U.S. patent number 3,625,787 [Application Number 04/849,119] was granted by the patent office on 1971-12-07 for method of attaching withdrawal string to a sponge tampon.
This patent grant is currently assigned to Kimberly-Clark Corporation. Invention is credited to Michael Deane Radl, Edward E. Werner.
United States Patent |
3,625,787 |
Radl , et al. |
December 7, 1971 |
METHOD OF ATTACHING WITHDRAWAL STRING TO A SPONGE TAMPON
Abstract
A method for economically and efficiently securing a withdrawal
string to a regenerated cellulose sponge tampon in the manufacture
of menstrual tampons. A string which includes a heat-reactive
adhesive element is inserted into a sponge tampon, and sonic energy
is then applied to the tampon to provide a rapid and highly
localized heating of the adhesive element, causing it to flow into
intimate contact with the surrounding sponge material and form a
secure bond between the string and sponge when cooled. The
disclosure alternatively shows a means for simultaneously applying
an adhesive substance to a string as it is being drawn into a
sponge tampon so that an adhesive coating is applied only to the
portion of the string contained within the tampon.
Inventors: |
Radl; Michael Deane (Appleton,
WI), Werner; Edward E. (Oshkosh, WI) |
Assignee: |
Kimberly-Clark Corporation
(Neenah, WI)
|
Family
ID: |
25305107 |
Appl.
No.: |
04/849,119 |
Filed: |
August 11, 1969 |
Current U.S.
Class: |
156/73.2;
156/580.1; 604/11 |
Current CPC
Class: |
A61F
13/26 (20130101); A61F 13/2085 (20130101); B29C
65/524 (20130101); B29C 66/69 (20130101); B29C
66/71 (20130101); B29C 66/72 (20130101); B29C
65/54 (20130101); B29C 66/729 (20130101); B29C
66/71 (20130101); B29C 65/08 (20130101); B29K
2001/00 (20130101); B29C 66/832 (20130101); B29C
66/9513 (20130101); B29L 2031/753 (20130101); B29K
2105/0085 (20130101); B29K 2105/0097 (20130101); B29C
65/4815 (20130101); B29K 2023/06 (20130101); B29K
2031/04 (20130101) |
Current International
Class: |
B29C
65/00 (20060101); B29C 65/54 (20060101); A61F
13/20 (20060101); A61F 13/26 (20060101); B29C
65/08 (20060101); B29C 65/52 (20060101); B29C
65/48 (20060101); B29c 027/08 (); A61f
013/20 () |
Field of
Search: |
;156/73
;128/270,285 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
R S. Soloff, "New Concepts in Ultrasonic Sealing" Modern Plastics,
March, 1964.
|
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Doramus; James V.
Claims
The following is claimed as invention:
1. A method of securing a withdrawal string to a tampon of dry,
expanded, fine-pore, regenerated cellulose sponge in the
manufacture of menstrual tampons, comprising the steps of inserting
a string into said sponge tampon by drawing the string through the
tampon with a hollow needle so that a portion of the string is
contained within said tampon and a portion extends outwardly of the
tampon, simultaneously supplying a heat-reactive adhesive substance
to said string as it is being inserted into said tampon by passing
said adhesive substance through the interior of said needle in a
fluid state and extruding said adhesive substance into the tampon
as the string is drawn by the needle, placing said tampon with said
inserted string adjacent an ultrasonic energy source, and directing
sonic energy into said tampon to heat said adhesive substance to a
temperature sufficient to cause it to bond with the surrounding
sponge while not decomposing the sponge tampon.
2. The method of claim wherein said adhesive is applied only to the
portion of said string which is inserted into said tampon.
3. The method of claim 1 wherein said adhesive substance is a hot
melt adhesive material.
4. The method of claim 1 wherein said adhesive substance is a fluid
dispersion including a carrier solvent causing the remaining
adhesive element to securely bond said string to the tampon.
5. The method of claim 1 wherein said sonic energy has at least
20,000 cycles per second.
Description
DESCRIPTION OF THE INVENTION
The present invention relates generally to absorbent menstrual
tampons and the like, and more particularly to an improved method
of making such tampons.
