DE102021003553A1 - security substrate - Google Patents

Abstract

A security substrate is disclosed which has a substrate front side (2) and a substrate back side (4) opposite this, with a first transfer element (6) which is arranged on the substrate front side (2) and a second transfer element (8) which is arranged on the substrate back (4) is arranged. The first (6) and the second transfer element (8) have a layer sequence (7, 9) comprising a stabilization layer (20), a transfer adhesive layer (14) and at least one further layer, and the first transfer element (6) is asymmetrical to the second transfer element (8) trained. The second transfer element (8) has no carrier layer (12) that gives stability to the transfer element, and the first transfer element (6) either has a carrier layer (12) that gives stability to the transfer element, or has no carrier layer (12) that gives stability to the transfer element, and is designed asymmetrically to the second transfer element (8) with regard to its layer sequence (7).

Description

The invention relates to a security substrate, e.g. for a banknote or banknote paper, which has a substrate front and an opposite substrate back, with a first transfer element, which is arranged on the substrate front and a second transfer element, which is arranged on the substrate back, wherein the first and the second transfer element have a layer sequence comprising a stabilization layer, a transfer adhesive layer and at least one further layer and the first transfer element is designed asymmetrically to the second transfer element.

Transfer elements are known as security elements for security substrates. Applied to one side of the security substrate, they can negatively affect the flatness of the substrate. To compensate, an additional second transfer element can therefore be applied as a stabilizing solution to the opposite side of the substrate (which is therefore referred to as the rear side).

The flatness of the substrate and thus the stability of the substrate during processing is improved by the second transfer element on the back of the substrate. In the understanding of this application, the term “substrate” is synonymous with the term “security substrate”. If a first transfer element is applied or, in the case of banknote printing, intaglio printing (steel engraving) is carried out, a force is applied to the front side of the substrate, which is counteracted by a counter-force with the second transfer element. Stretching/lengthening/rolling out of the substrate and the transfer elements is reduced or avoided, as is rising of the edges of the substrate. This reduces or avoids flatness problems when applying the first transfer element and during the steel engraving. In intaglio printing (steel engraving), an asymmetrical rolling out of the paper and the formation of channels caused by the lateral standing up of the substrate are avoided. The substrates can be processed more easily in banknote printing, for example, so that waste is reduced.

The gluing of the substrate front and the substrate back is described as well as an asymmetric configuration of the two transfer elements on the substrate front and back in the prior art, because the EP 3398781 A1 describes that the two transfer elements differ in width, and the EP 2860040 A1 provides that the two foil elements have different thicknesses and widths.

The invention is based on the object of creating a stabilization solution for a security substrate in order to counteract the flatness problems described, so that problems during processing in printing processes are reduced and rejects are reduced and at the same time an increase in protection against forgery is achieved.

The invention is defined in the independent claim. The dependent claims relate to preferred developments.

A security substrate is provided, which has a substrate front side and a substrate back side opposite thereto. A first transfer element is arranged on the front side of the substrate and a second transfer element on the back side of the substrate.

The first and the second transfer element each have a layer sequence comprising a stabilization layer, a transfer adhesive layer and at least one further layer. The first transfer element is designed asymmetrically to the second transfer element. The second transfer element does not have a carrier layer that imparts stability to the transfer element. The first transfer element either has a carrier layer that imparts stability to the transfer element, or has no such carrier layer and is then designed asymmetrically to the second transfer element with regard to its layer sequence.

The asymmetry between the first transfer element and the second transfer element thus relates to the layer structure—this can be referred to as layer asymmetry.

On the one hand, this can be done by providing a carrier layer imparting stability only in the first, but not in the second transfer element. The layer sequences of the first and of the second transfer element can then be symmetrical (relative to the substrate as the plane of symmetry). The first transfer element then has a symmetrical structure to the second transfer element with regard to the layer sequence, but is nevertheless asymmetrical as a whole to the second transfer element, since it also has the carrier layer, which the second transfer element lacks.

If the transfer element has a carrier layer, it is referred to as a film element in the understanding on which it is based. The carrier layer creates such a stability of the transfer element that, for example, it is possible to span a window in the substrate due to the presence of the carrier layer. A film layer is generally used as the carrier layer (small thickness), but it is also conceivable a paper layer, in particular a transparent one, as the carrier layer. A transfer element without a carrier layer, on the other hand, is not suitable for spanning a window in the substrate.

