Note: Descriptions are shown in the official language in which they were submitted.
CA 02321418 2000-07-26
- 1 -
TITLES HIGHLY -AB50RBEN? AHD FLEBIBLE CELLULOSIC PULP
FLUt° SHEET
FIELD OF THE INVENTION
The invention relates to the general field of fluid
absorbing products and, more particularly, to a highly
absorbent and flexible pulp sheet. More specifically, the
flexible and absorbent sheet is a densified and
mechanically worked cellulosic pulp fluff material which
has a high structural integrity and provides a soft, thin
and flexible fluid absorbent core having good Wicking
characteristics, well-suited for use in disposable
absorbent products such as sanitary napkins, wound
dressings, bandages, incontinence pads, disposable diapers
and the like. The invention also provides a aethod of
preparing such highly absorbent and flexible cellulosic
pulp fluff sheet and its method of use in disposable
absorbent products.
BACKGROUND OF THE INVENTION
Many disposable absorbent articles use pulp fluff
m~rorial » trc absorbent core. Such cores are generally
soft, flexible and absorbent but tend to be bulky and
thick and have poor wicking properties. In addition, pulp
CA 02321418 2000-07-26
_ 2 _
fluff cores have poor structural stability, prone to
collapsing when wet.
An absorbent structure that has poor wicking
properties may increase the likelihood of failure of the
absorbent product to hold and contain body fluids. Body
fluids will be localized to a certain area of a poorly
wicking absorbent core, causing saturation in such area
whereby excess fluid may overflow through an external
surface of the absorbent product. This overflow may
contact the user's garment and cause stains or contact the
user's body and cause wet discomfort or rash. It is
therefore desirable to provide an absorbent core for
disposable absorbent articles which can wick away body
fluids from the point of contact with the absorbent core
and spread it through the absorbent core to pore
efficiently utilize the entire surface area of the
absorbent core. The improved wicking properties of such
an absorbent core provide the capacity for fluids to
travel by capillary action throughout the surface area of
the absorbent core and thus permit the use of thinner
cores, since more absorbent surface area can be made
available for absorbing body fluids by such wicking
action. Thinner absorbent cores :~;y prove to be more
comfortable for the user and less unsightly or obvious
when worn under clothes.
CA 02321418 2000-07-26
- 3 -
Absorbent cores with excellent wicking properties
comr:ising .eat moss and wood pulp composite materials are
described, for example, in U.S. patents, numbers
4,170,515= 4,226,237; 4,215,692; 4,507,112; 4,676,871; and
4,4.73,440. In accordance with the teaching of these
patents, an absorbent structure comprising peat moss as a
primary absorbent component is formed as a sheet by air or
wet laying of fibers and calendering the sheet to obtain
a relatively thin, i.e, from about 0.01 to 0.1 inch thick,
a relatively dense, i. e. from about 0. 2 to 1.0 gram per
cubic centimeter (g/cc) structure. Such absorbent peat
moss sheets may be processed to increase their flexibility
by subjecting the sheets to mechanical tenderizing such as
perf-embossing as described in U.S. patent number
4,596,567 or microcorrugating as described in U.S. patent
number 4,605,402.
The peat moss sheets thus formed have a large
proportion of extremely tiny pores and capillaries which
give them the ability to absorb and retain an enormous
capacity of fluid. The peat moss pores swell as they
absorb fluid, however, this swelling does not cause a loss
of capacity for further absorbing fluid. Rather, the
swelling contributes to the ability of thp sheer t~ rc~nin
fluid while generally maintaining the structural integrity
of the absorbent structure in use.
CA 02321418 2004-04-16
-4-
The wicking properties of the above-described peat moss sheets
provide the ability for the sheets to be highly absorbent and thin.
The flexibility of peat moss sheets may be improved by perf-embossing
and/or micro-corrugating as described above.
while peat moss sheets make excellent absorbent and wicking
cores for disposable absorbent articles. They have limitations. Peat
moss sheets may not be readily available particularly in areas which
lack the critical raw materials, i.e. peat moss or sphagnum moss of
desirable age, structure and moisture content. Peat moss sheets also
are relatively dark in color and may not be aesthetically acceptable
for use in all absorbent products.
Having regard to the foregoing, it is desirable to provide a
thin, absorbent and wicking core for disposable absorbent articles
which may be substituted for peat moss sheets or pulp fluff sheets.
Attempts to utilize other cellulosic pulp materials such as
kraft wood pulp boards as absorbent cores have not been successful
because they tend not to have as much absorbent capacity as peat moss
composite sheets but more importantly kraft wood pulp boards cannot
be sufficiently softened for their intended use. While the
flexibility
CA 02321418 2000-07-26
and other characteristics of such Kraft wood pulp boards
~:.si bE i;;.yo~ed by pprf-embossing and/or ~~icrocor=i~gating
techniques, such products still do not provide a desirable
combination of absorption capacity and fluid penetration,
wicking rates and most importantly a sufficient degree of
flexibility for .optimal use in disposable .absorbent
products, particularly sanitary napkins.
OBJECTS AND STATEHENT OF THE IHVgNTION
It is, therefore, an object of the present invention
to provide a cellulosic pulp fluff sheet which does not
utilize peat moss in its structure but has sufficient
absorption capacity, good wicking characteristics as well
as a relatively short fluid penetration time, and
possessing good flexibility for use in disposable
absorbent articles. Optimal flexibility of such products
requires that the product be comfortably soft and flexible
to the wearer but stiff and strong enough to withstand
bunching and breakage when subjected to mechanical stress
in a dry and a wet state.
Another object of the invention is a method for
manufacturing such a ce~lulosic pulp fluff sheet.
CA 02321418 2000-07-26
- 6 -
Yet, another object of the invention is to providq a
disposarle absoi~bec~t Nroducc wnieh uses ~~:ch a r.ellulosic
pulp fluff sheet as an absorbent core.
The present inventors have discovered that When
conventional cellulosic pulp fluff material is densified
by mechanical compression, such as calendering, and
subsequently embossed, a highly absorbent and flexible
sheet is obtained, having exceptionally good wicking
characteristics. The improvement in the wicking
properties is a direct result of the embossing process
which selectively compacts the densified cellulosic pulp
fluff material imparting a fiber density profile of
alternating high and low fiber density zones. (For the
purpose of this specification, the terms "high fiber
density zones" and "low fiber density zones" should be
construed in a relative manner indicating that one zone
has a higher fiber density than the other, without
reference to the absolute density values of the zones).
