CN111788075B

CN111788075B - Method for producing a security element transfer material and security element transfer material

Info

Publication number: CN111788075B
Application number: CN201980014767.0A
Authority: CN
Inventors: C.富泽; J.席纳贝克; B.托伊费尔
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient GmbH
Priority date: 2018-03-21
Filing date: 2019-03-14
Publication date: 2022-03-01
Anticipated expiration: 2039-03-14
Also published as: DE102018002306A1; WO2019179654A1; CN111788075A; EP3768521A1; EP3768521B1

Abstract

The invention relates to a method for producing a security element transfer material having a security element provided on a support substrate and designed as a transfer element, the method comprises a) providing a support substrate (1) which is provided in succession with a composite of a security element layer and a mask (4) having at least one recess, wherein the security element layer composite has a feature layer (2) which is detachably connected to the carrier substrate and which displays an optically variable effect and an adhesive layer (3), said feature layer being oriented towards the viewer after the security element has been transferred onto the document of value substrate, wherein the recesses along the mask are configured as a security element layer composite provided with embossed lines to be transferred onto the substrate of the document of value, b) the mask is peeled off from the support substrate together with the security element layer composite which is masked by the mask and is present outside the recesses of the mask.

Description

Method for producing a security element transfer material and security element transfer material

Technical Field

The invention relates to a method for producing a security element transfer material having a security element provided on a support substrate and embodied as a transfer element, comprising

a) Providing a support substrate which is provided in succession with a composite of the security element layer and a mask having an indentation, wherein the composite of the security element layer has a feature layer which exhibits an optically variable effect and which is connected to the support substrate in a separable manner and an adhesive layer, which feature layer is oriented toward the viewer after transfer of the security element onto the document of value substrate, wherein the indentation along the mask is configured with the composite of the security element layer provided with stamping lines to be transferred onto the substrate of the document of value,

b) the mask is peeled off from the support substrate together with the security element layer composite masked by the mask and present outside the recesses of the mask.

Furthermore, the invention relates to a security element transfer material obtainable by the invention.

Background

Valuable items, such as brand goods or valuable documents, in particular banknotes, are often designed with security elements which allow the authenticity of the valuable item to be checked and at the same time serve to prevent unauthorized copying. The security element used for this purpose is often not provided separately, but rather in the form of a transfer tape having a plurality of security elements in the form of transfer elements. The transfer belt is characterized in that the security element is prepared on a support layer, wherein the order of the layers of the transfer element must be reversed from the order in which it is later present on the article to be protected. The carrier layer is usually removed from the layer structure of the security element during the transfer process. The transfer tape has an adhesive layer on the side opposite the carrier layer, and is usually made of a heat-sealing compound or a heat-sealing varnish which melts during the transfer of the security element and bonds the security element to the object to be secured. The transfer belt is applied to the article with a heat seal adhesive layer and is pressed by a heated transfer stamp or transfer roller and transferred to the article in the contour shape of the heated transfer stamp. Transfer of a transfer element, a transfer belt and a transfer element onto a target substrate are described, for example, in patent documents EP 0420261B 1 and WO 2005/108108 a 2.

It has been found in practice that, precisely when using more stable and/or more flexible UV embossing lacquers, transfer elements, for example transfer patches, cannot be torn off cleanly at the edge of the heating field. This results in unclean edges and may also result in residues of the film composite being torn from the layer composite in the non-bonded areas remaining on the transferred patch. This residue is undesirable because it can then peel off and affect subsequent processing steps, such as the printing process, in the form of impurities.

In addition to shaping the transfer elements during transfer by means of a transfer stamp, each transfer element can also be present on the transfer belt already pre-shaped to the desired contour. It is useful to pre-process the separate individual security elements when the security element has a layer structure which makes it difficult to precisely separate the entire layer structure during the transfer process. This is the case, for example, when the layer structure of the security element to be transferred has a permanently supporting substrate, for example a plastic film. The support substrate within the layer structure of the security element is expedient when the security element has to be constructed particularly securely, for example when it has to be self-supporting since it should be used to close a continuous opening in an article to be secured. Depending on the size of the article and the opening to be closed, a high need for stability of the security element may be provided here. For example, banknotes are subjected to high loads, seizing, bending and in some cases also exposure to moisture during circulation. As with banknote paper itself, the security element must also withstand these loads, since otherwise there is a risk of exposing successive openings in the banknote after a period of circulation.

Those security elements whose layer structure comprises a solid support substrate, usually a plastic film, must be present as a prefabricated individual element on the transfer element, which means that the contour of the security element must be cut beforehand in the security element material. The preliminary cutting can be carried out, for example, by means of a laser.

