SECURITY ENVELOPE

Abstract: A tamper-proof security container suitable for the transmission of documents, money and other valuables comprises a bag having a front wall and a rear wall joined together at the bottom and side edges, the rear wall extending beyond the free edge of the front wall to provide a projecting flap (1) which can be folded over the open mouth of the bag to form a closure. The bag has a membrane (2) of material which is attached along one edge to the inner surface of the projecting flap so that the free portion (3) of the membrane extends into the open mouth of the bag. The projecting flap is coated with a security adhesive so that it can be folded down to adhere onto the exposed surface of the membrane, and also onto the outer face (4) of the front wall of the bag.

Description: This invention relates to tamper proof containers and particularly to envelope-like bags used for the transmission of documents, money and other valuables. Such containers are required to hold the contents securely, and preferably, to render obvious any attempt at unauthorised access to the contents. Bags of this type for use in carrying cash may be formed from an elongate sheet of material, which is folded over along a line offset from the centre, so as to form a U-shape in cross-section with one arm of the U longer than the other, the overlapping side edges then being welded together so that the long arm of the U provides a projecting flap which can be folded over the open mouth of the bag, to form a closure. A bag of this type is referred to herein below as a "bag of the type herein described". A number of variations on this type of construction have been proposed. One popular form of bag of this type incorporates a separate sheet forming an additional "pocket" at the mouth of the bag, which can be turned inside out to form a closure. A bag of this kind comprising the features of the entering clause of claim 1 is shown in British Patent No. 1546419, and although this construction provides extra security by making it more difficult for the contents to fall out of the bag, it does not provide protection against unauthorised access. It has also been proposed to provide adhesive closures for security bags, but it is not necessarily possible to determine whether an unauthorised attempt has been made to open such a bag, for example, by peeling away the adhesive closure. Accordingly, the present invention seeks to provide a security bag with improved protection against unauthorised tampering. According to the present invention, there is provided a bag of the type according to the entering clause of claim 1 the flap being according to the characterising portion of claim 1 coated with a security adhesive so that it can be folded down to adhere onto the exposed surface of the membrane, and also onto the outer face of the bag. The security container of the invention may be made from flexible plastic, such as polyethylene film, paper, foil or laminate of such materials which can be formed into bags, pouches, sachets, sacks or the like. Preferably, the flap is also transversely perforated in the adhesive area, so that any attempt at peeling open the closure will cause severance of the perforations. As an additional security feature, a transverse stripe of solvent sensitive ink may be applied to the front face of the bag, so that any application of solvent to the closure adhesive will be rendered obvious. One embodiment 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 the bag of the invention in an open condition; Figure 2 is a cross-section through the bag of Figure 1; Figure 3 is a cross-section corresponding to that of Figure 2, with the bag in a partially closed state; and Figure 4 is a cross-section corresponding to that of Figure 2, with the bag in a complete closed state. Referring to Figures 1 and 2, the bag is made from an elongate sheet of plastics film material which is folded over at 6, to form a front wall 8 and a rear wall 10, the rear wall extending beyond the free edge of the front wall so as to form a closure flap 1. The side edges 12 of the bag are heat sealed to form an open bag-like structure having a mouth 14 for the insertion of the contents. The inner surface of the flap 1 is coated with a security adhesive, and also carries parallel lines of perforations 5 so that the flap will be permanently damaged if any attempt is made to peel the adhesive once the bag has been closed. Below this upper region, a membrane 2, also of plastics film material, is heat welded to the flap 1 by its upper edge 16, so as to form a captive flap which extends into the mouth 14 of the bag, so that the upper portion is visible as indicated at 2 in Figure 1, whilst the lower portion 3 is concealed below the upper edge of the outer face 8 of the bag. After the contents have been inserted in the bag, the flap 1 is folded over as shown in Figure 3, and when pressure is subsequently applied to the outer surface of flap 1, it adheres to the upper portion of captive flap 2, as well as to the outer surface 4 of the front wall 8 of the bag, as shown in Figure 4, in an area which is coated with a stripe of solvent sensitive ink. Thus a subsequent attempt at removing the adhesive by means of a solvent will be obvious from the effect on the solvent sensitive ink. Since the adhesive on the flap 1 attaches to the surface of the captive flap 2, it is also more difficult to remove the contents by shaking them to the top of the container in order to obtain access through the side edges, since the contents will then be retained behind the captive flap. In order to ensure that the adhesive will become firmly attached to the captive flap, the latter is treated by a known corona discharge process, which improves the affinity of the surface for the adhesive.

Claims: A tamper-proof security container comprising a bag having a front wall (8) and a rear wall (10) joined together at the bottom (6) and side edges, the rear wall extending beyond the free edge of the front wall to provide a projecting flap (1) which can be folded over the open mouth of the bag to form a closure, the bag having a membrane of material (2) having one edge (16) attached to the inner surface of the flap (1), so that the free portion (3) of the membrane extends into the open mouth of the bag, characterised in that the projecting flap (1) is coated with a security adhesive so that it can be folded down to adhere onto the exposed surface (2) of the membrane, and also onto the outer face (4) of the front wall (8) of the bag. A security container according to claim 1, wherein the bag is formed from an elongate sheet of material which is folded over along a line offset from the centre, so as to form a U-shape in cross-section. A security container according to claim 1 or claim 2, wherein the projecting flap is also transversely perforated in the adhesive coated area. A security container according to any one of claims 1 to 3, wherein a transverse stripe of solvent sensitive ink (4) is applied to the outer face of the front wall of the bag. A security container according to any one of claims 1 to 4, wherein the bag is made from flexible plastic, paper, foil or laminates of such materials. A security container according to claim 5, wherein the flexible plastic is polyethylene film.

Inventors: BALDWIN,PAUL RICHARD, HODGES,WILLIAM, BALDWIN,PAUL RICHARD, C/O INTERPOLY LIMITED, HODGES,WILLIAM, C/O INTERPOLY LIMITED
Applicants: NMC SECURITY PRODUCTS LIMITED
Application year: 1989
Main classification: B65D27
IPC codes: B65D33, B65D27