This property of the carrier layer, which imparts stability to the foil element or the transfer element with carrier layer, can be realized, for example, by a certain thickness or composition of the carrier layer. For example, the carrier layer has a thickness of 4 μm to 40 μm, preferably 6 μm to 19 μm, particularly preferably 8 μm to 15 μm.

In addition to generating the asymmetry between the first and second transfer element by means of a carrier layer only in the first transfer element, both transfer elements can also be formed without the carrier layer that imparts stability to the transfer element. Then the layer sequences of the two transfer elements are not designed symmetrically. There are then asymmetrical layer sequences. The asymmetry is not realized by a carrier layer provided only on one side, but by the layer sequences themselves. Possible layer sequences of the first and of the second transfer element are explained in more detail below. The asymmetry is again present in relation to the substrate as a plane of symmetry.

The asymmetrical configuration of the first and second transfer element enables optical effects in transmitted light. These optical effects can be seen better because (at least) the second transfer element does not have a carrier layer, which is relatively thick and can therefore restrict the ability to see optical effects. In addition, optical effects can also be produced in transmitted light on continuously constructed substrates in which no windows are integrated, by omitting the carrier layer in the layer sequence of the second transfer element. Effects generated in this way in transmitted light allow additional security features to be integrated into the security element, thereby increasing protection against forgery. In most cases, optical effects in transmitted light are less impaired by the carrier layer than by a paper substrate. However, if the substrate is polymer-based and has a high degree of transparency per se, this is not the case. The carrier layer then absorbs short-wave UV light, which means that excitation with a wavelength of e.g. 254 µm, which is sometimes desired, would be prevented through the carrier layer. In addition, the carrier layer can exhibit wavelength-dependent birefringence, which means that polarization effects have less contrast. These disadvantages can be reduced or even avoided by omitting at least one carrier layer.

The interaction of the two possibly differently constructed layer sequences of the transfer elements can generate further optical effects which cannot be generated in the case of first and second transfer elements arranged symmetrically to one another. For example, on the front of the substrate and/or the back of the substrate, fluorescent elements can be applied directly to the substrate (e.g. using heat-sealing lacquer, alone preferably with designs, or in combination with fluorescent primers, preferably with designs), i.e. below the transfer element, which in combination with demetallized areas increase counterfeit security.

Also advantageously, the omission of one or both carrier layers reduces the total thickness of the security substrate, so that stacking properties are improved.

In preferred embodiments, the first transfer element has the carrier layer that imparts stability to the transfer element and is additionally designed asymmetrically to the second transfer element with regard to its layer sequence. The asymmetry from the first to the second transfer element is then based not only on the carrier layer alone, but also on the asymmetry of the layer sequences themselves. This enables the integration of further optical effects in the transmitted light and thus in turn an increase in security against forgery.

In preferred embodiments, the substrate between the transfer elements is continuous, i.e. without windows. The transfer elements are then not designed to span windows, so that the substrate does not have to have a window to produce the additional optical effect, as already explained. This facilitates the manufacture of the security substrate and reduces the manufacturing costs.

In preferred embodiments, the dimensions of the first transfer element differ from those of the second transfer element. This establishes a further asymmetry in addition to the asymmetry caused by the layered structure. Flatness problems can be further reduced as a result, and additional optical effects can be generated by a partial overlap in transmitted light.

The first transfer element, like the second transfer element, can be designed as a strip, the second transfer element on the substrate rear being preferably wider, but particularly preferably 1-4 mm wider than the first transfer element on the substrate front. In a further preferred embodiment, it can also be 1-2 mm narrower than the first transfer element. Furthermore, in embodiments, the thickness of the first and the second transfer element can differ. A displacement of the first transfer element relative to the second transfer element is also possible. The displacement of the transfer elements relative to one another is preferably no greater than 1 mm.

In a preferred embodiment, the security substrate has a smaller thickness in the areas in which the first and the second transfer element are applied than in the adjacent areas. This further improves the stack position and processability.

In a further preferred embodiment, the first and the second transfer element also have at least one fourth layer in the respective layer sequence. This increases the optical variability and, in connection with this, also the security against forgery.

More preferably, the optically attractive areas can be registered within the second transfer element in the longitudinal or transverse direction. The second transfer element itself can also be registered on the substrate or relative to the first transfer element.

