid intake
rate of the absorbent member and inhibit rewetting. In addition,
the composite absorbent member can also be relatively resistant to
twisting and bunching. In one embodiment, for example, the
composite absorbent member is a coform material formed from three
or more layers.
[0019] Referring to FIG. 1., for example, one embodiment of a
composite absorbent member formed according to the present
invention is illustrated. In this embodiment, the absorbent member
22 contains two outer layers 70 and 72 and in inner layer 74 that
form a unitary, composite structure. It should be understood,
however, that the composite absorbent member 22 can contain any
number of layers desired. For example, in one embodiment, the
absorbent member 22 can contain four layers. In the illustrated
embodiment, each layer contains a mixture of pulp fibers and a
synthetic polymer. Typically, it is desired that the outer layers
70 and 72 contain a lesser amount of pulp fibers than the inner
layer 74 such that the outer layers 70 and 72 are more hydrophobic
than the inner layer 74. Thus, for example, the layer 74 can
contain between about 10% to about 90%, in some embodiments from
about 20% to about 80%, and in some embodiments, from about 30% to
about 70% by weight thermoplastic polymeric fibers. Likewise, the
layers 70 and 72 can contain between about 90% to about 10%, in
some embodiments between about 80% to about 20%, and in some
embodiments, between about 70% to about 30% by weight pulp
fibers.
[0020] To form a composite material having such a fiber content,
any of a variety of processes may be utilized. For instance, in one
embodiment, a multi-bank airlaying process may be used. In another
embodiment, a "coform" process may be utilized. As used herein, the
term "coform" generally refers to continuous melt-spun fibers
(e.g., meltblown or spunbond fibers) intermixed with an absorbent
material. For example, the melt-spun fibers can be intermixed with
staple length fibers, such as described in U.S. Pat. No. 4,118,531;
4,100,324 and 4,655,757. Further the melt-spun fibers, in some
instances, may be intermixed with superabsorbent particulates, such
as described in U.S. Pat. No. 3,971,373. Such superabsorbent
materials may be used in combination with the microfibers and
staple fibers or in lieu of the staple fibers.
[0021] Any of a variety of synthetic polymers may be utilized as
the melt-spun component of the coform material. For instance, in
some embodiments, thermoplastic polymers can be utilized. Some
examples of suitable thermoplastics that can be utilized include
polyolefins, such as polyethylene, polypropylene, polybutylene and
the like; polyamides; and polyesters. In one embodiment, the
thermoplastic polymer is polypropylene. Moreover, some suitable
absorbent materials that can be used in the coform material include
staple fibers, such as polyester, rayon, cotton, pulp fibers, and
the like. Pulp fibers are generally obtained from natural sources
such as woody and non-woody plants. Woody plants include, for
example, deciduous and coniferous trees. Non-woody plants include,
for example, cotton, flax, esparto grass, milkweed, straw, jute,
and bagasse. In addition, synthetic wood pulp fibers are also
available and may be used with the present invention. Wood pulp
fibers typically have lengths of about 0.5 to about 10 micrometers
and a length-to-maximum width ratio of about {fraction (10/1)} to
about {fraction (400/1)}. A typical cross-section has an irregular
width of about 30 micrometers and a thickness of about 5
micrometers.
[0022] For example, referring to FIG. 2, one embodiment for forming
a composite coform material with a differential pulp fiber content
is illustrated. As shown, a forming apparatus 110 is composed of
three meltblown units 120, 121, and 230, and a movable foraminous
belt apparatus 123, such as a wire belt. The meltblown apparatus
120 is composed of a die head 122 through which air streams 124 and
126 pass. A supply device 128 delivers a polymer to an extruder 130
for delivery to the die head 122. The polymer leaves the extruder
head 122 and is combined with a primary air stream 132, where the
fine polymer streams leaving the die head 122 are attenuated by the
converging flows of high velocity heated gas (usually air) supplied
through nozzles 124 and 126 to break the polymer streams into
discontinuous microfibers of small diameter. The die head 122
typically includes at least one straight row of extrusion
apertures.
[0023] In general, the resulting microfibers have an average fiber
diameter of up to about 10 microns. The average diameter of the
microfibers is usually greater than about 1 micron and within the
range of about 2 to about 6 microns, often averaging about 5
microns. While the microfibers are predominantly discontinuous,
they generally have a length exceeding that normally associated
with pulp fibers.
[0024] The primary gas stream 132 is merged with a secondary gas
stream 140 containing individualized pulp fibers so as to integrate
the two different fibrous materials in a single step. The
individualized wood pulp fibers typically have a length of about
0.5 to about 10 micrometers and a length to maximum width ratio of
about 10:1 to about 400:1. A typical cross-section has an irregular
width of about 10 microns and a thickness of about 5 microns. In
the illustrated arrangement, the secondary gas stream 140 is formed
by a pulp sheet divellicating apparatus, such as described in U.S.
