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Claims  |
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What is claimed is:
1. An absorbent article for wearing by a human female, said absorbent
article comprising:
a primary absorbent component having a base, an apex, said base and apex
each having a width, wherein the width of said base is greater than the
width of said apex and the width of said primary absorbent component
decreases from said base to said apex, and at least a portion of said
primary absorbent component has a width of less than or equal to about 9.5
mm, said primary absorbent component comprises a compressible,
hydrophilic, flexible, nonionic polymeric foam structure of interconnected
open cells which is capable of absorbing blood and blood-based liquids,
wherein said foam structure is resiliently compressible and has a
resistance to compression deflection of from about 5% to about 85% when
measured under a confining pressure of 0.74 psi at 31 degrees C. after 15
minutes, according to the Resistance to Compression Deflection Test.
2. The absorbent article of claim 1 wherein at least a portion of said foam
structure adjacent said apex has a resistance to compression deflection of
from about 40% to about 85% under such conditions.
3. The absorbent article of claim 2 wherein at least a portion of said foam
structure adjacent said apex has a resistance to compression deflection of
from about 60% to about 85% under such conditions.
4. The absorbent article of claim 1 wherein said foam structure is
compressible under such forces that when it is placed in the space between
the wearer's labia majora, it will be compressed without deforming the
wearer's labia, and will be molded by the wearer's labia and conform to
the shape thereof.
5. The absorbent article of claim 1 wherein said primary absorbent
component has a length and a height measured along at least a portion of
said length which is between about 5 mm and about 30 mm so that at least a
portion of said primary absorbent component will fit in the wearer's
gluteal groove.
6. The absorbent article of claim 1 wherein said foam structure has:
A) a capillary specific surface area in the range of from about 0.0080 to
about 0.49 m.sup.2 /cc;
B) a free absorbent capacity of from about 20 to bout 125 g/g; and
C) inorganic salt content of less than about 2% by dry weight of foam.
7. The absorbent article of claim 1 wherein said foam structure has a Tg of
less than about 50.degree. C.
8. The absorbent article of claim 1 wherein said foam structure has a cell
size of from about 30 to about 130 .mu.m.
9. The absorbent article of claim 1 wherein said foam structure has a hole
size of from about 5 to about 30 .mu.m.
10. The absorbent article of claim 1 wherein said foam structure has the
ability to wick artificial menstrual fluid vertically to a height of 5 cm
in less than about 40 minutes.
11. The absorbent article of claim 1 wherein said foam structure comprises
a single homogeneous foam structure.
12. The absorbent article of claim 1 wherein said foam structure comprises
a heterogeneous mixture of a first foam portion having a capillary
specific surface area of from about 0.012 to about 0.020 m.sup.2 /cc and a
second foam portion having a capillary specific surface area of from about
0.020 to about 0.026 m.sup.2 /cc.
13. An absorbent article for wearing by a human female, said absorbent
article comprising:
a primary absorbent component having a base, an apex, said base and apex
each having a width, wherein the width of said base is greater than the
width of said apex and the width of said primary absorbent component
decreases from said base to said apex, and at least a portion of said
primary absorbent component has a width of less than or equal to about 9.5
mm, said primary absorbent component comprises a compressible,
hydrophilic, flexible, nonionic polymeric foam structure of interconnected
open cells which is capable of absorbing blood and blood-based liquids,
wherein said foam structure is resiliently compressible and has a
resistance to compression deflection of from about 40% to about 85% when
measured under a confining pressure of 0.74 psi at 31 degrees C. after 15
minutes, according to the Resistance to Compression Deflection Test, and
said primary absorbent component is capable of at least partially fitting
in the space between the wearer's labia.
14. The absorbent article of claim 13 wherein said acquisition/fit
component has an average cell diameter of between about 100-130 microns
and said storage component has an average cell diameter of between about
35-60 microns.
