Method for producing a transfer structure and transfer structure

Abstract

The invention relates to a method for producing a transfer structure comprising a temporary support and a multi-layer transfer material. The transfer material has, in particular, a transfer element which is characterised in that the film layer of the transport element has, on one side, an adhesion-promoting surface such that subsequent coating layers can be anchored adhesively directly on the film layer of the transfer element by means of pressing.

Description

[0001] Method for producing a transfer structure and transfer structure

[0002] The present invention relates to an improved transfer structure comprising a carrier substrate and a transfer element for value documents and a method for producing a transfer structure.

[0003] Data storage media, such as valuables or identification documents, but also other valuable objects such as branded goods, are often provided with security elements for security purposes. These elements allow the authenticity of the data storage medium to be verified and also serve as protection against unauthorized reproduction. Security elements can, for example, be integrated into the substrate of the data storage medium (security thread, etc.) or applied to the substrate of the data storage medium as a transfer element. A permanent connection between the transfer element and the target substrate is usually achieved by means of an adhesive that can be activated, for example thermally. It is known in the art to provide transfer structures comprising a multi-layer transfer material and a temporary carrier material for applying security elements to the data storage medium.The transfer structures are used, as described, for example, in WO 2010 / 031543 A1, to transfer transfer elements of the transfer material to a target substrate (banknote substrate in sheet or web form). Typically, the temporary carrier material is removed from the transfer elements after their transfer. WO 2010 / 031543 A1 proposes a carrier material with two laminated film layers for such transfer structures.

[0004] Inverted transfer structures are also known, as described, for example, in DE 102019001 422 A1. In this context, "inverted" refers to those transfer structures in which the film in the transfer structure lies beneath (or, in the transferred state, above) the functional layers that provide the security features of the transfer element.

[0005] Against this background, the object of the invention is to provide an improved transfer structure and a corresponding manufacturing method.

[0006] This object is achieved by the transfer structure and the method for producing a transfer structure according to the independent claims. Advantageous embodiments of the transfer structure and the production method are defined in the respective dependent claims. Accordingly, a transfer structure is provided, comprising a carrier substrate and a transfer element for a value document. The transfer element comprises a release layer firmly anchored to the carrier substrate in a detachable manner, a film layer firmly connected to the release layer by a first adhesive layer, a functional multilayer structure comprising an optical security feature firmly anchored to the film layer, and a connecting adhesive layer firmly connected to the functional multilayer structure. The connecting adhesive layer is suitable for forming a permanent connection to a target substrate.

[0007] The transfer structure includes the film layer having an adhesion-promoting surface on one side.

[0008] An advantage of the film layer provided according to the invention with a one-sided adhesion-promoting surface is that no adhesive is required to apply the subsequent layer, but the subsequent layer can be applied or printed directly onto the film layer and can thus be firmly anchored to the film layer.

[0009] The adhesion-promoting surface acts as an adhesion promoter and improves the adhesion of a coating to the film layer.

[0010] A strong bond can be created through a material bond, for example, through adhesive bonding, especially through laminated bonding. Two layers in a strong bond form a body in which the two layers are immovable relative to each other, meaning they can no longer slide or shift against each other.

[0011] A strong adhesive bond can be created by printing, whereby the layer printed on a lower layer is immovable relative to the lower layer, but can be detached from the lower layer depending on the acceptance pressure.

[0012] The transfer structure according to the invention also has advantages with regard to chemical and mechanical resistance of the functional multi-layer structure with the security feature, since it is protected by the film layer.

[0013] The adhesion-promoting surface is preferably formed by a pressure-accepting layer. The film layer accordingly comprises a pressure-accepting layer on one side. The pressure-accepting layer is particularly preferably an acrylate layer. The acrylate layer can already be arranged on the film layer as a very thin layer. In other words, the film layer can be precoated with a very thin acrylate layer on one side.

[0014] Preferably, the side of the film layer with the adhesion-promoting surface faces the functional multilayer structure. In this case, the layer following the film layer is a layer from the functional multilayer structure, for example, a thin lacquer layer by means of which an embossing lacquer layer can be firmly anchored to the film layer. The embossing lacquer layer can be UV-cured, printed from solvent-based raw materials, and / or comprise a thermoplastic.

