U.S. patent application number 10/237582 was filed with the patent office on 2003-08-07 for multi-layered tampon cover.
Invention is credited to Cole, Robert, Louie, Lai-Hing, Pierson, Linda M., Yeganeh, Mary S..
Application Number | 20030149416 10/237582 |
Document ID | / |
Family ID | 25544253 |
Filed Date | 2003-08-07 |
United States Patent
Application |
20030149416 |
Kind Code |
A1 |
Cole, Robert ; et
al. |
August 7, 2003 |
Multi-layered tampon cover
Abstract
The present invention relates to a tampon having an absorbent
structure and a multilayered cover substantially enclosing the
absorbent structure. The cover has an outer layer capable of
retaining liquid and an inner layer disposed between the outer
layer and the absorbent structure. The inner layer creates a
controlled interruption of fluid flow between the outer layer and
the absorbent structure. This interruption allows the outer layer
retains sufficient liquid to minimize vaginal wall drying prior to
saturation of the absorbent structure.
Inventors: |
Cole, Robert; (Jackson,
NJ) ; Louie, Lai-Hing; (Kendall Park, NJ) ;
Pierson, Linda M.; (Stockton, NJ) ; Yeganeh, Mary
S.; (Piscataway, NJ) |
Correspondence
Address: |
AUDLEY A. CIAMPORCERO JR.
JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
25544253 |
Appl. No.: |
10/237582 |
Filed: |
September 9, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10237582 |
Sep 9, 2002 |
|
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08997676 |
Dec 23, 1997 |
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Current U.S.
Class: |
604/383 ;
604/385.17; 604/904 |
Current CPC
Class: |
Y10S 604/904 20130101;
A61F 13/2071 20130101; A61F 13/202 20130101; A61F 13/2057
20130101 |
Class at
Publication: |
604/383 ;
604/385.17; 604/904 |
International
Class: |
A61F 013/20 |
Claims
What is claimed is:
1. A tampon comprising an absorbent structure and a multilayered
cover substantially enclosing the absorbent structure, the cover
comprising an outer layer capable of retaining liquid and an inner
layer disposed between the outer layer and the absorbent structure;
wherein the inner layer creates a controlled interruption of fluid
flow between the outer layer and the absorbent structure whereby
the outer layer retains sufficient liquid to minimize vaginal wall
drying prior to saturation of the absorbent structure.
2. The tampon of claim 1 wherein the outer layer has a first
average pore size, the inner layer has a second average pore size,
and the second average pore size is greater than the first average
pore size.
3. The tampon of claim 2 wherein the absorbent structure has a
third average pore size that is less than the second average pore
size.
4. The tampon of claim 1 wherein the outer layer comprises
materials that are more hydrophilic than the inner layer.
5. The tampon of claim 4 wherein the absorbent structure comprises
materials that are more hydrophilic than the inner layer.
6. The tampon of claim 4 wherein the inner layer comprises
materials having a contact angle with water of less than about
90.degree..
7. The tampon of claim 1 wherein the outer layer comprises a
fibrous nonwoven web having a first average denier, the inner layer
comprises a fibrous nonwoven web having a second average denier,
and the second average denier is greater than the first average
denier.
8. The tampon of claim 7 wherein the outer layer has a thickness,
the inner layer has a thickness, and a ratio of the thickness of
the outer layer to the thickness of the inner layer is between
about 1:1 to about 1:4.
9. The tampon of claim 2 wherein the multilayered cover comprises
foam material.
10. The tampon of claim 1 wherein the inner layer comprises an
apertured film.
11. A tampon comprising an absorbent structure and a multilayered
cover substantially enclosing the absorbent structure, the cover
comprising an outer layer capable of retaining liquid and an inner
layer disposed between the outer layer and the absorbent structure;
wherein the inner layer creates a spacer to disrupt fluid flow
between the outer layer and the absorbent structure in conditions
of low fluid availability whereby the outer layer retains
sufficient liquid to minimize vaginal wall drying prior to
saturation of the absorbent structure.
