DE10326645A1 - Value document with a security element and method for producing the value document - Google Patents

Abstract

The invention relates to a value document (1) provided with at least one safety element (6) comprising a marking layer (8) which is arranged in a marking area (4) and is applied to a substrate (2) containing electroluminescent pigments (10). The aim of said invention is to produce a value document complying with particularly high safety standards even when automatic evaluation methods are used. For this purpose, each electroluminescent pigment (19) comprises a pigment core (20) made of an electroluminescent material enclosed by an active optical layer (24).

Description

The The invention relates to a value document with at least one Security element in a marker area one on one Carrier body applied, comprising electroluminescent pigments comprising marking layer. It further relates to a use in such a value document suitable electroluminescent pigment, a process for the preparation of such a value document and a method of manufacturing such electroluminescent pigments.

To the Protection against counterfeiting or imitations become value or security documents, such as Banknotes, identity cards or chip cards, with so-called security features or Security elements provided, for example, in paper-based value documents among other things an imitation by making color copies safely exclude should. The security elements can in particular as optically variable elements, such as holograms or interference layer elements, be designed while viewing depending on the viewing angle different color impressions conveyed during the copying process but not on the copy become. Such security elements are not or only Hard machine readable or evaluable, allowing an automated Security check of the respective value documents only conditionally and with high technical complexity is possible.

From the DE 197 08 543 However, a value document is known, which is particularly suitable for automated evaluation of its security elements. For this purpose, the value document as a security element in a marking area has a marking layer applied to a carrier body, for example the banknote paper, which is mixed with electroluminescent pigments. When checking or authenticating this security element, the marking layer containing the electroluminescent pigments is exposed to an alternating electric field contactlessly via a suitably designed test device. The alternating electric field in turn excites the electroluminescent pigments contained in the marking layer to emit electromagnetic radiation, which can be registered directly or indirectly in a suitable receiver. In particular, in combination with the corresponding test apparatus, the valuable document thus equipped is therefore particularly suitable for an automated and thus particularly reliable evaluation with only limited technical effort.

Of the Invention is based on the object, a value document of the above specify the type mentioned, which has a particularly high safety standard having. In addition, a for use in such a document of value suitable electroluminescent pigment, a process for the preparation of such a value document and a method of manufacturing such pigments are given.

Regarding the Wertdocuments this object is achieved in that the electroluminescent pigments in each case one of electroluminescent Comprise material formed pigment core, that of an optical surrounded by active coating.

The Invention is based on the consideration, that the value document for a particularly high safety standard with electroluminescent Equipped with pigments should be.

at the evaluation of emitted by electroluminescent pigments Radiation is common a vote of the receiver part of the tester used on the Emission spectrum of the electroluminescent pigments provided. At the targeted use of electroluminescent pigments with each other distinguishable spectra it is thus possible to use the characteristic Signature of the security feature to make particularly concise and thus the quality to improve the authentication. In terms of authentication be provided to determine a degree of agreement a received in the exam Compare spectrum with an expected spectrum. It is one the higher Accuracy in the evaluation and thus a higher backup function the respective security feature can be reached for the document of value, the more specifically that emitted by the electroluminescent pigments Spectrum can be adjusted, with a rather sharply defined Spectrum a higher one selectivity and proof accuracy allowed as a broadband spectrum. In contrast, are the emission spectra of known electroluminescent pigments However, comparatively broadband and more suitable on the setting Doping only a limited number clearly from each other distinguishable spectra expandable.

