EP2723578B1 - Security element, method for the manufactur thereof, and use therof - Google Patents

Description

The invention relates to a security element for securing valuables with a covering ink layer and an introduced into the ink layer by the action of laser radiation marking in the form of patterns, characters or a coding.

Data carriers, such as valuables or identity documents, but also other valuables, such as branded goods, are often provided with security elements for the purpose of security, which permit verification of the authenticity of the data carrier and at the same time serve as protection against unauthorized reproduction. In this case, the security elements are provided, for example, with identifications produced by the action of laser radiation, which are known as laser inscription in personalized cards, for example. Even with banknotes or other value documents a visually recognizable individualization by laser exposure is known.

It is also known to provide security elements with machine-readable codes that enable an automatic authenticity check and, if appropriate, a more extensive sensory acquisition and processing of the documents equipped with them. For example, the document describes WO 2007/110155 A1 a data carrier with markings, which are preferably not visible in the visible spectral range, but can be detected by machine only in the near infrared with corresponding detectors.

In the known designs, either the visible marking or the machine-readable marking usually stands in the foreground, while the respective other aspect is perceived as disturbing. The machine-readable Markers are therefore often laminated or hidden optically, while the visually recognizable markings typically do not have sufficient machine-readable properties for secure detection.

document DE 10 2010 009 977 A1 discloses a method according to the preamble of claim 1.

Proceeding from this, the present invention seeks to provide a security element of the type mentioned above, on the one hand offers an attractive visual appearance and its identification on the other hand not only visually, but also mechanically detected safely.

This object is achieved by the security element having the features according to independent claim 6. A method for producing such a security element, a use and a method for the authenticity verification of valuables are given in the independent claims 1, 7 and 8, respectively. Further developments of the invention are the subject of the dependent claims.

A first aspect of the invention relates to a method according to claim 1.

The multilayer pigments preferably have a uniform color substantially independent of the viewing angle.

The multilayered pigments include, for example, a support and a support-applied layer containing a first component having a first infrared absorption and a second laser-ablatable component having a second infrared absorption, wherein the first infrared absorption is greater than the second infrared absorption is. The first infrared absorption is preferably more than 1.25 times, more preferably more than 2 times, and most preferably more than 5 times the size of the second infrared absorption.

The multilayer pigments are magnetic pigments which have a support and a layer applied to the support, wherein the support of Al ₂ O ₃ , Al ₂ O ₃ with up to 5 wt .-% TiO ₂ , SiO ₂ , SiO ₂ with up to 20 wt .-% silicon hydroxide, glass or borosilicate is selected and the layer of iron oxide, in particular gamma-iron oxide, which is doped with at least one alkaline earth metal oxide, preferably MgO, contains.

It is preferred that the magnetic pigments are magnetically aligned after the step of applying the color layer to the substrate in the form of a motif, in particular in the form of patterns, characters or an encoding.

The ink layer may preferably contain 75% to 100% of a multilayer pigment having a uniform color substantially independent of the viewing angle, and 25% to 0% of optically variable pigments besides a binder.

The laser application is carried out with a pulsed infrared laser in the wavelength range of 0.8 microns to 3 microns, preferably with short pulse durations of 25 ns or less, more preferably from 8 to 18 ns.

A second aspect of the invention relates to a security element according to claim 6.

A third aspect of the invention relates to a use of the security element according to the second aspect of the invention for the authenticity verification of valuables by detecting the infrared absorption of the security element in the area of the marking.

A fourth aspect of the invention relates to a method for authenticity verification of valuables equipped with the security element according to the second aspect of the invention, the method comprising a step of detecting the infrared absorption of the security element in the region of the marking.

The invention will be described below with reference to preferred embodiments.

According to the invention, a generic security element has a covering ink layer and an introduced into the ink layer by the action of laser radiation marking in the form of patterns, characters or a coding that is both visually and mechanically detectable. In this case, the color layer in the background area located outside the marking contains multilayer pigments which, for example, may have a uniform color substantially independent of the viewing angle. For example, the multilayered pigments may include an inner layer having a first infrared absorption and at least one inner layer covering outer layer having a second infrared absorption, wherein the first infrared absorption is greater than the second infrared absorption. Furthermore, in the area of the marking by the action of the laser radiation, the outer layer of the multilayer pigments is at least partially ablated or removed. The marking is brighter in the visible spectral range than the background range and thereby visually detectable, while the marking in the infrared spectral range has a greater absorption than the background area and is thus mechanically detectable.

