EP3980273B1 - Optically variable security element having a multi-colored reflective area - Google Patents

Description

The invention relates to an optically variable security element with a multi-colored reflective surface area for securing valuables. The invention also relates to a method for producing such a security element and to a data carrier equipped with such a security element.

Data carriers, such as valuables or identification documents, but also other valuables, such as branded items, are often provided with security elements for security purposes, which allow the authenticity of the data carrier to be checked and which also serve as protection against unauthorized reproduction.

The security elements can be designed, for example, in the form of a security thread embedded in a banknote, a cover film for a banknote with a hole, an applied security strip, a self-supporting transfer element or also in the form of a feature area printed directly on a document of value.

Security elements with a viewing angle-dependent or three-dimensional appearance play a special role in authenticity assurance, as these cannot be reproduced even with the most modern copying machines. For this purpose, 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 the prior art, optically variable effects are described, for example, movement effects, pump effects, depth effects or flip effects, which are realized with the help of holograms, microlenses or micromirrors.

From the publication WO 2015/078572 A1 a security element with magnetically alignable magnetic pigments is known. The publication EP 3 254 863 A1 relates to a security element with a printed color layer which, in addition to first pigments, also includes second pigments which are designed as magnetic pigments.

WO2012/176169 A1 describes a security thread with two optically variable areas arranged parallel and spaced apart from one another, in which flat pigments can each be aligned differently. EP1780040A2 discloses the preamble of claim 1.

Based on this, the invention is based on the object of further increasing the anti-counterfeit security and the visual attractiveness of generic optically variable security elements and, in particular, of providing optically variable security elements with two or more different appearances or effects in different colors. This task is solved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

To solve the stated problem, the invention contains an optically variable security element with a multi-colored reflective surface area, which can be used in particular to secure valuables.

The surface extent of the security element defines a plane and a z-axis perpendicular to it. According to the invention, the multicolored reflective surface area contains two optically variable reflection structures which are arranged at different height levels in the z direction and which produce a different color impression in reflection.

The higher reflection structure is formed by a relief structure provided with a color coating, said relief structure being formed by a micromirror arrangement with directed micromirrors, while the lower one Reflection structure is formed by a layer with platelet-shaped, reflective effect pigments, which are spatially aligned.

The two reflection structures overlap in an overlap area and the color coating of the higher reflection structure has at least one recess in the overlap area in which the lower reflection structure appears when the security element is viewed.

The overlap mentioned can be partial or complete, so one of the reflection structures can also completely cover the other reflection structure and the two reflection structures can even be designed to be congruent. The overlap mentioned refers to the relative lateral position of the reflection structures in the plane defined by the surface extent of the security element.

The terms “higher lying” and “lower lying” refer to viewing the security element from the positive z-direction. It is understood that in transparent areas or window areas of a data carrier, an applied security element can typically also be viewed from the back, i.e. the negative z-direction. The viewer then first looks at the layer with the platelet-shaped, reflective effect pigments, and in areas where this layer is translucent or has recesses, also at the relief structure provided with the color coating.

The platelet-shaped effect pigments are particularly advantageously formed as platelet-shaped magnetic pigments that can be aligned by a magnetic field, but they can also be platelet-shaped effect pigments which are formed by other fields, for example electric fields, can be aligned. This alignability in magnetic or other fields is a property of the effect pigments themselves. For example, due to their magnetic properties, magnetic pigments can be influenced by an external magnetic field and can also be aligned in a mobile state. In the finished security element, the effect pigments are already aligned and immobilized, so their alignment is fixed. The aligned effect pigments not only lie flat in the plane of the surface area, but are at least partially tilted against this plane and are therefore spatially aligned. The alignment is determined in particular by the angle of inclination and azimuth angle of the effect pigments. Due to the alignment with the help of an external field, the alignment of the individual ones is Effect pigments not freely selectable. Rather, the alignment of the effect pigments is not individual and is particularly dependent on the field. The field dependence requires, for example, that an alignment difference between neighboring effect pigments corresponds to the maximum possible field change at this distance, i.e. it is rather small. The maximum alignment difference between jointly aligned, neighboring effect pigments is less than 30 degrees for both angles, preferably less than 20 degrees.

Metallized pigments, in particular aluminum or silver-coated pigments, are preferably used as effect pigments. Pigments with a thin film coating, especially color-shifting pigments or aluminum pigments with a coloring coating produced by wet-chemical precipitation processes, can also be considered. In addition, reflective metal pigments, preferably aluminum pigments, with a translucent color coating can also be used, or pigments with a color coating formed by structural colors, in particular by nano- and binary structures.

