EP1744904B2 - Sheeting and methods for the production thereof - Google Patents

Description

The invention relates to a film material for transfer to a target substrate, and to methods for producing such a film material and to 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, to a method for producing a security element and to a method for producing a valuable article, such as a security paper or a value documentary.

Valuables, such as branded goods or documents of value, are often provided with security elements for the purpose of protection, which allow verification of the authenticity of the object of value and 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, at different viewing angles. In many cases holograms, holographic grating images and other hologram-like diffraction structures are used for authenticity assurance, which offer the viewer a viewing angle-dependent diffraction pattern.

Security elements with hologram-like diffraction structures are transferred, inter alia, in the transfer process to the target substrate, for example a banknote. The detachment of the security element from the carrier film is carried out either via so-called release or release layers, which are usually thermally activated, or coated by the low adhesion of the adhesive system. Other security features, such as luster pigments or other optically variable effect colors, are usually printed directly onto a paper substrate.

From the publication EP 0 435 029 A2 For example, a transfer element with a plastic-like layer of a liquid crystal polymer is known, which exhibits a pronounced color-interplay at room temperature. The transfer element comprises, in addition to a carrier film, an optional wax layer, a protective lacquer layer, a layer of a liquid crystal polymer, a colored layer and a hot-melt adhesive layer.

The publication US 2003/0189684 A1 discloses a process for making an anisotropic polymer film on a substrate having a structured surface.

The publication EP 1 120 737 A1 relates to an optical authentication device in combination with a verification tool, wherein the authentication device comprises a first layer of optically anisotropic material which is selectively oriented in different orientations over its surface such that an object is inscribed therein. The verification tool includes another layer of optically anisotropic material that is selectively oriented in different orientations across its surface to decipher the object so that the object can be viewed as the authentication device is viewed through the examination tool.

The publication WO 2004/032099 A relates to a liquid crystal marker, a liquid crystal continuous label body, and a method for producing the liquid crystal marker.

The publication EP 1422 283 A1 , which is a document under Article 54 (3) EPC, relates to the use of a printable polymerizable liquid crystal material as a printable system for the production of polymers and pigments. The publication EP 1132 450 A2 relates to a multilayer reflective film or pigment having viewing-angle-dependent reflective properties.

Solvent-based liquid crystal coatings require orientation-promoting conditions in order to be effective. Typically, special alignment layers are used for this purpose. In particular, alignment layers are used which consist of a linear photopolymer which is exposed to align suitable radiation. Furthermore, liquid crystalline materials can also be aligned by means of alignment layers provided by a finely-structured layer or a shear-stress-oriented layer. The orientation of the liquid-crystalline materials on such alignment layers is complicated by the additional work steps that are usually necessary for this.

Proceeding from this, the object of the invention is to provide 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. Further developments of the invention are the subject of the dependent claims.

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 to align the liquid-crystalline material in the desired shape. According to the invention, the plastic film has a surface structure formed during production. As examples of such plastic carrier sheets suitable for aligning liquid crystal material are PET, PE, BOPP, OPP films and cellulose triacetate.

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

In a preferred embodiment is on the liquid-crystalline layer and applied in the exposed areas according to the carrier film a functional layer over the entire surface. The use of a functional layer also makes it possible to transfer security elements made of liquid-crystalline material that are not present over the entire area, for example printed as a motif, onto a target substrate. If desired or required, the carrier film for the liquid-crystalline layer and the functional layer may be removed during or after the application of the film material to the target substrate. In order to ensure the damage-free detachability of the carrier film of a film material designed as transfer material, the adhesion of the functional layer to the carrier film is advantageously lower than to the liquid-crystalline layer.

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

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

The liquid-crystalline layers are preferably applied as a lacquer layer of nematic, cholesteric or smectic liquid-crystalline material, preferably printed. As printing techniques for the liquid-crystalline layers and / or the functional layer, gravure printing, screen printing, flexographic printing, knifecoating or curtain coating are particularly suitable.

As a functional layer, a UV-curing lacquer layer is preferably applied, in particular printed. The UV-curable lacquer layer expediently contains photoiniators. In individual cases, in particular in the production of a transfer material, a balance must be sought between sufficiently high adhesion of the functional layer to the liquid-crystalline layer to be detached and sufficiently low adhesion to the carrier film.

In a further, alternative embodiment, a layer of cholesteric liquid-crystalline material is applied, in particular printed, as the functional layer. In a third alternative embodiment, an embossing lacquer layer is used as the functional layer. In this case, the embossing lacquer layer is expediently printed on and subsequently embossed, provided with a metal layer, and optionally demetallized in regions, for example, to introduce a negative writing into the metallized embossed structure. The embossed structure advantageously forms an optically active 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 a subsequently applied embossing lacquer layer, the functional layer can advantageously be subjected to a corona treatment or be provided with an adhesion promoter.

