Method for producing a data carrier, security element or semi-finished product, and microlens-based security element

Abstract

The invention relates to a method for producing a data carrier (20), in particular a film element, which has a metal layer (32) present at least in some regions and a colored layer (40) positioned in register with the metal layer, wherein the method has the steps of: B) providing an electrically insulating support (22), in particular an electrically insulating support film, M) applying an electrically conductive metal coating (32) onto the support in first regions (30) such that second regions (34) which differ from the first regions (30) are formed on the support so as to be either not conductive or electrically insulated from the metal coating of the first regions, T) applying a first toner (40) having toner particles (42) onto the partly metallized support, E) applying an electric field (54, 56) in order to selectively deposit the toner particles (42) of the first toner (40) either only in the first regions (30) or only in second regions (34) of the support, and F) securing the deposited toner particles (42) in the first or second regions of the support.

Description

[0001] Method for manufacturing a data carrier, security element or semi-finished product and microlens-based security element

[0002] The invention relates to a method for manufacturing a data carrier comprising a metal layer present at least in certain areas and a colored layer arranged in relation to the metal layer. The invention also relates to an associated security element or a semi-finished product for manufacturing a security element, as well as a corresponding microlens-based security element.

[0003] Data carriers, such as valuables or identification documents, but also other valuables, such as branded goods, are often equipped with security elements for protection, which allow verification of the authenticity of the data carriers and also serve as protection against unauthorized reproduction.

[0004] Security features with viewing-angle-dependent effects play a particularly important role in ensuring authenticity, as these cannot be reproduced even with the most modern copying equipment. These security features are equipped with optically variable elements that convey a different visual impression to the viewer from different angles, displaying, for example, different color or brightness levels and / or a different graphic motif depending on the viewing angle.

[0005] For optically variable security elements, it is known to precisely coat the metal layers of the security elements with colored layers, for example, by printing a colored resist varnish onto a solid metal layer and then removing the metal layer outside the resist varnish-printed areas by etching. However, such processes are technically complex due to the required precision of the printing processes, often environmentally harmful due to the use of chemical etchants, and also limited in their design flexibility and resolution, so there is a need for more efficient and precise methods.

[0006] For some time now, optically variable security elements have also been known, in which two relief structures are arranged at different heights and each coated with a color layer. An example of such a security element is described in publication WO 2020 / 011390 Al.

[0007] Based on this, the invention aims to provide an alternative, in particular an efficient and precise method with which perfectly congruent metal and color layers can be produced and different embossing structures can be covered with different colored materials in just one embossing plane with a precise fit.

[0008] This problem is solved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

[0009] The invention is described below with particular reference to banknotes, but is equally suitable for other security papers and other data carriers.

[0010] The invention provides a method for manufacturing a data carrier comprising a metal layer present at least in certain areas and a colored layer arranged in relation to the metal layer. The data carrier can, in particular, be a foil element. The method comprises the following steps:

[0011] B) Providing an electrically insulating support, in particular an electrically insulating support film,

[0012] M) the partial application of an electrically conductive, metallic coating in first areas onto the substrate, such that different second areas on the substrate are either non-conductive or electrically insulated from the metallic coating of the first areas,

[0013] T) Application of a first toner with toner particles to the partially metallized substrate,

[0014] E) Applying an electric field to selectively deposit the toner particles of the first toner either only in the first regions or only in the second regions of the carrier, and

[0015] F) Fixing the deposited toner particles in the first or second areas of the carrier.

[0016] The proposed method differs significantly from known xerographic printing processes. In xerography, which is widely used in modern copiers and laser printers, a rotating drum with a light-sensitive photoconductor layer is first electrostatically charged by a corona discharge. Exposure of the photoconductor layer with the image of an original causes local discharge, creating electrically charged and uncharged areas on the drum that form a latent electrostatic image. Fine toner powder is then applied to the drum, and the toner particles adhere to the areas where the charge has been retained. This toner image is then electrostatically transferred to paper and permanently fixed there by heat and pressure, resulting in a stable copy of the original.While the toner pattern in xerography is created by an exposure step of a structurally unchanged photoconductor layer, in the proposed method the metallic coating itself is applied in a structured form to a substrate. Furthermore, in xerography, the photoconductor layer forms an integral part of the copier or printer and does not become part of the printed image.

[0017] In the proposed method, with an advantageous process flow, the electrically insulating substrate is provided with relief structures onto which the electrically conductive metallic coating is applied in certain areas in step M). The relief structures provide an optical effect, at least in certain areas, and / or enable lateral structuring of the metallic coating.

[0018] The relief structures can be embossed directly into the electrically insulating carrier film. However, it is particularly preferred that the relief structures are molded in an embossing varnish and produced with maximum embossing depths between 0.1 µm and 50 g / m, preferably between 1 g / m and 5 g / m. An electrically insulating embossing varnish is advantageously selected. In particular, the electrically insulating embossing varnish in which the relief structures are molded is part of the electrically insulating carrier.

