Abstract
A security foil including at least a carrier layer, a protection layer and a functional layer. The functional layer has at least one clearance. The security foil includes a printed layer arranged within and partially filling the clearance and adjacent to and non-overlapping with the functional layer. The printed layer represents a marking. Also disclosed is a method for producing such a security foil from an original foil by selectively removing parts of the functional layer of the original foil to produce the clearance in the functional layer and by printing a marking within the clearance to produce the printed layer adjacent to and non-overlapping with the functional layer.
Claims
1. A method for producing a security foil from an original foil comprising at least a carrier layer, a protection layer and a functional layer, the method comprising: selectively removing parts of the functional layer in the original foil to produce a clearance in the functional layer; and printing a marking within the clearance to produce a printed layer adjacent to and non-overlapping with the functional layer.
2. The method according to claim 1, including: applying an adhesive material to produce an adhesive layer covering the functional layer and/or the printed layer.
3. The method according to claim 1, including: applying a first adhesive material on the printed layer, wherein said first adhesive material is different from a second adhesive material covering the functional layer.
4. The method according to claim 1, including: filling at least a part of the clearance between the printed layer and the functional layer with a filling material.
5. The method according to claim 4, wherein during selectively removing parts of the functional layer a pattern area of the functional layer having a predefined shape is spared such that said pattern area is enclosed by the produced clearance.
6. The method according to claim 1, wherein the marking is printed using a digital printing technology, in particular digital ink-jet printing.
7. A Security foil comprising at least a carrier layer, a protection layer, and a functional layer, wherein the functional layer has at least one clearance and in that the security foil includes a printed layer arranged within and partially filling said clearance and adjacent to and non-overlapping with the functional layer, wherein the printed layer represents a marking.
8. The security foil according to claim 7, wherein the security foil includes an adhesive layer covering the functional layer and/or the printed layer.
9. The Security foil according to claim 8; wherein the adhesive layer includes a first adhesive material covering the printed layer and a second adhesive material covering the functional layer, wherein the first adhesive material is different from the second adhesive material.
10. The security foil according to claim 7, wherein the security foil includes a filling material arranged within the clearance of the functional layer, at least enclosing the printed layer.
11. The security foil according to claim 10, wherein the filling material is transparent or the color or brightness of the filling material is complementary to the color or brightness respectively of the printed layer.
12. The security foil according to claim 7, wherein the clearance encloses a security feature formed by a spared pattern area of the functional layer.
13. The security foil according to claim 7, wherein the security foil is configured for transferring a security device according to claim 14 from the security foil onto an object in a single production step.
14. A security device comprising a protection layer and a functional layer, wherein the functional layer has at least one clearance, and the security device includes a printed layer arranged within and partially filling said clearance and adjacent to and non-overlapping with the functional layer, wherein the printed layer represents a marking.
15. A batch of security devices according to claim 14, having a randomly distributed offset between the marking represented by the printed layer and the functional layer and/or having a randomly distributed offset between the clearance and a reference marking provided in the functional layer, wherein one standard deviation of the offset is at least 50 micrometers.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The present teaching will be defined in more detail below by means of preferred exemplary embodiments, to which it is not to be limited to, however, and with reference to the drawings. In detail:
[0035] FIG. 1 schematically illustrates the meta model of a transferable foil used to explain the present teaching;
[0036] FIG. 2 schematically illustrates a state-of-the-art production of security devices comprising a security feature and a machine-readable marking;
[0037] FIG. 3 schematically shows a security foil according to the present teaching;
[0038] FIG. 4 schematically illustrates a production of a security device with the foil of FIG. 2;
[0039] FIG. 5 schematically illustrates the production of a first embodiment of a security foil according to the present teaching in comparison with the production of a conventional security foil;
[0040] FIG. 6 schematically shows a production method for a second embodiment of the present teaching;
[0041] FIGS. 7A-7C schematically shows the layered structure of five embodiments of a security foil according to the present teaching, including the first embodiment according to FIG. 4;
[0042] FIG. 8 schematically shows a possible security foil layout and transfer process for the seventh embodiment of the present teaching;
[0043] FIG. 9 schematically shows the layer structure of the present security foil for the eighth embodiment of the present teaching; and
[0044] FIGS. 10A and 10B schematically show the random offsets involved in the production of the security foil according to the present teaching, which may be used as stochastic security features.
