Note: Descriptions are shown in the official language in which they were submitted.
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m '~.'l~IMPON APPLICATOR HADING ROLLED GRIPPER
a d "f the Invention
Tliis invention relates to a method of fabricating
paperboard tampon applicators having a diameter of less
than about 25 mm which have an outwardly rolled finger
grip.
aak round of the Invention
P~lperboard tampon applicators which include a pair of
telescoping cylinders are well known in the art. For
example:, Wiegner et al., U.S. Patent No. 4,412,833;
Beastal..l et al., U.S. Patent No. 5,087,239; Hinzmann, U.S.
Patent No. 4,755,164; Huffman, U.S. Patent no. 4,573,964;
Whitehs=ad, U.S. Patent No. 4,508,531; all teach various
aspects. of these applicators.
Tampon applicators, whether paperboard or plastic,
generally incorporate surface features at the rear or
gripper end to allow the user to more or less securely
hold tt~e applicator while ejecting the tampon from the
opposite end of the applicator. While plastic applicators
can ger..erally have pronounced gripper ends by nature of
their fabrication, the gripper end configuration of
paperboard applicators is more limited. For example,
Wiegner et al. teaches a lightly grooved grip; Beastall et
al., teaches a series of more pronounced grooves forming
rings iz~ the gripper end; Hinzmann discloses both a grip
area having a reduced diameter and surface indentations;
and Whitehead and Huffman both teach finger grip areas
' 30 having :>>ubstantially reduced diameter. Each of the finger
grips t,~3ught in this prior art has a limited ability to
prevent finger slip during ejection of the tampon.
Pay>erboard applicators have been limited by the
SUBSTITUTE SHEET (RULE 26)
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amount of deformation accepted by the paperboard ,
applicator stock before it is destroyed by the grip-
forming process steps. Therefore, the finger grip areas
are generally only formed with minimal raised rings or
grooves.
In view of the shortcomings of the prior art, what is
needed is a paperboard tampon applicator which has
increased distortion of the tampon applicator stock to
provide for more pronounced finger grips.
.. summary of the Invention
The present invention relates to a method of forming
an improved finger grip at the gripper end of a tampon
tube. This gripper end has an outwardly rolled edge
produced by applying moisture to the gripper end of the
paperboard tube having a diameter of less than about 25
mm, heating a forming tool to about 100 °F to about 350 °F,
rotating the paperboard tube with respect to the forming
tool, preferably at a rate of about 10 to 1000 rpm, and
- 20 contacting the gripper end of the paperboard tube with the
forming tool for about 0.2 to about 5 seconds. In this
manner, the forming tool rolls the gripper end of the
paperboard tube outwardly to form a radiused surface at
the outside of the gripper end of the paperboard
applicator tube.
The present invention works well with paperboard
tampon tubes which are formed either by the spiral winding
of paper and/or cardboard layers to form a continuous tube
or by the rolling of relatively rectangular, paperboard
,_.
tube blanks. The more pronounced finger frip allows the
use of slicker coatings on the applicator tube surface.
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According to one aspect of the present invention,
there is provided a method of forming an outwardly rolled
edge on a gripper end of a paperboard tampon applicator
tube, the method comprising the steps of: applying moisture
to the gripper end of the paperboard tube having a diameter
of less than about 25 mm; heating a forming tool to about
37,7°C to about 176,7°C; rotating the paperboard tube with
respect to the forming tool in order to provide at least one
rotation of the tube during the formation of the rolled
edge; contacting the gripper end of the paperboard tube with
the forming tool for about 0.2 to about 5 seconds; whereby
the forming tool rolls the gripper end of the paperboard
tube outwardly to form a radiused surface at the outside of
the gripper end of the paperboard applicator tube.
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Brief Description of the Drawing
Figure 1 illustrates a paperboard tampon applicator
having outwardly rolled gripper ends.
:Figure 2 illustrates an enlarged cross-section along
line .2-2 of Figure 1.
:Figure 3 illustrates an enlarged cross-section of the
, lamin,xted tube stock which is used in a preferred
embodiment.
h'igure 4 illustrates the moistening of the gripper
end oi: a tube in preparation for the edge rolling process.
l:~igures 5A-5C depict the sequence of forming the
outwa~vdly rolled edge in a tampon applicator barrel.
etai7ed Description of the Invention
~teferring initially to Figs. 1 and 2, the tampon
applicator 10 includes at least one tube 12 having an
eject~_on end 14 and a gripper end 16. The tube 12 has an
outwardly rolled edge i8 at its gripper end 16. In use,
the b~:rrel 12 of a tampon applicator 10 is generally held
betweE:n a user's thumb and middle finger, while the
plunger 20 is manipulated by the user's index finger. The
rollec.. edge 18 forms a flange at the end of the barrel 12
which helps to keep it from slipping through the user's
finger as the plunger 20 is pushed into the barrel 12. Of
course, the plunger 20 may also be formed of a paperboard
tube avnd may include an outwardly rolled edge 22 at its
gripper end 24.
P.eferring now to Figs. 4 and 5A-5C, a previously
formed tube 100 having a diameter of less than about 25 mm
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is seated in a collet device 102 which holds the tube 100
firmly in place while also providing a stop 104 to allow
the correct seating depth. The collet 102 holding the
tube 100 is then rotated to provide for at least one
rotation of the tube 100 during the formation of the
outwardly rolled edge. Thus, if it takes about one second
to form a rolled edge from tube-to-forming tool contact
until the edge is fully rolled, without any additional
dwell time, the collet device 102 would rotate at a speed
of at least about 60 rpm. Under preferred applicator
forming conditions, the collet device 102 would rotate at
a speed of about 10 rpm to about 1,000 rpm, more
preferably about 50 rpm to 500 rpm, and most preferably
about 100 rpm to 380 rpm.
