EP3823839B1 - Security element comprising a lenticular image - Google Patents

Description

The invention relates to a security element for securing security papers, value documents and other data carriers, with a lenticular image which contains a lenticular grid made up of a plurality of microlenses and a radiation-sensitive motif layer arranged at a distance from the lenticular grid, wherein the radiation-sensitive motif layer contains, at least in one motif region, a plurality of transparency regions produced by the action of radiation, in which the radiation-sensitive motif layer is removed.

Data storage media, such as valuables or identification documents, but also other valuable items, such as branded goods, are often provided with security elements for security purposes. These allow the authenticity of the data storage media to be verified and at the same time serve as protection against unauthorized reproduction.

Security elements with viewing angle-dependent effects play a special role in authenticity assurance, as these cannot be reproduced even with the most modern copying machines. The security elements are equipped with optically variable elements that give the viewer a different image impression at different viewing angles and, for example, show a different color or brightness impression and/or a different graphic motif depending on the viewing angle.

In this context, it is known to provide the data carriers with laser-engraved tilting images for security purposes. In this case, two or more different markings, such as a serial number and an expiration date, are displayed at different angles by an arrangement of cylindrical Lenses are laser engraved into the data carrier. The laser radiation creates a local blackening of the data carrier body, which makes the engraved markings visually visible. When viewed, depending on the viewing angle, only the marking engraved from this direction is visible, so that tilting the data carrier perpendicular to the axis of the cylindrical lenses creates an optically variable tilting effect.

In the case of tilting images, it is further desirable to increase the security against counterfeiting if the images visible from different directions have different colors.

There are several known methods for producing tilted images, but they all have certain disadvantages. Basically, the known methods can be differentiated according to whether the microimages in a motif layer are produced with or without the aid of the lens grid of the tilted image.

Without the aid of the lenticular grid, the microimages can be printed or embossed, for example. These manufacturing variants are generally very cost-effective, but it is generally not possible, particularly with the very thin layer structures that are important in security printing, to arrange the microimages in such a precise register with the lenticular grid that the different images always appear at the same angle, so that, for example, when looking at several banknotes with the same tilted image next to each other, all banknotes show the same image from a certain angle.

Other manufacturing processes use the lenticular grid to structure the microimages. Laser engraving processes are used in particular, in which an image is inscribed into a motif layer through the lenses of the lenticular screen using a laser. The motif layer is either exposed to laser radiation through a mask or a laser beam is scanned over the motif layer to inscribe a desired motif. In both process variants, the motif is inscribed under the lenses in focus and is therefore always perfectly registered to the lenses. It is also ensured that the inscribed motif will later be visible from exactly the direction from which it was exposed with the laser beam. The disadvantage, however, is that laser engraving processes are often difficult to implement on a large scale. For example, lasering millimeter-sized motifs using a mask or scanner in film production represents a major and costly technical challenge with the film widths and process speeds usual for security applications. This is particularly true if, in order to create two or more different motifs that are visible in different directions from two or more different directions, a different image must be lasered into the motif layer.

WO 2010/115235 A1 , WO 2014/127403 A1 and WO 2015/149939 A1 show various optically variable security elements. WO 2017/097430 A1 discloses the preamble of claim 1.

Proceeding from this, the invention is based on the object of specifying a security element of the type mentioned at the outset which has a visually attractive appearance and is easy to manufacture.

This object is achieved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

The invention includes a security element as defined in claim 1.

Compared to the conventionally often used vapor-deposited aluminum layers, a printed metal pigment layer offers the particular advantage of being easier to manufacture. This means that a metallization machine step can be completely eliminated, as the metal pigment layer can be printed together with the color sub-layer in one operation. In addition, the metal pigment layer also creates an advantageous metallic impression and also significantly increases the opacity of the colors of the color sub-layer. The inventors have found that the colors of the color sub-layer with a printed metal pigment layer as a background appear richer and more striking than when using an aluminum background layer, and that they also appear less darkened.

