CA2707728C

CA2707728C - Optically variable security element

Info

Publication number: CA2707728C
Application number: CA2707728A
Authority: CA
Inventors: Christoph Mengel; Alexander Bornschlegl
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2007-12-11
Filing date: 2008-12-09
Publication date: 2016-03-29
Anticipated expiration: 2028-12-09
Also published as: WO2009074284A2; CN101903183A; CN101903183B; EP2234816A2; RU2010127783A; PL2234816T3; CA2707728A1; RU2472627C2; HK1150039A1; EP2234816B1; DE102007059550A1; WO2009074284A3

Abstract

The present invention relates to an optically variable security element (12) for securing valuable articles, having an optically variable ink layer (40) that includes first, optically variable effect pigments (34) for producing a viewing-angle-dependent visual impression, and that includes second effect pigments (36) that are reversibly alignable by an external magnetic field, the degree of markedness of the viewing-angle-dependent visual impression of the optically variable effect pigments (34) depending on the orientation of the magnetically alignable effect pigments (36) relative to the plane of the ink layer (40).

Description

Optically Variable Security Element The present invention relates to an optically variable security element for securing valuable articles. The present invention further relates to a method for manufacturing such a security element, a security arrangement having such a security element, a correspondingly furnished data carrier and a verification device for such a security element.
For protection, data carriers, such as value or identification documents, but also other valuable articles, such as branded articles, are often provided with security elements that permit the authenticity of the data carrier to be verified, and that simultaneously serve as protection against unauthorized reproduction. The security elements can be developed, for example, in the form of a security thread embedded in a banknote, a cover foil for a banknote having a hole, an applied security strip, a sell-supporting transfer element, or also in the form of a feature region applied directly to a value document.
Security elements that display viewing-angle-dependent visual effects play a special role in safeguarding authenticity, as these cannot be reproduced even with the most modern copiers. For this, the security elements are furnished with optically variable elements that, from different viewing angles, convey to the viewer a different image impression and, depending on the viewing angle, display for example another color or brightness impression and/or another graphic motif.
In this connection, it is known to use security elements having multilayer thin-film elements whose color impression for the viewer changes with the viewing angle, and when the security feature is tilted, shifts for example from green to blue, from blue to magenta or from magenta to green. The

- 2 -occurrence of such color changes upon tilting a security element is referred to in the following as a color-shift effect.
From publication WO 02/073250 A2 are known optically variable thin-film elements in whose layer structure at least one magnetic layer is integrated.
The magnetic properties of these optically variable thin-film elements can then be used as an additional authenticating mark.
In publication EP 1 780 040 A2 is described a security element in which are present, in a sub-region, magnetically aligned pigment particles that produce a kinematic visual effect. Here, the magnetically aligned pigment particles can especially also exhibit optically variable properties.
Based on that, it is the object of the present invention to further improve a security element of the kind cited above, and especially to create a security element having an attractive visual appearance and high counterfeit security whose appearance can additionally be interactively influenced when checking the authenticity.
A method for manufacturing such a security element, a security arrangement having such a security element, a correspondingly furnished data carrier and a verification device for such a security element are described.
According to the present invention, a generic security element exhibits an optically variable ink layer that includes first, optically variable effect pigments for producing a viewing-angle-dependent visual impression, and

- 3 -that includes second effect pigments that are reversibly alignable by an external magnetic field, and in which the degree of markedness of the viewing-angle-dependent visual impression of the optically variable effect pigments depends on the orientation of the magnetically alignable effect pigments relative to the plane of the ink layer.
Such a security element offers a combination of attractive visual effects, namely, on the one hand, the optically variable effects of the first effect pigments and, on the other hand, the reversible magnetic alignability of the second effect pigments, through which, as described in greater detail below, three-dimensional-seeming appearances can be interactively produced that can, if applicable together with further information, reversibly be brought to appear and to disappear again. In one development of the present invention, the second effect pigments can, at a later time, through an activatable fixative, be fully or partially fixed in a desired position such that the security element can especially be subsequently provided with an individual marking, as explained in greater detail below.
According to the present invention, the two effects occur here in interaction in that the markedness of the optically variable effect depends on the orientation of the magnetically alignable effect pigments. The interactive influencing of the magnetic pigments thus not only reveals previously non-visible appearances and, if applicable, further information, but also changes the intensity and brilliance of the optically variable effect.
To ensure a reversible magnetic alignabidity of the pigments, the second effect pigments are preferably encapsulated in a microcapsule and are substantially freely rotatable in the microcapsule. Here, without an external magnetic field, the second effect pigments are preferably aligned

- 4 -isotropically within the microcapsule, so exhibit, as a whole, no preferred direction. In practice, certain deviations from the ideal isotropic alignment can, of course, occur here, depending, for example, on the geometric shape, the magnetizability, the viscosity of the encapsulation liquid or the structure of the encapsulation.
After the application of an external magnetic field, the second effect pigments initially align quickly and, after cessation of the external magnetic field, return to their initial state. Without a restoring force or without other external forces, this return can, in some cases, last very long and require several minutes, hours or even days. Within this period, a magnetization pattern displayed by the security element initially remains visible also after the removal of the verification magnet, and recedes only when an active movement with an external magnet cancels or changes the orientation of the second effect pigments.
To accelerate the return to the initial state, the microcapsules can include, in expedient embodiments, a gel that provides a restoring force for the magnetically alignable effect pigments. For this, for example, a transparent polymerizable substance that is preferably a mixture of photocrosslinkable mono- and oligomers and a suitable solvent, can be introduced into the microcapsules and, through crosslinking, a gel-like structure systematically produced in the microcapsules that, on the one hand, allows a rotation of the effect pigments by an external field and that, on the other hand, when a rotation has occurred, produces a restoring force that causes the effect pigments to quickly return to their initial position after a cessation of the external field. In another embodiment, such a restoring force can also be produced by a premagnetization of a magnetic layer combined with the optically variable ink layer.

- 5 -In an advantageous embodiment of the present invention, the first effect pigments are present outside the microcapsules of the second effect pigments. Alternatively, the first effect pigments can also be encapsulated in the microcapsules together with the second effect pigments. In this case, the first effect pigments are advantageously developed to be platelet-like. Since, in this embodiment, the alignment of the first effect pigments likewise changes when the magnetic second effect pigments are aligned, dynamic, interactive color effects can be produced through the joint encapsulation. In a special variant, the first and second effect pigments are formed by the same magnetically alignable and optically variable effect pigments.
The second effect pigments are preferably formed on the basis of high-purity iron powder and can, for example, be manufactured from carbonyl iron powder treated under reducing conditions. Advantageous platelet-like iron pigments are set forth especially in publication EP 1 251 152 B1, whose disclosure on the manufacture and properties of such pigments is incorporated in the present description by reference.
Here, the second effect pigments can be magnetically soft or magnetically hard. The second effect pigments are preferably developed to be non-spherical, for example acicular. Here, effect pigments that exhibit a platelet form are particularly preferred. In the following, the largest diameter of a non-spherical pigment is also referred to as the length or size of the pigment, while the smallest diameter is referred to as the thickness of the pigment.
The ratio of the largest diameter to the smallest diameter of the non-spherical second effect pigments is preferably more than 5:1, preferably more than 10:1. This ratio is particularly preferably between 40:1 and 400:1. The largest

