Note: Descriptions are shown in the official language in which they were submitted.
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INTEGRALLY MOULDED CLOSURE SYSTEM
The present invention relates to an integrally
moulded closure system comprising a cap and neck and
having tamper evident means such that, having applied
the cap to the neck, the cap is prevented from being
removed from the neck prior to the removal of the
tamper evident means.
In WO 99/37547 there is described a one piece
fitment having a reclosure cap. The fitment comprises
a spout which converges upwardly and has a cylindrical
external locking bead. Above the spout is an outward
slanted tear band and above the tear band is a
reclosure cap comprising a top, a depending skirt
formed with internal interrupted beads and a plug. The
tear band is connected to the spout and cap by thin
horizontal tear lines. A pull tab extends outwardly or
downwardly with respect to the tear band so that a
consumer may conveniently grip the pull tab and pull it
circumferentially around the fitment to separate the
tear band from both the spout and the cap. The cap is
dimensioned so that the skirt fits over the outside of
the spout with the internal beads detachably locking
under the locking bead. The plug seals.against the
inside of the spout to prevent spillage.
Thus it is known to provide a closure system
comprising a cap and neck which are integrally moulded
in a unitary structure. It is also known for such a
structure to comprise tamper evident means since,
before its removal, the tear band and reclosure cap
function as a tamper evident closure for the spout.
However, what is not known and what has previously not
been provided is an integrally moulded closure system
comprising a cap and neck and which incorporates tamper
evident means in which the cap may be applied to the
neck prior to the removal of the tamper evident means.
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Similarly, there has been no disclosure of a closure
system comprising a cap applied to a neck in which
tamper evident means prevents the removal of the cap
from the neck prior to the removal of the tamper
evident means, the cap, neck and tamper evident means
having been integrally moulded in a unitary structure.
According to a first aspect of the present
invention there is provided a closure system comprising
a cap, a neck and tamper evident means integrally
moulded in a unitary structure, the structure allowing
the application of the cap to the neck whereupon the
tamper evident means prevents the cap from being
removed from the neck while the tamper evident means
remains intact.
Advantageously an intermediate member is joined to
the neck at a first frangible connection and joined to
the cap at a second frangible connection, the first
frangible connection being adapted to break upon
application of the cap to the neck whereupon the
intermediate member co-operates with the neck and the
cap to form said tamper evident means. Preferably the
intermediate member comprises an annular band adapted
to pass over the neck upon application of the cap to
the neck and a transition member joined to the annular
band, the transition member being adapted to co-operate
with the neck to resist the subsequent removal of the
annular band from the neck. Preferably the transition
member is hinged to the annular band. For example, the
annular band may be joined to the transition member by
a web, the web forming a hinge permitting the
transition member to flex with respect to the annular
band. Advantageously the web may constitute a region
of reduced thickness. Alternatively, the web may be of
substantially the same thickness as the transition
member but include one or more score lines to permit
the transition member to flex with respect to the
annular band.
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Advantageously the neck is provided with a locking
wall, the transition member being adapted to engage
with the locking wall to resist subsequent removal of
the annular band upon application of the cap to the
neck. Preferably the transition member is joined to
the neck at said first frangible connection, said first
frangible connection being adapted to break upon
application of the cap to the neck only after the act
of applying the cap to the neck causes the transition
member to fold inwardly of the annular band.
Advantageously, upon application of the cap to the neck
the transition member hinges with respect to the
annular band, folding inwardly and into engagement with
a locking wall provided on the neck.
Advantageously the annular band may be joined to
the cap at said second frangible connection, said
second frangible connection being adapted to break upon
the attempted removal of the cap from the neck.
Advantageously the first and second frangible
connections may lie within respective parallel planes.
Advantageously one or both of the first and second
frangible connections may be formed as a line of
weakness defined by a region of reduced thickness. In
one preferred embodiment the transition member is
tapered in the direction of the first. frangible
connection so that the transition member is joined to
the neck in a region of reduced thickness.
Advantageously one or both of the first and second
frangible connections may be formed as a plurality of
frangible tabs. The plurality of frangible tabs may be
circumferentially spaced with each tab being separated
from an adjacent tab on either side by a pair of slits,
each slit communicating at opposite ends thereof with a
respective pair of apertures of increased cross-
section. In this way a respective pair of apertures of
increased cross-section may constitute an area of
weakness disposed on either side of each of the tabs.