Some prior menstrual tampons have been made of fibrous material,
and the withdrawal string has been sewn to the tampon. With tampons
made of sponge, however, sewing the withdrawal string to the tampon
decreases the efficiency of the sponge. Heretofore, various methods
have been proposed for attaching the withdrawal string to sponge
tampons without sewing, such as by using glues or heat sealable
thermoplastics. These prior methods, however, often have been
ineffective in reliably securing the withdrawal string have
required heating of the entire sponge to the fusion temperature of
the heat sealable thermoplastic often charring or damaging the
sponge, or have required equipment that is relatively expensive or
inefficient.
Accordingly, it is an object of the present invention to provide an
improved method for economically and efficiently securing a
withdrawal string to a sponge tampon in the manufacture of
menstrual tampons.
Another object is to provide a method for reliably bonding a
withdrawal string to a sponge tampon by means of a heat-reactive
substance wherein there is less tendency of charring or decomposing
the sponge during the heating process. More particularly, an object
is to provide such a method which utilizes an energy source adapted
to create a highly localized heating of the adhesive without
heating the entire sponge tampon to the fusion temperature of the
adhesive.
A further object is to provide a method of the foregoing type which
more efficiently utilizes energy in the heating process and
requires equipment that is relatively inexpensive.
Still another object is to provide a method for adhesively bonding
a withdrawal string to a sponge tampon without contaminating or
coating the outwardly extending handle portion of the string with
the adhesive. In this connection, it is an object to provide a
method and means for simultaneously applying an adhesive substance
to the string as the string is being inserted into the sponge
tampon.
Other objects and advantages of the invention will become apparent
from the following description taken in conjunction with the
accompanying drawings, in which:
FIG. 1 is a perspective and partial sectional view of an
uncompressed sponge tampon with a string having an adhesive coating
being inserted longitudinally through the tampon by an appropriate
needle;
FIG. 2 is an enlarged fragmentary cross section of the string and
tampon shown in FIG. 1.
FIG. 3 is a perspective of the tampon shown in FIG. 1 with the
string fully positioned in the tampon;
FIG. 4 is a schematic side elevation of an apparatus for applying
heat to the string and tampon assembly shown in FIG. 3 in bonding
the string to the tampon; and
FIG. 5 is a section view of an alternative means for inserting a
string into a sponge tampon, which simultaneously applies an
adhesive substance to the string as it is drawn into the
tampon.
While the invention is susceptible of various modifications and
alternative forms, certain specific embodiments thereof have been
shown by way of example in the drawings which will be described in
detail herein. It should be understood, however, that it is not
intended to limit the invention to the particular forms disclosed
but, on the contrary, the intention is to cover all modifications,
equivalents, and alternatives falling within the spirit and scope
of the invention.
Turning to the drawings, FIG. 1 shows an elongated sponge tampon 10
preferably formed of dry, fine-pore, expanded, regenerated
cellulose material and shaped to a typical tampon length. While the
illustrated tampon 10 has a cylindrical form with a polygon cross
section, it will be understood that various other well-known shapes
may be employed. As will be explained below, the tampon 10, which
is shown in its uncompressed fully expanded state, subsequently may
be radially and longitudinally compressed in forming the desired
finished shape and be of a size adapted for easy insertion into the
vaginal tract.
A withdrawal string 11 is shown in FIG. 1 being inserted into the
tampon 10 by passing a needle 12 longitudinally through the tampon.
The needle 12 has a barbed end 14 to which one end of the string 11
is attached. By passing the needle completely through the tampon
and unhooking the string, the string remains coaxially positioned
along the entire length of the cylindrical tampon. The string may
then be cut, or may be precut to the required length, so that a
portion 15 remains extending outwardly from the tampon to serve as
a withdrawal string handle. The string at this point, however, is
not bonded to the tampon.
To facilitate subsequent bonding of the string 11 to the tampon 10
in the illustrated method, the string, or at least the portion of
the string which is to be inserted into the tampon 10, includes a
heat-reactive bonding element 18. The bonding element 18 may be a
thermoplastic adhesive which is previously applied to the string by
dipping the string into the adhesive, or by other well-known
applicator means. When the adhesive is cooled to room temperature,
it solidifies and forms the uniform coating 18 surrounding, or
impregnating and surrounding, the string as shown in FIG. 2. The
thermoplastic adhesive should have a sufficiently high melting
point that it is not melted or sticky at body temperature or
slightly above, and is not soluble in menstrual fluid. Thus, the
entire string may be coated with the adhesive if desired.