The transfer elements, in particular the second transfer element, can be applied directly to the substrate or to an adhesion promoter layer, such as a primer layer. This adhesion promoter layer can be colorless, colored, designed with fluorescence or with pearlescent pigments. The transfer elements can be transferred over the entire surface or partially. After application of the transfer elements, remoistening of the substrate can be omitted in this area.

The second transfer element is applied to the back of the substrate in a second operation before or after the application of the first transfer element to the front of the substrate, but the first transfer element is particularly preferably applied together with the application of the second transfer element in just one operation. All common application methods are suitable, such as flat-flat applications, flat-roll applications, or roll-roll applications.

Banknotes or their precursors are particularly suitable as security substrates, but other documents of value such as identity cards, passports, etc. are also possible. The substrate is preferably based on paper, particularly preferably banknote paper or security paper. However, substrates made of polymers or composite products, such as hybrid composites, foil-foil composites, or foil-paper composites, can also be used. In the case of substrates made of polymers or composite products, the asymmetrical design of the transfer elements is particularly preferred because of their increased transparency.

• 1 eine schematische Schnittdarstellung eines Sicherheitssubstrats in einer ersten Ausführungsform,
• 2 eine schematische Schnittdarstellung eines Sicherheitssubstrats in einer zweiten Ausführungsform,
• 3 eine schematische Schnittdarstellung eines Sicherheitssubstrats in einer dritten Ausführungsform,
• 4 eine Schnittdarstellung eines Sicherheitssubstrats in einer ersten Ausführungsform,
• 5 eine Schnittdarstellung eines Sicherheitssubstrats in einer zweiten Ausführungsform,
• 6 eine Schnittdarstellung eines Sicherheitssubstrats in einer dritten Ausführungsform,
• 7A ein zweites Folienelement mit thermoformbarer Schicht in der Schnittdarstellung,
• 7B ein Formen einer thermoformbaren Schicht an einem sich auf einem Sicherheitssubstrat befindlichen zweiten Transferelement,
• 8 ein zweites Transferelement mit strukturierter Farbannahmeschicht in der Schnittdarstellung,
• 9A ein zweites Transferelement mit unstrukturierter Farbannahmeschicht in der Schnittdarstellung,
• 9B ein auf einem Sicherheitssubstrat aufgebrachtes zweites Transferelement mit unstrukturierter Farbannahmeschicht und matter Beschichtung in der Schnittdarstellung,
• 9C ein auf einem Sicherheitssubstrat aufgebrachtes zweites Transferelement mit unstrukturierter Farbannahmeschicht in der Schnittdarstellung,

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the accompanying drawings, which also disclose features that are essential to the invention. These embodiments are provided for illustration only and are not to be construed as limiting. For example, a description of an embodiment having a plurality of elements or components should not be construed as implying that all of those elements or components are necessary for implementation. Rather, other embodiments may include alternative elements and components, fewer elements or components, or additional elements or components. Elements or components of different exemplary embodiments can be combined with one another unless otherwise stated. Modifications and variations that are described for one of the embodiments can also be applicable to other embodiments. To avoid repetition, the same or corresponding elements in different figures are denoted by the same reference symbols and are not explained more than once. In the figures show:

• 1 a schematic sectional view of a security substrate in a first embodiment,
• 2 a schematic sectional view of a security substrate in a second embodiment,
• 3 a schematic sectional view of a security substrate in a third embodiment,
• 4 a sectional view of a security substrate in a first embodiment,
• 5 a sectional view of a security substrate in a second embodiment,
• 6 a sectional view of a security substrate in a third embodiment,
• 7A a second film element with a thermoformable layer in the sectional view,
• 7B forming a thermoformable layer on a second transfer member located on a security substrate,
• 8th a second transfer element with a structured ink acceptance layer in the sectional view,
• 9A a second transfer element with an unstructured ink acceptance layer in the sectional view,
• 9B a second transfer element applied to a security substrate with an unstructured ink acceptance layer and a matt coating in a sectional view,
• 9C a second transfer element applied to a security substrate with an unstructured ink acceptance layer in a sectional view,

1 FIG. 1 shows a schematic sectional illustration of a security substrate 1 in a first embodiment. The security substrate 1 can in particular be a banknote or its non-individualized precursor, or a banknote/or security paper, but other documents of value, such as identity cards, passports, etc. are also possible. Security substrates 1 made of polymers or composite products (such as hybrid composites, foil/foil composites, or foil/paper composites) are also possible.

