DE102020007606A1 - Drainage screen, injection molding tool and method for manufacturing drainage screens - Google Patents

Abstract

The invention relates to a drainage wire (10) for the production of paper with high-resolution watermarks, with a carrier wire (12) with a plurality of individual use areas (14) which each produce one of a plurality of individual uses of the watermark paper during paper manufacture, the drainage wire ( 10) is provided with its individual use areas (14) with watermark inserts (20), which are designed as high-resolution, multi-stage watermark inserts at least in partial areas (22). According to the invention, the watermark inserts (20) each have a series watermark area (22) that is identical for all individual copies (14) and an individual watermark area (24) that is individualized for each individual copy (14). The invention also relates to an injection molding tool (70) for producing high-resolution, multi-stage watermark inserts (20) for such drainage screens (10), and a method for producing drainage screens of the type mentioned.

Description

The invention relates generally to the manufacture of watermark paper. In particular, the invention relates to a drainage wire for the production of paper with high-resolution watermarks, which has a carrier wire with a plurality of individual use areas, which each produce one of a plurality of individual use areas of the watermark paper during paper production, the drainage wire being provided with its individual use areas with watermark inserts, which are designed, at least in some areas, as high-resolution, multi-stage watermark inserts. The invention also relates to an injection molding tool for producing high-resolution, multi-stage watermark inserts for such drainage screens, as well as a method for producing drainage screens of the type mentioned.

When paper is made on cylinder molds or fourdrinier machines, the paper pulp is continuously deposited on a moving dewatering wire and is solidified to such an extent that it can be drawn off the dewatering wire as a moist paper web for further processing. In particular security papers for banknotes, identification documents and the like are often provided with watermarks for security purposes, which allow the authenticity of the security paper to be checked and which at the same time serve as protection against unauthorized reproduction.

A cylindrically welded dewatering screen with a multi-layer structure of various bronze screens is typically used for the production of detailed watermarks in cylinder screen technology. The desired watermark motifs can be embossed into the bronze screen or soldered onto the screen structure as so-called electrotypes.

Generation of high-resolution watermarks by means of perforated injection molding reliefs is also known and is described in the publication, for example DE 10 2006 058 513 A1 described.

In some applications, such as the production of passport paper, individual watermarks are required for each page or for each copy. For this purpose, electrotypes, which represent, for example, the page number of a passport page, are soldered onto the dewatering screen by hand, which involves a great deal of work. Alternatively, highlight areas can also be integrated into high-resolution injection molding reliefs. However, no usage-specific variation is possible, so that at present different injection molds have to be milled at great expense for different watermarks.

Proceeding from this, the invention is based on the object of specifying a dewatering fabric of the type mentioned at the outset, which avoids the disadvantages of the prior art and, in particular, enables the production of watermark paper with customized watermarks in a simple and cost-effective manner.

According to the invention, in a generic drainage wire, the watermark inserts present in the individual use areas each have a series watermark area that is identical for all individual uses, and also have an individual watermark area that is individualized for each individual use.

The individual watermark area preferably has an individualization in the form of patterns, characters or a code, in particular a sequence of letters or numbers. The individualization can represent, for example, the page number of a passport or another multi-page identification document.

In a currently particularly preferred embodiment, the individual watermark area generates a highlight area of the watermark, the information of which appears particularly light in the watermark paper. Such highlight areas are very noticeable when viewed and are therefore quickly and reliably perceived by the user. In principle, however, it is also possible with the methods described here to generate individual watermark areas that appear particularly dark in the watermark paper.

The individual watermark area is advantageously formed in each case by a binary structure whose flat surface sections are arranged at only two different height levels. Such binary structures can produce high contrast and are therefore visually very noticeable. The individual watermark area can advantageously also be formed by a multilevel structure with 3, 4 or 5 different levels. As a result, differentiated brightness variations can still be present within a highlight area, for example, an effect that cannot be easily reproduced with conventional electrotypes.

The series watermark area of the watermark inserts is preferably formed by a high-resolution, multi-level relief with 6 or more vertical levels. The height levels can also be so close together that the impression of a continuous relief progression is created. The contrast between the resolution of the series watermark area (high-resolution, multi-level) and the individual watermark area (low-resolution, binary or low-level) creates a visual tension in the watermark that emphasizes the individual watermark area and draws the viewer's attention to its information content. The image content of the high-resolution serial watermark area often acts as a decorative background area that enhances the overall visual attractiveness of the watermark but does not itself carry any useful information.

