Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Screw cap with sealing disc
The invention relates to a cap with sealing disc for a container closure, for
use on a
container with an opening bounded by a peripheral edge, wherein the sealing
disc
consists of several layers, the bottom-most layers of which seal tightly the
opening of the
container prior to the initial opening of the container and are connected in a
releasable
manner to the top-most layers of the sealing disc, wherein said top-most
layers are able to
form a renewed temporary closure of the opening of the container. --
1o On the closure of a container it is frequently desirable, or even
necessary, to provide the
container mouth with a disc-shaped sealing which seals off the contents, for
example
liquids or else substances such as foodstuffs.
There are several reasons why said sealing off is required. On the one hand,
the contents
are to be protected against outside influences, for example against water
vapour or
oxygen, on the other they are also to remain aroma-tight. There is a further
reason in the
case of aggressive contents, for which as optimum a leakage protection as
possible must
be provided. Finally, an originality protection for the trade may also be
provided by such
a sealing off, since a user is able to recognise immediately whether someone
has akeady
2o handled the container contents beforehand.
In addition, the container closure is then also sealed with a screw cap or a
similar
element, which ensures a mechanical and stable sealing outside the filin. On
initial use
the user destroys the film in order to get at the contents of the container
and closes the
container afterwards (unless he has already removed the entire contents) with
the screw
closure, which may provide a temporary seal for the opened contents for a
suitably short
period of time.
If the tightness requirements are only slight, a cardboard disc may, as
proposed in DE 94
10 934 Ul, be placed on the container mouth as a sealing element or in some
cases be
clamped in the screw cap. The sealing disc may then be ejected through a small
flap in
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the screw cap, in order to allow the contents to flow out of said flap again
after renewed
screwing on. However, any sealing after the initial opening is therefore
forfeited, and
furthermore the possible uses are also limited to undemanding and insensitive
contents.
The film that seals the container contents is frequently applied by means of
induction
sealing, as inter alia in EP 0 717 710 B1 and DE 39 20 324 A1. A complete
sealing disc
is put on for this purpose, whose bottom-most layer foams the sealing layer.
Above it lies
a second layer consisting as a rule of aluminium, which serves for the
generation and
transmission of heat during the induction process and optionally forms an
additional
1o mechanical protection. The second layer is connected to the first one
firmly and in
particular favourably for the transmission of heat. Above said aluminium layer
are then
provided also further components of the sealing disc, which remain in the cap
after the
opening of the screw or other rotating closure.
Said further or upper components of the sealing disc are clamped together in
the screw
cap. If said screw cap is rotated at the initial opening, the torque is
automatically also
transferred onto said upper parts of the sealing disc. Said upper parts of the
sealing disc
therefore rotate relative to the opening of the container. The lower parts of
the sealing
disc, on the other hand, are sealed firmly onto the container mouth and do not
rotate. In
2o this way the upper part of the sealing disc is sheared off from the lower
part precisely in
the separation area provided. The upper part remains in the screw cap, the
lower part
remains on the container and may now be suitably handled by the user and
destroyed.
Problems arise at this point, however. In order that the user may remove said
lower part
with the sealing layer, certain sensitive measures have been taken in said
area. For
example, it is provided according to EP 0 395 660 B1 or EP 0 534 949 B1 to
make the
top-most layer capable of being swung open here, by it being in part not
bonded to the
induction layer. Said non-bonded area in particular is therefore naturally
very sensitive to
applied stresses, above all in the rotation direction, where no resistance of
any kind may
3o also be offered to them because of the lack of bonding. A point may
therefore be reached
where destruction or damage occurs here, which gives the inexperienced user in
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particular the impression that the container closure was defective or possibly
not tight or
else was not sealed in the proper manner. In extreme cases said process may
actually lead
to partial destruction of the sealing layer.
The object of the invention is conversely to propose a cap with a sealing disc
with which
a more gentle separation of the sealing disc components takes place.
This object is achieved by the fact that the cap comprises devices for
limiting the distance --
of the top-most layers of the sealing disc from the underside of the cap in
the event of an
to opening of the cap and the top-most layers of the sealing disc are adhesion-
free relative to
the underside of the cap and rotatable with respect to the latter.
