EP2498998A1

EP2498998A1 - Method for producing a security element having registered metallized parts and security element obtainable therefrom

Info

Publication number: EP2498998A1
Application number: EP10778569A
Authority: EP
Inventors: Winfried HOFFMÜLLER; Theodor Burchard
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient GmbH
Priority date: 2009-11-11
Filing date: 2010-11-09
Publication date: 2012-09-19
Anticipated expiration: 2030-11-09
Also published as: WO2011057759A1; DE102009052792A1; EP2498998B1

Abstract

The invention relates to a method for producing a security element (1), to a security element (1) that can be obtained according to the method of the invention, to transfer materials having the security elements according to the invention, and to value items secured with the security elements according to the invention. The security element (1) according to the invention comprises two reflective layers (12, 22), which are glued to each other by means of a resist layer (30), and two optically active layers (52, 62; 72, 82), which are arranged on both sides of the security element. The resist layer (30) has a pattern that is used to create a congruent pattern in the first reflective layer (12). The pattern of the resist layer (30), and thus also of the first reflective layer (12), is exactly reproduced in the second reflective layer (22). This is achieved by gluing on the second reflective layer (22) in the shape of the pattern of the resist layer (30). The regions of the second reflective layer (22) that are not glued are removed, thus forming a negative type.

Description

Method for producing a security element

with calibrated metallizations and security element available therefrom

The invention relates to a method for producing a security element having two metallizations which have been matched to one another and two optically active layers which are arranged on both sides of the security element and which each form a phase delay layer for light passing through, the security element having visually recognizable signs in transmitted light and preferably also in incident light , a security element obtainable by the method, the security element designed as a transfer element, the use of the security element or transfer element for product security, a valuable article equipped with the security element and a method for producing such a valuable article.

Valuables, in particular value documents such as banknotes, shares, identity cards, credit cards, certificates, checks, and other forgery-prone papers, such as identification documents of various kinds, as well as branded articles and packaging of branded goods, are often provided with security elements to secure their authenticity and at the same time serve as protection against unauthorized reproduction. The security elements may, for example, take the form of security threads or stickers or any other form insertable or attachable to a valuable article or security paper, a "valuable article" within the meaning of the present invention being any objectionable to counterfeiting, in particular a value document, while a "security paper "represents the precursor to a value document, which is not yet ready for use. Security elements are typically multilayer elements with multiple functional layers. Functional layers are generally layers that have any properties that can be detected visually or by machine. Functional layers therefore contain, for example, dyes, luminescent substances, thermochromic substances, liquid crystals, interference pigments, electrically conductive substances, magnetic substances, light-diffractive or refractive structures or combinations thereof. The functional layers are usually designed as geometric or figurative patterns or motifs, ie there are functional areas within a layer with the detectable property (for example luminescence) and recesses in between. If a plurality of functional layers are arranged one above the other, it is generally desirable for the functional regions and the recesses in the individual functional layers to be formed exactly in register, ie with high register accuracy, and with contour-sharp edges between the functional regions and the recesses. In this way, one functional layer can be hidden under another, for example magnetic substances under a colored layer, or security elements with multiple functional layers and "negative writing" can be produced.

Negative-type security elements comprise a transparent substrate having at least one non-transparent coating having recesses (the negative writing). These recesses may have any shapes, such as letters, numbers or patterns of any kind, especially line patterns. The term "negative writing" as used in this application accordingly comprises recesses of any shape, ie any non-solidity in a non-transparent coating The more transparent, ie the more translucent, the carrier substrate is, the more pronounced is the contrast between coated and uncoated regions. In the case of very transparent substrates, the negative writing is clearly recognizable in incident light, with less transparent substrates only in transmitted light. If such a security element with negative writing has two different functional layers, for example a motif in the form of a gold-colored metallic coating and the same motif as the red printing ink, then this motif appears to the viewer golden-colored from one side and red from the other side.

Such multilayer motifs are difficult to imitate due to the required high registration accuracy. Motifs with negative fonts in particular offer good counterfeit protection, as inaccuracies during production are particularly easily recognizable in transmitted light, and "primitive" counterfeiting attempts, such as copying with color copiers, are immediately recognizable even to the inexperienced eye.

The tamper-proof is the higher the finer the structures in the functional layers are with the matched-to-each other motifs. Finely contoured structures and forming the perfect register with each other, however, also pose a challenge for authorized manufacturers. A number of methods are known which are intended to enable recesses in a plurality of superimposed functional layers to be registered precisely. H. congruent in all layers, train.

From WO 92/11142 it is known to produce negative writings in functional layers by means of heat-activatable printing inks. The printing inks are printed in the form of the desired negative writing under the functional layers and contain waxes or intumescent additives which soften when heated or split off a gas and thereby produce foam structures. This reduces the adhesion in the areas printed with the activatable ink, and the functional layers can be mechanically removed in these areas.

DE 10 2007 055 112 discloses a method for register-containing, d. H. Conformity of forming a negative typeface in a plurality of functional layers with the aid of a printed in the form of trainees negatives printed under the functional layers ink containing a component which causes a process when irradiated or heated or in contact with a washing liquid, which causes the side The ink is applied to the overlying coating a force that breaks the coating. This force can be exerted by a gas generated from constituents of the ink when they come into contact with washing liquid, irradiated and / or heated, or by a source in the ink, which swells upon contact with a washing liquid. Once the multilayer coating has been broken, it is relatively easily accessible for washing with washing liquid.

The methods mentioned work satisfactorily, as long as no very fine structures are to be formed. However, the problem of forming congruent patterns and negatives in multiple layers with high registration accuracy and contour sharpness is not yet satisfactorily resolved, especially for fine structures. It is therefore an object of the present invention to provide a method for producing security elements with high security against counterfeiting, which makes it possible to form congruent patterns or motifs in two overlapping layers at least in regions. It is an object of the present invention, in particular, to provide such a method with which congruent patterns or motifs can be formed with sharp contours and with high register accuracy, at least partially.

It is also an object of the present invention to provide such a method, wherein the patterns or motifs to be formed have very fine structures. Object of the present invention is also to provide a security element with two motif layers with corresponding patterns or motifs, which have a high registration accuracy.

It is also an object of the present invention to provide such a security element in which the motif layers have very fine structures and have a sharp contours.