12. A tampon comprising an absorbent structure and a multilayered
cover substantially enclosing the absorbent structure, the cover
comprising (a) a fibrous outer layer having a first average pore
size and being capable of retaining liquid and (b) a fibrous inner
layer having a second average pore size and disposed between the
outer layer and the absorbent structure; wherein second average
pore size is greater than the first average pore size and the inner
layer creates a controlled interruption of fluid flow between the
outer layer and the absorbent structure whereby the outer layer
retains sufficient liquid to minimize vaginal wall drying prior to
saturation of the absorbent structure.
13. The tampon of claim 12 wherein the absorbent structure has a
third average pore size that is less than the second average pore
size.
14. The tampon of claim 12 wherein the outer layer comprises a
fibrous nonwoven web having a first average denier, the inner layer
comprises a fibrous nonwoven web having a second average denier,
and the second average denier is greater than the first average
denier.
15. The tampon of claim 12 wherein the outer layer has a thickness,
the inner layer has a thickness, and a ratio of the thickness of
the outer layer to the thickness of the inner layer is between
about 1:1 to about 1:4.
16. The tampon of claim 1 which further comprises an additional
layer disposed between the inner layer and the absorbent
structure.
17. The tampon of claim 1 which further comprises an additional
layer disposed between the inner layer and the absorbent structure.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to a catamenial
tampon having a multi-layered cover and an absorbent core. The
outer surface of the cover is wettable to provide a moist surface
against the vaginal wall, while inner regions of the cover disrupt
immediate liquid flow into the absorbent core. This structure
decreases the likelihood that the tampon will desiccate the surface
of the vaginal wall.
BACKGROUND OF THE INVENTION
[0002] Catamenial tampons are generally used to absorb menstrual
fluid of women during the menstrual cycle. Usually, menstrual flow
varies during the cycle, and there are often days of relatively
light flow at the beginning and end of the cycle. On light flow
days, there is little excess fluid available for a tampon to absorb
in the vaginal cavity, and conventional tampons may absorb too much
fluid, desiccating the vaginal wall or mucosa. This can cause
discomfort during the insertion and removal of these tampons.
[0003] The area of the vaginal cavity of major concern relating to
the desiccation is the upper layer of cells in the vaginal mucosa,
the squamous epithelium. Under non-menstrual conditions, the
vaginal well is lubricated by secretions that pass through the
vagina: fluids and mucus flowing from the cervix and
hormone-controlled secretions originating in the uterus. The
natural exfoliation of vaginal epithelial cells also contributes to
the natural moisture in the vaginal cavity and the squamous
epithelium.
[0004] When a conventional tampon absorbs the natural moisture from
between the cells in the squamous epithelium on light flow days of
the menstrual cycle, the cells are rendered more susceptible to
being peeled off prematurely. This peeling is called desquamation,
and it can occur in removal of the tampon prior to its saturation.
First, the initial release of an unsaturated conventional tampon
can be quite painful, as some of the squamous cells may have become
"attached" to the conventional tampon as it absorbs the natural
moisture. Next, the dry, absorbent surface of the conventional
tampon can drag along other portions of the relatively dry squamous
epithelium causing additional pain.
[0005] These conventional tampons often have a cover disposed on
the majority of the surface of the absorbent structure to contain
absorbent materials therein. An example of such a cover can be seen
in Friese, U.S. Pat. No. 4,816,100, which uses a nonwoven cover.
Several attempts have been made to improve tampon covers. One
attempt is illustrated in Jackson, U.S. Pat. No. 4,305,391, which
employs a combination of two wrapping layers to form a cover. The
outer wrap has a substantially greater pore size than the inner
wrap. Purportedly, this allows fluid to rapidly pass through the
outer wrap before it is partially absorbed and more slowly passed
through the inner wrap of the cover. This arrangement of a porosity
gradient or suction gradient is conventionally used to better
isolate fluids within the tampon to reduce reverse flow from the
absorbent core to the surface of the cover.
[0006] Another attempt to reduce the pain associated with the
removal of tampons is disclosed in Jackson, U.S. Pat. No.
4,335,722. This attempt employs a water dispersible barrier layer
around a strongly absorbent core containing superabsorbent
material. This absorbent structure is then covered with a
non-superabsorbent material, such as rayon. In this construction,
the absorbent core is utilized only after the outer layer is
saturated. Then, fluid from the saturated cover is available to
disperse the barrier layer. However, once the barrier layer is
dispersed, a conventional suction pressure gradient draws fluid
into the core from the cover.
