Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02084389 2003-04-15
TAMPER EVIDENT CONTAINER CLOSURE
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to tamper evident containers,
and more particularly to closures having visible seals which
reveal whether tampering or leakage has occurred, without
the necessity of removing the closure to inspect the seal.
Description of Related Art
Containers such as jars with screw-on caps have been
provided with various means fox indicating tampering.
For example, my prior U.S. patent No. 4,778,069
discloses and claims a container having a tab extending from
an inner seal through a slot in the container cover. Damage
to the tab is indicat:i.ve of tampering.
U.S. patent No. 4,553,678 has a film or foil seal which is
visible through a transparent screw cap.
Relative movement between an outer container cap and an
inner liner .is shown by indicia on the liner which can be
seen through a window provided in the cap of U.S. patent No.
4,446,979.
In the package of U.5. patent No. 4,489,841, a color
change in the skirt of a cap indicates that the package has
been opened.
Patent No. 4,674,642 relates to a closure for a
container having contents under vacuum. An inner liner has a
projection which extends through an aperture in the container
cap when vacuum is lost. However, if the container contents were
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an oil-based product such as peanut butter or. mayonnaise,
vacuum would be re-established after opening and re-closing
of the container because of reaction of the contents with
air admitted by opening of the container.
SUMMARY OF THE INVENTION
The tamper evident container closure of the
invention includes an inner seal which is held in a concave
or convex condition by a difference between the ambient
pressure and the pressure of gas within the container. The
inner seal is visible through an opening in a top panel of
the closure. When tampering has occurred the curvature of the
seal will be changed or eliminated, making it evident that
the tampering has occurred. Leakage of the seal will prpduce
an effect similar to that of tampering. This will alert a
retailer or consumer that the product should not be sold or
purchased.
Two embodiments of the closure of the invention
are illustrated. Although it may be desirable in so~ie cases
to employ an underpressure in the container to contract the
inner seal into a concave state in many cases it is
desirable for the seal to be held in a convex state, by
overpressure as shown in the dxawings for purposes of
comparison of the two embodiments.
A convex condition also provides a tactile
indication of security. Pressing upon the seal with a
finger offers assurance of pressure, indicating that the
seal has not been broached.
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The closure of the invention provides external
evidence that a container, such as a jar or bottle with a
screw-on cap, has been subjected to tampering or leakage
without resorting to complex devices which are costly to
manufacture and which are, in some cases, unreliable. There
will be fewer false positive signals of tampering than will
result from some of the prior art expedients, and fewer
false negative signals than there would be with other prior
art devices.
According to the invention, the condition of an inner
seal reveals whether the container has been tampered with or
otherwise opened. When the container has been opened, the seal
configuration changes from a convex or concave condition which
denotes container integrity, to another condition, signaling
that the container has been opened.
The invention is discussed with reference to closure
for a jar with a screw-on cover, but the invention is
applicable to covers secured to containers by other means
than mating screw threads, and to closures for other types
of containers.
The inner seal, which can be sealingly secured either
to a lip of the container or to a container cap or lid as
well reveals whether the container has been opened. The term
"opened", as used herein, refers to either complete or
partial removal of or leakage past the inner seal, which
could expose the container contents to unintentional
contamination or tampering.
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The inner seal is visib:Le through an aperture in the
container cover, such as a circular central hole in a flat
top panel of the cover, Enougr: of the periphery of such an
apertured panel is retained to l:rovide pressure for sealing
to the seal surface of t:he container.
For some products which az:~e not c:c>nsurned after the
first opening but are uv,ed repeatedly it is desirable that
the aperture not. be open when the cover is repl.ac:ed. While
this may be accommodated by ret::i:;ckirg the seal member, it
may be more desirable for the ~~Eaal member to be sealed to
the cover as well as t:he contair:er rim. The sea7_ to the rim
must be suff:icie~ntly strong to °etai.n a hermetic seal but
sufficiently weak to fai.:l by shE~ar when opening.
