LAYER STRUCTURE WITH ENGRAVING AS VISIBLE SECURITY ELEMENT

Abstract

Provided is a layer structure, preferably a security form in a book cover, particularly preferably a security form in a book cover for identification or security documents, comprising at least a) a first radiation-engravable layer a) containing at least one polymeric material; and b) at least one further layer b) containing at least one polymeric material, preferably a thermoplastic elastomer, preferably a thermoplastic polyurethane with a hardness of 40 Shore A according to DIN ISO 7619-1-2012-2 to 95 Shore D according to DIN ISO 7619-1-2012-2; wherein the further layer b) overlies the first layer a) at least partly to form an overlapping region, and wherein a coherent engraving partly extends in the overlap region, preferably in the further layer b), and partly in the portion of layer a) that extends outside the overlap region, most preferably exclusively in the further layer b). The invention also relates to a method for producing this layer structure and to a laminate comprising such a layer structure and to the use of the layer structure in a security document.

Claims

1. A layer structure, comprising a hinge formed between a security form and a book cover of an identification or security document, comprising at least a) a first radiation-engravable layer a) comprising at least one polymeric material; and b) at least one further layer b) comprising at least one polymeric material, having a Shore A hardness of 40 to DIN ISO 7619-1-2012-2 up to a Shore D hardness of 95 to DIN ISO 7619-1-2012-2; wherein the further layer b) partly covers the first radiation-engravable layer a) to form an overlap region, and wherein a coherent engraving partly extends in the overlap region, and partly in the portion of layer a) that extends outside the overlap region.

2. The layer structure as claimed in claim 1, wherein at least one of the first layer a), and the second layer b), further comprise at least one additive having an absorption maximum in the wavelength range of the focused nonionizing electromagnetic radiation used for the production of the engraving, or wherein at least one of the first layer a), and the second layer b), is coated with at least one additive in the form of a coating composition having an absorption maximum in the wavelength range of the focused nonionizing electromagnetic radiation used.

3. The layer structure as claimed in claim 1, wherein the second layer b) contains an IR absorber having a transmittance of light of 20% in the wavelength range of 950 to 1200 nm, in an amount of 0.5% to 10% by weight, based on the total amount of layer b).

4. The layer structure as claimed in claim 1, wherein the portion of the engraving on the second layer b) is different in terms of color or structure than the portion of the engraving on the first layer a).

5. The layer structure as claimed in claim 1, wherein the portion of the coherent engraving incorporated on the first layer a) has a colored or black character.

6. The layer structure as claimed in claim 1, wherein the portion of the engraving that extends within the overlap region and is incorporated into the second layer b) is characterized by a colorless altered structure of the polymeric material.

7. The layer structure as claimed in claim 1, wherein removal of the second layer b) from the first layer a) separates the coherent engraving at least in the overlap region.

8. The layer structure as claimed in claim 1, wherein the portion of the engraving within the overlap region is readable only atop the second layer b).

9. The layer structure as claimed in claim 1, wherein the polymeric material of the first layer a) contains a thermoplastic selected from the group consisting of polymers of ethylenically unsaturated monomers, polycondensates of bifunctional reactive compounds, and polyaddition products of bifunctional reactive compounds.

10. The layer structure as claimed in claim 1, wherein the first layer a) comprises at least one selected from the group consisting of a dye and at least one pigment.

11. The layer structure as claimed in claim 1, wherein the second layer b) comprises at least one thermoplastic polyurethane.

12. A method of producing a layer structure having a join zone, the method including at least the steps of: I) providing a first layer a) comprising at least one material which is laser-engravable; II) at least partly covering the first layer a) with at least a portion of a second layer b) comprising at least one polymeric material, to form an overlap region of the second layer b) onto the first layer a); III) producing an engraving in the layer structure, wherein a portion of the engraving is present on a portion of the first layer a) which is not covered by the second layer b) and a further portion of the engraving is present at least on a portion of the second layer b) and optionally on a portion of the first layer a) which is covered by the second layer b), to form a join zone, wherein the layers a) and b) are inextricably bonded to one another in the join zone.

13. A laminate comprising a layer structure as claimed in claim 1.

14. The layer structure as claimed in claim 1 for production of a security document.

15. A method of producing a multilayer laminate, comprising at least the steps of i) providing a layer structure as claimed in claim 1; ii) laminating the layer structure from step i) at a temperature of 80 C. to 220 C. and with a pressure of 2 N/cm.sup.2 to 500 N/cm.sup.2, with an engraved lamination plate; iii) optionally, folding the layer structure along a centerline of the layer structure, such that the layer structure and laminate are folded symmetrically; iv) optionally, pressing the layer structure after step iii) along the centerline, between two rollers, rolls and/or plates, at a temperature which is 0.5 C. to 150 C., above the softening temperature of the outermost layer, for a period of 2 to 20 seconds; v) optionally, removing the laminate including the layer structure from the press.

