GB2200337A - Plastic bags - Google Patents

Abstract

A tamper-evident plastics bag for bank notes is made from a transparent plastics film and has a closure flap 19 which is foldable over the mouth of the bag and is formed with a band 20 of a pressure-sensitive adhesive by which to attach the closure flap permanently over the bag mouth for closure. In order to provide evidence of an attempt to open the bag using a solvent on the adhesive, the adhesive band is patterned so as to be formed of a plurality of portions or discrete elements having mutually opposing free edges which are difficult or impossible to reinstate after removal without leaving visual evidence of the fact. <IMAGE>

Description

PLASTIC BAGS This invention relates to plastics bags, particularly (but not exclusively) plastics bags for holding bank notes for transit, for example, between a clearing bank and its retailer customers or between different branches of a clearing bank.

Such bags for bank notes are known which comprise an elongate strip of plastics film which is folded in two approximately midway along its length to form one folded end for the bag. At the opposite end of the bag the free ends of. the strip form the bag mouth, and usually one end of the strip is extended beyond the other so as to form a projecting flap which can be folded over the mouth for closure purposes. Heat seals are formed between the two webs of the bag down the sides of the bag, so that the bag is of elongate rectangular form with a mouth at one end, a folded end opposite the mouth, and two heat-sealed sides extending between the folded end and the mouth.

The bags are typically formed of polyethylene film; they are transparent so that any bank notes within them are visible, and can be tinted in accordance with a colour coding to indicate the denomination of the bank notes which they are to contain; for example, bags to contain 5 bank notes are tinted green.

In bank note bags of the known type described above the mouth of the bag is intended or adapted to be permanently closed after the bag has been loaded with bank notes. Closure may be effected by heat-sealing as in UK Patent Specification 2009707B, or it may be effected by an adhesive bond as in UK Patent Specifications 1536784, 1523933. The permanence of the closure is intended to ensure that access to the bank notes is only possible by cutting or tearing the plastics material of the bag, in which case readily visible evidence of the access should subsequently be available.

The present invention is concerned with bags of the kind arranged to be sealed closed by a permanent adhesive bond, and has as its object to provide easily visible indication of any attempt to gain access to the contents of the bag by opening the adhesive bond using a solvent.

Accordingly, the invention provides a plastics bag, which is substantially rectangular and formed from two superimposed webs which are attached together at or adjacent three of the edges of the bag and form a mouth adjacent the fourth edge, the mouth being defined between a marginal edge region of a front one of the two webs and a projecting flap portion of the back web which is foldable over the marginal edge region and permanently adherable thereto by an adhesive, wherein the adhesive is carried either by the flap portion or by the marginal edge region and extends across the flap portion or marginal edge region (as appropriate) as a patterned band, portions or of discrete elements of which have mutually opposing free edges which are difficult or impossible to reinstate after removal without leaving evidence of the same.

In order that the invention may be more fully understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Fig.l shows a typical bag to which the invention may be applied, when empty and open and in plan view; Fig.2 shows a detail of the empty and open bag as seen on the sectional line II-II of Fig.l and to an enlarged scale, showing the position of the patterned adhesive band; and Figs. 3A to 3J show various different forms of the adhesive band.

Referring now to the drawings, a bank note bag for holding a predetermined number of a desired denomination of bank notes is formed from an elongate rectangular strip of transparent but appropriately colour-tinted polyethylene film which is folded in two along an edge 10 (Fig.l) at one end of the bag to form superimposed front and back webs 11, 12 (Fig.2).

The webs 11,12 are heat-sealed together along lines 13 so as to define the sides of the enclosure formed by the bag. For security the heat-seal lines 13 are spaced inboard of the free side edges 14 of the webs to leave free skirts 15 down the bag side margins; also, a printed security line or band 16 is laid down inboard of and adjacent to each heat-seal line 13 so as to define the inward limit of the heat-seal line for tamper-indication purposes. A paper label 50 affixed to the front web enables information regarding the contents of the bag to be recorded.

