EP1740393B1 - Security mark for a data carrier, corresponding data carrier and method for the production of a security mark - Google Patents

Abstract

The invention relates to a security mark, a corresponding data carrier and a corresponding method for the production of a security mark. The security mark comprises a carrier (1). In the region (5) of the carrier, transparent modifications in the volume of the carrier (1) are produced by means of an additionally added substance and a hardenable substance, enabling first information to be represented. The surface relief (7) is imprinted in at least one part of said region (5), and second information or an optically active verification element is represented by the surface relief.

Description

The invention relates to a security feature for data carriers according to the preamble of claim 1. The invention further relates to a corresponding data carrier and a method for producing such a security feature or such a part of a security feature according to the preamble of the further independent claims.

With data carriers in the present application value and security documents such as banknotes, ID cards, passports, check forms, tickets, tickets, vouchers or other value and security documents are summarized. A security feature for such media allows one to determine if the media is genuine or fake.

Watermarks are well known and widely used security features for media made from paper. A watermark denotes an area on a data carrier which, when viewed through the data carrier against the light or against a surface rich in contrast with the color of the data carrier, reveals information to the viewer. The information is not so clearly visible if the data carrier is considered against a less contrasting surface or opposite to the light.

Information is considered to be images or patterns or letters or text or numbers or numbers or combinations of these elements. Information in security features are read by the user or a tester. The user or the device determines based on the information content, whether the disk is real or fake.

The security expert will distinguish genuine watermarks and so-called chemical or pseudo-watermarks.

Conventionally, watermarks are generated by elevations in a sieve by embossing in still wet pulp, so that the paper is thinner and thus more transparent at this point. This form of marking has been used since the Middle Ages to prove the authenticity of papers, since such watermarks are only original in the manufacture of the paper can be introduced. The production cost for such papers is very high.

On the other hand, in so-called chemical or artificial watermarks, chemical substances are added during papermaking or after completion of the carrier manufacturing process, which change the transparency of the carrier. Many methods are based initially on the impregnation of the paper with reactive substances, which leads by an appropriate post-treatment to increased transparency or to increased opacity (English: opaque-shadow-watermark).

In the publication EP 0 203 499 B1 a method for producing a chemical watermark and a corresponding security feature is described. During papermaking, a thermosensitive material such as a polyethylene polymer is added to the composition. After completion of the paper, a heat-treated die or a heat-treated stamp is pressed onto the mass at the locations where the transparency of the paper is to be changed. It should be noted that the pressure with which the die or the stamp is pressed on the paper should be very low, in order to avoid stronger notches on the surface of the paper.

From the publication US 3,985,927 There is known a method for producing chemical watermarks, in which the watermark-generating substance is transferred to the paper by means of a stamp and subsequently treated by means of ultraviolet radiation. The publication US 6,358,596 B1 describes a method in which the surface of a soaked substrate by means of calenders or embossing matrices for producing the Watermark is compressed. In the areas in which a treatment by means of calender or embossing die takes place, a substance is present which increases the transparency of the substrate. There is an aftertreatment by means of electromagnetic radiation or thermally.

The publication US 6,630,055 B1 shows the production of a chemical watermark for paper, where the chemical watermark locally changes the density, thickness or transparency of the paper. For this purpose, the paper material is treated with a moistening solution, which is applied for example by means of ink jet. The solution is preferably hydrophilic or polar. After the solution has been applied, pressure and heat are applied to the substrate provided with the solution during a calendering step.

The publication EP 0 540 455 B1 shows a paper support, which is provided with a print layer and an overlying plastic layer. In the plastic layer a relief for a hologram or cylindrical lenses is engraved. As a plastic layer, a paint or a thermoplastic resin is provided. Also the publication US 4,933,120 describes a hologram applied directly to a document. Here, a liquid resin is transferred by means of rollers on the surface of the document, at the same time a relief is generated. To harden the resin, electromagnetic radiation is also used in this case.

In the publication DE 197 29 908 A1 describes a two-part security feature for media. The security feature consists of a window and a part to be verified. Both parts of the security feature are located in different areas of the volume. After superimposing window and verifizierendem part, the interaction of the two parts gives a statement about whether the disk is real or fake. Such a security feature is also referred to as a self-verifying security feature, as for verification separate, provided on the same or a different medium verification device is required.

The publication WO 00 / 45344A shows a security feature for disk according to the preamble of claim 1.

