Note: Descriptions are shown in the official language in which they were submitted.
CA 02584194 2007-04-10
#454992
TAMPER-EVIDENT CLOSURE
BACKGROUND OF THE INVENTION
The present invention relates in general to an internally-threaded closure for
a container with an externally-threaded neck, wherein the closure includes a
tamper-evident band. The tamper-evident band is initially attached to an upper
body portion of the closure by a plurality of frangible elements or by a
weakened
score line in the form of a severable web. Once the frangible elements are
broken,
the upper body portion separates from the tamper-evident band and provides a
closing cap for the container. More specifically, the present invention
relates to
this style of internally-threaded closure where the tamper-evident band is
constructed and arranged to be retained on the neck of the container at the
time of
closing cap removal, after breaking the frangible elements or severing the
web. As
the upper body is unscrewed from the container neck, the tamper-evident band
stays connected to the neck and the frangible elements break, or the web
severs,
separating the upper body portion (now the closing cap) from the tamper-
evident
band.
Traditionally, tamper-evident closures of the type generally disclosed above
have a plurality of undercut beads that are constructed and arranged to engage
cooperating beads or similar structural forms on the neck of the container
that are
located axially below the external threads. As the closing cap is unscrewed
from
the neck of the container, the cooperating sets of beads prevent the tamper-
evident
band from rising (axially) with the remainder of the closure (i.e., the
closing cap).
The referenced frangible elements may be constructed and arranged as molded
strands or links in unitary construction with the tamper-evident band and with
the
closing cap. Alternatively, the frangible elements can be created by making a
circumferential slit around the circumference of the closure between the
tamper-
evident band and the closing cap. The intent is to construct a weakened zone
between the tamper-evident band and the closing cap that fractures as the
closing
cap is unscrewed from the container neck, leaving the tamper-evident band
behind
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on the container. This particular configuration can be accomplished by the use
of a
weakened, severable web or by a similar weakened portion located between the
closing cap and the tamper-evident band.
One of the problems discovered with the use of undercut beads on the
tamper-evident band is that the frangible elements are disturbed and often
broken
by the ejection process during molding and/or during the capping process. As
the
tamper-evident band is forced over the cooperating annular bead formed on the
neck of the container, the deflections and stress can cause some of the
frangible
elements to break. One approach to try and prevent such breakage is to design
the
frangible elements to be stronger by making them larger. While these stronger
(larger) frangible elements may survive the molding and capping process, they
do
not thereafter break or fracture reliably, as would be desired and intended,
during
closure (upper body portion) removal from the neck of the container. This in
turn
means that the frangible elements, in cooperation with the tamper-evident
band, do
not provide a tamper-evident capability to the closure.
Another design adjustment or modification to try and help the frangible
elements survive the molding and capping process involves the depth and angle
of
engagement of the undercut beads. These depth and angle values or dimensions
are kept (reduced) at values which detract from the ability of the undercut
beads
relative to the bead or beads on the neck of the container to be able to
provide a
robust tamper-evident capability. When the undercut is reduced in this manner
and
to this extent, the tamper-evident band is able to slip over the container
bead. This
means that the closure can be removed (intact) without fracture of the
frangible
elements.
According to the present invention, the described problem and design
challenge is addressed by replacing the undercut beads with an alternative
structure
to hold the tamper-evident band down during closing cap removal. This
alternative
structure, according to the present invention, involves ultrasonically welding
the
tamper-evident band directly to the neck of the container. With the tamper-
evident
band securely retained on the container neck in this manner, the fabrication
problems of the undercut beads are eliminated. This in turn allows the
geometry
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and construction of the frangible elements to be optimized for the desired
tamper-
evident capability. Without providing any bead or beads on the neck of the
container, there is no deflection or stress introduced into the frangible
elements
during the molding and capping process. This means that the frangible elements
do not have to be enlarged or made more robust in order to be made stronger.
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BRIEF SUMMARY OF THE INVENTION
A unitary, tamper-evident closure for use on the threaded neck of a
container according to one embodiment of the present invention comprises a
closure cap having a series of threads formed on an inner surface, an annular,
tamper-evident band constructed and arranged for being ultrasonically welded
to a
portion of the container, a plurality of frangible elements constructed and
arranged
for connecting the tamper-evident band to said closure cap at a plurality of
spaced-
apart locations and wherein the tamper-evident band is free of any undercut
beads
and the sole structural connection of the tamper-evident band to the container
is by
way of ultrasonic welding.
One object of the present invention is to provide an improved tamper-
evident closure.
Related objects and advantages of the present invention will be apparent
from the following description.
