TAMPER EVIDENT SECURITY DOCUMENT WITH COLOURED LAYER

This invention relates to security documents. In particular, the invention relates to tamper evident security documents:

Security documents often include an authenticity or verification device to guard against the copying or fraudulent alteration of the document. The device may be fixed to the document by printing the device onto the document.

One such problem with printing the device on to the security document is that the adhesion between the device and the document is such that the printed device may be removed or altered without damaging the document.

It would be desirable to provide a security document including a security device which is tamper evident.

In a first aspect of the present invention there is provided a security document including: a substrate; a security layer provided on at least one side of the substrate; and one or more opacifying layers concealing the security layer; wherein at least one opacifying layer includes a security device such that removal of the security device causes removal of the opacifying layer to reveal the security layer.

The security document may comprise, for example, any one of the following: identity documents such as passports, visas, identity cards, drivers licences, academic transcripts, birth certificates, land titles and security entrance cards; value documents such as bank notes, shares, bonds, certificates, cheques, lottery tickets, bank cards, charge cards and credit cards; and documents such as aeroplane tickets, bus tickets, rail road tickets and entrance tickets to fun parks and specific rides.

The security device is preferably personalised variable data which may be applied to the document at the time of personalisation or issuance of the document.

The security layer is preferably a coloured layer which is revealed when the at least one opacifying layer including the security device is removed. In one preferred embodiment, the security layer includes a brightly coloured pigment.

For example it may include titanium oxide and a coloured pigment such as orange, yellow or other bright colour.

Preferably, the substrate comprises a core film which is at least partially transparent or translucent. The at least one opacifying layer including the security device may be provided on the same side of the substrate as the security layer, but is preferably provided on the opposite side of the core film from the security layer.

At least two layers of opacifying coating may be provided. A first opacifying layer including the security device may be provided on one side of the core film while a second opacifying layer may be provided on the opposite side of the substrate over the security layer so as to sandwich the security layer between the second opacifying layer and the core film. The opacifying layers may be printed coatings. Suitably, the opacifying layers may be applied using one or more of the following printing processes: gravure, silk screen, offset and flexo.

The or each opacifying layer is preferably a colour which contrasts with the colour of the security layer, for example, white. Such an opacifying layer may include titanium oxide without any other pigments. The security device is preferably embedded within at least one opacifying layer. In a particularly preferred embodiment, the opacifying layer including the security device may include compounds which improve toner and/or inkjet adhesion which allows the security device to be embedded in the opacifying layer by inkjet printing, or laser printing, or electrophotographic printing.

The improved toner adhesion may be achieved by the inclusion of a resin based coating having high concentrations of silica components in the opacifying coating. The resin based coating bonds or fuses with the printed security device to embed the security device in the opacifying coating.

It will also be appreciated that the layers of the opacifying coatings may be formed from different compositions. For example, the first opacifying layer which is in contact with the core film and has a security device embedded therein may be formed from the resin based coating. The second opacifying layer may be formed from another less expensive composition, thereby reducing the cost of manufacturing the security document.

As the security device is embedded in the first opacifying layer removal of the security device causes removal of the first opacifying layer to render the security layer visible through the transparent or translucent core film.

This advantageously creates a tamper evident security document as once the security device and opacifying layer have been removed, it is necessary to reapply an opacifying layer to conceal the security layer, and it can be difficult to match the colour of the opacifying layer.

The core film may be formed from a polymeric material such as polyester, polyethylene terepthalate (PET), polycarbonate, polypropylene or polyvinyl chloride (PVC). It may be formed from a single layer or from a laminate of two or more layers.

The security device may be an optically variable security device. In a preferred embodiment of the invention, the security device is printed onto the opacifying layer.

In another aspect of the present invention there is provided a method of manufacturing a tamper evident security document, the method including the steps of: applying a security layer to a substrate; concealing the security layer with at least one opacifying layer; and embedding a security device in the opacifying layer such that removal of the security device causes removal of the opacifying layer to render the security layer visible.

Preferably, the substrate is a transparent or translucent core film and the step of concealing the security layer with an opacifying coating includes applying a first opacifying layer to the core film, and applying a second opacifying layer to the security layer so as to sandwich the core film and security layer between the first and second opacifying layers.

The opacifying layer with the embedded security device may be applied over the security layer on the same side of the substrate as the security layer, but is preferably provided on the opposite side of the substrate from the security layer. This provides additional protection for the security layer.

The opacifying layers may be applied to the core film and security layer by printing. Suitable printing methods may include any or more of the following

printing processes: gravure, silk screen, offset and flexo. The security layer is preferably a coloured layer and may also be applied by printing.

In a particularly preferred embodiment, the step of applying the first opacifying layer to the core film includes printing a resin based coating having high concentrations of specific silica components in the opacifying coating. Further, the step of embedding a security, device in the opacifying coating such that removal of the security device renders the security layer visible may be performed by printing the security device onto the opacifying layer such that the security device bonds or fuses with the opacifying coating.

In a preferred embodiment the core film is either at least partially transparent or translucent and one of the opacifying layers is in contact with the core film on the opposite side from which the security layer is provided. The security layer may include titanium oxide and a colour pigment such as orange, yellow or other bright colour. In a particularly preferred embodiment, the colour pigment of the opacifying layer contrasts with the colour of the pigment of the security layer.

