EP3486092B1 - Method for production of a security element - Google Patents

Description

The invention relates to a method for producing a strip-shaped security element for documents of value such as bank notes, identity cards or the like, the security element consisting of a polymeric carrier layer with a front side and a rear side. Such a strip-shaped security element is, for example, a security thread which is at least partially introduced into the substrate of a value document, or a security strip which is applied to the surface of a value document.

This is for example from the DE 10 2016 009 440 A1 a method for producing a security element is known in which a substrate which is translucent for laser radiation has a watermark which modulates the opacity of the substrate. An embossed layer which at least partially covers the watermark is applied to one side of the substrate. A hologram structure is embossed into the embossing layer and a reflector layer is applied to it. The substrate is irradiated with the laser radiation from the opposite side, the intensity of the radiation being set so that the watermark acts as a mask by means of the opacity modulation it causes, so that the reflector layer is ablated in a structured manner by the radiation in the register with the watermark.

That from the DE 10 2016 009 440 A1 however, known methods require a substrate with a watermark and are not applicable to a substrate without a watermark.

Out WO 2009/109343 A2 is a metal transfer process for the production of a foil element with metallic layers registered to one another and a film element that can be produced by means of such a method is known. A first metallic layer provided on a first surface of a flexible, single-layer or multilayer carrier film and a masking layer provided on the second surface of the carrier film opposite the first surface are structured in register with one another by means of synchronized, structuring processes. After the first metallic layer and the masking layer have been structured, one or more additional layers are applied to the first metallic layer. A second metallic layer, to which a first photoactivatable layer is applied, is applied to the one or more further layers. The first photoactivatable layer is structured by means of exposure through the masking layer, the first metallic layer, the one or more further layers and the second metallic layer on the part of the masking layer by means of electromagnetic radiation of a wavelength to which the first photoactivatable layer is sensitive, or the first The photoactivatable layer is exposed, controlled by the masking layer, from the side of the film body opposite the masking layer.

The invention is therefore based on the object of developing a method for producing a security element in such a way that the disadvantages of the prior art are eliminated and the number of method steps and the complexity of the production method are reduced overall.

This object is achieved by the features of independent claim 1. Developments of the invention are the subject of the dependent claims.

1. a. Aufbringen einer Prägelackschicht auf die Vorderseite der polymeren Trägerschicht,
2. b. Einbringen einer Prägestruktur in die Prägelackschicht,
3. c. Aufbringen einer opaken metallischen Schicht auf die Oberseite der Prägestruktur, wobei die metallische Schicht die Oberseite der Prägestruktur mindestens teilweise abdeckt,
4. d. Aufbringen einer Waschfarbe auf die Oberseite der metallischen Schicht, wobei sich die Waschfarbe und die metallische Schicht mindestens teilweise überlappen und wobei der Umriss der Waschfarbe eine für einen Betrachter erkennbare Information bildet,
5. e. Entfernen oder Transparentisieren der metallischen Schicht von der Oberseite der Prägestruktur mittels eines Laserstrahls, wobei die metallische Schicht an den Stellen, an denen sie mit der Waschfarbe überlappt, nicht entfernt oder transparentisiert wird,
6. f. Abwaschen der Waschfarbe von der Oberfläche der metallischen Schicht mit einer Waschflüssigkeit.

According to the invention, the manufacturing method has the following steps:

1. a. Applying an embossing lacquer layer to the front of the polymeric carrier layer,
2. b. Introducing an embossed structure into the embossing lacquer layer,
3. c. Applying an opaque metallic layer to the top of the embossed structure, the metallic layer at least partially covering the top of the embossed structure,
4. d. Applying a wash color to the top of the metallic layer, the wash color and the metallic layer at least partially overlapping and the outline of the wash color forming information that can be recognized by a viewer,
5. e. Removal or transparency of the metallic layer from the top of the embossed structure by means of a laser beam, the metallic layer not being removed or made transparent at the points where it overlaps with the wash color,
6. f. washing off the washing color from the surface of the metallic layer with a washing liquid.

