EP3302997A1

EP3302997A1 - Method for manufacturing a security element, security element obtained thereby, security paper, and value document

Info

Publication number: EP3302997A1
Application number: EP16730682.8A
Authority: EP
Inventors: Winfried HOFFMÜLLER; Theodor Burchard; Maik Rudolf Johann Scherer; Ralf Liebler; Michael Rahm
Original assignee: Giesecke and Devrient Currency Technology GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2015-06-05
Filing date: 2016-06-02
Publication date: 2018-04-11
Anticipated expiration: 2036-06-02
Also published as: DE102015007233A1; WO2016192854A1; EP3302997B1

Abstract

The invention relates to a method for manufacturing a security element for a security paper or an object of value, in particular a document of value, said method involving the following steps: a) providing a transparent carrier substrate; b) providing a layer of stamping lacquer, which has a stamping structure, on the carrier substrate; d) applying a crack-forming coating to the layer of stamping lacquer and drying the crack-forming coating such that the coating forms numerous cracks in the form of a close-meshed, uninterrupted grid when drying; e) applying a metal coating to the carrier substrate obtained in step d); f) removing the coating having cracks along with any metal located on the coating such that a transparent, conductive metal coating in the form of a close-meshed, uninterrupted grid remains on the layer of stamping lacquer in the region of the coating that has cracks and has been be removed.

Description

Method for producing a security element, security element available therefrom, security paper and value document

The invention relates to a method for producing a

Security elements for a security paper or a valuable item, in particular a value document. The invention further relates to a security element obtainable by the method and to a security paper or value document provided therewith.

Security elements with in transmitted light, and possibly also in reflected light, visually recognizable characters are known. The characters may have any shapes, such as numbers, letters, patterns, geometric or figurative representations, etc., and are generally referred to as "negative writing" regardless of their shape The security elements are made, for example, by a transparent substrate having a coating, generally If the security element is held against the light, the areas with metallic or other coating appear dark and the areas where the coating has been removed appear On the other hand, the more transparent or translucent a substrate is, the more pronounced the contrast between the coated and the transparent

coating-free areas. For very transparent substrates, the negative writing is clearly visible not only in transmitted light but also in incident light.

In vapor deposition processes, metallic coatings are formed in the

Essentially full surface. The provision of recesses within the metallic coating can in the simplest case by the insertion a shutter or a shielding plate during the

Steaming process done. This measure only leads to coarse-structured metallizations. Optically appealing

However, security elements require fine structuring.

Finely structured metallizations can e.g. by etching processes

to be provided. In this case, the metal to be structured is applied in a first step over the entire surface of the substrate and coated in a second step in certain subject areas with a suitable resist. In a third step, the removal (or chemical conversion) of the metal into the non-resist paint

protected areas by means of an etching medium. The resist can also be applied over the entire surface and selectively changed by exposure in such a way that certain areas of the resist are selectively removed and the metallization arranged below can be etched accordingly. The use of photoresist coatings in security element fabrication is e.g. from EP 2 049 345 B1.

The fine structuring of a metallization can moreover take place by means of a so-called washing process. In WO 99/13157 is a

A washing process in which a carrier film is printed with a high pigment content printing ink in the form of characters, coated with a thin covering layer (for example of aluminum) and then the printing ink together with the cover layer above

Washing with a liquid is removed to produce coating-free areas in the form of the characters.

WO 92/11142 (corresponds to EP 0 516 790) or the German

Priority application DE 4 041 025 discloses heat-activatable inks, for example wax-containing emulsions. at Heating soften these emulsions and thereby reduce the adhesion to the carrier film, so that in these poorly adhering areas, supported by mechanical treatment, such. As ultrasound, brushing or rubbing, both the softened ink and the overlying layers can be removed. In addition, as activatable inks with foaming additives, such as are customary in the production of foams disclosed. These blowing agents split gas under the action of heat and produce foam structures. As a result, the volume of the ink increases, whereby the adhesion to the carrier film is reduced and the layers lying above the ink are arched outwards, so that they have a good effect

Offer a point of attack for a mechanical removal.

