EP2498999B1 - Production of a security element provided with colored micro-depressions - Google Patents

Description

The invention relates to methods for producing a microwaved security element for security papers, documents of value or the like, wherein the microwells are colored with a specific color and the method comprises the steps of: coating an upper side of a carrier with an embossable lacquer, forming microwells in the lacquer in an area of the varnish-coated top, and applying the specified color to the top and scrubbing excess paint so that the color remains in the microwells.

Items to be protected are often provided with a security element that allows verification of the authenticity of the item and at the same time serves as protection against unauthorized reproduction.

Items to be protected include, for example, security papers, identity and value documents (such as banknotes, chip cards, passports, identification cards, identity cards, stocks, bonds, certificates, vouchers, checks, tickets, credit cards, health cards, etc.) as well as product security elements such as security items. Labels, seals, packaging.

The security against forgery and visibility of a security element is particularly great when the security element shows colored motifs or information.

The DE 102007055112 A1 and the DE 102008029158A1 disclose a method according to the preamble of claim 1, or the use of a so-called wash color for structuring a layer.

A well-known for banknotes security element is the so-called security thread and the so-called security strip. This is usually a 0.8 to 2 mm wide strip, which is introduced into the paper during banknote production or woven as a window security thread so that it is partially open, or is glued to the paper. For additional copy protection, this element is usually provided with optical properties. The combination of microstructure elements with overlying microlenses, which increase the microstructure elements, has proved to be particularly tamper-proof. In this case, in particular, the so-called moiré effect can be used. Such security elements are also referred to as "Moiré Magnifier". An exemplary description of such a security element can be found in the WO 2008/031170 A1 which proposes to produce the microlenses and microstructures by an embossable lacquer.

It has been shown that colored structures, in particular when using moiré magnifiers, ensure further protection against counterfeiting. It would therefore be conceivable to color the microstructure elements of Moire Magnifier security elements. However, the problem would arise that color residues normally remain outside of the microstructure elements as so-called toning, whereby the contrast difference between the color-filled microstructure elements, which are usually formed as depressions, and the other surface would be reduced.

The invention has for its object to provide a method for producing a colored with a particular color microwells security element for security papers, documents of value or the like in which the colored microwells have a high color contrast to the environment.

This object is achieved by a method according to claim 1.

The invention achieves a partial coloration of microwells without leaving a troublesome hue outside the microwells.

Essential for this is the presence of a protective layer in the areas where no microwells are to be dyed with the particular color at the time of the paint job. Removing this protective layer after dyeing, at the same time becomes an otherwise when paint unavoidable coloration, ie color residues outside the microwells to be colored removed. Thus, the color fill is limited to the microwells that are to be colored with the particular color. A good contrast is the result.

This contrast is particularly advantageous when using the microwells in conjunction with a Moire Magnifier security element, since its optical effect is particularly affected by toning shadows outside the microwells. However, insofar as the invention is described here in connection with Moiré-Magnifiern, this is only to be understood as an example. The method according to the invention can also be applied to any other colored microwells in all variants, "microwells" meaning depressions which, based on a process of the application of paint and optionally the removal of excess color, e.g. By scribing, have a small depth, so that after the paint application or, where appropriate, the removal of excess color, the color remains in the wells. Microwells in the context of this invention are in particular 1.5 to 3.5 microns, more preferably 2.0 to 3.0 microns deep.

The method according to the invention makes it possible, in particular, to mold hologram structures into the layer, which can be formed as a stamping layer and, in particular, as a lacquer and into which the microwells are formed. Then microwells and hologram structures can be molded in an embossing process at the same time, which of course is advantageous from a production engineering point of view. These hologram structures are optionally metallized. Subsequently, they are suitably protected so that the hologram structures are not colored become. This protection can be achieved by the provided for color avoidance protective layer.

Metallization of the coated surface is advantageous for embodiments in which hologram structures are applied, since a hologram structure usually has to be metallized. It is therefore provided in a preferred development that hologram structures are also formed in the embossed layer, wherein these hologram structures are metallized and then provided with the protective layer, and that outside of the hologram structures, the top is provided with a protective coating and not provided with the protective coating areas the hologram structures are demetallized by etching.

For the desired contrast enhancement, it is sufficient for the protective layer to leave open a window with the microwells, without covering the elevations between the microwells with the protective layer.

Depending on the fineness, ie distances between the microwells, but it may also be appropriate to release only the microwells and otherwise completely cover the top with the protective layer, ie also the elevations between the microwells.

The security element produced in this way can be further processed by conventional methods; so it is possible to provide on the top or bottom of the carrier an adhesive layer or a primer pressure.

The application of paint on the surface can be done in various ways. Thus, it is possible to apply color to the paint on the top surface color and then remove excess color outside the microwells, z. B. to roll off. Also, the color can be applied from the outset only in the areas in which microwells (and consequently also elevations, in particular micro-increases) are provided. For this comes z. As the so-called flexographic printing or the kiss-print method in question, as mentioned in H. Kipphan (ed.), Handbook of print media, Springer Verlag, 2000, p 409. All the disclosure of this standard work of the printing technique is fully incorporated in the present description with respect to the kiss-print method.

