EP3150400A1 - Method for manufacturing a safety element - Google Patents

Abstract

A method (100) for producing a security element (1) having a metallized optical diffraction structure (8) in an embossed lacquer layer (3) is shown, in which a lacquer layer (3) is applied, embossed and cured on a support (2) , wherein by embossing the lacquer layer (3) structure depressions (6), structure elevations (7) and an optical diffraction structure (8) are produced, subsequently a reflection layer (9, 9 ') on the structure recesses (6) and structure elevations (7) of embossed lacquer layer (3) provided by metallization and subsequently this reflection layer (9, 9 ') is selectively demetallisiert. In order to provide a simple and reliable method for producing a security element, it is proposed that the optical diffraction structure (8) is embossed on at least one structure elevation (7) and that the selective demetallization comprises joining at least the metallized and the optical diffraction structure (8 7) with a transfer carrier (11) and subsequently a separation of said structure elevation (7) connected to a transfer carrier (11) both from the carrier (2) and from at least one metallized structure depression (6) adjoining this structure elevation (7) ) by removing the transfer carrier (11) from the carrier (2).

Description

The invention relates to a method for producing a security element having a metallized optical diffraction structure in an embossed lacquer layer in which a lacquer layer is applied, embossed and cured on a support, structural embossings, structure elevations and an optical diffraction structure being produced by embossing the lacquer layer, hereinafter a reflection layer is provided on the structure depressions and structure elevations of the embossed lacquer layer by metallization, and subsequently this reflection layer is selectively demetallised.

For the selective demetallization of metallic reflection layers for the production of security elements, it is known ( EP1843901 B1 ) To evaporate portions of these reflection layers by the action of laser radiation. The positional accuracy of the laser radiation is improved in that the partial area to be demetallised has a different contour profile on structural recesses and structure elevations than is the case in the non-demetallizing partial areas. These structural depressions, structure elevations are embossed before their metallization in a coated on a support lacquer layer, which is then cured. In addition, optical diffraction structures can also be embossed into this lacquer layer. Although the selective demetallization can thus be carried out quickly and nevertheless accurately with the aid of laser radiation, this disadvantageously requires considerable effort in the preceding embossing step to prepare the subregions with mutually different laser interactions. In addition, provision of such subregions is often not possible at all by embossing structures predetermined on the security element, so that such processes are not only comparatively complicated by this step, but also only of limited applicability.

The invention is therefore based on the object to provide a method for producing a security element with a metallized optical diffraction structure of the type described input, which is simple and flexible applicable and reproducibly generates an accurate security element.

The invention achieves the stated object in that the optical diffraction structure is impressed on at least one structure elevation and that the selective demetallization comprises connecting at least the structure elevation having the metallized and the optical diffraction structure to a transfer carrier and subsequently separating this structure elevation connected to a transfer carrier from the carrier as well as at least one adjacent to this structure survey metallized structure recess by removing the transfer carrier from the carrier.

If the optical diffraction structure is embossed on at least one structure elevation of the lacquer layer, the lacquer layer can be divided into comparatively sharply delimited partial areas in a procedurally simple manner due to the transition between the structure elevation and the subsequent structural recess. In this way, a subsequent selective demetallization of the metallized embossed lacquer layer or demetallization of a partial region on the metallized embossed lacquer layer can be facilitated, if this selective demetallization involves joining at least the structure elevation comprising the metallized and the optical diffraction structure to a transfer carrier and subsequently separating the latter comprising a transfer structure connected to a transfer carrier, both from the carrier and from at least one metallized structure depression adjoining this structure elevation by removing the transfer carrier from the carrier. In accordance with the invention, the metallization in the region of the diffraction structure can be demetallized in a highly reproducible manner in a precise and accurate position, and unwanted demetallization of the reflection layer on the structure elevations can be avoided. For example, by the Diffraction structure exactly subsequent viewing areas, cutouts, interruptions, exemptions, etc. are created on the security element, which can significantly increase its security against counterfeiting. In addition, it is thus possible to create a reflection layer congruent with the structure elevations - in particular a reflection layer that is congruent with the optical diffraction structure at the structure elevation. An extremely reproducible but nevertheless cost-effective method for producing a tamper-proof security element can accordingly be created.