[0015] The film layer preferably has a thickness between 4 pm and 12 pm, particularly preferably 6 pm. Reducing the thickness of the film layer to a maximum of 6 pm has the additional advantage that the transfer structure is considerably thinner overall and has improved stacking and flatness.

[0016] Advantageously, the carrier substrate comprises a carrier film layer and a support film layer, wherein the carrier film layer and the support film layer are firmly bonded to one another by an adhesive layer. The release layer of the transfer element is firmly and releasably anchored to the carrier film layer of the carrier substrate. In other words, the release layer is anchored to the carrier film layer in such a way that it is firmly bonded with respect to subsequent application of further layers, but can be detached from the carrier film layer upon application of the transfer element to the target substrate. Such anchoring of the release layer can be controlled by a specific choice of the thickness of the release layer. Preferably, the release layer has a thickness corresponding to a weight per unit area of ​​between 0.5 g / m 2 and 5 g / m 2 , preferably 2.5 g / m 2 , corresponds.

[0017] Weight specifications such as these refer to the dried fabric. As a rough approximation, the conversion applies, according to which a weight per area of ​​1 g / m 2 corresponds to a thickness of 1 pm.

[0018] The carrier film layer can have a thickness between 12 pm and 23 pm, preferably a thickness of 19 pm. The support film layer can have a thickness between 6 pm and 23 pm, preferably a thickness of 12 pm.

[0019] After the transfer element has been applied to the target substrate, the release layer lies on top and thus at least partially forms the surface of the applied transfer element or patch. It is advantageous if the release layer is suitable as a print-receiving layer.

[0020] Preferably, the functional multi-layer structure comprises a structured embossing lacquer layer and / or a metallization and / or a dielectric layer and / or a printing ink layer and / or a color-shifting multi-layer structure.

[0021] The structured embossing lacquer layer can be structured with micromirrors, holograms, and / or nanostructures. The transfer element can be equipped with or without clear text. The metallization can be constructed from simple layers or complex layer sequences of different elements.

[0022] The bonding adhesive layer preferably comprises a heat-sealing lacquer or a UV heat-sealing lacquer. This has the advantage that the transfer element can be permanently bonded to the target substrate in such a way that the structure of the transfer element is destroyed by any attempts at tampering. Thus, the patch cannot be removed from the target substrate undamaged. The UV heat-sealing lacquer is additionally crosslinked using UV radiation after application.

[0023] The target substrate can be a paper or polymer substrate. The transfer element or patch can be applied to a hole and / or window (in the target substrate) or not to a hole or window.

[0024] A method for producing a transfer structure comprising a carrier substrate and a transfer element for a value document is also provided. The method comprises the following steps, preferably in the following order: a) printing a release layer of the transfer element onto a carrier film layer of the carrier substrate, b) laminating a film layer onto the release layer, c) applying a functional multilayer structure comprising an optical security feature to the film layer, d) laminating a support film layer onto the carrier film layer of the carrier substrate, e) applying a bonding adhesive layer to the functional multilayer structure.

[0025] In contrast to the conventional manufacturing process for transfer assemblies, the carrier film layer and the film layer of the transfer element are first bonded before the support film layer is bonded to the carrier film layer. This has the advantage that the functional multilayer structure can be applied to an overall smaller stack. This can at least partially reduce manufacturing complexity and achieve improved stacking and flatness.

[0026] Advantageously, step c) comprises a direct application of a thin lacquer layer to the film layer, wherein the film layer comprises an adhesion-promoting surface formed by a pressure-accepting layer, preferably an acrylate layer, and an embossed lacquer layer of the functional multi-layer structure can be firmly anchored by means of the thin lacquer layer.

[0027] This offers the additional advantage that the functional multilayer structure can be applied to the adhesion-promoting surface of the film layer without the need for an additional laminating adhesive layer. This eliminates the need for a laminating adhesive layer, resulting in a more efficient transfer structure, particularly in terms of reduced manufacturing complexity and thus lower costs.

