EP1744904A1

EP1744904A1 - Sheeting and methods for the production thereof

Info

Publication number: EP1744904A1
Application number: EP05747862A
Authority: EP
Inventors: Winfried HOFFMÜLLER; Theodor Burchard; Thorsten Pillo; Manfred Heim
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2004-04-30
Filing date: 2005-04-29
Publication date: 2007-01-24
Anticipated expiration: 2025-04-29
Also published as: US20070165182A1; US7808605B2; EP1744904B1; RU2377133C2; WO2005105475A1; EP1744904B2; RU2006141814A

Abstract

The invention relates to a sheeting that is to be transferred to a target substrate as well as methods for producing such sheeting. According to the inventive method, a plastic support film (32) is provided that is suitable for orienting crystalline liquid material. A layer (34) of crystalline liquid material that is oriented is partially applied to the support film (32).

Description

Foil material and process for its manufacture

The invention relates to a film material for transfer to a target substrate, as well as a method for producing such a film material and a security element that can be produced with the film material. The invention further relates to a method for transferring a film material onto a target substrate, a method for producing a security element and a method for producing an object of value, such as a security paper or a document of value.

Valuables, such as branded articles or documents of value, are often equipped with security elements for security purposes, which allow the authenticity of the valuables to be checked and which at the same time serve as protection against unauthorized reproduction.

In many cases optically variable elements are used as security elements, which give the viewer a different image impression, for example a different color impression, from different viewing angles. In order to ensure authenticity, holograms, holographic grating images and other hologram-like diffraction structures are often used, which offer the viewer a diffraction image that is dependent on the viewing angle.

Security elements with hologram-like diffraction structures are transferred to the target substrate, for example a bank note, using the transfer method, among other things. The security element is detached from the carrier film either via so-called separating or release layers, which can usually be activated thermally, or through the low adhesion of the Security elements on the carrier film. To enable a bond to the paper, the security element is also coated with a suitable adhesive system. In contrast, other security features, such as glossy pigments or other optically variable effect colors, are usually printed directly on a paper substrate.

From the printed publication EP 0435 029 A2 a transfer element with a plastic-like layer made of a liquid crystal polymer is known, which shows a pronounced interplay of colors at room temperature. In addition to a carrier film, the transfer element comprises an optional wax layer, a protective lacquer layer, a layer of a liquid crystal polymer, a color layer and a hot-melt adhesive layer.

Solvent-based liquid crystal coatings require alignment-promoting conditions in order to be effective. Special alignment or alignment layers are typically used for this purpose. In particular, alignment layers are used which consist of a linear photopolymer which is exposed to a suitable radiation for alignment. Furthermore, liquid-crystalline materials can also be aligned with the aid of alignment layers, which are provided by a finely structured layer or a layer aligned by exerting shear forces. The alignment of the liquid-crystalline materials with such alignment layers is complex due to the additional work steps that are usually required. Proceeding from this, the object of the invention is to specify a film material and a method for its production which avoids the disadvantages of the prior art.

This object is solved by the features of the independent claims. Developments of the invention are the subject of claims under.

According to the invention, the liquid crystalline material is prepared on a plastic carrier film. Due to its internal structure, the plastic carrier film has a preferred direction which is sufficient for the liquid crystalline

Align material in the desired shape. Particularly suitable are plastic films that have a surface structure created during manufacture. PET, PE, BOPP, OPP films and cellulose triacetate are examples of such plastic carrier films suitable for aligning liquid-crystalline material.

The liquid-crystalline material can therefore be applied directly to the plastic carrier film, preferably printed, without further alignment layers. According to the invention, the liquid crystalline material is partially applied. Liquid-crystalline layer is preferably applied in the form of patterns, characters or codes.

In a preferred embodiment, a functional layer is applied over the entire surface of the liquid-crystalline layer and in the exposed areas correspondingly onto the carrier film. By using a functional layer, security elements made of liquid-crystalline material that are not fully present, for example printed as a motif, can also be applied to one Target substrate to be transferred. If desired or necessary, the carrier film for the liquid-crystalline layer and the functional layer can be removed during or after the application of the film material to the target substrate. In order to ensure that the carrier film of a film material designed as a transfer material can be removed without damage, the adhesion of the functional layer to the carrier film is advantageously less than to the liquid-crystalline layer.

In a further preferred embodiment, an adhesive layer is also applied for transfer to a target substrate.

In an advantageous development of the invention, further layers of liquid-crystalline material can be applied partially, in particular in the form of patterns, characters or codes, between the partially applied liquid-crystalline layer and the functional layer. In this case, these can advantageously overlap at least partially with the liquid-crystalline layer applied first.

The liquid-crystalline layers are preferably applied, preferably printed, as a lacquer layer made of nematic, cholesteric or smectic liquid-crystalline material. Printing techniques for the liquid-crystalline layers and / or the functional layer are in particular gravure printing, screen printing, flexographic printing, knife coating or curtain coating.

A UV-curing lacquer layer is preferably applied, in particular printed, as the functional layer. Appropriately contains the UV-curing Paint layer photoinitiators. In individual cases, in particular when producing a transfer material, a balance must be sought between sufficiently high adhesion of the functional layer to the liquid-crystalline layer to be removed and sufficiently low adhesion to the carrier film.