In a further preferred embodiment, one or more further layers can be applied to the functional layer, in particular printed, in order to produce more complex layer structures. Preferably, an embossing lacquer layer can be applied as a further layer, in particular printed. After embossing, the embossing lacquer layer is advantageously embossed, metallized and optionally demetallised in some areas.

As a further layer, it is also possible to use a machine-readable and / or decorative layer which is applied at least regionally, 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 on this already applied further layer.

Likewise, as a further layer, a reflective layer can be applied. 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, in addition to the layer composite already described, one or more further layer collars are produced and, for example, connected to one another via laminating lacquer layers. In this way, it is possible to realize a variety of complex security layer structures, which make it possible to achieve a layer sequence which is often unrealisable in known multilayer security elements and enhances the effects of the security element. Optimal production conditions can be selected for the individual layer composites by the separate production. Thus, according to the invention, it is also possible to combine layered composites which require mutually exclusive production conditions or interfering carrier foils, since the carrier foils can be removed during or after the joining of the partial layer composites.

In particular, according to the invention, a second security layer composite present on a second carrier film can be provided, 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 applied by applying an embossing lacquer layer to the second carrier foil, embossing, metallizing and possibly areawise demetallizing the embossing lacquer layer produced.

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

The second security layer composite may also comprise a reflective layer. In all variants, the reflective layer may advantageously be formed by a metal layer or, in the case of more complex structures, by a reflective thin-film element having a viewing angle-dependent color impression. In the latter case, the 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. The reflection layer of the thin-film element is preferably formed from an opaque or semitransparent 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 embodiment possibility, the thin-film element is formed with a plurality of dielectric spacer layers, wherein adjoining layers having greatly different refractive indices are formed.

According to a further variant of the invention, the second security layer composite comprises an optically active 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.

In all variants, a layer which contains machine-readable feature substances, in particular magnetic, electrically conductive, phosphorescent, fluorescent or other luminescent substances, can be imprinted as a machine-readable and / or decorative layer.

The invention also includes a sheet material for security elements, which can be produced, in particular, by one of the production methods described above, and which contains a security layer sequence with a plastic carrier film which is suitable for aligning liquid-crystalline material and with a first partially present layer of liquid-crystalline material , which is present in aligned form on the plastic carrier film. 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 functional layer projecting over the entire area. 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 may also be formed of a cholesteric liquid-crystalline material.

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

The invention also includes a security element for securing valuables with a partially present layer of a liquid-crystalline material, in particular a nematic liquid-crystalline material, and a functional layer provided over the entire area, which is arranged directly above the partially present layer of liquid-crystalline material. The functional layer is formed by a UV-curing lacquer layer, a layer of cholesteric liquid-crystalline material or an embossing lacquer layer.

The security element 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 certain areas.

The optically effective microstructure may 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 of transferring a sheet material to a target substrate, wherein a sheet material of the type described is placed with the adhesive layer on the target substrate and bonded to the target substrate by heat and / or pressure. When using radiation-curing adhesives, the film material is correspondingly connected by pressure and radiation with the target substrate. If the film material is formed as a transfer material, the plastic carrier film of the liquid-crystalline layer is expediently removed during or shortly after application 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 and equipped with further layers for embedding in or for application to a security paper or a valuable article, in particular value document. The security element contains preferably a carrier substrate made of paper or plastic.

In a method for producing a valuable article, such as a security paper or a document of value, a film material of the type described is applied to an object to be protected, in particular adhered by heat and / or pressure and / or radiation. Advantageously, the surface of the security paper or valuables can be specially treated to improve the adhesion of the film material on the surface and the optical efficiency of the film material. For this purpose, in particular a bonding agent can be used, which is applied to the surface of the security paper.

Valuables within the meaning of the present invention are in particular banknotes, stocks, bonds, certificates, vouchers, checks, high-quality admission tickets, but also other counterfeit-endangered papers, such as passports and other identification documents, as well as product security elements, such as labels, seals, packaging and the like. The term "object of value" in the following includes all such objects, documents and product protection means. The term "security paper" is understood to mean the precursor that can not yet be processed to a value document which, in addition to the security element, has further authenticity features, such as e.g. in volume provided luminescent substances may have. Security paper is usually in quasi-endless form and will be further processed at a later date.

