AU2012272129B2

AU2012272129B2 - Magnetic screen printing ink or flexographic ink and security element printed using the same

Info

Publication number: AU2012272129B2
Application number: AU2012272129A
Authority: AU
Inventors: Christoph Mengel; Elisabeth Paul; Jurgen Schutzmann; Max Voit
Original assignee: Giesecke and Devrient Currency Technology GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2011-06-22
Filing date: 2012-06-21
Publication date: 2015-10-29
Anticipated expiration: 2032-06-21
Also published as: CN103608413A; HK1190747A1; CN103608413B; DE102011105396A1; AU2012272129A1; MX362953B; EP2723577B1; BR112013032519A2; PL2723577T3; MX2013014702A; EP2723577A1; WO2012175212A1; ES2765027T3

Abstract

The invention relates to a magnetic screen printing ink or flexographic ink (30) having a binder (32) and magnetically orientable, plate‑like magnetic pigments (34, 36) which are characterized by the following parameters: inherent colour, coercivity, retentivity and NIR remission. According to the invention, the screen printing ink or flexographic ink (30) contains at least two different magnetically orientable, plate‑like magnetic pigments (34, 36), which differ significantly in at least one of the characteristic parameters. The invention also relates to a security element (12) having a first print region (14) which is printed using a first magnetic screen printing ink or flexographic ink (30) of the type mentioned.

