EP1744905B1 - Layer-type value document comprising an ink mixture in one layer - Google Patents

Description

The invention relates to a value document, in particular a banknote, with a layer sequence, in which by the action of laser radiation visually and / or machine-recognizable markings in the form of patterns, letters, numbers or images are introduced. The invention also relates to a security element for value documents with such a layer sequence and to methods for producing such value documents or security elements.

Identity cards, such as credit cards or identity cards, have long been personalized by laser engraving. In personalization by laser engraving, the optical properties of the card material in the form of a desired marking are irreversibly changed by suitable guidance of a laser beam. For example, in the document DE 30 48 733 A1 an identity card with applied information is described, which has on a surface of different colored and stacked layer areas, which are at least partially interrupted by visually recognizable personalization data.

Furthermore, from the WO 03/039888 A1 a value document with a layer sequence known in the by the action of laser radiation visually and / or machine-recognizable markings are introduced in the form of patterns, letters, numbers or images. In the layer sequence, a change in the optical properties is effected by the action of the laser radiation.

In general, value documents such as banknotes, stocks, bonds, certificates, vouchers, checks; Tickets and the like, provided with an individualizing tag, such as a serial number.

Proceeding from this, the object of the invention is to propose a value document of the type mentioned at the beginning, which has laser-generated markings of high security against counterfeiting. To further increase the safety and recognizability of the markings in particular be associated with other, hard to imitate optical effects.

This object is achieved by the value document and the security element having the features of the independent claims. Methods for producing the same are given in the independent claims. Further developments of the invention are the subject of the dependent claims.

According to a first aspect of the invention, the layer sequence of the document of value contains a marking layer of a color mixture which has a mixture component absorbing the laser radiation and a mixture component transparent to the laser radiation. The markings are visually and / or mechanically recognizable due to an irreversible change in the optical properties of the paint mixture caused by the action of the laser radiation. In the context of the present description, the term "layer sequence" designates a sequence of at least one, but as a rule more than one layer arranged above and / or next to one another. The term "optical properties" includes primarily the absorption and reflection properties of a material for optical radiation (ultraviolet, visible or infrared radiation), but also other specific responses to the incidence of optical radiation, such as fluorescence or phosphorescence emission.

As explained in detail below, the absorbing mixture component under the action of the laser radiation, for example, bleached, evaporated, changed in their reflective properties or by a chemical Reaction can be converted into a material with different optical properties.

In a preferred variant of the invention, the introduced markings are visually recognizable without aids. This means that no special equipment is required to illuminate or look at the markings, but that they can be seen by the unaided eye under normal environmental conditions.

The color mixture preferably contains optically variable color pigments, in particular optically variable liquid crystal pigments or a transparent or translucent intaglio printing ink and, for example, optically variable interference layer pigments for the absorbing mixture component as the mixture component transparent to the laser radiation. Other color components which can be irreversibly changed in their optical properties, such as an intaglio printing ink, a metallic effect ink or metallic pigments, a luminescent color or luminescent pigments, luster pigments or a thermochromic color, are also suitable for the absorbing mixture component.

It is also possible that the optical properties of the absorbent mixture component do not change, but that the color mixture contains a color component which interacts with the absorbent mixture component, the optical properties of which are indirect, namely by the absorption of the laser radiation in the absorbent mixture component, in particular the local Temperature shift in the marking layer, irreversibly changed.

As such a cooperating color component, in particular, even non-absorbing color components, such as certain intaglio inks, luminescent colors or luminescent pigments, luster pigments or thermochromic colors are suitable. As an absorbing mixture component, the color mixture contains, for example, carbon black, graphite, TiO ₂ or an infrared absorber.

In a preferred embodiment of the invention, the layer sequence has at least one laser radiation absorbing layer which is arranged between the marking layer and the substrate of the document of value. In a further preferred refinement, the layer sequence has at least one layer absorbing the laser radiation and at least one layer transparent to the laser radiation, both of which are arranged between the marking layer and the substrate of the document of value.

A layer transparent to the laser radiation is preferably arranged between the absorbing layer and the marking layer. Also advantageously, a (further) transparent to the laser radiation layer between the absorbent layer and the substrate of the document of value is arranged.

One or more of the absorbent or transparent layers are structured according to an advantageous development of the invention information leading. The structures are preferably produced at least partially by printing technology. It is also preferred if the information-carrying structures at least partially by the action of the laser radiation, in particular by a partial removal of a absorbent layer are produced. Printing technology structuring and laser ablation can cooperate with particular advantage and complement each other in order to produce special, practically not reproducible printing technology alone effects, such as the pass effects described below.

In a further advantageous embodiment, the layer sequence contains, in addition to the marking layer, a further layer of a color mixture which has a mixture component absorbing the laser radiation and a mixture component transparent to the laser radiation. The further color mixture layer is arranged between the marking layer and the substrate of the value document. The further color mixture layer preferably has a color mixture of the type described above for the marking layer. If appropriate, the further color mixture layer is structured in terms of information by printing technology.

After the laser application of the layer sequence, only the transparent mixture component then remains in the further color mixture layer. This embodiment can therefore serve as an alternative to a layering of a transparent and an absorbent layer as a substrate to the marking layer. In this case as well, the effect of the laser radiation makes a colored background visible and it is possible to save a pressure layer and thus a single operation. For the further color mixture layer also color mixtures, as they are for the Offsetbzw. Nyloprintdruck be used, optionally with other effect components. For example, a black blend of absorbing milori blue, red and yellow may be used. By the action The laser radiation is the blue area removed and an orange tone remains.

In all described embodiments, the information-carrying structuring advantageously forms at least part of the markings, and can be visually recognized on account of the irreversible change in the optical properties of the color mixture. For example, the information-carrying structures are introduced by printing technology in various printing layers, which are covered by an initially opaque or only translucent marking layer. As a result of the action of the laser, the marking layer is partially transparent or even removed, so that the underlying structuring can be recognized.

In another, likewise preferred variant of the invention, the introduced markings are not visually recognizable or at least not recognizable without auxiliary means. This means that, for example, special lighting devices or special viewing devices are required for the detection of the markings, while the markings are essentially invisible to the unaided eye under normal ambient conditions. Such markings are used particularly with banknotes or other value-representing data carriers with particular advantage because they are essentially invisible to the human eye, the design of the disk is not or only slightly disturbing, they take up little space on the disk and they represent a safety feature for yourself.

The introduced markings are preferably recognizable in the infrared spectral range. The markings can stand out from their surroundings, for example, in the IR reflectivity and thus detected by irradiation with an infrared lamp with an infrared detector and evaluated by machine.

In another advantageous embodiment, the introduced markings are recognizable after irradiation with ultraviolet radiation. In this case, for example, a different reflectivity in the ultraviolet spectral range can be utilized, or luminescent substances can be provided which emit visible or infrared radiation after excitation with UV radiation.

The absorbing mixture component and the transparent mixture component appear in the visible spectral range preferably the same shade, so that the label remains invisible to the naked eye without aids. In this case, the color mixture visually preferably has a hue different from black, thus appearing, for example, blue, green or red.

It has proven to be advantageous if the proportion of the transparent mixture component outweighs the proportion of the absorbing mixture component in the color mixture. As a result, it can be achieved in a simple manner that the markings can not be recognized by the naked eye despite sufficiently high feature contrast in the case of machine detection. In particular, the transparent mixture component in the color mixture Suitably a proportion of 60% or more, preferably of 70% or more, particularly preferably of 80% or more, on.

