Tamper or damage-indicating members

Abstract: The members, which are typically in the form of a bi-layer glove, comprise an inner layer (1,4) and an outer layer, (3,7) both being liquid- and air-impermeable. The outer layer (3,7) is sealed to the inner layer (1,4) so as to surround a zone of the inner layer (1,4) which is not sealed to the outer layer (3,7). The space (11) between the layers in the above-mentioned zone is free of air, and the outer layer (3,7) is translucent or transparent in the area overlying that zone and having a contrasting colour relative to the colour of the inner layer (1,4), so as to provide a visual indication (a change in the perceived colour) when the outer layer (3,7) is breached, as a result of tampering, accidental damage or the like.

Description: The present invention is concerned with tamper- or damage-indicating members. There are many types of product for which it is desirable to provide a visual indication that breach or damage has occurred, which may in some circumstances be indicative of accidental damage to the product, and in other circumstances indicative of tampering with the product. Examples of products where it is desired to provide a visual indication of accidental damage or tampering include containers (particularly containers which are intended to provide security for the contents), coin-meters, seals on lorries and other vehicles, and the like. For such products it is often desirable to provide a visual indication of when a seal has been broken. US 4516679 describes a tamper-proof wrap for a consumer product. The wrap comprises overlaid interior and exterior sheets of thin plastics material bonded together around an outer edge. A layer of a selected chemical is sealed between the sheets, such that, on puncture of a wrap exterior sheet, a chemical response produces a visual indication of wrap puncture. Protective gloves are a further example of products for which it is desired to provide a visual indication of accidental damage. Protective gloves are worn by surgeons in the course of surgical operations and are increasingly worn by other medical personnel (such as nurses, dentists and ambulance operatives), as well as other emergency workers, in view of concern over cross-infection in connection with diseases such as hepatitis B and acquired immune deficiency syndrome (AIDS). The basic rationale behind the use of protective gloves is that they should provide a complete barrier between the medical or emergency worker and the patient. Unfortunately, there is a risk of damage to the gloves by the use of sharp instruments such as scalpels, needles and the like; such damage is not always immediately detectable. US 3633216 describes a surgical glove in which at least one finger stall is of greater wall thickness than the remainder of the glove so as to obviate puncture of the finger stall and passage of contamination therethrough. The thickened portion may comprise two spaced apart layers, with a contrast colour indicator, preferably a coloured saline solution, between the layers. If the two-layer structure is breached, the colour indicator will leak through the resultant opening and cause a colour contrast in the layered structure around the breach. WO81/00344 describes a two-layer glove in which the inner layer is halogen-treated and the outer layer is halogen resistant; this enhances the flexibility of the glove. It is an object of the invention to provide tamper- or damage-indicating members in which damage (either accidental or as a result of unauthorised tampering) is readily detectable. The present invention provides a tamper- or damage-indicating member, which comprises an inner layer and an outer layer, at least a portion of the outer layer being sealed to the inner layer so as to surround a zone of the surface of the inner layer which is not sealed to the outer layer, thereby forming a space between the layers which is adjacent the abovementioned zone and is substantially free of air, both the layers being of substantially liquid- and air-impermeable material, the outer layer being of translucent material at least in the area thereof overlying the abovementioned zone and having a contrasting colour relative to the colour of the inner layer such that, when there is a breach in either layer adjacent the zone, there is a change in perceived colour in the area of breach. It is preferred that at least the portions of the outer layer and the inner layer adjacent the space should be of substantially uniform coloration throughout. The outer layer is typically of yellow and the inner layer is typically of a darker colour, such as green, black or the like. Because of the optical properties of the outer layer, the perceived colour when a complete vacuum remains in the abovementioned space (when the member is undamaged or not tampered with) is that of the inner layer; when the vacuum has been broken, however, the perceived colour is that of the outer layer. When the abovementioned space is free of air but not fully evacuated (for example, when the outer layer is secured to the inner layer only by the resilience of the outer layer, as will be described in more detail below), the optical effect is reversed. That is, the perceived colour when the member is undamaged, or not tampered with, is that of the outer layer, but when damage has taken place, and in the presence of an aqueous liquid, a capillary action takes place between the two layers such that the perceived colour is that of the inner layer). In some embodiments of the invention, the outer layer is conveniently thinner than, or of substantially the same thickness as, the inner layer; the contacting surfaces of the inner and outer layers may both be smooth or, in some embodiments (such as when the outer layer and the inner layer are both flexible), the outer surface of the inner layer, or the inner surface of the outer layer, may have a fine textured finish. In other embodiments (such as when the outer layer and the inner layer are both rigid), it is preferred that both the outer surface of the inner layer and the inner surface of the outer layer should be