Description

-1 Magnetic Screen Printing Ink or Flexographic Ink and Security Element Printed Using the Same 5 FIELD OF THE INVENTION The present invention relates to a magnetic screen printing ink or flexographic ink having a binder and magnetically alignable, platelet-shaped magnetic pigments. The present invention also relates to a security element that is printed using such a magnetic screen printing ink or flexographic ink. 0 BACKGROUND ART 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 5 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 self-supporting transfer element, or also in the form of a feature region imprinted directly on a value document. 0 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 purpose, also magnetically alignable effect pigments that are magnetically aligned in the form of a motif to be depicted, as described, for 25 example, in publication WO 2009/033601 Al, have been in use for some time. Proceeding from this, it is a preferred aim of the present invention to increase the counterfeit security of security elements having magnetically alignable magnetic pigments. 30 -2 SUMMARY OF THE INVENTION According to the present invention, a generic magnetic screen printing ink or flexographic ink includes, besides a binder, at least two different magnetically alignable, platelet-shaped magnetic pigments that differ significantly in at least one 5 of the characteristic parameters of inherent color, coercive field strength, remanence and NIR (near infrared) remission. In particular, the different magnetic pigments exhibit an inherent color having a visually different hue, a coercive field strength that differs by a factor of 1.5 or more, a remanence that differs by a factor of 1.5 or more, and/or an integral NIR remission differing by 10% or more in a sub-region having a 0 width of 50 nm, the sub-region lying in the wavelength range from 800 nm to 1,500 nm. In a preferred first variant of the present invention, one of the different magnetic pigments is substantially optically non-variable and is especially gold, silver or 5 copper colored, while another of the differing magnetic pigments is optically variable. The optically variable magnetic pigment can especially be opaque and, for example, exhibit a color-shift effect from green to blue, gold to green or magenta to green. Through the combination of the optically variable magnetic pigment with a substantially optically non-variable magnetic pigment, the color range of the color 0 shift effect of the optically variable magnetic pigment can be varied and the color play expanded. Moreover, through the combination, the machine-detectability, especially the magnetic detection specifically of the alignment of the magnetic pigments can be improved. 25 Here, the selected formulation, according to which one of the differing magnetic pigments is substantially optically non-variable, accounts for the fact that, in such magnetic pigments, substantially no, or only a negligible, color-shift effect is present. In one expedient embodiment of this variant of the present invention, at a 30 wavelength of 800 nm and at a wavelength of 1,200 nm, one of the magnetic pigments exhibits, in each case, an NIR remission that is higher than the NIR -3 remission another of the magnetic pigments by 10% or more, especially by 20% or more. According to another, likewise advantageous embodiment of the first variant of the 5 present invention, at a wavelength of 800 nm, one of the magnetic pigments exhibits more than 10%, preferably more than 20%, higher NIR remission than another of the magnetic pigments, while at a wavelength of 1,200 nm, the NIR remission is more than 10%, preferably more than 20%, less than that of the other magnetic pigment. 0 In an advantageous second variant of the present invention, substantially none of the magnetic pigments is optically variable, also if the coloring of the pigments can be based on interference effects. In particular, in the second variant of the present invention, one of the different magnetic pigments is metal colored, especially gold, silver or copper colored, and another of the different magnetic pigments is likewise 5 metal colored, especially gold, silver or copper colored. Through the combination of the two different magnetic pigments, on one hand, novel hues can be achieved, and on the other hand, the machine-detectability, especially the magnetic detection of the alignment of the magnetic pigments can be improved. 0 In an expedient embodiment of the second variant of the present invention, at a wavelength of 800 nm and at a wavelength of 1,200 nm, one magnetic pigment exhibits in each case more than 10%, preferably more than 2 0%, higher NIR remission than the other magnetic pigment. 25 Besides binary pigment mixtures having two different magnetic pigments, also ternary pigment mixtures can advantageously be used. In this case, a magnetic screen printing ink or flexographic ink includes three different magnetic pigments that, in pairs, differ significantly in at least one of the characteristic parameters inherent color, coercive field strength, remanence and NIR remission. In particular, 30 pairs of the magnetic pigments have an inherent color having a visually different hue, a coercive field strength that differs by a factor of 1.5 or more, a remanence that -4 differs by a factor of 1.5 or more and/or an integral NIR remission differing by 10% or more in a sub-region having a width of 50 nm in the wavelength range from 800 nm to 1,500 nm. 5 In all embodiments, the screen printing ink or flexographic ink advantageously includes a UV-curing binder. After an alignment of the magnetic pigments by an external magnetic field, said magnetic pigments can then be fixed in the desired position by curing the binder. 0 The present invention also provides a security element having a first print region that is printed using a first magnetic screen printing ink or flexographic ink of the kind described above. Here, it can advantageously be provided that the magnetic pigments of the first magnetic screen printing ink or flexographic ink are magnetically aligned in the first print region. 5 According to an advantageous development of the present invention, the security element includes, besides the first print region, an adjoining second print region, the first print region being printed using a first magnetic screen printing ink or flexographic ink, and the second print region being printed using a second, different 0 magnetic screen printing ink or flexographic ink of the kind described above. In a particularly preferred variant of the present invention, the two print regions exhibit the same hue visually, but differ significantly in their NIR remission. 25 In particular, the integral NIR remission of the two print regions differs in a sub region having a width of 50 nm in the wavelength range from 800 nm to 1,500 nm by 10% or more, preferably by 20% or more. In a likewise advantageous variant of the present invention, the two print regions 30 exhibit the same hue visually, but differ significantly in their magnetic properties. In -5 particular, the coercive field strength and/or the remanence of the two print regions differ by 10% or more, preferably by 20% or more. Advantageously, in each of the first and second magnetic screen printing inks or 5 flexographic inks, one of the different magnetic pigments is optically variable and another of the different magnetic pigments is substantially optically non-variable, and in each case may be metal-colored, preferably gold-, silver- or copper-colored magnetic pigments. 0 In a special embodiment, the first and second magnetic screen printing ink or flexographic ink each include one of the different magnetic pigments substantially in the same proportion of the total amount of magnetic pigment. At least one of the screen printing inks or flexographic inks can additionally include 5 a colored pigment or a dye to match the visual hues of the two print regions with each other as well as possible. The magnetic pigments can be magnetically aligned in none, one or possibly also in both print regions. Particularly attractive designs are created when the first and second print regions 0 meet each other in perfect register. Preferably, the two print regions are arranged in the shape of patterns, characters or a code, especially the second print region forming the inner region of the first print region. In this way, the IR colored edges known from intaglio printing can be transferred to 25 screen printing. Here, in screen printing, unlike in the intaglio printing process, which, due to the template technology, permits only simple IR edges, complex or figurative 2-D colored edges can also be realized. The present invention also provides a method for manufacturing a security element 30 of the kind described above, in which a first print region and an adjoining second print region are printed using different magnetic screen printing inks or flexographic -6 inks, in each case of the kind described above. Optionally, the magnetic pigments of the magnetic screen printing inks or flexographic inks are magnetically aligned in one or both print regions. 5 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. The different exemplary embodiments are not limited to the use in the form specifically described, but rather can also be combined with one another. 0 BRIEF DESCRIPTION OF THE DRAWINGS Shown are: Fig. 1 a schematic diagram of a banknote having a security element according to the present invention, 5 Fig. 2 in (a), a top view and in (b), a cross section of the security element in fig. 1, Fig. 3 schematically, a measurement curve upon the machine detection of the marking in fig. 2(a) along the detection line drawn in with dotted lines, the measurement signal being given in arbitrary units as a function of 0 the location on the detection line, Fig. 4 in (a) and (b), in each case in the near infrared, the remission R of an ink layer having only one first or only one second magnetic pigment (solid curves) and an ink layer according to the present invention having a pigment mixture of the first and second magnetic pigments (dotted 25 curve), Fig. 5 a security element having two print regions printed in the same hue, according to a further exemplary embodiment of the present invention, and Fig. 6 a security element according to yet a further exemplary embodiment of 30 the present invention.