Pat. No. 3,793,678 to Appel. This apparatus contains a conventional
picker roll 142 having picking teeth for divellicating pulp sheets
144 into individual fibers. The pulp sheets 144 are fed radially
along a picker roll radius to the picker roll 142. It is the teeth
of the picker roll 142 that allocate the pulp sheets 144 into
individual fibers, the resulting separated fibers are conveyed
toward the primary air stream 132 through a nozzle or duct 148. A
housing 150 covers the picker roll 142. A passageway 152 provides
process air to the picker roll in sufficient quantity to provide a
medium for conveying the fibers through the forming duct 148 at a
velocity approaching that of the picker teeth. The air may be
supplied by conventional device, e.g., a blower not shown.
Typically, the individual fibers should be conveyed through the
duct 148 at substantially the same velocity at which they leave the
picker teeth after separation from the pulp sheets 144.
[0025] The air stream 132 having pulp fibers from the stream 148
incorporated therein is then placed onto a moving belt 220 that
passes beneath the forming die 122 as the microfibers and air
stream are directed downwardly. The foraminous belt 160 is provided
with suction boxes 162, 164, and 226 driven by blowers that
withdraw air from beneath the foraminous belt 220 and provide for
uniform laydown of the fibers onto the belt. Two rolls 222 and 224
support the belt 220. While illustrated with three suction devices,
the number and size of the suction devices below the belt may be
varied.
[0026] As illustrated, the meltblowing device 120 lays down a layer
of meltblown polymer fibers having pulp fibers entangled therein as
layer 72. This passes beneath a second meltblowing device 121 where
a second layer 74 is placed thereon and joined to the layer 72.
[0027] The layer 74 is formed by the device 121 that is composed of
an extruder 174 fed by a material supply device 177. The extruder
174 feeds to a die head 176 that is generally similar to the die
head 122, having high velocity air nozzles for supplying air to the
extrusion stream 182. As the air streams from the nozzles 178 and
180 merge into the stream 182 and entrain the extruded fibers, they
are meltblown into microfibers and mixed with a stream of wood
fibers 184, exiting through the nozzle 186 from the picker device
188. In the picker device 188, the picker roll 190 rotates and
divellicates pulp sheets 192 as they are unrolled from a supply
roll 194. The pulp sheets are divellicated and passed through the
nozzle 186 to join the meltblown stream 182. Process air is
supplied through the duct 198 of the picker roll housing 188.
[0028] As illustrated, the meltblowing device 121 lays down a layer
of meltblown polymer fibers having pulp fibers entangled therein as
layer 74. This passes beneath a third meltblowing device 230 where
a third layer 70 is placed thereon and joined to the layer 74.
[0029] The layer 70 is formed by the device 230 that is composed of
an extruder 232 fed by a material supply device 234. The extruder
232 feeds to a die head 236 that is generally similar to the die
heads 122 and 176, having high velocity air nozzles for supplying
air to the extrusion stream 260. As the air streams from the
nozzles 240 and 238 merge into the stream 260 and entrain the
extruded fibers, they are meltblown into microfibers and mixed with
a stream of wood fibers 242, exiting through the nozzle 258 from
the picker device 244. In the picker device 244, the picker roll
246 rotates and divellicates pulp sheets 250 as they are unrolled
from a supply roll 252. The pulp sheets are divellicated and passed
through the nozzle 258 to join the meltblown stream 260. Process
air is supplied through the duct 248 of the picker roll housing
244. After leaving the support roller 224, the composite structure
of layers 70, 72, and 74 may be further processed by known devices,
such as cutters and stackers.
[0030] When laid down, the fibers of the layer 74 becomes somewhat
entangled with fibers on the surface of the layer 72 and the fibers
of the layer 70 become somewhat entangled with fibers on the
surface of the layer 74 such that a composite structure is formed.
For instance, referring to FIG. 1, one embodiment of a
three-layered composite absorbent member is depicted. As shown, the
layers 70, 72, and 74 are each composed of an entangled structure
of pulp fibers and meltblown polymer fibers that are joined at
areas 75. In addition to containing three layers, it should also be
understood that the composite material may also contain other
layers as well. For example, in one embodiment, a five-layered
composite material can be formed in a manner similar to that
described above and shown in FIG. 2, except that two additional
meltblown units would be utilized. Various methods for forming such
composite coform materials are described in U.S. Pat. No. 4,655,757
to McFarland, et al., which is incorporated herein in its entirety
by reference thereto for all purposes.
[0031] By containing such a differential fiber content in each of
the layers, such as described above, the composite absorbent member
of the present invention can possess a variety of different
beneficial properties. For example, as discussed above, the outer
layers 70 and 72 can each contain a lesser amount of pulp fibers
than the inner layer 74 such that the outer layers 70 and 72 are
relatively hydrophobic and the inner layer 74 is relatively
hydrophilic. Moreover, by varying the fiber content in each layer,
the pore size distribution of the layers can also be readily
controlled. Specifically, layers having a relatively large amount
of pulp fibers tend to have smaller pore sizes. Although not
limited in theory, it is believed that this is the result of a
greater level of hydrogen bonding within a layer containing more
pulp fibers, thus causing the fibers to be located closer in
proximity to each other so that smaller pores are formed. On the
other hand, layers having less pulp fibers tend to display less
hydrogen bonding, thereby causing larger pores to be formed.
