EP3939801B1 - Valuable document - Google Patents

Description

The invention relates to a document of value with a paper substrate having a front and a back, the front of the paper substrate being provided with a film security element, the film security element area being recognizable in the form of a light-dark effect when the back of the paper substrate is viewed in incident light, and the film security element area when viewing the back of the paper substrate in transmitted light, it is only recognizable in a uniform shade of gray, so that when the observer changes from viewing the back of the paper substrate from reflected light to transmitted light, he perceives a disappearance of an embossed structure motif that can be seen lightly against a dark background.

A value document within the meaning of the invention can be, for example, banknotes or identity documents, but also shares, certificates, stamps, cheques, admission tickets, tickets, airline tickets, ID cards, visa stickers or the like, as well as labels, seals, packaging or other elements. In the following, the simplified designation "document of value" therefore always includes documents of the type mentioned. The term document of value also includes security paper for the production of banknotes.

For security purposes, documents of value are generally equipped with security elements which allow the authenticity of the document of value to be checked and which at the same time serve as protection against unauthorized reproduction of the document of value. Foil security elements, for example, can be considered as security elements, which have a foil substrate or Have plastic substrate and be applied by means of an adhesive layer on the value document substrate.

In order to increase protection against forgery, it is known to combine such film security elements with continuous openings or perforation areas in the documents of value.

The WO 95/10420 A1 describes a document of value in which the carrier is provided with a window-like opening which is closed with a covering film which is transparent at least in some areas, the covering film being able to be provided with additional security features, for example diffraction structures, particularly in the region of the window-like opening.

The WO 2005/025891 A2 describes a data carrier with a foil security element, both the foil security element and the data carrier having a perforation area; the perforation areas preferably overlap at least partially and particularly preferably they are congruent. In a further variant, the perforation area in the data carrier is covered with a further film on the side facing away from the data carrier side carrying the film security element.

The WO 2010/000432 A1 describes a document of value with an opening which is closed on one side with a translucent film. To increase security against forgery, both the top and the bottom of the document of value are covered with a translucent coating, which is preferably implemented over the entire surface.

Preferably, the coatings are each independently extruded or laminated.

The WO 2011/015622 A1 describes a document of value with an opening which is closed on one side with an at least partially translucent or transparent film, there being a coating on the side of the document of value opposite the film in the area of the opening and essentially in the area of the film surface, with the coating inside the Opening does not exist or essentially does not exist.

The WO 2014/108329 A1 describes a method for producing an endless paper web for the production of security and valuable documents. The paper web is first provided with a continuous opening. A film with security features to be applied to the paper web is then applied in register.

WO 2014/023415 A1 discloses a document of value comprising a substrate with a front side and a back side, the front side of the substrate being provided with a film security element having a front side and a back side in an area referred to as the film security element area, the front side of the film security element having a reflective embossed structure based on tilting of the foil security element has a motif which develops an optically variable effect and is referred to as an embossed structure motif; the film security element area is recognizable in the form of a light-dark effect when viewing the rear side of the substrate in incident light, the embossed structure motif being lightly perceptible against a dark background; the area of the film security element is only recognizable in a uniform color when viewing the rear side of the substrate in transmitted light, so that when the viewer changes from viewing the rear side of the substrate from reflected light to transmitted light, the embossed structure motif, which can be seen lightly against a dark background, disappears .

WO 2014/023415 A1 does not disclose that the substrate is a paper substrate and that a uniform shade of gray appears in transmitted light.

The object of the invention is to provide a document of value provided with a film security element, the document of value being improved in terms of the ability to check its authenticity and in terms of protection against unauthorized reproduction of the document of value.

This object is achieved by the combination of features defined in the main claim. Further training is the subject of dependent claims.

Detailed Description of the Invention

In terms of this invention, observation in incident light is illumination of the document of value from one side and observation of the document of value from the same side. Observation in reflected light is therefore present, for example, when the front side of the document of value is illuminated and also viewed.

A viewing in transmitted light is one within the meaning of this invention

Illuminating a document of value from one side and viewing the document of value from another side, in particular the opposite side. An observation in transmitted light is therefore present, for example, when the back of the document of value is illuminated and the front of the document of value is viewed. The light thus shines through the document of value.

