EP1503903A2

EP1503903A2 - Security element comprising metallic layers

Info

Publication number: EP1503903A2
Application number: EP03718785A
Authority: EP
Inventors: Manfred Heim; Christian Schmitz
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2002-04-26
Filing date: 2003-04-23
Publication date: 2005-02-09
Anticipated expiration: 2023-04-23
Also published as: ZA200408360B; CN1652945A; JP4493004B2; CA2483467C; EP1503903B1; RU2004134572A; BRPI0309564B1; KR101205588B1; DE10218897A1; BR0309564A; RU2314930C2; UA84401C2; WO2003091042A3; CA2483467A1; JP2005528997A; PL371494A1; AU2003222834A1; EP1503903B9; WO2003091042A2; CN1652945B

Abstract

The invention relates to a security element for security documents, bank notes, identity cards, or the like. Said security element comprises a substrate on which at least two metallic layers having different optical densities are arranged.

Description

Security element and process for its manufacture

The invention relates to a security element for security papers, banknotes, identity cards or the like, as well as a security paper and a value document with such a security element. Furthermore, the invention relates to methods for producing the security element or the security paper and the value document with such a security element.

A security thread is proposed in EP 0 330 733 A1, which can be checked both visually and by machine. For this purpose, a translucent plastic film is coated with metal and this coating is provided with cutouts in the form of characters or patterns. In addition, the security thread contains coloring and / or luminescent substances in the areas congruent with the cutouts, by means of which the characters or patterns differ from the opaque metal coating in contrasting colors under suitable lighting conditions. An aluminum layer is preferably used as the metal layer. This security thread is embedded in so-called "window security thread" in security paper, ie it is virtually woven into the paper during the formation of the security paper, so that it is freely accessible at regular intervals on the surface of the paper and is completely embedded in the paper only in the intermediate areas is.

This security thread already meets a very high security standard. The continuous metallic coating enables the electrical conductivity to be checked mechanically, while the recesses serve as a visual authenticity feature that can be recognized by the viewer in transmission. In addition, the thread has an additional feature that is not readily recognizable by the viewer, namely the Luminescence in the area of the cutouts, which can also be checked mechanically. When a quick glance at banknotes that have such a security thread, the metallic gloss of the window areas is particularly striking. This gloss can be imitated by simply sticking on aluminum foil elements. In the case of a fleeting inspection only in incident light, such counterfeits could therefore be considered real banknotes.

The invention is therefore based on the object of proposing a security element as well as a security paper and a value document which has increased security against forgery in comparison with the prior art.

This object is solved by the features of the independent claims. Further training is the subject of the subclaims.

According to the invention, the security element has a substrate on which at least two metal layers with different optical densities are preferably arranged one above the other and / or preferably on the same side of the substrate. At least the optically denser layer preferably has cutouts, ie that at least in a partial area on the substrate there is only the optically thinner layer of the at least two metal layers with different optical densities. In the event that the metal layers are arranged one above the other, the two metal layers in particular adjoin one another directly, ie there are no further layers between the metal layers. The optical impression of such a security element can be imitated, if at all, only with a great deal of effort, in particular if differently colored metal layers in complicated patterns with precisely defined layer thick are applied, which may also be intertwined.

The metal layers have a different optical density, i.e. they show different transmission behavior. The optically denser metal layer of the at least two metal layers, hereinafter referred to as metal layer A, shows a lower transmission, preferably at most 30%, particularly preferably at most 10%. The optically thinner metal layer of the at least two metal layers, hereinafter referred to as metal layer B, shows a higher transmission than layer A, preferably more than 10%, particularly preferably 25 to 80%. Particularly attractive effects result if the metal layer A has a transmission of at most 10% and the metal layer B has a transmission of at least 50%.

The metal layer A is perceived by the viewer as opaque due to the lower transmission, while the metal layer B shows semi-transparent properties.

In this context, “semitransparency” is to be understood as translucency, i.e. the layer has a light transmission of less than 90%, preferably between 80% and 20%.

The functional relationship between transmission T and optical density OD is formulated as follows: OD = log l∞

T [%] The transmission values are preferably determined in the visually visible spectral range, particularly preferably at a wavelength of 500 nm.

The optical density of a metal layer also depends, among other things, on the metal used and the layer thickness. Depending on the type of metal and which transmission properties are to be achieved, a rough guide value for the metal layer A is a layer thickness of approximately 20 to 300 nm and for the metal layer B a layer thickness of approximately 2 to 20 nm.

The metal layers can be applied next to one another, overlapping or one above the other on the substrate.

