EP3286010A1

EP3286010A1 - Method for producing a security element with register between printed element and watermark

Info

Publication number: EP3286010A1
Application number: EP16716473.0A
Authority: EP
Inventors: Jana Kisselova; Harald Reiner
Original assignee: Giesecke and Devrient Currency Technology GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2015-04-21
Filing date: 2016-04-11
Publication date: 2018-02-28
Anticipated expiration: 2036-04-11
Also published as: DE102015005083A1; WO2016169640A1; EP3286010B1

Abstract

The invention relates to a printing method for producing a security element (1). A substrate (2) has a watermark (5) which modulates the opacity of the substrate (2). A printed element (9) which at least partly covers the watermark (5) and contains at least one first and a second color layer (9, 22) is applied onto a front face (3). The first color layer (9) can be ablated by means of a first specified radiation (10) and the second color layer (22) cannot. The specified radiation (10) is emitted through the substrate (2) from the rear face (4), and the first color layer (9) is ablated by the specified radiation (10). The watermark (5) is used as an intensity mask in order to modify the printed element in register with the watermark (5). The first color layer (9) is a remitting colorant, and the second color layer (22) is a luminescent colorant, the first color layer (9) covering the second color layer (22). Because the first color layer (9) is ablated by the specified radiation (10) using the watermark (5) as a mask, the second color layer (22) is exposed at some locations (46) such that the luminescent effect of the second color layer is stronger at these locations (46).

Description

G e t i o n c e m e n t i o n s

S e c tio n s with Pa s s e r s

c u st e m e n t i o n d d a tio n s

Wa w ith s

The invention relates to a method for producing a security element, wherein a substrate is provided, which has a front and a back, at least for certain radiation is translucent and has a watermark, which modulates the opacity of the substrate is applied to the front of a printing element which at least partially covers the watermark and which contains at least a first and a second colorant, wherein the first colorant is ablatable by the first specific radiation and the second is not and the substrate irradiates from the backside with the particular radiation and the first colorant of the first predetermined radiation is ablated, the watermark being used as a mask to modify the printing element in the register to the watermark.

Such a method is known from DE 102012003601 AI.

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 considered, 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 reduction in thickness leads to an opacity reduction. But there are also other approaches for generating a watermark known, for example by means of so-called Watermark colors that also locally modify the opacity of the substrate.

Since watermarks are usually formed in the substrate in the production of the starting material for the security element, for example in the production of a banknote paper, it is fundamentally difficult in later printing to arrange printed elements in an exact position relative to the watermark, that is to pass. This problem arises regardless of the specific design of the printing element, not only when printing with different inks, but also during coating or application with printing elements, when applying transfer films or laminating or when applying a window filament.

The aforementioned DE 102012003601 AI therefore proposes to use the locally varying opacity of the watermark as a mask to modify a previously applied surface pressure element in the register to the watermark by means of laser radiation. As an example of the modification, ablation is mentioned. It is also apparent from the document that the pressure element may contain a mixture of substances that are modifiable and that are not modifiable. It is also known to make the printing ink visually visible or invisible. The watermark serves as a mask which modulates the intensity of the transmitted radiation, whereby the printing element is modified, for example ablated. As a result of the system, a perfect registration between the laser structuring, which is introduced into the printing element, and the watermark is achieved.

Based on this prior art, the invention is based on the object to provide a manufacturing method for a security element whose security against counterfeiting is increased again. This object is achieved according to the invention with a method for producing a security element, wherein a substrate is provided which has a front and a back, at least for certain radiation is translucent and has a watermark, which modulates the opacity of the substrate, on the front Printing element is applied, which at least partially covers the watermark and containing at least a first and a second colorant, wherein the first colorant is ablatierbar by means of the first specific radiation and the second not, and the substrate from the back irradiated with the particular radiation and the ablating the first colorant from the particular radiation, the watermark being used as a mask to attenuate the intensity of the particular radiation to modify the printing element in the register to the watermark, the first colorant being a remittent colorant having a color effect i and the second colorant is a luminescent colorant and is disposed in a second color layer, the first color layer covers the second and wherein the second colorant is exposed at locations by using the first colorant using the watermark as Mask ablated from the first specific radiation or changed in terms of Farbef- effect.

The object is also achieved according to the invention with a method for producing a security element, wherein a substrate is provided which has a front and a back, at least for certain radiation is translucent and has a watermark, which modulates the opacity of the substrate, on the front a printing element is applied, which at least partially covers the watermark and which contains at least a first and a second colorant, wherein the first colorant is ablatierbar by means of the first specific radiation and the second, and the substrate is irradiated from the backside with the particular radiation and the first colorant is ablated from the particular radiation, the watermark being used as a mask to attenuate the intensity of the particular radiation to modify the printing element in the register to the watermark, wherein the first colorant is a colorant remitting colorant and the second colorant is a luminescent colorant, the first colorant and the second colorant are disposed in a common color layer, and the second colorant is exposed at locations by using the first colorant using the watermark is changed as a mask of the first specific radiation in terms of its color effect.