A wash color is a laser-resistive color, i.e. a color that is impermeable to laser radiation and almost unaffected, which can be removed again by a subsequent washing process. Such a wash color is off, for example EP 1023499 B1 , EP 1609619 B1 or

EP 1972462 B1 known. Applications of this washing color are for example off EP 1 747 905 A2 , DE 10 2008 008 685 A1 or DE 10 2015 007 233 A1 known. In the prior art, however, the washing ink is arranged below a metallic coating, so that during a washing process the part of the metallic coating that is located directly above the washing ink is washed off and an opening is created within the metallic coating, the so-called clear text.

According to the invention, the clear text is created by removing or transparentizing the metallic layer by means of a laser beam, the metallic layer not being removed or made transparent at the points where it is covered with the washing ink that is impermeable to laser radiation. The wash color thus serves as a mask for the laser radiation and shields it in the entire area of the layer sequence which are arranged in the "core shadow" below the wash color. In these areas, the security element remains opaque; in the surrounding areas next to the wash color, the security element becomes translucent or transparent.

In a final process step, the washing color is completely removed again with a washing liquid, for example water, preferably with the aid of a rotating roller coated with felt.

The method according to the invention has the particular advantage that there are no adhesion problems on a substrate of a document of value due to remaining toning. The stated toning and the resulting adhesion problems are caused by the fact that gravure printing is used in the methods known from the prior art. In gravure printing, however, a toning film is always created, as the squeegee is never 100% able to remove the ink in areas of the gravure cylinder that are not to be printed. This thin toning film is now an additional layer, which can lead to weaknesses in the layer structure or in the adhesion to a substrate.

• als polymere Trägerschicht eine beidseitig druckvorbehandelte Folie z.B. M816 von Dupont Teijin Films. Bei der Vorbehandlung handelt es sich um eine chemische Acrylatschicht. Alternativ kann auch eine Folie beidseitig mit einem geeigneten Primer versehen werden, welcher eine gute Haftung für den UV-Lack herstellt.

• als Prägelackschicht einen UV-Lack: UVR010 bzw. UVR012 oder ähnliche Acrylate, welche durch UV-Strahlung und mit Hilfe eine Photoinitiators polymerisiert werden.
• als metallische Schicht eine mit PVD- oder CVD-Verfahren aufgedampftem Schicht Metallen, beispielsweise Aluminium, und Interenzaufbauten wie Color-Shift und Color-Change.
• als Waschfarbe beispielsweise WAF025 bzw. WAF035. Hier handelt es sich um Farben, die sich sehr leicht in Wasser lösen, beispielsweise Polyvinypyrrolidon oder Hydroxypropylcellulose. Alternativ kann neben einer Wasserlöslichkeit auch eine erhöhte Löslichkeit gegenüber einem anderen Lösungsmittel gegeben sein, mit welchem die Schicht dann entfernt werden kann, wie beispielsweise Aceton.

Another advantage of the method according to the invention is that there are fewer operations than with one, for example WO 2009/109343 A2 Has known metal transfer process and that no or fewer insetter operations than in the metal transfer process are required. The following materials can be used as examples:

• a film pretreated on both sides, for example M816 from Dupont Teijin Films, is used as the polymeric carrier layer. The pretreatment is a chemical acrylate layer. Alternatively, a film can be provided with a suitable primer on both sides, which creates good adhesion for the UV varnish.

• a UV lacquer as an embossing lacquer layer: UVR010 or UVR012 or similar acrylates, which are polymerised by UV radiation and with the help of a photoinitiator.
• as the metallic layer, a layer of metals, for example aluminum, vapor-deposited using a PVD or CVD process, and interference structures such as color shift and color change.
• as a wash color, for example WAF025 or WAF035. These are colors that dissolve very easily in water, for example polyvinypyrrolidone or hydroxypropyl cellulose. Alternatively, in addition to water solubility, there can also be increased solubility compared to another solvent with which the layer can then be removed, such as acetone for example.

The layer thickness of the embossing lacquer layer is preferably 0.5 μm to 20 μm and particularly preferably 2 μm to 5 μm in each case per layer of embossing lacquer.