The platelet-shaped effect pigments advantageously have a ratio of the largest to the smallest diameter (diameter-to-thickness ratio) that is more than 5:1, preferably more than 10:1, and particularly preferably more than 15:1 or even more than 50:1 amounts. The largest diameter of the platelet-shaped effect pigments is preferably between 5 µm and 35 µm, preferably between 15 µm and 25 µm or between 8 µm and 12 µm. Platelet-shaped effect pigments, for example, are those in the publications EP 1 689 586 B1 , WO 2010/069823 A1 and WO 2013/090983 A1 particles and pigments described in question.

The effect pigments are expediently present in a printing layer with a transparent or translucent binder. The binder can also be colored to create an additional color effect in the security element.

The relief structure of the higher-lying reflection structure is formed by a micromirror arrangement with directed micromirrors, in particular with flat mirrors, concave mirrors and/or Fresnel-like mirrors. The orientation (inclination angle and azimuth angle) of the micromirrors of the relief structure can be freely selected for each micromirror. The micromirrors are aligned independently of one another, in particular aligned by means of embossing. A maximum (or average) alignment difference between adjacent micromirrors is - for one or both angles - greater than 90 degrees. Adjacent micromirrors of the relief structure differ in their orientation, in particular in the inclination angle and in the azimuth angle. The lateral dimensions of the micromirrors are advantageously below 20 μm, preferably below 10 μm. In principle, however, other relief structures can also be used, In particular, embossed Fresnel lenses, concave mirrors, hologram structures, nanostructures or diffractive blazed gratings can be used.

The relief structure of the higher-lying reflection structure is advantageously formed in a transparent or translucent embossed lacquer layer, in particular embossed into this embossed lacquer layer. The embossing lacquer layer can also be colored in order to create an additional color effect in the security element.

In an advantageous variant of the invention, the color coating of the higher-lying reflection structure is designed as a regular or irregular grid with grid elements and grid spaces. The grid spaces represent the above-mentioned recesses. In this variant, the dimensions of the grid elements and/or grid spaces are below 140 μm, at least in one direction. Preferably, the dimensions of the grid elements and/or grid spaces are even below 140 μm in one or both lateral directions, preferably between 20 μm and 100 μm, in particular between 20 μm and 60 μm.

In an advantageous embodiment, the grid elements and grid spaces of the grid have the same shape and preferably also the same size. The grid elements and/or the grid spaces can in particular be formed by strip-shaped, square, triangular or other polygonal elements, but can also have irregular shapes. The grid itself can be regular, i.e. have a regular arrangement of grid elements and grid spaces, but can also be an irregular grid, for example a stochastic grid, in which the grid elements and / or grid spaces have irregular spacing and/or sizes and/or shapes. The area coverage of the grid by the grid elements is advantageously between 30% and 70%, preferably between 40% and 60%, in particular around 50%.

In a further variant of the invention, the color coating is advantageously applied alternatively or in addition to the grid mentioned in partial areas which have lateral dimensions of more than 140 µm, and/or the color coating is produced with recesses which have lateral dimensions of more than 140 µm. In the first-mentioned case, the surface areas surrounding the applied partial areas represent the above-mentioned recesses in the color coating. Preferably, the lateral dimensions of at least one partial area and/or at least one recess are more than 250 μm, preferably more than 500 μm and in particular more than 1 mm.

The color coating of the relief structure mentioned is formed in an advantageous design by translucent colors. Metallizations, for example made of aluminum, silver or an alloy, such as copper and aluminum, are also possible, as are thin-film structures, in particular color-shifting thin-film structures, gold-blue or silicon-aluminum thin films. The color coating can also be formed by translucent colors with a backed metallic mirror coating, for example made of aluminum. The color coating can represent a translucent image made up of several translucent colors, which is backed with a mirror coating, for example made of aluminum. Luminescent colors, in particular fluorescent colors with a metallic mirror coating, can also be considered as color coatings. The color coating can also be done using structural colors, especially nano and binary structures. be formed, which are embossed on or into the micromirrors of a micromirror arrangement. Finally, nanoparticle colors can also be considered as color coatings, such as gold-blue particles, various effect pigments, color-shifting pigments or super silver.

The different height levels in which the two reflection structures are arranged advantageously have a distance in the z direction between 5 µm and 100 µm, preferably between 10 µm and 50 µm. The small vertical distance between the two reflection structures is not noticeable when looking at the security element. The height level of a relief structure is given by the base area of the relief structure, for example a micro-mirror embossing. Analogously, the height level of aligned effect pigments is given by the middle position of the pigments tilted against the plane of the surface area. However, the exact definition of the height level is usually not important, since different height levels can be easily achieved, for example, by having the two reflection structures on opposite sides of a carrier film, or by having the two reflection structures one above the other on the same side of a carrier film .

The two reflection structures of the reflective surface area provide a color change together with a motif change depending on the viewing angle. The motifs of the two reflection structures can differ in particular in terms of shape (e.g. head, apple or tail), movement (static to moving or moving to static, with linear, rotating and/or pumping movement) and/or dimensionality (2D to 3D, or different three-dimensional with positively or negatively curved Appearance or floating in front of or behind a plane) of the motif.