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

Fig. 1

eine schematische Darstellung einer Banknote mit einem eingebetteten Sicherheitsfaden und einem aufgeklebten Sicherheitstreifen, jeweils nach einem Ausführungsbeispiel der Erfindung,

Fig. 2

eine Aufsicht auf einen Teilbereich des Sicherheitsstreifens der Fig. 1, wie er bei Betrachtung ohne Hilfsmittel bzw. bei Betrachtung durch einen Polarisator erscheint,

Fig. 3

in Querschnittsdarstellung einen Zwischenschritt bei der Herstellung eines erfindungsgemäßen Folienmaterials,

Fig. 4

eine Darstellung wie in Fig. 3 eines Folienmaterials nach einem weiteren Ausführungsbeispiel der Erfindung,

Fig. 5

die Herstellung eines Folienmaterials nach einem weiteren Ausführungsbeispiel der Erfindung, wobei (a) und (b) einen ersten und zweiten Schichtverbund vor dem Kaschieren und (c) das fertige Folienmaterial zeigt,

Fit. 6

eine Darstellung wie in Fig. 5(c) eines Folienmaterials nach einem weiteren Ausführungsbeispiel der Erfindung,

Fig. 7

eine Darstellung wie in Fig. 3 eines Folienmaterials nach einem weiteren Ausführungsbeispiel der Erfindung,

Fig. 8

die Herstellung eines Folienmaterials nach einem weiteren Ausführungsbeispiel der Erfindung, wobei (a) und (b) einen ersten und zweiten Schichtverbund vor dem Kaschieren und (c) das fertige Folienmaterials zeigen,

Fig. 9

eine Variante des Ausführungsbeispiels von Fig. 8(c), das sich von diesem nur in der Ausgestaltung des zweiten Sicherheitsschichtverbunds unterscheidet,

Fig. 10

die Herstellung eines Folienmaterials nach einem weiteren Ausführungsbeispiel der Erfindung, wobei (a), (b) und (c) einen ersten, zweiten und dritten Schichtverbund vor dem Kaschieren und (d) das fertige Folienmaterial zeigen,

Fig. 11

die Übertragung des als Transfermaterial ausgebildeten Folienmaterials der Fig. 5 auf ein Zielsubstrat,

Fig. 12

eine Darstellung eines Sicherheitselements nach einem weiteren Ausführungsbeispiel der Erfindung, und

Fig. 13

in (a) eine Querschnittsdarstellung eines Folienmaterials nach einem weiteren Ausführungsbeispiel der Erfindung und in (b) eine Aufsicht auf einen Teilbereich des Folienmaterials.

Show it:

Fig. 1

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

Fig. 2

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

Fig. 3

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

Fig. 4

a representation like in Fig. 3 a sheet material according to a further embodiment of the invention,

Fig. 5

the production of a film material according to a further exemplary embodiment of the invention, wherein (a) and (b) show a first and second layer composite before laminating and (c) the finished film material,

Fit. 6

a representation like in Fig. 5 (c) a sheet material according to a further embodiment of the invention,

Fig. 7

a representation like in Fig. 3 a sheet material according to a further embodiment of the invention,

Fig. 8

the production of a film material according to a further exemplary embodiment of the invention, wherein (a) and (b) show a first and second layer composite before laminating and (c) the finished film material,

Fig. 9

a variant of the embodiment of Fig. 8 (c) which differs from this only in the design of the second security layer composite,

Fig. 10

the production of a film material according to a further exemplary embodiment of the invention, wherein (a), (b) and (c) show a first, second and third layer composite prior to lamination and (d) the finished film material,

Fig. 11

the transfer of the trained as a transfer material sheet material of Fig. 5 on a target substrate,

Fig. 12

a representation of a security element according to a further embodiment of the invention, and

Fig. 13

in (a) is a cross-sectional view of a film material according to another embodiment of the invention and in (b) is a plan view of a portion of the film material.

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

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

Fig. 2 shows a plan view of a portion of the security strip 16, as it appears when viewed without aids or when viewed through a linear polarizer 20. Viewed without aids, the security strip 16 shows shiny metallic, optically variable diffraction structures 22, such as holograms or kinegrams. Such diffraction structures 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 may 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 visualized with a circular polarizer. These structures, which are virtually invisible to the naked eye, can be used to check the authenticity of the banknote 10.

The construction and production of security elements according to the invention will first be explained by means of simpler and then increasingly complex security element structures.

Fig. 3 shows a cross-sectional view of an intermediate step in the production of a film material 30, for example, in a security thread 12 or a security strip 16 of the in Fig. 1 shown type can be used. 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 Nematenschicht 34 is typically printed in the form of a motif of patterns, characters or a coding, for example in the form of in Fig. 2 shown honeycomb pattern. Due to the surface structure of the carrier film 32, which specifies a preferred direction for the alignment of the liquid-crystalline material, the nemate layer 34 can be printed directly onto the carrier film.

On the nemate layer 34 may be at least partially overlapping this another, not shown here layer of liquid crystal material, e.g. from cholesteric liquid crystalline material, in the form of a motif also partially printed.