-7 DESCRIPTION OF EMBODIMENT(S) OF THE INVENTION The invention will now be explained using a banknote as an example. For this, figure 1 shows a schematic diagram of a banknote 10 having an inventive security element 12 that was printed in a print region 14 using a magnetic screen printing ink 5 according to the present invention. The print region 14 is depicted in greater detail in fig. 2(a) in top view and in fig. 2(b) in cross section. With reference to figures 2(a) and (b), to form the security element 12, the substrate 20 of the banknote was printed in the print region 14 using a magnetic screen 0 printing ink 30 that includes two different, but both magnetically alignable, platelet shaped magnetic pigments 34, 36 in a UV-curing binder 32. In the exemplary embodiment, the platelet-shaped magnetic pigments 34, 36 were aligned in the shape of a sharply delimited circular marking 22 by a sphere magnet and fixed. 5 To produce this marking 22, the substrate 20 having the magnetic pigments 34, 36 that are initially still mobile in the uncured screen printing ink 30 was brought to a small distance over a sphere magnet. Here, the spherically curved magnetic field lines of the sphere magnet align the magnetic pigments 34, 36, in a region 24 that lies immediately over the magnet, substantially vertically to the substrate surface, while 0 the preferred orientation of the magnetic pigments in a region 28 that is further away from the sphere magnet runs substantially parallel to the substrate surface. The two regions 24 and 28 are separated by a narrow transition region 26 in which the orientation of the magnetic pigments quickly transitions from a substantially vertical to a substantially parallel orientation. The magnetic pigments 34, 36 aligned in this 25 way are permanently fixed in their orientation by curing the UV-curing binder 32, as shown in cross section in fig. 2(b). For a particularly good machine-detectability, the inner region 24, in which the magnetic pigments are substantially vertical to the substrate surface, exhibits a 30 diameter of 5 mm or more.

-8 The circular marking 22 is visible due to the different reflection direction of the aligned magnetic pigments, and also visually verifiable due to its special three dimensional appearance and the cinematic effects. Specifically, due to the alignment of the magnetic pigments, it offers the viewer an effective, three-dimensional 5 seeming appearance, and moreover, appears to move when the security element is tilted, and thus produces a cinematic effect with a high attention and recognition value. For a more detailed description of the realization and the embodiment of said effects, reference is made to documents WO 2009/033601 Al and WO 2009/074284 A2, the disclosure of which is incorporated in the present 0 description by reference. The distinctive feature of the magnetic screen printing ink 30 now consists in the fact that it includes two different magnetically alignable, platelet-shaped magnetic pigments 34, 36 having different properties in order to ensure, on one hand, a high 5 visual attractiveness, and on the other hand, a secure machine-detection of the security element 12. The magnetic pigments 34, 36 are each characterized by the parameters inherent color, coercive field strength, remanence and NIR remission, and differ significantly 0 from each other, according to the present invention, in at least one of said characteristic parameters. This means especially that the magnetic pigments 34, 36 exhibit an inherent color having a visually different hue, a coercive field strength that differs by a factor of 1.5 or more, a remanence that differs by a factor of 1.5 or more and/or an integral NIR remission differing by 10% or more in a sub-region having a 25 width of 50 nm in the wavelength range from 800 nm to 1,500 nm. In the described exemplary embodiment, the magnetic pigment 36 is an optically variable, magnetically alignable pigment having a brilliant color impression that ensures, above all, the visual attractiveness of the security element 12. The magnetic 30 pigment 36 can exhibit, for example, a color-shift effect from green to blue or from gold to green. For security printing, opacifying magnetic pigments having a color- -9 shift effect are available, for example magnetic interference pigments as are described in EP 1 366 380 A2, whose disclosure on the manufacture and characteristics of such pigments is incorporated in the present description, and are offered by Sicpa Holding S.A., for example under the names OVMI Gold/Green 5 SK 1001 S, OVMI 5 Green/Blue 5 SK 5001 S and OVMI Magenta/Green 5 SK 3001 S. However, it has been shown that a machine-detectability of an authenticity feature that includes only magnetic pigments 36 is not possible, or is possible to a limited extent only, with the aid of the magnetic characteristics of the pigments. To open up 0 such a detection possibility and thus increase the counterfeit security of the security element 12, the screen printing ink 30 includes, rather, additionally, the magnetic pigment 34 that constitutes a magnetically alignable pigment without optical variability, but having high coercive field strength and having high magnetic field strength in the magnetized state. For example, the magnetic pigments offered by 5 Merck KGaA under the name Colorona Blackstar(R), or also other magnetic, especially single-layer or multi-layer pigments based on mica and Fe304 can be used as the magnetic pigments 34. Figure 3 shows, schematically, a measurement curve 42 upon the machine-detection 0 of the marking 22 in fig. 2(a) along a detection line 40. To record such a measurement curve 42, the print region 14 is, for example, first magnetized with an NdFeB permanent magnet and, after the removal of the external magnetic field, the remanence is measured with a GMR (giant magneto resistance) magnetic sensor along the detection line 40. When traversing the detection line 40 over the points A, 25 B, C and D, a signal curve results as depicted in fig. 3. Here, the signal of the magnetic sensor, presented in arbitrary units, indicates the local magnetic field strength of the magnetized magnetic pigments 34, 36. The exact progression of the measurement curve 42 depends not only on the coercive field strength of the magnetic pigments used, but also on the sphere magnet used for aligning, and on the 30 conditions when magnetizing and reading out the print region 14.

