Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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NONWOVEN AND FILM CORRUGATED LAMINATES
FT~T~n OF THE INVENTION
The present invention is directed to corrugated laminates
of two or more layers which can use among other materials
films ancl nonwovens to form the laminates. The laminates have
a wide variety of applications, including, but not limited to
cover materials for personal care absorbent articles.
BACKGROUND OF THE INVENTION
Laminates are composite materials made from two or more
layers or sheets of material which have been attached to one
anotherO The resultant laminates can be used for a number of
applications including for example, cover materials for
plersona~ care absorbent articles such as diapers, training
plants, fG ;nine hygiene products such as sanitary napkins,
incontinence devices, bandages and the like. All of these
p,roducts typically include a body side liner or cover, an
outer cover or backing sheet and an absorbent core disposed
between the body side liner and the outer cover.
Two of the most commonly used materials in constructing
the body side liners and outer covers of such articles are
plastic films-and fibrous nonwoven webs. Plastic films have
the advantage that they are liquid impervious. As a result,
they are commonly used as the outer cover material for such
articles. If perforated or otherwise apertured, they can pass
liquids thereby making them useable as body side liners for
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the same articles. Nonwovens generally by design are both
liquid and gas permeable. As a result, when used as body side
liners, they will readily pass body fluids such as urine and
mens-es. If the pore structure of such nonwovens is made, for
example, sufficiently small, the same nonwovens also tend to
become resistant to liquid penetration and therefore can be
used as outer cover materials as well. Lastly, it is also
possible to combine such films and nonwovens in various
configurations to form laminates which can be used for the
same purposes.
When using films and nonwovens either alone or in
combination for body side liners for personal care absorbent
articles, several disadvantages become apparent, especiaily
when such materials are used in conjunction with body fluids
such as menses. Menses when compared to other body fluids
such as urine is highly viscose in nature due its blood-based
composition and high particulate content. As a result, it is
oftentimes difficult to completely transfer such materials all
the way through the body side liner and into the absorbent
core for storage until the article is discarded.
From a personal hygiene standpoint, it is desired by the
user that there be as much separation of such body fluids as
urine and menses away from the skin of the user as is possible
to provide a cleaner and drier feel. In addition it is
desirable for the body side liner to have as little contact
with the user as is possible. Unfortunately, such materials
do not provide sufficient three-dimensionality to always
provide the ~ser with such a clean and dry feel. As a result,
it is an object of the present invention to provide a material
which can be used in such applications and provide such a
perception. The same materials also may be used for a wide
variety of other applications as will become more apparent
from the following description, drawings and claims.
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';UMMARY OF THE INVENTION
The present invention is directed to corrugated laminates
o~ two or more layers of material. The laminates comprise a
i'irst sheet of material attached to a second sheet of material
at one or more locations between the sheets which result in
c~ plurality of generally parallel corrugations forming a
series of peaks separated by a series of valleys. The
:Laminate! in the vicinity of the peaks has a first density and
:in the vicinity of the valleys has a second density with the
second density being greater than the first density.
The materials from which the first and second sheets may
be formed vary widely and include, but are not limited to,
Eilms, wovens, nonwovens, foams and laminates of one or more
of the foregoing materials. In order to obtain the density
~lifferential between the peaks and valleys of the laminate it
i5 desirable that at least one of the materials be made from
~ compr~essible web which is capable of having its density
changed. A fibrous nonwoven web is but one example of such
a material.
In addition to having a density differential, it is also
possible to have a pore size differential in the laminate
according to the present invention. For example, if either
or both of the first and second sheets are made from a
compres;ible web such as a fibrous nonwoven web, then the
laminat:e in the vicinity of the peaks may have a first average
pore size and in the vicinity of the valleys may have a second
average pore size with the first average pore size being
~ greater than the second average pore size.
Thle size and spacing of the peaks and valley will vary
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depending upon the particular end use. Generally, however,
the laminates will have spacing between adjacent peaks of from
about 2 to about 7 millimeters and the vertical height of the
laminate will range between about 0.5 and about 5 millimeters
especially when such materials are being used in conjunction
with personal care absorbent articles.
Personal care absorbent articles include such products
as diapers, f~m i n i ne hygiene products including sanitary
napkins and pantiliners, incontinence devices, training pants,
bandages, wipes and the like. Typically these articles will
have a design which will include a body side liner and an
outer cover with an absorbent core disposed therebetween.
Such articles will also typically have a longitll~inA 1 and a
transverse axis with the longit~l~in~l axis corresponding to
the longer dimension of the product.
The laminate of the present invention is particular well-
suited for use as body side liner in such personal care
absorbent articles. The corrugations act to distance th~
product from the user and to trap solid particulate matter in
the valleys of the corrugations thereby providing ~h~ceA
comfort to the user. As shown by the drawings, the
corrugations can be positioned-to be generally parallel to
either or both the transverse and longitudinal axes of the
product. In more specific embodiments, the body side liner
can be desiqned to have two side regions separated by a
central region with the corrugations in the central region
being generally perpendicular to the corrugations in the two
side regions.
Several processes are described herein for forming
materials according to the present invention. In one process
the first and second layers of material are placed in
generally face to face relationship and then at least one of
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the ~i~st or second layers is str~tched- While in a stretched
state, the two layers are bonded together at spaced apart
generally parallel bond lines to form the laminate. Once the
bonaing has taken place, the laminate is allowed to relax
thereby forming a plurality of corrugations which include an
alternating series of peaks and valleys with the laminate in
the vicinity of the peaks having a first densit:y and in the
~icinity of the valleys having a second density with the
second density being greater than the first density.
Depending on the equipment being used, the process can be
varied as, for example, by deleting the stretch;n~ step and/or
applying and adhesive between the first and second layers to
further aid in the bonding.
15One apparatus used to form laminates according to the
present invention includes a first geared tooth roll ha~ing
a plurality of teeth a~out its periphery with these teeth-
defining a first angle therebetween. This first geared tooth
roll is designed to intermesh with a second geared tooth roll
which also has a plurality of teeth about its periphery which
define a second angle therebetween. The angles are designed
such that the first angle of the teeth on the first roll are
greater than the second angle of the teeth on the second roll.