[0019] Advantageously, in a single step (M2), the second areas are provided with an electrically conductive metallic coating that is electrically insulated from the metallic coating of the first areas. Preferably, the substrate in the first and second metallized areas is provided with relief structures that produce optical effects, the optical effects of which are different and / or visible from different viewing angles.

[0020] In an advantageous embodiment of the invention, the electrically insulating carrier is provided with relief structures, and the first and / or second metallized areas are produced in step M) or M2) with a precise fit to the relief structures of the carrier. This is preferably achieved by

[0021] The carrier is provided with a demetallization relief structure in the third area separating the first and second areas for selective demetallization of these areas.

[0022] In step M) or M2), a large-area metallization is first applied to the first, second and third areas, and the metallization in the third areas is selectively removed using the demetallization relief structure, so that the demetallized third areas electrically separate the first and second areas from each other.

[0023] Before, after, or concurrently with the application of the first toner, a second toner containing toner particles can advantageously be applied to the substrate. In step E2), an electric field is then applied to deposit the toner particles of the second toner onto the first or second metallized areas, which differ from those of the first toner. Step E2) can coincide with step E).

[0024] The toner particles are preferably colored, for example, red, yellow, green, blue, magenta, cyan, or mixtures of these colors. A mixture of two or more differently colored toners can also be used to achieve a desired color. In particular, it is advantageous to mix a desired color from a set of toners with different base colors, resulting in the desired final color impression. The base colors can include cyan, magenta, and yellow; additionally or alternatively, red, green, blue, or, for lightening or darkening, transparent or black toner particles can also be used.

[0025] Advantageously, the first and second areas are nested within each other, with the nesting preferably occurring on a length scale below the resolving power of the human eye, i.e., in particular on a length scale of less than 100 µm, preferably less than 50 µm, and most advantageously less than 25 µm. The first and second areas can, for example, be designed as alternately arranged narrow strips with a width of less than 100 µm, preferably less than 50 µm, and most advantageously less than 25 µm. In other, equally advantageous embodiments, the nesting can also be visible to the naked eye as a design element, for example, by means of a visible grid with a grid spacing significantly above 100 µm.Hybrid forms are also conceivable, in which, for example, a raster pattern is visible to the naked eye and only with aids, such as a magnifying glass or a microscope, does it become additionally apparent that the raster elements have a certain shape (symbols, lettering, motif) with the high resolution possible according to the invention.

[0026] The first toner and / or, if applicable, the second toner are advantageously applied with charged toner particles. If two toners are used, the first and second toners can be applied, in particular, with oppositely charged toner particles. As mentioned, the first and second toners can be applied together, meaning that oppositely charged toner particles, especially toner particles of different colors, are present simultaneously.

[0027] The first toner and / or, if applicable, the second toner can be a dry toner. However, it is particularly preferred that the first toner and / or, if applicable, the second toner be applied in the form of a liquid toner.

[0028] Advantageously, when an electric field is applied, the metallic coating of the first areas and / or a metallic coating of the second areas are brought to a predetermined electrical potential. In particular, the electrical potential of the first and second areas can have opposite polarities.

[0029] The data carrier can be, in particular, a valuable document such as a banknote (especially a paper banknote, a polymer banknote, or a foil-laminated banknote), a share certificate, a bond, a deed, a voucher, a check, a seal, a tax stamp, a high-quality admission ticket, or an identification card such as a credit card, a debit card, a cash payment card, an authorization card, an identity card, or a passport personalization page. The aforementioned electrically insulated carrier can be formed by the substrate of the data carrier itself, or it can be applied to or embedded in the data carrier after the toner particles have been deposited and fixed. The carrier can also be removed after being applied to the data carrier.In other designs, the data carrier represents a security element, in particular a foil element, preferably a security thread, a security strip, a patch or a label.

[0030] The invention also includes a safety element or semi-finished product for the manufacture of a safety element, wherein the safety element or semi-finished product is manufactured in particular by a method of the type described above. The safety element or semi-finished product comprises first regions and second regions distinct from the first regions, wherein

[0031] the first areas are provided with an initial metallization and a first toner layer made of toner particles lying above the metallization,

[0032] the second areas are not metallized or are provided with a second metallization that is electrically isolated from the first metallization, and

[0033] The second areas are either not coated with a toner layer, or are coated with a second, different toner layer.

[0034] Preferably, the first areas contain optically effective relief structures that preferably offer an optical effect at least in some areas.

[0035] Advantageously, the second areas are provided with a second metallization and feature optically effective relief structures which preferably offer, at least in some areas, an optical effect that differs from the optical effect of the first areas. According to an advantageous embodiment, the first and second areas, through the covering with the different toner layers, exhibit the optical effects of the optically effective relief structures in different colors.

[0036] Finally, the invention also includes a microlens-based security element with a micro-image layer and a one- or two-dimensional microlens array for viewing the micro-image layer, wherein the micro-image layer is produced by a method of the described type or is formed from a semi-finished product of the described type.