- 6 -diameter of the non-spherical second effect pigments is advantageously more than 2 gm, preferably more than 5 gm, particularly preferably more than 10 gm and very particularly preferably more than 15 gm. The use of magnetically alignable effect pigments in the micrometer range and especially in the cited size range has especially the advantage that the particle concentration compared with nanoparticles can be kept lower.
Platelet-like effect pigments, especially in the preferred size range and in the preferred diameter-to-thickness range, can be oriented as desired relative to the layer plane by an external magnetic field. Depending on the orientation, they then either largely reveal, like the slats in a window blind, the view of underlying layers (nearly vertical orientation relative to the layer plane) or block it partially (oblique orientation relative to the layer plane) or completely (substantially horizontal orientation relative to the layer plane).
In this way, high contrasts between translucent and opaque layer regions can be set for high diameter-to-thickness ratios.
In the context of the present description, "translucent" here means sheer in the sense of a certain or complete transmittance and thus also includes transparency. A translucent layer permits the perception of the objects located behind or below it, even if the brightness of the objects can be reduced and/or the color of the objects altered by the translucent layer. If, in contrast, the transmittance of a layer is so low that the objects located behind or below it are no longer perceptible, then it is no longer referred to as translucent, but rather as opaque or opacifying.
Instead of using non-spherical, especially platelet-like second effect pigments, it can also be provided that the second effect pigments are formed by isotropic particles that are present in microcapsules and that align

- 7 -cooperatively, that is, e.g., chain-like, in the microcapsules through an external magnetic field. In this way, dynamic optical effects can likewise be produced. Here, the isotropic particles can be developed as nanoscale particles having a particle size of 1 nm up to 1 gm, or can alternatively exhibit particle sizes of more than 1 gm, the particle size especially being between 1 gm and 20 gm, preferably between 2 gm and 10 gm. The diameter of the microcapsules is advantageously between 1 gm and 200 gm, especially between 5 gm and 80 gm, and is preferably coordinated with the particle size of the isotropic particles in such a way that, upon magnetic alignment, in each case, multiple isotropic particles can lie against one another cooperatively, especially chain-like, in the microcapsules.
In an advantageous development of the present invention, the second effect pigments are formed by coated iron pigments. Here, the iron pigments exhibit especially the composition FeO, where x is between 1.3 and 1.5. Due to the coating, in addition to their magnetic alignability, the second effect pigments are provided with a further desired property. In the simplest case, the coating is a coloring coating that includes, for example, yellow, green and/or blue organic and/or inorganic colorants and preferably, in addition, a white pigment having a high scattering power. Also other coatings, such as laser-markable, fluorescent or phosphorescent coatings may be considered in order to lend the effect pigments the appropriate properties.
The encapsulation of the second effect pigments can occur, for example, in that iron pigments of a suitable size are selected, such as in the size range of 10 gm to 20 gm, are dispersed in a water-insoluble solvent, suitable micellar precursors having a controlled particle size are prepared in water, and these are encapsulated, for example, with acrylated gelatine through coacervation.

- 8 -General information on rnicroencapsulation and on coacervation is set forth e.g. in EP 1 479 432 B1.
Also other methods for the encapsulation are, of course, possible, such as emulsion polymerization with acrylates, methacrylates or styrene.
The microcapsules described in this application can consist of a number of different organic or inorganic materials. To ensure the required optical and mechanical properties, especially the capsule material, and if polymers are used, also their degree of crosslinking and the wall thickness of the microcapsules can be adjusted. Advantageous capsule materials include, for example, gelatin, modified gelatin, especially with chemical postcrosslinking, PMMA and other polyacrylates that are well suited, primarily due to their high transparency, polyurethanes, polyamides, melanin! formaldehyde, silicones, but also inorganic oxide materials, such as silicates, titanium, hafnium or iron oxides.
According to the present invention, the diameter of the microcapsules is advantageously between about 1 gm and about 200 gm, especially between about 1 gm and about 80 gm. The wall thickness of the microcapsules is typically between 5% and 30%, preferably between 10% and 20% of the diameter of the microcapsules.
The first effect pigments are advantageously pigments manufactured on the basis of liquid crystal polymers, or so-called pearlescent pigments, such as the silvery-white, gold luster or metallic luster pigments sold under the name Iriodin(R) or Colorcrypt by Merck KGaA. Both pigments on the basis of liquid crystal material and pearlescent pigments are per se translucent. In another, likewise advantageous embodiment of the present invention, the

- 9 -first effect pigments are formed by interference layer pigments. Such interference layer pigments typically exhibit a thin-film structure that expediently includes at least one reflection layer, one absorber layer and one dielectric spacing layer arranged between the reflection layer and the absorber layer. Interference layer pigments can, per se, be translucent, even if opaque interference layer pigments are also known.
In one development of the present invention, the second effect pigments are encapsulated in microcapsules, the microcapsules including an activatable fixative through whose activation the second effect pigments are fixable in a desired position. Such a design makes it possible to partially or completely fix in a desired position, at a later time, the second effect pigments in order to introduce, for example, an individual marking into the security element. In this way, a printed layer having the second effect pigments can still be magnetically aligned also after the drying of the layer, and for example through local UV irradiation or through local laser irradiation, be fixed in the form of patterns, characters or a code in a desired position in sub-regions.
If the second effect pigments are subsequently fixed only in sub-regions, then a combination effect is created in which the non-fixed regions react reversibly to external magnetic fields, while the magnetic alignment in the regions impinged on with, for example, UV or laser radiation, is permanently fixed.
Here, in an advantageous embodiment, the microcapsules include, as the activatable fixative, a transparent polymerizable mixture or substance, and to activate the fixative, an initiator, preferably a photoinitiator. For this, upon microencapsulation, which preferably occurs through colloidal coacervation or microemulsion polymerization, the second effect pigments can be

- 10 -suspended, for example, in a 100% system composed of mono- and oligomers and photoinitiator. Here, the polymerization conditions, such as micelle or drop size, are chosen such that microcapsules of the desired size (1 1.tm to 200 tam, preferably 5 gm to 80 m) are created. The viscosity of the mixture can be adjusted both through the choice of the type of mono- or oligomer and through the variation of its ratio.
Through suitable choice of the polymerization conditions, both microcapsules having completely fixed effect pigments can be produced, and microcapsules having gel structures that preferably consist of a mixture of photopolymerizable mono- and oligomers and a suitable solvent, in which the effect pigments can still be rotated through an external magnetic field and for which the gel structure exerts a restoring force on the rotated effect pigments, as explained in greater detail above.
Alternatively, the microcapsules can also include a largely inert filling with added, short, chain-like reactive molecules that, upon irradiation, crosslink with themselves and with the capsule wall and fix the effect pigment included in the microcapsule in its position.
According to a further possibility, also laser-destructible nanocapsules can be introduced into the microcapsules with a polymerization starter such that the fixation can be triggered by laser radiation.
In a further variant, the microcapsules include liquids or pigments that can be decomposed by laser radiation and, for example, foam up. Here, the effect pigments included in the microcapsules are permanently fixed in their position by the resulting increase in volume of the fixative. One advantage of

- 11 -such a variant consists in that no subsequent crosslinking can occur, for example through leakage of polymerization starter or through UV light.
Examples of activatable fixatives that are suitable for foaming up through the action of laser radiation and/or through a high temperature include polymers, such as POM (polyoxymethylene), PMMA (poly(methyl methacrylate)) or PA (polyamide), which, due to their decomposition properties, already tend to foam up without further additives. Furthermore, also other plastics can be used, such as polystyrene, polyester or PET, to which a blowing agent is added to produce the desired foamability. As the blowing agent, sodium carbonate, diphenyloxide-4-4'-disulphohydrazide or the blowing agents of the product series Genitron(R) or Ficel(R) from Lanxess, for example, may be used. Alternatively, also foamable hollow spheres can be used. To increase the laser sensitivity of the foamable polymers, in addition, absorbers can be added for the wavelength range of the laser used.
In an advantageous development of the present invention, the optically variable ink layer can further include third, unencapsulated and magnetically alignable effect pigments that are magnetically aligned in the form of a specified motif in the form of patterns, lines, characters or a code.
Unlike the alignment of the second effect pigments, the alignment of the third effect pigments here is permanently fixed. For the third effect pigments, except for the lack of encapsulation, the same materials may be used with the same size ranges and properties as for the second effect pigments, such that the above statements in this regard also apply to the third effect pigments.

