EP1575785B1 - Security element and method for producing the same - Google Patents

Abstract

The invention relates to a security element (12, 18) with a carrier film (20) and a cover layer (22; 42; 50) applied to the carrier film (20). The cover layer has gaps (24; 30, 32, 34; 44) in the form of characters or patterns forming visually and/or machine readable first information. Additionally, a printed image (26; 36, 38, 40; 46, 48; 52) forming visually and/or machine readable second information is disposed in the gaps (24; 30, 32, 34; 44) in register, the first and second information being different.

Description

The invention relates to a security element comprising a carrier film and a cover layer applied to the carrier film, which has recesses in the form of characters or patterns which form visually and / or machine-readable first information. The invention further relates to a security paper and a valuable article with such a security element, as well as a method for producing such a security element.

Banknotes and other monetary securities, such as shares, checks, traveler's checks, check or credit cards, but also other forgery-prone papers, such as passports and other identity cards, are often secured by introducing or applying so-called security threads against counterfeiting. All papers of this type are referred to below as security papers. The security threads used are typically made of a plastic film, which are coated, printed, colored or pigmented substances with metallic coating.

If the metallic coated threads are arranged partially or completely inside the paper, then these areas are almost invisible in incident light, but appear in transmitted light as striking black stripes. Such an effect can not be imitated by a print on the paper and therefore contributes particularly to the security against counterfeiting.

Security films are also known which contain diffraction patterns, such as holograms, kinegrams or pixelgrams. The protection against counterfeiting of these elements is based on the variable color impression, which they convey to the observer depending on the viewing direction. Such security films are often in the form of strips or labels on valuables, such as value documents, or for product protection applied to any other objects to be secured.

To further increase security and as counterfeit protection, the security threads or the security films are often provided with a so-called negative writing. This negative writing is formed by metal-free regions in an otherwise continuous metallic coating of the carrier material of the security element. In the backlight, the element itself appears dark because of the opaque metallic coating. The metal-free areas stand out from this dark background easily recognizable bright. The special securing effect of the negative writing lies in particular in the complex and complex production process, which requires a lot of technical experience, a lot of equipment, special printing inks and a variety of steps.

Methods for producing recesses in the form of characters or patterns are described, for example, in the document EP 0 330 733 A1 specified. There, in particular, a production process is described in which a thermoplastic resin ink is printed on the metal-coated side of a film, which softens upon heating and intimately bonds with the metal layer. If one laminates a pretreated film under heat and pressure against a second untreated film and separates the two films after cooling, then the ink or the areas of the metallic coatings corresponding to the characters or patterns are removed from the first film.

From the publication DE 3610 379 A1 a method for the production of packaging material is known, in which on the films first a printed image is printed, as it later in the metal coating as a negative image should appear. The print image is applied in gravure or flexo printing. This printing inks or paints are used, which have only a low adhesion to the subsequent metal coating. Then, in a further process step, the metal coating is applied to the printed film. By the action of an air or liquid jet or a mechanical scraping device, finally, the metal coating is removed to expose the recesses in the form of the printed image.

All of the described methods have a working step in which the information, which is later to be in the form of recesses, is printed either with poorly adhering or corrosive printing inks. Since separate printing plates, such as a special gravure cylinder, have to be produced for this printing step, this is very laborious and costly. Negative characters can therefore be introduced into the security elements only economically if a correspondingly high number of elements is produced. For small runs or for series to be provided with several different designs of negative characters, the manufacturing cost in the known methods are too high.

It is further from the post-published document WO 2003/106185 It is known to provide the backing film of a security thread with a printed, gray cover layer having recesses to form approximately a negative writing. The gray color of the cover layer is caused by metallic pigments of the printing ink, which are usually called "supersilver". Since the security thread is printed in a printing press using register marks, it is easily possible to arrange a colored impression in the recesses in register. However, the gray color of the cover layer often undesirable, especially if the security thread is recognizable on the surface of the value document in which it is incorporated, as is the case, for example, with a window security thread of a banknote.

From the publication US 6,474,695 is a security element in the form of a metallized security thread or plastic tape known, the surface is provided with an opaque coating. The opaque coating has recesses in the form of characters and patterns to be applied to the security thread. For color design of the security element, the plastic tape is dyed with colorants or luminescent substances or is a color layer on the opposite side of the plastic tape or below the coating. Alternatively, the colorants or luminescent substances can also be present exclusively in the region of the recesses of the metal coating. In all three cases, there is a security thread, in which the recesses appear full color or are covered over the entire surface with color.

