CN115122801A

CN115122801A - Method for producing an optically variable security element

Info

Publication number: CN115122801A
Application number: CN202210236386.0A
Authority: CN
Inventors: W.霍夫米勒; T.萨特勒; A.劳赫
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient GmbH
Priority date: 2021-03-25
Filing date: 2022-03-11
Publication date: 2022-09-30
Also published as: EP4067103A1; DE102021001589A1; EP4067103B1

Abstract

The invention relates to a method for producing a security element for securing a valuable item, comprising a feature layer (24) having a first and a second feature region (30, 40), in which first and second feature regions a different first or second embossing lacquer layer is present. In the method, a hydrophilic layer of a first embossing lacquer (42) is applied to a carrier (90) in a first feature region (40), and the applied layer is embossed with embossing structures (44) producing a first optical effect and hardened. A different layer of a second embossing lacquer (32) is provided on the printing tool (94), and in the printing step the printing tool (94) is brought into contact with the carrier (90) and the second embossing lacquer (32) is thereby transferred.

Description

Method for producing an optically variable security element

Technical Field

The invention relates to a method for producing an optically variable security element for securing a valuable item, comprising a carrier and a feature layer having a first and a second feature region, in which first and second feature regions different first or second embossing lacquer layers are present.

Background

Data carriers, such as value or identification documents, and other valuable articles, such as branded goods, are often provided with security elements for providing security, which can verify the authenticity of the data carrier and at the same time serve as protection against unauthorized copying. The security element can be designed, for example, as a security thread embedded in a banknote, as a cover film for banknotes with holes, as an applied security strip, as a self-supporting transfer element or else as a feature region applied directly to the document of value.

Previously, optically variable security elements have been proposed which have two relief structures arranged in different height levels and each provided with a color coating, which are embossed in a matching pigmented embossing lacquer layer, see WO 2020/011390 a1, WO 2020/011391 a1 and WO 2020/011392 a 1. However, in this case, in order to observe the lower relief structure, the observer must generally observe through the embossing lacquer layer of the higher relief structure, so that there may be a greater limitation to the coloring of the embossing lacquer, in particular of the embossing lacquer layer of the higher embossing lacquer layer, depending on the desired visual impression.

If a plurality of printing inks or embossing lacquer layers are applied to the substrate in the production of such security elements, the unavoidable register fluctuations in the printing press prevent the layers from being precisely registered (Passerung) in the plane to less than about 50 μm. These register fluctuations can occur both longitudinally along the printed web and transversely to the printed web.

Disclosure of Invention

Starting from this, the object of the present invention is to provide a method by means of which optically variable security elements of the type according to the invention can be produced, which have a high degree of registration accuracy of the different first and second embossing lacquer layers.

The object is achieved according to the invention by a method for producing a security element for providing security to a valuable item.

In order to solve the technical problem, the invention provides a method for producing a security element which can be used, in particular, for providing security to a valuable item. The security element to be produced comprises a feature layer having a first and a second feature region, in which first and second feature regions a different first or second embossing lacquer layer is present.

In a first aspect of the invention, in the method, a hydrophilic layer of a first imprint lacquer is applied to a carrier in the first feature region, the applied layer is imprinted with an imprint structure that produces a first optical effect and hardened.

A different layer of a second embossing lacquer is further provided on the printing tool (Druckwerkzeug), and in the printing step the printing tool is brought into contact with the carrier and the second embossing lacquer is thereby transferred.

The carrier may be permanently retained in the security element or it may be a manufacturing carrier that is removed from the security element after the security element is transferred to the target substrate.

In the printing step, the second embossing lacquer is advantageously transferred only into the second feature regions which are not coated with the hydrophilic embossing lacquer.

The layer of the second, different embossing lacquer is advantageously provided on the printing tool over the entire surface or over the entire surface.

Preferably, the carrier is wetted with the first embossing lacquer layer before the printing step and the wetting agent is transferred here only to the hydrophilic first embossing lacquer layer of the first feature region.

The second feature region is preferably a region having a hydrophobic surface.

In an advantageous method guide, in the printing step, a layer of a second embossing lacquer is provided on a flexible printing tool, in particular a printing cylinder having a compressible element, which is locally deformed by a pressure tip generated by the already hardened first lacquer layer.

In a further, likewise advantageous method approach, in the printing step, a layer of the second embossing lacquer is provided on the printing tool, in particular a hard printing cylinder, and a soft pressure roller (pressure) is used for generating the counterpressure, which is locally deformed by the pressure tip generated by the already hardened first lacquer layer.

In a further, likewise advantageous method guide, a flexible compensation layer is provided on the carrier, which compensation layer is locally deformed by the pressure tip generated by the already hardened first lacquer layer in the printing step.

In an advantageous embodiment, the first embossing lacquer is applied, for example, printed, in a structured manner in the first feature region. However, it is also possible for the first embossing lacquer to be applied first over the entire surface and then removed again in regions, for example by an etching step, in order to achieve the desired structuring. Particularly high resolution can be achieved if, according to an advantageous embodiment, the first embossing lacquer is first applied to the support over the entire surface (or to the entire surface of the support) and is then structured by the approach of the structured embossing tool by the residue-free embossing method into a first wetted feature region and a second dewetted (entnetzt) feature region, wherein the embossed structures which produce the first optical effect are simultaneously embossed by the structured embossing tool for the first wetted feature region.

The first embossing lacquer can advantageously be hardened by irradiation, in particular by UV (ultraviolet) radiation, but also by IR (infrared) radiation or by the application of an electron beam. The use of UV-curing embossing lacquers is advantageous in particular if the embossing lacquer is structured with high resolution by the residue-free embossing method described.

According to a second aspect of the invention, in the method, a first embossing lacquer layer with a lower surface energy is applied to the carrier in the first feature region, the applied layer is embossed with an embossing structure producing the first optical effect and hardened.

A layer of a second, different embossing lacquer having a lower viscosity and a higher surface tension is then applied over the entire surface, and the second embossing lacquer is dewet from the first feature region coated with the first embossing lacquer into the second feature region.

The application and de-wetting process is repeated as necessary to collect a sufficient amount of the second imprinting lacquer in the second feature areas for imprinting.

In the second aspect of the invention, the carrier may also remain permanently in the security element or it may be a production carrier which is removed from the security element after transfer of the security element to the target substrate.

In both aspects of the invention, the second embossed structure is advantageously embossed into the embossing lacquer layer of the second embossing lacquer, said second embossed structure producing the second optical effect. In this case, the second imprinted structure is advantageously transferred exclusively into the second imprint lacquer layer, preferably by using a flexible imprint mold, a soft imprint pressure roller or a flexible compensation layer in the layer structure of the security element, in order to transfer the second imprint structure exclusively into the second imprint lacquer layer.

The embossed structures of the first and second embossing lacquer layer are advantageously located at substantially the same level, which means in particular that the difference in the intermediate level of the two embossed structures is not greater than the level difference within each embossed structure.