The multilayer pigments described in the preceding paragraph comprise a support, in particular a support of mica, Al ₂ O ₃ , borosilicate or silicon dioxide, on which the at least one inner layer and the at least one outer layer are applied. Alternatively, the support itself may also constitute the inner layer of high infrared absorption and be surrounded by an outer layer of lower infrared absorption. The inner layer does not necessarily have to represent a complete envelope for the wearer. The multilayered pigments may, for example, also be formed by a carrier which is coated on its opposite major surfaces with the inner layer, respectively, without the inner layers being joined to one another at the edge of the carrier. Likewise, the inner layers of the opposed major surfaces may each be coated with the outer layer without interconnecting the opposing outer layers at the edge of the pigment.

The inner layer may, for example, be magnetic and based on Fe ₃ O ₄ , gamma iron oxide or maghemite, with alkaline earth oxide, in particular MgO, doped gamma iron oxide, Co-containing gamma iron oxide, Co-containing Fe ₃ O ₄ or CrO ₂ . If the carrier of the pigments themselves constitutes the inner layer of high infrared absorption, the carrier itself may be magnetic and be formed, for example, on the basis of Fe ₂ O ₃ .

The outer layer of the multi-layered pigment consists for example of MgO or TiO ₂ , wherein in principle also other materials with high infrared remission come into question, as used for example for solar heat reflection.

In the case of nonmagnetic multilayer pigments, the inner layer can advantageously also be formed on the basis of antimony-doped tin oxide. Also TiO ₂ / carbon black mixtures or Rußeinschlussschichten with high infrared absorption come into consideration for the inner layer.

The multilayer pigments used according to the invention may alternatively have a carrier with a coating applied above the carrier, wherein the coating has a first constituent with a first infrared absorption and a second component having second infrared absorption ablatable by the action of laser radiation, and the first infrared absorption is greater than the second infrared absorption. For example, the first component may be in the form of a matrix in which the second component is embedded, or vice versa.

The above-mentioned "first infrared absorption" is suitably more than 1.25 times, preferably more than 2 times, more preferably more than 5 times, and most preferably more than 8 times as large as the aforementioned "second infrared absorption". The term "infrared absorption" as used herein suitably refers to a wavelength range of 800 to 1400 nm, preferably 800 to 1200 nm, and more preferably 800 to 1050 nm.

In an advantageous variant of the invention are as multilayer pigments in the WO 2010/149266 A1 disclosed magnetic pigments used. The magnetic pigments in particular have a support and a layer applied to the support, wherein the support of Al ₂ O ₃ , Al ₂ O ₃ with up to 5 wt .-% TiO ₂ , SiO ₂ , SiO ₂ with up to 20 wt. -% silicon hydroxide, glass or borosilicate is selected and the layer gamma-iron oxide, which is doped with at least one alkaline earth metal oxide, preferably MgO, contains. The proportion of the alkaline earth metal is for example 0.01 to 2 wt .-%, in particular 0.1 to 1 wt .-%, based on the total pigment. Furthermore, the layer applied on the carrier may consist exclusively of the gamma-iron oxide doped with alkaline-earth metal oxide, in particular MgO. In addition, however, the gamma iron oxide may also contain other iron compounds, for example Fe ₃ O ₄ or alpha iron oxide. The last two compounds are in the gamma-iron oxide layer, individually or in combination, preferably in a proportion of at most 25 wt .-% based on the gamma-iron oxide. In addition, a dielectric layer may be arranged above the gamma-iron oxide-deposited layer on the carrier. The dielectric layer may for example be based on metal oxides or metal oxide hydrates or mixtures thereof, in particular oxides or hydrates of Ti, Zr, Zn, Sn, Ce, Si and Al, such as titanium dioxide, zirconium oxide, zinc oxide, tin oxide, cerium oxide, silicon dioxide or hydrates thereof ,

The magnetic pigments described above may advantageously be oriented magnetically in the form of a motif, in particular in the form of patterns, characters or an encoding. Such a motif resulting from a magnetic alignment may be independent of the laser-generated marking or interact with it. For example, the tag may form a static reference point for a dynamic motion effect of the magnetic motif. In the context of the invention, however, multilayer magnetic pigments can also be used without magnetic alignment of the pigments.

