EP2225108A2

EP2225108A2 - Security element, and method for the production thereof

Info

Publication number: EP2225108A2
Application number: EP08863945A
Authority: EP
Inventors: Manfred Heim
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2007-12-20
Filing date: 2008-12-17
Publication date: 2010-09-08
Anticipated expiration: 2028-12-17
Also published as: US20100308570A1; WO2009080263A2; US8733797B2; WO2009080263A3; EP2225108B1; DE102007061828A1

Abstract

The invention relates to a security element (12) for protecting objects of value, comprising a thin-film element (22) that has a color flipping effect, and a semi-transparent ink layer (34) which is disposed over the thin-film element (22) in first zones (30). The color impression of the thin-film element (22) is adjusted to the color impression of at least one subarea of the semi-transparent ink layer (34) when viewed in predetermined viewing conditions. The security element (12) further comprises a transparent phase delaying layer (36) which is disposed over the thin-film element (22) in second zones (38) and forms a phase-shifting layer for light in the visible wavelength range.

Description

Security element and method for its production

The invention relates to a security element for securing valuables, a method for producing such a security element as well as a security paper and a data carrier with such a security element.

Data carriers, such as securities or identity documents, but also other valuables, such as branded articles, 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. Such security elements can be embodied, for example, in the form of a security thread embedded in a banknote, a covering film for a banknote with a hole, an applied security strip, a self-supporting transfer element or else in the form of a feature area applied directly to a value document.

A special role in the authenticity assurance play security elements, the viewing angle-dependent visual effects show, as they can not be reproduced even with the latest copiers. The security elements are equipped with optically variable elements that give the viewer a different image impression under different viewing angles and, for example, show a different color or brightness impression and / or another graphic motif depending on the viewing angle.

In this context, it is known to use security elements with multilayer thin-film elements whose color impression changes with the viewing angle for the observer and, for example, changes from green to blue, from blue to magenta or from magenta to green when the security feature is tilted. The occurrence of such color change In the following, the term "color shift effect" is used to refer to a security element that is tilted.

Proceeding from this, the object of the invention is to further improve a security element of the aforementioned type and in particular to provide a security element with an attractive visual appearance and high security against counterfeiting.

This object is achieved by the security element having the features of the main claim. A method for producing such a security element, a security paper and a data carrier are specified in the independent claims. Further developments of the invention are the subject of the subclaims.

According to the invention, a security element of the aforementioned type contains a thin-film element with a color-shift effect,

a semi-transparent ink layer, which is arranged in first regions above the thin-film element, wherein the color impression of the

Thin film element is adapted to the color impression of at least a portion of the semi-transparent ink layer when viewed under predetermined viewing conditions, and

a transparent phase retardation layer disposed in second regions over the thin film element and forming a phase shift layer for light from the visible wavelength range. In the context of the invention, a combination of different color ranges is thus used, which act very similar from a certain viewing direction, but behave differently when the security element is tilted. In the color-shifting regions not covered by the semitransparent ink layer, the color impression for the observer changes when the security element is tilted, while the covered regions remain substantially color-constant. Such a combination of color-constant and color-variable areas has a visually attractive appearance and is self-explanatory for the user since the color-constant areas simultaneously form a visually quiescent pole and a comparison point for the color-variable areas in the authenticity check. The combination of two color effects in the immediate vicinity makes it difficult to adjust the security element, since freely available colors or foils with color-shift effects can no longer be used directly.

In addition to the open security feature formed by the two different color areas, the security element according to the invention contains a hidden security feature which can only be recognized by auxiliary means and which is formed by the transparent phase delay layer arranged in second areas. Phase-retarding layers, which in the context of this description are also sometimes called phase-shifting layers, are optically active layers which act on the phase of a transmitted light wave. Due to different refractive indices, the partial beams of an incident polarized light wave receive a path difference and thus a phase difference. If the phase difference of the two partial beams is just half or quarter wavelength, so-called λ / 2 or λ / 4 layers are obtained. Preferably, the phase delay of the phase retardation layer in the invention corresponds to a retardation between about λ / 6 and about λ / 2, more preferably between about λ / 4 and about λ / 2. The path difference is modulo λ, ie in the range between 0 and λ indicated, since a layer with a path difference, for example, of 5/4 * λ or 9/4 * λ generates the same phase delay as a λ / 4 layer. In the context of the invention, it is also preferable that the phase-shifting layer is formed from nematic liquid-crystalline material and / or that the phase-delay layer is in the form of patterns, characters or a coding.

