EP0330733B1 - Thread- or strip-like security element to be included in a security document, and a method of manufacturing same - Google Patents

Abstract

Security element in the form of a thread (1) or a ribbon for insertion into security documents such as banknotes, cheques, securities, credit and identity cards or the like, comprising characters, patterns, etc., which can be rendered visible by transparency and/or read by a machine. Said element consists of a translucent plastic film (2) covered by an opaque coating (3) and having recesses (4) shaped like the characters or patterns to be applied. Said element also comprises colouring and/or luminescent substances, in the regions coinciding with the recesses, which make it possible under suitable lighting conditions to distinguish the characters and/or patterns from the security document and from the opaque coating by means of contrasting colours.

Description

The invention relates to a security element in the form of a thread or tape for embedding in security documents such as bank notes, checks, securities or the like with visually and / or machine-readable characters, patterns etc. visible in transmitted light, and to methods for producing security documents of this type.

It has long been known to secure banknotes and other monetary documents such as checks, shares, travelers checks, check and credit cards, but also passports and identity cards by inserting so-called security threads. Papers of this type are referred to below as security papers. The security threads used for this purpose consist of various materials in the form of fine ribbons, which are inserted into the paper sheet in widths of 0.4 to 2 mm during its manufacture. They are mainly made of plastic films, which are coated with metal foils, printed, colored or z. B. are provided with pigment-shaped substances. In addition, it is also known to impart magnetic, fluorescent, X-ray absorbing and other properties to these security threads by applying appropriate substances.

The use of security threads with microprint images has proven to be particularly advantageous, this microprint being able to contain information that is readable by the eye or only machine-readable.

With regard to the protection against counterfeiting, security threads with metallic reflecting surfaces have also proven to be particularly useful, since such threads inserted inside the paper are almost invisible in the incident light, since the light rays penetrating through the upper paper layer are completely reflected on the metallic surface and the paper is diffusely scattered leave again. In contrast, such threads appear in transmitted light as black stripes that stand out clearly from their surroundings. Threads of this type cannot be imitated by printing on the paper. On the other hand, they show the disadvantage that by inserting thin aluminum foils between two layers of paper, a corresponding impression can also be erroneously produced. It has therefore already been proposed to provide such aluminum-vapor-coated security threads with a micro script (DE-A-14 46 851). In practice, however, this has proven to be of little use, since this writing on the otherwise opaque security thread is not visible in transmitted light and is very difficult to recognize in incident light. It is usually necessary to make the paper transparent at least for the time of the test using chemical agents. The execution of such micro fonts in special, e.g. B. fluorescent, colors has proven in the same way and for the same reasons to be less advantageous.

A security thread is now known from DE-B-22 05 428, which, designed as a metal strip, has a machine-readable and / or visually readable coding introduced by means of a laser. The labeling of this thread, which may also contain alphanumeric characters, consists of through holes (perforations), the diameter of the holes or the “line width” should be small compared to the thickness of the metal strip in order to make it difficult to copy.

The characters of this security thread are recognizable as only faintly visible lighter areas due to the extremely small stroke width compared to the dark background. In addition, the effort to produce such inscriptions is relatively large, since powerful lasers are required to make the perforations in the metal thread. The perforation of the security thread material, however, is so time-consuming that this method of producing large quantities (thousands of kilometers) cannot be used solely for reasons of time and therefore also for reasons of cost.

From US-A-4,652,015 a security thread was also known, which is to be used for banknotes and the like and on which shiny metallic micro characters are provided on clear, transparent film material. The security thread described in this patent or the micro-characters on it are not recognizable in incident light. In transmitted light, however, only the characters can be recognized as sharply contoured characters, since the security thread itself is transparent. Such a security thread is produced by vapor-coating a transparent film with a thin aluminum layer over a large area, then printing this layer with the micro-characters using an acid-resistant printing ink and then etching away the unprinted areas, whereupon the characters remain on a transparent background.

In the transmitted light, the viewer only sees a lettering that runs through the banknote. The disadvantage, however, is that it is difficult to find due to the small size of the characters, its embedding in the paper mass and possibly a printed image above it. The thread as such is no longer visually recognizable and, because of the extremely thin design required here, it is also not tactile as an unevenness in the paper surface. These identification features that actually characterize a security thread are therefore no longer present in the known thread.

From the earlier application EP-A-0 319 157, which is not relevant for the countries AT, BE and LU, a security thread is known which has an opaque metallic coating. This coating is partially removed again in the form of characters. The edge areas of the thread remain unprocessed in any case, i. H. metallized throughout. This metallized thread can additionally be provided on one or both sides with colored luminescent or dichroic layers. Special processes for the production of this thread are not described in the application mentioned.

The invention is based on the object of creating a new security element which can be found more easily in a security document, is easier to read and which shows different visual effects in reflected light and transmitted light.