From the publication WO 99/04983 is a security document, for example a banknote, a security or an identity card, known, with a security element, which has at least one machine-testable, magnetic layer and at least one further layer. This further layer is a partially transparent layer in the visual spectral region, which covers the magnetic layer.

From the publication US Pat. No. 6,030,691 For example, a security paper with a security element in the form of a thread or ribbon is known, which consists of a translucent plastic film with at least partially opaque coating, wherein the coating translucent areas in the form of visually and / or machine-readable characters or patterns that form a first piece of information. On the plastic film, a second information in the form of visually and / or machine-readable characters or patterns is arranged, which distinguishes them from the first information regarding their size and / or their visual impression.

The invention is therefore an object of the invention to provide a security element and a method for its production, which avoid the disadvantages of the prior art. In this case, a visually appealing design of the security element is to be associated with low production costs even for short runs or series with varying information content.

This object is achieved by the security element having the features of the main claim. A security paper and a valuable article with such a security element, as well as a method for producing such a security element are the subject of the independent claims 16, 22 and 23. Further developments of the invention are the subject of the dependent claims.

According to the invention, in a security element of the type mentioned in the recesses of the cover layer in register, a printed image is arranged, which forms a visually and / or machine-readable second information, wherein the information content of the first and the second information is different. The invention is based on the recognition that for the register-containing printed image in the recesses digital printing can be used, which can not be used in direct securities printing due to their widespread use and easy handling due to the imitation risk.

In the case of the security element according to the invention, the securing effect, as described above in detail, is already brought about by the complex production process of the covering layer with recesses. It is therefore not necessary to use as counterfeit-proof method for impression in the recesses. Rather, a printed image is economically introduced into the recesses by means of digital printing, even in small batches, the information content of which differs according to the invention from the information content formed by the recesses itself. For example, banknotes of different denominations with the same geometric shape of the recesses can each be provided with a denomination representing print image in the recesses. Also, an individual design of each security element, such as by different colors, gradients or a code number is possible.

The cover layer may be opaque, screened or at least partially transparent. In this case, combinations of these designs are possible, the cover layer may be opaque in other areas and rasterized in other areas. The grid may have approximately the shape of a dot matrix, a line grid or a grid of repetitive similar raster elements of any geometric shape.

According to a preferred embodiment, the cover layer comprises a metal coating. In particular, the metal coating may be formed of aluminum, gold, copper, iron, nickel or an alloy containing one or more of these metals. The metal layer is preferably applied to the carrier film by the vacuum vapor method or by electron beam evaporation. Metallic cover layers are due to their Glaze effect visually very attractive and therefore can also be arranged on the surface of a value document.
The metal coating may additionally be combined with a plastic layer in which a surface relief in the form of a diffraction structure is embossed. As a result, an optically variable effect, in particular a viewing angle-dependent color impression, can be generated.

Alternatively, the cover layer may also include a dielectric layer structure that is opaque or partially transparent. Such layer structures also produce different color impressions in the viewer when the viewing angle changes in reflection. Such cover layers are also visually appealing and can therefore also be arranged on the surface of a value document.

The production of the recesses takes place either by subsequent removal of the metal layer by etching or by Schichtabtrag, for example by means of a laser. Preferably, however, the so-called "washing process" is used, in which a printing ink in the form of the later recesses is printed onto a carrier film before the application of the covering layer. After the full-surface application of the covering layer, this printing ink is dissolved by means of a suitable solvent, preferably water, so that both the printing ink and the covering layer are removed in this area.

The printed image introduced into the recesses may be finely structured and / or highly resolved, such as a pattern of guilloche lines. The printed image may contain a printing ink containing luminescent pigments, magnetic pigments, liquid crystal pigments and / or interference layer pigments. By printing inks with liquid crystal pigments or interference layer pigments can produce optically variable effects in the printed image. The printed image can also be multicolored or formed from a plurality of printing inks with different pigment content.

In particular, it can be provided according to the invention that the printed image forms letters, numbers or any geometric figures representing the visually and / or machine-readable second information. A first visually and / or machine readable information is already formed by the recesses in the cover layer. Also, the recesses may form letters, numbers or geometric figures, but according to the invention, the first and second information are different. For example, the recesses may form geometric figures in which a key figure, such as the denomination of a banknote, a portrait or a symbol, such as a country flag, is imprinted.

