GB2265883A - Security bag - Google Patents

Abstract

A bag has front and rear walls 14, 15 formed of superimposed layers of plastics material joined to one another about the periphery of the rear wall to define an enclosure, the front wall having a terminal edge 35 defining one side of an access opening 18 into said enclosure and a strip of plastics material 30 carrying a band of adhesive 31 extending either side of said terminal edge for sealingly closing said opening, the strip of plastics material being adapted to give a visual indication of an attempted entry through said opening. <IMAGE>

Description

A BAG The present invention relates to a bag formed from plastics sheet material. The bag may be a courier bag or a security bag.

Security bags are desirable for the transportation of valuables, such as currency notes, or confidential documentation. For such bags it is important that they are constructed so as to be tamper evident ie, once closed. access into the interior of the bag is not possible either by entry through openings or by unsealing of the mouth of the bag without resulting in the visual evidence of such unauthorised entry.

It is known from UK patent 2149381 to construct a bag of generally rectangular shape from plastics material in which the bag is formed from two superimposed layers of material which are joined along one side by a fold line and are joined along the other three sides by a continuous seam. The mouth of the bag is defined by a slit formed in one of the sheets of material and the slit is totally sealed by a flap having a strip of adhesive which engages the sheet material on both sides of the slit.

According to the present invention, there is provided a bag having front and rear walls formed of superimposed layers of plastics material joined to one another about the periphery of the rear wall to define an enclosure the front wall having a terminal edge defining one side of an access opening into said enclosure and a strip of plastics material carrying a band of adhesive extending either side of said terminal edge for sealingly closing said opening, said strip of plastics material being adapted to give a visual indication of an attempted entry through said opening.

Various aspects of the present invention are hereina"fter described with refelellce to the accompanying drawings in which: Figure 1 is a schematic perspective view of a bag according to the present invention Figure 2 is a sectional view taken along line II-II in Figure 1; Figure 3 is a schematic cross-sectional perspective view of another embodiment of the present invention.

Referring initially to Figures 1 and 2, there is illustrated a bag 10 including a front wall 12 and a rear wall 14, both of which are formed from flexible sheet plastics material. The front wall 12 comprises a first front wall portion 15 and a second front wall portion 16 which are located side by side with adjacent marginal side portions 15a, 1 6a respectively overlapping. The overlapping portions 15a,16a define therebetween an access opening 18 into the enclosure 19 of the bag.

Preferably the rear wall 14 and first front wall portion 15 are formed from the same sheet material by a folding operation and are thus joined along the bottom edge of the bag 10 by a fold 20. The sides 21 of front wall portions 15 and 16 are joined to the periphery of the rear wall 14 by welded seams 24 and the top edge of both the front and rear walls 12,14 is defined by a welded seam 25. Accordingly the front wall 12 is continuously joined to the periphery of the rear wall 14 and thereby the enclosure 19 is totally bounded except for the access opening 18.

It is envisaged that the rear wall 14 and first front wall portion 15 may be formed from separate strips of material and that in such a situation the bottom edge would be formed by a welded seam instead of fold 20.

This facility enables the front wall portion 15 and rear wall 14 to be formed of different materials.

The rear wall 14 has an integral extension which defines a closure flap 30. A strip of high tack adhesive 31 covered by a releasable cover strip 32 is provided on the closure flap 30 . A suitable adhesive is a synthetic rubber based pressure sensitive hot melt adhesive. The strip of adhesive 31 is of sufficient width and is located on the flap in such a position that on folding of the flap 30 to overlie the front wall 12 the adhesive adheres to the exposed faces of the first and second front wall portions located adjacent to the upper edge 35 of the first front wall portion 15.

It will be appreciated that more than one strip of adhesive 31 may be provided if desired. It is envisaged that a strip of adhesive may be located on the exposed surface of overlapping portion 15a for adhesive contact with the strip of adhesive 31 in order to provide a very strong bond.