The problem arises here that the cutting depth must be controlled very precisely, on the one hand in order to sever the entire layer structure of the security element, but on the other hand in order not to damage the support material that is separated during the transfer. As a support material, a plastic film is generally used. Plastic films have a higher tear strength, but a lower continuous tear strength. It is difficult to avoid tearing of the plastic film that the security element transfer material present as a continuous material tears at a plurality of points during the transfer of the security element onto the value item. It must also be noted that the layer structure to be severed or the support film not to be severed is a material with a thickness in the order of microns. The layer structure of the security element typically has a thickness of approximately 20 μm to 30 μm, and the support film typically has a thickness of 10 μm to 20 μm. In view of the precision required here, it is difficult to carry out the cutting process in such a way that, despite complete severing of the layer structure of the security element, the cutting process is stopped in such a way that the carrier film is not cut at any point. However, since the support film is partially cut, the security element transfer material loses its stability and may even tear, so that precise and friction-free application of the security element from the continuous material onto the product to be protected is no longer ensured.

From WO 2010/031543 a1, a security element transfer material in the form of a continuous material is known, in which the security element is pre-cut to the desired contour shape and the pre-cut element can then be transferred to the product to be secured without the risk of the support material possibly tearing. The security element transfer material is a continuous material, in particular a web-shaped material having a length of several hundred meters and a width of several centimeters per decimeter up to several meters. The security element transfer material has a composite of the security element layer, i.e. the actual security element material, and a temporary support, i.e. the material on which the security element is "stored". The temporary support is based on a support layer composite consisting of a first and a second temporary support substrate which are bonded together in a non-releasable manner by means of an adhesive layer. The layer composite of the security element is connected directly to the temporary support or via a separating layer. The release layer is of conventional type and facilitates the peeling of the security element from the temporary support when transferred onto the value item. The temporary support is located on the side of the composite security element layer which faces the viewer after transfer of the security element. The term "temporary" support substrate means that the support substrate is not an integral part of the security element, as opposed to a "permanent" support substrate. The construction of the temporary support as a support layer composite avoids the stability of the temporary support being adversely affected by tearing open the temporary support when cutting the contour of the security element. Since the plastic film has a low resistance to further tearing, i.e. the film continues to tear easily and may tear completely even if it is cut only a small amount, a correspondingly thicker construction of the single temporary support film does not easily achieve comparable results. Furthermore, in a support layer composite consisting of a first and a second temporary support substrate bonded in a non-releasable manner by means of an adhesive layer: even if one of the temporary support substrates is completely severed, the other temporary support substrate (or possibly a plurality of other temporary support substrates) generally remains undamaged and accordingly remains stable. In addition, the adhesive also constitutes an additional "buffer zone" between the temporary support substrates.

The method described in patent document WO 2010/031543 a1 consists in scrapping the patch film (entgittern) before application. For this purpose, the layers to be transferred are punched out with a punch in the shape of a patch, in other words the layers are punched through with a punch. These layers are then peeled off in the areas other than the patches, while remaining on the support film in the patch areas, with the exception of waste. It is thus ensured that after application the patch has a clean edge. However, this method has the disadvantage that the layer structure must have sufficient stability for removing waste material, which can be achieved, for example, by inserting a stabilizing film layer. This is, however, again associated with an increased thickness of the patch being manufactured, which is undesirable in practice.

Disclosure of Invention

The object of the present invention is to provide an improved method for producing a transfer element, for example a transfer pad, compared to the prior art. In particular, on the one hand, a low thickness of the produced patch should be achieved and, on the other hand, reliable transfer of patches with clean edges should be achieved.

The technical problem is solved by the following technical scheme.

Summary of The Invention

1. (first aspect of the invention) a method for producing a security element transfer material having a security element provided on a support substrate and configured as a transfer element, the method comprising

a) Providing a support substrate which is provided in turn with a composite of the security element layer and a mask (Maskenfolie) having at least one recess, wherein the composite of the security element layer has a feature layer which is connected to the support substrate in a separable manner and which exhibits an optically variable effect and a layer of adhesive, which feature layer is oriented toward the viewer after the transfer of the security element onto the value document substrate, wherein the recess along the mask is provided with the composite of the security element layer which is provided with stamping lines and is to be transferred onto the substrate of the value document,

The adhesive layer of the security element layer composite does not necessarily have to be present over the entire security element layer composite, but may, according to a variant, be present only in the region of the security element to be produced, which is designed as a transfer element. In this case, the production can be carried out, for example, in such a way that:

-providing a support substrate;

providing the support substrate with a layer composite of the security element and a mask having at least one recess, wherein the security element layer composite has a feature layer which is detachably connected to the support substrate and exhibits an optically variable effect and which, after transfer of the security element onto the value document substrate, faces the viewer, wherein the recess along the mask forms the security element layer composite provided with embossed lines to be transferred onto the value document substrate;

applying an adhesive layer, in particular by printing, to the security element layer composite at least in the region of the recesses of the mask, wherein parts of the mask adjoining the recesses can optionally also be provided with an adhesive layer;

the mask is peeled off from the support substrate together with the security element layer composite masked by the mask and present outside the recesses of the mask.

