Note: Descriptions are shown in the official language in which they were submitted.
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Tampon having Improved Early Expansion Characteristics
Field of the Invention
The present invention relates to a compressed,
radially-expanding, generally cylindrical, fibrous
tampon. These tampons rapidly expand in environments of
high humidity and provide improved early expansion
characteristics.
Background of the Invention
Catamenial tampons are used to absorb, not block
the flow of, menstrual fluids to prevent leakage, for
example, staining of a user's garments. Unfortunately,
commercial tampons are subject to two major types of
failure: a tampon's inability to continue to absorb
fluids once the absorption capacity of the tampon is
reached, and a tampon's inability to immediately expand
to fill the vaginal cavity. Thus, until the tampon
expands sufficiently to substantially fill the vaginal
cavity, menstrual fluid may flow along the tampon's side
and bypass its absorbent portions such as the core.
Generally, tampons are manufactured from absorbent
fibers, such as rayon, cotton, or a mixture of both
fibers. The volume of absorbent fibers necessary to
provide sufficient absorption capacity must be highly
compressed to form a cylindrical tampon of sufficiently
small size to allow for comfortable insertion into the
body. The compression should be adequate to hold the
tampon in the cylindrical shape until insertion. As a
result the tampon, when first inserted into the body, is
often highly compressed into a relatively non-
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conformable form with a relatively high initial density.
Thus, the tampon is not able to immediately conform to
the vaginal walls directly after insertion. The initial
high density can also inhibit the rapid expansion of the
tampon. Expansion, if it occurs at all, occurs only
when the tampon comes into contact with a sufficient
amount of menstrual fluids to swell the absorbent fibers
and to release the expansion energy locked into the
tampon when it is compressed. Thus, the tampon is
susceptible to early bypass leakage as described above.
There have been several attempts to address the
problem of early bypass leakage by providing rapidly
expanding tampons. However, these designs suffer from
two drawbacks: first, several designs are based upon
synthetic materials which are not currently widely
accepted for use in internal sanitary products, and
second, many designs have insufficient stability and
thus require the use of an applicator; they cannot be
used as digital tampons. Designs based upon synthetic
materials include those which use foams such as
Schaefer, U.S. Patent No. 3,815,601; Dulle, U.S. Patent
No. 3,794,029; and Fries et al., U.S. Patent No.
4,341,214; or resilient fibers such as Wolfe et al.,
U.S. Patent No. 4,543,098; and Gellert, U.S. Patent No.
4,475,911. Designs which require applicators include
Fries et al. and Gellert.
In addition, Walton et al., U.S. Patent No.
4,627,849, describes the use of a pre-shortened batt ;
made from natural fibers to obtain a more rapidly
expanding compressed tampon. However, this design
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requires several additional manufacturing steps to form
the pre-shortened batt.
There is a desire to avoid premature expansion of
these compressed tampons, especially those using more
resilient fibers. For example, Courtaulds PLC,
EP 0 301 874 B1, discloses a tampon having mufti-lobed
regenerated cellulose fibers which patentee claims
provide high absorbency and a cotton-like handle. These
tampons are described as having good stability and
absorbency. Longitudinally-expanding tampons having
these fibers are described as having less expansion than
conventional longitudinally-expanding tampons.
Therefore, what is needed is a radially-expanding
tampon having substantial dimensional stability prior to
use while rapidly expanding in high humidity
environments.
Summary of the Invention
Tnle have developed a tampon which can expand in the
presence of high humidity after insertion into a user's
body to prevent early bypass leakage from occurring.
This tampon is a substantially cylindrical mass of
compressed fibers enclosed within a fluid-permeable
cover. The tampon has a stability of at least about
15 N, and is capable of radially expanding upon exposure
to a humid environment. The radius increases by at
least about 10o after 15 minutes to 90'U relative
humidity at 40°°C.
i
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According to one aspect of the present invention,
there is provided a dimensionally stable tampon comprising a
substantially cylindrical mass of compress fibers
substantially enclosed by a fluid-permeable cover, the
tampon having a central axis, a radius, and a stability of
at least about 15 N and being radially expandable upon
exposure to a humid environment, wherein the radius
increases by at least about 10o after 15 minutes exposure
to 90o relative humidity at 40°C.