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Advantageously, the transition member may extend
from the neck to the annular band within a generally
frustoconical surface.
Advantageously the transition member extends from
the neck to the annular band in a direction which is
inclined radially outwardly at an angle of between 22°
and 32° to the axis of the closure system.
Advantageously the transition member may comprise
a plurality of circumferentially spaced transition
elements, the transition elements having a first
circumferential dimension adjacent the annular band and
a second circumferential dimension adjacent the neck,
the first circumferential dimension being greater than
the second circumferential dimension. Preferably, the
transition elements are separated by a plurality of
apertures, the apertures being arranged in groups on
circumferentially opposite sides of the transition
member.
Alternatively, the transition member may comprise
one or more pleats or folds. In another arrangement
the transition member may comprise a plurality of
circumferentially spaced transition elements separated
by areas of weakness or reduced thickness.
Advantageously the cap may be provided with
engagement means for a repeated and releasable
engagement with complimentary engagement means provided
on the neck. Preferably the pair of complimentary
engagement means may comprise a pair of helical thread
configurations. Under such circumstances, the said
configuration provided on the neck is preferably a
female thread configuration.
Advantageously the pair of thread configurations
are adapted so as to permit the application of the cap
to the neck by means of an axially applied force
whereupon the threads on the cap slide over those
provided on the neck and then interengage. Preferably
the treads on the cap are orientated with respect to
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those on the neck in such a way that upon axial
application of the cap to the neck the respective
thread configurations are placed in optimal thread
engagement.
Advantageously the cap may be provided with an
annular plug for receipt within a bore of the neck.
Advantageously the closure system comprises a
fitment for attachment to a carton or other container.
Alternatively, the closure system may be integrally
moulded with a container, the neck forming a neck of
the container.
According to a second aspect of the present
invention there is provided a method of closing a
container in a tamper evident manner comprising the
steps of moulding a neck of the container in one piece
with a cap and tamper evident means to form a unitary
structure and applying the cap to the neck in such a
way that the cap is prevented from being removed from
the neck while the tamper evident means remains intact.
According to a third aspect of the present
invention there is provided an integrally moulded
closure system comprising a cap applied to a neck, the
closure system including tamper evident means
integrally moulded with the cap and neck, the tamper
evident means preventing removal of the cap from the
neck while the tamper evident means remains intact.
The present invention will now be described by way
of example with reference to the accompanying drawings
in which:
Figure 1 is an elevational side view of a closure
system embodying the present invention;
Figure 2 is a cross-sectional view of the closure
system of Figure 1;
Figure 3 is a perspective view of the closure
system of Figure 1;
Figure 4 is an elevational side view of the
closure system of Figure 1 once the cap portion has
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been applied to the neck portion;
Figure 5 is a cross-sectional view of the closure
system once the cap portion has been applied to the
neck portion;
Figure 6 is a perspective view of the closure
system of Figure 1 once the cap portion has been
applied to the neck portion; and
Figure 7 is a cross-sectional view of the closure
system taking along lines VII - VII of Figure 1.
As shown in Figure l, a closure system embodying
the present invention may take the form of a fitment
10. The fitment 10 comprises a neck portion 12, a cap
portion 14 and, between the two, a transition member 16
which joins the neck portion 12 to the cap portion 14.
Looking firstly at the neck portion 12, the neck
portion comprises an apertured flange 18 having
substantially smooth and planer upper and lower
surfaces 20 and 22 respectively. Surrounding the
aperture, a cylindrical wall 24 projects upwardly from
the upper flange surface 20 to form the neck. Adjacent
to the flange 18, the external surface of the
cylindrical wall 24 is smooth before merging with a
radially outwardly projecting locking wall 26 to define
a shoulder. At an end of the locking wall 26 remote
from the cylindrical wall 24, the locking wall 26 in
turn merges with an upwardly and radially inwardly
inclined surface 30 which, with the radially outwardly
projecting locking wall 26, defines an annular locking
bead 32. Above the annular locking bead 32, the
upwardly and radially inwardly inclined surface 30
merges with a neck stretch portion 34 of slightly
increased diameter compared to the cylindrical wall 24
in which is provided engagement means with which to
engage complimentary engagement means provided on the
cap portion 14. In the example shown, the engagement
means provided on the neck stretch portion 34 takes the
form of an equi-spaced, multi-lead female helical
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thread configuration 36 which includes four threads or
leads 36a, 36b, 36c and 36d. It will be apparent
however, that the engagement means may take a number of
different forms and, in particular, need not be limited
to four threads or leads but may comprise one, two or
three threads as appropriate. The engagement means may
also comprise five or more threads if so desired.