The second colorant is exposed in both variants mentioned (colorant in separate color layers or in a common color layer) by changing the color effect of the first colorant and thus repealed. This can be done by completely or partially removing the first colorant from the corresponding color layer. Alternatively, it is also possible that only the optical properties of the colorant are changed so that it no longer shows the color effect. This is possible, for example, by breaking bonds in the colorant, for example in pigments. It is therefore possible according to the invention to change the colorant with regard to the color effect, both by removing it from the layer (ablation) and, while it remains in the layer, but is modified there. As far as the option of ablation is described below, this is to be understood as an example only, and the corresponding description also refers to the variant that the first colorant is modified. To make the luminescent image in the register to the see-through or on viewing image, the invention either achieved by providing the first colorant in a first color layer and the second colorant in a second color layer and the two color layers are arranged so that the first color layer on the second color layer is, or that both colorants are in a common color layer. In the separate color layers, the first colorant is removed / modified by ablating / modifying the first color layer, and the second colorant in the second color layer is exposed. As a result, the brilliance of the second colorant is particularly large. If the colorants in a common color layer, the production is easier. The first colorant is then ablated / modified from the color layer so that the effect of the second colorant thus increases in the color layer. The invention therefore forms the concept disclosed in DE 102012003601 A1 of making a modification of a previously applied printing element by radiation, wherein the watermark is used as a mask for intensity attenuation of the radiation, to the effect that the particular radiation is only one of two colorants ablated. Thus, at the locations where the first colorant is removed, the second luminescent colorant is exposed, which also means that the concentration of the second colorant in the layer system increases. When viewed normally, the security element offers a sight, as it is known from DE 102012003601 AI. When viewed under illumination which excites the luminescence of the second colorant, a luminescent image is shown which is negative to the supervisory image under normal illumination and to the see-through image. The images are in perfect register with each other, since the second colorant is exposed there and gives off strongly the luminescent radiation, where the first colorant was removed. The design of the watermark also allows a multistage or even continuous variation of the opacity of the watermark and thus a corresponding multistage or uniform variation of the ablation / modification of the first colorant. Also in these cases, the exposure of the second colorant and thus the intensity of the image recognizable in luminescence is inverse to the color impression, which is mediated in a plan view or in a view through the first colorant.

In a further development, DE 102012003601 A1 provides that the pressure element cooperates with an additional layer whose visual effect depends on the previous modification of the pressure element. Thus, it is known, for example, for optically variable layers that they are particularly clearly recognizable on a dark or black background in incident light. After the printing element has been provided by the specific radiation with a contrast structure, flat, d. H. Without Passeranforderungen an optically variable layer are applied, the visual effect on around the precise registration of acting as a background pressure element then automatically in the register to the watermark, although the optically variable layer itself was applied without register requirements. In this multilayer system, a part of the layer system is applied and illuminated with the specific irradiation. Another part of the layer system is then applied only after the exposure.

The physical removal of the first colorant can be done directly or indirectly. In the latter case, the particular radiation removes an element which in turn removes all or part of the first color layer or colorant. For example, by means of the specific radiation, a layer can be modified which adversely affects the adhesion of the first color layer to the second color layer. After the modification of this direction influencing layer is then removed in a further step, the first color layer in the areas in which the adhesion was modified (or not modified in the inverse case). The procedure is similar to the principle of the so-called wash color.

Another possibility is an indirect modification of a developer layer which, in cooperation with a developer or fixing medium, modifies the first color layer at those points at which the developer layer has been suitably exposed. Indirect influence is also possible in a two-stage process if the printing element has an adhesive layer for the first color layer, which is applied to the front side and exposed from the rear side with the participation of the watermark as a mask. In a second step, the first ink layer of the printing element can then be applied, which adheres only to those places where the exposure took place. Optionally, the exposed adhesive layer can also be acted upon here in an intermediate step so that it remains only in those areas in which a suitable exposure took place (positive effect) or remains in those areas in which no suitable exposure took place (negative effect).

In the context of this description, the term "printing element" is understood to mean an element which is applied to a substrate and, if appropriate, realizes a visually or mechanically evaluable element after further processing.Of course, printing elements based on printing inks are most widely used , this is to be understood by way of example for a printing element.

As far as spoken in this description and in particular in the claims that of "printing element" or "printing ink" and the application this printing element on the front side above the watermark is also included in that of a printing element layer system only a part of the layer system is applied and exposed to the specific irradiation; the other part is then applied after these steps and interacts with the exposed portion of the layer system to create a printed image in the watermark to the watermark.

Colorants or coloring substances are known to be subdivided into dyes and color pigments. Dyes are colorants that are soluble in the application medium, whereas color pigments are colorants that are insoluble in the application medium.

The terms "colorant" and "color" are not limited to a colorful sensory impression with respect to the remittant colorant. An achromatic effect, for example by black or metallic colorants, is possible for the remittant colorant. The remittant colorant may in particular achromatic pigments, such as. As black or silver pigments, colored pigments, effect color pigments or color shift pigments.

