EP1377461B2 - Method for forgery-proof labeling of items, and forgery-proof label - Google Patents

Abstract

The invention relates to a method for forgery-proof labeling of items, such as credit cards, bank notes and the like, comprising the following steps: (a) applying, to a first layer (1) that reflects electromagnetic waves, and inert second layer (3) that is permeable to electromagnetic waves, said second layer having a predetermined thickness, (b) applying, to said second layer (3), a third layer (4) that is formed by metal clusters, and (c) linking the first layer (1) of the label so produced with the item.

Description

The invention relates to a method for counterfeit-proof marking of objects such as check cards, banknotes, packaging and the like. It also relates to a tamper-proof mark.

According to the prior art, it is known to provide holograms to prove the authenticity of check cards or banknotes. Further, to prove the authenticity of an article, magnetic codes are applied to magnetic stripes or fluorescent markers. The well-known markings are relatively easy to fake.

From the US 5,611,998 is an optochemical sensor known. In this case, a chemically reactive layer is applied to a metal layer, which changes its volume on contact with a solution containing a substance to be detected. On the chemically reactive layer, a layer formed of metallic clusters is applied. By bonding the substance to be detected, the distance between the layer formed by the metallic cluster and the metal layer changes. At the same time, the absorption of light irradiated to the sensor also changes. The presence of the substance to be detected causes a color change of the sensor. The known sensor is not suitable for the counterfeit-proof marking of objects. A color change only occurs when the sensor is exposed to a liquid phase. In addition, contact with moisture or liquids may cause a reaction that triggers or alters a color signal.

The object of the invention is to provide a method for marking objects and a marking, which offer a high degree of protection against forgery in a simple and cost-effective manner.

This object is solved by the features of claims 1 and 6. Advantageous embodiments result from the features of claims 2 to 5 and 7 to 8.

According to the invention, a method for the counterfeit-proof marking of objects such as check cards, banknotes and the like., Is provided according to claim 1.

With the aforementioned features, a forgery-proof permanently visible mark can be produced in a simple and cost-effective manner.

The second layer is applied structured in the process. The structuring is a structure in the surface in the manner of a pattern or a drawing. It is also a relief-like structure. In this case, the marker appears in different colors.

An electromagnetic fourth wave permeable fourth layer is applied to the third layer. The fourth layer serves primarily to protect the covered layers.

The substrate may be made of an electromagnetic wave transmissive material, preferably of glass or plastic.

It is expedient to apply to the third or fourth layer first molecules which are affine to the second layer or to second molecules provided thereon. In this case, polymers, silanes or structurally related compounds can be used as molecules. It is e.g. also conceivable to use complementary polynucleotide sequences, such as DNA, as molecules. The function of the first and second molecules is essentially to adhere the substrate to the marking at a fixed predetermined distance.

The metallic clusters can be made, for example, from silver, gold, platinum, aluminum, copper, tin or indium. The second layer is made of one of the following materials: polymer, especially polycarbonate (PC), polyethylene (PE), polypropylene (PP), polyurethane (PU), polyimide (PI), polystyrene (PS) or polymethacrylate (PMA). These materials are chemically substantially inert. They are insensitive to moisture. The function of the second layer is essentially to permanently provide a predetermined distance to the third layer and a predetermined structure.

According to a further embodiment, it is provided that at a distance between the first and the third layer of less than 2 microns, a dye forming the mark is visible. The coloration is dependent on the angle of observation and characteristic. For this purpose, the first layer can be irradiated by means of a device for generating electromagnetic waves, preferably by means of LASER, fluorescent lamp, light-emitting diode or xenon lamp. The marker may be identified by means for determining the optical properties of the electromagnetic waves reflected from the first layer. It can be measured with the means for determining the optical properties of the absorption, preferably at different observation angles. Such a determination of the optical properties allows a high security against counterfeiting.

According to a further embodiment feature, it is provided that the layers are at least partially produced by means of thin-film technology. In particular, vacuum coating technologies and the like come into consideration.

According to a further embodiment feature, it is provided that at least one of the layers is made of a material having an anisotropic refractive index. Preferably, the second layer is made of an anisotropic refractive index material. The material may be e.g. to be liquid crystal polymers which are stable at different observation angles, i. Angles to the z-axis, as well as at different angles of rotation, i. Angles in the x-y plane, showing a characteristic coloration.