In a further preferred embodiment, a layer of cholesteric liquid-crystalline material is applied, in particular printed, as the functional layer. An embossing lacquer layer can also advantageously be used as a functional layer. In this case, the embossing lacquer layer is expediently printed on and subsequently embossed, provided with a reflective layer, in particular a metal layer, and optionally demetallized in some areas, for example in order to introduce negative writing into the metallized embossing structure. The embossed structure advantageously forms an optically effective microstructure, in particular a diffractive diffraction structure, a matt structure, an arrangement of microlenses or an arrangement of micromirrors.

In order to achieve better adhesion to subsequently applied layers, for example an embossing lacquer layer subsequently applied, the functional layer can advantageously be subjected to a corona treatment or can be equipped with an adhesion promoter.

In a further preferred embodiment, one or more further layers can be applied to the functional layer, in particular printed on, in order to produce more complex layer structures. An embossing lacquer layer can preferably be applied as a further layer, in particular be printed on. After application, the embossing lacquer layer is advantageously embossed, metallized and, if necessary, demetallized in some areas.

A machine-readable and / or decorative layer can also be used as a further layer, which is applied at least in some areas, in particular in the form of patterns, characters or codes. For example, the machine-readable and / or decorative layer can be printed with a printing ink on the functional layer or a further layer already applied thereon.

A reflective layer can also be applied as a further layer. In all variants with a reflective layer, this can also be formed by a reflective thin-film element. Such a thin-film element is preferably formed with a reflection layer, an absorber layer and a dielectric spacer layer arranged between the reflection layer and the absorber layer.

In an advantageous development of the invention, one or more further layer composites are produced in addition to the layer composite already described and are connected to one another, for example, by laminating lacquer layers. In this way, diverse and complex security layer structures can be realized, which enable a layer sequence which is often not realizable in known multilayer security elements and which reinforce the effects of the security element. For the individual layer composites, the optimum manufacturing conditions can be selected through the separate production. In this way, layer composites can also be combined according to the invention, which are mutually exclusive manufacturing conditions or mutually interfering carrier films because the carrier films can be removed during or after the partial layer composites have been joined together.

In particular, a second security layer composite present on a second carrier film can be provided according to the invention, which is connected via a second adhesive layer to the layer composite of carrier film, partial liquid-crystalline layer and optionally further layers.

In a first variant of the invention, the second security layer composite is produced by applying an embossing lacquer layer to the second carrier film, embossing, metallizing and, if appropriate, demetallizing the embossing lacquer layer in certain areas.

According to another variant of the invention, the second security layer composite is produced in that a rastered metal layer, in particular in the form of patterns, characters or codes, or a semi-transparent metal layer is applied to the second carrier film and that a machine-readable and / or decorative layer is applied to the metal layer. in particular in the form of patterns, characters or codes.

The second security layer composite can also comprise a reflective layer. In all variants, the reflective layer can advantageously be formed by a metal layer or, in the case of more complex structures, by a reflective thin-layer element with a color impression depending on the viewing angle. In the latter case, the thin-film element is preferably with a reflection layer, an absorber layer and a dielectric spacer layer arranged between the reflection layer and the absorber layer. The reflective layer of the thin-film element is preferably formed from an opaque or semi-transparent metal layer.

The thin-film element can also be formed with at least one absorber layer and at least one dielectric spacer layer, the absorber layers and the dielectric spacer layers being arranged alternately one above the other. According to a further possible embodiment, the thin-film element is formed with a plurality of dielectric spacer layers, layers adjacent to one another having very different refractive indices being formed.

According to a further variant of the invention, the second security layer composite comprises an optically effective microstructure, which is preferably formed as a diffractive diffraction structure, as a matt structure, as an arrangement of microlenses or as an arrangement of micromirrors.

All variants can be machine-readable and / or decorative

Layer a layer can be printed that contains machine-readable feature substances, in particular magnetic, electrically conductive, phosphorescent, fluorescent or other luminescent substances.

The invention also includes a film material for security elements, which can be produced in particular by one of the production methods described above, and which contains a sequence of security layers with a Plastic carrier film which is suitable for aligning liquid-crystalline material, and also with a first partially present layer of liquid-crystalline material which is present on the plastic carrier film in an aligned form. The first liquid-crystalline layer of the film material is also advantageously formed from a nematic liquid-crystalline material. The first liquid-crystalline layer preferably forms a phase-shifting layer.

In an advantageous development of the invention, at least one further layer of liquid-crystalline material is present between the partially applied liquid-crystalline layer and a full-surface functional layer. The at least one further liquid-crystalline layer is preferably formed from cholesteric liquid-crystalline material.

The functional layer preferably consists of a UV-curing lacquer layer. Alternatively, the functional layer can also be formed from a cholesteric liquid-crystalline material.

In all variants, the film material can comprise an adhesive layer for transferring the sequence of security layers to the target substrate.

The invention also contains a security element for securing valuables with a partially present layer made of a liquid-crystalline material, in particular nematic liquid-crystalline material, and a full-surface functional layer which is arranged directly above the partially present layer made of liquid-crystalline material. The functional layer is a UV-curing lacquer layer Layer of cholesteric liquid crystalline material or an embossing lacquer layer is formed.

The security element preferably comprises a plastic carrier film which is suitable for aligning liquid-crystalline material. The functional layer is preferably formed by an embossing lacquer layer into which an optically effective microstructure is embossed and which is provided with a reflective layer, in particular a metal layer, and optionally demetallized in some areas.

The optically effective microstructure can advantageously be formed by a diffractive diffraction structure, a matt structure, an arrangement of microlenses or an arrangement of micromirrors.