Basically, the order of layers of the metal layers can be arbitrary. The designation metal layer A and metal layer B does not reflect the order in relation to a carrier, but is only intended to enable a linguistically easier distinction between optically dense and less dense layers. For example, in the case of the layers lying one above the other, the optically denser and then the optically thinner metal layer can be applied to the substrate first. The layer order can be reversed just as well. Which layer sequence is more suitable depends on the individual case.

In the embodiment according to the invention, the metal layers are preferably arranged one above the other. In particular, the metal layers arranged one above the other directly adjoin one another, ie no further layer is arranged between the metal layers A and B. The metal layers A and B can consist of the same material, but also of a different material. When combining different metals, the color combinations gold / silver, gold / copper, chrome / gold, chrome / copper are particularly suitable.

The metals can be, for example, aluminum, cobalt, copper, gold, iron, chromium, nickel, silver, platinum, palladium, titanium or other “non-ferrous metals” and any alloys thereof, such as Inconel, gold bronzes, silver bronzes etc. Aluminum is preferably used for the optically denser layer A because of its shallow depth of penetration for visible light and easier processing, and gold, copper, chromium, silver or iron as optically thinner layer B because of its great depth of penetration for visible light and its characteristic color.

Some preferred material combinations are summarized in the table below.

T: transmission

O: Visually perceptible color contrast

M: With a corresponding thickness, machine-readable magnetism is created in

Layer A D / A: the incident light appears homogeneously metallized in incident light; recesses can be seen in 0 transmitted light.

The security against counterfeiting can be further increased if the recesses, i.e. the places where the optically denser layer is not present or which are metal-free, are not only simple in shape, but are in the form of alphanumeric characters, patterns, logos or the like or are also arranged in the form of a code, for example a bar code. With an appropriate thickness, the optically denser metal layer can additionally have magnetic properties. With a suitable arrangement of the cutouts, machine-readable coding can even be introduced into the security element.

The substrate of the security element is preferably a plastic film. This can also be provided with diffraction structures in the form of a relief structure. The diffraction structures can be any diffraction-optical structures, such as holograms or grating structures (e.g. Kinegramme®, pixelgrams) or the like.

It is also possible for the substrate to consist of foils laminated together. In particular, two foils can be laminated together, each with a metal layer on the outside of a foil.

In the following, the different variants in the layer material and structure in combination with recesses and diffraction structures and their different appearances are described. Of course, all variants can be combined with each other in any way.

Variant 1: metal layers made of the same material

In this embodiment, the metal layers A and B are made of the same material. For example, as metal layers A and B

Aluminum can be evaporated onto the substrate. The different optical densities of the individual layers are achieved, for example, by varying the layer thickness. The layer sequence in the security element is, for example, substrate, optically thin metal layer B, optically dense metal layer A. Alternatively, the layer structure can also be substrate, optically dense metal layer A, optically thin metal layer B. All three layers are preferably directly one above the other and are not separated from one another by further layers. The optically dense metal layer A is not applied over the entire surface, ie the layer A, which appears opaque, has cutouts.

If this security element is viewed in transmitted light, the areas not covered with the opaque layer A can be clearly recognized as translucent areas. Depending on how the transmission properties of the optically thin metal layer B have been set, the viewer believes that despite the existing metal coating B in the area of the cutouts in layer A, he can perceive fully transparent areas to semi-transparent areas.

In incident light, the security element appears as a uniform, fully coated surface. The recesses are therefore not visible.

In addition to the cutouts in the metal layer A, there may also be cutouts in the metal layer B. Effective effects always result when the layers A and B lie on top of each other and some of the cutouts in the metal layers A and B are at least partially on top of each other and are preferably arranged congruently, or are on top of each other and preferably the cutouts in the metal layer A are larger than the cutouts in the semi-transparent metal layer B. The cutouts in one or both metal layers can be arranged in any shape, combination and order.

In addition, the security element can be equipped with diffraction structures. These are preferably introduced, preferably embossed, at least in partial areas of the substrate surface, the metal layers coming to lie on the substrate surface with the diffraction structures. The coating sequence will preferably be substrate with diffraction structure / metal layer A / metal layer B.

The diffraction structures are particularly brilliantly visible at those places where there is a metal layer, i.e. no recess. In the area of the cutouts, the diffraction structures are very weak to invisible in transmitted light. In the reflected light, the diffraction structures are visible both in the area of the metal layer and in the area of the cutouts.