In both aspects, it is preferred that the two embossing lacquers have different curing properties, the embossing lacquers also particularly preferably having different optical properties.

As embossing lacquer, in each case a lacquer, in particular a thermoplastic embossing lacquer, can be applied which hardens by physical drying. If the first and second embossing lacquers are each formed by a thermoplastic embossing lacquer, the first and second embossing lacquers advantageously have different softening temperatures, which preferably differ by more than 10 ℃, particularly preferably by more than 25 ℃, in particular by more than 50 ℃.

In a likewise advantageous embodiment of both aspects, it is provided that the radiation-curing, in particular UV-curing, embossing lacquer is applied as one embossing lacquer and the thermoplastic embossing lacquer is applied as the other embossing lacquer.

The embossing lacquer can in particular be applied in different colors, different transparencies and/or different brilliances. The embossing lacquer is preferably pigmented to the gloss and is therefore both colored and partially transparent.

The embossing lacquer layers of the first and second feature regions are advantageously arranged side by side without gaps and overlaps.

In an advantageous further development of the invention, the first and second embossing lacquer layers are provided with a common reflection-enhancing coating, in particular a highly refractive or metallic coating. Such a coating is preferably carried out after embossing the first and second embossing lacquer with corresponding embossed structures producing different first and second optical effects.

The embossed structures of the first and second embossing lacquer layer each advantageously contain structural elements having a structure size in the plane of between 30 μm and 200 μm, in particular between 50 μm and 150 μm. One or both imprinted structures advantageously contain a micromirror arrangement having directionally reflecting micromirrors, in particular mirrors that act non-diffractively, and preferably plane mirrors, concave mirrors and/or fresnel-type mirrors, as structural elements.

It goes without saying that the optically variable security element can comprise further layers, for example a protective layer, a cover layer or additional functional layers, a machine-readable element, a primer layer or a heat-seal lacquer layer, which are however not essential elements of the invention and are therefore not described further. The security element to be produced is advantageously a security thread, in particular a window security thread or a security thread of pendulum type, tear-open security thread (Aufrei β faden), a security tape, a security strip, a patch or a label for application on security paper, value documents or the like.

The UV embossing lacquers and thermoplastic lacquers (also referred to as thermoplastics) used generally have the properties described below, wherein, however, lacquers having different properties can also be used for specific applications.

Typical UV embossing lacquers are first of all significantly easier to emboss than thermoplastic embossing lacquers. For example, for UV embossing, a liquid embossing lacquer may first be applied to the film. The embossing lacquer reaches the embossing mold without contacting the rollers. The film with the embossing lacquer is brought into contact with the embossing tool by means of a pressure roller, wherein the lacquer surface adopts or forms the structure of the (anehmen) embossing tool. In theory, no pressure is needed in any slow process and the paint simply flows into the structure and forces out the air. In practice, however, the embossing process on the machine is not arbitrarily slow, so that the paint can no longer completely force out the air within a predetermined time when embossing with too little pressure against the rollers. In practice, therefore, the embossing press is operated with a certain embossing pressure when certain requirements are placed on the speed and the bubble-free behavior. If no UV curing is performed, the lacquer will flow again immediately after contact with the imprint mold after the film has been removed from the imprint mold. In practice, however, the film wraps around the imprint mold to some extent. If the lacquered film is brought into contact with the embossing tool by means of a pressure roller, the film is generally no longer detached spontaneously from the embossing tool. After the top press roller, a UV emitter is arranged in the virtually pressureless region, which UV emitter cross-links the UV lacquer while it is still in contact with the embossing tool. Only after this reaction is the film removed from the imprint mold. The entire process is typically run continuously. The lacquers hardened in this way are usually thermosetting plastics.

Thermoplastic embossing is generally different from the described UV embossing. Thermoplastics are solid at room temperature and therefore non-flowable, and become imprintable at a certain temperature when the temperature is increased. If the temperature is further increased, the lacquer may become viscous, thereby limiting meaningful imprinting using standard imprint molds. However, a non-stick coated mold may be used if desired. In the case of thermoplastic embossing, the embossing punch can, for example, be heated, the embossing carried out at elevated temperature and, if appropriate, cooled slightly again before demolding. In a roll-to-roll (roller-zu-roller) process, cooling is typically not performed prior to demolding. In the case of thermoplastic embossing, the film can be heated, for example, if necessary in contact with an embossing mold, embossed at the highest temperature and immediately released from the mold without entering the viscous regions of the thermoplastic. This high heating, which causes the thermoplastic to become truly liquid, is advantageously avoided.

In order to avoid the adhesion of the thermoplastic with the lower melting point, the embossing tool is advantageously provided with a non-stick coating. Alternatively, a metallization of the unembossed embossing lacquer that prevents sticking can be provided, or it can be ensured that the higher-melting thermoplastic material does not become higher in melting point at a later point in time. This can be ensured, for example, by means of crosslinking agents mentioned elsewhere (e.g. isocyanates) or also by radiation crosslinking. For example, two thermoplastically imprintable UV raw materials can be placed side by side, wherein one of the two formulations (Formulierung) contains a photoinitiator. After the first imprint, exposure may be performed, in which case demolding may be performed afterwards, since the solid lacquer obtains the imprinted structure even without contact with the imprint mold. The formulations containing the photoinitiator thus increase the melting point and are no longer deformable under the previous printing conditions. A second imprint may then be performed. The second "thermoplastic" either remains uncrosslinked or is postcrosslinked by electron beam hardening (nachvernetzen), since the latter process can be carried out without photoinitiator. Alternatively, the second thermoplastic may likewise contain photoinitiators which are not active in the wavelength of the first emitter.

In addition to the already mentioned and advantageous designs of the embossing lacquer, it is also possible in principle to use an embossing lacquer which is thermally hardened or thermally crosslinked instead of photochemically hardened or crosslinked. For example, some embossing lacquers have a softening temperature T ₁ And a hardening temperature T ₂ >T ₁ . Such impression lacquers may be formed, for example, on the basis of acrylates with isocyanates.

A further working step consists in selectively heating one of the embossing lacquers. In this case, the regions with the substance that can be selectively excited (in the ultraviolet/visible/infrared or electrically/capacitively/magnetically with alternating fields) selectively cause only the regions containing the substance to heat up. In this way, for example, two regions with UV embossing lacquer can also be provided and the regions can be treated, in particular embossed, in succession.

Within the scope of the present description, a precisely registered (or fit-precise) layout of feature regions refers in particular to a layout in which the feature regions border one another or are arranged at a predetermined, defined, small distance from one another. Small distances are in particular distances of a few micrometers or a few tens of micrometers up to 100 micrometers, and in some applications may reach 200 micrometers.

Drawings

Further embodiments and advantages of the invention are explained below with reference to the drawings, which are not shown to scale and proportion to improve the intuitiveness.