WO 97/23357 makes reference to EP 0 516 790 and further discloses activatable inks prepared by treatment with a

suitable solvent activated, i. washed out.

The aforementioned ways of structuring a metallization are complex and often lead to an unsatisfactory line thickness. When printing resist coatings, for example, the minimum line thickness requires relying on the available printing processes. Lineweights below 50 μπι are difficult to implement. The same restriction applies to the printing of washing colors. Fine lines are available based on the exposure of photoresist coatings. This

Process is, however, relatively expensive and expensive.

The present invention has for its object to overcome the disadvantages of the prior art. This object is achieved by the feature combinations defined in the independent claims. Further developments of the invention are

Subject of the dependent claims. Summary of the invention

1. (First aspect of the invention) Method for producing a

Security element for a security paper or a valuable article, in particular a value document, comprising the following steps: a) the provision of a transparent carrier substrate; b) providing an embossing lacquer layer having an embossed structure on the carrier substrate; d) the application of a crack-forming coating on the

Embossing lacquer layer and drying of the crack-forming coating, wherein the coating forms numerous cracks during drying in the form of a dense, coherent network; e) applying a metallization to that obtained in step d)

Carrier substrate; f) removal of the cracked coating with metal optionally present on the coating so that a transparent, conductive coating is present in the area of the removed, cracked coating

Metallization in the form of a dense, coherent network remains on the embossing lacquer layer. The embossing lacquer layer used in step b) can in particular be based on a thermoplastic lacquer or a UV lacquer. The embossed structure is in particular a hologram structure. The application of the crack-forming coating in step d) can be effected, for example, by printing technology, in particular by gravure printing, flexographic printing or by means of an inkjet process.

The step f) of removing the cracked coating with metal which may be present on the coating may e.g. by washing with a suitable solvent. Alternatively, the removal step may be accomplished by means of a separately provided adhesive layer device, the device being attached to the removed, cracked, adhesive layer

Coating the security element substrate fixed and after fixing together with the cracked coating of

Security element substrate is removed.

2. (Preferred embodiment) The method according to paragraph 1, wherein either between steps b) and d), or between steps d) and e), additionally step c) takes place, namely the application of a washing ink on the embossing lacquer layer in the first, a first motif forming areas; in step d) the crack-forming coating is applied in second areas forming a second motif, wherein the second areas are selected independently of the first areas, so that optionally provided with wash ink first areas are at least partially coated with crack-forming coating; and after step e) of applying the metallization, step f) is carried out so as to remove the metal-coated wash paint present in the first regions on the one hand and the optionally metal-bearing, cracked coating present in the second regions on the other hand, so that the resulting carrier substrate is such that:

- In the first, a first motif forming areas has no metallization;

- In the second, a second motif-forming areas outside optionally existing first areas has a transparent, conductive metallization in the form of a dense, coherent network;

in the regions which do not belong to the first regions forming a first motif and the second regions forming a second motif comprise an opaque or continuous conductive metallization. The above term "opaque or continuous metallization" is to be understood as meaning a full-surface or continuous metal layer, which in particular has a uniform layer thickness.

3. (Preferred embodiment) Method according to paragraph 1 or 2, comprising in addition: g) the application of a resist coating above the obtained metallization in third areas forming a third motif; h) the removal of the metallization, which is not protected by resist, so that the resist-protected areas remain in the form of a third motif on the embossing lacquer layer. 4. (Preferred embodiment) Method according to paragraph 3, additionally comprising: i) providing and planarizing the carrier substrate obtained in step h) with a protective lacquer having the same refractive index as the resist lacquer.

5. (Second aspect of the invention) Security elements for a

Security paper or a valuable item, in particular a

A value document obtainable by the method according to any one of paragraphs 1 to 4.

