EP2769016B1 - Dewatering screen and method for manufacturing a dewatering screen - Google Patents

Description

The invention relates to a dewatering screen for the production of paper with at least one security feature. The invention also relates to a method for producing such a dewatering screen and to a method for producing paper with a security feature using such a dewatering screen.

In papermaking on round screening or screening machines, pulp accumulates continuously on a moving dewatering screen and is solidified to the extent that it can be removed as a wet paper web for further processing of the dewatering screen. In particular, security papers for banknotes, identity documents and the like are often provided with watermarks or through holes for security purposes, which permit verification of the authenticity of the security paper and which at the same time serve as protection against unauthorized reproduction.

Security features introduced in papermaking have typical characteristics. For example, through openings which are produced in papermaking contain characteristic irregularities in the edge region, which are produced by irregular deposition of fibers in the edge region and by individual fibers protruding into the opening, as for example in the document WO 03/054297 described.

If sharp-edged holes are to be produced in a paper, then a separate laser cutting or punching step is required for this, which, in addition to a higher outlay for the additional work step, also leads to register fluctuations between the paper-produced safety features and the features produced by laser cutting or punching.

In the DE 10 2006 058 513 A1 discloses a dewatering screen for the production of paper with multi-level watermark, with a support screen, which has a multi-level relief in the form of the watermark to be generated in a partial area. The multi-level relief is formed by an injection-molded perforated watermark insert.

Based on this, the present invention seeks to provide a Entwässerungssieb of the aforementioned type, which avoids the disadvantages of the prior art. In particular, the dewatering screen is intended to allow easy production of paper with security features, and ideally to allow a registered combination of security features with different visual appearances.

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

• ein Trägersieb, das ein Siebgewebe mit einem Einlegebereich enthält,
• ein in dem Einlegebereich des Siebgewebes angeordnetes Einlegeelement zur Erzeugung des zumindest einen Sicherheitsmerkmals in dem Papier, und
• eine Kunststoff-Umspritzung oder Kunststoff-Hinterspritzung des Einlegeelements, die das Einlegeelement mit dem Trägersieb verbindet.

According to the invention contains a dewatering screen for the production of paper with at least one security feature

• a carrier screen containing a screen cloth with an insert area,
• an insert element arranged in the insertion region of the screen fabric for producing the at least one security feature in the paper, and
• a plastic encapsulation or plastic back injection of the insert element, which connects the insert element with the support screen.

The security features generated in the invention include in particular watermarks, sharply edged holes in the paper and holes with characteristic irregularities in the edge region. With particular advantage, the dewatering screen is designed to produce several security features in the paper, each of which may have different visual appearances, but still because of the simultaneous generation stand in the register in the paper production and the very good tolerances when insert molding or injection molding. Several security features may in particular relate to each other or complement each other. For example, a first security feature can repeat the form or shape of a second security feature or supplement it to a total information.

As explained in more detail below, a plurality of different insert elements can be integrated into a carrier screen for producing such security features by the plastic encapsulation or plastic injection molding according to the invention, in particular also those insert elements, which due to their material properties or shape with conventional techniques not in the have the desired carrier screen integrated. Particular advantages, the invention thus provides, for example, in cases where the mesh of the support wire and the insert element made of different materials. For example, the screen cloth and the insert element may be made of different metals, such as a bronze screen cloth and a steel insert member. In other advantageous embodiments, the support screen may be made of metal and the insert element made of plastic, or conversely, the support screen made of plastic and the insert element made of metal.

In an advantageous variant of the invention, the insert element comprises a sieve element whose material and / or mesh size differs from the sieve cloth of the carrier sieve. The sieve element can be embossed in particular. In a particularly advantageous embodiment, the screen fabric of the carrier screen is a pure plastic fabric, while the screen element comprises a bronze screen, in particular an embossed bronze screen. Thereby In a simple way, an embossing can be integrated into an otherwise non-embossable plastic screen fabric.

In a further likewise advantageous variant of the invention, the insert element comprises an E-type or a watermark insert, in particular a tapered E-type or a multi-level watermark insert. Such insert elements can be advantageously formed of steel. Insertion elements, for example made of steel, can not easily be connected with conventional bronze mesh by conventional techniques. The invention provides a remedy and allows to combine the advantageous properties of a bronze support wire and E types or steel watermark inserts with each other.