In an advantageous embodiment, it is provided that the higher-lying reflection structure generates a first motif with a first color impression that is visible from a first viewing angle range and the lower-lying reflection structure generates a second motif with a second, different color impression that is visible from a second viewing angle range is, wherein the first and second viewing angle ranges do not overlap. When tilted, the security element then shows a binary color and effect change without an overlap area. The two viewing angle ranges can be adjacent to one another or only be separated by an angular distance of a few degrees, so that the associated image impressions change almost seamlessly for the viewer.

The higher-lying reflection structure can also generate a first movement motif with a first color impression and the lower-lying reflection structure can generate a second movement motif with a second, different color impression, with the first and second movement motifs moving offset from one another or moving against one another when the security element is tilted crossing in a crossing position in which both movement motifs are visible.

The two reflection structures can also generate motifs or movement motifs that are simultaneously visible in the same surface area, that is to say have at least partially overlapping viewing angle areas. Since the vertical distance between the two reflection structures is very small and is well below the resolution limit of the naked eye, they appear the appearances generated by the two reflection structures are present for a viewer at the same time in the same place.

• Ein binärer Motivflip zwischen gewölbten und/oder dreidimensional erscheinenden Bildmotiven mit binärem Farbwechsel. Ein erster Betrachtungswinkelbereich erstreckt sich beispielsweise von +5° bis +20° bezogen auf eine Flächennormale des Sicherheitselements, ein zweiter Betrachtungswinkelbereich von -5° bis -20°. Das erste und zweite Motiv können auch identisch sein, so dass sich ein reiner binärer Farbwechsel ergibt.
• Pump- oder Laufeffekte mit unterschiedlichen Farben, die sich örtlich kreuzen, beispielsweise entgegengesetzt laufen. Ein Betrachtungswinkelbereich für das erste Bewegungsmotiv erstreckt sich beispielsweise von -20° bis +20°, ein Betrachtungswinkelbereich für das zweite, gegenläufige Bewegungsmotiv umgekehrt von +20° bis -20°. Bei versetzt laufenden Bewegungsmotiven läuft ein Motiv beispielsweise von -20° bis +10°, das andere Motiv von -10° bis +20°.
• Ein binärer Motivflip, bei dem die gewölbten und/ oder dreidimensional erscheinenden verschiedenfarbigen Bildmotive ineinander liegen und/oder einander überschneiden. Beim Kippen findet insbesondere ein gleichzeitiger Farbtausch des inneren und des äußeren Motivs bzw. der überschneidenden Motivteile statt.

The following examples of variants have proven to be particularly visually attractive:

• A binary motif flip between curved and/or three-dimensional image motifs with a binary color change. A first viewing angle range extends, for example, from +5° to +20° based on a surface normal of the security element, a second viewing angle range from -5° to -20°. The first and second motifs can also be identical, resulting in a purely binary color change.
• Pumping or running effects with different colors that cross each other locally, for example running in opposite directions. A viewing angle range for the first movement motif extends, for example, from -20° to +20°, and a viewing angle range for the second, opposing movement motif extends from +20° to -20°. For example, with staggered movement motifs, one motif runs from -20° to +10°, the other motif from -10° to +20°.
• A binary motif flip in which the curved and/or three-dimensionally appearing different colored image motifs lie within one another and/or overlap one another. When tilting, there is a simultaneous color change of the inner and outer motif or the overlapping parts of the motif.

In a possible further development, a translucent color layer or an image made up of several translucent colors can be present between the two reflection structures in order to create an additional color effect in the security element. The translucent colors do not have to be applied directly on/above the reflective effect pigments, Rather, a translucent color can be applied anywhere between the two reflection structures. In other designs, a translucent color can also be mixed into another layer, for example by using a colored UV varnish for the embossing varnish layer mentioned, a colored film or a colored binder for the printing layer of the effect pigments.

The security element described can also be equipped with colorless or colored negative markings. For this purpose, it can be provided in particular that the overlap area contains partial areas with a negative marking, in which the color coating of the higher-lying reflection structure and the effect pigments of the deeper-lying reflection structure are left out.

If the effect pigments are present in a print layer, the entire print layer can be left out in areas to create a negative mark. Alternatively, the printing layer can also have areas in which only the binder is present, but the effect pigments have been removed, for example by laser exposure, or their visual effect has been deactivated.