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BRIEF DESCRIPTION OF THE SEVERAL VIEWS
OF THE DRAWINGS
FIG. 1 is a front elevational view of a tamper-evident closure assembled to
a container according to a typical embodiment of the present invention.
FIG. 2 is an exploded, front elevational view of the FIG. 1 closure and
container combination with a portion of the closure separated from a tamper-
evident band.
FIG. 3 is a front elevational view of the FIG. 1 tamper-evident closure.
FIG. 4 is a top plan view of the FIG. 3 tamper-evident closure.
FIG. 5 is a bottom plan view of the FIG. 3 tamper-evident closure.
FIG. 6 is a front elevational view of the FIG. 3 tamper-evident closure as
viewed along line 6-6 in FIG. 4.
FIG. 7 is a front elevational view of a tamper-evident closure assembled to
a container according to another embodiment of the present invention.
FIG. 8 is an exploded, front elevational view of the FIG. 7 closure and
container combination with a portion of the closure separated from a tamper-
evident band.
FIG. 9 is a front elevational view of the FIG. 8 tamper-evident closure.
FIG. 10 is a top plan view of the FIG. 9 tamper-evident closure.
FIG. 11 is a bottom plan view of the FIG. 9 tamper-evident closure.
FIG. 12 is a front elevational view of the FIG. 9 tamper-evident closure as
viewed along line 12-12 in FIG. 10.
FIG. 13 is a front elevational view of a tamper-evident closure according to
another embodiment of the present invention.
FIG. 14 is a front elevational view of a tamper-evident closure according to
another embodiment of the present invention.
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DETAILED DESCRIPTION OF THE INVENTION
For the purposes of promoting an understanding of the principles of the
invention, reference will now be made to the embodiments illustrated in the
drawings and specific language will be used to describe the same. It will
nevertheless be understood that no limitation of the scope of the invention is
thereby intended, such alterations and further modifications in the
illustrated
device, and such further applications of the principles of the invention as
illustrated
therein being contemplated as would normally occur to one skilled in the art
to
which the invention relates.
Referring to FIGS. 1 and 2, there is illustrated a container 20 and a tamper-
evident plastic closure 21 assembled to container 20 according to one
embodiment
of the present invention. This container and closure combination has the FIG.
1
appearance as a result of the initial capping operation following filling of
the
container.
Container 20 includes a generally cylindrical, externally-threaded neck 22
that defines an annular dispensing opening 22a. The contents of container 20
are
to be dispensed by way of opening 22a after opening of the container following
the
initial filling and capping. Closure 21 has the form of an internally-threaded
cap
and is constructed and arranged for secure threaded connection directly to the
threaded neck 22. Closure 21 includes a closed end and an opposite open end as
further illustrated in FIGS. 3-6.
The tamper-evident closure 21 is a unitarily molded, plastic component that
includes three cooperating portions. These cooperating portions include a
tamper-
evident band 23, a closing cap that is also described as being the closure
body 24,
and a plurality of spaced-apart frangible elements 25 that span the
circumferential
gap 26 between band 23 and body 24 and connect to the tamper-evident band 23
and the closure body 24. The plurality of frangible elements is considered to
constitute one "poi-tion" of closure 21. The circumferential gap 26 provides
axial
spacing between the lower edge of.the closure body 24 and the upper edge of
the
tamper-evident band 23.
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Each frangible element 25 is a small strand of plastic that is unitarily
molded as part of the one-piece closure 21 and spans the axial separation as
defined by circumferential gap 26. One end 27 of each frangible element is
joined
(unitarily molded) to the upper edge 28 of tamper-evident band 23 and the
opposite
end 29 of the corresponding frangible element is joined (unitarily molded) to
the
lower edge 30 of closure body 24. Circumferential edges 28 and 30 define gap
26
while each of the frangible elements 25 extends across and spans the axial
height
of gap 26. Since the only connection between the tamper-evident band 23 and
the
closure body 24 is by way of the frangible elements 25, the location of gap 26
becomes a weakened location in terms of the overall construction of tamper-
evident closure 21.
According to the present invention, the initial assembly of closure 21 onto
container 20 occurs after the filling of container 20 with the desired
contents. The
assembly procedure involves the first step of threading closure 21 directly
onto
neck 22 and applying the requisite tightening torque. The next step is to
perform a
plastic weld operation in order to securely anchor the tamper-evident band 23
directly to the base 34 of neck 22 below the series of external threads 35.