This object is achieved by the features mentioned in the characterizing part of claims 1, 10, 12 and 16. Further developments of the invention, which are directed to a film material, a security document and a method for producing a security element or a film web, are the subject of subordinate and secondary claims.

In a preferred embodiment, the security thread consists of a transparent plastic film which is provided with a metal coating on one side. Characters are introduced into this reflective, opaque metal coating in transmitted light by locally removing the coating material. In addition to this metal coating, the thread is coated with a color that can extend over the entire surface of the thread. The colorants used have no covering effect and are preferably glazing printing inks in different colors and tints. However, the plastic film can also be colored with appropriate colorants in such a way that transparency is retained in a part of the visually accessible spectrum.

If you look at such a thread after it has been embedded in paper or only white, translucent plastic material, such as is used in part for the production of ID cards or credit cards, the thread itself is easily recognizable as a dark stripe in the document and the characters and patterns stand out from their immediate surroundings, the opaque thread coating and additionally from the wider surroundings, the white paper or plastic material, as bright, colored areas. The thread is in the document very easy to find and the characters are clearly recognizable due to their contrasting effect with the surroundings and can be read at any time with the appropriate font size even without tools.

While the characters appear in transmitted light as colored characters against the dark or white background, the thread in reflected light is not, or at least only very slightly, visible due to the highly reflective metal coating and the use of glazing or non-opaque colorants. This means that it cannot be imitated by an external print, which is inevitably always clearly visible in both reflected and transmitted light.

In addition to metal layers, other opaque coating materials are also other non-metallic layers which contrast in color and / or in gray tone when viewed in transmitted light, such as. B. opaque, preferably white layers of paint, shiny metallic layers such. B. titanium nitride, interference layers such as z. B. are known from US-A-3,858,977.

By using luminescent colors, the visual impression of this thread can be further improved and carried out more effectively. The luminescent colors can either be colorless in the non-excited state or have a body color that preferably differs from the color of the emission light. The characters or patterns only appear colored in the excitation light or change their color when the thread, e.g. B. under UV light. Several luminescent substances emitting in different colors increase both the design possibilities and the security against forgery, since the analysis of each individual luminescent substance is necessary for exact imitation. This analysis can be made even more difficult in a simple manner by mixing or printing the different luminescent colors.

Various color effects can also be achieved using diffraction gratings or holograms. The diffraction structures are e.g. B. as volume or embossing holograms directly as embossments in the carrier material of the plastic thread before or in an additional layer.

The reflective metal layer present in the case of reflection holograms or gratings is preferably interrupted here for the generation of a lettering or pattern visible in transmitted light by one of the methods mentioned below.

Such a thread is preferably embedded in the document in such a way that it is directly visible at least in places or appears on the surface. Methods for embedding in the security under window formation in the security thread area are e.g. B. known from DE-A-36 01 114. With a thread embedded in this way, the hologram diffraction grating or reflection pattern is predominantly visible in the reflection in the window area, while the negative writing or negative pattern incorporated into the metal coating dominates when viewed in transmitted light.

For the production of security threads z. B. dyed, printed and / or luminescent, but in a part of the visually accessible spectrum transparent plastic films are initially vapor-coated with a thin aluminum layer. The cutouts in the form of the desired characters and patterns are then introduced into this metal layer using known methods (etching, spark erosion, etc.). The thread produced in this way then shows the desired properties. When using spark erosion (also electrical erosion It is advantageous if the electrodes already have the shape of the characters and patterns to be applied. In this way, extremely fine micro characters can be produced in good quality.

According to a preferred production method, the means known in principle from printing technology are used for the creation of the characters and patterns, and the characters and patterns are printed onto the metal-coated side of the film using known microprinting methods. However, a printing ink is used, the z. B. has thermoplastic properties, d. H. softens and becomes sticky at higher temperatures. If a film pretreated in this way is laminated against a second untreated film web using heat and pressure, the two films adhere to one another in the area of the printed characters or patterns. When the two films, which have cooled in the meantime, are separated, the areas corresponding to the characters or patterns are then released from the aluminum coating. In this way, a metal material is deposited on the foil material, in which characters or patterns in the form of translucent colored dots or lines are obtained in the otherwise opaque light-reflecting surface.

It is advantageous if, before carrying out the method described above, the film provided for the production of the security thread is first provided with a primer in the form of a printing ink and then the vapor deposition is applied to this primer. In this case, instead of using colored foils, the primer can be applied in the form of a colored and / or luminescent surface.

In a further embodiment, this colored primer can also be designed in the form of a multicolored printed image. B. results in a random distribution in the coloring of the individual characters. It can be used to create threads that have a shimmering micro script that appears bright in many colors on a black background.

In a further embodiment, the film material can first be provided with the colorless primer, while the colored, transparent ink layer is applied to the opposite side of the film. This process offers advantages if different printing ink qualities have to be used for the primer and colored transparent layers. After subsequent metal vapor deposition of the primer, further processing can be carried out in the above form.