According to a further likewise advantageous variant of the invention, the insert element comprises a pointed frame, for example a pointed steel frame, for producing a sharply edged hole in the paper. Unlike conventional methods, such a dewatering screen allows to produce well-edged holes already in papermaking. This not only saves a separate operation, such as a laser cutting or punching step, the sharply edged holes can also be accurately combined with other papermaking security features, in particular with watermarks and / or holes with characteristic irregularities in the edge region.

In advantageous embodiments, the insert element comprises a metal plate and / or a plastic plate, in particular of water-repellent plastic. A plastic tile made of water-repellent plastic For example, it may be disposed inside an above pointed steel frame to assist in the formation of holes.

Depending on the desired design, it can be useful if the metal plate or the plastic plate is provided with a multiplicity of perforations, the dimensions of which are preferably so small that they do not adhere to fibers during papermaking. For example, a thinned paper area can be created by a bronze plate with a reduced perforation density. The metal or plastic plate may also be imperforate, if it is to support about the formation of holes.

The carrier screen of the dewatering screen may also include a magnetic element with which magnetic fibers and / or magnetic additives in the pulp may be affected during sheet formation. For example, magnetic fibers may be aligned along the magnetic field lines of the magnetic element and fixed in their aligned orientation upon drying to provide a security feature in the form of a magnetic portion in the paper. The magnetic element can also lead to a targeted accumulation or depletion of magnetic additives in certain paper areas.

The magnetic element can be advantageously contained in the insert element, for example in the form of a perforated permanent magnet. Alternatively or additionally, the magnetic element may also be formed by magnetic additives in the plastic encapsulation or the plastic back-injection. The magnetic element can also be arranged on inserted threads. Finally, it is also possible not to integrate the magnetic element in the uppermost screen layer of the carrier screen, but to arrange it, for example, within the round screen. The only important thing is that the magnetic field the magnetic element in the region of the first wire layer has a sufficient strength to influence the magnetic fibers or the magnetic additives of the pulp in sheet formation.

According to one embodiment of the invention, the plastic encapsulation or the plastic back-injection on a surface relief for generating a two- or multi-level watermark in the paper. Since the encapsulation or back-injection generally runs around the insert element, the security features generated by the insert element itself can be combined with another security feature in the form of a two- or multi-level frame watermark.

In all designs, the plastic overmoulding or the plastic backmolding can be provided with a multiplicity of perforations, the dimensions of which are preferably so small that no fibers adhere to them in the papermaking process.

The insertion region may in particular be formed by a cut-out portion of the screen fabric.

Advantageously, two or more of the concrete embodiments described are combined in an insert element in order to simultaneously produce a plurality of security features that stand in very good or even perfect register in papermaking.

• ein Trägersieb bereitgestellt wird, das ein Siebgewebe mit einem Einlegebereich enthält,
• in dem Einlegebereich des Siebgewebes ein Einlegeelement zur Erzeugung zumindest eines Sicherheitsmerkmals in dem Papier angeordnet wird, und
• das Einlegeelement mit Kunststoff umspritzt oder hinterspritzt wird, um das Einlegeelement mit dem Trägersieb zu verbinden.

The invention also includes a process for producing a dewatering screen for papermaking, in which

• a support screen is provided which contains a screen fabric with an insertion area,
• in the insertion region of the screen fabric, an insert element for generating at least one security feature is arranged in the paper, and
• the insert element is encapsulated with plastic or injected behind to connect the insert element with the support screen.

In the method, the plastic encapsulation or the plastic back-injection is preferably provided with a multiplicity of perforations whose dimensions are so small that no fibers adhere to them in the papermaking process. The perforations can be generated by means of a laser beam, preferably by means of an infrared laser.

Finally, the invention also includes a method for producing a paper having at least one security feature, in which the paper attachment takes place on a dewatering screen of the type described.

In an advantageous variant of the method, a sharp-edged hole is produced in the paper as a security feature. According to another likewise advantageous variant of the method, a hole with characteristic irregularities in the edge region and / or a watermark in the paper is produced as a security feature. Particular advantages are offered by a process control in which a sharply edged hole is produced in the paper as the first security feature and in which a hole with characteristic irregularities in the edge region and / or a watermark in the paper is produced as a second security feature, the first and second Security feature to each other in the register. Such designs are visually attractive due to the combination of different security features and offer a high security against counterfeiting.