Colorants with silver pigments are printed, for example, with a layer thickness or mass per unit area of 0.5 g / m ² to 2.0 g / m ² and preferably from 0.8 g / m ² to 1.5 g / m ² . The watermark can be generated by varying the thickness of the substrate at a constant density, by varying the density of the substrate with a constant thickness or by a so-called watermark color. The latter are also referred to as "spurious" watermarks. The watermark can binary modulate the opacity of a substrate. In other words, it produces a structure which can be seen in the transparency in that at individual points the substrate is less opaque or more translucent than at other points. But there are also watermarks in the sense of a gray scale modulation possible, which modulate the opacity or translucency between two maximum values. In the transmitted light view, one then recognizes a grayscale image. Both types of watermarks are equally suitable for the present printing process. In the case of a watermark which is designed in the manner of a gray scale image, it is of course particularly advantageous to use an ink whose modifiability goes beyond a simple threshold value modification, the modification of which thus knows more than two states. The multi-level modulation by the watermark is then converted into a corresponding multi-stage modification of the printing element. The first color layer or colorant and the particular radiation are matched to one another such that the particular radiation is capable of ablating / modifying the first colorant, the watermark modulating the opacity of the substrate being used as a mask to modulate the colorant Intensity of the particular radiation is used. The term "certain radiation" expresses this: the ablation / modification is achieved when the particular radiation at the front has an appropriate intensity, and the opacity modulation caused by the watermark modulates the intensity of the radiation on the front surface on which the radiation is emitted The radiation intensity on the backside is therefore adjusted so that the opacity modulation caused by the watermark on the front side results in a radiation modulation that modulates the modification / ablation effect, in other words, the radiation intensity on the backside becomes chosen so that at the places where the watermark is the lowest Opacity in the substrate causes the greatest effect occurs, where no or only a very small ablation / modification is achieved at the points where the watermark causes the highest opacity of the substrate. Thus, the watermark serves as an intensity mask when the substrate is irradiated with the particular radiation.

The exposed second luminescent colorant shows in the luminescence image, which is recognizable, for example when viewed under illumination containing UV, a main pattern which is defined by the structure of the exposed second colorant. If the particular radiation is applied so that the first colorant is either completely or completely removed, the luminescence image corresponds to a pure black and white image without tints. Equally, it is also possible to adjust the ablation by the watermark so that a partial ablation of the first colorant takes place. This partial ablation weakens the absorbing effect of the first

Colorant such that at the partially ablated sites in the luminescent image there is an intensity which is between that which is obtained upon complete exposure of the second colorant and that present with the first colorant unaffected. Alternatively and additionally, of course, a grayscale representation by half or multi-tone screening is possible, as is known in the gray scale representation by screened image representation. Finally, the watermark is then patterned accordingly to provide the appropriate variation of opacity as an intensity mask for the effect of the particular radiation on the first colorant.

Since ablation usually requires a comparatively high radiation intensity, it is advantageous to use a beam that is scanned over the back of the substrate. The beam may be in the form of a laser beam, for example. It is then not only easy to To provide Liche radiation intensity, the intensity adjustment can be done easily, since it is less effort to adjust a beam in its intensity, as to effect a homogeneous intensity adjustment of a fanned light beam. Nevertheless, for certain embodiments, far-field radiation of the particular radiation is also possible.

The use of a rastered beam has the advantage that the intensity of the particular radiation can be varied in addition to using the water mark as a mask to effect additional patterning according to a first auxiliary pattern. Of course, this additional pattern is not in the register for the watermark. It is therefore provided in a development that the specific radiation is structured or modulated so that a first additional pattern is omitted, that is not irradiated, in which then consequently the first colorant is not ablated. As a result, in this first additional pattern, the intensity of the luminescence radiation from the second colorant remains further attenuated due to the non-ablated first colorant, which makes the first additional pattern clearly recognizable in the luminescence image.

In a development, a second additional pattern is formed with the second colorant. This development can be combined with the training that forms the first pattern. The second additional pattern is produced by also removing the second colorant in the exposed areas with another radiation. In the luminescence image, the second additional pattern can then be recognized by locations of no luminescence. In the region of the second additional pattern not only the first colorant is removed, but also the second luminescent colorant. This embodiment can be realized particularly simply by the fact that the particular radiation and the further radiation originate from the same laser source, for example in that the laser source emits pulsed laser radiation in order to provide the specific radiation, that is to say to ablate the first colorant, and to emit continuous wave radiation in order to ablate the second colorant.

In another development, which can be combined with those of the first and / or second additional pattern, a third additional pattern in the form of a recess in the color layer is provided when applying the first and second color layer. The effect of this third additional pattern is substantially the same as that of the second additional pattern, however, this third additional pattern can be placed completely independent of the variation of opacity by the watermark, since no color layer removal is necessary in the structure of the third motif. It is also possible in areas outside the watermark.

As a second color coat, in particular metallic pigments come into question. They achieve an additional protection against counterfeiting, since in addition a gloss effect is perceptible, which at those places, at which the first color layer was completely or partially ablated, is correspondingly omitted or reduced.

The first color layer and the second color layer are selected such that in a wavelength range in which the particular radiation is located, the first color layer absorbs more strongly than the second color layer. Preferably, infrared radiation is used as the specific radiation, and the second color layer is transparent in this area. A particularly preferred spectral range of the infrared radiation is the spectral range between 1000 nm and 1100 nm. The term ink used here stands out for the printing effect achieved by the watermark-masked and radiation-based modification. Of course, the ink itself can also include structures that go beyond conventional printing systems, such as a foil coating or metallization.

Items to be protected within the scope of this description may include, for example, security papers, identity and value documents (such as banknotes, passports, identity cards, shares, bonds, certificates, vouchers, checks, tickets, etc.) as well as product security elements such as security items. Labels, seals, packaging, where a watermark is possible.