In the drawings:

fig. 1 shows a schematic representation of a banknote with an optically variable security element;

fig. 2 shows a schematic representation of a security element with a carrier substrate having an embossed feature layer;

fig. 3 shows in (a) to (d) four intermediate steps in the production of a security element having a feature layer with two thermoplastic embossing lacquers with different softening temperatures;

fig. 4 shows in (a) to (d) four intermediate steps in the production of a security element with a feature layer made of a thermoplastic embossing lacquer and a UV embossing lacquer;

fig. 5 shows in (a) to (c) intermediate steps in the production of a security element by using a flexible imprint template;

fig. 6 shows in (a) to (c) intermediate steps in the production of a security element by using a hard imprint mold in combination with a soft imprint pressure roller;

fig. 7 shows intermediate steps in the production of a security element in which a flexible compensation layer is arranged in the layer structure, in (a) to (c);

fig. 8 shows in (a) to (d) intermediate steps in the application of two different embossing lacquers side by side in a feature layer without register fluctuations;

fig. 9 shows in (a) to (c) intermediate steps in a further variant for applying two different embossing lacquers side by side in a feature layer without register fluctuations;

fig. 10 shows in (a) to (c) intermediate steps in a further variant for applying two different embossing lacquers side by side in a feature layer without register fluctuations;

fig. 11 shows in (a) and (b) an intermediate step in the application and high-resolution structuring of a UV imprint lacquer layer;

fig. 12 shows in (a) and (b) an intermediate step in a further possibility for applying two different embossing lacquers side by side in a feature layer without register fluctuations;

fig. 13 shows in (a) to (c) intermediate steps in a method for the registered application of two different impression varnishes by means of mechanical layer stripping; and is

Fig. 14 shows in (a) to (d) intermediate steps in a method for the registered application of two different embossing varnishes by means of a selective stripping medium.

Detailed Description

The invention will now be illustrated by way of example of a security element for banknotes. Fig. 1 shows a schematic representation of a banknote 10 for this purpose, which banknote 10 has an optically variable security element 12 in the form of a sticky transfer element. It goes without saying, however, that the invention is not limited to transfer elements and banknotes, but can be used in all types of security elements, for example in labels on goods and packaging or in providing security for documents, identity cards, passports, credit cards, health cards, etc. For banknotes and similar documents, for example, security threads or strips can also be considered in addition to transfer elements (for example patches with or without their own carrier layer).

Despite the flat design of the security element 12, the security element 12 gives the observer a three-dimensional impression and, for example, when the banknote 10 is tilted, simultaneously exhibits a binary color and effect change, wherein a first three-dimensional pattern (Motiv, or subject) appears in a first color when viewed from a first viewing direction and a second three-dimensional pattern appears in a second color when viewed from a second viewing direction.

These visual effects and a large number of other visual effects can advantageously be produced by a security element in which two or more embossing lacquer layers, which are purposefully provided with different embossing structures that are independent of one another, are arranged side by side in register in the plane of the security element. In addition to different embossed structures, the embossing lacquer layer expediently also has other different properties, i.e. in particular different visual properties, such as different colours, transparency and/or brilliance. In this way, the optically variable effect produced by the embossing on the one hand and the visual effect produced by the additional properties of the embossing lacquer layer on the other hand can be matched to one another in perfect register.

For illustration, fig. 2 shows a schematic representation of a security element 20 having a carrier film 22 in the form of a transparent PET film, which carrier film 22 is provided with an embossed feature layer 24. The feature layer 24 consists of an alternating sequence of

feature regions

30, 40 of the desired shape and size (only one of the feature regions is assigned a respective reference numeral), which differ from one another by the different varnishing colors of the applied embossing lacquer layers 32, 42 and the different designs of the

respective embossing structures

34, 44.

The

imprint structures

34, 44 of the two

feature regions

30, 40 are located essentially at the same height level in a common plane and are provided with a common reflection-enhancing metal coating 26, for example a layer of vapor-deposited aluminum. In the present exemplary embodiment, the metallized embossed structure is smoothed by a lacquer layer 28, and the security element can be bonded to a desired target substrate, for example a banknote 10, by means of an adhesive layer 29. After bonding, the carrier substrate 22 can be removed or remain as a protective film in the security element.

The security element 20 is designed to be viewed through the gloss-applied

embossing lacquer layer

32, 42. In this case, the observer 14 observes the metallized imprinted structure 34 in the feature region 30 through the imprinted lacquer region 32, while he observes the metallized imprinted structure 44 in the feature region 40 through the imprinted lacquer region 42. For example, embossing lacquer 32 may be tinted with a tint to red and embossing structure 34 may produce a view of the camber of the value "10" as the pattern, while embossing lacquer 42 is tinted with a tint to green and embossing structure 44 may produce a view of the camber of the emblem as the pattern. The two patterns may also be identifiable from different viewing directions. As can be seen from fig. 2, the

feature regions

30, 40 with the different color effects produced by the embossing lacquer layers 32, 42 and the different patterns produced by the

embossing structures

34, 44 are arranged directly next to one another in register without gaps or overlaps.

The basic principle of advantageous production of the feature layer 24 of the security element 20 is now explained in more detail with reference to fig. 3 and 4, which show four intermediate steps in the production of the security element 20 in fig. 3 and 4 in (a) to (d), respectively.

Referring to fig. 3(a), a carrier film 22, such as a clear, colorless PET film, is first provided and thermoplastic embossing paints 32, 42 of the desired color effect are applied in the desired

feature areas

30, 40, respectively. In this case, the thermoplastic embossing lacquers 32, 42 are adapted to one another in such a way that, in addition to the different colors, they also have different softening temperatures and can therefore be embossed at different temperatures. For example, thermoplastic imprinting paint 42 is at a lower temperature T ₂ Can already be embossed, while the thermoplastic embossing lacquer 32 is at a higher temperature T ₁ >T ₂ Can be imprinted.

Then, at a higher temperature T ₁ In a first embossing step, a first embossing structure 34 is associated with the two

embossing varnishes

32, 42 by means of a first embossing tool 50, as shown in fig. 3 (b).

The carrier film with the imprinted feature layer is then cooled to a lower temperature T ₂ And demolded, and imprinting paint 32 in feature areas 30 having imprinting structures 34 is thereby cured, while imprinting paint 42 remains deformable. As a result, the embossing lacquer 42 still flows partially or completely after demolding and, at best, does not completely form the first embossed structure, as is shown in fig. 3(c) by reference numeral 34'.

Fig. 3(c) also shows a second imprint template 52 for a second imprint step, with which the second imprinted structure 44 is brought to a lower temperature T ₂ Is embossed into the still deformable embossing lacquer layer 42 of the feature area 40. The imprint structures 34 of feature regions 30 have solidified, inter alia, due to the more detailed description belowIs no longer significantly affected by the second embossing step.

After the second imprinting step, the carrier film with the twice-imprinted feature layer is cooled to a temperature T < T ₂ E.g., cooled to room temperature, and the imprint varnish 42 in the feature areas 40 is thereby cured.