[0032] Referring to FIG. 3, for example, the outer layers 70 and 72
can have pores 81 that are relatively large in diameter, while the
layer 74 can have pores 83 that are relatively small in diameter.
In some embodiments, the average pore size within the inner layer
74 is at least about 10% smaller, in some embodiments at least
about 25% smaller, and in some embodiments, at least about 50%
smaller than the average pore size in the outer layers 70 and 72.
Due to the presence of such larger pores, the layer 70 can receive
fluids at a relatively fast rate. Moreover, as a result of the
hydrophobic nature of the layer 70 and the hydrophilic nature of
the layer 74, fluids also tend to flow quickly through the layer 70
and into the inner layer 74. Once present within the inner layer
74, the fluids are absorbed by the hydrophilic pulp fibers. In
addition, because fluids do not tend to flow in a direction from
smaller pores to larger pores, the fluid absorbed within the inner
layer 74 does not readily flow into the outer layer 72 or back into
the layer 70, which each have pores that are relatively larger in
diameter than the pores of the inner layer 74. This allows the
fluid to remain absorbed in the inner layer 74, inhibiting
rewetting of the outer surfaces.
[0033] To achieve a pore size distribution, such as described
above, it is typically desired that each layer of the composite
absorbent member have a different pore size distribution than an
adjacent layer. In this manner, the composite absorbent member can
possess properties that differ from layer to layer. For example, in
one embodiment of a three-layered absorbent member, such as shown
in FIG. 1, the inner layer 74 typically contains pulp fibers in an
amount of at least about 10% by weight greater than adjacent layers
70 and 72, and in some embodiments, at least about 25% by weight
greater than adjacent layers 70 and 72. As discussed above, by
containing a greater amount of pulp fibers, the inner layer 74 is
able to form smaller pores than the outer layers 70 and 72.
[0034] Moreover, the outer layers 70 and/or 72 can also contain a
certain content of the thermoplastic polymer such that the
resulting absorbent article can possess greater strength and
stiffness to inhibit bunching and twisting of the article. For
example, the Edge-wise Compression (EC) value generally reflects
the stiffness of a dry absorbent material. Accordingly, the
Edge-wise Compression value can also reflect the ability of the
absorbent article to resist twisting and bunching when positioned
between the legs of the wearer, and can provide a good indication
of desired comfort and fit.
[0035] The method by which the Edge-wise Compression (EC) value can
be determined is as follows. A piece of the absorbent material
(e.g., 2".times.12" or 1".times.10") is cut with its longer
dimension aligned with the longitudinal direction of the product or
raw material web. The weight of the sample is determined. The
thickness of the material is determined under a 0.2 psi load. The
material is formed into a cylinder having a height of 2 inches and,
with the two ends having 0 to about 0.125 inch overlap, the
material is stapled together with three staples. One staple is near
the middle of the width of the product and the other two nearer
each edge of the width of the material. The longest dimension of
the staple is in the circumference of the formed cylinder to
minimize the effect of the staples on the testing.
[0036] An "Instron" tensile tester, or other similar instrument, is
configured with a bottom platform, a platen larger than the
circumference of the sample to be tested and parallel to the bottom
platform, attached to a compression load cell placed in the
inverted position. The specimen is placed on the platform, under
the platen. The platen is brought into contact with the specimen
and compresses the sample at a rate of 25 mm/min. The maximum force
obtained in compressing the sample to 50% of its width (1 inch) is
recorded. If the material buckles, it is typical for the maximum
force to be reached before the sample is compressed to 50%.
[0037] If the sample has a length smaller than 12 inches (e.g.,
1".times.10"), certain modifications may be needed. For instance,
The Handbook Of Physical And Mechanical Testing Of Paper And
Paperboard, Richard E. Mark editor, Dekker 1983, (Vol. 1) provides
a detailed discussion of the edge-wise compression strength. Based
on theoretical models governing buckling stresses, in the Edge-wise
Compression configuration described, the buckling stress is
proportional to E*t.sup.2/(H.sup.2) with the proportionality
constant being a function of H.sup.2/(R*t) where E is the Elastic
modulus, H is the height of the cylinder, R is the radius of the
cylinder, and t is the thickness of the material. Expressing the
stress in terms of force per basis weight, it can be shown that the
parameter that needs to be maintained as a constant is H.sup.2/R.
Therefore, for a sample that is smaller than 12 inches, the largest
possible circle should be constructed and its height (width of the
sample being cut out) adjusted such that H.sup.2/R equals 2.1
inches. A description of the method for determining
Edge-Compression values may also be found in U.S. Pat. No.