The document of value mentioned in the present description can be, for example, a banknote, in particular a paper banknote, a polymer banknote or a foil composite banknote, a share, a bond, a document, a voucher, a check, a high-quality entrance ticket, but also an authorization card, an ID card or a passport personalization page.

The film security element mentioned in the present description can be, for example, a patch or a label, an (endless) strip or an (endless) thread.

The value document substrate is in particular a paper substrate or a paper-like substrate. According to a preferred embodiment, the value document substrate is based on a film composite substrate with a multi-layer film/paper/film structure. Value document substrates with a paper middle layer, the front and back of which is covered by a film, are from WO 2004/028825 A2 known. According to a further preferred embodiment, the value-document substrate has a multi-layer paper/plastic/paper structure. From the WO 2006/066431 A1 a multi-layer substrate is known which comprises at least one first paper ply, at least one second paper ply, and at least one plastic layer of at least one thermoplastic polymeric material arranged between the paper plies and connected to the paper plies.

In the prior art, watermarks in paper are common, inter alia, as a security feature in banknotes and stamps and in personal documents. Watermarks, which are also referred to herein as “genuine” watermarks, are image marks introduced into paper through different paper thicknesses and recognizable by light transmission. The present invention is based on the finding that, particularly in the case of a thin paper substrate provided with a special film security element on its front side, a Observing the back of the paper substrate in reflected light can be simulated recognizable watermark, which, in contrast to a real watermark in transmitted light, does not come into its own, but surprisingly disappears. On its front side, the special film security element has an embossed structure motif based on a reflective embossed structure that unfolds an optically variable effect when the film security element is tilted is perceptible as a result of differently reflecting mosaic elements in front of a dark background, in particular in multitonal form or in the form of a gray scale image.

In order to achieve a particularly effective motif shimmering through the paper in multitonal form or in the form of a grayscale image when viewing the back of the paper substrate in reflected light, it is advantageous to make the layer thickness of the paper substrate in the film security element area smaller than the layer thickness of the paper substrate outside the film security element area , to provide the paper substrate in the area of the film security element, ie diluted. Alternatively, according to a preferred variant, the document of value can be provided in such a way that it is based on a paper/plastic layer/paper composite substrate, each with thin paper, and the composite substrate has the layer sequence first paper substrate, plastic layer, second paper substrate, with the film security element, for example, between the plastic layer and the second paper substrate is arranged. Alternatively, according to a further preferred variant, the document of value can be provided in such a way that the document of value is based on a foil/paper/foil composite substrate and the foil security element is arranged between one of the two foils and the paper.

It is preferred that the reflective embossed structure of the film security element in the area of the embossed structure motif is formed in the form of a reflective microstructure with a mosaic made up of a large number of reflective mosaic elements, the mosaic elements being characterized by the parameters size, outline shape, relief shape, reflectivity and spatial orientation and a form a predetermined motif in that different groups of mosaic elements with different characteristic parameters reflect incident light in different areas of the room. The simulated watermark shimmering through the paper is particularly effective in the case of a relief structure forming a micromirror arrangement, which is also referred to herein as a micro-optical relief structure. The production of a micro-optical relief structure is known in the prior art (see, for example, WO 2014/060089 A2 ). The dimensions of the structural elements of the micromirror arrangement are preferably in a range that is greater than 1 μm and less than 40 μm, with a range greater than 1 μm and less than 30 μm being particularly preferred. The dimensions of the structural elements of the micromirror arrangement have, for example, a height of up to 15 μm and a lateral extent of up to 30 μm. In this case, both the height and the lateral extent of the structural elements of the micromirror arrangement are preferably greater than 1 μm.

Other preferred micro-optical relief structures are, for example, from WO 2007/079857 A1 known.

The embossed structure is embossed in particular in an embossing varnish, e.g. a UV varnish or a thermoplastic varnish.

The reflective embossed structure of the film security element is preferably formed by a metallization arranged above an embossing lacquer layer, e.g. by an Al or Ag layer.