In a spectral range in which the color impression of the thin-film element is adapted to the color impression of the semitransparent layer, the semitransparent color layer preferably has a light transmittance between 30% and 95%, more preferably between 60% and 95% and very particularly preferably between 80% and 95% % on.

The semitransparent ink layer can be applied in various ways, and is advantageously imprinted, for example in screen-printing, gravure printing, flexographic printing or another suitable printing process. The semitransparent ink layer can be printed directly on the thin-film element, but it can also be provided between the ink layer and thin-film element and transparent intermediate layers, for example, act as a protective layer or adhesive layer. It is also possible to provide such transparent intermediate layers between the color layer and the phase delay layer.

In order to introduce additional features in the security element, the semi-transparent ink layer is in preferred embodiments in the form of Characters, patterns or encodings. This also includes designs in which the color layer has recesses in the form of characters, patterns or codes.

In particularly preferred embodiments, the semi-transparent ink layer is selected such that it substantially preserves the polarization state of transmitted light from the visible wavelength range. In this way, the patterns, characters or codes formed by the phase retardation layer can be made equally visible both in the color-variable and in the color-constant regions, as explained in more detail below.

The semitransparent ink layer can also have several subregions with different color impressions, in which case the color impression of the thin film element is adapted to the color impression of at least one of the subregions when viewed under predetermined viewing conditions.

A particularly appealing effect can be achieved if the thin-layer element and the semitransparent ink layer are matched to one another such that, when the security element is viewed vertically, the color impression of the thin-film element outside the first regions essentially corresponds to the color impression of at least one subregion of the semi-transparent ink layer. When viewed vertically, which often results from the first perception of a security element applied to a valuable object, the color-variable and the color-constant areas initially convey essentially the same color impression. When tilting the security element, the color impression changes in the color-variable regions while remaining unchanged in the color constant covered regions.

In an advantageous variant of the invention, the thin-film element has a reflection layer, an absorber layer and a dielectric spacer layer arranged between the reflection layer and the absorber layer. The color shift effect in such thin-film elements is based on viewing angle-dependent interference effects due to multiple reflections in the different sub-layers of the element. The path difference of the light reflected at the different layers depends on the one hand on the optical thickness of the dielectric spacer layer, which determines the distance between the absorber layer and the reflection layer, and on the other hand varies with the respective viewing angle.

Since the path difference is on the order of the wavelength of the visible light, the result is an angle-dependent color impression for the viewer due to the extinction and amplification of certain wavelengths. By a suitable choice of material and thickness of the dielectric spacer layer, a multiplicity of different color-shift effects can be designed, for example tilting effects in which the color impression changes with the viewing angle from green to blue, from blue to magenta or from magenta to green.

The reflection layer of the thin-film element is preferably formed by an opaque or by a semitransparent metal layer, in particular aluminum. As a reflection layer, an at least partially magnetic layer can also be used so that a further authenticity feature can be integrated without requiring an additional layer in the layer structure. The reflective layer may further comprise recesses in the form of patterns, characters or codes that form transparent or semi-transparent regions in the thin-film element. In the transparent or semi-transparent recessed areas, the observer has a conspicuous contrast to the surrounding color effects. In particular, the patterns, characters or codes can light up brightly in transmitted light when the thin-film element is applied to a transparent or translucent carrier. The recesses in the reflection layers can also be grid-like, preferably with a small surface area of 40% or less, so that they are practically inconspicuous in reflected light and only appear in transmitted light.

