EP3511177B1 - Security element with optically variable embossed structure - Google Patents

Description

The invention relates to a security element made of a substrate with an optically variable structure which has an embossed structure and a coating, the embossed structure and the coating being combined in such a way that at least parts of the coating are completely visible when viewed perpendicularly, but are covered when viewed obliquely, so that when the viewing direction changes, different information becomes visible, the embossed structure consisting of non-linear embossed elements which adjoin one another, with each non-linear embossed element essentially consisting of a flank. The invention also relates to an embossing tool for producing such a security element.

Out EP 3124285 A1 an embossing tool for producing a security element with an optically variable structure is known, the optically variable structure showing a tilting effect when the security element is tilted about an axis. The embossing tool consists of an embossing plate with a surface, the surface of the embossing plate having a plurality of groove-shaped depressions arranged essentially parallel to one another. The channel-shaped depressions each consist of a first and a second flank, which are opposite one another. The first flank of a depression and the second flank of the depression adjacent to this depression converge in the direction of the surface of the embossing plate, the first flank of each channel-shaped depression having a different angle of inclination to the surface of the embossing plate than the corresponding second flank. In each case between the first flank of a depression and the second flank of the one adjacent to this depression In the recess, a flat area is arranged which is aligned essentially parallel to the surface of the embossing plate.

Out WO 2006/018232 A1 A security element with an optically variable structure is known which has an embossed structure and a coating, the embossed structure and the coating being combined in such a way that at least parts of the coating are completely visible when viewed perpendicularly, but are covered when viewed obliquely, so that when there is a change Different information becomes visible depending on the viewing direction. The embossed structure consists of non-linear embossed elements which can in particular be arranged in a grid shape and can have the shape of a tetrahedron, spherical segment, truncated pyramid, truncated cone, cylinder segment, torus, oval, drop or pyramid. Out WO 2013/045054 A1 a security element with an optically variable structure is known which has a plurality of embossed elements, each of the embossed elements consisting of at least two flanks which converge at a specific angle and / or a specific direction. The surface of the embossing elements is reflective. Furthermore, the security element consists of at least two groups of embossed elements, the at least two groups only differing from one another in the angle and / or the direction at which the flanks of the embossed elements converge. Each embossing element of the WO 2013/045054 has a regular hexagonal base.

document U.S. 5,538,753 discloses a security element according to the preamble of claim 1.

The aim of the invention is to prevent the fine, tapered flanks from being rounded off during the complex production of embossing forms and process steps for intaglio printing or gravure printing, and thus the optically variable effect to be generated suffers. Furthermore the aim is to avoid changes in the structures to be depicted or wear and tear of a knife, wiper cylinder, etc. when the embossing forms are subsequently used for longer runs. surrender.

The invention is therefore based on the object of developing a generic security element in such a way that the disadvantages of the prior art are eliminated and the protection against counterfeiting is further increased.

This object is achieved by the features of the independent claims. Developments of the invention are the subject of the dependent claims.

According to the invention, a flat area or a plateau is arranged between adjoining embossing elements, which area is arranged essentially parallel to the surface of the substrate surrounding the embossing element. Essentially parallel here means that the angle between the flat area or plateau and the surface of the substrate surrounding the security element or the embossing tool is preferably 0 ° (exactly parallel) and particularly preferably 0.5 ° to 5 °.

According to a preferred embodiment, the flat area or the plateau is only arranged between two adjacent embossing elements, so that it is only located near the surface of the substrate or the embossing plate. Alternatively, the flat area or the plateau is arranged around the entire embossing element, that is to say runs around the entire embossing element and is therefore not only arranged between two adjacent embossing elements.

• Die Kante zwischen zwei Prägeelementen befindet sich an der Plattenoberfläche oder ist maximal um den Abstand d von der Plattenoberfläche vertieft angeordnet, wobei d < 20 µm, bevorzugt d < 10 µm, besonders bevorzugt d < 5 µm ist, und
• der Winkel α zwischen der Spiegelfläche des Prägeelements und der betreffenden Kante beträgt α < 120°, bevorzugt α < 90° und besonders bevorzugt α < 60°.