- 12 -The encapsulated second effect pigments and the tmencapsulated third effect pigments can be present at least partially in the same regions of the optically variable ink layer and/or at least partially in separate regions of the optically variable ink layer. In both variants, conspicuous visual effects having a high recognition value can be produced, as explained in greater detail below.
In a preferred embodiment of the present invention, the optically variable ink layer includes a pigment mixture having the first effect pigments, the encapsulated second effect pigments and, if applicable, the unencapsulated third effect pigments. Alternatively, the optically variable ink layer can consist of multiple stacked sub-layers that each include only one type of effect pigment.
The optically variable ink layer is preferably formed by a screen printing layer or flexo printing layer, in some embodiments also by an intaglio printing layer. In all cited embodiments, it can, in addition, be blind embossed, especially to intensify the 3D effect of the magnetically aligned effect pigments.
To permanently fix the magnetically aligned motif of the third effect pigments, the ink layer is preferably formed on the basis of a UV-curing color system, with purely UV systems, UV/water-based systems or also UV/solvent-based systems being able to be used. In addition to the first, second and, if applicable, third effect pigments, the ink layer can also include further pigments, especially isotropic pigments and/ or magnetically soft pigments. Of course the further pigments or, in general, further additives can exhibit visually and/or machine-perceptible properties that do not affect the described visual effects of the security element according to the present invention, or affect them only marginally.

- 13 -In an advantageous embodiment, the optically variable ink layer is applied on a standard banknote paper or on a colored background layer. Any type of paper may be used as the substrate material for the banknote paper, especially cotton vellum paper. Of course, also paper that includes a proportion x of polymer material can be used, where x can be between 0 and 100 wt. %.
The substrate material of the banknote or, in general, of a data carrier can also be a plastic foil, such as a polyester foil. The foil can be stretched monoaxially or biaxially. A stretching of the foil causes it to, among other things, obtain light-polarizing properties that can be used as a further security feature. The substrate material can also be a multilayer composite that includes at least one layer composed of paper or a paper-like material.
Such a composite, which can also be used as a substrate material for banknotes, is characterized by an extraordinarily high stability, which is highly advantageous for the durability of the note or data carrier.
Further, as the substrate material, a multilayer, paper-free composite material can be used that, especially in some climate regions of the earth, can be used advantageously.
All substrate materials can include additives that can serve as authenticity features. Here, especially luminescent substances may be used that are preferably transparent in the visible wavelength range and, in a non-visible wavelength range, can be excited through suitable auxiliary means, such as a UV- or IR-radiation-emitting source, to produce a luminescent radiation that is directly visible or detectable with auxiliary means.

- 14 -Background layers having dark colors normally lead to a particularly high brilliance of the optically variable effects. However, also a transparent or translucent foil can be used as the substrate. In this case, the security element can advantageously be used in or over a window region or a through opening of a value document as a see-through security element. The foil can be developed as a patch that covers a sub-area of the substrate, or as a strip that extends across the entire length or width of the data carrier. As materials for the foil, primarily the plastics PET (polyethylene terephthalate), PBT
(polybutylene terephthalate), PEN (polyethylene naphthalate), PP
(polyproyplene), PA (polyamide) and PE (polyethylene), may be used.
Further, the foil can be stretched monoaxially or biaxially, as already explained above.
An opening in a banknote can already be produced at manufacture of the security paper used for the banknote, and then exhibits a fibrous, irregular edge. Such an edge is characteristic for openings already manufactured at sheet formation and cannot be produced subsequently. Details on the manufacture of such irregular edges are set forth in publication WO
03/054297 A2, the disclosure of which is incorporated herein by reference. In other embodiments, the opening is produced only after paper manufacture by punching or cutting, for example by laser cutting.
In one development of the present invention, the optically variable ink layer can be applied on an information-bearing background layer, especially a screen printing, flexo printing or an intaglio printing layer. Since the information is perceptible in the translucent regions of the ink layer, but is covered in the opaque regions, the ink layer and background layer can coact to produce a further authenticity feature, as explained in greater detail below.

- 15 -The background layer can advantageously also exhibit thermochromic properties to create a security element that is interactively influenceable in a further way. Such a thermochromic background layer can especially be designed such that, when it is activated through a temperature increase, the optically variable effect of the first effect pigments disappears for the viewer.
According to one development of the present invention, the optically variable ink layer is combined with a magnetic background layer that can be present contiguously or in the form of patterns, characters or a code.
Through such a magnetic background layer, it can be achieved that the optically variable ink layer already displays a desired motif without an external magnetic field, or that an initially hidden motif is exposed by an external magnetic field.
In a first variant, the magnetic background layer includes a magnetically soft substance of low to negligible remanence that is arranged in the form of a motif, for example in the form of patterns, characters or a code. Due to its low remanence, the magnetically soft substance itself is not permanently magnetizable, so retains no magnetization after cessation of an external magnetic field.
If the security element is exposed to an external magnetic field, then the magnetic background layer largely shields the magnetic field in the regions in which the magnetically soft substance is present, such that the second effect pigments there are influenced only a little or not at all. Through the emerging, locally different alignment of the second effect pigments, the external magnetic field exposes the motif that is present in the magnetic background layer and makes it perceptible for the viewer. Thus, through the

- 16 -magnetic background layer, a reversibly displayable, magnetic motif is produced without the external magnetic field having to exhibit the motif shape. Rather, the verification can occur with common, widespread magnets, such as with the permanent magnets of a mobile phone, of a portable audio playback device or of a product security system.
Pigments having the desired magnetically soft properties include, for example, soft ferrites, such as Zn-Mn ferrite, or various amorphous, crystalline or nanocrystalline metals or metal alloys that are known to the person of skill in the art for shielding static or low-frequency magnetic fields.
Here, the pigments are preferably imprinted in the form of a magnetic printing ink. The markedness of the effect can be adjusted especially via the pigmentation of the printing ink and the thickness of the imprinted layer.
In a second variant, the magnetic background layer includes a magnetic substance, having a medium to high coercive field strength, that can be present contiguously or in the form of a motif. Here, the coercive field strength is typically between 50 kA/m and 300 kA/m. Such a magnetic substance can still be magnetized or remagn.etized relatively easily by an external magnetic field. The initial magnetization in the form of a desired motif can be produced, for example, with a strong permanent magnet. Due to the remanence of the magnetic material, also after cessation of the external magnetic field, a magnetization is retained that is strong enough to keep the reversibly alignable second effect pigments in their position.
Suitable materials for this variant include, for example, mixtures of hard and soft ferrites or sintering materials and alloys, such as AlNiCo, CuNiFe or chrome-cobalt steels.

- 17 --According to a third variant of this aspect of the present invention, the coercive field strength of the magnetic substance is chosen to be so large that it no longer permits remagnetization through standard permanent magnets, but rather that very strong fields are required for this, such as can be produced, for example, with strong electromagnets or through flash magnetization. Here, the coercive field strength of the magnetic substance is above 300 kA/m.
In this variant, at manufacture of the security element or in a subsequent individualization step, there can, for example, be magnetized into the magnetic background layer a motif that cannot be removed by the means usually available to a user. Through the alignment of the second effect pigments, a visible, permanent magnetic pattern is created that can be intensified or weakened by an external magnetic field.
Suitable materials for this variant include, for example, anisotropic and especially isotropic magnetic powders based on hard ferrite, such as barium or strontium ferrite, or magnetic powder based on sintering materials and alloys, such as NdFeB or SmCo. Also HiCo (high coercivity) materials from the field of magnetic cards may be considered, since these exhibit a coercive field strength up to 4000 Oe (about 320 kA/m).
The application of a magnetic background layer to a paper substrate can occur directly through printing an ink that includes the magnetic substances cited in the first to third variant in the highest possible pigmentation in the range of about 15% to 50%. To achieve the highest possible layer thicknesses and thus an intense effect, the ink is preferably applied in screen or intaglio printing.