According to another likewise advantageous variant of the invention, the thin-film element can also be formed by superimposed absorber layers and dielectric spacer layers, it also being possible for a plurality of absorber and spacer layers to be arranged alternately one above the other. Such thin-film elements also show a color-tilting effect, but are not opaque, so that the color-shift effect is also visible from the rear side of the security element.

In all configurations, the dielectric spacer layer is preferably produced by a vacuum vapor method. Alternatively, the spacer layer can also be formed by a printing layer or by an ultrathin film, in particular a stretched polyester film. Particularly preferred at present is a configuration in which the dielectric spacer layer is formed by a low-refractive dielectric layer, in particular a vapor-deposited SiCb layer or an MgF 2 layer. Further details on the structure of such thin-film elements and on the materials and layer thicknesses that can be used for the reflection layer, the dielectric spacer layer and the absorber layer can be found in the publication WO 01/03945, the disclosure of which is incorporated in the present application.

As an alternative or in addition to the recesses in the reflection layer, the absorber layer and / or the spacer layer can also have recesses in the form of patterns, characters or codes. There is no color shift effect in the recessed areas of the absorber layer or the spacer layer.

In an advantageous development of the invention, the security element additionally has a relief structure over which the thin-film element is arranged in an overlapping area. The thin-film element may in this case be arranged partially or completely over the relief structure or may also project beyond it.

The relief structure may represent a diffractive structure, such as a hologram, a holographic grating image or a hologram-like diffraction structure, or an achromatic structure, such as a matt structure with a non-colored, silvery matt appearance, a micromirror arrangement, a blazed grating with a sawtooth-like furrow profile or a Fresnel lens arrangement. The dimensions of the structural elements of the diffractive relief structures are usually of the order of magnitude of the wavelength of light, that is to say generally between 300 nm and 1 μm. Some relief structures also have smaller structural elements, such as sub-wavelength gratings or moth-eye structures, whose structural elements may also be smaller than 100 nm. The structural elements achromatic The dimensions of micromirrors or blazed grating lines are approximately up to a height of about 15 μm and a lateral extent of about 30 μm.

In an advantageous embodiment, the security element contains a substrate on which the thin-film element _/ the semitransparent color layer and the phase delay layer are arranged. This substrate may in particular be formed by a plastic film. After the transfer of the security element to a data carrier, the substrate can be removed from the layer structure of the security element or it can remain as a protective layer as an integral part of the security element in the layer structure. In some embodiments, a release or release layer, for example a wax, can also be provided between the security element and the substrate.

Preferably, the security element is a security thread, a security tape, a security strip, a patch or a label for application to a security paper, document of value or the like.

It is understood that the security element can also have further layers, such as protective layers or additional effect layers with other security features.

The invention also includes a method for producing a security element of the type described, in which

a semitransparent color layer is arranged above a thin-film element with a color-shift effect in first regions, wherein the Color impression of the thin-film element is adapted to the color impression of at least a portion of the semi-transparent ink layer when viewed under predetermined viewing conditions, and

a transparent phase delay layer is arranged in second regions above the thin-film element, which forms a phase-shifting layer for light from the visible wavelength range.

The semitransparent ink layer is advantageously printed in the process according to the invention, in particular in screen printing, gravure printing or flexographic printing processes. The phase retardation layer can also be advantageously printed on the thin-film element and optionally the previously applied ink layer. Alternatively, the phase delay layer can be applied to a separate carrier foil and transferred to the thin-layer element with the applied color layer.

In one development of the method according to the invention, an embossing lacquer layer is applied to a substrate and embossed in the form of a desired relief structure. Over this relief structure, a thin-film element of the type described above is then applied in an overlap region.

In advantageous developments, the reflection layer and / or the absorber layer of the thin-film element are provided with recesses in the form of patterns, characters or codes.

The invention further comprises a security paper with a security element of the type described, as well as a data carrier which is provided with such a security element. - li ¬

The security element is equipped. The data carrier may in particular be a banknote, a value document, a passport, a document or an identity card. The described security elements, security papers or data carriers can be used in particular for securing objects of any kind.