[0028] In one embodiment, the adhesion-promoting surface may be formed by a pressure-accepting layer.

[0029] In one embodiment, the pressure-accepting layer may comprise an acrylate layer.

[0030] In one embodiment, the pressure-accepting layer after process step b) may point in the opposite direction to the carrier film layer and be exposed.

[0031] In one embodiment, the film layer to be laminated in step b) can have a thickness between 4 gm and 12 gm, preferably 6 gm. In one embodiment, the carrier film layer and the support film layer can be firmly bonded to one another by a second adhesive layer in process step d). In process step a), the release layer of the transfer element can be firmly and releasably anchored to the carrier film layer of the carrier substrate.

[0032] In one embodiment, the functional multilayer structure may comprise a structured embossing lacquer layer and / or a metallization and / or a dielectric layer and / or a color-shifting multilayer structure.

[0033] In one embodiment, the bonding adhesive layer may comprise a heat seal lacquer or a UV heat seal lacquer.

[0034] Further details and features of the invention will become apparent from the following description taken in conjunction with the drawings. They show:

[0035] Fig. 1 is a cross-sectional view of a transfer assembly according to one aspect of the invention; and

[0036] Fig. 2 is a flowchart of an embodiment of the manufacturing method according to one aspect of the invention;

[0037] Detailed description of the invention

[0038] Fig. 1 shows a cross-section of a transfer assembly according to one aspect of the invention.

[0039] The transfer element 10 is a multi-layer element. The external shape of the transfer element 10 can correspond to a motif or a simple geometric shape. For example, the transfer element can be provided as a local patch on the value document or as a strip extending over the value document (e.g. banknote). Section A of Fig. 1 shows the transfer structure 1 before transfer of the transfer element 10 to the target substrate 30. In this state, the transfer element 10 is firmly anchored to the carrier substrate 20. The transfer element 10 can be arranged flush with the carrier substrate 20. In other embodiments, the surface of the carrier substrate 20 can be larger than the underside of the transfer element 10. The firmly anchored connection between the transfer element 10 and the carrier substrate 20 is achieved by arranging the release layer 11 on the carrier film layer 21.The carrier film layer 21 can be a polyethylene terephthalate (PET) film and have a thickness between 12 μm and 23 μm, preferably 19 μm. The release layer 11 can be a lacquer layer with a thickness corresponding to a weight per area of ​​between 0.5 g / m. 2 and 5 g / m 2 , preferably 2.5 g / m 2 , is printed onto the carrier film layer 21. The lacquer layer can be printed from solvent-based raw materials, cured with ultraviolet (UV) light, or be a thermoplastic lacquer layer. Thus, the release layer 11 is printed onto the carrier film layer 21 in such a way that the release layer 11 is anchored firmly enough for further production steps of the transfer element 10, yet can be efficiently mechanically detached from the carrier film layer 21 upon application of the transfer element 10 to the target substrate 30.

[0040] A film layer 13 is laminated onto the release layer 11, i.e. brought into adhesive connection with the release layer 11 by means of a first adhesive layer 12, in particular a first laminating adhesive layer. The film layer 13 can have a thickness of between 4 pm and 12 pm, i.e. 4 pm, 5 pm, 6 pm, 7 pm, 8 pm, 9 pm, 10 pm, 11 pm or 12 pm, preferably 6 pm. The film layer 13 comprises on one side an adhesion-promoting surface 18, which in the embodiment of Fig. 1 is formed by a very thin acrylate layer and is shown in Fig. 1 as a thick black bar. The very thin acrylate layer can advantageously already be applied to the film from which the film layer 13 is formed before the production of the transfer element 10. In other words, the film layer 13 is pre-coated on one side with an adhesion-promoting surface 18.Surface 18 acts as an adhesion promoter, since a further layer, such as a lacquer layer, can be firmly anchored to it directly, i.e., without a laminating adhesive layer. The side with the adhesion-promoting surface 18, i.e., the thin acrylate layer in Fig. 1, is the upper side of the film layer 13, i.e., the side facing the functional multilayer structure 14; 15; 16.