Variant 2: metal layers made of different materials

In this embodiment, the metal layers A and B are made of different materials. For example, aluminum can be evaporated onto the substrate as metal layer A and gold as metal layer B. The different optical densities of the individual layers are e.g. achieved by varying the layer thickness and / or the material.

The layer sequence in the security element and the arrangement of the cutouts in the individual layers can be as described in variant 1. If this security element is viewed in transmitted light, the cutouts in layer A can be clearly recognized as translucent areas. Depending on how the transmission properties of the optically thin metal layer B have been set, the viewer believes that despite the existing metal coating B in the area of the cutouts in layer A, he can perceive fully transparent areas to semi-transparent areas. If necessary, the semitransparent areas stand out in color due to the different materials in layers A and B.

In incident light, the security element does not appear as a uniform, fully coated surface, but shows a different appearance in the areas that are not coated with the optically denser metal, namely surfaces in the color tone of the second metal. The recesses in the metal layer A are therefore also visible in incident light and have the color of the metal layer B.

In addition to the cutouts in the metal layer A, there may also be cutouts in the metal layer B. Effective effects always result when the layers A and B lie on top of one another and some of the cutouts in the metal layers A and B lie at least partially on top of one another and are preferably arranged congruently or lie on top of one another and preferably the cutouts in the metal layer A are larger than the recesses in the semi-transparent metal layer B.

The cutouts in one or both metal layers can be arranged in any shape, combination and order. In addition, the security element can be equipped with diffraction structures. These are preferably introduced, preferably embossed, at least in partial areas of the substrate surface, the metal layers coming to lie on the substrate surface with the diffraction structures. The coating sequence is preferred

Be substrate with diffraction structures / metal layer A / metal layer B.

The diffraction structures are particularly brilliantly visible at those places where there is a metal layer, i.e. no recess. In the reflected light, the diffraction structures can also be seen at the recesses.

The following description is not limited to variants 1 and 2 but is to be understood in general and applies equally to all embodiments.

The security element can be a security thread that consists of a self-supporting plastic film on which the various metal layers are applied. This security thread can be at least partially incorporated into a security paper or security document. If the security thread is designed so that it looks identical from the front and back, there is no need to even pay attention to the correct insertion. However, it is also conceivable to design the security element in the form of a tape or label and to fasten it on the surface of the security paper or value document.

Alternatively, the security element can also be designed as a transfer element or laminating film. This variant is particularly advantageous if the security element is arranged completely on the surface of the security paper or value document. In this case, the layer structure of the security element is prepared on a carrier film, usually a plastic film, and then transferred, for example in a hot stamping process, in the desired outline contours to the security paper or document of value.

If the security element is arranged on the surface of the security paper or value document, it can have any outline structures, such as round, oval, star-shaped, rectangular, trapezoidal or stripe-shaped outline contours.

According to a preferred embodiment, the security paper or value document to which the security element is applied has a continuous opening. The security element is arranged in the area of the opening and projects beyond it on all sides.

In another preferred embodiment, the security paper or document of value has a security element in the form of a security thread.

In both embodiments, the security element can be checked from the front and back of the paper or document, which significantly simplifies the authenticity check even for the inexperienced viewer.

Imitation of the color effect is therefore particularly difficult or completely impossible in these embodiments. However, the use of the security element according to the invention is not limited to the area of security documents. The security element according to the invention can also be used advantageously in the field of product security for counterfeiting security of any goods. For this purpose, the security element can have additional anti-theft elements, such as a coil or a chip. The same applies to the security paper or value document provided with such a security element.

The metal layers are preferably applied using a vacuum evaporation system, e.g. by means of sputtering or by means of electron beam vapor deposition.

The cutouts in the respective metal layers are preferably produced with the aid of a washing process, as described in WO 99/13157, to which reference is expressly made here. The security elements are prepared as a security film that has several uses of the security element. The base material forms a self-supporting, preferably transparent, plastic film. In the case of security threads or labels, this plastic film corresponds to the plastic layer of the security element according to the invention. If the security elements are detached from an embossing film, the plastic film forms the carrier material of this transfer material, to which the plastic layer is applied in the form of a lacquer layer. Diffraction structures can be embossed into this lacquer layer or, in the case of security threads or labels, into the plastic film. The plastic layer of the security element according to the invention is preferably printed in gravure in the form of the later cutouts. A printing ink with a high pigment content is used for this, which has a porous, raised Paint application forms. Then the different colored metal layers are evaporated onto the printed plastic layer. In a final step, the paint application and the metal layer above it are removed by washing out with a liquid, possibly combined with mechanical action. A water-soluble printing ink is preferably used, so that water can be used as the liquid. This process is therefore very environmentally friendly and does not require any special protective measures. This method also has the advantage that the cutouts for both or more metal layers are produced in one operation.