Since the described semitransparent color layers largely preserve the polarization of the transmitted light, it is also possible in principle to coat a metal layer with a semitransparent color layer and to arrange a transparent phase delay layer in the form of patterns, characters or codings, and the latter when viewed with a suitable polarizer in the coated and uncoated areas equally visible.

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

Show it:

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

2 shows a cross section through a security element according to a

Embodiment of the invention,

3 shows the visual impression of a security element according to the invention under different viewing conditions, in FIG (a) when viewed vertically without auxiliary means, in (b) when viewed obliquely without aids and in (c) when viewed vertically with an applied circular polarizer,

4 shows a security element according to another exemplary embodiment of the invention, in which the phase retardation layer is arranged below the semitransparent ink layer,

5 shows a security element according to a further exemplary embodiment of the invention, in which the phase delay layer and the semitransparent color layer are applied to the thin-film element, and

6 shows a security element according to yet a further exemplary embodiment of the invention, in which color-constant areas, color-shifting areas and the hidden security feature of the phase-delay layer are combined with an embossed hologram.

The invention will now be explained using the example of a banknote. 1 shows a schematic representation of a banknote 10 with a security element 12 according to the invention in the form of a glued-on transfer element. It is understood that the invention is not limited to transfer elements and bank notes, but can be used with all types of security elements, for example labels on goods and packaging or in the security of documents, ID cards, passports, credit cards, health cards and the like , Banknotes and similar documents come except transfer elements, for example also security threads and in addition to supervisory elements and see-through elements in question.

The structure of a security element 12 according to the invention will now be explained in more detail with reference to Figures 2 and 3, wherein Figure 2 shows a cross section through the security element and Fig. 3 in (a) to (c) the visual impression of the security element in three different viewing conditions shows. FIG. 3 (a) shows a section of the security element 12 when viewed perpendicularly and without auxiliary means, FIG. 3 (b) shows the section of (a) obliquely also without aids and FIG. 3 (c) shows the section of (FIG. a) and (b) when viewed vertically with an applied circular polarizer.

Referring first to FIG. 2, the security element 12 includes a thin-film element 22 with a color-shift effect applied to a carrier film 20. The thin-film element 22 comprises a reflective layer 24 formed by an opaque aluminum layer, a dielectric SiCh spacer layer 26 vapor-deposited on the reflective layer, and a partially transparent absorber layer 28, which may be formed of chromium, for example. As explained above, the color shift effect of such a thin film element 22 is due to interference effects due to interference of the light beams reflected at the sublayers 24, 26, 28 of the element.

In the first regions 30, a semi-transparent ink layer 34 is printed on the thin-film element 22; in the regions 32 outside the first regions 30, the thin-film element 22 is present without a printed ink layer. The thin-film element 22 and the semitransparent ink layer 34 are matched to one another in such a way that they produce substantially the same color impression at a normal viewing angle. When tilting the security element 12, the color impression of the thin-film element 22 changes in the uncovered areas 32, while the color impression in the covered first areas 30 remains virtually unchanged. For example, the thin-film element 22 may be designed so that its color impression changes from magenta when viewed perpendicularly to green when viewed obliquely. Coordinated with this, the semitransparent ink layer 34 when viewed perpendicularly conveys a likewise magenta color impression, which changes only insignificantly when the security element 12 is tilted.

As indicated in the illustration of FIG. 3 (a) by the similar hatching, the covered areas 30 and the uncovered areas 32 when viewed vertically thus have a very similar or even the same color impression. In order to approximate the color impression of the two areas, the semitransparency of the color layer 34 additionally contributes. Namely, while the color location of a printed ink layer can be set very accurately and reproducibly, the tilt color in which the thin-film element 22 appears at a normal viewing angle varies slightly due to manufacturing variations of the security element to the security element.