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 banknote) 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, as used for example 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. Further preferably, the substrate consists of a combination nation 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 substrate of paper 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 known for example from DE 102009056462 AI.

Under translucency or translucent in this description, the partial translucency of a body is understood, so the property of transmitting light scattering. Translucency is among others in contrast to the transparency (= image or view permeability) to see. 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:

Fig. La and lb is a schematic representation of a substrate in a sectional view

(FIG. 1 a) or in plan view (FIG. 1 b) for illustrating the opacity modulation by the watermark, FIG.

, 2a and 2b show schematic representations of the substrate of FIG. 1 for producing a watermarked printed image, FIG.

3a and 3b show a schematic view similar to FIGS. 1a and 1b, relating to an embodiment in which the watermark is generated by a watermark color,

FIG. 4 is a view similar to FIG. 2 for the substrate of FIGS. 3a and 3b; FIG.

5a shows a schematic illustration similar to FIG. 2 for an exemplary embodiment in which a non-modifiable coating is provided on the front side of the substrate,

5b and 5c views of the substrate of Fig. 5a from the back or

the front after a modification,

Fig. 6 views of nine images showing the security element of

Fig. 1 to 2 during manufacture and in different viewing conditions shows, and Fig. 7 to 9 representations similar to Fig. 6 for various modifications and developments of the security element.

Fig. La shows in a sectional view of a security element 1, wherein for simplicity, only a substrate 2 is drawn. The substrate 2 has a front side 3 (which is arranged at the bottom in the figures without further restriction) and a rear side 4. In the substrate 2, a watermark 5 is incorporated, which modulates the thickness of the substrate 2 and thus its opacity. This opacity modulation is shown in Fig. Lb, which shows a view from the front side 3 of the substrate 2 schematically. There are regions 6 of high opacity at locations where the substrate 2 has the maximum (unreduced) thickness. In regions 7 where the thickness is reduced by an average amount, the substrate 2 has a medium opacity. In a region 8 in which the thickness is greatly reduced, the substrate 2 has a low opacity or a high translucency.

To produce a printed image that has been adapted to the watermark, an ink layer 9 is applied to the front side 3, whose ink-repellent colorant can be ablated by means of laser radiation or modified with respect to a color effect. Under the ink layer 9 is a fluorescent ink layer 22 containing a luminescent colorant. 2a and 2b show the substrate 2 with the ink layer 9 and the fluorescent ink layer 22 applied on the front side 3. They are not (yet) structured further in this state, but at least partially cover the region in which the watermark 5 is in the substrate 2 is present. 2b, the ink layer and the fluorescent ink layer are combined in a common color layer 64, which contains both the remittant and the luminescent colorant. From the front side 3, a laser beam 10 is now passed over the substrate. It radiates through the substrate 2. The wavelength of the laser beam is such that the remitting colorant is absorbed by the radiation and modified or ablated. The laser beam 10 is attenuated depending on the opacity of the substrate 2, which is modulated by the watermark 5. At a position 10a where the substrate has high opacity by the watermark, the laser beam 10 is greatly attenuated. At a position 10b where the substrate has the least opacity, the laser beam is least attenuated. In FIGS. 2 a and b, this is illustrated schematically by the thickness of the laser beam 10. In fact, of course, only the intensity of the laser beam 10, but not its radiation cross section when passing through the substrate 2 is attenuated.

The intensity of the laser beam 10 is adjusted so that the watermark as an intensity mask modulates the effect on the remitting

Colorant z. For example, the ink layer 9 causes the laser beam 10 to have the ink layer 9 or ink layer 64 applied to the front side 3: in the region 8 having low opacity, the remittant colorant is ablated or modified to a maximum extent in areas 7 having medium opacity , and in areas 6 with maximum opacity, the least or possibly even no ablation / modification occurs. Of course, this applies only insofar as the ink layer 9 / the color layer 64 on the front side 3 covers the region in which the watermark 5 is formed in the substrate 2. The fluorescent colorant is not ablated / modified by the laser beam 10, z. B. transparent to the laser beam 10.

The described embodiment can be modified such that, instead of a watermark, which has the opacity variation of the substrate, a so-called "fake" or printed watermark occurs, ie a watermark that has been generated on the substrate 2 by a so-called watermark color., Figures 3a and 3b show schematically the provision of such a printed watermark 4 of the substrate 2, a watermark color 11 is printed in. The watermark color 11 penetrates into the substrate 2 according to FIG. 3b and causes, after drying or other suitable processing, a translucency elevation 12 in the substrate 2 at the locations where the watermark color 11 was printed.

If, as shown in FIG. 4, which shows two color layers 9 and 22 purely by way of example, but can also be realized with a common color layer 64, the substrate 2 with the printed watermark 12 with the laser beam 10 results again Effect that the laser beam 10 at positions 10a, where the watermark or the watermark color increases the translucency of the substrate 2, less attenuated in intensity than at positions 10b, where the watermark does not have this effect. Again, ablation / modification of the remittant colorant in the exact register to the watermark is obtained without the registration of the ink layer 9, color layer 64, of this register.

