EP3727871B1 - Value document - Google Patents

Description

The invention relates to a value document, such as a banknote, a cheque, a credit or other payment card, an identification card or the like.

For valuable documents such as banknotes, foil-based security features such as holograms, optically variable elements and/or transparent windows can be used. They are produced on foil and later applied to the banknote paper. Foil elements give banknotes additional protection against counterfeiting, but are difficult to register accurately with the printed image and the watermark. There is also a risk that foil elements will come off during the circulation of a banknote. WO 2016/096095 A1 A generic value document is known that is made up entirely of a foil body. The foil body consists of two foils that are connected to each other via an intermediate layer. On the sides facing the intermediate layer, the foils each have subwavelength structures. All optical views that are The images presented in a valuable document are generated by these subwavelength structures. Other image-generating elements are deliberately excluded.

Banknotes with different substrates currently exist. Paper, polymer and mixed forms of paper and polymer in the form of so-called hybrid banknotes are well known. Special process steps are required for each type of banknote in order to apply security elements to the banknote paper or to create them on the banknote paper when printing the banknotes. With polymer banknotes, color retention during circulation is problematic.

The problems and requirements mentioned apply not only to banknotes, i.e. paper or foil-based value documents, but also to payment cards or identification cards. The term "value document" is therefore understood here to include sheet-like value documents, such as banknotes, checks, etc., as well as comparatively rigid value documents, e.g. security, ID or payment cards.

The WO 2011/107782 A1 describes as well as the WO 2017/026521 A1 , the WO2006/125224 A2 and the WO 02/00445 A1 an optically variable security element. The WO 02/00445-A1 discloses in particular a security element which has a front and a back side, in plan view at least from the front side shows a representation which can be seen with the naked eye, has certain dimensions (W, H) in the plan view and has a substrate body which has the certain dimensions (W, H) in the plan view and is made up of at least one transparent film which also has the certain dimensions (W, H) in the plan view, wherein the representation which can be seen from the front side is produced by a first, at least partially metallized embossed structure which is arranged on one side of the first film and has a varying profiling and/or metallization laterally, i.e. transversely to the plan view direction, wherein the first, at least partially metallized embossed structure is formed on a front side of the film facing the front side and a second, at least partially metallized embossed structure is formed on a back side of the film facing the back side and at least one of the metallized embossed structures is covered with a leveling cover layer.

The EP 0 271 673 A1 describes a security element that has a full-surface metallization and can be applied to a banknote as a transfer element.

The EN 10 2015 010744 A1 describes a security element with an embossed structure that is formed in sections as a nanostructure.

The invention is based on the object of creating a value document in which foil-based security elements can be easily combined with security elements that are generated by displaying images, etc. A further object underlying the invention is to create a value document that is particularly durable in circulation.

The invention is defined in independent claim 1. The dependent claims relate to advantageous developments of the invention.

The invention provides a value document that consists entirely of a film body. The value document has certain dimensions in plan view. The film body has the same dimensions in plan view. A representation can be seen from the front. This is produced by a first embossed structure that is metallized at least in sections. The embossed structure has a varying profile and/or metallization transverse to the plan view direction.

The substrate body is made up of at least one transparent film and bears the first embossed structure on the front side of the film facing the front. In this first variant, a second embossed structure, which is at least partially metallized, is formed on a film back facing the rear side. At least one of the metallized embossed structures is covered with a leveling cover layer.

The embossed structure has microlenses, as are known for so-called moiré magnifiers, and/or it is formed in parts, i.e. in sections, as a subwavelength structure and has a periodicity of 150 nm to 500 nm or is aperiodic with structure widths of 150 nm to 500 nm.

In embodiments, at least one opaque section is provided between the first and the second embossed structure. This can have a laterally structured opacity.

In embodiments, the first and second embossed structures form a window in opposite areas, in which the representation by the first embossed structure complements the further representation by the second embossed structure when viewed through to form a motif. The first and second embossed structures can optionally have an asymmetrical profile in the area of the window and create a motif in reflection that disappears when viewed through.

