DE102016009440A1 - Method for producing a security element - Google Patents

Abstract

The invention relates to a method for producing a security element (1), wherein a substrate (2) is provided that is translucent at least for certain radiation (10) and has a watermark (3) which modulates the opacity of the substrate (2). wherein on one side (6) of the substrate (2) an embossing layer (7) is applied, which covers the watermark (3), a holgram structure (9) is embossed into the embossing layer (7) and on the holgram structure (9) a reflector layer (8) is applied, and the substrate (2) from the opposite side (6) with the particular radiation (10) is irradiated, wherein an intensity of the radiation (10) is adjusted so that the watermark (3) by means of it caused opacity modulation acts as a mask and the reflector layer (8) by the radiation (10) in the register to watermark (5, 11) is removed structured.

Description

The invention relates to a method for producing a security element, wherein a substrate is provided which is translucent at least for certain radiation and has a watermark which modulates the opacity of the substrate.

To increase the security against forgery of protected objects, for example banknotes, watermarks are known. They are usually introduced in the production of the substrate from which the security element is made, usually a paper. Watermarks are easily recognizable when the security element is viewed through transmitted light, since they modify the opacity of the substrate. As a rule, in the production of the paper, the thickness of the substrate is varied, so that a local reduction in thickness leads to a local reduction in opacity. However, other approaches to generating a watermark are also known, for example using so-called watermark colors, which also locally modify the opacity of the substrate.

Watermarks are formed in the substrate in the production of the security material starting material, for example in the manufacture of banknote paper. Due to variations in the cutting process of a paper substrate, paper sheets usually have variations in the position of the watermark, which are in the millimeter range. Therefore, it is difficult to arrange other security features in an exact location to the watermark, so to pass.

To apply a security feature in the register to a watermark, it describes the WO 2013/124059 A1 as conceivable, by means of a transmission sensor to detect the position of the watermark in the substrate, and to set a subsequent printing process to the current position of the watermark, z. B. by a mechanical adjustment of a printing cylinder or correction of the printing data of a digital printing system. However, it has been shown that watermarks are usually difficult to detect accurately with an image recognition. In particular, the edge structures of a watermark are usually provided with a contrast profile, which makes accurate measurement of the position of the watermark difficult.

The WO 2013/0124059 A1 as well as the EP 2199095 A2 describe that a watermark can be used as a mask for laser radiation to pattern a layer printed on the watermark. For example, a laser-ablatable print layer can be arranged above the watermark, and the opacity variation, which has the watermark, serves to remove the print layer in a structured manner in the exact register to the watermark. However, this procedure is limited to print layers which, in addition, have a contrast characteristic identical to the watermark after removal.

Holograms are known for securing items or documents from counterfeiting. They are particularly hard to fake.

The invention has for its object to provide a method by which a security element is generated in which a hologram image in the register is a watermark.

This object is achieved according to the invention with a method for producing a security element, wherein a substrate is provided which is translucent at least for certain radiation and has a watermark which modulates the opacity of the substrate, wherein a stamping layer is applied to one side of the substrate the watermark is at least partially covered, a holgram structure is embossed into the embossing layer and a reflector layer is applied to the holgram structure, and the substrate is irradiated from the opposite side with the particular radiation, an intensity of the radiation being adjusted so that the watermark is adjusted by means of the Opacity modulation caused by it acts as a mask and the reflector layer is removed in a structured manner by the radiation in the register to the watermark.

The invention is based on the concept of WO 2013/0124059 A1 on, which can generate a printing element in the register to a watermark. Based on this concept, the reflector layer, which is located on a stamped embossed layer with a hologram, is now structured. As a result, the reflector layer remains only in dark areas of the watermark, and the remaining hologram stands in perfect register with the watermark, since a reflective hologram is only visible in the non-ablated areas of the reflector layer. The hologram is effective only in the areas as a reflective hologram in which the reflector layer has not been removed. Optionally, in areas where the reflector layer has been removed, holographic structures which are still slightly visible can be suppressed by the optional application of a protective lacquer to the regions of the hologram structure exposed by the removal of the reflector layer. This is because the hologram structures are open after ablation in these areas and when covered with a protective lacquer no longer form a holographically effective structure, especially when the Refractive index of the resist is adjusted within +/- 0.2 to the embossing layer.