5a to 5c relate to a third embodiment, in addition to the front side 3 a not by the laser radiation 10 modifizier bare coating 13 has been applied, which is transparent to the laser radiation 10 and thus does not attenuate them. Again, a system with two layers 3 and 22 is shown purely by way of example. A common color layer 64 is equally possible. FIG. 5a shows a sectional view similar to FIG. 2, wherein the coating 13 that is not modifiable by the laser radiation but is nevertheless absorbing is now applied in some areas. FIG. 5 b shows a plan view of the rear side 4 with the coating 13.

5c shows a top view of the front side 3 after irradiation with the laser radiation 10. Due to the different opacity of the substrate 2 in the region of the watermark, the ink layer 9 is influenced to a different extent by the laser radiation 10, so that the different regions 14 , 15 and 16 result. In the region 16, the ink layer 9 is almost unaffected, since the energy of the laser beam is greatly attenuated due to the opacity of the substrate 2. In region 14, the ink layer 9 is modified, for example ablated, due to an average laser energy attenuation by the substrate due to the average opacity of the substrate 2. The laser beam had a strong effect on the ink layer 9 in the region 15, because there the substrate 2 has a low opacity and only slightly weakened the laser beam. The variant of FIG. 5 can also be configured so that the coating 13 does not absorb the laser radiation, but is a luminescent ink layer, which on the back of the substrate in transmitted light results in additive color mixing with the luminescent colorant, as described on the front side was exposed differently by means of laser radiation.

Of course, the described embodiments can also be realized with a watermark that was generated by a watermark color and not by a thickness modulation. Of course, it is basically possible for all embodiments to use a combination of watermark color and thickness modulation. A watermark ink is available, for example, from Sun Chemical under the designation 669440 Vernes UVSP (art.No .: JV 40000009).

Of course, the approaches described here can also be carried out on both sides of a substrate, wherein the color layers are then applied alternately on front and back of the substrate, so that they do not overlap.

In addition, two different ink layers can be used, which can be modified by radiation of different spectral ranges. This makes it possible to work with different intensity profiles for these two radiations or to print on the front and back the same area with radiation-modified ink layers in the register to the watermark. For this purpose, a first ink layer is applied to the front and a second ink layer on the back. Subsequently, these ink layers are exposed and modified by laser radiation from the back side (for the ink layer located on the front side) or the back side (for the ink layer located on the front side).

Three examples are described below for the ink layers: Example V.

A black, soot-based offset ink was printed over the area of a watermark after a fluorescent ink layer had been printed. The paint was dried for several days and then From the back of the ND vanadate laser ablate the paint on the front. In areas of low paper thickness, ie maximum translucent watermark, 80% to 95% of the color was thereby removed. In areas of maximum paper thickness, ie minimal translucency of the watermark, only 10% to 30% of the color was ablated.

Example 2:

The area of a watermark on the front side was overprinted by means of an OVI screen printing ink WP from the manufacturer SICPA. The paint dried out for several days. Subsequently, the color on the front side was ablated by means of a Nd.Yag laser from the rear side. In areas of low paper thickness, 80% to 95% of the paint was removed. In areas of maximum paper thickness, 10% to 30% of the paint was ablated.

Example 3:

Using a magnetic OVMI screen-printing ink from manufacturer SICPA, the area of a watermark on the front side was overprinted after a fluorescent ink layer had been printed. The paint dried out for several days. Subsequently, the color on the front side was ablated by means of a Nd: Yag laser from the rear side. In areas of low paper thickness, 80% to 95% of the color except a yellow colorant was removed. In areas of maximum paper thickness, 10% to 30% of the paint was ablated. Figures 6 to 9 show various images of the security element during different stages of manufacture. The upper lines of the figure show the view of the security element before applying the color layers 9 and 22. The middle lines show the views after applying the color layers 9 and 22, but before the modification by the radiation. Finally, the bottom lines show the completed security element. The left columns show the views that result from normal top view of the security element. The middle columns show the respective see-through image and the right columns show the luminescence image after excitation with UV radiation.

The hatching used in FIGS. 6 to 9 are assigned to the individual views / functions. A vertical bar is used for the brightness of the background of the respective images, with increasing baring indicating a decreasing brightness. A vertical hatch denotes the brightness of elements in the see-through image. A crosshatch designates the brightness of elements in the supervisory image. A vertical hatch denotes the brightness of structures in the luminescence image. The hatching or hatching distance symbolizes the brightness. A wider-meshed hatching or stroke therefore illustrates a lighter structural element, a closer meshing or brightness a darker element.

Stronger hatched sections are therefore darker in the respective view than less densely hatched sections. Outlines of corresponding elements are entered in all pictures. This was done solely for better recognizability of the images. In fact, there are no separate outline boundaries in the images. Dashed lines illustrate an area over which the particular radiation is applied. They are not visible in the views, but only entered to clarify the application of the laser radiation. To simplify the illustration, only one black-and-white representation is used in the exemplary embodiments

Fig. 6 shows a first embodiment for the manufacturing method of a security element with Passer between printing element and watermark. Figure 23 shows the security element before applying the pressure element in supervision. Not surprisingly, a white surface 32 can be seen. Figure 24 shows the same manufacturing status in review. In front of a gray area 33, the watermark, which is formed by a horizontal bright rectangle 37 and a darker rectangle 36 in contrast, stands out. Both rectangles 37 are lighter than the gray area 33. Finally, FIG. 25 shows the fluorescence image which is a black area 34 due to fluorescence colorant not yet present in this production status. It is assumed here that the substrate of the security element does not fluoresce.