• einer reflektierenden Schicht (insbesondere einer metallischen, reflektierenden Schicht), z.B. eine Al-Schicht;
• einer semitransparenten Schicht, z.B. eine Cr-Schicht; und
• einer zwischen der reflektierenden Schicht und der semitransparenten Schicht angeordneten dielektrischen Schicht, z.B. eine SiO₂-Schicht,

wobei sich die Farbe des mehrschichtigen Aufbaus mit der Änderung des Betrachtungswinkels ändert.Other preferred reflective embossed structures include, for example, a multilayer structure capable of generating interference

• a reflective layer (particularly a metallic reflective layer), eg an Al layer;
• a semi-transparent layer such as a Cr layer; and
• a dielectric layer, for example an SiO ₂ layer, arranged between the reflective layer and the semi-transparent layer,

the color of the multi-layer structure changes with the change in viewing angle.

It is possible to create a first appearance of the multilayer structure capable of causing interference that is recognizable when viewing the front side in incident light and a second appearance of the multilayer structure capable of causing interference when viewing the front side in transmitted light, e.g. by gaps in the reflective layer and/or the semitransparent layer Layer. Such a film security element with different reflected light / transmitted light appearance is from WO 2009/149831 A2 known. For example, the semi-transparent layer can have a large number of gaps arranged in a grid-like manner, which in their entirety result in a character, an image or a pattern. The pattern created in this way is visible in reflected light and disappears in transmitted light. Alternatively and/or additionally, a different incident light/transmitted light appearance of the multilayer structure be brought about by combining the structure with a relief structure, in particular a diffractive relief structure, a micro-optical relief structure or a sublambda structure.

• die beiden semitransparenten Spiegelschichten werden bevorzugt von Al oder Ag gewählt; die dielektrische Schicht ist insbesondere eine SiO₂-Schicht;
• im Falle, dass jede der beiden semitransparenten Spiegelschichten auf Al beruht, liegt die jeweilige bevorzugte Schichtdicke in einem Bereich von 5 nm bis 20 nm, insbesondere bevorzugt in einem Bereich von 10 nm bis 14 nm; die dielektrische SiO₂-Schicht hat vorzugsweise eine Schichtdicke in einem Bereich von 50 nm bis 450 nm, weiter bevorzugt in einem Bereich von 80 nm bis 260 nm, wobei die Bereiche von 80nm bis 100nm und von 220nm bis 240nm speziell für die Bereitstellung eines Gold/Blau-Farbwechsels besonders bevorzugt werden;
• im Falle, dass jede der beiden semitransparenten Spiegelschichten auf Ag beruht, liegt die jeweilige bevorzugte Schichtdicke in einem Bereich von 15 nm bis 25 nm; die dielektrische SiO₂-Schicht hat vorzugsweise eine Schichtdicke in einem Bereich von 50 nm bis 450 nm, weiter bevorzugt in einem Bereich von 80 nm bis 260 nm, wobei die Bereiche von 80nm bis 100nm und von 220nm bis 240nm speziell für die Bereitstellung eines Gold/Blau-Farbwechsels besonders bevorzugt werden.

Other preferred reflective embossed structures contain, for example, a multi-layer structure with two semi-transparent layers and a dielectric layer arranged between the two semi-transparent layers, the multi-layer structure having different shades of color when viewed in reflected light on the one hand and when viewed in transmitted light on the other hand, in particular when viewed in Incident light appears gold-colored and shows a blue tint when viewed in transmitted light. The two different hues are, in particular, complementary colors. Such a multi-layer structure is based in particular on two semi-transparent mirror layers and a dielectric layer arranged between the two semi-transparent mirror layers. Such a multilayer structure, which appears gold when viewed in reflected light and shows a blue hue when viewed in transmitted light, is, for example, from WO 2011/082761 A1 known. A metal selected from the group consisting of Al, Ag, Ni, Cr, Cu, Au and an alloy of one or more of the above-mentioned elements is particularly suitable as the semitransparent mirror layer, with Al or Ag being preferred as the semitransparent mirror layer and Al is particularly preferred. Suitable multilayer structures with two semi-transparent mirror layers and a dielectric layer arranged between the two semi-transparent mirror layers preferably have the following physical properties:

• the two semi-transparent mirror layers are preferably chosen from Al or Ag; the dielectric layer is in particular an SiO ₂ layer;
• in the event that each of the two semi-transparent mirror layers is based on Al, the respective preferred layer thickness is in a range from 5 nm to 20 nm, particularly preferably in a range from 10 nm to 14 nm; the dielectric SiO ₂ layer preferably has a layer thickness in a range from 50 nm to 450 nm, more preferably in a range from 80 nm to 260 nm, the ranges from 80 nm to 100 nm and from 220 nm to 240 nm being particularly suitable for providing a gold /blue color changes are particularly preferred;
• in the event that each of the two semi-transparent mirror layers is based on Ag, the respective preferred layer thickness is in a range from 15 nm to 25 nm; the dielectric SiO ₂ layer preferably has a layer thickness in a range from 50 nm to 450 nm, more preferably in a range from 80 nm to 260 nm, the ranges from 80 nm to 100 nm and from 220 nm to 240 nm being particularly suitable for providing a gold /Blue color change are particularly preferred.

• im Auflicht Magenta, im Durchlicht Blau-Grün;
• im Auflicht Türkis, im Durchlicht Orange-Gelb;
• im Auflicht Gold, im Durchlicht Blau-Violett;
• im Auflicht Silber, im Durchlicht Violett.

The multi-layered layer structures mentioned not only enable the production of a semi-transparent functional layer, which appears gold-colored when viewed in reflected light and shows a blue hue when viewed in transmitted light, but depending on the choice of layer thickness, in particular the dielectric layer, further color changes can be generated, e.g

• magenta in reflected light, blue-green in transmitted light;
• turquoise in incident light, orange-yellow in transmitted light;
• reflected light gold, transmitted light blue-violet;
• reflected light silver, transmitted light violet.

Further preferred reflective embossed structures contain, for example, a liquid crystal layer which, when viewed in incident light, shows a different color than when viewed in transmitted light. Alternatively and/or in addition a different reflected light/transmitted light appearance can be achieved by combining the liquid crystal layer with a relief structure, in particular a diffractive relief structure, a micro-optical relief structure or a sublambda structure.

Further preferred reflective embossed structures contain, for example, a print layer with an effect pigment composition which shows a different color when viewed in reflected light than when viewed in transmitted light, in particular a gold/blue color change, a gold/violet color change, a green-gold /magenta color change, a violet/green color change or a silver/opaque color change. Such inks are, for example, in the WO 2011/064162 A2 described. Alternatively and/or additionally, a different incident light/transmitted light appearance can be achieved by combining the printed layer with a relief structure, in particular a diffractive relief structure, a micro-optical relief structure or a sublambda structure.

According to a preferred embodiment, the embossed structure motif of the foil security element is formed in the form of characters, in the form of an image or in the form of a code.

It is preferred that the paper substrate is a watermark paper with a watermark motif which is arranged outside the film security element area and is not recognizable when viewing the document of value in incident light and is recognizable when viewing the document of value in transmitted light. In particular, the watermark motif can be formed in the form of characters, in the form of an image or in the form of a code and preferably with the embossed structural motif of the Be identical to the film security element or stand in relation to the embossed structure motif of the film security element or in a supplementary relationship.

The foil security element is preferably a patch, a security strip or a security thread.

It is preferred that the foil security element has a plurality of embossed structure motifs. In the special case that the document of value is based on a paper/foil/paper composite substrate and the composite substrate has the layer sequence first paper substrate, foil, second paper substrate, with the foil security element being arranged between the foil and the second paper substrate, the second paper substrate preferably has a Recess in the area of an embossed structure motif.

According to a preferred embodiment, the document of value according to the invention is a banknote.

Further exemplary embodiments and advantages of the invention are explained below with reference to the diagrammatically greatly simplified figures, in the representation of which a true-to-scale and proportionate reproduction was dispensed with in order to increase clarity.

Figuren 1 bis 6

ein erfindungsgemäßes Wertdokument gemäß einem ersten Ausführungsbeispiel; und

Figuren 7 bis 12

ein erfindungsgemäßes Wertdokument gemäß einem zweiten Ausführungsbeispiel.

Show it:

Figures 1 to 6

an inventive value document according to a first embodiment; and

Figures 7 to 12

an inventive value document according to a second embodiment.

First embodiment

Based on Figures 1 to 6 an inventive value document 1, in the present case a banknote, is illustrated according to a first exemplary embodiment.