-10 The measurement curve 42 shows, at each of points A and D, which lie at the left or right edge of the print region 14, a strong signal 44 that originates from the emergence of the magnetic field lines at the edges of the print region 14. Said two border signals 44 also occur in non-aligned magnetic pigments and can be deducted 5 from the measured signal 42. Due to the aligned magnetic pigments in the inner region 24 of the marking 22, a magnetic field exits from the print region 14 there, also, and produces between the points B and C a wanted signal 46 having the width of the marking 22. In the exemplary embodiment, the presence or non-presence of the marking 22 can be machine-detected beyond a doubt due to this wanted signal 0 46. Here, also the position of the wanted signal 46 relative to the border signals 44 can be drawn on for analysis. However, a sufficiently strong wanted signal 46 results only if the magnetic screen printing ink includes, in addition to the magnetic pigments 36 that ensure the visual 5 attractiveness, also the magnetic pigments 34 that thus facilitate a magnetic machine detectability. In the case of control measurements in which the sensor signal of a print region was measured, in which only the magnetic pigments 36, but not the magnetic pigments 34 were present, it was, in fact, possible to detect border signals 44 at the edges of the print region 14, but even said border signals were already too 0 small for a reliable detection. In the inner region 24 of the marking 22, it was no longer possible to detect any usable wanted signal. Besides the magnetic characteristics, the magnetic pigments 34, 36 also differ in their absorption properties in the near infrared (NIR), which, in the context of this 25 description, is understood to be the wavelength range from 800 nm to 1,500 nm. As is common in the technical field of printing technology, the infrared properties of printed-on ink layers are indicated by the remission of the printed paper substrate. A high remission thus means that the NIR absorption of the ink layer is low, while a low remission points to a high NIR absorption of the ink layer. 30 -11 For the present screen printing inks, fig. 4(a) shows, by way of example, the remission R of a screen printing ink layer having only the second magnetic pigment 36 (remission curve 50), an ink layer having only the first magnetic pigment 34 (Colorona Blackstar(R), remission curve 52) and an inventive ink layer having a 5 pigment mixture of the first and second magnetic pigments 34, 36 in the proportion 50/50 of the two screen printing inks (remission curve 54, dotted). As to be expected, the remission curve 54 of the pigment mixture lies between the curves 50, 52 of the ink layers that each have only a single magnetic pigment 34 or 36. Although not explicitly depicted in the drawing, when the proportion of the first magnetic pigment 0 34 is increased, a practically continuous transition from the remission curve 50 to the remission curve 52 results. As is further evident from fig. 4(a), the remission of the ink layer increases with the increasing proportion of the first magnetic pigment 34 at a wavelength of 800 nm, while it decreases at a wavelength of 1,200 nm. 5 Figure 4(b) shows a further exemplary embodiment of a screen printing ink layer according to the present invention, in which the first magnetic pigment 34 is formed by another magnetically alignable, platelet-shaped magnetic pigment, specifically by the multilayer magnetic pigment disclosed in WO 2010/149266 Al. Such magnetic pigments especially exhibit a support and a layer applied to the support, the support 0 being selected from A1 2 0 3 , A1 2 0 3 with up to 5 wt. % TiO 2 , SiO 2 , SiO 2 with up to 20 wt. % silicon hydroxide, glass or borosilicate, and the layer including iron oxide, especially gamma-iron oxide that is doped with at least one earth alkali metal oxide, preferably MgO. 25 Figure 4(b) shows, in the near infrared, the remission R of an ink layer having only the second magnetic pigment 36 (remission curve 50), of an ink layer having only the first magnetic pigment (remission curve 56) and of an ink layer according to the present invention having a pigment mixture of the first and second magnetic pigments in a 50/50 proportion of the two screen printing inks (remission curve 58, 30 dotted). Here, too, a practically continuous transition from the remission curve 50 to the remission curve 56 can be achieved by increasing the proportion of the first -12 magnetic pigment. As can further be seen from fig. 4(b), in this exemplary embodiment, the remission the of ink layer increases with the increasing proportion of the first magnetic pigment in the entire NIR range, that is, the NIR absorption of the ink layer decreases. 5 In the context of the present description, the specified proportional ratios always refer to the weight ratio of the screen printing inks used to the manufacture the inventive screen printing ink including the first or the second magnetic pigment. Here, the screen printing inks that include the first magnetic pigment are present in a 0 UV-curing binder in a magnetic pigment concentration of 15 wt. %. To manufacture the screen printing ink according to the present invention, said screen printing ink was then mixed, in the specified proportion (e.g. 50/50), with the screen printing ink including the second magnetic pigment, e.g. a screen printing ink offered by Sicpa Holding S.A. under the name OVMI Gold/Green 5 SK 1001 S, OVMI Green/Blue 5 5 SK 5001 S or OVMI Magenta/Green 5 SK 3001 S. Proceeding from the second magnetic pigment 36 (remission curve 50), the NIR remission of a screen printing ink according to the present invention can thus be adjusted as desired in a broad range by adding a proportion of the first magnetic 0 pigment (remission curve 52 in fig. 4(a) or remission curve 56 in fig. 4(b)). Here, the remission of the pigment mixture can be both increased and decreased compared with an ink layer having the second magnetic pigment 36 alone, as illustrated in figures 4(a) and (b). 25 The measurement of the NIR remission is usually done, not at a single wavelength, but by measuring a broad remission spectrum. However, by using sensors having certain sensitivity ranges or by using appropriate filters, also only a sub-range of the NIR spectrum can be detected as needed. The measurement of the NIR remission can be carried out, for example, with a Datacolor Microflash 45 NIR on screen printing 30 patterns on cotton velum paper.