Due to the semi-transparent formation of the color layer 34, this vertical tilting color partially shines through the color layer 34 and contributes to the overall color impression of the security element in the first regions 30. With a small variation of the vertical tilting color of the thin-film element 22 in the uncovered areas 32, therefore, the color impression in the covered areas 30 likewise changes accordingly, so that the overall color impressions of the areas 30, 32 are matched to one another. In addition, the semitransparency of the imprinted Th color layer 34 in the overlaid areas 30, the visual impression of a metallic luster, since there the metallic luster of the underlying reflective layer 24 shines through. The covered regions 30 and the uncovered regions 32, which anyway have a metallic luster due to the thin-film element 22 which is directly visible there, therefore also have a similar appearance in terms of their luster properties.

When the security element 12 is tilted, the color impression of the thin-film element 22 visible in the uncovered regions 32 changes with increasing tilt angle from magenta to green, while the color impression in the first regions 30 covered by the color layer 34 remains substantially constant. From an oblique viewing angle shown in FIG. 3 (b), therefore, a clear color difference between the areas 30 and 32 can be perceived by the observer, as indicated by the different hatchings in the figure. The combination of color-variable regions 32 with immediately adjacent color-constant regions 30 further increases the visual conspicuousness of the color-shift effect, since the human eye reacts more strongly to the color differences that occur than to the color change per se.

In addition to the open security feature formed by the color variable and color constant regions 30, 32, the security element 12 includes a hidden security feature formed by a transparent phase retardation layer 36 that is patterned in second regions 38 over the thin film element 22.

The phase retardation layer 36 is made of a birefringent material, for example of nematic liquid crystalline material. The layer thickness of the phase retardation layer 36 is typically as chooses that its phase delay corresponds to a path difference between about λ / 6 and about λ / 2, preferably about λ / 4, where λ represents a wavelength in the visible spectral range.

When the security element 12 is viewed with ordinary unpolarized light and without auxiliaries, the second regions 38 with the phase delay layer 36 are virtually undetectable, since the phase delay of the layer 36 acts equally on all polarization directions of the incident light and its light absorption is negligibly small.

On the other hand, when the security element 12 is viewed with an applied polarizer 40, as shown in FIG. 3 (c), strong contrast differences occur between the regions 38, 39 with and without the phase retardation layer 36. The presence and shape of the pattern formed by the areas 38 can thus be used for additional authenticity testing, for example at the point of sale or in banks.

The mode of operation of the hidden security feature will now be explained in more detail using the example of a λ / 4 phase delay layer 36 and an applied circular polarizer 40, which transmits only right-circularly polarized light. Under these conditions, only the right circularly polarized portion of the circular polarizer 40 is transmitted by incident unpolarized light. In the subregions 39 of the security element without phase delay layer 36, the right circularly polarized light is reflected by the metallic reflector layer 24 of the thin film element 22 with the direction of polarization reversed, that is to say as left circularly polarized light. The reflected left circularly polarized light is blocked by the circular polarizer 40, so that the partial areas 39 appear dark to the viewer. On the other hand, in the sub-regions 38 with the phase retardation layer, the right-circularly polarized light is converted into linearly polarized light by the retardation layer 36 prior to reflection at the reflector layer 24. The unchanged linearly polarized, reflected light passes through the phase retardation layer 36 again and is thereby converted into right-circularly polarized light, which can pass through the circular polarizer 40 in the selected conditions without further notice. In the subregions 38, the pattern 30, 32 of the open security feature therefore appears to the viewer essentially unchanged as bright.

When a linear polarizer is placed in place of a circular polarizer, the reversed contrast ratios are obtained with suitable orientation of the linear polarizer. In this case, the linearly polarized light is reflected by the metallic reflector layer 24 of the thin-film element 22 with unchanged linear polarization in the subregions 39 without the phase retardation layer 36 that the reflected light is transmitted by the linear polarizer. The pattern 30, 32 of the open security feature is thus still brightly visible in the subregions 39. Meanwhile, the phase retardation layer portions 38 now appear dark because the linearly polarized light is converted by the retardation layer 36 into circularly polarized light, the circularly polarized light is reflected at the retardation layer in the reverse circular polarization direction, and retransporting the phase retardation layer into linearly polarized light is converted, whose polarization vector is perpendicular to the output polarization, so that the reflected light is blocked by the linear polarizer.