The security substrate 1 has a substrate front 2 and a substrate back 4 opposite thereto. A first transfer element 6 with a first layer sequence 7 is applied on the substrate front side 2 and a second transfer element 8 with a second layer sequence 9 is applied on the substrate rear side 4 . In addition to the layer sequence 7 , the first transfer element 6 has a carrier layer 12 that imparts stability to the first transfer element 6 . When the first transfer element 6 is applied to the front side 2 of the substrate, a force 10 is applied, just as it is in the further course of the production process of the security element. The same applies when applying the second transfer element 8 to the substrate rear side 4.

The transfer elements 6, 8 have the layer sequences 7, 9 in the 4 until 9C to be explained further. These layer sequences 7, 9 can be symmetrical or asymmetrical to one another. This is related to the substrate 1 as the plane of symmetry.

If the identical transfer elements 6 , 8 are applied both to the front side 2 of the substrate and to the back side 4 of the substrate, the same layer sequence 7 , 9 is present on both sides of the substrate 1 as seen from the substrate 1 . As related to the representation in 1 that one transfer element is upside down in relation to the other, there is symmetry with regard to the layer sequence 7, 9. If the layer sequences 7 are asymmetric with respect to the layer sequence 9, one layer sequence 7, 9 cannot be converted into the other by simply folding it over.

Within the meaning of this application, a film element is spoken of when there is a transfer element 6, 8 that is sufficiently stable to span a window (its own carrier layer). A transfer element, with or without its own carrier layer 12, has the stability necessary for the transfer process. This carrier layer 12 is thick enough, for example, that the transfer element 6 , 8 can span a window in the substrate 1 . In case of 1 If the first transfer element 6 has the carrier layer 12, it is therefore a foil element which is applied to the substrate front side 2 of the substrate 1. The second transfer element 8 is located on the substrate rear side 4. It has no carrier layer 12. A layer asymmetry is thus realized.

Willingly. 1 the first transfer element 6 is thus designed asymmetrically with respect to the second transfer element 8 . The second transfer element 8 additionally (and optionally) has other, in particular larger, dimensions than the first transfer element 6, so that the first transfer element 6 on the substrate front 2 is overlapped by the second transfer element 8 on the substrate back 4. There is thus a geometric asymmetry in addition to the layer asymmetry described. Other properties that create geometric asymmetry would also be possible, such as a different thickness of the two transfer elements 6, 8.

The layer sequence 7 of the first transfer element 6 corresponds to the layer sequence 9 of the second transfer element 8 in terms of symmetry 1 characterized by the same hatching, which is mirror-symmetrical to the substrate plane, since the transfer element, if it is applied to the substrate rear side 4 instead of to the substrate front side 2, is also mirror-symmetrical to the substrate plane. However, lies in 1 Despite the symmetrical layer sequences 7, 9 of the two transfer elements 6, 8, there is an asymmetry between the first transfer element 6 and the second transfer element 8, because the first transfer element 6 has the carrier layer 12 as an additional layer. There is thus an asymmetry with regard to the layer sequence (layer asymmetry).

Foil or paper layers, for example, can be used as carrier layer 12, which preferably have a suitable thickness so that handling for the mentioned transfer process is ensured. Film layers preferably have a thickness of not more than 36 μm. Paper layers, ie fiber-based carrier layers 12 have preferably a thickness of not more than 20 μm, particularly preferably not more than 30 μm (if they remain on the substrate, ie form a film element). A production film that is removed from the transfer element after the transfer is of course not a carrier layer in the present sense, since it does not remain on the substrate.

When the first transfer element 6 is applied to the front side 2 of the substrate, the force 10 is applied to the substrate 1 . A force 10 is also applied during intaglio printing in the banknote production process.

In order to avoid an unintentional lengthening of the substrate 1 by this force 10, the second transfer element 8 is preferably also applied to the substrate rear side 4 in the same process, i.e. by means of the same force 10. Of course, separate operations are possible.

the 2 and 3 show the same schematic sectional view of the security substrate 1 as 1 . The embodiment of 2 differs from that of the 1 that the first transfer element 6 also has no carrier layer 12, but is formed asymmetrically to the layer sequence 9 of the second transfer element 8 with regard to its layer sequence 7. In addition, there is a difference to 1 in that the first transfer element 6 has the same dimensions as the second transfer element 8 . In this variant of the security substrate 1 there is consequently a dimensional symmetry, but no layer sequence symmetry.

