EP2240330A2

EP2240330A2 - Method for producing a microstructure

Info

Publication number: EP2240330A2
Application number: EP08866269A
Authority: EP
Inventors: Winfried HOFFMÜLLER; Theodor Burchard; Marius Dichtl; Patrick Renner; Michael Rahm; Manfred Heim; Lars Hoffmann; Manfred Dotzler; Ralf Liebler; Mario Keller
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2007-12-21
Filing date: 2008-12-17
Publication date: 2010-10-20
Anticipated expiration: 2028-12-17
Also published as: US8685488B2; US20110045248A1; DE102007062089A1; WO2009083146A3; EP2240330B1; WO2009083146A2

Abstract

The invention relates to a method for producing a microstructure on a carrier (22), in which a carrier (22) is provided with a relief structure (26, 28) having elevations (26) and depressions (28), and in which the elevations (26) and/or depressions (26) are arranged in the form of the desired microstructure, and an imprint substance (30; 34) is transferred onto the relief structure (26, 28) by means of a printing tool, wherein the viscosity of the imprint substance (30; 34) is chosen in such a way that the imprint substance (30; 34) is transferred selectively either substantially only onto the elevations (26) or substantially only into the depressions (28) of the relief structure.

Description

Method for creating a microstructure

The invention relates to a method for producing a microstructure on a support, a device for carrying out the method, a microstructure that can be produced in this way, and an article having such a microstructure.

Data carriers, such as valuables or identity documents, but also other objects of value, such as branded articles, are often provided with security elements for the purpose of security, which permit verification of the authenticity of the data carrier and at the same time serve as protection against unauthorized reproduction. The security elements can be embodied, for example, in the form of a security thread embedded in a banknote, a covering sheet for a banknote with a hole, an applied security strip or a self-supporting transfer element which is applied to a value document after its production.

Security elements with optically variable elements, which give the viewer a different image impression under different viewing angles, play a special role, since they can not be reproduced even with high-quality color copying machines. For this purpose, the security elements can be equipped with security features in the form of diffraction-optically effective microstructures or nanostructures, such as with conventional embossed holograms or other hologram-like diffraction structures, as described, for example, in the publications EP 0330 733 A1 or EP 0 064 067 A1.

For some time, so-called Moire magnification arrangements have also been used as security features. The basic operation of such Moire magnification arrangements is described in the article "The moirέ Magnifier ", MC Hutley, R. Hunt, RF Stevens and P. Savander, Pure Appl. Opt 3 (1994), pp. 133-142.) In short, moire magnification thus indicates a phenomenon to be considered As with any pair of similar screens, this results in a moire pattern, in which case each of the moire fringes appears in the form of an enlarged and rotated image of the repeated elements of the image grid ,

Based on this, the object of the invention is to avoid the disadvantages of the prior art and, in particular, to specify an improved method for producing a microstructure on a carrier that can be used in the production of micro-optical moiré magnification arrangements.

This object is achieved by the method having the features of the main claim. An associated device for carrying out the method, an article with such a microstructure and a microstructure that can be produced in this way are specified in the independent claims. Further developments of the invention are the subject of the dependent claims.

According to the invention, in a method of producing a microstructure on a support

a carrier provided with a relief structure having elevations and depressions, and wherein the elevations and / or depressions are arranged in the form of the desired microstructure, and is transferred with a printing tool, an imprint material on the relief structure, wherein the viscosity of the imprint material is chosen so that the imprint material is transmitted selectively either substantially only on the elevations or substantially only in the recesses of the relief structure.

The chosen formulation, according to which the imprint material is selectively transferred either essentially only to the elevations or essentially only into the depressions of the relief structure, takes account of the fact that, for example, in the transfer of the imprint material into the depressions a slight toning film is used in practice can remain on the elevations of the relief structure, which does not affect the visual impression of the microstructure.

According to a preferred first aspect of the invention, a highly viscous imprint material is selectively transferred substantially only to the elevations of the relief structure using the printing tool. The high-viscosity printing material is advantageously transferred in a layer thickness which is smaller than the structural depth of the relief structures. The structure depth indicates the height difference between elevations and depressions in the relief structure. Preferably, the transferred layer thickness of the imprint material is less than 50%, more preferably less than 30% and most preferably even less than 15% of the structural depth of the relief structures.

Advantageously, the desired size and / or depth of the transfer areas, in which the imprint material is to be transferred to the elevations of the relief structure, predetermined. The hardness and the surface roughness of the printing tool and the pressure during the transfer of the imprint material are then selected according to the desired size and / or depth of the transmission ranges. The pressure during transfer of the imprint material is expediently chosen so low that the imprint material is not squeezed. The imprint material can also be transferred substantially without pressure to the relief structure, wherein a predetermined distance between the printing unit and the relief structure is filled by the imprint material.

With particular advantage, the printing material is transferred in the offset printing process or in the flexographic printing process. In order to achieve the best possible results, it may be necessary to modify the standard offset printing process. For example, instead of a (rubber) blanket, a rubber roller can be used to allow in particular a shock and seam-free as well as more homogeneous and precise printing of the raised structures. Instead of a (rubber) blanket can in principle also be provided a metal roller, which then offers as a counter-pressure cylinder, a rubber roller. Instead of a printing plate, the use of a directly coated with a polymer cylinder in question to print shock and seamless. In further modifications, the pressure cylinder can be dispensed with. Instead, a direct coloring of the

Rubber blanket or the rubber roller or in general the Farbübertragszy- Linders over the entire surface or with a motif analogous to a high-pressure process. The curing can be carried out under inert gas in order to cure even extremely thin films well.

The printed, raised areas can be provided with protective lacquer to prevent re-dissolution in the following process. In particular, a substance having a viscosity of between about 10 mPa * s and about 200 Pa * s, preferably between about 800 mPa * s and about 150 Pa * s at room temperature, is selected as the imprint material. In this case, it is also possible to take into account any structural viscosity of the print material that may be present. Suitable printing materials are, in particular, a printing ink, preferably an offset printing ink, a radiation-curable, thermosetting or oxidatively drying printing ink, an adhesive, such as a highly viscous heat-sealing lacquer, and / or a water-activatable adhesive system. All printing materials can be pigmented with an effect and in particular contain luminescent pigments, thermochromic pigments, metal pigments and / or pearlescent pigments.

Particular preference is given to using imprint materials which have a certain stickiness, ie which are not tack-free. In the context of the present description, the term "non-tack-free" also means tacky in the sense of a sticky surface.The test can be carried out by the following test: coated film pieces of about 100 cm ² are stacked and loaded with a weight of 10 kg and 72 Hours stored at 40 ^° C. If the film pieces can then only be separated from one another with damage to the coatings, the coating should be considered tack-free.

If an adhesive is transferred as an imprint material, the relief structure can be brought into contact with a transfer medium after the transfer of the adhesive, and a transfer substance can be transferred from the transfer medium to the adhesive elevations of the relief structure. The transfer medium may be, for example, a coated film, a hot stamping film or a transfer roller. As transfer agents come in particular Colors, colored films, effect coatings, effect pigments, color, black or white pigments, dyes, effect layers or metallizations into consideration. Also, portions of a releasable hologram or other hologram-like diffraction structure may be selected as the transfer material and transferred to the adhesive-coated protrusions, as described in more detail below. The possibly still sticky adhesive layer with the transfer substance can be cured in a further step.

The relief structure can also be dusted directly after the transfer of the adhesive with a transfer substance, wherein any excess of the transfer material can be removed after dusting, preferably by a non-contact method. In particular, blowing, sweeping, brushing, electrostatic removal or a combination of two or more of these methods may be considered. The transfer substance can also be optimized for removal with an electrostatic process. The unit which receives the surplus contactlessly can itself be mechanically cleaned. The excess can be at least partially returned to the process. The removal of the excess can also be done only after the curing of the highly viscous adhesive layer. Direct dusting is particularly suitable for metal pigments, for example for bronzing the embossing lacquer layer.

In an advantageous development of the method, after the transfer of the adhesive, a laminating film is laminated onto the relief structure. The laminating film serves on the one hand to protect the microstructure, on the other hand it allows to provide the surface of the laminating film opposite the microstructures with an adhesive layer which has a strongly adhering effect Embedding the layer sequence of carrier, microstructure and laminating in a security paper, document of value or the like allows.

By transferring the adhesive only to the elevations of the relief structure, a large number of microcavities filled with air are created in the area between the laminating film and the relief structure. These microcavities have the refractive index of the air contained (n = 1) and therefore have a large refractive index difference to the relief structure material (n∞l, 5). As a result, a desired refractive or optically variable effect of the relief structures is obtained despite film lamination, as explained in more detail below with reference to some embodiments.

According to a further embodiment of the invention, a transfer material provided with an adhesive is transferred to the elevations of the relief structure as imprint material. As a transfer agent may in particular a color, a colored film, an effect, effect pigments, colored pigments, black pigments, white pigments, dyes, effect layers, a metallization, a portion of a hologram or a hologram-like diffraction structure or a farbkippendes element, in particular a farbkippendes thin-film element or a at least one liquid crystal layer-containing element can be selected.

In visually particularly attractive variants, the microstructure represents the motif image of a micro-optical magnification arrangement which generates a predetermined target image after the application of a viewing grid on the front side of a security element. The transfer substance additionally provides the micro-optical magnification arrangement with a backside effect, for example a backside hologram or a backside color-shift effect, as explained in more detail below. In one embodiment of the invention, different high-viscosity printing materials, in particular different-colored or provided with different effect pigments imprint materials can be transferred.

In part, the elevations of embossed relief structures toward the edges have a gentle drop in height. In order to avoid possible unevenness in printing, before transferring the desired imprint material, a high-viscosity lacquer layer can be transferred, which compensates for the sloping edges of the elevations.

The elevations and / or depressions of the relief structure can also be rounded to support the method, be provided with continuous transitions and / or with additional structures. For example, the elevations can be formed with a sharply delimited, upstanding edge region in order to limit the transferred imprint material even more to the area of the elevations. Such edge elevations are typically of the order of 1 μm. Optionally, the requirements for the viscosity of the imprint material can be reduced by this measure.

The elevations of the relief structure can also be provided with a microrelief structure, in particular with a diffractive microrelief structure for producing a hologram or a hologram-like diffraction structure. Alternatively, the elevations can also be provided with an achromatic, ie not colored, micro-relief structure. The elevations of the relief structure may also have a further superstructure, such as spikes, which hold the imprint material better on the surveys. Such a measure is particularly suitable for narrow lines to prevent squeezing of the imprint material As a printing material can also be a high-viscosity resist, especially a colored highly viscous resist are selected. The use of such a resist lacquer is particularly suitable in conjunction with metallizations of the relief structure, since then the non-raised areas can be demetalized in a targeted manner.

