EP2560822B1 - Security element having a transparent image region - Google Patents

Description

The invention relates, according to claim 1, a security element for security papers, documents of value and other data carriers, which has an image area, which shows a predetermined multitonal motive. The invention further relates to a method according to claim 12, for the production of such a security element and a data carrier with such a security element.

Data carriers, such as security, value or identity documents, but also other valuables are often equipped with security features for security, which allow verification of the authenticity of the data carrier and at the same time serve as protection against unauthorized reproduction. In this case, security features whose authenticity is checked in a transparent manner, such as the long-known watermark of paper banknotes, allow a particularly simple authenticity check by the user.

The publication WO 2008/008635 describes a micro-optic imaging system having an array of focusing elements and an imaging system formed by an array of microscopic image-symbol elements. The icon elements may be formed as basal surfaces filled with a pigmented or colored material whose thickness variations produce a variation in the optical density of the icon element.

In the case of polymer banknotes, only transparent printed security elements that are not firmly anchored in the note have hitherto been known. However, such printed see-through security elements are relatively easy to forge and do not allow individualization of the substrate, since they are not or not sufficiently anchored in the substrate. Accordingly, those security features that are printed on a polymer banknote in a known manner can be easily removed and applied to another polymer banknote, leaving behind the polymer banknote originally provided with the security element as a non-individualized polymer film.

Proceeding from this, the present invention seeks to provide a security element of the type mentioned above, which shows a watermark-like see-through effect in thin polymer substrates and combines a high security against forgery with easy testability by the user. Another object is to provide a security element of the type mentioned, which allows a tamper-proof individualization of the data carrier.

• das Sicherheitselement einen Bildbereich aufweist, der in Durchsicht ein vorgegebenes Motiv mit einem wasserzeichenähnlichen Durchsichtseffekt zeigt,
• das Sicherheitselement ein dünnes Polymersubstrat einer Dicke von 300 µm oder weniger aufweist,
• das Polymersubstrat in dem Bildbereich ein mehrstufiges Relief mit Vertiefungen in Form des vorgegebenen multitonalen Motivs enthält, und
• die Vertiefungen des Reliefs mit einem Füllmaterial mit dickenabhängigen optischen Eigenschaften gefüllt sind.

According to the invention, it is provided in a generic security element that

• the security element has an image area which, when viewed, shows a given motif with a watermark-like see-through effect,
• the security element has a thin polymer substrate of a thickness of 300 μm or less,
• the polymer substrate in the image area contains a multi-level relief with depressions in the form of the predetermined multitonal motif, and
• the depressions of the relief are filled with a filling material with thickness-dependent optical properties.

The thickness-dependent optical properties of the filling material preferably consist of a thickness-dependent optical density of the material. The opacity of a material is generally given by the ratio of the illuminances before and after passing through the material (see "http://www.wikipedia.org/wiki/ Opacit% C3% A4t"). The decadic logarithm of opacity is also referred to as extinction or optical density (see also "http://en.wikipedia.org/wiki/Extinktion_(Optik)"). For example, an optical density of 1.0 corresponds to a weakening of the light to one-tenth of the original illuminance, an optical density of 2.0 to one-hundredth of a weakening. The optical density of a filler layer is substantially proportional to the layer thickness, a twice as thick layer area therefore has substantially twice the optical density and appears correspondingly darker when viewed.

It should be noted here that in addition to the currently claimed security element with an image area which shows a given multitonal motive when viewed, image areas which show a given monotonal motive when viewed are also included in the invention described in this application. Such a security element with monotonal motifs differs from the multitonal security element currently claimed only in that the polymer substrate in the image area has a one-step relief with recesses in the form of the predetermined monotone motif. That is, all pits have substantially the same relief depth, whereby the viewer of such a security element perceives a monotone motif in phantom. Such a security element is a particularly simple embodiment of the invention and can be produced with relatively little effort, but the protection against counterfeiting is not as good as in the currently claimed security elements with an image area, which shows a multitonal motive, as the latter security element due of the multi-level relief with depressions in the form of the given multitonal motif is much more difficult to falsify.

The filler material preferably has a color, in particular a color of high opacity, so that the image area shows an opacity-modulated, multitonal motif.

In any case, the opacity of the filling material must be chosen so that the viewer can easily recognize the multitonal motif according to the invention as a security feature of the data carrier. The person skilled in the art can determine the opacity of the filling material, depending on the parameters determining the opacity of the security element, in particular the average relief depth.