FIGS. 26 to 28 again show in plan view (FIG. 26), review (FIG. 27) and fluorescence view (FIG. 28) the state of the security element after application of a printed image 38. The printing element has a metallic silver pigment which is a remittant colorant. Next has the printing element has a fluorescent ink layer 22 which has a luminescent colorant and is constructed below an overlying ink layer containing the remitter colorant. The colorants may alternatively (not shown) also lie in a common color layer.

In image 26, the printed image 38 is highlighted in black in front of the white surface 32. In addition, in the image 26, an irradiated area 60 is still marked by a dashed line. This is the area where laser radiation will subsequently be applied. In FIG. 27, the watermark, consisting of the standing rectangle 36 and the lying rectangle 37, in front of the gray area 33, covered by a black ellipse 49, which is formed by the printed image 38, is shown looking through this production stage. In the fluorescence view, the image 28 against a black background by the black surface 34, a darkened fluorescence image 39, which is due to the fact that the underlying fluorescent ink layer 22 is covered by the overlying ink layer 9 and only to a very small extent fluorescence radiation to the Surface penetrates. FIGS. 29 to 31 show top view, transparent and fluorescence images after application of the laser radiation in the irradiated region 60, wherein the watermark is used as an intensity mask, as explained above with reference to FIGS. 1 to 5. For the ablation / modification of the printed image 38, the watermark, consisting of the rectangles 36 and 37, acts as an intensity mask. As a result, a maximum radiation intensity reaches the printed image 38 in the area of the horizontal rectangle 37 and a minimum intensity in the region of the background. In the area of the standing rectangle 36, the printed image 38 with a mean intensity, which lies between the two extreme values applied. As a result, the printed image 48 is structured into three regions which lie in the perfect register with the watermark 5. An unchanged section 42 lies in those areas of the printed image 38 which do not cover the watermark, that is to say are illuminated by the radiation with the minimum intensity. A gray portion 40 lies in the areas of the printed image 38, which cover the standing rectangle 36. A bright section 41 is finally formed by those areas of the printed image 38 which cover the horizontal rectangle 37. This breakdown and patterning of the print image 38 is shown in FIG. 27, which is the

Top view of the finished structured security element shows, clearly recognizable.

In the transparent image 30, the structured printing element 38 has an effect in superposition with the intensity modulation by the watermark, namely the rectangles 36 and 37. The unchanged section 42 of the plan image leads to a black area 45 in the see-through image, since there the translucency of the security element is still completely reduced by the unchanged layer structure of the print image 38. In a bright area 44, which corresponds to the bright portion 41, a brightness of the see-through image is established, which is reduced in relation to that of the horizontal rectangle 37. This reduction is caused by the small residual thickness of the visible layer absorbing layer structure of the printed image 38. A dark area 43 is formed corresponding to the gray portion 40. Here the translucency is reduced compared to that of the standing rectangle 36, but not as strong as in the black area 45.

In the ablation of the print image 38, as described above, only the remittant colorant, but not the luminescent colorant, is removed, removed, reduced or modified. Thus results in fluorescence image 31 a darkened region 48 whose fluorescence intensity corresponds to the darkened fluorescence image 39. In accordance with the effect on the remitting colorant, a bright region 46 and a dark region 47 are further obtained which correspond in position and location to the gray section 40 / dark section 43 or bright section 41 / bright section 44, respectively.

FIG. 7 shows a development of the manufacturing method in a view similar to FIG. 6. Identical elements are provided with the same reference numerals. The essential difference from the embodiment of FIG. 6 is that the irradiated region 60 has a recess 61 in which the particular radiation is not applied. This is indicated by dashed lines in Figure 26. The recess 61 causes a further unaltered section 50 corresponding to the contours of the recess 61 to be formed in the supervision image 29. Also in Durchsichtsbild 30 you get on this

Make another black area 51 of the same dimensions. In fluorescence image 31, another darkened region 52 results, also with the same dimensions and outlines. In this way it is possible to provide a first additional pattern in the security element.

FIG. 8 shows a further modification, wherein in the irradiated area 60, in the example diamond-shaped spot 62, irradiation is now effected with additional radiation which is designed such that it also removes the fluorescent color 22. As a result, in the supervisory image 29, a diamond-shaped surface 53 is obtained in which no printed image 38 is present. In the illustration of FIG. 8, this is illustrated by the fact that the diamond-shaped surface 53 is provided with the inking of the background white surface 32, usually a banknote paper. The rhombic surface 53 may, however, due to the original printing in their gloss of the In the transparency 30, the diamond-shaped area is divided into two triangular parts 54, 55, since the spot 62 is the two rectangles 36, 37 , which have different transmissions, covered. The two triangular parts 54 and 55 each have in the see-through image the brightness of the standing behind standing rectangle 36 or 37. This is determined by the location of the spot 62. Another location of the spot 62 results in a different or no division in the see-through image.

Finally, a rhombic surface 56 is also shown in the fluorescence image where the fluorescent dye layer 22 has been removed. In this diamond-shaped surface, the fluorescence intensity of the background, ie a black surface, is present.