For advantageously producing a microstructure with two microrelief structures visible from opposite sides with a common, perfectly matched negative pattern, the relief structure provided in the elevations with a microrelief structure is metallized over the entire area and a highly viscous resist lacquer is selectively transferred to the elevations of the metallized relief structure. After transfer, the relief structure is demetallized in regions not protected by resist coating, the relief structure is provided with an embossing lacquer layer after the demetallization step, and a further microrelief structure, in particular a diffractive microrelief structure, is embossed into the embossing lacquer layer.

Thereafter, the relief structure is metallized again, it is again a highly viscous resist coating selectively on the elevations of the relief structure transmitted, the re-metallized relief structure is demetallized again in areas not protected by resist coating and the resist is optionally removed. If desired, a further high-viscosity ink can then be transferred to the elevations, so that the microrelief structures appear colored from the top side.

A demetallization step can be saved by selectively transferring a highly viscous resist to the elevations of the full-surface metallized relief structure and providing this resist with the further microstructure-structure embossing. For this purpose, for example a thermoplastic resist is used. Then the relief structure is metallized again, it is again a highly viscous resist coating selectively transferred to the elevations of the relief structure. The re-metallized relief structure is then demetallized in areas not protected by resist, thereby removing both the first and second metallizations.

If larger contiguous Demetallisierungsflächen provided it is preferably printed before the metallization, a soluble wash in the form of the desired Demetallisierungsbereichs on the relief structure, and washed the wash after the metallization together with this by a solvent. Further details of such a washing process can be found in the publication WO 99/13157, the disclosure of which is incorporated in the present application in this respect.

In addition, both during and after the embossing distance tracks for setting a defined distance and / or pressure when transferring the imprint material can be applied. The thickness of additional spacer tracks of clearcoat, which need not occur in the final product, can be chosen arbitrarily within wide limits. Depending on the available printing machine strips of defined thickness can facilitate the setting of a defined distance and / or pressure, which prevails between blanket and film. Such spacing tracks may, when at least partially taken into account in embossing, form adjacent, uniformly low lying and uniformly elevated areas.

Such areas without further structuring can also be advantageously used as indicator traces and recorded by measurement. Thereby For example, the application of paint and / or the pressure can be controlled according to a predetermined, maximum permissible toning film in the low-lying areas or the color saturation in the high-lying areas of the indicator tracks.

The imprint material can also be provided with particles of defined size, which prevent a crushing of the imprint material during transfer and thus also act as a kind of spacer.

In general, the use of relatively hard printing blankets in the method of the first aspect of the invention is advantageous since a hard blanket can reach deeper points of the relief structure harder. Softer blankets, on the other hand, provide a smoother, lower pressure and can help offset imperfections in the overall system. Depending on the available equipment and the desired results, therefore, a suitable compromise for the hardness of the printing blanket must be found.

In general, the application of the high-viscosity printing material can also take place in several layers and / or in the form of a motif. As the uppermost layer, it is also possible to transfer a high-viscosity clearcoat. If toning is unavoidable in a motif, for example because of too small height differences or too large open areas, the desired view from above, ie from the direction of the raised structures, can avoid the problem by subsequently printing a low-viscosity opaque white formulation. The existing Tonungsfilm in the valleys is thereby covered in white, as explained in detail below in connection with the second aspect of the invention. For reverse consideration can also first the opaque white formulation are printed and then the high-viscosity printing ink.

If a relatively low-viscosity imprint material is to be transferred to the elevations of the relief structure, a pronounced intrinsic viscosity of the imprint material is advantageous.

Intrinsic viscosity of a liquid or the imprint material in the sense of this invention is the property of exhibiting a lower viscosity at high shear forces. The stronger the shear that acts on the imprint material, the less viscous it is. Since the viscosity does not remain constant, this is classified as non-Newtonian behavior. The decrease in viscosity results from a structural change in the imprint material, which ensures that the individual particles of the printing material (for example polymer chains) can better slip past one another.

For example, printing inks are converted by mechanical action, such as stirring, shaking, trowelling or doctoring, of a solid or pasty consistency in a flowing consistency. In offset printing, this is done by the color splitting in the inking unit, reinforced by oscillating distributor rollers.

If the viscosity does not increase immediately after reducing the shear force, this behavior is called thixotropy. However, it is preferred to have an immediate increase in viscosity after application of the imprint, i. the imprint material should stand or not run immediately.

According to a likewise advantageous second aspect of the invention, the printing tool is used to print an imprint material, in particular a low-viscosity printed substance selectively transmitted substantially only in the recesses of the relief structure. In the selection of the low-viscosity imprint material, the surface tension of the imprint material is preferably also matched to the surface energy of the relief structure.

In this aspect, an imprint material having a viscosity of between about 3 mPa * s and about 1500 mPa * s at room temperature is chosen as the imprint material. Suitable printing materials are printing inks, in particular dye solutions, pigment dispersions, inks or else preferably low-viscosity liquid-crystal solutions. In the latter case, the depressions of the relief structure can also be formed with alignment structures for aligning liquid crystals. The dye solutions or pigment dispersions can optionally be binder-containing.

The transfer of the imprint material can also take place in two steps, wherein initially a low-viscosity printing ink or liquid crystal solution is transferred with a low binding body portion, which selectively flows into the depressions of the relief structure. Then, a solution with a high binding body portion is transferred, which fixes the printing ink or liquid crystal solution in the depressions of the relief structure.

In further variants of the invention, a low-viscosity adhesive or a low-viscosity resist can also be selected as the imprint material. All imprint materials can be pigmented with effect, in particular luminescent pigments, thermochromic pigments, metal pigments and / or pearlescent pigments can be contained.

Also in this aspect of the invention may advantageously different low-viscosity printing materials, in particular different colors or with different effect pigments provided imprint materials are transferred to the wells.

The elevations of embossed relief structures are often surrounded by deep areas at their edges. If only a small amount of an imprint material is transferred, then the imprint material initially accumulates in the region of these edges. If this effect is desired for design reasons, for example in order to provide the elevation patterns with a circumferential color edge, then the imprint material can be transferred in such a small amount that during the transfer it only flows into the edge regions of the recesses immediately surrounding the elevations.

On the other hand, if the recesses are to be filled evenly, it may be expedient to transfer a small amount of a low-viscosity clearcoat material before the transfer of the desired imprint material, which fills the edge regions of the recesses which directly surround the elevations. In the subsequent transfer, the printing material then flows evenly into the recesses.

The elevations and / or depressions of the relief structure can also be rounded, provided with continuous transitions and / or with additional structures to support the method. In particular, the recesses may be formed with rounded transitions to the elevations in order to avoid the previously described effect of filling of the recesses starting from the edge regions.

In other embodiments, the bumps may also be provided with a lotus structure to produce low wettable bump surfaces. Such lotus structures reduce the contact area between the surveys and the imprint material to be transferred, so that it practically can not adhere to the surface of the surveys and flows more easily into the wells. The depressions of the relief structure can also be provided with a microrelief structure, for example a diffractive or achromatic microrelief structure.

Of course, the two aforementioned aspects of the invention can also be combined with each other. Thus, for example, in a first step, a first highly viscous imprint substance can be selectively transferred substantially only to the elevations of the relief structure, and in a second

Step a second low-viscosity imprint selectively transmitted substantially only in the recesses of the relief structure. With suitable process control, the low-viscosity printing material can also be selectively transferred first into the depressions and then the high-viscosity printing material selectively onto the elevations of the relief structure.

The elevations and depressions of the microstructure preferably form microstructure elements having a line thickness between approximately 1 μm and approximately 10 μm and / or with a structure depth between approximately 0.5 μm and approximately 20 μm, preferably between approximately 1 μm and approximately 10 μm ,

The method according to the invention can be used with particular advantage in the production of micro-optical moiré magnification arrangements, as described in the publications DE 10 2005 062 132 A1 and WO 2007/076952 A2, in the production of moiré-type micro-optical magnification arrangements, as described in the applications DE 10 2007029 203.3 and PCT / EP2008 / 005173, and in the production of modulo magnification arrangements, as described in particular in the applications PCT / EP2008 / 005171 and PCT / EP2008 / 005172 used become. All of these micro-optical magnification arrangements contain a motif image with microstructures which, when viewed with a suitably coordinated viewing grid, reconstructs a predetermined target image. As explained in more detail in the abovementioned publications and applications, a multiplicity of visually attractive enlargement and movement effects can be produced which lead to a high recognition value and a high security against forgery of the security elements equipped therewith. It should be emphasized, however, that the invention is not limited to these applications. Rather, the method described can be advantageously used in the production of other security elements, for example in the production of microtext printing on paper or film.

In an advantageous development of the invention, the microstructure forms a motif image, which is divided into a plurality of cells, in each of which imaged regions of a predetermined target image are arranged. The lateral dimensions of the imaged regions are preferably between about 5 μm and about 50 μm, in particular between about 10 μm and about 35 μm. In the case of the above-mentioned micro-optical moiré magnification arrangements, the imaged areas of the cells of the motif image are in each case miniaturized images of the predetermined reference image, which are completely located within a cell. In the moiré-type micro-optical magnification arrangements, the imaged regions of a plurality of spaced-apart cells of the motif image, taken together, each represent a reduced and possibly linearly imaged image of the target image whose extent is greater than one cell of the motif image. In the most general case, the magnification arrangement represents a modulo magnification arrangement in which the imaged areas of the cells of the model represent each time represented by a modulo operation, incomplete sections of the predetermined target image.

The security element preferably further comprises a viewing grid of a plurality of viewing grid elements for reconstructing the predetermined target image when viewing the motif image using the viewing grid. The lateral dimensions of the viewing grid elements are advantageously between about 5 μm and about 50 μm, in particular between about 10 μm and about 35 μm.

In the special case of a micro-optical moiré magnification arrangement, a motif image of a planar periodic or at least locally periodic arrangement of a multiplicity of micromotif elements is preferably applied as the microstructure. The lateral dimensions of the microparticles are advantageously between about 3 μm and about 50 μm, preferably between about 10 μm and about 35 μm. In addition, the opposite side of the carrier is expediently provided with a planar periodic or at least locally periodic arrangement of a multiplicity of microfocusing elements for moire-magnified viewing of the micro-motif elements of the motif image. In some embodiments, it is appropriate to arrange the microfocusing elements and the micromotif elements on the same side of the carrier. Bilateral designs in which a micromotif element arrangement can be viewed through two opposing microfocusing element arrangements also come into question and are explained in greater detail below in this description.