The high fiber density zones have the ability to disperse
fluid throughout the entire surface of the absorbent sheet
by virtue of excellent wicking properties, establishing a
network of capillary-action channels interconnecting the
low fiber density zones which have the task of Permanently
absorbing and retaining the fluid. When a fluid mass is
released on a certain point of the absorbent sheet, the
fluid will rapidly penetrate the low fiber density zones
CA 02321418 2000-07-26
-
immediately underneath the fluid impact point. Local
overflow is avoided by the wicking puwe~ of the high fiber
density zones which transfer fluid from saturated to non-
satura~~ed low fiber density zones, thus spreading the
fluid throughout a larger absorbent volume.
In addition to the above, the embossing process also
increases the flexibility of the densified pulp fluff
material. The selective compaction creates hinges
permitting the absorbent sheet to become more pliable and
compliant.
The densification step of the cellulosic pulp fluff
material, prior to the embossing stage, is an important
aspect of the invention because it increases the cohesion
of the fibrous web, with a resultant increase in
structural stability. With regard to the fluid absorption
characteristics, the densification has the effect of
increasing the capability of the fibrous material to
prevent absorbed fluid to escape. In contrast, untreated
pulp fluff does not have the ability to lock in and retain
absorbed fluid due to the large voids present in the
fibrous network and a leak-through failure can occur.
when fluid is discharged on the densified and embossed
cellulosic pulp fluff sheet, the fluid mass is absorbed in
low fiber density zones which, by virtue of the
improvement in the fluid retention characteristics, can
CA 02321418 2000-07-26
_ g _
hold the fluid for a sufficiently long period of time to
allot: ;.:;~ fluid to he pulled throughout the ansoroenL
sheet by the wicking high fiber density zones.
Objectively, the densification Will increase to sore
degree the fluid penetration time over untreated pulp
fluff, however, on balance an overall gain in efficiency
is observed due to the improvement in fluid retention and
structural stability.
While it is known in the art of manufacturing
absorbent products to process peat moss by calendering and
embossing, the objective of such treatment is solely to
selectively crush the peat moss structure to improve its
comfort factor. In contrast, the inventors have found
that when this process is applied to pulp fluff,
surprisingly, a considerable improvement in the fluid
absorption characteristics is obtained, doubled by an
incaease in the structural stability of the pulp fluff
material.
In a preferred embodiment, the desired fiber density
profile of the densified cellulosic pulp fluff sheet is
obtained by a perf-embossing process which has the
advantage over embossing alone, to selectively perforate
the pulp fluff sheet, opening-up its structure for an
CA 02321418 2000-07-26
_.
g _
increase in flexibility and also creating vertical
channel:, ~.~.r~4nci;~g fluid absorption ir_ the Z axis.
Accordingly, the invention provides a c~~llulosic pulp
fluff absorbent sheet which has the combined desirable
advantages of rapid fluid penetration, high absorption
capacity, excellent wickability characteristics such that
fluid is transported via capillary action throughout the
surface area to make efficient use of the available fluid
absorption surface of the sheet, also possessing good
drying power and an excellent structural stability.
The densified and embossed cellulosic pulp fluff
sheet according to the invention is well-suited as an
absorbent core for disposable absorbent products such as
sanitary napkins, wound dressings, bandages, incontinence
pads, disposable diapers and the like. When incorporated
in a sanitary napkin for example, it is sufficiently
flexible to be worn comfortably and at the same time, it
has a sufficient structural integrity to prevent bunching
and breakage when subjected to mechanical stress in the
dry or in the wet state.
In preferred embodiments of the invention, the dry
thickness of the densified and embossed cellulosic pulp
fluff sheet is in the range of about 0.075 to 0.20 inches
measured at 0.05 pounds per square inch (psi) pressure,
CA 02321418 2000-07-26
- 10 -
preferably in the range of about 0.09 to 0.15 inches at
0.~5 psi pressm.e. the dry tensile strength of the
densified and embossed cellulosic pulp fluff sheet is
at least of about 1 pound per inch (lbs/inch) in the
machine direction and more preferably at least of about 2
lbs/in. in the machine direction. The density of the
densified and embossed cellulosic pulp fluff sheet is in
the range of about 0.1 to 0.3 grams per cubic centimeter
(g/cc) and more preferably of about 0.2 to 0.25 g/cc, and
its absorbent capacity is at least of about 4 cubic
centimeters per gram (cc/g) and more preferably of about
6 cc/g.
The preferred cellulosic pulp fluff starting material
utilized in accordance with the invention is a sulfate,
sulfite or Kraft wood pulp, but other cellulosic pulps may
be used, such as, for example, debonded pulp, unbleached
wood pulp or wood pulp bleached by chlorine processes or
hydrogen peroxide, and chemical thermal mechanical pulp.
As embodied and broadly described herein, the
invention further comprises a disposable absorbent product
having an absorbent core with good wicking and absorption
characteristics comprising the flexible ab.:o~bent
densified and embossed cellulosic pulp fluff sheet which
is sufficiently pliable and compliant to be comfortably
worn by the wearer of the disposable absorbent product.
CA 02321418 2000-07-26
- 11 -
In preferred embodiments of the invention, the disposable
atscrbent pr~~iur,t iR selected from the grcup consisting
sanitary napkins, incontinence products, diapers, and
wound dressings. In a more preferred embodiment of the
invention, a thin, absorbent and flexible sanitary napkin
is provided which has an improved absorbent core
comprising a calendered and a perf-embossed cellulosic
pulp fluff sheet. In a most preferred embodiment of the
invention the absorbent core is of optimal flexibility to
be comfortable to the product wearer but stiff enough to
substantially retain its original shape in use or after
wetting.
As embodied and broadly described herein, the
invention further comprises a method of preparing a highly
absorbent and flexible cellulosic pulp fluff sheet,
comprising the steps of:
a) forming a densified pulp fluff sheet by
mechanically compressing cellulosic pulp fluff material;
and
b) embossing the densified pulp fluff sheet of step
(a) to impart the densified pulp fluff sheet with a fiber
density profile exhibiting alternating high and low fiber
density zones, while impressing a multitude of hinge areas
for reducing the stiffness of the pulp fluff sheet.