A typical mercerized cotton string impregnated and coated with a
thermoplastic adhesive such as a composition of 50 percent Elvax 40
- 50 percent Elvax 150 (Elvax is a copolymer of ethylene and vinyl
acetate) has been found to form a highly satisfactory string for
use in the process of the present invention, although other
suitable thermoplastic adhesives may be used. Other nonfusible
yarns or strings made of linen, hemp, regenerated cellulose, rayon
or the like, can be combined with thermoplastic adhesives.
Synthetic yarns of material with a melting point lower than the
adhesive may also be used. While the thermoplastic adhesive
coatings should not fuse or lose bonding strength at human body or
commercial storage temperatures, it will be appreciated that they
should be readily fusible at higher temperatures to which the
regenerated cellulose sponge tampon can be heated without
decomposing the sponge. It should be noted that the string is the
force carrier, i.e., the string should be strong enough after
processing to be able to withdraw the tampon without breaking, and
the thermoplastic coating is the adhesive agent that does the
bonding. The string properties must be of such composition that it
fulfills its force carrier relationship with the ultrasonic
process, i.e., there exists a differential temperature between the
string and the adhesive such that the string will not melt, char,
decompose or lose strength during the string coating or ultrasonic
attachment process. In addition, the thermoplastic coating provides
a protective coating that prevents exudate from soaking through it
during use.
In accordance with the invention, a sonic energy source is provided
for rapidly, efficiently, and economically heating the
heat-reactive bonding element surrounding the portion of the string
inserted within the sponge tampon. Sonic energy is directed into
the sponge tampon to create a nearly instantaneous and highly
localized heating of the adhesive coating causing it to become
fluid and flow into intimate contact with the adjacent fine pores
of the regenerated cellulose sponge tampon. Subsequent cooling and
solidifying of the adhesive creates a secure bond between the
string and the sponge. In the illustrated embodiment, the tampon 10
with the inserted adhesively coated string 11 is positioned on an
upper surface 20 of an anvil 21 immediately below a sonic energy
source, generally indicated at 22. The energy source may be
designed with a frequency which may vary from a few thousand cycles
per second up to perhaps one million cycles per second or more.
However, to minimize the problem of audible noise and to provide an
efficient source of energy, it is preferred to employ an ultrasonic
energy source that is capable of providing at least 20,000 cycles
per second. Typically, the energy source 22 may be of a
conventional type, including a power supply 24 capable of providing
necessary electrical energy and a converter 25 for converting the
electrical energy into mechanical energy in the form of vibrations.
The converter 25 may be a piezoelectric element made of material
such as barium titanate or lead zirconium titanate.
A horn 26 is employed to transmit the mechanical vibrations from
the converter 25 to the sponge tampon 10. The horn 26 may have
various masses and shapes depending upon the output oscillations
desired and the configuration of the tampons being heated. To
facilitate uniform heating of the string, the horn may have a
narrow elongated end surface, such as the surface 28, which can be
placed on the tampon directly over a substantial portion of the
string contained within the tampon. The horn 26 is adapted to be
brought into position so that its end 28 bears firmly against the
tampon 10 with a prelocated pressure preferably of between 20 to 40
lbs. The energy source 22 thus provides, within the region of the
horn, an intense highly localized zone of sonic energy.
During a controlled period of time that the horn is in contact with
the tampon, high frequency mechanical vibrations are transmitted
from the horn into the sponge tampon. The vibrations travel through
the sponge until they reach the juncture of the string and sponge
surfaces. The intense vibration of one surface moving against the
other at high frequencies creates a sufficient buildup of heat
through friction to cause the adhesive surrounding the string to
melt and readily flow into the adjacent sponge pores. The
temperature created by the sonic energy at the juncture of the
string and sponge, which may be regulated by the time interval the
horn is in contact with the tampon and by its frequency output,
should be sufficient to melt and set the adhesive substance but not
char or burn the cellulose sponge. Generally, a temperature of less
than 450.degree. has been found to be satisfactory. Since the sonic
energy creates highly localized heating at the string and sponge
juncture, the entire sponge generally does not reach the fusion
temperature of the adhesive so that there is less tendency of
damaging the sponge during the heating process. After the adhesive
is cooled, a secure bond is created between the string and sponge
which will withstand the stresses of commercial storage conditions,
immersion in menstrual fluid, and the force required to remove the
wet, used tampon from a vagina.