2. (preferred embodiment) the method according to the above item 1, wherein,

step a) provides a support substrate, which is provided with a composite of a security element layer and a mask having at least one recess in that order, in that way: firstly, a mask provided with at least one recess is applied to the composite security element layer, and then a stamping line is introduced into the composite security element layer along the recess.

3. (preferred embodiment) the method according to the above item 1, wherein,

step a) provides a support substrate, which is provided with a composite of a security element layer and a mask having at least one recess in that order, in that way: the stamping line is first introduced into the composite security element layer and the mask provided with at least one recess is then applied in precise register on the composite security element layer provided with the stamping line.

4. (preferred embodiment) the method according to the above item 1, wherein,

step a) provides a support substrate, which is provided with a composite of a security element layer and a mask having at least one recess in that order, in that way: firstly, the entire mask is applied to the composite security element layer by means of a further adhesive layer, the further adhesive layer being provided only in regions of the mask outside the recesses to be produced, and then recesses are produced in the entire mask along the further adhesive layer by means of punching and the punched mask material is removed, wherein the punching step is performed simultaneously with the introduction of the punching line into the composite security element layer.

5. (preferred embodiment) the method according to one of the foregoing provisions 1 to 4, wherein,

the feature layer exhibiting optically variable effects is based on a retro-embossed structure.

6. (preferred embodiment) the method according to the item 5, wherein,

the retro-embossed structure is produced as follows: a reflective diffractive structure or (b) a reflective microstructure in the form of an insert comprised of a plurality of reflective inlay elements characterized by parameters of size, profile shape, relief shape, reflectivity, and spatial orientation, and configured in a predetermined pattern in such a way that a plurality of sets of inlay elements having different characterization parameters reflect incident light into different spatial regions, and wherein the inlay elements have side dimensions below a resolution limit of the naked eye.

7. (preferred embodiment) the method according to the above 5 or 6, wherein,

the retroreflective embossing structure has (i) an opaque metal layer as a reflective layer, or (ii) a transparent, highly refractive layer as a reflective layer, or (iii) a thin-film element with a color-shifting effect, in particular a thin-film element with a reflective layer and a translucent layer and a dielectric layer arranged between the reflective layer and the translucent layer, as a reflective layer, or (iv) a layer composed of a liquid crystal material, in particular a cholesteric liquid crystal material, as a reflective layer, or (v) a printed layer based on effect pigment components as a reflective layer, the printed layer having an effect determined by the viewing angle or having a different color when viewed in reflected light than when viewed in transmitted light, or (vi) the following multilayer structure as a reflective layer: two translucent layers and a dielectric layer arranged between the two translucent layers, wherein the multilayer structure has different colors when viewed in reflected light on the one hand and when viewed in transmitted light on the other hand.

8. (second aspect of the present invention) a security element transfer material obtainable by the method according to one of the foregoing provisions 1 to 7, the security element transfer material having a security element configured as a transfer element provided on a support substrate.

Detailed Description

In the context of the present invention, viewing under reflected light means that the value document is illuminated from one side and viewed from the same side. Observation under reflected light, for example, thus takes place when the front side of the document of value is illuminated and also observed.

In the context of the present invention, viewing in transmitted light means that the value document is illuminated from one side and viewed from the other side, in particular the opposite side. Thus, when the back side of the value document is illuminated and the front side of the value document is viewed, viewing in transmitted light, for example, then takes place. Light is thus transmitted through the value document.

In the context of the present invention, a value document is, for example, a banknote or an identity document, or also a security, certificate, stamp, check, admission ticket, air ticket, certificate, Visa sticker or the like, as well as a label, stamp, packaging or other element. In the following, the simplified name "value document" therefore always includes documents of the type mentioned. The term value document also includes security paper used for the manufacture of banknotes. The term banknote especially includes paper banknotes, polymer banknotes or film composite banknotes.

The transfer element, i.e. the security element to be transferred, can be in particular a transfer patch or a transfer sticker, or a transfer strip or a transfer line. The present invention is described in the following detailed description according to an example of a transfer patch, but should not be construed as being limited to the patch.

Instead of the term "feature layer", the term "functional layer" is also used herein. The functional layer may be a single (functional) layer or a plurality of (functional) layers.

Instead of the expression "mask having at least one recess", the terms "mask (lochmmask)" or "apertured film" are also used herein.