The neE:d to close this apE:e_ture may also be
accommodated by using a ~wo elE>rnent seal part of which seals
to the cover and part tc> the c<::ntsiner rim. The two parts
may be temporarily bonded with coax. which melts a7_lowing
separation at the time of sealing.
In one aspect, the present= invention provides a
tamper evident closure for a container in which a
cover is secured to a mouth of i:.he container. The
closure inc7_udes a flexible se al. member_ between the
container and the cover and visi.bl.e through an
opening in t=he c:over, wtui.ch seal. member is secured to
the cover and sealed to a rim of the o:onta:iner and
adapted to be curved away from <u flat <.:ondition by a
difference between pressures exist:ing inside and
outside the container so that :,:one integrity of the
container is detectable while Kf=eping the container
cover secured, and wherein the peal between the seal
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member and the rim is adapted tc fail by shearing
when opening while the seal member remains secured to
the cover.
In another aspect:, the present invention teaches a
method of providing a c:;ontai.ner with a seal for showing
evidence of tampering or leakage of the container. The
method includes the steps of providing a flexible seal
member between the container ane a cover for t:he container,
the seal member being secured to the cover and sealed to a
rim of the container, and provic:ing a pressure within the
container which differs from atmospheric pressure, whereby
the seal member is deformed frc,rn a flat. condition by the
pressure difference, and providing an opening in the cover
through which the deformation of the seal member is visible,
wherein the seal betweE:m the seGl member and t he rim fails
by .shearing when openirug while t.lne seal member remains
secured to the cover.
Brief Description of the Drawir~g
In the several figures of t:he drawing, like reference
characters indicate like parts,
Fig. 1 shows a container ~>rovided with a tamper evident
closure according to the invention.
Fig. 2 is an exploded view of the container closure of
Fig. 1 with a single element seal.
Fig. 3 shows the closure of Figs. 1 and 2 in its sealed
condition.
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Fig. 4 shows the effect of opening the container
of Figs. 1 - 3 in the embodiment in which the seal remains
affixed to the closure, but fails at the container interface
by shearing.
Fig. 5 shows another embodiment of the tamper
evident closure of the invention wherein the seal is
distended by internal pressure.
Fig. 6 illustrates the closure of Fig. 5 in sealed
condition.
Fig. 7 shows the effect of unscrewing the cover of
the container closure of Fig. 5 when the seal consists of
two elements.
Fig. 8 shows breakage of the seal of the container
closure of Figs. 5 - 6 wherein the seal element is affixed
solely to the container rim and is removed by peeling.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The drawings show embodiments of the tamper evident
container closure of the invention as applied 'to a screw-on
cap of a wide mouth jar, although the invention can be
employed in other types of closures, such as caps for
bottles, etc.
The jar, generally designated by the reference
character J in the several drawing figures, is hatched to
indicate plastic material, but it could be a glass, ceramic
or metal container.
As shown in Fig. 2, the jar J has an open mouth portion
M provided with an integral outwardly projecting helical
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thread T1 for engagement with an inwardly projecting helical
thread T2 of a cover 10 for the jar J as seen in Figs. 3 and
4 when the cover 10 is screwed on to close the mouth of the
jar J. The cover or cap 10, which may be of plastic
material, has the usual annular lip 11 which carries the
thread T2, which lip can have multiplicity of external
vertical extending grooves to allow manual gripping without
slipping of the hand when opening or closing the container.
The cover 10, instead of the conventional continous
disc-shaped top panel, has only an annular peripheral
portion 12, surrounding an opening 13 which occupies most of
what would usually be the central area of a top panel of a
cover. The annular peripheral portion 12 of the cover is
sufficiently wide to provide pressure for sealing a seal
member 14 to the rim 15 of the mouth portion M.