CA 02321418 2000-07-26
'~t
- 12 -
In a preferred embodiment, the density of the
~s~e ~o~~,:al~y cumpr~s5ed cellu~e~ic ylp fluff sheet of
step (a) has a density in the range of about 0.?.5 to 0.55
g/cc and more preferably in the range of about 0.35 to
0.50 g/cc, and a dry thickness in the range of about 0.03
to 0.07 inches measured at 0.05 psi pressure and more
preferably of about 0.04 to 0.06 inches measured at 0.05
psi pressure.
As embodied and broadly described herein, the
invention further comprises a method of providing good
fluid absorption in a thin and comfortable sanitary napkin
comprising the step of incorporating as an absorbent core
in the sanitary napkin, a densified and embossed
cellulosic pulp fluff sheet. In a preferred embodiment,
the absorbent core has a dry thickness in the range of
about 0.075 to 0.2 inches measured at 0.05 psi pressure,
and more preferably in the range of about 0.09 to 0.15
inches at 0.05 psi pressure, an absorbent capacity
approximately of at least 4 cc/g, more preferably of at
about 6 cc/g, a density in the range of about 0.1 to 0.3
g/cc and more preferably in the range of about 0.2 to 0.25
g/cc, a lateral flexibility in the dry state in the range
of about 700 to 1700 grams (g) and preferably in the range
of about 1100 to 1900 g, a lateral flexibility in the wet
state in the range of about 550 to 950 g, and a dry
tensive strength in the machine direction of at least
CA 02321418 2005-07-11
-13 -
about 1 lb/inch and more preferably of at least about 2
lbs/inch.
As embodied and broadly described herein, the invention
further comprises a method of manufacturing a highly
absorbent and flexible article, comprising the steps of
uniformly densifying a cellulosic pulp fluff sheet by
mechanical compression, and embossing the densified
cellulosic pulp fluff sheet to impart thereto a fiber
density profile of alternating high fiber density and low
fiber density zones while impressing hinge areas for
increasing the flexibility of the densified cellulosic
pulp fluff sheet.
As embodied and broadly described herein, the invention
further comprises a method of manufacturing a highly
absorbent and flexible article, comprising the steps of
uniformly densifying a cellulosic pulp fluff sheet by
mechanical compression, and selectively compacting the
densified cellulosic pulp fluff sheet to impart thereto a
fiber density profile of alternating high fiber density
and low fiber density zones while impressing hinge areas
for increasing a flexibility of the densified cellulosic
pulp fluff sheet.
As embodied and broadly described herein, the invention
further comprises a method of manufacturing a thin and
comfortable sanitary napkin comprising the step of
incorporating as an absorbent and wicking core in a
sanitary napkin a calendered and perf-embossed cellulosic
pulp fluff sheet of a dry thickness of about 0.075 to 0.2
inches measured at 0.05 pounds per square inch pressure,
CA 02321418 2005-07-11
, ~ ,., .
' ' ' ' -13A-
a density of about 0.1 to 0.3 grams per cubic centimeter,
and an absorbent capacity at least of about 4 cubic
centimeters per gram.
BRIEF DESCRIPTION OF THE DRAWINGS
- Figure 1 is a graphic illustration of the process
for manufacturing the densified and perf-embossed
cellulosic pulp fluff sheet according to the invention;
- Figure 2 is a vertical cross-sectional view of the
perforation rolls which constitute the first stage of the
perf-embossing treatment;
- Figure 3 is a fragmentary front elevational view of
the perforation rolls shown in Figure 2, the web of
densified cellulosic pulp fluff to be treated being
omitted for illustrating the interrelation between the
perforation teeth on the rolls;
- Figure 4 is an enlarged top view of the densified
cellulosic pulp fluff web treated by the perforation
rolls shown in Figures 2 and 3, illustrating the web
topography resulting from the interaction of the
perforation teeth;
- Figure 5 is a sectional view taken along lines 5-5
in Figure 4;
CA 02321418 2000-07-26
- 14 -
- Figure 6 is a vertical cross-sectional view of the
cross-di.reccion embossing rolls wr~cn wm~iLULe the
second stage of the perf-embossing treatment;
- Figure 7 is a top view of one of the cross-
direction embossing roll, also showing the. resulting
embossing pattern created on the cellulosic pulp fluff
web;
- Figure 8 is a vertical cross-sectional view of the
machine-direction embossing rolls which constitute the
third and last stage of the perf-embossing treatment;
- Figure 9 is a top view of one of the machine-
direction embossing rolls, also showing the resulting
embossing pattern created on the cellulosic pulp fluff
web;
- Figure 10 is an enlarged perspective view of the
cellulosic pulp fluff sheet structure resulting from the
perf-embossing treatment;
- Figure 11 is a perspective fragmentary view of a
sanitary napkin according to the invention, the absorbent
core thereof being partially exposed;
CA 02321418 2000-07-26
- 15 -
- Figure 12 is a perspective view of a set-up for
c;,r.;:uc;.l;~g a L1U14 penetrat~cn rive test procedure;
- Figure 13 is a perspective view of a set-up for
conducting a 45° impact capacity test procedure;
- Figure 14 is a perspective view of a set-up for
conducting a fluid capacity and collapse test procedure;
- Figure 1S is a perspective view of an apparatus for
conducting an inclined plane wicking test procedure;
- Figure 16 is a perspective view of an apparatus for
conducting a lateral stability/flexibility test procedure;
- Figure 17 is a graph of fluid wicking and uptake
versus time for unprocessed cellulosic pulp fluff; and
- Figure 18 is a graph of fluid wicking and uptake
versus time for calendered and perf-embossed cellulosic
pulp fluff according to the invention.
DESCRIPTION OF PREFERRED EHBODIHENTS
Reference will now be made in detail to preferred
embodiments of the invention, examples of which are
illustrated in the following example sections.
' CA 02321418 2000-07-26
- 16 -
To achieve the object of the invention of providing
a highly abserbc:,t, flexible dr~d good wickt~h core for
disposable absorbent products which may be an economical
and suitable replacement for peat moss composite sheets o-
unprocessed cellulosic pulp fluff sheets, the present
inventors have made the unexpected discovery that
cellulosic pulp fluff material, particularly wood pulp
fluff, which when densified by mechanical compression,
such as calendering for example, and subsequently
.0 embossed, by perf-embossing for example, to impart a
pattern of alternating high fiber density and low fiber
density zones, will provide a flexible, highly absorbent
and wicking core possessing a high structural integrity.