In this manner, a feature layer 24 having the desired

dual imprint structures

34, 44 in registration with

feature regions

30, 40 is obtained, as shown in fig. 3 (d). The feature layer 24 can then be metallized as shown in fig. 2, or the intermediate product of fig. 3(d) can be further processed in a different manner into the desired security element.

In the embodiment of fig. 4, a thermoplastic embossing lacquer 32 and a UV embossing lacquer 42 are used instead of two thermoplastic embossing lacquers with different softening temperatures. In contrast to the embodiment described later, in the embodiment of fig. 4, the thermoplastic embossing lacquer is embossed first and only then the UV embossing lacquer is embossed. Even though UV imprint paints are generally easier to imprint than thermoplastic imprint paints, the imprint sequence shown in fig. 4 may be used when using a suitable imprint paint and/or under suitable conditions.

Referring to fig. 4(a), a carrier film 22, for example a transparent, colorless PET film, is provided and coated or painted with a thermoplastic imprint lacquer 32 in the feature areas 30 and with a UV imprint lacquer 42 in the feature areas 40, which respectively have the desired different color effects.

Then, in a first imprinting step, the first imprinted structure 34 is pressed into by the first imprint mold 50 under imprint conditions under which the thermoplastic imprint varnish 32 may be imprinted, as shown in fig. 4 (b). The imprinting conditions may, for example, comprise a temperature T of 120 ℃ ₁ And higher imprint pressures.

The carrier film with the imprinted feature layer is then cooled to a lower temperature T ₂ ＜T ₁ And demolded and the imprint lacquer 32 in the feature region 30 is thereby cured. E.g. lower temperature T ₂ May be T ₂ At 30 ℃. The UV imprint varnish 42 is not imprinted under the imprint conditions of the first imprint step, and is therefore imprinted in the first imprintAfter this step, there is an imprint lacquer 32 provided with the imprint structures 34 in the feature areas 30 and an unembossed UV imprint lacquer 42 in the feature areas 40, as shown in fig. 4 (c).

Fig. 4(c) also shows a second imprint template 52, by means of which the temperature T is lower ₂ And UV radiation 54, the second imprint structures 44 are pressed into the imprint lacquer layer 42 of the feature regions 40, which can be hardened by UV. By hardening the embossing lacquer layer 42 by means of radiation from the UV-LED, the heat input into the thermoplastic layer 32 can be minimized. Due to the lower temperature in the second imprinting step and due to the measures described in more detail below, the already solidified imprinted structure 34 of the feature region 30 is not significantly affected by the second imprinting step.

After the second embossing step and UV curing, embossing lacquer 42 is also cured in feature areas 40, so that, as shown in fig. 3, a feature layer 24 is obtained having the desired double embossed

structures

34, 44 in register with

feature areas

30, 40, as shown in fig. 4 (d).

In the embodiments described in conjunction with fig. 3 and 4, the two embossing lacquer layers 32, 42 are already present on the carrier film in the first embossing step. However, it is also possible to apply the layer requiring subsequent embossing after the layer requiring first embossing has been embossed. It is also important in this case that the imprinted structure of the first imprinted layer remains unchanged under the imprinting conditions of the subsequently imprinted layer. Special measures are usually required for this purpose, which are now explained in more detail with reference to fig. 5 to 7.

One possibility for ensuring that the imprinted structure of the first imprinted layer is not destroyed or damaged by the subsequent imprinting step is to use a flexible imprint mold for the second imprinting.

This is illustrated in accordance with the embodiment of fig. 5, in which, analogously to the example of fig. 4, the feature layer 24 comprises, on the one hand, feature regions 30 with a thermoplastic embossing lacquer 32 and, on the other hand, feature regions 40 with a UV embossing lacquer 42. The

structures

34 and 44 to be pressed in respectively have a structure dimension L of 50 μm to 150 μm in a plane ₁ And L ₂ . The structure height is typically on the order of a few microns.

In the variant of fig. 5, the UV embossing lacquer 42 is first provided with the desired second embossing structure 44 and subsequently hardened, as shown in fig. 5 (a). The thermoplastic embossing lacquer 32 can likewise be embossed or, as shown in fig. 5(a), it can be kept free of embossed structures by flowing.

The first imprint structure 34 is now pressed in by means of a flexible imprint template 60, which has the desired imprint structure 34 on its surface. The flexible imprint mold 60 is formed of, for example, silicone rubber, and deforms due to a pressure tip (Druckspitze) on a length scale λ of several micrometers. The feature region 40 with the already cured UV imprint lacquer 42 acts during imprinting upon a corresponding deformation 62 of the flexible imprint template 60, so that on the one hand the already cured imprint lacquer region 42 is not damaged, but on the other hand the imprint lacquer 32 can be imprinted in the feature region 30 with the imprint structures 34, as shown in fig. 5 (b).

The transition region 64 in which the shape of the imprint mold 60 changes significantly due to the fact that it has an order of λ < L ₁ 、L ₂ I.e., the transition region 64, is significantly smaller than the structural dimensions of the

imprint structures

34, 44, the imprint structures in the transition region 64, which may be small, defective, or even absent, have no significant effect on the overall quality of the imprint structures 34 in the feature region 30.

Thus, after the thermoplastic imprint lacquer 32 has cooled and the flexible imprint mold 60 has been released, the feature layer 24 is provided with the desired registered

dual imprint structures

34, 44 in the

feature regions

30, 40, as shown in fig. 5 (c).

Referring to fig. 6, another possibility consists in using a hard embossing tool 70 in combination with a soft embossing top roller 72 and a suitable carrier film 74 in the security element.

In this embodiment, the original situation shown in fig. 6(a) largely corresponds to the original situation of fig. 5(a), i.e. the presence of the feature layer 24 on a suitable carrier film 74, which will be described in more detail below, features being present thereinA thermoplastic embossing lacquer 32 is applied in region 30 and a UV embossing lacquer 42 is applied in feature region 40. In this case, the UV embossing lacquer 42 has already been provided with the desired embossing structure 44 in the first embossing step. The

structures

34, 44 to be pressed in also have a structure dimension L in the plane of between 50 μm and 150 μm ₁ And L ₂ 。

In order to imprint the imprint structure 34 in the second imprint step, a hard imprint mold 70, which may be made of nickel, for example, is used in the method of fig. 6. The hard embossing tool 70 is particularly suitable for embossing the thermoplastic lacquer 32, but has a lower compensation capability for height differences than the flexible embossing tool 60 of the embodiment of fig. 5.

In order to be able to ensure that the already embossed and hardened lacquer region 42 is not deformed or damaged in the second embossing step, use is made of the fact that embossing always requires a counter-pressure, which is usually applied by an embossing pressure roller 72. As a special feature, a relatively soft embossing pressure roller 72 is used in the method of fig. 6, which is made of an elastomer having a hardness of less than 90 shore, in particular less than 85 shore.

As schematically shown in fig. 6(b), in a second embossing step, the UV embossing lacquer regions 42, which have already been hardened, are pressed together with the carrier film 74 into the soft embossing pressure roller 72 by the hard embossing tool 70 sufficiently far that the embossing of the thermoplastic embossing lacquer 32 can take place without damaging or destroying the UV embossing lacquer regions 42.