The value document should be equipped with a particularly high safety standard with electroluminescent pigments, which are designed especially for the emission of a characteristic, selectively identifiable spectrum. Such a selectively identifiable In particular, the spectrum should have a comparatively narrow bandwidth, so that a wavelength-sensitive evaluation enables a particularly reliable assignment of emitted signals to individual pigment groups or types. Namely, authenticity detection can be made dependent in particular on the presence of specific pigment groups or types. For a comparatively small bandwidth of the emitted spectrum, a coating of the electroluminescent pigment cores is provided such that, depending on the wavelength, partial "filtering" of the spectrum actually emitted by the electroluminescent material takes place. The coating is designed for this purpose as an optically active coating. In the case of a single-layer coating, for example, a wavelength-selective transmission is effected by the use of a non-linearly absorbing coating. In such a non-linearly absorbing coating, suitable energetic levels can be generated in the crystal lattice of the coating, for example by selective doping of the coating, eg with metal ions (Fe ³⁺ , Co ³⁺ , Ni ³⁺ ), which can be excited with sufficient light intensity and thus the nonlinearity cause. The coating can be designed such that parts of the emission spectrum are defined suppressed.

Especially Advantageous optical properties are expediently achievable by a targeted use of interference effects by which the emitted Spectrum in single wavelengths or Wavelength ranges deliberately suppressed or toned down can be. A use of such interference effects is realized by a coating of the electroluminescent pigment cores, which preferably has at least two layers which are in their Different refractive index.

Basically, the coating of pigments with consequences of thin layers with varying refractive index is known from US Pat EP 1 138 743 A1 or from the EP 0 852 977 A1 , The concepts disclosed therein, however, are directed to the coating of magnetic pigment cores, wherein the coatings should ensure an increased refractive index and thus a high reflectivity and a light color of the pigments. The methods described in these publications for applying the coatings to the pigment cores can also be used in the present concept.

advantageously, is the value document for a Application of the security element with a printing process, preferably by screen printing, intaglio printing, offset printing, Lettersetdruck or a transfer method to the carrier body suitable. Show this the pigments expediently a mean pigment size of about 1 μm to 50 μm, preferably of about 3 microns up to 8 μm, allowing them in particular for use in a security printing process are suitable.

Especially fine-grained Pigments, which are therefore particularly suitable for use in a typographic printing Procedures are available by the respective Pigment core-forming electroluminescent material advantageously has a preferred cubic crystal structure.

The the respective pigment core forming electroluminescent material is expediently from an II-VI compound, advantageously from (co) doped ZnS, ZnSe, SrS, CaS or CdS, wherein in a further advantageous embodiment of the Doping as activator Cu and / or Au and / or Mn and as activator Halide ions or trivalent cations. Alternative or additional advantageous dopants can Ag, Fe, Co, Ni and / or rare earths, in particular Tm, Tb, Dy, Gd, Yb, Sm, Eu, include.

The coating surrounding the pigment core in the manner of a microencapsulation advantageously has at least one layer of inorganic material, preferably of oxides, nitrides, oxysulphides, sulfides of metals or semimetals, which are optionally (co-) doped with metals or semimetals. In this case, SiO ₂ , SiO ₂ , TiO ₂ , NiO, Ni ₂ O ₃ , CoO, Co ₂ O ₃ , Y ₂ O ₃ or ZrO _{2 is} provided in a further advantageous embodiment as an inorganic material. In an alternative or additional advantageous embodiment, the inorganic material comprises a metal, preferably Fe and / or Co and / or Ni and / or Cr and / or Mo and / or W and / or V and / or Nb.

Depending on the electrical conductivity of the Coating could the encapsulation of the pigment cores by the coating in the Kind of a Farraday cage cause that the pigment core completely externally imprinted electrical fields is shielded. This would be the excitation of the pigment core by the electric field, in particular the alternating electric field, make it difficult or completely impossible to authenticate the value document. Therefore covered in a further advantageous embodiment, the coating the surface of the respective pigment core only partially.

Advantageously, the coating is designed to profile the emission spectrum of the respective pigment core to a particular extent and to modify it for a particularly characteristic signature. To be an emission in this sense To provide spectrum of the pigment with comparatively low bandwidth, the coating is chosen in a particularly advantageous embodiment with respect to the refractive indices of their layers and / or dimensioned in their coating thickness such that the spectral transmission of the coating at a predetermined wavelength, preferably a wavelength at which natural emission spectrum of the electroluminescent material is particularly pronounced, having a maximum. In this case, the material parameters refractive index and / or layer thickness are deliberately predetermined such that the desired focusing of the emission spectrum of the pigments occurs due to the use of the interference effects in the coating. By appropriate specifications, the coating may, for example, in the manner of a band filter or in the manner of an upper or lower edge filter act, and maxima can be moved or additional maxima can be generated in the emission spectrum.