The seal member .L4, which is preferably a die cut disc
of flexible foil laminated plastic material and/or coated
paper, is fitted in place within the cover 10 and applied to
the container by use of radio frequency induction heating or
some other conventional technique. The seal is secured to
the rim 15 of the container. The contents of the jar J can
be filled by a conventional process such as hot filling,
nitrogen injection, under- or over-saturation with soluble
gas, flushing of a head space above the contents with a
soluble gas, or by any other known technique which will
result in a head space pressure beneath the seal 14 that
differs from atmospheric pressure.
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In the embodiment illustrated in Fig. 3, the pressure
in the head space within the jar J is lower than
atmospheric, and the seal member 14 is accordingly deformed
into the concave conformation illustrated. This contraction
of the seal member 14 is readily apparent to one inspecting
the seal through the opening 13 of the cover 10.
The cover 10 may also have a peripheral flange 17 for
vertical stacking of containers.
Fig. 3 shows the jar J with its seal member 14 in a
concave disposition, indicating that no tampering or leakage
has allowed outside air to enter the jar J. Alternatively,
an outwardly distended, convex seal member a?4 and could indicate
an overpressure in the jar J to signal. that. no leakage or
tampering has taken place as in Fig . ~ .
When the cover is rotatably displaced as shown in Fig.
4, the seal 14 moves away from the rim 15 of: the jar J,.
allowing the internal and external pressures to equalize.
Fig. 4 shows ambient air entering as illustrated by the
direction of the arrows. If the contents were filled under
an over-pressure, the pressurized gas would escape to the
outside. In either case, the seal 14 will respond by taking
on the unstressed flat conformation shown in Fig. 4. The
flat surface of the seal 14 as shown in Fig. 4, visible
through the opening 13, signals that there has been
tampering or leakage. The retailer will not sell, and the
potential customer will not purchase, a product whose seal
14 is flat and thus warns of tampering or leakage.
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Modified versions of the closure according to the
invention are shown in Figs. 5 - 8. In the embodiment of
Figs. 5 - 6 the seal member 24 is sealingly secured, to the
rim 25 of the jar J. The seal 24 is shown as having a convex
curvature in its undisturbed state. Fig. 6 shows the jar J
as it would be received after filling. Fig. 7 shows the
removal of the cover 2n if the seal consists of two
elements.
It is only when the seal member 24 is detached from the
rim 25 of the jar J that the pressure difference between the
interior space of the jar and the ambient is equalized. This
is illustrated in Fig. 8. .As shown in the drawings, the
closure of Fig. 5 - 8 has a central opening 23 like the
opening 13 of the embodiment of Figs. 1 - 4, but the opening
23 can be smaller in diameter than the opening 13. The
opening 23 permits inspection of the condition of the seal
24 or the combination of seal members 16 and 24 without
removal of the cover 20.
Some oil based products such as peanut butter, oil and
mayonnaise tend to react with oxygen, and would re-establish
a partial vacuum beneath the seal member 14 of the
embodiment of Figs. 1 - 4 if the cover In were tightly
replaced after opening. That will not occur when the closure
of Figs. 5 - 8 is employed, because once the seal 24 has
been breached, there is no mechanism to allow return to the
convex condition. Thus the seal arrangement of Figs. 5 - 8
is preferable for such products as mayonnaise, peanut butter
or oil.
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However, for other types of container contents, it may
be preferable to package the contents under a reduced
pressure to contract the seal 14 or 24 to a concave
conformation. Either of the embodiments described can be
employed with a pressure in the head space of the container
sufficiently different than ambient pressure. The use of an
overpressure and the consequent convex seal condition
evidencing closure integrity has advantages, such as the
possibility of using a less sturdy container than one which
is filled at atmospheric pressure or under vacuum.
The invention, in either form, allows printing on the
seal member, whether at be seal. 14, or 1~ or 24,
avoiding the need to put printed content identification or
other information on the cover 10 or 20,
Various modifications, choices of materials and
applications of the closure of the invention will suggest
themselves to those acquainted with the art. What is described
is a tamper or leakage evident closure arrangement for
containers.
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