The layer thickness of the metallic layer, for example the aluminum layer, is preferably 5 nm to 200 nm or the metallic layer has an optical density of 0.1 oD (optical density) to 5 oD WO 2005/108110 A1 known colorshift coating is used, the visible thicknesses are greater.

The layer thickness of the washing color is preferably 0.5 μm to 15 μm.

According to a preferred embodiment it is provided that between steps c and d at least one further layer sequence comprising an embossed lacquer layer and an opaque metallic layer is applied. This results in an alternating layer sequence consisting of several embossing lacquer layers and opaque metallic layers, with washing ink being applied only to the uppermost metallic layer. The wash color serves as a laser mask for all layers underneath.

In addition, it is particularly useful if steps a to c and e are also carried out on the rear side of the polymeric carrier layer. In this case, not only is an embossing lacquer layer and an opaque metallic layer or such a layer sequence applied to the front side of the polymeric carrier layer, but also to the rear side of the polymeric carrier layer. In this case, too, the wash color is only applied to the top metallic layer on the front side and serves as a laser mask for all the layers below and the layers on the rear side of the polymeric carrier layer. An exact registration of the demetallization of the two metal layers on the front and back is particularly advantageous.

According to a further embodiment, a washing color is also applied to the top of the outermost metallic layer, which is located on the back of the polymeric carrier layer. The wash color is applied to the back of the polymeric carrier layer in exact register with the wash color on the front of the polymeric carrier layer. After the metallic layer has been removed or made transparent from the top of the embossed structure by means of a laser beam, this wash color is also washed off again from the surface of the metallic layer. A particular advantage here is that the security element can be exposed to a laser beam from both sides and is located in both Cases the same opening within the metallic layer or the same graphic illustration results. The orientation of the security element when it is fed into a laser system, that is to say whether it is fed into the laser system with its front or back, is irrelevant.

Translucency in the context of this invention means that an object, such as the substrate or the plastic film, allows a certain amount of light to pass through. If light strikes one side of the object, a certain proportion of the light is let through to the other side of the object and exits there again. The greater the percentage of light passing through in relation to the incident light, the more translucent the object. If the percentage is at least 90%, i.e. if the object allows the incident light to pass through almost unimpaired like a window, the object is referred to as transparent. On the other hand, an object that allows less than 10% and preferably around 0% of the incident light to pass through, i.e. in which the proportion of the light passing through is low, close to or equal to zero in relation to the incident light, is referred to as opaque or not translucent.

See-through is present when the substrate is illuminated from one side and viewed from the other side. There is a top view when the lighting and viewing take place from the same side of the substrate.

Documents of value into which such a security element can be inserted or applied are in particular banknotes, shares, bonds, certificates, vouchers, checks, high-quality admission tickets, but also other papers at risk of forgery, such as passports and other identification documents, as well as cards, such as credit or debit cards, the card body of which has at least one layer of security paper, and also product security elements such as labels, seals, packaging, folding boxes, package inserts and the like.

The simplified designation of value document includes all of the above materials, documents and product security means.

In the context of this invention, the positional accuracy of printed images or other elements with respect to one another on the front and / or back of a substrate is referred to as register. For example, in the case of parts of printed images which, when viewed through, complement one another to form an overall printed image, even slight deviations of less than 0.1 mm between the respective printed images significantly disturb the visual impression when viewed through. DIN 16500-2: 1987-01 defines register as the accuracy in printing technology with which the intended reproduction quality of the details to be reproduced is achieved or maintained.

The terms “front side” or “back side” of the substrate or value document are relative terms which can also be referred to as “one” and “the opposite” side and which form the major part of the total surface of the substrate or value document. These terms expressly do not include the side surfaces of a substrate or document of value which, with a thickness of a substrate or document of value that is only about one millimeter for card bodies or only fractions of a millimeter for banknotes, are negligible and usually not provided with security elements or coatings will or can become. In particular, no see-through effects can be achieved with the side surfaces.