In general, it is mentioned that the structure supports which are connected to the transfer support and remain thereon can subsequently constitute the security element or a part thereof. The structure elevations connected to the transfer carrier can be subjected to further process steps, such as additional coatings, etc. for this purpose. In general, it is further noted that the lacquer layer can be any layer based on thermoplastic polymers such as PMMA, acrylates, PVC, PU or similar materials. The lacquer layer may further consist of free-radically or cationically curable UV lacquers which i.a. based on polyester, PU or acrylate binders.

If, in addition, the lacquer layer is applied to the carrier as a liquid or pasty lacquer and then embossed and cured, the process can be further accelerated and simplified. Due to the liquid or pasty consistency of the paint can also result in a homogeneous cohesive connection to the carrier and carried out a more uniform filling of the embossing tool, whereby the reproducibility of the process can be further increased.

The simplicity of the process can be further enhanced if the lacquer layer is cured during the embossing, in particular polymerized. In this way, very tight and simple narrow manufacturing tolerances can be followed with respect to the embossed structure. In addition, the manufacturing parameters - such as Curing time, contact time with the embossing tool etc. - can be set flexibly, whereby the reproducibility can be further improved. In general, it is stated that the curing or polymerization of the lacquer layer can be effected by UV radiation. Irradiation by the carrier during embossing is possible, for example, with UV-transparent carrier films. However, the irradiation can also take place from the side of the embossing tool.

If the lacquer layer is embossed with a rotating stamping tool, this can further improve the continuity of the method. In addition, a nearly bump-free embossing of the lacquer layer can be achieved by the rotating embossing tool. A simpler and more reproducible method may result.

If at least one diffraction structure embossed into a structure elevation forms a hologram, a security element with particularly good security effect can be generated in a simple manner in terms of process engineering. The hologram can already be impressed by the embossing tool with high precision in the structure surveys, whereby additional process steps can be avoided. A method with high reproducibility can thus be created.

The reproducibility of the method can be significantly increased if the thickness of the reflection layer is less than the embossing depth of the structure depressions. Thus, it can be reliably avoided that the reflection layers of the structure depressions and structure elevations form an overlap with one another. Among other things, such an overlap could result in an uncontrollable breakage of the reflective layer upon separation, which can lead to blurred contours in the reflective layer on the structure surveys.

If the optical diffraction patterns embossed in the structure elevations have a lower embossing depth than the structural depressions, reliable demetallization can be achieved by separating the structure elevations from the structure depressions be guaranteed during the removal of the carrier. Thus, it is also reliably avoidable that parts of the diffraction structures, in particular parts of the lacquer layer forming the structure elevations, are also removed during demetallization and thus the diffraction structure is destroyed. A particularly reliable and reproducible method can be achieved. In addition, low manufacturing tolerances can be made possible.

The selective demetallization by separating the structure elevations from the structure depressions can be considerably improved if the embossing depth of the structure depressions in the lacquer layer essentially corresponds to the lacquer layer thickness. This means that the bond between the structure elevations and structural depressions to be separated therefrom together with their metallization can be particularly weakened - which not only facilitates the removal of the transfer carrier, but can also ensure an exact, sharp-edged demetallization. This in particular when the structural depressions are stamped to the carrier. A particularly simple and reproducible method can result.

If an adhesion reducing agent is applied to the carrier before the lacquer layer, the separation of the structure elevations from the structural depressions can be further facilitated. Adhesion reducers in particular may prove useful in this case, the use of which leads to a lower adhesive strength between the support and the lacquer layer than between the reflection layer and the support, if the lacquer layer has been through-stamped to the support for this purpose. A particularly simple demetallization can be achieved and thus the reliability of the method can be further increased.

