WO2018010725A1

WO2018010725A1 - Method for producing a layer arrangement for a security document, and security document

Info

Publication number: WO2018010725A1
Application number: PCT/DE2017/100565
Authority: WO
Inventors: Klaus Gradischek; Oliver Muth
Original assignee: Bundesdruckerei Gmbh
Priority date: 2016-07-11
Filing date: 2017-07-07
Publication date: 2018-01-18
Also published as: EP3481642B1; DE102016112672A1; EP3481642A1; EP3481642B2

Abstract

The invention relates to a method for producing a layer arrangement for a security document, having the following steps: provision of a semi-finished product with a layer arrangement (1) with a stack of layers made from plastic material; production of a recess (5) in an outer layer of the layer arrangement (1) with the aid of a processing device; printing of a printed image (2) in the region of the recess (5) by means of a printing device, and production of an inner printed image, wherein a further layer made from plastic material is applied here to the outer layer, in such a way that at least the recess (5) with the printed image (2) is covered by the further layer, and wherein the inner printed image can be viewed from the outside through at least one of the layers from a front side and/or a rear side of the layer arrangement (1). Furthermore, a security document is disclosed.

Description

Method for producing a layer arrangement for a security document and security document

The invention relates to a method for producing a layer arrangement for a security document and a security document.

background

Security documents are known in which layer arrangements are used, wherein in the layer arrangement several layers of plastic material are stacked one above the other, for example by laminating several layers of the same or different plastic films. Such security documents are produced, for example, in the form of a card, for example a plastic card. One example is so-called chip cards or smart cards, in which a chip is integrated in the plastic card.

Document EP 2 307 614 B1 discloses a method for producing a security element with a coating applied on both sides. The security document is, for example, a banknote, a security or a card. When manufacturing the security element, an opening is produced in a substrate, which is closed on one side with an at least partially translucent film.

Document DE 10 2014 000 133 B4 discloses a method for processing a planar, at least single-layer substrate. A window opening in the substrate serves to accommodate electronic components, a chip or the like. The substrate may be formed as a multilayer plastic substrate.

The document WO 98/50883 A1 describes a method for producing a plastic card with a layer structure. In the layer structure, a flat coil and a chip connected to it are embedded.

Document EP 1 719 637 A2 describes a security document with a transparent window in which an ultraviolet light-blocking substance is introduced. Within the transparent window area, invisible ultraviolet fluorescent ink patterns are printed on opposite sides of the ultraviolet light blocking material. When either the front or the back of the security document is irradiated with ultraviolet light, only the pattern printed on that side within the transparent window area becomes visible. If the front and back are the same are exposed to ultraviolet light at the same time, the pattern printed on both sides of the ultraviolet blocking substance within the transparent window area becomes visible at the same time. From the document DE 10 2012 209 665 A1 a method for individualizing a security document is known in which a document blank comprising a lamination body and a digital printing device are provided. At least one outer surface of the lamination body is printed by means of the digital printing device by means of at least one preparation for introducing customization information into the laminae body. In this case, the document blank is provided with a lamination body which, at least in an individualization area, has a plurality of perforations penetrating the outer material layer as far as an information layer in an outer material layer adjoining the at least one outer surface. The individualization information is printed on the outer surface such that at least part of the individualization information is printed through the perforation openings onto the information layer.

Document EP 2 559 563 A1 discloses a method for producing a security document. Transparent external layers and at least one semitransparent internal layer having a see-through area that is more transparent than the largest remainder of the document are provided. The layers are laminated to form the security document and, before and / or after lamination of the layers, personalized data and a see-through security feature are applied to the document in the see-through area. The see-through feature comprises a first sub-image applied to one side of the at least one semitransparent internal layer and a second sub-image applied to the other side of the at least one semitransparent internal layer. The first and second field form a complete picture when viewed in the through-light. Prior to applying the see-through security feature, personal data is obtained for the security document and the complete image for the see-through security feature. The complete image is divided into the first field and the second field using a function that has a value that depends on at least a portion of the personalized data for the security document.

An overview of various printing processes can be found in the lecture Printing or Coating: Organic Electronics Saxony - Workshop (U. Herzau-Gerhardt, 20.03.2013,

Summary

The object of the invention is to specify improved technologies for producing a layer arrangement for a security document and a security document with which an individualization of the security document can be efficiently provided, for example for personalization, in a manner suitable also for mass production.