3 shows a third variant of the security substrate 1. The basic structure of the security substrate 1 acc. 3 again corresponds to the in 1 described. The first transfer element 6 according to 3 again includes (as in 1 ) A carrier layer 12, with the difference to the security substrate 1 according to 1 that the layer sequence 7 of the first transfer element 6 now also differs from the layer sequence 9 of the second transfer element 8 (indicated by different hatching). In addition, the second transfer element 8 on the substrate rear side 4 of the same size is (optionally) offset relative to the first transfer element 6 on the substrate front side. There is both a geometric asymmetry and an asymmetry with regard to the layer sequence 7, 9. In addition, the carrier layer 12 creates an asymmetry. One speaks of geometric asymmetry and layer asymmetry.

In 4 is an embodiment of the version of 1 shown in detail so that the layer sequences 7 and 9 can be seen. A hot-seal adhesive layer 14 is first applied to the substrate 1 both on the front side 2 and on the back side 4 of the substrate. The first transfer element 6 is attached to the front side 2 of the substrate with the hot-seal adhesive layer 14 . The second transfer element 8 is attached to the substrate back 4 in a similar manner. In the layer sequence 7 of the first transfer element 6, the carrier layer 12 already described is first applied to the hot-seal adhesive layer 14 before the layers of adhesion promoter layer 16, decorative layer 18, functional layer 20 and ink-accepting layer 22 follow. The ink-accepting layer is consequently located furthest away from the substrate 1 in the layer sequence 7 of the first transfer element 6 .

In the case of the second transfer element 8 , the adhesion promoter layer 16 is applied directly to the hot-seal adhesive layer 14 . This is in turn followed by the decorative layer 18, the functional layer 20 and the ink-accepting layer 22. These five layers together form the layer sequence 9 of the second transfer element 8, with the ink-accepting layer 22 being located furthest away from the substrate 1.

The adhesion promoter layer 16 can be a primer layer, for example. This adhesion promoter layer 16 can be colorless, colored, designed with fluorescence or pearlescent pigments. The decorative layer 18 includes optically attractive areas for creating optically attractive effects, such as patterns, images, colors, etc.

The functional layer 20, which acts as a stabilization layer, follows the decorative layer 18. The functional layer 20 is constituted in such a way that it cannot essentially flow or be plastically deformed either during heat sealing or in a later process, so that it gives the transfer element 6, 8 a certain stability. However, it does not make the transfer element 6, 8 self-supporting, which is why the functional layer 20 is not a carrier layer 12. The functional layer 20 is preferably an (embossed) embossing lacquer layer. A UV lacquer layer, for example, is used as the functional layer 20 . It preferably has a thickness of 2-10 μm, particularly preferably 5 μm. The thickness of the functional layer 20 can be adjusted depending on the application. The functional layer 20 can be opaque or transparent. For example, paints can be used that are already UV (or EBC) crosslinked, but also UV dispersions (aqueous UV paints), preferably those with particularly good film formation, so that the physically dried film, after UV crosslinking, has horizontal forces can absorb without tearing. All standard prepolymers and reactive diluents can be used as UV varnishes. Since, as already explained, a thermoplastic flow of the Functional layer 20 must be avoided, monofunctional compounds are less preferred. It is possible to integrate optically attractive areas into the functional layer 20 .

An example of the composition of the functional layer 20 is: 40% by weight Ebecryl 5129, 17% by weight Ebecryl 81, 35% by weight trimethylolpropane triacrylate (TMPTA), 5% by weight Ebecryl P115 and 3% by weight Irgacure 127 In this formulation, Ebecryl 81 can preferably be substituted for Ebecryl 83 or Craynor CN550. Depending on the curing conditions available, the photoinitiator content can be further increased or supplemented by a type II initiator such as phenylbenzophenone. When curing under inert conditions, the photoinitiator content can be reduced. Furthermore, the UV varnish can be heated in order to achieve a desired target viscosity. TMPTA can be replaced in whole or in part by Ebecryl 130, which is used to produce UV coatings with a high temperature limit. Depending on other requirements, the amine-containing raw materials (Ebecryl P115, Ebecryl 81) can be replaced by amine-free raw materials, and if there are problems with oxygen inhibition, appropriate thiols can be added. Instead of UV cross-linked paints, 2-component systems can also be used.