As a result, the apparatus is ~able to form the corrugated
laminates according to the present invention with varying
densities between the peaks and the valleys.
BRIEF ~ESCRIPTION OF THE DRAWINGS
30Figure ~ is a cross-sectional side view of a nonwoven and
film corrugated laminate according to the present invention.
Figure 2 is a partial cut-away perspectiYe view of a
personal care absorbent article, in this case a sanitary
napkin, which utilizes a nonwoven and film corrugated laminate
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according to the present invention as the body side liner of
the personal care absorbent article.
~Figure 3 is a cross-sectional side vi~w of the personal
care absorbent article of Figure 2 taken along line 3-3 of
Figure 2.
Figure 4 is a schematic side view of a process for
forming a nonwoven and film corrugated laminate according to
the present invention.
Figure 5 is a schematic side view of another process for
forming a nonwoven and film corrugated laminate according to
the present invention.
Figure 6 is a partial side view of a pair of geared
corrugating rolls which can be used in conjunction with the
process shown in Figure 5.
Figure 7 is a top plan view of a body side liner of a
personal care absorbent product utilizing a laminate according
to the present invention.
Figure 8 is a top plan view of a body side liner of a
personal care absorbent product utilizing a laminate according
to the present invention.
Figure 9 is a top plan view of a body side liner of a
personal care absorbent product utilizing a laminate according
to the present invention.
Figure 10 is a top plan view of a body side liner of a
personal care absorbent product utilizing a laminate according
to the present invention.
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Fi~ure 11 is a photomicrograph of the material according
~o the present invention as described in Example 1.
Fig~ure 12 is a photomi~o~Laph of the material according
~o the present invention as described in Example 2.
13~TAILE~ DESCRIPTION OF T~ NrVENTION
Re~erring to Figure 1 of the drawings, there is shown a
laminate 10 according to the present invention, including a
first la~yer 12 and a second layer 14. While thi~ is the most
~asic embodiment of the present invention, it should be
~ppreciated that more complex embodiments can be made by
adding additional layers (not shown) to the la~inate 10 and
these additional embodiments are also contemplated to fall
within t:he scope of the present invention.
Bo1:h the first layer 12 and the second layer 14 can be
made from a wide variety of materials including but not
limited to films and fibrous nonwoven webs as well as
combinations of the two materials. As shown in Figure 1, the
first layer 12 is a layer of film with a plurality of
apertures 13 defined therein and the second layer 14 is shown
as a layer of fibrous nonwoven web material. Other materials
can be used for either or both the first layer 12 and the
second layer 14. Examples of other materials include, but are
not limited to, foams, tissues, coform materials and
combinations of the forgoing materials. When using the
material of the present invention as, for example, a body side
liner ~or a personal care absorbent article such as a sanitary
napkin, it is desirable that at least one of the layers be a
compressible web. By that it is meant a web which, when
subjected to compression and/or bonding techniques, will have
~n incr~ease in its density and a reduction in the average pore
~ 35 size of the structure in specified areas of the structure.
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Foams and fibrous structures such as wovens and nonwovens are
particularly good examples of compressible webs. Examples of
suitable nonwoven webs include, for example, air laid and wet
laid~ webs as well as bonded carded webs all of which are
typically made from staple length or shorter fibers. The
fibers themselves may be natural or synthetic as well as a
blend of fibers as is possible, for example, in coform
materials. Synthetic fibers which are made from or include
materials which are thermobondable have been found to work
particularly well as they can be heat bonded to one another
as well as to other fibers which is helpful when changing the
density of the second layer as is required by the present
invention. To this end, multiconstituent and multicomponent
fibers such as biconstituent and bicomponent fibers have been
found to work particularly well. Nonwoven webs made from more
continuous fibers such as spunbond fibers and meltblown fibers
can also be used to form one or both of the layers of the
present invention. These f ibers also may be made from single
and/or multiconstituent or multicomponent f ibers.
The films used with the present invention can be made in
a wide variety of thicknesses and from a wide variety of
polymers. If the laminate formed by the present invention is
intended to pass liquids, the film should be provided with
apertures or other pores of sufficient size so as to be able
to pass liquids including body fluids such as blood, urine or
menses. In addition, if desired, it is possible to make the
film layer breathable, especially when the laminate is being
used as an outer cover on a personal care absorbent article.
Breathability-can be imparted ~, for example, using fillers
in the film polymer formulation, extruding the filler/polymer
formulation into a film and then stretching the film
sufficiently to create voids around the filler particles,
thereby ma~ing the film breathable. Generally, the more
3S filler used and the higher the degree of stretching, the
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greater will be the degree o~ breathability- If the film is
to be bonded to a fibrous nonwoven layer, it may be desirable
to make it from or design it such that it is heat bondable to
the~other layer of the laminate.
As will be explained in greater detail below in
conjunction with the process description, the t:wo layers 12
and 14 are bonded to one another along a plurality of bond
lines 16 in such a fashion that a plurality of longit~inAl
and/or transverse pleats or corrugatio~s are formed in the
laminate 10. These bond lines may be continuous or
disconkinuous and will be generally parallel to one another.
By "generally parallel" it is meant that the bond lines
themselves or an extension of the bond lines will either~not
intersect or if they do intersect, the interior angle formed
by the intersection will be less than or equal to 45 degrees.
Re~erring again to Figure 1, the areas 18 adjacent the
bond lines 16 in the compressible fibrous nonwoven layer
(second layer 14) have an increased density as c~ -~ed to the
density of the portions 20 of the compressible web 14
intermelliate the bond sites 16. This is because the fibers
of the ,_ompressible web 14 are more tightly compacted in the
areas 18 surrounding the bond lines 16. As a result, the
material in these areas has a higher density and smaller pore
sizes than the material in the areas 20 intermediate the bond
lines 16.
Referring to Figures 2 and 3, the laminate material 10
of the present invention can be used, for example, on a
personal care absorbent article 40 as a body side liner 42
with thle second layer 14 position adjacent an absorbent core
44 or ~ome other internal component of the artic:le 40. Such
articles 40 will also typically include some type of backing
or outer cover 46 such as a plastic film or other generally
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.
liquid-impervious material.
