EP4112326B1 - Security substrate and valuable document produced therefrom - Google Patents

Description

The invention relates to a security substrate for value documents, such as banknotes, checks, credit or other payment cards, identification cards or the like, which has a front and a back and covers a certain area in plan view and is film-based and has at least one relief structure.

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.

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 banknote paper to obtain a security substrate that can be printed on. In the state of the art, security features are known for this purpose that have at least one relief structure, usually created by embossing, for example holograms, nanostructures, micromirrors, moiré magnifiers, etc.

The security features are foil-based, and the substrate, which comprises at least one foil, is applied to a security substrate as a transfer element. This has the disadvantage that such security features can only be distributed or arranged on the security substrate and the value document subsequently produced from it with restrictions. Strips and security threads, for example, can only be attached with their security elements in a defined, rectangular area. Applying individual patches involves a high production cost. The more security features there are, the more the manufacturing cost of the security substrate or the value document increases.

In addition, with a security substrate with glued-on security elements, for example in the form of patches, there is always the risk that these will later detach from the security document either in circulation or be removed with fraudulent intent in order to use them to increase the value of counterfeit items. Foil elements give banknotes additional security against counterfeiting, but are also difficult in terms of registering accurately with the printed image and the watermark.

The WO98/13211 A1 describes as well as the WO 2008/031170 A1 , the EP 2384901 A1 and the WO 2017/055824 A1 a security substrate.

In particular, WO98/13211 A1 a security substrate for value documents comprising a substantially opaque layer arranged over a carrier film, a print acceptance layer arranged over the substantially opaque layer and a relief structure arranged between the opaque layer and the carrier film and provided with a reflection-enhancing coating.

From the WO 2016/096095 A1 A security document is known that is made up entirely of a film body. The film body consists of two films that are connected to one another via an intermediate layer. On the sides facing the intermediate layer, the films each have subwavelength structures. All optical views that are normally created by printing processes and presented by the security document are now created by these subwavelength structures. Other image-generating elements, such as printing elements, are deliberately excluded.

The problems and requirements mentioned above do not only apply to banknotes, i.e. paper or foil-based security documents, but also to payment cards or identification cards. The term "security substrate" is therefore understood here to include sheet-like security substrates, such as precursors for printing banknotes, cheques, etc., as well as comparatively rigid security substrates, e.g. precursors for security, identification or payment cards.

The invention is based on the object of creating a security substrate and a value document in which film-based security elements can be easily combined with security elements that are created by displaying images, etc., with the greatest possible freedom of design, without making production more difficult. At the same time, a particularly good color appearance should be achieved.

The invention is defined in the independent claims 1, 2 and 15. The dependent claims relate to advantageous developments of the invention.

The security substrate has a front and a back. It covers a specific area in plan view. It has a first carrier film which extends over at least 50%, preferably over 75% or 100% of this area. A first essentially opaque layer is arranged over the first carrier film, which covers at least 25%, preferably more than 50% and particularly preferably more than 75% of the specific area. A first print acceptance layer is arranged over this first opaque layer, on which a first, colored printing element is preferably formed. A first relief structure is arranged between the first opaque layer and the first carrier film. It is provided with a first reflection-enhancing coating which, together with the first relief structure or on its own, produces a first optically variable effect.

Alternatively, the first substantially opaque layer can also be omitted and the first print-accepting layer can have an opacity. In this case, a first print-accepting layer is arranged above the first carrier film, which is substantially opaque and covers at least 25%, preferably more than 50% and particularly preferably more than 75% of the specific area and on which a first, colored printing element is preferably formed. A first relief structure is arranged between the first print-accepting layer and the first carrier film. It is provided with a first reflection-increasing coating, which together with the first relief structure or on its own produces a first optically variable effect.

The term "opaque" means an opacity of at least 50%, preferably 75% or more.

In a further development, the first opaque layer or first pressure-accepting layer is arranged on a second carrier film, which lies between the first opaque layer or first pressure-accepting layer and the first relief structure. This makes it easier to manufacture, since the first opaque layer or first pressure-accepting layer is applied to the second carrier film and then connected to the first carrier film on which the first relief structure is formed, for example by lamination. This is then of course done in such a way that the first relief structure lies between the first opaque layer or first pressure-accepting layer and the first carrier film on which the first relief structure is located. The second carrier film is therefore located between the first opaque layer or first pressure-accepting layer and the first relief structure.

A second, essentially opaque layer is provided on the side of the first relief structure opposite the first opaque layer or first print-accepting layer. A second print-accepting layer is then also provided on this side, on which a second, colored printing element is formed.