The problem is surprisingly solved with such an idea, which is a complete
departure from
the prior art. To date, in fact, it had always been assumed that the
rotational movement of
the cap must be exploited in order to separate the two relevant components of
the sealing
disc from one another. Now, however, the sealing disc is quite deliberately no
longer
bonded in the cap, but lies loose in the latter. The result of this is that on
rotation of the
cap, as a result of the still present bonding of the upper parts of the
sealing disc to the
lower parts of the sealing disc the whole of the sealing disc remains
stationary and does
2o not imitate the rotational movement of the cap. The result of this in turn,
however, is that
no destruction of any kind is able to occur because of the relative rotational
movements
of the various layers to one another. The tabs, folds or other ingenious
arrangements on
the top-most layer of the lower layers of the sealing disc remain completely
unaffected.
The top-most part of the sealing disc, which later forms the reseal part, is
simply lifted
vertically upward. Vertically upward is in this case parallel with or exactly
in axial
direction of the opening of the container. Said lifting takes place by on the
one hand the
elastic pressure originally exerted by the cap falling away and on the other,
due to
suitable mechanical measures, by a light force being exerted exactly
vertically upward by
the cap, which moves reliably upward not only in a rotating manner.
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To ensure said movement, however, a controlled, light, connection is in fact
easily
settable by means, for example, of a polymer separation layer between the
reseal part and
the lower layers of the sealing disc. The latter may be provided precisely in
such a way
that, although it is stronger than any rotational forces and torques
nevertheless
transmitted, it still then yields to said vertical force effect. However, said
vertical lifting
of the upper layers from the lower ones leaves the top side of the lower
layers unaffected.
They are not displaced relatively into one another or buckled relative to one
another, but
remain lying uninfluenced.
The user may now carry out the respective manoeuvres offered, for example
lifting
partially bonded areas, vertically raising folds and similar. After this he
may remove said
lower area fully from the container. The screw cap then possesses again,
precisely as in
the prior art, a reseal part, which is exceptionally suitable for the renewed
sealing of the
container. It is also now immaterial whether and how said reseal part moves,
it is simply
screwed on again together with the screw cap. Despite the absence of adhesion,
it does
not drop out of the screw cap, as it is retained in the cap by the mechanical
engagement
means, in particular grooves and beads.
It is particularly preferable if the sealing disc exhibits a constant outer
diameter across all
the layers. In this way a single punching tool may be employed and in addition
only one
punching operation is required. In the prior art it was nevertheless sometimes
preferred,
because of the sensitivity of the upper layers, to provide individual layers
with outwardly
projecting tabs as in EP 0 697 345 A2, in order to counteract this.
An embodiment of the invention will be explained in detail below from the
drawing,
where
Figure 1 shows a diagrammatic cross-section, not to scale, through a screw cap
with
sealing disc during the opening.
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Figure 1 shows the area of the opening 11 of a container 10. This may be a
bottle, a
container for agrochemicals, or a container to be sealed aroma-tight, for
example for
coffee powder or similar. The opening is surrounded by a peripheral edge 12.
The edge
12 is in general circular.
On said opening is located after the filling of the container and prior to the
initial opening
a sealing disc 20 consisting of several layers, which is sealed upward and
laterally by a
screw cap base element 40.
to Viewed from the container side, the disc 20 begins first of all with a
sealing layer 21.
There follows on sand sealing layer 21 an induction layer 22, conventionally
of
aluminium. Said induction layer ensures that heat produced in the layer 22 by
means of
induction is transferred to the sealing layer 21 and the latter is sealed
firmly onto the edge
12 of the opening 11 of the container 10 during the production or packaging
process.
The induction layer 22 is followed next by a layer 23. By means of said layer
23 the user
is able to remove the sealing layer 21 together with the induction layer 22 if
he wishes to
get at the contents of the container 10. Said layer 23 comprises for said
purpose for
example outwardly projecting tabs or else inherently a corresponding fold for
gripping. In
2o the representation in Figure 1 this is indicated by such a projecting fold.