The aforementioned adaptation of the absorption properties of the color sub-layer and the printed metal pigment layer means that the two sub-layers can be removed together by exposure to radiation, in particular by laser treatment, due to the absorption properties being adapted to one another. The adaptation of the absorption properties can be particularly advantageously achieved by choosing the binding agent of the metal pigment layer and/or the color sub-layer or by adding absorbers that absorb at the wavelength of the ablation radiation. The absorbers can advantageously be visually transparent or at least only lead to a darkening of the metal pigment layer and/or the color sub-layer without changing their color tone.

The printed metal pigment layer is conveniently located behind the color sub-layer when viewed from the lens grid and therefore forms a background layer for the color sub-layer from the viewing direction. While the radiation-sensitive motif layer can in principle also have three or more sub-layers, in an advantageous design it is provided that the radiation-sensitive motif layer only consists of the two sub-layers mentioned, namely the color sub-layer and the metal sub-layer.

The printed metal pigment layer is particularly advantageously a printed silver ink, such as Lumogen OVD Ink 102 from BASF or SSF 014 Silver from Rotoflex.

The printed metal pigment layer advantageously forms an opacity-enhancing background for the color sublayer.

To adjust the absorption properties, the removal thresholds of the printed metal pigment layer and the color sub-layer for exposure to radiation are advantageously within 50%, preferably within 30%, particularly preferably within 20%. More precisely, the smaller of the two removal thresholds is within 50% (or 30% or 20%) of the larger removal threshold. If the color sub-layer requires a laser power density of at least L _F for removal and the metal sub-layer requires a laser power density of at least L _M , the above condition requires that min(L _F ,L _M ) is in the range from 0.5*max(L _F ,L _M ) to max(L _F ,L _M ) and in the preferred designs is in the range of 0.7*max(L _F ,L _M ) to max(L _F ,L _m ) or in the range of 0.8*max(L _F ,L _m ) to max(L _F ,L _M ).

In an advantageous embodiment, the absorption properties of the printed metal pigment layer and the color sub-layer in the near-infrared spectral range are matched to one another; in particular, the absorptions of the printed metal pigment layer and the color sub-layer for radiation exposure in the near-infrared spectral range are within 50%, preferably within 30%, particularly preferably within 20%. More precisely, the smaller of the two absorptions is within 50% (or 30% or 20%) of the larger absorption. If the absorption of the color sub-layer in the near-infrared is A _F and the absorption of the metal sub-layer is A _M , then min(A _F ,A _M ) is in the range from 0.5*max(A _F ,A _M ) to max(A _F ,A _M ), and in the preferred embodiments in the range from 0.7*max(A _F ,A _m ) to max(A _F ,A _M ) or in the range of 0.8* max(A _F ,A _M ) to max(A _F ,A _M ).

The printed metal pigment layer and/or the color sub-layer are advantageously mixed with an absorber additive that is adapted to the respective spectral range of the laser used, in particular with an absorber additive that is transparent in the visual spectral range. Alternatively, an absorber can be used that only darkens the metal pigment layer or the color sub-layer without changing its color tone. The absorber additive is preferably an infrared absorber additive or a laser absorber additive. The laser absorber additive is transparent in the visual spectral range but selectively absorbs a laser wavelength. The infrared absorber additive is absorbent in the IR range and optionally transparent in the visual range.

The color sub-layer is advantageously a printing layer, preferably with a color layer thickness of between 0.5 and 10 g/m ² , in particular between 1 and 2 g/m ² . The color sub-layer can be, for example, a layer of Midori blue, Heliogen green, or dioxazine violet, but also a non-ferrous metallic layer, such as a copper or gold layer. The printed metal pigment layer advantageously has a color layer thickness of between 0.5 and 10 g/m ² , in particular between 2.5 and 5 g/m ² .

• die Transparenzbereiche jeweils passergenau zu den Mikrolinsen des Linsenrasters angeordnet sind, und
• die strahlungssensitive Motivschicht außerhalb der durch Strahlungseinwirkung erzeugten Transparenzbereiche opak ist und in dem Motivbereich in Form eines ersten Motivs strukturiert ist, so dass das erste Motiv bei Betrachtung des Sicherheitselements aus einer ersten Betrachtungsrichtung durch das Linsenraster als erstes Erscheinungsbild sichtbar ist.