In this way, there are several possible designs. The security substrate can be made from a single film with the first relief structure embossed and embedded in protective varnish. It is also possible to laminate the first and second carrier films onto one another. A three-film structure, of which the middle one is the first carrier film with the first relief structure, is also equally possible.

The relief structure can be embossed on one side of the carrier film. It is also possible to emboss on both sides, i.e. to provide a second relief structure with a second reflection-enhancing coating on the other side of the first carrier film, so that there is a coated relief structure on both sides of the carrier film in an embossing varnish applied to it.

The security substrate can be made purely from foil. However, a combination with paper is also possible. A paper layer can be used as a core, onto whose surfaces the foils are applied over the entire surface, whereby one of the foils is then the first carrier foil. Of course, foils applied to both sides of the paper core can also have relief structures. In this case, the second relief structure mentioned above is provided. An inversion of this structure is possible in that the carrier foil, which has the first (and possibly also second) relief structure Paper layers are applied as a core. This can be done by laminating.

With regard to the reflection-enhancing coating, metallizations such as aluminum, gold, silver, chrome, Cr-Al, Cr-Al-Cr or alloys, e.g. Cu-Al, are possible. So-called color-shift or color-change coatings are also possible, i.e. layer sequences of metal-dielectric-metal. Another option is semi-transparent metallizations to only partially cover the colored printing elements, or metal pigment colors or flakes. The relief structure, usually created by embossing, can then be metallized using printing technology.

The reflection-enhancing coating can be structured laterally. This is usually referred to as demetallization and is done to reveal the effect or print elements behind it. A variety of means are known to the expert for demetallization, for example so-called wash-ink printing, etching techniques, metal transfer processes, printing with an oil film before vapor deposition, etc. The lateral structuring of the opacity of the reflection-enhancing coating can create the appearance of a watermark.

A wide variety of metal pigment inks or flakes, translucent inks, fluorine inks, structural or binary inks in the form of nanostructures, etc. can be used for the colored printing element. The print acceptance layer can be an opaque white or a semi-transparent or fully transparent ink acceptance layer.

As mentioned above, if a combination with paper layers is used, a low grammage is particularly preferred. can be chosen to locally vary the transparency of the paper portion. In this way, embossed optical effects can be made visible through the paper - again, this creates a watermark appearance. It is also possible to have cutouts in the paper as mentioned above. This can be done by laser cutting, etc. Another option is to use colored mottled fibers.

The relief structure can realize the optically variable effect using a wide variety of known techniques. Examples are hologram structures, nanostructures, micromirrors, blazed gratings, sawtooth structures, microstructures, microfocusing elements such as lenses, Fresnel lenses, concave mirrors, Fresnel concave mirrors, pinhole and slit diaphragms, each in combination with microstructures to create modulo mapper or moiré magnifier structures. Microfocusing elements are particularly interesting in connection with two- or multi-layer films, as the thicker composite structures then allow longer focal lengths and optical effect and printing elements can work better with the microfocusing elements.

According to a preferred embodiment, the micromirrors can be arranged in the z-direction at different heights, as is particularly evident from the EN 102018005474 A1 , DE 102018005447 A1 or EN 102018005454 A1 is known.

If films are laminated to one another or films are laminated to paper or paper to one another, standard laminating adhesives can be used. Colored and/or semi-transparent laminating adhesives are also possible, or laminating adhesives that contain fluorescent effects, OVI, metal flakes, etc. Lamination without adhesive is also possible, for example by melting under pressure or temperature.

The security elements that are formed on the security substrate using the options mentioned above can be distributed as desired over the entire security substrate. This also allows particularly individual security features to be designed, since the now achieved arbitrary distribution of the security elements was not possible in the prior art.

When laminating film layers, the print image, i.e. the colored printing elements and/or the print acceptance layer, can be aligned inwards, which is naturally useful for multi-layer structures. Then the outside of the security substrate can have a bare film surface, so that the security features are particularly well protected. This leads to a high level of resistance to circulation.

Furthermore, completely transparent or partially transparent windows can be created, for example via demetallized areas in the relief structure and/or the reflection-enhancing coating and/or the opaque layer. These windows can also be provided with semi-transparent color-shift coatings, etc. It is also possible to apply different vapor deposition layers in an overlapping manner in order to create different optical impressions from the front and back, for example different basic colors.

The machine readability of the security substrate can be improved by applying or introducing conductive materials.