In a second aspect of the invention, the layer sequence of the value document has at least one layer absorbing the laser radiation and at least one layer transparent to the laser radiation, wherein at least one of the absorbing or transparent layers contains optically variable color pigments. The markings are visually recognizable in this embodiment due to an area-wise ablation of the at least one absorbing layer caused by the action of the laser radiation.

At least one of the layers absorbing or transparent to the laser radiation is advantageously structured in an informative manner, wherein the information-carrying structures can be generated at least partially by printing technology. Likewise advantageously, the information-carrying structures can be generated at least partially by the action of the laser radiation, in particular by a removal of a (further) absorbing layer in regions. The optically variable color pigments are preferably formed by liquid-crystal pigments or interference-layer pigments.

According to a further aspect of the invention, machine identifiable characteristics are introduced into a layer sequence of a value document. In a first variant of this aspect, the layer sequence has at least one layer absorbing the laser radiation and at least one layer transparent to the laser radiation. At the same time appear the absorbing Layer and the transparent layer in the visible spectral range of the same color, and the markings are mechanically recognizable due to a caused by the action of the laser radiation areawise change of the absorbent layer. However, they are not visually recognizable or at least not recognizable without aids.

Also in this aspect of the invention, the introduced markings are preferably recognizable in the infrared spectral range or after irradiation with ultraviolet radiation. The absorbing layer and the transparent layer visually advantageously have the same hue different from black.

Suitably, the transparent to the laser radiation layer has a greater thickness than the absorbent layer, so that the markings remain invisible to the naked eye. The absorbent layer is advantageously arranged above the transparent layer so that there is no risk of the transparent layer bursting on absorption of the marking radiation in the absorbent layer.

According to another variant of this aspect of the invention, the finishing sequence and the underlying value document substrate have the same color tone in the visible spectral range. The layer sequence has at least one laser radiation absorbing layer. As in the case of the first variant of this aspect of the invention, the markings are mechanically recognizable due to an area-wise change in the absorbing layer caused by the action of the laser radiation, but are not recognizable visually or at least not without aids. Likewise, the introduced markings preferably in the infrared spectral range or after irradiation with ultraviolet radiation recognizable. The absorbing layer and the underlying value document substrate visually preferably have a hue different from black.

In both variants, it can be provided that the absorbent layer is structured in an information-guiding manner. An optionally provided transparent layer can also be structured as an information guide. Preferably, these information-carrying structures are at least partially produced by printing technology. Also useful is an embodiment in which the information-carrying structures are at least partially generated by the action of the laser radiation, in particular by a removal of an absorbent layer in regions. As in the first aspect of the invention, printing-technical structuring and laser ablation can cooperate with particular advantage and complement one another in order to produce virtually unreproducible effects in terms of printing technology alone.

In all aspects of the invention and variations, the labels may include an individualization identifier for the value document, such as a serial serial number, a symbol code such as a bar or matrix code, or the like.

The invention also includes a security element for value documents, which is provided with a layer sequence according to one of the invention aspects or variants described above.

• eine vorbestimmte Laserwellenlänge ausgewählt wird,
• auf ein Substrat oder auf eine Schicht der Schichtenfolge eine Markierungsschicht aus einem Farbgemisch aufgebracht wird, das eine die Laserstrahlung der vorbestimmten Laserwellenlänge absorbierende Gemischkomponente und eine für die Laserstrahlung der vorbestimmten Laserwellenlänge transparente Gemischkomponente aufweist, und
• durch Beaufschlagung der Schichtenfolge mit Laserstrahlung der vorbestimmten Laserwellenlänge Kennzeichnungen in Form von Mustern, Buchstaben, Zahlen oder Bildern in die Schichtenfolge eingebracht werden, die aufgrund einer durch die Einwirkung der Laserstrahlung bewirkten irreversiblen Änderung der optischen Eigenschaften des Farbgemisches visuell und/oder maschinell erkennbar sind.

The invention further comprises a method for producing a security element or a value document with a layer sequence, in which

• a predetermined laser wavelength is selected
• on a substrate or on a layer of the layer sequence, a marking layer is applied from a color mixture having a mixture component absorbing the laser radiation of the predetermined laser wavelength and a mixture component transparent to the laser radiation of the predetermined laser wavelength, and
• By applying the layer sequence with laser radiation of the predetermined laser wavelength, markings in the form of patterns, letters, numbers or images are introduced into the layer sequence which are visually and / or mechanically recognizable due to an irreversible change in the optical properties of the paint mixture caused by the action of the laser radiation.

• wird eine vorbestimmte Laserwellenlänge ausgewählt,
• werden auf ein Substrat oder auf eine Schicht der Schichtenfolge zumindest eine die Laserstrahlung der vorbestimmten Laserwellenlänge absorbierende Schicht und eine für die Laserstrahlung der vorbestimmten Laserwellenlänge transparente Schicht aufgebracht, wobei zumindest eine der absorbierenden oder transparenten Schichten optisch variable Farbpigmente enthält, und
• werden durch Beaufschlagung der Schichtenfolge mit Laserstrahlung der vorbestimmten Laserwellenlänge Kennzeichnungen in Form von Mustern, Buchstaben, Zahlen oder Bildern in die Schichtenfolge eingebracht, die aufgrund einer durch die Einwirkung der Laserstrahlung bewirkten bereichsweisen Abtragung der absorbierenden Schicht visuell erkennbar sind.

Advantageously, at least one layer absorbing the laser radiation and optionally additionally a layer transparent to the laser radiation is applied, in particular printed, between the marking layer and the substrate of the value document or security element. In a further method for producing a security element or a value document with a layer sequence

• a predetermined laser wavelength is selected
• at least one layer absorbing the laser radiation of the predetermined laser wavelength and a layer transparent to the laser radiation of the predetermined laser wavelength are applied to a substrate or to a layer of the layer sequence, wherein at least one of the absorbing or transparent layers contains optically variable color pigments, and
• By applying the layer sequence with laser radiation of the predetermined laser wavelength, markings in the form of patterns, letters, numbers or images are introduced into the layer sequence, which are visually recognizable due to an area-wise ablation of the absorbing layer caused by the action of the laser radiation.

In both said variants of the method, at least one of the layers absorbing or absorbing the laser radiation is advantageously structured in an informative manner, wherein the information-carrying structures are preferably produced at least partially by printing technology. Likewise advantageously, the information-carrying structures can be generated at least partially by the action of the laser radiation, in particular by a removal of a (further) absorbing layer in regions.

• eine vorbestimmte Laserwellenlänge ausgewählt wird,
• auf ein Substrat oder auf eine Schicht der Schichtenfolge zumindest eine die Laserstrahlung der vorbestimmten Laserwellenlänge absorbierende Schicht und eine für die Laserstrahlung der vorbestimmten Laserwellenlänge transparente Schicht aufgebracht werden, wobei die transparente und die absorbierende Schicht im sichtbaren Spektralbereich farbtongleich erscheinen, und
• durch Beaufschlagung der Schichtenfolge mit Laserstrahlung der vorbestimmten Laserwellenlänge Kennzeichnungen in Form von Mustern, Buchstaben, Zahlen oder Bildern in die Schichtenfolge eingebracht werden, die aufgrund einer durch die Einwirkung der Laserstrahlung bewirkten bereichsweisen Veränderung der absorbierenden Schicht maschinell erkennbar sind, jedoch visuell nicht, oder zumindest nicht ohne Hilfsmittel erkennbar sind.

