[0001] This invention relates to tamper indicating packages and labels, and in particular,
to packages made of plastics materials, of a type which are commonly used for transporting
cash or other valuables, and which are arranged so as to ensure that no tampering
with the contents is possible, without such tampering being made immediately obvious
on inspection.
[0002] One known system of this kind is shown in our WO91/04199 entitled "Tamper Indicating
Package", which discloses, inter-alia, a tamper indicating sealing tape, label or
package including a transparent or translucent flexible plastics base material, a
pattern printed on the base material in a silicone acrylate which forms a discontinuous
release layer, a layer of opaque ink applied over the release pattern, and a layer
of adhesive applied over the opaque ink.
[0003] The effect of this arrangement is that if the seal is peeled apart, the ink will
be left on the base material, in the intervening spaces formed by the silicone acrylate
release pattern, whereas they will come away from the base film, in the filled areas
of the silicone acrylate pattern, because the adhesive will cause them to adhere more
strongly to the overlying material in those areas.
[0004] The pattern of the release layer preferably spells out some wording such as "void",
and thus, if the ink layer is opaque, and the base film is transparent or translucent,
these words will be revealed, as soon as the seal is pulled apart, and it will then
be very difficult for the interrupted areas of ink to be reconstituted in such a way
that the wording is no longer visible.
[0005] Basically, systems of this kind depend on the fact that the ink has low cohesive
strength, and will adhere to whichever surface has the greatest surface energy. In
particular, seals of this kind are useful to prevent opening of the bag by freezing
it, which reduces the adhesivity of the adhesive. In most such existing systems, the
adhesive layer, and the ink layer are made continuous, and the discontinuities are
provided by the silicone release layer. However, such an arrangement does have the
disadvantage that it is necessary to apply three successive coatings to the material,
i.e. the release layer, the ink, and the adhesive.
[0006] The present invention therefore seeks to provide a tamper evident sealing system
which has improved performance and at the same time is simpler to manufacture.
[0007] Accordingly, the present invention provides a closure for a security bag or a security
label, comprising a seal for two surfaces which can be contacted together to close
the seal, and including an ink pattern and an adhesive pattern, characterised in that
both patterns are comprised of sets of strips or lines which are so arranged that
they overlap, but do not match, at least after the seal has been closed.
[0008] In one embodiment of the invention the ink pattern is applied first to one of the
surfaces to be sealed, and overlaid by the adhesive pattern.
[0009] When this surface is brought into contact with an opposing surface, so as to form
a seal, because the ink adheres more strongly to the adhesive on one side, than to
the surface on the other, any attempt to open the seal results in the ink pattern
being "broken up", because those areas which coincide with the adhesive will become
transferred with the adhesive to the opposing surface, whilst those areas which do
not coincide with the adhesive will, of course, remain on the original surface on
which they were printed. In this way, a very distinct disruption of the seal area
is produced, making it extremely difficult or impossible to reseal the bag without
this being apparent.
[0010] In another embodiment of the invention the ink pattern is applied to one surface
and the adhesive is applied to the opposing surface. Because the ink receiving surface
must be of low surface energy great care must be used to ensure that the pattern is
not damaged by normal handling before the seal is achieved. These embodiments ensure
tamper evidence both at normal operating temperatures and when the adhesive strength
of the adhesive has been diminished by low temperatures.
[0011] Normally, in order to achieve a required level of adhesivity, on a polythene surface,
for example, the supporting surface is first treated by corona discharge so as to
increase surface energy and the surface is subsequently treated with a coating which
reduces the surface energy to a predetermined degree for example, a coating of silicone
acrylate or a blend of a silicone copolymer with other polymers or copolymers. However,
a similar effect may be achieved more simply by leaving the surface untreated and
instead, using an ink which has adequate bonding to the surface. These inks include
those which are based on nitro-cellulose and polyamides, possibly modified by the
addition of wax to obtain the right balance of adhesive and cohesive strengths. Additionally
or alternatively, titanium esters may be added to increase the temperature resistance,
and nitro-cellulose urethane inks with titanates may also be utilised. On other surfaces
more appropriate ink vehicles may be used including inks which are cured by UV light
and use water rather than solvents as their diluent.