[0007] Finally, Kaczmarzyk et al., U.S. Pat. No. 4,056,103,
discloses a fluid-permeable cover with sufficient absorbent
capacity and capillary suction to successfully compete with the
suction pressure of a superabsorbent-containing core to maintain a
soft, lubricious condition during use. Unfortunately, these three
attempts provide a conventional capillary suction pressure gradient
which strongly draws liquids into the tampon using covers which may
themselves sufficiently dry the squamous epithelium to cause pain
and trauma during use.
[0008] A different approach is disclosed in Foley et al., EP
685215, which reduces the capillary suction pressure that a tampon
exerts on the vaginal walls to remove excess menstrual fluid while
limiting the vaginal drying which can occur. This may be
accomplished by using multiple cover layers, possibly hydrophobic,
to separate the absorbent core from the vaginal wall during use.
While this advance is significant, the outer surface of the tampon
is likely to be relatively dry.
[0009] Therefore, what is needed is a tampon having reduced suction
pressure to avoid drawing too much of the natural moisture from the
squamous epithelium and which maintains a moist outer surface
throughout use to provide a non-drying tampon for catamenial
use.
SUMMARY OF THE INVENTION
[0010] Understanding the discomfort and pain associated with tampon
insertion and removal has led to the invention of a tampon which
keeps the vaginal wall naturally moist. The unique structure of
this improved cover substantially reduces vaginal drying by
maintaining the natural moisture of the vaginal wall. Additionally,
insertion and removal comfort can be further enhanced by a smooth
surface presented by the outer layer of a multilayered cover.
[0011] Thus, the present invention relates to a tampon having an
absorbent structure and a multilayered cover substantially
enclosing the absorbent structure. The cover has an outer layer
capable of retaining liquid and an inner layer disposed between the
outer layer and the absorbent structure. The inner layer creates a
controlled interruption of fluid flow between the outer layer and
the absorbent structure. This interruption allows the outer layer
to retain sufficient liquid to minimize vaginal wall
desiccation/drying prior to saturation of the absorbent
structure.
BRIEF DESCRIPTION OF THE DRAWING
[0012] FIG. 1 is a perspective view of a tampon according to the
present invention.
[0013] FIG. 2 is a cross-section along line 2-2 of FIG. 1.
[0014] FIG. 3 is an enlarged view of a portion of the cross-section
of FIG. 2.
[0015] FIG. 4 is an enlarged view of an alternative embodiment of
the present invention employing a foamed cover.
[0016] FIG. 5 is a side view of a tampon according to the present
invention during use.
[0017] FIG. 6 is a diagram of fluid flow in a tampon according to
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] Referring to FIGS. 1 and 2, the tampon 10 includes a
multilayered cover 12 substantially enclosing an absorbent
structure or core 14, and a withdrawal string 16. In the embodiment
of FIG. 1, the multilayered cover 12 does not cover a rounded
insertion end 18. However, this may be enclosed in other
embodiments. The multilayered cover 12 has at least two layers, an
outer layer 20 and at least one inner layer 22. The outer layer 20
preferably provides a smooth surface to aid in insertion and
withdrawal of the tampon 10 during use. The inner layer(s) 22
is/are constructed in a manner to create a controlled interruption
of fluid flow. The controlled interruption may be achieved by
creating a porosity gradient between the outer layer 20 and the
inner layer(s) 22 from relatively small pores in the outer layer 20
to relatively Larger pores in the inner layer(s) 22. It may also be
achieved by a relatively more hydrophilic outer layer 20 and
relatively less hydrophilic inner layer(s) 22.
[0019] In a preferred embodiment, the outer layer 20 can be formed
of relatively low denier fibers 24 which form relatively small
inter-fiber pores as shown in FIG. 3. These low denier fibers 24
are hydrophilic. There are several recognized tests to determine
hydrophilicity. One such test is the contact angle with water.