The printed image is imprinted according to the invention with a digital printing process in the recesses. In this case, digital printing methods denote printing methods in which the information is brought directly from a computer to the medium to be printed without creating a print template.

Digital printing methods preferably used in the invention include virtual digital printing methods such as inkjet, thermal sublimation or thermal transfer, temporary digital printing methods such as electrophotographic methods, ionography or magnetography, in particular toner-based printing methods such as laser printing or liquid-color methods such as indigo.

Inkjet or inkjet printing refers to a variety of monochrome or color non-impact printing technologies that use liquid or melted inks based on dyes or pigments, the inks. The droplets of ink may either be discontinuously shot onto the print substrate on demand (drop-on-demand), or a continuous stream of droplets of defined diameter droplets will be generated, and the droplets not required for the imaging will be electrically charged as they pass through a charging station deflected under the influence of an electric field in a droplet catcher, so that only the uncharged droplets for imaging on the printing substrate pass (continuous inkjet).

Electrophotographic printing methods, particularly laser copying methods, are various technologies in which a drum coated with photoreceptor material is rendered electrically conductive by irradiation by means of lasers or light emitting diodes. At the irradiated points toner accumulates, which is transferred to the printing substrate and fixed under heat.

According to the inventive method for producing a generic security element, the cover layer with the recesses is preferably first applied to the carrier film, and then generates the printed image in digital printing in register in the recesses of the cover layer. It is thus not necessary to produce the printed image before the application of the covering layer in a separate printing layer. Alternatively, it is also possible to first produce the printed image and then apply the cover layer.

In preferred embodiments, the security element forms a security thread or a tear thread, or a transfer element or a label for securing a valuables item.
The invention also includes a security paper provided with a security element of the type described in the form of a thread or a ribbon. The security element can be embedded as a window security thread in the security paper or be arranged completely on the surface of the security paper. Of course, it is also possible to embed the security thread completely in the paper. Alternatively, the security paper can be provided with a security element of the type described in the form of a transfer element adhered to the security paper.

It may be expedient that the printed image arranged in the recesses repeats the motif of another printed image of the security paper, such as a country flag, a denomination, a portrait or an architectural motif. Such a design leads to a graphically appealing design of the security paper and makes forgeries easily recognizable.

The invention also includes a valuable article which is provided with a security element of the type described, in particular in the form of a preferably affixed to the valuable article, transfer element or label. In this case, the individual layers of the security element can be generated directly on the object of value or prepared on a separate carrier. The security element can be designed as a self-supporting label, or it is produced on a transfer material from which it in the desired outline shape on the valuable item is transmitted. For fixation on the object of value, a hot-melt adhesive is preferably used.

The valuable item may be value documents, product packaging or any other items to be secured. For example, the security elements can be used as Kaschierfolien in passports or other identity cards. Also, the value documents provided with the security element can in turn be used to secure other items.

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

Fig.1

eine schematische Darstellung einer Banknote mit eingebette- tem Sicherheitsfaden und aufgeklebtem Transferelement, je- weils nach einem Ausführungsbeispiel der Erfindung,

Fig. 2

den Schichtaufbau eines Sicherheitsfadens nach einem Ausfüh- rungsbeispiel der Erfindung, und

Fig. 3 bis 5

verschiedene Ausgestaltungen eines Sicherheitsfadens nach bevorzugten Ausführungsbeispielen der Erfindung.

Show it:

Fig.1

1 a schematic representation of a banknote with embedded security thread and glued-on transfer element, in each case according to an exemplary embodiment of the invention,

Fig. 2

the layer structure of a security thread according to an embodiment of the invention, and

Fig. 3 to 5

various embodiments of a security thread according to preferred embodiments of the invention.

FIG. 1 shows a schematic representation of a banknote 10, which has an embedded window security thread 12 and a glued transfer element is provided with diffraction structures 18. The window security thread 12 comes to the surface of the bank note 10 at certain areas 14 with its shiny metallic coating, while it is embedded in the intervening areas 16 inside the bank note 10. The transfer element 18 is glued to the surface of the banknote 10 with a hot melt adhesive. Both the window security thread 12 and the transfer element 18 have a cover layer with in Fig.1 not shown recesses, in which in digital printing a printed image is introduced.