On the Nematenschicht 34 and the carrier film 32 is fully functional layer, e.g. a UV-crosslinkable lacquer layer 36 printed. Alternatively, it is also possible to use a layer of cholesteric liquid-crystalline material or an embossing lacquer layer as the functional layer 36. In order to be able to transfer the regionally present nematic layer 34 and, if appropriate, the further layer of cholesteric liquid-crystalline material to a target substrate, such as a security paper or a document of value, with removal of the carrier film 32 in a subsequent operation, the functional layer is preferably designed such that the latter Adhesion to the carrier film 32 is less than to the Nematenschicht 34th

Subsequently, an adhesive layer 38 is applied to the functional layer 36, with which the layer composite of carrier film 32, Nematenschicht 34 and functional layer 36 on a target substrate, such as a security paper, a document of value or another thread or strip structure 35, can be laminated. If desired or required, the carrier film 32 for the liquid-crystalline materials 34 and 36 can be removed by separation winding last. The damage-free detachability of the carrier film 32 is ensured by the greater adhesion of the functional layer 36 to the nemate layer 34.

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

Before applying the adhesive layer 38, a further, not shown here layer can be printed on the functional layer 36. The further layer can be provided in particular with recesses or in the form of patterns, characters or codes. In order to enable a good recognition of the color and polarization effects of the nematic or optionally cholesteric liquid crystal layers, 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 suitable when the functional layer 36 consists of cholesteric liquid-crystalline material. If the functional layer 36 is present as a UV-crosslinkable lacquer layer, the further layer can be provided by a metal layer into which recesses, for example in the form of a negative writing, can be introduced by partial demetallization. Under the layer another, eg machine-readable layer can be printed. Machine-readable security features can also be accommodated in the further layer itself. The further manufacturing process then proceeds, as already related to Fig. 3 described.

In the negative-proofed film material 60 of the Fig. 4 On a carrier film 32, a nematic liquid crystal layer 34 is printed. A UV-curable embossing lacquer layer 62, whose adhesion to the carrier foil 32 is smaller than that of the nematode layer 34, is printed over the carrier foil 32 and the nematic layer 34 so that the embossing lacquer layer 62 fulfills the function of the functional layer described above during transfer of the foil material 60 to a target substrate ,

Subsequently, into the embossing lacquer layer 62 a desired embossed structure 64, for example a diffraction structure, is formed. embossed and a reflective layer 66, for example in the form of a metal layer, applied, in particular vapor-deposited, in which by partial demetallization recesses 68, in the embodiment in the form of negative writing, are introduced. Alternatively, the embossing structure 64 may also be provided with a high refractive index layer. Examples of suitable high-index materials are CaS, CrO ₂ , ZnSi, TiO ₂ or SiO _x . Finally, an adhesive layer 38 is applied to the composite layer for transfer to the target substrate.

Instead of a reflective layer 66 in the form of a metal layer or a high refractive index layer, the embossing pattern 64 can also be provided with a color shift effect thin film element, as described below with reference to FIG Fig. 6 is described in detail.

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 overlap with the metal layer 66. For example, a commercially available printing ink can be printed, which is then recognizable in the recesses or demetallized areas of the embossing lacquer layer when viewing the foil material applied to a substrate. The ink, as well as the adhesive layer 38, may also contain machine-readable feature substances, such as e.g. contain magnetic, electrically conductive, phosphorescent or fluorescent substances.

Fig. 5 illustrates the production of a sheet material 70 according to another embodiment of the invention. It will, as in Fig. 5 (a) a first layer composite 72 is produced from a first carrier foil 32, a nematic liquid crystal layer 34 and a functional layer 36, as described in connection with FIG Fig. 3 described. The functional layer 36 may be formed, for example, by a UV-crosslinkable lacquer layer or a layer of cholesteric liquid-crystalline material.

In addition, as in Fig. 5 (b) a second security layer composite 74 is produced by printing on a second carrier film 80 an embossing lacquer layer, embossing a desired embossed structure, in the exemplary embodiment a diffraction structure, into the embossing lacquer, onto which embossed layer 82 a metal layer 84 is vapor-deposited, and by partial demetallization of the Metal layer 84 recesses 86, for example, be generated in the form of negative writing.

The second security layer composite 74 is applied via an adhesive layer 76 (FIG. Fig. 5 (c) ) laminated on the first layer composite 72, as by the FIGS. 5 (b) and 5 (a) connecting arrow 78 indicated. Subsequently, the second carrier film 80 is removed by a separation winding and applied for the transfer of an adhesive layer 38 on the Schichtverbünd thus produced, as in Fig. 5 (c) shown. If the film material is to be used as a transfer material for transfer to a target substrate, then the carrier film 32 can be removed 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 polarization effect features are thus not affected by films in their effect 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 separating windings and further layers of the thread structure, such as a primer and a heat sealing lacquer, can be applied to the then exposed liquid crystal layers 34 and 36.

The reduced by the detachment of the second carrier film 80 protection function for the metallization can be compensated by protective lacquer layers. Conventional protective lacquer layers are optically largely isotropic 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, dark-colored layer can optionally be partially applied to the security layer composite 74, in order to ensure good visibility of the color effect of the cholesteric liquid crystal layer. Alternatively, the embossing lacquer layer 82 can be darkened.