6,323,388 to Melius, et al.
[0038] In general, the absorbent member 22 has an Edge-Wise
Compression (EC) value of at least about 100 grams, in some
embodiments between about 150 to about 800 grams, and in some
embodiments, between about 300 to about 600 grams. By forming the
absorbent member 22 to achieve such an Edge-Wise Compression value,
the resulting absorbent article 10 can be flexible enough to
provide comfort to a user, yet stiff enough to resist bunching and
twisting. The basis weight of the composite absorbent member 22 can
also vary, such as from about 50 to about 350 grams per square
meters (gsm), in some embodiments from about 150 to about 250 gsm,
and in some embodiments, from about 150 to about 200 gsm.
[0039] The beneficial properties of the composite member of the
present invention can generally be utilized in a wide variety of
applications. For instance, referring to FIG. 4, the composite
absorbent member 22 can be utilized in an absorbent article 10. For
purposes of description only, the absorbent article 10 is
illustrated as a sanitary napkin for feminine hygiene having
generally a racetrack shape. However, it can be a pantiliner,
pantishield, or any other disposable absorbent article that is well
known in the art, and can include other shapes, such as oval,
hourglass, straight sided, wrapped and peripheral sealed
constructions. It should also be noted that absorbent articles come
in various sizes and shapes and vary in thickness. For example, in
some embodiments, the absorbent article 10 is between about 150 mm
to about 320 mm long, and between about 60 mm to about 120 mm wide
and has a racetrack shape with rounded ends. Moreover, in some
embodiments, the absorbent article has a thickness or caliper of
less than about 20 millimeters. For example, when formed as a
sanitary napkin, the absorbent article typically has a caliper of
less than about 15 millimeters, in some embodiments less than about
5 millimeters, and in some embodiments, less than about 4
millimeters.
[0040] In the illustrated embodiment, the absorbent article 10
includes a cover 12, a baffle 14, and an absorbent core 16. The
absorbent core 16 is positioned inward from the outer periphery of
the absorbent article 10 and includes a body-facing surface
positioned adjacent the cover 12 and a garment-facing surface
positioned adjacent the baffle 14.
[0041] The cover 12 is generally designed to contact the body of
the user and is liquid-permeable. The cover 12 can surround the
absorbent core 16 so that it completely encases the absorbent
article 10. Alternatively, the cover 12 and the baffle 14 can
extend beyond the absorbent core 16 and be peripherally joined
together, either entirely or partially, using known techniques.
Typically, the cover 12 and the baffle 14 are joined by adhesive
bonding, ultrasonic bonding, or any other suitable joining method
known in the art.
[0042] The liquid-permeable cover 12 is sanitary, clean in
appearance, and somewhat opaque to hide bodily discharges collected
in and absorbed by the absorbent core 16. The cover 12 further
exhibits good strike-through and rewet characteristics permitting
bodily discharges to rapidly penetrate through the cover 12 to the
absorbent core 16, but not allow the body fluid to flow back
through the cover 12 to the skin of the wearer. For example, some
suitable materials that can be used for the cover 12 include
nonwoven materials, perforated thermoplastic films, or combinations
thereof. A nonwoven fabric made from polyester, polyethylene,
polypropylene, bicomponent, nylon, rayon, or like fibers may be
utilized. For instance, a white uniform spunbond material is
particularly desirable because the color exhibits good masking
properties to hide menses that has passed through it. For instance,
U.S. Pat. No. 4,801,494 to Datta, et al. and U.S. Pat. No.
4,908,026 to Sukiennik. et al. teach various cover materials that
can be used in the present invention.
[0043] If desired, the cover 12 may also be sprayed with a
surfactant to enhance liquid penetration to the absorbent core 16.
The surfactant is typically non-ionic and should be non-irritating
to the skin.
[0044] The cover 12 can also contain a plurality of apertures (not
shown) formed therethrough to permit body fluid to pass more
readily into the absorbent core 16. The apertures can be randomly
or uniformly arranged throughout the cover 12, or they can be
located only in the narrow longitudinal band or strip arranged
along the longitudinal axis X-X of the absorbent article 10. The
apertures permit rapid penetration of body fluid down into the
absorbent core 16. The size, shape, diameter any number of
apertures can be varied to suit one's particular needs.
[0045] As stated above, the absorbent article also includes a
baffle 14. The baffle 14 is generally liquid-impermeable and
designed to face the inner surface, i.e., the crotch portion of an
undergarment (not shown). The baffle 14 can permit a passage of air
or vapor out of the absorbent article 10, while still blocking the
passage of liquids. Any liquid-impermeable material can generally
be utilized to form the baffle 14. For example, one suitable
material that can be utilized is a microembossed polymeric film,
such as polyethylene or polypropylene. In particular embodiments, a
polyethylene film is utilized that has a thickness in the range of
about 0.2 mils to about 5.0 mils, and particularly between about
0.5 to about 3.0 mils.