- 13 The magnetic screen printing inks according to the present invention not only permit customizing the magnetic properties and the NIR remission of the screen printing ink, but also facilitate varying the optical impression of the ink. If, for example, one assumes an optically variable second magnetic pigment 36 that displays a color-shift 5 effect from magenta to green, such as the magnetic pigment offered by Sicpa Holding S.A. under the name OVMI Magenta/Green 5 SK 3001 S, then, by adding different proportions of a gold-colored, substantially optically non-variable first magnetic pigment 34, a visually attractive range of magnetic screen printing inks can be produced. Here, both the color coordinates of the color-shift effect and the color 0 difference between the vertical and oblique viewing direction change with an increasing proportion of first magnetic pigment, and in this way lead to an expanded color play. In a further exemplary embodiment of the present invention, which will now be 5 described in greater detail with reference to fig. 5, a security element 60 according to the present invention includes, besides a first print region 62, an adjoining second print region 64, the first print region 62 being printed using an inventive first screen printing ink, and the second print region 64 using an inventive second screen printing ink that is different from the first screen printing ink. 0 Here, the two print regions 62, 64 meet each other in perfect register and are arranged in the form of a motif, for example the maple leaf shown in fig. 5, in which the second print region 64 forms the inner region of the first print region 62. 25 The magnetic screen printing inks used for the two print regions 62, 64 are now coordinated with each other in such a way that the two print regions 62, 64 exhibit substantially the same hue visually, but differ significantly in their NIR remission. The "maple leaf" motif formed by the print region 62, 64 is thus visually practically not perceptible for a viewer, while it is easily detectable upon machine readout with 30 an IR sensor due to the different NIR remissions of the two print regions 62, 64.