The watermark may be a so-called "true watermark" if the substrate is a paper substrate. The watermark is then formed by depressions on a screen side of the substrate and modulates the thickness of the substrate. It is then preferred to apply the embossing layer and the reflector layer on the opposite felt side of the substrate, since this is flat. A watermark that modulates the opacity of a substrate can also be generated by a so-called watermark color, rather than by varying the thickness of the substrate. The watermark color causes a reduction of the scattering of light in the substrate core. Basically, scattering is due to a large number of interfaces of fibers, organic and inorganic fillers, glue, etc. to the surrounding air. These ambient airborne interfaces are significantly reduced by suitable binder components in the watermark ink, thus decreasing opacity in these areas. Such a binder component is, for example, glycerol, which penetrates into the substrate and remains in the pores of the substrate. The same applies analogously if the watermark is caused by a coloration which modulates the opacity of the substrate.

Another possibility for modulating the opacity of the substrate are substrate erosions and / or substrate recesses by, for example, laser technology, grinding and / or punching, optionally in combination with a paper-made watermark and / or a watermark color.

In addition, the hologram can be combined with a Stahldruckverprägung. A steel print embossment passes through the entire substrate and leads to a tactile perceptible structure that is comparatively coarser than the hologram structure.

The reflector layer can be provided with further pigments or dyes to produce additional register-containing effects.

The embossing layer can be a UV-curable embossing lacquer or a thermoplastic lacquer.

The embossing layer or the reflector layer can be provided with laser-sensitive dyes, so that the hologram, which is generated by the hologram structure, an additional color motif by the laser-sensitive dyes that have been modified during the ablation and complement the watermark register.

After removal with the laser radiation, it is possible to apply a different colored mirror layer, so that the reflective hologram in the color of the reflector layer, the reflective hologram in color of the differently colored mirror layer and the watermark complement each other in register.

The term hologram structure is generally understood to mean a diffractive structure, in particular a diffractive structure, which makes a hologram recognizable. But there are also other diffractive effects possible.

The term "certain radiation" as used in this description therefore expresses that it can remove the reflector layer. The ablation is achieved when the particular radiation has an intensity suitable for ablation at the exit on the side of the reflector layer. The opacity modulation caused by the watermark reduces the intensity of the radiation on the side on which the reflector layer is located. The irradiated radiation intensity is therefore adjusted so that the opacity modulation effected by the watermark results in a radiation modulation which modulates the ablation effect. Thus, the watermark serves as a mask in the irradiation of the substrate with the specific radiation.

Items to be protected within the scope of this description may include, for example, security papers, identity and value documents (such as banknotes, chip cards, passports, cards, identification cards, identity cards, stocks, bonds, certificates, vouchers, checks, tickets, credit cards, health cards,. ..) and product safety elements, such. As labels, seals, packaging, be.

The term security paper is understood here in particular as the precursor that can not yet be processed to form a value document (eg a card) which, in addition to the pressure produced according to the invention, can also have further authenticity features (such as luminescent substances provided in the volume, for example). Under value documents here on the one hand from security papers produced documents, eg. B. banknotes understood. On the other hand, value documents can also be other documents and articles which are processed with the printing method according to the invention, so that the value documents have non-copyable authenticity features, whereby an authenticity check is possible and at the same time unwanted copies are prevented.

The substrate is particularly preferably made of paper made of cotton fibers, or substantially of the natural polymer cellulose, as it for example, is used for banknotes. Preferably, the substrate may also be made of paper of other natural fibers, also preferably of synthetic fibers, ie a mixture of natural and synthetic fibers. More preferably, the substrate consists of a combination of at least two superimposed and interconnected different substrates, a so-called hybrid. It may be, for example, a combination of plastic film paper or even a three-layer composite, such as plastic film paper plastic film, ie a paper substrate is covered on either side by a plastic film, or paper plastic film paper, ie Substrate made of a plastic film is covered on each side by a paper substrate.

Optionally, the substrate consists of an at least partially transparent plastic film. The watermark is generated in this case by a color which is applied to one side of the substrate and whose hue is at least similar to the hue of the substrate. Such a watermark is for example off DE 10 2009 056 462 A1 known.