According to the invention, in particular, fragile, tall peaks are to be protected from "eroding" or mechanical damage in the various process steps and during the embossing process. It is therefore particularly advantageous if a flat area or a plateau is introduced at the edges between two adjacent embossing elements if the following two conditions are met:

• The edge between two embossed elements is located on the plate surface or is recessed by a maximum of the distance d from the plate surface, with d <20 μm, preferably d <10 μm, particularly preferably d <5 μm, and
• the angle α between the mirror surface of the embossing element and the relevant edge is α <120 °, preferably α <90 ° and particularly preferably α <60 °.

The corresponding plateau runs where the two preceding conditions are met in the predominant part of the edge of the embossing element, parallel to the plate surface and in each case in the depth at which the two embossing element surfaces meet at the edge. If there is a jump in depth between the two embossed element surfaces at the edge, the depth of that embossed element surface is used for the plateau whose distance from the surface of the plate is smaller.

The invention also relates to an embossing tool for producing such a security element. The embossing tool is preferably an embossing cylinder, an embossing die or a printing plate, in particular a intaglio printing plate, the elements to be embossed being designed as an engraving or an elevation in the surface of the embossing tool.

The flat area or the plateau has the advantage over pointed structures that it is less sensitive to erosion by processing tools with which the embossing tool is engraved, in particular a (wide) laser beam. Furthermore, plateaus are less sensitive to deburring, cleaning and polishing of the embossing tool, for example by means of a doctor blade, polishing agent, abrasive, water jet cleaning, etching process or by means of rotating brushes, and thus show less plate wear. Furthermore, a downstream chrome plating of the embossing tool has better adhesion to the carrier material, which also reduces mechanical wear. In addition, the stamping tool itself, when used as intended, is more stable against wear and tear due to process-related influences.

The edge of a flat area or plateau can run towards the flank of an adjacent embossed element in such a way that the plateau is surrounded by a “sharp” edge. Here, the flat area with a certain inclination merges directly into the embossing element with a different inclination, the inclination directly at the edge not being differentiable in a mathematical sense. Alternatively, however, the edge of a flat area or plateau can also continuously merge into a flank of an adjoining embossed element, so that an arcuate or round transition results from the flat area to the flank of the adjoining embossed element. Of course, an approximately steady transition is also possible, in which the inclination of the flat area gradually merges over one or more adjacent flat areas with a gradually changing inclination into the flank of the adjacent embossed element.

Particularly preferably, the angle of the flank remains the same within an embossed element. The engraving depth must be adjusted accordingly. A A constant flank angle is necessary if the micromirror element should only appear in a certain angular range.

According to the invention, the non-linear embossed elements have a base in the form of a triangle, square, hexagonal honeycomb, octagon or other polygon. Mixtures of various of the aforementioned shapes are also possible, for example hexagons that border on quadrilaterals.

The width of the flat area, i.e. both the "peak" (near the surface of the embossing plate or the substrate) and the "troughs" (away from the surface of the embossing plate or the substrate) are preferably 1 μm to 200 μm, particularly preferably 5 μm to 150 μm and very particularly preferably 10 μm to 120 μm.

The distance d of the plateau to the plate surface can also be zero (d = 0), then the plateau is at the plate level. If plateaus at plate level are predominantly used, the structures can also be used in conventional gravure printing to carry ink. In this case, the plateaus represent a support structure for the doctor blade.

It is also particularly useful if the ratio of the distance between adjacent engravings and the corresponding engraving depth, the so-called aspect ratio, is 1: 5 to 20: 1, preferably 1: 3 to 10: 1 and particularly preferably 1: 2 to 6: 1 amounts.

According to a preferred embodiment, the depth of the engraved depressions is 10 μm to 500 μm, preferably 10 μm to 350 μm and particularly preferably 10 μm to 200 μm.

In the illustrations above, only embossed structures below the plate level were shown, as are mainly used in intaglio printing. If the embossing structure for gravure printing is used as blind embossing (round embossing cylinder versus round impression cylinder) or embossing (flat embossing plate versus flat impression plate), these are usually used raised above the plate surface. This increases the partial embossing pressure enormously and at the same time reduces the requirement for the provision of printing. The plateaus are then particularly preferably to be attached to the edges and tips which protrude farthest from the plate surface.

The embossing tool according to the invention is particularly suitable for engraving processes in which a rotating cylindrical workpiece made of plastic, for example Kapton, or of metal, for example brass, is engraved by means of a laser beam, the so-called "Computer to Intaglioplate" or "CTiP" method . The invention preferably makes it possible to use CTiP systems and thus to enable the use of “data merchandise”, that is to say predetermined embossing data for certain banknote denominations of a currency. Even if the laser diameter is not compensated, a suitable choice of the plateaus can prevent damage to the desired embossed structures by keeping sufficiently wide plateaus within the data structure.