It is also an object of the present invention to provide such security elements in the form of transfer elements, as well as to provide security papers and valuables with the security elements or transfer elements according to the invention and methods for producing the security papers and the valuables.

The objects are achieved by the method for producing a security element having the features specified in claim 1, by the security element having the features specified in claim 5, by the transfer material having the features specified in claim 9, by the security paper or the valuable article according to claim 10 and by the method according to claim 11. Specific embodiments of the present invention are set forth in the respective dependent claims. One aspect of the invention relates to a method for producing a security element with negative writing for a security paper or a valuable article, in particular a value document, comprising the following steps:

a) producing a first security element partial element

Providing a first transparent or translucent carrier substrate,

Applying a first embossing lacquer layer as an intermediate layer to the first carrier substrate,

Applying a first reflective layer to the first embossing lacquer layer,

Embossing the first embossing lacquer layer before or after the application of the first reflective layer,

Applying a resist layer to the first reflective layer in the form of a predetermined pattern having resist areas and gaps between the resist areas,

Removing the non-resist areas of the first reflective layer to form first reflective areas and first recesses therebetween;

b) producing a second security element partial element

Providing a second carrier substrate,

Applying a second embossing lacquer layer as an intermediate layer to the second carrier substrate,

Applying a second reflective layer to the second embossing lacquer layer, Embossing the second embossing lacquer layer before or after the application of the second reflective layer,

c) assembling the first and second security element sub-elements into a composite such that the resist layer and the second reflective layer face each other, and bonding the first and second security element sub-elements, preferably under elevated pressure and elevated temperature, and

d) separating the second carrier substrate from the bonded composite, wherein the second reflective layer adheres to the resist areas to form second reflective areas, while the remaining areas of the second reflective layer are separated together with the second carrier substrate, whereby in the second reflective layer are formed second recesses, which form the negative writing together with the recesses in the resist layer and optionally the first recesses in the first reflective layer,

e) arranging a first optically active layer, which forms a phase retardation layer for transmitted light, above the second reflective areas, and arranging a second optically active layer, which forms a phase retardation layer for transmitted light, above the opposite side of the first optically active layer from the first Carrier substrate.

A further aspect of the invention relates to a security element with negative writing which is obtainable according to the above-mentioned method for attachment to or at least partial introduction into a security paper or a valuable article, in particular a value document which is made up of several layers which each cover the entire security - or at least part of the security element, the layers having at least the following:

a transparent or translucent carrier substrate,

a resist layer having resist areas and recesses forming a predetermined pattern,

- A first reflective layer, optionally with first reflective areas and first recesses forming a pattern, if necessary. is due to the pattern of the resist layer,

a second reflective layer having second reflective regions and second recesses forming a pattern at least partially due to the pattern of the resist layer, a first optically active layer forming a phase retardation layer for transmitted light above the second reflective regions, and a second optically active layer, which forms a phase retardation layer for transmitted light, above the side of the first carrier substrate opposite the first optically active layer,

in which

the resist areas directly adhere the first reflective layer and the second reflective layer, and

- The security element between the first carrier substrate and the first reflective layer has at least one embossing lacquer layer. The basic idea of the present invention is to use a stickable resist layer to form congruent patterns in two functional layers. For this purpose, a resist layer in the form of the desired pattern is applied to a first functional layer. The pattern is exactly reproduced in the first functional layer, not by the be removed by the resist protected areas of the first functional layer. Subsequently, the pattern in the second functional layer is reproduced by adhering the second functional layer to the resist. The bonding only takes place in the areas in which the second functional layer makes contact with the resist. The non-bonded regions of the second functional layer are then removed, while the bonded regions can not be removed, whereby an exact reproduction of the pattern of the resist layer and the first functional layer is produced in the second functional layer.

In summary, the security element according to the invention is produced from a layer structure obtainable from two partial elements. The layer structure is expelled on both sides, each with an optically active layer which forms a phase retardation layer for light passing through.

A first subelement consists at least of a carrier substrate and a functional layer, preferably with recesses therein. Additional layers may be present. The functional layer can also be composed of several individual layers.

The carrier substrate of the first security element partial element is preferably a film, for example made of polypropylene, polyethylene, polystyrene, polyester, in particular polycarbonate or polyethylene terephthalate. Transparent or translucent films are particularly preferred. When using such films, the register-formed recesses in the individual functional layers can be clearly recognized as negative writing. A great advantage of the method according to the invention is that it does not require an exposure step, since the resist in the form of the desired motif can be applied by means of methods known per se. Accordingly, the method according to the invention makes it possible to produce precisely calibrated functional layers without exposure steps, the security elements according to the invention nevertheless being characterized by a very high security against counterfeiting.

To produce the first security element partial element, a functional layer is first formed on the carrier substrate. In the present invention, the functional layer is a reflective layer, eg, a metal layer or metallization, preferably selected from the group consisting of aluminum, iron, copper, gold, nickel, and alloys of one or more of these elements. However, a layer of metallic effect paints, a layer with interference pigments or a thin-film element layer can also be used as the functional layer. High-index layers of, for example, T1O2 or Si0 ₂ are also suitable as functional layers. The application of the functional layers is carried out by known methods that are suitable for the respective functional layer, for example by physical vapor deposition (PVD) in metals or by printing on color pigments. The application can be made over the entire area or only in partial areas.

The functional layer can be formed directly on the carrier substrate, or one or more intermediate layers can be provided. For some functional layers, intermediate layers are absolutely necessary, for example if the motif of the functional layer is is a metallized hologram, kinegram, pixelgram or other metallized diffraction structure. In such a case, first an embossing lacquer layer is applied and embossed into the embossing lacquer layer, before or after the metallization, the desired diffractive structure. Alternatively, if appropriate, the carrier film can also be suitably treated.

According to a preferred embodiment of the present invention, one of the motif layers (functional layers) is a metallized diffraction structure such as a metallized hologram, and a further motif layer is particularly preferably a metallized diffraction structure, such as a metallized hologram. If holograms are used below, it is understood that the same applies to other diffraction structures and refractive structures as well as to so-called "matte structures" (lattice images with achromatic grating regions), as defined, for example, in WO 2007/107235 A1 and are described (see in particular claim 1).