According to another aspect of the present
invention, there is provided the tampon as described herein
wherein a majority of the fibers are oriented in a direction
substantially perpendicular to said radius.
According to still another aspect of the present
invention, there is provided a method of forming a
compressed, radially-expanding, generally cylindrical tampon
having improved early expansion characteristics comprising
the steps of: forming a web having about 25 to 100 wt-o of
resilient staple fibers having a multi-limbed cross-section
having at least three limbs and about 0 to 75 wt-o of non-
limbed staple fibers, said web having a length dimension,
substantially perpendicular to both a width dimension and a
thickness dimension; orienting a majority of said multi-
limbed fibers substantially parallel to said length
dimension; winding a portion of said web about an axis
substantially parallel to said width dimension to form a
generally cylindrical tampon blank having a central axis,
said tampon blank having a length substantially
corresponding to the width dimension of said web;
substantially enclosing said tampon blank with a fluid-
permeable cover; and compressing said tampon blank radially
inward toward said central axis.
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According to yet another aspect of the present
invention, there is provided a method of increasing early
expansion of a compressed, radially-expanding, generally
cylindrical tampon comprising the steps of: incorporating
resilient staple fibers to provide an increase in compressed
tampon diameter by at least about loo after 15 minutes
exposure to about 90o relative humidity at about 40°C into a
web having a length dimension, substantially perpendicular
to both a width dimension and a thickness dimension, said
resilient staple fibers having a multi-limbed cross-section
having at least three limbs; orienting a majority of said
multi-limbed fibers substantially parallel to said length
dimension of said web; winding said web about an axis
substantially parallel to said length dimension to form a
substantially continuous, low density cylinder of fibers;
substantially enclosing said tampon web with a fluid-
permeable cover; compressing said cylinder of fibers
radially inward toward a central axis of said cylinder to
form a compressed cylinder; and severing a length of said
compressed cylinder to form a tampon.
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Brief Description of the Drawing
Figure 1 is a cross-section of one embodiment of a
tampon according to the present invention.
Detailed Description of the Invention
.Absorbent tampons are generally cylindrical masses
of compressed fibers having a substantially central axis
and a radius which defines the outer circumferential
surface of the tampon. Tampons are often formed by
IO first obtaining a mass of nonwoven fibers called a
tampon blank. This blank can be a rolled fibrous batt,
a segment of a fibrous tow, a mass of randomly oriented
fibers, a blank of substantially uniformly oriented
fibers, and the like.
I5 Thus, the fibers may have a number of orientations.
Rolled blanks may be formed from a carded web which is
then rolled about an axis either perpendicular or
parallel to the major axis of the web. If the web is
rolled about a perpendicular axis, a majority of the
20 fibers are oriented in a circumferential manner or
generally tangent to the tampon radius. If the web is
rolled about a parallel axis, a majority of the fibers
are oriented generally parallel to the central tampon
axis. If the blank is formed of a fibrous tow, the
25 majority of the fibers will generally be oriented
parallel to the central tampon axis.
The tampon blank is relatively uncompressed and has
a relatively low fiber density. It is often compressed ,
to form a finished product having overall dimensions
30 less than those of the blank. When pressure is released
after moderate mechanical compression, a tampon tends to
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expand toward its original dimensions. Therefore,
tampon blanks are generally over-compressed to allow
,, them to rebound slightly to the desired density for use.
Over-compression mechanically constricts expansion to
prevent the tampon from expanding without added liquid.
The over-compression of the mass of fibers which
form the tampon provides some degree of dimensional
stability, especially longitudinal crush resistance.
This measurement is generally described as the tampon's
stability. Preferably, tampons of the present invention
have a significant stability, at least about 15 N. More
preferably, the tampons have a stability of at least
about 20 N, and most preferably, they have a stability
of about 30 N to about 85 N. Tampons with a stability
which is too low do not have sufficient dimensional
stability to maintain their basic structure during
insertion as a digital tampon; tampons with a stability
which is too high can be perceived as being too stiff or
hard to be comfortably inserted as a digital tampon.