• ein Träger bereitgestellt wird, dessen Flächenausdehnung eine Ebene und eine darauf senkrecht stehende z-Achse definiert,
• der Träger mit einem mehrfarbigen reflektiven Flächenbereich versehen wird, der mit zwei optisch variablen Reflexionsstrukturen ausgebildet wird, die in z-Richtung in unterschiedlichen Höhenstufen angeordnet werden, und die in Reflexion einen unterschiedlichen Farbeindruck erzeugen,
• die höher liegende Reflexionsstruktur durch eine mit einer Farbbeschichtung versehene Reliefstruktur gebildet wird,
• die tiefer liegende Reflexionsstruktur durch eine Schicht mit plättchenförmigen, reflektierenden Effektpigmenten gebildet wird, welche räumlich ausgerichtet werden, und
• die beiden Reflexionsstrukturen in einem Überlappungsbereich überlappend ausgebildet werden und die Farbbeschichtung der höher liegenden Reflexionsstruktur in dem Überlappungsbereich mit zumindest einer Aussparung ausgebildet wird, in der bei Betrachtung des Sicherheitselements die tiefer liegende Reflexionsstruktur in Erscheinung tritt, wobei die Reliefstruktur der höher liegenden Reflexionsstruktur durch eine Mikrospiegelanordnung mit gerichteten Mikrospiegeln gebildet wird.

The invention also contains a data carrier with an optically variable security element of the type described. In an advantageous embodiment, the data carrier contains a carrier with opposite main surfaces, on which one of the two optically variable reflection structures is arranged. The carrier is transparent in the overlap area or contains a transparent viewing window. For example, the support may be formed by a transparent polymer substrate, or by a paper substrate or hybrid substrate with a transparent window area. Alternatively, both optically variable reflection structures can also be arranged one above the other on a main surface of a carrier. Finally, the invention also contains a method for producing an optically variable security element, preferably a security element of the type described in more detail above, in which

• a carrier is provided, the surface extent of which defines a plane and a z-axis perpendicular thereto,
• the carrier is provided with a multi-colored reflective surface area, which is formed with two optically variable reflection structures which are arranged at different height levels in the z-direction and which produce a different color impression in reflection,
• the higher reflection structure is formed by a relief structure provided with a color coating,
• the deeper reflection structure is formed by a layer with platelet-shaped, reflective effect pigments, which are spatially aligned, and
• the two reflection structures are designed to overlap in an overlap area and the color coating of the higher reflection structure is formed in the overlap area with at least one recess in which the lower reflection structure appears when the security element is viewed, the relief structure of the higher reflection structure being formed by a micromirror arrangement is formed with directed micromirrors.

To form the deeper reflection structure, a printing ink with a binder and effect pigments that can be aligned magnetically or by other fields is advantageously applied. The effect pigments are aligned with an external field, in particular an external magnetic field, while the binder is still in the liquid state, in order to achieve the desired spatial alignment and the binder is solidified in order to permanently fix the alignment of the effect pigments. Solidifying the printing ink may include an active curing step, for example by heating or irradiation. The printing ink can optionally additionally comprise volatile components, but is preferably (substantially) free of volatile components.

To form the higher-lying reflection structure, an embossing lacquer layer is advantageously applied to a carrier film, embossed with the desired micromirror relief structure and then provided with the color coating in areas. A further lacquer coating is expediently applied to the embossed and coated embossed lacquer layer, the refractive index of which does not deviate by more than 0.25 from the refractive index of the embossed lacquer layer. In an advantageous method variant, the layer sequence produced in this way is applied at least partially overlapping to the printing layer with the effect pigments or to a target substrate. After application, the carrier film used for production can be removed or, for example in the case of a thin, transparent carrier film, can also remain in the security element.

Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, which are shown to scale. and proportionate reproduction was omitted in order to increase clarity.

Fig. 1

eine schematische Darstellung einer Banknote mit einem erfindungsgemäßen optisch variablen Sicherheitselement,

Fig. 2

schematisch einen Ausschnitt des Sicherheitselements der Fig. 1 im Querschnitt,

Fig. 3

in (a) bis (d) einige konkrete vorteilhafte Ausgestaltungen des Rasters der Farbbeschichtung der Mikrospiegelprägung in Aufsicht,

Fig. 4

als weiteres Ausführungsbeispiel der Erfindung eine Abwandlung der Ausgestaltung der Fig. 2,

Fig. 5

eine weitere Variante eines erfindungsgemäßen Sicherheitselements im Querschnitt, und

Fig. 6

in (a) bis (c) einige vorteilhafte Varianten von erfindungsgemäßen Datenträgern mit unterschiedlicher Schichtenfolge.

Show it:

Fig. 1

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

Fig. 2

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

Fig. 3

in (a) to (d) some concrete advantageous embodiments of the grid of the color coating of the micro-mirror embossing in top view,

Fig. 4

as a further exemplary embodiment of the invention, a modification of the design of Fig. 2 ,

Fig. 5

a further variant of a security element according to the invention in cross section, and

Fig. 6

in (a) to (c) some advantageous variants of data carriers according to the invention with different layer sequences.

The invention will now be explained using the example of security elements for banknotes. Figure 1 shows a schematic representation of a banknote 10 with an optically variable security element 12 according to the invention.

