Laminated credential

Technical Field

0001The present invention relates to a laminated credential.

Background

0002Laminated credentials are known to be used as identity cards and other documents, such as data pages of passports. Such laminates include a number of layers which are laminated together, and which include a security feature, such as a hologram, to provide a visual indication of the authenticity of the credential and protection of personal data entered on the credential. Laminated credentials made of durable plastics such as polycarbonate have been accepted as standard for high-durability identity documents with a typical lifespan of ten years. However, such known solutions can be costly, prone to tampering, and/or can produce unsatisfactory finishes.

0003We have devised an improved credential laminate.

Summary

0004According to the first aspect of the invention there is provided a holographic insert according to claim 1.

0005According to a second aspect of the invention there is provided a method of producing a laminated credential according to claim 14.

0006According to a third aspect of the invention there is provided a laminated credential according to claim 20.

0007The invention may comprise one or more features as described in the detailed description and/or as shown in the drawings.

Brief Description of the drawings

0008Various aspects of the invention will now be described, by way of example only, with reference to the following drawings in which: <ul id="ul0001" list-style="none"><li><figref idref="f0001"><b>Figure 1</b></figref> is a cross-section of a laminated credential,</li><li><figref idref="f0001"><b>Figure 2</b></figref> is a plan view of the laminated credential of <figref idref="f0001">Figure 1</figref>, where the holographic insert is a stripe.</li><li><figref idref="f0001"><b>Figure 3</b></figref> is a plan view of the laminated credential of <figref idref="f0001">Figure 1</figref>, where the holographic insert is a patch,</li><li><figref idref="f0002"><b>Figure 4</b></figref> is a cross-section of the laminated credential of <figref idref="f0001">Figure 1</figref> during a manufacturing step, and</li><li><figref idref="f0002"><b>Figure 5</b></figref> is a plan view of a holographic insert in stripe and patch form.</li></ul>

Detailed Description

0009There will now be described a laminated credential, and a method of producing the same. <figref idref="f0001">Figure 1</figref> shows an example of such a credential 1, which may be an identity card, or a data page for a passport. The credential comprises a plurality of transparent or opaque layers or substrates which are laminated together. As will be described in more detail below, the credential includes a holographic insert 10 which provides a visible authenticating security feature. Advantageously, the insert is completely assimilated within the card. In the example described, the credential includes an opaque part and a (transparent) windowed part, as indicated by 1a and 1b respectively.

0010An exemplary method of producing the holographic insert is first described. The insert comprises a partially holographic 'stripe' (in the form of a strip) or patch deployed between the transparent or partially transparent top layer 4 and the second layer 5 of a polycarbonate document, or between any further transparent or partially transparent layers 6 to 9, of the credential. The layers/substrates 4 and 5 are made of polycarbonate material meaning that they substantially comprise polycarbonate. The insert is manufactured by embossing a holographic feature on a polycarbonate film. The holographic feature (shown schematically by reference numeral 11 in <figref idref="f0001">Figures 2 and 3</figref>) includes areas of embossed or UV cast holographic micro-structure. The polycarbonate film is also provided with a patterned reflective coating, metallic or otherwise (eg largely transparent high refractive index ZnS or TiO2 reflective coating), largely overlapping with the areas of the holographic micro-structure. Such coating may be provided by all-over metallisation and subsequent patterned demetallisation by chemical, laser or other methods, or by selective metallisation.

0011The insert 10 may also be provided with a heat or pressure-sensitive adhesive on one or both sides of the film. With reference to <figref idref="f0002">Figure 5</figref>, the adhesive 12 is (schematically) shown in a criss-cross pattern. In this example, the adhesive is provided on the same side, surface 10a, of the film on which the holographic feature is provided (although the holographic representation of the holographic feature is omitted for clarity). The holographic feature may also be provided on the opposite surface of the film from the adhesive. As can be seen, the majority of the surface area of the side on which the adhesive is provided is free of adhesive in order to enable direct bonding by thermo-compression between the polycarbonate material of the insert and the adjacent polycarbonate layers of the credential on both sides of the insert. The application of the adhesive may be by way of by methods such as gravure or flexo coating/printing. Although a continuous pattern of adhesive is shown, in other embodiments, a pattern or field of discrete/discontinuous adhesive regions may be provided, and indeed a discrete adhesive may be combined with discontinuous arrangement. The thickness of the insert may be the in the range of 30 micrometres to 50 micrometres, prior to incorporation with the credential structure, and is generally of smaller thickness than at least one of the polycarbonate substrates between which it is located.