[0041] For application of the transfer element 10 to a hole in the target substrate 30, it is advantageous if the film layer 13 has a thickness of 12 μm. For application of the transfer element 10 to the target substrate 30 without a hole, the thickness of the film layer 13 is preferably 6 μm.

[0042] The functional multi-layer structure 14; 15; 16 is arranged in a firmly adhering manner on the adhesion-promoting surface 18 of the film layer 13. The functional multi-layer structure 14; 15; 16 generally comprises at least one optical security feature by which the data carrier or the value document is to be protected. Particularly preferably, the optical security feature is structured differently in certain areas and / or is optically variable (changing impression for the viewer when tilted or rotated). In the transfer structure of Fig. 1, a thin lacquer layer is printed as the first layer of the functional multi-layer structure 14; 15; 16, by means of which a subsequent embossing lacquer layer 14 can be firmly anchored. The embossing lacquer layer 14 cannot be removed from the film layer 13 without causing damage. The thin lacquer layer has a thickness corresponding to a weight per area of ​​between 0.2 g / m 2 and 1.5 g / m 2 , preferably of approx. 0.75 g / m 2, corresponds. The embossing lacquer layer 14 can be structured with micromirrors, holograms and / or nanostructures. A dielectric layer or a metallic layer, for example a metallization, which has a reflection-enhancing effect can be provided on the nanostructures. Optionally, a wash ink layer 15 is also printed onto the embossing lacquer layer 14, from which clear text areas can subsequently be washed out. Washing out the wash ink creates non-metallized areas in which clear text can be provided. A color-shifting multilayer structure 16 can optionally be applied as a further functional layer. In one exemplary embodiment, the color-shifting multilayer structure 16 can comprise a chromium layer as an absorber, a layer comprising a dielectric, such as preferably SiO2, optionally a thin adhesion-promoting layer, such as Cr or Ti, and a reflector layer, preferably consisting of Al.The dielectric can also be made of MgF or ZnS. The reflector layer can also be made of Ti or Ag. Paints with metallic pigments can also be used as a color coating.

[0043] A support film layer 22 is laminated onto the carrier film layer 21 of the carrier substrate 20, ie, arranged in a firmly adhesive connection with the carrier film layer 21 by means of a second adhesive layer 23, in particular a second laminating adhesive layer. The support film layer 22 can have a thickness between 6 μm and 23 μm, preferably 12 μm. Both the support film layer 22 and the carrier film layer 21 are preferably made of PET. The thickness of the second laminating adhesive layer 23 can correspond to a weight per unit area of ​​between 0.7 and 3.5 g / m 2The carrier film layer 21 and the support film layer 22 are firmly bonded to one another by the second laminating adhesive layer 23. A bonding adhesive layer 17 is applied to the upper end of the transfer element on the functional multi-layer structure 14; 15; 16. The bonding adhesive layer 17 can comprise a primer and a heat-sealing lacquer or UV heat-sealing lacquer. After the application of the transfer structure 10 to the target substrate 30, the bonding adhesive in contact with the target substrate 30 can be thermally activated by the application of heat, so that a permanent bond can be established between the transfer element 10 and the target substrate 30. Due to the permanent bond, the transfer element 10 can no longer be removed from the target substrate 30 without causing damage. Section B of Fig. 1 shows the transfer element 10 after it has been transferred to the target substrate 30.In this state, the transfer element 10 is permanently connected to the target substrate 30. The carrier substrate 20 has been detached from the transfer element 10 or its release layer 11 upon application of the transfer element 10 to the target substrate 30.

[0044] In the exemplary embodiment, the bonding adhesive layer 17 is permanently bonded to the target substrate 30. The layers are arranged on the bonding adhesive layer 17 in the reverse order as described above, as shown in section A. Thus, the release layer 11, in the applied state, forms the upper end of the transfer element 10 or patch. Advantageously, the release layer 11 is suitable as a print-receiving layer.