The security element 12 simultaneously shows two security features with different visual appearance and movement behavior in the same area. As in detail section 20 of the Fig. 1 Shown schematically, a first security feature 14 of the security element 12 has a metallic, three-dimensional appearance in which a row of larger rings 22 appears to float above a row of corresponding smaller rings 24. When the security element 12 is tilted, the larger and smaller rings 22, 24 move against each other for the viewer and thus create a striking three-dimensional movement feature.

At the same time, in the same surface area of the security element 12, a second security feature 16 can be seen, which is designed in the form of a color-shifting zigzag pattern 26. The lines of the zigzag pattern 26 show an outwardly curved three-dimensional appearance, and the color impression of the pattern 26 changes depending on the viewing angle from green when viewed vertically to blue when viewed at an angle.

The special structure of optically variable security elements according to the invention is now based on the design of Fig. 2 explained in more detail, which shows a section of the security element 12 Fig. 1 shown schematically in cross section.

The security element 12 contains a flat carrier 18, the surface extent of which defines an xy plane and a z-axis perpendicular thereto. In the exemplary embodiment, the carrier 18 represents the polymer or paper substrate of the banknote 10.

To produce the second security feature 16, the security element 12 contains a printing layer 30 with color-shifting, platelet-shaped magnetic pigments 32 that are magnetically aligned in the form of the bulging zigzag pattern 26. For this purpose, a printing layer 30 with magnetically alignable magnetic pigments 32 was printed onto the carrier 18, and The magnetic pigments 32 were aligned in the form of the desired motif while the binder 34 was still wet using an external magnetic field. Then the binder 34 was solidified, for example by UV exposure, in order to permanently fix the alignment of the magnetic pigments 32. The magnetic pigments with a color-shifting effect can, for example, be magnetic interference pigments, as described in the EP 1 366 380 A2 and are offered by Sicpa Holding SA, for example, under the names OVMI Gold/Green 5 SK 1001 S, OVMI Green/Blue 5 SK 5001 S and OVMI Magenta/Green 5 SK 3001 S.

To produce the first security feature 14, an embossing layer 40 is arranged above the print layer 30, which includes an embossing lacquer layer 42 with a micromirror embossing 44. The micromirror embossing 44 is provided with a color coating 46, for example a metal layer, which is only present in certain areas and which reveals the print layer 30 in its recesses 54. The micromirror embossing 44 is formed from a large number of micromirrors inclined towards the xy plane and having a typical edge length of approximately 10 μm. The local angles of inclination of the micromirrors are chosen so that the relief structure formed by the micromirrors together with the color coating 46 has a desired optical appearance, for example the representation of the two rows of rings 22, 24 lying one inside the other Fig. 1 generated.

To produce the embossing layer 40, for example, an embossing lacquer layer 42 can be applied to a carrier film, embossed with the desired micromirror relief structure 44 and then provided with the color coating 46 in areas. The coated embossing lacquer layer 44, 46 is then provided with a lacquer coating 48, the refractive index of which essentially corresponds to the refractive index of the embossing lacquer layer 42, and the layer sequence produced in this way is finally applied to the printing layer 30 in an at least partially overlapping manner. The lacquer coating 48 itself can have adhesive properties or an additional adhesive layer can be used. After application, the carrier film used in production can be removed from the embossing lacquer layer or, for example in the case of a thin, transparent carrier film, can also remain on the banknote.

After such a superposition of the printing layer 30 and the embossing layer 40, the coated micromirror embossing 44, 46 of the embossing layer 40 forms a higher-lying reflection structure in the security element 12, while the spatially aligned magnetic pigments 32 of the printing layer 30 form a deeper-lying reflection structure. Together, the layers 30, 40 form the multicolored reflective surface area of the security element 12.

What is important with the deeper reflection structure is that the platelet-shaped magnetic pigments 32 do not just lie flat in the plane of the printing layer 30 due to the magnetic alignment, but are locally tilted to different degrees against this plane and are therefore spatially aligned. In this way, the magnetic pigments 32 reflect to different degrees in different spatial directions and thus create the special, for example, a three-dimensional and/or dynamic appearance of the zigzag pattern 26.

What is important in the higher reflection structure is that the color coating 46 is provided with recesses 54 in order to enable a viewer 56 to see the underlying magnetic pigments 32 in some areas despite the continuous micromirror embossing 44.

Specifically, the color coating 46 is in the design of Fig. 2 in the form of a regular grid 50 made up of grid elements 52 and grid spaces 54. The grid elements 52 and grid spaces 54 form, for example, a checkerboard pattern in which each field, i.e. each grid element 52 and each grid space 54, has a dimension of 100 µm x 100 µm. Since the individual micromirrors of the micromirror embossing 44 are generally significantly smaller, for example having an edge length of only 10 μm, the grid 50 of the color coating 46 falls differently than in the simplified schematic representation Fig. 2 , generally not related to the grid of micromirrors.