After cooling and demolding of the thermoplastic imprint lacquer 32, the feature layer 24 is thus provided with the desired registered

double imprint structures

34, 44 in the

feature regions

30, 40, as shown in fig. 6 (c).

As an alternative or in addition to the use of a soft embossing press 72, the press may also be equipped with a structured surface which locally limits the deformation of the press. For example, the surface may be divided to have λ _c Individual cells of characteristic size 25 μm, so that, for example, the structure size in the embossed

structure

34, 44 is L ₁ 、L ₂ When 100 μm, it is expectedIn each case a plurality, in particular 9 honeycomb segments can exert their desired embossing pressure, while the adjacent segments are strongly deformed.

Returning to the advantageous properties of the carrier film 74, it must be sufficiently easily deformable under the embossing conditions of the second embossing step to allow the height compensation shown in fig. 6(b) to be carried out by the embossing top roller 72.

For this purpose, for example, a very thin carrier film 74 can be used, the thickness of which is preferably less than 23 μm, in particular less than 19 μm and particularly preferably between 6 μm and 15 μm. Alternatively or additionally, carrier film 74 can also be adapted to the embossing conditions in such a way that the glass transition temperature T of the carrier film is adapted to the embossing conditions _g Is exceeded under the embossing conditions of the second embossing step and the film is therefore particularly susceptible to deformation.

Another possibility for ensuring that the layer which is imprinted first is not destroyed or damaged under the imprinting conditions of the subsequently imprinted layer consists in providing a compensation layer 80 in the layer structure of the security element itself.

For illustration, fig. 7 shows a layer structure of a security element to be produced, wherein a compensation layer 80 is arranged between carrier film 22 and feature layer 24, which compensation layer is flexible at least under the embossing conditions of the second embossing and preferably has elastic properties. If provision is made for the optical effect of the security element to be viewed from the side of the

embossing lacquer layer

32, 42 and thus also through the compensation layer, the compensation layer is preferably transparent and designed to have a low scattering effect. Specifically, the compensation layer 80 may be formed of, for example, silicone rubber.

The initial situation shown in fig. 7(a) largely corresponds to the initial situation of fig. 6(a), in particular the feature layer 24 contains a thermoplastic embossing lacquer 32 in the feature region 30 and a UV embossing lacquer 42 in the feature region 40, which UV embossing lacquer has been provided with the desired embossed structures 44 in the first embossing step.

The imprinted structure 34 may then be imprinted in a second imprinting step using a hard imprinting mold 70 that is particularly suitable for imprinting the thermoplastic lacquer 32. Referring to the view of fig. 7(b), the second embossing step of the thermoplastic lacquer 32 is carried out at an elevated temperature at which the compensation layer 80 is elastic, so that the UV embossing lacquer regions 42 which have hardened are locally pressed into the compensation layer 80 by the hard embossing mold 70. This prevents the embossing structure 44 from being deformed or damaged and at the same time enables embossing of the embossing lacquer layer 32.

In order for the UV embossing lacquer regions 42 to be pressed in sufficiently, the layer thickness of the compensation layer 80 should be slightly greater than the height difference to be compensated, which in the case of typical embossed microstructures 44 is typically between 2 and 15 μm. The compensation layer 80 can also advantageously be deformed in such a way that, when the UV embossing lacquer regions 42 are pressed in, the thermoplastic embossing lacquer regions 32 are simultaneously pressed slightly upwards and thus contribute to the second embossing. This deformation can be carried out in particular while maintaining the volume.

After the second embossing step has ended and the thermoplastic embossing lacquer 32 has cooled and been released from the mold, the deformation of the elastic compensation layer 80 returns to its original shape, so that the produced feature layer 24 is provided with the desired registered

double embossing

34, 44 in the

feature regions

30, 40, as shown in fig. 7 (c).

In the embodiments described so far, it is assumed that the

feature regions

30, 40 already have registered embossed paint regions on the carrier film. Some advantageous possibilities for applying two or more different embossing lacquers side by side and therefore ideally without unintentional gaps or overlaps in the feature layer without register fluctuations are now described next.

First, a modification of the phenomenon using surface energy or surface tension is described here. Depending on the material of the carrier film used, it may be necessary to first provide the carrier film with a coating having a suitable surface energy. Other layers may be required for this purpose, such as a primer layer or a release layer for subsequent release. Corona treatment, plasma treatment or flame treatment of the film may also contribute to sufficient adhesion. In the following description, it is assumed that the carrier 90 mentioned is or comprises a suitable carrier film and may have been pretreated accordingly or provided with further layers in order to provide a surface energy suitable for the respective method.

In the process variant shown in fig. 8, the carrier 90 is first printed in the characteristic regions 40 by any method with a formulation 42 that can be embossed and that is hydrophilic after drying, said formulation 42 having the desired color or transparency in the characteristic regions 40. In the illustrated embodiment, the formulation is a UV embossing lacquer 42 which, after printing, is embossed with associated embossing structures 44 in the feature regions 40 and is finally cured by UV crosslinking, as illustrated in fig. 8 (a). Here, the characteristic region 30 is initially uncoated and represents a region with a hydrophobic surface.

The carrier film provided with the UV impression lacquer is then moistened inline with the moistening agent 92 or in a separate process. Here, only the hydrophilic coated feature regions 40 receive the wetting agent 92, while the hydrophobic feature regions 30 remain free of the wetting agent, as shown in fig. 8 (b).

A second embossing lacquer layer of the thermoplastic embossing lacquer 32 is then applied to the carrier film, for which purpose in the present exemplary embodiment a printing cylinder 94 is used, on which printing cylinder 94 the embossing lacquer layer 32 is provided over its entire surface, as is shown in fig. 8 (b). In order to achieve the application of the embossing lacquer 32 only in the gaps 30 between the already coated regions 40, the surface of the printing cylinder 94 is provided with compressible elements 96.

The compressible element 96 is deformed during the printing of the embossing lacquer layer 32 by the pressure tip produced by the UV lacquer layer 42 that has already hardened, as shown in fig. 8(c), so that the embossing lacquer 32 comes into contact with the carrier 90 in the non-raised feature region 30 and is transferred there without damaging the already present embossing structure 44. Although the UV impression lacquer 42 of the feature areas 40 is also in contact with the impression lacquer layer 32 when printing, it is ink-repellent (farbabweisend) and therefore does not accept the impression lacquer 32 due to the previously applied wetting agent 92.

In this way, the thermoplastic imprint lacquer 32 is deposited only in the feature areas 30 during the printing step, as shown in fig. 8 (d). UV imprint lacquer 42, which has been imprinted and hardened, is present in the feature areas 40. The intermediate product thus obtained can then be further processed, for example as described in conjunction with fig. 5 to 7, and the embossing lacquer layer 32 can also be provided with the desired embossing structure. Instead of the thermoplastic embossing lacquer, other UV embossing lacquers can also be used, which can also have the same curing properties as the first embossing lacquer, since the first embossing lacquer is already cured when printing the other embossing lacquer.