According to a further aspect, the invention includes a method for producing a value document with a layer sequence, in which

• a predetermined laser wavelength is selected
• at least one layer absorbing the laser radiation of the predetermined laser wavelength and a layer transparent to the laser radiation of the predetermined laser wavelength are applied to a substrate or to a layer of the layer sequence, the transparent and the absorbing layer appearing in the same color in the visible spectral range, and
• By applying the layer sequence with laser radiation of the predetermined laser wavelength, markings in the form of patterns, letters, numbers or images are introduced into the layer sequence, which are mechanically recognizable due to an area-wise change of the absorbing layer caused by the action of the laser radiation, but not visually, or at least are not recognizable without aids.

• eine vorbestimmte Laserwellenlänge ausgewählt wird,
• auf das Wertdokumentsubstrat eine im sichtbaren Spektralbereich farbtongleich erscheinende Schichtenfolge mit zumindest einer die Laserstrahlung der vorbestimmten Laserwellenlänge absorbierenden Schicht aufgebracht wird, und
• durch Beaufschlagung der Schichtenfolge mit Laserstrahlung der vorbestimmten Laserwellenlänge Kennzeichnungen in Form von Mustern, Buchstaben, Zahlen oder Bildern in die Schichtenfolge eingebracht werden, die aufgrund einer durch die Einwirkung der Laserstrahlung bewirkten bereichsweisen Veränderung der absorbierenden Schicht maschinell erkennbar sind, jedoch visuell nicht, oder zumindest nicht ohne Hilfsmittel erkennbar sind.

According to yet another aspect, the invention includes a method for producing a value document with a layer sequence, in which

• a predetermined laser wavelength is selected
• on the value document substrate, a layer sequence appearing the same color tone in the visible spectral range with at least one layer absorbing the laser radiation of the predetermined laser wavelength is applied, and
• By applying the layer sequence with laser radiation of the predetermined laser wavelength, markings in the form of patterns, letters, numbers or images are introduced into the layer sequence, which are mechanically recognizable due to an area-wise change of the absorbing layer caused by the action of the laser radiation, but not visually, or at least are not recognizable without aids.

Suitable laser sources are CO ₂ lasers, Nd: YAG lasers, Nd: YVO ₄ lasers or other types of lasers in the wavelength range from UV to far-infrared, where the lasers often also advantageously work with frequency doubling or tripling. Laser sources in the near infrared are used with particular advantage, since this wavelength range fits well with the absorption properties of the substrates and printing inks used for value documents. For example, it is easy to specify for this range printing inks which are transparent to the laser radiation but opaque and colored in the visible spectral range for the human observer. YAG laser or Nd: with particular advantage infrared laser in the wavelength range from 0.8 microns to 3 microns, in particular Nd be used YVO ₄ laser.

With an Nd: YAG marking laser (λ = 1.064 μm), for example, vectors can be inscribed in the layer sequence, which is advantageous, above all, for fast inscriptions. For this purpose, a Nd: YAG laser with a pulse frequency between 20 kHz and continuous wave, a power between 10 and 100 W, for example 50 W, and a travel speed between 3 and 30 m / s, preferably operated between 7 and 20 m / s , The working distance between the lens and the substrate is chosen to be slightly less than that required for optimum focusing in order to achieve a slight defocusing of the laser spot.

In another example of introducing the markings, an Nd: YVO ₄ marker laser (also A = 1.064 μm) is operated in raster mode, which is particularly advantageous for imaging and labeling passport cards or data pages. For this purpose, the Nd: YVO ₄ laser can be operated, for example, with a pulse frequency between 20 kHz and 80 kHz, a power between 0.5 and 4 W and for a dot resolution of the grid between 250 and 4800 dpi. Again, the laser spot can be easily defocused.

Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, in the representation of which a representation true to scale and proportion has been dispensed with in order to increase the clarity.

Fig. 1

eine schematische Darstellung einer Banknote mit einem erfindungsgemäß gestalteten Kennzeichnungsbereich,

Fig. 2

ein Substrat mit einer bereichsweise veränderten Markierungsschicht aus einem Effektfarbengemisch,

Fig. 3

ein Substrat mit einer bereichsweise abgetragenen Schichtenfolge absorbierender und transparenter Schichten,

Fig. 4

ein Wertdokument nach einem Ausführungsbeispiel der Erfindung, bei dem in (a) der Kennzeichnungsbereich des Dokuments in Aufsicht und in (b) der Schichtaufbau in Querschnittsdarstellung entlang der Linie B-B von (a) gezeigt ist,

Fig. 5

eine Darstellung wie in Fig. 4 für ein anderes Ausführungsbeispiel der Erfindung,

Fig. 6

ein weiteres Ausführungsbeispiel eines Wertdokuments, das einen makroskopischen Passereffekt zeigt,

Fig. 7

ein Ausführungsbeispiel eines Wertdokuments mit einem nur unter der Lupe erkennbaren Mikropasser, wobei (a) den Schichtaufbau vor der Laserbeaufschlagung und (b) die gekennzeichnete Schichtenfolge nach erfolgter Laserbeaufschlagung zeigt,

Fig. 8

in (a) den Kennzeichnungsbereich des Wertdokuments von Fig. 7 in Aufsicht, und (b) einen Ausschnitt im Randgebiet des laserbeaufschlagten Bereichs,

Fig. 9

in einer perspektivischen Explosionsdarstellung die aufeinander folgenden, drucktechnisch strukturierten Schichten des Wertdokuments von Fig. 7 und 8,

Fig. 10

ein Ausführungsbeispiel eines Wertdokuments mit einer maschinell erfassbaren Kennzeichnung, die für das menschliche Auge ohne Hilfsmittel nicht erkennbar ist,

Fig. 11

einen Ausschnitt des Wertdokuments der Fig. 10 schematisch in Aufsicht, wobei (a) die visuelle Erscheinung und (b) das Bild einer IR-Kamera bei Beleuchtung des Wertdokuments mit einer IR-Lampe zeigt, und

Fig. 12 und 13

weitere Ausführungsbeispiele für Wertdokumente mit einer maschinell erfassbaren Kennzeichnung.

Show it:

Fig. 1

a schematic representation of a banknote with an inventively designed labeling area,

Fig. 2

a substrate with a partially modified marking layer of an effect color mixture,

Fig. 3

a substrate with a partially removed layer sequence of absorbing and transparent layers,

Fig. 4

a value document according to an embodiment of the invention, wherein in (a) the marking region of the document in plan view and in (b) the layer structure in cross-sectional view along the line BB of (a) is shown

Fig. 5

a representation like in Fig. 4 for another embodiment of the invention,

Fig. 6

another embodiment of a value document showing a macroscopic pass effect,

Fig. 7

an embodiment of a value document with a micropasser recognizable only under the magnifying glass, wherein (a) shows the layer structure before the laser application and (b) the marked layer sequence after laser application,

Fig. 8

in (a) the identification area of the value document of Fig. 7 in plan view, and (b) a section in the edge region of the laser-applied region,

Fig. 9

in a perspective exploded view of the successive, technically structured layers of the value document of Fig. 7 and 8th .