Regarding the electroluminescent pigment, the stated object is achieved by a pigment core formed from electroluminescent material from a coating with nonlinear transmission and / or Absorption behavior is surrounded. Particularly advantageous developments of electroluminescent pigment and the coating the for the value document provided embodiments.

One such electroluminescent pigment may also preferably in a luminescent device as a light-emitting component of LEDs, displays or backlights are used. By the coating, the electroluminescent pigment is expediently before environmental influences, especially against water vapor migration, protected.

to solution which is directed to the process for producing the value document Task two variants are proposed, either individually or can be used in combination with each other. In A first variant is used to prepare the marking layer a resin is applied to the carrier body and softened, wherein in the softened state of the resin pigment cores such be applied that the pigment cores at least partially in sink the resin so that only part of the surface of the Pigment cores out of the resin, followed by means of Physical Vapor Deposition (PVD) and / or Chemical Vapor Deposition (CVD) the coating is applied. This will ensure that in the coating of the pigment cores only a part of their surface is provided with the coating, so that a shield of the Opposite pigment cores the stimulating electric field as a result of a continuously surrounding surface coating is safely excluded.

there Advantageously, an acrylate-based resin is used, wherein in alternative or additional Advantageously, the pigment cores are sprinkled over a sieve on the resin become. The use of the sieve makes it possible to special simple way a high homogeneity and equal distribution of Pigment cores over the surface.

In In a second variant, the marking layer is formed by means of a Printing method, preferably by screen printing, intaglio printing, Offset printing, Lettersetdruck or a transfer printing method on applied to the carrier body. Such a method is particularly favorable Dimensions for the production greater numbers with comparatively simple means.

there is advantageously when applying the marking layer a printing ink used in addition to the electroluminescent Pigments a solvent and / or a binder are included. Conveniently, the ink in terms of their composition and their constituents for one particularly favorable usability designed in a printing process ,.

To contains the ink advantageously a pigment content of less than 30%, advantageously less than 25%.

Regarding the Process for the preparation of for the use in the value document particularly suitable electroluminescent Pigments, the stated object is achieved by using pigment cores means Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD) and / or plasma process and / or a sol-gel process and / or Polymerization and / or electrochemical / galvanic coating and / or fluidized bed process and / or self-assembly (self-assembling) and / or hybridization provided with the coating become. In order to avoid shielding the pigment core from the impressed electrical Field to ensure that the coating is the pigment core only partially encloses the pigment cores advantageously after their coating one Grinding subjected such that a part of the coating respectively is broken away, so that then at most a part of the surface of the respective pigment core is covered with the coating.

The grinding process is expediently carried out in a ball mill, wherein a grinding aid is supplied before the beginning or during the grinding. As a grinding aid is special suitable acetylcholine and / or oil and / or an aqueous suspension.

For one Particularly low production costs, the milling process advantageously be integrated into the color production. This is the grinding process advantageously in a color production in a three-roll dyeing chair performed, where the coated pigments are part of the paint. As another Components of the color are advantageously color binders and colored pigments provided. To the desired comparatively fine-grained structure To ensure the pigments, the distance of the surfaces of the Rolling the Dreiwalzenfarbstuhls advantageously to a value set at the maximum of the average diameter of the pigments.

Of the Grinding process is in an advantageous embodiment for a maximum two hours, so as to ensure that the coating is not completely from the pigment cores is removed again.