In the method variant of fig. 9, a soft pressure roller 98 with a shore hardness of less than 90, in particular less than 85, is used instead of the compressible element in the printing cylinder.

The original situation shown in fig. 9(a) essentially corresponds to the original situation of fig. 8 and shows the carrier 90 which has been coated with the hydrophilic UV imprint lacquer 42 after hardening in the feature region 40. The UV imprint lacquer 42 is imprinted with the desired imprint structure 44 and hardened by UV crosslinking. The carrier film coated in this manner is then moistened with the moistening agent 92 either inline or in a separate process, wherein only the hydrophilically coated feature areas 40 receive the moistening agent 92, while the uncoated feature areas 30 remain free of the moistening agent.

A second layer of embossing lacquer of the thermoplastic embossing lacquer 32 is then applied over the entire surface of the printing cylinder 94. The soft top pressure roller 98 provides the counter pressure for the printing step, but due to its lower hardness of less than 90 or less than 85 shore a, it can be deformed locally by the pressure tip. As schematically shown in fig. 9(b), during printing of the embossing lacquer layer 32, the UV embossing lacquer region 42, which has already been hardened, is pressed slightly into the soft top roller 98 together with the carrier film 90 by the printing cylinder 94, so that the thermoplastic embossing lacquer 32 in the feature region 30 comes into contact with the carrier film 90 and is transferred there without damaging the already present embossing structure 44.

Although the UV embossing lacquer region 42 is also in contact with the embossing lacquer layer 32, it is ink-repellent and therefore does not accept the embossing lacquer 32 due to the applied wetting agent 92. Thus, a design with unembossed thermoplastic imprint lacquer 32 in feature areas 30 and embossed, hardened UV imprint lacquer 42 in feature areas 40 is produced by the printing step, which can be further processed as described above. Instead of the thermoplastic embossing lacquer, it is also possible to use other UV embossing lacquers, which may also have the same curing properties as the first embossing lacquer, since the first embossing lacquer is already cured when printing the other embossing lacquer.

In this variant, the carrier film 90 must be sufficiently easily deformable under the printing conditions of the second embossing lacquer 32 to allow the height compensation shown in fig. 9(b) to be achieved by the pressure roller 98. For this purpose, for example, a very thin carrier film 90 (preferably having a thickness of less than 23 μm, in particular 19 μm, in particular a thickness of between 6 μm and 15 μm) and/or a carrier film 90 having a low glass transition temperature, which is exceeded by the printing conditions of the second embossing lacquer, can be used, so that the film is particularly easily deformable.

Another possibility consists in providing a compensation layer 80 in the layer structure of the security element itself. Referring to fig. 10, in the layer structure of the security element to be produced, a compensation layer 80 is arranged on the carrier film 22, which compensation layer is flexible at least in the printing condition of the embossing lacquer layer 32 and preferably has elastic properties.

The original state shown in fig. 10(a) corresponds to the original state of fig. 9(a) with the exception of the compensation layer and shows the carrier film 22 with the applied compensation layer 80, for example made of silicone rubber, which is coated with the UV imprint lacquer 42, which is hydrophilic after hardening, in the feature region 40. The compensation layer can also be provided with a thin cover layer in order to make it easier to subsequently apply the

embossing lacquer layer

32, 42 and/or to provide a suitable surface energy. The UV imprint lacquer 42 is imprinted with the desired imprint structure 44 and hardened by UV crosslinking. The carrier film coated in this manner is then moistened with the moistening agent 92 either inline or in a separate process, wherein only the hydrophilically coated feature areas 40 receive the moistening agent 92, while the uncoated feature areas 30 remain free of the moistening agent.

A second layer of embossing lacquer of the thermoplastic embossing lacquer 32 is then applied over the entire surface of the printing cylinder 94. As shown in fig. 10(b), the compensation layer 80 is elastic in the printing condition of the thermoplastic lacquer 32, so that the UV imprint lacquer areas 42 that have hardened are locally pressed into the compensation layer 80 by the printing cylinder 94. This prevents the embossed structures 44 from being deformed or damaged and allows the embossing lacquer layer 32 to be applied without problems precisely in the gaps 30 between the UV embossing lacquer regions 42.

In order to be able to press the UV embossing lacquer regions 42 far enough, the layer thickness of the compensation layer 80 should be slightly greater than the height difference to be compensated, which is typically between 2 and 15 μm.

Although the UV embossing lacquer region 42 is also in contact with the embossing lacquer layer 32, it is ink-repellent and therefore does not accept the embossing lacquer 32 due to the applied wetting agent 92.

After the printing step is completed, the deformation of the resilient compensation layer 80 returns to its original shape, thus forming the desired design shown in fig. 10(c) with unembossed thermoplastic imprint lacquer 32 in the feature areas 30 and embossed, hardened UV imprint lacquer 42 in the feature areas 40, which may be further processed as described above.

If a particularly high-resolution structuring of the UV embossing lacquer layer 42 is to be achieved in the described embodiment, instead of printing the embossing lacquer layer in a structured manner as in the exemplary embodiment of fig. 8 to 10, the embossing lacquer layer 42 can also be applied in a residue-free embossing process, as described in principle in patent document EP 3230795B 1.

In order to be able to successfully carry out such high-resolution, residue-free embossing, the surface energy of the carrier, the embossing tool used and the surface tension of the embossing lacquer must be adapted to one another.

Referring to fig. 11(a), in the method, first the UV imprint paint 42 is applied to the carrier 90 over the entire surface. Structured imprint mold 100 includes

mold regions

102, 104 having different height levels, the shape and size of which correspond to feature regions 30 (raised mold region 102) or 40 (recessed mold region 104). The desired imprint structures 44 of the feature regions 40 are arranged in a recessed mold region 104, which in a subsequent imprint step is remote from the layer 42 to be imprinted.

When the structured embossing mold 100 approaches the entire embossing lacquer layer 42, which is not yet cured, the raised regions 102 reduce the layer thickness of the embossing lacquer 42 present there by extrusion due to their geometry. More precisely, based on the wetting properties of the imprint lacquer 42, the release coefficient, i.e. the interface energy between the carrier 90 and the imprint lacquer 42 and between the imprint lacquer 42 and the structured imprint mold 100, becomes negative, so that the imprint lacquer 42 withdraws from the feature region 30 below the convex mold region 102 into the feature region 40 below the concave mold region 104.

The tendency of wetting and dewetting depends not only on the surface energy but also on the layer thickness. In the feature region 30, the protruding mold region 102 of the imprint mold 100 thus locally leads to a residue-free dewetting of the imprint varnish 42 when approaching. The imprint lacquer 42 collected in the feature region 40 is imprinted there by imprint structures 44 arranged in the recessed mold region 104.