The invention also includes a method for transferring a film material to a target substrate, in which a film material of the type described is placed with the adhesive layer on the target substrate and is connected to the target substrate by the action of heat and / or pressure. When using radiation-curing adhesives, the film material is connected to the target substrate by the action of pressure and radiation. If the film material is designed as a transfer material, the plastic carrier film of the liquid-crystalline layer is expediently removed during or shortly after being applied to the target substrate.

In a method for producing a security element, in particular a security thread or a security element to be applied or transferred, a film material of the type described is produced. provided and equipped with further layers for embedding in or for application to security paper or a valuable object, in particular a value document. The security element preferably contains a carrier substrate made of paper or plastic.

In a method for producing an object of value, such as security paper or a document of value, a film material of the type described is applied to an object to be secured, in particular glued on by the action of heat and / or pressure and / or radiation. The surface of the security paper or object of value can advantageously be specially treated in order to improve the adhesive effect of the film material on the surface and the optical efficiency of the film material. In particular, an adhesion promoter can be used for this purpose, which is applied to the surface of the security paper.

Valuable objects in the sense of the present invention are, in particular, banknotes, shares, loans, certificates, vouchers, checks, high-quality admission tickets, but also other papers that are at risk of forgery, such as passports and other identification documents, as well as product security elements such as labels, seals, packaging and the like. In the following, the term “valuable object” includes all such objects, documents and product security means. The term “security paper” is understood to mean the preliminary stage to a value document which is not yet fit for circulation and which, in addition to the security element, can have other authenticity features, such as luminescent substances provided in the volume , security paper is usually in an almost endless form and will be processed at a later date.

Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, in the illustration of which a true-to-scale and proportioned reproduction has been omitted in order to increase clarity.

Show it:

1 is a schematic representation of a banknote with an embedded security thread and a glued-on security strip, in each case according to an embodiment of the invention,

2 is a plan view of a portion of the security strip of FIG. 1 as it appears when viewed without aids or when viewed through a polarizer,

3 shows a cross-sectional illustration of an intermediate step in the production of a film material according to the invention,

4 shows a representation as in FIG. 3 of a film material according to a further exemplary embodiment of the invention,

5 shows the production of a film material according to a further exemplary embodiment of the invention, with (a) and (b) one first and second layer composite before lamination and (c) shows the finished film material,

6 shows a representation as in FIG. 5 (c) of a film material according to a further exemplary embodiment of the invention,

7 shows a representation as in FIG. 3 of a film material according to a further exemplary embodiment of the invention,

8 shows the production of a film material according to a further exemplary embodiment of the invention, with (a) and (b) showing a first and second layer composite before lamination and (c) the finished film material,

9 shows a variant of the embodiment of FIG. 8 (c), which differs from it only in the configuration of the second security layer composite,

10 shows the production of a film material according to a further exemplary embodiment of the invention, with (a), (b) and (c) showing a first, second and third layer composite before lamination and (d) the finished film material,

11 shows the transfer of the film material of FIG. 5 designed as a transfer material to a target substrate, 12 shows a security element according to a further exemplary embodiment of the invention, and

13 in (a) a cross-sectional representation of a film material according to a further exemplary embodiment of the invention and in (b) a plan view of a partial area of the film material.

The invention will now be explained in more detail using the example of a banknote. 1 shows a schematic illustration of a bank note 10 with two security elements 12 and 16, which are each produced with the aid of a film material according to the invention.

The first security element represents a security thread 12 which emerges from certain window areas 14 on the surface of the banknote 10, while it is embedded in the areas in between inside the banknote 10. The second security element is formed by a wide security strip 16 glued to the banknote paper with a heat seal adhesive.

FIG. 2 shows a top view of a partial area of the security strip 16 as it appears when viewed without aids or when viewed through a linear polarizer 20. When viewed without tools, the security strip 16 shows shiny metallic, optically variable diffraction structures 22, such as holograms or kinegrams. Diffraction structures of this type are known to the person skilled in the art and are therefore not explained further below. Instead of the diffraction structures 22, matt structures or refractive structures can also be provided, for example. If the security strip 16 is viewed through a linear polarizer 20, additional structures, in the exemplary embodiment a honeycomb pattern 24, appear. Alternatively, the structures can also be made visible using a circular polarizer. These structures, which are practically invisible to the naked eye, can be used to check the authenticity of the banknote 10.

The construction and manufacture of security elements according to the invention is first explained using simpler and then increasingly complex security element structures.

FIG. 3 shows a cross-sectional illustration of an intermediate step in the production of a film material 30, which can be used for example with a security thread 12 or a security strip 16 of the type shown in FIG. 1. For this purpose, a layer 34 of nematic liquid-crystalline material is printed on a transparent carrier film 32, for example a smooth plastic film of good surface quality. The nematic layer 34 is typically printed in the form of a motif made of patterns, characters or a code, for example in the form of the honeycomb pattern shown in FIG. 2. Due to the surface structure of the carrier film 32, which specifies a preferred direction for the alignment of the liquid-crystalline material, the nematic layer 34 can be printed directly on the carrier film.

A further layer, not shown here, made of liquid-crystalline material, for example, can overlap the nematic layer 34, at least partially made of cholesteric liquid crystalline material, also partially printed in the form of a motif.