Moisture 106 is applied to the tube 100 in the region
of the gripper end 108 to help to soften the fibers in the
_, rolling zone 110 to reduce material splitting. The
'' moisture 106 is preferably applied after the collet 102 is
rotated, but moisture 106 may also be applied before the
tube 100 is rotating on the collet 102. Moisture 106 can
be applied as a fine mist of water, steam, water spray,
dipping into an aqueous bath, and the like. It is
preferred that about 5 to 50 mg of moisture is added to
the tube 100 at the gripper end 108 to facilitate the edge
rolling procedure. More preferably, about 10 to 30 mg,
_ arid most preferably, about 10 to 20 mg of moisture is
added to the tube 100.
The moistened tube 100 which is rotating in the
collet device 102 is then brought into contact with a
..
,
stationary forming tool 112 (Figs. 5A-5C). Preferably,
the collet device 102 is moved toward the forming tool 112
::
at. about 2.5 cm/sec to about 11.5 cm/sec. In a
particularly preferred embodiment, the collet device 102
is moved toward the forming tool 112 at about 6 cm/sec.
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The forming tool 112 may be heated to about 100 F to about
350 F, preferably about 200 F to 250 F, and more
. preferably about 225 F. After the tube 100 contacts the
forming tool 112 (Fig.5B), the collet device 102 continues
to mve toward the forming tool 112, thereby feeding a
sufficient length of the rolling zone 110 of the tube 100
into the forming tool 112 to roll the gripper edge 108 of
the tube 100 outwardly to form a finger grip flange 114.
The exact amount of tube 100 which is fed into the forming
tool 112 will generally depend on the radius of the rolled
edge 114, which will be recognized by the ordinarily
skilled practitioner. When the collet device 102 reaches
its n~.aximum extension toward the forming tool 112 (Fig.
5C), it may be held for about 0.25 to about 3 seconds to
set the rolled shape 114.
.After the desired forming time has been reached, the
collet device 102 is retracted from the forming tool 112
and tie finished tube 100 is ejected from the collet 102.
While the invention is herein described with reference to
a stationary forming tool 112 and rotating, moving collet
device 102 holding the tube 100, the invention also
functions with other combinations as long as the relative
rotation and movement between the tube 100 and forming
tool 112 are maintained. The resulting rolled edge 114
can h,,ive a radius of about 0.5 to 2 mm, preferably about
0.75 ~~~o about 1.25 mm, and most preferably, about 1 mm.
'.;the heat of friction caused by rotating the tube 100
with respect to the forming tool 112 along with the
appli<.:d heat tend to drive off the applied moisture 106
in
the r~~lling process. In addition, the heating step also
stabi:~_izes the rolled shape 114. Finally, it is helpful
a
to dr:we off all applied moisture 106 in order to reduce
the likelihood of the applicator tube fostering the growth
of undesirable microorganisms. Such growth can be
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detrimental to the health of the user of the tampon
applicator.
The forming tool 112 preferably has a low friction
surface where the tube edge 108 is rolled. This surface
can be a highly polished surface, such as stainless steel,
a tef lon-coated surf ace., and preferably, a tef lon-coated
stainless steel surface. Additional lubrication provided,
e.g., by wax and other known lubricants can also improve
the edge rolling process.
In a particularly preferred embodiment, a cardboard
barrel and plunger are fabricated by laminating a waxed
paper layer 200 to a cardboard layer 202 to provide
applicator stock 204 having a thickness of about 0.3 to
0.4 mm. The barrel and plunger may then be formed into a
tube having wax outer surface and a longitudinal seam, as
described, for example in EP-A-0 581 136, or U.S. Patent
No. 4,755,164. Of course, this invention may
also be used with spiral-wound tubes. The barrel and
plunger tubes which are formed have an inside diameter of
about 14.5 and 13 mm, respectively. Generally, the
plunger will have a smaller diameter than the barrel in
order to be accommodated within the barrel. We have found
that we can form outwardly rolled edges on tubes having an
inside diameter of less than about 25 mm, preferably about
10 to 20 mm, and most preferably, about 11 to 18 mm. The
gripper ends of both the barrel and plunger tubes may then
be rolled according to the present invention to result in
the tampon applicator illustrated in Fig. 1 wherein a
tampon pledget is enclosed in the barrel.
The useful paperboard stock for the formation of the
applicator tubes will be recognized by the skilled
artisan. A representative, non-limiting list of such
stock includes paperboard, cardboard, cup stock, paper,
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and the like. The stock can have a thickness of about 0.2
to 0.5 mm. This stock may be laminated or coated with a
cover layer to provide a smoother outer surface to the
tampc.n applicator tube. The cover layer may have a
thickness of about 0.01 to 0.1 mm. A representative, non-
limiting list of such cover layer material includes wax,
plastic, and the like. A representative, non-limiting
list of plastic material includes polyolefins such as
polyethylene and polypropylene, polyesters such as
polyethylene terephthalate, cellophanes, nitrocelluloses,
and tze like.
''Che specification and embodiments above are presented
to ai~~ in the complete and non°limiting understanding of
the invention disclosed herein. Since many variations and
embod:~ments of the invention can be made without departing
from ,its spirit and scope, the invention resides in the
claim:: hereinafter appended.