[0037] The preferred embodiments and their advantages presented with reference to the respective method according to the invention apply accordingly to the safety element or semi-finished product according to the invention. The components of the safety elements or semi-finished products according to the invention are each configured to perform the respective steps of the method.

[0038] Further features of the invention will become apparent from the claims, the figures, and the figure description. Exemplary embodiments of the invention are explained in more detail below with reference to schematic drawings. In the figures, identical or functionally equivalent elements are designated with the same reference numerals.

[0039] This shows:

[0040] Fig. 1 a schematic representation of a banknote with an optically variable security element according to the invention, Fig. 2 a schematic cross-sectional embodiment of a security element according to the invention,

[0041] Fig. 3 in (a) to (d) Intermediate steps in the manufacture of the safety element of Fig. 2,

[0042] Fig. 4 shows the use of a method according to the invention in a roll-to-roll process.

[0043] Fig. 5 shows the contacting of the metallization during the deposition of toner particles in a roll-to-roll process.

[0044] Fig. 6 in (a) a microlens-based security element and in (b) a section of the motif layer of the security element of (a) in top view,

[0045] Fig. 7 shows a safety element with two relief structures arranged at different height levels and each provided with a color coating to illustrate an advantageous application of the manufacturing process according to the invention.

[0046] Fig. 8 in (a) to (e) Intermediate steps in the precise application of a metallization to create effect-giving relief structures,

[0047] Fig. 9 in (a) to (d) intermediate steps in a method for fitting metallizations and relief structures based on relief structures with large aspect ratios, Fig. 10 a safety element with alternatingly nested stripes of different colors,

[0048] Fig. 11 in (a) to (d) a reversible image with nested areas according to Fig. 10, and

[0049] Fig. 12 shows a security element with a strip-shaped nested microimage under a cylindrical lens array.

[0050] The invention will now be explained using the example of banknotes. Fig. 1 shows a schematic representation of a banknote 10 with an optically variable security element 12 according to the invention, which has, in the manner described in more detail below, area-metallized relief structures that are precisely coated with a colored layer, so that the optical effect produced by the relief structures appears colored to a viewer.

[0051] For further explanation, Fig. 2 schematically shows a cross-sectional embodiment of a security element 20 according to the invention. The security element 20 comprises an electrically insulating carrier film 22, which is provided with an embossed lacquer layer 24 with embossed relief structures 26. The embossed lacquer layer 24 with the relief structures 26 is coated in first areas 30 with an electrically conductive metallization 32, while second areas 34 are not metallized. The metallized first areas 30 are also precisely coated with a translucent colored toner layer 40 consisting of a plurality of toner particles 42, which, together with the metallization, produce the desired color effect of the areas 30.The security element 20 can, for example, show a motif that appears curved, such as a symbol, a coat of arms, lettering or a portrait, which appears colored at least in some areas due to the color effect of the clay layer, for example red, yellow, green, blue, magenta, cyan or in mixtures of these colors.

[0052] The following procedure can be used, for example, to manufacture the security element 20 and in particular to precisely align the toner layer 40 with the metallization 32.

[0053] Referring to Fig. 3(a), an electrically insulating carrier film 22, for example made of PET, is first provided and an electrically insulating embossing varnish layer 24 is applied to the carrier film 22.

[0054] The desired relief structures 26 are then molded into the embossing lacquer layer 24. The relief structures 26 can, for example, include binary lattice structures 26a, such as holographic lattices, micromirror structures 26b, and planar sub-areas 26c.

[0055] Referring to Fig. 3(b), the relief structures 26 are then provided in first areas 30 with an electrically conductive metallic coating 32, while second areas 34 remain unmetallized. The structuring of the metallic coating 32 can be carried out using industrially standard washing or etching processes, for example, such that the metallization 32 essentially covers only the structures 26a, 26b, while the flat areas 26c remain unmetallized.

[0056] The film structure with the partially present metallization 32 is then placed between two electrodes 50, 52. In practice, the electrodes can be formed, for example, by two spaced-apart, conductive rollers between which the film passes in a roll-to-roll process (Fig. 4).

[0057] Electrodes 50 and 52 are then brought to a suitable electrical potential, as shown in Fig. 3(c). For example, electrode 50 can be grounded (potential V = 0) and electrode 52 can be brought to a positive electrical potential of, for example, several tens or several hundred volts. In the areas 34 where the foil is not metallized, an electric field 54 is thereby built up between the electrodes in the direction of electrode 50, i.e., with upward-pointing electric field lines in the illustration of Fig. 3(c).

[0058] Within the scope of the invention, it is further provided that the metallization 32, which is present in certain areas, is electrically contacted, for example, in the manner described below via corresponding electrical conductors (Fig. 5). The metallization 32 can thereby be set to a negative electrical potential, so that the resulting electric field 56 points towards the metallization 32 over the metallized areas 30, and the field lines between the metallization 32 and the electrode 50 in this area point downwards, as shown in Fig. 3(c).