The figure 1 shows the front of the bank note 1 when viewed in reflected light. The bank note 1 is based on a paper substrate 2 which is provided with a strip-shaped foil security element 3 on its front side. In the present example, the foil security element 3 has a width of 1.4 cm and a length of 7.5 cm. The film security element 3 comprises a carrier film, in the present case a polyethylene terephthalate (PET) film, a UV-curing embossing varnish provided with a relief structure and an interference-capable, multi-layer, opaque structure which has a reflective layer (e.g. Al), a semi-transparent layer (e.g Cr) and a dielectric layer (eg SiO ₂ ) disposed between the reflective layer and the semi-transparent layer such that the color of the multi-layer structure changes with the change of the viewing angle. In the upper area of the foil security element 3 there is an embossed structure motif in the form of the denomination “20”, which unfolds an optically variable effect when the foil security element 3 is tilted. The embossed structure motif is based on a micro-optical relief structure that is known in the prior art (see, for example, WO 2014/060089 A2 ).

The structure of the foil security element 3 in cross section along the dashed line AA' is explained further below with reference to FIG figure 6 described.

The figure 2 shows the banknote 1 in a cross-sectional view.

The figure 3 shows the front of the bank note 1 when viewed in transmitted light. In transmitted light, the viewer can see the watermark motif 4 in the form of the denomination "20", which appears when the banknote 1 is viewed in reflected light (see figure 1 ) was not recognizable. The watermark motif 4 is a “genuine” watermark that is produced in papermaking by partially thinned areas in the paper.

The figure 4 shows the back of the banknote 1 when viewed in reflected light. The viewer perceives the paper 2 in the area of the foil security element 3 in the form of a dark background, with the denomination "20" formed in the upper area of the foil security element 3 in the form of an embossed structure motif being somewhat lighter in multitonal form against the dark background of the foil security element as a simulated Watermark is visually detectable.

The figure 5 shows the back of the bank note 1 when viewed in transmitted light. The observer perceives the paper 2 in the area of the foil security element 3 in a uniform gray tone. In addition, the watermark motif 4 is visible in the form of the denomination "20", which appears when the bank note 1 is viewed in reflected light (see figure 4 ) was not recognizable.

• das Erscheinen des "echten" Wasserzeichens 4 (siehe Figur 5) gefolgt von einem Verschwinden des "echten" Wasserzeichens 4 (siehe Figur 4); und
• das Nicht-Vorhandensein des simulierten Wasserzeichens in dem Bereich des Papiers 2, der mit dem Foliensicherheitselement 3 versehen ist (siehe Figur 5), gefolgt von einem Erscheinen des simulierten Wasserzeichens (siehe Figur 4).

When repeatedly switching between viewing the back of banknote 1 in transmitted light (see figure 5 ) on the one hand and viewing the back of banknote 1 in incident light (see figure 4 ) on the other hand, the viewer perceives two separate effects that are complementary to each other, viz

• the appearance of the "real" watermark 4 (see figure 5 ) followed by a disappearance of the "real" watermark 4 (see figure 4 ); and
• the absence of the simulated watermark in the area of the paper 2 provided with the foil security element 3 (see figure 5 ), followed by an appearance of the simulated watermark (see figure 4 ).

The figure 6 shows the structure of the in the figure 1 shown film security element 3 in cross section along the dashed line AA '. The foil security element 3 comprises a carrier foil 5, in the example a polyethylene terephthalate (PET) foil. The carrier film 5 is provided with a UV-curing embossing lacquer 6 . In order to produce the embossed structure motif in the form of the denomination “20” that develops an optically variable effect, the embossed varnish 6 has a micro-optical relief structure in a specific area, which is known in the prior art (see, for example, WO 2014/060089 A2 ). The embossing varnish 6 is provided on its upper side with a color-shifting multi-layer structure 7, which has the reflective Al layer, the dielectric layer SiO ₂ and the absorbing or semi-transparent Cr layer.

Second embodiment

Based on Figures 7 to 12 an inventive value document 8, in the present case a banknote, is illustrated according to a second exemplary embodiment.

