Polymer Laminate Comprising at Least One Diffraction Element and Method for Producing it

Abstract

A production method for a polymer laminate with at least one diffraction element is simplified. The method includes the following method steps: providing a diffraction element material with a carrier film and a light-sensitive layer located thereon, and also at least one polymer layer; producing the at least one diffraction element by creating a light-diffracting layer from the light-sensitive layer, in that a light-diffracting pattern is created in the light-sensitive layer of the at least one diffraction element material; bringing together the at least one diffraction element and at least one polymer layer to form a stack of layers; and surface bonding the at least one diffraction element and the at least one polymer layer 170 by way of a lamination process, thereby forming the polymer laminate.

Claims

1-14. (canceled)

15. A method for producing a polymer laminate, the method comprising the following steps: (a) providing a diffraction element material having a carrier film and a light-sensitive layer on said carrier film, and at least one polymer layer; (b) producing at least one diffraction element by producing a light-diffracting pattern in the light-sensitive layer of the at least one diffraction element material to thereby create a light-diffracting layer from the light-sensitive layer; (c) bringing together the at least one diffraction element and the at least one polymer layer to form a stack of layers; and (d) surface bonding the at least one diffraction element and the at least one polymer layer by a lamination process, to thereby form the polymer laminate with the at least one diffraction element.

16. The method according to claim 15, wherein method step comprises bonding the at least one diffraction element and the at least one polymer layer to each other without using an additional adhesive material.

17. The method according to claim 15, wherein the diffraction element material additionally has a scratch-resistant layer arranged on a side of the light-sensitive layer opposite the carrier film.

18. The method according to claim 17, which comprises, in steps and, retaining the scratch-resistant layer on the light-diffracting layer as a component of the polymer laminate to be produced.

19. The method according to claim 15, wherein step comprises arranging the at least one diffraction element on an outer side of the stack of layers.

20. The method according to claim 19, wherein step comprises arranging the light-diffracting layer on a side of the carrier film of the at least one diffraction element in the stack of layers that is opposite the at least one polymer layer.

21. The method according to claim 19, wherein: step comprises arranging the carrier film on a side of the light-diffracting layer of the at least one diffraction element in the stack of layers that is opposite the at least one polymer layer, and the method further comprises, subsequent to step: embossing microoptical elements in a material of the carrier film.

22. The method according to claim 15, wherein the carrier film is formed with polycarbonate or is composed of polycarbonate.

23. The method according to claim 15, wherein the at least one polymer layer is formed with polycarbonate or is composed of polycarbonate.

24. The method according to claim 15, wherein the at least one polymer layer is one of a plurality of polymer layers and at least one of the polymer layers is formed with polycarbonate or is composed of polycarbonate.

25. The method according to claim 15, wherein the diffraction element material includes a protective film arranged on a side of the light-sensitive layer opposite the carrier film, and the method further comprises, subsequent to step: (b1) peeling of the protective film from the light-sensitive layer.

26. The method according to claim 15, which comprises providing at least one of the polymer layers with data.

27. The method according to claim 26, which comprises applying the data to the at least one of the polymer layers simultaneously with a production of the at least one diffraction element from the diffraction element material.

28. The method according to claim 15, which comprises producing a value or security product.

29. A polymer laminate, comprising: a plurality of polymer layers; and at least one diffraction element bonded to the polymer layers without additional adhesive material.

30. A value or security product, comprising a polymer laminate produced by the method according to claim 15.

Description

[0049] The following figures serve to explain the invention in greater detail, and they are to be understood solely as illustrative examples that do not limit the scope of the invention.

[0050] FIG. 1 shows an ID card in an isometric view;

[0051] FIG. 2 shows a sectional view of the ID card of FIG. 1 along section line A-A;

[0052] FIG. 3 shows successive method steps for the production of a polymer laminate for producing the ID card of FIG. 1 according to a first embodiment of the present invention in sectional views along section line A-A;

[0053] FIG. 4 shows successive method steps in the production of a polymer laminate for producing an ID card according to a second embodiment of the present invention in sectional views.

[0054] The same reference numbers in the figures indicate the same elements or elements having the same function. The drawing elements shown in the figures are not shown to scale or in natural proportions to one another.

[0055] The ID card 200 shown in FIG. 1 is a value or security document. For example, the card has the format ID 1. It has an upper side 201 and an underside 202 (not shown). Provided on the upper side of the card are a first field 210 and a fourth field 240 for a passport photo of the card holder and a second field 220 and a third field 230 for data of the card holder, for example reproduction of the name, birth date and birthplace, the address in plain text and an identification number of the ID card. These data and passport photos thus constitute individualizing, here personalizing, security features. While the passport photo in the first field and the data indicated in alphanumeric form in the second field and the third field are produced in a printing process, for example inkjet printing, the passport photo in the fourth field is formed by a volume hologram.