The washing out can be supported by mechanical means, such as a rotating roller, brush or ultrasound.

As an alternative to vapor deposition of the layers on a substrate, the layers can be applied to a substrate in each case. The coated substrates are then laminated together, preferably in such a way that the coated sides of the substrates come to lie with one another.

Due to the fact that the security element according to the invention cannot be imitated by simple technical means and any attempt to readjust it is easy to recognize, but also due to the color and transmitted light / incident light effects that are easily recognizable for a viewer, the security element according to the invention shows one enormously improved counterfeit security. In particular, the security element cannot be produced simply by punching out the film, etching away or scraping off the metal layer, since the metallization technology must be mastered while at the same time controlling the layer thicknesses exactly. Further embodiments and advantages of the security element or security paper and value document according to the invention are explained with reference to the figures. The representations are schematic and do not necessarily correspond to the actual proportions and proportions.

Show it:

1 shows a document of value according to the invention,

Fig. 2a layer structure and section through an inventive

Security element along the line A - A,

2b the security element according to FIG. 2a in supervision with transmitted light,

Fig. 2c the security element according to Fig. 2a in supervision

incident,

Fig. 3a layer structure and section through an inventive

Security element along the line A - A,

Fig. 3b layer structure and section through an inventive

Security element along the line A - A,

Fig. 4a layer structure and section through an inventive

Security element along the line A - A, 4b the security element according to FIG. 4a in supervision

By light

4c the security element according to FIG. 4a in supervision in incident light,

Fig. 5a layer structure and section through an inventive

Security element along the line A - A,

Fig. 5b the security element according to Fig. 5a in supervision

By light

Fig. 5c the security element according to Fig. 5a in supervision

incident,

Fig. 6a layer structure and section through an inventive

Security element along the line A - A,

6b the security element according to FIG. 6a in supervision with transmitted light,

6c the security element according to FIG. 6a in supervision

incident,

Fig. 7a layer structure and Schratt by an inventive

Security element along the line A - A,

7b the security element according to FIG. 7a in supervision

By light Fig. 7c the security element according to Fig. 7a in supervision

incident,

8a layer structure and section through an inventive security element along the line A - A,

8b the security element according to FIG. 8a in supervision

By light

Fig. 8c the security element according to Fig. 8a in supervision

incident,

9a to 9e method for producing a security element according to the invention,

10a to 13 further variants of the security element according to the invention in supervision with transmitted light and in cross section.

1 shows a document of value according to the invention in supervision. In the example shown, it is a bank note 1. This bank note has a strip-shaped security element 2, which extends over the entire width of the bank note 1 and spans a hole 3 in the bank note. The security element shown is a security element that consists of a plastic layer and two metal layers of different optical density. There are recesses at least in the optically denser layer, possibly also in the optically thinner layer. The entire surface of the security element 2 facing the viewer is coated according to the invention, the area in particular in the area of the Hole 3 visually perceptible effects are described in the following figures. For the sake of clarity, the following figures each show the layer structure mirrored on the basic idea of the invention. Additional layers, such as adhesive layers or laminating foils etc. used to protect the surface, can of course also be present and must be supplemented by the person skilled in the art depending on the application.

FIG. 2a shows a section of the cross section of the security element 2 along the line AA in FIG. 1 in a first exemplary embodiment. The plastic film 4, which serves as a substrate for the metal layers still to be vapor-deposited, can be seen here. The diffraction structures 5 are introduced into the plastic layer. Alternatively, the diffraction structures could also be incorporated in an additional lacquer layer. On the side of the plastic film on which the diffraction structures are located, a metal layer 6 was evaporated directly adjacent, which is the optically denser metal layer A and which appears opaque when viewed. In the present exemplary embodiment, the metal layer A consists of aluminum. There is in turn a metal layer 7, namely the optically thinner metal layer B, which also consists of aluminum. The layers 6 and 7 also have the diffraction structures as in the plastic film 4. In addition, there are recesses 8 in the layer 6, which are any characters, alphanumeric characters, patterns, logos or the like. The layer sequence of substrate / layer A / layer B leads, in particular in the case of diffraction structures present in the substrate, to advantageously designed security elements.

FIG. 2b shows the detail shown in FIG. 2a as it appears when viewed in transmitted light. If one looks at the security element from the layered side of the substrate 4, the cutout 8 can be seen in transmitted light as a transparent area or as a semi-transparent area. The cutout 8, here in the form of a star, is completely surrounded by the silver-appearing aluminum layer 6.