The multilayer pigments used according to the invention are preferably not optically variable, ie they preferably exhibit a uniform color substantially independent of the viewing angle. In particular, the pigments can show shiny metallic colors, in particular gold, copper or bronze tones. Such pigments are for example in the WO 2010/149266 A1 disclosed.

The effects according to the invention also occur even when the color layer, in addition to the multilayer pigments and a binder, contains not too large a proportion of optically variable pigments. Preferably, in addition to the binder, the color layer contains 75% to 100% of the described non-optically variable, multi-layered pigments and from 25% to 0% optically variable pigments.

In the method for producing the security element according to the first aspect of the invention, the laser application is carried out with a pulsed infrared laser in the wavelength range of 0.8 .mu.m to 3 .mu.m, preferably with short pulse durations of 25 ns or less, in particular from 8 to 18 ns.

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 erfindungsgemäßen Sicherheitselement,

Fig. 2

das Erscheinungsbild des Sicherheitselements von Fig. 1, in a) im sichtbaren Spektralbereich (VIS) und in b) im infraroten Spektralbereich (IR),

Fig. 3

in der linken Bildhälfte die Absorption einer relativ stark absorbierenden Farbschicht im sichtbaren Spektralbereich (VIS) und im infraroten Spektralbereich (IR), in der rechten Bildhälfte die Absorption der Farbschicht in den beiden Spektralbereichen nach Laserbeaufschlagung,

Fig. 4

in der linken Bildhälfte die Absorption einer schwach bis mäßig absorbierenden Farbschicht im sichtbaren Spektralbereich (VIS) und im infraroten Spektralbereich (IR), in der rechten Bildhälfte die Absorption der Farbschicht in den beiden Spektralbereichen nach Laserbeaufschlagung,

Fig. 5

in der linken Bildhälfte die Absorption einer erfindungsgemäßen Farbschicht im sichtbaren Spektralbereich (VIS) und im infraroten Spektralbereich (IR), in der rechten Bildhälfte die Absorption der Farbschicht in den beiden Spektralbereichen nach Laserbeaufschlagung,

Fig. 6

ein mehrschichtiges Pigment eines erfindungsgemäßen Sicherheitselements,

Fig. 7

schematisch die Abhängigkeit der Absorption A von der Belichtungsintensität I im sichtbaren Spektralbereich und im infraroten Spektralbereich bei der Laserbeaufschlagung der Farbschicht eines erfindungsgemäßen Sicherheitselements,

Fig. 8

ein zweischichtiges Pigment eines erfindungsgemäßen Sicherheitselements, und

Fig. 9

die gemessenen VIS/IR-Remissionen dreier erfindungsgemäßer Sicherheitselemente.

Show it:

Fig. 1

a schematic representation of a banknote with a security element according to the invention,

Fig. 2

the appearance of the security element of Fig. 1 , in a) in the visible spectral range (VIS) and in b) in the infrared spectral range (IR),

Fig. 3

in the left half of the picture the absorption of a relatively strongly absorbing color layer in the visible spectral range (VIS) and in the infrared spectral range (IR), in the right half the absorption of the color layer in the two spectral ranges after laser application,

Fig. 4

in the left half of the image the absorption of a weakly to moderately absorbing color layer in the visible spectral range (VIS) and in the infrared spectral range (IR), in the right half the absorption of the color layer in the two spectral ranges after laser application,

Fig. 5

in the left half of the picture the absorption of a color layer according to the invention in the visible spectral range (VIS) and in the infrared spectral range (IR), in the right half the absorption of the color layer in the two spectral ranges after laser application,

Fig. 6

a multi-layered pigment of a security element according to the invention,

Fig. 7

schematically the dependence of the absorption A on the exposure intensity I in the visible spectral range and in the infrared spectral range on laser exposure of the color layer of a security element according to the invention,

Fig. 8

a two-layered pigment of a security element according to the invention, and

Fig. 9

the measured VIS / IR remissions of three inventive security elements.