Generally speaking however, it is preferable for the
configuration to comprise a plurality of threads.
In the illustrated embodiment, each thread 36a,
36b, 36c and 36d extends about 120°around the
circumference of the neck stretch portion 34. Once
again however, it will be understood that threads of a
lesser or greater extent may also be employed. For
example, each thread 36a, 36b, 36c, 36d may extend
within a range from 90° to more than 360°. Preferably
the helical thread configuration 36 has a fine thread
density to limit the vertical float of the cap portion
14 on the neck portion 12. Thus the thread density
preferably lies within a range of between 6 and 12
threads per linear inch. Most preferably of all, is a
thread density of approximately 8~ threads per linear
inch.
Above the helical threads 36, the neck stretch
portion 34 merges with a second upwardly. and radially
inwardly inclined surface 38 which in turn merges with
a further vertical neck stretch portion 40 before
terminating in an annular rim 42.
At a radially inner edge, the annular rim 42
merges with a downwardly and radially inwardly inclined
surface 44. This downwardly and radially inwardly
inclined surface 44 in turn merges with a substantially
smooth inner surface 46 of the cylindrical wall 24.
The substantially smooth inner surface 46 flares
radially outwardly adjacent the flange 18 to define a
downwardly and radially outwardly inclined surface 48.
Adjacent to the transition between the substantially
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smooth inner surface 46 and the downwardly and radially
outwardly inclined surface 48, the substantially smooth
inner surface 46 is provided with a plurality of
circumferentially spaced, radially inwardly projecting
lugs 50.
Turning to the cap portion 14, the cap portion
comprises a circular top 52 having an under surface 54.
The circular top 52 merges at a radially outer edge
with a downwardly and radially outwardly inclined
surface 56 which in turn merges with a depending
annular side wall 58 to form a downwardly extending
upper skirt portion 60. The depending annular side
wall 58 is provided on an inner surface 62 with
complimentary engagement means for repeated and
releasable engagement with the engagement means
provided on the neck portion 12. As before, these
engagement means may take many forms but, in the
example shown, comprise an equi-spaced, multi-lead,
male helical thread configuration 64 having four
threads or leads 64a, 64b, 64c and 64d and a thread
density of approximately 8~ threads per linear inch.
In the embodiment shown each thread extends
approximately 120° around the inner surface 62 of the
depending annular side wall 58. However, it is to be
understood that this thread length may be increased or
decreased if desired. For example, each thread may
extend in a range from 90° to more than 360°.
Likewise, the thread density is not intended to be
limited to being about 8~ threads per linear inch but,
nevertheless, preferable lies within the range from
about 6 to about 12 threads per linear inch.
Preferably, the female thread configuration 36 on the
neck portion 12 and the male thread configuration 64 on
the cap portion 14 each have at least two threads and a
thread density of at least 6 threads per linear inch.
As shown, the male threads 64a, 64b, 64c and 64d
provided on the cap portion 14 may be interrupted at
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intervals along their length.
In order to facilitate the axial application of
the cap portion 14 to the neck portion 12 when an
axially downward force is applied to the cap portion in
a direction to urge the cap portion into engagement
with the neck portion, the threads of the male helical
thread configuration 64 may be provided with an
appropriate cross-sectional shape. For example, the
threads may be formed with an asymmetric cross-section
or else may be made less pronounced.
In the illustrated embodiment, the two thread
configurations 36 and 64 each comprise multiple turns
of thread. As a result a vertical line drawn across
the thread configuration 36 on the neck portion 12
intersects two or three turns of thread depending upon
the location of the line around the circumference of
the neck stretch portion 34. At the same time a
vertical line drawn across the thread configuration 64
on the cap portion 14 intersects one or two turns of
thread depending upon the location of the line around
the circumference of the depending annular side wall
58. This ensures that when the cap portion 14 is
applied to the neck portion 12 there will be multiple
turns of thread engagement. Of course, the total
cumulative thread engagement is subject to variation
and, depending upon the linear thread density, may be
as little as one turn of thread engagement or more than
three turns of thread engagement.
