Flexible bags – Tamper indicating
Reexamination Certificate
1999-02-08
2001-07-31
Pascua, Jes F. (Department: 3727)
Flexible bags
Tamper indicating
C383S084000
Reexamination Certificate
active
06267505
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to sealable security bags and in particular to providing secure evidence of thermal tampering with a seal.
Tamper-evident sealable security bags are used for storing and transporting valuable goods such as money. The valuables can be sealed into the bag. When the bag comes to be opened the tamper-evident features of the bag indicate to the recipient whether the sealing of the bag has been tampered with. If the tamper-evident features are intact then they give the recipient confidence that the bag's contents have not been interfered with. The recipient can then cut the bag open.
Security bags typically have an enclosed main body formed of sturdy plastics sheet—for example of polythene or polypropylene. The main body has an opening and a flap that can be folded over the opening on to the main body of the bag to close the opening, Either the flap or the area of the main body of the bag which will be in contact with the flap is coated with strong adhesive which, once stuck, provides a strong bond. The strong adhesive and the sturdy plastic sheet make it difficult, but not impossible, for the bag to be opened illegitimately. However, the bag is provided with tamper-evident security features that aim to provide evidence of an attempt to open the bag illegitimately.
One known way to open such a bag illegitimately is to heat the adhesive of the seal to a temperature at which it becomes plastic, but at which the plastics sheet material of which the body of the bag is made is still stable. This temperature is normally above at least 70° C., depending on the adhesive used. At those temperatures the adhesive becomes sufficiently plastic that the bag can be opened, the contents inspected or removed, and then the bag shut. Without any suitable tamper-evident features it would not then be obvious to the recipient that tampering of this sort had occurred. It would thus be impossible to know, for example, if confidential information in the bag had been seen by a third party or to identify where in a supply chain removal of goods from the bag had occurred.
One tamper-evident feature that is known for providing evidence of such thermal tampering is a detailed pattern printed on the outer surface of the flap of the bag, for example by ink-jet printing. When the seal area is heated and the flap comprised from the body of the bag the resultant stretching of the flap becomes evident as a deformation in the detailed pattern. However, it has been argued that because there may potentially be little stretching (since the material of the bag may remain stable at the temperature at which the adhesive softens) R can be difficult for inexperienced users to notice deformation of the pattern.
Another tamper-evident feature that is known for providing evidence of such thermal tampering is a coating on the outer surface of the flap of a heat-sensitive water-based ink. When the seal area is heated the heat-sensitive ink irreversibly changes colour, clearly indicating that the bag has been tampered with. However, because the ink is water-based it can be wiped off the flap to give the appearance that no tampering has occurred.
It would be desirable to provide a seal suitable, for example, for a security bag which addresses the problem of providing obvious and secure evidence of tampering by heating.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a tamper-evident seal comprising: a first seal member having an adhesive surface region; a second seal member having a sealing surface region located for adhesion to the adhesive surface region, at least one of the adhesive surface region and the sealing surface region being at least partially coated with a heat-sensitive layer so that when the adhesive surface region is adhered to the sealing surface region the heat-sensitive layer is sealed between the first seal member and the second seal member for providing evidence of thermal tampering.
Preferably the adhesive surface region and/or the sealing surface region is light transmissive, most preferably to allow the said evidence of thermal tampering to be observed therethrough.
The said at least one of the adhesive surface region and the sealing surface region that is at least partially coated with the heat-sensitive layer may be at least partially coated with an absorbent layer such as a matt ink beneath the heat-sensitive layer. Preferably the absorbent layer is the same colour as the at least one of the adhesive surface region and the sealing surface region on which it is at least partially coated.
The heat-sensitive layer may be in the form of a pattern or symbols. The heat-sensitive layer is suitably the same colour as the at least one of the adhesive surface region and the sealing surface region on which it is at least partially coated, and/or the same colour as any underlying absorbent layer. The said evidence of thermal tampering is suitably provided by a change in the heat-sensitive layer, such as a change in colour of that layer. The change suitably occurs at a lower temperature than the temperature at which the adhesive or the seal members thermally deteriorate under heating. The change suitably occurs in the range from 50 to 100° C., most preferably in the range from 70 to 95° C.
The adhesive surface region may be provided by one or more hot melt glues.
Preferably at least one of the adhesive surface region and the sealing surface region is at least partially coated with a cold-sensitive layer so that when the adhesive surface region is adhered to the sealing surface region the cold-sensitive layer is sealed between the first seal member and the second seal member for providing evidence of thermal tampering. The cold-sensitive layer may be a release layer. The cold-sensitive layer is preferably coated on the one of the adhesive surface region and the sealing surface region that is not coated with the heat-sensitive layer.
The seal may be incorporated into a bag, preferably a security bag. The seal is preferably arranged at the opening of the bag to allow the opening to be sealed shut. The opening may be closeable by a flap, suitably a flexible flap. The flap may be welded to the body of the bag. Thus, one of the first or second members may be a flap disposed at the opening of the bag.
At least one of the members suitably comprises or is made of plastics material.
According to the second aspect of the present invention there is provided a bag comprising: a first sheet member and a second sheet member together defining a bag opening therebetween; a flap bonded to the first sheet member at the opening; a flap engagement member bonded to the second sheet member at the opening; and a security seal comprising a tamper-evident structure borne by the flap or the engagement member and an adhesive structure borne by the other of the flap and the engagement member for adhering the flap to the engagement member to close the opening.
The flap engagement member is suitably formed of a flexible sheet The flap engagement member is suitably of an elongate form, most preferably disposed along one jaw of the opening. The flap engagement member may be in the form of a flap. The flap and the flap engagement member are preferably located and/or configured so that they may be mutually engaged to close the opening, suitably with the adhesive structure adhered directly to the tamper-evident structure. The adhesive structure and/or the tamper-evident structure may take the form of coatings comprising one or more layers.
The flap is suitably welded to the first sheet member. The flap engagement member is suitably welded to the second sheet member. The one of the flap and the engagement member that bears the tamper-evident structure may be of a different material from the one of the first and second members to which it is bonded.
The first sheet member may be bonded to the second sheet member to define the bag opening.
The tamper-evident structure is suitably a temperature-sensitive structure for example a heat- and/or cold-sensiti
Learoyd Packaging Ltd.
Pascua Jes F.
Perman & Green LLP
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