While the reflective effect of the color coating 46 dominates in the area of the grid elements 52, the micromirrors of the micromirror embossing 44 in the grid spaces 54 have no optical effect due to the lack of refractive index difference between the lacquer layers 42, 48, so that the viewer 56 can see the magnetic pigments 32 of the print layer there 30 looks. In this way, both security features 14, 16 are visible to the viewer in the same surface area of the security element 12. Since the thicknesses of the printing layer 30 and the embossing layer 40 are in the range of a few micrometers or a few tens of micrometers, it is not apparent to the viewer 56 that the two optically variable reflection structures are actually arranged at different height levels in the z direction - rather, they appear to be present in the same place at the same time despite their different visual appearance.

In the exemplary embodiment, the grid elements 52 and the grid spaces 54 each have the same dimensions, so that the area coverage of the grid is 50%. However, depending on the desired relative brightness of the two appearances and the reflection properties of the color coating 46 and the magnetic pigments 32, other surface coverages of the grid 50 may also be possible. In principle, the area coverage of the grid with grid elements 52 is preferably between 30% and 70%, in particular between 40% and 60%.

Is the security element 12 the Fig. 1 and 2 arranged in a transparent area or a window area of the banknote 10, it can also be viewed from the back. The viewer 56 then first looks at the print layer 30 with the aligned magnetic pigments 32, so that the security feature 16 in the form of the color-shifting zigzag pattern 26 can also be clearly seen from the back. The first security feature 14 can also be seen, but appears weaker from the back, since the viewer also looks through the binder 34 of the printing layer 30 in the areas without magnetic pigments 32. The metallic, three-dimensional appearance of the micromirror embossing 44 also appears three-dimensionally inverted from the back, so that in the exemplary embodiment the smaller rings 24 appear to float above the larger rings 22.

Figure 3 shows some concrete advantageous embodiments of the grid of the color coating 46 of the micromirror embossing 44 in supervision. This shows Fig. 3(a) a grid 50 like it in Fig. 2 is used, in which the grid elements 52 and the grid spaces 54 form a checkerboard pattern. The dimensions of the grid elements and grid spaces are advantageously between 20 × 20 µm ² and 140 × 140 µm ² , the area coverage is 50%. If a different area coverage is to be created, some of the grid elements 52 can be omitted or some of the grid spaces 54 can be occupied with additional grid elements.

Figure 3(b) shows a grid 50 with alternately arranged strip-shaped grid elements 52 and grid spaces 54. The width of the grid elements and grid spaces is advantageously between 20 µm and 140 µm, the length is arbitrary and can be several millimeters or even a few centimeters. The area coverage can be easily adjusted via the relative width of the grid elements and grid spaces, and is preferably between 30% and 70%, in particular between 40% and 60%.

The grid elements and grid spaces can also have other polygonal shapes or irregular shapes. Shows as an example Fig. 3(c) an embodiment in which the grid elements 52 and grid spaces 54 of the grid 50 are formed by triangles. At the grid 50 the Fig. 3(d) the grid elements 52 and grid spaces 54 are formed by irregular shapes. The grid elements and/or grid spaces can also form a coherent structure, such as in Fig. 3(d) shown for the grid spaces 54 Here too, the surface coverage with grid elements is preferably between 30% and 70%, in particular between 40% and 60%.

Figure 4 shows a modification of the design of the Fig. 2 , in which the angle of inclination of the micromirrors of the micromirror embossing 44 and the magnetic orientation of the magnetic pigments 32 are selected so that the appearances generated by the two reflection structures become visible in different, non-overlapping viewing angle ranges and thereby a binary color and effect change when the security element 12 is tilted generate.

Specifically, the micromirrors of the micromirror embossing 44 are aligned, for example, in such a way that the appearance generated by the micromirrors, for example a metallic-looking curvature, is visible in a viewing angle range of +5° to +20° (viewing direction 58-A) relative to the surface normal N . The magnetic pigments 32, on the other hand, were aligned by an external magnetic field in such a way that they produce a running effect that is visible in a viewing angle range of -5° to -20° relative to the surface normal (viewing position 58-B).

From the viewing direction 58-A, the viewer looks at the coated micromirrors of the micromirror embossing 44 in the area of the grid elements 52. In the area of the grid spaces 54, the viewer can basically perceive the magnetic pigments 32 of the printing layer 30, but their orientation is far from the viewing direction 58-A removed from the glossy angle. The magnetic pigments 32 therefore appear inconspicuous and, since they are strongly outshone by the micromirrors, which are essentially at the gloss angle, they practically do not contribute to the image impression. Overall, the viewer from the viewing direction 58-A essentially sees the curved representation generated by the micromirror embossing 44.