The invention has for its object to provide security features with particularly high security against counterfeiting, for example, over the copying. The security features should also be able to be produced without much effort, the production should not take place in connection with the production of the carrier, but this is downstream. The security feature of the invention is intended to be integral with the carrier and not just, e.g. by gluing, be connected to this only via a connection. Another object is to realize particularly interesting and forgery-proof windows for self-verifying security features.

The invention is based on the further object of specifying corresponding data carriers with security features according to the invention and simple and cost-effective methods for producing such security features.

The object is achieved by a security feature, which additionally has a surface relief in a region which is provided with the transparenzändernden substance, wherein at least a second information or an optically effective verification element is represented by the surface relief. The object is further achieved by a data carrier which contains a security feature according to the invention. The object is also achieved by an inventive method for producing a security feature, wherein after the application of a substance provided for transparency change and curable substance on an area in the volume of the carrier at least parts of the area are provided with an embossing and at the same time curing the substance for transparency change in the area is carried out, wherein at least one of the region of interest by means of the transparency change produced by the substance first information and by means of the embossing at least a second information or an optically effective verification element can be represented.

Preferred embodiments of the invention are set forth in the dependent claims.

It is particularly advantageous if the carrier consists at least partially of cellulose. As a result, the influence on the transparency of the carrier is particularly pronounced. The same advantage is achieved if the proportion of titanium dioxide as a filler is influenced.

It is also advantageous, at least in a part of the range, to choose the average extent of a specific, fixed, predetermined change in transparency largely in comparison to the average extent of a specific, predefined relief height change in the range. The second information represented by the relief is thus better visible.

The transparency changes are particularly intense when they reach the volume of the support down to a depth of at least 50 μm.

In addition, the area with the change in transparency and the surface relief may still have a lacquer layer for protecting the surface relief. In addition, pigments which are colored or which luminesce upon irradiation with electromagnetic radiation can likewise be arranged in the support or in the substance provided for the change in transparency. As a result, an even higher security against counterfeiting is ensured and / or the realization of a more appealing design is possible.

A particularly preferred embodiment of the invention relates to the design of the surface relief such that the light is diffracted by the relief in the manner of an embossed hologram from the surface structure that in the interference of the diffracted light in reflection or transmission an image, namely a hologram, is generated. Such an embodiment creates a particularly tamper-proof security feature, which is also particularly appreciated by the untrained user in the design and easily verifiable.

In the case of a two-part, self-verifiable security feature, the surface structure is preferably designed as a lens structure, wherein the lens structure is used for verification of the second part of the security feature, which is arranged on the same or a different carrier. The lens structure is easy to produce.

Figur 1

einen erfindungsgemäßen Datenträger mit einem erfindungsgemäßen Sicherheitsmerkmal in einer Ansicht von oben (schematisch),

Figur 2

einen erfindungsgemäßen Datenträger und ein erfindungsgemäßes Sicherheitsmerkmal in einem Querschnitt entlang der Linie A-A (schematisch),

Figur 3

ein erfindungsgemäßes Herstellungsverfahren anhand von Querschnitten durch den Datenträger und das Werkzeug (schematisch) und

Figur 4

Ausschnitte aus einem erfindungsgemäßen Sicherheitsmerkmal (schematisch).

The invention will be explained in more detail by means of embodiments, which are illustrated in drawings. The embodiments also show other advantages of the invention. Show it

FIG. 1

a data carrier according to the invention with a security feature according to the invention in a view from above (schematically),

FIG. 2

a data carrier according to the invention and a security feature according to the invention in a cross section along the line AA (schematically),

FIG. 3

an inventive manufacturing method based on cross sections through the disk and the tool (schematically) and

FIG. 4

Cutouts from a security feature according to the invention (schematically).

FIG. 1 shows a data carrier according to the invention which has a carrier 1. The carrier 1 is a sheet-like article, which in the illustrated here Embodiment has a rectangular shape and a thickness of several microns to several millimeters. Preferably, the carrier has a thickness of about 20 microns to 900 microns. The carrier 1 has a number of security features, such as printed letters, which are provided with the reference numeral 3. In the area 5, the carrier 1 is provided with a subsequently applied and curable substance which alters the transparency of the data carrier 1 in this area. In the area so a chemical watermark is provided. In the exemplary embodiment illustrated here, the number "10" and a check pattern are represented by the change in transparency in area 5, wherein the different shades of gray are intended to illustrate a different transparency. For example, the light gray shaded areas forming the numerals "1" and "0" and the boundaries of the checks are provided with a low transparency compared to the other white areas of the area 5, as shown here, or vice versa. In other exemplary embodiments, other first information may also be displayed in region 5 by the substance.