Fig. 2c shows the same section in reflected light. The recess 8 is no longer recognizable as such and the viewer sees a security element that appears to be homogeneously coated over the entire surface.

3a shows a further embodiment of an inventive

Security element shown in cross section. Here, the plastic film 4 was first coated with an optically thinner aluminum layer 7, on which in turn there is an optically denser aluminum layer 6 with cutouts 8. A second optically thinner aluminum layer 7 was again vapor-deposited onto the optically denser aluminum layer 6. In the area of the recess 8, the two optically thinner aluminum layers 7 adjoin one another, the layer thickness in total of the two aluminum layers 7 being smaller than the layer thickness of the metal layer 6. The advantage of this embodiment is that this is a symmetrical security element, ie at

Viewing the front and back provides the same appearance.

3b shows an embodiment of a security element according to the invention in cross section, in which the optically denser layer 6 and the optically thinner layer 7 are not placed one above the other, but next to one another. First, a plastic film 4 with an optically thinner aluminum layer 7 was only partially, for example coated in a strip. In a second step, the optically denser aluminum layer 6 was fitted into the interspaces in register or slightly overlapping with layer 7. brought. This embodiment also shows the same appearance when viewed from the front and back. In transmitted light, the viewer sees alternating light and dark stripes running across the band-shaped substrate. The substrate appears uniformly coated in silver in reflected light.

4a shows a further embodiment in cross section. In this variant, the optically thinner layer B and then the optically denser layer A were applied to the substrate 4, in contrast to the layer sequence in FIG. 2a. This layer sequence is preferably used for non-embossed substrates. This variant is characterized in that the optically thinner and optically denser layer is composed of different metals. The expert has no limits. An example representative of many others is described with reference to FIG. 4a. The optically thinner metal layer 9 made of aluminum is located on the substrate 4 in the left figure area and the optically thinner metal layer 10 made of chrome is located in the right figure area. There is a further aluminum layer 11 above the metal layer 9 made of aluminum, but designed as an optically denser layer. The optically denser one is above the chrome coating

Metal layer 12 made of gold. The optically denser layers of aluminum and gold were arranged in such a way that there is a cutout 8 in the area where the optically thinner layers 9 and 10 adjoin one another.

FIG. 4b shows the section of the security element shown in cross section in FIG. 4a when viewed in transmitted light. If one looks at the security element from the direction of the optically denser layer, one sees in the left image area the area 13 which appears silvery and in the right area the area area 14 appearing gold-colored. The cutout 8 can be recognized as a transparent cutout which protrudes both into the area 11 and into the area 12.

4c shows the same section in incident light. In the left figure area, the viewer sees the security element as a full-surface, homogeneous, silver-shiny surface 13, while in the right figure area 14 a silver-colored partial area 15, largely surrounded by the gold-colored area 14, is visible.

5a shows a further embodiment of the security element 2 according to the invention. In this variant, both the optically thinner and the optically denser metal layer are made of aluminum. The optically thinner aluminum layer 7 is first applied to the substrate 4, a recess 16 already being located in this layer. The optically thicker aluminum layer 6 is applied to the optically thinner aluminum layer 7 in such a way that the cutouts in the optically denser layer 8 come to coincide with the cutout 16 and are located above the optically thinner layer 7.

If the security element from FIG. 5a is viewed in transmitted light, the viewer sees, as shown in FIG. 5b, a shiny silver band with transparent areas which are designed as a square 17 and a circle 18.

As shown in Fig. 5c, the viewer has a different image in reflected light. Here, the recess 16, which is congruent with the recess 8, can still be perceived as a transparent region 17, while the region 18 is no longer recognizable, but the security element presented in this area as an apparently homogeneously coated element.

6a shows a further embodiment variant of the security element according to the invention. This element is also optically thinner

Layer 7 and the optically denser layer 6 made of the same material, namely aluminum. The cutouts in both layers are arranged such that the cutout 16 in the optically thinner layer and the cutout 8 in the optically denser layer are arranged one above the other, the cutout 8 being larger than the cutout 16. The layer arrangement on the substrate 4 corresponds to that in FIG. 5a. If this security element is viewed in transmitted light, as shown in FIG. 6 b, the viewer perceives a transparent area 19 which corresponds to the outline shapes of the cutout 8. Recess 16 is not recognizable as such.

If this section is viewed in incident light, as shown in FIG. 6c, only a recess 16 can be perceived as a transparent area. Recess 8 is in turn perceived as a homogeneous surface that cannot be distinguished from the rest of the opaque layer.