Fig. 10

an embodiment of a value document with a machine-detectable label that is not recognizable to the human eye without aids,

Fig. 11

a section of the document of value Fig. 10 schematically in plan view, showing (a) the visual appearance and (b) the image of an IR camera upon illumination of the value document with an IR lamp, and

FIGS. 12 and 13

Further embodiments of value documents with a machine-detectable label.

The invention will now be explained first using the example of a banknote. Fig. 1 shows a schematic representation of a banknote 10, on the front side in a marking area 12 by the action of a laser beam visually recognizable markings in the form of patterns, letters, numbers or images are introduced. The markings may include, for example, the denomination of the bill, a serial number, a signature, or other text or graphic objects. The markings may also have been initially formed on a transfer element, which was then applied to the banknote, in particular glued.

The basic principles of inventive markings will now be described with reference to the cross-sectional representations of FIGS. 2 and 3 explained.

Fig. 2 1 shows a substrate 20, for example a banknote or another value document, on which a marking layer 22 made of a color mixture of two mixture components 24 and 26 is applied. One of the mixture components 24 is transparent to the radiation of the infrared laser used below for marking, the other mixture component 26 absorbs the laser radiation. In region 28, the marking layer 22 has been irradiated with the marking laser with suitably selected laser parameters to remove, alter, or deactivate the absorbent mixture component 26 by the action of the laser radiation.

For example, depending on the material used, the absorbent blend component 26 may be bleached, vaporized, altered in reflective properties, or converted to a material having other optical properties by a chemical reaction. Overall, the optical properties of the color mixture in the region 28 are irreversibly changed by the irradiation. Possible effects include a change in color, the generation of a color change, the lightening of a color, the change in the tipping color of an effect color mixture or the local change of the polarization properties or the luminescence properties of the marking layer 22.

Due to the laser-induced change in the optical properties of the color mixture, visually recognizable markings are created in the value document. These may be formed by the shape of the irradiated and modified regions 28 of the marking layer itself, or themselves only in conjunction with other, for example, information-containing structured printed layers result.

For example, an information-carrying printing layer may be provided between the substrate 20 and the marking layer 22, and the change of the optical properties of the marking layer 22 in the production of transparent portions 28 in an otherwise opaque layer, so that the information of the print layer in these areas after the laser irradiation are visible.

In the alternative design of Fig. 3 On a substrate 30, a layer sequence 32 is applied which has a first layer 34 transparent to the laser radiation of the selected wavelength, an absorbing layer 36 and a second layer 38 transparent to the laser radiation. At least one of the absorbent or transparent layers contains optically variable color pigments. For example, the transparent layer 34 may include liquid crystal pigments that exhibit a reflection-angle-changing reflection color.

As a result of laser irradiation, the absorbent layer 36 has been removed in a partial region 40, wherein the transparent layer 38 lying above the absorbent layer 36 has been entrained by ablation therewith. If, for example, an infrared laser, for example an Nd: YAG laser with λ = 1.064 μm, is used for the ablation, then the layers 34, 38 transparent to the laser radiation can be opaque and colored in the visible spectral range. Due to the shape and shape of the removed area 40, a variety of markings can be introduced into the layer sequence 32, in which, for example an optically variable color effect of a liquid crystal layer 34 emerges in contrast to a monochrome surrounding area of a second transparent print layer 38.

Another embodiment of the invention is in Fig. 4 shown. On a value document 50, a layer sequence 54 is applied in an identification region 52, the layer structure of which is along the line BB of FIG Fig. 4 (a) in the cross-sectional view of Fig. 4 (b) is shown. On the value document substrate 56, a print layer 58 which is transparent to infrared radiation but appears to be dark in the visible, is printed in the marking area, and a marking layer 60 composed of an effect ink mixture is applied to this print layer. In the exemplary embodiment, the effect color mixture contains optically variable liquid-crystal pigments 62 as the transparent mixture component and optically variable interference-layer pigments 64 as the absorbing mixture component. The marking layer 60 first shows the two-color change characteristic of optically variable pigments over the full area when tilting the value document.

In a subregion 66, the layer sequence 54 was then exposed to the infrared radiation of an Nd: YAG laser. The interference layer pigments 64 absorb the laser light and are thereby deactivated and / or removed in the subregion 66. There remain only those transparent to the laser radiation liquid crystal pigments 62, which show the characteristic of liquid crystal pigments color shift effect against the dark background of the print layer.

In general, the marking formed by the sub-region 66 when viewed vertically appears in a first color 70 and its surroundings in a second color 72. When tilting the value document, the liquid crystal pigments 62 produce a third color impression 74 in the acute viewing direction, the interference layer pigments 64 a fourth color impression 76. A particularly impressive tipping effect results when the first and fourth colors 70 and 76, and the second and third colors 72 and 74 are chosen the same, because then the color contrast just reverses when the value document is tilted. Such an effect can be achieved by suitable matching of the liquid crystal pigments 62 and the interference layer pigments 64.

In the embodiment of the Fig. 4 the information content of the marking is given by the shape of the lasered portion 66. Alternatively or additionally, the print layer 58 may be designed to carry information, as in the Fig. 5 illustrated. In this embodiment, the payload 80, here the digit sequence "10", introduced by printing technology in the printing layer 82, but initially not visible through the opaque marking layer 60 therethrough. By exposing the laser region 84 to the radiation of an infrared laser, the absorbing interference-layer pigments 64 are deactivated and / or removed there, so that the printed information 80 is visually recognizable in the now transparent laser region 84. In this variant, the laser irradiation can be done over a large area, since the payload is represented by printing technology.

In further embodiments of the invention, the printing technique structuring and the laser structuring are combined to different To create pass effects. Fig. 6 first shows an exemplary embodiment with a macroscopic, ie large-area register effect, wherein in Fig. 6 (a) a survey of the marking area 90 of a value document and in the Figs. 6 (b) and 6 (c) the layer structure of the value document and the applied layer sequence along the lines BB and CC of the Fig. 6 (a) is shown.

On the value document substrate 92 two color layers 94 and 96 are printed side by side, which have the same hue in plan view, but differ in their absorption behavior for the infrared laser radiation. The first color layer 94 is transparent to the laser radiation, absorbing the second color layer 96. The two color layers can also be structured and provided, for example, with a pattern, guilloche, or micro-writing. Also, further print layers may be disposed between the substrate 92 and the two color layers 94, 96.

Applied to the two color layers 94, 96 is a marking layer 98 composed of an effect color mixture which, in the exemplary embodiment, contains optically variable liquid crystal pigments 100 as a transparent mixture component and metallic pigments 102 as an absorbing mixture component. If the layer sequence is now exposed to infrared laser radiation in a marking region 104, adjacent regions with different visual appearances will result.

Outside of the marking area 104, the original layer sequence is retained even after the laser irradiation, as in FIG Fig. 6 (b) shown. In supervision, the appearance is dominated by the metallic shimmering metallic pigments 102.

In the labeling area 104, the transparent color layer 94 is not changed, but the overlying effect color mixture 98, see FIG Fig. 6 (c) , The absorbent mixture component, the metallic pigments 102, are removed by the laser radiation, so that in these areas 106 the color-shift effect of the liquid-crystal pigments 100 appears in the background of the color layer 94.