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 Banknote mit einer komplexen Kombination mehrerer Sicherheitsmerkmale,

Fig. 2

in (a) schematisch einen Querschnitt durch eine Grundform eines erfindungsgemäßen Entwässerungssiebs, und in (b) eine Abwandlung der Grundform von (a),

Fig. 3

ein Trägersieb mit einem integrierten Einlegeelement nach einem Ausführungsbeispiel der Erfindung,

Fig. 4

ein Trägersieb mit einem integrierten Einlegeelement nach einem anderen Ausführungsbeispiel der Erfindung,

Fig. 5

ein Trägersieb mit einem integrierten Einlegeelement nach einem weiteren Ausführungsbeispiel der Erfindung,

Fig. 6

ein komplexes Ausführungsbeispiel, mit einem Einlegeelement zur gleichzeitigen Erzeugung mehrerer Sicherheitsmerkmale, wobei (a) einen Querschnitt und (b) eine Aufsicht auf das Entwässerungssieb zeigt, und (c) das visuelle Erscheinungsbild des gebildeten Papiers illustriert,

Fig. 7

ein Entwässerungssieb mit einem integrierten magnetischen Einlegeelement, und

Fig. 8

das Erscheinungsbild eines mit dem Entwässerungssieb der Fig. 7 erzeugten Papiers.

Show it:

Fig. 1

a schematic representation of a banknote with a complex combination of several security features,

Fig. 2

in (a) shows schematically a cross section through a basic shape of a drainage sieve according to the invention, and in (b) a modification of the basic form of (a),

Fig. 3

a carrier screen with an integrated insert element according to an embodiment of the invention,

Fig. 4

a carrier screen with an integrated insert element according to another exemplary embodiment of the invention,

Fig. 5

a carrier screen with an integrated insert element according to a further exemplary embodiment of the invention,

Fig. 6

a complex embodiment, with an insert element for simultaneously generating a plurality of security features, wherein (a) shows a cross-section and (b) a plan view of the dewatering screen, and (c) illustrates the visual appearance of the formed paper,

Fig. 7

a dewatering screen with an integrated magnetic insert element, and

Fig. 8

the appearance of a with the dewatering sieve Fig. 7 produced paper.

The invention will now be explained using the example of security features for banknotes. Fig.1 shows a schematic representation of a banknote 10 with a complex combination 12 of several security features. The banknote 10 contains a finely structured hole 16 with a sharply delimited rim in the form of a rider, which is surrounded by a very thin paper area 15 and this by a high resolution frame watermark 14. The finely structured hole 16, the thin paper area 15 and the frame watermark 14 have very low register tolerances due to the overmolding or backmolding technology used.

Such complex combinations of security features 14, 15, 16 can not already be produced by conventional methods in papermaking. In particular, the production of a hole with a sharply defined edge and fine contour structure, such as the hole 16 of the Fig.1 , a separate step by laser cutting or punching. As a rule, relatively high register tolerances arise between the hole produced by punching or laser cutting and a watermark generated during papermaking. These passport tolerances limit the practical watermark / hole designs significantly, since The designer must already take into account the pass tolerances when designing the design.

According to the invention, the security paper of the banknote 10 is produced by using a dewatering screen described in more detail below, whereby both the finely structured hole 16 and the thin paper area 15 and the high-resolution frame watermark 14 can already be produced in papermaking and in almost perfect register.

Regarding Fig. 2 (a) schematically showing a cross section through a basic shape of a dewatering screen according to the invention, the dewatering screen 20 comprises a support screen 22 with a screen mesh 24 which is cut out in a partial region 30. The screen fabric 24 has at least one system of interwoven, longitudinally extending warp threads 26 and weft threads 28 extending transversely thereto. In the context of the present invention, the screen fabric may contain, for example, a metal fabric, in particular a bronze fabric, a metal-plastic mixed fabric, in particular a bronze-plastic blended fabric or a pure plastic fabric. The support screen 22 may comprise a single-layer or multi-layer screen fabric, wherein for the sake of simplicity, only one single-layer screen fabric is shown in the figures.