smooth. It is sometimes desirable to provide a release layer between the outer surface of the inner layer and the inner surface of the outer layer, in order to minimise the chances of the two layers sticking to one another. In one embodiment of the invention, the tamper- or damage-indicating member is a glove, comprising an inner glove-shaped body and an outer glove-shaped body surrounding the inner body, the inner and outer bodies each being of flexible, liquid- and air-impermeable material, and being sealed together at or near the wrist-engaging edges thereof, a substantial proportion of the outer surface of the inner body being in contact with the inner surface of the outer body but unbonded thereto. In this embodiment of the invention, the outer glove-shaped body is preferably wholly of translucent material. The inner glove-shaped body may be strongly coloured, for example, of black, luminous yellow or green. In the case where the member according to the invention is a glove, in addition to a visible change being detected when the outer layer is damaged, there is sometimes in addition a tactile change, detected by the wearer as the outer layer slides relative to the inner layer. In an embodiment of the invention in which the tamper- or damage-indicating member is a glove, the inner and outer layers are not sealed to one another but only secured to one another by the resilience of the outer layer. In this embodiment of the invention, when the outer layer is breached as a result of tampering or accidental damage, and in the presence of an aqueous liquid, the perceived colour is that of the inner layer, as a result of capillary action of the aqueous liquid. According to this embodiment of the invention therefore, there is provided a glove-shaped member, which comprises an inner glove-shaped body and an outer glove-shaped body surrounding the inner body, the outer glove-shaped body being secured to the inner body by the inherent resilience of the outer body when the glove-shaped member is worn, the inner and outer bodies each being of flexible, substantially liquid- and air-impermeable material, the outer body being of translucent material and having a contrasting colour relative to the colour of the inner body, such that when the outer body is breached, and in the presence of an aqueous liquid, there is a change in perceived colour in the area of breach as a result of capillary action of the liquid between the bodies. In this embodiment of the invention, a glove may be formed by the following sequence: (a) dip-forming an elastomeric latex on a hand-shaped former so as to form a glove-shaped body; (b) surface halogenating (e.g. chlorinating) at least part of the dip-formed elastomeric material present on the former; (c) dip-forming an elastomeric latex onto the halogenated glove-shaped body to form a further glove-shaped body; and (d) removing the glove-shaped bodies jointly from the former, the latices being such that the resulting glove-shaped member has an outer layer of a translucent material which has a contrasting colour relative to the colour of the inner layer. This latter removal step generally involves eversion of the glove-shaped bodies, such that the first applied halogenated body becomes the outer body and the second applied body becomes the inner body when both have been stripped from the former. The halogenation is preferably controlled such that adhesion in the halogenated area is substantially avoided; in order to obtain a glove according to the above-mentioned embodiment of the invention in which the inner and outer layers are secured to one another by the resilience of the outer layer, the first green (uncured) body may be halogenated all over the surface thereof. When the two bodies are then removed jointly from the former, they have been found to separate (or delaminate) from one another. The space between the inner and outer bodies may, in some embodiments, include an acceptable dye, or an anti-bacterial or anti-viral material, such as the the material commercially available under the trade mark Nonoxynol 9. For some applications, more than two glove-shaped bodies may be provided, one inside the other; these bodies may be sealed together at or near the wrist-engaging edges thereof. Alternatively, the outer body of such a multi-layer construction may be secured by its inherent resilience, as described above with reference to a two-layer construction. Two embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, wherein Figure 1 is a scrap-section greatly at enlarged scale through part of a glove according to the invention. Figure 2 is a plan view of a portion of a security seal tape according to the invention. Figure 3 is a cross-sectional view along line A-A of Figure 2, with the tape in an undamaged state; and Figure 4 is a cross-sectional view corresponding to that of Figure 3 with the tape in a damaged state. In the embodiment of Figure 1, an inner glove 1 is made of a thin flexible, elastic material such as rubber, or a suitable plastics material, which may be highly coloured, such as black, luminous yellow, or green. The outer surface 2 of the inner glove 1 has, in the illustrated embodiment, a fine textured finish (alternatively, it may be smooth). An outer glove 3 is of the same shape and size as the inner glove 1 and is a close fit thereon. The outer glove 3 is translucent. At or near the edges of the gloves 1,3 which engage the wearer's wrist, the gloves 1,3 may be sealed together. The space between the gloves 1,3 is substantially evacuated of air, so that the adjacent surfaces of the gloves 1,3 are pressed firmly together and the inner and outer gloves 1,3 act as a single glove. However, if a small puncture or leak is made in either of the gloves 1,3 in the presence of aqueous liquids such as blood or body fluids, a colour change in the vicinity of the puncture becomes apparent, indicating the existence of the puncture or leak. At the same time, the outer glove 3 becomes relatively more mobile over the inner glove 1 in the vicinity of the puncture, causing a detectable change of feel of the glove. An appropriate anti-bacterial