The extent to which the optically thinner layer 7 is perceived as transparent or semi-transparent depends on the respective materials and layer thicknesses. This can be adjusted accordingly by the person skilled in the art depending on the desired effect.

FIG. 7a shows an embodiment which shows the same layer structure as FIG. 5a, but differs from the embodiment from FIG. 5a in that the optically thinner layer 7 consists of copper, the optically denser layer 6 consists of aluminum. In transmitted light, as shown in Fig. 7b transparent areas 20, 21 can again be seen in the area of the cutouts 8 and 16. If desired, the transmission property of the copper layer can be set so that in the area 21 the viewer does not perceive a fully transparent cutout, but recognizes a slightly greenish, semi-transparent area. In incident light, as shown in FIG. 7c, the cutout 16 is still recognizable as a transparent area 20, while in the area of the cutout 8, which lies on the copper layer, a circular, copper-colored element 21 appears in a silvery environment.

Analogous to FIG. 6a, an embodiment is shown in FIG. 8a in which the recess 8 comes to lie over the recess 16 and occupies a larger area than this. In contrast to the exemplary embodiment in FIG. 6a, FIG. 8 shows a variant in which the optically denser layer 6 consists of aluminum and the optically thinner layer 7 consists of copper. The effect perceptible in transmitted light, as shown in FIG. 8b, corresponds to that shown in FIG. 6b. That is, the transparent surface 22 that the viewer can perceive corresponds to the cutout 8. However, in incident light, FIG. 8c shows a different appearance than that described in FIG. 6c. Recess 16 can be seen as a transparent area 23 in the form of a rectangle, while the recess 16 can be perceived as a copper-colored triangle 22. The remaining surface of the security element appears silver-colored due to the aluminum layer.

9a to 9e schematically illustrate the method for producing a security element according to the invention, as shown in FIGS. 5a and 7a. The method is explained by way of example for security threads or labels, but can of course be used in an analogous manner for security elements with other layer sequences. The security elements are preferably produced as a security film has several benefits of the security element. The starting point in the example shown here is a self-supporting plastic film 4. As shown in FIG. 9a, this is printed in a first step in the areas in which the cutouts 16, 8 are to be present later, with a printing ink 24 that contains a lot of pigment, so that a large-pored print is created. Then, in this case, the optically thinner metal layer 7 made of aluminum is applied to the printed plastic film 4. For this purpose, a vacuum vapor process is preferably used, in which the metals are evaporated onto the plastic film 4 one after the other, optionally via masks. Due to the porous surface structure of the printing ink, no coherent metal layer forms in the area of the print 24. The intermediate product provided with the metal layer 7 is shown in FIG. 9b.

In the embodiment shown in FIGS. 5 a and 7 a, the cutout 16 will be produced with the aid of the first printing of washing ink. In order to produce the cutouts 8, a print 25 with washing ink is again made at the desired location. 9c shows the intermediate product printed with the printing ink 24, then coated with aluminum and again printed with ink 25.

This intermediate product is in turn coated with metal, e.g. with aluminum in order to produce the optically denser layer 6 (see FIG. 9d).

Since no closed metal surface forms in the area of the imprint 24 and 25, the imprint and the metal layer 6 or 6 and 7 present in these areas can be removed almost effortlessly by washing out. Water is preferably used for washing out. It may be necessary to brush additionally use, which ensure that the printing 24 and 25 are completely removed. The final product is shown in Fig. 9e. The metal layers 6 and 7 have the cutouts 8 and 16. The security film can then be cut into security elements of the desired shape.

The washing process offers the advantage that sharp and defined edges and contours are achieved, so that this process can also be used to create very fine, high-resolution characters or patterns in the metal layers.

10a to 13 show further variants of the security element according to the invention, cutouts being combined as positive or negative text and these can be present in one or both layers.

10a shows an embodiment in which, on the one hand, the cutouts 16 in the optically thinner layer 7 come to lie congruently with the cutouts 8 in the optically denser layer 6 and, on the other hand, the cutout 8 in the optically denser layer is substantially larger than that Cutouts 16. Because of this explicit arrangement of the cutouts, the lettering "PL 2000" always appears to the viewer in transmitted light as a transparent area which is arranged on the one hand in an opaque field and on the other hand in a semitransparent field. The layer structure of the The security elements shown in cross-section can be seen in Figure 10. The cross-sectional view is limited to the display of the two left fields shown in Figure 10a.