In addition to the male helical thread
configuration 64, the interior of the cap portion 14 is
provided with an annular plug 66 which depends from the
under surface 54 of the circular top 52 and which is
spaced radially inwardly of the depending annular side
wall 58. The annular plug 66 is defined by respective
radially inner and outer walls 68 and 70, the radially
outer plug wall 70 merging at an end remote from the
circular top 52 with a generally downward and radially
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inwardly directed surface 72. This downwardly and
radially inwardly directed surface 72 intersects the
radially inner plug wall 68 and together serves to
provide the annular plug 66 with a bevelled radially
outer surface and a tapering cross-section. This
tapering cross-section is further accentuated by the
fact that, whereas the radially outer plug wall extends
in a direction substantially perpendicular to the plane
of the under surface 54, the radially inner plug wall
68 extends from the under surface 54 in a direction
which is both downwardly and radially outwardly.
By contrast, on the exterior of the cap portion
14, the depending annular side wall 58 is provided on
its outer surface with a plurality of circumferentially
spaced, vertical extending ribs 74 which serve as
knurls to facilitate the gripping of the cap portion 14
by a user. As is common with a number of caps, a small
downwardly directed. dimple 76 is formed in the centre
of the circular top 52 so that any flash left after the
cap portion has been moulded does not project above a
plane defined by the upper surface of the circular top
52.
In addition to the foregoing features, the cap
portion 14 is provided with an annular band 78 which is
formed as an extension of the depending annular side
wall 58 at a position remote from the circular top 52
and beneath the male helical thread configuration 64.
To this end the exterior surface of the annular band 78
occupies an extension of the same cylindrical surface
as that defined by the exterior surface of the
depending annular side wall 58. By contrast, the inner
surface 62 of the depending annular side wall 58
merges, via a short downwardly and radially outwardly
inclined surface 80, with an inner band surface 82 of
slightly greater inner diameter. At an end remote from
the depending annular side wall 58, and therefore at an
end remote from the circular top 52, the inner band
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surface 82 merges with the exterior band surface via a
radially outwardly directed rim 84. Both the inner and
exterior surfaces of the annular band 78 are formed
free of projections so as to be substantially smooth.
The annular band 78 is delimited from the
depending annular side wall 58 by a plurality of
arcuate slits 86 which are circumferentially spaced at
intervals around the cap portion 14 and in the same
horizontal plane. As a result the spacings between the
arcuate slits 86 define a plurality of
circumferentially spaced tabs 88 by which the annular
band 78 is connected to the depending annular side wall
58. At opposite ends of each of the arcuate slits 86,
the slits open out into apertures 90 of increased
cross-section, thereby weakening the area on either
side of each of the tabs 88.
As shown in Figure 1, the cap portion 14 is
initially joined to the neck portion 12 by means of
transition member 16. In the example illustrated, the
transition member 16 comprises a downwardly and
radially inwardly inclined frustoconical wall which is
provided with a plurality of trapezium-shaped apertures
92 which serve to define therebetween a similar number
of transition elements 94. Each transition element 94
lies within a frustoconical surface and has an upper
circumferential dimension adjacent the annular band 78
which is greater than a lower circumferential dimension
adjacent the neck portion 12. Furthermore, each
transition element 94 is joined to the annular band.78
by a thin, upwardly and radially outwardly inclined web
96 which merges with the annular band 78 at the
intersection of the inner surface 82 and the radially
outwardly directed rim 84. At the opposite end, the
inner surface of each transition element 94 is bevelled
with the result that each transition element tapers to
an edge 98 and it is at this edge 98 that the
transition element 94 merges with the neck portion 12
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at the intersection of the annular rim 42 and the
downwardly and radially inwardly inclined surface 44.
The closure system herein described may be moulded
in one piece with the neck portion 12 integrally formed
and joined with the transition member 16 and with the
transition member integrally formed and joined with the
cap portion 14. However, in order to assemble the
closure system an axially downwardly directed force is
applied to the cap portion in a direction towards the
neck portion 12. With the closure system in the
orientation shown in Figure 1, it will be understood
that as the cap portion 14 moves downwardly under the
action of the applied force so the plurality of
transition elements 94 begin to hinge about their
respective tapered edges 98. At the same time the
transition elements 94 also flex with respect to the
annular band 78, the flexure being accommodated by the
initially upwardly and radially outwardly inclined webs
96. As a result, as the cap portion 14 is urged
downwardly towards the neck portion 12, the transition
elements 94 fold upwards into the annular band 78 with
the consequence that, as the radially outwardly
directed rim 84 passes over the further vertical neck
stretch portion 40 followed by the neck stretch portion
34, the transition elements 94 take up an orientation
in which they extend from the annular rim 42 of the
neck portion to the annular band 78 in a downward and
radially outward direction.