Figure 1 graphically depicts a highly preferred
embodiment of the method for providing the highly
absorbent and flexible densified and embossed cellulosic
pulp fluff sheet according to the invention. A
commercially available pulp board 10 in a continuous sheet
form is subjected to mechanical defiberization and
maceration in a grinding mill 12 to produce a pulp fluff
web 14. This step is not an essential aspect of the
invention because the method of producing pulp fluff
material is well-known in the art of constructing fluid
absorbent structures. In addition, pulp fluff being a
commercially available product itself, the on-site
production of the pulp fluff web is not a necessity.
CA 02321418 2000-07-26
- 17 -
The pulp fluff web 14 is subjected to a two-stage
cap endering process to uniforoal~- cos,rress and density th s
web creatic~g a network of randomly oriented fibers which
has a superior resistance, preventing loss of integrity
under the effect of mechanical stress applied during
subsequent treatments, and providing. a good structural
stability to the finished product. In addition, the
densification also enhances the ability of the fibrous web
to retain fluid within the fibrous network, due to a
reduction of inter-fiber distances, as it will be
discussed hereinafter.
The first stage of the calendering station includes
a pair of compression rolls 16 and 18 forming a nip
through which the pulp fluff web 14 is passed. The
calendering pressure at the first stage is. not critical
because the primary objective is to stabilize the web
thickness, not to impart a precise density to the web.
Accordingly, a wide range of pressures are possible
without significantly affecting the properties of the
final product. For practical purposes, a relatively low
pressure in the order of 10 to 50 pounds per linear inch
(pli) is used because inexpensive small capacity
calendering equipment is adequate to perform this
operation.
CA 02321418 2000-07-26
E
- 18
The slightly densified pulp fluff web 20 obtained at
i~rst s~a5e of the ~~lc:n~3e:ing process is subjected io
a second stage mechanical compression achieved by a set
up essentially identical to tha;. used at the first stage,
except the calendering pressure is much higher,
approximately in the range of about 200 to 1300 pli,
preferably in the range of about 300 to 800 pli, and most
preferably in the range of about 900-500 pli, and the
thickness of the pulp fluff web 20 passing through the
l0 second stage nip is doubled to achieve a higher basis
weight product. A double layer web is achieved by feeding
simultaneously with the pulp fluff web 20 a web 20' having
identical characteristics.
By using a multi-stage calendering station and by
increasing, between the stages, the thickness of the
processed pulp fluff web a relatively high basis weight
material can be obtained without the necessity of
providing a large capacity calendering station operating
at high pressures. Although it may be envisaged to use a
single stage calendering station, in addition to the high
calendering pressure required, the basis weight of the
pulp fluff web 14 must also be increased which may present
some handling problems because the web becomes bulky.
The double layer compressed pulp fluff web leaving
the calendering station is fed to a perf-embossing station
CA 02321418 2000-07-26
- 19 -
designated comprehensively by the reference numeral 22.
The pe_i-rmbo~sing tecnnique first perforates the
densified pulp fluff web, then sequentially embosses the
resulting material in the Y (cross-direction) snd X
(machine direction).
The "PERF" operation (first step), best illustrated
in Figures 2, 3, 4 and S, is performed by passing the web
between a pair of rolls 24 and 26 provided with
intermeshing and non-contacting teeth 28 perforating the
web by shearing action mainly to open the structure of the
cellulosic material to reduce its stiffness, while
densifying other regions of the web.
Figures 3, 4 and 5 illustrate well the selective
treatment of the pulp fluff web as a result of the
interaction between the teeth 28. The teeth 28 on the
companion rolls 24,26 are so arranged that tooth 28a on
top roll 24 is off-center the inter-teeth void defined
between adjacent and axially aligned teeth 28b and 28c.
The shearing action actually occurs between teeth 28a,28c
during intermeshing, locally perforating the fibrous web
20.
The rolls 24 and 26 in addition to shearing locally
the web 20, also somewhat compress and further densify the
pulp fluff material. Such compression occurs between the
CA 02321418 2000-07-26
i.
- 20 -
flat top surface of each tooth 28 and the smooth arcuate
svrfa~e 29 of the npposit~ roll fa.:iu5 ~l~e tuuth curing
intermeshing. In practice, such selective compression
does n«t significantly alter the characteristics of the
final product. If it is desired to avoid it completely,
it suffices to increase the teeth height, allowing to
increase the gap between rolls 24,26 without affecting the
shearing action.
The above can be better visualized by examining the
structure of the pulp fluff web after treatment by the
perforation rolls 24 and 26. The imprints of teeth 28 are
identified by the same numerals used to designate the
teeth, followed by a " ' ". The imprints 28a' and 28c'
are separated by a slit 31 extending entirely throughout
the pulp fluff web resulting from the shearing action of
the teeth 28a and 28c.
In a preferred embodiment, interference i.e. overlap
between the teeth 28 of the perforating rolls 24 and 26 is
set at approximately 35 thousandths of an inch (mils).
This setting may vary according to the web thickness,
humidity and other factors.
The second step of the perf-embossing operation
consists of embossing the perforated pulp fluff web in the
cross-direction by passing the pulp fluff web between a
CA 02321418 2000-07-26
- 21 -
pair of rolls 30,32 with intermeshing longitudinally
e~~.e:.dvr.5 flutes 34. Figures 6 and 7- best i? :;~sWate i.ne
cross-direction embossing rolls 30 and 32 and the
tridimensional structure imFarted to the pulp fluff web.
The flutes 34 imprint lines 35 on each surface of the pulp
fluff web by locally compacting the fibrous material under
the effect of mechanical compression.
It will be appreciated that the cross-direction
embossing rolls alter the structure of the pulp fluff web
in two significant aspects. Firstly, the lines 35 form
miniature hinges extending transversely to the pulp fluff
web increasing its flexibility in the longitudinal
direction. Secondly, the fiber density in the vicinity of
the lines 35 is increased by virtue of the mechanical
compaction necessary to form the impressions. As a
result, a distinct fiber density profile is imparted to
the pulp fluff web, consisting of high and low fiber
density zones alternating in the machine direction. A
desirable consequence of the achieved variable fiber
density, as it will be discussed in more detail
hereinafter, is a selective alteration of the fluid
absorption characteristics of the pulp fluff web, creating
spaced apart high density, relatively non-absorbent areas,
providing a fluid wicking action in a transverse direction
to the pulp fluff web.
CA 02321418 2000-07-26
_ 22 _
In a preferred embodiment, the interference, i.e.