In an advantageous embodiment, the individual watermark area only occupies a subordinate surface area in the watermark insert. It preferably occupies less than 50%, advantageously less than 25% and in particular less than 15% of the area of the watermark insert.

The individual watermark area is advantageously integrated into the overall design of the watermark insert without any visible transitions, for example by a transition area between the individual watermark area and the serial watermark area being designed continuously or in several, in particular 4 or more, brightness levels.

Another authenticity feature within the watermark inserts can be formed by varying not only the information content of the individualization but also its position within the individual watermark area. For example, the position at which a highlight area is arranged can vary depending on the information displayed, for example even-numbered pages can be arranged on the left edge of the individual watermark area and odd-numbered page numbers can be arranged on the right edge of the individual watermark area.

In a preferred variant of the invention, the individual watermark area is formed by a laser-engraved area of the watermark insert. The individual watermark area can be formed individually in a simple, cost-effective and particularly flexible manner by means of laser engraving.

In another, likewise advantageous variant of the invention, the watermark insert has a watermark insert body with a recess into which one or more shaped elements are inserted in order to form the individual watermark area. The shaped elements are advantageously connected to the watermark insert body by pressing, gluing or fusing.

In all configurations, the serial watermark area is preferably formed by an injection molding relief. In this way, the part of the watermark inserts that is identical for all individual copies can be produced with high precision and quickly using an injection molding process, so that the total production time for the individualized watermark inserts remains short.

The watermark insert is advantageously a perforated injection molded insert. This means that advantageously at least the watermark insert body and the serial watermark area are formed by an injection molding process. In some designs, raw areas or rough forms of a high-resolution, multi-stage relief are provided in the individual watermark area, which are preferably formed at the same time by the injection molding process mentioned.

In an advantageous embodiment, the watermark inserts are provided with drainage perforations, the arrangement of which is matched to the relative position of the individual watermark area in the watermark inserts. For example, the arrangement of the drainage perforations can be chosen such that the drainage perforations either clearly separate the individual watermark area from the series watermark area or, conversely, produce smoother transitions. For this purpose, the drainage perforations can be arranged with a greater or lesser density in the individual watermark area than in the serial watermark area, or the diameter of the drainage perforations can be larger or smaller in the individual watermark area than in the serial watermark area. In the individual watermark area, the perforation can also be dispensed with entirely, which leads to a particularly light appearance.

An advantageous possibility for producing the desired watermark inserts is the use of a special injection molding tool with which high-resolution, multi-stage watermark inserts can be produced in a simple and cost-effective manner, each having a serial watermark area and an individual watermark area.

For this purpose, the injection molding tool contains an injection molding cavity with a series area and an individual area, the series area of the injection molding cavity being covered by a high-resolution watermark relief in the form of the inverted Reliefs of the desired series watermark area is provided, and the individual area of the injection molding cavity is provided by a recess with detachably inserted molded pieces in the form of the inverted relief of the desired individual watermark area.

The recess of the injection mold is preferably formed by round bores, but can also be freely shaped. The molded pieces used can be releasably accommodated in the recess, for example by pressing. Advantageously, the fittings are each provided with a seal to prevent plastic from flowing behind the fittings during the injection process. The injection molding tool and the fittings are produced with particular advantage by an additive manufacturing process.

• - ein Trägersieb bereitgestellt wird, das eine Mehrzahl von Einzelnutzbereichen aufweist, die bei der Papierherstellung jeweils einen einer Mehrzahl von Einzelnutzen im Wasserzeichenpapier erzeugen,
• - in den Einzelnutzbereichen des Trägersiebs jeweils Wasserzeicheneinsätze eingebracht werden,
• - die Wasserzeicheneinsätze jeweils mit einem Serienwasserzeichenbereich ausgebildet werden, der für alle Einzelnutzen identisch ist, und mit einem Individualwasserzeichenbereich ausgebildet werden, der für jeden Einzelnutzen individualisiert ist, wodurch die Wasserzeicheneinsätze zumindest in Teilbereichen als hochauflösende mehrstufige Wasserzeicheneinsätze ausgebildet werden.