It will be appreciated that the use of sonic energy in the method
of the present invention has several advantages over prior methods.
First, such energy is adapted to create rapid and highly localized
heating which quickly activates the adhesive in setting the bond
between the string and the sponge material. In addition, sonic
energy may be utilized much more efficiently than other energy
sources since a high percentage of the output energy from a sonic
energy source is converted to heat generated vibrations in this
application and the heat is concentrated at the location of the
string without heating the entire sponge to the adhesive fusion
temperature.
While in the illustrated embodiment the bonding element of the
string was a thermoplastic adhesive coating, alternatively
thermoplastic fibers could be combined with nonthermoplastic yarn
in forming the string. Thermoplastic fibers, such as vinyon fibers,
may be twisted in a strand and then wound around the
nonthermoplastic yarn, such as rayon or cotton, in a "barberpole"
fashion. Also the thermoplastic material can be interwoven with a
nonthermoplastic material. The application of sonic energy to such
a string inserted in a sponge tampon will thermally fuse or melt
the thermoplastic fibers sufficiently that they will bond to both
the regenerated cellulose sponge and the rayon or cotton yarn. The
yarn will continue to provide tensile strength to the string.
Referring now to FIG. 5, there is shown still another alternative
way of applying a bondable adhesive to the withdrawal string. In
the embodiment, an adhesive substance is applied to the string at
the same time the string is being inserted into the sponge. To this
end, there is shown a hollow needle 30 having a barbed end 31
drawing a nonfusable string 32, preferably made of rayon or cotton
yarn, through an expanded, regenerated cellulose sponge tampon 34.
As the string 32 is drawn into the sponge tampon 34, a
heat-reactive adhesive substance is directed by known means through
the hollow needle 30 and is extruded out openings 36 in the side of
the needle 30 to coat the surrounding area inside the sponge and
the string 32 as it is advanced through the sponge. The adhesive
substance may be thermoplastic adhesive material of the type
described above which cools and solidifies after being inserted
into the sponge to create at least a temporary bond between the
string and the porous cellulose sponge. The subsequent application
of sonic energy to the sponge tampon 34 in the above-described
manner will again melt the adhesive 35 and cause a further flow of
the substance into the surrounding sponge pores to insure bond
between the string and the sponge when the adhesive finally
solidifies.
As an alternative to extruding a thermoplastic adhesive in the
embodiment of FIG. 5, various solvent system adhesives may be used.
In such case, the adhesive solution similarly is directed out of
openings 36 in the needle and coats the string being drawn through
the sponge and the surrounding area. When sonic energy subsequently
is directed into the tampon sponge, the generated heat drives off
the solvent and leaves an adhesive residue which sets and securely
bonds the string to the adjacent sponge material.
It will be understood that after the withdrawal string has been
bonded to the expanded, regenerated, cellulose sponge tampon, the
sponge tampon may be radially compressed by known means up to 50
percent of its diameter to shape the tampon to a final desired
configuration. The finished tampon may then be placed into an
appropriate applicator tube or dispenser Thus, the expanded sponge
tampon may initially have any desired elongated shape which
facilitates its handling during the string insertion and heating
manufacturing steps. It will also be appreciated if the final
compressing of the expanded cellulose sponge tampon follows
immediately after the heating step, the compressive force will aid
in the formation of a strong permanent bond between the withdrawal
string and the sponge when the adhesive is cooled to room
temperature.
It will further be apparent to those skilled in the art that other
variations from the examples given may be employed without
departing from the spirit of the present invention. For example,
instead of inserting a string into a cellulose sponge tampon by
means of the needle, a tampon made of laminated layers of cellulose
sponge could be used with the adhesively coated withdrawal string
being interposed between the sponge layers. Moreover, while in the
illustrated method a single string was inserted into a single
tampon, alternatively, a plurality of parallel strings could be
inserted into a single sponge layer and sonic energy could be
applied to the entire layer to simultaneously bond all the strings
to the sponge. The sponge layer could then be cut into individual
tampons, each containing a single withdrawal string. While the
process is particularly useful for use in the manufacture of
cataminial devices it is readily adapted to string attachment to
absorbent devices for other uses.
* * * * *