Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02203744 1997-04-2~
Sealing disc for a closure cap for CQntA; ne~s
The invention relates to a sealing element in the form of a disc
or washer for a closure cap for containers, in particular for
bottle closures for substances, alcoholic drinks or wines which
react with oxygen.
There are various known embodiments of sealing discs. They are
produced in appropriate sizes for use in bottle closures, for
example with diameters of 16.6 to 45.0 mm or 12.0 to 115.0 mm. The
small sealing discs are inserted in, for example, aluminium
closure caps, the larger ones in plastic closure caps of screw-
type closures for bottles.
It is known from US Patent 4,818,577 and US Patent 4,930,646 to
provide a sealing disc consisting of a top layer of polyethylene
foam and a layer disposed underneath of "Saran", i.e. a
polyvinylidene chloride. The object of this is to achieve a
barrier effect against the emergence of gaseous constituents from
the inside of the bottle.
It is known from German Utility Model 72 40 238 to produce a
sealing disc from a layer of polyolefin foam, in particular
polyethylene foam, and a layer of a gastight plastics material, in
particular a composite layer of polyethylene terephthalate and
polyvinyl chloride (PVC). The latter layer is disposed as a
diffusion barrier with the PVC layer towards the container opening
so as not to form a barrier against the emergence of gas, for
example carbon dioxide, and prevent the diffusion of oxygen into a
container.
European Patent Application 0 332 725 discloses a sealing disc
cast into a closure of polyolefin, for example polypropylene, with
a layer of an organosol facing the container contents, above this
a metal foil, a layer of polyolefin carboxylic acid and a layer of
a thermoplastic polyolefin, for example polypropylene. This
sealing disc is supposed to be heat-resistant and resistant to
pasteurisation and allow fluids to pass through, and be
particularly suitable for filling under vacuum and pressure.
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The use of corks to close wine or champagne bottles is known. An
enclosure consisting of lead or tin was previously in most cases
pulled over the corks. The lead is now usually replaced by an
aluminium layer or a PVC shrink-on cap. The use of corks to close
wine or champagne bottles often proves to have disadvantages, as
mould-like bacteria form at the bottom edge of the cork on the
side facing the wine or champagne. This phenomenon has a
significant detrimental effect on the quality of the wine or
champagne. Moreover, the use of corks to close wine or champagne
bottles, at current prices of DM 200 per 1000 for high-quality
corks, is a cost factor which cannot be ignored. It is for this
reason, and reasons regarding easier opening and the possibility
of re-closing bottles, that there has been an increasing tendency
in recent years also to use aluminium screw-type closures for wine
bottles. The sealing discs consist of polyethylene foam, for
example.
The object of the invention is to provide a relatively inexpensive
sealing disc for a closure cap for containers, in particular for
bottle closures for substances, alcoholic drinks or wines which
react with oxygen, which avoids the described disadvantages of
known corks and reliably protects the container contents against
degradation, particularly due to oxygen also trapped in the
container.
According to a first aspect of the present invention, there is
provided a sealing disc for a closure cap for containers of
substances which react with oxygen, the sealing disc comprising a
layer of an oxygen-tight substance and a layer of a deoxidizing
substance on the side of the sealing disc which is to face the
container contents.
According to a second aspect of the present invention, there is
provided a process for producing a sealing disc, wherein the
underside of a first layer of polyethylene foam is covered over
its entire surface with a second layer of an oxygen-tight
substance and bonded thereto, a third layer of a deoxidizing
substance is applied to or foamed onto the underside of the second
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layer and bonded thereto, the sealing disc is inserted with the
surface of the first layer in a closure cap or fitted with the
underside of the third layer on a container or inserted in a
container mouth, and, as a result of loading the closure cap when
it is rolled onto or otherwise secured to the container, the
sealing disc is compressed to a thickness which is less than its
production thickness.
There is thus provided a sealing disc, in particular for bottle
closures for substances, alcoholic drinks or wines which react
with oxygen, which on the one hand prevents, for example, the
gaseous alcohol constituent contained in the alcoholic drink or
wine from passing out through the sealing disc and on the other
prevents oxygen or other unwanted gases from entering the bottle.