[0046] As indicated above, the absorbent article 10 also contains
an absorbent core 16 positioned between the cover 12 and the baffle
14. In the illustrated embodiment, for example, the absorbent core
16 contains three separate and distinct absorbent members 18, 20
and 22. It should be understood, however, that any number of
absorbent members can be utilized in the present invention. For
example, in one embodiment, only the absorbent member 22 may be
utilized.
[0047] As shown, the first absorbent member 18, or intake member,
is positioned between the cover 12 and the second absorbent member
20, or transfer delay member. The intake member 18 represents a
significant absorbing portion of the absorbent article 10 and has
the capability of absorbing at least about 80%, particularly about
90%, and more particularly about 95% of the body fluid deposited
onto the absorbent article 10. In terms of amount of body fluid,
the intake member 18 can absorb at least about 20 grams,
particularly about 25 grams, and more particularly, about 30 or
more grams of body fluid.
[0048] The intake member 18 can generally have any shape and/or
size desired. For example, in one embodiment, the intake member 18
has a rectangular shape, with a length equal to or less than the
overall length of the absorbent article 10, and a width less than
the width of the absorbent article 10. For example, a length of
between about 150 mm to about 300 mm and a width of between about
10 mm to about 40 mm can be utilized.
[0049] Typically, the intake member 18 is made of a material that
is capable of rapidly transferring, in the z-direction, body fluid
that is delivered to the cover 12. Because the intake member 18 is
generally of a dimension narrower than the absorbent article 10,
the sides of the intake member 18 are spaced away from the
longitudinal sides of the absorbent article 10 and the body fluid
is restricted to the area within the periphery of the intake member
18 before it passes down and is absorbed into the transfer delay
member 20. This design enables the body fluid to be combined in the
central area of the absorbent article 10 and to be wicked
downward.
[0050] In general, any of a variety of different materials are
capable of being used for the intake member 18 to accomplish the
above-mentioned functions. For example, airlaid cellulosic tissues
may be suitable for use in the intake member 18. The airlaid
cellulosic tissue can have a basis weight ranging from about 10
grams per square meter (gsm) to about 300 gsm, and in some
embodiments, between about 100 gsm to about 250 gsm. In one
embodiment, the airlaid cellulosic tissue has a basis weight of
about 200 gsm. The airlaid tissue can be formed from hardwood
and/or softwood fibers. The airlaid tissue has a fine pore
structure and provides an excellent wicking capacity, especially
for menses.
[0051] In some embodiments, the intake member 18 may also contain a
superabsorbent material to enhance its absorption capacity.
Superabsorbents have the ability to absorb a great amount of fluid
in relation to their own weight. Typical superabsorbents used in
sanitary napkins can absorb anywhere from about 5 to about 60 times
their weight in blood. Superabsorbent materials are produced in a
wide variety of forms including, but not limited to, particles,
fibers and flakes.
[0052] It has been found that superabsorbents having a high
mechanical stability in the swollen state, an ability to rapidly
absorb fluid, and ones having a strong liquid binding capacity
perform well in absorbent articles. Hydroxyfunctional polymers have
been found to be good superabsorbents for this application. For
example, a hydrogel-forming polymer, such as a partially
neutralized cross-linked copolymer of polyacrylic acid and
polyvinyl alcohol, can be utilized. After the polymer is formed, it
is mixed with about a 1% anhydrous citric acid powder. The citric
acid has been found to increase the ability of the superabsorbent
to absorb menses and blood. This is particularly beneficial for use
in a sanitary napkin or other feminine pads. The finely ground,
anhydrous citric acid powder, which is void of water, along with
trace amounts of fumed silica, is mixed with the polymer that may
have been screened to an appropriate particle size. This mixture
may also be formed into a composite or a laminate structure. Such
superabsorbents can be obtained from Dow Chemical,
Hoechst-Celeanese, and Stockhausen, Inc., among others. This
superabsorbent is a partially neutralized salt of cross-linked
copolymer of polyacrylic acid and polyvinyl alcohol having an
absorbency under load value above about 25.
[0053] The superabsorbent typically has a high absorbency under
load. That is, it typically has the ability to expand or swell
under a restraining pressure, such as about 0.3 psi. The absorbency
under load value is a function of gel strength, osmotic pressure
within the gel, and the composition of the polymer itself. The
absorbency under load value also pertains to the ability of the gel
to swell against other superabsorbent particles as well as against
adjacent fibers when under pressure. For purposes of this
invention, a superabsorbent having a high absorbency under load is
defined as having a value of about 20 or higher, and particularly
about 25 or higher. Some suitable superabsorbents are taught in
U.S. Pat. No. 4,798,603 to Meyers, et al., Re. 32,649 to Brandt, et
al. and U.S. Pat. No. 4,467,012 to Pedersen, et al., as well as in
published European Patent Application 0,339,461 to
Kellenberger.