In moiré magnification arrangements, even with incomplete and irregular coloring of the elevations, regular structures can be seen when viewed through the lens array, as shown above explained functional principle in each case many individual structures - here the elevations and depressions of the relief structure - are averaged to the visible structure. Therefore, it is also possible to provide as elevations fragmentary, raised structures that overlap only when viewed through the microlenses and form the desired motif. By mixing colorless areas, the achievable maximum contrast is then somewhat reduced.

This principle can also be used to form differently colored microstructure elements. If, for example, a first image component with more intense colors appears as a second image component, then the relief structure can be formed, for example, such that each elevation carries the first pictorial component, but only every second elevation carries the second pictorial component. When viewed, the second part of the picture appears with a lower color saturation than the first part of the picture. In the same way can be produced by different colors of the same image component for the viewer mixed colors.

In addition to the elements already mentioned, the carrier with the applied microstructure may also be provided with one or more functional layers for use as a security element for security papers, value documents and the like, in particular layers with visually and / or machine-detectable security features, protective or cover layers , Adhesive layers, heat sealing equipment and the like come into consideration.

To protect against counterfeiting and / or to facilitate further processing, the microstructure applied to the carrier is advantageously provided with a transparent topcoat. The relief structure of the carrier can be formed, for example, by a structured, self-adhesive resist coating whose areas, after structuring, are high or low, forming the elevations and depressions of the relief structure. Because of the achievable high resolution, the relief structure is formed with particular advantage by an embossed structure with elevations and depressions.

The relief structures of the support are preferably produced by embossing into thermoplastic and / or radiation-curing lacquers.

The invention also includes an apparatus for carrying out the described method with a printing tool for transferring an imprint material selectively either only to the elevations or only into the depressions of the relief structure and an article, in particular a data carrier or a security element, with one in the manner described generated microstructure. The microstructure is preferably formed by microstructure elements having a line thickness between about 1 μm and about 10 μm and / or with a pattern depth between about 0.5 μm and about 20 μm, preferably between about 1 μm and about 10 μm. Of course, the microstructures can also contain areal areas and can have both positive elements and negative elements. The elevations and depressions may also at least partially form a coherent network.

The support of the microstructure may in particular comprise a transparent plastic film or else a paper layer. Advantageously, the support has a thickness of between about 3 μm and about 50 μm, preferably between about 5 μm and about 25 μm. According to a particularly preferred development, the article contains a micro-optical moire magnification arrangement of the type already described and with the dimensions already indicated.

In a preferred embodiment, the article represents a security element, in particular a security thread, a label or a transfer element for application to a data carrier. The security element can be equipped for this purpose, for example, heat sealable. The total thickness of the security element is suitably between about 20 microns and about 60 microns, preferably between about 30 microns and about 50 microns.

It is likewise preferred if the article is a data carrier, in particular a banknote, a document of value, a passport, a passport card or a document.

The article with the applied microstructure can moreover be equipped with one or more functional layers, in particular with layers with visually and / or machine-detectable security features. In this case, for example, all-surface or partial reflective, high-refractive or color-tilting layers are suitable, or else polarizing or phase-shifting layers, opaque or transparent conductive layers, soft or hard magnetic layers or fluorescent or phosphorescent layers.

The invention further comprises a microstructure which can be produced in the described manner and which has a relief structure with elevations and depressions, the shape and arrangement of which form the structural elements of the microstructure, and in which a printing material selectively uses a printing tool either transferred only to the elevations or only in the depressions of the relief structure.

The invention further comprises a method for producing a high-resolution printing layer on a target substrate, in which a microstructure is initially produced by a method of the type described above, in which the imprint material is selectively transferred essentially only to the elevations of the relief structure. The microstructure thus produced is then brought into contact with the desired target substrate and the imprint material present on the elevations of the relief structure is transferred to the target substrate.

Further embodiments and advantages of the invention are explained below with reference to the figures. For better clarity, a scale and proportioned representation is omitted in the figures.

Show it:

1 is a schematic representation of a banknote with an embedded security thread and a glued transfer element,

2 in (a) and (b) are schematic representations for explaining the principle of the invention,

3 shows a combination of the variants of the invention of FIGS. 2 (a) and (b), 4 schematically shows the layer structure of a moire magnification arrangement in cross-section,

5 shows an exemplary embodiment in which a microscopic structuring according to the invention is combined with a conventional macroscopic structuring,

Fig. 6 in (a) to (c) intermediate steps in the production of a colored

Moire magnification arrangement, which is combined with a metallization,

7 in (a) to (d) intermediate steps in the production of a Moirέ-

Magnification arrangement combined with a hologram,

8 shows a two-color microstructure according to a further exemplary embodiment of the invention,

9 in (a) to (e) intermediate steps in the production of a security element with two different holograms visible from opposite sides, which have a common and thus perfectly matched negative pattern,

10 shows a moiré magnification arrangement, on the lens array of which an adhesive layer is transferred by means of a method according to the invention,

11-13 each embedded in paper window security thread according to an embodiment of the invention, 14 in (a) and (b) intermediate steps in the production of a further microstructure according to the invention,

15 in (a) and (b) intermediate steps in the production of a microstructure according to the invention with backside effects,

16 in (a) and (b) intermediate steps in the production of a microstructure according to the invention with two different, visible from opposite sides holograms,

17 in (a) to (c) intermediate steps in the production of a microoptical magnification arrangement according to the invention with colored metallic microstructures,

18 in (a) to (c) intermediate steps in the production of further inventive metallized microstructures, and

19 shows in (a) and (b) the use of a microstructure according to the invention for producing a high-resolution print layer on a target substrate.

The invention will now be explained using the example of security elements for banknotes. Fig. 1 shows a schematic representation of a banknote 10, which is provided with two security elements 12 and 16 according to embodiments of the invention. In this case, the first security element represents a security thread 12 which emerges in certain window areas 14 on the surface of the banknote 10, while it is embedded in the intervening areas in the interior of the banknote 10. The second security element 16 is formed by a glued transfer element of any shape educated. In other embodiments, the security element 16 may also be designed in the form of a cover film, which is arranged in or above a window area or a through opening of the banknote.

First, the principle of the invention will be explained with reference to the schematic diagrams of FIG. Subsequently, with reference to the other figures, some specific embodiments of security elements according to the invention will be described by way of example.

The security element 20 shown in FIGS. 2 (a) and (b) contains, for example, a transparent PET film as the carrier film 22. On the upper side of the carrier film 22, a UV-curing embossing lacquer layer 24 is applied, into which an embossed structure with elevations 26 and depressions 28 in the form of a desired microstructure is embossed.

The nature of the microstructure is only of secondary importance to the present invention. For example, the microstructures in question may be micro-optical magnification arrangements, such as moiré magnification arrangements, moirέ-type micro-optical magnification arrangements or modulo-magnification arrangements, or also other micro-optical structures, such as blazed grating structures, DOE (diffractive optical element). Structures, computer-generated holograms (CGH) or other hologram-like diffraction structures, around microlens structures or fresnel lenticular structures. Particular advantages of the invention in high-resolution microstructures, the microstructure elements are formed with a line thickness between about 1 micron and about 10 microns and with a structure depth between about 0.5 microns and about 20 microns. The elevations and depressions of the embossed structure in the present invention in each case form the microstructure. turelemente the microstructure, so that the dimensions of the elevations or depressions correspond to those of the microstructure elements.

In order to selectively apply printing ink substantially only to the elevations 26 of the embossed structure in a first variant of the invention, the embossed pattern is printed, for example, in offset printing at low pressure with a high-viscosity printing ink 30, as shown in FIG. 2 (a). Radiation-curing or thermosetting offset printing inks having a dynamic viscosity of between 800 mPa * s and 150 Pa * s at room temperature are particularly suitable. A thin, not fast drying paint can be achieved, for example, by rubbing the paint through a system consisting of several rotating rollers, dispensing with volatile solvents.

The ink 30 is applied in a layer thickness d, which is significantly smaller than the depth t of the embossed structures. The hardness of the printing tool and optionally a counter roll and the pressure when transferring the ink are each selected according to the desired size and depth of the transfer areas 32. On the one hand, the pressure during transfer is chosen to be so low on the one hand that the printing ink 30 is not squeezed, but on the other hand high enough that ink is transferred in the area of the elevations 26. By setting a higher pressure, the transfer area 32 can also be increased. If, for example, there are more than two height levels in the case of an embossed structure, not only is the top height level in contact with the ink 30 experienced during the printing process, then different color quantities can be transferred depending on the level. The relationship between pressure and size of the transmission range is not linear; from a very high level, color can even be squeezed out by pressure. In a particularly advantageous variant of the method, the printing ink is transferred to the embossing structure virtually without contact pressure, a defined distance between the application unit and the surface of the embossing structure being filled by the printing ink on or on the application unit.

In the described procedure and sufficiently low pressure no contact between the high-viscosity ink 30 and the recesses 28 of the embossed structure, so that selectively substantially only the elevations 26 of the microstructure are provided with color and a gravure typical, full-tone Tonungsfilm is avoided. As explained in more detail below, not only printing inks but also other imprint materials such as an adhesive or a resist lacquer can advantageously be selectively transferred to the elevations 26 of an embossed structure with the described method.

Embossed structures can be readily prepared by methods known per se with the highest accuracy of the dimensions of their elevations and depressions. Due to the selective transfer of the highly viscous printing ink only on the elevations of the embossed structures, the high resolution of the embossed structure is transferred to the printed image, so that a printed image can be produced with an extraordinarily high resolution.

With reference to FIG. 2 (b), according to a second variant of the invention, printing ink can also be selectively transferred essentially only into the depressions 28 of the embossing structure. For this purpose, for example, in flexographic printing or intaglio printing, such a low-viscosity printing ink 34 is applied to the embossed structure that the printing ink 34 flows into the depressions 28 and leaves the elevations 26 uncovered. In addition to the choice of the Viscosity and the surface tension of the ink are matched to the surface energy of the embossed structure.

Suitable printing inks for this variant of the invention are, in particular, dye-based solutions, pigment dispersions or inks having a viscosity of between 3 mPa * s and 1500 mPa * s at room temperature. In this variant of the invention, in addition to printing inks, other low-viscosity printing materials, such as low-viscosity adhesives or liquid-crystal solutions, can also be transferred selectively into the depressions 28.