The structure and design of a security element according to the invention will be explained in more detail using the security thread 12 as an example. The transfer element 18 or other embodiments of security elements may be designed analogously. In this case, it is merely necessary to ensure that the layer sequence in the case of transfer elements is present in reverse order on a carrier film, so that the security element applied to the object of value has the construction shown in the figures.

FIG. 2 schematically shows the layer structure of the security thread 12 in cross section. According to FIG. 2 the security thread 12 comprises a transparent plastic layer 20 onto which a metallic coating 22, in the exemplary embodiment an aluminum layer, is applied. The metal layer 22 has recesses 24 in the form of letters, numbers or geometric shapes, which can be mounted both in the areas 14 lying on the surface of the banknote 10 and in the areas 16 located in the interior of the paper. For the areas 16 located in the interior, the information of the shape of the recesses 24 is only visible or readable in transmitted light. For the lying on the surface areas 14 of the security thread 12, the information shown in the incident light can be seen. In the Recesses 24 of the metal layer 22 is a printed image 26 imprinted in digital printing.

For producing the layer structure of Fig. 2 First, the metal layer 22 is applied with the recesses 24 on the plastic film 20 and then in a subsequent step, the printed image 26 with a digital printing method, in the embodiment with an ink jet method, register-generated in the recesses 24 of the metal layer 22.

The shape of the recesses 24 forms a first piece of information that can be machine readable visually or for a reader for a viewer. The print image 26 then represents a second information other than the first information within the recesses 24, which may also be visually or machine readable. It can be provided that the information of the printed image 26 is visible only by special measures, such as heating, cooling or irradiation with ultraviolet or infrared light, so the printed image 26 can be designed, for example, thermochromic or luminescent.

Alternatively, the printed image 26 can first be produced to produce the layer structure, then the metal layer with the recesses can be applied. Also conceivable is a combination of a printed image produced in digital printing with a cover layer which is produced by printing super silver.

The Fig. 3 to 5 show some advantageous variants of the design of the recesses 24 and the print image 26 in a security thread 12 in a schematic representation.

In the embodiment of the Fig. 3 has the security thread 12, as in the Fig. 2 , an opaque metal coating 22 made of aluminum. The metal layer 22 is provided with recesses 30, 34 in the form of rectangular windows and recesses 32 in the form of a code indicating the denomination of the banknote, for which the security thread 12 is determined in the embodiment.

The denomination of the banknote is additionally printed as print image 36 or 38 in digital printing in the rectangular windows 30 and 34, respectively. In this case, the printed images 36 and 38 can each be multicolored and / or executed differently in different rectangular windows 30 and 34, respectively. In the embodiment of Fig. 3 visualizing a window security thread 12, for example, the print image 36 is bicolored with opaque ink, while the print 38 is made with a luminescent color. When excited with UV light, this printed image lights up and thus contributes to a high security against counterfeiting of the banknote 10.

In the digit-shaped recesses 32, which represent the outline of the banknote 10 in its outline, a representation of the country flag 40 of the issuing country is imprinted in digital printing. The printing is done according to the color of each flag. Again, inks can be used with pigments that produce special optical effects.

A further embodiment of a security element according to the invention is shown in FIG Fig. 4 shown. In this embodiment, the security thread is designed with a covering layer in the form of a regular metal grid 42, which has rectangular recesses 44. In the recesses 44, as already in connection with the embodiment of Fig. 3 described in digital printing, for example, the denomination of the banknote 46 or a country flag 48 imprinted.

In a further variant, the metal layer is not flat, but designed as a sequence of smaller geometric units. A possible embodiment shows Fig. 5 , The metal layer is applied in the form of spaced circular elements 50 on the carrier film 20. In the spaces or recesses between the circular elements a printed image is arranged, which also consists of geometric shapes. In the exemplary embodiment, the printed image is formed by spaced colored triangles 52 which are each printed in the middle between two adjacent metal elements 50 in digital printing. It is understood that instead of the triangles 52 also other geometric shapes or, as in the 3 and 4 The denomination of the banknote and / or the country flag can be represented.