To solve this, a method for producing a layer arrangement for a security document and a security document according to independent claims 1 and 15 are provided. Alternative embodiments are the subject of dependent claims.

In one aspect, there is provided a method of making a laminate for a security document in which a semifinished product having a laminate with a stack of layers of plastic material is provided. In an outer layer of the layer arrangement, a recess is produced by means of a processing device. In the region of the recess, a printed image is printed by means of a printing device. An inner printed image is produced, in which case a further layer of plastic material is applied to the outer layer, such that at least the recess with the printed image is covered by the further layer. The inner printed image can be viewed from the outside through at least one of the layers from the front and / or back of the layer arrangement.

According to a further aspect, a security document is provided with a layer arrangement which has an internal printed image which can be viewed from the outside through at least one of the front and / or back sides of the layer arrangement.

The security document may be, for example, a passport or other identity document, for example a plastic or plastic card. Alternatively, the layer arrangement can be integrated into a passport or security document of another type.

Provided with the internal printed image is a printed image embedded in the layer arrangement, which is integrated into the layer arrangement with the stack of layers of synthetic material and can be viewed from the outside, for example by means of transparent film sections of the layers overlapping with the printed image. The layers in the flat stack of the semifinished product may consist of one or more different plastic materials. It can be provided that one or more layers are formed from a plastic film.

The stack of layers of the semifinished product can be designed as a stack of superimposed layers, which are secured against relative movement to one another, in particular a sliding, for example by means of stapling and / or staples. A portion of the layers or all layers of the stack of semifinished product may be laminated. The lamination takes place, for example, in a hot pressing process known in the manufacture of security documents, in which thermoplastics are pressed together at elevated temperatures, so that a monoblock is formed. However, the joining of the stacked layers can also take place by means of the use of adhesive and / or by means of plastic welding.

The recess may be at least partially made as a breakthrough in the outer layer, wherein the printed image can then be printed on an underlying layer. The print image may be printed in whole or in part on the underlying layer. The printed image may be partially printed on the underlying layer and partly on the outer layer in the region of the recess. The breakthrough may extend through multiple layers.

The recess may be at least partially made as a recess in the outer layer, wherein the printed image can be printed in the region of the recess. The printed image can be partially or completely produced in the recess of the outer layer by means of printing. In contrast to the breakthrough, the outer layer is not continuously removed during the production of the depression. The recess can be produced by means of mechanical processing in the outer layer. Mechanical processing can be carried out, for example, by means of milling, lifting and / or engraving. Alternatively or additionally, a stamper can be used with an engraving to produce the recess. The recess can be produced by means of laser processing in the outer layer. The laser processing can be combined with the mechanical machining to produce the recess. The printed image can be printed at least in sections to capture a recess edge surrounding the recess. In this embodiment, the material used to produce the printed image, for example a printing ink, is partly also printed on the recessed edge surrounding the recess. As a result, in one embodiment, an image defect in the print image that can be recognized by means of an optical read-out device and / or with the naked eye can be produced.

The recess edge surrounding the recess can be made at least partially with sloping walls. The print image can be made with a print layer thickness that is less than a height of the recess. The layer thickness of the printed image may be substantially equal to the height of the recess. In an alternative embodiment, the printed layer thickness is higher than the height of the recess. In these or other embodiments, the printed image may completely or partially cover the surface of the recess.

The recess edge surrounding the recess can be produced at least in sections following an outer print image contour. The recess edge follows in terms of its course in this case at least partially the outer contour of the printed image, wherein the outer edge of the printed image and the recess edge can abut each other. Alternatively, the two edges may be spaced apart.