FIG. Ha shows an embodiment variant in which the cutouts in the optically denser and optically thinner layer are congruent in one area and the optically in another area thinner layer is present over the entire surface, while the cutouts in the optically denser layer are designed such that the lettering "PL 2000" stands out as positive text against a semi-transparent background. The associated layer structure is shown in FIG. 11b, again the two left fields of the Security elements shown in Fig. Ha are shown.

12a shows a security element which has areas in which the semi-transparent lettering "PL 2000" appears in an opaque environment, while in other fields the opaque positive lettering "PL 2000" appears in a semi-transparent environment. This appearance is achieved in that the optically thinner layer 7 is present over the entire surface and the optically thicker layer 6 applied thereon is applied with the desired cutouts for producing a positive or negative text. FIG. 12b shows the associated layer structure of the two fields on the left shown in FIG. 12a.

In FIG. 13, different cutout variants shown in the previous figures are combined with one another. For example, with this security element there is a semi-transparent negative lettering "PL 2000" in an opaque environment, adjacent to a semi-transparent field in which the positive lettering "PL 2000" appears, and again there is an opaque box with the transparent one Lettering "PL 2000". The layer structure of these three fields corresponds to the layer structure from FIG. 12b, combined with the layer structure of the first field, which is shown in FIG. 11b.

Claims

Patent claims

1. Security element for security papers, banknotes, identity cards or the like, with a substrate on which at least two metal layers are arranged, characterized in that the metal layers have different optical densities.

2. Security element according to claim 1, wherein the at least two metal layers are arranged on the same side of the substrate.

3. Security element according to claim 1 or 2, wherein the metal layers lie directly one above the other.

4. Security element according to at least one of claims 1 to 3, the optically thinner layer of the at least two metal layers being present at least in the regions on the substrate in which the optically denser layer is not present.

5. Security element according to one of claims 1 to 4, wherein at least the optically denser layer of the at least two metal layers

Has recesses.

6. Security element according to claim 5, wherein the recesses are in the form of alphanumeric characters, patterns, logos or the like or in the form of a bar code.

7. Security element according to at least one of claims 1 to 6, wherein the optically thinner layer is present over the entire surface.

8. Security element according to at least one of claims 1 to 7, wherein the optically denser layer has a transmission of at most 30%, preferably at most 10%.

9. Security element according to at least one of claims 1 to 8, wherein the transmission of the optically denser metal layer is at most 10% and that of the optically thinner metal layer is at least 50%.

10. Security element according to at least one of claims 1 to 9, wherein the metal layers consist of the same material.

11. Security element according to at least one of claims 1 to 9, wherein the metal layers consist of different material.

12. The security element according to at least one of claims 1 to 11, wherein the metal is aluminum, silver, copper, gold, iron, chromium, nickel, cobalt, platinum, palladium, titanium, inconel, silver bronze, gold bronze or an alloy of at least two metals thereof can be.

13. Security element according to at least one of claims 1 to 12, wherein the at least two metal layers have different layer thicknesses.

14. Security element according to at least one of claims 1 to 13, wherein a metal layer is opaque and a metal layer is semitransparent.

15. Security element according to at least one of claims 1 to 14, wherein part of the recesses in the at least two metal layers is congruent.

16. Security element according to at least one of claims 1 to 15, wherein the layer thickness of the optically denser layer ranges from approximately 20 to 300 nm and that of the optically thinner layer ranges from approximately 2 to 20 nm.

17. Security element according to at least one of claims 1 to 16, wherein the substrate is a plastic layer.

18. Security element according to at least one of claims 1 to 17, wherein the substrate has a diffraction structure in the form of a relief structure.

19. Security element according to at least one of claims 1 to 18, wherein the substrate is a self-supporting plastic film.

20. Security element according to at least one of claims 1 to 19, wherein the substrate is arranged on a carrier material.

21. Security element according to at least one of claims 1 to 20, wherein the security element is a transfer element.

22. The security element according to at least one of claims 1 to 21, wherein the security element is a self-supporting label.

23. The security element according to at least one of claims 1 to 22, wherein the security element has round, oval, star-shaped, rectangular, trapezoidal or strip-shaped outline contours.

24. Security element according to at least one of claims 1 to 23, wherein the security element is a security thread.

25. Security element according to at least one of claims 1 to 23, wherein the security element is a laminating film.

26. Security paper for the production of documents of value, characterized in that it has at least one security element according to at least one of claims 1 to 25.

27. The security paper according to claim 26, wherein the security element is a security thread that is at least partially embedded in the security paper.

28. Security paper according to claim 26, wherein the security paper has a continuous opening, the security element being arranged in the region of the opening and projecting beyond it on all sides.