The transfer of the ink into the recesses 28 can also be done in two steps. In this case, first a low viscosity ink is transferred with a low binder content, which selectively flows into the recesses 28 of the embossed structure. Subsequently, a solution with a high binder content is transferred, which fixes the colorants of the printing ink in the recesses 28 of the embossed structure and subsequently embedded in a binder matrix.

The selective transfer of the imprint materials on the elevations or into the recesses according to the first or second variant of the invention can be further enhanced by targeted structuring of the elevations or depressions. For example, in the variant of FIG. 2 (a), the elevations 26 can be formed with a sharply delimited, upstanding edge region which delimits the raised microstructure elements. The imprint material transferred to the elevations 26 is thus limited even more to the region of the elevations 26. The upstanding edge region may have, for example, a height of about 1 .mu.m to 2 .mu.m. Optionally, the requirements for the viscosity of the imprint material can be reduced by this measure. In the variant of FIG. 2 (b), for example, the elevations 26 may additionally be provided with a lotus structure which produces a slightly wettable elevation surface. The lotus structures reduce the contact area between the protrusions and the transferred imprint material, so that it can not adhere to the surface of the elevations 26 practically and flows more easily into the recesses 28. Optionally, the requirements for the viscosity of the imprint material can be reduced by this measure.

If a low-viscosity solution of nematic liquid crystals is selected as the imprint material, the recesses 28 can be provided with alignment structures for aligning liquid-crystalline material. After removing the solvent, the aligned nematic liquid crystal material is crosslinked and fixed. The resulting birefringent structures can be viewed in front of a suitable reflective background by means of a polarizer, for example the lens array of a micro-optical magnification arrangement described below. By different alignment directions of the alignment structures, the illustrated motif can be further structured.

In order to allow a particularly uniform flow of the ink into the recesses 28, it is also advisable not to allow the elevations 26 to grow out of the substrate vertically, but to allow the depressions 28 to pass into the elevations 26 with rounded transitions, as shown in FIG 2. This will in particular avoid that ink 34 accumulates at the transitions between elevations and depressions. Alternatively, before transferring the desired printing ink, a small amount of low-viscosity clearcoat can be transferred first, which fills up such transitions. The variants of the invention of FIGS. 2 (a) and (b) can also be combined with each other as shown in FIG. In the case of the security element shown schematically there, in a first step, a first highly viscous printing ink 30 was selectively applied substantially only to the elevations 26 of the embossed structure. In a second step, a second low viscosity ink 34 was then selectively transferred substantially only to the recesses 28 of the embossing pattern. As can be seen from FIG. 3, the microstructure is not flattened or weakened by the coating with the first printing ink 30, so that the selective transfer of the second printing ink 34 can take place as described above.

With proper matching of the printing inks 30, 34, the first printing step can even improve the suitability of the microstructure for the transfer of the second printing ink 34, for example by applying a printing ink 30 as the first printing ink having ink-repelling properties for the second printing ink 34. With suitable process control, the order of the printing steps can in principle be reversed and first the low-viscosity printing ink in the wells and then the high-viscosity printing ink are transferred to the surveys.

Overall, the embodiment of FIG. 3 appears both when viewed 36 from the top, and when viewed 38 from the bottom with microstructures of a first color (the color of the first ink 30) against the background of a second color (the color of the second ink 34 ).

Since the invention is explained below using the example of Moirέ magnification arrangements, which have microstructures of a plurality of micro-motif elements and microlenses, the operation of such Moire magnification arrangements will first be described with reference to FIG briefly described. The explanation of simple moiré magnification arrangements is not intended to be limiting to this type of microoptic magnification arrangements. Rather, it should be understood that the invention can be advantageously used for other micro-optical magnification arrangements, in particular for the general modulo magnification arrangements, as described in the applications PCT / EP2008 / 005171 and PCT / EP2008 / 005172.

4 schematically shows the layer structure of a moiré magnification arrangement 40 in cross section, wherein only the parts of the layer structure required for explaining the functional principle are shown. The Moirέ magnification 40 includes a carrier 42 in the form of a transparent plastic film, in the embodiment of an approximately 20 micron thick polyethylene terephthalate (PET) film. The upper side of the carrier foil 42 is provided with a grid-like arrangement of microlenses 44 which form on the surface of the carrier foil a two-dimensional Bravais grid with a preselected symmetry. The Bravais lattice may, for example, have a hexagonal lattice symmetry, but because of the higher security against forgery, preferred are lower symmetries and thus more general shapes, in particular the symmetry of a parallelogram lattice.

The spacing of adjacent microlenses 44 is preferably chosen as small as possible in order to ensure the highest possible area coverage and thus a high-contrast representation. The spherically or aspherically configured microlenses 44 preferably have a diameter between 3 .mu.m and 50 .mu.m and in particular a diameter between only 10 .mu.m and 35 .mu.m and are therefore not visible to the naked eye. On the underside of the carrier foil 42, a motif layer 46 is arranged, which contains a likewise grid-shaped arrangement of identical micromotif elements 48. The arrangement of the micromotif elements 48 forms a two-dimensional Bravais lattice with a preselected symmetry, again assuming a parallelogram lattice for illustration. As indicated in FIG. 4 by the offset of the micromotif elements 48 relative to the microlenses 44, the Bravais grid of the micromotif elements 48 differs slightly in its symmetry and / or in the size of its lattice parameters from the Bravais lattice of the microlenses 44 to a desired one Moire magnification effect. The grating period and the diameter of the micromotif elements 48 are of the same order of magnitude as those of the microlenses 44, that is to say preferably in the range of 3 μm to 50 μm and in particular in the range of 10 μm to 35 μm, so that the micromotif elements 48 themselves are visible to the naked eye are not recognizable.

The optical thickness of the carrier film 42 and the focal length of the microlenses 44 are matched to one another such that the micromotif elements 48 are located approximately at the distance of the lens focal length. The carrier film 40 thus forms an optical spacer layer which ensures a desired constant spacing of the microlenses 44 and the micromotif elements 48. Due to the slightly differing lattice parameters, the observer sees a slightly different subarea of the micromotif elements 48 when viewed from above through the microlenses 44, so that the multiplicity of microlenses 44 overall produces an enlarged image of the micromotif elements 48. The resulting moire magnification depends on the relative difference of the lattice parameters of the Bravais lattice used. If, for example, the grating periods of two hexagonal gratings differ by 1%, the result is a 100-fold moire magnification. For a more detailed description of the mode of operation and for advantageous arrangements of the micromotif elements and the microlenses, reference is made to the publications DE 10 2005 062 132 A1 and WO 2007/076952 A2, the disclosure content of which is incorporated in the present application in this respect.

In order to be able to produce such a moiré magnification arrangement with different-colored micromotif elements in the required fineness, the method according to the invention can be combined with a conventional macroscopic structuring, for example by means of a printing form. With reference to FIG. 5, an embossed structure 50 applied to a carrier foil, by virtue of its microstructuring, specifies which of the micrometer-sized subregions 52 are to be provided with ink and thus form the micromotif elements of a moiré magnification arrangement, and which subareas 54 are not to be printed.

According to the method described in connection with FIG. 2 (a), the embossing structure 50 has elevations 56 which are formed in the shape and arrangement of the desired micromotif elements. Embossing structures can also be produced without problems even in the high resolution required for the micromotif elements. By transferring a high-viscosity printing ink 60 to the embossing structure 50, substantially only the elevations 56, but not the depressions 58, are selectively colored, so that the high resolution of the embossing is transferred into a high-resolution print image.

This high-resolution structure 52, 54 through the embossed structure 50 can now be combined with a low-resolution structure 62, 64, 66, which is given for example by a printing forme, to a to produce multicolor moire magnification arrangement. For this purpose, highly viscous printing inks 60 of different colors are transferred to the elevations 56 in comparison with the micromotiv sections 52, 54, substantially more extensive macroscopic areas 62, 64, 66. With a corresponding design, the illustrated moire-magnified motif can then move from one color area to the next color area when the finished moire enlargement arrangement is tilted.

Since an exact juxtaposition of colors is often difficult, designs are advantageously used in which between two desired color areas 62, 66, a mixed color area 64 is provided. For example, an intermediate region 64 printed with green printing ink can be provided between a motif region 62 printed with blue printing ink and a motif region 66 printed with yellow printing ink. Such a procedure offers in particular at low opaque colors. For strongly opaque colors, the smallest color range can be printed first, then the next larger one, until finally a full surface is applied. Of course, the order of the print layers reverses when the moire magnification array lens array is not intended to be on the opposite side of the substrate as shown in Figure 4, but is also applied to the printing side.

When printing a plurality of at least partially opaque color layers, a multicolour of the moiré magnification arrangement results which, when viewed from above or from below, respectively conveys a different color impression. This different color impression can be made more visible by applying lens arrays on both sides of the arrangement. Instead of two colors, a combination of a color and a metal layer can also be used. Also, a combination of two colors and an intermediate metal layer comes into consideration, as shown in more detail below. The metal layer can also be produced by oblique vapor deposition of the relief structure, so that a demetallization for exposing the depressions can be dispensed with if the vapor deposition angle is suitably matched. If, for example, no suitable offset ink with resist properties is available, the desired effect can also be obtained by suitable oblique evaporation of the relief structure without demetallization.

In the exemplary embodiments described below, the elevations and depressions of the microstructures are always shown as rectangular structures for the sake of clarity. However, it is understood that the peaks and valleys can always be rounded, provided with continuous transitions and / or with additional structures, as explained above. Also, only the embossed structure and the layers necessary for explanation are shown and other elements of the structure, such as carrier foils, adhesive and protective layers or the moire magnification array lens arrays, are omitted. Also, all heightening / recess structures can be filled, for example, with a clearcoat to protect the printed elevations and depressions against unwanted filling with dirt and against manipulation or impressions.

6 shows an exemplary embodiment in which a colored microstructure, for example a colored moire magnification arrangement, matched with a metallization is combined. In order to achieve this registration, an embossed structure 70 with elevations 72 and depressions 74 is first of all produced. which forms the structural elements of the desired microstructure. The embossed structure 70 is then provided over its entire surface with a metallization 76, as shown in Fig. 6 (a). Then, a colored, highly viscous resist 78 is applied to the metallization 76, selectively covering substantially only the protrusions 72 of the embossment pattern 70 in the manner described above, as shown in FIG. 6 (b). Subsequently, the embossed, metallized and provided with resist coating structure is demetallized in a known per se, for example by means of an alkali. In this case, as illustrated in FIG. 6 (c), the metallization 76 is retained on the elevations 72 protected by the resist 78, while the metallization 76 in the depressions 74 is removed.