DETAILED DESCRIPTION
[0045] The meta foil 1 shown in FIG. 1 comprises a carrier layer 2, a protection layer 3, a functional layer 4 and an adhesive layer 7. The functional layer 4 comprises a replication layer 5 and a reflection layer 6. The reflection layer 6 in this example comprises a metal material. All subsequent features are based on this meta foil 1, whereas the compound functional layer 4 is depicted as a single layer for simplicity.
[0046] In a state-of-the-art production line according to FIG. 2, a security feature 8 is applied directly onto an object 9 (e.g. a product to be protected against counterfeiting) in the following steps: First, the security feature 8 is transferred from a raw material 10, e.g. a foil. The transfer is performed by hot-stamp foiling or cold-stamp foiling. After the transfer, in an area 11 of the just transferred part of the raw material 10 forming the security feature 8, only a carrier layer 2 (see FIG. 4) of the raw material 10 remains. In a second step, the machine-readable marking 12 is applied by direct part marking, e.g. laser, ink-jet etc. onto the object 9. However, in fast production lines it is difficult to register those two steps. Refer e.g. the production of bottle caps. In those production lines, the objects are continuously moving and rotating and it typically cannot be ensured at the direct part marking step, which side of the bottle cap faces the marking machine. Consequently, in such situations it can happen that the security feature 8 and the marking 12 are arranged on opposite sides of the object 9. Additionally, many producers do not have the equipment to do direct part marking with variable and/or graphical content, which is needed for printing e.g. a QR-code or a DataMatrix-code.
[0047] The present teaching is based on the realization that transfer-technologies such as hot-foil and cold-foil stamping are available for very high production speeds (yet in an unregistered manner). Most of today's printing lines are already equipped with hot- or cold-foil stamping equipment. The present teaching therefore proposes a transferable sheet-like product, in particular a security foil 13, which comprises a security feature 8 as well as a machine-readable marking 12 as shown in FIG. 3. The security feature 8 is delimited by a clearance 14 (see FIG. 5) in the functional layer 4 of the security foil 13. The marking 12 is arranged within the clearance 14 adjacent to the security feature 8 and non-overlapping with the security feature 8. The security feature 8 and the surrounding area 15 of the security foil 13 between the clearance 14 and the edge or border of the security foil 13 have the original foil's characteristics, meaning that the functional layer 4 is intact in these areas. Since they are both part of the security foil 13, the security feature 8 and the machine-readable marking 12 can be transferred to the object 9 together in a single production step as illustrated in FIG. 4.
[0048] A first example of the inventive method for producing a security foil 13 is illustrated in FIG. 5. The method starts from a conventional intermediate foil used as an original foil 16. In the present example the original foil 16 is an intermediate holographic foil. It has a layered structure comprising the following layers: a carrier layer 2, a protection layer 3 and a functional layer 4. With respect to the structure of the functional layer 4 it is referred to the description of FIG. 1. The functional layer 4 is responsible for the holographic effects. In a conventional production line (see FIG. 5 left-hand side), a final adhesive layer 7 would be applied to the original foil 16 to produce a raw material 10 as disclosed in connection with FIG. 2. According to the present teaching (see FIG. 5 right-hand side), first some portions of the original foil 16 are removed. Specifically, by selectively removing the functional layer 4 from the original foil 16 in an area that shall later form the clearance 14. In the present example the clearance 14 is partially filled with a printed layer 17 representing the marking 12. The printed layer 17 may comprise differently colored material as will be described in more detail in connection with FIG. 6. During a transfer, in both cases everything between and including the protection layer 3 and the adhesive layer 7 is transferred to the object 9. Thus, the part of the conventional raw material 10 transferred from the area 11 to the object 9 corresponds to the security feature 8 (compare FIG. 2) comprising a part of the protection layer 3, of the functional layer 4 and of the adhesive layer 7. The part of the present security foil 13 transferred from a transfer area 18 of the security foil 13 to the object 9 forms a security device 19. In contrast to the security feature 8 alone, the security device 19 additionally comprises the printed layer 17 representing the machine-readable marking 12, which is arranged in the clearance 14 of the functional layer 4. In this example the transfer area 18 is a subset or section of clearance 14 together with a pattern area within the clearance 14 for producing the security feature 8.