On the nematic layer 34 and the carrier foil 32, a functional layer, e.g. a UV-crosslinkable lacquer layer 36 is printed. Alternatively, a layer of cholesteric liquid-crystalline material or an embossing lacquer layer can also be used as functional layer 36. In order to be able to transfer the nematic layer 34, which is only present in certain areas, and possibly the further layer of cholesteric liquid-crystalline material to a target substrate, such as security paper or a value document, in a later operation, with the removal of the carrier film 32, the functional layer is preferably designed such that its Adhesion to the carrier film 32 is less than to the nematic layer 34.

An adhesive layer 38 is then applied to the functional layer 36, with which the layer composite comprising the carrier film 32, the nematic layer 34 and the functional layer 36 can be laminated onto a target substrate, such as a security paper, a value document or also another thread or strip structure 35. If desired or necessary, the support film 32 for the liquid-crystalline materials 34 and 36 can be finished last

Separating winding can be removed again. The damage-free detachability of the carrier film 32 is ensured by the greater adhesion of the functional layer 36 to the nematic layer 34.

However, it is also possible to leave the carrier film 32 in the layer composite after it has been applied to the target substrate or the thread or strip structure. The carrier film 32 can then serve as a cover film, for example. In all configurations, both the functional layer and the adhesive layer can contain machine-readable feature substances, such as, for example, magnetic, electrically conductive, phosphorescent or fluorescent substances.

Before the adhesive layer 38 is applied, a further layer, not shown here, can be printed on the functional layer 36. The further layer can in particular be provided with cutouts or in the form of patterns, characters or codes. In order to enable the color and polarization effects of the nematic or, if appropriate, cholesteric liquid crystal layers to be easily recognized, the layer can be provided by an absorbent imprint or a reflective metal layer. For example, the layer can be produced by printing the functional layer 36 with a commercially available, in particular black, printing ink. This is particularly useful when the functional layer 36 consists of cholesteric liquid crystalline material. If the functional layer 36 is in the form of a UV-crosslinkable lacquer layer, the further layer can be provided by a metal layer into which recesses, e.g. in the form of a negative writing. Another, e.g. machine-readable layer can be printed. Machine-readable security features can also be accommodated in the further layer. The further manufacturing process then proceeds as already described in connection with FIG. 3.

In the film material with negative writing 60 of FIG. 4, a nematic liquid crystal layer 34 is printed on a carrier film 32. A UV-curable is applied over the entire surface via the carrier film 32 and the nematic layer 34 Embossing lacquer layer 62 is printed, the adhesion of which to the carrier film 32 is less than to the nematic layer 34, so that the embossing lacquer layer 62 fulfills the function of the functional layer described above when the film material 60 is transferred to a target substrate.

A desired embossing structure 64, e.g. a diffraction structure, embossed and a reflective layer 66, e.g. in the form of a metal layer, applied, in particular vapor-deposited, into which cutouts 68, in the exemplary embodiment in the form of a negative writing, are introduced by partial demetallization. Alternatively, the embossed structure 64 can also be provided with a high refractive index layer. Examples of suitable high-index materials are CaS, CrO∑, ZnSi, ΗO2 or SiOx. Finally, an adhesive layer 38 is applied to the layer composite for the transfer to the target substrate.

Instead of a reflective layer 66 in the form of a metal layer or a highly refractive layer, the embossed structure 64 can also be provided with a thin-layer element with a color shift effect, as is described in detail below with reference to FIG. 6.

Before the adhesive layer 38 is applied, further machine-readable and / or decorative layers can be applied to the partially demetallized embossing lacquer layer 62, in particular also in an overlap with the metal layer 66. For example, a commercially available printing ink can be printed on, which is then recognizable in the cutouts or demetallized areas of the embossing lacquer layer when the film material applied to a substrate is viewed. The ink can be just like that Adhesive layer 38 also contain machine-readable feature substances, such as, for example, magnetic, electrically conductive, phosphorescent or fluorescent substances.

5 illustrates the production of a film material 70 according to a further exemplary embodiment of the invention. In this case, as shown in FIG. 5 (a), a first layer composite 72 is produced from a first carrier film 32, a nematic liquid crystal layer 34 and a functional layer 36, as described in connection with FIG. 3. The functional layer 36 can e.g. be formed by a UV-crosslinkable lacquer layer or a layer of cholesteric liquid-crystalline material.

In addition, as shown in FIG. 5 (b), a second security layer composite 74 is produced by printing an embossing lacquer layer on a second carrier film 80, a desired embossing structure, in the exemplary embodiment a diffraction structure, into which embossing lacquer is embossed, on the embossed layer 82 a metal layer 84 is evaporated, and cutouts 86, for example in the form of a negative writing, are produced by partial demetallization of the metal layer 84.

The second security layer composite 74 is laminated onto the first layer composite 72 via an adhesive layer 76 (FIG. 5 (c)), as indicated by the arrow 78 connecting FIGS. 5 (b) and 5 (a). Subsequently, the second carrier film 80 is removed by a separation winding and an adhesive layer 38 is applied to the layer composite thus produced, as shown in FIG. 5 (c). If the film material is to be used as a transfer material for transfer to a target substrate, the carrier film 32 can be used after the transfer material 70 has been applied to the target substrate, so that the entire security layer composite is then present without carrier films. The characteristics working with polarization effects are not affected by foils and can be viewed with high contrast. If the film material is to be used as a security thread for embedding in a security paper, the carrier film 32 can also be removed by separation wrapping and further layers of the thread structure, such as an adhesion promoter and a heat seal lacquer, can be applied to the then exposed liquid crystal layers 34 and 36 ,

The protective function for the metallization, which is reduced due to the detachment of the second carrier film 80, can be compensated for by protective lacquer layers. Conventional protective lacquer layers are largely isotropic optically and therefore do not impair the recognizability of polarizing effects.