The invention will now be explained using the example of security elements for banknotes. FIG. 1 shows a schematic representation of a banknote 10 with a printed directly on the banknote paper security element 12th

The design and the visual impression of the security element 12 for a viewer 20 are in Fig. 2 (a) shown in more detail. The security element 12 contains a covering ink layer 14, which in the exemplary embodiment has a uniform, glittering and gold-colored appearance in a background region 16. In the ink layer 14, a label 18 is introduced by the action of laser radiation, which may be formed, for example in the form of the denomination "10" of the bill. In the visible spectral range, the mark 18 appears brighter than the golden background 16 and is therefore visually easily recognizable to the viewer 20.

The peculiarity of the security element 12 is particularly evident in the infrared spectral range. As in Fig. 2 (b) illustrated, the label 18 in the infrared spectral region has a significantly higher absorption than the background region 16 and is thereby easily and reliably detectable by machine, for example with an infrared sensor 22 sensitive at a wavelength of 850 nm.

As a result of the action of the laser radiation on the color layer 14, the absorption of the color layer 14 in the visible spectral range was reduced while it was increased in the infrared spectral range (see Fig. 5 ). This opposite change clearly differs from the usual behavior of printed layers in laser application, which is now first with reference to the FIGS. 3 and 4 should be explained.

A first effect typically occurs in the visible and infrared spectral regions relatively strongly absorbing ink layers. In the left half of Fig. 3 For this purpose, the absorption 30 of such a color layer in the visible spectral range (VIS) and its absorption 32 in the infrared spectral range (IR) are shown schematically. If such a color layer is irradiated with pulsed laser radiation of sufficient intensity, the color layer is locally destroyed or desorbed by the laser radiation so that the substrate or an underlying printing layer becomes visible. As a result, the absorption by the color layer in the lasered region generally decreases both in the visible spectral range 34 and in the infrared spectral range 36, resulting in a bright identification with reduced IR absorption, as in the right half of FIG Fig. 3 shown schematically. The size of the absorption before the laser application is shown with dashed lines for easier orientation.

Some colors also show a virtually unchanged absorption in the visible spectral range and a reduced absorption only in the infrared spectral range. Such colors are described, for example, in the document WO 2007/110155 A1 in connection with the local FIG. 3 described. They are well suited for generating machine-readable encodings whose existence is hidden in the visible spectral range.

The opposite effect typically occurs with color layers which absorb weakly to moderately in the visible and infrared spectral regions. In the left half of Fig. 4 For this purpose, the absorption 40 of such a color layer in the visible spectral range (VIS) and its absorption 42 in the infrared spectral range (IR) are shown schematically. If such, only slightly absorbing ink layer is irradiated with pulsed laser radiation of sufficient intensity, the ink layer is formed by the laser radiation locally decomposed and carbonated, so that there is a local blackening with significantly increased absorption. Since the carbonized material absorbs in a broadband manner, the change in absorbance in the visible spectral region 44 and in the infrared spectral region 46 is usually the same and a visually black high infrared absorption label is produced as in the right half of FIG Fig. 4 shown schematically.

By the laser exposure of such color layers so markings can be generated, which are both visually and mechanically detectable. However, blackening in the visible spectral range is often perceived by viewers as being less attractive. It also allows the designer little leeway, as it can always be produced only a black mark regardless of the initial color of the color layer.

In contrast to these two conventional effects is the behavior of the ink layer of the invention 14. In the left half of Fig. 5 schematically the absorption 50 of the color layer in the visible spectral range (VIS) and the absorption 52 in the infrared spectral range (IR) is shown. If a color layer 14 according to the invention is irradiated with pulsed laser radiation of suitable intensity, a brightening results locally, ie a lower absorption 54 in the visible spectral range, while at the same time a high absorption 56 is produced in the infrared spectral range, as in the right half of FIG Fig. 5 shown.

The visually visible, bright mark 18 is set in this way a machine-readable mark with very clear and thus easily detectable infrared contrast. In this way, a multi-level authenticity feature is created, on the one hand due to its light color and the partial preservation of the starting color of the ink layer 14 a Visually attractive appearance and on the other hand, both for the layman easy to identify, as well as mechanically proven to prove.

In order to achieve this unusual opposite behavior of the ink layer upon laser application, the ink layer 14 contains multi-layered pigments 60 having a uniform color independent of the viewing angle. Regarding Fig. 6 In the exemplary embodiment, the pigments 60 are gold-colored and comprise a carrier 62, for example made of Al ₂ O ₃ , which is coated with an inner layer 64, for example of gamma-iron oxide, and an outer layer 66, for example of MgO. The inner layer 64 has a higher, for example by a factor of 4, higher infrared absorption than the outer layer 66.