[0012] The adhesive strips or lines may be applied in straight lines or in undulating lines
produced by moving the extruder head across the substrate or conversely moving the
substrate across the glue head.
[0013] In a further alternative embodiment of the invention the adhesive pattern is applied
first to one of the surfaces and the ink pattern is superimposed on it.
[0014] In this embodiment tamper evidence can be achieved even when the cohesive strength
of the adhesive has been diminished e.g. by high temperatures, in addition to the
situation at normal and low temperatures. This is because the failure of the seal
by cohesive failure still results in ink being transferred from one surface to the
other and matching of the pattern becomes extremely difficult.
[0015] The application of the ink over the adhesive surface is best carried out by a non-contacting
process such as an ink jet printer.
[0016] Some embodiments of the invention will now be described by way of example, with reference
to the accompanying drawings in which:
Figure 1 is a plan view of part of a bag closure flap of a first type in accordance
with the invention;
Figure 2 is a plan view of a closure of a second type;
Figure 3 is a schematic view of a security bag incorporating a closure of the type
shown in Figure 1;
Figure 4 illustrates a second type of bag incorporating a seal according to the invention;
Figure 5 illustrates a third example of a security bag;
Figure 6 illustrates a fourth example of a security bag; and
Figure 7 is a partial view of an alternative form of seal in accordance with the invention.
[0017] Referring first to Figure 1, a small section of a sealing flap for a security bag
is illustrated, comprising a region 2 extending along one edge of the flap, which
is adapted to be heat sealed onto a corresponding edge of the bag to be sealed, for
example along the top edge of the bag as illustrated in Figure 3. The main body of
the flap 4 carries a series of transversely extending glue lines, and preferably,
as shown, these comprise a number of narrow lines 6, 8, 10 etc, and a broader line
12 which is positioned so that in use, it overlies a slit 14 in the face of the bag,
which forms the normal opening.
[0018] Before the lines of glue are applied to the flap, as illustrated, it is printed with
a distinctive non matching opaque ink pattern comprised of sets of strips or lines.
After application of the glue, the exposed glued surface is covered with a silicone
release tape to protect it, before the bag is closed. As can be seen from Figure 3,
when the release tape is removed and the flap is pressed down over the mouth of the
bag to close it, the lines of glue will adhere to the face of the bag, and in particular,
the glued area 12 will effectively seal the slit opening 14.
[0019] If an attempt is then made to peel away the flap from the face of the bag, the ink
pattern will become detached from the flap, in those areas that coincide with adhesive
lines, whereas the ink will remain on the flap, in the intervening areas, and thus,
the printed ink pattern will be clearly disrupted. For this purpose, the ink must
have a relatively low cohesive strength, so that the pattern will be clearly broken
at the interface between the glued and non glued regions.
[0020] Alternatively, instead of being attached with a heat seal, as suggested in Figure
1, the flap illustrated in Figure 2 carries a further area of adhesive on its edge
2a, and otherwise functions in the same way as the flap of Figure 1.
[0021] Figures 4, 5 and 6 illustrate various different ways of arranging the adhesive stripes
on the flap, such as lengthwise of the flap as illustrated in Figures 4 and 5, and
of arranging the flap itself Figure 6. In the latter case, where it will be seen that
the flap is connected to the bag below the mouth, the arrangement may be of the "double
seal" type as exemplified by our British Patent No. 2,145,997.