For all embodiments, the first embossed structure can be formed in at least one region as a microstructure with a period of 500 nm to 2 µm, which represents, for example, a hologram or an image with a tilting or movement effect.

The invention uses banknotes with a full surface structure that show a viewer a representation that is created by embossed structures. The conventional printed image of a value document, for example a banknote, is reproduced by the embossed structure with the lateral variation of profile/periodicity. The embossed structures offer the representation not only in specular reflection, but also, for example, in a higher diffraction order, for example the first or further diffraction orders. They are designed in such a way that the representation can be recognized over a wide viewing angle range that is almost or completely the same as that of a conventional printed image.

Because the print image of the value document is reproduced by full-surface embossed structures, the conventional printing process in banknote production is superfluous. The embossed structure is covered and thus robust against environmental influences. In addition, all desired security features such as holograms, micromirrors, etc. can be produced in a single embossing step. Furthermore, overhead/transparent effects can be easily implemented in windows. The production of the value document is thus significantly simplified. The appearance of the first diffraction order increases the security against counterfeiting compared to conventional banknotes.

In a preferred embodiment, the first and second embossed structures form a window in opposite areas. The metallization of the embossed structures is relevant for this window. Preferably, no metallization is provided in the window area. This can be achieved by not applying the metallization in the window area from the start or by subsequently removing the metallization in the window area, for example by removing it with a laser or using a so-called wash paint. Both means are known to the person skilled in the art from the prior art.

In the simplest case, the cover layer can consist of a dielectric with which the inner sides of the foils are laminated. It is also possible to design the value document as a so-called hybrid value document, for example as a hybrid banknote, if the intermediate layer comprises banknote paper. Banknote paper that has a watermark is particularly preferred here, with the embossed structures in the area above the watermark forming a window. This makes the watermark visible through the window.

A colorful effect of the display can be achieved by applying a layer of color to the foil or foils or by coloring the foil/foils.

Banknotes are examples of value documents that are individualized. They have a serial number. This serial number can be generated particularly easily in the value document according to the invention by, for example, omitting or subsequently removing the metallization in a pattern, so that the value document is thereby individualized. It is therefore preferred that the metallization is omitted or removed in a pattern that individualizes the value document, in particular in a pattern that represents a serial number.

For the purposes of this description, metallization is understood to mean a coating that consists of metal or that contains metal. A layer structure is also possible that consists of a composite layer that has metal deposits. However, it can also consist of a multi-layer structure in which one or more layers are metallic.

For the production of the value document using an embossing process, direct exposure techniques, e.g. using a laser writer, are particularly suitable for producing a pattern. The original of the embossed structure is written into a substrate coated with photoresist using direct exposure using a laser writer and the exposed part of the photoresist is then removed. More complex methods for producing the original, such as electron beam or "Focused Ion Beam" exposure methods, allow a particularly fine design of the embossed structure. The material exposed in this way The original can then be electroplated and an embossing stamp can be created as a master, which is used to produce an embossing cylinder for embossing a film web. Ultimately, the structure is replicated using an embossing process, for example in UV varnish on film or directly (e.g. by hot stamping into the surface of the film). Alternatively, a nanoimprint process can be used.

The embossed film surface is then metallized, e.g. with a reflective layer and/or a structure that creates a color effect, e.g. an interference layer structure, and/or a color layer, e.g. a color-fix coating. This can be done using electron beam vapor deposition, sputtering or thermal vaporization under vacuum. Finally, the film is laminated.