A quantity of oxygen inevitably also trapped between the bottle
contents and the closure upon closing the bottles is absorbed by
the deoxidizing substance, for example Daraform. The constituent
which makes an opened wine unpalatable after a short time is thus
removed from the unopened wine bottle. The wine therefore keeps
longer and is not subject to any degradation. Together with the
storage time and temperature, the effect of oxygen on the wine may
lead to undesirable changes in the taste of the wine. The addition
of sulphur to wine, which normally gives rise to general concern,
increasingly in terms of health, can then be reduced or dispensed
with entirely. The sealing disc also contributes to efforts on the
part of, for example, the European Community to improve hygiene.
No bacteria which, like those on conventional corks, are on the
European prohibited list can settle on it.
The distinct cost advantage, with improved efficiency, in relation
to corks should also be emphasised.
Generally speaking, a sealing disc for a closure cap for
containers, in particular for bottle closures for substances,
alcoholic drinks or wines which react with oxygen, is provided
which comprises a layer of an oxygen-tight substance and a layer
of a deoxidizing substance on the side of the sealing disc which
is to face the container contents.
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It preferably comprises another layer of polyethylene foam above
the layer of the oxygen-tight substance. The sealing disc is
advantageously covered by an aluminium screw-type closure on the
side of its first layer of polyethylene foam. The underside of
the polyethylene layer is covered over its entire surface by the
layer of the oxygen-tight substance, preferably polyvinylidene
chloride. The underside of the layer of the oxygen-tight substance
is covered by the layer of a deoxidizing substance. The underside
of the layer of the deoxidizing substance faces the container
contents.
The deoxidizing substance is preferably of the type which only
acts in this capacity under certain external conditions, for
example under pressure or when the ambient moisture content is at
a certain level. This enables the sealing disc to be handled,
produced, stored and fitted under normal external conditions and
thus with the usual oxygen present in the ambient air. The
deoxidizing effect only develops in the filled container due to
the resulting pressure above atmospheric and/or moisture content.
The deoxidizing layer advantageously comprises the deoxidizing
substance polyolefin carboxylic acid, especially as a copolymer
together with other polyolefins. A product marketed under the
trade name Daraform is particularly suitable. Ethylenevinyl
alcohol copolymer or another material of this kind may
alternatively be used. The Daraform layer is rendered extrudable
so that it can be applied to the polyvinylidene chloride layer. It
thus has a clean, firm consistency.
Daraform cannot be faulted from the sensory aspect, i.e. there is
3U no effect in terms of taste on the contents of the bottle, and
hence particularly the wine, which also remains unimpaired in
other respects - for example visually.
The layer of polyethylene foam preferably has a density of
250 g/m2 and a thickness of 2 mm, the layer of polyvinylidene
chloride preferably a thickness of 19 um and the layer of Daraform
a thickness of 0.25 to 0.5 mm.
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The sealing disc is produced in a process in which the underside
of the first layer of polyethylene foam is firstly covered over
its entire surface with the second layer of an oxygen-tight
substance and bonded thereto. The third layer of a deoxidizing
substance is then applied to or foamed onto the underside of the
second layer and bonded thereto.
The sealing disc can either be fitted in the closure cap before
the aluminium screw-type closure is screwed down or secured to the
container edge by the underside of the third layer in another way.
It may, for example, also be firstly placed on a bottle neck
opening, particularly with the third layer inserted in the
container mouth, after which the aluminium screw-type closure can
be pulled over it. A load in the form of a compressive load is
applied when the aluminium screw-type closure is screwed down,
rolled onto or otherwise secured to the bottle neck. The sealing
disc is thus compressed to a thickness which is less than the
production thickness.
It is particularly preferable for the layer of a deoxidizing
substance to have a smaller surface diameter than the other layers
of the sealing disc, in particular a surface diameter which is
smaller than the inside diameter of the associated container mouth
which is to be sealed.
The additional advantage of this lies in the fact that, after the
container closure with the sealing disc has been applied, the
layer with the deoxidizing substance only comes into contact with
the container contents, or the gaseous fraction below the closure,
not with the ambient atmosphere, which could otherwise still reach
the edge of this layer within the closure to a certain degree.
The polyvinylidene chloride layer performs a dual function.