While
various procedures might be suitable for this rigid connection requirement,
the
preferred procedure for the present invention is to ultrasonically weld the
tamper-
evident band 23 to the container 20 at the base 34 of neck 22. This approach
of
ultrasonic welding is considered to be more reliable and more cost effective
than
other possible procedures. The intent of this ultrasonic welding step is to
make
certain that the tamper-evident band 23 remains on the neck 22 of container 20
and
stays securely connected to the neck as the remainder of closure 21,
specifically
closure body 24, is removed (i.e., unscrewed). During the ultrasonic welding
process, a vibrating metal horn pushes on selected points of the outside
diameter
surface of the tamper-evident band 23 and the transmitted vibrations cause the
surface area of contact between the inside diameter of the tamper-evident band
23
and the outside surface of the base of the neck 22 to actually melt together,
thereby
creating the ultrasonic weld between these two plastic members.
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The completed and filled container and closure combination, according to
the present invention, includes container 20 that is filled with the desired
contents
and closure 21 that is tightly and securely threaded onto the neck 22 with the
tamper-evident band 23 ultrasonically welded to the base 34 of the neck 22.
The
tightly threaded closure prevents any loss or leakage of the contents and the
tamper-evident band 23 acts to prevent any retrograde movement of the closure
21
during transportation and handling. While the frangible elements 25 are
constructed and arranged to break when purposefully unscrewing the closure
body
24, they are strong enough to resist any anticipated vibrational loads that
might be
induced due to transportation and handling of the filled container 20.
When it is desired to open the filled container 20 to dispense some or all of
the contents, the end user simply grasps or secures the container and grasps
the
outside surface of the closure body 24 (or alternatively applies an
appropriate hand
tool), and the twists in a counterclockwise (i.e., retrograde) direction to
unscrew
the closure body 24 from the neck 22 of container 20. This unscrewing action,
whether manual or tool-assisted, causes the closure body 24 to move upwardly
in
an axial direction. Since the tamper-evident band 23 is ultrasonically welded
to the
base of the neck 22, the tamper-evident band 23 does not rotate relative to
the neck
22 and does not move axially with the closure body 24. This stationary
condition
of tamper-evident band 23 relative to container 20, while closure body 24 is
being
unscrewed, results in both a twisting force and an axial pulling or stretching
force
on each frangible element 25. While these combined forces are not necessarily
equal on every frangible element 25, once a first frangible element breaks,
these
two forces, which continue to increase with the unscrewing action, are now
applied
against and resisted by a fewer number of frangible elements. Rapidly, the
remaining frangible elements each break, thereby allowing the closure body 24
to
be removed from the neck of the container while the tamper-evident band 23
remains securely connected to the neck 22. This entire separation step of
separating the closure body 24 from the tamper-evident band 23 typically
occurs
quite rapidly. Once the closure body 24 is separated from the tamper-evident
band,
it can be repeatedly reapplied to and removed from the container neck. In this
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mode, the closure body 24 functions as a closing cap. In the embodiment of
FIGS.
1-6, the number of frangible elements 25 is twelve (12) and these frangible
elements are equally-spaced around the circumference of closure 21. The number
of frangible elements can vary depending on their individual size and to some
extent depending on closure and container sizes.
The specific style of closure illustrated in FIGS. 1-6 is what may be referred
to as a hex or crown cap due to the raised hex contour of the closure body 24.
This
hex-shape provides six (6) flat faces 37 and alternating corner edges 38 and
these
features facilitate the use of automated capping equipment with a matching hex
socket shape to be able to fit over the closure 21 and apply the desired
tightening
torque. The center area of the closure body 24 is recessed into circular
socket 39.
As discussed and explained in the Background section, there are concerns
with the use of undercut beads for tamper-evident bands and the present
invention
embodiment of FIGS. 1-6 provides an improved tamper-evident closure that
eliminates the need for and use of undercut beads. The result is a better and
more
reliable tamper-evident closure without encountering any of the problems or
concerns associated with the use of undercut beads.
Referring to FIGS. 7 and 8, there is illustrated a container 70 and tamper-
evident plastic closure 71, as assembled according to another embodiment of
the
present invention. Except for those differences that will be described herein
regarding the specific construction of closure 71, it should be understood
that the
use, function, and cooperation of closure 71 relative to container 70 is
substantially
the same as tamper-evident closure 21 relative to container 20. As with
container
20, container 70 includes a generally-cylindrical, externally-threaded neck 72
that
defines an annular dispensing opening 72a. The contents of container 70 are to
be
dispensed by way of opening 72a once closure 71 is removed. Closure 71 has the
form of an internally-threaded cap and is constructed and arranged for secure
threaded connection directly to the threaded neck 72 of container 70. Similar
to the
style of closure 21, closure 71 includes a closed end and an opposite open
end, as
illustrated in FIGS. 9-12.