[0022] The above examples are of the general type in which the flap is first printed with
a distinctive ink pattern, and the glue lines are subsequently laid down on top of
the ink. However, in an alternative arrangement illustrated diagrammatically in Figure
7, the arrangement may be "inverted" with lines of adhesive 20 applied first to a
corona treated plastics (e.g. polythene) flap surface, and very narrow lines 22 of
ink, subsequently laid down on top of the adhesive. Obviously, it is undesirable to
use a "contact method" of applying the ink onto a surface already carrying adhesive,
and it has been found that a good non contact method of applying the ink, is to use
an "ink jet" printer. This also has the advantage that a complex and "programmable"
pattern can then be laid down under automatic control (for example by computer) and
in this way the seal can embody a code which can be automatically read at the receiving
end of the package, and which will be unreadable if the seal has been tampered with.
For example, the pattern could be made to form a "bar code".
[0023] In use, the surface that the flap is brought into contact with, to form the seal,
is preferably treated, for example by the known process of corona discharge, so that
the adhesive lines will adhere strongly to it, and thus, if a subsequent attempt is
made to peel the seal apart, the considerably greater cohesive strength of the lines
of adhesive will cause the narrow "bridging" regions of ink to break, thus ensuring,
as before, that the overall pattern is visibly disrupted.
[0024] As a further precaution against unauthorised opening of the seals by freezing or
heating, it is also envisaged that any of the arrangements discussed above could be
modified by incorporating parallel sets of glue lines, comprising adhesive with different
operating temperature ranges. For example, there could be three sets of glue lines,
a first one of which has a normal operating temperature range such as -5°C to +30°C,
whilst the next adjacent one has a very low operating range as much as -30°C to +10°C,
and the final set has a high operating range such as 25°C to 60°C. It will be appreciated
that the glue lines having the "colder" operating range must be confined between other
sets, since, at normal ambient temperatures, they will be liquid and likely to "run
out". Such an arrangement will, therefore, protect the bag against tampering, even
if it is frozen to a very low temperature or heated to a very high temperature, because
there will always be one or other set of patterns which is disrupted by the subsequent
tampering.
[0025] Although the examples have been described specifically as having both the ink and
adhesive pre-coated onto the same surface, it will also be appreciated that, particularly
in the case of a bag closure, it would be possible to apply the pattern of adhesive
to one surface and the pattern of ink to the other surface, since the effect of the
finished closure will still be the same.
[0026] While the invention is particularly suitable for sealing devices it may also be used
for labels where it is desirable that the removal of a label should be evident both
on the label itself and the surface from which it has been removed. This is particulary
valuable if the bar code design is incorporated thereby preventing the switching of
bar coded labels which may give incorrect specification or price.
1. A closure for a security bag or a security label, comprising a seal for two surfaces
which can be contacted together to close the seal, and including an ink pattern and
an adhesive pattern, characterised in that both patterns are comprised of sets of
strips or lines which are so arranged that they overlap, but do not match, at least
after the seal has been closed.
2. A closure according to claim 1, in which the ink pattern is applied to one of the
surfaces, and the adhesive pattern is then applied over the ink pattern.
3. A closure according to claim 1 in which the adhesive pattern is applied to one of
the surfaces, and the ink pattern is then applied over the adhesive pattern.
4. A closure according to any preceding claim in which the ink is applied by means of
an ink jet printer.
5. A closure according to claim 1 in which the ink pattern is applied to one of the surfaces,
and the adhesive pattern is applied to the other surface.
6. A closure according to any preceding claim in which the adhesive strips are laid down
in an undulating pattern by moving the extruder head and the receiving substrate relatively
to one another.
7. A closure according to any of claims 1 to 6 for a bag made from polythene, in which
the ink is based on nitro-cellulose and polyamides.
8. A security bag having a closure according to claim 7, the bag being made from polythene,
in which the ink also includes wax and/or titanium esters.
9. A closure according to any of claims 1 to 6 in which the ink is based on nitro-cellulose
urethanes and includes titanates.