The hot stamping method known per se can also be used advantageously for the selective metal coating of colored or printed security threads. This method can be used advantageously in particular in connection with "light collecting foils", so-called LISA foils, as foil material. These foils have the property of "collecting" incident light and allowing it to emerge in a certain color and only in edge areas or at imperfections on the surface (embossing). Since the characters or patterns are to be embossed into the film for the hot embossing process and these embossed structures represent such defects, the characters appear with a luminous edge contour. With LISA foils with daylight fluorescent properties, colored light effects are also visible in daylight.

According to a further method, a printed image is first printed on the foils, as it will later appear as a negative image in the metal coating, and only in a second process step is the opaque coating z. B. applied the metal coating. For the application of the printed image, printing inks or lacquers are used which have low adhesion either to the film and / or to metal coatings, so that either the metal coating alone or together with the printing ink can only be removed mechanically in an air or liquid jet. This method is used for the production of packaging materials and is known in principle from DE-A-36 10 379. Instead of the liquid jet, mechanical scrapers can also be used to remove the poorly adhering printing ink. More advantageous than the above The process is to use printing inks, which can then be chemically dissolved under the metal coating. However, it turns out that the dissolving of the printing ink is generally not completely sufficient for a complete removal of the metal layer in the entire printing area. However, if an ultrasound source is introduced into the solution bath or the film is drawn through an ultrasound bath after the solution bath, the printing film is completely removed in a simple process.

According to a further process variant, printing inks are used which become brittle during drying. If you pull the printed and then metal-coated colors through an ultrasound bath, these colors are removed even without a chemical solution process solely by the action of the ultrasound fur, which creates the desired negative lettering in the metal coating. Suitable colors are z. B. Colors based on a Novolack binder. The ultrasonic bath is in this case a liquid container with an ultrasound generator arranged therein or thereon, the liquid taking over the role of the coupling medium and in the simplest case water can be used for this.

Further advantages, advantageous developments and methods for producing security threads according to the invention are the subject of the description of the subject matter of the invention with reference to figures. For the sake of clarity of the actual facts, the figures are not drawn to scale and proportion.

Fig. 1

einen erfindungsgemäßen Sicherheitsfaden in der Aufsicht,

Fig. 2

den Sicherheitsfaden in einer Schnittdarstellung nach Einbettung in einen Papierträger,

Fig. 3 - 7

verschiedene Ausführungsformen eines erfindungsgemäßen Sicherheitsfadens,

Fig. 8 - 10

verschiedene Verfahren zur Herstellung derartiger Sicherheitsfäden, dargestellt in den verschiedenen Verfahrensstadien.

The figures show:

Fig. 1

a security thread according to the invention in supervision,

Fig. 2

the security thread in a sectional view after embedding in a paper carrier,

3 - 7

different embodiments of a security thread according to the invention,

8-10

different processes for the production of such security threads, shown in the different process stages.

Fig. 1 shows a security thread 1, consisting of a plastic tape 2 (Fig. 2) made of a tear-resistant plastic material, such as. B. polyester, one surface of which is provided with an opaque coating 3. The coating is preferably a reflective metal layer, e.g. B. aluminum layer, or a white opaque, in opaque appearing, color application that has the recesses 4 in the form of the signs and patterns to be applied to the security thread. In both In some cases, this coating is not visible in incident light after embedding the thread in security paper 5 (FIG. 2), since the light reflected from the metal surface is again diffusely scattered in the paper or the white color layer does not stand out from the white paper pulp. The recesses in this opaque coating can therefore only be recognized as bright areas when viewed in transmitted light.

In the example shown in FIGS. 1 and 2, the plastic film 2 is colored with preferably organic dyes, which reduce the translucency of the film in a part of the visually accessible spectrum. Films with similar properties are used e.g. B. used in optics as a filter. Depending on the coloring of the film, the characters appear in a certain color when viewed in transmitted light and not only stand out from the opaque black coating, but also contrast in color with the usually white paper layer.

The dyes can be supplemented or also replaced by luminescent substances, so that the characters light up in color or appear in a different color only when stimulated accordingly. If the luminescence is sufficiently strong, the thread is also visible in incident light. If you look at the thread from the side of the metal coating, the characters are recognizable, while when looking from the opposite side and the arrangement of the excitation light source on the observer side, the thread is visible as a homogeneous fluorescent band. This property can be used as a further authenticity indicator.

Instead of the coloring of the plastic film shown in FIG. 2, a completely transparent film can also be provided with a color layer 8 which, for. B. on the the surface opposite the metal coating 3 is applied (FIG. 3) or is introduced as a primer layer between the metal layer and the film (FIG. 4). The separate application of this color layer 8 makes it possible to apply a multicolored printed image in any pattern, as a result of which the characters also appear in different colors and patterns. Standard transparent transparent films can then be used as films. The print samples can be adapted to the respective application. So it offers z. B. on security threads that are embedded in banknote paper, select the colors according to the respective national colors.