In the method according to the invention for producing a security element transfer material, a mask is used in the step of removing waste material. The mask is removed from the security element transfer material before application, i.e. final application, of the transfer patch to be produced. The method according to the invention is similar to the method known from prior art WO 2010/031543 a1, wherein the transfer patches are punched out and the intermediate areas are removed in a waste removal material. However, unlike the method known from patent document WO 2010/031543 a1, the transfer patch according to the invention no longer has a stabilizing film per se. The following advantages are thus given in comparison with the transfer patch material known from patent document WO 2010/031543 a 1:

smaller layer thickness before application or final application of the transfer patch. Therefore, the longer winding length of the anti-counterfeiting element transfer printing material wound on the reel can be realized;

the layer thickness after application or final application of the transfer patch is smaller. A smaller layer thickness of the value document substrate provided with the sticker, in particular of the security paper or the banknote, is advantageous for processing in printing banknotes, for example with regard to an improvement in the flatness of the paper provided with the sticker and with regard to a smaller stacking height of the banknotes provided with the sticker;

higher security against forgery, since it is difficult to peel the sticker from the banknote provided with the sticker without destruction.

According to the present invention, the transfer material can be realized according to the following preferred embodiments:

1. providing a transfer printing film structure:

the starting point is a conventional transfer film structure, as it is also used, for example, for applying transfer ribbons. Such a structure is based on a support film, one or more functional layers present on the support film, and a heat-seal lacquer layer. The functional layer provides an optically variable security feature, i.e. for example an embossed hologram, a micro-mirror element, a sub-wavelength structure, etc. Optically variable security features are usually provided by embossing lacquers, for example UV embossing lacquers, with microstructures embossed therein and at least regionally present metal coatings. Usually, other layers, such as protective lacquers or primers, are also present, to which heat-sealing lacquers are finally attached. The heat-seal lacquer layer may in fact also consist of a plurality of layers of different lacquers. The functional layer has only a weak adhesion to the support film, which can be achieved, for example, by a poor adhesion of the embossing lacquer to the support film or by the incorporation of special separating layers.

2. Applying a mask:

according to the invention, a mask is applied on the transfer film structure described above. The mask may in particular be given by an apertured film from which the desired shape of the patch is punched out. Such apertured films are advantageously laminated or bonded to a transfer film structure. This can be achieved with a laminating glue adhesive or simply by using the adhesion of the heat-sealing lacquer which is present anyway. The side facing the heat-seal lacquer may be provided with a primer before, which enables a better adhesion of the mask to the functional layer. The mask and the functional layer can also be bonded regionally. In principle, the mask can also be bonded to the functional layer only when applied, by melting the heat-seal lacquer. In practice, however, it is advantageous to avoid slipping of the mask by at least regionally gluing.

3. Stamping:

in the stamping step, a stamping line is inserted by means of a stamping tool or by means of a cutting tool in order to stamp out the shape of the patch to be produced in such a way that the contour of the patch is stamped out in the transfer compound. The stamped shape is advantageously slightly smaller than the opening in the mask.

4. Removing the mask:

the mask is then removed from the support film in a step of removing the waste material together with the heat-seal lacquer layer covered by the mask and the functional layer. The patch thus remains on the support film and a transfer patch film after waste removal is obtained.

In application or end use, the patch is heated as usual, wherein the heat-seal lacquer melts and adheres to the substrate (of the value document). The substrate (of the value document) may be, for example, a paper substrate or a polymer substrate or a paper/polymer-composite substrate. The heating can be effected here regionally (i.e. in an area slightly larger than the patch itself) or over the entire surface. The support film is then detached from the substrate (of the document of value), so that the functional layer remains on the substrate (of the document of value) in the region of the patch, since the heat-seal lacquer adheres more strongly to paper than between the support film and the functional layer.

According to other preferred embodiments, the transfer material can be realized as follows:

1. providing a transfer printing film structure:

the starting point is again a conventional transfer film structure, as it is also used for applying transfer ribbons, for example. Such a structure is based on a support film, one or more functional layers present on the support film, and a heat-seal lacquer layer. The functional layer provides an optically variable security feature, i.e. for example an embossed hologram, a micro-mirror element, a sub-wavelength structure, etc. Optically variable security features are usually provided by embossing lacquers, for example UV embossing lacquers, with microstructures embossed therein and at least regionally present metal coatings. Usually, other layers, such as protective lacquers or primers, are also present, to which heat-sealing lacquers are finally attached. The heat-seal lacquer layer may in fact also consist of a plurality of layers of different lacquers. The functional layer has only a weak adhesion to the support film, which can be achieved, for example, by a poor adhesion of the embossing lacquer to the support film or by the incorporation of special separating layers.

2. Application of non-apertured film:

on the above-described transfer film structure, an unopened film is first applied, in particular by means of a regionally present adhesive layer ("laminating adhesive").

3. Stamping:

in the stamping step, a stamping line is inserted by means of a stamping tool or by means of a cutting tool in order to stamp out the shape of the patch to be produced in such a way that the contour of the patch is stamped out in the transfer compound. At the same time, holes are produced in the first unperforated film and the stabilizing film is removed in the region of the holes, for example by suction or blowing.

4. Removing the mask:

the mask is then removed from the support film in a step of removing the waste material together with the heat-seal lacquer layer covered by the mask and the functional layer. The patch thus remains on the support film and a waste-removed transfer patch film is obtained.