Without wishing to be bound by any specific explanation, the effect used for the invention, as currently understood, may be due to the laser radiation partially or even completely ablating or removing the outer MgO layer 66. This exposes the high IR absorbing inner layer 64 which, on the one hand, increases the overall infrared absorption of the pigment 60 and, on the other hand, mitigates, for example, gold gloss interfering effects, resulting in brightening in the visible spectral region.

At very high laser intensity, the inner layer 64 is destroyed in addition to the outer layer 66 and there is a reduced absorption both in the visible and in the infrared spectral range, as described above Fig. 3 already described. The inner and outer layers 64, 66 need not extend beyond the edge 68 of the pigment, the inner ones and outer layers may instead be deposited separately on the opposite major surfaces of the core 62.

The dependence of the absorption A on the exposure intensity I in the visible spectral range and in the infrared spectral range is in Fig. 7 shown schematically. While the absorption 70 decreases in the visible spectral range with increasing exposure intensity, the absorption 72 in the infrared spectral range according to the model described above due to the exposure of the inner layer 64 first increases, and then decrease with increasing destruction of the gamma-iron oxide layer, with a Exposure intensity 74 reaches a reduced absorption in both spectral ranges and thus a situation as in Fig. 3 is generated.

The intensity range which is preferred according to the invention, in which simultaneously a reduced absorption in the visible spectral range and an increased absorption in the infrared spectral range are obtainable, is indicated in the figure by the reference numeral 76. Of course, the absolute values of the preferred intensity range depend on the one hand on the pigment 60 used and on the other on the other laser parameters, in particular on the laser wavelength, the pulse duration, the repetition frequency and the speed with which the laser beam is passed over the ink layer during the marking. Suitable absolute values for the intensity to be used according to the invention can be determined in the case of the known basic course of the invention Fig. 7 however, can be determined experimentally by a person skilled in the art for a specific parameter set and a specific pigment 60 by a few experiments.

It has proved to be advantageous laser marking with a pulsed infrared laser in the wavelength range of 0.8 .mu.m to 3 .mu.m, in particular with a Nd: YAG laser. The pulse durations are preferably below 25 ns, in particular in the range from 8 to 18 ns.

The multilayer pigments used according to the invention may in particular be magnetic pigments which, in addition to the described effect, may be aligned by an external magnetic field in the form of a desired motif. For this purpose, the magnetic pigments are admixed, for example, with a UV-curing lacquer which is screen-printed with the contained magnetic pigments onto the target substrate. Then, the target substrate with the still-movable magnetic pigments is placed in a magnetic field of a desired field distribution and the pigments thereby aligned. The aligned magnetic pigments are now permanently fixed in their orientation by curing the UV varnish. Safety elements with magnetic motifs oriented in the form of a motif show the viewer an effective, three-dimensionally arunutendes appearance with a dynamic movement effect when tilting the security element, which is combined with the static marking described above.

However, magnetic pigments can also be used within the scope of the invention without special orientation of the pigments. The resulting ink layer 14 then has a uniform appearance except for the label 18, as in Fig. 2 (a) illustrated.

In addition to the in Fig. 6 Pigments shown with a core, an inner layer with high infrared absorption and an outer layer with lower infrared absorption are also possible two-layer pigment designs in which the core or carrier itself is the inner layer of high infrared absorption. FIG. 8 shows for illustration a two-layered pigment 80 with a core 82 of gamma-Fe ₂ O ₃ and a shell 84 of TiO ₂ . The core 82 represents an inner layer which has a significantly higher, for example a factor of 3, infrared absorption than the outer TiO ₂ shell 84.

According to the explanatory approach described above, the laser radiation in the intensity range 76 (FIG. Fig. 7 ) partially or even completely destroys the outer TiO ₂ shell 84 and exposes the highly IR-absorbing internal gamma-Fe ₂ O ₃ core 82. This increases the infrared absorption of the pigment 80, while at the same time attenuating the coloring interference effects and lightening the color impression in the visible spectral range.

In addition to the in Fig. 6 and in Fig. 8 The pigments shown are also the multilayer pigments in question, which in the WO 2010/149266 A1 are disclosed. These include, for example, an Al ₂ O _{3 support} and a MgO-doped layer of gamma-iron oxide applied above the support.