1. Verschluß für eine Sicherheitstasche oder eine Sicherheitsmarke mit einem Siegel für
zwei Oberflächen, die zum Schließen des Siegels in gegenseitige Berührung gebracht
werden können, und mit einem Tintenmuster und einem Klebstoffmuster, dadurch gekennzeichnet,
daß beide Muster aus Gruppen von Streifen oder Linien bestehen, die so angeordnet
sind, daß sie sich wenigstens nach dem Schließen des Siegels überlappen, aber nicht
zusammenpassen.
2. Verschluß nach Anspruch 1, bei dem das Tintenmuster auf eine der Oberflächen aufgebracht
ist und das Klebstoffmuster dann über dem Tintenmuster aufgebracht ist.
3. Verschluß nach Anspruch 1, bei dem das Klebstoffmuster auf eine der Oberflächen aufgebracht
ist und das Tintenmuster dann über dem Klebstoffmuster aufgebracht ist.
4. Verschluß nach einem vorhergehenden Anspruch, bei dem die Tinte mittels eines Tintenstrahldruckers
aufgebracht ist.
5. Verschluß nach Anspruch 1, bei dem das Tintenmuster auf eine der Oberflächen aufgebracht
ist und das Klebstoffmuster auf die andere Oberfläche aufgebracht ist.
6. Verschluß nach einem vorhergehenden Anspruch, bei dem die Klebstoffstreifen durch
Bewegung des Ertruderkopfes und des aufnehmenden Substrats relativ zueinander in einem
wellförmigen Muster abgelegt sind.
7. Verschluß nach einem der Ansprüche 1 bis 6, für eine Tasche aus Polyethylen, bei dem
die Tinte auf Basis von Nitrocellulose und Polyamiden gebildet ist.
8. Sicherheitstasche mit einem Verschluß nach Anspruch 7, wobei die Tasche aus Polyethylen
besteht und die Tinte auch Wachs und/oder Titanester enthält.
9. Verschluß nach einem der Ansprüche 1 bis 6, bei dem die Tinte auf Basis von Nitrocelluloseurerhanen
gebildet ist und Titanate enthält.
1. Fermeture pour sachet de sécurité ou étiquette de sécurité, comprenant une garniture
pour deux surfaces qui peuvent être mises en contact ensemble afin de fermer la garniture,
et comprenant un motif à l'encre et un motif adhésif, caractérisée en ce que les deux
motifs sont constitués d'ensembles de bandes ou de lignes qui sont agencés de telle
sorte qu'ils se chevauchent, mais ne se correspondent pas, au moins après que la garniture
a été fermée.
2. Fermeture selon la revendication 1, dans laquelle le motif à l'encre est appliqué
sur une des surfaces, et le motif adhésif est ensuite appliqué sur le motif à l'encre.
3. Fermeture selon la revendication 1, dans laquelle le motif adhésif est appliqué sur
une des surfaces, et le motif à l'encre est ensuite appliqué sur le motif adhésif.
4. Fermeture selon l'une quelconque des revendications précédentes, dans laquelle l'encre
est appliquée à l'aide d'une imprimante à jet d'encre.
5. Fermeture selon la revendication 1, dans laquelle le motif à l'encre est appliqué
sur une des surfaces et le motif adhésif est appliqué sur l'autre surface.
6. Fermeture selon l'une quelconque des revendications précédentes, dans laquelle les
bandes adhésives sont disposées selon un motif ondulant en déplaçant la tête de filière
et le substrat récepteur l'une par rapport à l'autre.
7. Fermeture selon l'une quelconque des revendications 1 à 6 pour un sachet en polythène,
dans laquelle l'encre est à base de nitrocellulose et de polyamides.
8. Sachet de sécurité ayant une fermeture selon la revendication 7, le sachet étant tait
en polythène, dans lequel l'encre comprend également de la cire et/ou des esters de
titane.
9. Fermeture selon l'une quelconque des revendications 1 à 6, dans laquelle l'encre est
à base d'uréthanes de nitrocellulose et comprend des titanates.