Due to the positioning tolerances of the adhesive and the punched cut, it is advantageous to have the adhesive end at a sufficient distance from the patch in step 2 above. The patch shape is then punched out and the film in the region of the opening is removed by sharp edges, for example by means of compressed air or by means of drawing.

A further advantage of the method according to the invention is that the patch does not have to be torn off from the functional layer composite (i.e. a break must be achieved within the functional layer) during the step of application to the substrate (of the value document), but the functional layer has been cleanly severed by punching on the patch edges. This results in an extremely clean patch edge.

Other preferred embodiments are:

functional layer:

for example, micromirrors, holographic structures, subwavelength structures or (for example embedded) microlenses can be embedded in the functional layer. The microlenses can be present in particular in combination with microimages which are formed on separate planes and in this way produce optically variable security features in the form of so-called moir e magnifiers, mode mappers, tipping images or the like. Security features based on microlenses combined with microimages are known, for example, from patent document WO2006/087138a 1.

Micromirrors, holographic structures, etc. are usually coated with an at least regionally present metal coating of a metal, such as Al or Ag, a highly refractive coating, such as ZnS or TiO₂Or a three-layer system reflector/dielectric/absorber composition with color-shifting effect (e.g., Al/SiO)₂a/Cr structure).

Heat-sealing paint:

it is essential for the heat-sealing lacquer to ensure the desired adhesion at the end of application by pressure or, if necessary, by increasing the temperature. The heat seal can be melted and/or activated by thermal energy. It can also be provided that the heat-sealing lacquer is then also subjected to a post-treatment (post-crosslinking), for example by means of UV radiation.

Film thickness:

the mask is preferably as thin as possible. A film having a thickness in the range of 4.5 μm to 19 μm may be advantageously used. Polyethylene terephthalate (PET) film is preferably used as the film.

Support substrate or support film:

a thicker film, for example a 19 μm thick PET film, is preferably used as the support film. In those embodiments in which the functional layer is punched in by stamping, it is also usually slightly punched into the support film. It must be ensured here that the support film does not tear after the application of the patch to the substrate (of the value document). According to an advantageous embodiment, instead of a single support film as a support film, a layer composite consisting of two films is used, as is known from patent document WO 2010/031543 a1 (for example a 12 μm thick film and a 19 μm thick film bonded to one another): only one of the two films is subsequently blanked in the stamping, and the second film remains undamaged. A single stamped film tears more easily than a layer composite because a "incipient crack" of one film requires more force than continued tearing.

Application of a transfer patch on a substrate (of a value document):

for better transfer, it may be advantageous for the support film to be torn off from the remaining layer composite by means of sharp edges (or wedges).

Other advantageous parameters:

the functional layer preferably has an embossing lacquer, which generally has a total thickness in the range from 2 μm to 7 μm. The conventional imprint depth may be in the range of, for example, 100nm to 3.5 μm depending on the structure type;

the total thickness of the patch without support film is preferably below 50 μm, more preferably below 30 μm and especially preferably below 20 μm;

conventional patch sizes are for example 5mm to 35mm wide and for example 5mm to 70mm high;

the patch shape can be chosen arbitrarily. Oval shapes are generally easier to apply than rectangular shapes, for example. Sometimes a jagged edge may be advantageous. The stamping solution of the functional layer (see above) makes it possible in particular to achieve the application of patches having a relatively complex contour shape which is difficult to apply under normal conditions.

Other basic remarks:

the embossing structures that can be used according to the invention are in particular embossed in an embossing lacquer. In the context of the present application, the term "optically variable effect" includes, in addition to holograms, hologram-like diffractive structures, i.e. structures which, for example, do not produce a defined image but rather a blurred, colored impression. Likewise, the term "optically variable effect" also includes diffraction patterns, structures with color-shifting effects, motion picture films (Kinoforme), structures with micro-lens effects, structures with isotropic or anisotropic scattering effects or with other interference effects, sub-wavelength structures, moth-eye structures, micro-lens structures and microstructures for moire magnifiers or mode mappers, micro-mirror structures and micro-prism structures.

Preferred reflective embossing structures (otherwise known as reflective embossing structures) have, for example, an interference-capable multilayer structure having:

a reflective layer (in particular of metal);

a translucent (mirror) layer (in particular selected from Al, Ag, Ni, Cr, Cu, Au and alloys of one or more of the foregoing elements); and

a dielectric layer arranged between the reflective layer and the translucent (mirror) layer,

wherein the color of the multilayer structure changes with the viewing angle.