If, in addition, the transfer carrier is coated with an adhesion promoter before it is joined to the structure elevations, it can be ensured that the structure elevations form a stable connection with the transfer carrier via their reflection layer. This can be an unintentional release of the structure surveys be prevented by the transfer carrier during the removal of the carrier from the security element with the transfer carrier stable. The reproducibility of the process can thus continue to increase.

If the security element is provided with a protective lacquer layer after separation from the support, this can facilitate the further treatment of the security element in the process. In addition, the protective lacquer layer can compensate for the unevenness created by the structural depressions and thus create a homogeneous planar surface for further processing steps. In addition, the protective lacquer layer can reliably protect the security element against external influences, such as oxidation of the metallic reflection layer. For example, the protective lacquer layer may be a transparent lacquer layer. It is also conceivable that the protective lacquer layer may also be an adhesive layer in order to be able to provide the security element in a handling-friendly manner on a document of value. Such an adhesive layer may be, for example, a heat-sealable, cold-seal or self-adhesive coating. The adhesive layer may also be applied additionally with a protective lacquer layer.

The security against forgery of the security element can additionally be increased if the security element is provided with further security features. This can be done, for example, by gluing (or laminating) the security element according to the invention with a further security element having other security features.

The security element can be connected to a value document in a manner that are easy to handle, for example, by sticking it to the value document. Even a lamination of the same is conceivable. In general, it is noted that a value document may be, for example, a passport, an identity card, a driver's license, a bill, a credit card, or the like.

• Fig. 1 eine schematische Darstellung des erfindungsgemäßen Verfahrens,
• Fig. 2 einen Detailausschnitt des Trennvorgangs des Verfahrens aus Fig. 1, und
• Fig. 3 einen Detailausschnitt des Prägevorgangs des Verfahrens aus Fig. 1.

In the figures, for example, the subject invention is illustrated in more detail with reference to a variant embodiment. Show it:

• Fig. 1 a schematic representation of the method according to the invention,
• Fig. 2 a detail of the separation process of the method Fig. 1 , and
• Fig. 3 a detail of the embossing process of the method Fig. 1 ,

According to Fig. 1 For example, a method 100 for producing a security element 1 is shown. In this case, in a first step, a lacquer layer 3 is applied to a support 2, which lacquer layer 3 is embossed in a further step with an embossing tool 4 and subsequently hardened - hereinafter shown. The hardening is schematically represented by a radiation source 5, for example. By embossing 3 structural depressions 6 and structure elevations 7 are generated in the lacquer layer. In addition, the lacquer layer 3 has optical diffraction structures 8 after embossing. In a further step, the lacquer layer 3 is metallized to produce a reflection layer 9, 9 '- by the metallization, a reflection layer 9, 9' is created both on the structure depressions 6 and on the structure elevations 7. The metallization takes place as in Fig. 1 shown, with a common metal coating method 10. The reflection layer 9, 9 'is selectively removed in the further process of the method, in particular from the structure recesses 6 of the lacquer layer 3, or demetallisiert therewith.