Tampons are generally categorized in two classes:
applicator tampons and digital tampons. Applicator
tampons use a relatively rigid device to contain and
protect the tampon prior to use. To insert the tampon
into a body cavity, the applicator is partially inserted
into the body cavity, and the tampon can be expelled
therefrom. Because the tampon is protected by the rigid
applicator device, the tampon need not have a high
degree of dimensional stability. In contrast, digital
tampons do not have an applicator to help guide them
. 30 into the body cavity and require sufficient stability to
allow insertion without using an applicator.
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Compressed tampons may have a generally uniform
fiber density throughout the tampon, or they may have
regions of differing density as described in the ,
commonly assigned applications to Friese et al., U.S.
Serial No. 07/596,454, and Leutwyler et al., U.S. Serial
No. 08/196,664, the disclosures of which are herein
incorporated by reference. Preferably, the tampon 10
has a relatively dense core 12 substantially surrounding
the central axis 14 and a less dense annulus 16
surrounding the core 12 and forming the outer
circumferential surface 18. This is illustrated in
Fig. 1. This density differential may be provided by
relatively uniform fiber distribution within the core 12
and annulus 16, or it may be provided by a plurality of
ribs 20 which extend radially (in the direction R) from
the core 12. In a preferred embodiment, each rib 20 is
separated from adjacent ribs where it is attached to the
core 12, i.e., at its root 22, and each rib 20 contacts
adjacent ribs, e.g., at 24, proximate the
circumferential surface 18 of the tampon. In addition,
the tampon has a cover 26.
The tampons fibers are compressible, that is, they
can be compressed to hold a generally compressed form,
but they also can expand to a relatively uncompressed
state upon exposure to sufficient moisture. This
moisture may be liquid or vapor. Preferably, the fibers
include hydrophilic fibers, and more preferably, the
fibers include absorbent fibers, i.e., individual fibers ,
absorb fluid. A useful, non-limiting list of useful
tampon fibers includes natural fibers such as cotton,
wood pulp, jute, and the like; and processed fibers such
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as regenerated cellulose, cellulose nitrate, cellulose
acetate, rayon, polyester, polyvinyl alcohol,
polyolefin, polyamine, polyamide, polyacryl onitrile,and
the Iike. Other fibers in addition to the above fibers
may be included to add desirable characteristics to the
absorbent body. For example, hydrophobic ffibers may be
used in outer surfaces of the tampon to reduce surface
wetness and hydrophilic fibers may be used to increase
the rate of fluid transport into and throughout the
body. Preferably, the tampon fibers are ra yon or
cotton, and more preferably, the fibers are rayon. The
fibers may have any useful cross-section.
Preferred fiber cross-sections include multi-limbed
and non-limbed. More preferably, the fiber s are
predominantly multi-limbed. Multi-limbed, regenerated
cellulosic fibers have been commercially available for a
number of years. These fibers are known to possess
increased specific absorbency over non-limbed fibers.
One commercial example of these fibers is the Galaxy
viscose rayon fibers available from Courta ulds PLC,
London, England. These fibers are described in detail
in Courtaulds PLC, EP 0 301 874 B1. These rnulti-limbed
fibers are described as comprising a solid filament of
regenerated cellulosic material having a de citex of less
than 5.0 and a mufti-limbed cross-section, each limb having
a length-to-width ratio of at least 2:1. The fibers are
preferably staple length fibers having thre a or four limbs
and a generally symmetrical cross-sectional shape, e.g.,
Y-. X, H, or T-shaped. A preferred cross-sectional shape is
Y-shaped
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having an angle between limbs of about 120. Preferred .
regenerated cellulosic material are viscose having a
cellulose content of 5 to 12 wt-~: and a caustic soda
A
content of 4 to 10 wt-'~:. The fibers are preferably spun
S having a salt figure of 4.0 to 12Ø It is expected
that any multi-limbed commercial fiber or even other
such fibers, not currently commercially available, would
be useful in the practice of the present invention. It
is merely required that the fibers lead to an absorbent
body having a relatively high specific absorption
capacity which is increased by the addition of a less
absorbent, non-limbed fiber to form a fibrous absorbent
body.
We have found that tampons including about 25 wt-'..
to about 100 wt-'n of the multi-limbed fibers provide the
early expansion properties of the present invention.
The fibers may be a mixture of mufti-limbed and non-
limbed fibers. Preferably, the tampon includes about 25
wt-n to about 100 wt-~ of the mufti-limbed fibers and
about 75 wt-° to about 0 wt-": of the non-limbed fibers.