Suitable fillers are, in particular, solvent-based inks, IR, UV-curing inks or acrylics, optionally also mixtures of these inks.

To produce the thickness-dependent optical properties of the security element according to the invention, it is advantageous to use pigments, such as titanium dioxide (TiO ₂ ), polymeric fillers or dyes. In the context of the present invention, dyes in the filler material are soluble colorants, whereas pigments in the filler material are practically insoluble.

The thickness-dependent optical property of the security element by a filling material with thickness-dependent optical properties can basically be changed after introduction of the filling material. For this purpose, a filler material with activatable substances is introduced into the depression of the relief, wherein the substances are activated after filling of the filling material, for example by heat or exposure to electromagnetic radiation, in particular by means of laser radiation. The activation can, for example, take place in a region-wise increase of the opacity in the motif area. In this way, for example, a relatively simple design motif can be supplemented by a corresponding fine structure. It is also conceivable the introduction of additional information in the field of the subject, eg in the form of a denomination for the document of value in the form of a banknote or an individualizing information, in particular numbers and letters, in the case of a document of value in the form of a card.

In further advantageous embodiments, the filling material may have a luminescent color, an IR- or UV-absorbing color or a magnetic color. The filler material can also combine several of the mentioned properties. For example, for a watermark-like visual impression, the filler may have high opacity and at the same time be magnetic to permit machine reading of the motif image.

The depressions of the multistage relief expediently have a maximum relief depth of less than 100 μm, preferably a maximum relief depth of between 5 μm and 50 μm. It is understood that the maximum relief depth and the layer thickness of the polymer substrate are suitably matched to one another. In general, the maximum relief depth is between 1% and 99% of the layer thickness of the polymer substrate of the security element according to the invention. In advantageous embodiments, the maximum relief depth is for example about 50% or about 25% of the layer thickness of the polymer substrate.

In an advantageous embodiment, the polymer substrate is provided with a relief only on one of its major surfaces. In another embodiment, which is also advantageous, it is provided that the polymer substrate in the image area is provided with a multi-level relief on both its opposite major surfaces.

The wells filled with the filling material are advantageously covered with a cover layer, in particular with a paint finish, a lamination or a lamination with film or pulp. The cover layer may be formed by a single layer, or may consist of several partial layers.

To enhance the see-through effect, the cover layer may also be provided with recesses. In particular, the cover layer can be completely or partially recessed in the image area. Advantageously, the cover layer has a layer thickness between 6 μm and 50 μm, preferably between 6 μm and 20 μm.

In a preferred embodiment, the security element contains as polymer substrate a polymer film, in particular polyethylene, polypropylene, polyester or polyamide. The layer thickness of the polymer substrate is suitably between 25 .mu.m and 300 .mu.m, preferably between 60 .mu.m and 140 .mu.m.

In advantageous variants of the invention, the security element forms part of a polymer banknote, a composite banknote or a polymer layer of a value document, for example a data page of an identification document.

• ein dünnes Polymersubstrat einer Dicke von 300 µm oder weniger bereitgestellt wird,
• das Polymersubstrat in dem Bildbereich mit einem mehrstufigen Relief mit Vertiefungen in Form des vorgegebenen multitonalen Motivs versehen wird, und
• die Vertiefungen des Reliefs mit einem Füllmaterial mit dickenabhängigen optischen Eigenschaften gefüllt werden.

The invention also includes a method of producing a security element having an image area which shows in phantom a predetermined multitoneial motif having a watermark-like see-through effect, in which

• a thin polymer substrate of a thickness of 300 μm or less is provided,
• the polymer substrate in the image area is provided with a multi-level relief with recesses in the form of the predetermined multitonal motif, and
• the depressions of the relief are filled with a filler having thickness-dependent optical properties.

In a preferred variant of the method, the multistage relief is produced by cold embossing, thermal embossing or by laser abrasion in the polymer substrate. The relief is preferably already introduced during the production of the polymer substrate or shortly thereafter.

For example, the filling material can be applied over the entire surface to the security element and an excess of filling material present outside the relief can be removed, in particular scraped off. Also, direct introduction of the filler without subsequent doctoring is accomplished by the use of suitable printing techniques, e.g. in the "continuous inkjet process" (inkjet printing process) possible.