[0045] By arranging the precoated film layer 13 above the functional multilayer structure 14; 15; 16, the latter can be protected from chemical and mechanical attack. The film layer 13 thus serves as a barrier for the functional multilayer structure 14; 15; 16, which includes at least one optical security feature.

[0046] Fig. 2 shows a flow diagram of an embodiment of the manufacturing method according to one aspect of the invention.

[0047] The production of a transfer structure 1 according to one aspect of the invention starts in step a) from the carrier film layer 21, onto which a release layer 11 is printed and thus anchored in a strong, yet releasable manner. In step b), a film layer 13 is laminated onto the release layer 11, i.e., firmly bonded to the release layer 11 by means of a first laminating adhesive layer 12. The film layer can have an adhesion-promoting surface 18 on one side, which can be designed as a print-receiving layer. After production step b), the print-receiving layer faces upwards, i.e., in the opposite direction to the carrier film layer 21, and is exposed. The film layer 13 can also be untreated, i.e., laminated without pre-coating with an adhesion-promoting surface 18. In step c), a functional multi-layer structure 14; 15; 16 is applied to the film layer 13.For this purpose, if the film has an adhesion-promoting surface 18, a thin layer of lacquer is first applied to the side of the film layer 13 with the adhesion-promoting surface 18. A thin application of the lacquer layer corresponds to a weight per area of ​​between 0.2 g / m. 2 and 1.5 g / m 2 , preferably of approx. 0.75 g / m 2 . An embossing lacquer layer 14 is then applied to the thin, cured lacquer layer, preferably with a thickness corresponding to a weight per area of ​​between 2 g / m 2 and 10 g / m 2 , preferably of approx. 4 g / m 2, corresponds. The printed embossing lacquer layer can then be embossed, for example by introducing optically effective microstructures and / or holograms and / or nanostructures. The embossing lacquer layer 14 can be cured with UV light or can be a lacquer layer printed from solvent-containing raw materials or a thermoplastic lacquer layer. In this step, a wash ink layer 15 can optionally be printed at the same time, which subsequently forms the clear text areas. If a film layer 13 was laminated on without an adhesion-promoting surface 18 in step b), the embossing lacquer layer 14 is anchored to the film layer 13 by means of an additional adhesive layer or primer layer, e.g. a laminating adhesive layer.

[0048] Further in step c), a color-shifting multilayer structure 16 can be applied to the embossing lacquer layer 14. Subsequently, in the case of transfer elements with clear text, the printed wash ink can be washed off, creating metallized areas with clear text. In one embodiment, the color-shifting multilayer structure 16 can comprise a chromium layer as an absorber, a layer comprising a dielectric, such as preferably SiO2, optionally a thin adhesion-promoting layer, such as Cr or Ti, and a reflector layer, preferably consisting of Al. The dielectric can also be formed from MgF or ZnS. The reflector layer can also be formed from Ti or Ag. Colors with metallic pigments can also be used as the color coating.

[0049] The multi-layer structure 14; 15; 16 applied in step c) generally comprises at least one optical security feature by which the data carrier or the value document is to be protected. The optical security feature is particularly preferably structured differently in certain areas and / or is optically variable (changed impression for the viewer when tilted or rotated). In step d), a support film layer 22 is laminated onto the carrier film layer 21, i.e. firmly bonded to the carrier film layer 21 by means of a second adhesive layer 23. Accordingly, the support film layer 22 is only laminated after the optical security feature has been completely applied. In step e), a connecting adhesive layer 17 is applied to the functional multi-layer structure 14; 15; 16. The connecting adhesive layer 17 can comprise a primer and layers of heat-sealing varnish or UV heat-sealing varnish.

[0050] After carrying out steps a) to e) in the order shown, the transfer structure 1 is completely manufactured and can be prepared for application of the transfer element 10 on the target substrate 30.