Firstly, it prevents gaseous constituents such as alcohol, for
example, from passing outwards from the inside of the bottle
through the sealing disc. Secondly, it prevents oxygen or other
gases from entering the region of the Daraform layer. By means of
a compressive force (with elastic recovery), the polyethylene foam
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layer which is preferably provided over the polyvinylidene
chloride layer provides the appropriate clamping pressure and thus
a seal. Tolerances of the closures and bottle necks are
compensated by the thickness of the layer and the elastic
formation thereof. Any fluid (also in vapour form) which could
penetrate into the bottle from outside, for example, is thus
prevented from doing so. Moreover, because it is substantially
thicker than the other two layers, the polyethylene foam layer
makes the sealing disc stable and particularly easy to handle.
In order to illustrate the invention further, several embodiments
of sealing discs will now be described with reference to the
drawings, in which:
Figure 1 is a perspective view of a bottle with a closure cap
comprising a sealing disc according to the invention;
Figure 2 is a perspective view of the sealing disc according to
the invention which is shown in Figure 1;
Figure 3 is a perspective view of a second embodiment of a sealing
disc according to the invention; and
Figure 4 is a sectional view of a third embodiment of a sealing
disc according to the invention.
Figure 1 is a perspective view of a bottle 1 with a closure cap 2
comprising a sealing disc 3. The closure cap 2 is a screw-type
closure. It is shown broken open in part to illustrate the
internal sealing disc 3. The closure cap 2 is made of aluminium,
for example.
The sealing disc 3 consists of three layers. The top layer 4,
which is connected to the closure cap 2, is made of polyethylene
foam. A layer 5 of polyvinylidene chloride is provided below the
layer 4. A layer 6 of a deoxidizing substance, for example
Daraform, is provided below the layer 5 and thus directly adjacent
to the bottle neck edge and resting on its opening.
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The layer 6 of Daraform removes from the closed bottle the oxygen
which is also introduced into the bottle when the latter is filled
with the alcoholic drink, for example, in particular wine. The
oxygen which is also trapped when using conventional wine bottle
closures, in particular corks, although also twist closures with
conventional sealing discs, may cause the wine to "turn~. It may
in any case change the taste of the wine. The Daraform layer 6
removes this oxygen and thus enables the quality of the bottle
contents, in particular wine, to be preserved.
The action of covering the layer 6 of Daraform by the layer 5 of
polyvinylidene chloride ensures that the Daraform layer 6 only
absorbs oxygen from below, i.e. from the inside of the bottle, and
not from outside from the area around the bottle. The quantity of
oxygen which is thus withdrawn and absorbed can therefore be
ascertained and is relatively slight. The purpose of the Daraform
layer 6 is not therefore to remove from a bottle which has been
opened and then re-closed the oxygen which has penetrated upon
opening and partly emptying the latter or to preserve the bottle
contents, but rather just to absorb the oxygen originally
penetrating when the bottle is filled, as well as any oxygen still
escaping from the wine.
The layer 5 of polyvinylidene chloride thus prevents gas from
passing into the inside of the bottle and from the latter to the
outside. It is in particular impossible for the alcohol to escape
from the inside of the bottle as a gaseous constituent. Oxygen
from the area around the bottle cannot pass inwards into the
region of the Daraform layer or through this.
The layer 4 of polyethylene foam serves on one hand as a means for
connecting the two other layers to the closure cap 2. It is,
however, also possible to select a layer of a different material
with corresponding properties instead of the polyethylene foam
layer.
Figure 2 is a perspective view of the sealing disc 3 according to
the invention which is shown in Figure 1. The top layer 4 of
polyethylene foam has a density of, for example, 250 g/m2. The
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layer is approximately 2 mm thick. The top surface 7 of the layer
4 of polyethylene foam bears directly against the inside of the
closure cap 2 after being inserted in the latter and is held in a
retaining bead in the closure. However it may also be secured in
the closure by means of an adhesive. The layer's own adhesive or
bonding action is in some cases sufficient to secure it in the
closure cap 2.