6. (Third aspect of the invention) Security paper or document of value comprising the security element according to paragraph 5. Detailed description of the invention

The present invention is based on the idea of the known in the field of semiconductor manufacturing lift-off method for the

Security element production. The structuring of a soluble coating in the lift-off process usually takes place by exposing the soluble coating in regions and then structuring it in a development step. The literature has recently described a method for the fine structuring of evaporated material: Document D1: KDM Rao, C. Hunger, R. Gupta, GU Kulkarni, M.

Thelakkat: "A cracked polymer templated metal network as a transparent conducting electrode for ITO-free organic solar cells", Phys. Chem. Chem. Phys., 2014, Volume 16, pages 15107-15110.

Kiruthika, R. Gupta, KDM Rao, S. Chakraborty, N. Padmavathy, GU Kulkarni: "Large area solution processed transparent conducting electrode based on highly interconnected Cu wire network", J. Mater. Chem. 2014, Volume 2, pages 2089-2094.

According to the above literature, a coating is initially applied to a film, which forms numerous cracks during drying. These cracks form a dense, coherent network. Upon subsequent vapor deposition of a material, the material is deposited both on (i.e., above) the coating and in the cracks. When removing the coating, e.g. Washing with suitable solvents also removes the material deposited above the coating. All that remains is the vapor-deposited material present in the crack lines.

The above method is described in the literature D1 and D2 in connection with the production of electric heating elements and transparent electrodes for solar cells. In accordance with the present invention, the production of a dense, contiguous metallic mesh described in the literature D1 and D2 is transferred to the field of security element fabrication. According to the invention, the crack-forming coating used is preferably a dispersion, more preferably a colloidal dispersion.

Particularly suitable are e.g. Dispersions of SiCh nanoparticles or of acrylic resin nanoparticles, as described on page 2090 in document D2. In addition, the crack-forming coating may be based on a polymer in solution. The polymer solution is applied to the substrate, e.g. by imprinting, so that a thin polymer film is produced. The thin polymer film cracks during drying.

The crack formation depends on the choice of the raw materials and the choice of the substrate, the thickness of the crack-forming coating and the drying parameters. They are at the end of the

Manufacturing method achievable line weights, e.g. in the case of silver in the range of 1 μπι to 50 μπι, the lines are usually so fine that they are recognizable as lines only when using a magnifying glass. In the area, the human eye does not dissolve the individual lines, but one recognizes both in reflected light (or reflection) and in transmitted light (or light).

Transmission) a difference compared to the untreated or bare film. Since the fine lines form an irregular, continuous network, unwanted diffraction effects do not occur. By varying the island size and the crack width, the reflectance and the light transmittance, respectively, can be adjusted appropriately. In addition, the electrical conductivity can be regulated.

Compared to a conventional, full-surface and very thin

Metal layer (hereinafter also called "semitransparent metallization"), which has a constant optical reflection and transmission, is the security element according to the invention in terms of the essential higher chemical resistance pronouncedly advantageous. In the metal lines, the metal is in the "normal" layer thickness, while a conventional semitransparent metallization is very thin and therefore susceptible to corrosion, especially in the case of Al and Cu.

The metallization according to the invention in the form of a dense, coherent network shows an electrical conductivity and an optical transmission, which is comparable to a full-surface ITO layer. The fine metallic lines can be used with advantage to provide a "transparent" hologram and other security elements based on embossed structures with electrical conductivity, whereby the fine metallic lines can be used in combination with conventional ones

Embossing lacquers, customary primer compositions and customary

Heat sealing lacquers are used and act as a reflector. The fine metallic lines can also be used in combination with transparent holograms that rely on a refractive index jump between the embossing lacquer and the coating following the embossing lacquer. According to a first preferred embodiment for producing a security element, a substrate (in particular transparent), such as a film, for example, is applied with an embossing lacquer layer which is provided with a (hologram) embossing. The embossing lacquer layer is coated over its entire area with the crack-forming coating. The crack-forming coating is then dried. This form fine