It is a significant advantage of the invention that the inking process no longer needs to be optimized to apply color as exclusively as possible to the microwells to be inked. The structured protective layer used in the method according to the invention automatically ensures that any toning shadows that remain in a paint application method which may be insufficient under previous aspects are removed again. The invention therefore opens up a much wider range of inking processes than in the prior art Technology was possible. A corresponding cost reduction in the production is the positive result.

For the protective layer, it is essential that it securely adheres to the top during the paint application process, and that it can nevertheless be removed without residue after the paint application. For this purpose, known protective or resist coatings are eligible. Also, a washing method can be used, as for example in the EP 1520929 A1 (there with further evidence) is described.

The method according to the invention also permits the generation of multicolored microstructures in a further development by repeating the corresponding steps b2) to d) for a further different color, the protective layers being applied to different areas preferably not overlapping in the region of the microwells during the individual passes become.

Fig. 1

eine Draufsicht einer Banknote mit einem Sicherheitselement 1,

Fig. 2 bis 10

Schnitte durch das Sicherheitselement 1 längs der Linie A-A der Fig. 1, wobei die einzelnen Schritte aufeinanderfolgende Stufen des erfindungsgemäßen Herstellverfahrens bis zum Abschluss in Fig.10 zeigen.

The invention will be explained in more detail by way of example with reference to the accompanying drawings, which also disclose features essential to the invention. Show it:

Fig. 1

a top view of a banknote with a security element 1,

Fig. 2 to 10

Sections through the security element 1 along the line AA Fig. 1 , wherein the individual steps successive stages of the manufacturing process according to the invention until completion in Figure 10 demonstrate.

All figures are not shown to scale for better presentation, especially as regards layer thicknesses. Furthermore, some hatching is not shown in order to represent the structure of the corresponding security element 1 more clearly. Incidentally, elements which in different embodiments functionally and / or structurally resemble or correspond bear the same reference numbers in all figures in order to avoid description repetitions. In the following description of interfaces is referred to as the front of the security element in the representations above page. The back is accordingly the bottom side. This convention is merely for ease of description and is not intended to be limiting as to the construction and / or application of the security element.

At the in Fig. 1 In the embodiment shown, a security element 1 is integrated in a banknote 2. The security element 1 provided on the banknote 2 can also be part of a security thread 3 of the banknote which, as in FIG Fig. 1 illustrated by way of example, is usually woven into the paper of the banknote 2 in such a way that it is partly on the front (the in Fig. 1 visible side) and partially visible on the back of the banknote is. It is also possible to arrange the security element 1 at least partially over a window provided in the banknote 2. Of course, these possibilities are only examples of the use of the security element 1 described below, which of course can also be used in other ways for copying or imitation protection of a protected object.

Fig. 2 shows a sectional view through the security element 1 of Fig. 1 at the beginning of its manufacture according to the embodiment. To produce a carrier 4, which may be formed, for example, as a film, provided on its upper side 5 with an embossable layer, which is an embossing lacquer layer in the described embodiment, for example, a UV-curing embossing lacquer. Of course, the coating can also be provided on an underside 6 of the film 4. However, this description is limited to the explanation of the layer structure on the top 5 for reasons of simplicity.

In the embossing lacquer layer microstructure elements 8 and at least one hologram 9 are molded, for example by a known embossing process, as in the already mentioned WO 2008/031170 A1 is mentioned. Consequently, an embossed layer 7 is obtained on the upper side.

Thus, after the in Fig. 2 shown state is achieved, a full-surface metallization of the surface is made by applying an aluminum layer 10, for example, by evaporation. The application of the aluminum layer 10 takes place in such a way that the microstructure elements 8 and the hologram structure 9 are retained on the upper side of the aluminum layer 10. This state presents Fig. 3 Of course that is an aluminum layer 10 is just one example of one of the many possible metallizations.

Now, a protective coating 11 is applied to the areas that should not be colored. The protective lacquer 11 thus leaves a window 12 above the microstructure 8 free. The protective lacquer may be a resist lacquer, as known in printing or semiconductor technology. Such a resist coating is usually first applied over the whole area and then patterned photographically by means of a suitable exposure so that after development only the exposed (in the case of a positive resist) or unexposed areas (in the case of a negative resist) remain free. The manner in which or how the resist 11 is applied is not relevant to the invention. So z. B. also a wash color can be used. It is essential, however, that the window 12 is formed in the protective lacquer 11, which leaves free those regions of the microstructure elements 8 which are to be colored. If the microstructure is to be provided with different colors, you will not get the in Fig. 4 strive for the state in which the window 12 leaves the microstructure completely free, but for each color in different passes the window 12 set so that the areas of the microstructure to be inked with the respective color remain free and the non-colorable areas of the resist 11 are covered.

Next, the aluminum layer 10 in the region of the window 12 is removed by means of an etching step, so that the microstructure in the embossing lacquer layer 7 is exposed. This condition is in Fig. 5 to recognize.