The printed image can be produced with image security points that individualize a security document. The image doorstep locations can be evaluated with the aid of an optical reading device, for example with the aid of a camera and a downstream digital image analysis. It can be provided that the image disturbance sites individualizing the security document are visible to the naked eye. The image defects can be persons identifying, for example by the fact that when read with the aid of an optical read-out device, the image disturbances determined here can be assigned to a person-related data record. The image defects may extend in the various embodiments over a partial area of the printed image or over the entire printed image. In the region of the recess, the security document can be produced in the layer arrangement of individualizing defects that are associated with the image defects. The defects in the region of the recess can be produced by means of mechanical processing and / or laser processing. For example, the impurities can be produced as surface-side depressions in the region of the recess. In this way, in one embodiment associated image defects arise when the printed image is printed, for example, the fact that the impurities in the outer layer and / or an underlying layer of the layer arrangement lead to a different course of the printed substrate than outside the interference parts. In this embodiment, the image defects can arise automatically due to the previously produced defects or defects in the region of the recess in the layer material. The image defects associated with the defects can be designed in accordance with their course and / or their shape of the defects. The impurities may be formed on a surface of the outer layer and / or on the surface of an underlying layer. The layer of the layer arrangement in which the defects are produced can consist of an opaque layer material. An electronic storage medium may be incorporated in the layer arrangement and the electronic storage medium may be stored with readable electronic data indicating information about the image staging areas and / or the impurities. The electronic data may, for example, indicate by machine and / or with the naked eye readable properties of the defects and / or the image defects, for example a profile. If the layer arrangement is integrated into a security document, the electronic data can be read from the storage medium when the security document is read out, for example from the chip of a chip card. Furthermore, the printed image can be optically read out, whereupon the image defects are determined. Afterwards, the electronic data read out and the specific image defects can be compared in order to carry out an examination of the security document. As an alternative to introducing the storage medium during production of the layer arrangement, provision can be made for the electrical storage medium to be introduced during the further processing of the layer arrangement for producing a security document. The storage of the electronic data can, for example, be carried out as part of a personalization of the security document. The method can provide the following steps: generation of electronic processing data by means of a data processing device, whereby personal data and / or non-personal data are processed and a security document individualizing the arrangement of the impurities are determined; Transferring the electronic processing data to the processing device; and producing the impurities according to the security document individualizing arrangement by means of the processing device. When the electronic processing data are generated, by means of determining the arrangement of the defects, a coding of the personal and / or non-personal data can be carried out by determining the arrangement of the defects which individualizes the security document in dependence on this data. The personal and / or non-personal data can thus be converted into an individualizing arrangement of impurities. This arrangement is then manufactured by means of the processing device in the layer arrangement. The defects can lead to associated image defects when applying the printed image. In this way, the individualizing arrangement of the defects can be converted into an associated arrangement of image defects. Supplementary picture defects may be provided which are not related to an associated defect. Such additional image defects can be produced as part of the printing of the printed image. The electronic processing data and / or electronic data obtained therefrom can be stored in the storage medium. Alternatively or additionally, the method can provide the following steps: generation of electronic print data by means of the data processing device, in which case the personal and / or non-personal data are processed and a training of the image disturbances that individualises the security document is determined; Transmitting the electronic print data to the printing device; and producing the image defects according to the security document individualizing arrangement when printing by means of the processing device. The personal and / or the non-personal data determine the security document individualizing training of Bildstörstellen, so that the data are encoded in an arrangement and form of the Bildstörstellen. Image interference parts can be produced, for example, by means of a higher or a lower print material output, a changed color and / or the use of different print patterns in the region of the defects when applying the print image. This may relate to the overlap region with and / or regions outside the previously produced impurities. The layer arrangement produced in accordance with the alternative embodiments may be subjected to further processing in order to produce a security document. spielswiese a plastic or plastic card, either with or without a chip. Technologies for integrating the layer arrangement into such a card or other security document are known as such in various embodiments. The layer arrangement can hereby be supplemented, for example, on the front and / or the back by one or more further layers, for example by means of lamination of plastic material layers.

In the following, further embodiments will be explained with reference to figures of a drawing. Hereby show:

Fig. 1 is a schematic representation for producing a layer structure with a printed image for a plastic card;

FIG. 2 shows a schematic illustration of an alternative method for producing a layer structure with a printed image for a plastic card; FIG.

Fig. 3 is a schematic representation of another alternative method for Hersteh len a layer structure with a printed image for a plastic card;

4 shows a schematic illustration of a plastic card, in which a viewing window is provided in a card body, which is formed as a layer structure;

5 shows a schematic representation of a plastic card in which a viewing window is provided in a card body, which is formed as a layer structure, wherein herein a print image is surrounded by an edge which follows an outer contour of the print image;

6 shows a schematic illustration of a further plastic card in which image defects of a contour are formed following in the region of the printed image;

Fig. 7 is a schematic representation of an arrangement with parts of an apparatus for producing a plastic card and

8 shows a schematic representation of a plastic card which has a chip in addition to the printed image on the inside.