As mentioned above, in the case of holograms, an embossing lacquer layer is provided which contains the desired structural information embossed. The structure information is transmitted when glued to the second security element subelement. Holograms or structural information in general can be identical or different in the functional layers of a security element according to the invention. Materials for embossing lacquer layers are known to a person skilled in the art. Suitable embossing lacquers are disclosed, for example, in DE 10 2004 035 979 A1, which discloses heat-sealing lacquers which can likewise be used as an embossing lacquer. A resist is applied to the functional layer of the first security element partial element in a further step. In the context of the present application, a resist is understood to mean any material which allows the process according to the invention to be carried out to produce a security element according to the invention. In particular, such a resist material must be able to protect regions of the first functional layer from removal in order to produce first recesses in the first functional layer only in the unprotected regions. Furthermore, the resist material must have sufficient adhesiveness to bond first and second functional areas together. Accordingly, suitable as resist materials are compounds which can protect areas of the first functional layer from removal and are sufficiently adhesive. Suitable resist materials are therefore, for example, various thermoplastic materials. Preference is given to using thermoplastic resist coatings. Examples of resist coatings according to the invention are given below.

The resist is preferably applied in the form of the desired pattern, for example printed. The person skilled in the art is known for suitable printing methods.

Subsequently, the functional layer of the first security element partial element, ie the first functional layer, is structured, ie the pattern of the resist layer is transferred into the first functional layer. The transmission takes place in such a way that the regions of the first functional layer not protected by resist are removed, in the case of metallic functional layers for example by etchants such as alkalis or acids, for printing inks for example by washing out with suitable solvents. Suitable methods are known to the person skilled in the art. The first safety The subunit element now has a pattern which has congruent functional areas and resist areas and also congruent recesses between these areas. The pattern may, for example, form an encoding or a geometric or figurative motif.

Next, the second security element subelement is manufactured.

The second security element partial element has, like the first security element partial element, at least two layers, namely a carrier substrate and a functional layer formed thereon. In addition, additional layers may be present, or must be present, as stated above for the first security element subelement.

In general, the same applies to the materials, the structure and the manufacture of the layers of the second security element partial element as to the first security element partial element, although it should be noted that no recesses are formed in the functional layer or the functional layer sequence. The recesses are only produced by cooperation with the first security element subelement or the resist layer thereon. In addition, the carrier substrate of the second security element subelement is later separated together with parts of the functional layer of the second security element subelement, for. B. by separation winding (eg, the parts of the functional layer, which are arranged in the composite security element via recesses in the functional layer of the first security element subelement), while the support substrate of other parts of the functional layer of the second security element subelement (eg, the parts that are located in the composite security element over functional areas of the first security element sub-element) must peel off. Therefore, it is necessary lent that the functional layer has only a slight adhesion to the carrier substrate.

The required low adhesive force is already achieved in many Funktionsschichtmateria-, in particular metallization, alone that is waived adhesion-promoting measures between the carrier substrate and functional layer. The meeting of adhesion-promoting measures between the individual layers of a security element is otherwise customary, and the corresponding provisions are known to a person skilled in the art.

If the adhesive force between the carrier substrate and the functional layer is too high, it can be reduced by treating the carrier substrate with suitable additives. For example, the carrier substrate can be washed off with water and / or solvents with or without suitable additives. Suitable additives are, for example, surface-active substances, defoamers or thickeners. Additives can also be introduced into the carrier substrate itself. Alternatively, adhesion-reducing layers can be provided under the functional layer. For the adhesion reducing layers, materials are selected on the surfaces of which, as is generally known, a relatively poor adhesion occurs, for example siliconizations, layers containing release additive (eg Byk 3500), waxes, cured UV lacquers, metallizations, untreated films, such as, for example , Eg PET. By matching the surface energy ratios of the carrier substrate or the adhesion-reducing layer and the functional layer to be detached, an easy detachability of the functional layer can be achieved and thus the desired pattern can be generated in the functional layer of the second security element partial element. The same applies to any intermediate layers present between the carrier substrate and the suspension layer, for example embossing lacquer layers for a hologram. If such an embossing lacquer layer or other intermediate layer is to be taken off together with the carrier substrate, the adhesive force between the intermediate layer and the functional layer, ie for example between the embossing lacquer layer and a metallization applied thereon, must be correspondingly low. If the adhesive force is too high, the intermediate layer should be treated with the above-mentioned additives or an adhesion-reducing layer should be provided.

If a treatment of the carrier substrate or an intermediate layer with adhesion-reducing additives is carried out, residues of the additives can remain on the functional layer after the carrier substrate or the intermediate layer has been separated off. These can normally be washed away simply with an aqueous solution whose pH is suitably adjusted and which may optionally also contain surfactants. Even a laundry with solvents is possible. In persistent cases, high-pressure nozzles and / or mechanical support (felts, brushes) can be used, but this is usually not necessary. Small additive residues can also be "burned off" by corona treatment. Moreover, in many cases can be completely dispensed with a removal of additive residues. Suitable formulated conformal coatings can also adhere adequately to "additive-loaded" functional layers. The first security element subelement, which has a functional layer with functional areas and recesses, and the second security element subelement, which has a functional layer essentially without recesses, are now joined with the aid of the resist layer located on the functional areas of the first security element subelement. the connected. The second security element subelement is placed on the resist layer in such a way that its functional layer contacts the resist layer. The two sub-elements are pressed together, optionally at elevated temperature, whereby the resist layer adheres to the functional layer of the second security element sub-element. Since the resist areas correspond in dimension and shape to the functional areas of the functional layer of the first security element partial element, the bonding with the functional layer of the second security element partial element takes place in such a way that it exactly reproduces the pattern of the functional layer of the first security element partial element. Suitable bonding conditions for thermoplastic resist coatings are typically about 60 ° C to 160 ° C and a line pressure of typically 0.1 N / mm to 15 N / mm, more preferably about 5 N / mm. Finally, the carrier film of the second security element sub-element is peeled off, optionally together with intermediate layers between carrier film and functional layer, wherein the functional layer is peeled off in the non-bonded areas, while of course can not be deducted in the bonded areas, so that a layer structure with two to each other completely congruent patterns arises. The blurs in the separation are less than 10 μπι. The second motif layer may optionally be covered with a protective layer. So structures with a width of about 50 μιτι or less congruent and sharp edges can be formed. The layer structure thus obtained is, as explained below, on both sides, each with an optically active layer which forms a phase retardation layer for passing light equipped. Since it is not always possible to glue the first security element partial element and the second security element partial element to one another immediately after production by means of resist lacquer, it is advantageous if prepared elements can be kept in stock. A certain amount of time is also advantageous in that aging increases the resistance of the resist. This requires that the security element subelements can be stacked or wrapped. To prevent the stacked or wound resist-coated security element sub-elements from sticking together, the coated security-element sub-elements should be well dried. In addition, resist materials should be used which are not prone to blocking at room temperature, ie are "tack-free". The absence of tack can be checked by the following test: Coated pieces of film of about 100 cm ² are stacked and loaded with a weight of 10 kg and stored for 72 hours at 40 ° C. If the pieces of film can then be easily separated without damaging the coatings, the coating should be considered tack-free. Under increased pressure and increased temperature (about 100 ° C is 160 ° C) coated with the resist coatings substrates can be bonded to other substrates. According to the invention, the following resist coatings, in some cases tack-free resist coatings, may be used. The following formulas are to be considered as illustrative and not restrictive.