According to a further embodiment feature, at least one of the layers can be made of a material whose optical properties can be selectively changed after the application of the layer. The material may be e.g. to be a photosensitive polymer whose refractive index is variable by irradiation with a suitable wavelength.

Because of the further design features of the forgery-proof marking, reference is made to the preceding comments on the method.

• Fig. 1   eine schematische Querschnittsansicht einer ersten ständig sichtbaren Markierung, die nicht Gegenstand der Erfindung ist,
• Fig. 2   eine schematische Querschnittsansicht einer zweiten ständig sichtbaren Markierung, die nicht Gegenstand der Erfindung ist,
• Fig. 3   eine schematische Querschnittsansicht einer nicht ständig sichtbaren ersten Markierung und eines zur Sichtbarmachung geeigneten Substrats, die nicht Gegenstand der Erfindung ist,
• Fig. 4   eine schematische Querschnittsansicht einer nicht ständig sichtbaren zweiten Markierung und eines zur Sichtbarmachung geeigneten Substrats, die nicht Gegenstand der Erfindung ist,
• Fig. 5.   Absorptionsspektren einer Markierung gemäß Fig. 1 unter verschiedenen Beobachtungswinkeln und
• Fig. 6   eine quantitative Auswertung der Spektren gemäß Fig. 5 bei verschiedenen Wellenlängen.

Hereinafter, embodiments of the invention will be explained in more detail with reference to the drawings. Show it:

• Fig. 1 a schematic cross-sectional view of a first permanently visible mark, which is not the subject of the invention,
• Fig. 2 a schematic cross-sectional view of a second permanently visible mark, which is not the subject of the invention,
• Fig. 3 a schematic cross-sectional view of a not always visible first marker and a suitable for visualization substrate, which is not the subject of the invention,
• Fig. 4 a schematic cross-sectional view of a not always visible second marker and a suitable for visualization substrate, which is not the subject of the invention,
• Fig. 5 , Absorption spectra of a label according to Fig. 1 under different viewing angles and
• Fig. 6 a quantitative evaluation of the spectra according to Fig. 5 at different wavelengths.

In the in the Fig. 1 to 4 1, an electromagnetic wave reflecting first layer is designated 1. It can work to a metal foil, such as an aluminum foil act. However, the first layer 1 can also be a layer formed from clusters which is applied to a carrier 2. The carrier 2 can be the object to be marked. The clusters are suitably made of gold.

Applied to the first layer 1 is a chemically inert second layer 3. The second layer 3 has a structure. The structure is in the form of a relief which is e.g. designed in the manner of a bar code. The thickness of the second layer is preferably between 20 and 1000 nm. It is applied by means of thin-film technology. For this purpose, e.g. Vacuum coating process.

In the in the Fig. 1 and 2 1, a third layer 4 made of metallic clusters is applied on the second layer 3. The third layer 4 in turn is superimposed by a fourth layer 5. The fourth layer 5 protects the underlying layers from damage. The fourth layer 5 may be made of a chemically inert and optically transparent material, eg a metal oxide, nitrite, carbide or polymer.

The in the 3 and 4 Marks shown are only visible when they are brought into contact with a substrate 6, on the surface of which the third layer 4 formed of metallic clusters is applied. The third layer 4 may be superposed with a fifth layer 7 formed of first molecules. The fifth layer 7 is expediently formed from molecules which are affine to the material of which the second layer 3 is made. Upon contact of the fifth layer 7 with the second layer 3, a specific adhesion thus occurs. It may also be that the second layer 3 is covered with a further fifth layer 7. In this case, the fifth layers 7 are each formed of molecules having affinity to each other. These may be biopolymers which are complementary to each other. However, the fifth layer 7 can also be made of other polymers, silanes and / or structurally related compounds.

The substrate 6 is made of a transparent material, e.g. made of glass or plastic.

The function of the marker is as follows:

When irradiating light from a light source, such as a LASER, a fluorescent tube or a xenon lamp on an in Fig. 1 and 2 As shown, this light is reflected at the first layer 1. By an interaction of the reflected light with the third layer 4 formed from the metallic clusters, part of the incident light is absorbed. The reflected light has a characteristic spectrum. The marking appears colored. The coloration dependent on the irradiation or observation angle serves as proof for the authenticity of the marking which is secure against counterfeiting.