In a preferred more specific embodiment, it is further provided that the lenticular image shows at least two different appearances from different viewing directions, whereby

• the transparency areas are arranged in precise register with the microlenses of the lens grid, and
• the radiation-sensitive motif layer is opaque outside the transparency areas created by the action of radiation and is structured in the motif area in the form of a first motif, so that the first motif is visible as the first appearance when the security element is viewed from a first viewing direction through the lens grid.

In a preferred embodiment, the radiation-sensitive motif layer is laser-sensitive and is ablated in particular by laser radiation.

The refractive effect of the microlenses of the lens grid defines a focal plane, whereby the radiation-sensitive motif layer is advantageously arranged essentially in this focal plane. The motif layer must not lie exactly in the focal plane, but in some designs can lie up to half a focal length above or below the focal plane. Such a defocused arrangement of the motif layer can be particularly advantageous if a particularly low thickness of the security element is to be achieved or a particularly large area under the respective microlenses is to be made transparent. By arranging the motif layer outside the focal plane, the viewing angles from which the appearances are visible can also be influenced and in particular enlarged. A large viewing angle range is a particularly desirable product property of the security elements described.

In an advantageous embodiment, it is provided that the lens grid has or represents a one-dimensional arrangement of microlenses, in particular cylindrical lenses. It can also advantageously be provided that the lens grid has or represents a two-dimensional arrangement of microlenses, in particular spherical or aspherical lenses.

In the context of this description, microlenses are lenses whose size in at least one lateral direction is below the resolution limit of the naked eye. The microlenses can be cylindrical in particular, but the use of spherical or aspherical lenses is also possible. The latter preferably have a diameter between 5 µm and 300 µm, in particular between 10 µm and 50 µm, particularly preferably between 15 µm and 20 µm. Micro-cylindrical lenses preferably have a width between 5 µm and 300 µm, in particular between 10 µm and 50 µm, particularly preferably between 15 µm and 20 µm. The length of the micro-cylindrical lenses is arbitrary, it can For example, when used in security threads or transfer elements, they must also correspond to the total width of the thread or transfer element and be several millimeters or several centimeters.

In an advantageous embodiment, a second motif layer is arranged on the side of the radiation-sensitive motif layer facing away from the lenticular grid, which is structured in the form of a second motif, so that the second motif is visible as a second appearance when the security element is viewed from a second viewing direction through the lenticular grid and the transparent areas of the radiation-sensitive motif layer. The second motif layer can in particular be formed by a printed layer. The second motif layer can be formed over the entire surface, but can also only be present partially, and the security element can then reveal a background lying beneath the security element outside the second motif layer.

According to a further, likewise advantageous embodiment, one or more transparent layers are arranged on the side of the radiation-sensitive motif layer facing away from the lenticular grid, so that when the security element is viewed from a second viewing direction through the lenticular grid and the transparency areas of the radiation-sensitive motif layer, a background lying beneath the security element is visible as a second appearance.

The invention also includes a data carrier, in particular a value document, a security paper, an identity card, a branded article or the like, with a security element of the type described.

Such a data carrier can in particular contain a security element without a second motif layer, in which one or more transparent layers are arranged on the side of the radiation-sensitive motif layer facing away from the lenticular grid, as described above. It is further provided that the data carrier is provided in a partial area with a second motif layer that is structured in the form of a second motif. The security element is then arranged with the lenticular grid and the transparency areas above the second motif layer, so that the second motif is visible as a second appearance when the security element is viewed from a second viewing direction through the lenticular grid and the transparency areas of the radiation-sensitive motif layer. This makes it easy to produce data carriers with tilt images that show a general, generic motif (first motif) from a first viewing direction and an individualized motif (second motif) from a second viewing direction, as explained in more detail below.

The invention also includes a method for producing a security element as defined in claim 13.

• die Transparenzbereiche in der strahlungssensitiven Motivschicht passergenau zu den Mikrolinsen des Linsenrasters erzeugt werden, und
• die strahlungssensitive Motivschicht außerhalb der durch Strahlungseinwirkung erzeugten Transparenzbereiche opak und in Form eines ersten Motivs strukturiert ausgebildet wird, so dass das erste Motiv bei Betrachtung des Sicherheitselements aus einer ersten Betrachtungsrichtung durch das Linsenraster als erstes Erscheinungsbild sichtbar ist.