15. An absorbent article for wearing by a human females said absorbent
article comprising:
a primary absorbent component having a base, an apex said base and apex
each having a width wherein the width of said base is greater than the
width of said apex and the width of said primary absorbent component
decreases from said base to said apex and at least a portion of said
primary absorbent component has a width of less than or equal to about 9.5
mm, said primary absorbent component comprising:
an acquisition/fit portion comprising a hydrophilic flexible, nonionic
poltmeric foam structure of interconnected open cells which is capable of
absorbing blood and blood-based liquids, said acquisition/fit portion
having a first cell size and a first width;
a storage portion als o comprising a hydrophilic, flexible, nonionic
polymeric foam structure of interconnected open cells which is capable of
absorbing blood and blood-based liquids, having a second cell size and a
second width, wherein said second cell size is smaller than said first
cell size, creating a capillary gradient, first width is less than said
second width, and said acquisition/fit is facing the body of the wearer,
wherein said acquisition/fit portion has a resistance to compression
deflection of from about 40% to about 85% when measured under a confining
pressure of 0.74 psi at 31 degrees C. after 15 minutes, according to the
Resistance to Compression Deflection Test, and said storage portions has a
resistance to compression deflection of about 5% to about 50% under such
conditions.
16. The absorbent article of claim 15 wherein said acquisition/fit portion
and said storage portion comprise separate components.
17. The absorbent article of claim 15 wherein said acquisition/fit portion
is more compressible and resilient than said storage portion.
18. The absorbent article of claim 15 wherein at least said acquisition/fit
portion is able to fit in the space between the wearer's labia.
19. The absorbent article of claim 16 wherein said acquisition/fit
component has a capillary suction specific surface area of from about
0.012 to about 0.020 m.sup.2 /cc and said storage component has a
capillary specific surface area higher than that of said acquisition fit
component and in the range of from about 0.020 to about 0.026 m.sup.2 /cc.
20. A compound sanitary napkin comprising a primary absorbent component and
a secondary absorbent component;
said primary absorbent core and an outer cover, said absorbent core
comprising a compressible, hydrophilic, flexible, nonionic polymeric foam
structure of interconnected open cells which is capable of absorbing blood
and blood-based liquids, said foam structure comprising:
an acquisition/fit portion having a resistance to compression deflection,
according to the Resistance to Compression Deflection Test, of from about
40% to about 85% when measured under a confining pressure of 0.74 psi at
31 degrees C. after 15 minutes, a capillary specific surface area,
according to the Capillary Suction Specific Surface Area Test, of from
about 012 to about 0.020 m.sup.2 /cc, and an average cell diameter of
between about 100-130 microns; and
a storage portion having a resistance to compression deflection of from
about 5% to about 50% under the same conditions specified for said
acquisition/fit portion, a capillary specific surface area of from about
0.020 to about 0.026 m.sup.2 /cc, and an average cell diameter of between
about 35-60 microns; and
said secondary absorbent component comprising a liquid pervious topsheet, a
liquid impervious backsheet joined to said topsheet, and an absorbent
element positioned between said topsheet and said backsheet, said
secondary absorbent component being joined to said primary absorbent
component.
21. The absorbent article of claim 20 wherein said primary absorbent member
has a capacity and said secondary absorbent member has a capacity, and the
ratio of the capacity of the primary absorbent member to the capacity of
said secondary absorbent member is between about 1:1 and about 10:1.
22. The absorbent article of claim 20 wherein said primary absorbent member
has a capacity and said secondary absorbent member has a capacity, and the
ratio of the capacity of the primary absorbent member to the capacity of
said secondary absorbent member is about 5:1. |
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Claims |
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Description |
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FIELD OF THE INVENTION
The present invention relates to absorbent articles such as sanitary
napkins, panty liners, and the like. More particularly, the present
invention relates to absorbent articles of the foregoing type which have a
foam absorbent structure that provide improved acquisition of blood based
liquids such as menses, and improved fit relative to a female wearer's
body.