Description

FIGURES

[0245] FIGS. 1-4 describe preferred embodiments for the layer structure and the method of production thereof, which should not be interpreted in a limiting manner The figures show:

[0246] FIG. 1: a diagram of a layer structure in the form of a travel passport with a personalized engraving on the first layer a) in black and on the further layer b) in the overlap region in milky to white;

[0247] FIG. 2: a close-up of the representation of the security document from FIG. 1 in the form of a travel passport with a personalized engraving on the first layer a) in black (first part-engraving) and on the further layer b) in the overlap region in cloudy to white (further part-engraving);

[0248] FIG. 3: a layer structure of the invention, in which the personalized engraving cannot be detached nondestructively;

[0249] FIG. 4a: a schematic diagram of the method of producing a layer structure of the invention with join zone;

[0250] FIG. 4b: a schematic diagram of the method of producing a multilayer laminate comprising the layer structure of the invention;

[0251] FIG. 5: a diagram of the transmittance values of two further layers b) from examples 2) and 3) with different proportions of IR absorber in the wavelength range of 200 to 2700 nm.

[0252] FIG. 1 shows a layer structure 10 of the invention in the form of a travel passport, which represents a security document. The layer structure 10 was produced according to example 7. The layer structure 10 includes at least one first layer a) 14 consisting of a polycarbonate, and a further layer b) 12 consisting of a thermoplastic polyurethane. The further layer b) 12 overlaps in the overlap region 17 with the first layer a) 14. In addition, multiple coherent engravings 13, each consisting of a white or almost transparent portion 16 and a black portion 18, are present in the layer structure 10. The white portion of the engraving 16 is in the overlap region 17, and the black portion of the engraving 18 is exclusively on the first layer a) 14. The two portions 16 and 18 of the engraving are joined to one another by a join zone in which the black portion of the engraving, namely the first part-engraving 18, directly adjoins the cloudy or white part of the engraving, the further part-engraving 16.

[0253] FIG. 2 is an enlargement of the middle portion of the layer structure 10 from FIG. 1. The overlap region 17 and the engraving 13 with their part-regions of the further part-engraving 16 on the further layer b) 12 and of the black part-engraving 18 on the first layer a) 14 are readily apparent.

[0254] FIG. 3 shows an attempted forgery on a layer structure of the invention, as shown in FIG. 2, produced according to example 6. It is apparent that the coherent engraving 13 cannot be separated in such a way as to enable re-establishment of the engraving 13 or reading on one of the layers, layer a) 14 or layer b) 12. There is thus no possibility of nondestructive detachment of the further layer b) 12 from the first layer a) 14. From the remaining part-engraving 18, it is possible only with difficulty, if at all, to deduce the information given in the coherent engraving 13 before the further layer b) 12 was pulled away.

[0255] FIG. 4a shows a schematic of the method of producing a layer structure 10 with a join zone. In step I) 20, the first layer a) was provided. In step II) 22, the first layer a) was at least partly covered by the further layer b), and they were laminated together by lamination on a Brkle 50/100 press. The materials of the first layer a) and the further layer b) were compressed at least in the overlap region in the press mentioned at 160 C. for 60 seconds at a pressure of 30 N/cm. Subsequently, the materials were cooled down under a pressure of 50 N/cm.sup.2, down to a temperature of 35 C. Then the laminates were removed from the press. For the laminating, lamination sheets with a nonstick coating were used, in order to prevent the adhesion of the TPU film to the lamination sheet. Lamination sheets from 4-Plate were used, with a nonstick coating from Plascotec. In step III) 24, the engraving was produced by means of a laser both in the overlap region of layers a) and b) to form a join zone and in the portion of the first layer a) not covered by the further layer b).

[0256] FIG. 4b shows a schematic of the method of producing a multilayer laminate. In step i) 30, the layer structure 10 of the invention was provided. In step ii) 32, the layer structure 10 from step i) 30 was laminated at a temperature of 180 C. and a pressure of 100 N/cm.sup.2 in a commercial press, as described above in association with FIG. 4a. In step iii) 34, which is optional, the laminated layer structure 10 from step ii) 32 was folded along a line that runs along the middle of the layer structure 10. In step iv) 36, which is optional, the layer structure 10 from step iii) 34 was pressed between two rolls at a temperature of 250 C. for 5 seconds. Subsequently, the laminate was removed from the press in step v) 38.

[0257] Plotted in FIG. 5 are the transmittance values of the further layers b) from examples 2) and 3) within the wavelength range of 200 to 2700 nm, as measured by the test method as described above. Unexpectedly, there was not a linear but a much more significant decrease in transmittance at the wavelength of 1064 nm, at which the engraving 13 is incorporated into the layer structure 10. Thus, when the IR absorber concentration was doubled, from 0.75% by weight in example 2) to 1.5% by weight in example 3), the decrease in transmittance was not by half but to , namely from 45% to 15%.

[0258] FIG. 6 shows a layer structure 10 of the invention in the form of a travel passport, which represents a security document. The layer structure 10 was produced according to example 10. The layer structure 10 includes at least one first layer a) 14 consisting of a polycarbonate, and a further layer b) 12 consisting of a thermoplastic polyurethane. The first layer a) 14 overlaps in the overlap region 17 with the further layer b) 12. In addition, there are multiple coherent engravings 13 which consist at least partly of a white or almost transparent portion 16 and a black portion 18, partly on the first layer a) 14 and partly on the further layer b) 12. The white portion of the engraving 16 is on the further layer b) 12, and the black portion of the engraving 18 is in the overlap region 17 on the first layer a) 14. The two portions 16 and 18 of the engraving are joined to one another by a join zone in which the black portion of the engraving, namely the first part-engraving 18, directly adjoins the cloudy or white part of the engraving, the further part-engraving 16.