In a preferred more specific method, the lenticular image shows at least two different appearances from different viewing directions, wherein in the method

• the transparency areas in the radiation-sensitive motif layer are created in precise register with the microlenses of the lens grid, and
• the radiation-sensitive motif layer is opaque and structured in the form of a first motif outside the transparency areas created by the action of radiation, so that the first motif is visible as the first appearance when the security element is viewed from a first viewing direction through the lens grid.

In an advantageous process, the radiation-sensitive motif layer is exposed to laser radiation through the lens grid in order to create the transparent areas. The radiation-sensitive motif layer is advantageously ablated by the laser radiation.

• Frequenz: 10 - 100 kHz, bevorzugt 10-20 kHz
• Vorschub: 10-2500 mm/s, bevorzugt 100-300 mm/s
• Leistung: 0,1-100%, bevorzugt 70-85% bei einem 3,5 W-Laser

IR or NIR lasers (NIR: wavelength 0.78 - 3 µm) are advantageously used as laser sources, especially lasers in the IR-A range (wavelength 0.78 - 1.4 µm), for example at a wavelength of around 1064 nm, or green lasers, for example, whose radiation can be obtained by doubling the frequency of the NIR laser. For a green laser with a wavelength of 532 nm, but also for NIR lasers, the following parameters are suitable for ablation:

• Frequency: 10 - 100 kHz, preferably 10-20 kHz
• Feed: 10-2500 mm/s, preferably 100-300 mm/s
• Power: 0.1-100%, preferably 70-85% with a 3.5 W laser

A security element according to the invention can also contain more than two representations that are visible from more than two different viewing directions.

Further embodiments and advantages of the invention are explained below with reference to the figures, in which a true-to-scale and true-to-proportion reproduction was omitted in order to increase clarity.

Fig. 1

in schematischer Darstellung eine Banknote mit einem erfindungsgemäßen Sicherheitselement, das ein Kippbild mit zwei unterschiedlichen Erscheinungsbildern enthält,

Fig. 2

schematisch den Schichtaufbau des Sicherheitselements der Fig. 1 im Querschnitt,

Fig. 3

eine Aufsicht auf das Sicherheitselement der Fig. 2 ohne das Linsenraster und damit ohne die fokussierende Wirkung der Mikrolinsen,

Fig. 4 bis 7

die Herstellung des Sicherheitselements der Figuren 2 und 3, wobei (a) jeweils einen Zwischenschritt bei der Herstellung des Sicherheitselements und (b) das Erscheinungsbild des jeweiligen Zwischenprodukts in Aufsicht ohne das Linsenraster und damit ohne die fokussierende Wirkung der Mikrolinsen zeigt, und

Fig. 8

schematisch ein erfindungsgemäßes Sicherheitselement, bei dem auf die zweite Motivschicht verzichtet wurde.

They show:

Fig.1

in schematic representation a banknote with a security element according to the invention, which contains a tilting image with two different appearances,

Fig. 2

schematically the layer structure of the security element of the Fig.1 in cross section,

Fig.3

a supervision of the safety element of the Fig. 2 without the lens grid and thus without the focusing effect of the microlenses,

Fig. 4 to 7

the production of the security element of the Figures 2 and 3 , where (a) each shows an intermediate step in the manufacture of the security element and (b) the appearance of the respective intermediate product in plan view without the lens grid and thus without the focusing effect of the microlenses, and

Fig.8

schematically shows a security element according to the invention in which the second motif layer has been omitted.

The invention will now be explained using the example of security elements for banknotes. Figure 1 shows a schematic representation of a banknote 10 which is provided with a security element 12 according to the invention in the form of a glued-on transfer element. In the exemplary embodiment, the security element 12 represents a tilted image which, depending on the viewing direction, shows one of two different appearances 14A, 14B.

However, the invention is not limited to the transfer elements shown for illustration purposes on banknotes, but can also be used, for example, with security threads, wide security strips or cover films that are arranged over an opaque area, a window area or a continuous opening of a data carrier.

Returning to the presentation of the Fig.1 The two appearances in the example are represented by a two-colour display 14A of the value number "50" and a representation 14B of two colored rectangles, but it is understood that in practice the appearances typically represent more complex motifs, such as geometric patterns, portraits, coding, numbering, architectural, technical or natural motifs. When the banknote 10 is tilted 16 or the viewing direction is changed accordingly, the appearance of the security element 12 changes back and forth between the two appearances 14A, 14B.