1 shows a schematic representation of a method for producing a layer structure 1 with a printed image 2 for a security document, for example a plastic card. The layer structure is provided in the embodiment shown in a simple embodiment with layers 3, 4. These are layers, each made of a plastic material. The layer structure 1 can be provided as a separate sheet or as an endless material from the roll for further processing. the. As part of the further processing, a recess 5 is produced in the layer 3 by removing the layer 3 in the region of the recess 5. Mechanical or non-mechanical methods can be used to produce the recess 5, in particular micro-milling, micro-planing, micro-engraving and / or laser-machining. In particular, when using the mechanical processing methods such as micro-milling or micro-planing side walls 6, 7 of the recess 5 can be formed as inclined wall sections, which is shown in Fig. 1. Alternatively, the side walls 6, 7 may be formed substantially upright on the layer 4. Subsequently, in the region of the recess 5 on the layer 4, a printed image 2 is applied by means of a printing process. For example, an inkjet printing process can be used. In this way, an existing printed image is generated in the recess 5. The height of the applied printing material (ink) may be less than 20 pm. The height of the printed image 2 may be less than or approximately equal to the layer thickness of the layer 3. In one embodiment, the layer 3 is an opaque layer. The layer 4 can be formed as a transparent or opaque layer, wherein the print image 2 can be viewed through the layer 4 in the case of transparent formation.

The print image 2 can detect the recess 5 in its entire width or in parts, which is shown in Fig. 1, where the print image 2 is surrounded by an edge 8, a portion of the recess 5, which is not printed.

The layer structure 1 produced in this way can then be supplied to the further processing for producing a plastic card. In this case, at least one further layer is laminated on the cover side 9 of the layer structure 1, so that the printed image 2 is covered. Further lamination steps can be provided to finally produce the plastic card with an integrated or internal printed image, which can be viewed from one or both sides of the plastic card through transparent layers. Fig. 2 shows a schematic representation of an alternative method for producing a layer structure for a plastic card. For the same features, the same reference numerals as in FIG. 1 are used in FIG.

During or after the production of the recess 5, in the method according to FIG. 2 in the region of the recess 5 on a surface 10 of the layer 4 desired or fault points 11, 12 are generated, which in the illustrated embodiment are recesses are formed, for example, may have a V-shape in cross section. The desired doorsteps 11, 12 can be produced by mechanical (machining, in particular by micro-milling and / or micro-planing) Alternatively or additionally, micro-engraving and / or laser machining can be used.

During the subsequent application of the printed image 2, image defect or image defects 13, 14 of the printed image 2 are formed in the region of the desired defects 11, 12. For example, the applied ink can accumulate in the region of desired defects 11, 12 with a higher layer thickness during printing, resulting in a shadow contour within of the printed image can lead. In this way, the printed image 2 is provided with additional counterfeit-proof features, which can be visible to the naked eye. Alternatively or additionally, an evaluation of the printed image 2 can be provided by means of optical measurement. FIG. 3 shows a schematic representation of a further alternative method of a layer construction 1 for a plastic card. For the same features in Fig. 3, the same reference numerals as in Figs. 1 and 2 are used.

In contrast to the method from FIG. 2, in the embodiment in FIG. 3 the set points 11, 12 are produced in the layer 4, without the recess 5 (see FIGS. 1 and 2) being produced beforehand. Scanning over the area of the desired defects 11, 12, the printed image 2 is applied to the layer 4, so that the image defects 13, 14 are produced in the printed image 2. The print image 2 can be printed, for example, as a print grid. The image defects 13, 14 in the printed image 2 can in this case arise in particular from the fact that the ink of printed halftone dots in the region of side walls 15, 16 of the desired defects 11, 12 runs due to the oblique formation, in contrast to the ink of halftone dots on the horizontal surface the layer 4.

In the exemplary embodiment according to FIG. 3, the layer structure 1 can then be supplied to the further process of the plastic card in order to laminate one or more layers, whereby a plastic card with integrated or internal printed image is produced. For the further manufacturing process, various process designs are known as such, which is why they need not be explained further here. One or more transparent layers of plastic material can be laminated, through which the printed image 2 can be viewed. One or more opaque layers can be integrated, through which an underlying image is not visible, and then in the opaque layer optionally a recess is incorporated as a window to allow the visibility of the printed image 2. Various layer structures with transparent and opaque layers can be provided, wherein the inner printed image 2 of at least one flat side of the plastic card can be viewed through one or more transparent layers.