29. Security paper according to claim 26, wherein the security element is a transfer element or a laminating film which is applied to the surface of the security paper.

30. Security paper according to at least one of claims 26 to 29, wherein the security element has round, oval, star-shaped, rectangular, trapezoidal or strip-shaped outline contours.

31. document of value, such as a banknote, identity card or the like, characterized in that it has at least one security element according to at least one of claims 1 to 25.

32. Transfer material or laminating film for the production of security elements, which has a carrier film and a substrate on which at least two metal layers are arranged, characterized in that the metal layers have different optical densities.

33. Transfer material or laminating film according to claim 32, wherein the at least two metal layers are arranged on the same side of the substrate.

34. Transfer material or laminating film according to claim 32 or 33, wherein the metal layers lie directly one above the other.

35. Transfer material or laminating film according to at least one of claims 32 to 34, wherein the optically thinner layer of the at least two metal layers is present at least in the regions on the substrate in which the optically denser layer is not present.

36. Transfer material or laminating film according to at least one of claims 32 to 35, wherein at least the optically denser layer of the at least two metal layers has cutouts.

37. Transfer material or laminating film according to at least one of claims 32 to 36, wherein the substrate is a plastic layer.

38. Transfer material or laminating film according to at least one of claims 32 to 37, characterized in that the substrate has a diffraction structure in the form of a relief structure.

39. Use of a security element according to at least one of claims 1 to 25 for the counterfeit protection of goods of any kind.

40. Use of a security paper according to at least one of claims 26 to 30 for anti-counterfeiting of goods of any kind.

41. Use of a value document according to claim 31 for the counterfeit protection of goods of any kind.

42. Method for producing a security element for security papers, banknotes, identity cards or the like, with a substrate on which at least two metal layers are arranged, the metal layers having different optical densities, characterized by the following steps:

al) providing the substrate in the form of a self-supporting plastic film or a carrier material on which a plastic layer is arranged;

bl) optionally printing on the substrate with alphanumeric characters, patterns, logos or the like using a printing ink with a high pigment content and drying the printing ink to form a porous, raised ink application;

cl) applying the optically thinner metal layer to the optionally printed substrate;

dl) printing the optically thinner metal layer with alphanumeric characters, patterns, logos or the like using an ink with a high pigment content and drying the ink to form a porous, raised ink application;

el) applying the optically denser metal layer to the optically thinner metal layer;

fl) removing the paint application and the metal layer or metal layers lying above or penetrating into the paint application by washing out with a liquid, possibly combined with mechanical action;

gl) drying and optionally cutting the substrate.

or

a2) providing the substrate in the form of a self-supporting

Plastic film or a carrier material on which a plastic layer is arranged; b2) printing the substrate with alphanumeric characters, patterns, logos or the like using an ink with a high pigment content and drying the ink to form a porous, raised ink application;

c2) applying the optically denser metal layer to the printed substrate;

d2) removing the paint application and the metal layer or metal layers lying above or penetrating into the paint application by washing out with a liquid, possibly combined with mechanical action;

e2) applying the optically thinner metal layer to the optically denser metal layer;

f2) optionally cutting the substrate.

43. The method according to claim 42, wherein the metal layers are applied by vapor deposition, optionally with the aid of masks.

44. The method of claim 42 or 43, wherein the substrate is provided in the form of an endless belt and the method is carried out continuously.

45. The method according to at least one of claims 42 to 44, wherein the printing ink is water-soluble and water is used for washing out.

46. The method according to at least one of claims 42 to 45, wherein the printing of the substrate is carried out in gravure printing.

47. The method according to at least one of claims 42 to 46, wherein the plastic layer in step a1) or a2) in the form of an endless

Plastic film is provided and is cut into security threads of predetermined width in step gl) or f2).

48. The method according to at least one of claims 42 to 47, wherein the plastic layer in step a1) or a2) is arranged on a specially prepared carrier material in order to form a transfer material which in step g1) or f2) has strips of a predetermined width is cut.

49. The method according to at least one of claims 42 to 48, wherein a diffraction structure is embossed into the substrate before step bl) or b2).

50. A method for producing a security paper for the production of documents of value, characterized in that a security thread produced according to at least one of claims 42 to 49 is embedded during the production of the security paper.

51. Method for producing a security paper for documents of value, characterized in that a security element, produced in accordance with at least one of claims 42 to 49, is applied to the surface of the finished security paper.

2. The method according to claim 51, characterized in that in the

Security paper an opening is made during paper production, which is then closed at least on one side with the security element.