While lenticular images with tilting images are known as such, the present invention provides a specially designed lenticular image in which the motifs shown are introduced into the motif layer of the lenticular image in a particularly simple and yet highly precise manner. In particular, neither a mask for exposure by means of a laser nor a fine scanning of the motif layer with a sharply focused laser beam or multiple laser exposure from different directions is required.

Figure 2 shows schematically the layer structure of the security element 12 according to the invention in cross section, wherein only the parts of the layer structure required for explaining the functional principle are shown. Figure 3 shows a top view of the security element 12 without the lens grid and thus without the focusing effect of the microlenses.

The Figures 2 and 3 show the finished security element 12, but for understanding the complex layer structure and the interaction of the individual layers, the detailed description of the manufacture of the security element with reference to the Figures 4 to 7 helpful.

The security element 12 contains a carrier substrate 22 in the form of a transparent plastic film, for example a polyethylene terephthalate (PET) film approximately 20 µm thick. The carrier substrate 22 has opposite first and second main surfaces, wherein the first main surface is provided with a lens grid 24 made up of a plurality of essentially cylindrical microlenses 26.

The thickness of the carrier substrate 22 and the curvature of the focusing lens surfaces of the microlenses 26 are coordinated with one another in such a way that the focal length of the microlenses 26 essentially corresponds to the thickness of the carrier substrate 22. The focal plane of the microlenses 26 then essentially coincides with the second, opposite main surface of the carrier substrate 22. As explained above, in some embodiments it may also be useful not to allow the focal plane to coincide with the second main surface of the carrier substrate, for example in order to produce particularly thin security elements.

A laser-sensitive motif layer 30 is arranged on the second main surface of the carrier substrate 22, which in the exemplary embodiment shown consists of two sub-layers, namely a color sub-layer 32 and a metal sub-layer 34 in the form of a printed metal pigment layer. Specifically, the color sub-layer 32 in the exemplary embodiment is formed by a printed Milori blue color layer and the metal pigment layer by a silver pigment layer, for example Lumogen OVD Ink 102 from BASF. The Milori blue color layer is printed, for example, with a basis weight of 1.5 g/m ² and the silver pigment color with a basis weight of 3.5 g/m ² .

The motif layer 30 also contains a large number of parallel, linear transparency areas in the form of linear recesses 40, which were created in the manner described in more detail below in precise registration with the microlenses 26 of the lens grid 24. The areas of the motif layer 30 between the recesses 40 form remaining material areas 42, which are also linear and in precise registration with the microlenses 26. In the exemplary embodiment, the linear recesses 40 and the linear material areas 42 have the same width, but in general the recesses and the material areas can also have different widths.

In the remaining material areas 42, the motif layer 30 is opaque and structured in the form of a first motif, in the example in the form of the value number "50". Specifically, the color sub-layer 32 represents the number "50" with a blue appearance, while the metal pigment layer 34 forms a well-contrasting, metallic silvery background for the value number "50". In the areas in which the metal pigment layer 34 is arranged above the color sub-layer 32, it increases the opacity of the color layer 32. The blue color of the Milori blue layer therefore appears rich and striking when viewed through the lens grid 24, but less darkened than with a conventional vapor-deposited aluminum background layer.

Due to the focusing effect of the microlenses 26, a viewer looks from a first viewing direction 50 at the remaining material areas 42 of the motif layer 30 and therefore perceives the blue value number "50" against a metallic silvery background as appearance 14A. The recesses 40 are not visible from the viewing direction 50. visible, so that the representation of the value number "50" appears to the viewer over the entire surface.

From a second viewing direction 52, the viewer looks at the recesses 40 in the motif layer 30 due to the focusing effect of the microlenses 26, so that the motif layer 30 is not visible from this viewing direction and the perceived appearance depends on the further design of the security element in the recesses 40. In the exemplary embodiment shown, on the side of the motif layer 30 facing away from the lens grid 24, there is a second motif layer in the form of a print layer 60, which is structured in the form of a second motif. A simple motif made up of two differently colored rectangles 62, 64 is shown as the second motif for illustration purposes, but it is understood that motifs of any complexity can be created here as desired.