Of particular importance for the combinability of the two security features is the fact that the semi-transparent ink layer 34 the Polarization state of the transmitted light largely preserved. This ensures that the pattern formed by the phase retardation layer 36 in the color-variable and color-constant regions 30, 32 can be made equally visible.

For the production of the security element 12 of FIG. 2, for example, the thin-film element 22 and the semitransparent ink layer 34 can be applied to a first carrier film and the phase retardation layer 36 can be applied to a second carrier film in the form of the desired pattern. The second carrier film is then transferred together with the phase retardation layer 36 by means of laminating adhesive 42 onto the thin-film element 22 with the semitransparent ink layer 34 and the second carrier film is then stripped off.

Another embodiment of the invention is shown in FIG. In contrast to the design of FIG. 2, the phase retardation layer 36 in this exemplary embodiment lies below the semitransparent ink layer 34. The layer denoted by reference numeral 44 represents a transparent layer, for example an adhesive layer, a protective lacquer layer, a primer or the like The semi-transparent ink layer 34 is also covered with a protective lacquer layer 46.

Since the semi-transparent ink layer 34 largely preserves the polarization state of the light passing through, the mode of operation of the embodiment of FIG. 4 corresponds to the already described mode of operation. In addition, recesses 50 are introduced into the reflector layer 24 of the thin-film element, which form a negative writing, for example. In the area of these recesses 50, the thin-film element 22 is transparent or translucent, so that there in addition to the described effects a striking contrast effect in the transmitted light results. Translucence is used in the sense of a certain transparency, with translucent layers usually reducing the brightness of the objects behind and / or below them and / or changing their color.

The absorber layer 28 may be provided with recesses 52. In the region of the recesses 52 of the absorber layer, the thin-film element 22 has no color-shift effect due to the lack of interference. If the cutouts 52 lie in ink-layer-free areas 32, as shown in FIG. 4, then the security element 12 appears there with the metallic luster of the reflection layer 24. It is understood that the exemplary embodiment of FIGS. 2 and 3 described above also includes such Recesses may be provided in the reflector layer and / or the absorber layer.

In the alternative configuration shown in FIG. 5, the phase-delay layer 36 and then the semitransparent color layer 34 are printed on the thin-film element 22 first. As in the embodiments of FIGS. 2 and 4, the color layer 34 can also completely cover the phase retardation layer 36, as shown in the left part of the figure, the color layer can be completely within the phase-retarding areas, as shown in the middle figure part, or the color layer may partially overlap with the phase retardation layer 36, as shown in the right part of the figure. Since the semitransparent ink layer 34 largely preserves the polarization state of the transmitted light, the desired polarization effect can be used in all cases for the authenticity check. Fig. 6 shows, as a further embodiment of the invention, a color-shift hologram in which the effects described above are combined with an embossed hologram. The security element 60 of FIG. 6 contains a carrier foil 62 and an embossed and cured UV lacquer layer 64 applied to the carrier foil 62. The embossed structures of the lacquer layer 64 form a diffractive relief structure representing a hologram, a hologram lattice image or a hologram-like diffraction structure , In other designs, the embossed structures can also represent achromatic relief structures with a non-colored, for example, silvery matt appearance.

Applied to the relief structure of the lacquer layer 64 is a thin-layer element 66 which, as described above, comprises, for example, a reflection layer 68, a dielectric spacer layer 70 and a partially transparent absorber layer 72. The reflective layer and the absorber layer may be provided with recesses 74 and 76, respectively.

Analogously to the procedure already described, color-variable and color-constant areas which are matched to one another by area-wise printing of a semitransparent ink layer 80 are then created which, together with the holographic relief structure, form the open security feature. A transparent phase delay layer 82 in the form of a character, a pattern or an encoding is transferred to this layer sequence in order to obtain a hidden security feature which can be detected by means of a linear or circular polarizer.