The advantages achieved by the invention are, in particular, that a wavelength-selective transmission takes place through an optically active coating of the pigment cores. This is achieved, for example, in the case of a single-layer coating by means of a non-linearly absorbing coating by targeted doping, for example with metal ions (Fe ³⁺ , Co ³⁺ , Ni ³⁺ ). Furthermore, due to interference effects, a targeted modification of the spectrum emitted by the electroluminescent pigment cores can be made possible by a multi-layer coating of the pigment cores, in which two, three or even more coating layers with completely or partially different refractive indices can be provided. In particular, this spectrum can be made comparatively narrow-band, so that a particularly characteristic signature of the emission spectrum can be achieved. It is thus possible, by a suitable choice of material for the electroluminescent pigment core in combination with the specification of suitably selected coating parameters, ie in particular suitably selected refractive indices and layer thicknesses for the coating layers, from each other on the basis of their emission spectrum distinguishable pigment groups or varieties, so that in terms of their characteristic emission wavelength distinguishable security features are available. As a result of the high level of flexibility with regard to the emission properties in the security features that can be achieved, a particularly high security standard can be achieved in the respective security document. The possibility of targeted use of the properties of the coating of pigments is thus now being developed for a pigment class important for the mechanical verification of value and security documents.

Furthermore is in a very favorable way also a local reinforcement the stimulating electric field achievable when the coating at least in one of the layers a certain electrical conductivity having. The respective coating layer then acts in fact the nature of a local, in the immediate vicinity of the electroluminescent Material "floating" electrode, the one Compression and focusing of contactless externally applied electric field in the immediate vicinity of the electroluminescent Material causes. As a result, even at comparatively low externally imprinted field strength locally exceeded the excitation field of the electroluminescent material be so that with comparatively low externally pronounced field strengths a reliable Excitation of the luminescence allows is. Especially by the particularly advantageous combination of these Effects is thus a particularly succinct, narrow-band spectrum producible as well as in the evaluation the use comparatively Small test field strengths possible.

One embodiment The invention will be explained in more detail with reference to a drawing. Show:

1 a value document in plan view,

2 the marking area of the value document 1 on average,

3 Cuts through a security element of the value document 1 (Schematically)

4 . 5 each an electroluminescent pigment in section,

6 schematically each an emission spectrum of an electroluminescent pigment with uncoated ( 6a ) and coated ( 6b - 6g ) Pigments,

7 Examples of electroluminescent pigments in section, and

8th a section through a part of a security element during its production (schematically).

Same Parts are provided with the same reference numerals in all figures.

The value document 1 according to 1 , which is, for example, a banknote, an off white card, a chip card or any other security document or product secured against counterfeiting or copying, comprises as a basic element a carrier body 2 depending on the purpose of the value document 1 can be constructed of paper, plastic, laminated plastic layers or other suitably chosen material. On the carrier body 2 is in a marker area 4 a security element 6 applied. The security element 6 and the marking area covered by it 4 can be dimensioned and configured according to any criteria tailored to the application, and in particular designed for the optical reproduction of a printed image, for example a numerical value.

The security element 6 serves as a security feature for detecting whether the value document 1 is genuine. For this purpose, verification or authentication methods are used that check certain chemical or physical properties of the security feature and thus detect whether the security feature meets the expected specifications.

The security element 6 is designed especially for automated evaluation of its security function. This includes the security element 6 , as in the embodiment according to 2 is shown in section, in the marking area 4 one on the carrier body 2 applied marking layer 8th , The marking layer 8th is to ensure an automated readability based on electroluminescent pigments 10 built up. It is for authentication or evaluation of the security element 6 the contactless irradiation of electromagnetic radiation in the Markie insurance layer 8th from a suitably selected tester, as for example in the DE 197 08 543 is disclosed provided. The in the marking layer 8th Irradiated electromagnetic radiation dissolves in the pigments 10 Elektrolumineszenzerscheinungen, wherein the generated electromagnetic response radiation can be detected by a suitable sensor and evaluated automatically.