When viewed from the second viewing direction 52, the viewer thus looks through the recesses of the first motif layer 30 onto the second motif layer 60 and therefore perceives the two colored rectangles 62, 64 as appearance 14B.

The security element 12 typically contains further layers 66, such as protective, covering or additional functional layers, which are not essential here and are therefore not described in detail. One or more of the further layers 66 can be opaque and form a background for the representation of the second motif layer 60, or the further layers can be transparent or translucent and, if the second motif layer does not cover the entire surface, allow a view through the security element 12 in some areas.

The second motif layer 60 can be full-surface, or, as in the embodiment of the Figures 2 and 3 , are only partially present and therefore allow a view of a background layer lying beneath the security element 12 in the areas outside the motif layer 60. The background layer can be formed, for example, by the substrate of the banknote 10 (in Fig. 2 indicated by dashed lines) or another data carrier on which the security element 12 is applied. The background layer can be single-colored or structured itself and, for example, contain information that can be recognized in the recesses 40 from the viewing direction 52. The security element 12 can also be present in a window area of a data carrier, so that the transparent areas lying outside the motif layer 60 represent see-through areas in the security element 12.

The production of the security element 12 will now be explained with reference to Figures 4 to 7, wherein the figure part (a) of the figures shows an intermediate step in the production of the security element and the figure part (b) shows the appearance of the respective intermediate product in plan view without the lens grid 24 and thus without the focusing effect of the microlenses 26.

With reference first to Fig.4 a carrier substrate 22 is provided in the form of a polyethylene terephthalate (PET) film approximately 20 µm thick and is provided on a first main surface, preferably by embossing, with a lens grid 24 made up of a plurality of essentially cylindrical microlenses 26 with a width b = 15 µm. Then, on the opposite second main surface of the carrier substrate 22, a layer of Milori blue with a basis weight of 1.5 g/m ² in the form of the Value number "50" printed in the desired original size. As shown in the top view of the Fig. 4(b) As shown, after this process step, the color partial layer 32 structured in the form of the value number "50" is present on the carrier substrate 22.

Subsequently, as a second partial layer, a metal pigment layer 34, specifically a silver pigment layer, is printed over the entire surface of the structured color partial layer 32, as shown in Fig. 5(a) It is important that the visual appearance of the metal pigment layer 34 differs significantly from that of the color sub-layer 32, so that a good contrast is created when viewed.

Instead of the Milori blue layer, a layer of heliogen green or dioxazine violet can be printed on, or a layer of a different colored metal, such as copper or gold, or a color-contrasting alloy can be applied. A multi-layer system, such as a thin film interference layer system with a reflector, dielectric spacer layer and absorber, which shows different colors depending on the direction, can also be considered. As can be seen in the top view of the Fig. 5(b) As shown, after this process step the motif layer 30 with the blue value "50" (reference number 32) is present in front of a metallic silvery background 34.

In the next process step, the surface of the motif layer 30 is exposed to laser radiation 70 over a large area from a predetermined direction through the lens grid 24, as shown in Fig. 6(a) The laser radiation 70 is focused linearly by the cylindrical microlenses 26 onto the motif layer 30 arranged on the second main surface of the carrier substrate 22 and ablates the metal partial layer 34 or in the area the value "50" both sub-layers 32, 34, so that linear recesses 40 are created in the motif layer 30. In order to be able to ablate the sub-layers cleanly, the color particles of the color sub-layer and the metal sub-layer should be easily transportable. The film does not lie on a substrate with the layers to be ablated, but is lasered "in suspension". As in the top view of the Fig. 6(b) As shown, after this process step, the motif layer 30 with the blue value "50" (reference number 32) and the metallic silvery background 34 is only present in the remaining material areas 42. Between the material areas 42, transparency areas 40 were created by the laser exposure, in which the intermediate product is transparent.