The invention also includes a method of manufacturing a dewatering screen, in particular of the type described above, in which

• - a carrier screen is provided, which has a plurality of individual use areas, which each produce one of a plurality of individual use areas in the watermark paper during paper production,
• - watermark inserts are placed in the individual usable areas of the carrier screen,
• - The watermark inserts are each formed with a series watermark area that is identical for all individual copies, and are formed with an individual watermark area that is individualized for each individual copy, whereby the watermark inserts are formed at least in partial areas as high-resolution multi-stage watermark inserts.

• - durch Spritzgießen Wasserzeicheneinsatzrohlinge mit dem Serienwasserzeichenbereich und einem Rohbereich für den Individualwasserzeichenbereich erzeugt, und
• - werden durch Lasergravur in den eingebrachten Wasserzeicheneinsatzrohlingen die Individualwasserzeichenbereiche erzeugt.

In an advantageous method are thereby

• - produced by injection molding watermark insert blanks with the series watermark area and a raw area for the individual watermark area, and
• - the individual watermark areas are produced by laser engraving in the introduced watermark insert blanks.

In a particularly advantageous way of carrying out the method, the watermark insert blanks are each injected directly into the carrier screen in this variant and in the variants described below.

In this advantageous variant, the watermark insert blanks are individualized by laser impingement only after they have been produced, in particular after they have been directly injected into the carrier screen. Laser engraving allows practically any graphic design of the individualization. For letters and numbers, font types, sizes and their graphic design are completely free.

Advantageously, the watermark insert blanks are additionally provided with drainage perforations by laser impingement. The laser engraving of the raw areas can be done with the same laser processing unit with which the drainage perforations are also produced. Alternatively, two laser processing units can be used, one unit for laser engraving the watermark insert blanks from the mold side and one unit for creating the drainage perforations from the drainage side. While the former solution requires little outlay in terms of equipment, the latter solution offers greater flexibility. In particular, the drainage perforations can advantageously be designed to taper conically from the drainage side to the mold side.

CO ₂ lasers can be considered as laser sources both for laser engraving and for laser perforation, with CO ₂ lasers or CO lasers advantageously being used for the laser processing of watermark inserts based on thermoplastic elastomers. The latter allow particularly small spot sizes due to the shorter wavelength. Even finer resolutions in laser engraving and perforation can be achieved with lasers in the near infrared or even visible spectral range, whereby solid-state lasers or fiber lasers can be used. Short pulses in the nanosecond range, in the picosecond range or even in the femtosecond range are advantageously used for processing. In the case of the particularly short pulses below a nanosecond, thermal effects are advantageously avoided due to the low energy input.

The laser beam can advantageously be deflected using a galvanometer scanner. The exit optics of the laser are preferably protected by a strong air current because they are located below the material to be processed. At the same time, any gases and residues that are formed are advantageously sucked off well so that they cannot be deposited in the area of the screen.

Even if the use of laser engraving is currently preferred, a mechanical removal process with a scraping or rotating tool can also be used to generate the individual watermark areas. Will the watermark insert raw ings made of a conductive material, the individual watermark areas can also be produced by electroerosion from the raw areas.

• - durch Spritzgießen Wasserzeicheneinsatzrohlinge mit einem Rohbereich für den Serienwasserzeichenbereich und einem Rohbereich für den Individualwasserzeichenbereich erzeugt, und
• - werden durch ein materialabtragendes Verfahren, insbesondere durch Lasergravur, in den Rohbereichen der erzeugten Wasserzeicheneinsatzrohlinge die Serienwasserzeichenbereiche und die Individualwasserzeichenbereiche erzeugt.

Even if it is currently preferred to produce the watermark insert blanks by injection molding with the serial watermark area, in principle the entire molded side of the watermark inserts can also be formed by subsequent material removal or can be machined from a rough mold. In such a procedure

• - produced by injection molding watermark insert blanks with a raw area for the series watermark area and a raw area for the individual watermark area, and
• - The serial watermark areas and the individual watermark areas are produced by a material-removing process, in particular by laser engraving, in the raw areas of the produced watermark insert blanks.