The layer 4 of polyethylene foam is covered over the entire
surface of its underside 8 by the middle layer 5 of polyvinylidene
chloride. Polyvinylidene chloride is a double chloride compound,
which is also called PVDC film. The company Dow Chemical produces
polyvinylidene chloride under the trade name "Saran". The layer 5
of polyvinylidene chloride is of a thickness of, for example,
19 um. This very slight thickness of the layer 5 is sufficient to
develop the barrier effect, in particular for the gaseous alcohol
and against the entrance of the gaseous oxygen.
The bottom layer 6 of the deoxidizing substance Daraform is
provided at the underside 9 of the layer 5. The product name
Daraform of the company Grace Chemicals designates in chemical
terms a mixture of polyolefin carboxylic acid with other
polyolefins, also prepared as copolymers. Daraform is entirely
PVC-free and binds oxygen. The third layer 6 of Daraform is
approximately 0.25 mm or 0.5 mm thick, for example. In order to
apply it to the underside 9 of the middle layer 5 of
polyvinylidene chloride, the bottom layer 6 is extruded from
Daraform. This gives it a clean, firm consistency.
After the three layers 4, 5, 6 have been joined together, the
overall thickness of the sealing disc 3 is approximately 2.3 mm.
The sealing disc 3 is either firstly inserted in a prefabricated
aluminium closure cap 2 in which it is secured or clamped in
place. The three layers 4, 5, 6 of the sealing disc 3 already
adhere to one another in this case. If the aluminium closure cap 2
is rolled on or otherwise secured to the bottle neck, this cap is
additionally subjected to a load of 120 to 180 kg. The sealing
disc 3 lying in the closure is as a result compressed to a
thickness of approximately 1 mm. The inside of the bottle is
~ CA 02203744 1997-04-2~
thereby hermetically sealed by means of the sealing disc 3 and the
closure cap 2.
According to the field of application of the sealing disc 3, it
may be advisable to make the Daraform layer 6 of a thickness other
than that specified. The sealing disc 3 is not only suitable for
closures for wine bottles or other alcoholic drinks, but for all
cases in which the inside of a container with trapped, unwanted
oxygen is to be deoxidized.
The underside 10 of the bottom layer 6 of Daraform is directly in
contact with the inside of the bottle and thus the oxygen trapped
in the latter. Daraform is resistant to alcohol, tartaric acid and
other substances which are used in the food sector and, moreover,
cannot be faulted from the sensory aspect. If a deoxidizing
substance other than Daraform is used, there should be no
possibility of this other substance being affected by the contents
of the bottle. Where wine bottles are concerned, the substance
should therefore be resistant to alcohol and tartaric acid, for
example.
Figure 3 is a perspective view of a second embodiment of a sealing
disc 3 according to the invention. The sealing disc 3 comprises a
top layer 5 of polyvinylidene chloride and a bottom layer 6 of a
deoxidizing substance, for example Daraform. Although the sealing
disc 3 could be produced just from Daraform, this would be
comparatively expensive, as Daraform costs many times as much as
polyethylene foam. Apart from this consideration, this single
layer of Daraform would not only absorb the oxygen from inside the
bottle, but also draw in and absorb the oxygen from the area
around the bottle. It is therefore far better to cover the top
surface 13 of the Daraform layer 6 with the barrier layer of
polyvinylidene chloride. A closure cap 2 can then also be provided
directly over this layer 5 of polyvinylidene chloride.
Figure 4 is a sectional view of a third embodiment of a sealing
disc 3 according to the invention. Here a middle layer 5 of
polyvinylidene chloride can be seen below the top layer 4 of
polyethylene foam and, beneath this middle layer 5, a bottom layer
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6 of Daraform. Whereas the layers 4 and 5 have the same surface
diameter, the layer 6 is smaller.
If the disc is now imagined to be in a closure cap and this on a
container mouth as in Figure 1, for example, the layer 6 of
Daraform projects slightly below the container mouth into the
container, while the layer 5 lies exactly on the container mouth.
Together with the container, this prevents any oxygen from
entering, so that the layer 6 is only confronted with the oxygen
inside the container.
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11
List of reference ~-rs
1 bottle
2 closure cap
3 sealing disc
4 layer of polyethylene foam
layer of polyvinylidene chloride
6 layer of deoxidizing substance/Daraform
7 top surface
8 underside
underside
underside
13 top surface