With the film side of the laminate 10 adjacent the user
and~the nonwoven side adjacent the absorbent core 44, fluid
entering the laminate 10 through the first layer 12 in the
raised or convex areas 20 intermediate the bond lines 16 will
pass through the first layer 12 and come in contact with the
lower density portion of the nonwoven material 14. Due to
what the inventors believe to be capillary action, this fluid
will be drawn down to the areas 18 adjacent the bond sites 16
where the nonwoven has a higher density and from there the
fluid will be drawn/passed into the absorbent core 44.
Consequently, a structure can be formed which will have less
affinity for body fluids in the raised or convex areas 20
which are adjacent the wearer's skin and a higher affinity for
the same fluid in the more densified areas 18 around the bond
sites 16 where the fluid can then be transferred to the-
absorbent core 44.
As can be seen from the cross-section of the material in
Figure 1, the laminate 10 has raised peaks separated by
valleys with the raised areas or peaks being in vertical
registry with the less dense areas 20 and the valleys being
in vertical registry with the bond lines 16. As a result, the
material is particularly well-suited for use as a liner on a
sanitary napkin, incontinence device or other product designed
to receive and absorb more viscous and/or particulate
containing fluids such as is the case with blood, menses and
feces. These materials which do not readily flow through the
liner material can collect in the valleys which in turn
distances these materials from the user's skin thereby
providing improved dryness and comfort.
Referring to Figure 4, one method and apparatus for
forming materials according to the present invention involves
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~;tretch-ing one of the two layers 12 and 14 in one direction
prior to the bonding of the stretched layer to the non-
stretched layer. Once the two layers have been bonded to one
another the stretching or tensional forces can be relaxed
t:hereby causing the composite to retract and corrugate or
pleat. Thus, for example, the nonwoven second layer 14 can
be stretched in the machine direction and then bonded to the
iilm layer 12. Conversely, the film layer 12 can be stretched
cmd then bonded to the unstretched fibrous nonwoven second
].ayer 14. To accomplish this, the first layer 12, which in
t:his case for illustration purposes only is a fil~, is unwound
from a first unwind 30 while the second layer 14, which is a
fl~brous nonwoven web, is unwound from a second unwind 32. The
second layer is unwound in such a fashion that as it comes
into thl_ bonding apparatus 34, it is in a stretched or
1:ensioned condition. This can be accomplished for example
}jy bra~iLng and/or driving the second unwind 32 at a speed
~rhich i.s less than the speed of the first unwind 30/first
:Layer 17. and less than the rotational surface xpeed of the
corrugat.ed bonding roll 35 which is part of the bon~ng
apparatuis 34. By stretching one of the two layers in a
direction transverse to the bond lines, the laminate will
corrugat:e in between the bond lines 16 when the tension is
released. As shown in Figure 4- the corrugated bonding roll
35 imparts bond lines which are transverse to the machine
direction of the material. Alternatively, the corrugated
]bonding roll 35 can have its teeth running parallel to the
machine direction of the apparatus in which case the
stretchi.ng of one of the layers must be in the cross-machine
~irection.
As shown in Figure 4, the bonding and corrugating
apparatus 34 includes a corrugated or geared tooth bonding
roll 35 and an ultrasonic horn 38. The ultrasonic horn is
~ 35 activated and as each of the raised tooth portions of the
11 ~
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bonding- roll 35 comes in registry with the horn 38 bonding
results whereas between the teeth no bonding takes place. As
a result, a line of bonding is achieved between the first
layer 12 and the second layer 14 with the nonwoven material
being more densely compacted at the bond sites 16 and the
areas 18 ;m~iately surrounding the bond sites 16 as compared
to the convex portions 20 intermediate the areas 18. Once
the bonding of the two layers has been completed and the
laminate 10 thus formed, the tensional forces are released and
the laminate is allowed to relax, thus enhancing the
corrugations or pleats in the laminate 10 as it is wound onto
a take-up roll 39. Additionally,an adhesive spray applicator
33 may be positioned between the two layers 12 and 14 to spray
or otherwise apply a layer of adhesive to one or both the
layers 12 and 14 prior to their entering the bonding apparatus
34.
An important feature of the above-described process is
the corrugations or pleats caused by stret~h; nq one of the
first and second layers, bonding the layers together and then
retracting the overall laminate. The corrugations or pleats
increase the overall surface area per unit area of laminate
10 thereby making the laminate thicker and more bulky.
A second process and apparatus for forming laminates 10
according to the present invention is shown in Figure 5 of the
drawings. This process is similar to and run in the same
manner as the process shown in Figure 4. As a result, like
reference numerals are used for like elements. The main
difference is in the bonding apparatus 34.
The bonding apparatus 34 in Figure 4 includes a geared
tooth bonding roll 35 and an ultrasonic horn 38. In Figure
5 the ultrasonic horn 38 has been replaced with a second
geared tooth bonding roll 36 which is designed to intermesh
12
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with t]le first geared tooth bonding roll 35. In order to
bring about bonding and/or densification it is desirable that
heat be applied to one or both of the webs either just before
or during bonding. consequently, one or both of the bonding
S rolls 35 and 36 may be heated to thermally bond the two layers
of mate:rial together. If the bonding rolls are not heated,
then a preheating of the webs must take place as with for
example an infrared or through-air bo~i ng apparatus 37
positioned just before the bonding apparatus 34.
Alterna1_ively or in addition to the heating of one or both of
the webs an adhesive spray applicator 33 may be positioned
between the two layers 12 and 14 to spray or otherwise apply
adhesive to one or both the layers 12 and 14 prior to their
entering the bonding and corrugating apparatus 34.