Plastic films may include, for example, polypropylene, polyethylene, polyethylene terephthalate, and polyamide.

Under translucency or translucent in this description, the partial translucency of a body understood, so the property of transmitting light scattering. Translucency is to be seen, among other things, in contrast to the transparency (= image or eye transmittance). The reciprocal property of translucency is opacity. As far as there is talk here that a watermark modulates the opacity, it can equally be said that it inversely modulates the translucency.

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

The invention will be explained in more detail by way of example with reference to the accompanying drawings, which also disclose features essential to the invention. Show it:

1 a sectional view through a security element in a first embodiment and

2 a sectional view similar to the 1 by a security element of a second embodiment.

1 shows a sectional view through a security element 1 that on a substrate produced in the embodiment paper-based 2 is constructed. The security element 1 has a watermark 3 on that the thickness of the substrate 2 and thus modulates its opacity. In the embodiment of the 1 the watermark is formed by the fact that during the production of the substrate 2 wells 4 in the top 5 of the substrate 2 were incorporated. Wells are examples of forming regions of reduced pulp (and reduced opacity). They can also be formed on the bottom. Due to the production method of the watermark 3 becomes the top 5 also referred to as the sieve side; the opposite bottom 6 as felt side.

On the bottom 6 is a pre-history 7 applied, on which a reflector layer 8th , z. As a metallization is located. In the pre-history 7 is before the application of the reflector layer 8th a hologram structure 9 imprinted, which together with the reflector layer 8th a reflection hologram viewed from the top 5 makes recognizable. The reflector layer 8th is first applied flat, ie without initial structuring. A structuring is done by the top 5 laser radiation 10 is irradiated, the intensity of which is adjusted so that they are in the areas of the wells 4 the reflector layer 8th after passing through the substrate 2 from the pre-history 7 erodes. In areas without depressions 4 is the intensity of the laser radiation 10 so far weakened that no removal of the reflector layer 8th more is done. In other words, the intensity of laser radiation 10 is set exactly so that when passing through the substrate 2 in no reduced thickness just no removal of the reflector layer 8th more occurs, with reduced thickness due to the depressions 4 However, a removal is achieved. In this way, the watermark modulates 3 the removal of the reflector layer 8th ,

From the top 5 becomes the laser beam 10 over the substrate 2 guided. He radiates through the substrate 2 , The wavelength of the laser beam is such that the reflector layer 8th absorbs the radiation. The laser beam 10 will depend on the opacity of the substrate 2 which by the watermark 3 modulated, attenuated. At a position where the substrate has high opacity by the watermark, the laser beam becomes 10 strongly weakened. At a point where the substrate 2 has reduced opacity, the laser beam is less attenuated. The intensity of the laser beam 10 is adjusted so that a modulation of the Ablation effect results, which the laser beam 10 on the on the Prägeschicht 7 applied reflector layer 8th Has.

By structuring ablation at the bottom 6 become watermarks in individual areas in the Passer 3 exposed sections of the pre-history 7 generated. These sections no longer act as a reflective hologram. The only thing left to do is the areas in which the metallization 8th remained and acts as a reflector layer. To prevent areas with exposed hologram structure 9 under certain viewing conditions could still be visually noticeable, is additionally a protective coating 13 applied to the entire pre-history 7 covered at least in the exposed areas. A precise structuring is not required because it is completely harmless when the protective coating 13 also the reflector layer 8th covers. Because the protective paint 13 has a refractive index which is at most 0.2 of that of the embossing layer 7 deviates, the protective lacquer equalized the hologram structure 9 in the exposed areas where no reflector layer 8th is more, and makes a remaining, slightly perceptible holographic effect optically disappear entirely.

Basically, top are 5 (Screen side) and bottom 6 (Felt side) interchangeable, ie Prägeschicht 7 and reflector layer 8th (eg metallization) could also be applied to the screen side.

1 shows the manufacturing method for a substrate 2 that is a watermark 3 in the form of depressions 4 Has. 2 refers to an embodiment where the watermark 3 by a watermark color 11 is generated. The structuring of the reflector layer 8th doing the same thing - with the difference that not with watermark color 11 printed areas of the substrate the wells 4 correspond, so areas with lower opacity of the substrate 2 are.