In a variant of the invention, the security element 12 can already be fed into the final production after this process step and, for example, be provided with a transparent protective layer on the second main surface, as described below in connection with Fig.8 described in more detail. In the invention variant of the present embodiment ( Fig. 7(a) ), on the other hand, a second motif layer 60 is printed onto the first motif layer 30 provided with recesses 40, which is structured in the form of a second motif with two colored rectangles 62, 64. After this process step, the security element now has Fig. 7(b) shown two structured motif layers 30 and 60, respectively, whose motifs are each viewed from the viewing directions 50, 52 ( Fig. 2 ) are visible. As far as can be seen when viewing, both motifs are also arranged in precise register with the microlenses 26 of the lens grid 24, although only a single laser exposure step was required to produce them.

At the Fig.8 In the variant shown, the second motif layer 60 was omitted and only transparent layers were used, for example a transparent protective or covering layer and/or a transparent adhesive layer is applied to the first motif layer 30. The security element 80 thus created shows, when viewed from a first viewing direction, the first motif already described above, formed by the first motif layer 30, and from a second viewing direction, provides a view of a background layer in the recesses 40 of the first motif layer 30.

In this way, it is particularly easy to produce data carriers with tilted images that show a general, generic motif from a first viewing direction and an individualized motif from a second viewing direction. For example, the security element 80 can be intended for use in identity documents 82 and its motif layer 30 can show a state coat of arms as the first, generic motif. Since the security element 80 itself only shows the generic motif "state coat of arms", it can be used unchanged for all similar identity documents 82.

A motif present in a data area 84 of the ID document 82, for example a passport photo of the holder, serves as the individualized motif. This individualized motif is different for each ID document 82. The security element 80 is then glued to the data area 84 with the cut-out motif layer 30, 40, so that the state coat of arms of the motif layer 30 is visible from the first viewing direction and the individualized motif of the data area 84 is visible from the second viewing direction.

List of reference symbols

10

Banknote

12

Security element

14A, 14B

Appearances

16

Tilt direction

22

Carrier substrate

24

Lenticular grid

26

Microlenses

30

laser-sensitive motif layer

32

Color sub-layer

34

Metal sublayer

40

Recesses

42

areas of material left standing

50.52

Viewing directions

60

second motif layer

62, 64

colored rectangles

66

additional layers

70

Laser radiation

80

Security element

82

Identification document

84

Data area

Claims (15)

1. Security element (12) for safeguarding security papers, valuable documents and other data carriers, comprising

   - a lens grid image containing a lens grid (24) composed of a plurality of microlenses (26), and a radiation-sensitive motif layer (30) arranged at a distance from the lens grid (24),

   - wherein the radiation-sensitive motif layer (30) contains, at least in a motif region, a multiplicity of transparency regions (40) which are generated by the action of radiation through the lens grid (24) and in which the radiation-sensitive motif layer is removed,

   - wherein the radiation-sensitive motif layer (30) has, at least in the motif region, a colour sublayer (32) and a metal sublayer (34),

   characterized in that

   - the metal sublayer (34) is a printed metal pigment layer, the absorption property of which is adapted to the absorption property of the colour sublayer (32).
2. Security element (12) according to Claim 1,
   characterized in that the printed metal pigment layer is a printed silver ink.
3. Security element (12) according to Claim 1 or 2,
   characterized in that the printed metal pigment layer forms an opacity-increasing background for the colour sublayer (32).
4. Security element (12) according to at least one of Claims 1 to 3, characterized in that for adapting the absorption properties, the removal thresholds of the printed metal pigment layer and the colour sublayer (32) for the action of radiation are within 50%, preferably within 30%, particularly preferably within 20%.
5. Security element (12) according to at least one of Claims 1 to 4, characterized in that the absorption properties of the printed metal pigment layer and the colour sublayer (32) in the visible and/or in the near-infrared spectral range are adapted to one another, in particular in that the absorption of the printed metal pigment layer and the colour sublayer (32) for the action of radiation in the visible and/or in the near-infrared spectral range are within 50%, preferably within 30%, particularly preferably within 20%.
6. Security element (12) according to at least one of Claims 1 to 5, characterized in that an absorber additive, preferably an infrared absorber additive or a laser absorber additive, is added to the printed metal pigment layer and/or the colour sublayer (32), wherein the absorber additive preferably appears transparent in the visual spectral range.
7. Security element (12) according to at least one of Claims 1 to 6, characterized in that

   the colour sublayer (32) is a printed layer, preferably having a colour layer thickness of between 0.5 and 10 g/m², in particular between 1 and 2 g/m²; and/or

   the printed metal pigment layer has a colour layer thickness of between 0.5 and 10 g/m², in particular between 2.5 and 5 g/m².
8. Security element (12) according to at least one of Claims 1 to 7, characterized in that the lens grid image shows at least two different appearances from different viewing directions, wherein