With the cap portion 14 pressed down onto the neck
portion 12 to the extent permitted by the hinging
action of the transition elements 94, it will be
recognised that although the annular band 78 now
overlies the neck stretch portion 34, the male helical
thread configuration 64 provided on the cap portion is
not yet in engagement with the female helical thread
configuration 36 provided on the neck portion.
Continued downward movement of the cap portion 14 under
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the action of the applied force causes the transition
elements 94 to break away from the neck portion 12
along their respective tapering edges 98. The cap
portion 14 is then free to move downwardly onto the
neck portion 12 with the transition elements 94 still
folded upwardly within the annular band 78. As the cap
portion 14 moves downwardly so the transition elements
94 ride over the neck stretch portion 34 and the female
helical thread configuration 36 until such time as the
now downwardly and radially outwardly inclined webs 96
encounter the upwardly and radially inwardly inclined
surface 30 of the cylindrical locking wall 24. At
approximately the same time the male threads of the
helical thread configuration 64 provided on the cap
portion 14 encounter the second upwardly and radially
inwardly inclined surface 38 which constitutes the
transition between the neck stretch portion 34 and the
further vertical neck stretch portion 40. Meanwhile,
in the interior of the neck portion 12, the end of the
annular plug 66 remote from the circular top 52 is
received within the annular rim 42.
Continued downward pressure on the cap portion 14
causes the now downwardly and radially outwardly
inclined webs 96 and the transition elements 94 to
slide over the upwardly and radially inwardly inclined
surface 30 causing the transition elements to be
pressed up against the smooth inner band surface 82 and
causing the annular band 78 to flex slightly radially
outwardly. However, as the tapered edge 98 passes over
the transition between the upwardly and radially
inwardly inclined surface 30 and the radially outwardly
projecting locking wall 26, so the transition elements
94 are free to flex under the restoring action of the
now downwardly and radially outwardly inclined webs 96
bringing the tapered edges 98 into confronting
relationship with the locking wall 26. At the same
time, the slight radially outward flexing of the
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annular band 78 coincides with the slight radially
outward flexing of the upper skirt portion 60 as the
male helical thread configuration 64 slides over and
into engagement with the female helical thread
configuration 36. Also at this time the annular plug
66 is received within the bore~of the neck portion 12
defined by the substantially smooth inner surface 46.
In so doing the generally downward and radially
inwardly directed surface 72 slides along the
downwardly and radially inwardly inclined surface 44
causing the annular plug 66 to flex slightly radially
inwardly. Once fully received within the neck portion
12, the restoring force inherent in the resilient
nature of the design and materials making up the
annular plug 66 causes the radially outer plug wall 70
to be urged into sealing engagement with the
substantially smooth inner surface 46. Thus, in the
assembled condition, the interaction between the
annular plug 66 and the substantially smooth inner
surface 46 constitutes a primary seal.
A secondary seal is provided in the assembled
condition by the receipt of the annular rim 42 within
the annular recess defined between the radially outer
plug wall 70 and the downwardly and radially outwardly
inclined surface 56 of the cap portion 14. In order to
accommodate the annular rim 42 the radially outwardly
inclined surface 56 is forced to flex slightly radially
outwardly with the result that the restoring force
holds the radially outwardly inclined surface in
sealing engagement with the annular edge defined by the
intersection of the annular rim 42 and the further
vertical neck stretch portion 40.
With the closure system in the assembled condition
the fitment 10 may be applied to a paperboard or other
carton in the conventional manner. In this regard it
will be noted that the flared opening to the neck
portion 12 defined by the downwardly and radially
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outwardly inclined surface 48 facilitates the insertion
of a spud of a manipulation tool. At the same time the
provision of the plurality of circumferentially spaced,
radially inwardly projecting lugs 50 facilitate the
retention of the fitment on the spud. Since the
apertured flange 18 has substantially smooth and planar
upper and lower surfaces 20 and 22, the fitment 10 may
be bonded either to the outside or to the inside of a
carton panel as desired.~However, in another
arrangement, the neck portion 12 may be provided with
one or more additional projections which cooperate with
the apertured flange 18 to retain the fitment 10 in a
specific orientation with respect to the carton panel
to which the fitment is to be attached.