If a layer of cholesteric liquid-crystalline material is used as the functional layer 36, an additional, darkly colored layer can optionally be partially applied to the security layer composite 74 in order to make the color effect of the cholesteric layer easily recognizable

Ensure liquid crystal layer. Alternatively, the embossing lacquer layer 82 can also be colored dark.

Instead of the embossed structure, the second security layer composite can also contain only one metallic reflection layer, which is preferably integrated into a print motif with large proportions of demetallization. Compared to conventional designs, the film material according to the invention has al then with the nematic layer 34 on an additional test level that can be authenticated with a polarizer.

In all designs with a metallic reflection layer, this can also be replaced by a more complex reflection layer structure with special reflection effects, such as a color shift effect. 6 shows an exemplary embodiment, the production of which is analogous to the production process described in FIG. 5.

For the production of the film material 90 of FIG. 6, which can be used, for example, with a security thread 12 or a security strip 16 of the type shown in FIG. 1, a first layer composite is made of a first carrier film 32, a nematic liquid crystal layer 34 and a functional layer 36, eg a UV-crosslinkable lacquer layer, and a second security layer composite from a second carrier film, to which a thin-layer element 92 with a color-shift effect is applied.

In the exemplary embodiment, the thin-film element 92 has a reflection layer 94, an absorber layer 98 and a dielectric spacer layer 96 arranged between the reflection layer and the absorber layer. In such thin-film elements, the color shift effect is based on interference effects that are dependent on the viewing angle, due to multiple reflections in the various sub-layers of the element. The absorber layer 98 and / or the dielectric spacer layer 96 can have cutouts in the form of patterns, characters or codes in which no color shift effect can be seen. The reflection layer 94 can also have cutouts in the form of patterns, characters or codes which then form transparent or semi-transparent areas in the thin-film element 92.

The order of the layers of the thin-film element can also be reversed. Alternatively, the thin-film element can have a layer sequence of absorber layer / dielectric layer / absorber layer or a sequence of several layers of alternating high-index and low-index dielectrics. A layer sequence consisting of a reflection layer and an absorbing dielectric layer can also be considered.

The second security layer composite produced in this way is then laminated onto the first layer composite via an adhesive layer 76 and the second carrier film is removed by a separating winding. For the transfer to the target substrate, an adhesive layer 38 is applied to the now exposed rear side of the thin-layer element 92. Before the adhesive layer 38 is applied, further machine-readable and / or decorative layers, e.g. with a magnetic paint. After the transfer, the first carrier film 32 can also be detached.

In a variant of the embodiment of FIG. 6, not shown, a film material for a two-sided security thread with a liquid-crystal-based color shift or polarization effect, which can be seen by the viewer from one side, and a thin-film element with a color shift effect, which is from the second side is generated. The film material differs from that shown in FIG. 6 in that the functional layer 36 is formed from cholesteric liquid-crystalline material. In order in particular to enable the color effect of the cholesteric liquid crystal layer to be easily recognized, the adhesive layer 76 also forms a dark, preferably black, background. For this purpose, the adhesive layer 76 can be colored or, if necessary, subsequently blackened by the action of a laser beam. The thin-film element 92 has a reverse order to the layer sequence described above, ie the reflective layer is adjacent to the adhesive layer 76 in the film material and the absorber layer is adjacent to the adhesive layer 38.

FIG. 7 shows a film material 100 according to a further exemplary embodiment of the invention, in which, as in FIG. 3, a nominal liquid crystal layer 34 and a UV-crosslinkable functional layer are placed on a smooth plastic carrier film 32 which is suitable for aligning liquid-crystalline material 36, for example made of cholesteric liquid crystal material, can be printed on. An embossing lacquer layer is further printed on the functional layer 36, a desired embossing structure, in the exemplary embodiment a diffraction structure, is embossed into the embossing lacquer layer, and a metal layer 104 is evaporated onto the embossed layer 102. Recesses 106 in the form of a negative writing are made in the metal layer 104 by partial demetallization. Instead of the metal layer 104, it is also possible to use a transparent high-index layer which has a refractive index greater than 2. As a result, both are present on a dark background, which can be formed by a corresponding additional layer, for example a black imprint, or also on the target substrate Diffraction structure as well as the liquid-crystalline layers 34 and 36 perceptible over the entire surface.

In order to improve the adhesion of the embossing lacquer layer 102 to the functional layer 36, the latter is advantageously subjected to a corona treatment beforehand or it is equipped with a suitable adhesion promoter. An adhesive layer 38 is also applied to the entire layer composite for application to the target substrate. Depending on the choice of the mediating layer and the demands placed on the brilliance, the carrier film 32 can be removed after the film material 100 has been applied or left on the structure.

The production of a film material 110 for a security thread with a liquid crystal-based color shift effect, a negative writing and a magnetic coding according to a further exemplary embodiment of the invention will now be explained with reference to FIG. 8.

First, as shown in FIG. 8 (a), a first layer composite 112 is produced from a first carrier film 32, a nematic liquid crystal layer 34 and a functional layer 36, for example from cholesteric liquid crystal material, as described in FIG. 3. A second security layer composite 114 is produced by applying a rastered aluminum layer 122 with cutouts in the form of negative writing to a second carrier film 120, and applying a magnetic layer 124, in the exemplary embodiment in the form of a coding, to the aluminum layer. This second security layer composite 114 is shown in FIG. 8 (b). In a further embodiment, not shown here, the aluminum layer 122 can also be provided as a full-surface layer with cutouts, for example in the form of a negative writing, to which the magnetic layer 124 is in turn applied.