• - durch Spritzgießen Wasserzeicheneinsatzrohlinge mit einer Grobform des Serienwasserzeichenbereich und einem Rohbereich für den Individualwasserzeichenbereich erzeugt, und
• - werden durch ein materialabtragendes Verfahren, insbesondere durch Lasergravur, jeweils die Grobformen zur dem Serienwasserzeichenbereich verfeinert und in dem Rohbereich die Individualwasserzeichenbereiche erzeugt.

If a rough shape for the series watermark area is already specified in a mixed form in the watermark insert blank by injection molding, then in the method

• - produced by injection molding watermark insert blanks with a rough form of the series watermark area and a raw area for the individual watermark area, and
• - the rough forms for the series watermark area are refined by a material-removing process, in particular by laser engraving, and the individual watermark areas are generated in the raw area.

The coarse form typically has a resolution that is 2 to 10 times lower than the refined series watermark area. The demands on the accuracy of the injection molding process are therefore comparatively low. Compared to the processing of the series watermark area from a raw area, however, a prefabricated rough form can be refined with significantly less processing effort and shorter processing time through the material-removing process, in particular through laser engraving.

• - durch Spritzgießen Wasserzeicheneinsatzrohlinge mit dem Serienwasserzeichenbereich und einer Vertiefung zur Aufnahme von Formelementen erzeugt,
• - werden separate Formelemente in Gestalt der Individualwasserzeichenbereiche erzeugt oder bereitgestellt, und
• - werden die separaten Formelemente in die Vertiefung der Wasserzeicheneinsatzrohlinge eingesetzt, um die Individualwasserzeichenbereiche zu bilden.

In an alternative, likewise advantageous method

• - produced by injection molding watermark insert blanks with the series watermark area and a recess for receiving shaped elements,
• - separate shape elements are created or provided in the form of the individual watermark areas, and
• - the separate mold elements are inserted into the cavity of the watermark insert blanks to form the individual watermark areas.

The separate shaped elements are preferably connected to the watermark insert blanks by pressing, gluing or fusing, in particular permanently connected. The mold elements themselves are advantageously cast. The separate shaped elements can be inserted into the depressions of the watermark insert blanks, for example, using a pick-and-place assembly unit.

It can be advantageous here to use only a single shaped element for each watermark insert blank, which has the desired shape of the respective individual watermark area. However, the individual watermark areas can also be formed by a plurality of shape elements, which together form the desired individual watermark area. As a result, under certain circumstances, any desired individualization can be produced with a limited number of different shaped elements. For example, any complex number-based individualization can be generated by ten form elements in the form of the numbers "0" to "9".

In a further, likewise advantageous method, watermark inserts are produced with an injection molding tool of the type mentioned above, each of which has a serial watermark area and an individual watermark area.

Even if the production of the watermark blanks or the watermark inserts by injection molding is currently preferred, the watermark blanks or watermark inserts can also be formed by an additive manufacturing process (also often referred to as 3D printing) as a layer sequence of a plurality of material layers firmly connected to one another.

In general, the proposed solutions are particularly suitable for the production of watermark paper for valuable documents, such as passport paper, visas, certificates or banknotes. In the present description, the term “paper” includes all substrates into which watermarks in the papermaking sense can be introduced. This includes, in particular, fibrous substrates made from natural and/or artificial fibers. In addition to the additional authenticity protection, the procedures described allow the production of individualized watermarks with a complex and visually attractive appearance.

Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, which are not shown to scale and proportions in order to improve clarity.

• 1 schematisch einen Ausschnitt eines zur Papierherstellung eingesetzten Entwässerungssiebs in Aufsicht,
• 2 einen Querschnitt des Entwässerungssiebs der 1 im Bereich eines Einzelnutzens entlang der Linie II-II,
• 3 in (a) bis (c) Zwischenschritte bei einem erfindungsgemäßen Herstellungsverfahren für die Wasserzeicheneinsätze der 1 und 2,
• 4 einen Zwischenschritt bei einem anderen erfindungsgemäßen Herstellungsverfahren,
• 5 in (a) bis (e) Zwischenschritte bei einer weiteren erfindungsgemäßen Herstellungsvariante für die Wasserzeicheneinsätze der 1 und 2,
• 6 in (a) ein erfindungsgemäßes Spritzgusswerkzeug für eine alternative Variante zur Herstellung von Wasserzeicheneinsätzen, in (b) bis (d) die besondere Ausbildung des Reliefwerkzeugs des Spritzgusswerkzeugs von (a), und in (e) ein Querschnitt eines Entwässerungssiebs mit einem mit Hilfe des Spritzgusswerkzeugs von (a) einspritzten Wasserzeicheneinsatz.