-14 To achieve this effect, the first and second screen printing ink according to the present invention each include, as the second magnetic pigment 36, the same optically variable magnetic pigment that is selected for a brilliant color impression and thus for the visual attractiveness of the security element 60. However, the first 5 and second screen printing ink differ in their first magnetic pigment 34, the first screen printing ink including the above-mentioned multilayer magnetic pigments disclosed in WO 2010/149266 Al, and the second screen printing ink the above mentioned Colorona Blackstar(R) magnetic pigments. 0 In the exemplary embodiment, the two screen printing inks each include the optically variable magnetic pigment 36 in the same proportion of the total amount of magnetic pigment, specifically each in the proportion 90/10 of the screen printing inks mixed in the screen printing ink according to the present invention. In other designs, also other proportional ratios are, of course, possible, such as 80/20, 70/30, 5 60/40 or 50/50, which likewise yield very similar hues visually, and nevertheless differ sufficiently strongly in their absorption properties in the near infrared for a detection. Also different proportional ratios in the two print regions are, of course, possible. 0 To match the visual hues of the two print regions 62, 64 with each other as well as possible, one or both of the screen printing inks according to the present invention can additionally include a colored pigment or a dye. If, for example, the first magnetic pigment of the first screen printing ink is more brilliant and color pure than the first magnetic pigment of the second screen printing ink, then the hues can be 25 matched by adding colored pigments to the first screen printing ink. Figure 6 shows a security element 70 according to a further exemplary embodiment of the present invention. The security element 70 depicts, as the motif, the value number "100" of the banknote 10 and includes a first print region 72 and, adjoining 30 in perfect register, a second print region 74. The print regions 72, 74 are each printed using inventive magnetic screen printing inks that are identical in hue, but differ in -15 their NIR remission. Additionally, the magnetic pigments of the second print region 74 are magnetically aligned in einem strip-shaped region 76 such that, when the security element 70 or the banknote provided therewith is tilted, a cinematic effect in the form of an optically running bar 76 results. 5 In this exemplary embodiment, the motif of the value number "100" formed by the print region 72, 74 can also be recognized visually, despite the very similar hues of the two print regions 72, 74, due to the cinematic effect of the running bar, especially when the security element 70 is tilted back and forth. In this way, the print regions 0 72, 74 that have identical hues and are nevertheless visually distinguishable constitute an optically attractive authenticity feature having a high attention and recognition value. Simultaneously, the differing NIR remission of the print regions 72, 74 permits a secure machine detection and verification of the security element 70. 5 Instead of a different NIR remission, also different magnetic properties of the two print regions can, of course, be used for the machine detection. For all described security elements, instead of the binary mixtures with two different magnetic pigments described by way of example, also ternary mixtures with three 0 different magnetic pigments can be used. Such a ternary magnetic screen printing ink includes three different magnetic pigments that, in pairs, differ significantly in at least one of the above-mentioned characteristic parameters. In the exemplary embodiments in figures 5 and 6, the two identical-hue print regions can differ both in their NIR remission and in their magnetic characteristics. 25 -16 List of reference signs 10 Banknote 12 Security element 5 14 Print region 20 Substrate 22 Marking 24 Inner region 26 Transition region 0 28 Distant region 30 Screen printing ink 32 Binder 34 First magnetic pigments 36 Second magnetic pigments 5 40 Detection line 42 Measurement curve 44 Border signals 46 Wanted signal 50, 52, 54, 56, 58 Remission curves 0 60 Security element 62 First print region 64 Second print region 70 Security element 72 First print region 25 74 Second print region 76 Strip-shaped region

Claims

1. A magnetic screen printing ink or flexographic ink having a binder and magnetically alignable, platelet-shaped magnetic pigments with characteristic parameters of inherent color, coercive field strength, remanence and NIR remission, characterized in that the screen printing ink or flexographic ink includes at least two different magnetically alignable, platelet-shaped magnetic pigments that differ significantly in at least one of the characteristic parameters.