0012The insert may conveniently be provided in wound form on a reel. To create a stripe in the credential, reel-wound tape may be provided on a release liner and slit to the required width. A suitable length of the tape can then be used.

0013To create a patch in the credential, the insert material can be provided on a release liner, die cut to size, and feature registration marks for further application to the polycarbonate substrate in register. An alternative way to create a patch in the credential comprises providing the insert material without the release liner as self-wound polycarbonate tape with partially punched-out patches where thin connecting bridges are used to keep the patches in the tape prior to hot-stamping and then break during hot-stamping, ensuring their separation from the tape and transfer to the polycarbonate substrate.

0014A heat-sensitive/activated adhesive pattern serves as a means of preliminary attachment of the tape/patch to the polycarbonate substrate layer during hot-stamping and/or temporary attachment of the tape/patch to the release liner where used. Alternatively, a patterned pressure-sensitive/activated adhesive may be used for the same purpose (in which case the feature may be applied to the polycarbonate substrate by a label applicator rather than a hot-stamping machine).

0015The adhesive may comprise one of the following types: <ul id="ul0002" list-style="none" compact="compact"><li>A pure acrylic emulsion copolymer having a TG below 25 °C and Refractive index below 1.5.</li></ul>

0016An adhesive which comprises styrene -acrylic emulsion co-polymer containing at least 25% styrene monomer An adhesive which comprises a polycarbodiimide crosslinker An adhesive which comprises a polyaziridine crosslinker An adhesive which comprises unsaturated oligomers and an initiator that generates free radicals when exposed to UV light.

0017An adhesive which comprises liquid polycarbonate.

0018In other embodiments there may be a case when no adhesive is required, when the insert is presented in a self-wound reel of tape or partially punched out patches without a release liner and applied to the polycarbonate substrate with thermal roll-on or hot-stamping machinery using the effect of direct thermo-compression bonding of the insert to the substrate under heat and pressure. Alternatively, ultrasonic welding can be used to ensure the preliminary attachment of the insert to the substrate. Alternatively, the patterned adhesive may be provided on the polycarbonate substrate itself, rather than the insert.

0019The incorporation of the insert into the credential includes two stages. As shown in <figref idref="f0002">Figure 4</figref>, the first is application of the insert to a polycarbonate substrate 4 by heat and pressure (in case of heat-sensitive adhesive) or pressure (in case of pressure-sensitive adhesive). The second is lamination in a lamination machine to bond together the various layers 4 to 9 of the credential by thermo-compression.

0020During the first stage, the adhesive 12 ensures preliminary adhesion of the insert 10 to surface 4a of the polycarbonate substrate 4. The substrate 4 with the attached insert 10 will be used as a layer of the finished credential, advantageously the uppermost transparent layer or the second uppermost layer, transparent or opaque, or the next uppermost layer, transparent or opaque. Where the insert is applied in the form of the tape the adhesion may be achieved by thermal roll-on machinery, such as that used to apply magnetic stripes to bank cards. When the insert is in the form of patch (or label) this may be applied by a hot-stamping press, such as that used to apply holographic patches to paper or plastic documents. The polycarbonate substrate with the attached insert may then be finished to reels of suitable width and length for subsequent reel-based lamination or to sheets of suitable size for subsequent sheetform lamination into finished credentials.