Show it:

• 1 Schematic view of a section of a dewatering screen used in papermaking,
• 2 a cross section of the dewatering screen 1 in the area of a single panel along line II-II,
• 3 in (a) to (c) intermediate steps in a production method according to the invention for the watermark inserts 1 and 2 ,
• 4 an intermediate step in another manufacturing process according to the invention,
• 5 in (a) to (e) intermediate steps in a further production variant according to the invention for the watermark inserts 1 and 2 ,
• 6 in (a) an injection molding tool according to the invention for an alternative variant for the production of watermark inserts, in (b) to (d) the special design of the relief tool of the injection molding tool from (a), and in (e) a cross section of a drainage screen with a Injection molding tooling of (a) injected watermark insert.

The invention will now be explained using the example of a dewatering screen for the production of banknotes. 1 shows schematically a detail of a dewatering screen 10 used for papermaking in plan view, and 2 shows a cross section of the screen in the area of a single blank along line II-II of FIG 1 .

The dewatering fabric 10 contains a single-layer or multi-layer carrier fabric 12 with a plurality of individual use areas 14, which each produce one of a plurality of individual uses of the watermark paper during papermaking. In the single-up areas 14, the dewatering screen 10 is provided with a watermark insert 20, which is designed in a partial area 22 as a high-resolution, multi-stage watermark insert.

The watermark inserts 20 of the dewatering screen are formed by perforated injection-molded inserts which, as the variants of the invention described below show, are injected directly into the screen fabric of the carrier screen 12 in the area of a recess 16 either completely or at least with their main component.

As a special feature, the watermark inserts 20 have on the one hand a serial watermark area 22 which is identical for all individual copies 14 and on the other hand each have an individual watermark area 24 which is individualized for each individual copy 14 . For example, the watermark inserts 20 can be used to produce watermark paper for the pages of a passport, in which the page number of the passport page is contained in an individualized watermark area.

In another embodiment, the watermark inserts 20 can be used to produce watermark paper for banknotes, in which the watermarks carry individual information that is specific to the row, column or position of the single-use area 14 on the printed sheet. With modern numbering methods, this position or individualization can be included in the numbering and thus represent a further hurdle for potential forgeries as a mark of authenticity.

Coming back to the presentation of 1 and 2 shows the serial watermark area 22 in the exemplary embodiment a high-resolution, multi-level relief 26, such as a portrait or another graphic motif. In contrast to this, the page number of the individual watermark area 24 is in the form of a binary structure 28 with only two vertical levels. During paper production, the individual watermark area 24 of the watermark insert 20 produces a conspicuous highlight area within the watermark, in which the page numbers in the paper appear as particularly light areas.

To produce such watermark inserts 20, for example, as with reference to FIG 3 be proceeded as described. The starting point is a carrier screen 12 which is provided with recesses 16 in the area of the watermark inserts 20 to be attached. As in 3(a) shown, watermark insert blanks 30 are produced in these recesses by injection molding, which already have the desired high-resolution, multi-stage relief 26 in their serial watermark area 22 .

In contrast, the individual watermark area is not yet structured in the injection-molded blanks 30; instead, the blanks 30 each contain only a raw area 32 that is used to form the desired binary structures has suitable dimensions. The watermark insert blanks 30 with the serial watermark area 22 and the raw area 32 are all identical and can be produced easily and inexpensively using the same injection molding tool.

In an individualization step, the watermark insert blanks 30 injected into the carrier screen are then exposed to laser radiation 34 from the mold side of the blanks in the raw area 32, with the specific binary structure 28 of the respective individual watermark area 24 being produced individually for each blank by laser engraving, as shown in 3(b) shown.