• Fig. 1 eine Draufsicht auf eine Banknote und
• Fig. 2 bis 4 Schnittdarstellungen für verschiedene nichterfindungsgemäße Beispiele von Prägestrukturen der Banknote der Fig. 1.
• Fig. 5 Schnittdarstellung einer erfindungsgemäßen Ausführungsform der Banknote der Fig. 1

It is understood that the features mentioned above and those to be explained below can be used not only in the combinations given, but also in other combinations or on their own, without departing from the scope of the present invention. The invention is explained in more detail below by way of example with reference to the attached drawings, which also disclose features essential to the invention. They show:

• Fig.1 a top view of a banknote and
• Fig. 2 to 4 Sectional views for various non-inventive examples of embossed structures of the banknote of Fig.1 .
• Fig.5 Sectional view of an embodiment of the banknote according to the invention of Fig.1

Fig.1 shows schematically a banknote 1 with an embossed structure over its entire surface, which is made up of a substrate body 2 which has a height H and a width B. In a first embodiment, the substrate body 2 is provided with an embossed structure on each of its inner surfaces, which, for example, provides micromirrors and/or microlenses at least in sections. In other embodiments, the embossed structures are formed on both sides of the same film. Both are explained below using the sectional views of the Fig. 2 to 5 , which show different embodiments for the embossed structure, are explained in more detail.

Banknote 1, which is an example of a value document, presents an observer from the front, which is in Fig.1 is shown, a representation 3 is provided, as is usual for banknotes. The representation 3 can, for example, comprise a graphically designed background 4, a moiré image 5, a hologram 6, a value indication 7 and a serial number 8. It is also possible to provide a window 19 in which the banknote is partially transparent. In the window 19, for example, see-through effects can be present, ie a motif visible on the front complements a motif visible on the back in transparency to form another motif.

The substrate body 2 with the height H and the width B is constructed from at least one film of the same dimensions as the sectional views of the non-inventive Fig. 2 to 4 , which show embodiments for the banknote 1. The sectional views of the non-inventive Figures 2 to 4 differ in terms of the design of the banknotes. What they have in common is that an embossed structure is provided, which in some variants comprises microlenses. In the embodiments of the non-inventive Figures 2 to 4 The substrate body comprises two foils, in the embodiment of the Fig.5 a slide.

In the sectional view of the non-inventive Fig.2 There is a top side 9, which is Fig.1 can be seen, at the top, and a rear side 10 is at the bottom. The substrate body 2 comprises a first film 11, the outward-facing surface of which forms the front side 9, and a second film 12, the outside of which forms the rear side 10. Between the first film 11 and the second film 12 there is a dielectric 13 as an intermediate layer.

A first embossed structure 14 is formed on the inside of the first film 11 and a second embossed structure 15 on the inside of the second film 12. The embossed structures are designed with a laterally varying structure and/or metallization. In detail, depending on the embodiment, they comprise a different selection of microlenses 16, which interact with a microimage structure 18 arranged in an intermediate layer 17 and, for example, form a known moiré magnifier in order to generate the moiré image 5. Furthermore, a hologram structure or other microstructure 24 can be provided in the embossed structure 14. It is also possible to form a mirror structure 20 which consists of differently inclined micromirrors and thus creates a tilting effect. Furthermore, the embossed structures can also have subwavelength structures 21 with a laterally varying profile and/or laterally varying periodicity. Details for the design of the subwavelength structure can be found in the literature references already mentioned: DE 102011115589 A1 , WO 2012/156049 A1 , WO 2014/023415 A1 , EN 102009012300 A1 , Y. Yu, L. Wen, S. Song, and Q. Chen, "Transmissive/Reflective Structural Color Filters: Theory and Applications," Journal of Nanomaterials, vol. 2014, Article ID 212637, 17 pages, 2014. doi:10.1155/2014/212637 and H. Lochbihler , "Colored images generated by metallic subwavelength gratings," Opt. Express 17, 12189-12196 (2009 ).

The microstructures 24 differ further in their structure from the subwavelength structures 20, which have structure widths in the range of the light wavelength. The microstructures 24 are significantly longer (from 0.6 µm) and generate, for example, diffractive effects, while the subwavelength structures cause interference effects of the light waves.

