Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
. CA 02297840 2000-O1-24
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SEALING AND TAMPER-PROOF ELEMENT FOR CONTAINER.
The present invention relates to a combined sealing
and tamper-proofing element for a container, and in
particular for a container whose opening is designed to
be closed by a lid, and to a method of manufacturing such
an element.
Numerous technical solutions exist for jointly
sealing and tamper-proofing a container.
Among such solutions, heat-sealed covers or "tops"
are in wide use, in particular for food products.
Such covers are sometimes associated with additional
sealing means such as gaskets disposed inside the lid or
cap that is designed to fit over the top portion of the
container.
Such covers can also be provided with graspable
means such as tabs which are generally formed by portions
of the cover itself, as described in EP 395 660,
EP 460 096, EP 534 949, and US 4 754 890.
Unfortunately, the presence of such tabs prevents
any possibility of the top face of the cover being
bonded, even temporarily, to the gasket of the cover.
Such bonding is necessary to reinforce the tamper-
proofing, and to simplify the manufacturing method
insofar as it enables the sealing and tamper-proofing
element to be made in one piece.
An object of the present invention is to solve the
preceding technical problems, firstly by making the
graspable tab in the form of a separate tape mounted on
the cover, and secondly by setting up temporary bonding
around said tab between said cover and the gasket of the
lid.
The invention achieves this object by means of a
combined sealing and tamper-proofing element for a
container whose opening can be closed by a lid, said
element being of the type comprising:
a removable cover whose bottom face is designed to
be sealed in leak-tight manner to the rim of the opening
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CA 02297840 2000-O1-24
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and whose top face carries a tape forming a graspable
tab; and
a gasket designed to be retained in said lid, said
element being characterized in that the cover and the
gasket are made in one piece; the bottom face of said
gasket adhering to the top face of the cover, at least in
the zones not covered by said tape, with bonding force
that is weaker than the forces retaining respectively the
gasket in the lid and the cover on the rim of the
opening.
According to an advantageous characteristic, said
tape is provided with a longitudinal fold forming a
resilient hinge and defining firstly a fixed portion
secured to the top face of the cover, and secondly a
moving portion folded-over parallel to said fixed portion
by means of the gasket bearing against said moving
portion.
Preferably, said moving top portion of the tape is
bonded to the gasket in separable manner.
In a variant, the fixed portion and the moving
portion are of equal width.
In a particular embodiment, said tape extends
diametrally over the top face of the cover.
In a variant, said tape is made up of at least two
layers.
In which case, the bottom layer of the tape is
secured to the top face of the cover, and is bonded
separably to the bottom face of the gasket.
For example, the bottom layer is made of
polyethylene and the top layer is made of polyethylene
terephthalate (PET) or polyester.
In another embodiment, said cover is made up of at
least two layers.
In a variant, said cover comprises a sealing bottom
layer, a metal interposed layer and a top layer.
Preferably, said top layer is made up of at least
two sub-layers, namely a bottom sub-layer compatible with
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CA 02297840 2000-O1-24
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the metal layer and a top sub-layer compatible with the
tape.
In yet another embodiment, said gasket comprises at
least two layers.
In a variant, said gasket comprises a bottom layer
bonded reparably to the tape and to the cover, an
expanded intermediate layer, and a top layer disposed
facing the bottom of the lid.
In another variant, the bottom layer and the top
layer of the gasket are each made up of two sub-layers.
For example, the bottom layer of the gasket is made
of polyethylene terephthalate or of polyamide, and the
intermediate layer is made of a polyolefin foam.
Preferably, said gasket has a symmetrical structure.
In a specific embodiment, the weak bonding between
the bottom face of the gasket and the top face of the
cover is mainly of mechanical origin.
The invention also provides a method of
manufacturing said element, said method being
characterized in that the top layer of the cover is
formed by hot extrusion and then the gasket is applied to
the hot top layer, thereby holding the previously fixed
tape captive, so that, after cooling, weak bonding is
obtained between the gasket and the cover.
The invention makes it possible to reinforce sealing
and tamper-proofing for the container because the gasket
and the cover are assembled together so as to form a
single hermetic-sealing piece.
The layers making up the cover are fixed together
firmly as are the layers making up the gasket.
Thus, on taking off the lid, the gasket and the
cover come apart easily without causing either of them to
undergo delamination, and without causing any damage to
their interface or to the tab.
Once the lid has been taken off, the cover can also
be unstuck without undergoing delamination or tearing, by
means of the graspable tab.
CA 02297840 2000-O1-24
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In addition, by making a single element for tamper-
proofing and for sealing, it is possible to simplify
closing and packaging operations.