Claims (25)

1. A security element (12, 18) with a cover layer (22; 42; 50) having gaps (24; 30, 32, 34; 44) in the form of characters or patterns forming visually and/or machine readable first information, wherein a printed image (26; 36, 38, 40; 46, 48; 52) forming visually and/or machine readable second information is disposed in the gaps (24; 30, 32, 34; 44) in register, characterized in that the information content of the first and second information is different.
2. The security element (12, 18) according to claim 1, characterized in that the cover layer (22; 42; 50) is opaque at least in partial areas.
3. The security element (12, 18) according to claim 1 or 2, characterized in that the cover layer (22; 42; 50) is rasterized at least in partial areas, being configured in particular in the form of a dot screen, a line screen or a grid of iterative like grid elements.
4. The security element (12, 18) according to at least one of claims 1 to 3, characterized in that the cover layer (22; 42; 50) is semitransparent at least in partial areas.
5. The security element (12, 18) according to at least one of claims 1 to 4, characterized in that the cover layer (22; 42; 50) comprises a metal coating, preferably in that the metal coating is formed of aluminum, gold, copper, iron, nickel or an alloy containing one or more of said metals.
6. The security element (12, 18) according to at least one of claims 1 to 5, characterized in that the cover layer (22; 42; 50) contains a dielectric layer structure that produces different color impressions in reflected light upon a change of viewing angle.
7. The security element (12, 18) according to claim 6, characterized in that the dielectric layer structure is opaque or semitransparent.
8. The security element (12, 18) according to at least one of claims 1 to 7, characterized in that the security element (12, 18) contains a plastic layer with a surface relief in the form of a diffraction structure embossed thereinto.
9. The security element (12, 18) according to at least one of claims 1 to 8, characterized in that the printed image (26; 36, 38, 40; 46, 48; 52) is finely structured and/or of high resolution.
10. The security element (12, 18) according to at least one of claims 1 to 9, characterized in that the printed image (26; 36, 38, 40; 46, 48; 52) contains a printing ink containing luminescent pigments, magnetic pigments, liquid crystal pigments and/or interference layer pigments.
11. The security element (12, 18) according to at least one of claims 1 to 10, characterized in that the printed image (26; 36, 38, 40; 46, 48; 52) is multicolored or formed of printing inks with different pigment content.
12. The security element (12, 18) according to at least one of claims 1 to 11, characterized in that the printed image (26; 36, 38, 40; 46, 48; 52) forms letters, numbers or geometrical figures.
13. The security element (12, 18) according to at least one of claims 1 to 12, characterized in that the gaps (24; 30, 32, 34; 44) form letters, numbers or geometrical figures.
14. The security element (12) according to at least one of claims 1 to 13, characterized in that the security element forms a security thread (12) or a tear thread.
15. The security element (18) according to at least one of claims 1 to 13, characterized in that the security element forms a transfer element (18) or a label for protecting an object of value such as a document of value.
16. A security paper (10) having a security element (12) according to at least one of claims 1 to 15.
17. The security paper according to claim 16, characterized in that the security element is present in the form of a thread or band.
18. The security paper (10) according to claim 17, characterized in that the security element (12) is embedded into the security paper (10) as a windowed security thread.
19. The security paper (10) according to claim 17, characterized in that the security element is disposed completely on the surface of the security paper (10).
20. A document of value having a security element according to at least one of claims 1 to 15.
21. A document of value (10) according to claim 20, characterized in that the printed image (26; 36, 38, 40; 46, 48; 52) disposed in the gaps (24; 30, 32, 34; 44) iterates the motif of another printed image of the security paper (10), such as a national flag, a denomination, a portrait or an architectural motif.
22. An object of value provided with a security element (12, 18) in the form of a transfer element (18) or label according to any of claims 1 to 15 attached to the object of value.
23. A method for producing a security element with a printed image and a cover layer, wherein the cover layer has gaps in the form of characters or patterns, wherein the cover layer with the gaps is first applied to a carrier foil, and the printed image is then produced in the gaps of the cover layer in register by digital printing.
24. The method according to claim 23, characterized in that the cover layer comprises a metal layer, preferably a layer of aluminum, gold, copper, iron, nickel or an alloy containing one of said metals, and in that the metal layer is applied by vapor deposition or by electron-beam vaporization.
25. The method according to claim 23 or 24, characterized in that the printed image is produced in the gaps by a virtual digital printing method such as ink jet, thermal sublimation or thermal transfer, a temporary digital printing method such as an electrophotographic method, ionography or magnetography, in particular by a toner-based printing method such as laser printing, or by a liquid-ink method such as Indigo.

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