BACKGROUND OF THE INVENTION
Absorbent articles such as sanitary napkins, pantiliners, and incontinence
pads are devices that are typically worn in the crotch region of an
undergarment. These devices are designed to absorb and retain liquid and
other discharges from the human body and to prevent body and clothing
soiling. Sanitary napkins are a type of absorbent article worn by women in
a pair of panties that is normally positioned between the wearer's legs,
adjacent to the perineum. Sanitary napkins of a wide variety of shapes and
dimensions are currently used by women for the collection of menses and
other bodily discharges.
In the past, a number of efforts have been directed at providing sanitary
napkins that maintain contact with the wearer's body. One attempt to
provide such body contact is disclosed in U.S. Pat. No. 2,747,575 issued
May 29, 1956 to Mercer. The Mercer patent discloses a catamenial bandage
having a longitudinal hump which bulges towards and may contact the body
of the wearer, The catamenial bandage described in the Mercer patent
suffers from several disadvantages, however. For instance, the size and
shape of the absorbent pad and hump in the Mercer bandage appear to limit
the conditions under which the bandage is able to maintain contact with
(and conform to) the body of the wearer. The portions of the bandage that
lie laterally to the sides of the hump are not thin and flexible. In
addition, the hump of the Mercer bandage is made of a cellulosic material,
and, as a result, may tend to collapse and become permanently distorted
during use.
U.S. Pat. No. 4,425,130 issued to DesMarais on Jan. 10, 1984, discloses a
compound sanitary napkin that comprises a primary menstrual pad and a
panty protector joined to one another at their corresponding ends in such
a manner that the two constituents are free to move relative to one
another along essentially their entire common length. The primary
menstrual pad is intended to absorb the bulk of the bodily fluids
discharged by the user, while the panty protector is intended to protect
the user's garments from soiling. In use, the relative freedom of movement
between the primary menstrual pad and the panty protector serves to
maintain the primary menstrual pad adjacent the user's crotch region while
the panty protector remains associated with the user's undergarment.
The current tendency has been to develop sanitary napkins that are
increasingly thinner, and thus more comfortable and less obtrusive than
prior sanitary napkins. Recently, efforts have been directed at developing
thin sanitary napkins which have the capacity to absorb and contain medium
to high menstrual discharges. Previously, such discharges could only be
handled by relatively thick sanitary napkins. Examples of thin sanitary
napkins having capacities great enough to handle medium to high menstrual
flows are disclosed in U.S. Pat. Nos. 4,950,264 and 5,009,653, issued to
Osborn, III, on Aug. 21, 1990 and Apr. 23, 1991, respectively.
It is also desirable that sanitary napkins, not only maintain contact with,
but conform as closely as possible to the wearer's body. Such a
body-conforming capability increases the effectiveness of the sanitary
napkin by reducing the possibility that menses will travel around the
perimeter of the sanitary napkin and leak. There have been a number of
recent efforts to provide sanitary napkins and other absorbent articles
with improved body-conforming characteristics. In addition to serving as
examples of thin sanitary napkins, the sanitary napkins disclosed in the
above-mentioned Osborn patents also serve as examples of
anatomically-conforming sanitary napkins. While the sanitary napkins
disclosed in the Osborn patents work quite well, the search for improved
sanitary napkins has continued.
For example, PCT International Patent Application Publication No. WO
94/16658, entitled "Generally Thin, Flexible Sanitary Napkin With Central
Absorbent Hump", published on Aug. 4, 1994, discloses a generally thin,
flexible sanitary napkin which has a central absorbent hump, and is
capable of handling medium to high menstrual flows. The hump is
particularly useful in fitting into the space between the wearer's labia
to more readily intercept menses and other bodily discharges when they
leave the wearer's body. The search, however, has continued for improved
sanitary napkins, particularly sanitary napkins that will achieve even
better fit within the space between the wearer's labia majora, and which
are more adept at absorbing blood-based liquids, such as menses.