Cracks. Metal is vapor-deposited on the substrate treated in this way (alternatively, the metal can also be applied wet-chemically). The metal is deposited both above the cracked coating, as well as in the cracks. The cracked coating is then removed, along with the metal deposited above the coating. Removal may be accomplished, for example, by washing with a suitable solvent ("Alternative 1") Alternatively, removal may be accomplished by means of a separately provided adhesive layer device, the device being affixed to the torn, peeled, adhesive layer

Substrate ("Alternative 2") is removed after removal of the cracked coating

Embossing lacquer layer and the metallic network structure provided

Security element optionally with a conventional primer composition or with a layer whose refractive index differs significantly from the refractive index of the embossing lacquer layer, overcoated. An overcoating with a metal that has a different color than the metal of the metallic network structure could also take place. Of the

Observer would see a mixed color in this case. In the course of further processing of the security element, further primer layers and / or heat sealing lacquer layers can be used. Also other optical effects, e.g. Fluorescence, are easily possible by applying additional effect layers, as the used

Reflector, i. the metallic network structure is present only over part of the area.

The process for removing the cracked coating according to the above "Alternative 1" is advantageously carried out by dissolving with a suitable solvent The choice of solvent is suitably made in accordance with the coating Typically, the following solvents can be used: methyl acetate, ethyl acetate, Propyl acetate, butyl acetate, methoxypropyl acetate, acetone, Methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, methylene chloride, chloroform, toluene, xylene, methanol, ethanol, 2-propanol. Furthermore, acetals or mixtures of the abovementioned

Solvent can be used. Alternatively, a detachment of the crack-forming coating by infiltration can take place. In this case, in addition to the solvents mentioned also aqueous solutions, mixtures of solvents and water, optionally with surfactants, possibly with defoamers and other additives are used. The

Replacement or dissolution of the cracked coating can also be supported by spray nozzles or mechanically by brushing, rolling or by felts.

The method for removing the cracked coating according to the above "Alternative 2" is peeling in the form of a kind

Lamination (or bonding) and separation winding. Thereby, a second, separate substrate, e.g. a film, with a large area under the

Laminating conditions (or adhesive conditions) adhesive coating coated. By the term "large area" it is meant that the extent is at least as large as the area of the crack-forming layer to be detached.The layer thickness of the adhesive coating is, for example, after a physical drying, for example, 0.4 μπ \ to 4 μιη the material (ie the metal) lying on the crack-forming coating bonds with the adhesive coating

Coating serves as a spacer to the film and the material deposited directly on the film (i.e., metal). Depending on the choice of crack-forming

Coating occurs in the subsequent separation winding either to peel off the metal from the crack-forming coating or to completely peel off the crack-forming coating. On the adhesively coated film (ie the second, separate substrate) is located after the Separating winding at least the negative image of the metal. The film can be further processed if necessary. The foil is metallic with very high reflection (eg higher than 85%), but not electrically conductive. It is therefore preferred to further process the film of the security element which originally carried the crack-forming coating.

A combination of the above-mentioned manufacturing method according to the first preferred embodiment with the methods known in the art for producing a negative writing (eg, the above-mentioned washing method or resist method using resist coatings) is easily possible, see the second and third preferred embodiments described below for producing a security element.

According to a second preferred embodiment is on a

(In particular, transparent) substrate, such as a film, which may optionally have an embossing lacquer layer or embossed structures, printed in a first step, a wash color as a motif. Subsequently, further motif elements are printed by means of the crack-forming lacquer, e.g. Lines within areas that are not covered with wash paint (the order can also be reversed, that is, first

Applying the crack-forming paint and then applying the wash paint). Thereafter, the metallizing step, e.g. by

Vapor deposition of metal. After removal of the wash paint and the crack-forming coating, a security element is obtained having the following ranges: first areas which form a "true" negative writing (ie recesses or areas without any metal) without electrical conductivity; second, metallic areas with electrical conductivity; third areas, which form a negative writing or a transparent area with electrical conductivity, generated by a metallic network structure. Metallic lines of the third areas can serve as an optical, recognizable with the magnifying glass security feature.