In the cut-out portion 30 of the screen fabric 24, an insert element 32 for generating at least one security feature 14,15,16 is arranged in the security paper, wherein the insert member 32 is connected by a plastic extrusion coating 34 with the support screen 22. Fig. 2 (b) shows a modification of the basic form of Fig. 2 (a) in which the insert element 32 by a plastic injection back 36 with the support beam 22nd connected is. By means of the encapsulations 34 or backwards injections 36 according to the invention, a multiplicity of different insertion elements 32 can be integrated into the support screen 22, in particular also those insertion elements 32 which are produced by conventional techniques due to the diversity of the materials or due to a particular shape or other particular characteristics of the insertion element 32 can not be integrated into the support 22.

In some embodiments, it is useful if the insert element 32, the plastic encapsulation 34 or plastic back injection 36, or even both elements are provided with perforations to ensure the dewatering in papermaking in these areas. The dimensions of the perforations are chosen so small that they do not adhere to fibers in paper production.

In further embodiments, the screen fabric 24 is not cut out, but has only one insertion region, in which the insert element is arranged. In particular, the screen fabric during encapsulation behind the insert element and the back injection in or behind the back injection continue.

The following figures show some concrete embodiments of insert elements, which are not easily integrated with conventional methods in the carrier screen used.

In the embodiment of Fig. 3 the carrier screen 40 has a bronze screen mesh 42. In the cut-out portion 30 of the bronze screen fabric 42, an insert member 44 is arranged, which contains a steel plate 46 with a tapered steel E-type 48. The insert element 44 is connected by a plastic encapsulation 34 with the support screen 40.

A steel insert 44 with a tapered steel E-type 48 can not readily be welded to a bronze screen 42 due to the diversity of materials. A connection by means of electric welding fails because of the pointed E-Type 48 on the diversity of the surfaces to be joined. Although a solder joint of the steel insert element 44 with the bronze screen fabric 42 would be possible in principle, but fine soldering decompose in the acidic environment of the paper pulp, and there is also the danger that the mesh of the screen fabric 42 are closed by the solder paste. The same problems generally occur in upwardly tapered steel E-types, such as multi-stage E-types, or even in multi-stage steel watermark inserts, which can not readily be joined to the bronze mesh 42 by conventional methods can be easily integrated into the carrier screen by a plastic encapsulation 34 or plastic injection back 36.

Fig. 4 shows a further embodiment in which the carrier screen 40 also has a bronze screen mesh 42. In a cut-out portion 30 of the bronze screen fabric 42, an insert element 50 is arranged, which contains a pointed steel frame 52. With the pointed steel frame 52, a hole 16 with a sharp edge is already produced in papermaking, such as in Fig.1 illustrated. The insert element 50 with the steel frame 52 is connected to the carrier screen 40 by a plastic encapsulation 34. By contrast, with conventional methods, the steel frame 52 can not be integrated into the bronze carrier screen 40 for the reasons stated above.

To enhance the effect, the insert element within the steel frame additionally contain a plastic plate 54 made of a water-repellent plastic. Such a measure is particularly useful when only smaller holes are to be produced with the steel frame 52.

In the embodiment of the Fig. 5 the insert element integrated in the carrier screen 60 is formed by a screen element 64 whose material and / or mesh size differs from the screen fabric 62 of the carrier screen 60. For example, the carrier screen 60 may contain a pure plastic screen cloth 62 and the screen element 64 may be formed by a bronze screen with an embossment 66 which is connected to the carrier screen 60 by the plastic extrusion coating 34. In this way, embossing 66 can nevertheless be integrated into a plastic screen cloth 62, which itself can not be embossed, in a simple manner.

Fig. 6 shows a complex embodiment in which the insert element 72 of the Entwässungssiebs 70 is designed for the simultaneous generation of several different security features. Fig. 6 (a) shows a cross section and Fig. 6 (b) a plan view of the dewatering screen 70. The visual appearance of the formed paper 90 is in Fig. 6 (c) shown.

Referring first to the FIGS. 6 (a) and (b) contains the dewatering screen 70 as the dewatering screen 20 of the Fig. 2 a support screen 22 with a cut out in a portion 30 screen mesh 24 made of bronze. In the cut-out portion 30, an insert element 72 is arranged, which is connected by a plastic encapsulation 80 with the support screen 22. The plastic encapsulation 80 has in this embodiment multi-level surface relief 82 and is also provided to ensure drainage during sheet formation with a variety of perforations. Since the plastic overmold 80 runs around the edge of the insert member 72, it forms a perforated injection molding frame which, in papermaking, creates a multi-level frame watermark 94 in the paper 90 due to its multi-level surface relief 82 which includes the security features created by the insert member 72 in Fig. 6 (c) shown.