Preferably, the fibers have a contact angle in water of less than
about 90.degree.. They may be synthetic, such as synthetic
cellulosic fibers and polymeric fibers, or they may be natural,
such as cotton, wood pulp, wool, silk, and the like. Useful
synthetic cellulosic fibers include rayon and lyocell. Useful
polymeric fibers include bicomponent fibers, polyolefin fibers,
polyester fibers, polyamide (including nylon), polyacrylic, and the
like. If the fibers are not hydrophilic per se, they can be
rendered hydrophilic by appropriate treatments and/or finishes.
[0020] The inner layer(s) 22 can be formed of higher denier fibers
26 which form relatively larger inter-fiber pores as shown in FIG.
3. These higher denier fibers 26 are hydrophilic, and they may be
less hydrophilic than the low denier fibers 24 of the outer layer
20. The same general categories of fibers may be used for the inner
layer(s) 22 as those described above for the outer layer 20. Again,
if the fibers are not hydrophilic per se, they can be rendered
hydrophilic by appropriate treatments and/or finishes.
[0021] If more than one inner layer 22 is employed, the additional
layers should be compatible with the ability of the first inner
layer 22 to interrupt "fluid connectivity" between the outer layer
20 and the absorbent structure 14 as described below. Preferably,
the additional inner layers have a similar pore size or even a
greater pore size than a first inner layer.
[0022] The inner layer(s) 22 may also be formed of apertured films.
These apertured films may be two-dimensional films such as are
generally described in Mattingly, III, et al., U.S. Pat. No.
4,690,679, but preferably, they are three-dimensional films such as
are generally described in Thompson, U.S. Pat. No. 3,929,135.
[0023] The multilayered cover 12 of the present invention can be
formed by carding first web of relatively high denier fiber, such
as polyethylene/polyester bicomponent fibers, or a mixture of such
fibers with other resilient fibers such as polyester, on a moving
belt or screen. This first web will form the inner layer 22. A
second web of lower denier fibers can then be carded onto the
moving first web. This second web will form the outer layer 22. The
resulting multilayered nonwoven web can then be thermally bonded by
drawing hot air through the web and moving belt. This through-air
bonding can occur with a second restraining belt laid to
substantially enclose the multilayered nonwoven web, a double-belt
system, or in the absence of such a restraining belt, a single-belt
system. A conventional belt, e.g., 40.times.40 mesh, can be used to
carry the carded webs. However, finer mesh belts, such as
80.times.80 or 100.times.100, can produce a smoother fabric
surface, and coarser mesh belts, such as 20.times.20, can produce a
loftier fabric layer.
[0024] Different multilayered covers can be formed by combining the
inner and outer layers by lamination, thermobonding point bonding,
needle-punching, hydroentangled, adhesives, and the like. This may
be necessary to combine different, layers such as nonwoven with
apertured film, nonwoven with foam, and the like.
[0025] In an alternative embodiment, the multilayered cover 12 is
formed of a multilayered or multi-zoned foam structure 12'. In this
embodiment, the outer layer 20' has relatively narrow pores 24',
while the inner layer 22' has relatively large pores 26'. Foams of
this type can be created by optimizing and selectively controlling
the foam components and the foaming process conditions such as
viscosity, temperature, amount of blowing agent and surfactants.
The pore size gradient in foams may be more gradual than achieved
by combining separate, discrete layers. However, multiple layers of
foamed material may be combined, e.g. through lamination.
[0026] Alternatlvely, it is possible to employ an open cell foam as
only the inner layer(s) 22. Preferably, the foam has about 30 to
about 60 pores per linear inch (ppi). The foam material is not
critical to the invention, and a exemplary, non-limiting list of
useful foams may include polyurethane, poly(vinyl alcohol),
cellulose sponge, and the like. Polyurethane may be treated to
provide the desired hydrophilicity, while poly(vinyl alcohol) is
inherently hydrophilic. Such foams are commercially available
through suppliers such as Foamex of Eddystone, Pa., USA.