As in 3a shown, the marking layer 8th by a printing process, in particular by screen printing, intaglio printing, offset printing or Lettersetdruck, on the carrier body 2 be upset. In this case, the marking layer comprises 8th on the one hand the electroluminescent pigments 10 and on the other hand, other components of the printing ink, such as color pigments and / or color binders 12 , As an alternative to the printing process, it is also possible to use a different coating technique, such as painting, for example. In the embodiment according to 3b on the other hand, the security element consists of a substrate 14 and a coating 16 , The substrate 14 may be a paper, a plastic or a composite material. As a coating 16 could in this case one of the electroluminescent pigments 10 comprehensive powder or a mixture of in 3a shown used type. The security element 6 with the in 3b shown construction can with the value document 1 be connected for example by gluing or laminating.

In a further embodiment for the production of the security element 6 or the value document 1 can one the electroluminescent pigments 10 comprehensive powder with plastic particles or plastic precursor particles are mixed and processed into a film by calendering, extruding or film casting. The film itself can already be the value document 1 or the security element 6 represent or connected by means of one or more laminating or gluing steps with a carrier.

The security element 6 is designed to comply with very high safety standards. This ensures that the electroluminescent pigments 10 of the security element 6 have a particularly narrow-band emission spectrum in response to the radiated alternating electric field, so that with a suitable vote of the test device, an individualized detection and assignment of a specified group or type of electroluminescent pigments 10 is possible. To ensure this, the electroluminescent pigments include 10 one in each 4 exemplified pigment core 20 that from its surface 22 is limited. The pigment core 20 consists of an electroluminescent material, that is, of a material that emits electromagnetic radiation upon application of an alternating electric field. Typical electroluminescent materials consist of a host lattice, a II-VI compound, for example zinc sulfide (ZnS), zinc selenide (ZnSe), strontium sulfide (SrS), calcium sulfide (CaS) or cadmium sulfide (CdS). Such materials have an activator, this activator being provided as doping in the host lattice. Such dopants may consist of copper (Cu), gold (Au) or manganese (Mn).

Furthermore, electroluminescent materials have coactivators, which are also dopants of the host lattice. These dopants can be used as halide ions (chlorine ions (Cl ^- ), bromine ions (Br ^- ) or iodine ions (I ^- )) or as 3-valent cations (aluminum ions (Al ³⁺ ), gallium ions (Ga ³⁺ ), indium ions (In ³⁺ ), europium ions (Eu ³⁺ ), prometium ions (Pm ³⁺ ), praseodymium ions (Pr ³⁺ )) be educated. For example, a widely used electroluminescent material consists of a zinc sulfide host lattice with a manganese and chlorine dopant (ZnS: Mn, Cl) and preferably has a cubic crystal lattice. Alternatively or additionally, the doping can be silver (Ag), iron (Fe), cobalt (Co), nickel (Ni) and / or selected rare earths such as thulium (Tm), terbium (Tb), dysprosium (Dy), gadolinium (Gd ), Ytterbium (Yb), samarium (Sm), europium (Eu).

The electroluminescent pigment cores 20 when excited by an alternating electric field emitted electromagnetic radiation is in a wavelength range between 200 nm to 3 microns. The mean diameter (the so-called D-Index 50 value) of such pigment cores 20 is in the embodiment at most 30 microns, preferably less than 25 microns, more preferably about 1 micron to 15 microns.

To ensure the desired optical properties, is to form the actual pigments 10 the respective pigment core 20 from an at least single-layer optically active coating 24 surround. In the case of a single-layer coating, for example, a wavelength-selective transmission by means of a non-linearly absorbing coating is effected by targeted doping, for example with metal ions (Fe ³⁺ , Co ³⁺ , Ni ³⁺ ). In the embodiment according to 5 is in order to additionally use interference effects, an optically active coating 24 from three layers 26 . 28 . 30 shown. However, it is also possible to provide another suitably selected number of coating layers, for example two or even more than three.

The this coating 24 forming layers 26 . 28 . 30 are executed in the embodiment of inorganic material. However, they may also be organic polymer-based materials such as PET and / or PMMA. Suitable inorganic materials are metals, in particular iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), molybdenum (Mo), tungsten (W), vanadium (V) or niobium (Nb). Metal oxide layers are preferably composed of silicon dioxide (SiO ₂ ), silicon monoxide (SiO), titanium dioxide (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ) or zirconium dioxide (ZrO ₂ ). The thickness of such a layer 26 . 28 . 30 should be at most 1 μm, but preferably 50 to 200 nm.