The second security layer composite 114 is then laminated onto the first layer composite 112 via an adhesive layer 116 (FIG. 8 (c)). Subsequently, further layers 118, such as a white cover layer, which are required for embedding the security thread in a security paper, can be applied to the back of the second carrier film 120. Finally, an adhesive layer 38, for example a heat seal lacquer, is applied for the transfer to the target substrate. The carrier film 32 can be removed by separation winding and further layers of the thread structure, such as an adhesion promoter and a heat seal lacquer, can be applied to the then exposed liquid crystal layers 34 and 36.

In a variant of the exemplary embodiment of FIG. 8, not shown, instead of the magnetic layer 124 applied in the form of a coding, a dark, in particular black, layer with cutouts and, in some areas, a magnetic layer, for example in the form of magnetic bits, can also be used. In particular, not all black areas need to be magnetic at the same time. In this way, magnetic coding can be optically hidden in the black layer.

A further variant of the exemplary embodiment from FIG. 8, which differs only in the configuration of the second security layer composite, is shown in FIG. 9. The second security layer composite 132 of the film Instead of the screened aluminum layer, materials 130 of FIG. 9 contains a full-surface, semi-transparent metal layer 136 applied to a carrier film 134, on which a magnetic layer 138 is arranged, for example in the form of a coding. The further procedure for the production of the security thread 130 follows the description given above in connection with FIG. 8.

10 illustrates the production of a film material 140 for a hologram security thread with magnetic coding and nematic printing according to a further exemplary embodiment of the invention.

First, a first layer composite 150 is produced from a first plastic carrier film 152, a nematic liquid crystal layer 154, a functional layer 156 from a modified UV-curing lacquer and a first adhesive layer 158, as shown in FIG. 10 (a).

To produce a second security layer composite 160, which is shown in FIG. 10 (b), an embossing lacquer layer is printed on a second plastic carrier foil 162, a desired diffraction structure is embossed in the embossing lacquer and a metal layer 166 on the embossed layer 164. For example, an aluminum layer is evaporated, in which, as already described in connection with FIG. 5, cutouts 168, for example in the form of a negative writing, are produced by partial demetallization. A magnetic layer 170 in the form of a coding is applied to the back of the carrier film 162 which is not coated with embossing lacquer. The magnetic bits of the magnetic coding are then covered with a cover layer 172. A third layer composite 180, which acts as a covering element in the finished security thread, is produced by applying a full-surface metal layer 184 to a third, particularly thin plastic carrier film 182 and providing the metal layer 184 with a further full-surface adhesive layer 186, as in FIG. 10 ( c) shown.

Now the first layer composite 150 is laminated with the nematic printing with the aid of the adhesive layer 158 onto the top of the hologram layer composite 160 (arrow 142) and the cover layer composite 180 is laminated via the adhesive layer 186 onto the underside of the hologram layer composite 160 carrying the magnetic code (arrow 144) , Further layers 146, such as a white cover layer, which are required for embedding the security thread in a security paper, can then be applied to the back of the third carrier film 182. Finally, an adhesive layer 38, for example a heat seal lacquer, is applied for the transfer to the target substrate, as shown in FIG. 10 (d). The carrier film 152 of the first layer composite 150 can then be removed by separation winding and further layers of the thread structure, such as an adhesion promoter and a heat seal lacquer, can be applied to the then exposed liquid crystal layers 154 and 156.

The application of the described security elements to a target substrate 200, for example a security paper or a plastic film, is explained with reference to FIG. 11 using the film material of FIG. 5, which is present as transfer material 70. For this purpose, the transfer material 70 is placed with the heat-sealing adhesive layer 38 on the target substrate 200 and pressed on. The pressing can be done, for example, with a heated one, not shown Transfer stamp or a transfer role. Under the action of pressure and heat, the adhesive layer 38 bonds in the desired areas 202 to the target substrate 200, so that a transfer element, possibly with a predetermined outline shape, is created. The carrier film 32 of the liquid crystal layers 34, 36 can be removed during the application process or shortly thereafter. Before the transfer material 70 is applied to the target substrate 200, the surface of the target substrate 200 can be specially treated. As a result, in particular the adhesive effect of the transfer material and the optical efficiency of the security features provided by it can be improved. For example, an adhesion promoter can be applied to the surface of the transfer material.

Fig. 12 shows a security element 190 according to a further exemplary embodiment of the invention, in which, as in Fig. 4, a smooth plastic carrier film 32, e.g. a PET film which is suitable for aligning liquid-crystalline material, a nematic liquid-crystal layer 34 and, over the entire surface, a UV-curable embossing lacquer layer 192 are printed as a functional layer. A metal layer 194 is vapor-deposited onto the diffraction structure embossed into the embossing lacquer layer 192, into which recesses can be made if necessary by partial demetallization.

Before the adhesive layer 38 is applied, further layers, in the exemplary embodiment a machine-readable layer 196, which contains machine-readable feature substances, such as magnetic, electrically conductive, phosphorescent or fluorescent substances, and a white cover layer 198, which is required for embedding the security thread in a security paper, partially applied, for example in the form of a motif.