Then, as the sectional view of Fig. 6 shows, all over a color layer 14 applied. This will then be possible again This is done, for example, by doctoring, so that the ink layer 15 remains, which, however, usually inevitably includes a toning layer 16 also in the areas under which no microstructures 8 are located. The result is the state according to Fig. 7 , This can also be achieved by a so-called kiss-print process, which is an alternative to full application and doctoring.

to Fig. 7 It should also be noted that, as already mentioned, the layer thicknesses are not to scale. The above the microstructure in Fig. 7 recognizable volume with the remaining ink layer 15 is greatly enlarged by the non-scale representation. In fact, the volume over the microstructure is negligible against the volume of the wells of the microstructure.

Now, in a next step, the resist 11 is removed. Thus, the unwanted Tonungsschicht 16 is automatically lifted and the surface of the aluminum layer 10 is free again.

Of course, in constructions which work without a hologram structure 9, the aluminum layer 10 can be completely eliminated, so that the protective lacquer 11 is applied directly to the embossed layer 7 (optionally with the interposition of one or more suitable separating layers). The manufacturing process would then be completed after the removal of the protective coating 11.

In the embodiment shown in the figures, however, the hologram structure 9 is introduced into the embossing lacquer layer together with the microstructure 8 and the aluminum layer 10 is laid over it. In order to demetallize these in a suitably structured manner in order to achieve the desired hologram effect, at least in the Area of the hologram structure 9, a second resist 18 applied and desirably structured so that windows 19 are formed at which the metallization, ie in the exemplary embodiment, the aluminum layer 10, to be removed again ( Fig. 9 ). This removal of the aluminum layer 10 takes place, for example, by means of a suitable etching. After subsequent removal of the second protective layer 18, there is thus a structured demetallization 20, as is needed for a hologram of good effect. As a result, you get the in Fig. 10 schematically illustrated section with a microstructure 8, the recesses are provided with a color layer 15, and a demetallisierte desired hologram structure. 9

In the embodiment, the protective layer 11 covers the top 5 except for the window 12 containing the area of the microstructure elements 8 to be colored. Within the microstructure elements 8 is no protective layer.

LIST OF REFERENCE NUMBERS

1

security element

2

bill

3

security thread

4

carrier

5

top

6

bottom

7

embossed layer

8th

microstructure

9

hologram structure

10

aluminum layer

11

protective lacquer

12

window

14

coat of paint

15

Color coat after doctoring

16

Tonungsschicht

17

Colored microstructure

18

2. Protective varnish

19

window

20

demetallization

Claims (10)

1. A method for manufacturing a security element supplied with microdepressions (8) that are dyed with a certain ink for security papers, value documents or the like, wherein the method has the following steps of:

   a) coating an upper side (5) of a carrier (4) with an embossable layer (7),

   b1) forming microdepressions (8) in the embossable layer (7) for producing an embossed layer (7), subsequently

   b2) applying a protective layer (11; 10) to the layer (7), wherein the protective layer (11; 10) is so structured that it does not cover the microdepressions (8) that are to be dyed with the certain ink, subsequently

   c) applying the certain ink to the upper side (5), so that the ink (14) remains in the microdepressions (8), subsequently

   d) removing the structured protective layer (11; 10) and thereby a color toning (16) present outside the microdepressions, wherein an ink filling is limited to the microdepressions (8),

   characterized in that
   in step b2) a structured protective layer (11) is applied that has a window (12) in which the microdepressions are disposed,
   before step b2) the coated upper side (5) is metalized (10),
   in step b2) the structured protective layer (11) is applied, wherein the protective layer (11) is configured such that it protects the metalization from etching, and
   after applying the structured protective layer (11), the metalization (10) that is not protected by the protective layer (11) and is disposed in the window (12) is etched in order to demetalize the microdepressions (8).
2. The method according to claim 1, characterized in that
   in step b1) or before step b2) also hologram structures (9) are formed in the embossable layer (7), wherein these hologram structures (9) are metalized (10) and supplied with the protective layer (11) and that after step d)

   e) outside the hologram structures (7) the upper side (5) is supplied with a protective coating (18) and

   f) regions (19) of the hologram structures (9) that are not supplied with the protective coating (18) are demetalized (19) by means of etching.
3. The method according to any of the above claims, characterized in that the upper side or a lower side (5, 6) of the carrier (4) is supplied with an adhesive layer.
4. The method according to any of the above claims, characterized in that the upper side or a lower side (5, 6) of the carrier (4) is supplied with a primer print.
5. The method according to any of the above claims, characterized in that in step c) for applying ink a kiss print is effected.
6. The method according to any of the claims 1 to 5, characterized in that in step c) for ink application to the upper side, ink (14) is applied areally and excess ink is scraped off.
7. The method according to any of the above claims, characterized in that as protective layer (11) a washing ink or a resist lacquer is utilized.
8. The method according to any of the above claims in connection with claim 5, characterized in that as separating layer (21) a washing ink or a resist lacquer is utilized.
9. The method according to any of the above claims, characterized in that the steps b2) to d) are repeated with a further ink that differs from the certain ink, wherein the protective layer is structured differently in the steps b2).
10. The method according to any of the above claims, characterized in that the microdepressions (8) have a depth of between 1.5 and 3.5 µm.

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