product

VMCH (vinyl chloride copolymer with acid groups,

Manufacturer: DOW) 20%

Ethyl acetate 80%

VMCA (vinyl chloride copolymer with acid groups,

Manufacturer: DOW) 18% Plasticizer (eg phthalates, citric acid ester ¹⁾ ) 2%

MEK (methyl ethyl ketone, 2-butanone) 80%

H15 / 45M (vinyl chloride copolymer with acid groups,

Manufacturer: Wacker) 18%

Plasticizer (eg phthalates, citric acid ester ¹⁾ ) 2%

MEK (methyl ethyl ketone, 2-butanone) 80%

VMCH (vinyl chloride copolymer with acid groups,

Manufacturer: DOW) 8.35%

VYHH (vinyl chloride copolymer, manufacturer: DOW) 8.35%

Plasticizers (eg phthalates, citric acid ester ¹⁾ ) 3.30%

MEK (methyl ethyl ketone, 2-butanone) 80.00% ^l Examples of suitable plasticizers are: Citrofol B II (ATBC), Citrofol AH II (ATEHV), Citrofol BI (TBC) from Jungbunzlauer, Palatinol N from BASF.

Pioloform BL 18 (polyvinyl butyral, manufacturer: Wacker) 20%

Ethyl acetate 40%

Ethanol 40%

If it is desired to bond the first security element partial element and the second security element partial element together at the lowest possible temperature, the first security element partial element can be printed directly before bonding with a solvent, for example with cyclopentanone, or exposed to a solvent-containing atmosphere , The resist lacquer absorbs the solvent and becomes sticky or melts at low temperature than in the dry state. The security element according to the invention, which has two motif layers arranged on a carrier substrate, is equipped on both sides with a so-called "polarization feature". These are security features that use polarization effects for authenticity assurance. The functional areas which form the surface on one side of the layer structure described above, for example metallized holograms, and the side opposite the functional areas of the carrier substrate are each fully or partially with an optically active layer, which forms a "phase retardation layer" for passing light, ie one Phase-retardation layers are capable of changing the polarization and phase of transmitted light, because the light is split into two mutually perpendicular directions of polarization, which pass through the layer at different speeds, their phases thus shifted from one another Depending on the type and thickness of the layer, the displacement varies in size and has different effects: A λ / 4 layer, that is to say a layer which diffracts the light in one direction by a quarter wavelength from the one to the other delayed in the right direction, can make circularly polarized light circularly or elliptically polarized light and linearly polarized again from circularly polarized light. The phenomenon of polarization and polarizing materials are known. In the context of the invention, one or both of the phase delay layers is preferably formed from nematic liquid-crystalline material. A security element that uses polarization effects for authenticity assurance is described, for example, in DE 10 2006 021 429 A1. When viewed under ambient light, the phase-retarding layer portions of such a security element are hardly noticeable, but when viewed under polarized light, the phase-retardation-layer portions become recognizable. If light is incident on a light-reflecting surface, which is partially coated with polarizing material, through a polarizer, the light is reflected in the coated and in the uncoated regions with different polarization. When viewed through a polarizer observed by light / dark contrasts. Indispensable for achieving good optical effects is that the light-reflecting surface does not change the polarization state of the incident light uncontrollably. Suitable reflective layers are layers of metallizations, eg vapor-deposited metallizations, layers of metallic effect paints, layers with interference pigments or thin-film element layers. High-index layers of, for example, TiO ₂ or SiO ₂ are also suitable as reflection layers.

In the present invention, metallic functional layers, for example metallized diffraction structures, are preferably combined with a polarization feature. The polarization feature may, for example, be embodied as a λ / 4-layer, applied in motif form, over the entire area or in regions, with only one orientation or with two or more different orientations.

The security element according to the invention, which has two motif layers arranged on a carrier substrate, more precisely two reflective layers bonded with a resist, is provided on both sides with the same or different polarization characteristics. The transparent areas (recesses) are not disturbing. The carrier substrate should be isotropic or at least show no excessive dispersion in the optical range.

For alignment of the phase delay layers one or more photoalignment layers are expediently provided. alignment layers (Alignment layers) of linear photopolymers, which can be patterned by exposure to polarized light, are known. In an alignment layer, for example, two alignment directions with photo-resolution can be predetermined by exposing the alignment layer in a first step through a mask with linearly polarized UV radiation. In a second step, the mask is removed and the previously unexposed areas are exposed with 90 ° rotated linearly polarized UV radiation. If nematic liquid crystals are applied to such an alignment layer (eg by evaporation or by gravure printing, screen printing, flexographic printing, knifecoating or curtain coating), then they respectively orient themselves to the local orientation of the alignment layer.

Alternatively, structured, in particular embossed, alignment layers, which are subdivided into regions with different alignment directions, can also be provided in another way for aligning the phase-delay layers. In an expedient embodiment, the embossed alignment layer has a diffractive structure. If nematic liquid crystals are applied to such an alignment layer, they are oriented in each case to the local orientation of the alignment layer, as in the case of the above-described photoalignment layer.

The motifs may also be formed by a partially different thickness of one or both of the phase delay layers. For example, the degree of phase rotation may be proportional to the layer thickness, so that the influence of the polarized light on the layer thickness can be adjusted specifically.