Turning to Figure 6 the first geared tooth bo~ g roll
35 has a plurality of teeth 50 which are designed to intermesh
with the valleys 51 between the teeth 53 on the second geared
tooth bonding roll 36. The apices 55 of each of the teeth 50
form an~ angle A while the valleys 51 between the teeth 53 of
the bonding roll 36 form a second angle B. Angle A is
designed to be greater than angle B. As a result there is
greater area between the apices 55 of the geared tooth roll
35 and the valleys 51 of the geared tooth roll 36 than there
is between the apices 57 of the geared tooth ro}.l 36 and the
valleys 54 of the geared tooth roll 35. Thus when a laminate
is formled with the nonwoven layer 14 adjacent the first roll
35 and the film layer 12 adjacent the second roll 36, there
will be higher degrees of compaction of the two layers
together in the areas adjacent the valleys 54 of the first
roll 35 than in the valleys 51 of the second roll 36. This
in turn will yield a laminate similar to that described in
Figures 1 through 3 of the drawings with the ~ond lines 16
being formed in the areas of intermeshing of the peaks 57 of
roll 36 with the valleys 54 of roll 35. It should be noted
13
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that if- the angles A and B equal one another there will be
uniform density throughout the laminate but as the
differential between the angles A and B increases, the density
gradient will increase. The degree of densification can be
further varied by adjusting the gap between the two rolls 35
and 36. A smaller gap will increase densification.
Variations to the two processes described above include
imparting corrugations or pleats to the laminate by making one
of the two layers from a heat retractable or heat shrinkable
material. Examples of such materials include oriented films
that are not heat set and elastomeric materials made from
resins including, for example, polyurethanes, polyesters,
polyolefins and polyacetates. In this process, the heat
shrinkable layer, whether film, nonwoven or otherwise, is
bonded to the other layer using one of the bonding ~chAnisms
described above and, once bonded, the laminate is subjected
to a sufficient amount of heat to cause the heat shrinkable
layer to retract thereby causing the laminate to corrugate or
pleat. Here again, either the first layer or the second layer
can be made heat shrinkable. Care should be taken though that
the amount of heat needed to effect shrinking does not destroy
the bonding between the layers.
Yet another means for imparting corrugations or pleats
to the laminate involves stretching one of the layers and
bonding it to the other layer with the other layer being made
from a heat shrinkable material. Once the two layers are
bonded, the tension in the stretched layer can be relaxed and
heat can be applied to the laminate thereby providing two
means within the same laminate for creating corrugations or
pleats.
Having described the materials, apparatus and processes
of the present invention, it should become apparent that
14
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various- modifications can be made to the present invention.
For example, turning to Figures 7 through 10 there are shown
several additional body side liner designs which can be made
uti~izing the present invention. Referring to Figure 7, there
is show~n a body side liner 90 wherein the bond lines 16,
while still linear in nature, are not continuous but instead
broken lines of bonding. Such broken lines of bonding will
still form corrugations and as a result are still considered
to be within the scope of the present invention and the term
"bond lines."
In Figure 8 of the drawings there is shown a body side
liner 1~0 which has two side regions 102 and 104 separated by
a central region 106. As can be seen from the drawing, the
central region 106 contains the corrugations while the side
regions 102 and 104 are devoid of any corrugations. Figure
9 is the same as Figure 10 but for the fact that the
corrugations in the central region 106 are generally parallel
to the longitudinal axis 110 and generally perpendicular to
the transverse axis 112 whereas the corrugations in Figure 8
are generally perpendicular to the longitudinal axis 110. By
"generally perpendicular" it is meant that the bonds lines or
an extension thereof intersect at an interior angle which is
greater than 45 degrees and less-than or equal to 90 degrees.
Lastly, in Figure 10 of the drawings, the body side liner 100
has corrugations in all regions 102, 104 and 106 with the
corrugations in the central region 106 being generally
perpendicular to the corrugations in the side regions 102 and
104. ~f course the direction of the corrugations in region
106 as compared to regions 102 and 104 can be reversed.
Having described the materials and processes of the
present invention, several sample materials were prepared and
tested to demonstrate the present in~ention. The test
procedures and examples are set forth below.
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T~T PROCEDURES
Several test methods were employed in determining the
properties of the materials according to the present
invention. The methods for determining these properties are
set forth below.
INTAKE l~ND REWET TESTING
The absorption time test indicates the intake rate for
a material or laminate using of synthetic menstrual fluid.
The composition of the synthetic menstrual fluid comprised,
on a weight percent basis, approximately 82.5% water, 15.8%
polyvinyl pyrrolidone and 1.7% salts, coloring agents, and
surfactants. It has a viscosity of 17 centipoise and a
surface tension of 53.5 dynes per centimeter. A 3 inch by
5 inch (7.6 cm by 12.7 cm) sample of the test material was
placed on top of nonabsorptive surface and insulted with 10
cc of synthetic menstrual fluid delivered from a fluid
reservoir having a 2 inch by 0.5 inch (5.1 cm by 1.3 cm)
delivery slot. The block was marked with a level line to
indicate when 8 of the lO cc has been delivered. The time to
absorb 8 cc of fluid was then measured in seconds. A lower
absorption time as measured in seconds was an indication of
a faster intake rate for a particular material. The values
reported in the Examples were based upon an average of five
samples.
After determining the time to absorb 8 cc of fluid, an
additional one minute of time was allowed to elapse to permit
the additional 2 cc of fluid in the delivery block to ba
absorbed into the sample. Next the delivery block was removed
and a preweighed piece of blotter paper was placed on top of
the sample and a one pound per square inch (0.070 kg/cm2)
16
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pressure was applied to the blotter paper and specimen for a
period of three minutes. At the end of the three minute
period the blotter paper was removed and weighed and the
amount of synthetic menstr~al fluid absorbed by the blotter
5 paper was measured in grams and was an indication of the
degree of rewet. Higher values were an indication of a
greater degree of rewet for the particular material tested.
The values reported in the Examples were based upon an average
of five samples.
THICKNESS
The thickness of the materials, including laminates, was
measured using the Starrett Bulk test. Under this test a 12.7
15 x 12.7 centimeter sample of the material was compressed under
a load of 0.05 pounds per square inch (3.5 grams per square
centimeter) and the thickness was measured while under this
]Load. Higher numbers indicate a thicker material. Five
~;amples were measured for each material and then averaged.
