EP2753754B1 - Method for producing a security paper and microlens thread - Google Patents

Description

The invention relates to a method for producing a security paper, as well as a microlens thread for introduction into a paper web with such a method.

Security documents, such as banknotes, stocks, bonds, certificates, vouchers, checks, high-quality admission tickets, but also other forgery-prone papers, such as passports or other identity documents, are often provided with security elements for security, which allow a verification of the authenticity of the value document and at the same time serve as protection against unauthorized reproduction. The security elements can be designed, for example, in the form of a security thread completely or partially embedded in a banknote.

In recent years, microlens security threads have become established on the banknote market. These microlens filaments differ significantly from metallized filaments and offer attractive optical properties. On the side facing the observer, the microlens threads are equipped with microlenses whose focusing effect is produced by refraction of light on an approximately spherically curved surface. In the focal plane of the microlenses there are microstructures which are arranged so that the interaction of the microlenses and the microstructures allows the viewer to display an enlarged image with special motion effects.

In order not to affect the focusing effect of the microlenses and thus the optical effect of the microlens thread, the lens side of the thread is not provided with adhesive prior to embedding in a paper web, as with conventional security threads, such as hologram threads the case is. However, dispensing with adhesive on the top of the thread (lens side) often results in reduced durability of the produced banknotes and in part even wrinkling on the banknotes back.

Based on this, the present invention seeks to avoid the disadvantages of the prior art and in particular to provide a method for producing a security paper, which allows a secure embedding of a microlens thread in the paper and at the same time in the window areas in which the microlens thread on the Surface of the paper, ensuring an attractive visual appearance of the microlens thread.

This object is solved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

• M) ein endloser Mikrolinsenfaden bereitgestellt wird, der eine Oberseite und eine gegenüberliegende Unterseite aufweist, wobei die Oberseite zumindest in Teilbereichen mit Mikrolinsen versehen ist,
• P) eine Papierbahn mit einem vorbestimmten Stegmuster erzeugt wird, welches Stegbereiche aufweist, in denen der Mikrolinsenfaden im Inneren der Papierbahn eingebettet ist, und das zwischen den Stegbereichen liegende Fensterbereiche aufweist, in denen der Mikrolinsenfaden an der Oberfläche der Papierbahn hervortritt, und
• E) der Mikrolinsenfaden in die Papierbahn eingebracht und dabei auf seiner Unterseite und in den Stegbereichen auch auf seiner Oberseite mit der Papierbahn verbunden wird, wobei die Papierbahn mit dem eingebrachten Mikrolinsenfaden das Sicherheitspapier bildet.

According to the invention, it is provided in a generic method that

• M) an endless microlens thread is provided, which has an upper side and an opposite lower side, wherein the upper side is provided with microlenses at least in partial areas,
• P) a paper web having a predetermined web pattern is produced, which has land regions in which the microlens thread is embedded in the interior of the paper web, and which has window regions lying between the web regions, in which the microlens thread protrudes on the surface of the paper web, and
• E) the microlens thread is introduced into the paper web and in this case is also joined on its underside and in the web areas on its upper side to the paper web, wherein the paper web forms the security paper with the introduced microlens thread.

• der Mikrolinsenfaden vor der Einbringung in die Papierbahn auf seiner Oberseite mit einer Klebstoffschicht in Gestalt des Stegmusters versehen wird, und
• der Mikrolinsenfaden in Schritt E) registriert in die Papierbahn eingebracht wird, so dass die mit Klebstoff beschichteten Bereiche des Mikrolinsenfadens mit den Stegbereichen der Papierbahn zusammenfallen.

In a preferred variant of the method it is provided that

• the microlens thread is provided on its upper side with an adhesive layer in the form of the web pattern prior to introduction into the paper web, and
• the microlens thread in step E) is registered in the paper web, so that the adhesive-coated areas of the microlens thread coincide with the web areas of the paper web.

A registered introduction of the microlens thread can in particular according to one of the in the document WO 2004/050991 A1 described method. The disclosure of this document is included in the present application in this respect.

In some designs, the microlens thread may include a motif with a motif jump. As in the publication WO 2008/145333 A2 described in more detail, in the production of a microlens thread usually first an endless security element film is produced as a roll material, which always occur when using conventional manufacturing methods break points, especially gaps or an offset in the appearance of the security elements. These fractures are due to the fact that the precursors for the embossing tools used in the production in general are produced as flat plates, which are mounted on a printing or embossing cylinder. At the seams, the mutually adjacent image patterns usually do not match and lead after printing or embossing in the appearance of the finished security elements to a scene jump of the type mentioned. According to an advantageous embodiment of the invention, a microlens thread containing a motif with a motif jump , Registered registered in the paper web, so that the motif jump comes to rest in one of the web areas of the paper web. The subject jump then remains hidden from the viewer.