Information within the meaning of this invention is a visually perceptible representation designed in the form of a pattern. This can, for example, form an alphanumeric string of digits and / or letters, a graphic image, an image, a text or other characters. The information particularly preferably consists of positive and / or negative motifs. In the case of a positive motif, a motif element itself is applied to the substrate, whereas in the case of a negative motif, the area surrounding the motif element is applied to the substrate. A positive motif is, for example, a letter printed in dark color on the light substrate. A negative motif is, for example, an area applied in dark color to the light-colored substrate, which has an unprinted area in the form of a letter within the area.

It goes without saying 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 without departing from the scope of the present invention, insofar as this is covered by the scope of protection of the claims.

The advantages of the invention are explained on the basis of the following exemplary embodiments and the supplementary figures. The exemplary embodiments represent preferred embodiments to which, however, the invention is not intended to be restricted in any way. Furthermore, the representations in the figures are highly schematic for better understanding and do not reflect the real conditions. In particular, the proportions shown in the figures do not correspond to the conditions present in reality and serve exclusively to improve the clarity. Furthermore, the embodiments described in the following exemplary embodiments are reduced to the essential core information for better understanding. In the practical implementation Much more complex patterns or images can be used.

Fig. 1

in Seitenansicht eine erste Ausführungsform eines erfindungsgemäßen Sicherheitselements vor Beaufschlagung mit Laserstrahlung,

Fig. 2

in Seitenansicht das erfindungsgemäße Sicherheitselement aus Fig. 1 nach Beaufschlagung mit Laserstrahlung und Abwaschen der Waschfarbe,

Fig. 3

in Seitenansicht eine zweite Ausführungsform eines erfindungsgemäßen Sicherheitselements vor Beaufschlagung mit Laserstrahlung.

In detail show schematically:

Fig. 1

a side view of a first embodiment of a security element according to the invention before exposure to laser radiation,

Fig. 2

the security element according to the invention in side view Fig. 1 after exposure to laser radiation and washing off the washing color,

Fig. 3

a side view of a second embodiment of a security element according to the invention before exposure to laser radiation.

The Fig. 1 shows a side view of a first embodiment of a security element according to the invention before exposure to laser radiation, which consists of a transparent polymeric carrier 1, on the front side of which a first transparent embossed lacquer layer 2.1 with an embossed structure (indicated by the wave-like surface of the embossed lacquer layer 2.1) is applied and a first opaque metallic layer 3.1 is vapor-deposited. Here and below, layers that are the same, of the same type or are functionally similar are represented by the same hatching. A washing color 4.1 which is impermeable to laser radiation is applied to the metallic layer 3.1, the washing color only covering parts of the metallic layer 3.1. The outline of the wash color forms information that can be recognized by a viewer, for example a graphic image, letters, numbers or geometric structures.

On the back of the polymeric carrier 1, the same sequence of layers is applied in mirror image as on the front, consisting of a second transparent embossing lacquer layer 2.2, a second opaque metallic layer 3.2 and wash color 4.2.

If the front of the security element is now exposed to laser radiation, the corresponding laser beam L striking the surface of the security element perpendicularly and being guided parallel to the surface of the security element, the laser radiation penetrates the entire sequence of layers of the security element from the front to the rear, with the exception of the parts the sequence of layers below the wash color 4.1. The metallic layers 3.1 and 3.2 are removed by the laser radiation at all points that are not below the wash color 4.1. In contrast, the metallic layers 3.1 and 3.2 are retained at the points below the washing color 4.1. The laser beam changes or only removes the metallic layers 3.1 and 3.2, all other layers of the security element are not or almost not influenced by the laser beam or to an extent that is not relevant for this invention.

If the washing paint 4.1 and 4.2 is washed off again in a final washing process with water and a rotating mopping cylinder with a felt coating, this results in Fig. 2 shown security element. The metallic layers 3.1 and 3.2 are only left at the points 5.1 and 5.2 where they were previously covered with the washing dye 4.1 and 4.2, the points 5.2 on the back being in exact register with the points 5.1 on the front .