FIG. 9 shows a further embodiment, which as a result comes very close to that of FIG. Here, not a spot 62 is irradiated with additional laser radiation, but it is provided during application of the print image 38, a pressure recess 63. The same conditions arise with respect to the see-through image 30 and the fluorescence image 31. The supervisory image 29 also shows a representation which, when viewed vertically, essentially corresponds to that of the supervisory image of FIG. 8. However, since no printed image 38 was present in the diamond-shaped surface 56 from the outset, the gloss level, ie the impression on oblique viewing in the diamond-shaped surface 59, is no different than in the background, ie in the white area 32. Of course, the developments according to FIGS. 7 to 9 can be combined as desired. It is thus possible to combine the recess 61 of the irradiated area 60 with the additional irradiation of the spot 62. A combination with the pressure recess 63 is possible. Likewise, using a separately irradiated spot 62 may be combined with the pressure recess 63. Of course, all three measures, ie the use of a recess 61 in the irradiated area 60, a separately irradiated spot 62 and a pressure recess 63, are combined.

The exemplary embodiments presented above provide a two-level watermark with the rectangles 36, 37. This was chosen because of the clarity of the description. Of course, a single-level watermark and a multi-level or even an opacity continuously varying watermark can be used. The described principles apply equally.

In the described embodiments, simple geometric figures for the structures used were shown. Of course, this is purely exemplary. It is also possible to use complex geometric figures or image representations. Of course, this also applies to the further developments according to FIGS. 7 to 9. Here motifs or alphanumeric representations, in particular banknote values, currency information or information about the publisher of a banknote or a security element can be correspondingly coded.

In particular, the invention can also be realized by the following embodiment: The print motif is applied with at least one printing ink which has at least the following substances: Laser markable (IRA), preferably metallic pigments and UV-transparent pigments which are visibly luminescent under UV radiation (preferably in the range 1000 nm to 1100 nm) , IR transparent pigments and / or colorants may also be included, among others. In this case, the luminescence of excitable under UV radiation pigments by the z. B. weakened metallic pigments. The print motif is at least partially printed over the watermark, preferably on the substrate screen side (rougher than the felt side). The print motif can consist of a closed surface and / or additional ornaments and / or be screened. There is a laser marking from the opposite side of the substrate - through the substrate, whereby the laser beam is attenuated accordingly due to the modulated paper thickness or opacity in the darker areas of the watermark. The laser should be adjusted so that the full thickness of the paper (outside the watermark area) will not cause any marking or ablation. At the same time, it must be ensured that the contrast in the sub-region modulated by the laser through the opposite substrate side over the watermark is to be kept as high as possible.

The area to be marked with the laser must be selected so that the tolerances between printing and laser marking are maintained. The size of the surface results from the desired machine speed, but may not be less than 1.5 cm ² in the rule. Decisive for the effect is the laser operating mode. In order to achieve a modulated ablation of IRA, preferably metallic pigments, pulse operation should be selected. In continuous wave operation, the entire pigment is destroyed in the present opinion, whereas in pulsed operation, only the optical properties of a metallic pigment due to non-linear effects are changed, for example, bonds are broken, so that the color effect emanating from the unmodified metallic pigment, changed is or fails. The following laser parameters are possible: 10 W maximum power in continuous wave mode, 30 kHz to 50 kHz pulse frequency, 5 ns to 50 ns, preferably 8 ns to 15 ns pulse length, 0.2 mm to 0.8 mm spot diameter (depending on the area to be exposed or Machine speed), 100 W maximum total energy (typically 50 W for silver pigments).

The modulated ablation IRA, preferably of metallic pigments in pulse mode, simultaneously "exposes" the pigments which are luminescent under UV radiation, thereby producing a modulated luminescent motif which is perceptible under UV light, resulting in the subregion of the watermark under UV being marked by the laser Radiation as a modulated motif becomes visible, whereby the unmarked areas also luminesce weakly and complement the motif, but at the same time this motif is also recognizable under visual light as a modulated motif which preferably has a metallic effect Fitted with the watermark added.

For the development of FIG. 7, the following may apply: In the area to be marked in pulse mode (main motif), a preferably alphanumeric motif is left out negatively (first motif, not marked). As a result, in this region (first motif), the luminescence power of the pigments which can be excited under UV radiation continues to be weakened by the non-ablated metallic pigments and thus the first motif remains recognizable under UV light. At the same time, this first motif is also recognizable under visual light as an alphanumeric motif, which has the full metallic effect. This first motif becomes visible through the comparatively higher opacity - appears darker than its surroundings.

For the development of FIG. 8, the following may apply:

In the area to be marked in the pulse mode (main motif), a preferably alphanumeric motif is marked in cw mode (second motif, cw laser marking). As a result, not only the metallic pigments but also the pigments luminescent under UV radiation are ablated in this region (second motif), so that the second motif is recognizable under UV light as a black or dark motif (non-luminous) , Under visual light in the supervision, the second motif remains invisible. In the tilted state, on the other hand, the second motif can be recognized as a latent motif (no color difference, only gloss difference). This second motif is not visible in the review, since the opacity of the color (lasered in pulse mode compared to the cw mode) has not changed.