- 18 -The application of the magnetic background layer to a foil substrate opens up further possibilities. In this way, with known methods, one or more layers composed of magnetic materials can be applied to a foil. For example, the foil can be evaporated with a magnetic metal layer, for instance composed of iron or nickel, demetalized in the form of a desired motif, and over- or underprinted with an optically variable ink layer of the kind described. Through vacuum methods, to a foil can also be applied various non-metallic layers or metallic alloys that exhibit the desired magnetic properties with respect to coercive field strength, remanence and the like.
The present invention also comprises a method for manufacturing an optically variable security element for securing valuable articles, in which, to a substrate, an optically variable ink layer is applied that includes first, optically variable effect pigments for producing a viewing-angle-dependent visual impression, and that includes second effect pigments that are reversibly alignable by an external magnetic field, the degree of markedness of the viewing-angle-dependent visual impression of the optically variable effect pigments depending on the orientation of the magnetically alignable effect pigments relative to the plane of the ink layer. Here, the second effect pigments are preferably encapsulated, such that they are substantially freely rotatable in their encapsulation.
In an advantageous development of the method, an optically variable ink layer is applied that further includes, in addition to the first and second effect pigments, third, unencapsulated and magnetically alignable effect pigments, the third effect pigments being permanently aligned by an external magnetic field to form a motif in the form of patterns, lines, characters or a code.

- 19 -Advantageously, the first, second and, if applicable, third effect pigments are mixed to form a pigment mixture and printed together, preferably in the screen printing, flexo printing or intaglio printing technique. Alternatively, first a purely magnetic layer having the second effect pigments can be imprinted on the substrate, and over the purely magnetic layer, a purely ink layer printed with the first effect pigments. If appropriate, a further layer having the third effect pigments can be provided.
The motif of the third effect pigments, which is produced by the magnetic alignment, is advantageously permanently fixed by UV curing.
The present invention further includes a security arrangement for securing security papers, value documents and the like, having a security element of the kind described and having a verification element having a magnetic motif region in which magnetic material is present in the form of patterns, lines, characters or a code. Here, the magnetic motif region is particularly advantageously magnetized substantially vertically to the plane of the verification element. The motif depicted by the magnetic motif region can be openly visible or also not be perceptible without auxiliary means, for example by covering with a dark printing layer.
In addition to the use of motif magnets for verification of the security elements according to the present invention, also the use of other magnets for verification may be considered. For example, nearly all modern mobile phones include strong permanent magnets in the loudspeakers. Also portable audio playback devices or their head- or earphones, as well as product security systems at the point of sale, often include permanent magnets of sufficient strength. Due to their wide prevalence, these magnets are available to the user almost everywhere and can, especially with security

- 20 -elements that include an above-described magnetic background layer, advantageously likewise be drawn on for the verification of security elements according to the present invention.
The present invention also comprises a data carrier, especially a value document, such as a banknote, a passport, a certificate, an identification card or the like, that is furnished with a security element of the kind described or with a security arrangement of the kind described. The security element can, especially if it is present on a transparent or translucent substrate, also be arranged in or over a window region or a through opening of the data carrier.
If the data carrier includes both a security element according to the present invention and an associated verification element, then these are advantageously arranged geometrically on the data carrier in such a way that the security element is bringable over the verification element by bending or folding the data carrier.
A further object of the present invention is a verification device for checking the authenticity of a security element of the kind described, having a magnetic motif region in which magnetic material is present in the form of patterns, lines, characters or a code, and that is magnetized substantially vertically to the plane of the motif region in order to magnetically align the second effect pigments of the optically variable ink layer of the security element.
Further exemplary embodiments and advantages of the present invention are explained below by reference to the drawings, in which a depiction to scale and proportion was omitted in order to improve their clarity.

- 21 -Shown are:
Fig. 1 a schematic diagram of a banknote having a security element according to the present invention, Fig. 2 the security element in fig. 1 together with a verification device, where, in (a), the security element and verification device are spatially separated, and in (b), the security element rests on the verification device, Fig. 3 a cross section through a security element according to an exemplary embodiment of the present invention, in the left half of the image without verification device and in the right half of the image with, Fig. 4 a security element according to another exemplary embodiment of the present invention in a cross-sectional diagram as in fig. 3, Fig. 5 a security element according to a further exemplary embodiment of the present invention, in cross section, Fig. 6 top views of a section of the security element in fig. 5, in (a) without verification device and in (b) with verification device, Fig. 7 a security element according to yet a further exemplary embodiment of the present invention, in cross section,

- 22 -Fig. 8 a banknote having a security arrangement according to the present invention, composed of a security element and a verification element arranged mirror-symmetrically relative to the centerline, Fig. 9 a security element according to a further exemplary embodiment of the present invention in a cross-sectional diagram as in fig. 3, Fig. 10 a security element according to the present invention, having a magnetically soft background layer upon verification with an external magnet, and Fig. 11 a security element according to the present invention, having a magnetic background layer having a magnetic substance having a medium to high coercive field strength.
The invention will now be explained using a banknote as an example. For this, fig. 1 shows a schematic diagram of a banknote 10 having an optically variable security element 12 that is imprinted directly on the banknote paper.
It is understood that the present invention is not limited to imprinted security elements and banknotes, but can be used in all types of security elements, for example in labels on goods and packaging or in securing documents, identity cards, passports, credit cards, health cards and the like.
In banknotes and similar documents, besides, for example, imprinted elements, also transfer elements, security threads or security strips may be used, and besides top view elements, also see-through elements may be used.

- 23 -In fig. 2, the optically variable security element 12 is depicted together with an external verification device 20, the security element 12 and the verification device 20 being clearly spatially separated from each other in fig. 2(a), while the security element 12 in the diagram in fig. 2(b) rests on the verification device 20.
As depicted in fig. 2(a), without the verification device 20 or with a sufficient spatial separation from the verification device 20, the optically variable security element 12 displays a metallic gloss that is combined with a weakly pronounced, consistent color-shift effect. With the color-shift effect, the color impression of the security element changes for the viewer upon tilting the security element, for example from green when viewed vertically from above to blue when viewed obliquely. However, also other color shifts are conceivable, such as from copper-colored to green or from gold-colored to green.
The verification device 20 for the security element 12 exhibits a motif magnet 22 whose magnetization is indicated by the magnetic field lines 24 drawn in.
The magnetic material of the motif magnet 22 is arranged in the form of patterns, lines, characters or a code and forms, in the exemplary embodiment, the letter "H". Here, the magnetic north pole constitutes the top of the magnet and the magnetic south pole the bottom of the magnet, such that the magnetization of the motif magnet stands substantially vertical to the plane of the magnetic material. It is understood that, in the general case, the motif magnet of the verification device 20 can depict arbitrary patterns, characters or codes and that its magnetization can also be reversed or formed by a more complex sequence of magnetic north and south poles. For a high magnetization, besides conventional magnet materials, especially also magnetic rare earth alloys, such as samarium-cobalt or neodymium-iron-