[0051] List of reference symbols

[0052] 1 Transfer setup

[0053] 10 Transfer element 11 Release layer

[0054] 12 first layer of adhesive

[0055] 13 film layers

[0056] 14 embossing lacquer layer

[0057] 15 Wash-on color layer 16 Color-shifting multi-layer structure

[0058] 17 Bonding adhesive layer

[0059] 18 adhesion-promoting surface of the film layer 13

[0060] 20 carrier substrate

[0061] 21 Carrier film layer 22 Support film layer

[0062] 23 second adhesive layer

Claims

Patent claims 1. Method for producing a transfer structure (1) comprising a carrier substrate (20) and a transfer element (10) for a value document, the method comprising the following steps, preferably in the following order: a) printing a release layer (11) of the transfer element (10) onto a carrier film layer (21) of the carrier substrate (20), b) laminating a film layer (13) onto the release layer (11), c) applying a functional multi-layer structure (16) comprising an optical security feature to the film layer (13), d) laminating a support film layer (22) onto the carrier film layer (21) of the carrier substrate (20), e) applying a connecting adhesive layer (17) to the functional multi-layer structure (16).

2. The method according to claim 1, step c) further comprising directly applying a thin lacquer layer to the film layer (13), wherein the film layer has an adhesion-promoting surface (18), and an embossed lacquer layer (14) of the functional multi-layer structure (14; 15; 16) can be firmly anchored by means of the thin lacquer layer.

3. The method according to claim 2, wherein the adhesion-promoting surface (18) is formed by a pressure-accepting layer.

4. The method of claim 3, wherein the pressure-accepting layer is an acrylate layer.

5. Method according to one of claims 3 or 4, wherein the pressure-accepting layer after method step b) points in the opposite direction to the carrier film layer (21) and is open.

6. Method according to one of the preceding claims, wherein the film layer (13) has a thickness between 4 pm and 12 pm, preferably 6 gm.

7. Method according to one of the preceding claims, wherein by method step d) the carrier film layer (21) and the support film layer (22) are firmly bonded to one another by a second adhesive layer (23), wherein by method step a) the release layer (11) of the transfer element is firmly and releasably anchored to the carrier film layer (21) of the carrier substrate (22).

8. Method according to one of the preceding claims, wherein the functional multi-layer structure (14; 15; 16) comprises a structured embossing lacquer layer (14) and / or a metallization (15) and / or a dielectric layer and / or a color-shifting multi-layer structure (16).

9. Method according to one of the preceding claims, wherein the bonding adhesive layer (17) comprises a heat-sealing lacquer or a UV heat-sealing lacquer.

10. Transfer structure (1) comprising a carrier substrate (20) and a transfer element (10) for a value document, the transfer element (10) comprising: a release layer (11) in adhesively releasably anchored connection to the carrier substrate (10), a film layer (13) in adhesive connection with the release layer (11) by a first adhesive layer (12), a functional multi-layer structure (14; 15; 16) comprising an optical security feature in adhesive connection to the film layer (13), and a connecting adhesive layer (17) in adhesive connection with the functional multi-layer structure (14; 15; 16), wherein the connecting adhesive layer is suitable for forming a permanent connection with a target substrate (30), wherein the film layer (13) has an adhesion-promoting surface (18) on one side.

11. Transfer structure (1) according to claim 10, wherein the adhesion-promoting surface (18) is formed by a pressure-accepting layer, preferably an acrylate layer.

12. Transfer structure (1) according to one of claims 10 or 11, wherein the side of the film layer (13) having the adhesion-promoting surface (18) faces the functional multi-layer structure (14; 15; 16).

13. Transfer structure (1) according to one of the preceding claims 10 to 12, wherein the film layer (13) has a thickness between 1 pm and 12 pm, preferably 6 pm.

14. Transfer structure (1) according to one of the preceding claims 10 to 13, wherein the carrier substrate (20) has a carrier film layer (21) and a support film layer (22), wherein the carrier film layer (21) and the support film layer (22) are firmly bonded to one another by a second adhesive layer (23), wherein the release layer (11) of the transfer element is firmly and releasably anchored to the carrier film layer (21) of the carrier substrate (22).

15. Transfer structure (1) according to one of the preceding claims 10 to 14, wherein the functional multi-layer structure (14; 15; 16) comprises a structured embossing lacquer layer (14) and / or a metallization (15) and / or a dielectric layer and / or a color-shifting multi-layer structure (16).

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