After the curing of the embossing lacquer 42, the carrier film 90 therefore contains the desired high-resolution structures with embossed, cured UV lacquer regions 42 and feature regions 30 lying therebetween which are still uncoated, as is shown in fig. 11 (b). Further processing may then be performed, for example, as already described in connection with fig. 8 to 10.

According to a further method variant, which also uses the phenomenon of surface energy or surface tension, with reference to fig. 12(a), a layer of a first embossing lacquer 32 is first printed onto a support 90, said first embossing lacquer having a particularly low surface energy after it has dried or crosslinked. The printed first embossing lacquer 32 is embossed and dried or hardened. The first embossing lacquer 32 is applied here in a structured manner, so that there are feature regions 30 with this first embossing lacquer and feature regions 40 without embossing lacquer which are not yet coated. It has proven advantageous here to provide approximately half of the total area to be coated with the first embossing lacquer 32.

A second imprint varnish formulation 42 having a low viscosity and a high surface tension is then applied over the entire surface. This corresponds to the case of the intermediate step shown in fig. 12 (a). The second imprint paint formulation 42 may be a UV imprint paint, particularly a water-dilutable formulation, which may also have to be physically dried before imprinting.

Due to its low viscosity and high surface tension, the second formulation 42 is dewetted from the first imprint varnish 32, which has a lower surface energy, as is indicated in fig. 12(a) by the arrow 110, so that the situation in fig. 12(b) results after dewetting. In the case of complete de-wetting, as shown in fig. 12(b), the application of the second embossing lacquer formulation 42 can also be repeated a number of times, so that material with a high surface tension continuously accumulates in the feature areas 40 until there is a sufficient amount of the second embossing lacquer 42 there for the desired second embossing.

In addition to the described utilization of the surface energy and surface tension phenomena, there is also an advantageous possibility based on layer stripping (schichtbastrag) for applying two or more different layers of embossing lacquer side by side without register fluctuations, which is now described in more detail in connection with fig. 13 and 14.

Referring first to fig. 13, a first layer made of a first thermoplastic embossing lacquer 42 having a desired first color is structurally applied to carrier film 22 and dried. The first embossing lacquer 42 is applied in a structured manner in the pattern of the feature areas 40, but with the applied layer thickness d ₁ Greater than the final desired layer thickness d ₀ As shown in fig. 13 (a).

A second layer of a second thermoplastic embossing lacquer 32 having the desired second color is then applied over the entire surface. As shown in fig. 13(b), the second embossing lacquer 32 is advantageously provided with a layer thickness d ₂ >d ₁ The second embossing lacquer is applied, but in principle in a layer thickness d ₂ >d ₀ Application is sufficient. The second embossing lacquer 32 can also be applied in a plurality of steps and in each case in conjunction with a wiping or scraping (Rakel) step, in order to keep the layer thickness of the second embossing lacquer 32 low on the first embossing lacquer region 42 applied.

After the second imprint varnish 32 has cured or has physically dried, the resulting structure is mechanically stripped to the desired layer thickness d ₀ Projecting beyond the layer thickness d, for example by milling 120 ₀ Layer area 122. If the milling cutter 120 is set to the desired targetThe layer thickness, at which the two

embossing varnishes

32, 42 are exposed in the

feature regions

30, 40 in a precisely side-by-side arrangement, as shown in fig. 13(c), can then be milled to this target layer thickness in the simplest case.

The fine-tuning and feedback of the milling step 120 may be performed by means of milling the strippings, i.e. the material removed from the layer areas 122. As shown in fig. 13(b), during the milling process, initially only the material of the higher second embossing lacquer 32 is removed in the still small layer stripper 124, and in the case of larger layer strippers also the material of the first embossing lacquer 42 is stripped. The desired stripping depth can thus be controlled by spectroscopic inspection or, if necessary, also simply by inspection of the color of the milled strippings. It is thereby ensured that the excess of the second embossing lacquer 32 present on the first embossing lacquer region 42 is completely stripped off and reliably reaches the end position shown in fig. 13 (c).

In the further embodiment of fig. 14, two different embossing lacquers are used to produce the feature layer 24, one of which is soluble in the stripping medium and the other is insoluble.

Referring first to fig. 14(a), a first color UV imprinting lacquer 42 is first applied on carrier film 22, structured in feature areas 40. The UV imprinting paint 42 is typically imprinted with the desired imprinting structures 44 and hardened. The feature areas 30 located between the imprint lacquer regions 42 ideally remain completely uncoated.

A thermoplastic impression lacquer 32 is then provided, which has a second color and for which there is a suitable stripping medium, by means of which the dried impression lacquer 32 can be removed at a well-defined stripping rate, but which does not dissolve the UV impression lacquer 42.

As shown in fig. 14(b), a second layer is applied to carrier film 22 over the entire surface using this embossing lacquer 32. Application can be effected, for example, in flexographic printing (or flexography), in which the flexographic sleeve, at a relatively high pressure, already presses a significant portion of the impression lacquer 32 into the recesses 130 between the already hardened UV impression lacquer regions 42, and only relatively little ink remains on the impression lacquer regions 42.

The embossing lacquer 32 is still liquid immediately after it has been applied, so that excess can be wiped or scraped off from the printed film and thus removed, in particular, from the already hardened embossing lacquer region 42. After the embossing lacquer 32 has been physically dried, the recesses 130 between the already hardened UV embossing lacquer regions 42 are partially filled, as shown in fig. 14 (b). A thin, color-tone film 132 of embossing lacquer material is also generally present on the embossing lacquer region 42.

The embossing lacquer 32 is repeatedly applied and excess material removed until the recesses 130 are sufficiently filled or even overfilled, as shown in fig. 14 (c). The repetition improves the relationship between the filling level of the recesses 130 and the undesired color tone 132 of the embossing lacquer region 42. It may be provided here that the color depth of the embossing lacquer 32 is changed in a stepwise filling process, in particular toward lower and lower color depths, since the hue of the respective penultimate application step is also reduced when wiping off or scraping off and thus the proportion of undesired colors on the embossing lacquer region 42 is reduced.

After the final repeated application and wiping or scraping, the thermoplastic imprint paint 32 is physically dried, thus creating the condition shown in fig. 14 (c).

The embossing lacquer 32 is then subjected to a development step (Entwicklungsschrit) by means of an associated stripping medium. The stripping medium may be aqueous, have a defined pH or may also be solvent-based. Where it may be desirable to expose imprinting lacquer 32 prior to stripping.

Once the imprint paint 32 is sufficiently stripped by the stripping medium to expose (freelegen) imprint paint region 42, the stripping process is stopped, such as by rinsing with another medium. The hardened UV imprint lacquer 42 is not stripped by the stripping medium of the imprint lacquer 32, so that the exposure takes place with a high selectivity.

After the stripping step is completed, there are desired structures on the carrier film 22 having feature regions 40 with an imprinted UV imprint lacquer layer 42 of the first color and feature regions 30 between the feature regions 40, which feature regions 30 have a still unembossed thermoplastic imprint lacquer layer 32 of the second color, as shown in fig. 14 (d). The further processing can be carried out, for example, in accordance with the working steps already described.