The security substrate can be produced using the traditional banknote sheet-fed printing method, or using roll-to-roll printing. In the latter process, the colored printing element is printed onto the already laminated end product or onto the films to be laminated together.

In particular, it is intended to form a window in the first opaque layer or first pressure-accepting layer and/or the second opaque layer - if the latter is present - so that the security substrate becomes at least partially transparent in the area of the window or the relief structure with the reflection-enhancing coating is visible through the window in the opaque layer or the first pressure-accepting layer. If windows are applied one above the other in two opaque layers or a pressure-accepting layer and an opaque layer, a see-through security feature is obtained. The first opaque layer or first pressure-accepting layer and - if present - the second opaque layer can each be formed as a white layer, in particular as an opaque white layer.

Various embossing processes can be used to produce the relief structure. In particular, an embossing layer is provided on the carrier film for this purpose. The relief structure can be further formed in sections as a subwavelength structure and have a periodicity of 150 nm to 500 nm or can be designed aperiodically with a structure width of 150 nm to 500 nm.

For the opaque layer or pressure-accepting layer and/or the reflection-enhancing coating, a laterally structured opacity is preferred so that a light/dark representation is visible when viewed through transmitted light. This naturally applies to any of the opaque layers and reflection-enhancing coatings that may be provided.

In addition, a further layer with laterally structured opacity is provided between the first opaque layer or first pressure-accepting layer and the second opaque layer. This can be the reflection-enhancing coating itself, which has gaps or recesses.

In addition, each opaque layer can also be designed as an additional print acceptance layer, so that additional print images, even inside the security substrate, are possible.

A translucent color can be printed above or below the reflection-enhancing coating, so that the optically variable effect is influenced in terms of its color impression.

A tactile embossing can be formed on the outside of the security substrate, preferably in the form of a steel engraving print.

Each of the intended colored printing elements can be applied at least in part over the relief structure and the reflection-enhancing coating in such a way that the optically variable effect appears in a color influenced by the colored printing element.

Within the scope of the invention, a value document is of course also provided which has been produced from a security substrate of the type described and is individualized by printing on one of the provided print acceptance layers, in particular by a printed serial number, etc.

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

Embossing processes, in particular direct exposure techniques, e.g. using a laser writer, can be used to produce the security substrate. The original of the embossed structure is written into a substrate coated with photoresist using direct exposure with the help of a laser writer and the exposed portion of the photoresist is then removed. More complex processes for producing the original, such as electron beam or "focused ion beam" exposure processes, allow the embossed structure to be designed particularly finely. The original exposed in this way 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 embossing 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. B. 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 vapor deposition under vacuum. Finally, the film is laminated together with the intermediate layer.

It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without departing from the scope of the present invention.

Fig. 1

eine Draufsicht auf eine Banknote,

Fig. 2 und 3

Schnittdarstellungen für verschiedene Ausführungsformen für das Sicherheitssubstrat, aus dem die Banknote der Fig. 1 hergestellt ist, und

Fig. 4 und 5

Vorder- und Rückseitenansicht einer weiteren Banknote.

The invention is explained in more detail below by way of example with reference to the accompanying drawings, which also disclose features essential to the invention. They show:

Fig.1

a top view of a banknote,

Fig. 2 and 3

Sectional views of different embodiments for the security substrate from which the banknote of the Fig.1 is manufactured, and

Fig. 4 and 5

Front and back view of another banknote.

Fig.1 shows schematically a banknote 1 with a fully embossed surface structure, which is constructed from a substrate body 2 that forms a security substrate and has a height H and a width B. The substrate body 2 thus covers a plan view, which in Fig.1 It is shown in a first embodiment, which is the sectional view of the Fig. 2 shows, constructed from a film that covers the same area. These and other variants for the construction of the substrate body are explained below using the other figures.

In Fig.1 It can be seen that banknote 1, which is an example of a value document, appears to an observer from the front, which is in Fig.1 is shown, provides a representation 3 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 9 in which the banknote is partially transparent. In the window 9, for example, see-through effects , ie a motif visible on the front is complemented by a motif visible on the back to form another motif.

The substrate body 2 with the height H and the width B is made up of at least one first carrier film of the same or smaller dimensions. In the embodiments, the carrier film covers at least 50% of the specific area, preferably the entire area.

The sectional views of the Figures 2 and 3 differ in terms of the embodiment of the substrate body 2. They have in common that a relief structure is provided. In the embodiments of the Fig.3 the substrate body 2 comprises several carrier films, in the embodiment of the Fig.2 a carrier film.