The ink acceptance layer 22 is, for example, a releasable lacquer that can later be overprinted. The ink receiving layer 22 preferably enables good ink drying. This is necessary because, after the transfer element 6, 8 has been applied, it is on the surface (i.e. furthest away from the substrate 1) and is usually overprinted there. For example, aqueous polyurethane or acrylate dispersions or also hybrid materials with matting agents such as precipitated or polygenic silicic acids, titanium dioxide or the like can be used as the ink acceptance layer 22 . Polyurethane dispersions or acrylate dispersions are i. i.e. R. only releasable from silicone-based production films. Siliconized films or PET films are preferably used as the production film, from which, in particular, a UV lacquer has been removed beforehand. The dispersions mentioned should be able to be released from the production film.

For 4 an exemplary layer sequence 7, 9 was selected. In the direction towards the substrate 1, the described ink acceptance layer 22 can be followed by one or more functional layers 20, one or more decorative layers 18 with optically attractive areas, one or more adhesion promoter layers 16 and one or more hot-seal adhesive layers 14 in any order. Different types of layers would also be possible in the layer sequence 7, 9. It is also possible that not the ink accepting layer 22 but any other layer in the layer sequence 7, 9 or a carrier layer is located furthest from the substrate 1.

5 corresponds to the detailed representation of the layer sequence 7, 9 of the schematic representation 2 . The first transfer element 6 and the second transfer element 8 are arranged symmetrically with regard to their dimensions (dimensional symmetry), both transfer elements 6, 8 also have no carrier layer 12, although the first transfer element 6 differs from the second transfer element 8 with regard to the layer sequence 7, 9 , so that there is again an asymmetry (layer asymmetry). The layer sequence 7 in the first transfer element 6 viewed from the substrate 1 is: hot-seal adhesive layer 14 - adhesion promoter layer 16 - functional layer 20 - decorative layer 18 - ink accepting layer 22. The layer sequence in the second transfer element 8 viewed from the substrate, however, is: hot-seal adhesive layer 14 - adhesion promoter layer 16 - decorative layer 18 - functional layer 20 - ink accepting layer 22. Consequently, the same layers are present but in a different order viewed from the substrate 1, as a result the required asymmetry with regard to the layer sequences 7, 9 between the first transfer element 6 and the second transfer element 8 is produced.

6 corresponds to the detailed representation of the layer sequence 7, 9 of the schematic representation 3 . The first transfer element 6 and the second transfer element 8 are offset from one another on the substrate 1; the described geometric asymmetry is present. The first transfer element 6 has a carrier layer 12, the second transfer element 8 does not, to that end there is asymmetry (layer asymmetry). In addition, the layer sequence 7 of the first transfer element 6 differs from the layer sequence 9 of the second transfer element 8. The layer sequence 7 of the first transfer element 6 is: adhesion promoter layer 16 - functional layer 20 - decorative layer 18 - thermoformable layer 24. In the layer sequence 9 of the second transfer element 8 is the decorative layer 18 and the functional layer 20 are interchanged.

Instead of the ink acceptance layer 22, which in the 4 and 5 provided is in 6 a thermoformable layer 24 is provided. For example, solvent-based coatings based on vinyl chloride copolymers and acrylates or methacrylates or mixtures of these classes of substances can be used as the thermoformable layer 24 . Examples of vinyl chloride copolymers are Solbin A, optionally crosslinked with isocyanates (H15/45M, H30/48M, etc.). Examples of acrylates and methacrylates are, for example, products from the series of Elvacite types and Degalan types, in which it is particularly advantageous that data on the respective temperature limit of the respective products are given. The thermal deformability can be set in a defined temperature range by suitable mixing and adhesion to an embossing tool used for matting can be avoided. For example, a structured heating roller or a calender roller can be used as the embossing tool. While the crosslinking reaction of LTV paints can be inhibited on non-crosslinked vinyl chloride copolymers, the acrylates and methacrylates are uncritical in this respect.

The in the 4 until 6 The layer sequences 7, 9 shown are selected as examples. Other layer sequences 7, 9 with more or fewer layers and the integration of different types of layers are also possible. A transfer adhesive layer and a stabilization layer as well as any further layer must always be arranged on the substrate front side 2 or the substrate back side 4 . A carrier layer 12, which can be inside or outside of the layer sequence 7, 9, will only include one of the two transfer elements 6, 8.