4 shows a schematic representation of a plastic card 40, in which a viewing window 42 is provided in a card body 41, which is formed as a layer structure, in which the printed image 2 can be seen. The printed image 2 is surrounded by the edge 43 in the embodiment shown. The edge 43 may be formed following an outer contour 44 of the printed image 2, which is shown schematically in FIG. 5. For this purpose, the recess 5 was produced in accordance with the manufacture of the layer structure 1.

FIG. 6 shows a schematic representation of a further plastic card 60, in which the image defects 61 are formed in the region of the printed image 2.

On the security document, in particular the plastic card, a representation of the formation of the image defects can additionally be printed, for example in the form of a line representation for the course of the image defects or as a reference image. In this way, for example, any contours or symbols can be introduced as impurities in the printed image, which are shown on the plastic card for comparison, which supports an authenticity check in a simple and efficient manner. 6 shows this by way of example for the image defects 61 in the case of the further plastic card 60 (see the card at the bottom left). For the production of the layer structure 1 in its various embodiments for the subsequent further processing for producing the plastic card, a device can be provided, for which device parts in FIG. 7 are shown schematically. In the apparatus of FIG. 7, a raster image processor 70 provides rendered digital data including control data for both a printing system 71 for printing the print image 2 and processing systems 72, 73 for forming the layer structure 1 when fabricating the layer structure 1 Recess 5 and / or the desired interference points 11, 12 produce, in particular by means of laser processing and / or mechanical processing. The raster image processor 70 is also referred to as a pixel area calculator. Usually, the raster image processor 70 is used to prepare data from the pre-press for an imagesetter or a printer so that it can produce the printed image 2 determined by means of a layout page. Here, raster image processor 70 receives certain data for printing, which is obtained by means of a screen. stored description texts such as Postscript, and repositioned all presented components, in order to then translate them into a grid of grid points. An imageable bitmap can be created here. The data thus generated in the raster image processor 70 can be supplied as raster data via a database 74a to the printing system 71, which generates the printed image 2 during production of the layer structure 1.

In addition, the raster data provided by the raster image processor 70 are processed as processing data via a further database 74b in a respective control device 75, 76 for the processing devices 72, 73 and converted into corresponding control signals. This is done by providing and passing one or more data files. It can be provided that the processing devices 72, 73 serve a mechanical processing (milling, planing) and / or laser processing. Due to the processing of the raster data both for the control of the printing system 71 as well as the control of the processing device 72, 73, a highest precision in the production of the recess 5 and / or the target fault points 11, 12 on the one hand in the manufacture of the layer structure 1 and the subsequent application of the printed image 2 can be ensured in the area on the other hand. The raster data provided by the raster image processor 70 may be processed to generate the raster data 74a and the processing data 74b at different resolutions. The processing data 74b can be provided to the processing systems 72, 73 in a respectively adapted format, for example in a "CNC language" that can be processed by the mechanical processing devices (milling, planing) per se for the laser ("spot size, intensity") as well as coordinates for a mirror system of the laser.

FIG. 8 shows a schematic representation of a plastic card 80, which has a chip 81 in addition to the inner printed image 2. In accordance with the structure of a conventional chip card, the chip 81 can be described with electronic data during the production of the plastic card 80, which can be read out by a suitable reading device, as is known in various embodiments as such. The entry of such electronic data into the chip 81 can take place as part of a personalization. It can be provided that the electronic data which are stored on the chip 81 comprise defect data which contains information concerning the desired defect sites 11, 12 and / or the Bildstörstellen 13, 14 in the print image 2 show. For example, the contour (line shape and / or image contour) can be displayed by the defect data.