Finally, the carrier screen with the engraved watermark insert blanks 30 is exposed to further laser radiation 36 from the drainage side of the blanks in order to produce a plurality of small drainage perforations 38 in the blanks and thereby complete the individualized watermark inserts 20, as in 3(c) shown. In the individualized area in particular, it can be advantageous not to introduce a continuous perforation, as this creates a particularly bright impression in transmitted light.

In the method described, the drainage perforations 38 are introduced from the drainage side of the blanks 30 in order to be able to produce slightly tapering perforations 38 whose opening on the mold side is smaller the higher the relief structure is formed there. In order to maintain this flexibility, two laser processing units are used for laser processing of the mold side ( 3(b) ) and the laser processing of the drainage side ( 3(c) ) used. Alternatively, only one laser processing unit can be used, which then carries out both the laser engraving of the raw areas 32 and also produces the drainage perforations 38 from the mold side.

The procedure described not only allows the desired individualization of the watermark inserts to be carried out in a simple and cost-effective manner, complex and visually attractive individual watermark areas can also be produced. For example, the individual watermark areas can also be designed as a multilevel structure with 3, 4 or 5 different height levels instead of as a binary structure. Differentiated brightness variations can also be provided within a highlight area due to such different height levels.

A further authenticity feature can be formed in the watermark inserts 20, for example, in that the position of the binary structure 28 within the raw area 32 ( 3(a) ) is varied depending on the information displayed, for example the number of pages displayed.

The arrangement of the drainage perforations 38 can also be matched to the respective position of an individual watermark area 24 and particularly delimit it from the series watermark area 22 or produce smoother transitions. Differences in contrast in the individual watermark area 24 can be supported by varying the arrangement of the drainage perforations 38, for example a greater or lesser density of the perforations 38 produced.

It is also possible not to produce continuous perforations in the individual watermark area. Since some material is removed from the entire surface during perforation on the drainage side, areas that should not be drained to create high contrast differences are nevertheless treated with the perforation laser in order to avoid creating height differences on the drainage side. However, no continuous perforations are produced in these areas, so that no drainage effect occurs there.

The laser impingement for laser engraving of the raw areas and for laser perforation of the watermark inserts can be carried out using a CO ₂ laser, for example. The wavelength of 9.4 µm, which is otherwise rather unusual for CO ₂ lasers, has proven advantageous for watermark inserts based on thermoplastic elastomers.

Regarding 4 the relief of the mold side of injection-moulded watermark insert blanks 40 can also be produced completely by subsequent laser engraving, ie by laser engraving of watermark insert blanks that are already present in the carrier screen. Both the specific binary structure 28 of the respective individual watermark area 24 (laser radiation 34-A) and the high-resolution, multi-level relief 26 of the serial watermark area 22 (laser radiation 34-B) are formed by laser treatment 34 of the form side.

In addition, mixed forms are also possible, in which, for example, watermark insert blanks are first produced in the carrier screen by injection molding. In the subsequent laser engraving step, the specific binary structure 28 of the respective individual watermark area 24 is generated in the raw area 32 and in the same processing step the rough form for the high-resolution, multi-stage relief 26 of the series water character area 22 refined. Such a mixing method is particularly useful if the watermark insert is to contain smooth transitions between the individual watermark area and the serial watermark area.

The subsequent generation of dewatering perforations can also from the mold side or, as in connection with the 3 described, take place from the drainage side of the blanks.

Another manufacturing variant for the watermark inserts 1 and 2 is in 5 illustrated. Regarding 5(a) watermark insert blanks 50 are first produced in the recesses 16 of the carrier screen 12 by injection molding, which have the desired high-resolution, multi-stage relief 26 in their serial watermark area 22 . Instead of the individual watermark area, the body 52 of the blanks 50 each have a depression 54 for receiving shaped elements 60 in the form of the desired binary structures 28 . The watermark insert blanks 50 with the series watermark area 22 and the depression 54 are therefore all identical and can be produced easily and inexpensively using the same injection molding tool.

In order to form the individual watermark area of the watermark inserts, individual plastic mold elements 60 with the desired binary reliefs have already been cast in advance, as shown in 5(b) shown. These individual mold elements 60 are then inserted, for example with a pick-and-place assembly unit, into the depressions 54 of the respective watermark insert blanks 50 in order to form the binary reliefs 28 of the individual watermark areas 24, as shown in FIG 5(d) shown. The connection of the shaped elements 60 to the watermark insert body 52 can take place, for example, by pressing, gluing or fusing.