FIG. 5 shows a further embodiment, in which the colorants and / or luminescent substances 9 are only present in the area of the cutouts 4 of the metal coating 3. Suitable colorants are z. B. glazing printing inks, which were printed in the recesses of an opaque white color layer or a metal coating.

Fig. 6 shows a security thread, consisting of a transparent plastic film 7 and a cover layer 30 in the form of an optical interference filter as z. B. is known from US-A-3,858,977. This cover layer has local interruptions 31 to represent a pattern, characters, numbers, etc. This interference filter has the property that the color changes when changing reflections in transmission.

If these threads are incorporated into the security, the thread preferably being stored in such a way that it appears at least partially on the surface, the pattern or the lettering, when viewed in reflected and transmitted light, is in each case against a differently colored background visible. If the film 7 is dyed in a third color or an additional layer of color is applied, then a color interplay results from these colors and the mixed colors.

The security thread can also with optically varying structures such. B. holograms, diffraction gratings, three-dimensional reflective structures, the at least visible through negative lettering in the reflection hologram z. B. already existing reflective metal layer or in the existing in volume holograms opaque coating or layer.

7 shows a simple embodiment of such a security thread. The carrier material is a tear-resistant embossable plastic film 40, and composite films can also be used to achieve these two properties. This film is provided with a reflective opaque metallic coating 41, into which a negative lettering or pattern is preferably introduced by one of the methods mentioned below. Then the optically active structures 43, such as. B. holograms, diffraction structures, reflection patterns in the form of the document plane differently inclined surfaces etc. imprinted in the metal-coated surface. An additional transparent protective layer 44 protects these structures and the metal coating against external mechanical and chemical influences.

So that the optically effective structures are at least locally well visible even in the case of a security thread embedded in paper, the thread is stored in such a way that the thread at least partially comes to the paper surface. Methods for this are e.g. B. already known from the writings mentioned. Also the ones described above other embodiments of security threads can, if necessary, be embedded in the document paper as so-called window security threads using one of these methods.

Methods for producing security threads with lettering or patterns as a negative in an opaque coating are described in more detail below:
According to a preferred method, a z. B. colored, transparent film is first printed with the printed characters and then the film is exposed over the entire surface of a metal vapor deposition. If the printing ink is selected so that the adhesive effect between the printing ink and the plastic film is less than the adhesive effect between the metal vapor deposition and the film, the metal coating in the printed areas can be removed with the aid of an adhesive tape of suitable adhesive strength. The following example:

example 1

A 23 µm thick polyester film (eg Melinex from ICI) is printed using the gravure printing process using the gravure printing ink shown below. The printed film is then vapor-coated with aluminum with a thickness of 1 µm. Finally, the vapor-coated film is pressed against a commercially available adhesive tape, the locations of the vapor deposition corresponding to the characters being torn out at the previously printed locations due to the low adhesion of the aluminum layer there. In this way, a color-transparent lettering or symbol appears on the otherwise opaque aluminum layer. The printing ink corresponds to the wording below.
100 g ethyl alcohol
20 g Movital B20H (Hoechst company)
0.3 g of an alcohol-soluble dye (e.g. neozapone blue from BASF).

According to a further method (Fig. 8) serving as a carrier film, for. B. colored, transparent plastic film 2 made of polyester first over the entire area on at least one surface with a metal coating 3, z. B. aluminum. The desired characters and patterns are printed on this coating, a thermoplastic plastic ink being used as printing ink 11, which in the softened state has an adhesive effect and binds intimately to the metal coating (FIG. 8a). After cooling, d. H. When the thermoplastic printing ink hardens again, the adhesive effect between the printing ink and the metal coating should be greater than between the metal coating and the carrier film. If the film 2 pretreated in this way is laminated under heat and pressure to film 12, to which the thermoplastic printing ink 11 also adheres well, and if these two films are separated after cooling, the metallic coating 3 is also removed locally with the printing ink 11 (FIG. 8b). . The metal coating 3 remaining on the security thread 1 then shows the cutouts 4 corresponding to the characters and patterns (FIG. 8c).

Suitable printing inks and process parameters to be observed can be derived from the following description of specific examples.

Example 2

A polyester film 23 µm thick (eg Hostaphan from Hoechst) is coated over the entire surface with the formulation given in Example 4. Subsequently an aluminum layer of 1 µm thickness is applied to this formulation by vacuum evaporation. Finally, characters or symbols are printed on the vapor-coated layer using an intaglio cylinder, using the following hot-melt printing ink.
100 g distilled water
60 g Vinnol dispersion 50/25 C (from Wacker)
1 g of Tylose MH 16000 K (Hoechst company).