It is possible, for example, to produce, by means of recesses in the reflective layer and/or the translucent layer, a first appearance of the interference-capable multilayer structure which is visible when the front side is viewed in reflected light and a second appearance of the interference-capable multilayer structure which is visible when the front side is viewed in transmitted light. Such film security elements with different reflected/transmitted light appearances are known from patent document WO 2009/149831 a 2. The translucent layer may have a plurality of grid-like arranged hollows giving symbols, images or patterns as a whole. The pattern produced in this way is visible in reflected light and disappears in transmitted light. Alternatively and/or additionally, the different reflected/transmitted light appearances of the multilayer structure can be achieved by combining structures with relief structures, in particular with diffractive relief structures, micro-optical relief structures or sub- λ structures.

Other preferred reflective embossing structures have a multilayer structure, for example having two translucent layers and a dielectric layer arranged between the two translucent layers, wherein the multilayer structure has different hues when viewed in reflected light on the one hand and when viewed in transmitted light on the other hand, in particular a gold hue when viewed in reflected light and a blue hue when viewed in transmitted light. The two different hues are in particular complementary colors. Such a multilayer structure is based in particular on two semi-transparent mirror layers and a dielectric layer arranged between the two semi-transparent mirror layers. Such a multilayer structure that shows a gold color when viewed in reflected light and a blue color when viewed in transmitted light is known, for example, from patent document WO2011/082761 a 1. Metals from the group of Al, Ag, Ni, Cr, Cu, Au and alloys of one or more of the above elements are particularly suitable as the translucent mirror layer, Al or Ag being preferred as the translucent mirror layer and Al being particularly preferred. A suitable multilayer structure having two translucent mirror layers and a dielectric layer arranged between the two translucent mirror layers preferably has the following specific features:

the two semitransparent mirror layers are preferably selected from Al or Ag; dielectric layer, especially SiO₂A layer;

in the case of both translucent mirror layers being based on Al, the respective preferred layer thickness is in the range from 5nm to 20nm, particularly preferably in the range from 10nm to 14 nm; dielectric SiO₂The layer has a layer thickness preferably in the range from 50nm to 450nm, further preferably in the range from 80nm to 260nm, wherein the ranges from 80nm to 100nm and from 220nm to 240nm are particularly preferably used in particular for providing a gold/blue discoloration;

in the case of both semi-transparent mirror layers based on Ag, the respective preferred layer thickness is in the range from 15nm to 25 nm; dielectric SiO₂The layer has a layer thickness preferably in the range from 50nm to 450nm, further preferably in the range from 80nm to 260nm, wherein the ranges from 80nm to 100nm and 220nm to 240nm are particularly preferably used in particular for providing a gold/blue discoloration.

The multilayer layer structure described not only achieves the production of a translucent functional layer which displays a gold color when viewed in reflected light and a blue color when viewed in transmitted light, but also produces other color changes, for example, depending on the choice of the layer thickness, in particular of the dielectric layer

-magenta in reflected light and cyan in transmitted light;

-turquoise in reflected light and orange-yellow in transmitted light;

-gold in reflected light and blue-violet in transmitted light;

silver in reflected light and violet in transmitted light.

Other preferred reflective embossed structures have, for example, a liquid crystal layer which displays a different colour when viewed in reflected light than when viewed in transmitted light. Alternatively and/or additionally, different reflected/transmitted light appearances can be achieved in that the liquid crystal layer is combined with a relief structure, in particular with a diffractive relief structure, a micro-optical relief structure or a sub- λ structure.

Other preferred reflective embossed structures have, for example, a printed layer with effect pigment components which, when viewed in reflected light, exhibits a different color than when viewed in transmitted light, in particular a gold/blue color change, a gold/violet color change, a green gold/magenta color change, a violet/green color change or a silver/opaque color change. Such process colors are described, for example, in patent document WO 2011/064162 a 2. Alternatively and/or additionally, different reflected/transmitted light appearances can be achieved by combining the printed layer with a relief structure, in particular with a diffractive relief structure, a micro-optical relief structure or a sub- λ structure.

The relief structure for structuring the diffractive structure is in particular a holographic structure. The dimensions of the structural elements of the diffractive structure are preferably in the size range of the light wavelength, more preferably in the range of more than 100nm and less than 1 μm, with a range of more than 300nm and less than 1 μm being particularly preferred.

The relief structure that constitutes the micromirror device is also referred to herein as a micro-optical relief structure. The production of such micro-optical relief structures is known from the prior art (see for example patent document WO 2014/060089 a 2). The size of the structural elements of the micromirror device is preferably in the range of more than 1 μm and less than 40 μm, wherein the range of more than 1 μm and less than 30 μm is particularly preferred. The dimensions of the structural elements of the micromirror device have, for example, a height of up to 15 μm and a lateral extension of up to 30 μm. Here, the height and lateral extension of the structural unit of the micromirror device are preferably greater than 1 μm.

Other preferred micro-optical relief structures are known, for example, from patent document WO 2007/079857 a 1. The reflective microstructure is in the form of an insert made of a plurality of reflective inserts which are characterized by parameters such as size, contour shape, relief shape, reflectivity and spatial orientation, and which form a predetermined pattern in such a way that a plurality of groups of inserts with different characteristic parameters reflect incident light into different spatial regions, and the inserts have lateral dimensions below the resolution limit of the naked eye.