In the irradiated region 108 of the absorbing ink layer 96, it is removed by the action of the laser radiation together with the overlying marking layer 98. At the boundary line 110 of the absorbing ink layer 96 and the transparent ink layer 94, an absolutely exact macroscopic register is produced.

A complex embodiment of the invention with a recognizable only under the microscope micro-water will now be with reference to the Fig. 7 to 9 explained. First shows Fig. 7 (a) the layer structure of the layer sequence 122 applied to a light security substrate 120 before the laser application. The layer sequence 122 comprises a first color layer 124 transparent to the laser radiation, an absorbing layer 126, a second color layer 128 transparent to the laser radiation, and a marking layer 130 of an effect color mixture which, as in the exemplary embodiment of FIG Fig. 4 contains optically variable liquid crystal pigments 132 and optically variable interference layer pigments 134 as transparent or absorbent mixture components. In the present embodiment the effect color mixture has a high proportion of liquid crystal pigments 132, so that the mixture has an overall glaze effect.

The color layers 124, 126 and 128 are already applied structured in terms of printing technology, with the first transparent color layer 124 and the absorbing color layer 126 being printed in the exemplary embodiment with a congruent structuring. In the visible, the infrared-transparent color layers 124, 128 may appear red or black, for example. The marking layer 130 is applied over the color layers 124, 126 and 128 over the entire surface.

After the application of the layer sequence 122 with laser radiation in a laser region 136 results in the Fig. 7 (b) illustrated situation. As related to Fig. 4 As already explained, the marking layer 130 in the laser region 136 is converted into a transparent modification by the removal or deactivation of the interference layer pigments 134, so that depending on the background, the color-shift effect of the liquid crystal pigments 132 may be present.

Due to the transparent part of the marking layer 130 and the transparent ink layer 128, the laser radiation also reaches the lower-lying absorbing ink layer 126. The action of the laser radiation ablates the laser radiation, whereby it also entrains the areas of the transparent ink layer 128 and the marking layer 130 immediately above it. so that in these areas 146, the first color layer 124 is exposed.

In the region 140 outside the laser region 136, the two-color change effect of the interference-layer pigments 134 dominates. In the adjacent region 142, the modified marking layer overlies the light-colored security substrate 120, so that the color-shift effect is barely visible when viewed and area 142 appears substantially featurelessly bright. In region 144, the modified marking layer is disposed over the second color layer 128, so that here the color-shift effect of the liquid crystal pigments 132 is clearly visible through the dark background. In the already mentioned fourth area 146, the red color layer 124 is visible.

Fig. 8 shows the corresponding identification area 150 of the value document in a plan view, wherein the shape of the laser area 152 as large area information represents the number sequence "10", as in Fig. 8 (a) shown. Fig. 8 (b) shows a section 154 in the edge region of the laser region 152, in which the micropasser formed by the micro-digit sequence "10" is clearly visible. The exact structure of the illustrated identification area 150 is best understood in conjunction with FIGS Fig. 7 and 9 the latter, the latter showing the successive structured layers of the layer sequence 122 in a perspective exploded view.

Regarding Fig. 7 and 9 is the lowest color layer, the first, red color layer 124 in the form of the micro-digit sequence "10" on the in Fig. 9 not shown value document substrate printed. The absorbing ink layer 126 is printed congruently on the first color layer 124 and likewise in the form of the micro-digit sequence "10". The second transparent color layer 128 is how best in Fig. 9 with a visibly glazed color in the form of a checkered pattern with small squares 156 and 158 printed in two different shades of gray. The translucent marking layer 130 is applied over the entire surface of this second ink layer 128, wherein in the Fig. 9 also the part of the laser region 152 that falls in the cutout 154 is shown.

After laser irradiation of the marking 152 results in the neck of the Fig. 8 (b) Appearance: Outside of the laser region 152, the checkered pattern of the second color layer 128 and the underlying dark color layer 126 in the form of the micro-digit sequence "10" can be recognized by the translucent marking layer 130.

In the lasered area 152 is, as already in connection with the Fig. 7 5, the absorbent color layer 126 is removed together with the second transparent color layer 128 and the marking layer 130, so that the microfilm "10" in the red color of the first color layer 124 appears there. As in Fig. 8 (b) can be seen, results along the boundary lines 160 of the laser range, a sharp and exact register accurate transition between the two color impressions in the micro-digit. Such a microscopic registration effect can not be reproduced by printing technology.

In alternative embodiments, the first transparent color layer 124 may also be absent. In this case, the light value document substrate itself is recognizable in the areas 146.

• 1) ein Gemisch aus 20% bis 90% Flüssigkristallpigment-Farbe (STEP®) und 10% bis 80% Metallschichtpigment-Farbe (OVI®), sowie 1% bis 10% einer anderen Farbe.
• 1') ein Gemisch aus 12,5 Teilen Magenta/Grün der Firma Sicpa (OVI®) und 25 Teilen der Farbe HELICONE® HC Scarabeus der Firma Wacker, sowie 1,5 Teilen einer anderen Farbe.
• 2) ein Gemisch aus 10% bis 80% Metallpigment-Farbe (Metallfarbe Gold- und Silberfarben) und 20% bis 90% Flüssigkristallpigment-Farbe (STEP®).
• 2') ein Gemisch aus 4 Teilen Goldfarbe für den Siebdruck der Firma Sicpa und 25 Teilen der Farbe HELICONE® HC Maple der Firma Wacker.

In the aforementioned embodiments, for example, the following color mixtures can be used for the effect color mixture:

• 1) a mixture of 20% to 90% liquid crystal pigment paint (STEP®) and 10% to 80% metal layer pigment paint (OVI®), as well as 1% to 10% of another color.
• 1 ') a mixture of 12.5 parts of magenta / green from Sicpa (OVI®) and 25 parts of the color HELICONE® HC Scarabeus from Wacker, and 1.5 parts of another color.
• 2) a mixture of 10% to 80% metal pigment color (metallic color gold and silver colors) and 20% to 90% liquid crystal pigment color (STEP®).
• 2 ') a mixture of 4 parts of gold color for the screen printing of Sicpa and 25 parts of the color HELICONE® HC Maple from Wacker.

In the exemplary embodiments described so far, the color mixtures or the layer sequences are each designed so that markings are introduced by the action of the laser radiation, which are visually recognizable without aids. The now with reference to the FIGS. 10 to 13 illustrated embodiments show variants of the invention with machine-detectable labels that are not recognizable to the human eye, or only with tools.

For explanation shows Fig. 10 a value document substrate 170, for example a banknote, on which a marking layer 172 of a color mixture of two mixture components 174 and 176 is applied. One of the mixture components 174 is transparent to the radiation of the infrared laser used subsequently to the marking, the other mixture component 176 absorbs the laser radiation. The two mixture components 174 and 176 are chosen so that they are not distinguishable in color in the visible spectral range for the eye and appear, for example, in the same shade of blue.

In region 178, the marking layer 172 has been irradiated with the marking laser with suitably selected laser parameters to destroy or alter the absorbing mixture component 176 by the action of the laser radiation. The mechanism of destruction or alteration of the IR-absorbing material upon exposure to the laser beam is not relevant to the present invention.