More preferably, the tampon includes about 50 wt-'~> to
about 100 wt-~ of the mufti-limbed fibers and about
50 wt-øa to about 0 wt-'. of the non-limbed fibers.
Sufficient mufti-limbed fibers are included into
the tampon-forming fibrous web to provide a radial
increases of at least about 10'~ after 15 minutes
exposure to 90~ relative humidity at 40°C (90'a RH @
40°°C)_ More preferably, the tampon has a radial
increase of at least about 20after 15 minutes (90": RH
@ 40°°C), and most preferably, the tampon has a radial
increase of about 20~: to about 2S'~ after 15 minutes ( 90a.
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RH @ 40C). The tampon preferably has a radial increase
of at least about 15'~ after 30 minutes (90~. RH @ 40C),
and most preferably, the tampon has a radial increase of
about 25o to about 40a', after 30 minutes (90~<~, RH @ 40'~C)
.
The tampon preferably has a radial increase of at least
about 15'a after 45 minutes (90;, RH @ 40"C) , and most
preferably, the tampon has a radial increase of about
35~ to about 50 r, after 45 minutes (90'a, RH @ 40 C) .
The non-limbed and multi-limbed fibers are
preferably blended to a substantially uniform mixture of
fibers. These fiber blending operations are known to
those of ordinary skill in the art. For example, the
fibers can be continuously metered into a saw-tooth
opener. The blended fibers can be transported, e.g., by
air through a conduit to a carding station to form a
fibrous web. This web can be further processed to form
a tampon. In a tampon forming process, the web can be
formed into a narrow, fibrous sliver and spirally wound
to form a tampon blank. In addition, a liquid-permeable
cover material can be wrapped around the tampon blank to
substantially contain the fibrous absorbent portion of
the tampon.
During use, the tampons of the present invention
absorb moisture and liquids and radially expand. As
used in the specification and claims, the term "radially
expand" and variations of this term relate to the
expansion of generally cylindrical tampons. These
tampons expand primarily in a direction perpendicular to
the central axis of the tampon. Preferably, the tampons
expand in at least one direction perpendicular to the
central axis, more preferably, at least two directions.
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Most preferably, the tampons expand substantially
uniforml y in all directions perpendicular to the central
axis.
The tampon blank is substantially enclosed by a
fluid-permeable cover. Thus, the cover encloses a
majority of the outer surface of the tampon. This may
be achieved as disclosed in Friese, U.S. Patent No.
4,816,100. In addition, either or both ends of the tampon
may be enclosed by the cover. Of course, for processing or
other reasons, some portions of the surface of the tampon
may be free of the cover. For example, the insertion end of
the tampon and a portion of the cylindrical surface adjacent
this end may be exposed, without the cover to allow the
1S tampon to more readily accept fluids.
The cover can ease the insertion of the tampon into
the body cavity and can reduce the possibility of fibers
being separated from the tampon. Useful covers are
known to those of ordinary skill in the art. They may
be selected from an outer layer of fibers which are
fused together (such as by thermobonding), a nonwoven
fabric, an apertured film, or the like. Preferably, the
cover has a hydrophobic finish.
Examples
Example 1
A series of fibrous webs were formed by adding a
measured amount of multi-limbed regenerated cellulosic
staple fibers (Galaxy fibers, 3.3 denier, rayon fibers,
available from Courtaulds Fibres, London, England) and
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non-limbed regenerated cellulosic staple fibers
(Danufil~ fibers, 3.6 denier, rayon fibers, available
from Hoescht Kehlheim, Kehlheim, Germany). The fiber
components were weighed using a component scale, mixed
together in a bale breaker and subsequently opened in a
saw-tooth opener. The resulting blend was carded to
obtain the fibrous web. These webs were then used to
manufacture compressed, radially-expanding, generally
cylindrical tampons according to the process of the
commonly assigned, applications to Friese et al., U.S.
Serial No. 07/596,454, and Leutwyler et al., U.S. Serial
No. 08/196,664, and covered according to the process of
Friese, U.S. Patent No. 4,816,100. These tampons were
conditioned at 65« RH @ 21C for at least 24 hours and
the initial diameter was measured. fihe composition and
initial diameter of these tampons are identified below
in Table 1. The standard deviations of the diameter are
included in parenthesis.