However, the invention is not limited to embossing tools that are engraved by means of a laser beam. Rather, all other engraving methods known from the prior art can also be used, such as mechanical engraving using a stylus. In addition, direct manufacturing processes are also possible, such as 3D printing or sintering.

Particular advantages of the embossing tool according to the invention are furthermore that the plateau leads to a reduction in the sharpness of the edges, so that possible paper damage can be prevented during the embossing and the durability of the wiping cylinder of a intaglio printing machine can be increased. Conversely, the plateaus are also less sensitive to wear and tear from the wiping cylinder. Advantages of the invention are an improvement in the implementation and durability of the sensitive flanks and edges, an improved optically variable effect even with origination processes such as CtIP (creation of embossed structures in plastic plates or cylinders by means of laser radiation), better repeatability and greater adaptability to the substrate and counter pressure form.

An optically variable element in the context of this invention is an element whose visual appearance changes when the element is tilted or rotated. For example, when the optically variable element is tilted or rotated, its color changes, a bar appears to move from one side of the element to another, different characters are displayed when tilted or rotated, or a so-called pumping effect results in the form of an enlarging or decreasing effect Outline of an image motif.

The substrate particularly preferably consists of paper made of cotton fibers, as is used for example for bank notes, or of other natural fibers or of synthetic fibers or a mixture of natural and synthetic fibers, or of at least one plastic film. Furthermore, the substrate preferably consists of a combination of at least two different substrates arranged one above the other and connected to one another, a so-called hybrid. Here is the Substrate, for example, from a combination of plastic film-paper-plastic film, i.e. a substrate made of paper is covered on each of its two sides by a plastic film, or from a combination of paper-plastic film-paper, i.e. a substrate made of a plastic film is covered on each of its two sides Paper covered.

Information on the weight of the substrate used is for example in the document DE 102 43 653 A9 specified, the explanations of which are fully included in this application. The font DE 102 43 653 A9 states in particular that the paper layer usually has a weight of 50 g / m ² to 100 g / m ² , preferably 80 g / m ² to 90 g / m ² . Of course, any other suitable weight can be used depending on the application.

Documents of value for which such a substrate or security paper can be used are, in particular, banknotes, shares, bonds, certificates, vouchers, checks, high-quality entry tickets, but also other forgery-prone papers, such as passports and other identification documents, as well as cards, such as credit cards. or debit cards, the card body of which has at least one layer of security paper, and also product security elements such as labels, seals, packaging, folding boxes, package inserts, blisters and the like.

The simplified designation of value document includes all of the above materials, documents and product security means.

In the context of this invention, the positional accuracy of printed images or other elements with respect to one another on the front and / or back of a substrate is referred to as register. For example, interfere with parts of print images which, when viewed through, form an overall print image add, even small deviations of less than 0.1 mm between the respective print images significantly improve the visual impression when viewed through. DIN 16500-2: 1987-01 defines register as the accuracy in printing technology with which the intended reproduction quality of the details to be reproduced is achieved or maintained.

Information within the meaning of this invention is a visually perceptible representation designed in the form of a pattern. This can, for example, form an alphanumeric string of digits and / or letters, a graphic image, an image, a text or other characters. The information particularly preferably consists of positive and / or negative motifs. In the case of a positive motif, a motif element itself is applied to the substrate, whereas in the case of a negative motif, the area surrounding the motif element is applied to the substrate. A positive motif is, for example, a letter printed in dark color on the light substrate. A negative motif is, for example, an area applied in dark color to the light-colored substrate, which has an unprinted area in the form of a letter within the area.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the specified combinations but also in other combinations without departing from the scope of the present invention, insofar as this is covered by the scope of protection of the claims.

The advantages of the invention are explained on the basis of the following exemplary embodiments and the supplementary figures. The exemplary embodiments represent preferred embodiments to which, however, the invention is not intended to be restricted in any way. Furthermore, the representations The figures are highly schematic for better understanding and do not reflect the real conditions. In particular, the proportions shown in the figures do not correspond to the conditions present in reality and serve exclusively to improve the clarity.