Since the two mixture components 174 and 176 do not differ visually, the lasered region 178 does not stand out from its surroundings with suitably selected mixture proportions with the naked eye. The marking layer 172 thus appears to the viewer as a homogeneous monochromatic layer, as in FIG Fig. 11 (a) Illustrated, which shows the visual appearance of a corresponding section of the value document in supervision.

Upon irradiation of the value document with infrared radiation, however, the lasered region 178 can be read out in reflection, since the intensity of the reflected IR radiation in the lasered region 178 is significantly lower because of the missing IR absorber than in its surroundings. This can be easily detected with an IR camera or a silicon detector become. FIG. 11 (b) shows by way of example the same section as Fig. 11 (a) when illuminated with an IR lamp, taken with an IR camera. The value document can thus be provided with visually invisible, but easy-to-read individualizations that require little space on the value document, and which do not significantly affect the value document design.

As in Fig. 11 (b) As shown, the individualizations can be embodied in particular in the form of barcodes or matrix codes. The latter are preferred in the value document area, as they allow to represent a high information content in a small area. Of course, the absorbent mixture component 176 may also be only partially removed with the marking laser to obtain different brightness levels in the reflected infrared image and to avoid visually recognizable information in the visible range.

As a color mixture for the marking layer, it is possible, for example, to use a blue which has the IR-transparent mixture component copper-phthalocyanine blue with the International Color Index Name * (CI) PB 15 or 15: 3 (pigment: Cu-II-phthalocyanine) and as IR absorbing mixture component Milori blue CIPB 27 (pigment: an iron cyanide compound having the formula Fe ₄ [Fe- (CN) ₆ ] ₃ × H ₂ O). Particularly good results can be achieved if the proportion of the IR-transparent mixture component is greater than that of the IR-absorbing component. For example, the color ratio of phthalocyanine blue and milori blue may be 70:30 or even 90:10.

Alternatively, as a color mixture, for example, a green can be used, which is used as the IR-transparent mixture component Phthalocyan C.I. P. G. 7 (pigment: chlorinated Cu-II-phthalocyanine green and as IR-absorbing compound component chromium oxide green (chromium III oxide hydrate).

For example, a gray can be obtained by using diaryl yellow C.I. P.Y 13, phthalocyanine blue C.I. P. B. 15 (α-modification) or 15: 3 (β-modification) and Naphtol AS-Red C.I. P.R. 146 (pigment: monoazo pigment with 2-hydroxy-3-naphthoic acid arylidene) as IR-transparent mixture components and carbon black C.I. P.BI. 7 or graphite can be obtained as IR-absorbing mixture component.

As marking lasers, for example, Nd: YAG lasers or Nd: YVO ₄ lasers, both with λ = 1.064 μm, can be used for the mixtures mentioned. With the marking laser for a vectors, so lines in the layer sequence can be written, which is especially for quick captions, as they are needed in the environment of a printing office, is advantageous. On the other hand, the marking laser can also be operated in a raster mode in which the laser beam scans the substrate surface and the laser power is selectively switched on at those raster points at which lasering is to take place. This variant is particularly advantageous for the illustration and labeling of maps or data pages of passports.

Fig. 12 shows a variant according to another embodiment of the invention. In the design of Fig. 12 For example, on the security substrate 180, there is a layer sequence 182 in which, above an IR-transparent layer 184 an IR-absorbing layer 186 is arranged, wherein the absorbing layer and the transparent layer in the visible spectral region appear to be the same color tone. The two layers can be used in particular with printing inks associated with Fig. 10 pigments are printed on the substrate 180.

By laser irradiation with an infrared laser, an identification 188 is introduced into the IR-absorbing layer 186, for example by chemical modification or destruction of the IR-absorbing pigments or ablation of the layer or pigments. However, the underlying IR transparent layer 184 is not changed by the laser radiation. Since the two layers are the same color shade in the visible spectral range, the layer sequence 182 appears to the viewer as a uniform colored surface even after laser marking. As described above, when the value document is irradiated with IR radiation, the marking can be read out on the basis of the lower reflectivity in the region 188.

Another variant of the invention is in Fig. 13 shown. In this embodiment, an IR absorbing layer 196 is deposited on a color matching substrate 190, such that a laser-engraved marking 198 does not visually appear. The tag 198 does, as in 10 to 12 , Only in the infrared spectral range by the lower reflectivity noticeable and can be read by machine.

Instead of visually visible pigments, upconversion pigments may also be used (e.g., UC2 from Honeywell, rare earth oxysulfide).

Instead of the infrared codes described, other markings which can not be visually recognized or can only be identified with auxiliary means can also be used. For example, a UV code may be included in an orange tagging layer 172 (FIG. Fig. 10 ), which contains disazopyrazolone orange CIPO 34 as UV-transparent mixture component and perinone orange CIPO 43 as UV-absorbing component. A UV laser with λ = 321 nm is used as the marking laser, the reading of the marking takes place via a measurement of the UV reflection of the value-document surface or of the fluorescence of PO43 after excitation with UV light.

In addition, it is also possible to use visually invisible luminescent paints that fluoresce or phosphoresce after excitation with UV light and thus become recognizable only by the aid of a UV excitation source. It is also possible to combine different luminescent substances with one another. Suitable luminescent substances are, above all, organic pigments but also many inorganic pigments.

Claims (71)