The optically active coating 24 is applied to the respective pigment core with the aim of targeted exploitation of interference, the emission spectrum of the electroluminescent material of the pigment core 20 suitable to modify and in particular to make comparatively narrow band.

je nachdem, ob in dem betreffenden Wellenbereich eine Verstärkung oder eine Auslöschung erreicht werden soll, wobei m eine ganze Zahl und λ die Wellenlänge der elektromagnetischen Strahlung ist, die verstärkt oder ausgelöscht werden soll. Die Lagen 26, 28, 30 werden dann als sogenannten

Schichten bezeichnet.That's what the layers are for 26 . 28 . 30 the coating 24 of the embodiment selected such that the refractive index between adjacent layers 26 . 28 . 30 significantly different. In this case it is guaranteed that this is the pigment core 20 forming electroluminescent material emits an electromagnetic radiation when excited by an alternating electric field, which is then the coating 24 Suspends interference effects. The layers 26 . 28 . 30 are formed in view of the layer thickness and their respective refractive index such that the electroluminescent material of the pigment core 20 emitted electromagnetic radiation passes through the layers only in certain predetermined ranges of the wavelength spectrum. The following known law is used:

depending on whether a gain or an extinction is to be achieved in the relevant waveband, where m is an integer and λ is the wavelength of the electromagnetic radiation which is to be amplified or extinguished. The layers 26 . 28 . 30 are then called so-called

Called layers.

By using such a coating 24 for the pigment cores 20 can the emission spectrum of the pigment cores 20 significantly modify, as exemplified by the spectra in the 6a to 6g is explained. While, as in 6a qualitatively in the form of an intensity (I) wavelength (λ) spectrum for an uncoated pigment core 20 As shown, the electroluminescent material has a comparatively broad-band emission spectrum with a maximum at a wavelength λ ₀ , the width of this spectrum can be through the coating 24 reduce significantly. An example of this is in 6b represented by a further intensity (I) wavelength (λ) spectrum. This one for out with a coating 24 provided pigment cores 20 formed electroluminescent pigments 10 characteristic spectrum has a significantly lower bandwidth Δλ compared to in 6a shown spectrum. In the in the 6b and 6c The exemplary embodiments shown are the coating 24 chosen such that both for wavelengths below the wavelength λ ₀ (or λ ₀ and λ ₁ ) and for wavelengths above the wavelength λ ₀ (or λ ₀ and λ ₁ ) a filtering or attenuation of the emitted radiation is made, so that in this case the coating 24 acts in the manner of a band filter and a maximum is achieved ( 6b ) or several maxima, eg two maxima ( 6c ), be achieved. Depending on the desired specification of the spectrum of electroluminescent pigments 10 can the coating 24 but also in the manner of an upper edge filter ( 6d ), which in particular attenuates the emitted radiation having a wavelength of more than the wavelength λ ₀ , or in the manner of a lower edge filter (US Pat. 6e ), which in particular attenuates radiation of a wavelength of less than the wavelength λ ₀ , be designed. Furthermore, an additional maximum ( 6f ) or shift a maximum in the emission spectrum, as in 6g indicated by the double arrow.

To the chosen materials, especially with regard to the metallic components in the coating 24 , the complete shielding of the pigment cores 20 To avoid the impressed alternating electric field due to the Farraday effect is in the embodiments according to 7 the coating 24 such on the respective pigment core 20 applied that to its surface 22 only partially covered. To ensure this, can in the production of the value document 1 a method for which an intermediate in 8th is shown. In this embodiment for the production of the security element 6 , is for the security element 6 a substrate 14 intended. On the substrate 14 becomes a resin 32 applied, the resin 32 softened after application or already before or during application by heat input. Subsequently, pigment cores 20 of an electroluminescent material on the surface of the resin 32 sprinkled. This is preferably done through a sieve, so that a particularly uniform distribution of the pigment cores 20 is guaranteed. The softening of the resin 32 is designed in a strength that the pigment cores 20 not completely in the resin 32 sink, but that almost all cores with part of their surface from the resin 32 protrude. Subsequently, a coating is then carried out, for example by means of PVD or CVD method, so that the pigment cores 20 only partially coated.