In the completely
sealed state said fold lies flat naturally and takes up practically no
additional space.
There then exists in practice no gap between the layer 23 and the next layer
24 lying on
top of it, the so-called reseal part. The reseal part 24 therefore lies
directly on the layer
23, optionally on the flat lying fold of the layer 23.
All the layers are bonded to one another, the layers 21, 22 and 23 very firmly
by adhesive
layers, as they are no longer to be, and must not be, separated from one
another. The
layers 23 and 24 are conversely connected to one another by a relatively
easily releasable
connection which is at any rate easily controllable in terms of its adhesive
power. Care
3o should be taken in selecting the bonding and separating material between
the layer 23
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and the layer 24 that in the event of a separation said material remains in
the main on the
layer 23.
The total thickness of the layers 21, 22 and 23 is very small in relation to
the other
container and also opening dimensions. Their presence or non-presence plays
practically
no part in the procedure for screwing down or slipping the cap 40 onto the
container 10.
It should be pointed once again that Figure 1 is in no way to scale here.
There is provided on the screw cap 40 on the one hand a fixing device 43, for
example an
to internal thread, which engages with matching counter-fixing elements (not
shown) of the
container 10. The cap 40 may therefore be screwed on here.
Noticeably, and other than in the prior art, there is not only provided
between the top-
most cover plane of the cap 40 and the fixing device 43 a space for a sealing
disc 20, but
said space in addition comprises an inwardly projecting groove 41 or
alternatively, co-
ordinated with the latter, a bead 42 projecting slightly outwards in relation
to said groove
41. The size ratios are also exaggerated slightly here.
Likewise other than in the prior art, no adhesive connection is provided
between the
2o sealing disc 20 or the reseal part 24 of the sealing disc 20 on the one
hand and the
underside of the cover of the cap 40 on the other. The sealing disc 20 is
therefore
rotatable in its entirety relative to the cap 40.
The groove 41 is arranged exactly so that the reseal part 24 fits into the
bead 42. During
the screwing of the cap 40 onto the container 10 said reseal part 42 passes
into said area
without difficulty, due to light mechanical tension or suitable thermal
measures, across
the slight resistance of the groove 41. Prior to the initial opening of the
container also,
therefore, a separation of the reseal part 24 from the lower layers 21, 22 and
23 of the
sealing disc 20 is not carried out. The latter still remain together.
3o Not until the initial opening of the container, during the unscrewing of
the screw cap 40,
is said connection loosened. Other than in the case of screw caps from the
prior art,
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however, this does not take place, for instance, by the torque of the screw
cap 40 being
transferred onto the reseal part 24 during the opening, and the connection of
the reseal
part 24 thereby being "deflected" to the lower layers of the sealing disc. The
reseal part
24 simply remains stationary and only the then absent compressive force from
above,
combined with the mechanical engagement of the groove 41 with the reseal part
24, leads
to the reseal part being lifted vertically upward without any rotation. The
reseal part
therefore remains in the cap, whereas the lower layers remain on the container
10.
In the figure is indicated diagrammatically a phase in which the separation
between the
to layers 23 and 24 from one another has just taken place. Both layers are not
rotated against
one another, however, they move away from one another along the axis of the
container
mouth. The indicated fold is starting to form; in practice, however, it will
as a rule
intentionally require manual assistance for this.
The user is consequently presented, after the initial opening of the screw cap
40, with free
access to the layer 23 with the handling means provided there, for example the
tab or the
projecting fold.
If he has now loosened said lower layers and partially removed the contents of
the
2o container 10, he may seal the container once again with the screw cap 40
and the reseal
part 24 contained therein. Although the container then no longer has its
original seal, a
closure is nevertheless possible in this way for a temporary period. Opening
may then
naturally take place again, in order to gradually consume the container
contents.
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List of reference symbols
IO container
11 opening of the container
12 edge of the opening
20 sealing disc
21 sealing layer
22 induction layer
23 layer for opening
24 reseal part
40 cap
41 groove
42 bead
43 fixing device