This creates a microstructure that can be viewed from both sides with a perfectly adjusted visual appearance. Viewing 80 from above, the microstructure with the color impression of the resist 78, when viewed 82, appears from below with the metallic luster of the metal layer 76. If the elevations and depressions form the micromotif elements of a moiré magnification arrangement, then the microstructure can in each case a lens array may be applied, through which the colored (viewing direction 80) or metallic (viewing direction 82) micromotif elements become moire-magnified visible. The demetallized areas of the recesses 74 represent congruent recesses in both appearances, which may be in the form of a negative writing or in the form of any other patterns, characters or codes.

If desired, the resist 78 may also be removed after demetallization. The microstructure then appears from both sides with the metallic impression of the metallization 76 and with perfectly fitted recesses 74. In this or also other embodiments, If larger contiguous demetallization surfaces are provided in the microstructure, a soluble wash ink in the form of the desired demetalization region is preferably applied to the embossed structure before the metallization, and the wash ink is washed off with a solvent prior to transferring the resist together with the metallization.

By suitable design of the embossed structure, the microstructure formed by the elevations and depressions can be combined with a further microoptical structure. For example, a moiré magnification arrangement can be combined with a hologram, as will now be explained with reference to the embodiment of FIG.

FIG. 7 shows an embossed structure 90 with elevations 92 and depressions 94, which in their shape and arrangement form the micromotif elements of a moire magnification arrangement. In addition, the surfaces of the protrusions 92 are provided with diffractive microrelief structures 96 carrying a desired holographic information. By contrast, the depressions 94 of the embossed structure do not contain any optically relevant information.

The embossed structure 90 is initially provided over the entire surface with a metallization 98, as shown in Fig. 7 (a). Then, a highly viscous resist 100 is applied to the metallization 98, selectively covering substantially only the protrusions 92 of the embossment pattern 90 in the manner described, as shown in FIG. 7 (b). Subsequently, the embossed, metallized and provided with resist coating structure is demetallisiert and the resist 100 is removed. As a result, as shown in Fig. 7 (c), the metallization 98 remains on the protrusions 92 provided with the microrelief structures 96, while the depressions 94 are demetallized. By this procedure, on the one hand, a moiré magnification arrangement with a metallic appearance is created, of which micromotif elements are formed by the shape and arrangement of the depressions 92 and elevations 94. In addition, the assembly includes a hologram encoded only in the raised regions 96 of the embossment pattern 90. However, since the dimensions of the protrusions 92 and depressions 94 are below the resolution limit of the human eye, it is not apparent to the viewer that the holographic information 96 is present only on the elevations 92, so that the holographic image is perceived by the viewer as a full-surface image.

In an alternative variant of the method, a highly viscous resist 100 of a desired color is applied to the embossed structure, and after removal of the resist 100, the demetallization is dispensed with, so that the embossed structure shown in FIG. 7 (d) is formed. If the resist layer 100 is designed to be opaque, a colored moire magnification arrangement can be seen from above in this embodiment when viewed 102 from above, and the hologram of the microrelief structures 96 can be seen from below when viewed 104.

If the resist layer 100 is translucent or after the removal of the resist, as in Fig. 7 (c), a translucent, highly viscous ink layer printed on the elevations 92, so when viewed 102 from above next to the colored Moire magnification arrangement and the translucent Hologram of microrelief structures 96 recognizable.

With reference to FIG. 8, a clearly two-color microstructure can be produced, for example, by firstly applying a first high-viscosity printing ink 110 selectively to the elevations 72 of a stamping layer 70, the printed stamping layer having a full surface area. metallization 112 is provided, and then a colored, highly viscous resist coating 114 is selectively applied to the protrusions 72 of the metallized embossing layer. After demetallization, the microstructure shown in FIG. 8 results, which when viewed 116 appears from above with the color impression of the colored resist 114 and which, when viewed 118, appears from below with the color impression of the first printing ink 110. The depressions 74 form congruent recesses from both viewing directions. If desired, one or both color layers 110, 114 may be translucent such that the metallization 112 remains visible through the color layers. In this case, the protrusions 72 may also be provided with diffractive microrelief structures, as described in connection with FIG. 7, to provide a combination of the bichromal microstructure with a hologram or other micro-optic structure.

With an alternative production variant, such a clearly two-color microstructure can also be produced without demetallization step. For this purpose, the printed embossing layer 70, 110 is metallized at an oblique angle with metal, so that the metallization 112 is present only on the elevations 72 and one flank side of the elevations 72. The depressions 74 are shaded by the elevations 72 at a suitably selected evaporation angle, so that no metal deposits there. Subsequently, a further colored lacquer 114 is selectively applied to the elevations 72, so that the desired color impression is produced without demetallization.

9 shows, as a further embodiment of the invention, a security element 120 with two different, viewed from opposite sides. ble hologramines having a common, perfectly matched negative pattern, such as a negative font.

To produce such a security element 120, an embossed structure with elevations 122 and depressions 124 in the form of a desired microstructure is first of all produced. The surfaces of the elevations 122 are provided with diffractive microrelief structures 126, which carry the holographic information of the second, later visible from below 140 hologram. The recesses 124 contain no optically relevant information, but instead represent the later negative writing areas.

The embossed structure is then provided over the entire surface with a metallization 128, as shown in Fig. 9 (a). On the metallization 128, a highly viscous thermoplastic resist coating 130 is applied, which selectively covers essentially only the elevations 122 of the embossed structure in the described manner. The thermoplastic resist 130 is provided with an embossing in the form of diffractive microrelief structures 132 which carry the holographic information of the first hologram, visible later from above 138, as shown in FIG. 9 (b).

The structure thus obtained is again provided with a full-surface metallization 134, as shown in Fig. 9 (c), and the protrusions 122 of the embossment pattern are again coated with a high-viscosity resist 136 as shown in Fig. 9 (d). By a demetallization step, both metallizations 128, 134 are then removed in the region of the depressions 124. Subsequently, the resist paint 136 is removed from the protrusions 122 to obtain the double-sided hologram structure shown in FIG. 9 (e). Viewing 138 of the microstructure from above, the first hologram formed by the diffractive microrelief structures 132 is visible, as viewed 140 from below, the second hologram formed by the diffractive microrelief structures 126. Both holograms contain a common, congruent negative information, which is formed by the recesses 124. If desired, another high viscosity ink may be transferred to the bumps 122 to make the first hologram appear colored from the top when viewed 138.

Instead of embossing a thermoplastic resist 130, as described in FIG. 9 (b), after the application of a resist 130, a first demetallization step may also take place, which removes the metallization 128 in the region of the depressions 124. Then, a thin, full-surface embossing lacquer layer is applied, which follows the arrangement of the elevations 122 and recesses 124. This embossing lacquer layer is then provided with diffractive microrelief structures 132, which carry the holographic information of the first, later visible from above hologram. This is followed by a renewed full-surface metallization 134, application of a high-viscosity resist coating 136 to the elevations 122 and renewed demetallization. In this procedure as well, a security element is created which has two holograms, each visible from opposite sides, with congruent negative information in the area of the recesses 134, whereby, however, an additional demetallization step is required compared to the method of FIG.

Instead of a printing ink or a resist varnish, other imprint materials, for example an adhesive, can also be selectively transferred to the elevations or into the depressions of a microstructure without leveling the predetermined microstructures. With reference to FIG. 10, for example, the microlenses 44 of a lens array for a moire magnification arrangement 40 can be provided with an adhesive layer 150 in the manner described. The heat-sealable lacquer to be transferred must be adjusted to high viscosity and block-free at room temperature. The heat sealing lacquer may be, for example, in addition to conventional systems based on water, for example, a water-activatable adhesive system which is activated by the moisture in the paper machine.

By virtue of this measure, for example, a security thread with a Moire enlargement arrangement embedded in a paper substrate can be connected to the paper not only on the side of the motif layer, but also on the side of the lens array via an adhesive layer. In conventional designs, however, the side of the microlenses always remains open, resulting in a weaker anchorage of the security thread. It is understood that the additional adhesive layer 150 with its refractive index can already be suitably taken into account when designing the geometry and refractive index of the microlenses 44. Of course, adhesive material can also be selectively applied to the raised areas of an embossed pattern on the motif side of a moire magnification arrangement 40.

11 illustrates another way of embedding a security thread, in particular a window security thread 180, with a micro-optical magnification arrangement in paper 182. A disadvantage of conventional safety threads with micro-optical magnification arrangements is a poor embedding in the paper. For a good embedding, it is desirable to provide the security threads both on their top and bottom with an adhesive that will ensure that the security thread is well adhered to the paper. This is especially true at Window security threads of importance, since in these the paper 182 in the form of window bars 183 rests on the security thread. These window webs 183 have a length of a few millimeters up to about 20 mm.

If the top side of a security thread is not coated with adhesive, the paper web rests on the security thread without an adhesive bond. Between the top of the thread and the paper web, a gap can form in circulation which can lead to the paper web being torn or torn off and thus to highly visible and undesired changes in the embedding value document. In the case of banknotes, such non-glued-in security threads also tend to tear the paper in the area of the security thread so that the security thread actually embedded there is visible at the margin of the note.

In the previously known security threads with micro-optical magnification arrangements, the upper side of the thread can not now be coated with adhesive, since the adhesive would level the topography of the lens grid and would destroy the focusing effect of the lenses due to the similar refractive indices of adhesive and lens material.

According to the invention, however, in a micro-optical magnification arrangement 40 with microlenses 44, highly viscous adhesive 184 can be applied selectively only to the upper regions of the microlenses 44 and then a laminating film 186 can be laminated onto the microlens array 44. For embedding in paper 182, 183, both the lower side of the thread and the upper side of the thread can be provided with an adhesive layer 188, as shown in FIG. 11. Since the adhesive 184 covers only the uppermost region of the microlenses 44, a multiplicity of microcavities 185 arise between the laminating film 186 and the microlens array 44, apart from the adhesive regions. The microcavities 185 are filled with air (n = 1) and therefore have a large width. index difference to the material of the microlenses (n "1.5), so that the focusing effect of the microlenses 44 is substantially retained despite the lamination of the foil 186. In the uppermost regions of the microlenses 44, in which the laminating film 186 is connected to the lenses via the adhesive 184, the beam path through the lens is anyway substantially perpendicular when viewed, so that the optical effect of the lenses is there by the adhesive 184 is practically unaffected. This applies in particular to lenses in the form of spherical caps as well as for lenticular lenses.