The invention will be better understood on reading
the following description with reference to the drawing,
in which:
Figure 1 is a section view of the element of the
invention; and
Figure 2 is a perspective view of the element of the
invention after the lid has been taken off.
The element E shown in Figure 1 is designed to
provide both sealing and tamper-proofing of a container R
(visible in Figure 2) whose opening A can be closed with
a lid or a cap C.
The element E comprises a combination of a cover 1
and of a gasket 2 in one piece.
The bottom face of the cover 1 is designed to be
stuck or sealed in leak-tight manner to the rim of the
opening A in the container R, and its top face carries a
tape 10 forming a graspable tab. For example, the cover
1 may be heat sealed in known manner by high-frequency
induction.
The gasket 2 is designed to be received in the lid C
which is organized for this purpose. For example, the
gasket may be retained by means of a peripheral ring
provided on the inside wall of the cover and behind which
the gasket is locked at least in part. In the invention,
the bottom face of the gasket 23 adheres in easily-
separable manner to the top face of the cover 1 at least
in the zones not covered by the tape 10.
The bonding force between the bottom face of the
gasket 2 and the top face of the cover 1 is determined
such that it is less than the forces retaining the gasket
2 in its seat, and less than the resistance of the cover
1 to being torn off from the rim of the opening 1 of the
container R. Preferably, this bonding force is such that
any displacement of the lid C, and in particular of the
CA 02297840 2000-O1-24
gasket 2 relative to the container R causes the gasket
and the cover 1 to separate immediately. Such weak
bonding is preferably obtained by extruding or by co-
extruding the top layer of the cover 1 at a high
S temperature (at which the materials melt), then by fixing
the tape 10, and then by applying the gasket 2 rapidly to
the top layer of the resulting cover, thereby holding the
tape 10 captive.
While the gasket 2 is being applied, the extruded
top layer of the cover is still hot enough to conserve a
state facilitating adhesion, at least to some extent.
Then, after cooling, the lack of chemical
compatibility (that may be more or less marked) between
the materials constituting respectively the bottom layer
of the gasket 2 and the top layer of the cover 1 provides
weak bonding, mainly of mechanical origin (by a vacuum or
suction effect). Thus, the higher the degree of
compatibility between the materials in contact, the
larger the bonding force between the gasket and the
cover, because the chemical bonds that are strongest are
more numerous.
The tape 10 is provided with a longitudinal fold 100
forming a resilient hinge and defining firstly a fixed
portion l0a secured to the top face of the cover 1, and
secondly a moving portion lOb, folded over parallel to
the bottom portion l0a by means of the gasket 2 bearing
against said moving portion. The fixed portion l0a and
the moving portion lOb are preferably of equal width, as
shown in Figure 1, and they extend diametrally over the
top face of the cover 1 which, in this example, is
circular.
The moving portion lOb of the tape 10 which is
folded over so that it lies flat on the fixed portion l0a
is optionally bonded to the bottom face of the gasket 2
by an adhesion phenomenon analogous to that concerning
those zones of the top face of the cover 1 which are
adjacent to the fixed portion l0a of the tape.
CA 02297840 2000-O1-24
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In which case, when the lid is taken off on the
container being opened for the first time, removal of the
lid participates in raising the moving portion, which
makes it easier for it to be grasped subsequently.
However, the inside facing faces of the fixed and
the moving portions 10a, lOb of the tape 10 that are in
contact in the folded-over state, are never bonded
together, thereby allowing the moving portion lOb to move
resiliently upwards under the action of the hinge 100
after the gasket 2 has been separated from said portion.
When the tape 10 is made up of at least two layers
101, 102, the bottom layer 101 is fixed firmly to the top
face of the cover 1, and the layer 101 is free or is
bonded reparably to the bottom face of the gasket 2. By
means of the above-described adhesion phenomenon, when
the tape 10 is in the folded-over state, the top layer
102 is disposed inside the fold, between the fixed
portion l0a and the moving portion lOb.
For example, the bottom layer 101 may be made of
polyethylene while the top layer 102 is made of
polyethylene terephthalate (PET) so as to avoid any
adhesion phenomenon between the fixed portion l0a and the
moving portion lOb.
The cover 1 is made up of at least two layers and,
preferably, three layers in the embodiment shown in
Figure 1.
Going upwards from the bottom, the three layers are
constituted by a bottom layer 11 that is sealed to rim of
the opening A, a metal interposed layer 12, e.g. of
aluminum, and a top layer 13.
The top layer 12 is made up of at least two sub-
layers 131, 132.