[0056] The ID card 200 of FIG. 1 is shown in a sectional view along section line A-A in FIG. 2. The ID card contains a polymer layer 170 of PC that is preferably opaque. Printed layers 180 are applied to the polymer layer that reproduce the print images in the first field 210 and in the third field 230. On the polymer layer is a diffraction element 160 in the form of a volume hologram that comprises various components, namely a light-diffracting layer 122, a carrier film 150 of PC and a scratch-resistant layer 130 of PET, wherein these layers have been fused to one another by the preceding laminating process so that the layers can no longer readily be separately recognized. The diffraction element has the same format as the PC layer and therefore covers it completely. In the light-diffracting layer, a light-diffracting pattern 125 is imprinted in the form of a volume hologram in only a limited area. The layers of the diffraction element are preferably transparent or at least translucent so that the print images and the volume hologram are visible from the upper side 201 of the ID card 200. The individual layers and sheets are indicated in the figure by dashed lines. However, these borderlines are only partially visible in a section, specifically only if two different materials having sufficiently differing refractive indices are adjacent to each other. In any event, this is not the case for the polymer layer and the carrier layer. Nevertheless, the printed layers are clearly recognizable because of their absorption in the visible spectral region.

[0057] For producing the ID card 200 according to FIG. 1, 2, a method is used according to the invention in which production of the volume hologram 125 and production of the print images 180 on the polymer layer 170 take place simultaneously. From the polymer laminate 100 produced according to the method, the ID card can be obtained in the form of an individual blank, for example by punching. Optionally, the ID card also comprises further security features to be added subsequently to the polymer laminate in order to produce the ID card.

[0058] The method for producing the polymer laminate 100 according to a first embodiment of the present invention is shown in FIG. 3.

[0059] In a first method step corresponding to method step (a) according to the invention, a diffraction element material 110, here a volume hologram element material, and a polymer layer 170, here a PC layer, are first provided (FIG. 3A). The volume hologram element material is composed of a series of layers (from bottom to top) of a carrier film 150 of PC, a light-sensitive layer 120 of a photopolymer applied thereto, a scratch-resistant layer 130 of PET applied thereto and a protective film 140 of PE that is applied thereto and closes off the series of layers in the drawing in a upward direction. The volume hologram element material can be in a roll format, so that a plurality of volume hologram elements 160 can be produced in the roll. Alternatively, the material can be used in the form of sheet-like pieces, which respectively correspond to individual blanks, for example.

[0060] The volume hologram element material 110 is exposed in a second method step (corresponding to method step (b) according to the claims) to the volume hologram pattern, wherein laser radiation in the visible spectral region VIS (for example in the range of 440 nm to 660 nm) is used (FIG. 3B1). The diffraction pattern produced in the photopolymer is limited to an area in the light-sensitive layer 120 that corresponds to the fourth field 240 on the ID card 200. This gives rise to a light-diffracting layer 122 containing a volume hologram 125. After this, the exposed light-sensitive layer is fixed, wherein the diffraction pattern produced in the material is exposed to UV radiation UV (FIG. 3B2). The result is that the pattern in the material is no longer modifiable. This gives rise to a volume hologram element 160 that comprises the carrier layer 150, the light-diffracting layer 122, the scratch-resistant layer 130 and the protective film 140.

[0061] In parallel to this, the print images 180 are produced on the PC layer 170. For this purpose, the passport picture and the alphanumeric data reproductions are produced in the first field 210, the second field 220 and the third field 230 by means of a printing process. A digital printing process can be used, for example an inkjet printing process. Alternatively, of course, other printing processes such as an offset process are also conceivable.

[0062] After recording of these individualizing data on the PC layer 170 and production of the volume hologram element 160, the protective film 140 on the upper side of the volume hologram element is peeled off (FIG. 3B3).

[0063] After this, the volume hologram element 160, the PC layer 170 and optionally further polymer layers (the latter not shown) are combined into a stack, wherein the PC layer lies against the carrier film 150 of the volume hologram element (FIG. 3C). A stack of layers 190 is produced. If the volume hologram element is a component of a multiple blank, for example in the form of a rolled material, the required individual blanks are cut from the multiple blank. This stack can then be fixed, for example clamped, for simplified handling so that the layers do not slide relative to one another.