or anti-viral substance may be dispersed in the space between the gloves 1,3 to act against any viral material which penetrates into the space. For some applications, more than two gloves 1,3 may be provided, one inside the other, all sealed together at the wrist-engaging edges and having the spaces between the gloves evacuated of air. In the embodiment of Figures 2 and 3, the undamaged tape member comprising a bottom layer 4 made of deep coloured plastics is folded at its edges 5 and welded, or otherwise connected at 6, to the top layer 7 of semi-rigid light-coloured translucent plastics, preformed into a shallow trough. The top and bottom layers (7 and 4 respectively) are held together in the undamaged state by a vacuum, existing between the two layers, which are sealed on all four edges, as shown in Figure 2. The tape member is adhered to the required surface 8 using a layer of suitable adhesive 9, applied around a peripheral region 10 (see Figure 2) which is stronger than the tape itself. This is necessary in order to ensure that the tape cannot be removed from the surface without itself becoming damaged. In Figure 4 the semi-rigid, preformed top layer 7 has delaminated upon loss of vacuum due to damage of the tape, allowing air or liquid to ingress into the region 11. This effect causes the perceived colour of the tape member to change, in so doing giving a visual indication of damage. It is important to note that the adhesive line 9 is kept back from the folded edge 5 to allow movement of the top layer 7. Such a security seal may be useful on envelopes or other packages, for cargo vehicles such as lorries and for utility meters such as gas or electricity, providing visual assurance that contents have not been tampered with. While the present invention has been primarily described in terms of gloves and a security seal, it will be apparent that the tamper- or damage-indicating member according to the invention may be used for other purposes; for example, the member may be used as part of a tamper-proof seal for a screw cap (for bottles, jars or the like), such that a visual indication is readily given when the bottle or jar has been opened. Alternatively, the member may be used on the lid of a rip top can or similar container. In further embodiments, the member according to the invention may be used on consumer goods (e.g. electronic goods) to provide an indication that unauthorised repairs have been carried out.

Claims: A tamper- or damage-indicating member, which comprises an inner layer (1) and an outer layer (3), at least a portion of said outer layer (3) being sealed to said inner layer (1) so as to surround a zone (2) of the surface of the inner layer which is not sealed to the outer layer, thereby forming a space between said layers which is adjacent said zone and is substantially free of air, both said layers being of substantially liquid- and air-impermeable material, said outer layer (3) being of translucent material at least in the area thereof overlying said zone (2) and having a contrasting colour relative to the colour of said inner layer (1), such that when there is a breach in either layer adjacent said zone there is a change in perceived colour in the area of breach. A member as claimed in claim 1, wherein said area of said outer layer is substantially lighter in colour than said zone of said inner layer. A member as claimed in claim 1 or 2, wherein said outer layer is thinner than said inner layer. A member as claimed in any of claims 1 to 3, wherein a release layer is provided between the outer surface of the inner layer and the inner surface of the outer layer. A member as claimed in any of claims 1 to 4, which is in the form of a glove, wherein said inner layer comprises a flexible inner glove-shaped body and said outer layer comprises a flexible outer glove-shaped body surrounding the inner body, the inner and outer bodies being sealed together at or near the wrist-engaging edges thereof, a substantial proportion of the outer surface of the inner body being in contact with the inner surface of the outer body but substantially unbonded thereto and said space being substantially evacuated. A glove-shaped member, which comprises an inner glove-shaped body and an outer glove-shaped body surrounding the inner body, the outer glove-shaped body being secured to the inner body by the resilience of the outer body when the glove-shaped member is worn, the inner and outer bodies each being of flexible, substantially liquid- and air-impermeable material, the outer body being of translucent material and having a contrasting colour relative to the colour of said inner body, such that when said outer body is breached, and in the presence of an aqueous liquid, there is a change in perceived colour in the area of breach as a result of capillary action of said liquid between said bodies. A member as claimed in claim 5 or 6, wherein said outer body is substantially wholly of translucent material, the inner body being relatively more strongly coloured than said translucent material. A member according to any of claims 5 to 7, wherein said inner and outer bodies are each of elastomeric material. A method of producing a member according to claim 8, which comprises: (a) dip-forming an elastomeric latex on a hand-shaped former so as to form a glove-shaped body; (b) surface halogenating at least part of the dip-formed elastomeric material present on said former; (c) dip-forming an elastomeric latex onto said halogenated glove-shaped body to form a further glove-shaped body; and (d) removing said glove-shaped bodies jointly from said former, said elastomeric latices being such that the resulting glove-shaped member has an outer layer of a translucent material which has a contrasting colour relative to the colour of the inner layer.

Inventors: RICHARDSON MARGARET PAMELA, RICHARDSON PHILIP, RICHARDSON, MARGARET PAMELA, RICHARDSON, PHILIP
Applicants: RICHARDSON MARGARET PAMELA, RICHARDSON PHILIP, RICHARDSON, MARGARET PAMELA, RICHARDSON, PHILIP
Application year: 1989
Main classification: G09F3
IPC codes: A41D19, B32B7, B65D55, G09F3, B29C41, A61B19, B29D99