The area 5 has in the dark shaded areas on a surface relief 7, through which at least a second information is shown. The relief structures are, for example, microembossings which form holograms, diffractive structures or, in a further preferred embodiment, so-called kinegrams. Kinegrams are holograms in which an apparent movement of an element of the hologram becomes visible as the wearer moves. In another embodiment, the embossments may also be in the form of micro-cylindrical lenses, Fresnel lenses or other optical microstructures. As optically effective microstructures are also sawtooth-like elevations and depressions in question, which are visible when tilting the carrier in different directions in space.

In the exemplary embodiment illustrated in FIG. 1, an embossed hologram is realized in the rectangular area with relief structure 7. In the hologram, for example, the image of a famous composer can be displayed. In the second dark hatched area with relief structure 7, a matrix of 2 × 4 letters "a" is arranged, on the surface of which a microrelief with a sawtooth structure is contained. The letters are visible when tilting the carrier. Such a microrelief or a hologram is also called an optically variable device OVD, since the feature has a different appearance under different viewing directions.

As an alternative to the security feature illustrated with reference to FIG. 1, any other second information can also be realized. It is preferably provided that at least parts of the first information and parts of the second information correspond to each other, so that there is a redundancy, which leads to a greater security against counterfeiting.

The carrier 1 preferably consists of a proportion of cellulose. It may contain titanium dioxide as a filler in a preferred embodiment. The carrier 1 may also contain a proportion of plastic, for example synthetic binders in the form of aqueous polymer dispersions (for example polymers and copolymers of different monomers from the group of styrene, butadiene, acrylic ester, vinyl acetate, acrylonitrile). The cellulose may have been obtained from wood or cotton or other cellulosic natural products.

FIG. 2 shows a section through the data carrier 1 along the direction AA. It can be clearly seen that in the region 5 of the carrier 1, the volume of the carrier 1 is at least partially impregnated by the substance intended for the change in transparency and curable. Penetration depths of the substances are, for example, at least 1 .mu.m, preferably at least 50 .mu.m.

On the surface of the support 1 reliefs 7 are formed, which have the above-mentioned microstructures.

FIG. 3 shows the method for producing a data carrier with a security feature according to the invention. Figure 3a shows as a starting point the carrier 1, which may be in roll or sheet form. The carrier consists of an above-stated proportion of cellulose and is for example a paper carrier. The carrier 1 may also contain a plastic as indicated above. If paper is used, it should be unbacked. Optionally, the paper may contain titania as a filler.

In the subsequent step, the paper is printed with a reactive mixture. Suitable printing methods are all printing processes, namely gravure and gravure printing, offset printing, flexographic printing or in particular digital printing, for example inkjet printing. In order to allow the penetration of the reactive substance into the carrier 1, a certain amount of reactive substance has to be applied to the surface. Such amounts should be in the range of 0.5 to 50 g / m ² , preferably in the range of approximately less than 5 g / m ² .

FIG. 3 b shows schematically in a cross-section that the carrier 1 is provided in the region 5 with a reactive and hardenable substance which penetrates into the carrier 1 at least to a depth of 1 μm, preferably at least to a depth of 50 μm is. As such substance, thermosetting resin mixtures (examples see US 3,441,427 ), radically, cationically or UV-curing substances (examples see US 3,985,927 . US 6,103,355 . US 6,143,120 and US 6,358,596 ), Polyurethane blends (see DE 39 20 378 ), Substances with special solids and high-boiling solvents or plasticizers (see US 4,919,044 ) or cellulose solvents (for example N-methylmorpholine-N-monoxide (NMMO). The reactive substances can be provided with dyes, luminescent, thermochromic, electrochromic or photochromic pigments. As a result, further features to be verified can be added to the security feature according to the invention. For example, in the presence of luminescent pigments in the region 5 for verification of the security feature, it would additionally be possible to check the presence of the luminescence originating from the luminescent pigments and the wavelength of the luminescence. Electromagnetic radiation, which is applied to area 5, for example by means of a laser, serves as excitation of the luminescence.

FIG. 3c schematically shows the next method step. The carrier 1 provided with the reactive substance in the region 5 is placed between a punch 10 and a die 11, the surface of the punch 10 facing the carrier 1 having a relief 13. Stamp 10 and die 11 are moved in the direction of the carrier 1. The directions of movement are indicated by arrows 15 in FIG. 3c. After contact with the carrier 1, a pressure between about 5 to 100 bar, preferably of a few bar on the carrier 1 in the region 5, i. in the region provided with the reactive substance. As a result, relief is produced by the relief 13 of the stamp 10 on the surface of the carrier 1 in the region 5 in which the reactive substance is contained in the volume of the carrier 1, which corresponds to the negative of the stamp relief 13.