[0059] Referring to Fig. 3(d), a toner material 40 with toner particles 42 is placed between the electrode 50 and the film assembly with the metallized areas 30. In practice, the toner 40 can also be applied to the film assembly directly between the electrodes 50, 52 before the film is even inserted. The toner particles 42 are, for example, positively charged and are present, in particular, in the colorless carrier liquid 44 of a liquid toner, as schematically shown in Fig. 3(d). The positively charged toner particles 42 follow the electric field lines shown in Fig. 3(c); they are thus deposited on the metallization 32 in the metallized areas 30, while the toner particles 42 in the non-metallized areas 34 are attracted to the electrode 50.

[0060] This ensures that the colored toner particles 42 are applied precisely to the metallized and electrically contacted areas 30, while the non-metallized areas 32 remain colorless.

[0061] The foil structure is then removed from the electrodes 50, 52, and the toner particles adhering to the electrode 50 are peeled off the foil structure. The toner particles 42 applied to the metallized areas 32 are permanently fixed there, for example by applying heat or radiation. After applying a protective layer 28, the structure shown in Fig. 2 is formed, with a colored toner layer 40 perfectly matched to the metallization 32.

[0062] The method according to the invention is advantageously used in a roll-to-roll process. Figure 4 shows, by way of example, how the film structure 22, 24, 32 is removed from the two roller-shaped electrodes 50, 52 after the transfer of the toner particles 42 in such a roll-to-roll process.

[0063] The film assembly 22, 24, 32 initially passes between two rollers 50, 52, which are at the aforementioned electrical potentials. Simultaneously, the liquid toner 40 with the charged colored toner particles 42 can be supplied on roller 50. For example, an application unit 60 can apply fresh toner liquid 40 to roller 50 using an anilox roller, and the toner-particle-depleted liquid 46 returning from the film can be removed from roller 50 with a doctor blade.

[0064] The incoming film assembly 22, 24, 32 encircles the roller 50 within a certain circumference to ensure a sufficiently long residence time for the toner 40 in the electric field of the rollers 50, 52. This gives the toner particles 42 sufficient time to move onto the carrier film 22 before the film is separated from the roller 50 or the metallization 32.

[0065] The removed foil structure 22, 24, 32 with the transferred toner particles 42 is then fixed, thus ensuring that the deposited toner particles 42 remain permanently on the metallization 32 and adhere there as well as possible. The type of fixation depends in particular on the type of toner used: In the case of a liquid toner 40, the carrier liquid 44 can first be evaporated by heat in order to immobilize the toner particles 42.

[0066] Particularly in the case of dry toner, it can be briefly melted by heat or IR radiation to bond the toner particles 42 to each other and to the metal layer 32. Such a step can also be performed with liquid toner after the carrier liquid 44 has evaporated.

[0067] The deposited toner particles 42 can be additionally or alternatively fixed with a protective varnish 28 (Fig. 2). The protective varnish 28 can, for example, be printed or sprayed onto a surface. It is also conceivable to use a liquid toner with a UV-curable carrier fluid 44. In this case, during the roll-to-roll process of Fig. 4, the discharged film assembly 22, 24, 32 with the toner particles 42 and the carrier fluid 44 can pass under a UV lamp 62, so that the toner particles 42 are subsequently fixed in a cured UV varnish. In this case, the UV-curable carrier fluid can simultaneously act as a protective layer 28, so that no separate protective layer is required.

[0068] The embodiments shown in Figures 2 to 4 were described with reference to a toner with positively charged toner particles 42. However, according to the invention, toners with negatively charged toner particles can also be used. The polarities for positive and negative electrical potentials mentioned in Figure 3 are therefore only exemplary, and a person skilled in the art can easily adapt this teaching appropriately when using negatively charged toner particles.

[0069] It is even possible to use toner particles with different charges simultaneously, particularly of different colors. In the embodiment described above, for example, the positively charged toner particles 42 can have a first color, such as red. The toner liquid 44 can also contain negatively charged toner particles of a second color, for example, green. When the toner particles are deposited in the electric field of the rollers 50, 52, the positively charged red toner particles are deposited on the metallized areas 30, as described in Fig. 3, while the green toner particles, due to their negative charge, are deposited on the non-metallized areas 34 of the foil structure. This results in a particularly reliable security feature, in which the first (red) color is perfectly matched to the metallization 30 and the second (green) color is perfectly matched to the non-metallized areas 34 in between.

[0070] To enable the above-mentioned contacting of the metallization 32 during the deposition of the toner particles, the following procedure can be used, for example:

[0071] Referring to Fig. 5, narrow and therefore barely visible metallic ridges 36 are formed during the metallization of the areas 30, which electrically connect the metallized areas 30 to each other. Additionally, a metallic contact track 38 can be provided, for example at the edge of the foil, which is electrically connected to the areas 30 via the ridges 36. The metallized areas 30 can then be brought to a desired electrical potential via the contact track 38 and the ridges 36.