- 24 -boron alloys, may be used for the magnetic material of the motif magnet. The present invention also includes embodiments that can be verified without special motif magnets, as described in greater detail below.
If the user brings the security element 12 immediately over the verification device 20, as shown in fig. 2(b), then in this way, he interactively changes the visual appearance of the security element 12 in the region 26 over the motif magnet 22. The metallic gloss of the region 26 is significantly reduced and a dark background layer becomes visible. At the same time, the color-shift effect in the region 26 gains considerably in brilliance and intensity.
Instead of a consistently dark background, a piece of information, for example lettering, a serial number, a denomination specification or the like, can also be visible in the region 26. In the region 28 away from the motif magnet 22, the visual impression of the security element 12 remains unchanged. The motif depicted by the motif magnet 22 is thus characteristically reflected in the region 26 as an image-like, brilliant color-shift region against a metallic background.
If the security element 12 and the verification device 20 are distanced from each other again, the state shown in fig. 2(a) returns, such that the viewer then again sees a consistently metallically gleaming surface having a weakly pronounced color-shift effect. The security element 12 thus exhibits a reversible and interactively triggerable authenticating mark.
The structure of the security element 12 and the occurrence of the reversible change in the visual appearance will now be explained in greater detail with reference to the cross-sectional diagram in fig. 3. Here, the left half of the image in the figure shows the security element 12 without the verification

- 25 -device 20, or a region 28 away from the motif magnet 22. The right half of the image shows a section of the security element region 26 that is arranged immediately over the motif magnet 22.
To the banknote paper 30 of the banknote 10 is applied, in the region of the security element 12, a printing layer 32 that can depict an arbitrary piece of information, such as a line pattern 33, an alphanumeric character string, a logo or the like. The printing layer 32 can also, as in the exemplary embodiment in fig. 2, form a contiguously dark, for example black, background layer. The printing layer 32 can especially be applied to the banknote paper 30 by means of screen printing, flexo printing or intaglio printing.
In the present case, over this generally information-bearing printing layer 32 is imprinted, in the screen printing method using a pigment mixture composed of first effect pigments 34 and second effect pigments 36, an optically variable ink layer 40 having a color-shift effect.
The first effect pigments 34 are optically variable pigments, for example interference layer pigments having a thin film structure composed of a reflection layer, an absorber layer and a dielectric spacing layer arranged between the reflection layer and the absorber layer. Also pigments manufactured on the basis of liquid crystal polymers or iridescent pearlescent pigments, as sold by, for example, Merck KGaA under the name Iriodin(R) or Colorcrypt, may be used as the first effect pigments 34.
Besides these optically variable first effect pigments 34, the pigment mixture includes as second effect pigments magnetically alignable, platelet-like iron pigments 36 that, in the exemplary embodiment, are manufactured from

- 26 -carbonyl iron powder treated under reducing conditions. Such platelet-like iron pigments can be produced having a high ratio of platelet diameter to platelet thickness, the (largest) platelet diameter being preferably between 6 p.m and 60 [tin, especially between 101.1m and 20 rim, and the platelet thickness especially between 40 nm and 250 nm. Details of the manufacture and properties of such platelet-like iron pigments are set forth in publication EP 1 251 152 B1, the disclosure of which is incorporated in the present description by reference.
As a distinctive feature, the second effect pigments 36 are encapsulated and substantially freely rotatable in their encapsulation 38. Without an external magnetic field, the second effect pigments 36 ideally exhibit no preferred orientation within their encapsulation 38, such that the whole of the second effect pigments displays a substantially isotropic orientation. It is understood that, in practice, certain deviations from an ideal isotropic alignment can occur, depending, for example on the geometric shape, the magnetizability, the viscosity of the encapsulation liquid or the structure of the encapsulation.
This substantially isotropic alignment of the second effect pigments 36 corresponds to the situation shown in the left half of the image in fig. 3, with only four different general alignments of the pigments 36 being depicted there for illustration.
If the security element 12 is now brought over the motif magnet 22 of the verification device 20, then the magnetically alignable second effect pigments 36 are aligned by its magnetic field. Here, the iron pigments 36 align with their platelet expanse along the magnetic field lines 42. Due to the shape and magnetization of the motif magnet 22 indicated in fig. 2, the magnetic field lines 42 in the region 26 pass substantially vertically through the ink layer

- 27 -and align the iron pigments 36, which are freely rotatable in their encapsulation, likewise substantially vertically to the plane of the ink layer 40, as shown in the right image portion in fig. 3.
Due to their platelet-like form, the iron pigments 36 act for the viewer like the slats in a window blind that can reveal the view of the underlying layers or fully or partially block it. In the regions 28 in which the iron pigments are arranged substantially isotropically (left half of the image in fig. 3), they restrict the view of the underlying printing layer 32 so severely that the ink layer 40 appears opaque in this region and the metallic gloss of the iron pigments 36 dominates the visual impression of the security element.
Through the superimposition with the metallic gloss of the second effect pigments 36, the color-shift effect of the first effect pigments 34 visually recedes into the background and thus appears only weakly pronounced. It is understood that, in practice, the opaque effect of the isotropically oriented iron pigments 36 is produced by the multitude of pigments present, which exceeds the few pigments 36 in the schematic diagram in fig. 3 by many times.
In the region 26, in which the iron pigments 36 are aligned substantially vertically to the plane of the ink layer 40 by the motif magnet 22, they reveal, like the parallel-set slats of a window blind, the view of the underlying printing layer 32 and a piece of information 33 present there, if applicable.
The color-shift effect of the first effect pigments 34, which are not influenced by the external magnetic field, is, in principle, present in both sub-regions and 28. However, due to the superimposition with the metallic gloss of the isotropically oriented second effect pigments 36, it is normally significantly more weakly pronounced in the sub-region 28 than in the sub-region 26. The

- 28 -brilliance of the color-shift effect in the sub-region 26 also depends on the design of the background layer 32, a particularly high brilliance being achieved when dark inks are used.
Due to the relatively high ratio of platelet diameter to platelet thickness, it is possible to produce a high contrast between opaque sub-regions 28 and translucent sub-regions 26. Furthermore, the motif produced by the platelet orientation in the sub-regions 26, 28 appears for the human eye having an impactful, three-dimensional-seeming appearance that is also referred to, in the context of this description, as a 3D effect or 3D impression of the motif.
If the verification device 20 is removed from the security element 12 again, then, after some time, the magnetically aligned iron pigments 36 relax again, due to their free movability within the encapsulation 38, into the substantially isotropic initial state of the left half of the image in fig. 3.
In this way, the change in the visual appearance of the security element 12 can be interactively triggered and reversibly withdrawn again. However, without a restoring force, the return to the isotropic initial state can take several minutes, hours or even days. In the event that a quicker return is desired, there can, as described above, be provided within the encapsulation 38 a gel, for example, that provides a restoring force for the magnetically alignable iron pigments 36.
For the production of the ink layer 40, the second effect pigments 36 were first encapsulated 38, the encapsulated effect pigments 36, 38 then mixed with the first effect pigments 34 and printed together in screen printing. The encapsulation of the second effect pigments can occur, for example, in that iron pigments of suitable size are selected, are dispersed in a water-insoluble solvent, suitable micellar precursors having a controlled particle size are

- 29 -prepared in water, and these are encapsulated with acrylated gelatin through coacervation. Also other capsule materials, as described above, are conceivable.
The further exemplary embodiment in fig. 4 shows a security element 50 that permits an additional interactive influencing of the visual appearance, for example through touch. For this, a substrate 52 is provided with an imprint 54, especially an offset imprint in the form of patterns, lines, characters or a code 56. On the imprint 54 is applied, in screen printing, flexo printing or intaglio printing, a thermochromic background layer 58, and on the thermochromic layer 58 is imprinted an optically variable ink layer 40 having first 34 and second effect pigments 36, as described in connection with fig. 3.
Here, the thermochromic layer 58 is designed such that the color-shift effect of the ink layer 40 disappears for the viewer upon activation of the thermochromic layer 58, and only the basic structure of the iron pigments 36 is visible. If the thermochromic layer 58 changes its color, for example upon activation through temperature increase, from black (or generally a dark appearance) to white (or generally a light appearance), then the brilliance of the color-shift effect upon activation is significantly reduced, up to a degree at which the optically variable effect of the first effect pigments 34 completely disappears for the viewer. At the same time, the imprint 54, 56 is perceptible for the viewer through the then very light layer 58.
Upon cooling, the color of the thermochromic layer 58 changes back to black or to the original dark appearance again, the color-shift effect of the ink layer 40 then appears again clearly and the dark layer 58 covers anew the imprint 54, 56 arranged under it.