Table 1
a
Test Sample Avg. Wt-'-: Wt-'~>
Product Size Diameter Galaxy Rayon
(n) (mm) ('~) ('~)
Comp. Ex. A 5 13.20 (0.17) 0 100
Ex. B 5 13.50 (0.17) 100 0
Ex. C 5 13.46 (0.13) 75 25
Ex. D 5 13.38 (0.12) 50 50
Ex. E 5 13.20 (0.14) 25 75
The conditioned tampons re then placed into a high
we
humidity environment relative humidity 40"C).
(90'a. at
During this expo sure, the tampon diameter was measured
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at 15 minute intervals. The results are illustrated
below in Table 2. Again, the standard deviations of the
diameter measurements are included in parenthesis.
Table 2
Test Diameter at:
Product 15 Min. 30 Min. 45 Min. 60 Min.
(mm) imm) (mm) (mm)
Comp. 13_83 14.30 14.52 15.09
Ex. A (0.66) (0.27} (0.37) (0.24)
Ex. B 16.83 18.15 19.36 20.06
(0.73) (1.00) (0.85) (0.63)
Ex. C 16.06 17.40 18.79 29.91
(0.27) (0.69) (0.39) (0.39)
Ex. D 15.97 17.42 18.60 19.76
(0.54) (0.50) (0.48) (0.30)
Ex. E 14.45 14.97 15.19 15.10
(0.22) (0.47} (0.34) (0.32)
From these data, it can be seen that the incorporation
of multi-limbed rayon fibers increases the early
expansion of a compressed tampon in a high humidity
environment over a compressed tampon which does not
include such fibers. It should be noted that the
tampons do not take up a significant amount of fluid
during this experiment (approx. 0.1 g/tampon after 60
min. ) .
Example 2
A series of fibrous webs having 75 wt-'~ Galaxy
fibers and 25 wt-a;~ Danufil~~ fibers were formed as in
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Example 1 above. The fibrous webs were then formed into
tampon blanks and compressed. Three different tampon
blank styles were formed: folded, rolled, and cut. To
form the folded blank, a section of about eight times
the length of the tampon blank was folded back and forth
at five fold lines, perpendicular to the length of the
web. Each fold line was separated by the length of the
tampon blank. Thus, the tampon blank had two raw cut
edges and two fold lines at one longitudinal edge
thereof and three fold lines at the opposite
longitudinal edge, and a major portion of the fibers was
oriented substantially parallel to the central axis. To
form the rolled blank, a section of fibrous web was
wound about a central axis. Thus, a major portion of
the fibers was oriented substantially circumferentially.
To form the cut blank, the intermediate fold lines of
the folded blank were replaced by cut lines. Thus, the
tampon blank had six raw cut edges at each longitudinal
end thereof, and a major portion of the fibers was
oriented substantially parallel to the central axis.
These tampon blanks were further processed to form
tampons and conditioned as described above. The
composition and initial diameter of these tampons are
identified below in Table 3. The standard deviations of
the diameter are included in parenthesis.
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Table 3
Test Sample Avg. Tampon Blank
Product Size Diameter Type
(n) (mm)
Ex. F 6 13.24 (0.26) Folded
Ex. G 6 13.12 {0.13) Rolled
Ex. H 6 13.25 (0.10) Cut
Again, the conditioned tampons were placed into a high
humidity environment (90 a' relative humidity at 40°C).
During this exposure, the tampon diameter was measured
at 15 minute intervals. The results are illustrated
below in Table 4. Again, the standard deviations of the
diameter measurements are included in parenthesis.
Table 4
Test Diameter at:
Product 15 Min. 30 Min. 45 Min. 60 Min.
(mm) (~) (~) (~)
Ex. F 14.76 15.81 16.27 16.57
(0.88) (0.96) {1.00} (1.04)
Ex. G 15.32 16.18 16.43 16.84
(0.18) (0.44) (0.28} (0.38)
Ex. H 15.54 16.31 16.60 16.93
{0.29) (0.75} {0.14) (0.19)
From these data, it can be seen that the compressed
tampons of the present invention exhibit the early
expansion in a high humidity environment whether the
fibers are oriented circumferentially or longitudinally.
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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.
~. . , t