The selection of the various embossed structures can be made depending on the embodiment and the desired design for the banknote 1. In particular, the Fig.2 The assignment to slides 11 and 12 is purely exemplary.

For many embossed structures, it is necessary that the embossed structures are metallized in order to create an effect or an image. In the area of window 19, this metallization was removed after application or was not present to begin with. Removal can be done using a laser or a wash color, for example. The same applies to individualizing banknote 1 with serial number 8, which is also created by individually removing the metallization.

The first embossed structure 14 on the inside of the first foil 11 is visible when viewed from the front side 9 and forms the image 3, i.e. both the background 4 and the image 5 and the value 7 - either alone or in conjunction with conventional printed images on the outside of the foil. The hologram 6 is e.g. region of the embossed structure is created which has a suitable periodicity. Holograms are known to be formed by grating regions or microstructures with periods of 0.6 to 2 µm.

The first and second films 11 and 12 are transparent. They are preferably each a plastic film. During the production of the substrate body 2, the films 11 and 12 are embossed with the embossed structures 14 and 16 and then provided with the metallization, for example by a vapor deposition process. The two films are then connected to one another via the intermediate layer that forms the dielectric 13, for example by lamination. The dielectric 13 can preferably be a polymer.

In order to remove the shine that is usual for films from the front side 9 and the back side 10, which is further enhanced by the metallization of the embossed structures, the outer surfaces of the films 11, 12 are provided with a matting, for example in the form of a coating that creates a slightly scattering surface, in embodiments not shown in detail.

In order to prevent the embossed structure 15 on the second film from shining through when viewed from the front, it is preferable to make the intermediate layer 17 opaque. This is shown by the non-inventive Fig. 3 The opacity of the material between the embossed structures 14 and 15 ensures that when looking at the front side 9, only the embossed structure 14 contributes to the representation, and when looking at the back side 10, only the embossed structure 15 contributes. The opacity can be achieved, for example, by an opaque intermediate layer 17, preferably an opaque white or a colored adhesive layer or laminating layer. In a further embodiment, the opaque layer 17 can be provided with a locally varying opacity.

If the structural body 2 of the banknote 1 has a window 19, the opaque layer 17 is of course interrupted in this area by a transparent window 23, as is the case with the non-inventive Fig.4 shows.

Fig.5 shows an embodiment of the invention with only one film 11, which is provided on both sides with the embossed structures 14, 15. At least one of the embossed structures is covered with a cover layer 22, which levels the upper side. The embodiment of the Fig.5 that the embossed structure can have a gap on one of the two sides or on both sides in which no embossing has taken place. When using refractive microlenses 16, covering with an equalizing cover layer is disadvantageous because the lens effect could be destroyed. Equalization is possible if reflective lenses are used, i.e. micro concave mirrors. To produce the substrate body 2, the embossed structures are preferably produced in one operation in a double embossing system. In general, the production of the value document includes the following steps:
First, the relief structure is created for an original with the dimensions of the value document, for example with the height H and the width B of the banknote 1. This relief structure is created, for example, using a laser writing process or a mask process in a photoresist. A stamp is then produced as a master from the original structure, for example by copying the relief structure into a nickel form using galvanic molding or into a photopolymer. Using this stamp, an embossing cylinder is now created that reproduces the relief structure of the original. duplicated on the surface of the embossing cylinder. Common steps for producing an embossing cylinder are the galvanic molding of a replica in nickel and the drawing of the structured nickel foil onto an embossing cylinder.

The embossing cylinder produced in this way is then used to mold the original structure onto a plastic film web in a continuous process, multiple times next to each other, using UV varnish or using a hot embossing process. The film web embossed in this way contains lines across the direction of the web in which several areas of width B and height H lie next to each other. The lines are repeated along the length of the film web. The film web embossed in this way is then coated with a thin metal layer, preferably aluminum, silver, chromium, copper, gold or alloys thereof. Semi-metal layers, such as silicon, germanium, carbon and silicon oxide (preferably with a Si:O ratio of less than one) can also be used. High-vacuum vapor deposition using vapor deposition or sputtering or other coating processes are suitable as coating processes.