The asymmetrical design of the first transfer element 6 and second transfer element 8 serves the already explained effect of improving the flatness of the security substrate 1 and increasing the counterfeit security of the security substrate 1 by introducing additional optically attractive effects. In the following 7A until 9C Possible configurations of the second transfer element 8 on the substrate rear side 4 will now be described by way of example.

The second transfer element 8 can appear matt or glossy when viewed from the outside. It can be partially matted and/or contain optically attractive areas, such as holograms, micromirrors, microlenses, color or black printing, pearlescent printing, fluorescence, phosphorescence, or thermochromic colors that are integrated into the design of the substrate back 4 . In order to achieve a matt appearance, the second transfer element 8 can either be overprinted with a matt lacquer after application, or the matting is already integrated in the layer sequence 9 of the second transfer element 8 . The optically attractive areas can be applied in an additional layer (e.g. in the decorative layer 18) or integrated into a functional layer 20 (such as e.g. UV varnish), which acts as a stabilization layer. The second transfer element 8 can also be transparent or partially transparent. Areas can also be integrated that result in different thicknesses or a variation in the tactility within the second transfer element 8 after application, and UV absorbers can also be integrated during or after the application of the second transfer element 8 .

Based on 7A until 9C five types of transfer elements are explained, which can be used as the second transfer element 8 within the meaning of the application. Of course, optically attractive areas can also be integrated into all types.

the 7A and 7B represent a first type of the second transfer element 8, in which a frosting is introduced into the second transfer element 8 after application to the substrate rear side 4. A thermoformable layer 24 is applied to a production film 26, which is a siliconized film, for example. The functional layer 20 is applied to the thermoformable layer 24 as a stabilization layer. The functional layer 20 can be applied to the thermoformable layer 24 by means of printing methods such as gravure printing, flexographic printing or screen printing. Next, the decorative layer 18, the adhesion promoter layer 16 and finally the hot-seal adhesive layer 14 are applied, with which the second film element 8 is attached to the substrate 1 in a heat-sealing process. The hot-seal adhesive layer 14 is a transfer adhesive layer within the meaning of the application. After the second film element 8 has been applied to the substrate back 4 , the film 26 is pulled off so that the thermoformable layer 24 is located on the surface of the second film element 8 as the layer furthest away from the substrate 1 . Both the film 26 and the thermoformable layer 24 must be capable of being released, so that the film 26 can be detached. The film 26 is therefore not a partial layer of the transfer element on the substrate. The thermoformable layer 24 is thermally deformable, so that a matt finish can be embossed after the second film element 8 has been applied. This subsequent embossing of the matting can be done, for example, as in 7B shown by a compressive force 10 being applied to the substrate 1 with a calender 28 during the application of the transfer elements 6, 8, with a heating roller 30 applying a counterforce. The heating roller 30 has a rough surface, so that a matt finish is embossed into the thermoformable layer 24 during this printing process. In order to avoid adhesions to the heating roller 30, this is preferably coated with an anti-stick coating.

8th shows a second type of the second transfer element 8. The matting is produced by a matted, rough film. The layer sequence 9 differs from the layer sequence 9 in this regard 7A and B that a struc turated film 34 is used as a basis on which a structured ink acceptance layer 32 is applied. A film is thus structured, for example by embossing, and as a result a matt finish is introduced into an ink acceptance layer 22, as has already been explained in detail, so that the structured ink acceptance layer 32 is formed. This structured ink acceptance layer does not necessarily have to be structured on both sides (as is shown in 8th is shown), it can also be structured on one side. The remaining layer sequence 9 corresponds to the layer sequence 9 from FIG 7A and 7B : Functional layer 20 - decorative layer 18 - adhesion promoter layer 16 - hot-seal adhesive layer 14. The structured film 34 can be pulled off after the second transfer element 8 has been produced. This in turn requires that both the structured film 34 and the structured ink acceptance layer 32 are capable of being released. A siliconized film, for example, is suitable as the structured film 36 . After the structured film 36 has been pulled off, the structured ink acceptance layer 32 remains on the surface, so that a matting effect is perceived from the outside.

9A shows a basic structure of further types 3 to 5 of the second transfer element 8. The ink accepting layer 22 is applied to the production film 26. This is followed by the functional layer 20. It would also be possible here to introduce the thermoformable layer 24 instead of the ink acceptance layer 22, or to omit this layer entirely and apply the functional layer 20 directly to the film 26 using the printing methods described. The decorative layer 18, the adhesion promoter layer 16 and the heat-seal adhesive layer 14 follow as further layers.