   - the transparency regions (40) are each arranged with register accuracy with respect to the microlenses of the lens grid, and

   - the radiation-sensitive motif layer (30) is opaque outside the transparency regions (40) generated by the action of radiation and is structured in the form of a first motif in the motif region, such that the first motif is visible as a first appearance when the security element (12) is viewed from a first viewing direction through the lens grid (24).
9. Security element (12) according to at least one of Claims 1 to 8, characterized in that the radiation-sensitive motif layer (30) is laser-sensitive; and/or the lens grid (24) has or constitutes a one-dimensional arrangement of microlenses, in particular cylindrical lenses, or in that the lens grid (24) has or constitutes a two-dimensional arrangement of microlenses, in particular spherical or aspherical lenses.
10. Security element (12) according to at least one of Claims 1 to 9, characterized in that a second motif layer (60) structured in the form of a second motif is arranged on the side of the radiation-sensitive motif layer (30) facing away from the lens grid (24), wherein preferably the second motif is visible as a second appearance when the security element (12) is viewed from a second viewing direction through the lens grid (24) and the transparency regions (40) of the radiation-sensitive motif layer; wherein preferably the second motif layer (60) is formed by a printed layer; and/or
    the second motif layer (60) is only partially present and, outside the second motif layer (60), the security element (12) reveals an underlying surface situated beneath the security element (12).
11. Security element (12) according to at least one of Claims 1 to 10, characterized in that one or more transparent layers are arranged on the side of the radiation-sensitive motif layer (30) facing away from the lens grid (24), such that an underlying surface situated beneath the security element (12) is visible as a second appearance when the security element (12) is viewed from a second viewing direction through the lens grid (24) and the transparency regions (40) of the radiation-sensitive motif layer (30).
12. Data carrier comprising a security element (12) according to at least one of Claims 1 to 11; in particular comprising a security element embodied according to Claim 11, wherein the data carrier is provided, in a subregion, with a second motif layer (60) structured in the form of a second motif, and in that the security element (12) is arranged with the lens grid (24) and the transparency regions over the second motif layer (60), such that the second motif is visible as a second appearance when the security element (12) is viewed from a second viewing direction through the lens grid (24) and the transparency regions (40) of the radiation-sensitive motif layer (30).
13. Method for producing a security element (12) comprising a lens grid image, in which method

    - provision is made of a carrier substrate and the latter is provided with a lens grid (24) composed of a plurality of microlenses, and with a radiation-sensitive motif layer (30) arranged at a distance from the lens grid (24),

    - wherein in the radiation-sensitive motif layer (30), at least in a motif region, a multiplicity of transparency regions are generated by the action of radiation through the lens grid (24), in which transparency regions the radiation-sensitive motif layer (30) is removed,

    - wherein the radiation-sensitive motif layer (30) is embodied, at least in a motif region, with a colour sublayer (32) and a metal sublayer (34),

    characterized in that

    - as the metal sublayer (34), a metal pigment layer is selected, the absorption property of which is adapted to the absorption property of the colour sublayer (32), and the selected metal pigment layer is printed as the metal sublayer (34) of the radiation-sensitive motif layer.
14. Method according to Claim 13, characterized in that the lens grid image shows at least two different appearances from different viewing directions, and in that in the method

    - the transparency regions (40) in the radiation-sensitive motif layer (30) are generated with register accuracy with respect to the microlenses of the lens grid, and

    - the radiation-sensitive motif layer (30) is embodied in opaque fashion outside the transparency regions (40) generated by the action of radiation and in structured fashion in the form of a first motif, such that the first motif is visible as a first appearance when the security element (12) is viewed from a first viewing direction through the lens grid (24).
15. Method according to Claim 13 or 14, characterized in that the radiation-sensitive motif layer (30) is exposed to laser radiation through the lens grid (24) in order to generate the transparency regions (40).

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