Fig. 9 shows the measured VIS / IR remissions of three inventive, laser-treated security elements. To produce the security elements, in each case so-called magnetic gold pigments ("magnetic gold", in Fig. 9 also referred to as "M-gold") with an Al ₂ O _{3 support} and a MgO-doped layer of gamma-iron oxide applied above the support. The proportion of alkaline earth metal is about 1 wt .-% based on the pigment. The three security elements were each treated with a different laser energy. In the Fig. 9 shown VIS / IR remissions of the three laser radiation treated security elements (curves 1, 2 and 3) were measured by means of a UV-VIS-NIR spectrometer "Lambda 900" from the company "Perkin-Elmer" recorded in a measuring range from 250 to 2400 nm (pixel density: 512 dpi). The laser treatment of the security elements was carried out in each case by means of a pulsed infrared laser (power: about 6 W, pulse duration: about 8 nanoseconds, pulse frequency: 35 to 40 kHz). Measurement curve 4 shows the reference "magnetic gold", ie the IR remissions of the non-laser-treated security element. The above in Fig. 5 described opposite effect of the absorption in the VIS range on the one hand, and the absorption in the IR range on the other hand, is clear from the curves 1, 2 and 3 clearly.

LIST OF REFERENCE NUMBERS

10

bill

12

security element

14

coat of paint

16

Background area

18

Labelling

20

observer

22

infrared sensor

30, 34

Absorption VIS

32, 36

Absorption IR

40, 44

Absorption VIS

42, 46

Absorption IR

50, 54

Absorption VIS

52, 56

Absorption IR

60

multi-layered pigment

62

substratum

64

inner layer

66

outer layer

68

pigment edge

70

Absorption in the visible spectral range

72

Absorption in the infrared spectral range

74

exposure intensity

80

two-layered pigment

82

substratum

84

shell

Claims (8)

1. A method for manufacturing a security element (12) for securing value objects (10) with an ink layer (14) having a marking area (18) in the form of patterns, characters or a coding that is incorporated by the action of laser radiation and is both visually and machine-detectable, and having a background area (16), comprising

   - applying an ink layer containing magnetic pigments to a substrate, and

   - incorporating a marking in the form of patterns, characters or a coding in the ink layer by the action of laser radiation,

   characterized in that the ink layer is opaque, and that the nature of the multilayer pigments and the intensity of the laser radiation are chosen such that the marking becomes lighter than the background area in the visible spectral range, thereby becoming visually detectable, and is provided with a greater absorption than the background area in the infrared spectral range, thereby becoming machine-detectable, wherein the multilayer pigments have a carrier and a layer applied to the carrier, wherein the carrier is chosen from Al₂O₃, Al₂O₃ with up to 5 weight-% TiO₂, SiO₂, SiO₂ with up to 20 weight-% silicon hydroxide, glass or borosilicate, and the layer contains gamma iron oxide doped with at least one alkaline earth metal oxide, wherein the laser application is carried out with a pulsed infrared laser in the wavelength range of 0.8 µm to 3 µm.
2. The method according to claim 1, wherein the multilayer pigments have a uniform color substantially independent of the viewing angle.
3. The method according to claim 1 or 2, wherein the magnetic pigments are magnetically aligned in the form of a motif, in particular in the form of patterns, characters or a coding, after the step of applying the ink layer to the substrate.
4. The method according to any of the claims 2 or 3, wherein the ink layer contains, besides a binding agent, the multilayer pigments with the uniform color substantially independent of the viewing angle in the amount of 75% to 100%, and optically variable pigments in the amount of 25% to 0%.
5. The method according to any of the claims 1 to 4, wherein the laser application is carried out with a pulsed infrared laser with short pulse durations of 25 ns or less, in particular from 8 to 18 ns.
6. A security element for securing value objects with an opaque ink layer having a marking area in the form of patterns, characters or a coding that is incorporated by the action of laser radiation and is both visually and machine-detectable, and a background area, wherein the security element can be obtained by the method according to any of the claims 1 to 5.
7. The use of the security element according to claim 6 for proving the authenticity of value objects by detecting the infrared absorption of the security element in the area of the marking.
8. A method for proving the authenticity of value objects equipped with the security element according to claim 6, wherein the method comprises a step of detecting the infrared absorption of the security element in the area of the marking.

Images