The mouth of the bag, at the opposite end of the bag from the folded edge 10, is formed between the back web 12 and a marginal region 17 of the front web 11 adjacent its free edge 18. The back web is extended beyond the free edge 18 so as to form a closure flap 19.

As shown in Figs. 1 and 2, a band 20 of a pressure-sensitive adhesive is laid down on the upper surface of the closure flap 19 in parallel relation to the free edge 18 of the front web 11. The band is not shown in detail in Figs. 1 and 2, but its location is indicated in Fig.1 by the chain-dotted line 21 representing its rectangular envelope or outline.

The adhesive of the adhesive band 20 is capable of forming a permanent adhesive bond with the marginal region 17 of the front web 11 to close the bag when the flap is folded onto it after the bag has been loaded with bank notes. A removable barrier strip 22 covers the adhesive until required; as can be seen, it has a somewhat greater width than the adhesive band. In a modification the adhesive is provided by the top surface of-a double-sided adhesive tape of which the bottom surface is adhered to the back web 12.

Figs. 3A to 3J show some of the many different forms possible for the adhesive band 20. In the form illustrated in Fig.3A the band is formed of six longitudinally extending, rectilinear and parallel lines of adhesive 31 which are of equal width and are separated by spaces 32 having substantially the same width as the lines.

The band 30 is therefore laterally discontinuous and is interiorly provided wit pairs of opposed free edges 33 of adjacent lines. These free edges 33 are in addition to the free side edges 34 of the band as a whole, and because of them it is difficult or impossible for a criminal, having used a solvent on the adhesive of the band 20 for opening the bag, to reinstate the band without leaving readily visible evidence of tampering. A simple adhesive band, that is to say, one which extends continuously between the free side edges 34, could be much more easily reinstated.

Fig.3B shows a further possible form of the adhesive band 20 in which the band is formed of squares 36 of adhesive. The squares 36 are spaced apart longitudinally of the band 20 by spaces 37, and they individually extend for the full width of the band.

The band is therefore longitudinally discontinuous, having pairs of additional and interior free edges 38 provided by the opposed faces of adjacent squares and defining the spaces 37 between them. These free edges 38 serve the same tamper-evidence function as the interior free edges 33 in Fig.3A.

Fig.3C shows an adhesive band which is a variation of the band of Fig.3B with the adhesive laid down as circles 40 rather than as the squares 36. The band 20 is therefore again longitudinally discontinuous, with additional free edges 41 of semi-circular form.

Fig.3D shows a further adhesive band 20 which is longitudinally discontinuous. It is formed of elongate strips which are directed transversely of the band and which are alternately wide and narrow along the length of the band. The wide strips are denoted 42 and the narrow strips are denoted 43. Adjacent strips are separated by spaces 44 so as to provide additional free edges 45 within the band interior and having the same tamper-evidence function as the free edges 33, 38, 41 of the adhesive bands 20 described above.

Fig.3E shows to an enlarged scale, a part of an adhesive band 20 which can be considered as a variation of the band of Fig.3A. The thickness of the individual lines 31 is reduced and that of the spaces 32 is correspondingly increased. In addition, the lines 31 are wavy and generally sinusoidal rather than being straight as in Fig.3A.

Fig.3F illustrates the band of Fig.3E when provided with eleven lines 31 at a smaller spacing than before.

Fig.3G illustrates the band of Fig.3F when made longitudinally discontinuous by inclined but parallel interruptions 46. The band is thus both laterally and longitudinally discontinuous.

Figs. 3H and 31 show variations of the adhesive band of Fig.3A having a lesser number of lines and of differing thickness. In Fig.3H, two narrow lines 51 are spaced on either side of a further, wider line 52. In Fig.3I the adhesive band 20 is formed of one thick line 53 and one thin line 54 separated by a space 55. The thin line 54 is preferably disposed on the outboard side of the thick line 53, that is to say, adjacent the long free edge 56 of the closure flap 19. (See Fig.l).