At the in 3 and 4 As shown, only the optically transparent second layer 3 is applied to the electromagnetically reflecting first layer 1. The marking is initially not visible.

When the optically transparent substrate 6 provided with the third layer 4 is applied, an interaction between the light reflected at the first layer 1 and the third layer may occur. This in turn results in a color effect, which is observable by the substrate 6, preferably made of glass.

In order to ensure that the predetermined distance between the first 1 and the third layer 4 required for producing the color effect occurs, the third layer 4 may be covered with a fifth layer 7. Upon contact of the fifth layer 7 with the second layer 3, the substrate 6 adheres to the marking. It sets a predetermined distance between the third layer 4 and the first layer 1 a.

With regard to the parameters to be respected for the generation of the interactions, reference is made to US 5,611,998 , the WO 98/48275 as well as the WO 99/47702 directed.

In the Fig. 5 shown spectra of a marker according to Fig. 1 were measured using a Lambda 25 UV / VIS spectrometer from Perkin Elmer using a reflection insert. Out Fig. 5 It can be seen that the longer-wave peak shifts toward shorter wavelengths with increasing observation angle. Furthermore, a fixed peak can be observed, which is due to the silver clusters.

In Fig. 6 is a quantitative evaluation of the spectra according to Fig. 5 each shown at two different wavelengths. At the considered wavelengths, a changed absorption is observed depending on the observation angle. The absorption pattern is characteristic of the authenticity of the label.

LIST OF REFERENCE NUMBERS

1

first shift

2

carrier

3

second layer

4

third layer

5

fourth shift

6

substratum

7

fifth shift

Claims (8)

1. Method for the forgery-proof labeling of objects, such as check guarantee cards, bank notes, packaging etc., wherein

   a) an inert second layer (3) with a predetermined thickness, which is transmissive for electromagnetic waves, is applied to a first layer (1) which reflects electromagnetic waves, wherein the second layer (3) is made from polymer, in particular polycarbonate (PC), polyethylene (PE), polypropylene (PP), polyurethane (PU), polyimide (PI), polystyrene (PS) or polymethacrylate (PMA),

   b) a third layer (4), formed from metallic clusters, is applied to the second layer (3),

   c) the first layer (1) of the label produced in this way is connected to the object,

   d) wherein the second layer (3) is applied in a structured fashion, so that the second layer has a relief-like structure, and

   e) wherein an inert fourth layer (5), which is transmissive for electromagnetic waves, is applied to the third layer (4).
2. Method according to Claim 1, wherein the metallic clusters are made from silver, gold, platinum, aluminum, copper, tin or indium.
3. Method according to one of the preceding claims, wherein at least some of the layers (1, 3, 4, 5) is/are produced by means of thin-film technology.
4. Method according to one of the preceding claims, wherein at least one of the layers (3, 4, 5) has an anisotropic refractive index.
5. Method according to one of the preceding claims, wherein at least one of the layers is made from a material whose optical properties can be modified after the layer is applied.
6. Forgery-proof label for objects, such as check guarantee cards, bank notes etc.,
   wherein an inert second layer (3) with a predetermined thickness, which is transmissive for electromagnetic waves, is applied to a first layer (1) which reflects electromagnetic waves and which is connected to the object, wherein the second layer (3) is made from a polymer, in particular polycarbonate (PC), polyethylene (PE), polypropylene (PP), polyurethane (PU), polyimide (PI), polystyrene (PS) or polymethacrylate (PMA),
   wherein a third layer (4), formed from metallic clusters, is applied to the second layer (3),
   wherein the second layer (3) has a relief-like structure, and
   wherein an inert fourth layer (5), which is transmissive for electromagnetic waves and which covers the third layer (4), is provided.
7. Forgery-proof label according to Claim 6, wherein the metallic clusters are formed from silver, gold, platinum, aluminum, copper, tin or indium.
8. Forgery-proof label according to either of Claims 6 and 7, wherein the layers (1, 3, 4, 5) is/are produced by means of thin-film technology.

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