Alternatively, however, it can also be provided, the pigments 10 in a first step with a complete coating 24 , as in 5 shown to produce. The coating of the pigment cores 20 with the coating 24 can be done in particular by means of physical vapor deposition (PVD), chemical vapor deposition (CVD) or a sol-gel process. To start from such prepared pigments 10 a partially coated surface 22 the pigments 20 To ensure the coating step, a grinding process is followed. By grinding is of the initially completely coated pigment core 20 a part of the coating broke away. The grinding process is carried out, for example, in a ball mill, wherein the powder is added before or during grinding, a grinding aid. As a grinding aid may be provided acetylcholine ([N (CH ₃ ) ₃ (C ₂ H ₅ O)] ⁺ COO ^- ), oil or an aqueous suspension.

Alternatively, however, the grinding process can also take place in the context of the production of a printing ink, so that the total manufacturing effort required is kept particularly low. These are the electroluminescent pigments 10 attached to a printing ink, with which then the value document 1 for the production of the security element 6 and its marking layer 8th can be printed. The color, which is generally composed of binder and color pigments, in this case additionally contains the electroluminescent pigments 10 with the complete optically active coating 24 , If the color is now in a, as is usual in the color production in general, three-roll inking and adjusted the distance of the roll surface of the rolls of Dreiwalzenfarbstuhls such that the distance is slightly smaller or at most equal to the average diameter of the powder particles, then here Powder particle cores with the complete coating undergo a milling process, so that subsequently a mixture of paint and electroluminescent pigments 10 is present, their pigment cores 20 on its surface 22 only partially coated.

The meal in the ball mill or the grinding process in the three-roll paint chair are preferably 30 minutes to 2 hours. After this period, sufficient homogenization is achieved, with destruction of the pigment core 20 safely avoided by grinding.

1

value document

2

support body

4

marking region

6

security element

8th

marking layer

10

electroluminescent pigments

12

arrow

14

electrodes

16

coating

20

pigment core

22

surface

24

optical active coating

26 28, 30

documents

32

resin

I

intensity

λ, λ ₀ λ ₁

wavelength

Δλ

bandwidth

Claims (26)