2. The magnetic screen printing ink or flexographic ink according to claim 1, wherein the at least two different magnetic pigments exhibit an inherent color having a visually different hue, a coercive field strength that differs by a factor of 1.5 or more, a remanence that differs by a factor of 1.5 or more, and/or an integral NIR remission differing by 10% or more in a sub-region having a width of 50 rn, the sub region lying in the wavelength range from 800 nm to 1,500 nm.

3. The magnetic screen printing ink or flexographic ink according to claim 1 or 2, characterized in that one of the different magnetic pigments is substantially optically non-variable, and another of the differing magnetic pigments is optically variable.

4. The magnetic screen printing ink or flexographic ink according to any one of claims 1 to 3, characterized in that, at a wavelength of 800 nm and at a wavelength of 1,200 nm, one of the different magnetic pigments exhibits, in each case, more than 10% higher IR remission than another of the different magnetic pigments.

5. The magnetic screen printing ink or flexographic ink according to any one of claims 1 to 3, characterized in that, at a wavelength of 800 nm, one of the different magnetic pigments exhibits more than 10% higher NIR remission, and at a wavelength of 1,200 nm, more than 10% lower NIR remission, than another of the different magnetic pigments. -18

6. The magnetic screen printing ink or flexographic ink according to claim 1, characterized in that substantially none of the magnetic pigments is optically variable.

7. The magnetic screen printing ink or flexographic ink according to claim 6, characterized in that one of the different magnetic pigment exhibits, at a wavelength of 800 nm and at a wavelength of 1,200 nm, in each case, a more than 10% higher IR remission than another of the different magnetic pigments.

8. The magnetic screen printing ink or flexographic ink according to claim 1, characterized in that the screen printing ink or flexographic ink includes three different magnetic pigments that, in pairs, differ significantly in at least one of the characteristic parameters, especially in that pairs of the magnetic pigments have an inherent color having a visually different hue, a coercive field strength that differs by a factor of 1.5 or more, a remanence that differs by a factor of 1.5 or more, and/or an integral NIR remission differing by 10% or more in a sub-region having a width of 50 nm, the sub-region lying in the wavelength range from 800 nm to 1,500 nm.

9. The magnetic screen printing ink or flexographic ink according to at least one of claims 1 to 8, characterized in that the screen printing ink or flexographic ink includes a UV-curing binder.

10. A security element having a first print region that is printed using a first magnetic screen printing ink or flexographic ink according to one of claims 1 to 9.

11. The security element according to claim 10, characterized in that the magnetic pigments of the first magnetic screen printing ink or flexographic ink are magnetically aligned in the first print region.

12. The security element according to claim 10 or 11, having the first print region and an adjoining second print region, the first print region being printed using a first -19 magnetic screen printing ink or flexographic ink, and the second print region being printed using a second, different magnetic screen printing ink or flexographic ink according to one of claims 1 to 9.

13. The security element according to claim 12, characterized in that the two print regions exhibit the same hue visually, but differ significantly in their NIR remission, and especially in that, in a sub-region having a width of 50 rn, the integral NIR remission of the two print regions differs by 10% or more, and preferably by 20% or more, in the wavelength range from 800 nm to 1,500 nm.

14. The security element according to claim 12 or 13, characterized in that the two print regions exhibit the same hue visually, but differ significantly in their magnetic properties, especially in that the coercive field strength and/or the remanence of the two print regions differs by 10% or more, and preferably by 20% or more.

15. The security element according to any one of claims 12 to 14, characterized in that in each of the first and second magnetic screen printing inks or flexographic inks, one of the different magnetic pigments is optically variable, and another of the different magnetic pigments is substantially optically non-variable.

16. The security element according to any one of claims 12 to 15, characterized in that at least one of the screen printing inks or flexographic inks additionally includes a colored pigment or a dye.

17. The security element according to any one of claims 12 to 16, characterized in that the magnetic pigments are magnetically aligned in one or both print regions.

18. The security element according to any one of claims 12 to 17, characterized in that the first and second print regions meet each other in perfect register. -20

19. The security element according to any one of claims 12 to 18, characterized in that the two print regions are arranged in the shape of patterns, characters or a code, the second print region especially forming an inner region of the first print region.

20. A method for manufacturing a security element according to any one of claims 12 to 19, in which the first print region and the second print region are adjoining and are printed using different magnetic screen printing inks or flexographic inks, each according to any one of claims 1 to 9.