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The tamper-evident closure 71 is a unitarily molded, plastic component that
includes a tamper-evident band 73 and a closing cap that is also described as
being
the closure body 74. As will be described herein, this particular embodiment
includes the creation of a plurality of spaced-apart frangible elements 75
that span
a circumferential gap 76 that is created between the tamper-evident band 73
and
closure body 74. Each frangible element 75 is a small strand of plastic that
is left
as a result of a post-molding slitting operation. While the "fmished" closure
71
can be and is best described in terms of the three cooperating portions, the
closure
71 begins as a unitary, molded plastic part effectively with a single portion.
The
10 closure 71 is then modified by this slitting operation and this results in
three
cooperating portions including the tamper-evident band 73, the closure body
74,
and the plurality of spaced-apart frangible elements 75. The plurality of
frangible
elements is considered to constitute one "portion" of closure 71. Similar to
what
has been described with regard to tamper-evident closure 21 and its
relationship to
container 20, this post-molding slitting operation creates a lower edge as
part of the
closure body 74 and it creates an upper edge for tamper-evident band 73. These
two edges define the axial width of the separation gap 76 that is created by
this
slitting operation.
The unitarily molded closure 71 includes a plurality of axially-extending
ribs 71a that are located on the inside diameter of the lower portion of
closure 71,
adjacent open end 71b. In lateral section, each rib 71a has a generally
triangular
shape. The converging sides of each rib 71 a are directed radially inwardly.
These
ribs 71 a are described herein as "energy directors" due to their
participation, at
least for some of them, in the ultrasonic welding process and the manner in
which
these ribs function in focusing and directing the ultrasonic energy being used
to
ultrasonically weld the tamper-evident band 73 to the neck of the container.
These
ribs 71 a, while described as "energy directors", also later function, after
the
ultrasonic welding process is completed, as frangible elements in that these
ribs
71a span the gap 76 between the tamper-evident band 73 and the closure body
74.
These axially-extending ribs 71 a extend the full height of tamper-evident
band 73 and extend into the lower portion of what becomes closure body 74
after
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the slitting operation. These ribs 71a also span the gap 76 that is created by
the
slitting operation. Ribs 71 a are arranged as a uniformly spaced series and
are
located such that, regardless of the orientation of closure 71 on neck 72 of
container 70, at least one pair of these energy directors (i.e., ribs 71 a)
are located
adjacent the portions of the vibrating ultrasonic horn that contact the outer
surface
of the tamper-evident band 73.
The embodiment disclosed in FIGS. 7-12 is described as a "slit-band" style
of closure due to the post-mold operating of cutting a 360 degree
circumferential
slit from the outside diameter surface of the tamper-evident band 73 inwardly.
This slit is cut such that it extends completely through the annular wall of
the
molded closure. This results in the creation of gap 76 positioned between the
tamper-evident band 73 and the closure body 74. The depth of cut of the
circumferential slit is just slightly greater than the wall thickness of
closure 71.
The slit cuts through the wall of closure 71, but is not sufficiently deep to
actually
cut through or sever any of the axially-extending ribs 71a. Visually this
"slit" may
appear as a series of slit sections since the slit does not cut through any of
the ribs
71. Each slit section appears as if located and extending between a
corresponding
pair of adjacent ribs 71a. However, the gap 76 resulting from the slitting
operation
is a full 360 degrees of the closure wall. The machined slit cuts through the
wall of
closure body 74 overlapping each rib 71 a, as is illustrated. This vertical or
axial
location of the slit is at or near the top (upper axial direction) of each rib
71 a. The
"top" of each rib 71 a is defined as the end of the rib that is closest to the
closed end
of closure 71. The described molding and subsequent machining to create gap 76
results in a finished closure 71 that includes a closure body 74, a tamper-
evident
band 73, and a plurality of frangible elements 75, some of which also function
as
energy directors for the ultrasonic welding step. The frangible elements 75
connect
the tamper-evident band 73 with the closure body 74 in a manner similar to the
first embodiment of FIGS. 1-6.
In terms of the assembly or connection of the closure 71 to container 70, the
tamper-evident band 73 is ultrasonically welded to the neck 72 of the
container in a
manner similar to the first embodiment of FIGS. 1-6. It is important to note
that
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the positioning of the vibrating metal horn adjacent the tamper-evident band
is at a
location below the slit line or gap 76, actually between the gap 76 and the
open end
71b. This configuration and the positioning of the metal horn causes the
tamper-
evident band 73 to be ultrasonically welded to neck 72. While ribs 71 a have
been
described as energy directors, this functional description only applies to the
ribs
71 a selected for ultrasonic welding (i.e., melting) and it only applies to
the section
or portion of each rib 71a that is below the slit line (gap 76). This is the
only part
of each selected rib that is acted upon by the vibrating metal horn as part of
the
ultrasonic welding process.