The embodiments described in the following examples are reduced to the essential core information for better understanding. In the practical implementation, much more complex patterns or images in single or multi-color printing can be used as a coating. The same applies to the embossed structures. The information presented in the following examples can also be replaced by any complex image or text information. The generation of the coating z. B. as an imprint usually uses the possibilities of printing technology. Typical dimensions of non-linear basic elements from approx. 10 µm are used. Embossed elements that form the embossed structure generally have an embossed height in the range from 10 μm to 500 μm, preferably from 50 μm to 120 μm.

Furthermore, in the following examples only the design and mutual association of the embossed structure and the coating are shown in order to be able to clearly show the optical effects of the optically variable structure according to the invention.

Fig. 1

eine erstes Ausführungsbeispiel einer Prägestruktur in Form von zwei sechseckigen Waben und hierbei in der linken Figur in Draufsicht und in der rechten Figur im Querschnitt entlang der Schnittachse AB,

Fig. 2

eine zweites Ausführungsbeispiel einer Prägestruktur in Form von zwei sechseckigen Waben und hierbei in der linken Figur in Draufsicht und in der rechten Figur im Querschnitt entlang der Schnittachse CD,

Fig. 3

eine erstes Ausführungsbeispiel einer erfindungsgemäßen Prägestruktur in Form von zwei sechseckigen Waben mit einem Plateau und hierbei in der linken Figur in Draufsicht und in der rechten Figur im Querschnitt entlang der Schnittachse EF,

Fig. 4

eine zweites Ausführungsbeispiel einer erfindungsgemäßen Prägestruktur in Form von zwei sechseckigen Waben mit einem Plateau und hierbei in der linken Figur in Draufsicht und in der rechten Figur im Querschnitt entlang der Schnittachse EF,

Fig. 5

eine drittes Ausführungsbeispiel einer erfindungsgemäßen Prägestruktur in Form von zwei Waben mit einem Plateau im Querschnitt,

Fig. 6

eine viertes Ausführungsbeispiel einer erfindungsgemäßen Prägestruktur in Form von zwei Waben mit einem Plateau im Querschnitt.

In detail show schematically:

Fig. 1

a first embodiment of an embossed structure in the form of two hexagonal honeycombs and here in the left figure in Top view and in the right figure in cross section along the cutting axis AB,

Fig. 2

a second embodiment of an embossed structure in the form of two hexagonal honeycombs and here in the left figure in plan view and in the right figure in cross section along the cutting axis CD,

Fig. 3

a first embodiment of an embossed structure according to the invention in the form of two hexagonal honeycombs with a plateau and here in the left figure in plan view and in the right figure in cross section along the sectional axis EF,

Fig. 4

a second embodiment of an embossed structure according to the invention in the form of two hexagonal honeycombs with a plateau and here in the left figure in plan view and in the right figure in cross section along the sectional axis EF,

Fig. 5

a third embodiment of an embossed structure according to the invention in the form of two honeycombs with a plateau in cross section,

Fig. 6

a fourth embodiment of an embossed structure according to the invention in the form of two honeycombs with a plateau in cross section.

Fig. 1 shows schematically an arrangement of two embossed structures 1, 2 in the form of hexagonal honeycombs and here in the left figure in plan view and in the right figure in cross section along the cutting axis AB. The angle α at the honeycomb edge, that is, between the honeycomb mirror surfaces of the relevant edge is greater than 120 °, so that, according to the above statements, no plateau is inserted between the two honeycombs. In addition, the honeycomb edge is at the level of the substrate or plate surface 3, which is indicated in the right figure by the dashed line.

Fig. 2 shows schematically the two embossed structures 4, 5 in the form of hexagonal honeycombs, here in contrast to the honeycombs Fig. 1 the angle α at the honeycomb edge is less than 120 °, so that, according to the above statements, a plateau is inserted between the two honeycombs. The plateau is in Fig. 2 to clarify the angle α not shown. In addition, the honeycomb edge is located recessed by the distance d from the substrate or plate surface 3, with d <20 μm, preferably d <10 μm, particularly preferably d <5 μm.

Such a plateau is in Fig. 3 and in Fig. 4 shown. Fig. 3 shows a plan view in the left figure and a plateau along the sectional axis EF in the right figure, which is arranged both between the two embossed structures 4 and 5 and around both embossed structures 4 and 5. Fig. 4 shows in the left figure a plan view and in the right figure along the sectional axis GH a plateau which is only arranged between the two embossed structures 4 and 5. In Fig. 3 and in Fig. 4 the plateau between the two embossed structures 4 and 5 is arranged recessed by the distance d from the substrate or plate surface 3.