As shown in Figure 2, the band of adhesive 31 is shown to be located contiguous with the portion 16. It is envisaged that the band of adhesive 31 or a separate band of adhesive may also cover the upper marginal side portion of portion 16 located between edge 35 and seam 25. This enables an adhesive bond to continuously extend width wise from the fold of the flap to extend across the edge 35 and thereby totally seal access to the opening 18.

The welded seam 25 may be thickened during manufacture so as to define a definite fold line for the closure flap 30. If desired a separate crease line 40 may be formed in order to define a fold line for the flap.

As illustrated in Figures 1 and 2 the second wall portion 16 underlaps the first wall portion 15 and such an arrangement facilitates insertion of articles through the access opening 18. Also the second wall portion acts as a capture flap and helps retain articles within the enclosure 19 prior to closing of the access opening.

As indicated above, to seal the access opening 18 the cover strip 32 is removed and the closure flap 30 is folded to overlie the front wall 12 with the band of adhesive 31 contacting the exposed surfaces of the front wall portions 15,16 located either side of the upper edge 35. The band of adhesive 31 extends along the fuli length of the access opening 18 and so the access opening is totally closed thereby.

Access into the enclosure from the sides of the opening 18 is rendered difficult due to the sealing of the flap 30 to the front wall overlapping portions lSa, 16a but also due to the fact that the access path into the enclosure is extended by the amount of overlap between portions l5a 16a. This access path may also be made more restrictive by connecting the overlapping portion l5a to portion 16a at the end regions of edge 35 to thereby space the entry into opening 18 from the sides 21.

This may be achieved by a broad weld 70 (indicated schematically in Figure 1) or by spot welds.

In addition after sealing of the flap 30, both front wall portions 15,16 are held together and so loosely held articles will slide beneath the captive flap defined by the wall portion 16 rather than passing into the opening 18. Thus manipulation of articles for withdrawal through an unauthorised restricted opening is difficult.

In a modification it is envisaged that apertures 60 (shown in broken lines in Figure 1) may be provided in the overlapping portion 15a such that the adhesive strip 31 is able to engage the exposed surface of portion 16a. This mode of sealing the overlapping portions l5a 16a to one another may be the sole form of sealing or may supplement the sealing resulting from the adhesive strip 31 engaging to the exposed surfaces located either side of edge 35. The adhesive strip for bonding through apertures 60 may be the band of adhesive 31 or may be a separate band.

As seen in figure 2, it is also envisaged that a band of adhesive 80 protected by a removable cover strip 81 (similar to band 31 and cover 32) may be located in between the overlapping portions 15, 16a Thus after filling of the bag the cover strip 81 may be removed and the facing surfaces of portions 15, 16a may then be bonded to one another.

In the illustrated embodiment, the band 80 is shown as preferably extending beyond edge 35 so that the bands of adhesive 31, 80 make contact on closure of the flap and thereby create a strong bond.

When unauthorised entry is attempted by lifting of the flap 30, the adhesive strongly adheres to the material of the first front wall portion 15 and the flap 30 and resists separation. If the material from which flap 30 and wall portion 15 is formed is relatively thin distortion of the material within the vicinity of the band of adhesive may occur. Such distortion would provide a visual indication of an attempted entry.

Additionally, the flap 30 may be provided with a line of weakness 45, such as a line of perforations, which ruptures when the flap 30 is pulled away from the front wall portion 15. The line of weakness 45 is preferably located close to the outer edge of the band 31 to enable the outer portion of flap 30 to be removed leaving the remainder bonded to the front wall portion 15 without leaving a finger hold for lifting the remainder of the flap. This may be achieved by locating the line of weakness at or slightly in board of the outer edge of the band 31.

In addition, several lines of perforations 45a may be provided within the boundary of the adhesive band 31 in order to provide a progressive tearing feature ie. lifting of the flap 30 will result in the material rupturing at the first line 45a encountered and prevent further lifting of the flap.