The color-shift hologram 60 offers the viewer a visually attractive appearance with high recognition value. When viewed vertically, the security element shows as a basic structure a colored, For example, magenta hologram. When the security element is tilted, the regions of the hologram not covered by the semitransparent ink layer 80 change their color, so that their color impression, for example, shifts from magenta to green, while the color impression of the hologram in the covered regions 80 remains substantially constant.

In the areas in which recessed areas 74 of the absorber layer lie in non-ink-free areas, the visual impression of the security element is determined by the reflection layer 68, so that the hologram there appears to be silvery-metallic. In areas 76 without a reflection layer, the security element appears transparent or translucent. The recessed areas 74, 76 may thus form, for example, a negative metallic writing within the security element or create local viewing areas in an otherwise opaque security element. In addition, the hidden security feature of the phase retardation layer 82 is available for further authentication, as described above.

In all embodiments described, the semi-transparent ink layer can also have a plurality of partial regions with different color impressions. The color impression of the thin-film element can then be adapted to the color impression of one or more of the subregions for one or also for a plurality of predetermined viewing conditions. For example, a thin-film element whose color impression changes from magenta to green when tilted can be combined with a semi-transparent ink layer with two subregions, of which the first subregion appears magenta, the second subregion green. The color impression of the thin-film element then corresponds to the color input when viewed vertically. Printing the first portion of the color layer (magenta), while it corresponds to oblique viewing substantially the color impression of the second portion of the color layer (green). By means of this color change and the associated change in the visual assignment, for example, different design elements of the security element can emerge and / or disappear when tilted.

The thin-film elements can also be formed in the form of absorber layer / dielectric layer / absorber layer in all designs, wherein larger layer stacks with the sequence absorber layer 1 / dielectric layer 1 / absorber layer 2 / dielectric layer 2... Dielectric layer NI / absorber layer N, with N = 3, 4, 5 ..., are possible. Such layer sequences also have a color-shift effect, but are not opaque, so that the color-shift effect is also visible from the rear side of the security element. Security elements with such thin-film elements can be used in particular for documents with see-through areas.

The mentioned recesses in the reflection layers can also be grid-like, preferably with a small areal proportion of 40% or less. The recesses of the reflection layers are then practically not incident on reflected light, but only appear in transmitted light.

Claims

Patent claims

1. Security element for securing valuables with

a thin-film element with a color-shift effect,

a semitransparent ink layer which is arranged in first regions above the thin-film element, the color impression of the thin-film element, when viewed under predetermined viewing conditions, being adapted to the color impression of at least one subregion of the semitransparent ink layer, and

a transparent phase retardation layer disposed in second regions over the thin film element and forming a phase shift layer for light from the visible wavelength range.

2. Security element according to claim 1, characterized in that the semitransparent color layer in a spectral range in which the color impression of the thin-film element is adapted to the color impression of the semitransparent layer, a light transmission between 30% and 95%, preferably between 60% and 95% and more preferably between 80% and 95%.

3. Security element according to claim 1 or 2, characterized in that the semi-transparent ink layer is printed.

4. Security element according to at least one of claims 1 to 3, characterized in that the semi-transparent ink layer is in the form of characters, patterns or codes.

5. A security element according to at least one of claims 1 to 4, characterized in that the semi-transparent ink layer essentially receives the polarization state of passing light from the visible wavelength range.

6. The security element according to claim 1, wherein the semitransparent color layer has a plurality of partial areas with different color impressions, and the color impression of the thin-film element is adapted to the color impression of at least one of the partial areas when viewed under predetermined viewing conditions.

7. A security element according to at least one of claims 1 to 6, characterized in that when viewed perpendicularly the security element of the color impression of the thin-film element outside the first partial areas substantially corresponds to the color impression of at least a portion of the semi-transparent ink layer.

8. The security element according to claim 1, wherein the thin-film element contains a reflection layer, an absorber layer and a dielectric spacer layer arranged between the reflection layer and the absorber layer.