[0072] On the roller 50, an area 58 near the contact track 38 must be electrically isolated from the rest of the roller 50. This area 58 can advantageously be used directly for contacting the contact track 38.

[0073] However, such direct contacting of the metallized areas 30 during the development process is only one of several ways to attract the toner particles to the metallized areas 30 by means of electrical potentials. In another possibility, the entire film surface can be charged with a corona before the toner is applied, and only the metallized areas 30 can be discharged, for example, by contacting and grounding. In this way, any remaining positive charges in the non-metallized areas 34 cause positively charged toner particles 42 to be repelled there, while, with a suitable choice of the electrode potentials 50, 52, they are deposited on the discharged metallized areas 30.

[0074] The described method can advantageously be used to produce the motif layer of a microlens-based security element 70, as shown in the embodiment of Fig. 6. The security element 70 comprises a transparent, electrically insulating carrier film 22, the upper surface of which is provided with a grid-like arrangement of microlenses 72 that form a grid of a preselected symmetry on the surface of the carrier film, as shown in Fig. 6(a). The microlenses 72, which are usually spherical or aspherical, preferably have a diameter between 5 µm and 50 µm, in particular between 8 µm and 35 µm, and are therefore not visible to the naked eye. According to the invention, rod or lenticular lenses can also be used in special embodiments.

[0075] The underside of the carrier film 22 is provided with a motif layer 74, a section of which is shown in top view in Fig. 6(b). The motif layer 74 contains a grid-like arrangement of micro motif elements 76-1, 76-2 in the form of the digits "5" and "0", respectively, which together form the value "50". The micro motif elements have a size between 0.5 µm and 50 g / m², in particular between 3 µm and 35 g / m². The grid arrangements of the micro motif elements 76-1, 76-2 on the one hand and the microlenses 72 on the other hand are aligned with each other in a manner typical for moiré magnification arrangements, in particular slightly rotated or distorted relative to each other, in order to generate moiré magnification and optically variable effects, for example, buoyancy, pumping, morphing, flipping, or stereo effects, through the interaction of the micro motif elements and the microlenses.In other embodiments, the micro-motif elements and microlenses can also be coordinated to form a modulo-magnification arrangement or a non-magnifying lens grid image. For a more detailed description of the functionality and advantageous embodiments of micro-motif elements and microlenses, reference is made to German patent application DE 102005062132 and international applications WO 2007 / 076952 and WO 2009 / 000528 Al.

[0076] The motif image 74 of the security element 70 can advantageously be produced using the method described above. The first areas 30, shown in white in Fig. 6(b), are metallized continuously and electrically contacted during the deposition of the charged toner particles, while the second areas 34, shown in black, are produced without a metal layer in the exemplary embodiment.

[0077] The micro-motif elements 76-2, shaped like the digit "0", have small openings 78 that provide an electrical connection to the interior of the digit "0" and therefore allow the interior areas to be set to the same electrical potential as the exterior areas. As shown in Fig. 6(b), the openings 78 are advantageously provided at different locations within the digit "0" so that they are practically invisible in the synthetically magnified image resulting from the interaction of a multitude of small micro-motif elements 76-2.

[0078] In this way, the white background 30 shown in Fig. 6(b) can be colored in a desired color by depositing toner particles, as described above. Alternatively or additionally, the second areas 34 with the micro-motif elements 76-1, 76-2 can also be colored by depositing toner particles in a color. A particularly attractive and secure security feature is obtained, for example, if differently charged toner particles are used to create different colors for the value number "50" in the second areas 34 and the background 30.

[0079] The representations in the micro-motif elements of such lens features often require very high resolution, with line thicknesses often only a few micrometers. Metallization is therefore advantageously produced using the texture-dependent metallizations described below, for example, by targeted demetallization in areas with moth-eye structures by laser treatment or by etching.

[0080] Figure 7 illustrates another advantageous application of the manufacturing process according to the invention. The safety element 80 shown schematically there has two relief structures 82, 84 arranged at different heights and each provided with a colored coating. Safety elements of this type are described, for example, in publication WO 2020 / 011390 A1. The higher relief structure 84 is provided with a metallization 32 in first areas 30, while second areas 34 of the relief structure 84 are not metallized and allow a view through to the lower relief structure 82.

[0081] With such a security element 80, a colored toner layer with toner particles 42 can now be applied to the partially present metallization 32 of the higher relief structure 84 in the manner described above, and the appearance of the motif produced by the relief structure 84 can therefore be colored as desired.

[0082] The inventive method allows for a highly precise alignment of a colored layer (toner layer) with a structured metallization. Often, however, it is also desirable to align the metal layer with the colored layer in relation to underlying relief structures, for example, to precisely represent different optical effects with different colors.

[0083] If the metallized areas are aligned with underlying relief structures using a washing or etching process, the registration of the metallization in relation to the relief structures is only possible within the tolerances achievable by printing technology, typically a few tenths of a millimeter. However, more precise registration is often desirable or necessary, especially in security printing applications.