Instead of using a single shaped element 60, the individual watermark area 24 of the watermark inserts can also be formed by a plurality of shaped elements 61, 62, 63, which together form the desired binary relief 28 of the individual watermark area 24, as shown in 5(c) illustrated. For example, in the case of numerical individual information such as a page number, the form elements 61, 62, 63 can represent the required digits or digit components, so that any desired page number or any desired individual information can be compiled with a limited number of different form elements.

After inserting the mold elements 60, the watermark inserts including the mold elements 60 are exposed to laser radiation in order to produce the drainage perforations 38 of the blanks and thereby complete the individualized watermark inserts 20, as in FIG 5(e) shown.

An alternative variant for the production of the watermark inserts 1 and 2 will now be referred to 6 explained. The figure shows in 6(a) an inventive injection mold 70 for injecting a watermark insert 20 into the carrier screen 12 of 1 and 2 .

The injection molding tool 70 contains a nozzle tool 72 as the upper part of the injection molding tool and a relief tool 80 as the lower part of the injection molding tool. The nozzle tool 72 and the relief tool 80 form an injection molding cavity 74 between them in the region of a recess 16 of the carrier screen 12, into which plastic is injected to produce the watermark set 20.

The nozzle tool 72 is formed in the form of a flat plate, on the underside of which is formed a nozzle tool cavity which is connected to a nozzle opening 76 arranged on the upper side of the nozzle tool 72 for injecting plastic. The relief tool 80 is also designed in the form of a flat plate, the relief tool 80 having a watermark relief with a series area 82 and an individual area 84 on its upper side in the area of the injection molding cavity 74 .

The series area 82 is formed by a high-resolution watermark relief 86 in the form of the inverted relief 26 of the desired series watermark area 22, while the individual area 84 is provided with a binary relief 88 in the form of the inverted binary relief 28 of the desired individual watermark area 24.

The special design of the relief tool 80 is in 6(b) to (d) illustrated in more detail. The relief tool 80 has a depression 90 ( 6(b) ) into the detachable fittings 92, 93, 94 ( 6(c) ) can be used, which together form the binary relief 88 of the individual area 84. The shaped pieces 92-94 can represent a limited number of shaped pieces, similar to a type case in letterpress printing, from which any desired individual information, for example a page number, can be assembled ( 6(d) ).

The procedure described allows the injection molding tool 70 with the nozzle tool 72 and the relief tool 80 to remain in the apparatus as such; only the molds 92-94 have to be exchanged in order to produce a watermark insert 20 with different individual information.

The indentation 90 of the relief tool can be formed by round bores, for example, or it can be freely shaped. In the exemplary embodiment, the shaped pieces 92-94 are accommodated in the recess 90 in a detachable manner by pressing. Seals can also be provided in order to prevent plastic from flowing in the depression 90 behind the shaped pieces 92-94 during injection, which would have to be laboriously removed again during subsequent casting.

Coming back to the presentation of 6(a) After inserting the required shaped pieces 92-94 into the relief tool 80, the two tools are moved to the desired recess 16 in the carrier screen 12 and brought together in the vertical direction so that they receive the dewatering screen 10 between them in the area of the recess 16 with a predetermined pressure. The injection molding tool 70 here forms the injection molding cavity 74 already mentioned, which is delimited on its underside by the watermark relief 86 , 88 of the relief tool 80 .

By injecting plastic into the injection molding cavity 74, a watermark insert 20 is created that is injected directly into the drainage screen 10. After the injection molding tool 70 has been removed, the drainage screen 10 contains the watermark insert 20 in the recess 16 with the desired high-resolution relief 26 and the desired individualizing binary structure 28, such as in 6(e) shown.

The watermark insert 20 is then also exposed to laser radiation in order to form the drainage perforations, as already described above.