In further embodiments, only the punch 10 can be moved in the direction of the carrier 1, while the die 11 remains at rest. Conversely, it is also possible to leave the punch 10 at rest and to move the die 11 in the direction of the carrier 1.

During the contact of the punch 10 and the die 11 with the carrier 1 takes place a heat transfer and / or irradiation with electromagnetic Radiation. This electromagnetic radiation can take place, for example, through the stamp 10 and the stamp relief 13 and / or the die 11. For this purpose, if necessary, the punch 10 and the stamp relief 13 and / or the die 11 must be formed so that they are transparent to the corresponding electromagnetic radiation. The electromagnetic radiation can be generated for example by means of a laser of the appropriate wavelength or a mercury vapor lamp. By the heat input and / or the irradiation by means of electromagnetic radiation hardening and / or crosslinking of the reactive substance in the region 5 is achieved so that on the one hand the desired transparency changes in the region 5 are present, and the information explained in FIG. 1 in the region 5 visible are. On the other hand, the stamped relief 13 generates the desired surface relief 7 at least in partial regions of the region 5.

The stamp relief 13 is designed according to the desired first and second information. If, as in the example of FIG. 1, a microrelief, which represents, for example, an embossed hologram, is to be realized only in subregions of region 5, then the negative of this microrelief is also provided only on the corresponding subregions. The remainder of the surface of the punch 10, which corresponds in extent to the extent of the region 5, has a plane which is in contact with the remaining regions of the region 5 in the state, the heat action and / or the electromagnetic radiation, or at least from them only a small distance. Thus, heat and / or electromagnetic radiation can also act on the remaining regions of the region 5 and, accordingly, the change in transparency can be generated to display the first information. The design of the first information is determined by the print pattern.

The result of the last method step is shown in FIG. 3d. It corresponds to the figure 2.

The surface relief 7 in the area 5 contains at least one additional piece of information that can be used to verify the security feature in area 5. In order to achieve the desired diffractive microstructures, so-called nickel shims are used as punches 10 in a preferred embodiment. Such a nickel shim is designed to achieve the heat input, heatable. In a further embodiment, the stamp 10 may also be embodied as a quartz glass shim, which is characterized in that it is transparent to electromagnetic radiation, for example UV radiation, and thus enables the treatment of the region 5 with electromagnetic radiation.

Finally, in a preferred embodiment, the microstructures can be provided with a suitable, transparent protective lacquer which protects the surface of the support 1 against mechanical influences, in particular abrasion. As examples of such protective coatings, in addition to the conventional protective coatings, "nano-based" scratch-resistant coatings may be mentioned, which are also used in the automotive industry. The now present sheet or roll from the carrier 1 with the security feature of the invention will now be processed as usual. The carrier 1 can be provided, for example, with further printing or pasted security features. It may also be followed by a punching step, which serves to provide the carrier 1 with the desired dimensions.

In the following, three examples of the method according to the invention will be illustrated.

Via a flexographic printing unit, a mixture of a melamine impregnating resin (Kauramin®-752, -753, -786 or -787, BASF) of a hardener (Hardener 527, 529 for Kauramin® and Kaurit® impregnating resins, BASF ) and polymer dispersion Kauropal®-937, -938 at one speed printed at 30 m / min and this led into a hologram embossing tool. By means of a heated nickel shim the diffractive microstructures are imprinted at temperatures of 50 - 200 ° C. A paper roll buffer ensures that the embossing tool, consisting of punch and die, and the stamped product, the carrier 1, are at rest relative to each other during embossing. Subsequently, a UV-curable scratch-resistant coating is applied with a roller offset printing unit.

In a further exemplary embodiment, a mixture of bi- and tri-functional acrylates (eg SR-9003 and SR-415 from the company Sortomer, Laromer®-DPGDA, Laromer-LR 8863, BASF) with a photoinitiator (Irgacure® 2020, Irgacure® 819, Darocure® 1173, Ciba) are printed on a paper sheet and then transferred to the embossing tool with quartz glass shim. During the embossing, UV radiation with a power density of more than 150 W / cm ^{2 is} irradiated through the quartz glass and the printed area 5 is cured. Subsequently, a UV-curable scratch-resistant coating is applied with a roller offset printing unit.