Advantageously the method provides an improved tamper evident security document because once the security device and opacifying layer has been removed, it is necessary to re-apply an opacifying layer to conceal the security layer, and it can be difficult to match the colour of the opacifying layer. Further, because one or more of the security layer, the opacifying layers and the embedded security device may be applied by printing, the tamper evident document is relatively inexpensive to manufacture.

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic sectional view of a known security document taken on the line l-l of Figure 2;

Figure 2 is a schematic plan view of the known security document showing a security device;

Figure 3 is a schematic plan view of an attempt to tamper with the security device of Figure 2;

Figure 4 is a schematic sectional view of a first embodiment of security document in accordance with the invention taken at line A-A of Figure 5;

Figure 5 is a schematic plan view of the first embodiment in accordance with the invention;

Figure 6 is a schematic plan view of an attempt to tamper with the first embodiment of a security device made in accordance with the invention;

Figure 7 is a schematic sectional view of a second embodiment of a security document in accordance with the invention; and

Figure 8 is schematic sectional view of a simplified embodiment of a security document in accordance with the invention.

Referring now to Figure 1 , there is shown a schematic sectional view of a known security document. The security document 10 includes a core film 11 sandwiched between first and second opacifying layers 12, 13. The security document 10 further includes a security device 14 applied to the first opacifying layer 12. The security device 14 is applied to the security document 10 to prevent unauthorised coping or fraudulent alteration.

Figure 2 shows a schematic plan view of the security document 10 showing the first opacifying layer 12 with the security device 14 attached in the opacifying layer 12.

However, the security document shown in Figure 2 is subject to tampering. The security device 14 may be removed without affecting the first opacifying layer 12 or any other part of the document 10. This is shown in Figure 3 in which part of the device 14 has been removed without any evidence shown on the first opacifying layer 12.

A preferred embodiment of the invention is shown in Figure 4 which is a schematic view of a security document 20. The security document 20 comprises a core film 21 in contact with a security layer 22. The core film 21 and security layer 22 are sandwiched by opacifying coatings formed from opacifying layers 23 and 24. The security document further comprises a security device 25 embedded within the opacifying layer 23.

The core film 21 is formed from polymeric material, for example polyester, polyethylene terepthalate (PET), polycarbonate, polypropylene or polyvinyl chloride (PVC) and is preferably at least substantially transparent. It will also be appreciated that the core film may be formed from a translucent material. The

security layer may include titanium oxide and a colour pigment such as orange, yellow, or other bright colour.

The opacifying layers 23, 24 may also be formed from titanium oxide and are preferably white in colour so as to contrast with the security layer. At least the opacifying layer 23 provides improved toner adhesion by including a resin based coating having high concentrations of silica components bond or which fuse the security device 25 to the opacifying layer 23 when the security device is applied by digital printing, such as inkjet printing, laser printing or electrophotographic printing.

Figure 5 shows a top view of the security document of the present invention in which the security layer is covered by the opacifying coating 23. The security device 25 embedded in the opacifying layer 23 can also be seen. Figure 6 shows the security document 20 of the present invention having been tampered with. In this case, the security device 25 has been partially removed. However, given the improved toner adhesion of the opacifying layer 23, part of the opacifying layer has also been removed. Removal of the opacifying layer 23 renders the coloured security layer 22 visible through the transparent core film 21. The exposure of the security layer 22 indicates that tampering of the security document 20 has taken place.

A further advantage of the present invention is that once the document has been tampered with, it is difficult to match a replacement coating with the colour of the opacifying layer 23 such that the security layer 22 is once again concealed.

Figure 7 shows a modified security document 30 comprising a substrate 32, security layer 31 , and an opacifying coating 33 with an embedded security device 34. The substrate 32 may be transparent, translucent or opaque, because the opacifying coating 33 containing the embedded security device 34 is provided on the same side of the substrate 32 as the security layer 31. The substrate may be formed from a polymeric material or a paper or fibrous material. The security layer 31 is concealed by the opacifying coating 33. The security layer 31 and the opacifying layer 33 may be formed from similar materials to those described reference to Figures 4 to 6. The security device 34 is embedded in the opacifying coating 33 such that removal of the security device 34 causes removal of the opacifying layer 33 to reveal the security layer 31.

Figure 8 shows an alternative embodiment of the present invention in which a security document 40 comprises a coloured security layer 41 in contact with a first side of a transparent or translucent core film 42. An opacifying layer 43 is applied to the second side of the core film 44. The opacifying layer 43 includes a security device 45 embedded in the opacifying layer 43. The core film

42 is preferably formed from a transparent polymeric material, for example, polyester, polyethylene terepthalate (PET), polycarbonate, polypropylene or polyvinyl chloride (PVC). The security layer 41 and the opacifying layer 43 may be formed from similar materials to those described with reference to Figures 4 to 6.

When the embedded security device 44 is removed, the opacifying layer

43 is also removed to reveal the coloured security layer 41 on the opposite side of the transparent or translucent core film.

It will be appreciated that various modifications may be made to the preferred embodiments described above without departing from the scope and spirit of the invention.