As part of an authenticity check for the plastic card 80, the fault or fault location data can be read out by means of the card reader and displayed to the user of the card reader via a display, so that the user compares the displayed information with the image disturbance of the smart card 80 visible to the naked eye can. Alternatively or additionally, it can be provided that the inner printed image 2 with the image defects is scanned in with the aid of a scanning device and the image defects are determined in the scan image in order to compare them with the defect data stored in the chip 81. This can be carried out with the aid of a test device which has the scanning device and the card reader, for example a chip card reader, as separate or integrated functional units. Depending on the result of the comparison, the user can be informed by means of optical and / or acoustic output of the result of the authenticity check. Test devices that are set up to scan plastic cards with a chip and to read out electronic data from the chip of the plastic card are known as such in various embodiments, for example as a test terminal.

The features disclosed in the above description, the claims and the drawings may be important both individually and in any combination for the realization of the various embodiments.

Bezuaszeichenliste

1 layer structure

2 print image

3, 4 layers

5 recess

6, 7 side walls

8 print image 2 surrounding edge

9 cover page

10 surface

11, 12 target defects in layer

13, 14 picture glitches

15, 16 side walls

40 plastic card

41 card bodies

42 viewing window

43 edge

44 outer contour

60 more plastic card

61 picture glitches

70 raster image processor

71 printing system

72, 73 processing systems

74a database

74b further database

75.76 respective control device

80 chip card

81 chip

Claims

Claims 1. Method for producing a layer arrangement for a security document, with the following steps:

- Providing a semifinished product with a layer arrangement (1) with a stack of layers of plastic material;

- Producing a recess (5) in an outer layer of the layer assembly (1) by means of E3earbeitungseinrichtung;

- Printing a printed image (2) in the region of the recess (5) by means of a pressure device and

- Producing an internal printed image, wherein in this case a further layer of plastic material is applied to the outer layer, such that at least the recess (5) with the printed image (2) is covered by the further layer, and wherein the inner printed image of a front and / or a back of the layer assembly (1) through at least one of the layers is visible from the outside bar.

2. The method according to claim 1, characterized in that the recess (5) is at least partially produced as a breakthrough in the outer layer and the printed image (2) is printed on an underlying layer.

3. The method according to claim 1 or 2, characterized in that the recess (5) is at least partially produced as a recess in the outer layer and the printed image (2) is printed in the region of the depression.

4. The method according to at least one of the preceding claims, characterized in that the recess (5) is produced by means of mechanical processing in the outer layer.

5. The method according to at least one of the preceding claims, characterized in that the recess (5) is produced by means of laser processing in the outer layer.

6. The method according to at least one of the preceding claims, characterized in that the printed image (2) surrounding the recess Ausnehmungs- edge is printed at least partially detecting.

7. The method according to at least one of the preceding claims, characterized in that the recess (5) surrounding the recess edge is at least partially cut with wall bevels.

8. Method according to claim 1, characterized in that the printed image (2) is produced with a print layer thickness which is less than a height of the cutout.

9. The method according to at least one of the preceding claims, characterized in that the recesses (5) surrounding the recess edge is at least partially produced following an outer print image contour.

10. The method according to at least one of the preceding claims, characterized in that the printed image (2) with a security document individualizing image fault locations (13, 14) is produced.

11. The method according to claim 10, characterized in that in the region of the recess in the layer arrangement the security document individualizing impurity (11,12) are produced, which are associated with the Bildstürstellen (13, 14). 12. The method according to claim 9 or 10, characterized in that in the layer arrangement, an electronic storage medium (81) is stored and in the electronic storage medium readable electronic data are stored, the information on the Bildstürstellen (13, 14 ) and / or the impurities (11,

12).

13. The method according to claim 11 or 12, characterized by the following steps:

- Generation of electronic processing data by means of a data processing device, in which case personal and / or non-personal data and an arrangement of the defects (11, 12) which individualises the security document is determined;

- Transferring the electronic processing data to the processing device; and

- Producing the impurities (11, 12) according to the security document individualisieren- the arrangement by means of the processing device.

14. The method according to at least one of the preceding claims, as far as dependent on claim 10, g e ke nze c h n et by the following steps:

Generating electronic print data by means of the data processing device, wherein the personal and / or the non-personal data are processed and a design of the picture door stops (13, 14) individualizing the security document is determined;

- transferring the electronic print data to the printing device; and

- Produce the Bildstörstellen (13, 14) according to the security document individualisie- ing arrangement when printing by means of the processing device.

15. A security document with a layer arrangement which is produced according to at least one of the preceding claims and has an internal printed image which can be viewed from the outside through at least one of the front and / or back sides of the layer arrangement.