The insert element 72 itself contains an only slightly perforated bronze sheet 74, which produces a very thin paper area 96 due to the low perforation density and its smooth surface in papermaking. Inside the bronze plate 74 is a pointed steel frame 76 for creating a hole 98 with a sharp edge (FIG. Fig. 6 (c) ) intended. The steel frame 76 may be discontinued down so that it does not come into contact with the dandy or the take-off roll.

Within the steel frame 76, a plate 78 is disposed of water-repellent plastic, which supports the hole production. The connection between the bronze plate 74, the steel frame 76 and the plastic plate 78 can be done, for example, by gluing, welding, stapling or any other conventional method.

With reference to the representation Fig. 6 (c) For example, the paper 90 produced by the dewatering screen 70 outside the frame watermark 94 displays a vellum region 92 of normal paper thickness. The frame watermark 94 has a multi-stage design, the appearance of which is given by the multi-level surface relief 82 of the plastic encapsulation 80. Within the frame watermark 94, a vellum region 96 is very small Paper thickness, which is produced by the small perforated bronze sheet 74, and within this thin Velinbereichs 96 is a finely structured, sharply edged hole 98 in the form of a rider arranged. According to the invention, all these different security elements are produced simultaneously in papermaking. Their manufacture does not require separate operations, such as a laser cutting or stamping step. In addition, the security features due to the common generation by the insert element to each other very well in the register. In particular, there are no register fluctuations between the frame watermark 94 and the sharply edged hole 98, so that the two elements can be aligned as desired.

As a result of the encapsulation or injection molding of insert elements according to the invention, magnetic elements can also be integrated into a carrier screen. For illustration shows Fig. 7 a dewatering screen 100 with a carrier screen 22 with a cut-out screen mesh 24, in the cut-out portion of which a sickle-shaped permanent magnet 102 is provided as an insert element, which is provided with a multiplicity of perforations 104. The perforated permanent magnet 102 is connected to the carrier screen 22 by a plastic encapsulation 34.

The plurality of perforations 104 ensure drainage in the area of the permanent magnet 102. Due to the magnetic field of the permanent magnet 102, magnetic components of the pulp are specifically influenced during sheet formation. For example, the pulp may include magnetic fibers that are aligned with the sheet formation along the magnetic field lines of the permanent magnet 102. During drying of the paper web, the magnetic fibers are then permanently fixed in their aligned orientation.

Fig. 8 shows a plan view of a with the dewatering screen 100 of Fig. 7 produced paper 110 with a magnetic security feature. In a crescent-shaped portion 112, which was directly above the permanent magnet 102 during paper production, magnetic fibers contained in the pulp were aligned while the magnetic fibers in the surrounding paper portion 114 were disordered. The different orientation of the magnetic fibers can be detected on the finished paper 110, for example with a magnetic sensor.

In other configurations, subregion 112 may also differ visually from surrounding region 114. For example, the pulp may contain magnetic, colored or fluorescent additives that are attracted or repelled by the permanent magnet 102, so that the concentration of these additives in the subregion 112 differs from the concentration in the surrounding region 114.

Magnetic elements need not be included in the insert element 32, they may also be formed by magnetic additives in the plastic encapsulation 34 and the plastic injection back 36. They also do not have to be integrated into the uppermost sieve layer 24 of the support screen 22, but can also be arranged in a deeper sieve layer or in the interior of the round sieve. For example, they can also be on the threads that are inserted. Magnetic elements can be combined with all previously described designs.

LIST OF REFERENCE NUMBERS

10

bill

12

complex security feature

14

Frame watermark

15

thin paper area

16

finely structured hole

20

dewatering

22

support screen

24

mesh

26

warp

28

wefts

30

cut out section

32

insertion element

34

Plastic extrusion coating

36

Plastic insert molding

40

support screen

42

Bronze mesh

44

insertion element

46

steel plates

48

Steel E-Type

50

insertion element

52

pointed steel frame

54

Plastic plates

60

support screen

62

mesh

64

sieve

66

embossing

70

dewatering

72

insertion element

74

bronze sheet

76

pointed steel frame

78

Tile

80

Plastic extrusion coating

82

surface relief

90

paper

92

Velin area of normal paper thickness

94

Frame watermark

96

thin paper area

98

sharply bordered hole

100

dewatering

102

permanent magnet

104

perforations

110

paper

112

sickle-shaped portion

114

surrounding paper area

Claims (20)