Reference List

10

dewatering screen

12

carrier screen

14

individual use areas

16

recess

20

watermark insert

22

series watermark area

24

Individual watermark area

26

high-resolution, multi-level relief

28

binary structure

30

watermark insert blank

32

raw area

34, 34-A, 34-B

laser radiation

36

laser radiation

38

drainage perforations

40

watermark insert blank

50

watermark insert blank

52

watermark insert body

54

deepening

60

feature

61, 62, 63

form elements

70

injection molding tool

72

nozzle tool

74

injection molding cavity

76

nozzle opening

80

relief tool

82

serial range

84

individual area

86

high-resolution watermark relief

88

binary relief

90

deepening

92, 93, 94

fittings

QUOTES INCLUDED IN DESCRIPTION

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Patent Literature Cited

• DE 102006058513 A1 [0004]

Claims (17)

Dewatering wire for the production of paper with high-resolution watermarks, with a carrier wire with a plurality of individual use areas, which each produce one of a plurality of individual use areas of the watermark paper during papermaking, the drainage wire being provided with its individual use areas with watermark inserts, which at least in some areas as high-resolution multi-stage watermark inserts are formed, characterized in that the watermark inserts each have a serial watermark area which is identical for all individual copies and an individual watermark area which is individualized for each individual copy. dewatering screen after claim 1 , characterized in that the individual watermark area has an individualization in the form of patterns, characters or a code, in particular a sequence of letters or numbers. dewatering screen after claim 1 or 2 , characterized in that the individual watermark area generates a highlight area of the watermark, the information of which appears particularly light in the watermark paper. Dewatering screen according to at least one of Claims 1 until 3 , characterized in that the individual watermark area is formed by a binary structure or a multilevel structure with 3, 4 or 5 different levels. Dewatering screen according to at least one of Claims 1 until 4 , characterized in that the serial watermark area of the watermark inserts is formed by a high-resolution, multi-level relief with 6 or more vertical levels. Dewatering screen according to at least one of Claims 1 until 5 , characterized in that the individual watermark area takes up less than 50%, advantageously less than 25% and in particular less than 15% of the area of the watermark insert. Dewatering screen according to at least one of Claims 1 until 6 , characterized in that the individual watermark area is formed by a laser engraved area of the watermark insert. Dewatering screen according to at least one of Claims 1 until 7 , characterized in that the watermark insert in each case has a watermark insert body with a recess into which one or more shaped elements are inserted in order to form the individual watermark area. Dewatering screen according to at least one of Claims 1 until 8th , characterized in that the series watermark area is formed by an injection molding relief. Dewatering screen according to at least one of Claims 1 until 9 , characterized in that the watermark insert is in each case a perforated injection molded insert. Dewatering screen according to at least one of Claims 1 until 10 , characterized in that the watermark inserts are provided with drainage perforations, the arrangement of which is matched to the relative position of the individual watermark area in the watermark inserts. Injection molding tool for producing high-resolution, multi-level watermark inserts, each having a series watermark area and an individual watermark area, the injection molding tool containing an injection molding cavity with a series area and an individual area, the series area of the injection molding cavity being provided with a high-resolution watermark relief in the form of the inverted relief of the desired series watermark area, and the individual area of the injection molding cavity is provided by a recess with detachably inserted moldings in the shape of the inverted relief of the desired individual watermark area. Method for producing a dewatering screen, in particular according to one of Claims 1 until 11 , in which - a carrier screen is provided, which has a plurality of individual use areas, which each produce one of a plurality of individual use areas in the watermark paper during paper production, - watermark inserts are introduced in the individual use areas of the carrier screen, - the watermark inserts are each formed with a serial watermark area , which is identical for all individual copies, and are formed with an individual watermark area which is individualized for each individual use, as a result of which the watermark inserts are formed at least in partial areas as high-resolution multi-stage watermark inserts. procedure after Claim 13 , characterized in that - watermark insert blanks with the series watermark area and a raw area for the individual watermark area are produced by injection molding, and - the individual watermark areas are produced by laser engraving in the inserted watermark insert blanks. procedure after Claim 13 , characterized in that - watermark insert blanks with the series watermark area and a depression for receiving shaped elements are produced by injection molding, - separate shaped elements are produced or provided in the shape of the individual watermark areas, and - the separate shaped elements are inserted into the depression of the watermark insert blanks to form the individual watermark areas to build. procedure after Claim 14 or 15 , characterized in that the watermark insert blanks are injected directly into the carrier screen. procedure after Claim 13 , characterized in that with an injection mold according to claim 12 Watermark inserts are generated, each having a series watermark area and an individual watermark area.

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