Drawings

Further embodiments and advantages of the invention are explained below with reference to the schematic, highly simplified drawing, in which a display to scale and proportion has been omitted in order to increase the clarity of the description.

In the drawings:

fig. 1 to 4 illustrate manufacturing of a transfer material according to the present invention according to a first embodiment; and

fig. 5 to 9 illustrate manufacturing of a transfer material according to the present invention according to a second embodiment.

Fig. 1 to 4 illustrate manufacturing of a transfer material according to the present invention according to a first embodiment.

Detailed Description

According to fig. 1, a transfer film structure is first provided. The transfer film structure is based on a support film 1, one or more functional layers 2 present on the support film 1, and a heat-seal lacquer layer 3. The functional layer 2 provides optically variable security features such as embossed holograms, micro-mirror elements, sub-wavelength structures, etc. Optically variable security features are usually produced by embossing lacquers, for example UV embossing lacquers, together with the microstructures embossed therein and the at least regionally present metal coating. The functional layer 2 has only a weak adhesion to the support film 1, which can be achieved, for example, by a poor adhesion of the embossing lacquer to the support film 1 or by the incorporation of special separating layers.

According to fig. 2, a mask 4 is applied on the transfer film structure shown in fig. 1. The mask 4 may in particular be provided by an apertured film from which the desired shape of the patch is punched. Such an apertured film 4 is advantageously laminated to a transfer film structure. This can be achieved with an additional laminating glue adhesive (not shown in fig. 2) or simply by using the adhesion of the heat-sealing lacquer 3 that is present anyway. The side facing the heat-seal lacquer may advantageously be provided with a primer before, which enables a better adhesion of the mask 4 to the functional layer 2. The mask 4 and the functional layer 2 can also be bonded regionally.

Then, a patch shape is punched out according to fig. 3 (dotted line 5 indicates a punching line). Due to positioning tolerances, it is advantageous that the punch line 5 is at a slight distance from the edge of the mask 4.

As shown in fig. 4, the mask 4 is then removed from the support film 1 in a step other than the removal of the waste material, together with the heat-seal lacquer layer 3 present in the region of the mask 4 (i.e. outside the openings) and the functional layer 2. Therefore, the heat seal paint layer 3 and the functional layer 2 remain in the patch region on the support film 1 because the adhesion of the heat seal paint layer 3 to the mask 4 is stronger than the adhesion between the support film 1 and the functional layer 2.

The transfer patch obtained in fig. 4 can then be applied or applied to a document of value substrate, for example security paper for the production of bank notes. In such application, the patch is heated as usual, wherein the heat-seal lacquer 3 melts and adheres to the paper substrate. The heating can be effected here regionally (i.e. in an area slightly larger than the patch itself) or over the entire surface. The support film 1 is then separated from the remaining layers of the patch applied to the paper substrate. The functional layer 2 therefore remains on the paper substrate in the region of the mounting, since the adhesion of the heat-seal lacquer 3 to the paper is stronger than the adhesion between the support film and the functional layer 2 of 1.

Fig. 5 to 8 illustrate manufacturing of a transfer material according to the present invention according to a second embodiment.

A transfer film structure is first provided according to fig. 5. The transfer film structure is based on a support film 7, one or more functional layers 8 present on the support film 7, and a heat-seal lacquer layer 9. The functional layer 8 provides optically variable security features such as embossed holograms, micro-mirror elements, sub-wavelength structures, etc. Optically variable security features are usually produced by embossing lacquers, for example UV embossing lacquers, together with the microstructures embossed therein and the at least regionally present metal coating. The functional layer 8 has only a weak adhesion to the support film 7, which can be achieved, for example, by a poor adhesion of the embossing lacquer to the support film 7 or by the incorporation of special separating layers.

According to fig. 6, the transfer composite shown in fig. 5 is provided with a laminating adhesive 10 in the region outside the subsequent patches (but without the mandatory need for laminating adhesive 10; alternatively the already existing heat-sealing lacquer 9 can be melted or activated regionally) and subsequently bonded to the film 11. Due to the positioning tolerances of the adhesive and the punched cut, it is advantageous to have the adhesive end at a sufficient distance from the patch.

According to fig. 7, a tab shape is then punched out (solid line 12 represents a punching tool) and the film 11 is removed in the region of the opening by a sharp edge, for example by means of compressed air or by means of drawing.

Fig. 8 shows the layer structure already obtained, provided with a punching line 13 (shown in the form of a dashed line in the drawing).

As shown in fig. 9, the mask 11 is then removed from the support film 7 in a step of removing waste material together with the laminating adhesive bond 10, the heat-seal lacquer layer 9 and the functional layer 8 present in the region of the mask 11. Therefore, the heat seal paint layer 9 and the functional layer 8 remain in the patch region on the support film 7 because the adhesion capability of the heat seal paint layer 9 to the mask 11 is stronger than the adhesion capability between the support film 7 and the functional layer 8.