The principle illustrated in FIG. 11 can be used not only for the micro-lenses of micro-optical magnification arrangements, but advantageously also for unmetallized, optically variable microstructures. While the optically variable effect of metallized microstructures is generally only slightly influenced by covering with lacquers or lamination with a foil, an optically variable effect of unmetallised microstructures is generally lost by coating with lacquer or bonding with a foil. This is mainly due to the fact that the refractive indices of typical microstructure materials, for example an embossing lacquer layer, and typical adhesives are almost always close to each other. The surrounding adhesive then prevents effective light deflection through the microstructures and thus the desired refractive or optically variable effect. Referring to Figure 12, a window security thread 190 has a backing 192 and a non-metallized relief structure 194 forming an optically variable microstructure. FIG. 12 shows the relief structure for illustration in the form of a blazed grating 194, but the invention is also applicable to any other unmetallized relief structures. On the elevations of the relief structure 194, here the top of the Blazegitter- elements, a highly viscous adhesive 196 is selectively applied in the manner described above. Then, as already described in connection with FIG. 11, a laminating film 186 is laminated onto the optically variable microstructure 194 and the security thread 190 is reliably embedded in the paper 182, 183 via adhesive layers 188 applied on the top and bottom side.

Since the adhesive 196 covers only the uppermost portion of the blazed grating elements 194, a plurality of air-filled microcavities 195 are formed between the laminating film 186 and the optically variable microstructure. The blazed grating elements are therefore in an air environment with a large difference in refractive index, so that their optically variable effect is substantially retained despite the lamination of the film 186.

In a modification of the designs of FIGS. 11 and 12, the microstructure is designed specifically with regard to the subsequent lamination of a foil. For this purpose, the microstructure contains, in addition to the user surveys or utility depressions which produce the desired optical effect, also support surveys without an optical effect, which merely serve for bonding to the laminating film. By way of illustration, FIG. 13 shows a window security thread 200 with a micro-optical magnification arrangement 202 which, except for the support embossments additionally provided in the plane of the lens array. gene 204 of the micro-optical magnification arrangement 40 of FIG. 11 corresponds.

In the embossing of the microlenses 44, in addition to the optically active microlenses 44, regularly arranged support columns 204 are embossed into the embossing lacquer layer, which themselves have no optical effect but which project beyond the microlenses 44 to such an extent that during the transfer of the adhesive 206 to the embossed structure 44, 204 only the support columns 204, but not the microlenses 44 come into contact with the adhesive 206. The microlenses 44 remain therefore even after the bonding of the embossed structure 44, 204 with the laminating film 186 completely in air environment 208 and receive their optical effect undisturbed.

Of course, this variant of the invention can be used not only in microoptical magnification arrangements, but generally in optically variable microstructures. Particularly good results are achieved with optically variable embossed structures whose optically effective embossed structure elements (user surveys) are not too high. Preferably, the user surveys are not higher than 10 μm, more preferably not higher than 5 μm.

By way of example, the embossed structure may comprise optically active elements (user elevations) as diffractive optical elements which, when irradiated with a laser beam, project a predetermined image onto a screen. The structures of the diffractive optical elements typically have lateral dimensions of 0.5 μm to 30 μm and a height of barely more than 1 μm. Without support projections according to the invention, these embossed structure elements are too thin for covering with a film because the required adhesive penetrates into the intermediate spaces of the embossed structure elements run and destroy their visual impact. In contrast, can be generated by providing additional support surveys controlled a desired air-filled distance between the user surveys and the laminating film.

The shape and area coverage of the support surveys can vary widely. The support surveys may be formed, for example in the form of columns or webs in a regular or irregular arrangement.

A further possibility to specifically form the microstructure with regard to the subsequent lamination of a film is to provide the microstructure elements in their uppermost regions with small recesses intended to receive adhesive droplets. The recesses are in particular designed so that the complete form of the microstructure elements is restored by the transfer of small adhesive droplets. For example, 11 may be provided in the uppermost areas of the microlenses 44 of FIG. Small denting, which are supplemented by receiving adhesive droplets to the full lens shape.

Although not part of the present invention, it is basically also possible to modify the designs of FIGS. 11 to 13 by not providing the uppermost region of the relief structure with adhesive, but rather by very thinly coating the laminating film with adhesive and by using the microstructure such a prepared laminating film is coated. The adhesive layer must be so thin or must be so little melted or deformed that they only the top areas of the Microstructure evidenced, so that between the laminating film and the microstructure air-filled microcavities arise.

The transfer of an adhesive to the elevations of an embossed structure, for example, also allows the addition of additional holographic structures, as explained with reference to the embodiment of FIG. 14. 14 shows an embossing structure 160 with elevations 162 and depressions 164, which form a desired microstructure in their shape and arrangement. As in the exemplary embodiment of FIGS. 7 and 9, the surfaces of the elevations 162 are provided with diffractive microrelief structures 166 which carry desired holographic information, while the depressions 164 contain no optically relevant information. As already described above, the protrusions 162 of the embossing structure 160 were selectively provided with a metallization 168 as shown in Fig. 14 (a).

In order to apply additional holographic structures, a highly viscous pressure-sensitive adhesive 170 is selectively transferred to the elevations 162. The embossed structure 160 prepared in this way is then brought into contact with a further film 172, which carries a metallized, continuous and releasably formed hologram 174. By appropriate adjustment of temperature and pressure, the holographic structures 174 of the film 170 are selectively transferred to the adhesive-bearing elevations 162 of the embossing structure 160. Also in this way, a security element can be created with two holograms visible from opposite sides, which have a common, perfectly matched negative pattern 164. If desired, another high viscosity ink may be transferred to the bumps 162 to make the hologram 174 appear colored when viewed from above. Further possibilities for providing the microstructure with additional optical effects will now be illustrated with reference to FIGS. 15 and 16 using the example of motif images of microoptical magnification arrangements. Conventional micro-optical magnification arrangements often have the disadvantage that they are without an optical effect from the rear or that the application of, for example, a mirrored rear hologram clearly affects and disturbs the front view.

FIG. 15 (a) shows an embossing structure 212 with elevations 214 and depressions 216 present on a first carrier foil 210, which form in their shape and arrangement the motif image of a microoptical magnification arrangement. The surface of the protuberances may be left transparent or selectively coated with a paint 218 in the manner described above. On the side of the carrier foil 210 opposite the embossing structure 212, a microlens grid (not shown) is applied in a known manner during the further course of the production process for viewing the motif image formed by the embossing structure 212.

On a second carrier foil 220, an embossing lacquer layer 222 poorly anchored on the foil 220 is applied, provided with a desired hologram embossing 224, metallized 226 and possibly demetallised in some areas (not shown). Then, the metallized hologram foil 220-226 is provided with a thin adhesive coating 228, brought into contact with the first carrier foil 210 under pressure, and then separated again. The profile depths of the embossed structure 212 and the layer thickness of the adhesive coating 228 are matched to one another such that the contact only exists with the elevations 214 of the embossed structure 212. When the films 210, 220 are separated, the second carrier film 220 in the raised contact regions 214 is detached from the embossing lacquer layer 222 due to the poor anchoring, while no transfer takes place in the region of the depressions 216. The hologram 224 of the second carrier film 220 is thereby selectively transferred only to the protrusions 214 of the embossing pattern 212, as shown in Fig. 15 (b).

When viewed from the rear side R of the finished security element, the metallized embossed areas complement each other to the hologram 224 generated on the second carrier film 220. Nevertheless, the security element is still highly translucent, because with the depressions 216, large portions of the first film 210 are not covered with opaque metal are coated. When viewing from the front side V of the finished security element, the moire or modulo magnification effect of the micro-optical magnification arrangement can therefore be seen undisturbed. If the microstructures are colored 218, the metallization 226 even enhances the color effect. The holographic metallized backside image is practically invisible when viewed from the front side V, since the hologram reconstructed on the backside is strongly disturbed on the front side by the lenticular grid, which is not shown in the figure.

On the second carrier foil 220, instead of a metallized hologram, a removable color-shifting element can also be applied. The color-shifting element can be formed, for example, by a color-shifting thin-film element of absorber, dielectric and reflector. In order to produce an identical or different color-shift effect on both sides of the finished security element, it is also possible to use a double-sided thin-layer element with the layer sequence absorber, dielectric, reflector, dielectric 2, absorber 2. The color-shifting element can also be formed by a pigmented tilting ink, which is detachably applied to the carrier film 220. In further design variants, the color-shifting element contains one or more liquid crystal layers. For example, a cholesteric liquid crystal layer and, moreover, an absorbent color layer can be applied detachably to the carrier film 220. In order to produce a color shift effect on both sides of the security element, a further cholesteric liquid crystal layer can be provided over the absorbing color layer.

After the contacting and detachment of the second carrier film 220, the color-tilting element also remains only in the region of the elevations 214 on the embossing structure 212 and is thereby selectively transferred thereto. The finished security element has a color shift effect from the rear, which does not disturb the visual effect visible from the front and does not severely impair the transparency of the security element. By using double-sided color-shifting elements, a color-shift effect can also be generated on the front without greatly impairing the transparency of the security element.

The designs described are particularly suitable for micro-optical magnification arrangements which are used to cover viewing areas of works documents. Micro-optical magnification arrangements show a good optical effect both in reflected light and in transmitted light and are therefore well suited for applications with valuable documents with see-through windows. As a result of the backside effects described, these microoptical magnification arrangements are further upgraded without disturbing the front moire or general modulo effect. Fig. 16 illustrates another way to create a security element having two different holograms visible from opposite sides with a common negative pattern.

With reference to FIG. 16 (a), an embossing lacquer layer 232 is applied to a first carrier foil 230 and provided with a first hologram embossing 234. After a full-surface metallization 236, a structured resist layer 238 is produced in a manner known per se, the recesses of which show the desired common negative pattern. After demetallization of the unprotected metal areas, the appearance of the first carrier foil 230 shown in FIG. 16 (a) results. The structured resist layer 238 represents a relief structure with elevations 240 and depressions 242 in the sense of the present invention.

Furthermore, a poorly anchored embossing lacquer layer 252 is applied to a second carrier foil 250, provided with a desired second hologram embossing 254, metallized 256 and optionally partially demetallised (not shown). The metallized second hologram foil 250 is provided with a thin adhesive coating 258, brought into contact with the first hologram foil 230 under pressure and, if appropriate, the action of temperature, and separated again. The profile depths of the resist coating layer 238 and the layer thickness of the adhesive coating 258 are matched to one another such that the contact only exists with the elevations 240 of the resist coating layer 238.