According to a third preferred embodiment is on a

(In particular, transparent) substrate, such as a film, which may optionally have an embossing lacquer layer or embossed structures printed in a first step as a motif, the crack-forming coating. Thereafter, the surface coating with a metal, e.g. by vapor deposition. The crack-forming coating is then removed, so that one

A security element having the following ranges is obtained: first areas each formed by a bare (i.e., continuous) metal layer; second areas, each formed by a metallic mesh structure with fine, metallic lines. Using a resist varnish, the first and / or second areas can be printed. In one

subsequent etching process is the removal or conversion of the non-resist-protected metal. Also according to this

In the manufacturing process, a security element is obtained having the following ranges: first areas that form a "true" negative writing (ie recesses or areas without any metal), without electrical conductivity, second, metallic areas with electrical conductivity, third areas that have negative writing or form a transparent region with electrical conductivity, generated by a metallic network structure The fine, metallic lines of the third regions can serve as an optical, with the magnifying glass recognizable security feature.

According to the preferred method for producing a security element (see, for example, the above first preferred embodiment), a substrate (in particular a transparent one), such as a film, is used

Embossing lacquer layer applied, which provided with a (hologram) embossing is. The embossing lacquer layer becomes full-surface with the crack-forming

Coating coated. The crack-forming coating is then dried. This forms fine cracks. Without targeted external action, the crack formation occurs at random. The crack formation can be controlled by appropriate measures, so that the formation of cracks in desired

Regions of the crack-forming layer preferably occurs. This can e.g. by suitable structuring of the substrate, e.g. the embossing lacquer layer. This includes the use of embossed structures, the use of embossed structures in conjunction with additives in the embossing lacquer, which have an influence on the surface energy.

Basic notes:

The metallization of the security element according to the invention can be based on a single metal. As a metal, e.g. Aluminum, silver, copper, nickel, iron, chromium, cobalt, gold, titanium, tin, zinc or an alloy of one or more of the foregoing elements (e.g., an iron-silicon alloy). In addition, the metallization may be based on a multilayer metallization, e.g. by

successive vapor deposition is available. An advantageous multilayer metallization is e.g. a Cr layer followed by an Al layer. The adhesion of the Al layer to the layer structure is improved by the Cr layer. Furthermore, the electrical conductivity of the inventive

Metallization in the form of a dense, coherent network can be improved by an additional coating with an electrically conductive polymer. As an electrically conductive polymer, for example, an electrically conductive thiophene-based polymer such as poly-3,4- ethylenedioxythiophene (PEDOT or PEDT). Alternatively you can

inorganic, transparent and conductive layers, e.g. Metal oxides such as titanium dioxide, indium tin oxide or fluorine-tin oxide can be applied. These additional layers can also serve to improve the electrical properties of the metallization according to the invention, such as

Work function, controlled to modify.

In the manufacturing method according to the invention, metal is deposited within the cracks of the cracked coating, metal may also be deposited above the cracked coating. The cracked coating is then removed, along with any metal deposited above the coating. The step of removing may e.g. by washing with a suitable solvent ("Alternative 1") Alternatively, the removal step may be accomplished by means of a separately provided adhesive layer

Device, wherein the device by means of the adhesive layer on the to be removed, cracked coating of the

Security element substrate is fixed and withdrawn after fixing together with the cracked coating from the security element substrate ("Alternative 2").

In the production method according to the invention, the carrier substrate can be provided in certain areas with a crack-forming coating. In addition, the carrier substrate can additionally be provided with a transparent lacquer in certain regions (which are arranged, in particular, outside the regions of the tear-forming coating) which forms no cracks. After the step of applying a

Metallization takes place the step of removing the metallization, which is located above the cracked coating on the one hand, and above the transparent varnish is on the other. This step is carried out by means of the above-described, separately provided, adhesive layered device (see the above "Alternative 2") In this way, a security element can be produced which has no metallization in the region of the transparent lacquer.