20 Values given are for the average.
E3ASIS WEIGHT
The basis weights of the -various materials described
25 herein were determined in accordance with Federal Test Method
Number l9lA/5041. Sample size for the specimens was lS.24 x
lS.24 centimeters and three values were o~tained for each
material and then averaged. The values reported below are for
1:he average.
Pore Size ~nd Densitv Gradient Tests
The meehod for determining the Pore Size Gradient and Density
Gradient is described below. The method involves taking
~ 35 ~veral representative cross sections of a laminat:e sample and
17
,
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photographing the fiber network of the cross section by image
analysis. The Pore Size is determined by measuring the
distance between the fibers as the image is scanned from bond
line-to bond line and is reported in millimeters. The Density
Gradient is calculated by measuring the vertical height of
several scan lines from bond line to bond line and dividing
the basis weight by the measured height.
S~mnle PreParation
A cut section of sample was placed face up in an embe~;~g
mold. Enough embedding medium was added to completely
saturate and surround the sample. After curing, additional
medium was added and cured where samples had floated,
resulting in part of the sample not being fully embedded.
Cured molds were trimmed with a belt sander to expose the
sample and produce faces parallel to the Y-Z plane of the
sample thereby providing a cross-sectional view of the sample.
Thin sections were then cut with a microtome for mounting on
glass microscope slides.
Two to three photomicrographs from each of two to three cross
sections per sample were -obtained to produce 6
photomicrographs per sample. Photographic exposure was
adjusted to produce bright fibers on a black background.
Sample size: 0.7S" (l9.lmm) x 1.5" (38.2mm) MD parallel
to short dimension
Embedding mold: 1" (25.4mm) x 1.75" (44.5mm) x 0.75"
(19.lmm) deep
Embedding medium: LADD ultra low viscosity epoxy (use
recommended formulation for a medium
18
CA 02222444 l997-l2-l8
W 0 97/02133 PCTnUS96/10667
hardness block)
Microtome: Reichert Polycut E with tungsten car~ide
type D knife
,Section thickness: 25 um
~icroscope slides: 2 (50.8mm) x 3 (76.2mm) glass
¢over s]ips: 24mm x 50mm glass
]MountincJ medium: Resolve brand microscope immersion oil nD
= 1.5150
15 Microscope: Leica Wild M-420 Makroskop
Camera: Leica with polaroid sheet film back
~ilm: Polaroid T-53 (ASA 800) 4 (101.6mm) x 5
(127.Omm) instant sheet film
Magnification: 10.3X
~Exposure conditions: transmitted illumination, dark field
Measurement Technique
Image analysis by QUANTIMET 970 (Cambridge Instruments,
Deerfield, Illinois) macroviewer using a 35 mm lens, autostage
as a spacer, 65-cm camera pole position, and 4 incident flood
Lamps. A series of ten fields were scanned for each example.
Computer Program #1 was used to scan for Pore Size Gradient
and Computer Program #2 was used to scan for Density Gradient.
- 35 The results are shown in Tables 1 and 2.
19
CA 02222444 1997-12-18
W O 97/02133 PCTnUS96/10667
.
,
CQ~ul~K PROGRAM #1
Cambridge Instruments QUAhl~lM~l 970 QUIPS/MX: V08.00
DOES z SPACING VS DEPTH POSN OF NW MAT~RTA~
COND = 35 MM LENS; 65 CM POLE POSN; 4 FLOODS; ASTGE SPACER
Enter specimen identity
Scanner ( No. 1 Chalnicon LV= 0.00 SENS= 1.94 PAUSE )
Load Shading Corrector ( pattern - CHRISl)
Calibrate User Specified (Cal Value = 0.01077 millimeters per
pixel for photos at 10.3X magnification)
~U~l~ STANDARD
~ ~DS :z 0.
TOTAREA := 0.
X := O.
y := O.
20 W = o.
H := 0.
TEMP := o.
NUMFIELDS := 1.
Input NUMFIELDS
For FIELD
Detect 2D( Lighter than 64, Delin )
Image Frame (Pause) is Rectangle ( X: 228, Y: 84, W: 448,
H:451, )
30 X ;= I.FRAME.X - 2.
Y := I.FRAME.Y - 2.
W 2 I.FRAM.WR + 6.
H := I.FRAME.H + 4.
Live Frame is Rectangle ( X:X , Y:Y , W:W , H:H
, )
CA 02222444 1997-12-18
O 97/02133 ~CT~S96~10667
~etect -~D ( Lighter than 24, Delin PAUSE )
~mend ( OPEN by 1 )
Edit (pa~use)
-
Measure feature AREA X.FCP Y. FCP
into array FEATURE (of 400 features and 10 parameters )
Accept EEATURE AREA from 0. to 0.03000
Nearest neighbour in FEATURE (CALC.A,CALC.B,CALC.C)
ORIGIN := L.FRAME.X
FEATURE X.MIN := X.FCP - ORIGIN
l?EATURE X.MIN := X.MIN * CAL.CONST
EEATURE CALC.C := CALC.C * CAL.CONST
FEATURE CALC.C := CALC.C / NUMFIELDS
l)istribution of CALC.C (Units MM ) v X.MIN (Units MM )
from FEATURE in HISTO1 from 0. to 4.000
in 20 bins (LIN)
~:Ol~lrLDS := lOl~l~LDS + 1.
Pause Message
PLEASE CHOOSE ANOTHER FIELD, OR "FINISH"
Pause
Next FIELD
Print " "
~'rint " TOTAL NUMBER OF FIELDS SCANNED = " , TO~ LDS
Print " "
Print Distribution ( HISTOl, differential, bar c:hart, scale
=s o.oo)
E'rint " "
~'rint " "
Print " "
35 F'or LOOPCOUNT = 1 to 10
21
CA 02222444 1997-12-18
W O 97102133 PCTrUS96/10667
Print "-~'
Next
END ~F PROGRAM
CQ~u~l ~ PROGRAM #2
Cambridge Instruments QUANTIMET 970 QUIPS/MX: V08.00
Enter specimen identity
Scanner ( No. 1 Chalnicon LV= 0.00 SENS= 1.94 PAUSE )
Load Shading Corrector ( pattern - CHRISl)
lS Calibrate User Specified (Cal Value = 0.01077 millimeters per
pixel for photos at 10.3X magnification)
~U~'l'~ STANDARD
lO~ LDS := O.