The figure 7 shows the front of the bank note 8 when viewed in reflected light. The bank note 8 is based on a multi-layer paper/plastic/paper composite substrate 9 with the layer sequence first paper substrate (91)-plastic layer (92)-second paper substrate (93) (see figure 8 ). A foil security element 10 is arranged between the plastic layer (92) and the second paper substrate (93). The film security element 10 comprises a carrier film, in the present case a polyethylene terephthalate (PET) film, a UV-curing embossing varnish provided with a relief structure and an interference-capable, multi-layer, opaque structure which has a reflective layer (e.g. Al), a semi-transparent layer (e.g Cr) and a dielectric layer (eg SiO ₂ ) disposed between the reflective layer and the semi-transparent layer such that the color of the multi-layer structure changes with the change of the viewing angle. The film security element 10 has two embossed structure motifs, which are each formed in the form of the denomination “20” and which develop an optically variable effect when the film security element 10 is tilted. Only the lower embossed structure motif is visible to the observer because the second paper substrate (93) of the composite substrate 9 facing the observer has a square recess. The upper embossed structure motif shown in dashed lines is almost invisible to the viewer because it is covered by the second paper substrate (93) of the composite substrate 9 . The embossed structure motifs of the film security element 10 are each based on a micro-optical relief structure that is known in the prior art (see, for example, WO 2014/060089 A2 ).

The structure of the foil security element 10 in cross section along the dashed line BB' is explained below with reference to FIG figure 12 described.

The figure 8 illustrates the structure of the figure 7 banknote 8 shown in a cross-sectional view along the dashed line C-C'. The composite substrate 9 of the banknote 8 comprises a thin first paper substrate 91, a plastic layer 92 and a thin second paper substrate 93. The foil security element 10 is embedded between the plastic layer 92 and the second thin paper substrate 93. In addition, the thin second paper substrate 93 has a square cutout in a specific area, which can be obtained, for example, by punching or by laser cutting. The recess forms a so-called window area in which the film security element 10 embedded in the composite substrate 9 can be seen by the observer when looking at the front of the bank note 8 .

The figure 9 shows the front of the bank note 8 when viewed in transmitted light. In transmitted light, the viewer can see the watermark motif 11 in the form of the denomination "20", which appears when the banknote 8 is viewed in reflected light (see figure 7 ) was not recognizable. The watermark motif 11 is a “genuine” watermark that is produced by papermaking through partially thinned areas in the paper layers 91, 93 of the composite substrate 9.

The figure 10 shows the back of the banknote 8 when viewed in reflected light. The observer perceives the composite substrate 9 in the area of the film security element 10 in the form of a dark background, with the two denominations "20" formed in the film security element 10 each in the form of an embossed structure motif being somewhat lighter in multitonal form against the dark background of the film security element 10 are visually detectable to a certain extent as a simulated watermark.

The figure 11 shows the back of the bank note 8 when viewed in transmitted light. The observer perceives the composite substrate 9 in the area of the film security element 10 in a uniform gray tone. In addition, the watermark motif 11 is visible in the form of the denomination "20", which appears when the banknote 8 is viewed in incident light (see figure 10 ) was not recognizable.

• das Erscheinen des "echten" Wasserzeichens 11 (siehe Figur 11) gefolgt von einem Verschwinden des "echten" Wasserzeichens 11 (siehe Figur 10); und
• das Nicht-Vorhandensein der simulierten Wasserzeichen in dem Bereich des Verbundsubstrats 9, der das Foliensicherheitselement 10 aufweist (siehe Figur 11), gefolgt von einem Erscheinen der simulierten Wasserzeichen (siehe Figur 10).

When repeatedly switching between viewing the back of the bank note 8 in transmitted light (see figure 11 ) on the one hand and the observation of the back of the banknote 8 in incident light (see figure 10 ) on the other hand, the viewer perceives two separate effects that are complementary to each other, viz

• the appearance of the "real" watermark 11 (see figure 11 ) followed by a disappearance of the "real" watermark 11 (see figure 10 ); and
• the absence of the simulated watermarks in the area of the composite substrate 9 that has the film security element 10 (see figure 11 ), followed by an appearance of the simulated watermarks (see figure 10 ).

The figure 12 shows the structure of the in the figure 7 shown foil security element 10 in cross-section along the dashed line B-B'. The foil security element 10 comprises a carrier foil 12, in the example a polyethylene terephthalate (PET) foil. The carrier film 12 is provided with a UV-curing embossing lacquer 13 . To generate the two respectively embossed structure motifs in the form of the denomination "20" that develop an optically variable effect, the embossed lacquer 13 has a micro-optical relief structure in two specific areas, which is known in the prior art (see, for example, WO 2014/060089 A2 ). The embossing lacquer 13 is provided on its upper side with a color-shifting multi-layer structure 14 which has the reflective Al layer, the dielectric layer SiO ₂ and the absorbing or semi-transparent Cr layer.