The part or section of each rib 71 a that spans gap 76 is not melted as part
of
the ultrasonic welding process and thus becomes a frangible element 75,
temporarily connecting the upper portion of tamper-evident band 73 with the
lower
portion of the closure body 74. The functioning as a frangible element 75
applies
to each rib 71 a.
When the closure 71 is attempted to be removed from the container 70 for
the first time, the unscrewing action of closure body 74 results in the
combination
of an upward axial force and a twisting or circumferential force on each of
the
frangible elements 75. Since the tamper-evident band 73 is welded to the neck
72,
it is unable to move in response to these combined forces. Further, these
forces
increase until the frangible elements 75 break, thereafter allowing the
closure body
74 to be removed and leaving behind the tamper-evident band 73 securely
attached
to neck 72. This description of what occurs is basically the same as what has
been
described for the first embodiment as illustrated in FIGS. 1-6.
The completed and filled container combination, according to this
embodiment of the present invention, includes a container 70 that is filled
with the
desired contents with the closure 71 tightly and securely threaded onto the
neck 72
with the tamper-evident band 73 ultrasonically welded to the base 84 of neck
72.
The tightly threaded closure prevents any loss or leakage of the contents and
the
tamper-evident band 73 acts to prevent any retrograde movement of the closure
71
during transportation and handling. While the frangible elements 75 are
constructed and arranged to break when purposefully unscrewing the closure
body
Y1-11.
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74, they are strong enough to resist any anticipated vibrational loads that
might be
induced due to transportation and handling of the filled container 70.
When it is desired to open the filled container 20 to dispense some or all of
the contents, the end user simply grasps or secures the container and grasps
the
outside surface of closure body 74 and twists in a counterclockwise
(retrograde)
direction to unscrew the closure body 74 from the neck 72 of container 71.
This
unscrewing action causes the closure body 74 to move upwardly in an axial
direction.
While there are a number of similarities between the first embodiment and
the second embodiment as described thus far, it will be noted that the style
of
closure body 74 is different from that disclosed for closure body 24. Rather
than a
hex shape, closure body 74 is generally cylindrical with a plurality of
axially-
extending exterior gripping ribs 85 that are spaced apart on the outside
surface of
closure body 74 and provide a convenient means for manually grasping the
closure
body 74 for unscrewing and separating from tamper-evident band 73 by breaking
the frangible elements 75. In this second embodiment, there are sixteen (16)
frangible elements that are equally-spaced and this increased number is
desirable in
terms of selected ones of these ribs 71 a also functioning as the energy
directors for
the ultrasonic welding process.
The first embodiment of the present invention, as illustrated in FIGS. 1-6,
includes a crown-style, hex-shaped closure body 24 and the frangible elements
25
are created as part of the unitary molding of closure 21. The second
embodiment
of the present invention, as illustrated by FIGS. 7-12, includes a generally
cylindrical, ribbed closure body 74. In this second embodiment, the frangible
elements 75 result from a slitting operation following the unitary molding of
closure 71. It is to the understood that according to the present invention
either
style of closure body 24, 74, can be used with either style of frangible
elements 25,
75. These two additional embodiments of the present invention are illustrated
in
FIGS. 13 and 14.
FIG. 13 illustrates closure body 74 in combination with frangible elements
25 and the style of tamper-evident band 23 that is used with frangible
elements 25.
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In order to create this finished structure, the plastic closure 100 is
unitarily molded,
as illustrated, with a closure body 101, frangible elements 102, and a tamper-
evident band 103. The gap 104 between the closure body 101 and the tamper-
evident band 103 is defined by the molded structure and the molded frangible
elements 102 span this gap 104.
FIG. 14 illustrates closure body 24 in combination with frangible elements
75 and the style of tamper-evident band 73 that is used with frangible
elements 75.
In order to create this finished structure, the plastic closure 120 is
unitarily molded
with a closure body 121 corresponding to the style of closure body 24. After
the
molding step, a slitting operation is performed and the webs of material that
are
left, corresponding to the energy directing ribs 122, create the frangible
elements
123 that span the gap between the closure body 121 and the tamper-evident band
124.
While the invention has been illustrated and described in detail in the
drawings and foregoing description, the same is to be considered as
illustrative and
not restrictive in character, it being understood that only the preferred
embodiment
has been shown and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