The obtained in the production process of the invention

Transparent, conductive metallization in the form of a dense, coherent network can be subsequently removed by means of laser radiation in certain areas (so-called laser demetallization). In this way, a structuring of the transparent, conductive

Metallization possible, i. vacancies or demetallized areas can be provided. Likewise, the opaque or continuous, conductive metallization obtained in the manufacturing method according to the invention can be subsequently removed by laser radiation in certain areas. In this way structuring of the opaque, conductive metallization is possible, i. it can

Blank spaces or demetallisierte areas are provided. Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, in the representation of which a representation true to scale and proportion has been dispensed with in order to increase the clarity. Show it:

Figure 1 is a document of value with a strip-shaped

Security element according to the present invention; Figure 2 shows the security element of Figure 1 in magnification in plan view;

Figure 3 shows the security element of Figure 2 in cross-sectional view;

Figure 4 shows the individual manufacturing steps for obtaining a transparent, conductive metallization in the form of a dense, coherent network; Figure 5 is a transparent, conductive metallization in the form of a dense, coherent network

schematically in plan view in an enlarged view;

Figures 6-8 the preparation of a security element according to the second preferred embodiment;

Figures 9-13 the preparation of a security element according to the third preferred embodiment; Figure 14 Example of the targeted control of crack formation;

Figures 15-18 the preparation of a security element, wherein the

Detachment of the cracked coating by separation winding takes place;

FIGS. 19-21 show a variant of that in FIGS. 15, 16 and 18

shown manufacturing method, wherein additionally a transparent lacquer is used. 1 shows a value document 1, in the present example a banknote with the denomination "50." The banknote 1 is provided on the front side with a strip-shaped security element 2

Security element 2 has embossed structures 3, e.g.

Hologram embossing.

Figure 2 shows the designated in Figure 1 with the letter "A" area of the security element 2 in magnification.

FIG. 3 shows the security element 2 of FIG. 2 in a cross-sectional view along the line A-A '. The security element 2 comprises a transparent carrier substrate 4, e.g. a polyethylene terephthalate or other plastic based film. The carrier substrate 4 is provided with a

Embossing lacquer layer 5 provided. In area 3, the embossing lacquer layer 5 has an embossing structure, such as e.g. a hologram embossing, on. The embossing lacquer layer 5 is fully coated on its upper side with a transparent, conductive

Metallization 6 provided in the form of a dense, coherent network.

Figure 4 illustrates the individual manufacturing steps for obtaining a transparent, conductive metallization in the form of a

dense, coherent network. The carrier substrate 4 (the embossing lacquer layer 5 shown in FIG. 3 has been omitted for the sake of simplicity) is crack-formed in a first step

Provided coating 7. The crack-forming coating 7 is based, for example, on dispersions of SiCh nanoparticles or of acrylic resin nanoparticles. The application of the crack-forming coating 7 is preferably carried out by printing technology, for example by gravure printing, flexographic printing or by means of an inkjet coating. Process. The crack-forming coating 7 forms numerous cracks 8 during drying in the form of a dense, coherent network. In a second step, the application of a

Metallization 9. The metallization 9 is shown schematically in FIG. 4 in the form of individual black dots. The metallization 9 is reflected on the one hand above the cracked coating 7 and on the other hand, within the cracks 8 of the coating. 7

deposited. In a third step, the cracked coating 7 is removed, including the metallization 9 present above the coating 7. On the carrier substrate 4 remains a transparent, conductive metallization 10 in the form of a dense, coherent network.

FIG. 5 shows the transparent, conductive metallization 10 in the form of a dense, coherent network, schematically in plan view on an enlarged scale.