- 30 -In this way, a 3D piece of information made visible with the aid of the verification device 20 can be interactively removed through a temperature increase, or reduced to a two-dimensional piece of information. Here, the thermochromic layer 58 acts as an interactive switch with which the view of the imprint 54 or the piece of information 56 can be revealed for the viewer.
The thermochromic layer 58 can be developed to be contiguous, or be provided with a piece of information, for example in the form of patterns, lines, characters or a code. It can also exhibit a mixture of different thermochromic inks having different activation temperatures such that, upon a temperature increase, a cascade of changing optically variable effects is created.
While, in the exemplary embodiments in figures 3 and 4, the first effect pigments 34 are present outside the encapsulation 38 of the second effect pigments 36, the first effect pigments can also be encapsulated in microcapsules together with the second effect pigments, as shown in fig. 9.
Here, the structure of the security element 100 in fig. 9 largely corresponds to the structure already described for fig. 3. However, in contrast to this, the platelet-like first effect pigments 102 manufactured on the basis of liquid crystal polymers are encapsulated in microcapsules 106 together with the platelet-like iron pigments 104. In this embodiment, upon alignment, the orientation of the first effect pigments 102 changes together with the orientation of the second effect pigments 104, such that dynamic optical variable effects result. Through the joint rotation, also here, particularly the degree of markedness of the viewing-angle-dependent visual impression of the first effect pigments 102 changes with the orientation of the second effect pigments 104 relative to the plane of the ink layer 40.

- 31 -In the further exemplary embodiment in fig. 5, the security element 60 includes an optically variable ink layer 40 that, in addition to the first effect pigments 34 already described in connection with figures 2 to 4 and the encapsulated second effect pigments 36, 38, further includes third, unencapsulated, magnetically alignable effect pigments 62, 64. The third effect pigments are magnetically aligned in the form of a specified motif, a simple strip motif composed of alternating strips 66, 68 being shown for illustration in the exemplary embodiment shown in fig. 5.
Unlike the alignment of the second effect pigments, which can be interactively and reversibly changed by the user with the aid of a suitable verification device, the alignment of the third effect pigments 62, 64 is unchanging and permanently fixed. As materials for the third effect pigments, as for the second effect pigments, especially magnetically alignable, platelet-like iron pigments 62, 64 may be used that can be manufactured from carbonyl iron powder treated under reducing conditions and that preferably exhibit the sizes and properties already specified in the description of the second effect pigments. The second and third effect pigments introduced into the ink layer can also be identical except for the missing encapsulation of the third effect pigments.
For the manufacture of the ink layer 40, the first effect pigments 34, the encapsulated second effect pigments 36, 38 and the unencapsulated third effect pigments 62, 64 were mixed and printed together in screen printing.
Then a suitable external magnetic field having the form of the desired motif was applied to magnetically align the third effect pigments. As already described above, the magnetically alignable iron pigments 36, 62, 64 align themselves in the external field with their platelet expanse along the

- 32 -magnetic field lines such that, in those regions 68 in which, in the alignment step, the magnetic field lines stand vertical to the substrate plane, the iron pigments 64 are aligned substantially vertical to the plane of the ink layer and, accordingly, in the regions 66 in which the magnetic field lines run parallel to the substrate plane, an orientation of the iron pigments 62 lying substantially in the plane of the ink layer results, as depicted in fig. 5.
The ink layer 40 is then dried with the still magnetically aligned iron pigments 36, 62, 64. Here, to permanently fix the magnetically produced motif of the third effect pigments 62, 64, especially UV-curing color systems are used, with purely UV systems, UV/water-based systems or also UV/solvent-based systems being able to be used. Through the drying step, the aligned, unencapsulated third effect pigments 62, 64 are permanently fixed in their orientation, while the encapsulated second effect pigments 36, due to their free rotatability within the encapsulation, return again to a substantially isotropic alignment distribution after the removal of the external magnetic field.
Upon viewing the security element 60 without the verification device 20, its visual impression is dominated by the isotropically distributed and thus opaque-appearing second effect pigments 36. As depicted in the top view in fig. 6(a), the security element 60 without verification device thus displays a metallic gloss that is combined with a weakly pronounced, consistent color-shift effect.
If the security element 60 is brought over the verification device 20 having the motif magnet 22, then the movable and magnetically alignable second effect pigments 36 are aligned in some regions, by the magnetic field of the verification device, vertically to the plane of the ink layer 40, as already

- 33 -described in connection with fig. 3. The permanently fixed third effect pigments 62, 64 and the non-magnetic first effect pigments 34 are not influenced by the magnetic field of the verification device 20.
In the strip regions 68, both the second effect pigments 36 and the third effect pigments 64 are then oriented vertically to the plane of the ink layer 40 such that the view of the printing layer 32 is revealed there. In contrast, in the strip regions 66, the third effect pigments 62 oriented parallel to the plane of the ink layer block the view through, the ink layer 40 remains opaque there also in the presence of the verification device 20.
In this way, as depicted in the top view in fig. 6(b), for one, the verification device 20 reveals, within the region of the motif magnet 22, the permanently fixed magnetic motif 66, 68 that, due to its occurrence through the different alignments of platelet-like pigments 62, 64, exhibits a pronounced 3D effect for the viewer. In fig. 5, for the sake of simplicity, only two orientations of the third effect pigments 62, 64 are shown, but it is understood that, through appropriate orientation of the magnetic field lines in the alignment step, it is possible to set arbitrary angles between the iron pigment platelets and the plane of the ink layer, and thus also to produce complex, magnetic motifs.
If the printing layer 32 includes a piece of information 33, in the shown exemplary embodiment for instance the repeating numeric string "10," then, for another, this piece of information 33 becomes visible in the sub-regions of the strips 68 that lie over the motif magnet 22, while it always remains covered in the opaque-appearing strips 66. Through a movement of the motif magnet 22 over or under the security element 60, the user can interactively and reversibly make visible the initially hidden 3D motif 66, 68 and the piece of information 33 of the printing layer 32 across the entire region of the

- 34 -security element 60. Such an interactive embodiment has a high recognition value for the viewer and thus generally exhibits a very high counterfeit security.
The second and third effect pigments can also be present in separate regions of a security element 70, as shown in the exemplary embodiment in fig. 7.
The security element 70 includes in a sub-region 72 a permanently fixed magnetic motif 74, 76 having a 3D effect that, as already explained for fig.
5, is produced by the different magnetic alignments and subsequent fixation of unencapsulated iron pigments 78.
In a further sub-region 80, the iron pigments 82 are present in encapsulated form and thus reversibly alignable. In the sub-region 80, the visual appearance of the security element 70 can then be interactively changed with the aid of a verification device 20. In particular, for this purpose, a verification device 20 having a motif magnet can be used whose motif corresponds to the permanently fixed magnetic motif 74, 76. When checking the authenticity, then, in addition to the 3D motif 74, 76, the same motif is depicted again interactively in the region 80, such that a self-explanatory security element having a high attention value is created.
It is understood that also the embodiments in figures 5 and 7 can, if needed, be combined with a thermochromic background layer to create a further interaction possibility.
In the embodiments described so far, the authenticity check of the security element applied to the banknote 10 occurs in each case with a separate verification device 20. However, for the authenticity check, it is also possible to provide a verification element on the banknote itself such that the security