The layer composite of plastic carrier film 32, nematic liquid crystal layer 34, metallized embossing lacquer layer 192, 194, machine-readable layer 196 and cover layer 198 is then laminated onto a target substrate 199, such as a PET film, by means of the adhesive layer 38.

If desired or necessary, the plastic carrier film 32 can be removed again by means of a separation winding. In this case, it must be ensured that the adhesion of the functional layer 192 to the carrier film 32 is less than to the nematic layer 34.

However, it is also possible to leave the carrier film 32 in the layer composite. Such an embodiment is particularly useful when the security element is in the form of a security strip in a paper machine manufactured or punched out vein of a banknote. The carrier film 32 then serves, inter alia, as a cover film.

13 (a) shows a cross-sectional view of a film material 210 according to a further exemplary embodiment of the invention, in which, as in FIG. 3, a nematic liquid crystal layer 34 and a functional layer 36 made of cholesteric liquid crystalline material are printed on a smooth, transparent plastic carrier film 32 , The nematics layer 34 is typically printed in the form of a motif made up of patterns, characters or a code, for example in the form of the letter sequences “PL” shown in FIG. 13 (b). In order to enable the polarization effects of the nematic liquid crystal layer to be easily recognized, as described in connection with FIG. 3, a reflective metal layer 216 is applied over the nematic layer 34 in the regions 212 before the adhesive layer 38 is applied. In the metal layer-free areas 214, an absorbent print is also printed using a commercially available, in particular black, printing ink. This provides a dark background layer 218 which is essential for the recognition of the color shift effects of the cholesteric liquid crystal layer.

Subsequently, the adhesive layer 38 is applied, with which the layer composite of carrier film 32, nematic layer 34, functional layer 36, metal layer 216 and dark background layer 218 is laminated onto a target substrate, such as a security paper, a document of value or also another thread or strip structure can be. If desired or necessary, the carrier film 32 for the liquid-crystalline materials 34 and 36 can finally be removed again by means of a separation winding. The damage-free detachability of the carrier film 32 is ensured by the greater adhesion of the functional layer 36 to the nematic layer 34.

In a variant of the embodiment of FIG. 13, not shown, the nematic layer 34 can also be present in the area 214, for example in the form of a motif. When the film material applied to a target substrate is observed with the naked eye, only the color shift effects of the cholesteric liquid crystal layer 36 can be seen. If, on the other hand, the film material is viewed through a linear polarizer, the structures formed by the nematic layer 34 appear.

Claims

Patent statements

1. Method for producing a film material for security elements, with the method steps:

a) providing a plastic carrier film which is suitable for aligning liquid-crystalline material,

b) partial application of a first layer of a liquid-crystalline material to the carrier film, the liquid-crystalline material being aligned.

2. The method according to claim 1, characterized in that a film is provided as the carrier film, which has a surface structure formed during production.

3. The method according to claim 1 or 2, characterized in that a functional layer is applied over the entire surface of the first liquid-crystalline layer and the carrier film.

4. The method according to at least one of claims 1 to 3, characterized in that an adhesive layer for transferring the layer composite formed is applied to a target substrate.

5. The method according to at least one of claims 1 to 4, characterized in that the film material is formed as an application material.

6. The method according to at least one of claims 1 to 4, characterized in that the film material is formed as a transfer material.

7. The method according to claim 6, characterized in that the adhesion of the functional layer to the carrier film is less than to the liquid-crystalline layer.

8. The method according to at least one of claims 1 to 7, characterized in that at least one further liquid-crystalline layer is partially applied between the partially applied first liquid-crystalline layer and the functional layer.

9. The method according to at least one of claims 1 to 8, characterized in that the first liquid-crystalline layer and / or the further liquid-crystalline layers are applied in the form of patterns, characters or codes.

10. The method according to at least one of claims 1 to 9, characterized in that the first liquid-crystalline layer and / or the further liquid-crystalline layers are applied, preferably printed, as a lacquer layer composed of nematic, cholesteric or smectic liquid-crystalline material.

11. The method of at least one of claims 1 to 10, characterized in that the first liquid-crystalline layer and / or the further liquid-crystalline layers and / or the functional layer by means of deep printing, screen printing, flexo printing, kr-if coating or curtain coating.

12. The method according to at least one of claims 1 to 11, characterized in that a UV-curing lacquer layer is applied, in particular printed, as the functional layer.

13. The method according to at least one of claims 1 to 12, characterized in that a layer of cholesteric liquid-crystalline material is applied, in particular printed, as the functional layer.

14. The method according to at least one of claims 1 to 12, characterized in that an embossing lacquer layer is applied, in particular printed, as the functional layer, which is subsequently embossed.

15. The method according to claim 14, characterized in that the embossing lacquer layer is metallized and optionally demetallized in some areas.

16. The method according to at least one of claims 1 to 15, characterized in that the functional layer is corona-treated or is equipped with an adhesion promoter.

17. The method according to at least one of claims 1 to 16, characterized in that one or more further layers are applied, in particular printed, onto the functional layer.

18. The method according to claim 17, characterized in that an embossing lacquer layer is applied, in particular printed, as a further layer, which is subsequently embossed, metallized and optionally demetallized in some areas.

19. The method according to claim 17 or 18, characterized in that a machine-readable and / or decorative layer is applied, in particular printed, as a further layer, at least in regions.

20. The method according to claim 19, characterized in that the machine-readable and / or decorative layer is printed in the form of patterns, characters or codes.

21. The method according to at least one of claims 17 to 20, characterized in that a reflective layer is applied as a further layer.