Once the fitment 10 has been applied to a carton,
the fitment provides that carton with a closure that
can be repeatedly opened and closed as desired and
which offers excellent sealing and re-sealing
characteristics. In addition, the fitment also
provides a tamper evident capability to alert a
consumer should the contents of the carton have been
compromised prior to initial opening. This tamper
evident capability is provided in the form of a tear-
band which must first be separated from the cap portion
14 before the cap portion can be removed from the neck
portion 12. If a consumer finds that the tear-band has
been separated from the cap portion 14 before the
fitment 10 has first been opened by them then it is
possible that the contents of the carton may have been
tampered with or may have become adversely affected in
some other way. The tamper evident capability of the
fitment functions as follows.
In the assembled condition the cap portion 14 is
prevented from being removed from the neck portion 12
in an axial direction by the interengagement of the
male and female helical thread configurations 64 and 36
and by the engagement of the tapered edges 98 with the
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annular locking bead 32. In order to remove the cap
portion therefore, a user is required to rotate the cap
portion 14 with respect to the neck portion 12. This
causes the threads of the male thread configuration 36
to rise up the grooves of the female thread
configuration 36 bringing the tapered edges 98 more
firmly into engagement with the locking wall 26.
Continued upward movement of the cap portion 14 with
respect to the neck portion 12 is resisted by the
transition elements 94 with the result that the upward
force exerted by a user in unscrewing the cap portion
is applied to the circumferentially spaced tabs 88
which serve to connect the annular band 78 to the
depending annular sidewall 58. The provision of
apertures 90 of increased cross-section on either side
of each of the tabs 88 ensures that the tabs will
fracture as a user continues to unscrew the cap portion
14 and long before any damage is sustained to the now
downwardly and radially outwardly inclined webs 96.
Onoe the tabs 88 have been broken the cap portion 14
may be removed and the contents dispensed from the
carton. The cap portion 14 may be reapplied and
subsequently removed from the neck portion 12 as often
as it is desired.
In the example shown, once. the tabs 88 have been
fractured, the tear-band (in the form of annular band
78 and transition elements 94) remains in place on the
neck portion 12 beneath the locking wall 26. However,
it will be appreciated that in order to provide the
tear-band with a drop-down capability which may more
easily alert a consumer to potential tampering, all
that is required is to elongate the portion of the
cylindrical wall 24 between the apertured flange 18 and
the radially outwardly projecting locking wall 26.
It will be apparent to those skilled in the art
that the closure system of the present invention is not
limited to the embodiment described and that numerous
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variations are possible. Having said, in order to
facilitate the manufacturing process it has been found
advantageous to limit the extent to which the internal
diameter of the annular band 78 exceeds the internal
diameter of the substantially smooth inner surface 46.
Although the annular band 78 clearly has to pass over
the neck stretch portion 34, if the difference between
these two internal diameters becomes too large it
becomes difficult to extract that part of the mould
tool responsible for the internal surface features (the
core) through the restricted opening defined by the
neck portion 12 and transition member 16. For this
reason, although. it is possible to provide the neck
portion 12 with a male thread configuration with which
to engage a complimentary configuration provided on the
cap portion 14, nonetheless a female thread
configuration is preferred. A female thread
configuration 36 on the neck portion 12 also provides
the advantage that there are no radial protrusions
which might otherwise foul the annular band 78 as the
cap portion 14 is applied to the neck portion 12.
In order to facilitate the extraction of the core
it has also been found preferable for the transition
elements 94 to be inclined radially outwardly at an
angle of between 22° and 32° to the vertical, and most
preferably, at an angle of 27° to the vertical. At the
same time, in the specific embodiment shown, the
vertical distance between the radially outwardly
directed rim 84 and the annular rim 42 is preferably
3.5mm while the tapered edge 98 preferably has a radial
dimension of between 0.16mm and O.lOmm. Elsewhere
along their length the transition elements 94
preferably have a dimension at right angles to the
angle of inclination of 0.5mm.