The development of highly absorbent articles for blood and blood-based
liquids such as catamenial pads (e.g., sanitary napkins), tampons, wound
dressings, bandages and surgical drapes can be challenging. Compared to
water and urine, blood and blood based liquids such as menses are
relatively complex mixtures of dissolved and undissolved components (e.g.,
erythrocytes or red blood cells). In particular, blood-based liquids such
as menses are much more viscous than water and urine. This higher
viscosity hampers the ability of conventional absorbent materials to
efficiently and rapidly transport these blood-based liquids to regions
remote from the point of initial discharge. Undissolved elements in these
blood-based liquids can also potentially clog the capillaries of these
absorbent materials. This makes the design of appropriate absorbent
systems for blood-based liquids such as menses particularly difficult.
Foams of various types have been suggested for use in tampons, sanitary
napkins and other articles that absorb blood and blood-based liquids. See
for example U.S. Pat. No. 4,110,276 (DesMarais), issued Aug. 29, 1978
(soft, flexible, open celled foams made from polyurethanes, cellulose, or
styrene/butadiene rubber that can be used in tampons and sanitary pads);
U.S. Pat. No. 4,752,349 (Gebel), issued Jun. 21, 1988 (foams of "medium
cell size" hydrophilized by surfactant treatment and having a density
within the range of 0.1 to 0.8 g/cc); U.S. Pat. No. 4,613,543 (Dabi),
issued Sep. 28, 1986 (hydrophilic cellular polymers used in catamenial
products); U.S. Pat. No. 3,903,232 (Wood et al.), issued Sep. 2, 1975
(compressed hydrophilic polyurethane foams useful in biomedical
applications, including catamenial devices); U.S. Pat. No. 4,049,592
(Marans et al.) issued Sep. 20, 1977 (biodegradable hydrophilic
polyurethane foams highly absorptive upon contact with liquids or bodily
liquids having utility in sanitary napkins and the like). Prior foams used
in these products have tended to have relatively large cell sizes. As a
result, these prior foams do not exert sufficient fluid capillary pressure
for blood and blood-based liquids to acquire discharged menstrual liquids
quickly from and through the topsheet of catamenial products such as
sanitary napkin . This results in undesirable rewet since the surface in
immediate contact with the body retains some of the fluid that is not
absorbed into the core and is available to be transferred back onto the
body of the wearer.
Suitable absorbent foams for absorbent products have also been made from
High Internal Phase Emulsions (hereafter referred to as "HIPE"). See, for
example, U.S. Pat. No. 5,260,345 (DesMarais et al), issued Nov. 9, 1993
and U.S. Pat. No. 5,268,224 (DesMarais et al), issued Dec. 7, 1993. These
absorbent HIPE foams provide desirable urine handling properties,
including: (a) relatively good wicking and fluid distribution
characteristics to transport fluid away from the initial impingement zone
and into the unused balance of the foam structure to allow for subsequent
gushes of fluid to be accommodated; and (b) a relatively high storage
capacity with a relatively high fluid capacity under load, i.e. under
compressive forces. These HIPE absorbent foams are also sufficiently
flexible and soft so as to provide a high degree of comfort to the wearer
of the absorbent article; some of these foams, such as those described in
U.S. Pat. No. 5,387,207 issued Feb. 7, 1995 (Dyer, et al.), can be made
relatively thin until subsequently wetted by the absorbed body liquids.
See also U.S. Pat. No. 5,147,345 (Young et al), issued Sep. 15, 1992 and
U.S. Pat. No. 5,318,554 (Young et al), issued Jun. 7, 1994, which disclose
absorbent cores having a fluid acquisition/distribution component that can
be a hydrophilic, flexible, open-celled foam such as a
melamine-formaldehyde foam (e.g., BASOTECT.TM. made by BASF), and a fluid
storage/redistribution component that is a HIPE-based absorbent foam.
HIPE foams can provide the fluid capillary pressure necessary to remove
most of the menstrual fluid from the body, or topsheet adjacent to the
body, thus minimizing rewet. However, it has been found that the residual
hydratable salts such as calcium chloride typically present in prior HIPE
foams can impair the rapid acquisition blood and blood-based liquids by
these foams, and especially the wicking of such liquids within these
foams. As noted above, blood and blood-based liquids such as menses are
more highly viscous than water and especially urine. The higher viscosity
of these liquids is further increased by the presence of these salts.