Under certain circumstances, subject jumps occur several times within an embossing cylinder. For example, if the patterns are composed by recombination of small segments, stitches with motif jumps result. In general, motive jumps occur due to the process both in the grid of the microstructures and in the grid of the microlenses. Usually, attempts are made to bring the two seams in the production in coverage, so that arises for the viewer the impression of only one jump in the subject.

In a modification of the method described, the microlens thread is printed directly before entering the paper web targeted in the areas of its upper side with an adhesive layer, which come to lie in the sheet formation below land areas of the paper web.

• der Mikrolinsenfaden vor der Einbringung in die Papierbahn in einem Öffnungsbereich in Gestalt des Stegmusters mit einer Mehrzahl von Öffnungen versehen wird, und
• der Mikrolinsenfaden in Schritt E) registriert in die Papierbahn eingebracht wird, so dass die mit Öffnungen versehenen Bereiche des Mikrolinsenfadens mit den Stegbereichen der Papierbahn zusammenfallen.

In a further preferred variant of the method it is provided that

• the microlens thread is provided with a plurality of openings before being introduced into the paper web in an opening region in the form of the web pattern, and
• the microlens filament in step E) is registered in the paper web, so that the apertured areas of the microlens filament coincide with the web areas of the paper web.

In this variant, too, the microlens thread can contain a motif with a motif jump and the microlens thread can be registered, so that the motif jump comes to rest in one of the web areas of the paper web and is therefore hidden from the viewer.

According to a modification of the method, the microlens thread is provided in the areas of its upper side with openings, which come to rest below the land areas of the paper web during sheet formation, immediately before entering the paper web.

The openings are advantageously produced by punching or laser cutting. If the openings are only produced immediately before the microlens thread enters the paper web, they are preferably produced by laser cutting.

In all configurations, the paper web is expediently formed with the predetermined web pattern in a paper machine and the endless microlens thread runs into the paper machine.

According to a further preferred variant of the method, it is provided that in step M) a microlens thread is provided whose upper side has partial areas with microlenses and microlens-free partial areas, the microlens-free partial areas being smaller than the width of the bridge areas of the Web pattern are in the paper web, and wherein the microlens-free portions are coated prior to introduction into the paper web with adhesive. In particular, the microlens thread is introduced into the paper web in an unregistered manner so that microlenses can be seen at least in certain areas in each window region and a portion of the adhesive-coated subregions always come to lie below land areas of the paper web.

According to a further preferred variant of the method, it is provided that in step M) a microlens thread is provided which on the one hand has partial regions with microlenses, which partial regions are coated with adhesive before being introduced into the paper web and which are smaller than the width of the web regions of the web pattern in the paper web on the other hand, have partial areas with microlenses which are not coated with adhesive before being introduced into the paper web. The microlens thread is introduced in particular unregistered in the paper web, so that in each window area at least partially microlenses that have no adhesive coating, can be seen and always come to lie part of the adhesive-coated portions below web portions of the paper web.

In all described variants of the method, the microlens thread is advantageously provided over its entire surface with an adhesive layer on its underside prior to introduction into the paper web.

The invention also includes a microlens thread for insertion into a paper web, in particular with the method just described. The microlens thread includes a top and an opposite bottom, the top having microlens sections and microlens-free sections coated with adhesive.

The microlens sections and the microlens-free sections advantageously form alternating strips on the upper side of the thread, each of which completely occupies the width of the microlens thread and in each case has an extension of between 1 mm and 30 mm, preferably between 3 mm and 12, in the longitudinal direction of the microlens thread mm have.

The microlens sections and the microlens-free sections may usually be in the form of rectangles. However, it would also be possible for the partial areas with microlenses and the microlens-free partial areas to be present in the form of diagonals. It can be made especially for wider threads diagonal paper webs.

The underside of the microlens thread is preferably coated over the entire surface with adhesive.

Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, in the representation of which a representation true to scale and proportion has been dispensed with in order to increase the clarity.