20 TOTAREA := O.
FRAMEPOSX := O.
XPOS = o.
FLDAREA := O.
INCRMNT := 30.
25 STARTPOS := 125.
X := O.
Y := O.
W :-- O.
H := O.
For FIELD
Detect 2D ( Lighter than 64, Delin )
Image Frame (Pause) is Rectangle ( X: 204, Y: 118, W: 489, H:
398, ) Choose a field much larger than "corrugation," to gi~e
room for 40 dilations.
22
CA 02222444 1997-12-18
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-
X := I.FRAME.X
~ := I.FRAME.Y
W := I.FRAM.WR
H := I.FRAME.H
5 Detect 2D ( Lighter than 24, Delin PAUSE )
i~dit (pause) EDIT get rid of neighboring "corrugation" pieces,
and rest,ore valley floor by DRAW of a LINE.
~end ( CLOSE by 40 )
Image Frame (Pause) is Rectangle ( X: 243, Y: 133, W: 415,
~I: 313, ) Place this frame accurately to bisect valley ~loors
on either side of "corrugation."
Live Frame is Rectangle ( X:X , Y:Y , W:W , H:H
,~ )
YPOS := I.FRAME.Y
15 INCRMNT := I.FRAM.WR / 20.
HEIGHT := I.FRAME.H
C~ARTPOS := I.FRAME.X
Edit (pause) EDIT Use EDIT/LINE to take slices (vertical) from
iilled "corrugation".
Measure feature AREA FERET 90 X.FCP Y. FCP
into array FEATURE ( of 200 features and 5 parameters )
FEATURE CALC := ( ( X.FCP = I.FRAME.X ) * CAL.CONST
)
I)istribution of FERET (Units MM -) v CALC (Units ~M
from FEATURE in HISTOl from 0. to 5.000
in 25 bins (LIN)
I)istribu,tion of COUNT v CALC (Units MM ) need this to
clivide 'HISTO1 class data by COUNT/CLASS in HIST02, for
obtainin,g per-class averages.
from FEATURE in HIST02 from 0. to 5.000
in 25 bins (LIN)
- TO~ ~LDS := lO~ LDS + l.
- 35 I'ause Message
23
CA 02222444 1997-12-18
W O 97/02133 PCTnUS96/10667
PLEASE CHOOSE ANOTHER FIELD, OR "FINISH"
Pause
Next FIELD
Print " "
Print " TOTAL NUMBER OF FIELDS SCANNED = " , lOlrl~LDS
Print " TOTAL AREA SCANNED (sq cm) = ", CL.FRAREA *
lOl~l~LDS / 100.
Print " "
Print "EACH FRAMEPOSX = 1l , L.FRAM.WR * CAL.CONST , "(mm)"
Print '
Print " ll
Print Distribution ( HISTOl, differential, bar chart, scale
= 0.00)
Print " "
Print " "
Print " "
20 For LOOPCOUNT = 1 to 20
Print " "
Next
Print " "
Print " "
Print Distribution ( HIST02, differential, bar chart, scale
0.00)
For LOOPCOUNT = 1 to 20
Print " "
Next
END OF PROGRAM
24
=
CA 02222444 1997-12-18
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EXAMPT.F~F;
F~ MpLE 1
In Example 1 a film~nonwoven laminate was made in accordance
with the above-described process shown in Figure 4. The base
film was a 1 mil (0.00254 centimeter) thick low density
polyethy:Lene film containing 4 percent by weight titanium
dioxide (TiO2) uniformly dispersed throughout the film. The
film polymer was NA-206 low density polyethylene (LDPE) from
Quantum, Inc. of Wallingford, Connecticut. The Tio2 was in
concentrclte form and was obtained from the Ampacet C~mp~ny of
Mount Vernon, New York and designated 110313. The film once
formed was mechanically apertured with approximately -25
percent open area. The individual apertures were
approxima~tely 550 microns in diameter (equivalent circular
d:iameter). After aperturing the film thi~.kn~cc was-
approximately 0.015 inches (0.0381 cm).
The compressible fibrous nonwoven web portion of the
laminate was a bicomponent spunbond web having a basis weight
of 34 grams per square meter (gsm). The fibers were of a
side-by-6ide construction with a fiber denier of 5 and a fiber
diameter of 28.2 microns. The f-ibers included 50 percent by
weight Exxon 3445 polypropylene from the Exxon Chemical
Company of Darien, Connecticut and 50 percent by weight Dow
grade 6811A polyethylene from the Dow Chemical Company of
Midland, Michigan. The web was through air bonded at a
temperature of 267-F (128-C) with a dwell time of less than
one second. ~he web was treated, on a dry weight basis, with
0.4 percent Y12488 polyalkylene oxide-modified
polydimethylsiloxane non-ionic surfactant wetting package
ba~ed UpOIl the total weight of the web. The surfactant was
~anufactured by OSi Specialties, Inc. of Danbury, Connectic~t.
The web had a thickness of 0.1524 cm. Such bicomponent webs
CA 02222444 l997-l2-l8
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can be-made in accordance with the teachings of U.S. Patent
No. 5,336,552 to Strack et al. which is incorporated herein
by reference in its entirety.
The film was fed into the bonding apparatus such that it
was adjacent the geared tooth bonding roll and was traveling
~t approximately the same speed as the geared tooth bonding
roll which had a rotational surface speed of 5 meters per
minute (m/min). The geared tooth bonding roll was not heated
but was at ambient temperature which was approximately 20-C.
The geared tooth bonding roll had a diameter of 6.173 inches
(15.7 cm) as measured from tooth apex to tooth apex. The
teeth had flat tops and vertical sides. The tooth width was
0.025 inches (0.635 mm). Vertical depth of the teeth waa
0.254 centimeters and the tooth-to-tooth spacing was 0.18
inches (4.57 mm) (center line to center line). The ultrasonic
horn assembly used in the bonding apparatus was manufactured-
by the Branson Ultrasonics Corporation of Danbury,
Connecticut. The horn itself was a nine inch (23 cm) horn
with a gold booster having a 1 to 1.5 gain ratio. The booster
w~s connected to a model 900 actuator which was in turn
connected to a model 900B 300 watt/20,000 Hz power supply.