OVe~"~a~: i.~c:i..:s:cv iiutE~ JY VV the ?'C'1~.5 .~0,.~2 iS Sbt at
approximately 5 mils. This setting may vary according to
the specific operating conditions.
The last step of the perf-embossing operation
consists in embossing the resultant material in the
machine direction by passing the web bet~~ieen parallel
rolls 36, 38 having r_ircumferentially extending and
intermeshing flutes 40, as best shown in Figures 8 and 9.
This means a perpendicular impact to the second step
operation, creating longitudinal lines 41 to now impart a
fiber density profile of alternating high and low fiber
density areas in a transverse direction of the pulp fluff
web as well as providing longitudinal hinge lines.
In a preferred embodiment, the interference between
the machine direction embossing rolls 36,38 is set at 5
mils. This setting may vary according to the specific
operating conditions.
The perf-embossing process increases the dimension of
the pulp fluff web in the cross-direction by about 5 to
7'
a.
The final structure of the cellulosic pulp fluff
sheet, after being calendered and perf-embossed, is shown
CA 02321418 2000-07-26
- 23 -
in Figure 10. The entire surface of the pulp fluff sheet
exhibits a pattern of s.~uarE 1~;~ filer ciCosi~~- zones =3
which are separated from one another by longitudinal and
transverse lines 41 and 35 respectively. Slits 31 created
at the first stage of the perf-embossing treatment are
uniformly dispersed throughout the pulp fluff sheet.
From the stand point of fluid absorbency, this
structure is particularly advantageous because it combines
desirable characteristics, such as superior wicking power,
high absorbency and a rapid fluid absorption rate. Fluid
discharged on the pulp fluff sheet will penetrate the low
fiber density zones 43 immediately underneath the fluid
impact point, possibly causing local saturation. However,
leak-through failure of the absorbent structure is
unlikely to occur by virtue of an improved tolerance to
local saturation resulting from the densification of the
fibrous network by the calendering process. The
densification provides a superior fluid retaining ability,
whereby absorbed fluid is captured and held during a
sufficient period of time to allow the high fiber density
zones to pull and disperse the fluid within the cellulosic
pulp fluff sheet by capillary action. In similar
conditions, pulp fluff material which has been embossed
without being previously densified may not work as well
because the low f fiber density zones have a limited ability
to lock in and retain absorbed fluid and a leak-through
CA 02321418 2000-07-26
_ 2q
failure may occur before the fluid has been dispersed by
,. ; g
:.~,..,_n act.i n.
Fluid penetration within the pulp fluff sheet is
enhanced by the slits 31, forming channels in the Z axis
of the sheet promoting a faster fluid absorption.
The perf-embossing treatment also contributes to
provide desirable mechanical properties to the cellulosic
pulp fluff sheet, such as an increased flexibility
enhancing the comfort potential of the product. The slits
31 contribute to open-up the fibrous structure at precise
locations, thus locally disrupting fiber bonds to render
the material more pliable. The lines 35 and 41 constitute
miniature hinges, extending throughout the entire surface
of the cellulosic pulp fluff sheet to render the material
compliant in a transverse and in a longitudinal direction.
The increased flexibility of the cellulosic pulp
fluff material achieved by the perf-embossing process is
important to provide an absorbent core in a sanitary
napkin for example, which is comfortable to the wearer and
can conform to various body shapes and movements in use.
The optimal flexibility achieved in accordance with the
invention provides an absorbent sheet that is flexible
enough to meet the comfort criteria but stiff enough to
resist product bunching and deforming in use and/or upon
CA 02321418 2000-07-26
- 25 -
wetting. Such optimal flexibility and strength
' ~:,i:;.l:;.~u::~~ ;.c p~o~~u~ better fir for improved prote~.tion
against overflow leakages and retention of product shape
through use or wetting.
Another surprising advantage of the calendered and
pert-embossed cellulosic pulp fluff material over
unprocessed cellulosic pulp fluff and tenderized peat moss
sheet is the integrity and high tensile strength of the
improved pulp fluff core and its resistance to
deterioration through wetting and use. Absorbent cores
produced in accordance with the present invention
preferably have a dry tensile strength in the range from
about 1 to about 3 lbs/inch in the machine direction.
Further, the absorbent material according to the invention
has the combined desirable advantages of better fluid
penetration rate than tenderized peat moss and tenderized
debonded pulp, high absorption capacity, better
wickability characteristics and drying power than
unprocessed pulp fluff and tenderized debonded pulp.
The outstanding combination of absorption;
flexibility and wicking characteristics of the absorbent
core of the invention provides sanitary napkins capable of
absorbing menstrual or other body fluids quickly and
efficiently and retaining fluid in the absorbent structure
of the napkin so as to limit failure. Sanitary napkins
' CA 02321418 2000-07-26
' - 26 -
utilizing absorbent cores of the invention are flexible
and comfortable, yPL 1C$lStallt i:o bunching, twist~n5, and
deterioration through active use. The absorbent core of
the invention can be utilized as an insert or as an entire
surface bilayer of a sanitary napkin. For example, the
absorbent core of the invention can be utilized as a
reservoir layer or insert in conjunction with a cover and
transfer layer or because of its short fluid penetration
time, it may be used adjacent only a cover layer whereby
the absorbent core of the invention serves the dual
function of a transfer layer and reservoir layer.
In addition to sanitary napkins, the densified and
embossed cellulosic pulp fluff sheet according to the
invention may also be used in other absorbant products
such as diapers, incontinence products, wound dressings,
bandages and also as packaging material to provide dry
shipment of goods which may exude moisture in shipment or
storage.
The densified and embossed cellulosic pulp fluff
material of the invention may be treated with softening
agents, such as glycerin or lanolin or others. In
addition to softening agents, other absorbent materials
such as fibers or "superabsorbent" polymers may be
incorporated into the matrix spaces of the absorbent core
structure. Such fibers and polymers are described, for
CA 02321418 2000-07-26
r
_ 27 _
example, in U.S. patent number 4,559,050. Further,
supera~scrber.t laminates may he provideu in combination
with the calendered and perf-embossed cellulosic pulp
fluff material to provide extra absorption capacity such
as, for example, in incontinence products.
EgAHPLES
The invention will now be illustrated by examples.
The examples are not intended to be limiting of the scope
of the present invention but read in conjunction with a
detailed and general description above provide a further
understanding of the present invention and an outline of
a process for preparing a sanitary napkin which comprises
a calendered and perf-embossed cellulosic pulp sheet as
its absorbent core.