Alternatively, in the last exemplary embodiment, a coating or a varnish with high cohesion or scratch resistance can already be used when printing the region 5, so that the sealing step is saved.

In a further embodiment, a solution of N-methylmorpholine-N-oxide (NMMO) in water is applied to the region 5 of the carrier 1 via an inkjet printer on a paper web or a paper sheet. The embossing is then carried out with a nickel shim at temperatures of less than 100 ° C. Subsequently, the area 5 is sealed with a scratch-resistant paint. The peculiarity of this embodiment is that aqueous solutions of NMMO dissolve or dissolve cellulose with softening of the fiber structure, so that the cellulose is almost plastically deformable.

Reference will now be made to the relationship of the dimensions of the transparency and relief height change with reference to FIG. FIG. 4 a shows a section from region 5 in which the change in transparency is shown schematically by gray hatched areas. The extension d1, in which the change in transparency in the direction of the support surface has a specific, predetermined value, is indicated by a double arrow. Over the path length d1, the transparency changes from a certain, fixed high to a certain, fixed low value. The values are set, for example, as the value of the highest transparency or the value of the lowest transparency in the region 5. Average extensions d1 in the region 5 can be about 1 mm to 100 mm, preferably 5 mm to 30 mm. FIG. 4b shows a section of the relief region 7 in a view from the side. The extent d2 is entered in the direction of the carrier surface, which has a specific, fixed relief height change. The extent d2 describes the distance between a location in which the relief has a certain, large height and an adjacent location in which the relief has a predetermined low height. On average, possible expansions d 2 are about 0.05 to 1 μm, preferably on average about 0.2 μm to 0.6 μm for holograms, kinegrams and other diffractive structures. For other optical microstructures given above, the dimension d2 is on average about 1 μm to 200 μm, preferably about 50 μm to 80 μm on average. For good visibility of the second information represented by the relief 7, it is necessary that the mean extents of the relief height change d2 be small to the mean extents of the transparency changes d1.

Claims (14)

1. Security mark with a carrier (1), which has a region (5) in which through a substance that is subsequently applied and hardened, transparency modifications are present in the volume of the carrier, through which at least one first item of information is represented, wherein the carrier in at least one part of this region additionally has a surface relief (7),
   characterised in that through the surface relief, at least one second item of information or an optically effective verification element is represented.
2. Security mark as claimed in claim 1, characterised in that the carrier (1) consists at least in part of cellulose fibres.
3. Security mark as claimed in one of the preceding claims, characterised in that at least in one part of the region (5), the average extension of a particular, prescribed transparency modification (d1) is large in relation to the average extension of a particular, prescribed change in relief height (d2) in the region.
4. Security mark as claimed in one of the preceding claims, characterised in that the transparency modifications in the carrier (1) in the region (5) reach a depth at least of 50 µm.
5. Security mark as claimed in one of the preceding claims, characterised in that the security mark has a protective lacquer layer on its surface.
6. Security mark as claimed in one of the preceding claims, characterised in that the region (5) of the carrier (1) has pigments that fluoresce when subjected to electromagnetic radiation.
7. Security mark as claimed in one of the preceding claims, characterised in that the surface relief at least in one part of the region (5) has an embossed hologram structure.
8. Security mark as claimed in one of the preceding claims, characterised in that the optically effective verification element is a lens structure.
9. Data carrier with a security mark as claimed in one of the preceding claims.
10. Method for the production of a security mark on a data carrier with a carrier (1), wherein a substance which is provided for transparency modification, and which can be hardened, is applied to a region (5) of the carrier, wherein the substance in the region penetrates into the volume of the carrier,
    characterised in that at least parts of the region are equipped with an imprint (7), and at the same time the hardening of the substance and the transparency modification effected by the substance takes place in the region, wherein by means of the transparency modification brought about by the substance in the region at least one first item of information is represented, and by means of the imprinting at least one second item of information or optically effective verification element is represented.
11. Method as claimed in claim 10, characterised in that hardening takes place by means of the application of heat or electromagnetic radiation.
12. Method as claimed in claim 11, characterised in that for hardening, electromagnetic radiation in the UV, IR or visible wave range is used.
13. Method as claimed in one of the claims 10 to 12, characterised in that the substance which is provided for transparency modification, and which can be hardened, is imprinted.
14. Method as claimed in one of the claims 10 to 13, characterised in that as the substance, resinous compounds or polyurethane compounds are applied.

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