In the forms of the adhesive band 20 described above, the band is formed of a plurality of elements which are discrete and spaced apart longitudinally and/or laterally of the band. The band 20 shown in Fig.3J, however, is formed as a single line of substantial thickness from a succession of scallops 60 disposed end-to-end. The band is preferably disposed with the concave faces 61 of the scallops facing the long free edge 56 of the closure flap, and by virtue of its undulations it provides a series of pairs of opposed free edge portions which provide the same tamper-evidence function as the opposed free edges of the bands previously described. One such pair of free edge portions has its edge portions indicated in Fig.3J by the reference 62.

Any suitable process may be used for manufacturing the bag. In one process bags are formed at high speed from a plastics film which is drawn from a reel and progressively folded longitudinally in two along what will eventually become the folded ends of the finished bags.

Adhesive is then laid down along the material to form the closure flaps 19 of the bags, after which transverse heat-seals are formed at intervals along the folded strip, and the strip is severed transversely between or along the heat-seals to form the individual bags.

In an alternative the bags are formed in transversely aligned pairs from a flattened seamless tube of the plastics film. A longitudinally extending strip is removed along the centre of one web of the tube to provide access to the back web at what is to become the flap portions of the pairs of bags. The patterned adhesive bands of the two formative lines of bags are then laid down side-by-side along the strip of material which is thereby revealed, the "tube" is longitudinally slit in half between the pairs of bands, and the two halves are transversely heat-sealed and cut to form the individual bags.

The adhesive of the band 20 may'be of any suitable kind; for example, it may be hot melt, solvent-based or water-based. It is formed by extrusion through one or more nozzle orifices which, depending on the form of the adhesive band, are laterally movable and/or have associated valving enabling the adhesive flow to be interrupted.

Rather than being located on the flap portion 19 as particularly described, the adhesive band may be located on the marginal region 17 of the front web 11.

The adhesive of the band should be visible through the material of the flap portion 17 to enable any evidence of tampering to be readily seen, and in order to enhance the visibility of the adhesive through the flap portion the adhesive may be pigmented with any suitable colour.

Claims (12)

CLAIMS:

1. A plastics bag, which is substantially rectangular and formed from two superimposed webs which are attached together at or adjacent three of the edges of the bag and form a mouth adjacent the fourth edge, the mouth being defined between a marginal edge region of a front one of the two webs and a projecting flap portion of the back web which is transparent and foldable over the marginal edge region and permanently adherable thereto by an adhesive, wherein the adhesive is carried either by the flap portion or by the marginal edge region and extends across the flap portion or marginal edge region (as appropriate) as a patterned band, portions or discrete elements of which have mutually opposing free edges which are difficult or impossible to reinstate after removal without leaving evidence of the fact.

2. A plastics bag according to claim 1, wherein the adhesive is a hot melt adhesive.

3. A plastics bag according to claim 1, wherein the adhesive is a water-based adhesive.

4. A plastics bag according to claim 1, wherein the adhesive is a solvent-based adhesive.

5. A plastics bag according to any preceding claim, wherein the adhesive band is longitudinally and/or laterally discontinuous and formed of a plurality of discrete and spaced elements.

6. A plastics bag according to claim 5, wherein the adhesive band is formed of a plurality of longitudinally extending and laterally spaced lines of adhesive.

7. A plastics bag according to claim 6, wherein the lines of adhesive are identical.

8. A plastics bag according to claim 6 or claim 7, wherein the lines of adhesive are non-linear.

9. A plastics bag according to claim 5, wherein the elements are spaced apart longitudinally of the adhesive band.

10. A plastics bag according to any claim of claims 1 to 4, wherein the adhesive band is formed as a single line of substantial thickness, the band being non-linear but deviating in a regular manner.

11. A plastics bag according to any preceding claim, wherein the adhesive is pigmented.

12. A plastics bag according to claim 1, of which the adhesive band is substantially as herein described with reference to any one of Figs. 3A to 3J of the accompanying drawings.