1. A value document, especially a banknote (10), having a sequence of layers into which visually and/or mechanically perceptible identifiers in the form of patterns, letters, numbers or images are introduced by the action of laser radiation, characterized in that the sequence of layers contains a marking layer (22) composed of an ink mixture containing optically variable color pigments and exhibiting a laser-radiation-absorbing mixture component (26) and a laser-radiation-transparent mixture component, the identifiers being visually and/ or mechanically perceptible due to an irreversible change in the optical properties of the ink mixture, effected by the action of the laser radiation.
2. The value document according to claim 1, characterized in that the introduced identifiers are visually perceptible without auxiliary means.
3. The value document according to claim 2, characterized in that the ink mixture contains optically variable liquid crystal pigments as the laser-radiation-transparent mixture component.
4. The value document according to claim 2 or 3, characterized in that the ink mixture contains a transparent intaglio ink as the laser-radiation-transparent mixture component.
5. The value document according to at least one of claims 2 to 4, characterized in that the ink mixture contains optically variable interference layer pigments as the absorbing mixture component.
6. The value document according to at least one of claims 1 to 5, characterized in that the ink mixture contains as the absorbing mixture component an absorbing ink component whose optical properties are irreversibly changeable by the action of the laser radiation.
7. The value document according to claim 6, characterized in that the absorbing ink component contains an intaglio ink, a metallic ink or metallic pigments, a luminescent ink or luminescent pigments, glossy pigments or a thermochromic ink.
8. The value document according at least one of the claims 1 to 7, characterized in that the ink mixture contains an ink component that coacts with the absorbing mixture component, and whose optical properties are irreversibly changeable by the absorption of the laser radiation by the absorbing mixture component, especially the temperature rise caused thereby.
9. The value document according to claim 8, characterized in that the coacting ink component contains an intaglio ink, a metallic ink or metallic pigments, a luminescent ink or luminescent pigments, glossy pigments or a thermochromic ink.
10. The value document according to claim 8 or 9, characterized in that the absorbing mixture component contains soot, graphite, TiO₂ or an infrared absorber.
11. The value document according to at least one of the claims 1 to 10, characterized in that the sequence of layers exhibits at least one laser-radiation-absorbing layer (26), which is disposed between the marking layer and the substrate (20) of the value document.
12. The value document according to at least one of claims 1 to 11, characterized in that the sequence of layers exhibits at least one laser-radiation-absorbing layer (26) and at least one laser-radiation-transparent layer, which are disposed between the marking layer and the substrate of the value document.
13. The value document according to claim 12, characterized in that a laser-radiation-transparent layer is disposed between the absorbing layer and the marking layer.
14. The value document according to claim 12 or 13, characterized in that a laser-radiation-transparent layer is disposed between the absorbing layer and the substrate (20) of the value document.
15. The value document according to at least one of claims 11 to 14, characterized in that the absorbing layer is structured to bear information.
16. The value document according to at least one of claims 11 to 15, characterized in that a laser-radiation-transparent layer is structured to bear information.
17. The value document according to claim 15 or 16, characterized in that the information-bearing structurings are at least partially produced with printing technology.
18. The value document according to at least one of claims 15 to 17, characterized in that the information-bearing structurings are at least partially produced by the action of the laser radiation, especially by a selective ablation of an absorbing layer.
19. The value document according to at least one of claims 1 to 18, characterized in that the sequence of layers contains, in addition to the marking layer, an additional layer composed of an ink mixture exhibiting a laser-radiation-absorbing mixture component and a laser-radiation-transparent mixture component, the additional ink mixture layer being disposed between the marking layer and the substrate of the value document.
20. The value document according to claim 19, characterized in that the additional ink mixture layer exhibits an ink mixture according to one of claims 2 to 10.
21. The value document according to claim 19 or 20, characterized in that the additional ink mixture layer is structured to bear information.
22. The value document according to at least one of claims 15 to 21, characterized in that the information-bearing structurings form at least part of the identifiers and are visually perceptible due to the irreversible change in the optical properties of the ink mixture.
23. A value document, especially a banknote (10), having a sequence of layers into which identifiers in the form of patterns, letters, numbers or images are introduced by the action of laser radiation, characterized in that the sequence of layers contains a marking layer (22) composed of an ink mixture exhibiting a laser-radiation-absorbing mixture component (26) and a laser-radiation-transparent mixture component, the identifiers, due to an irreversible change in the optical properties of the ink mixture, effected by the action of the laser radiation, being mechanically perceptible but not being visually perceptible, or at least not without auxiliary means.
24. The value document according to claim 23, characterized in that the introduced identifiers are perceptible in the infrared spectral range.
25. The value document according to claim 23, characterized in that the introduced identifiers are perceptible following irradiation with ultraviolet radiation.
26. The value document according to at least one of claims 23 to 25, characterized in that the absorbing mixture component and the transparent mixture component appear in the same tone in the visible spectral range.
27. The value document according to claim 26, characterized in that the ink mixture visually exhibits a hue that differs from black.
28. The value document according to at least one of claims 23 to 27, characterized in that the proportion of the transparent mixture component outweighs the proportion of the absorbing mixture component in the ink mixture.
29. The value document according claim 28, characterized in that the transparent mixture component in the ink mixture exhibits a proportion of 60% or more.
30. The value document according to claim 28 or 29, characterized in that the transparent mixture component in the ink mixture exhibits a proportion of 70% or more, preferably of 80% or more.
31. A value document, especially a banknote (10), having a sequence of layers into which visually perceptible identifiers in the form of patterns, letters, numbers or images are introduced by the action of laser radiation, the sequence of layers exhibiting at least one laser-radiation-absorbing layer, characterized in that the sequence of layers exhibits at least one laser-radiation-transparent layer in addition to the absorbing layer, at least one of the absorbing or transparent layers containing optically variable color pigments and the identifiers being visually perceptible due to a selective ablation of the absorbing layer, effected by the action of the laser radiation.
32. The value document according to claim 31, characterized in that the absorbing layer is structured to bear information.
33. The value document according to claim 31 or 32, characterized in that a laser-radiation-transparent layer is structured to bear information.
34. The value document according to claim 32 or 33, characterized in that the information-bearing structurings are at least partially produced with printing technology.
35. The value document according to at least one of claims 32 to 34, characterized in that the information-bearing structurings are at least partially produced by the action of the laser radiation, especially by a selective ablation of an absorbing layer.
36. The value document according to at least one of claims 31 to 35, characterized in that the optically variable color pigments are liquid crystal pigments or interference layer pigments.
37. A value document, especially a banknote (10), having a sequence of layers into which mechanically perceptible identifiers in the form of patterns, letters, numbers or images are introduced by the action of laser radiation, the sequence of layers exhibiting at least one laser-radiation-absorbing layer, characterized in that the sequence of layers exhibits at least one laser-radiation-transparent layer in addition to the absorbing layer, the absorbing layer and the transparent layer appearing in the same tone in the visible spectral range, and the identifiers, due to a selective change in the absorbing layer, effected by the action of the laser radiation, being mechanically perceptible but not being visually perceptible, or at least not without auxiliary means.
38. The value document according to claim 37, characterized in that the absorbing layer and the transparent layer visually exhibit a hue that differs from black.
39. The value document according to claim 37 or 38, characterized in that the transparent layer exhibits a greater thickness than the absorbing layer.
40. The value document according to at least one of claims 37 to 39, characterized in that the absorbing layer is disposed above the transparent layer.
41. A value document, especially a banknote (10), having a sequence of layers into which mechanically perceptible identifiers in the form of patterns, letters, numbers or images are introduced by the action of laser radiation, the sequence of layers exhibiting at least one laser-radiation-absorbing layer, characterized in that the sequence of layers and the underlying value document substrate (20) appear in the same tone in the visible spectral range, and the identifiers, due to a selective change in the absorbing layer, effected by the action of the laser radiation, being mechanically perceptible but not being visually perceptible, or at least not without auxiliary means.
42. The value document according to claim 41, characterized in that the absorbing layer and the underlying value document substrate visually exhibit a hue that differs from black.
43. The value document according to at least one of claims 37 to 42, characterized in that the absorbing layer is structured to bear information.
44. The value document according to at least one of claims 37 to 43, characterized in that a laser-radiation-transparent layer is structured to bear information.
45. The value document according to claim 43 or 44, characterized in that the information-bearing structurings are at least partially produced with printing technology.
46. The value document according to at least one of claims 37 to 45, characterized in that the information-bearing structurings are at least partially produced by the action of the laser radiation, especially by a selective ablation of an absorbing layer.
47. The value document according to at least one of claims 37 to 46, characterized in that the introduced identifiers are perceptible in the infrared spectral range.
48. The value document according to at least one of claims 37 to 46, characterized in that the introduced identifiers are perceptible following irradiation with ultraviolet radiation.
49. The value document according to at least one of claims 1 to 48, characterized in that the identifiers comprise an individualization mark, such as a sequential serial number, a symbol code, such as a bar or matrix code, or the like.
50. A security element for value documents, especially banknotes (10), having a sequence of layers into which visually and/ or mechanically perceptible identifiers in the form of patterns, letters, numbers or images are introduced by the action of laser radiation, characterized in that the sequence of layers contains a marking layer (22) composed of an ink mixture containing optically variable color pigments and exhibiting a laser-radiation-absorbing mixture component (26) and a laser-radiation-transparent mixture component, the identifiers being visually and/ or mechanically perceptible due to an irreversible change in the optical properties of the ink mixture, effected by the action of the laser radiation.
51. The security element according to claim 50, characterized in that the introduced identifiers are visually perceptible without auxiliary means, and the sequence of layers is formed according to one of claims 4 to 22 or 49.
52. A security element for value documents, especially banknotes (10), having a sequence of layers into which identifiers in the form of patterns, letters, numbers or images are introduced by the action of laser radiation, characterized in that the sequence of layers contains a marking layer (22) composed of an ink mixture exhibiting a laser-radiation-absorbing mixture component (26) and a laser-radiation-transparent mixture component, the identifiers, due to an irreversible change in the optical properties of the ink mixture, effected by the action of the laser radiation, being mechanically perceptible, but are not visually perceptible, or at least not without auxiliary means.
53. The security element according to claim 52, characterized in that the sequence of layers is formed according to one of claims 24 to 29 or 49.
54. A security element for value documents, especially banknotes (10), having a sequence of layers into which visually perceptible identifiers in the form of patterns, letters, numbers or images are introduced by the action of laser radiation, the sequence of layers exhibiting at least one laser-radiation-absorbing layer, characterized in that the sequence of layers exhibits at least one laser-radiation-transparent layer in addition to the absorbing layer, at least one of the absorbing or transparent layers containing optically variable color pigments and the identifiers being visually perceptible due to a selective ablation of the at least one absorbing layer, effected by the action of the laser radiation.
55. The security element according to claim 54, characterized in that the sequence of layers is formed according to one of claims 32 to 36 or 49.
56. A security element for value documents, especially banknotes (10), having a sequence of layers into which mechanically perceptible identifiers in the form of patterns, letters, numbers or images are introduced by the action of laser radiation, the sequence of layers exhibiting at least one laser-radiation-absorbing layer, characterized in that the sequence of layers exhibits at least one laser-radiation-transparent layer in addition to the absorbing layer, the absorbing layer and the transparent layer appearing in the same tone in the visible spectral range, and the identifiers, due to a selective change in the absorbing layer, effected by the action of the laser radiation, being mechanically perceptible but not being visually perceptible, or at least not without auxiliary means.
57. The security element according to claim 56, characterized in that the sequence of layers is formed according to one of claims 38 to 40 or 43 to 49.
58. A method for manufacturing a security element or a value document having a sequence of layers, in which