The description of the various test procedures to
which the materials of Examples 1 and 2 have been
subjected, are described in the section entitled "TEST
PROCEDURES" following Table 4.
CA 02321418 2000-07-26
- 28 -
Examples 1-2
Preparation of Absorbent and Flexible calendered and Perf-
Embossed Cellulosic Pulp Fluff Sheet
taood pulp board, the starting material of the process
descriued in connection with Figure 1, is available
commercially from, for example:
Example 1 Rayfloc (Trademark)
produced by ITT Rayonier
Example 2 Supersoft (Trademark)
produced by The International Paper
Company
Technical characteristics of these wood pulp boards
are provided in Table I.
CA 02321418 2000-07-26
i
- 29 -
TABLE I
~On~ i uib DGaxu
Ex. 1 Ex. 2
al Physical Properties
. Basis weight 685 690
grams per meter squared (g/m2)
. Density .525 .535
grams per cubic centimer (g/cc)
b) Structural Integritv
. Dry tensile strength 70 95
pounds per inch (lbs/inch)
c) Fluid Absorption
. Penetration time above 800 above 3000
seconds (s)
. 45° Impact capacity 7.5 3.3
grams (g)
The boards of Examples 1-2 are mechanically grinded
to obtain wood pulp fluff webs, having the characteristics
described in Table 2.
CA 02321418 2000-07-26
t
- 30 -
TABLE 2
entreated wood gulp fluff ;aEw
Ex. 1 Ex. 2
a) Physical Properties
. Basis weight 350 360
grams per meter squared (g/m2)
. Density .045 .045
grams per cubic centimer (g/cc)
b) Structural Intecrrity
. Dry tensile strength virtually nil
pounds per inch (lbs/inch)
c) Fluid Absorption
. Penetration time 5 5
seconds (s)
. 45 Impact capacity 27 27
grams (g)
. Capacity 14 15
cubic centimeters per gram (cc/g)
. Collapse strength * -29 -27
percentage (a)
. Wet-back .51 .48
grams (g)
. Wicking (uptake) refer to graph Figure
17
d) Flexibility
. Lateral compression
g: ,-:-':~s ( g
i ) dry about '100
ii) wet about 100
* negative values indicate collapse
CA 02321418 2000-07-26
- 3I -
The wood pulp fluff webs of Examples 1-2 are
.-,.e c:~anical=; ~ompressPd by the calendPring n: ocea5
described in connection with Figure 1. The double layer
calendered webs of Examples 1-;: have the characteristics
as described in Table 3.
TABLE 3
Calendered double layer wood pulp fluff web
Ex. 1 Ex. 2
. . , . , . . ~ . .~ , . . - - . . . , ~ , . .: . ... . .:.;... -
aZ Fh~rsical ProQerties
. Basis weight 2 645 625
grams per meter squared (g/m )
. Density .48 .42
grams per cubic centimer (g/cc)
b) Structural Integrity
. Dry tensile strength 34 19
pounds per inch (lbs/inch)
c) Fluid Absorption
. Penetration time above 800 above 600
seconds (s)
. 45° Impact capacity 14.2 14.6
grams (g)
The calendered webs prepared in accordance with the
procedures set ouL .:boy? for E~~amples 1-2 are treated by
pert-embossing as described in this specification. The
resulting perf-embossed cellulosic pulp fluff sheets have
the characteristics as described in Table 4.
CA 02321418 2000-07-26
.~
- 32 -
TAHLE 4
~:alendered and Per'-E~~ccc~d ~G.~h;~ y3~~er Wond Pul~Fluff Shert
Ex. 1 E:. 2
a) Physical Properties
Basil Weight. . .615 620
. .
grams per meter squared (g/m2) ~ ~ ..
. Density .23 .21
grams per cubic centimer (g/cc)
b~ Structural Intecrrit_y
. Dry tensile strength 2.5 1.1
. ~ :
pounds per ~ihch ( lbs/inch) v ~ ~ . . . . ~ . , :. , . . .
.. . . . .
; . .1 . ' t' ./,.
.
c7 Fluid Absorption
. Penetration time
Seconds (s)
i) rigid sample support 64 62
ii) resilient sample support 29 34
. 45 Impact capacity 21.5 23.1
grams (g)
. Capacity 5.8 6.6
cubic centimeters per gram (cc/g)
. Collapse strength ' +46 +49
percentage (%)
. Wet-back .15 .16
grams (g)
. Wicking (uptake) refer to graph Figure 18
d) Flexibility
. Lateral compression
grams (g)
i) dry from 700 to 1700
ii) wet from 550 to 950
* positive values indicate swelling.
CA 02321418 2000-07-26
- 33 -
DESCRIPTION OF TES? PROCEDURES
A Br'1SIS liIEIGHT
Purpose: To determine the.basis weight of~the
absorbent material.
~ Test procedure: One square foot sample is weighted and
_ . the b.asi.s wei.g~t _, is_ ~c.alc~lated... in
. . . . ~ . . .... . ~. _ - . : . .: ~ .. . ~ ~.Y
grams per meter squared (g/m2).
B) THICKNESS
~ Purpose: To determine the thickness of the
absorbent material.
~ Test procedure:
1) Wood Pulp Board: The thickness of the
board material is measured with a THI
thickness gauge at 7 psi pressure with
a 5/8 inch diameter foot (TAPPI
standard T411 OS-76);
CA 02321418 2000-07-26
4.
- 34 -
2) Fluffed, Calendered, Perf-Embossed
Word Pulpy The thickness vi c.he
sample is measured at 0.05 psi
pressure With a compressometer using
a 2 inch diameter foot (ASTH D-1777).
C) DENSITY
., ~. ... . . . .. . . . . , . . _ . ~ . _ . . , _ .. . . . , , . ..
Purpose: To determine the density of an
absorbent material under a
predetermined pressure.
Test procedures
1) Wood Pulp Boards The density is
obtained by measuring the weight of a
1 square foot sample and dividing it
by its volume (thickness X area of
sample ;
2) Fluffed, Calendered, Perf-Embossed
Wood Pulp: The density of the
processed material is obtained by
taking the weight of a 2 inch X 3 inch
sample and dividing it by its volume
(thickness X area of sample).
CA 02321418 2004-04-16
-35-
D) TENSILE STRENGTH
Purpose: To determine the structural strength of the
absorbent material by measuring the force
required to rupture the sample.