When separating the hologram films 230, 250, the second hologram foil 250 in the raised contact regions 240 is detached from the embossing lacquer layer 252 due to the poor anchoring, while no transfer takes place in the region of the depressions 242. The second Hoio As a result, the gram is selectively transmitted only to the elevations 240 of the resist layer 238, as shown in FIG. 16 (b). The recesses 242 form a common, perfectly matched negative pattern for the two holograms 236 and 256 visible from opposite sides.

In order to produce micro-optical magnification arrangements with colored metallic microstructures, it is also possible to use the selective transfer of an imprint material into the depressions of an embossed structure. Referring to FIG. 17, an embossing structure 260 includes protrusions 262 and depressions 264 having a shape and arrangement given by the desired motif image. The embossing structure 260 is provided over its entire area with a metallization 266, for example of aluminum, as shown in FIG. 17 (a).

Then, in the manner described above, a colored resist 268 is selectively introduced into the recesses 264 of the embossing pattern 260, as shown in Fig. 17 (b). Subsequently, the metallized 266 and provided with resist 268 embossed structure is demetallized, for example by a caustic. As shown in FIG. 17 (c), the metallization 266 is retained in the recesses 264 protected by the colored resist 268 while being removed from the surface of the protrusions 262.

These measures result in a micro-optical magnification arrangement, in which the colored microstructures are lined with metal. The reflecting metal leads to a significantly increased luminosity of the colored microstructures and thus improves the recognizability of the colored, moiré-enlarged target images. In addition, it results as an additional optical effect that the moirέ-magnified target image for the viewer in transmitted light with colorless, black structures appears in appearance. The finished security element thus shows a striking reflected light / transmitted light contrast, in which the same target image appears once with bright colors (incident light) and once as a high-contrast black and white image (transmitted light).

In one embodiment, such little colored resist 268 is filled in the recesses 264 that it is distributed around the bumps only in the corner and edge areas. The metallization covers the depressions 264 thus not the entire surface but only at the edges of the surveys. In the subsequent etching process not only the metallization is removed on the surveys but also in the uncovered areas in the wells. In this way you get a kind of outline metallization that surrounds the surveys.

Optionally, the background can be colored in an additional color, for example by using a colored embossing lacquer, a colored or colored printed carrier foil, colored microlenses or a further color coat applied after the etching process. Instead of in the recesses, the colored resist can also be selectively transferred only to the elevations of the embossed structure, as already explained in connection with FIG. 6.

With reference to Fig. 18, metallized microstructures may also be formed with the aid of an adhesive paint transferred into the recesses. FIG. 18 (a) shows an embossed structure 270 with elevations 272 and depressions 274 with a shape and arrangement given by the desired microoptical motif image. The embossing lacquer 270 may be colored or colorless. Then, in the manner described above, a colored or colorless adhesive lacquer 276 is selectively introduced into the recesses 274 of the embossing pattern 270. As also shown in FIG. 18 (a), a metal layer 282, whose adhesion to the carrier film 280 is weaker than the adhesion to the adhesive lacquer 276 of the embossed structure 270, is prepared on a further carrier film 280 over the entire area or regions. This can be ensured, for example, by the coordination of the materials of the metal layer 282 and the carrier film 280, by a pretreatment of the carrier film 280 or by the use of special release layers between metal layer 282 and carrier film 280.

The carrier film 280 is then brought into contact with the filled embossed structure 270 without wrinkles under pressure and, if appropriate, temperature, and then separated again. Since the adhesion between the metal layer 282 and the adhesive resist 276 exceeds the adhesion between the metal layer 282 and the support film 280, the metal layer in the filled recess portions 274 is selectively transferred to the embossed structure 270, as shown in Fig. 18 (b). In the raised areas 272 of the embossed structure 270, no transmission takes place. In this way, metallized microimages or, if the adhesive coating 276 is colored, metallized, colored microimages are produced on embossed structure 270.

In an alternative process guide, which is illustrated in FIG. 18 (c), after the transfer of the colored or colorless, adhesive varnish 276, the embossed structure is first vapor-deposited over the whole area with a metal layer 282. In addition, an adhesive layer 292 is applied to a carrier film 290 over the whole area or regions, the adhesive effect of which is lower than the adhesive effect of the coating 276 introduced into the recesses 274. This support film 290 is then brought wrinkle-free under pressure and optionally temperature action with the filled and metallized embossed structure 270 in contact and then separated again. At the given relative adhesive strengths, the metal layer 282 remains in the filled recessed areas 274 on the imprinting structure 270, while in the raised areas 272 it is peeled off by the adhesive layer 292. As a result, the configuration shown in Fig. 18 (b) again arises.

In further variants, the embossed structure 270 shown in FIG. 18 (a) can be dusted after the transfer of the adhesive varnish 276 with effect pigments, metal pigments or other optically active particles, wherein the particles only adhere in the regions 274 of the adhesive varnish 276 , Alternatively, it is also possible to apply a color with particles which, after drying the paint, are present without stopping in the binder matrix. Of the non-adhesive regions 272, the particles are washed away or blown off in a further step.

In an alternative embodiment to the designs of FIG. 18, the adhesive lacquer 276 may also be selectively transferred to the protrusions of the embossed structure instead of into the depressions. Analogous to the procedure in the designs of Figures 18 (a) and 18 (c), metal is selectively transferred only to the bumps.

19 shows the use of a microstructure according to the invention for producing a high-resolution printed layer on a target substrate 310. As illustrated in FIG. 19 (a), a microstructure 300 with elevations 302 and depressions 304 is initially produced in the manner described above a desired imprint material 306 is selectively transferred essentially only to the elevations 302 of the relief structure. Because of the high achievable resolution, the protrusions 302 and depressions 304 are preferably generated by an embossing process. The imprint material 306 may in particular be a printing ink. Then, the microstructure 300 is brought into contact with the target substrate 310, optionally under pressure and / or temperature. The imprint material 306 present on the elevations 302 of the relief structure is thereby transferred to the target substrate 310 with the high resolution predetermined by the microstructure 300, as shown in FIG. 19 (b). The target substrate 310 may be appropriately pretreated for this purpose.

Claims

Patent claims

1. A method for producing a microstructure on a support in which

a carrier is provided with a relief structure having elevations and depressions and in which the elevations and / or depressions are arranged in the form of a desired microstructure, and

is transferred with a printing tool, an imprint material on the relief structure, wherein the viscosity of the imprint material is selected so that the imprinting substance selectively either substantially only on the elevations or substantially only in the wells of the

Relief structure is transferred.

2. The method according to claim 1, characterized in that with the printing tool, a highly viscous imprinting substance is selectively transmitted substantially only on the elevations of the relief structure.

3. The method according to claim 2, characterized in that the high-viscosity printing material is transferred in a layer thickness which is smaller than the structural depth of the relief structures.

4. The method according to claim 3, characterized in that the layer thickness of the imprint material is less than 50%, preferably less than 30%, particularly preferably less than 15% of the structural depth of the relief structures.

5. The method according to at least one of claims 2 to 4, characterized in that a desired size and / or depth of transfer areas is specified, in which the imprint material is to be transferred to the elevations of the relief structure, and that the hardness of the pressure tool and the pressure when transferring the imprint material can be selected according to the desired size and / or depth of the transfer areas.

6. The method according to at least one of claims 2 to 5, character- ized in that the pressure during the transfer of the imprint material is chosen so low that the imprint material is not squeezed.

7. The method according to at least one of claims 2 to 6, characterized in that the imprint material is transferred substantially without pressure on the relief structure, wherein a predetermined distance between the printing unit and relief structure is filled by the imprint material.

8. The method according to at least one of claims 2 to 7, characterized in that an imprint material having a viscosity between about 10 mPa * s and about 200 Pa * s, preferably between about 800 mPa * s and about 150 Pa * s selected at room temperature becomes.

9. The method according to at least one of claims 2 to 8, characterized in that the imprint material is transferred in the offset or flexographic printing process ren.

10. The method according to at least one of claims 2 to 9, characterized in that as printing material, a printing ink, in particular an offset printing ink is selected.

11. The method according to at least one of claims 2 to 10, characterized in that a radiation-curable, thermosetting or oxidatively drying printing ink is selected as the printing material.

12. The method according to at least one of claims 2 to 9, characterized in that as an imprinting material, an adhesive, in particular a highly viscous heat sealing lacquer and / or a water-activatable adhesive system is selected.

13. The method according to claim 12, characterized in that the relief structure is brought into contact after the transfer of the adhesive with a transfer medium, while a transfer material is transferred from the transfer medium to the adhesive provided with elevations of the relief structure.

14. The method according to claim 13, characterized in that as a transfer agent, a color, a colored film, an effect, effect pigments, colored pigments, black pigments, white pigments, dyes, effect layers, a metallization or subregions of a hologram or a hologram-like diffraction structure or an optical effective microstructure can be selected.

15. The method according to claim 12, characterized in that the relief structure is dusted after the transfer of the adhesive with a transfer substance.

16. The method according to claim 15, characterized in that a

Excess of the transfer material is removed after dusting, in particular by a non-contact method.

17. The method according to claim 12, characterized in that after the transfer of the adhesive, a laminating film is laminated to the relief structure.

18. The method according to claim 17, characterized in that the layer sequence with carrier, microstructure and Kaschierfolie is embedded as a security element in a security paper, document of value or the like, wherein the carrier and preferably also the laminating film are provided with an adhesive layer.

19. The method according to at least one of claims 2 to 9, characterized in that as an imprint material provided with an adhesive transfer substance is transferred to the elevations of the relief structure.

20. The method according to claim 19, characterized in that as transfer agent is a color, a colored film, an effect, effect pigments, colored pigments, black pigments, white pigments, dyes, effect layers, a metallization, a portion of a hologram or a hologram-like diffraction structure or an optically effective Microstructure, or a color-shifting element, in particular a color-shifting thin-film element or an element containing at least one liquid crystal layer is selected.

21. The method according to at least one of claims 2 to 20, characterized in that the printing material is an effect-pigmented printing material is selected, which preferably has luminescent pigments, thermochromic pigments, metal pigments and / or pearlescent pigments.

22. The method according to at least one of claims 2 to 21, characterized in that different high-viscosity printing materials, in particular different-colored or provided with different effect pigments imprint materials are transferred.

23. The method according to at least one of claims 2 to 22, characterized in that prior to the transfer of the desired imprint material to compensate for falling edges of the elevations of the relief structure, a highly viscous lacquer layer is transferred.