[0054] A second absorbent member 20, or transfer delay member, is
also positioned vertically below the intake member 18. In some
embodiments, the transfer delay member 20 contains a material that
is less hydrophilic than the other absorbent members, and may
generally be characterized as being substantially hydrophobic. For
example, the transfer delay member 20 may be a nonwoven fibrous web
composed of a relatively hydrophobic material, such as
polypropylene, polyethylene, polyester or the like, and also may be
composed of a blend of such materials. One example of a material
suitable for the transfer delay member 20 is a spunbond web
composed of polypropylene, multi-lobal fibers. Further examples of
suitable transfer delay member materials include spunbond webs
composed of polypropylene fibers, which may be round, tri-lobal or
poly-lobal in cross-sectional shape and which may be hollow or
solid in structure. Typically the webs are bonded, such as by
thermal bonding, over about 3% to about 30% of the web area. Other
examples of suitable materials that may be used for the transfer
delay member 20 are described in U.S. Pat. No. 4,798,603 to Meyer,
et al. and U.S. Pat. No. 5,248,309 to Serbiak, et al., which are
incorporated herein in their entirety by reference thereto for all
purposes. To adjust the performance of the invention, the transfer
delay member 20 may also be treated with a selected amount of
surfactant to increase its initial wettability.
[0055] The transfer delay member 20 can generally have any size,
such as a length of about 150 mm to about 300 mm. Typically, the
length of the transfer delay member 20 is approximately equal to
the length of the absorbent article 10. The transfer delay member
20 can also be equal in width to the intake member 18, but is
typically wider. For example, the width of the transfer delay
member 20 can be from between about 50 mm to about 75 mm, and
particularly about 48 mm.
[0056] The transfer delay member 20 of the absorbent core 16
typically has a basis weight less than that of the other absorbent
members. For example, the basis weight of the transfer delay member
20 is typically less than about 150 grams per square meter (gsm),
and in some embodiments, between about 10 gsm to about 100 gsm. In
one particular embodiment, the transfer delay member 20 is formed
from a spunbonded web having a basis weight of about 30 gsm.
[0057] Besides the above-mentioned members, the absorbent core 16
also includes a composite member 22 formed according to one
embodiment of the present invention. For example, the composite
member 22 can be a three-layered coform material, such as described
above and illustrated in FIG. 1. In this instance, fluids can be
wicked from the transfer delay member 20 into the outer layer 70 of
the composite absorbent member 20. Because the outer layer 70 is
relatively hydrophobic and contains large pores, fluid readily
flows therethrough and into the inner layer 74, where it is
absorbed by the hydrophilic pulp fibers contained therein. In
addition, because the inner layer 74 has smaller pores than the
outer layers 70 and 72, the fluid tends to remain in the inner
layer 74, thereby inhibiting rewetting. If desired, the composite
absorbent member 22 may be formed separately from the intake member
18 and/or transfer delay member 20, or can be formed simultaneously
therewith. In one embodiment, for example, the composite absorbent
member can be formed on the transfer delay member 20 or intake
member 18, which acts a carrier during the coform process described
above.
[0058] The absorbent article 10 may also contain other components
as well. For instance, in some embodiments, the lower surface of
the baffle 14 can contain an adhesive for securing the absorbent
article 10 to an undergarment. In such instances, a backing (not
shown) may be utilized to protect the adhesive side of the
absorbent article 10 so that the adhesive remains clean prior to
attachment to undergarment. The backing can generally have any
desired shape or dimension. For instance, the backing can have a
rectangular shape with dimension about 17 to about 21 cm in length
and about 6.5 to 10.5 cm in width. The backing is designed to serve
as a releasable peel strip to be removed by the user prior to
attachment of the absorbent article 10 to the undergarment. The
backing serving as a releasable peel strip can be a white Kraft
paper that is coated on one side so that it can be released readily
from the adhesive side of the absorbent article 10. The coating can
be a silicone coating, such as a silicone polymer commercially
available from Akrosil of Menasha, Wis.
[0059] Once formed, the absorbent article 10 generally functions to
absorb and retain fluids, such as menses, blood, urine, and other
excrements discharged by the body during a menstrual period. For
example, the intake member 18 can allow the body fluid to be wicked
downward in the z-direction and away from the cover 12 so that the
cover 12 retains a dry and comfortable feel to the user. Moreover,
the intake member 18 can also absorb a significant amount of the
fluid. The transfer delay member 20 initially accepts fluid from
the intake member 18 and then wicks the fluid along its length and
width (-x and -y axis) before releasing the fluid to the composite
absorbent member 22. The composite absorbent member 22 then wicks
the fluid along its length and width (-x and -y axis) utilizing a
greater extent of the absorbent capacity than the transfer delay
member 20. Therefore, the composite absorbent member 22 can become
completely saturated before the fluid is taken up by the transfer
delay member 20. The fluid is also wicked along the length of the
transfer delay member 20 and the composite absorbent member 22,
thereby keeping the fluid away from the edges of the absorbent
article 10. This allows for a greater utilization of the absorbent
core 16 and helps reduce the likelihood of side leakage.