2 shows yet another, optional embodiment to the effect that after the structured removal of the reflector layer 8th additionally a further mirror layer 12 is applied, which is not further structured. So it covers both the reflector layer 8th as well as the reflector layer 8th exposed areas of the hologram structure 9 from. The mirror layer 12 differs from the reflector layer 8th in terms of their color effect. In this way, two hologram structures are created, which complement each other in register, namely the hologram structure with the reflector layer 8th and overlying mirror layer 12 (eg also metallization), which cause a first color effect for the reflective hologram, the hologram structure only with the mirror layer 12 , which cause a second color effect for the hologram structure, as well as the watermark 3 , Of course, this embodiment with the further mirror layer 12 also with a real watermark according to 1 and is not limited to having a watermark color 11 to be implemented. The same applies to the protective lacquer 13 who also in 2 can be used.

Contains the substrate 2 printable window or is it fully transparent, there is also a different holographic effect of top 5 and bottom 6 , One then obtains a two-sided different color of the hologram in perfect register.

It is also possible to provide the embossing layer and / or the reflector layer with a laser-modifiable substance which is modified during removal with the laser radiation, so that in addition a colored motif is obtained which is in the register for the watermark 3 and the hologram stands.

LIST OF REFERENCE NUMBERS

1

security element

2

substratum

3

watermark

4

deepening

5

top

6

bottom

7

embossing layer

8th

reflector layer

9

hologram structure

10

laser beam

11

Watermark Color

12

mirror layer

13

protective lacquer

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2013/124059 A1 [0004]
• WO 2013/0124059 A1 [0005, 0009]
• EP 2199095 A2 [0005]
• DE 102009056462 A1 [0022]

Claims (7)

Method for producing a security element ( 1 ), wherein - a substrate ( 2 ) provided at least for certain radiation ( 10 ) is translucent and a watermark ( 3 ), which reduces the opacity of the substrate ( 2 ), characterized in that - on one side ( 6 ) of the substrate ( 2 ) a pre-history ( 7 ), the watermark ( 3 ) at least partially covered, - a hologram structure ( 9 ) into the pre-history ( 7 ) and the hologram structure ( 9 ) a reflector layer ( 8th ), and - the substrate ( 2 ) from the opposite side ( 5 ) with the particular radiation ( 10 ), wherein an intensity of the radiation ( 10 ) is adjusted so that the watermark ( 3 ) acts as a mask by means of the opacity modulation effected by it and the reflector layer ( 8th ) by the radiation ( 10 ) in the register to the watermark ( 3 ) is removed in a structured manner. A method according to claim 1, characterized in that the substrate ( 2 ) is a paper-based substrate and the watermark ( 3 ) by areas of reduced mass of the substrate ( 2 ) a thickness of the substrate ( 2 ) and the pre-history ( 7 ) and the reflector layer ( 8th ) on the laser beam ( 10 ) opposite side ( 6 ) of the substrate ( 2 ) are applied. Method according to claim 1, characterized in that the substrate ( 2 ) is a film or composite substrate and a watermark color ( 11 ) on at least one of the substrate sides ( 5 . 6 ) the opacity of the substrate ( 2 ) and the pre-history ( 7 ) and the reflector layer ( 8th ) on the laser beam ( 10 ) opposite side ( 6 ) of the substrate ( 2 ) are applied. Method according to one of the preceding claims, characterized in that the embossing layer ( 7 ) and / or the reflector layer ( 8th ) contains a laser-modifiable substance and when removing an additional motif is generated. Method according to one of the preceding claims, characterized in that after the removal of the reflector layer ( 8th ) on this a different colored mirror layer ( 12 ) is applied. Method according to one of the preceding claims, characterized in that the embossing layer ( 7 ) is provided with laser-sensitive, chromatic, fluorescent, metallic or effect pigments. Method according to one of the above claims, characterized in that above the reflector layer ( 7 ) after their structurable erosion and the areas of the hologram structure thereby exposed ( 9 ) a protective varnish ( 13 ) is applied.

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