Figures 6 to 8 illustrate the manufacture of a security element according to the second preferred embodiment described above.

According to FIG. 6, a carrier substrate 4 is provided with an embossing lacquer layer 5. The embossing lacquer layer 5 is printed with wash ink 11 in the form of a motif. Subsequently, 7 further motif elements are printed using a crack-forming lacquer. The crack-forming coating 7 forms numerous cracks 8 during drying in the form of a dense,

connected network.

Thereafter, according to the figure 7, the step of metallizing, for example by vapor deposition of metal 9. The metallization 9 is reflected on the one hand above the cracked coating 7 and above the wash paint 11 and, on the other hand, is deposited within the cracks 8 of the coating 7. Figure 8 shows the obtained security element after removing the wash paint 11 and the cracked coating 7 with a suitable solvent. You get a security element with the following areas:

first regions 12 forming a "true" negative writing (i.e., voids without any metal), without electrical conductivity;

- Second, metallic regions 13 with electrical conductivity;

third regions 14, which form a negative writing or a transparent region with electrical conductivity, generated by a metallic

Network structure.

The fine, metallic lines of the third regions 14 can serve as optical security feature recognizable by the magnifying glass.

Figures 9 to 13 illustrate the manufacture of a security element according to the third preferred embodiment described above.

According to FIG. 9, a carrier substrate 4 is provided with an embossing lacquer layer 5. The embossing lacquer layer 5 is printed with a tear-forming coating 7 in the form of a motif. The crack-forming coating 7 forms numerous cracks 8 during drying in the form of a dense,

connected network. Thereafter, the step of

Metallizing ens, for example by vapor deposition of metal 9. The metallization 9 strikes on the one hand above the cracked coating. 7 and above the embossing lacquer layer 5, and on the other hand, it is deposited inside the cracks 8 of the coating 7.

Figure 10 shows the obtained security element after removal of the cracked coating 7 with a suitable solvent. You get a security element with the following areas:

first regions 15, each formed by a bare (i.e., continuous) metal layer;

second regions 16 each formed by a metallic mesh structure with fine metallic lines.

Thereafter, as shown in FIG 11, the printing with resist 17 in certain motif areas. In a subsequent etching process, the non-resist metal 9 is removed or converted (see FIG. 12). Also in accordance with this manufacturing method, a security element having the following ranges is obtained:

- Second, metallic regions 13 with electrical conductivity;

Network structure.

The fine, metallic lines of the third regions 14 can serve as optical security feature recognizable by the magnifying glass. According to FIG. 13, the obtained security element structure can additionally be leveled with a protective lacquer 18.

According to the processes for producing a security element shown in FIGS. 4 and 6-13, the formation of the individual, fine cracks during drying of the crack-forming coating takes place without targeted external action and thus more by chance. As FIG. 14 shows, the

Training individual cracks 8 are controlled by appropriate measures. In the case of a suitable structuring of the embossing lacquer layer 5, for example, the formation of cracks in desired regions preferably occurs.

Figures 15 to 18 illustrate the manufacture of a

Security elements, removing the torn

Coating not mithilf e of a solvent, but by a detachment in the form of a kind of lamination (or bonding) and separation winding takes place (see the "alternative 2" described above).

According to FIG. 15, a carrier substrate 4 (which may be provided with an embossing lacquer layer, not shown) is printed with a tear-forming coating 7 in the form of a motif. The crack-forming coating 7 forms numerous cracks 8 during drying in the form of a dense,

connected network. Thereafter, the step of

Metallization, for example by vapor deposition of metal 9. The metallization 9 is deposited on the one hand above the cracked coating 7 and above the carrier substrate 4 and on the other hand is deposited within the cracks 8 of the coating 7. According to FIG. 16, the security element precursor shown in FIG. 15 is glued to a separate device 19 which has a substrate 20 (eg a foil) provided with an adhesive coating 21. In this case, the metal provided on the cracked coating 7 combines with the adhesive coating 21. The coating 7 provided with cracks serves as a spacer for the carrier substrate 4 and the metal deposited directly on the carrier substrate 4.