22. The method according to at least one of claims 1 to 21, characterized in that the carrier film with the liquid-crystalline material and the optionally further layers forms a first layer composite and a second security layer composite is provided on a second carrier film, which is provided with the first via an adhesive layer Layer composite is connected.

23. The method according to claim 22, characterized in that the second security layer composite by applying an embossing lacquer layer on the second carrier film, embossing, metallizing and, if appropriate, demetallizing the embossing lacquer layer in certain areas.

24. The method according to claim 22, characterized in that the second security layer composite by applying a rastered metal layer, in particular in the form of patterns, characters or codes, or a semi-transparent metal layer on the second carrier film and by subsequent application of at least one masculine readable and / or decorative Layer on the metal layer, in particular in the form of patterns, characters or codes.

25. The method according to at least one of claims 22 to 24, characterized in that the second security layer composite comprises a reflective layer.

26. The method according to claim 20 or 25, characterized in that the reflective layer is formed by a metal layer.

27. The method according to claim 20 or 25, characterized in that the reflective layer is formed by a reflective thin-film element with viewing angle-dependent color impression.

28. The method according to claim 27, characterized in that the thin-film element is formed with a reflection layer, an absorber layer and a dielectric spacer layer arranged between the reflection layer and the absorber layer.

29. The method according to at least one of claims 22 to 24, characterized in that the second security layer composite comprises an optically effective microstructure.

30. The method according to claim 29, characterized in that the optically effective microstructure is formed as a diffractive diffraction structure, as a matt structure, as an arrangement of microlenses or as an arrangement of micromirrors.

31. The method according to at least one of claims 1 to 30, characterized in that a layer is printed as a machine-readable and / or decorative layer which contains machine-readable feature materials, in particular magnetic, electrically conductive, phosphorescent, fluorescent or other luminescent substances ,

32. Foil material for security elements, in particular producible according to one of claims 1 to 31, with a plastic carrier film which is suitable for aligning liquid-crystalline material, and with a first partially present layer made of a liquid-crystalline material which is present in an aligned form ,

33. The film material according to claim 32, characterized in that the carrier film is a film which has a surface structure which has arisen during manufacture.

34. Foil material according to claim 32 or 33, characterized in that a full-surface functional layer is arranged over the partially present first liquid-crystalline layer and the carrier film.

35. Foil material according to at least one of claims 32 to 34, characterized in that at least one further liquid-crystalline layer is partially applied between the partially applied first liquid-crystalline layer and the functional layer.

36. Foil material according to at least one of claims 32 to 35, characterized in that the first liquid-crystalline layer is formed from a nematic liquid-crystalline material.

37. Foil material according to at least one of claims 32 to 36, characterized in that the first liquid-crystalline layer forms a phase-shifting layer.

38. Foil material according to at least one of claims 32 to 37, characterized in that the at least one further liquid-crystalline layer is formed from cholesteric liquid-crystalline material.

39. Foil material according to at least one of claims 32 to 38, characterized in that the functional layer is formed from a UV-curing lacquer layer or a cholesteric liquid-crystalline material.

40. Foil material according to at least one of claims 32 to 39, characterized in that the functional layer is formed by an embossing lacquer layer which is embossed.

41. Foil material according to claim 40, characterized in that the embossing lacquer layer is metallized and optionally demetallized in some areas.

42. Film material according to at least one of claims 32 to 41, characterized in that the adhesion of the functional layer to the carrier film is less than to the liquid-crystalline layer.

43. Foil material according to at least one of claims 32 to 42, characterized in that one or more further layers are applied to the functional layer.

44. Foil material according to claim 43, characterized in that a machine-readable and / or decorative and / or reflective layer is applied as a further layer.

45. Foil material according to claim 44, characterized in that a layer is printed as a machine-readable and / or decorative layer which contains machine-readable feature substances, in particular magnetic, electrically conductive, phosphorescent, fluorescent or other luminescent substances.

46. The film material according to at least one of claims 32 to 45, characterized in that the film material comprises an adhesive layer for transferring the sequence of security layers onto a target substrate.

47. Method for transferring a film material, in particular a transfer material, onto a target substrate, in which a film material according to at least one of claims 1 to 46 is placed with the adhesive layer on the target substrate and by the action of heat and / or pressure and / or radiation Target substrate is connected.

48. The method according to claim 47, characterized in that the plastic carrier film is removed during or shortly after application to the target substrate.

49. A method for producing a security element, in particular a security thread or a security element to be applied or transferred, in which a film material is produced according to at least one of claims 1 to 46, and with further layers for embedding in or for application to a security paper or Valuables.

50. The method according to claim 49, characterized in that the security element contains a carrier substrate made of paper or plastic.

51. A method for producing an object of value, such as a security paper or document of value, in which a film material according to at least one of claims 1 to 46 on an object to be secured brought on, in particular by heat and / or pressure and / or radiation.

52. Security element for securing valuables, with a partially present layer made of a liquid-crystalline material, a full-surface functional layer which is arranged directly above the partially present layer made of liquid-crystalline material,

wherein the functional layer is formed by a UV-curing lacquer layer, a layer of cholesteric liquid-crystalline material or an embossing lacquer layer.

53. Security element according to claim 52, characterized in that the security element further comprises a plastic carrier film which is suitable for aligning liquid-crystalline material.

54. Security element according to claim 52 or 53, characterized in that the functional layer is formed by an embossing lacquer layer, embossed, metallized and optionally demetallized in some areas.