After printing, the material can either be rolled up first and then processed later, or the next processing step can be added immediately without rolling up. In this subsequent work step, the printed film is pressed against an otherwise untreated hostaphane film of the same type and the press rolls are heated to a temperature of 160.degree. The characters applied with hot-melt lacquer soften. The compressed film combination is then passed over a chill roll and then both films are separated and rolled up separately. During the hot-pressing process, the aluminum-vapor-coated layer sticks to the additional polyester film by means of the hot-adhesive printing characters. During the subsequent cooling and separating, the parts of the aluminum coating corresponding to the characters are torn out and let the desired lettering or the characters appear transparently in the otherwise opaque aluminum layer.

For the color design of the characters, a correspondingly colored plastic film can in turn be used or the film can be provided with a single or multi-colored layer of color with or without luminescent properties before or after the characters are applied.

Example 3

A polyester film (eg Melinex from ICI) is first vacuum-coated with an approximately 1 µm thick layer of metallic nickel. The vapor-coated film is then printed on the opposite side with a four-color pattern using common gravure inks. In the same print run or in a second print run attached later, the nickel-coated side is finally printed with colorless characters using the previously mentioned hot-adhesive printing ink. The film printed in this way is hot pressed with the metal-vapor-coated side against a second polyester film, then cooled and then the two films are separated again. The metallic nickel is torn out at the points printed with the hot-melt ink, so that the characters printed with this color appear as brightly transparent points in the otherwise opaque thread. At these points, the four-color printing applied to the back can be seen, so that a multicolored pattern is created in the transmitted light, which is practically not visible in the incident light on the metallized side and is weakly recognizable as a colored band on the opposite side.

Example 4

A 23 µm thick polyester film (eg Hostaphan from Hoechst) is vacuum coated on one side with 1 µm aluminum. The opposite side of the film is printed over the entire surface in an intaglio printing process with a printing ink which is colorless in daylight but light blue under UV light. Then the metallized side of the film is printed with a hot-melt ink according to the previous example. The subsequent hot pressing, cooling and separating the foils in turn create transparent characters in one otherwise opaque web, which can be seen in transmitted light as brightly colorless fonts or patterns. If you embed such a material e.g. B. in a banknote paper, it will be practically invisible from both sides of the paper in the striking light. A dark streak appears in the transmitted light, in which the characters appear bright. If you additionally illuminate with ultraviolet light, the material introduced appears bright blue on one side, while blue illuminated signs appear in the transmitted UV light on the other side.

Another method, which allows the creation of bright-looking fonts on otherwise less translucent and therefore dark-looking surrounding material in the simplest possible way, consists in a carrier material, for. B. a polyester film of commercial quality, first to print with the desired characters and then to provide a metal coating. The film thus produced is then passed through a solvent which can dissolve the printing ink. Appropriate solvents can easily penetrate the metal layer and penetrate into the ink layer underneath. This leads to swelling and then dissolution of the printing ink under the metallized layer. The sole action of the solvent usually does not lead to the desired success. It has now been found that the dissolving effect is effectively supported if an ultrasonic field is simultaneously irradiated into the solvent bath, which acts directly "acoustomechanically" on the color and also ensures thorough mixing and swirling of the bath.

With the help of this ultrasound field, the color layer together with the metallization on it can then be completely removed. This method is also suitable for the local removal of other coatings. So z. B. coatings soluble in acids or alkalis such. B. the acid-resistant metallic shiny titanium nitride TINX can be used for the production of characters in an opaque coating.

This, as well as the aforementioned methods, also offer the advantage that printing ink only has to be used for the actual bright-looking characters appearing in the printing and the removal of the printing ink can be accomplished practically simultaneously or directly in succession using solvent and ultrasonic energy. The pollution of the environment with chemicals can be kept particularly low in this way. The substances contained in the printing ink can be separated off by precipitation or evaporation and, if necessary, reused. The solvents can of course be reused after vapor deposition and also do not pollute the environment. The quantities of substance resulting from the applied metal layer are small and can also be removed in a simple manner by filtration.

Another advantage is that fine lettering with very well-defined edges can be obtained while the rest of the surface remains completely intact. The materials produced in this way therefore have a particularly well-defined and error-free appearance, which is particularly advantageous when used as security elements with micro-writing.

The printing inks used to produce the characters can be of the simplest formulation. Printing inks of this type need in no case have any special properties or durability, compatibility, acid or alkali resistance, since they only are temporarily needed in the manufacturing process and their only purpose is to redissolve in the solvent. It is therefore sufficient to use an inexpensive, conventional binder for printing inks.

Example 5

An 8% solution is made from a 30A nitrocellulose and ethyl alcohol. This solution is made using any dye, e.g. B. Neozapon blue colored at will.