Depending on the choice of the crack-forming coating 7, it comes in the

subsequent separation winding either for stripping the metal from the cracked coating 7 (see Figure 18) or to

completely peeling off the cracked coating 7 (see Figure 17). Figures 19-21 show a variant of the manufacturing method shown in Figures 15, 16 and 18, wherein in addition a transparent paint is used.

According to FIG. 19, a carrier substrate 4 (which may be provided with an embossing lacquer layer, not shown) is printed with a tear-forming coating 7 in the form of a motif. The crack-forming coating 7 forms numerous cracks 8 during drying in the form of a dense,

connected network. In addition, the carrier substrate 4 (which may be provided with an embossing lacquer layer, not shown) is provided with areas 22 of a transparent lacquer. The transparent paint 22 forms no cracks. This is followed by the step of metallizing, for example by vapor deposition of metal 9. The metallization 9 beats on the one hand above the cracked coating 7, above the transparent varnish 22 and above the carrier substrate 4 and on the other hand is deposited within the cracks 8 of the coating 7.

Referring now to Figure 20, the security element precursor shown in Figure 19 is adhered to a separate device 19 having a substrate 20 (e.g., a film) provided with an adhesive coating 21. In the process, the coating 7 provided on the cracks and the metal lying on the transparent lacquer 22 combine with the adhesive coating 21.

In the subsequent separation winding, the metal is peeled off from the cracked coating 7 and from the transparent lacquer 22 (see FIG. 21). The security element obtained in this way has no metallization in the region 22 of the transparent lacquer.

Of course, the transparent paint 22 with respect to his

representational nature be chosen so that it at the

Separation winding either for stripping the metal from the transparent paint 22 comes (see Figure 21) or to completely peel off the transparent varnish 22 (similar to that shown in Figure 17).

Claims

Patent claims

1. A method for producing a security element for a

Security paper or a valuable item, in particular a

Document of value, comprising the following steps: a) the provision of a transparent carrier substrate; b) providing an embossing lacquer layer having an embossed structure on the carrier substrate; d) the application of a crack-forming coating on the

Embossing lacquer layer and drying of the crack-forming coating, wherein the coating forms numerous cracks during drying in the form of a dense, coherent network; e) applying a metallization to the carrier substrate obtained in step d); f) removal of the cracked coating with metal optionally present on the coating so that a transparent, conductive coating is present in the area of the removed, cracked coating

Metallization in the form of a dense, coherent network remains on the embossing lacquer layer.

2. The method of claim 1, wherein either between steps b) and d), or between steps d) and e), additionally the step c) takes place, namely the application of a Wash paint on the embossing lacquer layer in first areas forming a first motif; in step d) the crack-forming coating is applied in second areas forming a second motif, wherein the second areas are selected independently of the first areas, so that

optionally provided with wash ink first areas are at least partially coated with crack-forming coating; and after step e) of applying the metallization, step f) is carried out so as to remove the metal-coated wash paint present in the first regions on the one hand and the optionally metal-bearing, cracked coating present in the second regions on the other hand, so that the resulting carrier substrate is such that:

- In the first, a first motif forming areas has no metallization;

in the areas which do not belong to the first, a first motif forming areas and the second, second motif forming areas include an opaque, conductive metallization.

The method of claim 1 or 2, further comprising: g) applying a resist over the obtained metallization in third areas forming a third motif; h) the removal of the metallization, which is not protected by resist, so that the resist-protected areas remain in the form of a third motif on the embossing lacquer layer.

4. The method of claim 3, further comprising: i) providing and planarizing the carrier substrate obtained in step h) with a resist having the same refractive index as the resist.

5. Security element for a security paper or a valuable article, in particular a value document, obtainable by the method according to one of claims 1 to 4.

6. security paper or document of value, comprising the security element according to claim 5.