Fig.1

eine schematische Darstellung einer erfindungsgemäß hergestellten Banknote mit einem eingebetteten Mikrolinsenfaden,

Fig. 2

schematisch den Schichtaufbau eines Mikrolinsenfadens vor der Einbettung in das Sicherheitspapier,

Fig. 3

einen Querschnitt eines Sicherheitspapiers mit einem eingebetteten Mikrolinsenfaden nach Fig. 2,

Fig. 4

eine Aufsicht auf den Mikrolinsenfaden der Fig. 2,

Fig. 5

eine Aufsicht auf einen weiteren Mikrolinsenfaden vor der Einbettung in ein Sicherheitspapier,

Fig. 6

einen Querschnitt des Mikrolinsenfadens der Fig. 5,

Fig. 7

einen Querschnitt eines Sicherheitspapiers mit einem eingebetteten Mikrolinsenfaden nach den Figuren 5 und 6,

Fig. 8

einen Querschnitt des erfindungsgemäßen Mikrolinsenfadens; und

Fig. 9

einen Querschnitt eines Sicherheitspapiers mit einem eingebetteten Mikrolinsenfaden nach Fig. 8.

Show it:

Fig.1

a schematic representation of a banknote according to the invention with an embedded microlens thread,

Fig. 2

schematically the layer structure of a microlens thread before embedding in the security paper,

Fig. 3

a cross section of a security paper with an embedded microlens thread after Fig. 2 .

Fig. 4

a top view of the microlens thread the Fig. 2 .

Fig. 5

a view of another microlens thread before embedding in a security paper,

Fig. 6

a cross section of the microlens thread of Fig. 5 .

Fig. 7

a cross section of a security paper with an embedded microlens thread after the FIGS. 5 and 6 .

Fig. 8

a cross section of the microlens thread according to the invention; and

Fig. 9

a cross section of a security paper with an embedded microlens thread after Fig. 8 ,

The invention will now be explained using the example of a banknote. FIG. 1 shows a schematic representation of a banknote 10 according to the invention with a micro-optical window security thread 12, which is also referred to below as a microlens thread. The microlens thread 12 emerges in window areas 14 on the surface of the banknote 10, while it is embedded in the interposed web areas 16 in the interior of the banknote 10.

In a first embodiment of the invention is for the production of a security paper in the Figures 2 and 4 illustrated microlens thread 12 used. FIG. 3 shows a cross section of the security paper 50 with the already embedded microlens thread 12. In the production of security paper, the microlens thread runs, for example, in an endless form in a paper machine and is embedded there in a forming on a round screen paper web. The paper web together with the embedded microlens thread is referred to in this specification as security paper. From such a security paper arises after further processing steps and separation of the benefits of a paper web or a paper sheet banknote 10 as in Fig. 1 shown.

FIG. 2 shows schematically the layer structure of the microlens thread 12 before embedding in the security paper, wherein only the parts of the layer structure required for the explanation of the principle of operation are shown. FIG. 4 shows a plan view of the microlens thread 12 of Fig. 2 ,

The microlens thread 12 contains a carrier 20 in the form of a transparent plastic film, for example an approximately 20 μm thick PET film. The upper side 30 of the microlens thread 12 has a grid-like arrangement of microlenses 22 which form a grid with a preselected symmetry on the surface of the carrier foil. The spherically or aspherically configured microlenses 22 preferably have a diameter between 5 μm and 50 μm and in particular a diameter between only 10 μm and 35 μm and are therefore not visible to the naked eye. It is understood that in other designs also larger or smaller Dimensions come into question. The use of cylindrical lenses is possible in the same way.

On the underside 32 of the microlens thread 12, a motif layer 26 is arranged which contains a likewise grid-shaped arrangement of micromotif elements 28. The arrangement of the micromotif elements 28 also forms a lattice with a preselected symmetry, wherein the matching of the lattice of the microlenses 22 and the arrangement of the micromotif elements 28 produces a desired magnification effect, characteristic movement effects and / or tilting effects. The micromotif elements are invisible to the naked eye. At this point, in addition to the WO 2009/000528 A1 in which it is stated that the microstructures may also consist of image fragments which are not arranged repetitively. The microlens thread 12 typically includes other layers 24, such as protective, masking or other functional layers, which are not essential to the present invention and therefore will not be described further.

Due to the production with embossing cylinders, the motif perceived by the viewer usually has a motif jump, as in the publication WO 2008/145333 A2 described in more detail.

