Tamper evident security bag

Abstract

 The invention is intended to improve the security of tamper evident security bags (30) of the type having a tamper evident security tape (10) attached by heat seal to the remainder of the bag.
Bags of this type are susceptible to interference by cutting the security tape (10) close to the heat seal, interfering with the contents of the bag, then attaching a closure portion from another unused bag over the cut to conceal the tampering. Accordingly the invention provides a security bag in which an externally visible random or pseudo-random pattern (60) is applied to the bag in the region of the join (70) between the security tape and the remainder of the bag so that any attempt to superimpose the security tape from another bag is exposed by a lack of registration of the patterns (60).

Description

[0001] This invention relates to tamper evident security bags, and particularly to a self-seal bag having a closure flap or tape which is adapted to provide an indication of any illicit attempt to open and re-close the bag.

[0002] The state of the art currently includes such closures as described in our earlier British Patent No. 2327933 and European Patent No. 0628007. In general, tamper evident closures comprise a seal for two surfaces which can be contacted together to close the seal; generally at least one surface is coated in adhesive so as to close the seal. Common features which provide an indication of any illicit attempt to open and re-close the container including the seal include: at least one surface being made from a material which will deform when an attempt is made to pull them apart; at least part of at least one surface being coated with thermochromic ink which may change colour when heated or when cooled (heating or cooling can be used to lower the tack of the adhesive such that the seal can be opened and re-closed without deforming the container); at least part of at least one of the surfaces being treated with a solvent evident ink (this will indicate when an attempt has been made prior to closure to cover one surface in a substance to lower the adhesion caused by the adhesive); at least one portion of a surface being treated with a discontinuous pattern of adhesive and ink (this will indicate when the bag has been successfully opened and re-closed as the pattern will not match). Of course various combinations of these features can be provided to indicate different methods of tampering, and the features can be on either of the surfaces. It will be evident to the skilled man that a surface which has none of these features but cooperates with a surface having a tamper evident feature will nonetheless still be a tamper evident closure portion.

[0003] Frequently such tamper evident closures are formed as a tape and heat-sealed or otherwise attached to a portion of a bag. However, where this is the case, there is a problem that the bag can be interfered with in the following way, without obvious evidence of tampering: the tape can be cut close to the heat seal, so as to gain access to the inside of the bag without disturbing the tamper evident portion of the tape and then a strip of tape from another unused bag can be stuck over the cut tape effectively hiding the cut.

[0004] Accordingly the present invention provides a security bag formed of sheet material comprising a tamper evident closure portion a part of which is superimposed on a first portion of the sheet material and joined to it in the region of the superimposition; wherein an externally visible random or pseudo-random pattern is applied to at least part of a surface of the closure portion in the region of the superimposition and extends beyond the superimposition in one direction so that any attempt to superimpose another tamper evident closure portion to conceal damage caused by tampering is exposed by the lack of registration of the patterns.

[0005] By making the pattern random or pseudo-random it will be even more unlikely that the tampering could be concealed as it will be unlikely that the perpetrator will be able to locate a closure portion having the same pattern as the adjacent portion of the tampered container. The term pseudo-random pattern is used to describe a series of features which appears to be random but is in fact generated according to some pre-arranged sequence. For example it may be a pattern which repeats over a long distance relative to the width of the bag.

[0006] In a further aspect of the invention, there is provided a security bag formed of sheet material comprising a tamper evident closure portion a part of which is superimposed on a first portion of the sheet material and joined to it by a heat seal in the region of the superimposition, and a part of which is adhesive to effect closure of the bag; wherein an externally visible pattern is applied to at least part of a surface of the closure portion in the region of the superimposition, the pattern spanning at least part of the heat seal so that any attempt to superimpose another tamper evident closure portion to conceal damage caused by tampering is exposed by the lack of registration of the patterns in the region of the heat seal.

[0007] In general, when security tape is heat sealed to a bag, the adhesive portion of the closure portion does not directly abut the heat seal, so access to the inside of the bag can be gained by cutting in the region between the heat seal and the adhesive portion. Since the entirety of the security tape cannot be removed because part of it is attached to the bag in the region of the heat seal, so long as the pattern extends over the heat seal and the adhesive portion the perpetrator cannot conceal the tampering by cutting off the security tape from one bag adjacent to the heat seal and sticking it over the cut in the tampered bag as the tampering would be exposed by the lack of registration of the pattern in the region of the heat seal.

[0008] It has been found that thieves have overcome current tamper indicating bags by coating the adhesive layer of the bags with a less powerful adhesive, such as PRITT stick prior to closure thus affording a weak bond which can be overcome at a later stage (perhaps when under less surveillance, or having been searched) at which point the contents of the bag can be interfered with, prior to final closure.