One or both of the phase delay layers may also be present only in regions in the form of a motif. This design presents itself as Extreme case of the above-mentioned embodiment, when the recessed portions of the phase-delay layers are detected as layers with a layer thickness of zero. In particular, if one or both of the phase retardation layers are to be present only partially, they are advantageously produced by means of a transfer material. The transfer material comprises a layer sequence with a phase retardation layer partially applied to a carrier film (for example by intaglio, screen printing, flexographic printing, creasecoating or curtaincoating) and a transfer assist layer provided over the entire area, which is arranged directly above the phase retardation layer, and with an adhesive layer for transferring the layer sequence on the target substrate. The transfer assist layer expediently has a greater adhesion to the partial layer than to the carrier film to be removed, so that the latter can be removed after transfer to the target substrate without damaging the phase delay layer.

In this way, very complex layer structures can be created by repeatedly transferring individual layers or layer composites to one another, whereby optimum production conditions can be selected for each layer or layer composite by the separate production. Thus, it is also possible to combine layered composites which require mutually exclusive production conditions or interfering substrates, since these can be removed during or after the joining of the partial layer composites.

As a carrier film for the transfer material, a smooth film having good surface quality is preferably provided. In particular, a film specially designed for the alignment of liquid crystals can be provided. the. For example, it is advantageous to use a plastic film as a carrier film. Examples of plastic carrier films are films made of PET, OPP, BOPP, PE or cellulose acetate. The carrier foil may also itself comprise a plurality of partial layers, for example the carrier foil may be provided with an alignment layer for the alignment of liquid crystals.

As a transfer assist layer preferably a UV-curing lacquer layer is applied, in particular printed. The UV-curable lacquer layer expediently contains photoinitiators, it being necessary to search for a sufficiently high adhesion of the transfer assist layer to the layer to be transferred and sufficiently low adhesion to the substrate to be removed in order to select the optimal photoinitiator. To further increase the security against counterfeiting, the security elements can also have negative information in the form of patterns, characters or codes that are formed by recesses in one or both optically active layers. Returning to the above-described safety element subelements, the functional layers which have to be separated in areas remaining on the resist layer on the one hand and in areas to be subtracted with the carrier substrate on the other hand may not have too high internal strength in the horizontal direction (in the direction of extension of the resist layer) to ensure a clean and sharp separation. Functional layers whose internal strength is undesirably high are preferably applied in a screened manner. The edge of each halftone dot represents a predetermined breaking point, whereby the transfer to the resist layer in this case comprises a halftone dot as the smallest unit. Is a functional layer off constructed of several individual layers, it may be sufficient to perform only one of the individual layers as a stationary grid. If necessary, the transfer of the grid must be repeated with a further second security element subelement (another dispenser foil) in order to cover the resist completely over the entire area with the second functional layer.

According to a particularly preferred embodiment of the present invention, the security elements have three different views to be perceived by the viewer: a front view in reflected light (front incident light view), a rear view in reflected light (rear side illumination view) and a view in transparency (transmitted light view). These different views can be achieved by equipping the functional areas of the first security element partial element and of the second security element partial element in each case with motifs which can only be perceived from one side (front side or rear side) and also the functional areas, d. H. their areal extent, so varied that the surface variation, another pattern, a so-called sub-pattern is formed.

For example, the pattern perceived in front and back views may be formed by straight or curved, parallel or intersecting lines of a certain width with recesses therebetween. This pattern may additionally be a support for a motif which is primarily perceived by the observer in the form of a view, for example a first hologram visible in front elevational view and a second hologram different therefrom, which is perceived in rear elevational view. Such an effect can be achieved if the lines are formed by first and second functional areas. those that consist of metallizations with different holographic information.

In order to make a sub-pattern visible in transmitted light, the lines are made wider in places. The larger line width is not noticeable in supervision, but in transmitted light, when the motif information, such as the holograms, is no longer perceptible to the viewer, the areal extent of the lines becomes the only recognizable information, and deviations in the line width become sub-patterns perceived. This modulation of line-like features is known for the generation of halftone images. Reference is made in this connection to WO 2004/020217 A1, the disclosure content of which is the subject of the present application. According to the present invention, the patterns of the functional layers can be formed from linear structural elements, as disclosed in WO 2004/020217 Al.

The invention will be explained in more detail with reference to drawings. It should be noted that the present invention is by no means limited to the illustrated functional layers, their particular spatial arrangement and sequence. The layers can each be present over the entire surface or in subregions of the security elements. In addition, further layers, as are customary in the field of security elements, may be contained in the security element constructions, for example protective layers or release layers in the case of transfer elements, adhesion-reducing layers for facilitated separation of the functional layer regions which are used on the security layer Resist layer should remain etc .. It is understood that the additional layers must not interfere with the process flow. It should also be noted that the representations are not are true to scale. In particular, the individual layers are shown greatly exaggerated.

In the figures show:

1 shows a security element according to the invention in a transparent view,

2a to 2e the method sequence in the production of a layer structure which serves as a precursor for the security element according to the invention, a security element according to the invention according to an embodiment, a security element according to the invention according to a further embodiment, wherein (a) the finished security element and ( b) the separately manufactured

Layers or layer composites before laminating shows.

Fig. 1 shows an inventive security element 1 in a view in transmitted light. The security element 1 has inter alia the following layers: a transparent substrate 11, a first and a second functional layer (motif layers), and a resist layer which glues the first and the second functional layer. The two motif layers have the same size and shape in the exemplary embodiment and only partially cover the carrier substrate 11. Of course, the motif layers may be the carrier substrate also cover the entire surface. Additionally, one of the motif layers may only partially cover or partially overlap the other motif layer.

In the embodiment of the security element according to the invention shown in FIG. 1, the two motif layers form a triangular pattern 7 of lines 4, the lines 4 being formed from the functional regions of the functional layers (motif layers) bonded by means of resist. The lines 4 are separated by recesses 3, wherein the recesses 3 are formed by the congruent recesses in the functional areas and the resist layer. The lines 4 vary in their width y, whereby a sub-pattern 7 'becomes perceptible when viewed through the security element, in the embodiment shown another triangle.

Of course, the functional areas do not necessarily have to be in the form of parallel lines, but can have any other shapes.

Which subject an observer in front-side incident light view and rear-side incidental view walirnimmt depends on the special design of the functional areas of the first and the second functional layer.

2 illustrates the process sequence in the production of a layer structure which serves as a precursor for the security element 1 according to the invention. Shown is a section along the line A-A 'of the security element shown in Fig. 1, but again to emphasize that the sequence of layers is merely exemplary.