The second security layer composite may also contain only a metallic reflection layer instead of the embossed structure, which is preferably integrated with large Demetallisierungsanteilen in a print motif. Compared to conventional designs, the film material according to the invention then has an additional test plane with the nematic layer 34, which 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. Fig. 6 to an embodiment, whose production analogous to that at Fig. 5 described manufacturing process runs.

For the production of the film material 90 of the Fig. 6 for example, with a security thread 12 or a security strip 16 of the in Fig. 1 A first layer composite of a first carrier foil 32, a nematic liquid crystal layer 34 and a functional layer 36, eg a UV-crosslinkable lacquer layer, and a second security layer composite of a second carrier foil, onto which a thin-film element 92 with a color-shift effect is applied becomes.

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. The color shift effect is based on such thin-film elements on viewing angle-dependent Interference effects due to multiple reflections in the different sublayers of the element. The absorber layer 98 and / or the dielectric spacer layer 96 may have recesses in the form of patterns, characters or codes in which no color-shift effect can be recognized. The reflection layer 94 may also have recesses in the form of patterns, characters or codes, which then form transparent or semitransparent regions 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 may 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 of reflection layer and an absorbing dielectric layer is also possible.

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 separation winding. For transfer to the target substrate, an adhesive layer 38 is exposed to the now exposed one. Rear side of the thin-film element 92 applied. On the exposed back side of the thin-film element 92, prior to the application of the adhesive layer 38, further machine-readable and / or decorative layers, e.g. with a magnetic paint, are applied. After the transfer, the first carrier film 32 can also be removed.

In a variant of the embodiment of FIG Fig. 6 For example, a sheet material for a double-sided security thread having a liquid crystal-based color-tilting or polarizing effect which is recognizable to the viewer from one side and a thin-film element having a color-shift effect recognizable from the second side is produced.

The film material differs from that in Fig. 6 shown in that the functional layer 36 is formed of cholesteric liquid crystalline material. In order to allow in particular a good visibility of the color effect of the cholesteric liquid crystal layer, the adhesive layer 76 also forms a dark, preferably black background. The adhesive layer 76 can be dyed or, if appropriate, subsequently blackened by the action of a laser beam. The thin film element 92 has an order reverse to the layer order described above, ie, the reflective layer is in the film material adjacent to the adhesive layer 76, and the absorber layer is adjacent to the adhesive layer 38.

Fig. 7 shows a film material 100 according to another embodiment of the invention, in which, as in Fig. 3 on a smooth plastic carrier film 32, which is suitable for aligning liquid-crystalline material, a nematic liquid crystal layer 34 and a UV-crosslinkable functional layer 36, for example of cholesteric liquid crystal material, are printed. An embossing lacquer layer is further printed onto the functional layer 36, a desired embossed structure, in the exemplary embodiment a diffraction structure, embossed into the embossing lacquer layer, and a metal layer 104 is vapor-deposited onto the embossed layer 102. In the. Metal layer 104 are introduced by partial demetallization recesses 106 in the form of negative writing. 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 the diffraction structure and the liquid-crystalline layers 34 and 36 can be perceived over the entire area on a dark background which is formed by a corresponding additional layer, for example a black imprint, or else on the target substrate.

In order to improve the adhesion of the embossing lacquer layer 102 on the functional layer 36, the latter is advantageously subjected beforehand to a corona treatment or it is provided with a suitable adhesion promoter. An adhesive layer 38 is applied to the entire layer composite for application to the target substrate. Depending on the choice of the mediating layer and the demands on the brilliance, the carrier film 32 can be removed after the application of the film material 100 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 described with reference to FIGS Fig. 8 explained.

First, as in Fig. 8 (a) a first layer composite 112 of a first carrier foil 32, a nematic liquid crystal layer 34 and a functional layer 36, for example of cholesteric liquid crystal material, produced as in Fig. 3 described. A second security layer composite 114 is produced by applying to a second carrier foil 120 a screened aluminum layer 122 with recesses in the form of negative writing, and onto the aluminum layer a magnetic layer 124, in the exemplary embodiment in the form of a coding, is applied. This second security layer composite 114 is in Fig. 8 (b) shown.

In another embodiment, not shown here, the aluminum layer 122 can also be provided as a full-surface layer with recesses, for example in the form of a negative writing, to which in turn the magnetic layer 124 is applied.

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

In a variant of the embodiment of FIG Fig. 8 For example, instead of the magnetic layer 124 applied in the form of a coding, it is also possible to use a dark, in particular black layer with recesses and a magnetic layer in regions, for example in the form of magnetic bits. In particular, not all black areas need to be magnetic at the same time. In this way, a magnetic coding in the black layer can be optically hidden.

Another variant of the embodiment of Fig. 8 , which differs only in the configuration of the second security layer composite, is in Fig. 9 shown. The second security layer composite 132 of the film material 130 of the Fig. 9 instead of the screened aluminum layer, a full-area, semitransparent 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 in the production of the security thread 130 follows that described above in connection with FIG Fig. 8 given description.