- 35 -element and the verification element form a cohesive security arrangement, as now explained with reference to the exemplary embodiment in fig. 8.
The banknote 90 shown in fig. 8(a) includes a security element 92 of the kind described above, and a verification element 94 that, with respect to the centerline 96 of the banknote 90, is applied mirror-symmetrically to the security element 92. The verification element 94 exhibits a magnet region 98 in which magnetic material is present having a magnetization vertical to the paper plane and in the form of a desired motif, such as the crest depicted by way of example in fig. 8(a). The motif form of the magnet region 98 can be openly visible or also be covered, for example by a dark overprint.
By folding the banknote 90 about the centerline 96, the verification element 94 having the magnet region 98 comes to lie on the security element 92, as shown in fig. 8(b). The magnetization of the magnet region 98 then interactively and reversibly changes the visual impression of the security element 92 in the manner described above. For example, the visual appearance of the security element 92 can change from a uniform metallic gloss having a weakly pronounced, consistent color-shift effect (fig. 8(a)) to a motif depiction of a crest in which the inside of the crest stands out dark and having a brilliant, clearly pronounced color-shift effect. In the inside of the crest, also further information can be visible, such as the denomination of the banknote. The banknote 90 can thus be checked for authenticity by simple folding, without external verification means being required.
If the security element and the verification element will be arranged on the same data carrier, it is particularly appropriate to coordinate the motif that appears when checking the authenticity with a motif that is openly visible on the data carrier, such as the denomination of a banknote, an imprinted logo

- 36 -or the like, since the authenticity check is then self-explanatory for the user and a particularly easy distinguishability and verifiability is ensured.
It is possible to produce further interesting effects with embodiments in which the optically variable ink layer 40 is combined with a magnetic background layer that can be present contiguously or in the form of patterns, characters or a code. For the security element 110 in fig. 10, on a substrate composed of paper or foil is applied a magnetic background layer 114 that exhibits, in the form of a desired motif, regions 116 having a magnetically soft substance 120 of low or negligible remanence. Over the magnetic background layer 114 is arranged an optically variable ink layer 40 having encapsulated, magnetically alignable effect pigments 122 of the kind described above. The likewise present first effect pigments are not shown in fig. 10, to improve diagram clarity.
With an isotropic alignment of the effect pigments 122, the motif formed by the magnetic background layer 114 is not perceptible without an external magnetic field. If the security element 110 is now exposed to the magnetic field of an external magnet 124, then the magnetic background layer 114 largely shields the external magnetic field in the regions 116. The magnetically alignable effect pigments 122 are thus not influenced in these regions 116, or are influenced only a little, and remain substantially in their isotropic initial orientation. In contrast, the effect pigments 122 in the unshielded regions 118 align, as described above, along the magnetic field lines.
As a result, in interplay with the optically variable first effect pigments and/
or further background layers, in effect, a different visual appearance of the regions 116 and 118 results such that the motif formed by the magnetic

- 37 -background layer 114 becomes visible for the viewer. After removal of the external magnet 124, no magnetization remains in the magnetic background layer 114 due to the low remanence of the magnetic material 120, such that the effect pigments 122 return to their initial position again and the displayed motif disappears again.
Here, the verification can occur with an arbitrary magnet 124, since the displayed motif is stored in the magnetic background layer 114 of the security element 110 itself. Especially permanent magnets that are easily available everywhere are suitable, such as are built into mobile phones, portable audio playback devices or product security systems.
Fig. 11 shows a security element 130 according to a modification of the embodiment in fig. 10, in which the magnetic background layer 132 includes a contiguous magnetic substance having a medium to high coercive field strength (50 kA/m to 300 kA/m).
The magnetic background layer 132 was initially magnetized by a strong permanent magnet in the form of a desired motif having regions of high field strength or very low field strength. Due to the remanence of the magnetic material 132, an appropriate magnetization having regions of high magnetization 134 or of very low magnetization 136 remains in the background layer 132 also after cessation of the external magnetic field.
Here, the field strength of the regions of high magnetization 134 is large enough to hold the reversibly aligmable second effect pigments 122 in their position, while the orientation of the second effect pigments 122 in the regions of very low magnetization 136 remains substantially isotropic. The initially embossed magnetic pattern 134, 136 is thus preserved.

- 38 -In a further variant, the magnetic background layer 132 can also include a magnetic substance having a very high coercive field strength of more than 300 kA/m. Such a hard magnetic material can be remagnetized only with very strong magnetic fields, such that, with normal usage, an initially introduced pattern is permanently preserved.

Claims

1. An optically variable security element for securing valuable articles, having an optically variable ink layer that includes first, optically variable effect pigments for producing a viewing-angle-dependent visual impression, and that includes second effect pigments that are reversibly alignable by an external magnetic field, the degree of markedness of the viewing-angle-dependent visual impression of the optically variable effect pigments depending on the orientation of the magnetically alignable effect pigments relative to the plane of the ink layer.

2. The security element according to claim 1, characterized in that the second effect pigments are encapsulated in a microcapsule and are substantially freely rotatable in the microcapsule.

3. The security element according to claim 2, characterized in that the second effect pigments are aligned substantially isotropically within their microcapsule without an external magnetic field.

4. The security element according to claim 2 or 3, characterized in that the microcapsules include a gel.

5. The security element according to any one of claims 2 to 4, characterized in that the microcapsules include a swollen, polymeric gel that provides a restoring force for the magnetically alignable effect pigments.

6. The security element according to any one of claims 2 to 5, characterized in that the first effect pigments are present outside the microcapsules of the second effect pigments.

7. The security element according to any one of claims 2 to 5, characterized in that the first effect pigments are encapsulated in the microcapsules together with the second effect pigments.

8. The security element according to claim 7, characterized in that the first and second effect pigments are formed by the same magnetically alignable and optically variable effect pigments.

9. The security element according to any one of claims 1 to 8, characterized in that the second effect pigments are formed on the basis of high-purity iron powder.

10. The security element according to any one of claims 1 to 9, characterized in that the second effect pigments are magnetically soft or magnetically hard.

11. The security element according to any one of claims 1 to 10, characterized in that the second effect pigments are developed to be non-spherical.

12. The security element according to any one of claims 1 to 11, characterized in that the second effect pigments are developed to be platelet-like.

13. The security element at:cording to claim 11, characterized in that the ratio of a largest diameter to a smallest diameter of the non-spherical second effect pigments is more than 5:1.

14. The security element according to claim 11 or 12, characterized in that the largest diameter of the non-spherical second effect pigments is more than 2 µm.

15. The security element according to any one of claims 1 to 10, characterized in that the second effect pigments are formed by isotropic particles that are present in microcapsules and that align cooperatively, especially chain-like, in the microcapsules through an external magnetic field.

16. The security element according to any one of claims 1 to 15, characterized in that the second effect pigments are formed by coated iron pigments.

17. The security element according to any one of claims 1 to 16, characterized in that the second effect pigments are formed by coated iron pigments, the coating being a coloring, laser-markable, fluorescent or phosphorescent coating.

18. The security element according to any one of claims 1 to 17, characterized in that the first effect pigments are pigments manufactured on the basis of liquid crystal polymers or formed by pearlescent pigments.

19. The security element according to any one of claims 1 to 17, characterized in that the first effect pigments are formed by interference layer pigments.

20. The security element according to claim 19, characterized in that the interference layer pigments include at least one reflection layer, one absorber layer and one dielectric spacing layer arranged between the reflection layer and the absorber layer.

21. The security element according to any one of claims 1 to 20, characterized in that the second effect pigments are encapsulated in microcapsules and the microcapsules include an activatable fixative through whose activation the second effect pigments are fixable m a desired position.