The substrate body 2 has a first (and in the embodiment of the Fig.2 also single) carrier foil 10, on which a first relief structure 11 is formed in a suitable (not shown) embossing lacquer layer. This can be formed as a microstructure 12, for example as a diffractive hologram structure, as a subwavelength structure 13 and/or as a micromirror structure 14. How Fig.2 shows, different types of structures can be used in the relief structure 11. The structures are provided with a reflection-enhancing coating 15 on their upper side. An opaque layer 17 is arranged above the reflection-enhancing coating 15 by means of a leveling intermediate layer, for example in the form of a lamination 16, on which an opaque layer 17 is formed. A colored printing element 19 is printed on this.

Fig.3 shows an embodiment with a substrate body 2 made of several carrier films. Here, the opaque layer 17 is located on a second carrier film 20, which lies between the first relief structure 11 and the opaque layer 17. The lamination 16 is not only provided above the first relief structure 11, but also on the underside of the first carrier film 10, since a third carrier film 21 is optionally provided on the underside of the first carrier film 10, which has on its underside, i.e. the side facing away from the first relief structure 11, a second opaque layer 22 and a second print acceptance layer 23 for a (in Fig.3 not shown) second colored printing element. The use of additional carrier foils facilitates production, since the first relief structure 11, the first and second opaque layers 17, 22 and print acceptance layer 18, 23 are each produced on their own carrier foils and then in the direction of the symbolically Fig. 3 The arrows entered are joined together by the lamination 16.

A second relief structure with a reflection-enhancing coating is optionally formed on the underside of the first carrier film 10 or on the top side of the third carrier film 21. The same applies to this structure as has been said for the first relief structure.

Fig.3 shows a further optional feature, namely that windows 24 can be provided in the first and second opaque layers 17, 22 and the pressure-accepting layer 18, 23, the mode of operation of which has already been explained in the general part of the description. They can, unlike in Fig.3 shown, can also be formed in an identical lateral position. The pressure-accepting layer can also be combined with the opaque layer in the embodiments.

The Fig. 4 and 5 show exemplary designs for a substrate body 2 once from the front ( Fig.4 ) and once from the back ( Fig.5 ). Here, reference numeral 25 designates a security feature with micromirrors in a window design, reference numeral 26 designates surface micromirror effects, reference numeral 27 designates relief structures that produce hologram effects, and reference numeral 28 designates translucent colors on a micromirror structure as a relief structure. Furthermore, the first print acceptance layer 18 is provided on the front side, on which a first colored printing element 29 is formed, here essentially covering the entire front side.

Fig.5 shows the view from the back, corresponding to the bottom in Fig.3 . In addition to the Fig.3 In addition to the elements shown, there is a further, second relief structure with a reflection-enhancing coating on the back of the first carrier film 10, so that the micromirror structures are also present on the back. The transparent window 30 already visible on the front is of course also visible on the back. Furthermore, the second relief structure, which is formed on the back of the carrier film 10, comprises holograms 31, and a colored printing element 32 is also applied to the lower print acceptance layer 23. Reference number 33 designates translucent colors on a micromirror structure as a relief structure.

Although this is self-evident due to the optical requirements, it should be noted that the carrier films are naturally transparent. The same applies to the embossed lacquer coating in which the relief structures are formed. <b><u>List of reference symbols</u></b> 1 Banknote 23 second pressure acceptance layer 2 Substrate body 24 Window 3 Depiction 25 Security feature with micromirrors 4 background 26 Micromirror effects 5 Moire image 27 Relief structures producing hologram effects 6 hologram 28 translucent colours 7 Value indication 29 first coloured printing element 8th serial number 30 transparent window 9 Window 31 Holograms 10 first carrier film 32 second coloured printing element 11 first relief structure 33 translucent colours 12 Microstructure 13 Subwavelength structure 14 Micromirror structure 15 reflection-enhancing coating 16 Lamination 17 first opaque layer 18 Pressure acceptance layer 19 colored printing element 20 second carrier film 21 third carrier film 22 second opaque layer

Claims (15)

1. Security substrate for documents of value, such as a banknote (1), a cheque, a credit card or other payment card, an identity card or the like, which has a front and a back side, covers a given area when seen in plan view and has:

   - a first carrier film (10), which extends over at least 50% of the given area,

   - a substantially opaque layer (17), which is arranged on top of the first carrier film (10) and covers at least 25%, preferably more than 50% and particularly preferably more than 75% of the given area,

   - a first print receiving layer (18) arranged on top of the opaque layer (17), and