1. A dewatering screen (20) for manufacturing paper having at least one security feature, having

   - a carrier mold (22) that includes a wire cloth (24) having an insert region,

   - an insert element (32) arranged in the insert region of the wire cloth to produce the at least one security feature in the paper, and

   - a plastic overmolding (34) or plastic back molding (36) of the insert element (32), which connects the insert element (32) with the carrier mold (22).
2. The dewatering screen according to claim 1, characterized in that the wire cloth (24) of the carrier mold (22) and the insert element (32) consist of different materials, especially in that the wire cloth and the insert element consist of different metals or in that one of the elements carrier mold and insert element consists of metal and the other element of plastic.
3. The dewatering screen according to claim 1 or 2, characterized in that the insert element (32) comprises a mold element (64) whose material and/or mesh size differs from the wire cloth of the carrier mold.
4. The dewatering screen according to claim 3, characterized in that the mold element (64) is embossed.
5. The dewatering screen according to claim 3 or 4, characterized in that the wire cloth (24) of the carrier mold (22) is a pure plastic cloth, and the mold element (64) comprises a bronze mold, especially an embossed bronze mold.
6. The dewatering screen according to at least one of claims 1 to 5, characterized in that the insert element (32) comprises an E-type (48) or a watermark insert, especially a tapered E-type or a multi-level watermark insert.
7. The dewatering screen according to at least one of claims 1 to 6, characterized in that the insert element (32) comprises a sharp frame (52) for producing a sharply edged hole (16) in the paper.
8. The dewatering screen according to at least one of claims 1 to 7, characterized in that the insert element comprises a metal platelet and/or a plastic platelet (54), especially composed of water-repellant plastic.
9. The dewatering screen according to claim 8, characterized in that the metal platelet and/ or the plastic platelet (54) are provided with a plurality of perforations whose dimensions are preferably so small that no fibers stick in them at paper manufacture.
10. The dewatering screen according to at least one of claims 1 to 9, characterized in that the carrier mold (22) includes a magnet element, preferably in that the insert element (32), the plastic overmolding (34) or the plastic back molding (36) includes the magnet element, or in that the magnet element is arranged on shot threads.
11. The dewatering screen according to at least one of claims 1 to 10, characterized in that the plastic overmolding (34) or the plastic back molding (36) comprises a surface relief (82) to produce a bi- or multi-level watermark in the paper.
12. The dewatering screen according to at least one of claims 1 to 11, characterized in that the plastic overmolding (34) or the plastic back molding (36) is provided with a plurality of perforations whose dimensions are preferably so small that no fibers stick in them at paper manufacture.
13. The dewatering screen according to at least one of claims 1 to 12, characterized in that the insert region is a cut-out sub-region (30) of the wire cloth (24).
14. A method for manufacturing a dewatering screen (20) for paper manufacture, in which

    - a carrier mold (22) is provided that includes a wire cloth (24) having an insert region,

    - in the insert region of the wire cloth is arranged an insert element (32) for producing at least one security feature in the paper, and

    - the insert element (32) is overmolded or back-molded with plastic to connect the insert element with the carrier mold (22).
15. The method according to claim 14, characterized in that the plastic overmolding (34) or the plastic back molding (36) is provided with a plurality of perforations whose dimensions are so small that no fibers stick in them at paper manufacture.
16. The method according to claim 15, characterized in that the perforations are produced by means of laser beam, preferably by means of infrared laser.
17. A method for manufacturing a paper having at least one security feature, in which the paper accretion occurs on a dewatering screen according to one of claims 1 to 13.
18. The method according to claim 17, in which, as the security feature, a sharply edged hole (16) is produced in the paper.
19. The method according to claim 17, in which, as the security feature, a hole (16) having characteristic irregularities in the edge region and/ or a watermark is produced in the paper.
20. The method according to claim 17, in which, as the first security feature, a sharply edged hole is produced in the paper, and as the second security feature, a hole having characteristic irregularities in the edge region and/or a watermark is produced in the paper, the first and second security feature being in register with each other.

Images