Openings 6.1 and 6.2 are located between points 5.1 and 5.2 with the opaque metallic layer, which, like points 5.1 and 5.2, are aligned with one another in exact register. In the openings 6.1 and 6.2, a viewer only looks at the transparent embossing lacquer layers 2.1 and 2.2 and the transparent polymeric carrier 1 and can thus look through the security element. The result is an opaque graphic image made up of letters, digits or geometrical structures consisting of points 5.1 and 5.2 and transparent openings 6.1 and 6.2.

Fig. 3 shows a side view of a second embodiment of a security element according to the invention before exposure to laser radiation, which is in contrast to the embodiment FIGS. 1 and 2 located only on the front of the carrier 1. The security element consists of a transparent polymeric carrier 1, on the front side of which a first transparent embossed lacquer layer 2.1 with a first embossed embossed structure is applied and a first opaque metallic layer 3.1 is vapor-deposited thereon. A further transparent embossed lacquer layer 2.3 is applied to the metallic layer 3.1, which at least partially fills the embossed structure of the first embossed lacquer layer 2.1 and into which a second embossed structure, preferably different from the first embossed structure, is embossed. The second embossed structure can of course also be designed in the same way as the first embossed structure. A second metallic layer 3.2 is vapor-deposited onto the second embossed structure and a washing color 4.1 that is impermeable to laser radiation is applied to it, the washing color being the same as in FIG Fig. 1 only parts of the metallic layer 3.1 covered. In this embodiment too, the outline of the wash color forms information that can be recognized by a viewer, for example a graphic image, letters, numbers or geometric structures.

The second metallic layer 3.2 is transparent to laser radiation, so that the laser radiation penetrates the layer structure up to the first metallic layer 3.1 and changes, evaporates or removes it and thereby also evaporates or removes the layers overlying the first metallic layer 3.1.

Alternatively, the second metallic layer 3.2 can also be made opaque to laser radiation, so that the laser beam initially changes or removes the second metallic layer 3.2 and, given a sufficiently long exposure time, then changes or removes the first metallic layer 3.1 through the layer structure and thereby the layers lying above the first metallic layer 3.1 are also changed or removed.

The subsequent washing process corresponds to the washing process of the first embodiment FIGS. 1 and 2 .

Claims (4)

1. Method for producing a strip-shaped security element for valuable documents, such as banknotes, identification cards and the like, wherein the security element consists of a polymeric carrier layer (1) having a front side and a rear side, having the following steps:

   a. applying an embossing lacquer layer (2.1) onto the front side of the polymeric carrier layer (1),

   b. introducing an embossed structure into the embossing lacquer layer (2.1),

   c. applying an opaque metallic layer (3.1) onto the upper side of the embossed structure, wherein the metallic layer (3.1) at least partially covers the upper side of the embossed structure,

   d. applying a wash ink (4.1) onto the upper side of the metallic layer (3.1), wherein the wash ink (4.1) and the metallic layer (3.1) at least partially overlap and wherein the contour of the wash ink (4.1) forms a piece of information that is identifiable by a viewer,

   e. removing or transparentizing the metallic layer (3.1) from the upper side of the embossed structure using a laser beam (L), wherein the metallic layer (3.1) is not removed or transparentized at the locations (5.1) at which the metallic layer (3.1) overlaps with the wash ink (4.1),

   f. washing the wash ink (4.1) off the surface of the metallic layer (3.1) using a washing liquid.
2. Method according to Claim 1, characterized in that at least one further layer sequence of embossing lacquer layer (2.3) and opaque metallic layer (3.2) is applied between steps c and d.
3. Method according to at least one of the preceding claims, characterized in that steps a to c and e are additionally also performed on the rear side of the polymeric carrier layer (1).
4. Method according to Claim 3, characterized in that a wash ink (4.2) is applied onto the upper side of the outermost metallic layer (3.2) located on the rear side of the polymeric carrier layer (1), wherein the wash ink (4.2) on the rear side of the polymeric carrier layer (1) is applied with exact registration with respect to the wash ink (4.1) on the front side of the polymeric carrier layer (1) and, after the metallic layer (3.2) is removed or transparentized from the upper side of the embossed structure using a laser beam (L), is washed off the surface of the metallic layer (3.2).

Images