Using the above printing ink, any lettering is printed on a polyester film of the type RGH 23 (manufacturer Hoechst) using the gravure printing process. The film printed in this way is then vacuum-coated with aluminum with a thickness of 0.2 µm on the printed side.

Then ethyl alcohol is added to an ultrasonic bath and the ultrasonic generator is switched on. The printed and vapor-coated film is immersed in the ethyl alcohol for one second and then removed and dried. It follows that the printing ink and the aluminum present above have been removed from the printed areas and only at these locations. In an otherwise opaque surface, the film has the lettering as clear, transparent areas.

The known hot stamping process can also be used to produce security threads according to the invention (see plastics 72 (1982), 11 "hot stamping, a modern process for decorating plastic parts" by H. Schütt and B. Seeberger, Fürth, pages 701-707) . If the roll-off process is used, the characters and patterns are first embossed into the plastic films 13 (FIG. 9), so that these are present as recessed areas 14 in the film surface. The metal coating 15 of a transfer belt 16 is then transferred to the raised area 17 of the plastic film surface with the aid of a heated silicone embossing roller (not shown in the figure) (FIG. 9a). The lower-lying areas 14, which represent the characters, are left blank by a coating 18 (FIG. 9b). As shown in the aforementioned examples, the plastic film 13 can be colored again or preferably be provided with corresponding printed patterns on the back. In addition to the transfer of metallic color layers, the hot stamping process also allows the use of sublimable colors, which evaporate during transfer and penetrate into the plastic film material. This significantly improves liability.

Particularly in connection with the hot stamping process, light-collecting foils, so-called LISA foils, can also be used in a preferred form (plastics 75 (′85) 5, “plastics that collect light”, pages 296-297, Dr. A. El Sayed). These LISA films are characterized in that they usually contain luminescent substances that can be activated by daylight and that the "collected" light can only emerge in the edge area or at imperfections on the surface. Such defects are e.g. B. the edge areas of the embossed characters. If one uses such LISA foils as carrier foil for the security thread and coats them after the hot stamping process with an opaque metal or color layer with the exception of the recessed character areas, these characters not only appear as bright characters against the opaque background, but shine brightly in the edge area on, this light phenomenon can be varied by appropriate choice of the LISA film or the luminescent substances contained therein in the color, intensity and the necessary ambient light (daylight, UV).

When the threads are produced, in particular if one of the above-mentioned methods is used, wide film webs are preferably first coated and labeled in the desired security thread pattern. Only after these process steps have been completed are the film webs cut into individual threads. Methods for register-accurate printing and cutting of these films are e.g. B. is known from EP-A 0 238 043.

In the security thread 1 shown in FIG. 10, the opaque coating 3 is in the edge area in the form of a machine-readable coding 20 z. B. interrupted in the form of a regularly repeating bar pattern. This coding can be applied in addition or as a replacement for the human-readable lettering 21. The information introduced via this coding can e.g. B. the banknote value or also a random information by which the thread is individualized. By linking this random information with other document- and / or user-specific data, this thread - in a form that can no longer be exchanged - is bound to the respective document and / or user.

Security threads which have a machine-readable coding in the edge region are known in principle from DE-A-28 08 552, but here the entire thread is cut along an edge in the desired shape. This cutting of the threads is quite complex and also their embedding in the paper is problematic, since the threads twist easily due to the constantly changing bandwidth (garland effect) and also very often tear under the inevitable tensile stress that is present in the paper mass during storage of the thread . Since the paper sections in which the thread is not flat or not in the correct position in the paper or the thread storage is even interrupted, the storage of such threads must be discarded burdened with a high reject rate. These disadvantages are eliminated in the solution according to the invention. The thread according to the invention has a constant thread width, since here only the thin opaque coating, but not the thread or plastic carrier, is varied in width. The coding, which can be printed on a transparent plastic film by one of the aforementioned methods or in a simple manner, is perfectly legible in transmitted light due to the transparency of the film material and the opacity of the coating in the same way as a cut thread.

If you use colored or color-primed carrier films, the transparent (not printed) film area stands out as a negative coding pattern that runs parallel to the opaque coding. When using only luminescent colors that are only luminescent with UV light or other special light sources, this color effect only appears with special lighting. When viewed in daylight, this thread does not differ from the known cut version for the viewer.

1

Sicherheitsfaden

2

Kunststoffolie eingefärbt

3

opake Beschichtung

4

Aussparungen

5

Sicherheitspapier

6

Farbschicht

7

klare Folie

8

Farbschicht

9

Farbmittel

10

ätzende Farben

11

klebende Farbe

12

Abziehfolie

13

Prägefolie

14

vertiefter Bereich

15

Metallbeschichtung

16

Transferband

17

erhöhter Bereich

18

Beschichtung

20

Randkodierung

21

humanauslesbare Zeichen

30

Interferenzbeschichtung

31

Aussparung in Interferenzbeschichtung

40

transparente Folie

41

Metallbeschichtung

42

Aussparung in Metallbeschichtung

43

Reliefstruktur

44

Schutzschicht

If the opaque coating is printed on, it is again appropriate to first print wider film webs accordingly and then cut the threads from these printed film webs. Special randomly controlled printing units can be used to introduce random information. In a particularly simple form, such effects are also possible with the help of e.g. B. two printing units possible that print a pattern with different periodicity in overlapping form.