According to the invention, for the selective demetallization of the reflection layer 9, 9 ', the structure elevations 7 of the lacquer layer 3, in particular a reflection layer 9, are bonded to a transfer carrier 11, as described in detail in FIG Fig. 2 can be recognized. For this purpose, the transfer carrier 11, as a new substrate of the security element 1, is brought into contact with the structure elevations 7 of the lacquer layer 3 on the carrier 2. However, a connection between the structural recesses 6 of the lacquer layer 3 and the transfer carrier 11 does not take place. In a further step, the original carrier 2 is now removed from the security element 1 and thereby the structure elevations 7 connected to the transfer carrier 11 from the metalized structure depressions adjoining the same 6 separately. The structure depressions 6 continue to adhere to the original carrier 2 and are removed therefrom by the transfer carrier 11 in order to produce the security element 1. In particular, those regions of the reflection layer 9 'which are located in the structure depressions 6 are removed together with the carrier 2. By separating the carrier 2 from the transfer carrier 11, the reflection layer 9 of the security element 1 is selectively demetallised on the transfer carrier 11 in the regions of the structure depressions 6, by removing the reflection layer 9 '. As a result, a reflection layer 9 can be produced which is exactly congruent with the structure elevations 7 of the lacquer layer 3. Since a diffraction structure 8 is embossed in at least one of these structure elevations 7 -for example by means of the embossing tool 4-an exactly congruent metallization of the diffraction structure 8 is thus achieved. Accordingly, regions between the structure elevations 7 act as see-through regions 12 through the reflection layer 9, which represent an exact security feature on the security element 1 and lead to a high security against counterfeiting.

As in Fig. 1 can be further recognized, the lacquer layer 3 is applied in the form of a liquid or pasty lacquer 13 to the carrier 2. Due to the liquid or pasty consistency of the paint 13, the cavities 14 of the embossing tool 4 can be better filled and a more homogeneous and exact embossing can be achieved. In addition, sharply demarcated structure elevations 7 can be created. The lacquer layer 3 or the liquid or pasty lacquer 13 forming the lacquer layer 3 are hardened during the contact with the embossing tool 4. This can also be done in Fig. 1 be recognized. For this purpose, a radiation source 5 is shown schematically below the embossing tool 4, which hardens the lacquer layer 3 during contact with the embossing tool 4 by suitable radiation 15. Advantageously, in this case a UV lamp is used as the radiation source 5, wherein the UV radiation 15 emitted by the lamp can polymerize the paint 13. In particular, the embossing tool 4 is a rotating embossing tool 4, whereby the periodicity of the embossed structure is improved and a recurring impact in the embossed structure is avoided. By hardening the lacquer layer 3 during contact with the rotary embossing tool 4, a higher embossing accuracy can be achieved, whereby an overall more robust and reproducible method is provided.

Advantageously, the thickness of the reflection layer 9, 9 'on the structure elevations 7 and on the structure depressions 6 is less than the embossing depth 17 of the structure depressions 6. As a result, an overlap of the reflection layer 9 and the reflection layer 9' is avoided, the strong holding together of the metallic reflection layers. 9 '9' would require. However, if the reflection layer 9, 9 'is significantly smaller than the embossing depth 17 of the structure depressions 6, a simple detachment of the reflection layers 9' from the lacquer layer 3 during the separation can be guaranteed.

From the detail view in Fig. 3 It can be seen that 7 optical diffraction structures 8 are embossed in several structure elevations. In particular, these diffraction structures 8 form holograms 16 which represent a security feature of the security element 1. The embossing depth 17 of the diffraction structures 8 or holograms 16 is advantageously, most significantly, less than the embossing depth 17 of the structure recesses 6 in the embossed lacquer layer 3. Thus, the subsequent separation of the structure depressions 6 are greatly facilitated by the structure elevations 7, since the remaining Lackschichtreste 18 in the structure depressions 6 are kept as low as possible. Remaining lacquer layer residues 18 could adhere to the structure elevations 7 during separation and prevent an exact sharp-edged separation. In this case, it proves to be particularly advantageous if the embossing depth 17 of the structure depressions 6 in the lacquer layer 3 essentially corresponds to the lacquer layer thickness 19. In this case, no appreciable coating layer residues 18 are formed in the structure depressions 6, and the subsequently applied reflection layer 9 can thus adhere directly to the underlying layer, for example the support 2.