[0009] Accordingly a preferred embodiment of the invention provides a security bag wherein said tamper evident closure portion includes a discontinuous adhesive pattern on one surface.

[0010] In another aspect of the invention there is provided a tamper evident tape having a portion adapted to be attached to a security bag and a closure portion including a pseudo-random pattern spanning both portions.

[0011] In another aspect of the invention there is provided a tamper evident tape having a portion adapted to be heat sealed to a security bag and a closure portion including a part which is adhesive; the tape including a pattern extending over the portion adapted to be heat sealed and the adhesive portion.

[0012] In a further aspect of the invention there is provided a method of forming a security bag, comprising forming a tape having tamper evident features on one surface and a pattern visible on the opposite surface, the pattern comprising a series of features which appears to be random but is in fact generated according to some prearranged sequence, and cutting the tape into strips and attaching these strips to a container such that a portion of the strip forms a closure portion.

[0013] In a further aspect of the invention there is provided a method of forming a security bag according to any one of the preceding aspects, the method comprising-forming a tape having tamper evident features including adhesive on one surface and a pattern visible on the opposite surface, cutting the tape into strips and heat sealing a strip to a container such that a part of the strip forms a closure portion and the pattern spans at least part of the heat seal and at least part of the adhesive portion.

[0014] Some embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a schematic side view of a security bag in accordance with the invention.

Figure 2 shows a diagrammatic plan view of a security bag in accordance with the invention as shown in Figure 1.

Figure 3 shows a diagrammatic plan view of a piece of tape having an alternative pattern according to the invention.

Figure 4 shows a diagrammatic plan view of a piece of tape having another alternative pattern according to the invention.

Figure 5 shows a schematic side view of an alternative embodiment of the invention.

Figure 6 shows a schematic plan view of part of a security bag shown in Figure 5.

Figure 7 shows a schematic view of the underneath of the part of a security bag shown in figure 6.

Figure 8 shows a schematic plan view of part of a security bag shown in Figure 5.

[0015] Referring first to Figure 1, a security bag is illustrated, comprising a strip of preferably translucent or transparent tamper evident tape 10 attached to a preferably opaque bag 30 by a heat seal in zone 40 so as to form a tamper evident seal when the first (interior) surface 11 of the closure portion 50 of-the tape 10 contacts the first (interior) surface 21 of the closure portion 20 of the bag. In a preferred embodiment a pseudo-random pattern is printed on a first (interior) surface 11 of the transparent or translucent tamper evident tape 10 so as to be visible externally, as shown in Figure 2. The pattern may alternatively be printed on the second (exterior) surface 12 of the tamper evident tape 10 but it is preferable to print it on the internal surface since it will be appreciated that it will not be possible for a thief to remove the pattern with a solvent if it is printed on the interior surface.

[0016] Figure 2 shows an example of a pseudo-random pattern made up of a series of lines forming triangles 60 which span both the portion of the strip of tamper evident tape which forms the closure portion 50 and the portion of the tamper evident tape which is heat sealed to the bag so as to form a portion 70 of the bag adjacent to the closure portion 50.

[0017] Figure 3 shows an alternative embodiment of the invention, in which a piece of tamper evident tape 100 has a closure portion 500 and a portion adapted to be attached to a security bag by means of a heat seal in zone 700. In this case, it can be seen that the pattern is formed by a series of differently spaced words, in this case spelling "Misaligned?"

[0018] Figure 4 shows an alternative embodiment of the invention in which case the pattern 601 is regular, although in this case it will be simple for a person who has tampered with the bag to obtain a piece of tamper evident tape bearing the same pattern and stick this over the cut in the original tape, it will be difficult to line up the lines in the pattern correctly, and misalignment will indicate tampering. An embodiment such as this, in which the pattern is regular has the advantage that it is easier to produce.

[0019] Referring to Figures 5-8 which show a most preferred embodiment of a security bag according to the invention it can be seen from Figure 5 that the bag maintains all the same features as that of Figure 1 but further includes a foil release liner 80, foil release liners are well known in the art however, the foil liner of a most preferred embodiment has a folded part 90 extending away from the interior surface 11 of the closure portion 50.

[0020] It can be seen from Figure 6 that the top of the security bag includes a pseudo-random pattern, made up of a series of triangles 601 having gaps of a different size between them. This pattern can be printed or otherwise applied to the external surface, but in the preferred embodiment is printed on the internal surface of a transparent or translucent portion of the bag and therefore visible externally.