[0084] In a further development of the invention, the metallization can also be precisely aligned with such effect-creating relief structures for this purpose. Figure 8 illustrates an advantageous procedure in which a metallization produced by oblique vapor deposition is interrupted precisely to match the underlying relief structures.

[0085] Referring to Fig. 8(a), an electrically insulating embossing lacquer layer 24 is applied to an electrically insulating carrier film 22, and relief structures 90 are molded into this lacquer. In the exemplary embodiment, relief structures 90a are provided in an effect area 92, which produce an optically variable effect, such as diffraction gratings. As a special feature, depressions 90b with a high aspect ratio and steep flanks are provided at the edge of the effect area 92.

[0086] In directed oblique vapor deposition 94 for the metallization of the relief structures, for example from the upper right, the depressions 90b are not covered with a closed metal layer due to their geometry, but interruptions 96 in the metallization 98 are created by shading effects, which lead to the formation of several electrically isolated metallized areas 98-1, 98-2, which are perfectly suited to the effect area 92 or the surrounding exterior.

[0087] In the case of highly directional vapor deposition and very steep flanks of the recesses 90b, the vapor deposition does not necessarily have to be carried out at an oblique angle; in this case, the flanks of the recesses can remain uncoated even with vertical vapor deposition.

[0088] Referring to Fig. 8(c), the metallized film structure is then placed in an electric field together with a toner material 40 containing charged toner particles 42. The metallized areas 98-1, 98-2 can be contacted separately and subjected to different electrical potentials.

[0089] In the embodiment shown in Fig. 8, positively charged toner particles 42 are used in a first step, and the metallized areas 98-1 are brought to a negative potential and the metallized areas 98-2 to a positive potential relative to the reference electrode 50. This causes the toner particles 42 to be deposited precisely onto the areas 98-1 with the relief structures 90a, as shown in Fig. 8(c).

[0090] In an optional second step, after the toner 42 has been fixed, a further toner layer with toner particles 42B of a different color can be precisely applied to the second areas 98-2. For this purpose, the toner particles 42B of the second toner advantageously have the opposite charge to the toner particles 42, i.e., a negative charge. The potentials of the metallized areas 98-1, 98-2 can then be selected as before, as shown in Fig. 8(d). Alternatively, the toner particles 42B can carry the same charge as the toner particles 42, and the potentials of the metallized areas 98-1, 98-2 can be inverted. After fixing the second toner 42B and applying a protective layer 28, the safety element 95 shown in Fig. 8(e) is obtained, in which the colored metallizations are precisely aligned with the underlying relief structures.

[0091] If metallization is not desired in a section of a security element, an initially applied metallization can be selectively removed using a toner layer as a mask. For this purpose, a toner suitable as an etching resist can be used as an etching mask to selectively remove the metallization in areas not covered by toner.

[0092] In addition to the directed vapor deposition methods described in connection with Fig. 8, other methods known to those skilled in the art can also be used to match metallizations and relief structures. For example, it is known that a metal layer can be removed from structures with high aspect ratios, such as so-called moth-eye structures, by etching or laser demetallization in such a way that a metallization of nominally the same thickness remains completely or at least with sufficient residual thickness in areas with relief structures with lower aspect ratios, such as micro mirror arrangements or holographic gratings.

[0093] To illustrate this, Fig. 9 in (a) shows a section of a safety element 100 in which an electrically insulating embossed lacquer layer 24 is applied to an electrically insulating carrier film 22 and relief structures 102 are molded into this layer. In the exemplary embodiment, micromirrors 106 of a first orientation are molded in a first area 104-1 and micromirrors 106 of a different orientation are molded in a second area 104-2, so that the areas 104-1 and 104-2 produce different optical effects.

[0094] The first and second areas 104-1, 104-2 are separated by third areas 108, in which relief structures with a large aspect ratio, specifically for example moth-eye structures 109, are provided.

[0095] Referring to Fig. 9(b), the relief structures 102 are first metallized over their entire surface 110. Subsequently, the metallization 110 is removed from the moth-eye structures 109 in region 108, for example by etching or laser treatment, as shown in Fig. 9(c). Because of the high aspect ratio of the moth-eye structures 109, the metallization in region 108 can be completely removed, while at the same time the metallization 110-1, 110-2 in regions 104-1, 104-2 remains in sufficient thickness due to the lower aspect ratio of the micromirrors 106. The moth-eye structures 109 therefore form a demetallization relief structure for the selective demetallization of regions 108.The interruption by the demetallized third areas 108 creates several electrically isolated metallized areas 104-1, 104-2, which can be contacted separately and therefore subsequently subjected to different electrical potentials.

[0096] In an alternative process, the metallization in area 108 can also simply be converted into a non-conductive coating. Subsequently, areas 104-1 and 104-2 can be brought to suitable different potentials analogously to the procedure described above for the deposition of different toner particles 42 and 42B, so that in area 104-1 toner particles 42 of a first color and in area 104-2 toner particles 42B of a second, different color are applied precisely to the respective micromirrors 106, as shown in Fig. 9(b).