[0049] For practical applications it is beneficial for the production of the present security foil 13 not to use a finished raw material 10 as the original foil 16, but to intercept an existing production chain while the raw material 10 is still an intermediate foil without the adhesive layer 7 and use this intermediate foil as the original foil 16 for producing the security foil 13. FIG. 6 shows an exemplary method for producing the security foil 13 from an intermediate foil as the original foil 16 comprising the following steps: removing at least one part of the functional layer 4 to create a clearance 14 within the functional layer 4. This removal-step can be performed e.g. with chemical reactions or a laser-based process. Then the foil is conveyed into a digital printing press/ink-jet etc. (not shown) where a machine-readable marking 12 is applied in a registered way forming the printed layer 17. E.g. it can be directly printed onto the protection layer 3. For the registration of the foil and the digital printing steps, print marks can be used. Such print-marks can be produced e.g. by leaving some metalized material of the functional layer 4 to form a print-mark, which can be recognized by a printing press for registration purposes (not shown).
[0050] As shown in FIG. 6, more than one layer may be applied in the clearance 14 by printing. For example, in a two-color print, it may be desirable to print a black code pattern with a first material 20 onto the protection layer 3 and then filling at least a part of the clearance 14 with a filling material 21 to produce a white grounding layer 22, where the two layers 20, 22 together form a printed layer 17 representing the machine-readable marking 12. For simplicity, in all other figures only one printed layer 17 is depicted, representing one or more printed layers (e.g. 20, 22). In the final step, an adhesive layer 7 is applied, similar to the production of the conventional raw material 10 (cf. FIG. 5).
[0051] It has turned out that in practice different embodiments need to be considered. In most illustrations (e.g. FIGS. 5 and 6) the printed layer 17 is indicated having the same thickness as the functional layer 4. Yet this is unlikely in practice, as FIGS. 7A-7C reveal. At least four configurations additional to the optimal configuration shown in FIG. 5 and FIG. 6 may be observed: FIG. 7A shows a situation where the printed layer 17 is thinner than the functional layer 4. This can be compensated (although not exclusively) by using the adhesive layer 23 to cover-up those irregularities and provide a plane surface of the foil. The situation depicted in FIG. 7B is complementary to FIG. 7A in that the printed layer 17 is thicker than the functional layer 4. Again, such irregularities can be covered up with an appropriate adhesive layer 24.
[0052] With regard to FIG. 7C it is instructive to consider that the functional layer 4, which comprises e.g. metal, has different physical properties than the printed layer 17, which typically comprises ink. Especially heat-conductivity and pressure-damping characteristics differ, which may cause problems in the transfer process, where typically thermal- or pressure-activation of the adhesive is key. Therefore, it may be beneficial to use different adhesive layer materials 25, 26 to compensate such differences. Specifically, the adhesive layer materials 25, 26 may be selected such that a constant heat/pressure can be used in the transfer process and all parts of the security device 19 are transferred appropriately. FIG. 7C also reveals small gaps in the adhesive layer, which may still allow good transfer to the object 9 while this may have benefits in terms of processability, i.e. the adhesive layer does not interfere with the clearance 14. Contrary to the illustration in FIG. 7A,76 the adhesive layer may be soaked in an uncontrolled manner into the clearance whilst being applied.