9B now shows a third type of the second transfer element 8. The basic structure corresponds to that of the second transfer element 8 according to FIG 9A . This was bonded with the hot-seal adhesive layer 14 to the substrate 1, to the substrate rear side 4, and the film 26 was pulled off. A matte coating 36 is printed onto the overlying ink receptive layer 22 to provide a matte finish.

9C corresponds to a fourth and fifth type of the second transfer element 8, the layer sequence 9 in 9B described, except that the ink receptive layer 22 has not been overprinted with the matte coating 36 and remains as a glossy layer. The fifth type of the second transfer element 8 has the same structure, but the second transfer element 8 is transparent as a whole.

The first transfer element 6 on the substrate front side 2 can be designed with its layer sequence 7 in the same way as the second transfer element 8 with its layer sequence 9 . Viewed from the substrate, further layer sequences 7 would also be possible for the first film element 6, such as: transfer adhesive layer - carrier layer - internal adhesive layer - decorative layer - embossed lacquer layer, or transfer adhesive layer - decorative layer - embossed lacquer layer - carrier - internal adhesive layer - lacquer layer, or transfer adhesive layer - decorative layer - Embossing layer - internal adhesive layer - carrier. However, there must always be a layer asymmetry with regard to the layer sequence 7, 9 of the transfer elements 6, 8.

Reference List

1

substrate

2

substrate front

4

substrate backside

6

first transfer element

7

Layer sequence (first transfer element)

8th

second transfer element

9

Layer sequence (second transfer element)

10

power

12

backing layer

14

heat seal adhesive layer

16

adhesion promoter layer

18

decorative layer

20

functional layer

22

trapping layer

24

thermoformable layer

26

production film

28

calender

30

heating roller

32

structured ink acceptance layer

34

textured foil

36

matte coating

QUOTES INCLUDED IN DESCRIPTION

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

Patent Literature Cited

• EP 3398781 A1 [0004]
• EP 2860040 A1 [0004]

Claims (10)

Security substrate, which has a substrate front (2) and a substrate back (4) opposite this, - with a first transfer element (6), which is arranged on the substrate front (2), and - with a second transfer element (8), which is on the rear side (4) of the substrate, the first (6) and the second transfer element (8) each having a layer sequence (7, 9) comprising a stabilization layer (20), a transfer adhesive layer (14) and at least one further layer, and the first Transfer element (6) is designed asymmetrically to the second transfer element (8), characterized in that - the second transfer element (8) has no carrier layer (12) that imparts stability to the second transfer element, and - the first transfer element (6) either a) a dem has a carrier layer (12) that imparts stability to the transfer element, or b) has no carrier layer (12) that imparts stability to the transfer element, and with regard to its he layer sequence (7) is formed asymmetrically to the second transfer element (8). Security substrate after claim 1 , characterized in that the first transfer element (6) in variant a) is formed asymmetrically to the second transfer element (8) with regard to its layer sequence (7). Security substrate after claim 1 or 2 , characterized in that the substrate (1) between the transfer elements (6, 8) is continuous. Security substrate according to one of the above claims, characterized in that the dimensions of the first transfer element (6) differ from those of the second transfer element (8). Security substrate after claim 4 , characterized in that the first transfer element (6) and the second transfer element (8) are designed as strips, the second transfer element (8) being at least as wide as the first transfer element (6), preferably 1-4 mm wider. Security substrate after claim 4 , characterized in that the first transfer element (6) and the second transfer element (8) are designed as strips, the second transfer element (8) being 1-2 mm narrower than the first transfer element (6). Security substrate according to one of Claims 4 until 6 , characterized in that the first transfer element (6) differs from the second transfer element (8) in terms of its thickness. Security substrate according to one of Claims 4 until 7 , characterized in that the stabilization layer (20) has a thickness of 2-10 µm, particularly preferably 5 µm. Security substrate according to one of the above claims, characterized in that it has a smaller thickness in the areas in which the first (6) and/or the second transfer element (8) are applied than in adjacent areas. Security substrate according to one of the above claims, characterized in that the first (6) and the second transfer element (8) in the layer sequence (7, 9) each also have at least a fourth layer.

Images