In advantageous variants of the method, the depressions filled with the filling material are covered with a cover layer in a further method step, in particular by means of lacquering, lamination or lamination with film or fibrous material.

Finally, the invention also includes a data carrier with a security element of the type described. The data carrier is advantageously a security paper or a value document, in particular a polymer banknote or a film composite banknote. The term composite film banknote includes in particular paper / film composite banknotes, Paper / foil / paper composite banknotes and foils / paper / foil composite banknotes. The data carrier can also be a card, in particular an identity card, credit card, bank card, cash card, authorization card, identity card or passport personalization page. Such a data carrier in the form of a card has the security element according to the invention with advantage as a layer of a multilayer card composite, wherein the polymer substrate layer according to the invention covered by the other layers of the card composite, which are particularly transparent or translucent in the area of the subject covered and thus before Tampering is protected.

Further embodiments and advantages of the invention are explained below with reference to the figures. For better clarity, a scale or proportion accurate representation is omitted in the figures.

Fig. 1

eine schematische Darstellung einer Polymerbanknote nach einem Ausführungsbeispiel der Erfindung,

Fig. 2

einen Querschnitt durch die Polymerbanknote der Fig. 1 entlang der Linie II-II,

Fig. 3

einen Querschnitt durch eine Polymerbanknote ohne Deckschicht nach einem anderen Ausführungsbeispiel der Erfindung,

Fig. 4

ein Ausführungsbeispiel, bei dem ein dünnes Polymersubstrat auf seinen beiden gegenüberliegenden Hauptflächen jeweils mit einem gefüllten Relief versehen ist,

Fig. 5

ein Ausführungsbeispiel, bei dem die Deckschicht zur Verstärkung des wasserzeichenähnlichen Durchsichtseffekts mit Aussparungen versehen ist, und

Fig. 6

eine Gestaltung, bei der das mehrstufiges Relief in einer dünnen, transparenten Prägelackschicht vorliegt.

Show it:

Fig. 1

a schematic representation of a polymer banknote according to an embodiment of the invention,

Fig. 2

a cross section through the polymer banknote the Fig. 1 along the line II-II,

Fig. 3

a cross section through a polymer banknote without cover layer according to another embodiment of the invention,

Fig. 4

an embodiment in which a thin polymer substrate is provided on its two opposite major surfaces each with a filled relief,

Fig. 5

an embodiment in which the cover layer is provided for enhancing the watermark-like see-through effect with recesses, and

Fig. 6

a design in which the multi-level relief is present in a thin, transparent embossing lacquer layer.

The invention will now be explained using the example of a polymer banknote. Fig. 1 1 shows a schematic representation of a polymer banknote 10 having a security element 12 according to the invention, which shows an opacity-modulated, multitonal image image 14 firmly anchored in the note. The picture motif may be, for example, a portrait or a similar representation.

In the exemplary embodiment, the image motif is formed by a multitonal portrait 14, which in Fig. 1 for illustration is shown schematically as a line drawing. Fig. 2 shows a cross section through the polymer banknote 10 in the region of the security element 12 along the line II-II of Fig. 1 ,

The polymer banknote 10 contains a thin substrate 20 made of a polymer film, for example polyethylene, polypropylene, polyester or polyamide. The thickness of the polymer substrate 20 is in the illustrated embodiment 100 microns, but may in principle be in the range between 25 microns and 300 microns and preferably in the range between 60 microns and 140 microns.

A multistage relief 22 with depressions in the form of the portrait 14 has already been introduced into the polymer substrate 20 during its production, for example by cold embossing, thermal embossing or laser abrasion. The depressions of the relief 22 have in the exemplary embodiment on a maximum relief depth of 50 microns and form with the large number of occurring relief depths a relief with a practically continuous depth profile. In other embodiments, however, a relief with a certain number of discrete relief depth, for example, 10 relief levels can be generated. Finally, in a further conceivable embodiment, a number of discrete relief depths are used which, on the one hand, have more than about 10 relief steps but, on the other hand, do not have so many discrete relief depths that one can speak of a continuous depth profile. In this further embodiment can be spoken of a quasi-continuous depth profile.