The bottom sub-layer 131 is compatible with the
metal of the layer 12, and the top sub-layer 132 is
compatible with the bottom layer 101 of the tape 10.
The layers 11, 12, 131, 132, and 101 are assembled
together firmly and permanently, e.g. by extruding or co-
CA 02297840 2000-O1-24
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extruding surface coatings that are heat-sealed together
so as to obtain bonding that is strong enough to avoid
any delamination on tearing off the cover 1 by pulling on
the moving portion lOb of the tape 10 that forms the
graspable tab.
Where applicable, the bonding forces between firstly
the bottom layer 11 and the rim of the opening A and
secondly the bottom layer 11 and the interposed layer 12
are determined relative to one another so as to produce
partial delamination of the bottom layer 11 on tearing
off the cover 1. The purpose of this partial
delamination is to leave a peripheral portion of the
bottom layer 11 on the rim of the opening, after tearing
off the cover, as a sealing and tamper-proofing
indicator, when the container is opened for the first
time.
The gasket 2 is made up of one or more layers, and
preferably of at least two layers as in the embodiment
shown in Figure 1, with three layers 21, 22, 23 defining
a symmetrical structure.
The top layer 21 is disposed facing the end wall of
the lid C while optionally being fixed thereto by gluing
or any other means.
The intermediate layer 22 is expanded and has a
thickness that is much larger than the thickness of the
other two layers 21, 23. For example, this layer may be
formed of a cellular material such as a polyolefin foam.
The bottom layer 23 is bonded in separable manner
firstly to the moving portion lOb of the tape 10, and
secondly to the top face of the sub-layer 132 of the
cover 1. The top layer 21 and the bottom layer 23 of the
gasket 2 are each made up of two sub-layers 211 & 212 and
231 & 232.
The bottom layer 23 and optionally the top layer 21
are made of polyethylene terephthalate or of polyamide.
In a variant, the outermost layers are of very small
thicknesses and are, for example, constituted by films.
CA 02297840 2000-O1-24
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Thus, in the folded-over state, the tape 1 is
temporarily enclosed between the cover 1 and the
gasket 2.
When the container is used for the first time, the
consumer takes off the lid C as shown in Figure 2.
This effect of this action is to separate the gasket
2 from the cover 1 while releasing the moving portion lOb
of the tape 10, which portion can then pivot upwards to
come into a position in which it is substantially
perpendicular to the plane common to the fixed portion
l0a and to the cover 1.
Then, by pulling on the portion lOb, the consumer
separates the cover 1 from the rim of the container 1 so
as to open the opening A.
Various embodiments are given below by way of non-
limiting example, with the following abbreviations being
used as listed:
PET - polyethylene terephthalate or polyester
PA - polyamide
PVC - polyvinyl chloride
PVDC = polyvinylidene chloride
PE - polyethylene
PP - polypropylene
PO - polyolefin
* The top layer (13 or 132) is made by extruding a
material or co-extruding a plurality of materials taken,
for example, from the above list, on their own or in
association as alloys.
CA 02297840 2000-O1-24
Example 1
La er Materials
21 PET
gasket 2 22 PE foam
23 PET
tape 10 102 PET
101 PE
extrusion or co-
13 extrusion/spreading
of one or more layers*
cover 1
12 PET film, aluminum or
PA
11 Glassine (32 g)
stuck to the rim (A)
Example 2
2 La er Materials
0
21 card
asket 2 23 aluminum
tape 10 102 PET
101 PE
2 extrusion or co-
5
13 extrusion/spreading
of one or more layers*
cover 1
12 PET film
30
mono- or multi-layer
11 PE film heat-sealed
to
the rim (A)
CA 02297840 2000-O1-24
Example 3
La er Materials
21 card
5 asket 2 23 PET
tape 10 102 PET
101 PE
extrusion or co-
extrusion/spreading
10 132 of one or more layers*
cover 1 13
131 aluminum
12 PET film
mono- or multi-layer
11 PE film heat-sealed to
the rim (A)
Example 4
La er Materials
21 card
asket 2 23 PET
2 tape 10 102 PET
5
101 pE
extrusion or co-
extrusion/spreading
132 of one or more layers*
3 cover 1 13
0
131 PET film
12 aluminum
3 mono- or multi-layer
5
11 PE film heat-sealed to
the rim (A)
CA 02297840 2000-O1-24
11
Exam~l a 5
La er Materials
asket 2 mono-la er PP foam
to a 10 mono-la er PET
extrusion or co-
extrusion/spreading
132 of one or more layers*
cover 1 13
131 PET film
12 aluminum
mono- or multi-layer
11 PE film heat-sealed
to
the rim (A)