Moreover, prior HIPE foams often had a foam microstructure too small to
admit readily the undissolved components of blood and blood-based liquids
such as red blood cells.
Therefore, it is an object of the present invention to provide an absorbent
article, such as a sanitary napkin that maintains contact with and
conforms as closely as possible to the wearer's body.
It is another object of the present invention to provide an absorbent
article, such as a sanitary napkin that is comprised of a foam material
which is especially suitable for handling, absorbing, and storing
blood-based liquids, such as menses.
It is another object of the present invention to provide an absorbent
structure for an absorbent article, where the entire absorbent structure
is absorbent and resilient so that the absorbent article does not require
a separate resilient component that would interfere with the overall
absorbency of the absorbent structure.
It is another object of this invention to provide a sanitary napkin which
readily intercepts menses when discharged by being highly compressible so
that it can be compressed to a relatively small size to comfortably fit
and maintain contact with and conform to the shape of the female wearer's
body, particularly with the inwardly-facing surfaces of the labia majora,
or it can occupy the relatively large area in the crevice between the
wearer's buttocks (or gluteal groove).
It is an additional object of the present invention to provide an absorbent
article, such as a sanitary napkin, that has an absorbent structure which
can routinely and comfortably fit interlabially on wearer's having a wide
variety of body dimensions.
These and other objects of the present invention will be more readily
apparent when considered in reference to the following description and
when taken in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
The present invention is directed to absorbent articles for wearing by a
human female such as sanitary napkins, panty liners, interlabial devices,
and adult incontinence pads which provide improved acquisition of
blood-based liquids such as menses, and improved fit relative to a female
wearer's body.
The absorbent article comprises a primary absorbent component having a base
and an apex. In one preferred embodiment, the width of the base is greater
than the width of the apex and the width of said primary absorbent
component decreases from the base to the apex. Preferably, at least a
portion of the primary absorbent component has a width of less than or
equal to about 9.5 mm, or is compressible to such a width. The primary
absorbent component comprises a compressible and resilient, hydrophilic,
flexible, nonionic polymeric foam structure of interconnected open cells
which is capable of absorbing blood and blood-based liquids. The foam
structure is compressible under such forces that when it is placed in the
space between the wearer's labia majora, it will be compressed without
deforming the wearer's labia, and will be molded by the wearer's labia and
conform to the shape thereof The absorbent article is, thus, very
comfortable to wear. In addition, in a particularly preferred embodiment,
the absorbent article is provided in the form of a sanitary napkin in
which the primary absorbent component will be able to fit in the space
between the wearer's labia (and gluteal groove) by the simple action of
placing the sanitary napkin in a pair of panties, and pulling up the
panties.
The foam materials used in the absorbent article of the present invention
are capable of absorbing blood and blood-based liquids such as menses and
then moving these absorbed liquids efficiently to other regions of the
foam. These absorbent polymeric foam materials comprise a hydrophilic,
flexible, nonionic polymeric foam structure of interconnected open-cells.
This foam structure has:
A) the ability to wick artificial menstrual fluid (AMF) vertically to a
height of 5 cm in less than about 40 minutes;
B) a capillary specific surface area in the range of from about 0.0080 to
about 0.040 m.sup.2 /cc;
C) a resistance to compression deflection of from about 5 to about 85% when
measured under a confining pressure of 0.74 psi at 31.degree. C. after 15
minutes;
D) a free absorbent capacity of from about 20 to about 125 g/g;
E) less than about 2% of residual hydratable salts.