After the introduction of the relief 22, the depressions of the relief are filled with a high-opacity color 24. The color 24 may be any suitable filling material according to the invention, for example a cover white color. For this purpose, the ink 24 can be applied over the entire surface, for example, and a color excess present outside the depressions can be scraped off the surface of the substrate 20. Finally, the relief 22 filled with ink 24 is provided with a transparent cover layer 26, for example by printing or laminating a protective layer. This is how the in Fig. 2 The local opacity of the filled relief 22, 24 depends on the local layer thickness of the color 24 and thus on the local relief depth. Due to the high opacity of the color 24, the tonal range of the image motif can range from complete transparency (local relief depth zero) to almost complete opacity (at maximum embossing depth). rich. Nearly complete opacity means, depending on the opacity of the ink used and the maximum embossing depth, a light transmittance of 10% or less, 5% or less, 2% or less, or even 1% or less.

Since the opacity of the image motif 14 depends on the local layer thickness, an opacity-modulated representation of the image motif with a large number of different tonal values results in a transparent view. The different tonal values are formed by the locally different opacities, which convey a more or less bright image impression locally. The image motif 14 thus appears to the viewer with a watermark-like see-through effect.

Visible visual security features of this type are familiar to the user of watermarks in paper banknotes, and are therefore generally quickly recognized as security features and reliably checked. At the same time, the image motif 14 generated by the filled relief 22, 24 is firmly anchored in the polymer substrate 20 and inseparably connected thereto. The security element 12 therefore offers a much higher protection of the polymer banknote 10 than printed or other security features applied only to the substrate surface.

As the filling material for the relief, a luminescent ink, an IR- or UV-absorbing ink or a magnetic ink may also be used. Filler material with magnetic properties generates machine-readable image information due to the locally varying layer thickness. IR or UV-absorbing or luminescent motif images can also be read out by machine. In advantageous designs, the filler material can provide both high visibility for visual recognition and have magnetic properties for the automatic detection of the security element.

The cover layer 26 is preferably applied to the substrate 20 by means of lacquering, lamination or lamination with foil or fibrous material. In some designs can also be dispensed with a cover layer, as exemplified in Fig. 3 shown.

Regarding Fig. 4 For example, the polymer substrate 20 can also be provided with a relief 22, 32 on its two opposite major surfaces. The two reliefs 22, 32 may be formed with the same or different depth profile. Also, the two reliefs 22, 32 may be filled either with the same or with different filling material 24, 34. For example, the optical properties of two different fillers 24, 34 may complement each other only when viewed in the desired overall impression, or one filler 24 may be designed for visual recognition, the other filler 34 for machine detectability or optimized. In a variant of the invention not shown, the in Fig. 4 Reliefs 22, 32 shown in the surface direction of the substrate to be shifted against each other, so that the viewer perceives depending on the size of the displacement of the two reliefs 22, 32 in review an overall motif, which is composed of the reliefs 22 and 32 illustrated motifs. In this case, the observer perceives a high opacity, which is composed of the opacities of the reliefs 22 and 32, from certain viewing directions in the regions of the reliefs 22, 32 which overlap from these viewing directions.

The filled reliefs 22, 32 taken together show the desired image motif, such as the portrait 14 of FIG Fig. 1 , The opposite filled reliefs 22, 32 are preferably both covered with a cover layer 26, 36 and protected.

In all designs, the cover layer can also be provided with recesses 40 to enhance the watermark-like see-through effect. As in the embodiment of Fig. 5 illustrated, the recesses 40 of the cover layer 26 are arranged in particular in the region of the filled relief 22, 24 and can detect the relief region in whole or in part.

At the in Fig. 6 As shown, the polymer substrate is not single-layered but multi-layered. On a first layer 50, which is essentially in the FIGS. 1 to 5 corresponds to and shown in the associated description of the figure, a thin, transparent embossing lacquer layer 52 is applied, in which a multi-level relief 54 is imprinted in the form of the desired image motif. The depressions of the embossing lacquer layer 52 are filled with a filling material 56 of high opacity, so that here too an opacity-modulated, multitonal image motif is produced in a transparent view. The filled relief 54, 56 and / or the embossing lacquer layer may optionally be covered with a cover layer, not shown in the figure.