Fig. 10 illustrates the production of a film material 140 for a hologram security thread with magnetic coding and nematic printing according to a further 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 made of a modified UV-curing lacquer and a first adhesive layer 158, as shown in FIG Fig. 10 (a) shown.

For producing a second security layer composite 160, which in Fig. 10 (b) an embossing lacquer layer is printed on a second plastic carrier foil 162, a desired diffraction structure is embossed into the embossing lacquer and a metal layer 166, for example an aluminum layer, vapor deposited on the embossed layer 164, in which, as already described in connection with FIG Fig. 5 described by partial demetallization recesses 168, for example, be generated in the form of negative writing. A magnetic layer 170 in the form of a coding is applied to the rear side of the carrier foil 162 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 functions as a cover element in the finished security thread, is produced by applying a full-area metal layer 184 to a third, particularly thin plastic carrier film 182 and providing the metal layer 184 with another full-surface adhesive layer 186, as in FIG Fig. 10 (c) shown.

The first layer composite 150 with the nematic print is then laminated onto the top side 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). Additional layers 146, such as a white topcoat, required for embedding the security thread in a security paper can then be applied to the back side of the third carrier film 182. Finally, for transfer to the target substrate, an adhesive layer 38, such as a heat sealing lacquer, is applied as in Fig. 10 (d) shown. The backing film 152 of the first layer composite 150 may then be removed by means of parting and other layers of the thread structure, such as a primer and a heat sealing lacquer, may be applied to the then exposed liquid crystal layers 154 and 156.

The application of the described security elements to a target substrate 200, eg a security paper or a plastic film, will be made with reference to FIG Fig. 11 by way of example with reference to the film material present as transfer material 70 Fig. 5 explained. The transfer material 70 is placed with the heat seal adhesive layer 38 on the target substrate 200 and pressed. The pressing can be done for example with a not shown heated transfer punch or a transfer roller. Under pressure and heat, the adhesive layer 38 connects in the desired regions 202 with the target substrate 200, so that a transfer element, possibly with a predetermined outline shape, arises. The carrier film 32 of the liquid crystal layers 34, 36 can be removed during the application process or shortly thereafter. Prior to applying the transfer material 70 to the target substrate 200, the surface of the target substrate 200 may 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 this can be improved. For example, a bonding agent can be applied to the surface of the transfer material.

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

Before the adhesive layer 38 is applied, further layers, in the exemplary embodiment, a machine readable layer 196 containing 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, 94, machine-readable layer 196 and cover layer 198 is then laminated by means of the adhesive layer 38 onto a target substrate 199, such as a PET film.

If desired or required, the plastic carrier film 32 can be removed by separation winding again. In this case, it is to be ensured that the adhesion of the functional layer 192 to the carrier film 32 is lower than to the nemate layer 34.

However, it is also possible to leave the carrier film 32 in the layer composite. Such a configuration is particularly suitable when the security element is present in the form of a security strip in a papermaking-made or punched-out window of a banknote. The carrier film 32 then serves, inter alia, as a cover film.

Fig. 13 (a) shows in cross-sectional representation a film material 210 according to a further embodiment of the invention, in which, as in Fig. 3 On a smooth, transparent plastic carrier film 32, a nematic liquid crystal layer 34 and a functional layer 36 are printed from cholesteric liquid-crystalline material. The nemate layer 34 is typically printed in the form of a motif of patterns, characters or a code, for example in the form of in Fig. 13 (b) shown letter sequences "PL".

In order to allow a good visibility of the polarization effects of the nematic liquid crystal layer, as associated with Figure 3 In the regions 212, prior to the application of the adhesive layer 38, a reflective metal layer 216 is applied over the nemate layer 34. In the metal-layer-free regions 214, an absorbent imprint with a commercially available, in particular black ink is further printed. This provides a background dark layer 218 essential to the visibility 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, Nematenschicht 34, functional layer 36, Metaschicht 216 and dark background layer 218 on a target substrate, such as a security paper, a document of value or another thread or strip structure, can be laminated , If desired or required, the carrier film 32 for the liquid-crystalline materials 34 and 36 can be removed by separation winding last. The damage-free detachability of the carrier film 32 is ensured by the greater adhesion of the functional layer 36 to the Nematenschicht 34.

In a variant of the embodiment of FIG Fig. 13 For example, the nemate layer 34 may also be present in the region 214 in the form of a motif. When viewing the film material applied to a target substrate with the naked eye, only the color-shift effects of the cholesteric liquid-crystal layer 36 can be seen. On the other hand, if the film material is viewed through a linear polarizer, the structures formed by the nemate layer 34 appear.