Additionally, the second front wall portion 16 is formed from a layer having different physical properties to the first front wall portion 15, namely the second front wall portion 16 is chosen to have less resistance to distortion than the first front wall portion 15 This is conveniently achieved by using a thinner material for portion 16. Accordingly should it be possible to lift and separate the flap 30 from the first front wall portion 15 without causing deformation, then deformation of the second wall portion 16 would occur thereby giving a visual indication of an attempted entry.

In addition, should entry from the fold of the flap 30 be attempted, portion 16 would readily distort and again give a visual indication of an attempted entry.

Such an arrangement is particularly advantageous for the manufacture of security bags in which the rear wall 14 and flap 30 and first front wall portion 15 are formed from a heavy duty sheet material, such as for example 100 micron thermoplastics material and the second wall portion 16 is formed from a light gauge material such as for example 50 micron thermoplastics material. Accordingly choice of the material for the rear wall, flap 30 and front wall portion 15 can be made to accommodate the anticipated carrying loads of the bag and other requirements of the bag independently of the choice of material for the second front wall portion 16. The material for the second front wall portion 16 can be chosen to exhibit the desired distortion characteristics without imposing any load carrying restriction on the choice of material for the remainder of the bag.

It will be appreciated that other tamper evident features known in the art such as use of embossed seams, security printing and solvent detection inks may be incorporated in the bag construction of the present invention.

The thermoplastics materials for front wall portion 15 or 16 can be any stiitable plastics such as a polyolefin or a polyester. The material may if desired be a co-extrusion. The cover strip 32 for the adhesive 31 is preferably a high density polyethylene coated with a release agent such as silicone. The choice of the release agent and/or the material strip 32 is such as to deter welding of the strip 32 to the rear wall 14 during the severing operation.

In the bag 10 illustrated and described above the band of adhesive 3 1 is preferably a high tack adhesive which provides a permanent bond.

The band of adhesive may be defined by a continuous or intermittent line of adhesive directly applied to the bag or may be defined by double sided adhesive tape.

The provision of a high tack adhesive enables the closure flap to be permanently sealed and thereby renders the bag suitable for use as a security bag.

It is envisaged that the band of adhesive 31 may be a low tack adhesive which provides a resealable bond. This enables the flap 30 to be lifted for access into the enclosure 19 and then attached again to seal the opening 18. In such a construction there is no need for lines of perforations 45a.

Such a bag would be suited for use as a transit or courier bag.

An alternative embodiment 100 is illustrated in Figure 3.

Embodiment 100 is similar to the bag 10 illustrated and described with reference to Figures 1 and 2 with the closure flap 30 omitted.

Accordingly the various modifications relating to connection between the front and rear walls the different combination of materials etc apply to embodiment 100 also.

Closure of the opening 18 is achieved by a line of adhesive 80 located in between the overlapping portions 15a 16a.

The line of adhesive 80 is preferably covered by a removable cover strip (not shown) prior to closure and the cover strip is preferably formed from a material which does not weld with the material forming wall portions 15 and 16. Thus on forming the sides 21 the weld seams 24 does not secure the overlapping portion 15a to either the adhesive cover strip or portion 1 6a located therebeneath. Front wall portion 16 is however connected to the rear wall 14 by seams 24 and so still defines a capture flap.

Since closure flap 30 is not provided, it is possible for front wall portion 16 to be connected to the rear wall 14 by a fold line 120 rather than be a welded seam 25.

The line of adhesive 80 is a high tack adhesive which provides a permanent seal.

Claims (4)

1. A bag having front and rear walls formed of superimposed layers of plastics material joined to one another about the periphery of the rear wall to define an enclosure, the front wall having a terminal edge defining one side of an access opening into said enclosure and a strip of plastics material carrying a band of adhesive extending either side of said terminal edge for sealingly closing said opening, said strip of plastics material being adapted to give a visual indication of an attempted entry through said opening.

2. A bag according to claim I wherein said strip is formed so as to have less resistance to distortion than the front wall.

3. A bag according to claim 2 wherein said strip is formed from a thinner material than said front wall.

4. A bag according to claim 1, 2 or 3 wherein prior to sealing of said opening the band of adhesive is covered by a removable cover strip