The carrier film (5,12) present in the film security elements (3,10) of the exemplary embodiments described above is not obligatory but optional and is advantageous in terms of its supporting mechanical ability, particularly in the event that the value document substrate has a recess covered by the film security element having. An alternative film security element could be provided by using a release-capable (temporary) carrier film that is removed before or after the film security element is applied to the document-of-value substrate. In this way, foil security elements arranged on the value document can be produced with a small layer thickness.

Claims (13)

1. Document of value (1, 8) comprising a paper substrate (2) having a front side and a back side, wherein

   - the front side of the paper substrate, in a region designated as foil security element region, bears a foil security element (3, 10) having a front side and a back side, wherein the front side of the foil security element has a motif which is based on a reflective embossed structure, develops an optically variable effect when the foil security element is tilted, and is designated as embossed structural motif;

   - the foil security element region, when the back side of the paper substrate is viewed in reflected light, is discernible in the form of a light-dark effect, wherein the embossed structural motif is perceptible as light against a dark background, more particularly in multitonal form or in the form of a greyscale image;

   - the foil security element region, when the back side of the paper substrate is viewed in transmitted light, is discernible only in a unitary grey tone, so that the viewer, on changing the viewing of the back side of the paper substrate from reflected-light viewing to transmitted-light viewing, perceives a disappearance of the embossed structural motif perceptible as light against a dark background.
2. Document of value according to Claim 1, wherein the layer thickness of the paper substrate in the foil security element region is lower by comparison with the layer thickness of the paper substrate outside the foil security element region; in the foil security element region, therefore, the paper substrate is thinned.
3. Document of value according to Claim 1, wherein the document of value is based on a paper/plastic/paper composite substrate (9) and the composite substrate has the layer sequence of first paper substrate (91), plastic (92) and second paper substrate (93), wherein the foil security element is disposed between the plastic and the second paper substrate and the paper substrate defined in Claim 1 forms the first paper substrate in the composite substrate.
4. Document of value according to Claim 1, wherein the document value is based on a foil/paper/foil composite substrate and the foil security element is disposed between one of the two foils and the paper, wherein the paper substrate defined in Claim 1 forms the paper in the composite substrate.
5. Document of value according to any of Claims 1 to 4, wherein the reflective embossed structure of the foil security element in the region of the embossed structural motif takes the form of a reflective microstructure having a mosaic composed of a multiplicity of reflective mosaic elements, wherein the mosaic elements are characterized by the parameters of size, outline shape, relief shape, reflectivity and spatial orientation and form a predetermined motif, by different groups of mosaic elements having different characteristic parameters reflecting incident light into different spatial regions.
6. Document of value according to any of Claims 1 to 5, wherein the embossed structural motif of the foil security element takes the form of indicia, the form of an image or the form of a coding.
7. Document of value according to any of Claims 1 to 6, wherein the paper substrate is a watermark paper having a watermark motif (4) which is disposed outside the foil security element region and which is non-discernible when the document of value is viewed in reflected light and discernible when the document of value is viewed in transmitted light.
8. Document of value according to Claim 7, wherein the watermark motif takes the form of indicia, in the form of an image or the form of a coding and preferably is identical to the embossed structural motif of the foil security element or is contextual with or complementary to the embossed structural motif of the foil security element.
9. Document of value according to any of Claims 1 to 8, wherein the foil security element is a patch, a security strip or a security thread.
10. Document of value according to any of Claims 1 to 9, wherein the reflective embossed structure of the foil security element is formed by a metallization disposed above an embossing varnish layer (6), more particularly by a colour-flopping multi-layer construction (7) or by a multi-layer construction with colour change on a change from reflected-light viewing the transmitted-light viewing.
11. Document of value according to any of Claims 1 to 10, wherein the foil security element has a plurality of embossed structural motifs.
12. Document of value according to Claim 11 with reference to Claim 3, wherein the second paper substrate has a slot in the region of an embossed structural motif.
13. Document of value according to any of Claims 1 to 12, wherein the document of value is a banknote.

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