   - at least one relief structure (14, 15), which is arranged between the first opaque layer (17) and the first carrier film (10) and is provided with a reflection-increasing coating (15), which together with the relief structure (11) or on its own produces an optically variable effect, where

   a second substantially opaque layer (22) is arranged on a side of the relief structure (11) that is situated opposite the first opaque layer (17), and a second print receiving layer (23) and a second coloured print element (32) applied thereto are also formed on this side, and

   a further layer with a laterally structured opacity is arranged between the first opaque layer (17) and the second opaque layer (22), so that a light/dark representation is visible when viewed in transmitted light.
2. Security substrate for documents of value, such as a banknote (1), a cheque, a credit card or other payment card, an identity card or the like, which has a front and a back side, covers a given area when seen in plan view and has:

   - a first carrier film (10), which extends over at least 50% of the given area,

   - a first print receiving layer (18) which is arranged on top of the first carrier film (10), is substantially opaque and covers at least 25%, preferably more than 50% and particularly preferably more than 75% of the given area, and

   - at least one relief structure (14, 15), which is arranged between the first print receiving layer (18) and the first carrier film (10) and is provided with a reflection-increasing coating (15), which together with the relief structure (11) or on its own produces an optically variable effect, where

   a second substantially opaque layer (22) is arranged on a side of the relief structure (11) that is situated opposite the first print receiving layer (18), and a second print receiving layer (23) and a second coloured print element (32) applied thereto are also formed on this side, and

   a further layer with a laterally structured opacity is arranged between the first print receiving layer (18) and the second opaque layer (22), so that a light/dark representation is visible when viewed in transmitted light.
3. Security substrate according to Claim 1 or 2, characterized in that the further layer is formed by the reflection-increasing coating (15), which is provided with gaps or cutouts to vary the laterally structured opacity.
4. Security substrate according to Claim 1 or 2, characterized in that at least a first coloured print element (29) is applied on the first print receiving layer (18).
5. Security substrate according to one of Claims 1 to 4, characterized in that the first opaque layer (17), or first print receiving layer (18), is arranged on a second carrier film (20), which lies between the first opaque layer (17), or first print receiving layer (18), and the relief structure (11).
6. Security substrate according to one of Claims 1 to 5, wherein a window (24) is formed in the first opaque layer (17), or first print receiving layer (18), and/or the second opaque layer (22) - if the latter is present - so that the security substrate is transparent in the region of the window (24) or the relief structure (11) with the reflection-increasing coating (15) is visible through the window (24) in the opaque layer (17, 22) or first print receiving layer (18).
7. Security substrate according to Claim 6, characterized in that the windows (24) in the first and in the second opaque layer (17, 22), or first print receiving layer (18), at least partially overlap when seen in plan view.
8. Security substrate according to one of Claims 1 to 7, wherein the first opaque layer (17), or first print receiving layer (18), and/or the second opaque layer (22) - if the latter is present - is a white layer.
9. Security substrate according to one of Claims 1 to 8, characterized in that the relief structure (11) is in the form of a sub-wavelength structure (13) in certain portions and has a periodicity of 150 nm to 500 nm there or is aperiodic with a structure width of 150 nm to 500 nm there.
10. Security substrate according to one of Claims 1 to 9, wherein the first opaque layer (17), or first print receiving layer (18), and/or the second opaque layer (22) - if the latter is present - has a laterally structured opacity, so that a light/dark representation is visible when viewed in transmitted light.
11. Security substrate according to one of Claims 1 to 10, wherein the first opaque layer (17), or first print receiving layer (18), and/or the second opaque layer (22) - if the latter is present - is in the form of a further print receiving layer (23).
12. Security substrate according to one of Claims 1 to 11, wherein a translucent chromatic colour (28) which influences a perception of the colour of the optically variable effect is printed on top of or underneath the reflection-increasing coating (15).
13. Security substrate according to one of Claims 1 to 12, wherein a tactile embossment is formed on an outer side, preferably in the form of a siderography print.
14. Security substrate according to one of Claims 1 to 13, wherein the first coloured print element (29) and/or the second coloured print element (32) - if the latter is present - is mounted at least in regions on top of the relief structure (11) and the reflection-increasing coating (15), so that the optically variable effect appears in a colouring influenced by the print element (19) .
15. Document of value having a security substrate according to one of Claims 1 to 14, wherein the document of value is customized by a print on the first print receiving layer (18) and/or the second print receiving layer (23) - if the latter is present -, in particular a printed serial number (8).

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