FIG. 2a shows a first security element partial element 10, consisting of a first carrier substrate 11, for example a film of PET, an embossing lacquer layer 15 applied thereto with embossed diffraction structure 15 'with a gold-colored metallization. The metallization forms a first te functional layer 12, on which in turn a layer 30 of thermoplastic resist in the form of a pattern with resist areas 33 and recesses 34 is printed therebetween. The diffraction structure 15 'continues in the functional layer as a diffraction structure 12'.

Fig. 2b shows the same view as Fig. 2a, but after treatment with an etchant. As a result of the etching, the regions of the first functional layer 12 not protected by resist regions 33 were removed, while the regions of the first functional layer 12 protected by resist regions 33 were retained and form the first functional regions 13. The first functional areas 13 represent an exact reproduction of the pattern of the resist areas 33.

2c shows a section through the second security element subelement 20 to be combined with the first security element subelement 10. The second security element subelement 20 consists of the second carrier substrate 21, the second functional layer 22 and an embossing lacquer layer 25 therebetween. In the embossing lacquer layer 25, a diffraction structure 25 'is impressed, which continues in the second functional layer 22 as a diffraction structure 22'. The second functional layer 22 is a silver-colored metallization. The embossing lacquer 25 was washed off with an aqueous surfactant solution before the application of the metallization 22, with the result that the metallization 22 badly adheres to the embossing lacquer. FIG. 2d shows how the first security element partial element 10 from FIG. 2b and the second security element partial element 20 from FIG. 2c are assembled into a composite 5. The two sub-elements are pressed together, whereby the diffraction structure 22 'of the second functional layer 22 transmits into the resist areas 33, since the resist used is a deformable, preferably thermoplastic resist. By means of the resist areas 33, the first security element partial element and the second security element partial element are glued together. In the case of the thermoplastic resist paints used with preference, bonding is advantageously carried out at elevated temperature. The pressing together of the two security elements sub-elements can take place in one or more stages, ie the two sub-elements are preferably pressed together at elevated temperature in a heating roller with one (single-stage compression) or several so-called calender rolls (multi-stage compression), or else the two parts. Elements are pressed against one another at several heating rollers, each of which is equipped with one or more so-called calender rollers (multi-stage compression). The multi-stage compression can, depending on the particular embodiment, lead to a particularly strong connection of the safety element sub-elements. When using several heating rollers and temperature profiles during compression can be realized.

After bonding and, if appropriate, after a certain waiting time for cooling and for stabilizing the adhesive bond, the second carrier substrate 21 and the second embossing lacquer layer 25 are peeled off, for example by a separating winding. The result is shown in Fig. 2e. Only the regions 23 of the second functional layer 22, which were in contact with resist regions 33, were bonded to the first security element partial element 10. These areas form the second functional areas 23, the one represent exact reproduction of the pattern of the resist areas 33. The remaining regions of the second functional layer 22 were removed together with the second carrier substrate and the embossing lacquer layer, while the regions 23 of the second functional layer 22 bonded to the resist regions 33 were pulled off the embossing lacquer layer.

The regions 13, 33 and 23 are each exactly congruent and in the illustration of FIG. 1 form the lines 4. The recesses 3 between the lines 4 are also exactly congruent and are formed by the recesses 14 in the first functional layer 12, the Recesses 34 formed in the resist layer 30 and the recesses 24 in the second functional layer 22.

The lines 4 (which are formed by the first functional regions 13, the resist regions 33 and the second functional regions 23) are in each case carriers of a diffraction structure in the layer structure illustrated in FIG. 2e. The diffraction structures may, for example, be hologram structures, with different hologram structures preferably being present in the first functional areas 13 and the second functional areas 23. In this case, an observer of the security elements according to the invention shown in FIG. 3 and FIG. 4a in the transmitted-light view recognizes the line pattern shown in FIG. Specifically, in the front-side reflected light view, when viewing the side of the first supporting substrate 11 as the front side, the viewer recognizes the hologram of the first functional layer 12, and in the rear-side incident light view, the hologram of the second functional layer 22.

As a second security element sub-element, for example, a hot stamping foil can be used. In this case, in the case of the separation Only the second carrier substrate 21 are peeled off, while the embossing lacquer layer 25 would remain on the formed security element 1. It can also serve as a protective layer. In general, the provision of a protective layer (not shown in the figure) over the second functional area or the second functional layer is expedient, in particular, therefore, z. For example, the diffraction structure 22 'shown in FIG. 2e or the impression of the diffraction structure 25' in the functional layer 22 are covered and thus are not accessible to counterfeiting attacks. Fig. 3 shows the layer structure of a security element according to the invention according to an embodiment.

The precursor layer structure of FIG. 2e is provided with a first alignment layer 51, for example a photoalignment layer, a first phase retardation layer 52 of a nematic liquid crystal material, and a second alignment layer 61, for example a photoalignment layer, and a second retardation layer 62 of a nematic liquid crystal material. Independently of one another, the two phase delay layers 52 and 62 are each given a motif which is produced on the second functional layer 22 is a photostructurable layer 51 of polyvinyl cinnamate or polyimide which can be patterned by exposure to polarized light in accordance with a first desired motif , On the structured layer 51, a nematic liquid crystal layer 52 is then applied, which is oriented in the areas 52-1 and 52-2, respectively, in accordance with the respective orientation predetermined by the layer 51. The layer 51 acts as an alignment layer for the nematic liquid crystal layer 52, so that the imprinted motif of the photoacoustic alignment layer 51 continues into the liquid crystal layer 52. In an analogous manner, a photostructurable layer 61 of polyvinylminnamate or polyimide is applied to the carrier substrate 11, which can be patterned by exposure to polarized light in accordance with a second desired motif. On the structured layer 61, a nematic liquid crystal layer 62 is then applied, which is oriented in the regions 62-1 or 62-2 in accordance with the orientation predetermined by the layer 61 in each case. The layer 61 acts as an alignment layer for the nematic liquid crystal layer 62, so that the imprinted motif of the photoalignment layer 61 continues into the liquid crystal layer 62.

If the security element 1 shown in FIG. 3 is viewed in a plan view of the phase retardation layer 52 or in a plan view of the phase retardation layer 62 by a suitably superimposed linear polarization filter, then the motif of the retardation layer 52 or the motif of the retardation layer 62 emerges with clear contrast. The contrast is due to the fact that the reflective metallizations 22 and the reflective metallizations 12 appear in different brightness levels.