1

Security thread

2nd

Colored plastic film

3rd

opaque coating

4th

Recesses

5

Security paper

6

Layer of paint

7

clear film

8th

Layer of paint

9

Colorant

10th

caustic colors

11

sticky paint

12th

Peel-off film

13

Stamping foil

14

deepened area

15

Metal coating

16

Transfer belt

17th

raised area

18th

Coating

20th

Edge coding

21

human readable characters

30th

Interference coating

31

Recess in interference coating

40

transparent film

41

Metal coating

42

Cutout in metal coating

43

Relief structure

44

Protective layer

Claims (42)

1. A security element (1) in the form of a thread or strip to be embedded in security documents (5) such as bank notes, checks, bonds, identity cards, credit cards or the like, having characters, patterns or the like that are visible in transmitted light and readable to the naked eye and/or by machine, the security element (1) having a transparent plastic film (2, 7, 13, 40), characterized in that the plastic film (2, 7, 13) has a nonmetallic opaque coating (3) extending over the element (1) with recesses (4) in the form of the characters and patterns, and the security element (1) contains, at least in areas congruent with the recesses (4), coloring and/or luminescent substances (8, 9) which cause the characters and/or patterns to differ from the security document (5) and from the opaque coating (3) by color contrast under suitable light conditions.
2. The security element (1) of claim 1, characterized in that the coloring and/or luminescent substances (8, 9) are contained in the plastic film (2, 7, 13).
3. The security element (1) of claim 1, characterized in that the coloring and/or luminescent substances (8, 9) are printed on.
4. The security element (1) of claim 3, characterized in that the coloring and/or luminescent substances (8, 9) are printed onto the side of the film (2, 7, 13) opposite the coating.
5. The security element (1) of claim 3 or 4, characterized in that the coloring and/or luminescent substances (8, 9) are present in the form of a multicolored printed pattern and/or in the form of a luminescent pattern appearing in several colors.
6. The security element (1) of any of claims 1 to 5, characterized in that the luminescent substances (8, 9) are colorless in the unexcited state.
7. The security element (1) of any of claims 1 to 6, characterized in that the characters are embossed into the film (13) and are thus present in the form of depressed areas (14).
8. The security element (1) of claim 7, characterized in that the film (13) has light-collecting properties and preferably contains substances that are luminescent in daylight.
9. The security element (1) of claim 1, characterized in that the pattern is a machine-readable coding (20) extending in the longitudinal direction of the element (1) and preferably provided in the edge area of the element (1).
10. A security element (1) in the form of a thread or strip to be embedded in security documents (5) such as bank notes, checks, bonds, identity cards, credit cards or the like, having characters, patterns or the like that are visible in transmitted light and readable to the naked eye and/or by machine, the security element (1) having a transparent plastic film (2, 7, 13, 40), characterized in that the plastic film (2, 7, 13, 40) has an opaque coating (3, 15, 30, 41) extending over the element with recesses (4, 31) in the form of the characters and/or patterns to be introduced, whereby at least some of these recesses are present in the edge area of the element (1) and constitute a coding (20) that is machine-readable in transmission.
11. The security element (1) of claim 9 or 10, characterized in that this machine-readable coding (20) is a random piece of information.
12. A security element (1) in the form of a thread or strip to be embedded in security documents (5) such as bank notes, checks, bonds, identity cards, credit cards or the like, having characters, patterns or the like that are visible in transmitted light and readable to the naked eye and/or by machine, the security element (1) having a transparent plastic film (2, 7, 13, 40), characterized in that the plastic film (20) has an opaque coating (41) extending over the element with recesses (42) in the form of the characters and/or patterns to be introduced, whereby optically effective structures (43) such as holograms, diffraction grids or reflection patterns are present so as to overlap at least partially with these recesses (42).
13. The security element (1) of claim 12, characterized in that the opaque coating (41) has reflecting properties and the optically effective structures (43) are embossed holograms.
14. The security element (1) of claim 12, characterized in that the optically effective structures (43) are volume holograms.
15. The security element (1) of claim 12, characterized in that the opaque coating (41) has reflecting properties and the optically effective structures (43) are reflection patterns in the form of surfaces inclined at different angles to the document plane.
16. A security element (1) in the form of a thread or strip to be embedded in security documents (5) such as bank notes, checks, bonds, identity cards, credit cards or the like, having characters, patterns or the like that are visible in transmitted light and readable to the naked eye and/or by machine, the security element (1) having a transparent plastic film (2, 7, 13, 40), characterized in that the plastic film (7) has a coating (30) extending over the element with recesses (31) in the form of the characters and/or patterns to be introduced, whereby this coating (30) has dichroic properties and the security element (1) shows a change of color when the manner of viewing changes from incident light to transmitted light.