To produce a security paper, a paper web 50 with a predetermined web pattern 18 (FIG. Fig.1 ) generated. The web pattern 18 has land areas 16 in which the microlens thread 12 is later embedded in the interior of the finished paper web 50. Between the web regions 16 are window regions 14 in which the microlens thread 12 emerges on the surface of the finished paper web 50.

As in the Figures 2 and 4 shown schematically, the microlens thread 12 is provided prior to introduction into the paper web 50 on its upper side 30 with an adhesive layer 40 in the form of the web pattern 18, so that the adhesive layer 40 forms an adhesive pattern 48, the sequence of uncoated areas 44 and coated areas 46 of Sequence of the window areas 14 and web portions 16 of the web pattern 18 corresponds. The underside 32 of the microlens thread 12 is provided with a full-surface adhesive layer 42.

The microlens thread 12 thus coated with adhesive 40, 42 is registered in the paper web 50, so that the adhesive-coated regions 46 of the microlens thread coincide with the web regions 16 of the paper web 50, as in FIG Fig. 3 shown.

Such a registered contribution can in particular according to one of the in the document WO 2004/050991 A1 described method. For example, the microlens thread 12 can be introduced by means of a coil under pretension in the paper web. A first sensor detects the position of the coated regions 46 shortly before being introduced into the paper web, a second sensor detects the position of the webs 16 formed in the paper web immediately after sheet formation. The positions detected by the two sensors are evaluated and used to control the magnitude of the bias voltage. When the bias voltage is increased, the microlens thread 12 is stretched more, and when the preload is lowered, the elongation is reduced. The microlens thread 12 can be aligned in this manner with its coated and uncoated areas 44, 46 in register on the window and web areas 14,16.

Preferably, in the case of registered thread embedding, the method is such that the thread carries a register mark, which is recognized particularly well by a detection system. The thread embedding is then controlled by means of the tension on the thread so that the register mark of the thread is in fixed local reference to the register mark of the paper, usually a watermark. The areas in which the thread has adhesive on the top are then in a fixed, known local reference to the register mark of the thread. In an analogous manner, the land areas in the paper are in fixed local relation to the register mark in the paper.

This procedure ensures that the web areas 16 of the paper web 50 are glued to the microlens thread 12 so that secure embedding of the microlens thread 12 without wrinkling and without lifting or tearing the paper webs during production is ensured. Likewise, the stability of the paper webs against circulation stresses is significantly improved. At the same time, the microlenses 22 of the uncoated regions 44 visible in the window regions 14 remain free of adhesive, so that the optical properties of the microlenses 22 are not impaired. The microlens thread 12 therefore exhibits the desired clear visual appearance after being embedded in the paper web 50 in the window regions 14.

The uncoated regions 44 and the coated regions 46 have, in advantageous embodiments, the same size as the window regions 14 or the land regions 16. In some embodiments, it is also provided that the coated regions 46 are smaller, for example by not more than 10% or not more than 50% smaller than the land areas 16. By how much the glue-coated part compared to the paper webs thread length is also very much related to the register tolerance of registered thread embedding. For example, if the registration allowance is ± 1 mm registered thread insertion, the glue-free areas of the thread should be 2 mm shorter than the paper webs. Even if only a part of the microlens thread 12 is glued to the web areas 16, a significantly improved embedding results compared with the prior art.

Even configurations in which the uncoated regions 44 are slightly smaller than the window regions 14 come into consideration. However, the focusing effect of adhesive-loaded microlenses 22 in the window regions 14 is reduced or eliminated, so that the uncoated regions 44 are preferably smaller by no more than 10%, particularly preferably not more than 5%, than the window regions 14.

A further advantage of the registered introduction of the microlens thread 12 is that any motive jumps 34 in the motif image can be hidden under a paper web 16 of the security paper 50, as in FIG Fig. 3 shown. Thereby, the uniformity of the visual appearance of the microlens thread 12 is further increased.

In a modification of the described procedure, the microlens thread 12 is not registered registered in the paper web 50, but is printed immediately before entering the paper machine with an adhesive pattern 48 that the coated areas 46 in the recessed portions of the round screen in which the Train paper webs 16, come to rest. For this purpose, for example, a sensor can detect the position of the webs 16 formed in the sheet formation in the paper web, and the detected position can be used to control the printing positions for the adhesive pattern 48. Also in this way can the uncoated and coated areas 44, 46 are aligned in register on the window and web areas 14,16.