Overall, a viewer or a machine recording system can thus perceive the motif of the first phase retardation layer 52 formed by the areas 52-1 and 52-2 with high contrast, while the motif of the opposite phase retardation layer 62 does not appear when viewing the front side. Starting from a specific position of the polarizing filter, the motif appears as a negative image during a rotation of the linear polarizing filter (for example by 90 °, if the phase retardation layer is a λ / 4 layer due to its layer thickness). Conversely, a viewer or a machine recording system may perceive the scene formed by the areas 62-1 and 62-2 of the second high-contrast phase retardation layer 62 while the subject of the opposite retardation layer 52 does not appear when viewing the front side. Starting from a specific position of the polarizing filter, the motif appears as a negative image during a rotation of the linear polarizing filter (for example by 90 °, if the phase retardation layer is a λ / 4 layer due to its layer thickness).

The production of a security element 1 according to a further exemplary embodiment according to the invention will now be explained with reference to FIG. 4, FIG. 4 (a) the finished security element 1 and FIG. 4 (b) the separately produced layers or layer composites prior to laminating schematically shows.

To produce a first layer composite 70, a layer 72 of nematic liquid-crystalline material is partially printed on a smooth plastic film 73 of good surface quality in the form of a first desired motif. On this Nematenschicht 72 and the plastic film 73, a transfer assist layer 71 is printed over its entire surface, the adhesion to the plastic film 73 is less than the Nematenschicht 72 and the subsequent transfer of the only partially present Nematenschicht 72 is used. As described in greater detail above, this transfer assist layer 71 can be, for example, a UV-crosslinkable lacquer layer.

Similarly, a second Schichrverbund 80 is prepared by a layer 82 of nematic liquid crystalline material partially on a smooth plastic film 83 good surface quality in the form of a second desired Mo- is printed on. Also on the Nematenschicht 82 and the plastic film 83 a transfer surface 81 is printed over its entire surface, the adhesion to the plastic film 83 is lower than the Nematenschicht 82. Then, the first and second layer composite 70 and 80 on the Oberbzw. Laminated on the lower side of the layer structure of FIG. 2e, as indicated by the arrows 101 and 102. The lamination can preferably take place via an adhesive layer. The two layer composites 70 and 80 may additionally be provided with adhesion promoters in order to improve the laminating resistance with the laminating adhesive. Subsequently, the carrier sheets 73 and 83 are removed by separating coils to form the layer structure shown in Fig. 4 (a).

In the security element shown in Fig. 4 (a), the phase retardation layers 72 and 82 are now not printed over the entire surface, but only partially printed, the shape and arrangement of the printed areas 72 and 82 two independent motifs in the form of patterns, characters or Form codes that serve to verify the security element from opposite sides.

Without linear polarizing filters, the motives of the phase retardation layers 72 and 82 are not apparent to the viewer. On the other hand, if the security element is viewed in plan view by a suitably superimposed linear polarization filter, for example from the side of the phase retardation layer 72, the reflective metallizations 22 will appear differently bright, depending on whether a printed area 72 is present above the metallization. The method according to the invention allows a register-accurate and sharp-edged formation of very fine structures with a width or a diameter of about 50 μm or less. Finally, some specific embodiments of the present invention will be explained.

In the above, the present invention has always been described in the context of a transparent or translucent first carrier substrate. Alternatively, it is also possible to use an opaque first carrier substrate, as a result of which, however, the negative writing becomes poorly recognizable, and only one of the two reflected light views is easily recognizable. An opaque carrier substrate 11 is therefore less preferred. According to a further variant, the formation of recesses 14 in the first functional layer 12 can be dispensed with, ie the first security element partial element 10 can be glued to the second security element partial element 20 in the form shown for example in FIG. In this case, the pattern of the resist layer 30 is reproduced exactly only in the second functional layer 22, which, however, can also lead to very satisfactory results with clearly visible negative writing, for example if the first functional layer 12 is formed as a transparent color. According to a further variant, a first security element partial element 10 with congruent first functional areas 13 and resist areas 33 can be glued to a second security element partial element 20 whose second functional layer 22 already has a pattern but which does not match the pattern of the first functional layer 13 and the sistbereiche 33 matches. Considering a case in which the first functional areas 13 and the resist areas 33 form a line pattern as in FIG. 1, wherein bonding takes place with a second functional layer 22 having a perpendicular line pattern of parallel lines, this results in a security element 1 with punctiform second functional regions 23. The second functional regions 23 are then strung like pearls on a cord onto the lines formed by the first functional regions. In supervision of the second functional areas, the viewer recognizes lines with dots.

Still further variation possibilities arise when both the first functional layer 12, as well as the resist layer 30, and the second functional layer 22 have different patterns. The case in which the first security element subelement 10 has functional regions 13 in the form of circular concentric lines will now be considered as an example. The first functional layer 12 is printed with a resist layer 30 in the form of parallel straight lines 33. A second security element partial element 20 is adhesively bonded thereto, in the second functional layer 22 of which a pattern of functional regions 23 in the form of likewise parallel straight lines is formed which form an angle with the resist region lines 33. The second functional areas 23 stick together with the first security element partial element 10 in the areas in which they come to lie over resist areas 33. In view of the second functional layer, a viewer then, after separating the second carrier substrate 21, sees the circular pattern of the first functional layer with punctiform regions formed by the second functional layer. If a colored resist is used, the resist lines 33 are additionally recognizable. All security elements according to the invention have, inter alia, in common that two of their functional layers are bonded directly to one another by means of a resist, wherein at least the pattern of one functional layer, preferably also the pattern of the other functional layer, is at least partly due to the pattern of the resist layer.