[0027] There are a number of available techniques useful to measure
the average pore size of a nonwoven material. These techniques
include the use of the liquid extrusion cell, developed at Textile
Research Institute, Princeton, N.J., USA. This technique has been
described in Miller et al., "An Extended Range Liquid Extrusion
Method for Determining Pore Size Distributions", Textile Research
Journal, Vol. 56, pp. 35-40 (1986), herein incorporated by
reference, and it was used to derive a mathematical model to
predict the average pore size of a nonwoven fabric, Cohen, "A Wet
Pore-Size Model for Coverstock Fabrics", Book of Papers: The
International Nonwoven Fabrics Conference, INDA-TEC'90, Association
of the Nonwoven Fabrics Industry, pp. 317-330 (1990), herein
incorporated by reference.
[0028] Based on this model, the following equation was used in the
determination of average pore sizes reported in the
specification:
r=(S.sub.ix.sub.ia.sup.-/S.sub.ix.sub.ia)((r.sub.f/xr.sub.w)-1)/t
(I)
[0029] wherein r is the average pore radius;
[0030] a is the fiber radius;
[0031] x is a number fraction;
[0032] x.sub.i is the ratio of dry fabric density to wet fabric
density;
[0033] r.sub.f is the fiber density;
[0034] r.sub.w is the dry fabric density; and
[0035] t is the tortuosity parameter.
[0036] Based upon Cohen's work, the ratio 1.2 was selected for x,
and 1.44 was selected as t.
[0037] Additional means for determining the pore sizes of the cover
layers include measuring open area via the image analysis method
described below in Example 1 and determination of "ECD" as
described in Chen et al., U.S. Pat. No. 5,037,409, herein
incorporated by reference. The most suitable measurement will be
influenced by the type and the thickness of the layers.
[0038] The multilayered cover 12 preferably has a basis weight of
about 20 g/m.sup.2 (gsm) to about 80 gsm, more preferably, about 30
gsm to about 60 gsm, and most preferably, about 35 gsm (1
ounce/yd.sup.2) to about 50 gsm. The outer layer 20 should be
sufficiently thick to provide sufficient absorbent capacity to
provide a moist surface, but not thick enough to hinder the
transfer of fluids into the absorbent structure 14.
[0039] The inner layer(s) 22 should be sufficiently thick to
provide sufficient separation between the outer layer 20 and the
absorbent structure 14 to disrupt fluid connectivity, but not thick
enough to prevent fluid connectivity when the outer layer 20
approaches or exceeds fluid saturation. Preferably, the ratio of
the thickness of a fibrous outer layer to the thickness of a
fibrous inner layer is between about 1:1 to about 1:4, more
preferably, between about 1:2 to about 1:3.
[0040] As mentioned above, the cover 12 substantially encloses the
absorbent structure 14. It is preferred that the cover 12 is
present on most of the surface of the absorbent structure 14 which
can contact the vaginal wall (V) during use. This is illustrated in
FIG. 5 which shows a tampon 10 according to the present invention
in use in an expanded state after having absorbed some menstrual
fluid. It is not necessary that the cover 12 enclose the domed
insertion end 18 or the withdrawal end 28, as these surfaces
provide minimal of the surface arca for contact between the tampon
10 and the vaginal wall (V).
[0041] The cover 12 may be physically attached to the absorbent
structure 14 or it may simply form a pouch which completely
encloses the absorbent structure 14. Examples of the former may be
by thermobonding to the outer surface of the absorbent structure
14, as disclosed in Friese, U.S. Pat. No. 4,816,100, which is
herein incorporated by reference; by embedding one end of the cover
12 into the interior of the absorbent structure 14, as disclosed in
William's.sub., WO 95/16423, which is herein incorporated by
reference; by folding at least a portion of the cover 12 around a
sliver which is wound to form the absorbent structure 14, as
disclosed in Brown, U.S. Pat. No. 5,185,010, which is herein
incorporated by reference; by wrapping the cover 12 around the
absorbent structure 14, as disclosed in Heinemann et al., U.S. Pat.
No. 5,004,467, which is herein incorporated by reference; by
needle-punching the cover 12 and absorbent structure 14 together;
and by any other method or structure which combines the cover 12
and absorbent structure 14 to form a tampon 10.