24. The method according to at least one of claims 2 to 23, characterized in that the elevations of the relief structure are formed with a sharply defined, high-standing edge region.

25. The method according to at least one of claims 2 to 24, characterized in that the elevations of the relief structure are provided with a micro-feed structure, in particular with a diffractive microrelief structure.

26. The method according to at least one of claims 2 to 25, characterized in that a highly viscous resist, in particular a colored, highly viscous resist is selected as the printing material.

27. The method according to claim 26, characterized in that the barrier structure is metallized before transferring the highly viscous resist.

28. The method according to claim 27, characterized in that the metallized relief structure is demetallized after transfer of the highly viscous resist in areas not protected by resist coating.

29. The method according to claim 28, characterized in that

the relief structure is provided with an embossing lacquer layer after the demetallizing step,

a microrelief structure, in particular a diffractive microrelief structure, is embossed into the embossing lacquer layer,

the relief structure is metallised again,

again highly viscous resist, in particular a colored, highly viscous resist is transferred, and

the re-metallized relief structure is demetallised again in areas not protected by resist coating.

30. The method according to claim 27, characterized in that

the resist is embossed with a microrelief structure, in particular a diffractive microrelief structure,

- the relief structure is metallized again,

again a highly viscous resist is transferred, and the re-metallized relief structure is demetallized in areas not protected by resist coating.

31. The method according to at least one of claims 1 to 30, characterized in that the relief structure is provided with spacing tracks for setting a defined distance and / or pressure during transfer of the imprint material.

32. The method according to at least one of claims 1 to 31, characterized in that the relief structure is provided with indicator traces, which are detected by metrology during the transfer of the printing material for controlling inking and / or printing.

33. The method according to at least one of claims 1 to 32, characterized in that the imprint material is provided with particles of defined size, which prevent a squeezing of the imprint material during transfer.

34. The method according to claim 1, characterized in that with the printing tool an imprint material, in particular a low-viscosity imprint material is selectively transmitted substantially only in the recesses of the relief structure.

35. The method according to claim 34, characterized in that in the selection of the low-viscosity printing material, the surface tension of the

Imprint material is matched to the surface energy of the relief structure.

36. The method according to claim 34 or 35, characterized in that an imprint material having a viscosity between about 3 mPa * s and about 1500 mPa * s at room temperature is selected.

37. The method according to at least one of claims 34 to 36, characterized in that as printing material, a printing ink, in particular a dye solution, a pigment dispersion or an ink is selected.

38. The method according to at least one of claims 34 to 37, characterized in that a liquid crystal solution, in particular a low-viscosity liquid crystal solution is selected as the printing material.

39. The method according to claim 38, characterized in that the depressions of the relief structure are formed with alignment structures for aligning liquid crystals.

40. The method according to at least one of claims 37 to 39, characterized in that first a low-viscosity printing ink or liquid crystal solution is transferred with a low binder content, which selectively flows into the recesses of the relief structure, and that then a solution is transferred with a high binder content, which fixes the printing ink or liquid crystal solution in the depressions of the relief structure.

41. The method according to at least one of claims 34 to 36, characterized in that a low-viscosity adhesive is selected as printing material.

42. The method according to at least one of claims 34 to 36, characterized in that a low-viscosity resist is selected as the printing material.

43. The method according to at least one of claims 34 to 42, characterized in that as an imprinting an effect-pigmented imprint material is selected, which preferably has luminescent pigments, thermochromic pigments, metal pigments and / or pearlescent pigments.

44. The method according to at least one of claims 34 to 43, characterized in that different low-viscosity printing materials, in particular different-colored or provided with different effect pigments imprint materials are transferred.

45. The method according to at least one of claims 34 to 44, characterized in that the imprint material is transferred in such a small amount that it flows in the transfer only in the elevations immediately surrounding edge regions of the wells.

46. The method according to claim 34, wherein before the transfer of the desired imprint material in a small amount, a low-viscosity clearcoat is applied, which fills the edge regions of the recesses immediately surrounding the elevations.

47. The method according to at least one of claims 34 to 46, characterized in that the recesses are formed with rounded transitions to the elevations.

48. The method according to at least one of claims 34 to 47, characterized in that the elevations of the relief structure are provided with a lotus structure to produce low wettable elevation surfaces.

49. The method according to claim 1, characterized in that in a first step, a first high-viscosity printing material is selectively transferred substantially only to the elevations of the relief structure, and in a second step, a second low-viscosity printing material selectively essentially only into the depressions of Relief structure is transferred.

50. The method according to at least one of claims 1 to 49, characterized in that the elevations and depressions of the microstructure microstructure elements are formed with a line thickness between about 1 micron and about 10 microns.

51. The method according to at least one of claims 1 to 50, characterized in that the elevations and depressions of the microstructure microstructure elements are formed with a pattern depth between about 0.5 microns and about 20 microns, preferably between about 1 micron and about 10 microns.

52. Method according to claim 1, characterized in that a motif image is applied as a microstructure, which is divided into a plurality of cells, in which respectively imaged regions of a predetermined target image are arranged, the lateral dimensions of the imaged regions preferably between about 5 microns and about 50 microns, in particular between about 10 microns and about 35 microns.

53. Method according to claim 52, characterized in that the opposite side of the carrier is provided with a viewing grid of a plurality of viewing grid elements for reconstruction of the predetermined target image when viewing the motif image using the viewing grid, wherein the lateral dimensions of the viewing grid elements preferably between about 5 microns and about 50 microns, in particular between about 10 microns and about 35 microns.

54. Method according to claim 1, characterized in that a motif image from a planar periodic or at least locally periodic arrangement of a multiplicity of micromotif elements or an arrangement of micromotile elements for a modulo magnification arrangement is applied as the microstructure.

55. The method according to claim 54, characterized in that the lateral dimensions of the micromotif elements are between about 3 μm and about 50 μm, preferably between about 10 μm and about 35 μm.

56. The method of claim 54 or 55, characterized in that the opposite side of the carrier with a planar periodic or at least locally periodic arrangement of a plurality of micro-kussierelementen for enlarged or moire-magnified viewing of the micromotif elements of the motif image is provided.

57. The method according to at least one of claims 1 to 56, characterized in that the carrier equipped with the applied microstructure with one or more functional layers for use as a security element for security papers, documents of value and the like is, in particular with layers with visually and / or machine-detectable security features.

58. The method according to at least one of claims 1 to 57, characterized in that the microstructure applied to the carrier is provided with a transparent topcoat.

59. The method according to at least one of claims 1 to 58, characterized in that the carrier is provided with an embossed structure with elevations and depressions, which forms the relief structure.

60. The method according to at least one of claims 1 to 58, characterized in that a resist coating structure with elevations and depressions is applied to the carrier, which forms the relief structure.

61. Apparatus for carrying out the method according to at least one of claims 1 to 60, with a printing tool for transferring an imprint material selectively either only on the elevations or only in the depressions of the relief structure.

62. Article, in particular data carrier or security element, with a microstructure produced according to one of claims 1 to 60.

63. The article of claim 62, characterized in that the microstructure is formed by microstructure elements with a line thickness between about 1 micron and about 10 microns.

64. The article of claim 62 or 63, characterized in that the microstructure by microstructure elements with a structure depth is formed between about 0.5 microns and about 20 microns, preferably between about 1 micron and about 10 microns.

65. An article according to at least one of claims 62 to 64, characterized in that the microstructure has two microrelief structures visible from opposite sides with a common, perfectly matched negative pattern.

66. The article according to at least one of claims 62 to 65, characterized in that the carrier is a transparent plastic film or a

Includes paper layer.

67. The article according to at least one of claims 62 to 66, characterized in that the carrier has a thickness between about 3 microns and about 50 microns, preferably between about 5 microns and about 25 microns.

68. An article according to at least one of claims 62 to 67, characterized in that the microstructure forms a motif image, which is divided into a plurality of cells, in each of which imaged areas of a predetermined target image are arranged, wherein the lateral dimensions of the imaged Preferably, ranges between about 5 microns and about 50 microns, in particular between about 10 microns and about 35 microns.

69. An article according to claim 68, characterized in that a viewing grid of a plurality of viewing grid elements for

Reconstruction of the predetermined target image is provided when viewing the motif image using the viewing grid, wherein the lateral dimensions of the viewing grid elements preferably between about 5 microns and about 50 microns, in particular between about 10 microns and about 35 microns.

70. An article according to at least one of claims 62 to 69, characterized in that the microstructure forms a motif image from a planar periodic or at least locally periodic arrangement of a plurality of micromotif elements or an array of micromotile elements for a modulo magnification arrangement whose lateral dimensions preferably between about 3 microns and about 50 microns, in particular between about 10 microns and about 35 microns.

71. An article according to claim 70, characterized in that a planar periodic or at least locally periodic arrangement of a plurality of Mikrofokussierelementen for enlarged or moire-magnified viewing of the micromotif elements of the motif image is provided, the lateral dimensions preferably between about 3 microns and about 50 microns, in particular between about 10 microns and about 35 microns.

72. An article according to claim 71, characterized in that the arrangement of micromotif elements and the arrangement of microfocusing elements at least locally each form a two-dimensional Bravais grid, wherein the arrangement of micromotif elements and / or the arrangement of Mikrofokussierelementen a Bravais grid with the symmetry of a Parallelogram grating forms.

73. An article according to at least one of claims 68 to 72, characterized in that the carrier forms an optical spacer layer for the motif image and the arrangement of viewing grid elements or microfocusing elements.

74. An article according to at least one of claims 62 to 73, characterized in that the object is a security element, in particular a security thread, a label or a transfer element.

75. An article according to at least one of claims 62 to 73, characterized in that the object is a data carrier, in particular a banknote, a document of value, a passport, an identity card or a document.

76. The article according to at least one of claims 62 to 75, characterized in that the article is provided with the applied microstructure with one or more functional layers, in particular with layers with visually and / or machine-detectable security features.

77. A microstructure producible according to the method of any of claims 1 to 60, having a relief structure with elevations and depressions, the shape and arrangement of which form the structural elements of the microstructure, and in which with a printing tool an imprinting substance selectively either substantially only on the elevations or is essentially transferred only in the wells of the relief structure.

78. A method for producing a high-resolution printing layer on a target substrate, characterized in that a microstructure is produced by a method according to one of claims 1 to 60, wherein the imprint material is selectively transmitted substantially only to the elevations of the relief structure, and that the thus produced microstructure is brought into contact with the target substrate and the imprint material present on the elevations of the relief structure is transferred to the target substrate.