In general, the particular radiation is to be chosen so that the substrate as little or no absorption of the radiation occurs, which would lead to a change in the substrate. Both continuous wave lasers and pulsed lasers are possible for this purpose. An example of a suitable The continuous wave laser is the model Innoslab, IS8I-E of the manufacturer Edge- Wave GmbH, which is a Nd: YVO4-based laser at a wavelength of 1,064 nm. It provides a power of 100 watts in continuous wave mode. At a scan speed of 2.5 m / s to 5 m / s, the ablation of a soot-based color can be performed.

If an IR-modifiable color is used as the ink layer, there is the advantage that machine-based checking of the printer from the modified printed image and watermark by means of infrared measurement and ultrasound measurement is possible. The same applies to the use of a luminescent in the UV range colorant. By means of combined luminescence and ultrasound measurement, the registration accuracy and thus the authenticity can be verified. Transmitted light in the sense of this invention is when the substrate is illuminated from the side opposite to the viewer, i. the illumination through the substrate takes place. Incident light is in the sense of this invention, when a lighting of the substrate from the side of the viewer is made.

The watermark may be a multi-level modulated 3D, a two-level highlight, or a high resolution pixel watermark that modulates the opacity of the substrate by thickness variation. A combination of the different types of watermarks is also possible, especially if the main watermark motif is a portrait that can not be overprinted. Reference symbol

security element

substratum

front

back

watermark

, 7.8 area

Ink layer

0 laser beam

0a, 10b position

1 watermark color

2 Translucency increase

3 coating

4, 15, 16 area

7 window thread

8, 19 area

0, 21 section

2 fluorescent color layer

3-31 picture

2 white area

3 gray area

4 black area

5 watermarks

6 standing rectangle

7 lying rectangle

8 print image darkened fluorescence image gray section bright section, 50 unaltered section

dark area bright area

, 51 black area

bright region

dark region

, 52 darkened region

black ellipse, 56, 59 diamond-shaped surface

, 55, 57, 58 Triangular section

irradiated area

recess

spot

pressure recess

coat of paint

Claims

Patent claims

1. A method for producing a security element (1), wherein

a substrate (2) is provided which has a front side and a rear side (3, 4), is translucent at least for certain radiation (10) and has a watermark (5) which modulates the opacity of the substrate (2) .

on the front side (3) a printing element (9) is applied, which at least partially covers the watermark (5) and which contains at least a first and a second colorant, wherein the first

Colorant by means of the first specific radiation (10) ablatierbar and the second is not, and

the substrate (2) is irradiated by the particular radiation (10) from the rear side (4) and the first colorant is ablated from the specific radiation (10), the watermark (5) being used as a mask for

Intensity attenuation of the particular radiation is used to modify the pressure element (9) in the register to the watermark (5),

characterized in that

the first colorant is a colorant remitting colorant and is disposed in a first color layer (9) and the second colorant is a luminescent colorant and is disposed in a second color layer (22),

the first color layer (9) covers the second (22) and

- The second colorant is exposed at locations (46) by the first

Colorant is changed using the watermark (5) as a mask of the first specific radiation (10) with respect to the color effect or removed from the first color layer (9).

2. A method for producing a security element (1), wherein a substrate (2) is provided, which has a front and a back (3, 4), at least for certain radiation (10) is translucent and has a watermark (5) which modulates the opacity of the substrate (2),

on the front side (3) a printing element (9) is applied, which at least partially covers the watermark (5) and which contains at least a first and a second colorant, wherein the first colorant is ablatable by means of the first specific radiation (10) and the second not, and

the substrate (2) is irradiated from the backside (4) with the particular radiation (10) and the first colorant is ablated from the particular radiation (10), the watermark (5) being used as a mask to attenuate the intensity of the particular radiation to modify the pressure element (9) in the register to the watermark (5),

characterized in that

the first colorant is a colorant remitting colorant and the second colorant is a luminescent colorant,

the first colorant and the second colorant are disposed in a common color layer (64) and

the second colorant is exposed at locations (46) by changing the first colorant using the watermark (5) as a mask from the first particular radiation (10) with respect to its color effect or removing it from the color layer.

3. The method according to claim 1 or 2, characterized in that the first specific radiation (10) is structured or modulated such that a first additional pattern (50) is left out, in which the first colorant is not changed or removed.

4. The method according to any one of claims 1 to 3, characterized marked, that the second colorant by means of another radiation ablatierbar or changeable in terms of its color effect and the second colorant at portions of the exposed locations by irradiation of the further radiation (22) according to a second additional pattern ablated / changed.

5. The method according to claim 4, characterized in that the specific radiation (10) is pulsed laser radiation and the further radiation is cw laser radiation, preferably the same laser.

6. The method according to any one of the above claims, characterized in that the pressure element (9) is applied so that it over the

Watermark (5) has a recess (56) according to a third additional pattern.

7. The method according to any one of the above claims, characterized marked, that the remittierende colorant metallic pigments, effect color pigments or color-shift pigments.

8. The method according to any one of the above claims, characterized in that the luminescent second colorant comprises pigments which are transparent in the IR spectral range, preferably in the spectral range from 1000 nm to 1100 nm.

9. The method according to any one of the above claims, characterized in that the first colorant is removed by ablating it.

10. The method according to any one of claims 1 to 9, characterized in that the pressure element comprises a coating, transfer film, laminating film and / or a window thread.