Test procedure: The tensile strength is measured by
recording the force required to rupture a 1
inch wide sample placed between two jaws 3
inches apart and moving at a continuous
rate.
E) PSNSTRATION TIME
Purpose: To determine the penetration time of an
absorbent material by measuring the time
required to completely absorb a finite
amount of fluid.
Test procedure: The time required for a 2 inch X 8 inch
sample under 0.04 psi pressure covered by a
Plexiglas" plate, as shown in Figure 12, to
absorb 5 cubic centimeters of test fluid
fed to the
CA 02321418 2000-07-26
- 36 -
sample through an oval orifice on the
p7ote measurin5 1 iil inchea X 3/~ of
an inch. The sample may be supported
on either a rigid or a resilient base.
The latter embodiment is useful for
absorbent materials which swell when
absorbing fluid because the resilient
cushion can yield allowing for further
expansion. The penetration time is
,10 .. : . . _ . . ,.. , recoxde,d., when., all. free ._liguid _ _h~d ., . .
disappeared from the surface of the
sample exposed by the oval orifice.
- Test fluid: Synthetic menstrual fluid.
F? 45° IHPACT CAPACITY
Purpose: To determine the fluid retention
capacity of an absorbent material by
measuring its ability to accept and
retain a finite discharge of fluid at
an inclined plane.
CA 02321418 2000-07-26
- 37 -
Test procedures With reference to Figure 13, the
impact capacity on a 2 ir.co ::y 1C ii.c«
sample is measured by weighing the
a~no~int of fluid that is retained in
the sample placed on a 45° inclined
plane, on.which 25 cubic centimeters
of test fluid has been released from
an overhanging burette. The burette
barely touches the sample at a point
_ approximately 2 inches away from its
.. . . . ... .. .. _ . .. ~. , .. . . . . ._ . . : . -.
upper extremity.
Test fluid: Synthetic menstrual fluid.
G) FLUID CAPACITY AIJD COLLAPSE
~ Purpose: To determine the fluid saturation
capacity of an absorbent material by
measuring the maximum amount of fluid
the absorbent material can hold under
a predetermined pressure. In
addition, the degree of collapse (or
gain) of the absorbent material upon
fluid saturation is determined.
CA 02321418 2000-07-26
- 38 -
~ Test procedures With reference to Figure 14, the fluid
:.ara..~.ity of z pre-;weighted 4 inches by
4 inches sample is obtained by
measuring the amount of fluid that is
required to saturate the sample placed
under a 0.05 psi~pressure- (achieved
with a free moving top plexiglass
plate). The test fluid is introduced
through a small hole having 1/8 of an
, , . . , inch diameter located in, the .center of '.
the plate. The change in thickness of
the sample is measured. The
difference in the dry and the wet
thickness is recorded and the
percentage of gain or collapse
derived.
~ Test fluid: Synthetic menstrual fluid.
H ) INCLIIiED PLANE NICKING
~ Purpose: To determine the wicking capacity/
capillary action of an absorbent
material by measuring the amount of
fluid uptake and the distance of fluid
CA 02321418 2000-07-26
- 39 -
migration as a function of time at an
in::lined pla-..~.
~ Test procedure: With reference to Figure 15, the
wicking capacity of a 2 inches % 10
inches sample .i~s obtained by placing
it on a 45° inclined plexiglass plane
with the Sower end of the sample
dipped into a grooved depression which
'-0 . constitute.s the liquid bath.for the ,,
sample. A constant fluid level is
maintained by introducing measured
amounts of fluid into the bath via a
micrometric solenoid valve (activated
by an auto~oatic level control device ) .
The advancing liquid front moving up
the sample is monitored by measuring
the distance or height the fluid
travels above the bath at specific
time intervals, and the amount of
fluid uptake is recorded.
~ Test fluid: 1% NaCl solution.
, CA 02321418 2000-07-26
- 40 -
I1 HET BACK
~ Purposes To determine the ability of the
absorbent naterial to absorb and
retain fluid under a
pre-determined
pressure while preventing transfer of ~ .
fluid to another surface.
Test procedure: The wet-back characteristics of a pre-
, weighted. 2. inches X 8 inches sample _is
. . : , .. . :_ .. .. . ,. . . .
obtained by first adding 2 cc/g of
synthetic menstrual fluid through an
elliptical orifice on the sample under
a pressure of 0.04 psi. After the
i5 fluid has been absorbed and dispersed
in the sample for 3 minutes, 10 plies
of 2 inches X 6 inches NuGuaze
(Trademark) substrate are placed on
the sample and a "cushioned" pressure
of 0.25 psi is apglied. The quantity
of liquid transferred after 3 minutes
to the substrate is measured in grams.
~ Test fluid: Synthetic menstrual fluid.
CA 02321418 2004-04-16
-41-
J) LATERIAL FLEXIBILITY/ STABILITY
Purpose: To determine the lateral flexibility and
structural stability of a thin absorbent
sheet by subjecting the sample to side
compression.
Test procedure: With reference to Figure 16, the lateral
Flexibility/stability of 2 1/8 inches X 8
1/8 inches (rounded ends) sample is
obtained by placing the sample in between
two Plexiglas" curves (simulating the inner
thighs of a wearer); the stationary curve
is attached to a compression load cell in
an Instron"" unit and a speed of 500
millimeters per minute (mm/min) is imparted
to the moving curve. The sample is
securely placed in between the two curves
with three metal support rods stemming from
the stationary curve and slidingly received
in the moving curve. The force required to
compress the sample to one inch is
recorded. The wet test is done by adding 2
cc/g of fluid to
CA 02321418 2000-07-26
- ~:-".
- 42 -
the absorbent material and subjecting
it co the iaterat c:omprer ~i=~r..
Test fluid= Synthetic menstrual fluid.
DISCUSSION
For a better understanding of the invention, the test
results in Tables 2 .and 4 and the graphs of Figures t1.7 and
18 will be discussed. A direct comparison is made between
untreated wood pulp fluff and calendered and perf-embossed
wood pulp fluff because the latter is intended as a direct
replacement for untreated pulp-fluff. The test results in
Tables 1 and 3 are not discussed here since they relate to
a product in intermediate states of fabrication. This
data simply illustrates how the various steps of the
calendering and perf-embossing process affect the
properties of the fibrous material.