[0042] The structure of the absorbent core 14 is not critical to
the practice of the present invention. Preferably, the absorbent
core 14 is a spirally wound core as described in EP 422,660,
corresponding to U.S. Ser. No. 07/596,454, filed Oct. 12, 1990, the
disclosure of which is hereby incorporated by reference. Other
absorbent structures 14 which may be useful in the practice of the
present invention include those tampon structures commercially
available under the "TAMPAX", "PLAYTEX", and "KATE" brands. While
these tampon structures are fibrous, including natural and/or
synthetic fibers, it is also possible to use other materials in the
absorbent structure 14, including foams, sellable materials, such
as superabsorbents, and the like. Preferably, the absorbent
structure 14 contains absorbent cellulosic fibers 30 such as cotton
and/or rayon. These fibers are both absorbent and generally of low
denier or fiber cross-section to create small pores and/or
capillaries between the fibers to absorb and contain menstrual
fluid. Thus, the absorbent structure 14 strongly contains the
absorbed fluids.
[0043] It is believed that the relatively small pores in the outer
layer 20 provide a small reservoir and the relatively large pores
in the inner layer(s) 22 provide a mechanism to interrupt "fluid
connectivity" between the outer layer 20 and the main fluid
reservoir, the absorbent structure 14. This phenomenon is
illustrated in the FIG. 6. This fluid disconnection allows the
surface of the tampon 10 to quickly become substantially saturated
with a very small amount of fluid. Because the outer layer 20 does
not have a large absorbent capacity, it is not likely to dry out
the vaginal wall when used during light flow days of the menstrual
cycle.
[0044] However, it is believed that as an area of the outer layer
20 becomes saturated and substantially all of the pores in this
area become filled with fluid, a critical breakthrough point is
reached, illustrated by the arrows at (a) and (b) in FIG. 6. Just
after critical breakthrough, the fluid "overflows" into the inner
layer(s). The fluid can travel faster in the larger pores of the
inner layer(s) 22, and it can be transported directly to the
absorbent structure 14 to provide fluid connectivity between the
outer layer 20 of the cover 12 and the absorbent structure 14, as
shown by the downward arrows at (c).
[0045] In addition, if the immediate volume of the absorbent
structure 14 has already absorbed fluid, the newly received fluid
may travel along the inner layer(s) 22 of the cover 12, as shown by
the more horizontal arrows at (c), to a relatively unused volume of
the absorbent structure 14. When the fluid reaches the absorbent
fibers 30 of the core with their small interfere pores or fine
capillaries, the fluid becomes substantially "locked" into the
absorbent structure 14 at (d) in FIG. 6. As the absorbent structure
14 removes fluid from the inner layer(s) 22, the fluid connectivity
can be disrupted, and the capillary suction provided by the
absorbent structure 14 is prevented from acting directly upon the
vaginal wall (V). This process of establishing and then
interrupting the fluid connectivity between the outer layer 20 and
the absorbent structure 14 can be repeated many times during the
use of the tampon 10. Thus, it is believed that the interaction of
the outer layer 20, inner layer(s) 22 and absorbent structure 14
keeps the vaginal wall (V) naturally moist by functioning like a
pump with a check valve. When the "pump" is primed with a
continuous column or stream of liquid between the outer layer 20
and absorbent structure 14, liquid will flow into the absorbent
structure 14. However, when this process substantially drains the
inner layer(s) 22, there is a fluid disconnection. No matter how
much additional capacity the absorbent structure 14 may have,
because there is not fluid connectivity with the outer layer 20,
the structure 14 cannot pull in fluid.
[0046] The tampons of the present invention can be used with an
applicator or an inserter, or they may be digitally inserted,
without an applicator.
EXAMPLES
[0047] The present invention will be further understood by
reference to the following specific Examples which are illustrative
of the composition, form and method of producing the multilayered
cover of the present invention. It is to be understood that many
variations of composition, form and method of producing the cover
would be apparent to those skilled in the art. The following
Examples, wherein parts and percentages are by weight unless
otherwise indicated, are only illustrative.
Example 1
[0048] A commercially available tampon, o.b..TM. Super Absorbency
having a 8.5 gsm 3 denier bicomponent cover, a similarly
constructed tampon according to the present invention having a 40
gsm multilayered cover ("Tampon A"), and a similarly constructed
tampon having a 40 gsm 3 denier bicomponent cover were tested to
compare performance differences ("Tampom B"). The 40 gsm
multilayered cover had an outer layer (approximately 55 wt-% of the
cover) of 100 wt-% 3 denier bicomponent (polyethylene over
polyethylene terephthalate (PE/PET)) and an inner layer
(approximately 45 wt-% of the cover) of 66 wt-% 15 denier PET and
34 wt-% 10 denier PE/PET bicomponent fibers and was formed in a
double belt through-air bonding process.