9. A security element according to claim 8, characterized in that the reflection layer by an opaque or a semi-transparent metal layer is formed, preferably by an opaque or semi-transparent aluminum layer.

10. Security element according to at least one of claims 1 to 7, character- ized in that the thin-film element at least a first

Absorber layer, a second absorber layer and a disposed between the two absorber layers dielectric spacer layer contains.

11. A security element according to at least one of claims 8 to 10, characterized in that the dielectric spacer layer is formed by a vapor deposition layer produced in the vacuum vapor method, a printing layer or an ultra-thin film, in particular a stretched polyester film.

12. A security element according to at least one of claims 8 to 11, characterized in that the reflective layer has recesses in the form of patterns, characters or codes that form transparent or translucent areas in the thin-film element.

13. A security element according to at least one of claims 8 to 12, characterized in that the absorber layer and / or the spacer layer has recesses in the form of patterns, characters or codes in which no color shift effect is recognizable.

14. The security element according to at least one of claims 1 to 13, characterized in that the security element further comprises a relief structure, over which the thin-film element is arranged in an overlap region.

15. A security element according to claim 14, characterized in that the relief structure is a diffractive structure, such as a hologram, a holographic grating image, or a hologram-like diffraction structure, or an achromatic structure, such as a matte structure, a micromirror array, a blaze grating with a sawtooth-like Groove profile or Fresnellinsen- arrangement represents.

16. The security element according to claim 1, wherein the phase delay of the phase retardation layer for light from the visible wavelength range corresponds to a path difference between λ / 6 and λ / 2.

17. A security element according to at least one of claims 1 to 16, characterized in that the phase retardation layer for light from the visible wavelength range forms a λ / 4 layer at least in subregions.

18. The security element according to claim 1, wherein the phase delay layer is formed from nematic liquid-crystalline material.

19. A security element according to at least one of claims 1 to 18, characterized in that the phase delay layer is in the form of patterns, characters or a coding.

20. A security element according to at least one of claims 1 to 19, characterized in that the security element comprises a substrate on which the thin-film element, the semi-transparent ink layer and the phase delay layer are arranged.

21. Security element according to claim 20, characterized in that the substrate is formed by a plastic film.

22. Security element according to at least one of claims 1 to 21, characterized in that the security element is a security thread, a security tape, a security strip, a patch or a label for application to a security paper, document of value or the like.

23. A method for producing a security element according to at least one of claims 1 to 22, wherein

a semitransparent ink layer is arranged above a thin-film element with a color-shift effect in first regions, the color impression of the thin-film element being adapted to the color impression of at least one subregion of the semitransparent ink layer when viewed under predetermined viewing conditions, and

24. The method according to claim 23, characterized in that the semi-transparent ink layer is printed, in particular in screen printing, gravure printing or flexographic printing.

25. The method according to claim 23 or 24, characterized in that the phase delay layer is printed on the thin-film element and optionally the color layer.

26. The method according to claim 23 or 24, characterized in that the phase retardation layer is applied to a carrier film and is transferred to the thin film element with the applied ink layer.

27. Method according to claim 23, characterized in that an embossing lacquer layer is applied to a substrate and embossed in the form of a desired relief structure, and that the thin-film element is applied over the relief structure in an overlapping region.

28. The method according to at least one of claims 23 to 27, characterized in that the reflection layer of the thin-film element and / or the absorber layer of the thin-film element are provided with recesses in the form of patterns, characters or codes.

29. Security paper for the production of security or value documents, such as banknotes, checks, identity cards, certificates or the like, which is equipped with a security element according to at least one of claims 1 to 28.

30. Security paper according to claim 29, characterized in that the security paper comprises a carrier substrate made of paper or plastic.

31. Data carrier, in particular branded article, valuable document or the like, with a security element according to one of claims 1 to 28.

32. Use of a security element according to at least one of claims 1 to 28, a security paper according to claim 29 or 30, or a data carrier according to claim 31 for counterfeiting of goods of any kind.