[0097] It goes without saying that this approach is not limited to two areas, but can be extended to more than two areas and more than two toners or colors.

[0098] Two or more areas 104-1, 104-2 of a security element 110 can also be arranged nested multiple times, as illustrated in Fig. 10. In the embodiment shown, the areas 104-1, 104-2 are arranged in the form of narrow, alternating strips, with adjacent strips each being separated by an intermediate area 108 with relief structures having a high aspect ratio. The strips 104-1, 104-2 are each coated, as described in Fig. 9, with electrically insulated metallizations 110-1, 110-2 and covered with toner layers 42, 42B of different colors.

[0099] The stripes 104-1, 104-2 advantageously have a width B below the resolving power of the human eye. For example, the stripes can have a width of less than 100 µm, preferably less than 50 µm, and particularly advantageously less than 25 µm. The period length P of the interlacing essentially corresponds to twice the stripe width; however, in practice, the spacing between the stripes, i.e., the width of the intermediate regions 108, must also be taken into account. The separating intermediate regions 108 are expediently made as narrow as possible, since they generally do not contribute to the desired optical effects.

[0100] It can also be advantageous to make the stripes 104-1 and 104-2 of different colors and widths. This is the case, for example, when one color is much lighter or darker than the other, or when a type of stripe is only metallic and has no chromatic color. For instance, in a flip image transitioning from a yellow to a blue display, the darker blue stripes 104-2 may be wider than the lighter yellow stripes 104-1, so that the overall brightness appears similar to the viewer and both images are approximately equally visible.

[0101] Such nested areas can be used, for example, to create flip images in which a first representation with a first color flips into a second representation with a second color. Referring to Fig. 11, a convex flip effect can be realized in a security element 110, for example, in which a convex-appearing first representation 112 with a first color, for example a red, convex "A", flips into a convex-appearing second representation 114 with a second color, for example a green, convex "B", when the security element 110 is tilted 116 (Fig.

[0102] 11(a)).

[0103] Fig. 11(b) schematically shows how the surface areas of the first and second representations 112, 114 according to Fig. 10 are divided into strips 104-1, 104-2. The strips 104-1, 104-2 are continuous even in the area of ​​the letters "A" and "B"; they appear very light there only due to the limited image quality of Fig. 11(b). For clarification, Fig. 11(c) shows the metallized area of ​​the continuous strips 104-1, 104-2 for representations 112, 114 without letters again separately.

[0104] The combined overall appearance of the two representations 112, 114 on the surface of the safety element 110 is shown schematically in Fig. 11(d). The vertical stripes on the left and right edges represent contact traces 118-1 and 118-2, respectively, for contacting the two areas 104-1 and 118-2.

[0105] 104-2 during the deposition of the charged colored toner particles 42, 42B.

[0106] Compared to conventional designs, for example, flip images based on relief structures coated with color-tilting interference layer structures, the security elements produced according to the invention offer in particular the following advantages:

[0107] The colors used in the two images can be chosen virtually arbitrarily; only a toner of the desired color is required. As mentioned, the toner particles are typically colored, for example, red, yellow, green, blue, magenta, cyan, or mixtures of these colors. Mixtures of two or more different colored toners, especially primary colors (cyan, magenta, yellow or red, green, blue), can also be used.

[0108] Furthermore, according to the invention, color and image motif are closely linked. In the embodiment shown in Fig. 11, for example, motif "A" is always red and motif "B" is always green. The color impression is different with color-shifting interference coatings. If, for example, a comparable reversible image with the letters "A" and "B" is generated according to the teaching of DE 102012020257 Al using a color-shifting interference system with a color change from magenta to green, then, depending on the lighting conditions, when tilted, "A" appears magenta and "B" green, or vice versa, "A" green and "B" magenta. It is also possible that both images appear in the same color and a color change only becomes visible at tilt angles where no motif change occurs.

[0109] It goes without saying that, in addition to the warp-flip effects shown for illustration, other flip effects with color changes can also be implemented. Furthermore, it is possible to use more than two colors and to nest more than two differently colored stripes within each other. However, with a larger number of colors, only a smaller area per color is available, so the representations become correspondingly darker. In this case, it can be advantageous, even with a larger number of colors, to nest only two differently colored stripes within each other locally. Such an approach can also simplify the contacting of the stripes.

[0110] Another application of the strip-shaped nesting of metallized areas concerns microimages under cylindrical lens arrays. Referring to the embodiment shown in Fig. 12, for example, in such a microlens-based security element 120, two differently colored image strips 124-1, 124-2 can be provided under each cylindrical lens 122. In the case of a flip image, approximately exactly two strips are provided per lens; in the case of two-color scrolling effects, the period is typically chosen to be slightly larger or smaller than the period of the lenses.