0021During the second stage of the process, the permanent adhesion of the insert 10 to the polycarbonate layers lying directly above and below it is achieved by thermo-compression bonding during credential lamination. This process may be aided by the secondary activation of the patterned adhesive. Due to the holographic microstructure, the reflective coating and the adhesive all being patterned, on the holographic image side of the insert, and the adhesive (if present) on the other side of the insert, being patterned, areas of the feature free of those layers allow a free flow of polycarbonate material from the insert itself during thermo-compression and its molecular bonding to the adjacent layers of polycarbonate in the structure of the credential. During the lamination process, the uppermost (protective) layer 4, is positioned atop the layer 6 and the insert 10. The layers are then sandwiched between metal plates, which are subsequently subjected to a heat pressure cycle to create a thermo-compression and thereby form a laminate that will subsequently be punched out to a required credential size, for example an ID-1 size card or passport data page.

0022As can be seen in <figref idref="f0001">Figure 1</figref>, the insert 10 becomes incorporated and embedded into the layer 5 or both into the substrate 4 and the layer 5, as the case may be. The polycarbonate of the insert 10 becomes fused with the polycarbonate of the layers 4 and 5. Surprisingly, we have found that the uppermost/outermost surface of the credential does not present a raised region due to the underlying presence of the insert, but rather presents a substantially flat surface. Ordinarily it would be considered that the insert could cause some kind of perceptible presence in the outermost layer 4. However, we have found that the overlap region of the layer 4 with the insert is substantially continuous.

0023As is evident from the above, we have devised a secure, tamper-proof, durable and cost-effective holographic security feature for a polycarbonate document, which is very conveniently compatible with the feature application techniques widely deployed and used in the industry, in this case, hot-stamping or label application, with subsequent lamination, and therefore existing machinery can be used. More particularly, advantages include: <ol id="ol0001" ol-style=""><li>(1) simple application of the security feature to a polycarbonate substrate, using methods established in the industry: hot-stamping or pressure-based label application, which means that existing machinery standard for the identity industry can be used;</li><li>(2) superior tamper-resistance of the feature compared to traditional holographic features is ensured by molecular thermo-compression bonding of the free-flowing polycarbonate material of the feature itself to the adjacent layers of the credential;</li><li>(3) superior mechanical durability of the credential incorporating the insert (resistance to delamination, bending, torsional stress etc.) compared to one using traditional holographic features is ensured by molecular thermo-compression bonding of the free-flowing polycarbonate material of the feature itself to the adjacent layers of the credential;</li><li>(4) if the insert is in form of a stripe is used from edge to opposite edge of the credential, superior chemical durability of the edge areas of the credential compared to one using traditional holographic features is ensured by molecular thermo-compression bonding of the free-flowing polycarbonate material of the insert itself to the adjacent layers of the credential;</li><li>(5) superior visual appearance and surface quality of the credential incorporating the insert is ensured by the free-flow of the polycarbonate of the insert itself and its blending with the adjacent layers of the PC document, resulting in smooth appearance of the surface of the document, devoid of any noticeable visual or tactile borders, roughness or ridges. As can be seen in <figref idref="f0001">Figure 1</figref> the cross-sectional profile of the outermost layer 4 does not show any perceptible indication of the underlying presence of the insert since that surface of that layer is substantially flat;</li><li>(6) superior cost-efficiency of the insert compared to full-surface holographic polycarbonate credential features due to a smaller area of polycarbonate required to produce each insert.</li></ol>

0024In alternative embodiments, more than one insert may be incorporated, and these may be provided at different levels within the credential. Further, the insert may be provided with scalloped edges around some or all of its perimeter. Further, the insert may be positioned, wholly or partially, in a transparent window or transparent area of the credential, providing the visibility of the holographic image from either side of the document. Further, the insert may be positioned in the area where critical personal data of the credential, such as the bearer's photograph, will be applied during personalisation. In this case laser personalisation of such critical data, advantageously effected on the laser-sensitive polycarbonate layer lying below the feature, will be reliably secured from tamper by the feature. Yet further, the adhesive may comprise infrared or UV sensitive pigments, such as photoluminescent or photochromic pigments.