[0064] After this, the stack of layers 190 is arranged between two pressing plates P and fed together with the pressing plates into a laminating press (FIG. 3D). There, it is placed between two heatable press rams S. The press rams are configured to heat the stack to an elevated temperature, for example 180° C., and also to exert pressure on the stack, for example 110 N/cm.sup.2. Because of the pressure applied and the elevated temperature, the materials fuse with one another. This causes them to be firmly bonded to one another. The interfaces between the material layers partially disappear. A monolithic bond is produced between the layers. After the hot phase of lamination, a cold phase is carried out in which the pressure is increased further, for example to 450 N/cm.sup.2, but the temperature is reduced to room temperature.

[0065] Finally, the polymer laminate 100 produced in this manner is removed from the laminating press. This polymer laminate is shown in FIG. 3E. In order to produce an ID card 200, the card is cut out of the laminate in a precisely contoured manner, for example by means of a punching, milling or cutting process. Optionally, further security features are added.

[0066] A second embodiment of the method according to the invention for producing a polymer laminate 100 is shown in FIG. 4.

[0067] This method differs from the method according to the first embodiment in that the volume hologram element material 110, for example, contains no scratch-resistant layer. Moreover, the protective film 140 is not peeled from the diffracting layer 122 prior to the lamination step (method step (d)) and therefore remains in the volume hologram element 160. Furthermore, the volume hologram element with the carrier film 150 facing upward is combined with the PC layer 170, i.e., in the stack of layers 190 formed, the PC layer lies against the protective film of the volume hologram element. Moreover, one of the pressing plates P has an embossed structure P.sub.S (elevated structures in this case) that produces an embossed structure 155 (depressions in this case) in the material of the carrier film in the volume hologram element.

[0068] In a first method step, the volume hologram element material 110 and a PC layer 170 are provided (corresponding to method step (a) of the method according to the invention; FIG. 4A). The volume hologram element material is characterized by a protective film 140 of PET, a light-sensitive layer 120 of a photopolymer applied thereto and a carrier film 150 of PC applied thereto.

[0069] After this, the pattern of the volume hologram is created by exposure in the volume hologram element material 110, wherein radiation in the visible spectral region VIS is used (FIG. 4B1). A light-diffracting layer 122 is formed from the light-sensitive layer 120, and a volume hologram element 160 is formed from the volume hologram element material. The volume hologram 125 is produced in the light-diffracting layer. After this, the diffraction pattern produced is fixed in the photopolymer by means of UV radiation UV (FIG. 4B2), corresponding to method step (b) of the method according to the invention.

[0070] In parallel to this, a print image 180 with personalizing data is produced on the PC layer 170.

[0071] After this, the volume hologram element 160, the printed PC layer 170 and optionally further polymer layers (the latter not shown) are combined to form a stack of layers 190 (corresponding to method step (c) of the method according to the invention; FIG. 4C), wherein the carrier film 150 of the volume hologram element is arranged facing upward and the protective film 140 is arranged facing downward towards the PC layer.

[0072] After this, the stack of layers 190 is fed into a laminating press, wherein it is arranged between two pressing plates P and this stack is placed between press rams S of the laminating press. In the laminating press, the stack is heated and placed under pressure, for example 110 N/cm.sup.2, so that the layers of the stack of layers soften and bond to one another (FIG. 4D). This gives rise to the polymer laminate 100 (corresponding to method step (d) of the method according to the invention). The upper of the two pressing plates has a raised structure P.sub.S that is embossed during lamination into the upper outer layer (carrier film 150) of the volume hologram element 160 in the form of depressions 155. In this manner, microoptical elements such as an array of microprisms are produced.

[0073] Finally, the finished polymer laminate 100 is ejected from the laminating press. The polymer laminate can be further processed into an ID card 200 or another value or security product.

[0074] Moreover, reference is made to the description of FIG. 3 with respect to the details of the individual method steps.

REFERENCE SYMBOLS

[0075] 100 Polymer laminate [0076] 110 Diffraction element material, volume hologram element material [0077] 120 Light-sensitive layer [0078] 122 Light-diffracting layer [0079] 125 Light-diffracting pattern, volume hologram [0080] 130 Scratch-resistant layer [0081] 140 Protective film [0082] 150 Carrier film [0083] 155 Embossed structure in polymer laminate, microoptical elements [0084] 160 Diffraction element, volume hologram element [0085] 170 Polymer layer, PC layer [0086] 180 Print image [0087] 190 Stack of layers [0088] 200 ID card, value or security product, value or security document [0089] 201 Upper side [0090] 202 Underside [0091] 210 First field [0092] 220 Second field [0093] 230 Third field [0094] 240 Fourth field [0095] P Pressing plate [0096] P.sub.S Embossed structure on pressing plate [0097] S Press ram [0098] UV Radiation in the UV spectral region [0099] VIS Radiation in the visible spectral region