The security elements according to the invention can be provided in the form of transfer materials, ie films or tapes having a multiplicity of finished security elements prepared for the transfer. In the case of a transfer material, the layer structure of the later security element is prepared on a carrier material in the reverse order in which the layer structure is later to be stored on a valuable object, wherein the layer structure of the security element in continuous form or already in the final outline form used as security element on the Carrier material can be prepared. The transfer of the security element on the object of value to be secured by means of an adhesive layer, which is typically provided on the transfer material, but can also be provided on the object of value. Preferably, a hot melt adhesive is used for this purpose. If the security element is prepared in an endless form, an adhesive layer can be provided for transfer either only in the areas of the security element to be transferred, or the adhesive is activated only in the areas to be transferred. The carrier material of the transfer elements is usually deducted from the layer structure of the security elements during or after their transfer to the valuable article. In order to facilitate the detachment, a separating layer (release layer) can be provided between the carrier material and the part of the security elements to be detached. Optionally, the carrier material can also remain on the transmitted security element. The security elements according to the invention can be used to authenticate goods of any kind. Preferably, they are used to authenticate value documents, for example banknotes, checks or identity cards. In this case, they can be arranged on a surface of the value document or be completely or partially embedded in the value document. With particular advantage they are used in value documents hole hole hole. In this case, the advantages of the security elements according to the invention with transparent carrier substrates and from both sides of the value document to be considered, carefully matched motifs, can be particularly beautiful. Even negatives with the finest structures and sub-patterns can be clearly recognized in transmitted light. You are in the achievable according to the invention precision of a counterfeiter practically imitated. Also, a detachment of the security elements in order to transfer them to another valuable item, is practically not possible, because the security elements of the invention always contain at least two adhesive layers, ie they contain an adhesive resist layer and are connected with an adhesive layer with the valuable object to be secured. If, for the bonding of the security element to the object of value, an adhesive which is similar in terms of its chemical and physical properties to the resist in the layer structure of the security element, the layer structure of the security element is always destroyed during detachment attempts.

Claims

Patent claims

1. A method for producing a security element (1) with negative writing (3) for a security paper or a valuable item, in particular a value document, comprising the following steps: a) producing a first security element partial element (10)

Providing a first transparent or translucent carrier substrate (11),

Applying a first embossing lacquer layer (15) as an intermediate layer to the first substrate (11),

Applying a first reflective layer (12) to the first embossing lacquer layer (15),

Embossing the first embossing lacquer layer (15) before or after the application of the first reflective layer (12),

Applying a resist layer (30) to the first reflective layer (12) in the form of a predetermined pattern (7) having resist areas (33) and recesses (34) between the resist areas,

Removing the non-resist areas (33) protected areas of the first reflective layer (12) to form first reflective areas (13) and first recesses (14) therebetween; b) producing a second security element sub-element (20) by providing a second carrier substrate (21), - Applying a second embossing lacquer layer (25) as an intermediate layer on the second carrier substrate (21), - Applying a second reflective layer (22) on the second

Embossing lacquer layer (25),

Embossing the second embossing lacquer layer (25) before or after the application of the second reflective layer (22), c) assembling the first (10) and second (20) security element subelements into a composite (5) such that the resist layer (5) 30) and the second reflective layer (22) facing each other, and bonding the first (10) and the second (20) security element subelement, preferably under elevated pressure and elevated temperature, and d) separating the second carrier substrate (21) of the bonded composite (5), wherein the second reflective layer (22) adheres to the resist regions (33) to form second reflective regions (23), while the remaining regions of the second reflective layer (22) together with the second carrier substrate (22) 21) are separated, whereby in the second reflective layer (22) second recesses (24) are formed, which together with the recesses (34) in the resist layer (30) and optionally the first recesses (14) in the first reflective layer (12) form the negative writing (3), e) arranging a first optically active layer (52; 72), which forms a phase delay layer for passing light, above the two arranging a second optically active layer (62; 82) which forms a phase retardation layer for light passing therethrough, above the opposite side of the first carrier substrate (11) from the first optically active layer (52; 72).

2. The method according to claim 1, characterized in that the resist areas (33) are formed as lines (4) of a defined width y.

3. The method according to any one of claims 1 or 2, characterized in that the resist layer (30) is applied as a pattern (7), in which the

Resist regions (33) and the recesses (34) also form a sub-pattern (7 ').

4. The method according to claim 3, characterized in that the sub-pattern (7 ') by varying the width y of the lines (4) is generated.

5. security element (1) with negative writing (3) for attachment to or at least partial introduction into a security paper or a valuable item, in particular a value document, which is obtainable by a method according to any one of claims 1 to 4 and is composed of several layers each extending over the entire security element (1) or over portions of the security element, the layers having at least the following:

a transparent or translucent carrier substrate (11),

a resist layer (30) having resist areas (33) and recesses (34) forming a predetermined pattern (7), a first reflective layer (12), optionally with first reflective regions (13) and first recesses (14) forming a pattern which is possibly due to the pattern (7) of the resist layer (30), a second reflective layer (12) 22) having second reflective regions (23) and second recesses (24) forming a pattern at least partially due to the pattern (7) of the resist layer (30), a first optically active layer (52; 72) for the transmitted light forms a phase retardation layer above the second reflective regions (23), and a second optically active layer (62; 82) which forms a phase retardation layer for transmitted light above the opposite side of the first optically active layer (52; 72) the first carrier substrate (11), wherein the Resistber oak (33) the first reflective layer (12) and the second reflective layer (22) directly stick together, and the Siche has at least one embossing lacquer layer (15) between the first carrier substrate (11) and the first reflective layer (12).

6. Security element (1) according to claim 5, characterized in that the first reflective layer (12) first reflective areas (13) and first recesses (14) forming a pattern (7) caused by the pattern (7) of the resist layer, and the resist areas (33) directly connecting the first reflective areas (13) and second reflective areas (23) bonding, the first reflecting areas (13) and second reflecting areas (23) and the resist areas (33) viewed in plan view of the security element are congruent, and the first (14) and the second (24) recesses and the recesses ( 34) in the resist layer (30) are congruent and form the negative writing (3).

7. The security element (1) according to any one of claims 5 or 6, characterized in that the second reflective areas (23) and the resist areas (33), preferably also the first reflective areas (13), the shape of lines (4) one have defined width y.

8. Security element (1) according to one of claims 5 to 7, characterized in that in view through the security element (1), a SubMuster (7 ') can be seen.

9. Transfer material for transfer of security elements to a security paper or a valuable item such as a value document, characterized in that it comprises a plurality of transfer elements designed as security elements (1) according to one of claims 5 to 8.

10. Security paper or valuables, such as a document of value, characterized in that it (s) comprises a security element (1) according to one of claims 5 to 8.

11. A method for producing a security paper or a valuables item, such as a value document, characterized in that a Security element (1) according to one of claims 5 to 8 applied thereto or at least partially introduced therein.