[0111] In such a design, alternating red and green colored image stripes 124-1, 124-2 can be produced by depositing, for example, red and green toner particles 42, 42B, as described above. The stripes 124-1, 124-2 themselves do not contain any relief structures, but are separated from each other by a relief embossing 126 with a high aspect ratio. As described in connection with Fig. 9, the intermediate areas covered with the relief embossing 126 can be demetallized after initial full-surface metallization, thereby electrically separating the metallization of the image stripes 124-1, 124-2, so that the image stripes can subsequently be coated separately with red and green toner particles 42, 42B.

[0112] The cross-sectional view in Fig. 12 shows the safety element 120 with the electrically insulating carrier film 22, the applied embossed lacquer layer 24 with the aforementioned relief embossing 126, the metallization 32, and the color coating of the image strips 124-1, 124-2 with toner layers 42, 42B of different colors. The cylindrical lenses 122 can, for example, be provided on a further film 128.

Claims

Patantic proverbs 1. Method for manufacturing a data carrier, in particular a foil element, which has a metal layer present at least in certain areas and a colored layer arranged in relation to the metal layer, wherein the method comprises the steps: B) Providing an electrically insulating support, in particular an electrically insulating support film, M) the partial application of an electrically conductive, metallic coating in first areas onto the substrate, such that different second areas on the substrate are either non-conductive or electrically insulated from the metallic coating of the first areas, T) Application of a first toner with toner particles to the partially metallized substrate, E) Applying an electric field to selectively deposit the toner particles of the first toner either only in the first regions or only in the second regions of the carrier, and F) Fixing the deposited toner particles in the first or second areas of the carrier.

2. The method according to claim 1, characterized in that the electrically insulating substrate is provided with relief structures onto which the electrically conductive metallic coating is applied in certain areas in step M), wherein the relief structures provide an optical effect at least in certain areas and / or enable lateral structuring of the metallic coating.

3. The method according to claim 2, characterized in that the relief structures are molded in an embossing lacquer and are produced with maximum embossing depths between 0.1 µm and 50 gm, preferably between 1 gm and 5 gm.

4. Method according to at least one of claims 1 to 3, characterized in that in a step M2) the second areas are provided with an electrically conductive metallic coating which is electrically insulated from the metallic coating of the first areas, preferably that the carrier in the first and second metallized areas is provided with relief structures generating optical effects, the optical effects of which are different and / or are visible under different viewing angles.

5. Method according to at least one of claims 1 to 4, characterized in that the electrically insulating carrier is provided with relief structures and the first and / or second metallized areas are produced in step M) or M2) to precisely match the relief structures of the carrier, preferably by The carrier is provided with a demetallization relief structure in the third area separating the first and second areas for selective demetallization of these areas. In step M) or M2), a large-area metallization is first applied to the first, second, and third regions, and the metallization in the third regions is selectively removed using the demetallization relief structure, so that the demetallized third regions electrically separate the first and second regions from each other.

6. Method according to at least one of claims 1 to 5, characterized in that before, after, or together with the application of the first toner, a second toner with toner particles is applied to the substrate, and in a step E2), an electric field is applied to deposit the toner particles of the second toner onto the first or second metallized regions, which are different from those of the first toner.

7. Method according to at least one of claims 1 to 6, characterized in that the first and second areas are nested within each other, the nesting preferably taking place on a length scale below the resolving power of the human eye.

8. Method according to at least one of claims 1 to 7, characterized in that the first toner and / or optionally the second toner is applied with charged toner particles, preferably that the first and second toner is applied with oppositely charged toner particles.

9. Method according to at least one of claims 1 to 8, characterized in that the first toner and / or optionally the second toner is applied in the form of a liquid toner.

10. Method according to at least one of claims 1 to 9, characterized in that, when an electric field is applied, the metallic coating of the first areas and / or a metallic coating of the second areas is brought to a predetermined electrical potential.

11. Safety element or semi-finished product for the manufacture of a safety element, in particular manufactured according to one of claims 1 to 10, comprising first areas and second areas different from the first areas. wherein the first areas are provided with a first metallization and a first toner layer consisting of toner particles lying above the metallization, the second areas are not metallized or are provided with a second metallization that is electrically isolated from the first metallization, and The second areas are either not coated with a toner layer, or are coated with a second, different toner layer.

12. Safety element or semi-finished product according to claim 11, characterized in that optically effective relief structures are present in the first areas, which preferably offer an optical effect at least in certain areas.

13. Safety element or semi-finished product according to claim 11 or 12, characterized in that the second areas are provided with a second metallization and optically effective relief structures are present in the second areas, which preferably offer at least in some areas an optical effect that differs from the optical effect of the first areas.

14. Safety element or semi-finished product according to claim 13, characterized in that the first and second areas, by being covered with the different toner layers, offer the optical effects of the optically effective relief structures in different colors.

15. Microlens-based security element comprising a micro-image layer and a one- or two-dimensional microlens array for viewing the micro-image layer, characterized in that the micro-image layer is produced by a method according to one of claims 1 to 10 or is formed from a semi-finished product according to one of claims 11 to 14.

Images