The embossed structures are in FIGS. 1 to 4 each shown as a hexagonal honeycomb. However, any other shapes are also possible, such as triangles, squares, octagons or other polygons. Mixtures of various of the aforementioned shapes are also possible, for example hexagons that border on quadrilaterals.

Fig. 5 shows that the distance d of the plateau to the plate surface can also be zero (d = 0). In this case the plateau lies at the level of the substrate or plate surface 3.

In the above illustrations, only embossed structures on or below the substrate or plate surface 3 were shown, as are mainly used in intaglio printing. If the embossing structure for gravure printing is used as blind embossing (round / round) or embossing (flat / flat), these are used as in Fig. 6 shown, mostly inserted raised above the plate surface 3. This increases the partial embossing pressure enormously and at the same time reduces the requirement for the provision of printing. According to Fig. 6 In this case, the plateaus should preferably be attached to the edges and tips that protrude farthest from the plate surface.

Claims (11)

1. Security element made from a substrate with an optically variable structure comprising an embossed structure and a coating, wherein the embossed structure and the coating are combined such that at least parts of the coating are entirely visible when viewed perpendicularly but are hidden when viewed at an angle, with the result that different pieces of information become visible as the viewing direction changes, wherein the embossed structure consists of non-line-shaped embossed elements that adjoin one another, wherein each non-line-shaped embossed element substantially consists of a flank, wherein a planar region or a plateau, arranged substantially parallel to the surface of the substrate which surrounds the embossed element, is arranged between adjoining embossed elements, characterized in that the non-linear embossed elements have a base area in the shape of a triangle, a rectangle, a hexagonal honeycomb, an octagon or another polygon.
2. Security element according to Claim 1, characterized in that the angle between the planar region or plateau and the surface of the substrate surrounding the security element or between the planar region or plateau and the embossing tool with respect to one another is preferably 0° and preferably from 0.5° to 5°.
3. Security element according to Claim 1 or 2, characterized in that the planar region or the plateau is arranged only between two adjoining embossed elements.
4. Security element according to Claim 1 or 2, characterized in that the planar region or the plateau is arranged around the entire embossed element.
5. Security element according to one of the preceding claims, characterized in that the periphery of a planar region or plateau extends with respect to the flank of an adjoining embossed element in such a manner that the plateau is surrounded by a "sharp" edge.
6. Security element according to one of Claims 1 to 4, characterized in that the periphery of a planar region or plateau continually transitions into a flank of an adjoining embossed element, forming an arcuate or round transition from the planar region to the flank of the adjoining embossed element.
7. Embossing tool for producing a security element from a substrate with an optically variable structure comprising an embossed structure and a coating, wherein the embossed structure and the coating are combined such that at least parts of the coating are entirely visible when viewed perpendicularly but are hidden when viewed at an angle, with the result that different pieces of information become visible as the viewing direction changes, wherein the embossed structure consists of non-line-shaped embossed elements that adjoin one another, wherein each non-line-shaped embossed element substantially consists of a flank, characterized in that a planar region or a plateau, arranged substantially parallel to the surface of the substrate which surrounds the embossed element, is arranged between adjoining embossed elements, wherein the non-linear embossed elements have a base area in the shape of a triangle, a rectangle, a hexagonal honeycomb, an octagon or another polygon.
8. Embossing tool according to Claim 8, characterized in that the embossing tool is an embossing cylinder, an embossing die or a printing plate, in particular an intaglio printing plate, wherein the elements to be embossed are designed as an engraving or as an elevation in the surface of the embossing tool.
9. Embossing tool according to Claim 9, characterized in that the printing plate or intaglio printing plate is preferably fastened to a rotating cylinder.
10. Embossing tool according to one of Claims 8 to 10, characterized in that a planar region or a plateau is introduced at the edges between two adjoining embossed elements if

    • the edge is located between two embossed elements on the plate surface or is recessed relative to the plate surface by a maximum distance d, with d < 20 µm, preferable d < 10 µm, with particular preference d < 5 µm, and

    • the angle α between the reflective face of the embossed element and the relevant edge is α < 120°, preferably α < 90° and with particular preference α < 60°.
11. Embossing tool according to one of Claims 8 to 11, characterized in that the security element comprises at least one of the features of Claims 2 to 7.

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