A particularly important attribute of the foams used in the present
invention is that the connecting passages (holes) between the cells of
these foams are sufficiently large to pass insoluble solids such as
erythrocytes (mean diameter 8 .mu.m). As a result, these holes do not
become blocked or obstructed by blood and blood-based liquids absorbed by
the foam. Even though the cells and holes are large enough to allow free
movement of insoluble components in blood and blood-based liquids, they
are sufficiently small so as to produce the necessary high capillary
absorption pressure required of absorbents used in catamenial products. In
other words, these foams combine high capillary absorption pressure with
sufficient openness to allow free movement of the insoluble components in
blood and blood-based liquids such as menses. Typically, the cells of
these foams have a number average cell size of from about 30 to about 130
.mu.m, while the holes between these cells have a number average hole size
of from about 5 .mu.m to about 30 .mu.m.
The process of forming the foams used in the present invention allows these
absorbent foams to have cells and holes small enough to provide a high
capillary absorptive pressure but large enough to prevent or minimize
blockage by the insoluble components of these liquids. In addition. this
process removes most of the residual electrolytes (i.e., hydratable salts)
from the foam. While these hydratable salts are typically needed during
initial formation of the HIPE, their presence in the resulting foam can
adversely affect its ability to absorb blood and blood-based liquids such
as menses, especially as the concentration of these salts in the foam
increases. Accordingly, it is desirable to reduce the level of these
hydratable salts in the foam.
In one preferred embodiment, the absorbent article comprises a primary
absorbent component, comprising an acquisition/fit portion and a storage
portion. The acquisition/fit portion comprises a hydrophilic, flexible,
nonionic polymeric foam structure of interconnected open cells which is
capable of absorbing blood and bloodbased liquids. The foam structure
forming the acquisition/fit portion has a first width and the cells within
the foam structure are of a size within a first range of values (or first
average cell diameter or "cell size"). The storage portion also comprises
a hydrophilic, flexible, nonionic polymeric foam structure of
interconnected open cells which is capable of absorbing blood and
blood-based liquids. The foam structure forming the storage portion has a
second width and the cells within the foam structure have a second cell
size (or second average cell diameter or "cell size"), wherein the second
cell size is smaller than the first cell size and the first width is less
than the second width.
BRIEF DESCRIPTION OF THE DRAWINGS
While the specification concludes with claims particularly pointing out and
distinctly claiming the subject matter which is regarded as forming the
present invention, it is believed that the invention will be better
understood from the following description which is taken in conjunction
with the accompanying drawings in which:
FIG. 1 is a top plan view of a preferred embodiment of a sanitary napkin of
the present invention.
FIG. 2 is a cross-sectional view of the sanitary napkin shown in FIG. 1,
taken along line 2--2.
FIG. 3 is a bottom plan view of the sanitary napkin shown in FIG. 1.
FIG. 4 is a top plan view of the sanitary napkin of the present invention
shown with the side wrapping elements folded over the body-facing side of
the main body portion, and the fasteners thereon covered with a unitary
release strip.
FIG. 5 is a bottom plan view of the sanitary napkin shown in FIG. 4 which
is provided with a multiple piece panty fastener cover.
FIG. 6 is a perspective view of the sanitary napkin in a wearer's panties.
FIG. 7 is a top plan view of another embodiment of a sanitary napkin.
DETAILED DESCRIPTION OF THE INVENTION
1. General Characteristics of a Preferred Embodiment of the Absorbent
Article of the Present Invention.
The present invention is directed to absorbent articles for wearing by a
human female such as sanitary napkins, panty liners, interlabial devices,
and adult incontinence pads. The absorbent articles of the present
invention have a foam absorbent structure that provides improved
acquisition of blood-based liquids such as menses, and improved fit
relative to a female wearer's body.
The absorbent article comprises a primary absorbent component having a base
and an apex. In one preferred embodiment, the width of the base is greater
than the width of the apex and the width of said primary absorbent
component decreases from the base to the apex. The primary absorbent
component comprises a compressible, hydrophilic, flexible, nonionic
polymeric foam structure of interconnected open cells which is capable of
absorbing blood and blood-based liquids. The foam structure is
compressible under such forces that when it is placed i | | |