[0060] In addition to being utilized in an absorbent article in a
manner such as described above, the composite member of the present
invention may also be utilized in various other ways. For example,
referring again to FIG. 4, the composite member of the present
invention can function as the absorbent core 16 of the absorbent
article 10. In such instances, the outer layer 70 can function in a
manner similar to the intake member 18 by absorbing fluids at a
relatively fast rate. Likewise, the inner layer 74 can function in
a manner similar to the transfer delay member 20 by inhibiting the
flow of the fluids into the outer layer 72. In addition, the outer
layer 72 can contain a certain amount of thermoplastic polymer so
that it enhances the Edge-Compression value of the resulting
composite member. In other embodiments, the composite absorbent
member of the present invention may constitute the entire absorbent
article. For example, in one embodiment, at least one outer layer
of the composite absorbent member can be made relatively
liquid-impermeable so that it can readily function as the
liquid-impermeable baffle described above. Similarly, the composite
absorbent member can contain one or more layers to function as the
absorbent core and an additional layer that functions as a
cover.
[0061] Although various embodiments of absorbent articles have been
described above, it should be understood that other absorbent
article configurations are also contemplated by the present
invention. For instance, the materials described above are not
required in all instances. Moreover, other materials not
specifically discussed herein may also be utilized to form the
absorbent article. For example, various configurations of absorbent
articles that can be used in the present invention are described in
U.S. Pat. No. 6,160,197 to Lassen, et al., U.S. Pat. No. 5,649,916
to DiPalma, et al., U.S. Pat. No. 5,609,588 to DiPalma, et al., and
U.S. Pat. No. 5,248,309 to Serbiak, et al., which are incorporated
herein in their entirety by reference thereto for all purposes.
[0062] The present invention may be better understood with
reference to the following example.
EXAMPLE
[0063] The ability to form a composite absorbent member in
accordance with the present invention was demonstrated. In
particular, a two-layered, composite coform material was formed
according to the general procedures substantially described above
and illustrated in FIG. 2, except that only 2 meltblown units were
utilized. For instance, polypropylene resin (PD 701-Hercules) was
initially extruded from a series of orifices. The extrusion rate
was at about 9 pounds per inch per hour from each of the two (2)
meltblown units. The extrusion was at a final temperature of about
500.degree. F. and fibers were attenuated in primary air streams
flowing at a sonic velocity and a combined rate of about 325 SCFM
at a temperature of about 510.degree. F.
[0064] The secondary air stream containing suspended pulp fluff was
comprised of Southern pine bleached kraft. The pulp was picked and
forced into a fiber jet approximately 2 inches from the primary air
stream and 1.5 inches below the die tip. The velocity of the
primary air was between about 2 times the velocity of the secondary
stream at the point it was introduced. The composite coform
material was collected on a wire mesh belt, which was about 10
inches below the extrusion die tip. For the samples below, the
speed of the wire mesh belt was varied from between about 160 feet
per minute (fpm) to about 330 fpm.
[0065] The first meltblown unit in which pulp fibers were added was
placed downstream from the second meltblown unit. The two meltblown
units were essentially identical, except that each were supplied
with differing pulp fiber contents as set forth below in Tables
1-2.
[0066] For samples 9-10, a spunbond transfer delay member (0.4 osy)
was used as a carrier for the absorbent member, while for samples
11-12, a spunbond transfer delay member (0.8 osy) as a carrier for
the absorbent member.
[0067] The properties of the samples are set forth below in Tables
1-2.
1TABLE 1 Sample Properties Bank 1 Bank 2 Polymer Pulp Polymer Pulp
Basis Wt. Thickness Density Sample (wt. %) (wt. %) (wt. %) (wt. %)
(gsm) (mm) (g/cc) 1 50 50 50 50 162.4274 1.9067 0.0856 2 40 60 60
40 169.8545 2.1500 0.0793 3 30 70 70 30 168.9934 2.2950 0.0738 4 20
80 80 20 171.4691 2.2300 0.0771 5 40 60 70 30 172.2226 2.1267
0.0811 6 40 60 80 20 178.0351 2.1600 0.0826 7 30 70 40 60 160.7052
2.1850 0.0737 8 30 70 80 20 163.2885 2.0783 0.0788 9 40 60 40 60
185.6775 1.9567 0.0950 10 60 40 30 70 185.8927 2.0033 0.0930 11 40
60 40 60 200.9622 2.1000 0.0957 12 60 40 30 70 202.4692 2.2033
0.0921 13 40 60 70 30 161.8892 2.1100 0.0768 14 40 60 80 20
172.5455 2.1200 0.0814
[0068]
2TABLE 2 Sample Properties Bank 1 Bank 2 Basis Polymer Pulp Polymer
Pulp Wt. Thickness Density Sample (wt. %) (wt. %) (wt. %) (wt. %)
(gsm) (mm) (g/cc) 15 40 60 40 60 164.2573 2.0317 0.0810 16 35 65 35
65 163.8267 2.1317 0.0771 17 30 70 30 70 158.6600 2.1750 0.0731
[0069] Once the composite coform material was formed, various
properties of the resulting absorbent members were tested. In
particular, the Edge-Compression (EC) value of a 2".times.12"
specimen of the material was determined as substantially described
above, except that a manual instrument was used to determine the
buckling weight instead an Instron tensile tester. Specifically,
the manual instrument contained two (2) plexiglass platens having a
size larger than the sample. The sample was prepared as described
above and placed between the platens. Calibrated weights were then
placed on the top platen until the sample collapsed. The weight
required to collapse the sample was recorded.