For Example 1 the horn was adjusted to 50 percent output. The
nonwoven web was positioned adjacent the ultrasonic horn and
was fed into the bonding apparatus at a speed which was
approximately two thirds that of the bonding roll. As a
result, the nonwoven web was stretched approximately 50
percent before it was bonded to the film layer. After the
bonding step the laminate was withdrawn and allowed to relax
thereby causing the laminate to corrugate.
A cross-sectional side view of the laminate is shown in
Figure 11 of the Drawings. As can be seen from the photo of
Figure 11, the laminate has reduced skin contact area on the
film side due to the corrugation of the two materials. The
26
CA 02222444 1997-12-18
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overall height or thickness of the corrugations at their
highestl?oint averaged approximately 1.1 millimeters. Spacing
between adjacent apices was approximately 4.s millimeters and
t:he spac.ing between adjacent bond lines was approximately 4.5
5 millimeters. This corrugated effect is perceived as being
a.dvantag~eous as it should allow for more air circulation and
l.ess contact with the skin which is important especially when
the material is wet as with, for example, urine or menses.
on the nonwoven side of the laminate, the spacing between the
10 fibers is much more open with more interfiber spacing in the
a.rea ad~acent the apices of the corrugations. Conversely, the
fiber spacing in the areas of the fibrous nonwoven web to
either side of the bond lines is much closer thus creating a
h.igher dLensity fiber structure as compared to the above-
15 describe~ areas intermediate the bond lines. Consequently,the
n.onwoven side can be seen as having two density zones, a low
d.ensity zone at the apex of the corrugations approximately
intermed.iate two adjacent bond lines and a higher density zone
on either side of the bond lines. As a result, a density
20 differential is formed between the top of the corrugations and
the bottoms which also creates a pore size gradient which
fosters fluid flow away from the tops of the corrugations
which are most likely to be in closest proximity to the
wearer's skin and toward the bond lines which are typically
25 closer the additional absorbent material such as the absorbent
core of a personal care absorbent article.
Density measurements were taken of the laminate in
accordance with the test procedures outlined above. Midway
30 between the bond lines at the approximate apices of the
corrugat:Lons the density of the nonwoven web portion of the
laminat~ (it being assumed that there was little or no change
t in the dlQnsity of the film layer) was 0.023 grams per cubic
Centi~et:~!r (g/cc) while in the areas just adjacent the bond
~ 35 lines t~ density of the nonwoven was approximately 0.173 to
27
CA 02222444 1997-12-18
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0.236 g/cc based upon a ten sample average of the material of
Example 1. see Table 1. As is also shown in Table 1, there
is a gradual increase in density values from the apex in
either direction to the areas adjacent the bond lines.
CA 02222444 l997-l2-l8
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TABLE 1
~XAMPr~ 1 EXAMPT~ 2
Density Density
g/cc ~/cc
Area ad~acent bond line 0.291 0.200
0.173 0.090
0.070 0.047
0.047 0.032
0.035 0.027
0.030 0.022
0.029 0.019
0.027 0.019
0.026 0.017
0.025 0.018
0.02S 0.018
A~pex 0.024 0.017
0.026 0.019
0.025 0.022
0.028 0.026
0.029 0.031
0.032 0.038
0.044 0.048
0.057 0.096
0.108 0.125
0.236 0.150
Area adjacen~ bond line 0.358 0.351
CA 02222444 1997-12-18
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Pore-size measurement were also taken of the laminate in
accordance with the test procedures outlined above. Midway
between the bond lines at the approximate apices of the
corrugations the pore size of the nonwoven web portion of the
laminate was approximately 0.65 mm in size while in the areas
just adjacent the bond lines the density was approximately
0.21 to 0.29 mm based upon a ten sample average of the
material in Example 1. See Table 2.
CA 02222444 1997-12-18
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TABLE 2
EXAMPLE 1 ~Mpr ~ 2
Pore Size Pore Size
mm mm
A.rea adjacent bond l ine 0 . 29 0 . 26
0.57 0.49
0.41 0.62
0.52 0.94
0.63 0.78
0.62 0.91
0.61 0.85
0.69 0.87
0.62 0.82
Apex 0 . 65 0. 98
0.67 0.78
0 . 59 0 . 99
0.76 0.94
0.59 0.90
0.49 0.66
0.62 0. 56
0.41 0.56
Area adjacent bond line0.21 0.31
CA 02222444 l997-l2-l8
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. .
The film nonwoven laminate of this example was tested for
fluid handling performance using the intake time and rewet
tests described above. Swa~ches of the laminate were cut and
placed on top of a two layer absorbent core with the nonwoven
side adjacent the absorbent to simulate the cover material of
a personal care absorbent article, in this case a fem; n; ne pad
or sanitary napkin. on the back side of the pad there was
placed a layer of thermoplastic film. The top body side layer
of the core was a 425 gsm fluff with a density of
approximately 0.07 g/cc and the baffle side layer wa~ a 470
gsm fluff with a density of approximately 0.094 g/cc. The
baffle side layer was embossed with an acorn pattern.
The fluid handling performance of the laminate material was
compared to the identical components in a layered or
nonlaminated state. Thus the nonwoven and apertured film were
separately cut and layered on top of the two layer absorbent
core with the nonwoven material placed adjacent the absorbent
core.
The laminate and layered cover material samples were tested
for fluid intake time and rewet using the synthetic menstrual
fluid described above. The resu-lts of the testing are given
in Table 3 below:
TABLE 3
Intake time Rewet Thickness
(sec) (g) (mm)
Corrugated film/NW 11.47 0.25 1.63
Layered film/NW 12.38 0.56 1.19
32
CA 02222444 l997-l2-l8
~0 97/02133 PC~US96~0C67
,.
As is-readily apparent from the data presented above, the
corrugated laminate material according to the present
invention had an improved intake time and significantly
re!du~ed rewet compared to the identical layered structure.