22. The security element according to claim 21, characterized in that the microcapsules include, as the activatable fixative, a transparent polymerizable substance or mixture of oligomers and monomers, as well as an initiator, preferably a photoinitiator, for the activation of the fixative.

23. The security element according to claim 21, characterized in that the microcapsules include, as the activatable fixative, a substance that is foamable by the action of laser radiation.

24. The security element according to any one of claims 1 to 23, characterized in that the second effect pigments are encapsulated in microcapsules that exhibit a diameter between 11 µm and 200 µm.

25. The security element according to any one of claims 1 to 24, characterized in that the second effect pigments are encapsulated in microcapsules whose wall thickness is between 5% and 30% of the diameter of the microcapsules.

26. The security element according to any one of claims 1 to 25, characterized in that the optically variable ink layer further includes third, unencapsulated and magnetically alignable effect pigments that are aligned magnetically in the form of a specified motif in the form of patterns, lines, characters or a code.

27. The security element according to claim 26, characterized in that the encapsulated second and the unencapsulated third effect pigments are present at least partially in the same regions of the optically variable ink layer.

28. The security element according to claim 26 or 27, characterized in that the encapsulated second and the unencapsulated third effect pigments are present at least partially in separate regions of the optically variable ink layer.

29. The security element according to any one of claims 26 to 28, characterized in that the third effect pigments are formed on the basis of high-purity iron powder.

30. The security element according to any one of claims 26 to 29, characterized in that the third effect pigments are developed to be non-spherical.

31. The security element according to claim 30, characterized in that the ratio of the largest diameter to the smallest diameter of the non-spherical third effect pigments is more than 5:1.

32. The security element according to claim 30 or 31, characterized in that the largest diameter of the non-spherical third effect pigments is more than 2 µm.

33. The security element according to any one of claims 1 to 32, characterized in that the optically variable ink layer includes a pigment mixture having the first effect pigments and the encapsulated second effect pigments.

34. The security element according to any one of claims 1 to 33, characterized in that the optically variable ink layer includes a pigment mixture having the first effect pigments, the encapsulated second effect pigments and the unencapsulated third effect pigments.

35. The security element according to any one of claims 1 to 34, characterized in that the optically variable ink layer includes a purely magnetic layer having the second effect pigments and, arranged over the purely magnetic layer, a purely ink layer having the first effect pigments.

36. The security element according to any one of claims 1 to 35, characterized in that the optically variable ink layer is formed by a screen printing layer or a flexo printing layer.

37. The security element according to any one of claims 1 to 35, characterized in that the optically variable ink layer is formed by an intaglio printing layer.

38. The security element according to any one of claims 1 to 37, characterized in that the optically variable ink layer is blind embossed.

39. The security element according to any one of claims 1 to 38, characterized in that the ink layer includes, in addition to the first, second and third effect pigments, further pigments.

40. The security element according to any one of claims 1 to 39, characterized in that the optically variable ink layer is applied on a standard banknote paper or on a colored background layer.

41. The security element according to any one of claims 1 to 39, characterized in that the optically variable ink layer is applied on a transparent or translucent foil.

42. The security element according to any one of claims 1 to 41, characterized in that the optically variable ink layer is applied on an information-bearing background layer.

43. The security element according to any one of claims 1 to 42, characterized in that the optically variable ink layer is combined with a thermochromic background layer.

44. The security element according to claim 43, characterized in that the thermochromic background layer is designed such that, when it is activated through a temperature increase, the optically variable effect of the first effect pigments disappears for the viewer.

45. The security element according to any one of claims 1 to 44, characterized in that the optically variable ink layer is combined with a magnetic background layer.

46. The security element according to claim 45, characterized in that the magnetic background layer is present in the form of patterns, characters or a code.

47. A method for manufacturing an optically variable security element for securing valuable articles, in which, on a substrate, an optically variable ink layer is applied that includes first, optically variable effect pigments for producing a viewing-angle-dependent visual impression, and that includes second effect pigments that are reversibly alignable by an external magnetic field, the degree of markedness of the viewing-angle-dependent visual impression of the optically variable effect pigments depending on the orientation of the magnetically alignable effect pigments relative to the plane of the ink layer.

48. The method according to claim 47, characterized in that the second effect pigments are encapsulated in a microcapsule such that they are substantially freely rotatable in the microcapsule.

49. The method according to claim 47 or 48, characterized in that the second effect pigments are encapsulated in a microcapsule together with an activatable fixative, and the encapsulated second effect pigments are partially or completely fixed in a desired position by activating the activatable fixative.

50. The method according to claim 49, characterized in that the second effect pigments are fixed in a desired position in sub-regions in the form of patterns, characters or a code through local UV irradiation or through local laser irradiation.

51. The method according to any one of claims 47 to 50, characterized in that an optically variable ink layer is applied that further includes, in addition to the first and second effect pigments, third, unencapsulated and magnetically alignable effect pigments, and in that the third effect pigments are permanently aligned by an external magnetic field to form a motif in the form of patterns, lines, characters or a code.

52. T'he method according to any one of claims 47 to 51, characterized in that the first and second effect pigments are mixed to form a pigment mixture and printed together.

53. The method according to any one of claims 47 to 51, characterized in that the first, second and third effect pigments are mixed to form a pigment mixture and printed together.

54. The method according to claim 52, characterized in that the pigment mixture is printed in screen printing, flexo printing or in intaglio printing.

55. The method according to any one of claims 47 to 51, characterized in that on the substrate is first imprinted a purely magnetic layer having the second effect pigments, and over the purely magnetic layer is printed a purely ink layer having the first effect pigments.

56. The method according to claim 55, characterized in that the purely magnetic layer and/or the purely ink layer is printed in screen printing, flexo printing or in intaglio printing.

57. The method according to any one of claims 51 to 56, characterized in that the magnetically produced motif of the third effect pigments is fixed by UV curing.

58. The method according to any one of claims 51 to 57, characterized in that the third effect pigments are formed to be platelet-like and, in first sub-regions, are aligned substantially vertically to the plane of the ink layer in order to form translucent sub-regions of the ink layer.

59. The method according to any one of claims 51 to 58, characterized in that the third effect pigments are formed to be platelet-like and, in second sub-regions, are aligned substantially parallel to the plane of the ink layer in order to form opaque sub-regions of the ink layer.

60. The method according to any one of claims 47 to 59, characterized in that the optically variable ink layer is blind embossed in intaglio printing.

61. A security arrangement for securing security papers, value documents, data carriers and the like having a security element according to one of claims 1 to 46 and having a verification element having a magnetic motif region in which magnetic material is present in the form of patterns, lines, characters or a code.

62. The security arrangement according to claim 61, characterized in that the magnetic motif region is magnetized substantially vertically to the plane of the verification element.

63. The security arrangement according to claim 61 or 62, characterized in that the motif depicted by the magnetic motif region is openly visible.

64. The security arrangement according to claim 61 or 62, characterized in that the motif depicted by the magnetic motif region is not perceptible without auxiliary means.

65. A data carrier having a security element according to any one of claims 1 to 46.

66. A data carrier having a security arrangement according to any one of claims 61 to 64.

67. The data carrier according to claim 66, characterized in that the security element and the verification element are geometrically arranged on the data carrier in such a way that the security element is bringable over the verification element by bending or folding the data carrier.

68. The data carrier according to any one of claims 65 to 67, characterized in that the security element is arranged in or over a window area or a through opening in the data carrier.

69. The data carrier according to any one of claims 65 to 68, characterized in that the data carrier is a banknote or another value document, a passport, a certificate or an identification card.

70. A use of a security element according to any one of claims 1 to 46, of a security arrangement according to any one of claims 61 to 64, or of a data carrier according to any one of claims 65 to 69 for securing articles of any kind.