The transfer patch obtained in fig. 9 can then be applied to a document of value substrate, for example security paper for the production of bank notes. In such application, the patch is heated as usual, wherein the heat-seal lacquer 9 melts and adheres to the paper substrate. The heating can be effected here regionally (i.e. in an area slightly larger than the patch itself) or over the entire surface. The support film 7 is then separated from the remaining layers of the patch applied to the paper substrate. The functional layer 8 therefore remains on the paper substrate in the patch region, since the heat seal lacquer 9 adheres more strongly to the paper than between the support film 7 and the functional layer 8.

In a variant of the above-described embodiment, this is done:

the adhesive layer of the security element layer composite does not necessarily have to be present over the entire security element layer composite, but may, according to variants, be present only in the region of the security element to be produced, which is designed as a transfer element. In this case, the production can be carried out, for example, in such a way that:

-providing a support substrate;

providing the support substrate with a composite security element layer and a mask having at least one recess, wherein the composite security element layer has a feature layer which is detachably connected to the support substrate and exhibits an optically variable effect and which, after transfer of the security element onto the value document substrate, faces the viewer, wherein the recess along the mask forms the composite security element layer provided with embossed lines to be transferred onto the value document substrate;

the mask is peeled off from the carrier substrate together with the security element layer composite masked by the mask and present outside the recesses of the mask.

Claims

1. A method for manufacturing a security element transfer material having a security element configured as a transfer element provided on a support substrate, the method comprising

a) Providing a support substrate which is provided in succession with a composite of the security element layer and a mask having at least one recess, wherein the composite of the security element layer has a feature layer which exhibits an optically variable effect and which is connected to the support substrate in a separable manner and an adhesive layer, which feature layer is oriented toward the viewer after transfer of the security element onto the document of value substrate, wherein the recess along the mask is provided with the composite of the security element layer provided with embossed lines to be transferred onto the substrate of the document of value,

2. The method according to claim 1, wherein step a) provides a support substrate provided with a composite of the security element layer and a mask having at least one recess in that order, by: firstly, a mask provided with at least one recess is applied to the composite security element layer, and then a stamping line is introduced into the composite security element layer along the recess.

3. The method according to claim 1, wherein step a) provides a support substrate provided with a composite of the security element layer and a mask having at least one recess in that order, by: the stamping line is first introduced into the composite security element layer and the mask provided with at least one recess is then applied in precise register on the composite security element layer provided with the stamping line.

4. The method according to claim 1, wherein step a) provides a support substrate provided with a composite of the security element layer and a mask having at least one recess in that order, by: firstly, the entire mask is applied to the composite security element layer by means of a further adhesive layer, the further adhesive layer being provided only in regions of the mask outside the recesses to be produced, and then recesses are produced in the entire mask along the further adhesive layer by means of punching and the punched mask material is removed, wherein the punching step is performed simultaneously with the introduction of the punching line into the composite security element layer.

5. Method according to one of the preceding claims 1 to 4, wherein the feature layer exhibiting an optically variable effect is based on a retro-embossed structure.

6. The method of claim 5, wherein the retro-reflective embossed structure is produced by: a reflective diffractive structure or (b) a reflective microstructure in the form of an insert comprised of a plurality of reflective inlay elements characterized by parameters of size, profile shape, relief shape, reflectivity, and spatial orientation, and configured in a predetermined pattern in such a way that a plurality of sets of inlay elements having different characterization parameters reflect incident light into different spatial regions, and wherein the inlay elements have side dimensions below a resolution limit of the naked eye.

7. The method according to claim 5, wherein the retroreflective embossing structure (i) has an opaque metal layer as a reflective layer, or (ii) has a transparent, highly refractive layer as a reflective layer, or (iii) has a thin-layer element with a color-shifting effect as a reflective layer, or (iv) has a layer composed of a liquid crystal material as a reflective layer, or (v) has a printed layer based on an effect pigment component as a reflective layer, the printed layer having an effect depending on the angle of observation or having a different color when viewed in reflected light than when viewed in transmitted light, or (vi) has a multilayer structure of: two translucent layers and a dielectric layer arranged between the two translucent layers, wherein the multilayer structure has different colors when viewed in reflected light on the one hand and when viewed in transmitted light on the other hand.

8. A method as claimed in claim 7, wherein the thin-film element is provided with a light-reflecting layer and a translucent layer and a dielectric layer arranged between the light-reflecting layer and the translucent layer.

9. A method according to claim 7, wherein the liquid crystal material is a cholesteric liquid crystal material.

10. A security element transfer material obtainable by the method according to one of the preceding claims 1 to 9, having a security element provided on a support substrate, configured as a transfer element.