Another variant of the invention will now be described with reference to FIGS. 5 to 7 explained. The show FIGS. 5 and 6 a plan view and a cross section of the microlens thread 60 before embedding in the security paper and Fig. 7 shows a cross section of the security paper 50 with the embedded microlens thread 60th

In the variant of FIGS. 5 to 7 the microlens thread 60 is not coated with adhesive on its upper side 30, but it is provided with an opening pattern 68 in the form of the web pattern 18 before being introduced into the paper web 50. The opening pattern 68 consists of a sequence of regions 66 with openings 62 and regions 64 without openings, which corresponds to the sequence of the land regions 16 and window regions 14 of the web pattern 18. The underside 32 of the microlens thread 60 is preferably provided with a full-surface adhesive layer 42.

The microlens thread 60 is then registered in the paper web 50 introduced, so that the apertured portions 66 of the microlens thread 60 coincide with the web portions 16 of the paper web 50, as basically already in connection with the FIGS. 2 to 4 described. The first sensor in this case detects the position of the openings 62 just before the introduction of the microlens thread 12 into the paper web. The microlens thread 60 can be aligned in this manner with its opening pattern 68 register accurate to the window and land areas 14,16.

In this variant of the invention is achieved by the provision of the openings 62 that in the formation of paper under the web portions 16 paper fibers or other constituents of the substrate 50 can penetrate through the openings 62, to establish a connection between the web regions 16 and the substrate material 52 under the microlens filament 60 (FIG. Fig. 7 ). This also an intimate connection of paper web 50 and microlens thread 60 and thus a secure embedding is achieved without wrinkling. Since the top 30 of the microlens thread 60 remains adhesive-free, the optical properties of the microlenses 22 are not compromised.

The openings 62 may for example be stamped or produced by laser cutting. Each region 66 may include one or more apertures 62. For illustration, the show FIGS. 6 and 7 a design with only one opening 62 per area 66, while Fig. 5 a design with three openings 62 per area 66 illustrated.

In a modification of the method described procedure, the microlens thread 60 is not registered registered in the paper web 50, but it is only immediately before entering the paper machine by laser exposure so provided with the opening pattern 68 that the areas 66 with openings 62 in the recessed portions of Rundsiebs, in which the paper webs 16 form, come to rest. For this purpose, for example, a sensor can detect the position of the webs 16 formed in the paper web and the detected position can be used to control the laser beam. In this way too, the opening pattern 68 can be aligned in register with the window and web areas 14, 16.

In a further variant of the invention, in the FIGS. 8 and 9 is illustrated, a microlens thread 70 is used, which has on its upper side 30 a sequence of partial regions 74 with microlenses 22 and microlens-free partial regions 76. The motif layer and any further layers of the microlens thread 70 are in the FIGS. 8 and 9 for the sake of clarity not shown. The microlens-free portions 76 of the top 30 are coated with adhesive 40 and the underside of the microlens thread 70 is coated over its entire surface with adhesive 42.

The adhesive-coated, microlens-free subregions 76 are smaller than the width of the window regions 14 of the web pattern 18. This ensures that in the case of the unregistered introduction of the microlens thread 70 into a security paper 50, microlenses 22 are at least partially visible in each window area 14 ( Fig. 9 ).

In this way, on the one hand, a visually attractive appearance is obtained, on the other hand, even without a registered introduction of the microlens thread 70 can be achieved over the prior art improved embedding, since always a portion of the adhesive-coated portions 76 lie below web portions 16 of the paper web will come, as in Fig. 9 illustrated.

According to a modification of the above, in the FIGS. 8 and 9 In the illustrated variant of the invention, the areas coated with adhesive can certainly also have microlenses. Although these would be optically ineffective by the adhesive coating, but allow a uniform configuration of the thread with microlenses.

According to a further modification of the above, in the FIGS. 8 and 9 illustrated variant of the invention is particularly suitable for wider threads to arrange the microlens-free areas diagonally or strip-shaped along the thread and thus optionally provide over the entire length of the thread areas that can be coated with adhesive. The adhesive or adhesive used in the present invention may be, for example, a heat sealing lacquer. The adhesive may moreover have security features, for example dyes or color pigments and luminescent substances.