[0053] FIGS. 7A-7C also shows that the clearance may or may not be covered by the adhesive layer. Especially in the first case, since the protection layer 3 and replication layer 5 are typically transparent, to avoid interferences during the transfer process, the clearance 14 may be filled with transparent material.
[0054] Due to the different structure, the security foil 13 does not have the exact same physical properties as a conventional raw material 10. Yet the very same transfer processes can be used by only modifying the process parameters such as heat and/or pressure and/or time, because the general structure comprising the surrounding carrier layer 2, protection layer 3 and adhesive layer 7 remains the same. Similarly, the modified part comprising the functional layer 4 and the printed layer 17 as well as the clearance 14 can be seen as a functional layer with different properties, such as a large number of different function layers are knownand all of them can be transferred using the same process. Thus, the same machinery can be used for the transfer process, albeit it may need to be configured with different operation parameters.
[0055] Consequently, a security device 19 can be transferred from the security foil 13 in one non-registered production step onto an object 9. A coarse registration may be needed to not unintentionally transfer other parts of the security foil 13 interfering with the object's design. For such cases, it is beneficial to provide a clearance 14 that is larger than the security device 19. This accounts for manufacturing- and registration tolerances.
[0056] As shown in FIG. 8, in a preferable setting the original foil 16 is processed in a way such that the clearance 14 corresponding to each entity of the security device 19 overlaps. The result is that the security foil 13 has no areas showing the functional layer 4 except for the pattern area corresponding to the security feature 8. The clearance 14 is typically transparent. Hence only a very coarse registration is needed in the transfer process, because transferring additional, unwanted transparent parts in a large area 27 does not interfere with the design of the object.
[0057] In another preferable setting shown in FIG. 9, the adhesive layer 28 is only applied in the area corresponding to the security device 19 (indicated by the dashed rectangles). Again, only a coarse registration is needed, because a larger area 27 may be exposed to the activators, e.g. temperature, pressure or radiation, and only the area corresponding to the security device 19 will be transferred to the object 9, since only this area is covered by an activatable adhesive layer. This also allows to fill the clearance 14 completely with the printed layer 17. This setting is particularly cost-effective, because only a small part representing the area corresponding to the security device 19 of the functional layer 4 needs to be removed.
[0058] Each step in the process shown in FIG. 10A of transforming an original foil 16 to the security foil 13 is subject to registration- and process tolerances. The original foil 16, in particular the functional layer 4, may comprise at least one reference marking 29, which can be detected optically and may occur in a periodic manner. In a preferable embodiment the clearance 14 is chosen in a way that it encloses a security feature 8, such that the security feature 8 corresponds to an area in the original foil 16 comprising at least one reference marking 29. This typically requires a registration between the original foil 16, i.e. in respect to the at least one reference marking 29, in the selective removal process producing the clearance 14. This registration is subject to registration tolerances, hence the at least one reference marking 29 may have a (random) offset relative to the security feature border 30. In a following production step, the marking 12 is arranged in the clearance 14, which again uses registration means (e.g. the mentioned printing marks) which are subject to manufacturing tolerances as well. Consequently, the marking 12 may be characterized by having a random offset in respect to the security feature 8 and in particular also to the reference marking 29. As shown in FIG. 10B, the stochastic nature of registration tolerances may produce random and unique arrangements of the marking 12, the reference marking 29 and the security feature border 30 comprised in the security device 19. In particular, two entities 32, 33 from a batch of security devices may have different random arrangements, albeit being produced with a registered process. The marking 12 may be used to store a representation of the random arrangement and/or an identifier, which allows e.g. to store the representation of the random arrangement together with said identifier in a database, in particular for authentication purposes of the security device 19.