In the production of an in Fig. 6 Of course, it has to be ensured that the multilayered polymer substrate shown is substantially inseparably bonded to one another in order that the advantages of the invention, in particular the increased security against forgery, can be achieved. In any case, the layers must be joined together in such a way that, in the event of a manipulation attempt, for example by the action of certain solvents, the individual layers of the multilayered polymer substrate are not without at least partially Destruction can be separated from each other, so that a corresponding manipulation attempt would be immediately recognizable as such. Advantageously, the embossing lacquer layer 52 may be a thermally or UV-curing lacquer having a layer thickness of approximately 40 μm, the layer thickness range from 5 μm to 30 μm being particularly preferred.

LIST OF REFERENCE NUMBERS

10

Polymer banknote

12

security element

14

motif

20

polymer substrate

22

relief

24

colour

26

topcoat

32

relief

34

filling material

36

topcoat

40

recesses

50

layer

52

Embossing lacquer layer

54

relief

56

filling material

Claims (16)

1. A security element for security papers, value documents and other data carriers, having an image region that displays a specified multi-tonal motif (14) when looked through,
   characterized in that

   - the security element (12) exhibits a thin polymer substrate (20) of a thickness of 300 µm or less,

   - the polymer substrate (20) includes, in the image region, a multi-level relief (22) having depressions in the form of the specified multi-tonal motif (14), and

   - the depressions of the relief (22) are filled with a filler material (24) having thickness-dependent optical properties, such that,

   - when looked through, the multi-tonal motif appears for the viewer having a watermark-like see-through effect.
2. The security element according to claim 1, characterized in that the filler material exhibits an ink, especially a high-opacity ink, such that the image region displays an opacity-modulated, multi-tonal motif when looked through.
3. The security element according to claim 1 or 2, characterized in that the filler material exhibits a luminescent ink, an IR- or UV-absorbing ink, an acrylic ink or a magnetic ink.
4. The security element according to at least one of claims 1 to 3, characterized in that the depressions of the multi-level relief exhibit a maximum relief depth of less than 100 µm, preferably a maximum relief depth between 5 µm and 50 µm.
5. The security element according to at least one of claims 1 to 4, characterized in that the polymer substrate is provided with one multi-level relief each in the image region on both of its opposing main surfaces.
6. The security element according to at least one of claims 1 to 5, characterized in that the depressions filled with the filler material are covered with a cover layer, especially with a finish, a lamination or a plating with foil or fiber stock, wherein, preferably, the cover layer consists of multiple sub-layers.
7. The security element according to claim 6, characterized in that, to enhance the see-through effect, the cover layer is provided with gaps, especially in that the cover layer is fully or partially omitted in the image region.
8. The security element according to at least one of claims 6 to 7, characterized in that the cover layer exhibits a layer thickness between 6 and 50 µm, preferably between 6 µm and 20 µm.
9. The security element according to at least one of claims 1 to 9, characterized in that the security element includes, as the polymer substrate, a polymer foil, especially composed of polyethylene, polypropylene, polyester or polyamide.
10. The security element according to at least one of claims 1 to 9, characterized in that the substrate of the security element exhibits a layer thickness of 25 µm to 300 µm, preferably of 60 µm to 140 µm.
11. The security element according to at least one of claims 1 to 10, characterized in that the security element forms a portion of a polymer banknote, a composite banknote or a polymer ply of a value document.
12. A method for manufacturing a security element (12) having an image region that displays a specified multi-tonal motif (14) when looked through, characterized in that

    - a thin polymer substrate (20) of a thickness of 300 µm or less is provided,

    - the polymer substrate (20) is provided in the image region with a multi-level relief (22) having depressions in the form of the multi-tonal motif (14), and

    - the depressions of the relief (22) are filled with a filler material having thickness-dependent optical properties, so that

    - when looked through, the multi-tonal motif appears for the viewer having a watermark-like see-through effect.
13. The method according to claim 12, characterized in that the multi-level relief is produced in the polymer substrate by cold embossing, thermal embossing or by laser abrasion.
14. The method according to claim 12 or 13, characterized in that the filler material is applied contiguously to the security element and any excess of filler material present outside the relief is removed, especially is squeegeed off, and/or that the depressions filled with the filler material are covered with a cover layer, especially by finishing, a lamination or a plating with foil or fiber stock.
15. A data carrier (10), especially a security paper or value document, having a security element (12) according to one of claims 1 to 11.
16. A data carrier according to claim 15, characterized in that the data carrier is a banknote, especially a polymer banknote or a foil composite banknote, or a card, especially an identification or credit card.

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