The calendered and perf-embossed wood pulp fluff
sheet exhibits a considerable improvement in structural
integrity over untreated wood pulp fluff. The dry tensile
strength considerably increases from virtually nothing for
untreated wood pulp fluff to an average of 1.8 lbs/inch
for calendered and perf-embossed wood pulp fluff, which is
considered to be satisfactory for practical applications,
CA 02321418 2000-07-26
6'~.,;
- 43 -
permitting to obtain an absorbent core highly resistant to
mecl:~n:c:a1 :tress capable to retain its shape in use.
Unproce~se3 wood pulp fluff has better penetration
time, 45° impact capacity and absorbent capacity
characteristics over calendered and pert-embos.sed.wood
pulp fluff. These differences directly result from the
denser fibrous network of the calendered and perf-embossed
wood pulp fluff, however, they are not significant to a
. 10 _ . point . w.here the calendered. and perf-.embossed wood p.ulp_
fluff is no longer capable to efficiently absorb fluid.
A major improvement is observed in wicking power of
the fibrous web resulting from the calendering and perf-
embossing process. Referring to Figures 17 and 18, it
appears clearly that unprocessed wood pulp fluff has a
very limited ability to wick fluid. Over a period of 10
minutes the fluid front has barely exceeded a distance of
5 centimeters. In the same conditions, calendered and
perf-embossed wood pulp fluff exhibits a much superior
wicking action, pulling fluid over a distance of
approximately 27 centimeters which represents an
improvement by a factor in excess of S.
The improvement in the wicking characteristics of
calendered and perf-embossed wood pulp fluff compensates
for the reduction in absorbent capacity by comparison to
CA 02321418 2000-07-26
~.:
- 4! -
unprocessed wood pulp fluff, by the capability of the
....;c.~.~c~cd ;.-a perf-emhossed fibrous network to dis~;erse
fluid into a larger absorbent volume. This is reflected
by the fluid uptake values which are almost the same for
the compared wood pulp fluff materials. Undeniably,
unprocessed good pulp fluff has a much better absorbent .
capacity than calendered and perf-embossed wood pulp fluff
and theoretically, the amount of fluid it can absorb is
superior to what the calendered and perf-embossed wood
, pulp fluff can absorb. . However, . in , practice, .it _ is _ . - .
extremely difficult to use the entire absorbent volume of
unprocessed wood pulp fluff because fluid tends to remain
localized, causing saturation. The calendering and perf-
embossing process of wood pulp fluff considerably improves
its performance by achieving a certain balance between its
various attributes, improving some at the expense of
others, but however, achieving an overall gain in
efficiency.
Further, the calendered and perf-embossed wood pulp
fluff has a better ability to retain the absorbed fluid
(i.e. drying power) than unprocessed pulp fluff.
Accordingly, calendered and pert-embossed pulp is less
likely to wet adjacent surfaces that may come in contact
with the absorbent structure than is the case for
unprocessed pulp fiber.
CA 02321418 2000-07-26
... ,
- 45 -
EgANPLE 3
A sanitar;~ napkii; c~rupri5i~,w a:, absorhP~r and flexible
calendered perf-embossed cellulosic pulp fluff sheet as
its absorbent core.
Referring to Figure 11, a. sanitary 1'napk'in. ~ .42
comprises an absorbent core 44 constructed in accordance
with Example 1. The core 44 includes throughout its
entire surface perforations 31 created at the perforation
_ , stage. _of the..perf-embossing, treatment,. .and 1_aterallY .and _ . .. .
longitudinally extending lines 35 and 41, respectively,
created at the embossing stages. The width of the
absorbent core 44 is of importance to achieve good
comfort, good stability and, at the same time, to have
satisfactory fluid absorbance characteristics. The
narrower the core 44, the higher its comfort potential
beccmes, however, the risk of failure of the napkin
increases because it becomes unstable and its absorbency
characteristics are adversely affected by the reduction of
the available fluid absorption surface. There is a
delicate balance between these factors. It has been found
that a width in the range of from about 1 3/4 inches to
about 2 1/4 inches is a satisfactory compromise and most
preferably the width is of about 2 1/8 inr.hes. The
thickness of the absorbent core 44 is of about 0.1 inch
measured at 0.05 psi pressure and its length of about 8
inches.
CA 02321418 2000-07-26
- 46 -
The lateral flexibility of the absorbent core 44 is
also important for good comfcrt. A la2erai ilexinitiLy in
the dry state in the range of about 700 g to 1700 g has
been found adequate. The most preferred range is of about
1100 g to 1400 g. A lateral flexibility in the wet state
in the range of.about~550 g to 950 g is. satisfactory.
The remaining structure of the sanitary napkin
incudes an envelope to confine the absorbent core 44,
comprising .a fluid permeable side ,46 forarans.fer.ri.ng. the.,
menstrual fluid to the absorbant core 44, a fluid
impermeable side 48 provided with an adhesive band 50
covered by a peelable backing 52. The adhesive band
permits attachment of the sanitary napkin to the user's
underpants.
Sanitary napkins in accordance with Example 3 are
found in use to possess a better wicking capability as
that of napkins having an absorbent core made of
unprocessed cellulosic pulp fluff. The sanitary napkin of
the invention is found to be objectively somewhat less
flexible than peat moss composite absorbent core napkins,
but this was not observed as significantly affecting the
comfort for wearers in use. It was further found that the
sanitary napkins in accordance with the invention are
surprisingly more resistant to bunching and deforming than
napkins with absorbent cores of unprocessed cellulosic
CA 02321418 2000-07-26
47 -
pulp fluff material leading to better overall performance
in Lemn~ cf prot~~_tio.~i from leakage and retention of
product shape.
The scope of the present invention is not limited by
the description, examples , and sugges~te~d uses herein and
modifications can be made without departing from the
spirit of the invention. For example, additional
embossing patterns that provide either aesthetic or
1.0 fun_ctio.nal .qualitie to the, ca.lendexed and._.perf-embossed,, _ , ,
cellulosic pulp fluff sheets of the invention may be
provided. The absorbent cores of the present invention
may also be utilized in diverse products including
incontinence pads, absorbent cores as inserts for diapers
or tampons, or as desiccants for use in packaging
materials to keep goods dry during shipping or storage.
Application of the product and methods of the present
invention for sanitary and other health care uses can be
accomplished by any sanitary protection, incontinence,
medical, and absorbent methods and techniques as are
presently or prospectively known to those skilled in the
art. Thus it is intended that the present invention cover
the modifications and variations of this invention
provided that they come within the scope of the appended
claims and their equivalents.