From the viewing direction 58-B, the micromirrors of the micromirror embossing 44 in the grid spaces 54 have no optical effect due to the lack of refractive index difference of the lacquer layers 42, 48, so that the viewer there looks at the magnetic pigments 32, which are essentially at the gloss angle in the viewing direction 58-B. In the area of the grid elements 52, the micromirrors of the micromirror embossing 44 are basically perceptible, but their orientation is far from the gloss angle when viewed from the viewing direction 58-B. They therefore appear inconspicuous and, since they are strongly outshone by the magnetic pigments 32 at the gloss angle, they practically do not contribute to the image impression. Overall, the viewer from the viewing direction 58-B essentially sees the optically variable running effect generated by the magnetic particles 32.

When the security element 12 is tilted, its appearance at a certain viewing angle suddenly jumps between the appearance of the metallic curved representation and the appearance of the optically variable running effect. The change in the motif and the color effect occurs simultaneously and without an intermediate or transitional stage in which both motifs or colors would be visible at the same time or one motif would be visible in the color of the other motif, and therefore represents a binary color and effect change .

A further variant of a security element 62 according to the invention is shown in Fig. 5 illustrated. The security element 62 is largely similar to that in connection with Fig. 2 The security element 12 described is constructed so that corresponding elements are each provided with the same reference numerals. Like the security element 12, this also contains Security element 62 a flat carrier 18, a printing layer 30 with aligned, color-shifting, platelet-shaped magnetic pigments 32 and an embossing layer 40 arranged above the printing layer 30 with a micromirror embossing 44 introduced into an embossing lacquer layer 42, which is provided with a color coating 46 present in some areas.

In contrast to the design of the Fig. 2 has the color coating 46 of the design of Fig. 5 a large recess 66, for example in the form of a 5 mm wide and 2 cm long curved strip. In the area of the recess 66, the micromirrors of the micromirror embossing 44 have no optical effect due to the lack of refractive index difference between the lacquer layers 42, 48, so that a viewer there looks at the deeper magnetic pigments 32 of the print layer 30. In the outer area 64 outside the recess 66, however, the visual impression of the security element 62 is determined by the higher micromirror embossing 44 and its color coating 46.

Specifically, the micromirror embossing 44 can produce, for example, in the outer area 64 a motif 64 that appears to bulge out of the plane of the security element 62 and appears in a first color. Within the motif 64, a movement effect in a second color is visible in a partial area 66, which is generated by the aligned magnetic pigments 32. For example, a light bar can move up and down along the partial area 66 when the security element 62 is tilted and create a so-called rolling bar effect. Since the rolling bar effect is just visible in the recess 66 of the color coating 46, the areas of different colors (first and second colors) and different effects (three-dimensional motif or running bar) appear exactly registered to one another.

There are numerous degrees of freedom for the layer structure of the security elements and the layer structure of data carriers with such security elements. The possibility of applying the magnetic pigments in a printing layer to the paper or polymer substrate of a document of value and of applying a security film with a partially coated micromirror embossing over the print has already been described.

Further advantageous variants are available Fig. 6 illustrated, wherein the embossing layer 40 can be formed in all variants with or without a carrier film and can be present, for example, in the form of a strip or patch.

First shows Fig. 6(a) a polymer banknote 70 with a transparent polymer substrate 72, in which the printing layer 30 and the embossing layer 40 are arranged on opposite sides at least partially overlapping one another.

The design of the Fig. 6(b) shows a paper banknote 80 with a paper substrate 82 with window 84. The printing layer 30 and the embossing layer 40 are arranged at least partially overlapping one another on opposite sides of the window 84. Magnetic pigments 32 could also be present inside the window, as in Fig. 6(b) illustrated.

Figure 6(c) showed a hybrid banknote 90 with a film/paper/film hybrid substrate 92 with a window 94 in the paper core 96. The printing layer 30 and the embossing layer 40 are arranged on opposite sides of the hybrid substrate 92 and at least partially cover each other in the area of the window 94. The embossing layer 40 can, as in Fig. 6(c) shown, be applied to the outside of the composite of the hybrid substrate 92, but it can also be present, for example, between the paper core 96 and one of the film layers 98 and thus represent a particularly strongly protected, internal security feature.

A further variant of the invention consists in not applying the embossing layer in the form of a security film, but rather introducing the embossing structure 44 directly into the polymer substrate of a work document. The printing layer 30 can then be printed in an overlapping manner.