Claims (46)

1. A method for manufacturing a foil material (30) for security elements, having the method steps:

   a) providing a plastic substrate foil (32) that is suitable for aligning liquid crystal material,

   b) discontiguously applying a first layer (34) comprising a liquid crystal material to the substrate foil (32), the liquid crystal material being aligned,

   characterized in that in step a) a foil that exhibits a surface pattern created upon manufacture is provided as the substrate foil (32) and that has, due to its interior structure, a preferred direction that is sufficient to align the liquid crystal material in the desired form in step b), and that to the first liquid crystal layer (34) and the substrate foil (32) contiguously either

   i) a functional layer (36) in form of an UV-curing lacquer layer is applied, especially imprinted,

   ii) a functional layer (36) in form of a layer of cholesteric liquid crystal material is applied, especially imprinted, or

   iii) a functional layer (36) in form of an embossing lacquer layer (62) is applied, especially imprinted, which is subsequently metallized and, if applicable, demetallized in some areas.
2. The method according to claim 1, characterized in that a PET, PE, BOPP, OPP foil, or a cellulose triacetate foil is provided as plastic substrate foil (32).
3. The method according to at least one of claims 1 to 2, characterized in that an adhesive layer (38) is applied for transferring the layered composite formed to a target substrate.
4. The method according to at least one of claims 1 to 3, characterized in that the foil material (30) is formed as an application material.
5. The method according to at least one of claims 1 to 3, characterized in that the foil material (30) is formed as a transfer material.
6. The method according to claim 5, characterized in that the adhesion of the functional layer (62) to the substrate foil (32) is less than to the liquid crystal layer (34).
7. The method according to at least one of claims 1 to 6, characterized in that at least one further liquid crystal layer is applied discontiguously between the discontiguously applied first liquid crystal layer (34) and the functional layer (36).
8. The method according to one of claims 1 to 7, characterized in that the first liquid crystal layer (34) and/or the further liquid crystal layers are applied in the form of patterns, characters or codes.
9. The method according to at least one of claims 1 to 8, characterized in that the first liquid crystal layer (34) and/or the further liquid crystal layers are applied, preferably imprinted, as a lacquer layer comprising nematic, cholesteric or smectic liquid crystal material.
10. The method according to one of claims 1 to 9, characterized in that the first liquid crystal layer (34) and/or the further liquid crystal layers and/or the functional layer (36) are imprinted by means of intaglio printing, screen printing, flexo printing, knife coating or curtain coating.
11. The method according to at least one of claims 1 to 10, characterized in that the functional layer (36) is corona treated or furnished with an adhesion promoter.
12. The method according to at least one of claims 1 to 11, characterized in that one or more layers are applied to, especially imprinted on, the functional layer (36).
13. The method according to claim 12, characterized in that, as a further layer, an embossing lacquer layer is applied, especially imprinted, that is subsequently embossed, metallized and, if applicable, demetallized in some areas.
14. The method according to claim 12 or 13, characterized in that, as a further layer, a machine-readable and/or decorative layer is applied at least in some areas, especially imprinted.
15. The method according to claim 14, characterized in that the machine-readable and/or decorative layer is imprinted in the form of patterns, characters or codes.
16. The method according to at least one of claims 12 to 15, characterized in that a reflective layer is applied as a further layer.
17. The method according to at least one of claims 1 to 16, characterized in that the substrate foil (32) forms a first layered composite (72) with the liquid crystal material (34) and, if applicable, the further layers, and a second security layered composite (74) is provided that is present on a second substrate foil (80) and that is joined with first layered composite via an adhesive layer.
18. The method according to claim 17, characterized in that the second security layered composite (74) is manufactured by applying an embossing lacquer layer to the second substrate foil (80) and embossing, metallizing and, if applicable, demetallizing the embossing lacquer layer in some areas.
19. The method according to claim 17, characterized in that the second security layered composite (74) is manufactured by applying a screened metal layer, especially in the form of patterns, characters or codes, or a semitransparent metal layer to the second substrate foil (80) and by subsequently applying at least a machine-readable and/or decorative layer to the metal layer, especially in the form of patterns, characters or codes.
20. The method according to at least one of claims 17 to 19, characterized in that the second security layered composite (74) comprises a reflective layer.
21. The method according to claim 17 or 20, characterized in that the reflective layer is formed by a metal layer.
22. The method according to claim 15 or 20, characterized in that the reflective layer is formed by a reflective thin-film element (92) having a viewing-angle-dependent color impression.
23. The method according to claim 22, characterized in that the thin-film element (92) is formed having a reflection layer (94), an absorber layer (98) and a dielectric spacing layer (96) disposed between the reflection layer and the absorber layer.
24. The method according to at least one of claims 17 to 19, characterized in that the second security layered composite (74) comprises an optically effective microstructure.
25. The method according to claim 24, characterized in that the optically effective microstructure is formed as a diffraction pattern, as a matte pattern, as an arrangement of microlenses or as an arrangement of micromirrors.
26. The method according to at least one of claims 1 to 15, characterized in that, as a machine-readable and/or decorative layer, a layer is imprinted that includes machine-readable feature substances, especially magnetic, electrically conductive, phosphorescent, fluorescent or other luminescent substances.
27. A foil material (30) for security elements, especially manufacturable according to one of claims 1 to 30, having