Value document ( 1 ) with at least one security element ( 6 ) located in a marking area ( 4 ) one on a carrier body ( 2 ) applied, electroluminescent pigments ( 10 ) comprehensive marking layer ( 8th ), characterized in that the electroluminescent pigments ( 10 ) in each case a pigment core formed from electroluminescent material ( 20 ) derived from an optically active coating ( 24 ) is surrounded. Value document ( 1 ) according to claim 1, wherein the coating ( 24 ) at least two layers ( 26 . 28 . 30 ) having a different refractive index. Value document ( 1 ) according to claim 1 or 2, wherein the pigments ( 10 ) have an average pigment size of from about 1 μm to 50 μm, preferably from about 3 μm to 8 μm. Value document ( 1 ) according to one of claims 1 to 3, in which the respective pigment core ( 20 ) has an electroluminescent material having a cubic crystal structure. Value document ( 1 ) according to one of claims 1 to 4, in which the respective pigment core ( 20 ) forming electroluminescent material from a II-VI compound, preferably from (co) doped ZnS, ZnSe, SrS, CaS or CdS exists. Value document ( 1 ) according to claim 5, wherein the doping as activator comprises Cu and / or Au and / or Mn and as coactivator halide ions or 3-valent cations. Value document ( 1 ) according to one of claims 1 to 6, wherein at least one layer ( 26 . 28 . 30 ) of the coating ( 24 ) of inorganic material, preferably of oxides, nitrides, oxysulfides, sulfides of metals or semi-metals or those which are (co-) doped with metals or semimetals formed. Value document ( 1 ) according to claim 7, wherein as the inorganic material SiO ₂ , SiO, TiO ₂ , NiO, Ni ₂ O ₃ , CoO, Co ₂ O ₃ , Y ₂ O ₃ or ZrO _{2 is} provided. Value document ( 1 ) according to claim 7, wherein the inorganic material comprises a metal, preferably Fe and / or Co and / or Ni and / or Cr and / or Mo and / or W and / or V and / or Nb. Value document ( 1 ) according to one of claims 1 to 9, in which the coating ( 24 ) the surface of the respective pigment core ( 20 ) only partially covered. Value document ( 1 ) according to one of claims 1 to 10, in which the coating ( 24 ) with regard to the refractive indices of individual layers ( 26 . 28 . 30 ) and / or the coating thickness is dimensioned such that the spectral transmission of the coating ( 24 ) has a maximum at a given wavelength. Electroluminescent pigment ( 10 ), in particular for use in a value document ( 1 ) according to one of claims 1 to 11, with a pigment core formed from electroluminescent material ( 20 ) covered by a coating ( 24 ) is surrounded by nonlinear transmission and / or absorption behavior. Method for producing a value document ( 1 ) according to one of claims 1 to 11, in which for the production of the marking layer ( 8th ) a resin ( 32 ) on the carrier body ( 2 ) is applied and softened, wherein in the softened state of the resin ( 32 ) Pigment cores ( 20 ) are applied in such a way that the pigment cores ( 20 ) at least partially into the resin ( 32 ) so that only part of the surface of the pigment cores ( 20 ) from the resin ( 32 ), and then, by means of Physical Vapor Deposition (PVD) and / or Chemical Vapor Deposition (CVD), the coating ( 24 ) is applied. Process according to claim 13, wherein a resin ( 32 ) is used on acrylate basis. Process according to Claim 13 or 14, in which the pigment cores ( 20 ) over a sieve on the resin ( 32 ) are scattered. Method for producing a value document ( 1 ) according to one of claims 1 to 11, in which the marking layer ( 8th ) by means of a printing process, preferably by screen printing, intaglio printing, offset printing, Lettersetdruck or a transfer process to the carrier body ( 2 ) is applied. A method according to claim 16, wherein upon application of the marking layer ( 8th ) a printing ink is used in which, in addition to the electroluminescent pigments ( 10 ) a solvent and / or binder is included. A method according to claim 16 or 17, wherein the Printing ink has a total pigment content of less than 30%, preferably less than 25%. Process for the preparation of electroluminescent pigments ( 10 ) according to claim 12, wherein the pigment cores ( 20 ) by means of physical vapor deposition (PVD) and / or chemical vapor deposition (CVD) and / or plasma process and / or a sol-gel process and / or Aufpolymerisierens and / or electrochemical / electroplating and / or fluidized bed process and / or means Self-assembling and / or hybridization with the coating ( 24 ). Process according to Claim 19, in which the pigment cores ( 20 ) after coating ( 24 ) are subjected to a milling process such that a part of the coating ( 24 ) is broken away, so that then at most a part of the surface of the respective pigment core ( 20 ) with the coating ( 24 ) is covered. The method of claim 20, wherein the grinding operation in a ball mill carried out being, before or during the grinding a grinding aid is supplied. A method according to claim 21, wherein as a grinding aid Acetylcholine and / or oil and / or an aqueous one Suspension is used. Process according to Claim 20, in which the grinding operation is carried out in a paint-making process in a three-roll color dye, the coated pigments ( 10 ) Are part of the color. A method according to claim 23, wherein as further Components of the color color binders and color pigments are provided. A method according to claim 23 or 24, wherein the distance of the surfaces of the rolls of the three-roll color wheel to a value of at most the average diameter of the pigments ( 10 ) is set. Method according to one of claims 20 to 25, wherein the Grinding process for a maximum of 2 hours becomes.