[0021] Figure 7 shows the tamper-evident features on the interior surface 11 of the tamper evident closure portion 50 of the tape 10 of a most preferred embodiment of the invention. As mentioned above, in this most preferable embodiment of the invention, the base material forming the tape 10 is transparent. As seen in Figure 6, the pseudo-random pattern of triangles 601 is printed on the internal surface of the tape. The strips marked 1 in the drawing have a pattern (preferably displaying a message such as "STOP") of silicone acrylate or other methods known to those skilled in the art to achieve a discontinuous release layer on the base material, and a layer of opaque ink coating this layer or a similar arrangement if this type, such as those described in European Patent No. 0493465 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 left by the release pattern, whereas the ink will come away from the interior surface 11 where the silicone acrylate is printed as it will adhere more strongly to an overlying adhesive The strips marked 2 in the drawing are printed with a thermochromic ink such as the type described in British Patent No. 2270857, preferably the ink changes from being transparent, translucent or light coloured to a bright colour, and more preferably the ink is arranged in a pattern, for example a series of words spelling "tampered" or "stop" thus on application of heat (or on cooling) the change in colour will be clearly visible through the transparent/translucent base material. The closure portion 50 has a final top coat of adhesive covering all the features except in the strips marked 3 thus forming a discontinuous pattern. The purpose of the strips marked 3 will become clear once the surface 21 has been described.

[0022] Figure 8 shows the tamper evident features on the interior surface 21 of the tamper evident closure portion 20 of the bag 30. As can be seen, there are two sections 4 and 5, both of which are coated in solvent detecting ink, which may change colour, or dissolve on contact with a solvent. In a most preferred embodiment, section 4 (nearest the top of the bag, facing the non-adhesive strips marked 3 on interior surface 11 of tape 10) is coated in a solid area of solvent detecting ink and section 5 is a layer of solvent detecting ink in a pattern, most preferably spelling a word, such as "void" the function of the patterned ink being to smudge on contact with a solvent whereas the combination of a solid area of solvent active ink opposite the strips marked 3 serves a different function. As mentioned above, it has been found that a weak (usually water soluble glue) is used to coat the adhesive portion of the bag in order to weaken the bond when the bag is closed and allow for later tampering, therefore the non-adhesive strips 3 are intended to be accidentally contacted with adhesive during tampering causing the ink to be in a more intimate relationship with the strips marked 3 thus changing the appearance of the seal in that portion as the colour of the ink will be more visible through the transparent/translucent base material of the bag.

Claims

1. A security bag formed of sheet material comprising a tamper evident closure portion a part of which is superimposed on a first portion of the sheet material and joined to it in the region of the superimposition; wherein an externally visible random or pseudo-random pattern is applied to at least part of a surface of the closure portion in the region of the superimposition and extends beyond the superimposition in one direction so that any attempt to superimpose another tamper evident closure portion to conceal damage caused by tampering is exposed by the lack of registration of the patterns.

2. A security bag formed of sheet material comprising a tamper evident closure portion a part of which is superimposed on a first portion of the sheet material and joined to it by a heat seal in the region of the superimposition, and a part of which is adhesive to effect closure of the bag; wherein an externally visible pattern is applied to at least part of a surface of the closure portion in the region of the superimposition, the pattern spanning at least part of the heat seal so that any attempt to superimpose another tamper evident closure portion to conceal damage caused by tampering is exposed by the lack of registration of the patterns in the region of the heat seal.

3. A security bag according to claim 1 or 2 wherein said tamper evident closure portion includes a discontinuous adhesive pattern on one surface.

4. A security bag according to claim 3 wherein said adhesive surface of the tamper evident closure portion opposes a surface on a second portion of sheet material which when contacted together seals the security bag and said surface on the second portion includes an ink pattern opposing at least part of the areas of the adhesive surface not covered by the adhesive pattern.

5. A security bag according to claim 4 wherein said ink is water-soluble.

6. A security bag according to any one of the preceding claims further including a foil release liner having a tab projecting from it.

7. A tamper evident tape having a portion adapted to be attached to a security bag and a closure portion including a pseudo-random pattern spanning both portions.

8. A tamper evident tape having a portion adapted to be heat sealed to a security bag and a closure portion, including a part which is adhesive; the tape including a pattern spanning at least part of the portion adapted to be heat sealed and at least part of the adhesive portion.

9. A method of forming a security bag according to any one of claims 1-6, comprising forming a tape having tamper evident features on one surface and a pattern visible on the opposite surface, the pattern comprising a series of features which appears to be random but is in fact generated according to some prearranged sequence, and cutting the tape into strips and attaching a strip to a container such that a portion of the strip forms a closure portion.

10. A method of forming a security bag according to any one of claims 1-6 comprising forming a tape having tamper evident features including adhesive on one surface and a pattern visible on the opposite surface, cutting the tape into strips and heat sealing a strip to a container such that a part of the strip forms a closure portion and the pattern spans at least part of the heat seal and at least part of the adhesive portion.

Drawing