In order to facilitate the separation of the structure elevations 7 from the structure recesses 6, an adhesion reducer 20 is applied to the carrier 2 before the lacquer layer 3. The adhesion reducer 20 is advantageously designed such that the adhesive strength between the carrier 2 and the lacquer layer 3 is reduced, but the adhesive strength between the carrier 2 and the reflection layer 9 'is enhanced. This can be done during the separation, as in Fig. 2 illustrated, ensure that the reflective layer 9 'on the support 2 reliably adheres and is removed with, while the lacquer layer 3 of the structure elevations 7 remains undamaged.

The transfer carrier 11 is also coated with a bonding agent 21, whereby the adhesion between the transfer carrier 11 and the reflective layer 9 of the structure elevations 7 is increased. A cohesive connection between the reflective layer 9, the structure elevations 7 and the transfer carrier 11 is ensured. The separation can be carried out more reliably and reproducibly.

As in Fig. 1 shown, the security element 1 is provided after separation with a protective lacquer layer 22. The protective lacquer layer 22 can both serve to protect the security element 1 against external influences, as well as enable a connection of the security element 1 with further security features or value documents. The protective varnish 23 forming the protective varnish layer 22 can offer both a protective effect and an adhesive effect for the security element 1.

Further security features with which the security element 1 can be connected are, for example, holograms, luminescent layers, metal strips, layers with tilting effects or the like. The security element 1 can also be applied to value documents, such as banknotes, credit or bank cards, passports, identity cards, driving licenses, etc.

Claims (13)

Method for producing a security element (1) having a metallized optical diffraction structure (8) in an embossed lacquer layer (3), in which a lacquer layer (3) is applied, embossed and hardened onto a support (2), the embossing of the lacquer layer (3) structure recesses (6), structure elevations (7) and an optical diffraction structure (8) are produced, subsequently a reflection layer (9, 9 ') on the structure recesses (6) and structure elevations (7) of the embossed lacquer layer (3) by metallization provided and subsequently this reflection layer (9, 9 ') is selectively demetallisiert, characterized in that at least one structure elevation (7) the optical diffraction structure (8) is impressed and that the selective demetallization connecting at least the, the metallized and the optical diffraction structure (8) having a structure support (7) with a transfer carrier (11) and subsequently separating them with a transfer carrier (2) and at least one metallized structure depression (6) adjoining this structure elevation (7) by pulling off the transfer carrier (11) from the carrier (2). A method according to claim 1, characterized in that the lacquer layer (3) is applied as a liquid or pasty lacquer (13) on the support (2) and then embossed and cured. A method according to claim 2, characterized in that the lacquer layer (3) cured during the embossing, in particular polymerized, is. A method according to claim 1, 2 or 3, characterized in that the lacquer layer (3) is embossed with a rotating embossing tool (4). Method according to one of claims 1 to 4, characterized in that at least one, in a structure elevation (7) embossed diffraction structure (8) forms a hologram (16). Method according to one of claims 1 to 5, characterized in that the thickness of the reflective layer (9, 9 ') is less than the embossing depth (17) of the structural recesses (6). Method according to one of claims 1 to 6, characterized in that in the structure elevations (7) embossed optical diffraction structures (8) have a lower embossing depth (17) than the structural recesses (6). Method according to one of claims 1 to 7, characterized in that the embossing depth (17) of the structure recesses (6) in the lacquer layer (3) substantially corresponds to the lacquer layer thickness (19). Method according to one of claims 1 to 8, characterized in that before the lacquer layer (3) a Haftverminderer (20) is applied to the carrier (2). Method according to one of claims 1 to 9, characterized in that the transfer carrier (11), before bonding with the structure elevations (7), with a bonding agent (21) is coated. Method according to one of claims 1 to 10, characterized in that the security element (1) after separation from the carrier (2) with a protective lacquer layer (22) is provided. Method according to one of claims 1 to 11, characterized in that the security element (1) is provided with further security features. Method according to one of claims 1 to 12, characterized in that the security element (1) is connected to a value document.

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