17. Film material for security elements (1) in the form of threads or strips to be embedded in security documents (5) such as bank notes, checks, bonds, identity cards, credit cards or the like, having characters, patterns or the like that are visible in transmitted light and readable to the naked eye and/or by machine, characterized in that the film material is transparent and has a nonmetallic opaque coating (3, 15, 30, 41) with recesses (4, 31, 42) in the form of the characters and patterns to be introduced.
18. The film material of claim 17, characterized in that the film material contains coloring and/or luminescent substances (8, 9) at least in areas congruent with the recesses (4).
19. The film material of claim 17, characterized in that the film material has optically effective structures (43) such as holograms, diffraction grids or reflection patterns at least partly overlapping the recesses (4).
20. The film material of claim 17, characterized in that the coating (30) has dichroic properties.
21. The security element or film material of one or more of the above claims, characterized in that the coating (3, 15, 30, 41) is applied only in certain areas of the plastic film (2, 7, 13, 40).
22. The security element or film material of one or more of the above claims, characterized in that the opaque coating is printed on.
23. The security element or film material of one or more of the above claims, characterized in that the opaque coating reflects and/or contrasts with the surroundings in color and/or in a gray shade in transmitted light.
24. A security element (5) such as a bank note, identity card or the like, characterized in that the security element of one or more of the above claims is embedded in the security document.
25. A method for producing a security element in the form of a thread or strip to be embedded in a security document, having characters, patterns or the like that are visible in transmitted light and readable to the naked eye and/or by machine, characterized in that a transparent plastic film is provided with an opaque coating, characters and/or patterns are printed over this coating with thermoplastic inks, the film pretreated in this way is brought in close contact with a second film so that the two films adhere in the area of the printed characters, and the two films are then separated, whereby the opaque coating is removed from the first film in the area of the printed characters and the film produced in this way is then cut into safeguarding threads.
26. The method of claim 25, characterized in that the printed characters are applied to the transparent film in a first method step, and the opaque coating in a second step.
27. A method for producing a security element in the form of a thread or strip to be embedded in a security document, having characters, patterns, or the like that are visible in transmitted light and readable to the naked eye and/or by machine, characterized in that characters or patterns are embossed in a transparent plastic film so that the areas representing the characters or patterns are depressed compared to the film surface, the film surface is provided in the non-depressed areas with an opaque coating by the hot embossing method known as such, and the film produced in this way is then cut into safeguarding threads.
28. The method of claim 27, characterized in that a metallic coating is used as the opaque coating.
29. The method of either of claims 27 and 27, characterized in that a transparent plastic film with light-collecting properties is used.
30. A method for producing a security element in the form of a thread or strip to be embedded in a security document, having characters, patterns, or the like that are visible in transmitted light and readable to the naked eye and/or by machine, characterized in that a transparent plastic film is provided with a metallic coating and recesses in the form of the desired characters, patterns or the like are provided in this coating by the electroerosion method known as such, and the film produced in this way is then cut into safeguarding threads.
31. The method of claim 30, characterized in that electrodes in the form of the characters or patterns to be provided are used in the electroerosion method.
32. A method for producing film material for security elements in the form of a thread or strip having writing or patterns that appear light in transmitted light on an opaque or only slightly translucent background, the writing or patterns being printed on a transparent film material using a soluble printing ink, and the film thus printed then being provided with an opaque coating, the printing ink being solubilized using solvents in a solution bath, and the film being subjected to an ultrasonic field in a liquid bath to completely remove the printing ink.
33. The method of claim 32, characterized in that the ultrasonic field is radiated into the solution bath for the printing ink.
34. The method of claim 32, characterized in that the ultrasonic field is radiated into a separate liquid bath following the solvent bath.
35. The method of any of claims 25 to 34, characterized in that a plastic film with coloring and/or luminescent substances is used.
36. The method of any of claims 25 to 35, characterized in that a plastic film is used that is additionally printed in one or more colors.
37. The method of claim 35, characterized in that luminescent printing inks are used.
38. The method of any of claims 25 to 37, characterized in that the coating is applied only partly.
39. The method of any of claims 25 to 38, characterized in that the coating is printed on.
40. The method of any of claims 25 to 39, characterized in that nonmetallic materials that reflect and/or contrast with the surroundings in color and/or in a gray shade in transmitted light are used for the opaque coating.
41. A method for producing a security document such as a bank note, identity card or the like, characterized in that a security element produced by the method of any of claims 25 to 31 or 35 to 40 is embedded in the security document.

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