Reference symbol list

10

Banknote

12

Security element

14, 16

Security features

18

carrier

20

Detail section

22, 24

larger or smaller rings

26

Zigzag pattern

30

Print layer

32

Magnetic pigments

34

binder

40

embossing layer

42

embossed lacquer layer

44

Micro mirror embossing

46

Color coating

48

Lacquer coating

50

grid

52

Grid elements

54

Grid spaces

56

viewer

58-A, 58-B

Viewing directions

62

Security element

64

Outdoor area

66

recess

70

Polymer banknote

72

Polymer substrate

80

Paper banknote

82

Paper substrate

84

Window

90

Hybrid banknote

92

Hybrid substrate

94

Window

96

paper core

98

foil layer

N

surface normals

Claims (15)

1. Optically variable security element for securing articles of value, the areal extent of which element defines a z-axis perpendicular thereto, having a polychromatic reflective surface region, wherein

   - the polychromatic reflective surface region contains two optically variable reflection structures arranged at different height levels in the z-direction and generating a different colour impression in reflection,

   - the higher-up reflection structure is formed by a relief structure provided with a colour coating,

   - the lower-down reflection structure is formed by a layer with lamellar, reflective effect pigments which are spatially oriented,

   - the two reflection structures overlap in an overlap region and the colour coating of the higher-up reflection structure in the overlap region has at least one cut-out in which the lower-down reflection structure becomes visible when the security element is observed,

   characterized in that
   the relief structure of the higher-up reflection structure is formed by a micromirror arrangement with directed micromirrors.
2. Security element according to Claim 1, characterized in that the lamellar effect pigments constitute magnetically orientable magnetic pigments or lamellar effect pigments orientable by other fields.
3. Security element according to Claim 1 or 2, characterized in that the effect pigments are formed by metallized pigments, by pigments having a thin-film coating, by reflective metal pigments having a translucent colour coating or by pigments having structural colours.
4. Security element according to at least one of Claims 1 to 3, characterized in that the effect pigments are present in a print layer with a transparent or translucent binder and/or the relief structure of the higher-up reflection structure is impressed in a transparent or translucent embossing varnish layer.
5. Security element according to at least one of Claims 1 to 4, characterized in that the colour coating of the higher-up reflection structure is configured as a regular or irregular raster with raster elements and raster interspaces, wherein the dimensions of the raster elements and/or raster interspaces at least in one direction are below 140 µm, preferably in that the dimensions of the raster elements and/or raster interspaces in one or both lateral directions are below 140 µm, preferably between 20 µm and 100 µm, in particular between 20 µm and 60 µm.
6. Security element according to Claim 5, characterized in that the raster elements and raster interspaces of the raster have the same shape and preferably also the same size, and/or in that the surface coverage of the raster by the raster elements is between 30% and 70%, preferably between 40% and 60%, in particular about 50%.
7. Security element according to any of Claims 1 to 6, characterized in that, in the overlap region, the colour coating of the higher-up reflection structure is applied in partial regions which have lateral dimensions of more than 140 µm, and/or in that the colour coating of the higher-up reflection structure is generated with cut-outs which have lateral dimensions of more than 140 µm.
8. Security element according to at least one of Claims 1 to 7, characterized in that the directed micromirrors are planar mirrors, concave mirrors and/or Fresnel-type mirrors, and/or the lateral dimensions of the micromirrors are below 20 µm.
9. Security element according to at least one of Claims 1 to 8, characterized in that the colour coatings are formed by translucent inks, by metallizations, thin-film structures, by translucent inks deposited with a metallization, by luminescent inks with a metallic reflection, by textured inks and/or by nanoparticle inks.
10. Security element according to at least one of Claims 1 to 9, characterized in that at least one partial region with a negative characteristic, in which the colour coating of the higher-up reflection structure and the effect pigments of the lower-down reflection structure are cut out, is provided in the overlap region.
11. Data carrier having an optically variable security element according to at least one of Claims 1 to 10.
12. Data carrier according to Claim 11, having a carrier with opposite main surfaces, each of which bears one of the two optically variable reflection structures, wherein the carrier in the overlap region is transparent or contains a transparent see-through window.
13. Data carrier according to Claim 10, having a carrier with opposite main surfaces, wherein both optically variable reflection structures are disposed one above the other on one main surface of the carrier.
14. Method for producing an optically variable security element, preferably according to any of Claims 1 to 10, in which

    - a carrier is provided, the areal extent of which defines a plane and a z-axis perpendicular thereto,

    - the carrier is provided with a polychromatic reflective surface region which is configured with two optically variable reflection structures arranged at different height levels in the z-direction and generating a different colour impression in reflection,

    - the higher-up reflection structure is formed by a relief structure provided with a colour coating,

    - the lower-down reflection structure is formed by a layer with lamellar, reflective effect pigments which are spatially oriented, and

    - the two reflection structures are configured overlappingly in an overlap region and the colour coating of the higher-up reflection structure in the overlap region is configured with at least one cut-out in which the lower-down reflection structure becomes visible when the security element is observed,

    characterized in that
    the relief structure of the higher-up reflection structure is formed by a micromirror arrangement with directed micromirrors.
15. Method according to Claim 14, characterized in that, for the configuration of the lower-down reflection structure,

    - a printing ink with a binder and with effect pigments orientable magnetically or by other fields is applied,

    - in the still-liquid state of the binder, the effect pigments are oriented with an external field, in particular an external magnetic field, to generate the desired spatial orientation, and

    - the binder is solidified to set the orientation of the effect pigments durably.

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