[0049] The % Open Area can be used to estimate the relative
porosity of the two layers of Tampon A. The percent open area of
each layer was determined with a top light, photomicrography
equipment, and ImagePro.TM. Plus computer analysis program. Each
side was analyzed by focusing on the layer of interest and
adjusting the conditions to minimize interference from the other
layer. The results for the open area of the inner layer and outer
layers were 17.9% (std. de. 3.2%) and 59.3% (std. de. 5.0%),
respectively.
[0050] First, cross-sections of tampons were mounted in a rubber
mount leaving about 1 mm of the tampon exposed and examined at
75.times. magnification while synthetic menstrual fluid was added
using a Drummond Wiretral ten microliter capillary delivery system.
2-3 drops of fluid were added to each sample (each drop was about 2
microliters) and allowed to reach equilibrium within the sample.
After 5 minutes, fluid was seen in the cover outer layer of Tampon
A, and the inner cover layer was relatively clean. In contrast, the
commercial tampon and Tampon B had some fluid wicking into the
absorbent core.
[0051] In a simulation of light flow absorption, blotter paper was
wrapped around new tampon cross-sections (20 mm length) and secured
with a #8 rubber band, approximately 2 mm from the top of the
tampon sections. The upper edge of the blotter paper extended just
above the tampon section to prevent fluid overflow. Synthetic
menstrual fluid was added to the blotter paper using a 20
microliter capillary tube. First, 20 microliters was added and
allowed to be absorbed. A second 20 microliter addition of fluid
was added to saturate the blotter paper. The blotter paper was
pressed to determine whether fluid would breakthrough from the
cover to the core. Finally, an additional 20 microliters was added
to oversaturate the blotter paper. Observations of the procedure
were recorded. Neither Tampon A, Tampon B, nor the commercial
tampon absorbed fluid from the blotter paper into the core without
the external pressure. With the external pressure, the commercial
tampon cover and Tampon B wicked fluid into the absorbent core. In
contrast, the outer layer of Tampon A became filled with fluid, out
the inner layer prevented the fluid from immediately wicking into
the absorbent core. Only after the inner layer became filled with
fluid did fluid wick into the core. More pressure was required to
induce fluid to be absorbed into the core. During higher fluid
add-on levels, all three tampons exhibited similar rapid wicking of
fluid through the cover into the core.
Example 2
[0052] A 45.degree. angle run-off test was performed with a piece
of blotter paper over which a cover material was placed. Saline
fluid was introduced at a constant rate from a burette onto the
test sample until fluid ran off. The following samples were tested:
8.5 gsm 3 denier bicomponent cover (Control), 40 gsm single-belt
cover with 100 wt-% 3 denier PE/PET bicomponent fibers in outer
layer and with 50 wt-% 15 denier PET and 50 wt-% 10 denier PE/PET
bicomponent fibers in the inner layer, 40 gsm double-belt cover
with 100 wt-% 3 denier PE/PET bicomponent in outer layer and with
66 wt-% 15 denier PET and 34 wt-% 10 denier PE/PET bicomponent
fibers in the inner layer. The latter two materials are examples of
the present invention. The results are shown below:
1 Cover Cover Retention Weight Run-Off Time Capacity Cover Material
(g) (sec) (g/g) 8.5 gsm 3 d. Bico 0.10 50.0 1.1 40 gsm Single-Belt
0.40 195.7 6.5 100%/(50%/50%) 40 gsm Double-Belt 0.44 421.7 8.5
100%/(66%/34%)
[0053] A review of the results shows a significant increase in
run-off time and enhanced fluid retention capacity by the covers
according to the present invention.
[0054] The specification and examples above are presented to aid in
the complete and non-limiting understanding of the invention
disclosed herein. Since many variations and embodiments of the
invention can be made without departing from its spirit and scope,
the invention resides in the claims hereinafter appended.
* * * * *