Instead of the UV embossing lacquer 42, other thermoplastic embossing lacquers can also be used in the working step of fig. 14. The thermoplastic embossing lacquer may be insoluble in the stripping medium of the embossing lacquer 32 from the outset, or the thermoplastic embossing lacquer may contain a crosslinking agent which renders it insoluble in the stripping medium of the embossing lacquer 32, but the crosslinking reaction of the crosslinking agent has not yet proceeded at the time of the first embossing to such an extent that embossing is prevented. Such a crosslinking agent may be, for example, an isocyanate, wherein the use of an aliphatic isocyanate leads to a slower reaction if the embossing should take place with a certain time delay after the coating step.

The application of the first embossing lacquer layer 42 can take place by applying the desired pattern in a structured manner onto the feature regions 40. However, in particular in the case of UV embossing lacquers, it is also possible to first apply the embossing lacquer layer over the entire surface and then structure it as desired. The advantageous possibility for this purpose, in particular for structuring the UV embossing lacquer layer with high resolution, has already been described above. If the thermoplastic embossing lacquer is applied as the first embossing lacquer layer, pressure at elevated temperature or pressure from the melt may be required in order to successfully carry out the fine structuring with sufficient layer thickness.

Before and/or after embossing the first embossing lacquer layer 42, a further method step can be provided, with which the embossing lacquer is converted into a stable and/or embossable form. Here, this may be, for example, an exposure step or an annealing step. A wet-chemical treatment can also be provided, in which the impression lacquer is brought into contact with a liquid medium in order to cause hardening or crosslinking.

List of reference numerals

10 banknote

12 security element

14 observer

20 security element

22 carrier film

24 characteristic layer

30 characteristic region

32 embossing lacquer layer

34 embossing structure

34' incompletely formed stamped structures

40 characteristic region

42 embossing lacquer layer

44 embossed structure

50. 52 stamping die

60 flexible impression mould

62 deformation part

64 transition region

70 hard impression mould

72 soft top pressure roller

74 Carrier film

80 compensation layer

90 vectors

92 humectant

94 printing cylinder

96 compressible element

98 soft top pressure roller

100 structured imprinting mold

102 protruding die area

104 recessed mold area

110 dewetting section

120 milling cutter

130 recess

132-tone film

Claims

1. A method for producing a security element for securing a valuable item, comprising a feature layer (24) having first and second feature regions (30, 40) in which different first or second embossing lacquer layers are present, wherein, in the method,

-applying a hydrophilic layer of a first embossing lacquer (42) on a carrier (90) in the first feature areas (40), the applied layer being embossed with embossing structures (44) producing a first optical effect and hardened,

-providing a different layer of a second imprint lacquer (32) on the printing tool (94), and

-contacting the printing tool (94) with the carrier (90) and thereby transferring the second imprint varnish (32) in the printing step.

2. A method according to claim 1, characterized in that in the printing step, the second embossing lacquer (32) is transferred only into the second feature areas (30) which are not coated with the hydrophilic embossing lacquer (42).

3. The method according to claim 1 or 2, characterized in that the carrier is wetted with the first embossing lacquer layer before the printing step and the wetting agent (92) is transferred only to the hydrophilic first embossing lacquer layer of the first feature region (40).

4. Method according to at least one of claims 1 to 3, characterized in that the layer of the second, different embossing lacquer (32) is provided over the entire surface of the printing tool (94).

5. Method according to at least one of claims 1 to 4, characterized in that in the printing step a layer of the second embossing lacquer (32) is provided on a flexible printing tool, in particular a printing cylinder (94) having a compressible element (96), which is locally deformed by a pressure tip generated by the already hardened first lacquer layer (42).

6. Method according to at least one of claims 1 to 4, characterized in that, in the printing step, a layer of a second embossing lacquer (32) is provided on a printing tool, in particular a hard printing cylinder (94), and a soft top roller (98) is used for generating the counter pressure, which top roller is locally deformed by the pressure tip generated by the already hardened first lacquer layer (42).

7. Method according to at least one of claims 1 to 4, characterized in that a flexible compensation layer (80) is provided on the carrier (22), which compensation layer is locally deformed during the printing step by the pressure tip generated by the already hardened first lacquer layer (42).

8. Method according to at least one of claims 1 to 7, characterized in that the first embossing lacquer (42) is first applied to the entire surface of the carrier (90) and is subsequently structured by a residue-free embossing method by the approach of a structured embossing tool (100) into the wetted first feature region (40) and the dewetted second feature region (30), and simultaneously the embossed structures (44) which produce the first optical effect are embossed by the structured embossing tool (100) for the wetted first feature region.

9. Method according to at least one of claims 1 to 8, characterized in that the first embossing lacquer (42) is hardened by the action of radiation, in particular by UV irradiation.

10. A method for producing a security element for securing a valuable item, comprising a feature layer (24) having first and second feature regions (30, 40) in which different first or second embossing lacquer layers are present, wherein, in the method,

-applying a layer of a first imprint lacquer (32) having a lower surface energy on a carrier (90) in a first feature region (30), the applied layer being imprinted with imprint structures (34) producing a first optical effect and hardened,

-applying a layer of a second, different embossing lacquer (42) having a lower viscosity and a higher surface tension over the entire surface and dewetting the second embossing lacquer (42) from the first feature region (30) coated with the first embossing lacquer into the second feature region (40), and

-repeating the applying and de-wetting process as necessary to collect a sufficient amount of second embossing lacquer (42) for embossing in the second feature areas (40).

11. Method according to at least one of claims 1 to 10, characterized in that a second embossing structure (44) is embossed into the embossing lacquer layer of a second embossing lacquer (42), which second embossing structure produces a second optical effect.

12. Method according to claim 11, characterized in that the second embossed structure is transferred only into the second embossing lacquer layer, preferably by using a flexible embossing tool (60), a soft embossing top roller (72) or a flexible compensation layer (80) in the layer structure of the security element, in order to transfer the second embossed structure only into the second embossing lacquer layer.

13. The method as claimed in any of claims 1 to 8, 10 to 12, characterized in that thermoplastic embossing lacquers with different softening temperatures are applied as embossing lacquers (32, 42).

14. The method as claimed in any of claims 1 to 12, characterized in that a radiation-hardening, in particular UV-hardening, embossing lacquer (42) is applied as one embossing lacquer and a thermoplastic embossing lacquer (32) is applied as another embossing lacquer.

15. Method according to at least one of claims 1 to 14, characterized in that embossing paints (32, 42) of different colors, different transparencies and/or different brilliance are applied.

16. The method according to at least one of claims 1 to 15, characterized in that the embossing lacquer layers of the first and second characteristic regions (30, 40) are arranged side by side without gaps and overlaps.

17. The method according to at least one of claims 1 to 16, characterized in that the first and second embossing lacquer layers are provided with a common reflection-enhancing coating (26), in particular a highly refractive or metallic coating.