LIST OF REFERENCE NUMBERS

10

bill

12

Microlens thread

14

panes

16

web regions

18

web patterns

20

carrier

22

microlenses

24

more layers

26

motif layer

28

Micromotif elements

30

top

32

bottom

34

motive jump

40

Adhesive layer top side

42

Adhesive layer underside

44

uncoated areas

46

coated areas

48

adhesive pattern

50

paper web

52

substrate material

60

Microlens thread

62

openings

64

Areas without openings

66

Areas with openings

68

opening pattern

70

Microlens thread

74

Subareas with microlenses

76

Microlens-free sections

Claims (16)

1. A method for manufacturing a security paper, in which

   M) an endless microlens thread is provided that exhibits a top and an opposing bottom, the top being provided with microlenses at least in fractional regions,

   P) a paper web is produced having a predetermined ridge pattern that exhibits ridge regions in which the microlens thread is embedded in the interior of the paper web, and that exhibits, lying between the ridge regions, window regions in which the microlens thread emerges at the surface of the paper web, and

   E) the microlens thread is introduced into the paper web and, at the same time, is joined on its bottom and, in the ridge regions, also on its top, with the paper web, the paper web with the introduced microlens thread forming the security paper.
2. The method according to claim 1, characterized in that

   - before the introduction into the paper web, the microlens thread is provided on its top with an adhesive layer in the form of the ridge pattern and

   - in step E), the microlens thread is introduced into the paper web in register, such that the adhesive-coated regions of the microlens thread coincide with the ridge regions of the paper web.
3. The method according to claim 2, characterized in that the microlens thread includes a motif having a motif jump, the microlens thread being introduced in register, such that the motif jump comes to lie in one of the ridge regions of the paper web.
4. The method according to one of claims 1 to 3, characterized in that the adhesive layer forms an adhesive pattern having a sequence of uncoated regions and adhesive-coated regions, the adhesive-coated regions each having an up to 50%, preferably up to 10%, smaller dimension than the ridge regions of the paper web.
5. The method according to claim 1, characterized in that, immediately before entering into the paper web, the microlens thread is selectively coated with adhesive in those regions of its top that, at sheet formation, come to lie below ridge regions of the paper web.
6. The method according to claim 1, characterized in that

   - before the introduction into the paper web, the microlens thread is provided in an opening region with a plurality of openings in the form of the ridge pattern, and

   - in step E), the microlens thread is introduced into the paper web in register, such that the regions of the microlens thread that are provided with openings coincide with the ridge regions of the paper web.
7. The method according to claim 6, characterized in that the microlens thread includes a motif having a motif jump, the microlens thread being introduced in register, such that the motif jump comes to lie in one of the ridge regions of the paper web.
8. The method according to claim 1, characterized in that, immediately before entering into the paper web, the microlens thread is selectively provided with openings in those regions of its top that, at sheet formation, come to lie below ridge regions of the paper web.
9. The method according to one of claims 6 to 8, characterized in that the openings are produced by punching or laser cutting.
10. The method according to one of claims 1 to 9, characterized in that the paper web having the predetermined ridge pattern is formed in a paper machine, and the endless microlens thread enters into the paper machine.
11. The method according to claim 1, characterized in that, in step M), a microlens thread is provided whose surface, on the one hand, exhibits fractional regions having microlenses, which fractional regions are coated with adhesive before the introduction into the paper web, and which are smaller than the width of the ridge regions of the ridge pattern in the paper web, and on the other hand, exhibits fractional regions having microlenses that are not coated with adhesive before the introduction into the paper web.
12. The method according to claim 1, characterized in that, in step M), a microlens thread is provided whose top exhibits fractional regions having microlenses and microlens-free fractional regions, the microlens-free fractional regions being smaller than the width of the ridge regions of the ridge pattern in the paper web, and the microlens-free fractional regions being coated with adhesive before the introduction into the paper web.
13. The method according to one of claims 1 to 12, characterized in that the microlens thread is provided contiguously on its bottom with an adhesive layer before the introduction into the paper web.
14. A microlens thread for introduction into a paper web, especially with a method according to claim 12 or 13, having a top and an opposing bottom, characterized in that the top exhibits fractional regions having microlenses, and exhibits microlens-free fractional regions that are coated with adhesive.
15. The microlens thread according to claim 14, characterized in that the fractional regions having microlenses and the microlens-free fractional regions on the top form alternating strips that each completely occupy the width of the microlens thread and that each exhibit, in the longitudinal direction of the microlens thread, a dimension between 1 mm and 30 mm, preferably between 3 mm and 12 mm.
16. The microlens thread according to claim 14 or 15, characterized in that the bottom of the microlens thread is coated contiguously with adhesive.

Images