In this way, film webs for the first film 11 and, if applicable, the second film 12 are produced.

In the two-part variant, these are then connected on their inner sides, ie the sides that contain the metallized embossed structures. An inner substrate, for example banknote paper, can also be laminated on. The banknotes 1 produced in this way are then separated by cutting.

Demetallized areas or a window are created before the two films are joined. For example, it is possible to print a wash color onto the film strips at the locations where windows are to be located later, before the metallization is carried out. After metallization, the material and the color are removed using a washing process known to those skilled in the art. Alternatively, the metallization can be removed by irradiation with suitable laser radiation. In this way, the serial numbers 8 can also be embedded in the film, with the material preferably being removed on one side in a pattern corresponding to the serial number 8. The contrast is created later by looking at the inside of the rear film or at the internal substrate or dielectric.

The matting can be created on the film web by laminating a scattering layer onto the outside or by plasma melting the film surface.

List of reference symbols

1

Banknote

2

Substrate body

3

Depiction

4

background

5

Moire image

6

hologram

7

Value indication

8th

serial number

9

front

10

back

11

first slide

12

second slide

13

dielectric

14

first embossed structure

15

Second embossed structure

16

Microlenses

17

Intermediate layer

18

Microimage structure

20

Micromirrors

21

Subwavelength structure

22

Top layer

23

Window

24

Microstructure

Claims (8)

1. Value document such as a banknote (1), a check, a credit or other payment card, an identity card or the like, which has a front side (9) and a back side (10), shows a representation (3) recognizable to the unaided eye in top view at least from the front side (9), has specific dimensions (B, H) and comprises a substrate body (2) which has the specific dimensions (B, H) in top view and is constructed from at least one transparent film (11, 12) which also has the specific dimensions (B, H) in top view, wherein the representation (3) recognizable from the front side (9) is generated by a first and at least partly metallized embossed structure (14) and which is arranged on one side of the first film (9) and has a laterally, i.e. transversely to the top view direction, varying profiling and/or metallization, wherein the first and at least partly metallized embossed structure (14) is formed on a film front side facing the front side and a second and at least partly metallized embossed structure (14) is formed on a film back side facing the rear side (10) and at least one of the metallized embossed structures (14) is covered with a levelling cover layer (22), wherein

   - the embossed structure (14) comprises micro lenses (16) and/or micromirrors (20) and/or

   - the embossed structure (14) is formed in sections as a subwavelength structure (21) having a periodicity of 150 nm to 500 nm or being aperiodically with structure widths of 150 nm to 500 nm.
2. Security document according to claim 1, characterized in that at least one opaque section (17) is provided between the embossed structures (14, 15).
3. Value document according to one of the above claims, characterized in that the first and second embossed structures (14, 15) form a window (19) in opposite areas, in which the representation by the first embossed structure (14) is supplemented by the further representation by the second embossed structure (15) to form a motif in transparent view.
4. Value document according to claim 3, characterized in that the first and second embossed structures (14, 15) have an asymmetrical profile in the region of the window (19), and produce a motif in reflection which motif disappears in transparent view.
5. Security document according to claim 3, characterized in that no metallization is provided in the region of the window (19).
6. Security document according to any of the above claims, characterized in that the first embossed structure (14) is formed at least in one region as a microstructure (24) with a period of 500 nm to 2 µm, which represents a hologram.
7. Security document according to any of the above claims, characterized in that there is a colored layer on the foil or foils (11, 12), or the foil or foils (11, 12) is/are colored.
8. Security document according to any of the above claims, characterized in that the metallization is omitted or removed in form of a pattern individualizing the security document, in particular as a serial number.

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