    - a predefined laser wavelength is chosen,

    - to a substrate (20) or to a layer of the sequence of layers is applied a marking layer (22) composed of an ink mixture containing optically variable color pigments and exhibiting a mixture component that absorbs the laser radiation of the predefined laser wavelength and a mixture component that is transparent to the laser radiation of the predefined laser wavelength, and

    - through impingement on the sequence of layers by laser radiation of the predefined laser wavelength, identifiers are introduced into the sequence of layers in the form of patterns, letters, numbers or images that are visually and/ or mechanically perceptible due to an irreversible change in the optical properties of the ink mixture, effected by the action of the laser radiation.
59. A method for manufacturing a security element or a value document having a sequence of layers, in which

    - a predefined laser wavelength is chosen,

    - to a substrate (20) or to a layer of the sequence of layers is applied a marking layer (22) composed of an ink mixture exhibiting a mixture component that absorbs the laser radiation of the predefined laser wavelength and a mixture component that is transparent to the laser radiation of the predefined laser wavelength, and

    - through impingement on the sequence of layers by laser radiation of the predefined laser wavelength, identifiers are introduced into the sequence of layers in the form of patterns, letters, numbers or images that, due to an irreversible change in the optical properties of the ink mixture, effected by the action of the laser radiation, are mechanically perceptible but are not visually perceptible, or at least not without auxiliary means.
60. The method according to claim 58 or 59, characterized in that at least one laser-radiation-absorbing layer (26) is applied, especially is imprinted, between the marking layer and the substrate (20) of the value document or security element.
61. The method according to claim 58 to 60, characterized in that at least one laser-radiation-absorbing layer and one laser-radiation-transparent layer is applied, especially is imprinted, between the marking layer and the substrate (20) of the value document or security element.
62. A method for manufacturing a security element or of a value document having a sequence of layers, in which

    - a predefined laser wavelength is chosen,

    - to a substrate (20) or to a layer of the sequence of layers are applied at least one layer that absorbs the laser radiation of the predefined laser wavelength and one layer that is transparent to the laser radiation of the predefined laser wavelength, at least one of the absorbing or transparent layers containing optically variable color pigments, and

    - through impingement on the sequence of layers by laser radiation of the predefined laser wavelength, identifiers are introduced into the sequence of layers in the form of patterns, letters, numbers or images that are visually perceptible due to a selective ablation of the absorbing layer, effected by the action of the laser radiation.
63. The method according to at least one of claims 60 to 62, characterized in that the absorbing layer is structured to bear information.
64. The method according to at least one of claims 60 to 63, characterized in that a laser-radiation-transparent layer is structured to bear information.
65. The method according to claim 63 or 64, characterized in that the information-bearing structurings are at least partially produced with printing technology.
66. The method according to at least one of claims 63 to 65, characterized in that the information-bearing structurings are at least partially produced by the action of the laser radiation, especially by a selective ablation of an absorbing layer.
67. A method for manufacturing a security element or a value document having a sequence of layers, in which

    - a predefined laser wavelength is chosen,

    - to a substrate (20) or to a layer of the sequence of layers are applied at least one layer that absorbs the laser radiation of the predefined laser wavelength and one layer that is transparent to the laser radiation of the predefined laser wavelength, the transparent and the absorbing layer appearing in the same tone in the visible spectral range, and

    - through impingement on the sequence of layers by laser radiation of the predefined laser wavelength, identifiers are introduced into the sequence of layers in the form of patterns, letters, numbers or images that, due to a selective change in the absorbing layer, effected by the action of the laser radiation, are mechanically perceptible but are not visually perceptible, or at least not without auxiliary means.
68. A method for manufacturing a value document having a sequence of layers, in which

    - a predefined laser wavelength is chosen,

    - to the value document substrate (20) is applied a sequence of layers that appears in the same tone in the visible spectral range and having at least one layer that absorbs the laser radiation of the predefined laser wavelength, and

    - through impingement on the sequence of layers by laser radiation of the predefined laser wavelength, identifiers are introduced into the sequence of layers in the form of patterns, letters, numbers or images that, due to a selective change in the absorbing layer, effected by the action of the laser radiation, are mechanically perceptible but are not visually perceptible, or at least not without auxiliary means.
69. The method according to at least one of claims 58 to 68, characterized in that an infrared laser in the wavelength range of 0.8 µm to 3 µm, especially a Nd:YAG laser or a Nd:YVO₄ laser, is used as the laser source.
70. The method according to claim 69, characterized in that vectors are inscribed in the sequence of layers with the infrared laser, the infrared laser being operated with a pulse frequency between 20 kHz and continuous wave, an output between 10 and 100 W and a transverse speed between 3 and 30 m/ s.
71. The method according to claim 69, characterized in that a dot grid is inscribed in the sequence of layers with the infrared laser, the infrared laser being operated with a pulse frequency between 20 kHz and 80 kHz, an output between 0.5 and 4 W and for a dot density between 250 and 4800 dpi.

Images