    - a plastic substrate foil (32) that is suitable for aligning liquid crystal material, and having

    - a discontiguously present first layer (34) comprising a liquid crystal material that is present in aligned form,

    characterized in that the plastic substrate foil (32) exhibits a surface pattern created upon manufacture and that has, due to its interior structure, a preferred direction that is sufficient to align the liquid crystal material in a desired form, and that to the first liquid crystal layer (34) and the substrate foil (32) contiguously either

    i) a functional layer (36) in form of an UV-curing lacquer layer is applied, especially imprinted,

    ii) a functional layer (36) in form of a layer of cholesteric liquid crystal material is applied, especially imprinted, or

    iii) a functional layer (36) in form of an embossing lacquer layer (62) is applied, especially imprinted, metallized and, if applicable, demetallized in some areas.
28. The foil material (30) according to claim 27, characterized in that the plastic substrate foil (32) is a PET, PE, BOPP and OPP foil, or a cellulose triacetate foil.
29. The foil material (30) according to claim 27or 28, characterized in that a contiguously present functional layer formed from an UV-curing lacquer layer or a cholesteric liquid crystal material is disposed above the discontiguously present first liquid crystal layer (34) and the substrate foil (32).
30. The foil material (30) according to claim 31 or 32, characterized in that a contiguously present functional layer (36) formed by an embossing lacquer layer (62) that is embossed is disposed above the discontiguously present first liquid crystal layer (34) and the substrate foil (32).
31. The foil material (30) according to one of claims 29 to 30, characterized in that at least one further liquid crystal layer is applied discontiguously between the discontiguously applied first liquid crystal layer (34) and the functional layer (36).
32. The foil material (30) according to at least one of claims 27 to 31, characterized in that the first liquid crystal layer (34) is formed from a nematic liquid crystal material.
33. The foil material (70) according to at least one of claims 27 to 32, characterized in that the first liquid crystal layer (34) forms a phase-shifting layer.
34. The foil material (30) according to at least one of claims 27 to 33, characterized in that the at least one further liquid crystal layer is formed from cholesteric liquid crystal material.
35. The foil material (30) according to at least one of claims 29 to 34, characterized in that the adhesion of the functional layer (62) to the substrate foil (32) is less than to the liquid crystal layer (34).
36. The foil material (30) according to at least one of claims 29 to 35, characterized in that one or more further layers are applied to the functional layer (36).
37. The foil material (30) according to claim 36, characterized in that a machine-readable and/or decorative and/or reflective layer is applied as a further layer.
38. The foil material (30) according to claim 37, characterized in that, as a machine-readable and/or decorative layer, a layer is imprinted that includes machine-readable feature substances, especially magnetic, electrically conductive, phosphorescent, fluorescent or other luminescent substances.
39. The foil material (30) according to at least one of claims 27 to 38, characterized in that the foil material (30) comprises an adhesive layer (38) for transferring the security layer sequence to a target substrate.
40. A method for transferring a foil material (30), especially a transfer material, to a target substrate, in which a foil material (30) according to at least one of claims 1 to 39 is laid with the adhesive layer (38) on the target substrate and joined with the target substrate by influence of heat and/or pressure and/or radiation .
41. The method according to claim 40, characterized in that the plastic substrate foil (32) is removed upon or shortly after the application to the target substrate.
42. A method for manufacturing a security element, especially a security thread or a security element to be applied or transferred, in which a foil material (30) is manufactured according to at least one of claims 1 to 39 and is furnished with further layers for embedment in or for application to a security paper or a valuable article.
43. The method according to claim 42, characterized in that the security element includes a carrier substrate comprising paper or plastic.
44. A method for manufacturing a valuable article, such as a security paper or value document, in which a foil material (30) according to at least one of claims 1 to 41 is applied to an article to be secured, especially is affixed by heat and/or pressure and/or radiation action.
45. A security element for securing valuable articles, having

    - a discontiguously present layer (34) comprising a liquid crystal material,

    - a contiguously present functional layer (36) that is disposed directly over the discontiguously present layer (34) comprising liquid crystal material,

    the functional layer (36) being formed by a UV-curing lacquer layer, a layer comprising cholesteric liquid crystal material or an embossing lacquer layer (62) and wherein the security element further comprises a plastic substrate foil (32) that is suitable for aligning liquid crystal material and that exhibits a surface pattern created upon manufacture and that has, due to its interior structure, a preferred direction that is sufficient to align the liquid crystal material in a desired form.
46. The security element according to claim 45, characterized in that the functional layer is formed by an embossing lacquer layer (62), and is embossed, metallized and, if applicable, demetallized in some areas.

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