Whilst the trapezium-shaped apertures 92 may be
arranged at intervals around the transition member 16,
for ease of moulding the apertures are preferably
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arranged in groups of three on circumferentially
opposite sides of the closure system. In this way the
trapezium-shaped apertures 92 may be formed using
slides that open and close at right angles to the male
and female halves of the mould tool. In such an
arrangement, each group of three trapezium-shaped
apertures 92 are preferably symmetrical about a
vertical centre line with the central trapezium-shaped
aperture having an upper circumferential dimension
adjacent the annular band 78 of 2mm and the two
mutually inclined sides of the aperture subtending an
angle of 30°. The trapezium-shaped apertures on either
side are preferably spaced 6.2mm from the centre line
and arranged so as to have an upper circumferential
dimension adjacent the annular band 78 of 1mm while the
mutually inclined sides of the apertures subtend an
angle of 25°. In order to facilitate the folding
upwards of the transition elements 94 into the annular
band 78 as the cap portion 14 is pushed onto the neck
portion 12, the two trapezium-shaped apertures 92
spaced on either side of the central aperture within
each group of three are preferably not themselves
symmetrical. Rather, the inclined edge of the two side
apertures closest to the central trapezium-shaped
aperture preferably subtends an angle of 20° with
respect to the centre line. In this way each
transition element 94 has an upper circumferential
dimension adjacent the annular band 78 which is greater
than its lower circumferential dimension adjacent the
neck portion 12.
By contrast to the transition member 16, the
annular band 78 has a vertical dimension from the short
downwardly and radially outwardly inclined surface 80
to the radially outwardly directed rim 84 of 4.55mm
with the distance from the short downwardly and
radially outwardly inclined surface 80 to the arcuate
slits 86 accounting for 0.5mm of that vertical
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dimension. In order to facilitate the removal of the
core and to ensure that the tabs 88 are reliably
fractured upon initial unscrewing of the cap portion
14, the slits 86 preferably have a vertical dimension
of 0.25mm and open out into apertures 90 having a
vertical dimension of 0.85mm. This leaves the annular
band 78 with a vertical dimension of 3.2mm between the
apertures 90 and the radially outwardly directed rim
84.
As with the trapezium-shaped apertures 92, the
arcuate slits 86 are preferably formed using slides
that open and close at right angles to the male and
female halves of the mould tool. The arcuate slits 86
are therefore preferably formed so as to have no
undercuts in the direction of movement of the slides.
This means that the surfaces joining the
circumferential outer surface of the annular band 78 to
the inner band surface 82 do not extend radially but
rather have the configuration shown in Figure 7 in
which the surfaces on either side of one of the tabs 88
subtend an angle of 135° while those at opposite ends
of one of the arcuate slits 86 subtend an angle of 92°.
In order to ensure that the tabs 88 fracture reliably
they are preferably circumferentially spaced at
intervals of 45° and have a radial dimension of 0,25mm.
The apertures 90 on either side of each of the tabs 88
are preferably dimensioned so that an arcuate slit 86
joining two such apertures has a circumferential
dimension of 7.Omm.
One of the advantages of the closure assembly
herein described is that the cap portion 14 is held in
fixed relationship with the neck portion 12 prior to
application of the cap portion to the neck portion. As
a result it is possible, with suitable alignment of the
thread configurations 36 and 64, to ensure that once
the cap portion 14 has been applied to the neck portion
12 the threads are optimally engaged. This in turn
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means that no subsequent tightening of the cap portion
14 is required thereby simplifying the capping process
in comparison with the processes of the prior art. At
the same time, the optimization of the thread
engagement means that the closure system may utilise
the minimum thread length commensurate with the sealing
properties required, thereby enabling savings in both
cap and neck height. This in turn translates into a
saving of plastics material which bears a direct
relation to the cost of manufacture of the closure
system. The optimization of the thread engagement also
serves to eliminate any vertical float of the cap
portion 14 on the neck portion 12 which would otherwise
have to be allowed for in the vertical distance between
the annular locking bead 32 and the apertured flange
18. Because this vertical float can be eliminated, the
closure system can be designed so that the transition
elements 94 engage with the locking bead 32 almost
immediately upon unscrewing of the cap portion 14,
thereby rendering the closure system more secure
against unwanted tampering as well as cheaper to
manufacture.
Although the present invention has been described
in relation to a fitment for attachment to a carton, it
will be appreciated by those skilled. in the art that
the invention is not so limited and that the closure
assembly may be formed integrally with a container if
so desired.