[0070] Moreover, the penetration (intake) rate and MD tensile
strength of the absorbent members were determined as follows:
[0071] Penetration (Intake) Rate: To measure how quickly the coform
material would accept a liquid, a penetration rate test was
performed using "Z-Date," a synthetic menstrual fluid formulation
available from PPG Industries, Inc. of Pittsburgh, Pa. that
contains, on a weight percent basis, approximately 82.5% water,
15.8% polyvinyl pyrrolidone and 1.7% salts, coloring agents and
surfactants. "Z-Date" has a viscosity of 17 centipoise and a
surface tension of 53.5 dynes per centimeter. To determine the
penetration rate, a 3".times.7" sample of the absorbent member was
initially applied with 4 mL of the synthetic menstrual fluid, which
was delivered from a fluid reservoir having a 2".times.0.5"
delivery slot. The time to absorb 4 mL of fluid was then measured
in seconds. A lower absorption time as measured in seconds was an
indication of a faster intake rate for the particular material. The
test was run at conditions of 73.4.degree.+/-3.6.degree. F. and 50%
+/-5% relative humidity. Such a procedure is also described in U.S.
Pat. No. 5,643,240 to Jackson, et al., which is incorporated herein
in its entirety by reference thereto for all purposes.
[0072] MD Tensile Strength
[0073] MD (machine direction) tensile strength was determined using
a MTS/Sintech tensile tester (available from the MTS Systems Corp.,
Eden Prairie, Minn.). Samples measuring 3 inch wide were cut in the
machine direction. For each test, a sample strip was placed in the
jaws of the tester, set at a 4 inch gauge length for facial tissue
and 2 inch gauge length for bath tissue. The crosshead speed during
the test was 10 inches per minute. The tester was connected with a
computer loaded with data acquisition system; e.g., MTS TestWork
for windows software. Readings were taken directly from a computer
screen readout at the point of rupture to obtain the MD tensile
strength of an individual sample. The results are given below in
Table 3.
3TABLE 3 Sample Results Sample EC (g) Penetration Rate (s) MD
Tensile (g) 1 369.23 23.667 1997.10 2 421.55 37.500 2001.18 3
436.55 22.000 2451.13 4 399.22 19.167 2431.93 5 534.57 22.667
2618.33 6 698.47 37.667 3268.18 7 380.82 14.833 1653.27 8 416.83
25.333 2496.22 9 378.60 20.500 4346.78 10 375.21 20.500 4721.72 11
355.34 21.000 5135.52 12 415.04 37.167 N/A 13 544.82 37.167 N/A 14
498.07 46.667 N/A 15 284.26 14.167 1491.88 16 178.20 19.833 1188.14
17 137.00 18.333 994.28
[0074] For comparative purposes, an airlaid cellulosic tissue was
formed having a basis weight of 175 gsm, a caliper of 2.19 mm, and
a density of 0.08 g/cc. The EC value, penetration rate, and MD
Tensile strength of the airlaid tissue was tested as described
above. The results are given below in Table 4.
4TABLE 4 Control Sample Results Sample EC (g) Penetration Rate (s)
MD Tensile (g) 18 450.73 75.167 1958.47
[0075] Thus, as demonstrated above, a composite absorbent member
formed according to the present invention can have good absorption
characteristics, while also maintaining a relatively high
Edge-Compression (EC) value. For instance, the control sample had
an EC value of 450.73 grams, while absorbent members formed
according to the present invention had EC values up to 698.47 grams
while still maintaining a good intake rate. Such high EC values
reflect the ability of absorbent members of the present invention,
even when used in thin absorbent articles, to inhibit bunching and
twisting.
[0076] While the invention has been described in detail with
respect to the specific embodiments thereof, it will be appreciated
that those skilled in the art, upon attaining an understanding of
the foregoing, may readily conceive of alterations to, variations
of, and equivalents to these embodiments. Accordingly, the scope of
the present invention should be assessed as that of the appended
claims and any equivalents thereto.
* * * * *