ThLus, the fluid was absorbed into the f~m;~ine pad faster with
less fluid rewet to the surface. This decreased rewet is
believed 1_o be due in part to the increased separation between
the user and fluid absorbed in the absorbent core caused by
the corrugations as can be seen from the significantly
increased thickness of the corrugated laminate. The decreased
rewet is also believed to be due to the density gradient that
is createcl within each corrugation that transports and retains
the ~luid away from the user, thus allowing less fluid to
rewet the surface.
~MPLE 2
In Example 2 a nonwoven/nonwoven laminate was made in the
same manner and under the same conditions as the material in
Example 1. The only difference was that the film layer was
~eplaced with a 14 gram per square meter spunbond
polypropylene web containing 4 percent by weight Tio2~ based
upon the total weight of the fiber/web. The polypropylene
resin was designated E5D47 and was obtained from the Shell
Chemical Company. The TiO2 was obtained from the same
supplier as in Example 1 and bore the designation 41438. The
i-ibers from which the web were formed had a denier of 5 and
a diameter of 28.2 microns. The web was thermally point
bonded wit:h an approximate bond area of 15 percent. The bond
pa-ttern consisted of a staggered row of diamond shaped bond
points ha,ving equal length sides with a bond area of
approximat:ely 0.009 sc~are inches (0.058 cm2). The web was
t:reated on a dry weight basis based upon the total weight of
t:he web with 0.5 percent Triton X-102 nonionic surfactant
from the Union Carbide Company of Sisterville Virginia.
33
CA 02222444 l997-l2-l8
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The other nonwoven web was the same bicomponent spunbond
web used in Example 1. The two webs were fed into the
appa~atus in the same manner in Example 1 with the 14 gs~
polypropylene spunbond web adjacent the geared tooth bonding
roll and the ultrasonic horn set at 60 percent power. The
resultant laminate in shown in cross-section in the photograph
of Figure 8 of the drawings. The overall height of the
corrugations at their highest point averaged approximately 2
millimeters. Spacing between adjacent apices was
approximately 4 millimeters and the spacing between adjacent
bond lines was approximately 4 millimeters. Once again, this
corrugated effect is perceived as being advantageous as it
should allow for more air circulation and less contact with
the skin. As with the laminate in Example 1 the spacing
between the fibers was much more open with more interfibèr
spacing in the areas adjacent the apices of the corrugations.
Conversely, the fiber spacing in the areas of the fibrous
nonwoven web to either side of the bond lines was much closer
thus creating a higher density fiber structure as c- ~red to
the above-described areas intermediate the bond lines.
Conse~uently,the laminate can be seen as having two density
zones, a low density zone at the apex of the corrugations
approximately intermediate two adjacent bond sites and a
higher density zone on either side of the bond lines. As a
result, a density differential is formed between the top of
the corrugations and the bottoms which also creates a pore
size gra~ient which fosters fluid flow away from the tops of
the corrugations which are most likely to be in closest
proximity to the wearer's skin and toward the bond lines which
are typically closer the additional absorbent material such
as the absorbent core of a personal care absorbent article.
Density measurements were taken of the laminates in
accordance with the test procedures outlined above and are
34
CA 02222444 1997-12-18
W 097/02133 PCT~US96/10667
reported in Table 1. Midway between the bond lines at the
approximate apices of the corrugations the density of the
laminate was 0.017 grams per cubic centimeter (g/cc) while in
the -areas just adjacent the bond lines the density of the
la~minate was approximately 0-15 to 0.20 g/cc based upon a ten
sa~mple average of the material of Example 2.
..
Pore size measurement were also taken of the laminate in
ac:cordance with the test procedures outlined above. Midway
between t:he bond lines at the approximate apices of the
corruLgations the pore size of the laminate was approximately
0.98 mm i.n size while in the areas just adjacent the bond
li.nes the pore size was approximately 0.26 to 0.31 mm based
upon a ten sample average of the material in Example 2. See
TaLble 2 above.
CA 02222444 l997-l2-l8
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The nonwoven/nonwoven laminate of this example was tested
for $1uid handling performance using the intake time and rewet
tests described above. The laminate materials were prepared
and tested similarly to the procedure described in Example 1.
As in Example 1 the bicomponent spunbond web was placed
ad~acent the absorbent core. The fluid handling performance
of the laminate material was compared relatively to the
identical material components in a layered or nonlaminated
state. Thus each nonwoven material was separately cut and
layered on top of the two layer absorbent core with the
bicomponent spunbond material placed adjacent the absorbent
core. The results of the testing are given in the Table 4
below:
TABT~ 4
Intake time Rewet ~h;~bYxc
(sec) (g) (mm)
Corrugated NW/NW 9.05 0.42 1.24
Layered NW/NW 15.90 0.87 1.19
As in Example 1, the corrugated laminate material had a
improved intake time and significantly reduced rewet value,
again demonstrating the positive effect of the corrugations
on fast fluid intake and reduced rewet. Unlike Example 1, the
significant rewet reduction was achieved without a
corresponding significant increase in thickness. This is
believed to demonstrate the importance of the density gradient
imparted in the bicomponent nonwoven web that transports fluid
36
CA 02222444 l997-l2-l8
W 0'97/02133 PCT~US96~10C67
~way from the user and towards the absorbent core which
enhances the separation between the body side surface and
absorbent and minimizes fluid rewet.
As can be seen from the examples described above, the
ccrrugate~ laminates have improved fluid intake and rewet
performance compared to identical noncorrugated materials.
Th.is is believed to correlate with the desirable in-use
be!nefits of faster menses absorption and a drier feeling
surface. The corrugations are important to these in-use
be!nefits as they increase the separation between the user and
th~e fluid in the absorbent core and minimize the amount of
ma~terial in contact with the user. In addition, the density
di.fferential and resulting pore size differential between the
top and bottom of the corrugations provide the user with a
sanitary napkin that readily absorbs menses and maintains a
c3.ean and dry feeling body side surface.
Having thus described the invention in detail, it should be
apparent that various modifications and changes can be made
in the pr~esent invention without departing from the spirit and
scope of the following claims.
