HK1198481B - Security feature having several components - Google Patents

Description

Security feature with several components

The invention relates to a security feature having a luminescent component and a security feature concealing the luminescent component.

The name "value document" is to be understood within the framework of the invention to mean banknotes (bank notes), checks, stocks, tokens, identity cards, credit cards, passports and other documents as well as labels, seals, parcels or other elements for product authentication.

It has long been known to protect value documents from forgery by means of security features with luminescent components. The luminescent component is formed here by a substance, which will also be designated as luminophore (luminophore) in the following, formed by a host lattice doped with a transition metal or a rare earth metal as the luminescent ion. Such ions have the following advantages: upon suitable excitation, they exhibit one or more characteristic narrow-band luminescence that facilitates reliable detection and delineation with respect to other spectra. With regard to doping, combinations of transition metals and/or rare earth metals have been discussed. Such substances have the following advantages: in addition to the above-mentioned luminescence, so-called energy transfer processes are also observed, which can lead to more complex emission spectra. In such an energy transfer process, one ion can transfer its energy to another ion, and the spectrum can then consist of several narrow-band lines that are characteristic for both ions.

The security feature for protecting value documents has individual luminophores as luminescent components, the emission of which is different with respect to their spectral and/or temporal (temporal) properties. The security features are introduced and/or applied to the value document in different forms of use. For the luminescent component, combinations of luminophores may also be used. The emission bands of the luminophores used constitute the spectral code. Several different luminophores may be combined into a system, wherein the individual systems are independent of each other. The emission of the luminophore used is also referred to as luminescence, whereby this may involve fluorescence and/or phosphorescence.

It is also known that the described security features are not formed solely from luminescent components. As a further component, some security elements have a component for hiding the luminescent component. For example, DE 3048734 a1 describes security papers with concealed substances which protect authentication features. The masking substance of the masking component corresponds here substantially to the luminescent component, i.e. a very similar or identical (like-kind) host lattice and dopant is used both for the luminescent component and for the masking component. However, when manufacturing a sequestering substance for the sequestering component, it is ensured that the sequestering substance has no luminescent properties. For this purpose, the parameters of the masking component during annealing or grinding are varied, for example, in contrast to the production of luminescent components. Alternatively, so-called luminescence inhibitors (killers) are used. This prevents the use of conventional analytical techniques to distinguish luminescent components from cryptic components. In this way, the position of the luminescent component is largely concealed, since it cannot be distinguished using conventional methods from concealing components.

Since the luminescent component and the covert component comprise very similar or even identical substances, substance identity (identity) -based concealment of the luminescent component cannot be achieved, since the use of a covert component increases the total exploitable amount of material of the security feature in the value document to be protected and therefore tends to promote, rather than hinder, the analyzability of the security feature or the luminescent component.

Starting from this prior art, the invention is based on the following objects: a security feature is specified having a luminescent component and a component concealing the luminescent component, wherein an analysis of the type and doping of the host lattice employed for the luminescent component is prevented or at least substantially prevented. It is desirable herein to achieve the concealment of luminescent components both in elemental analysis and in structural analysis. Identification of the luminescent component is also hampered in the following cases: the security features are present in pure form before introduction into the value document or by ashing of the actual value document and can then be investigated by elemental analysis methods such as XRF (X-ray fluorescence analysis) or ICP-AES (inductively coupled plasma optical emission spectroscopy) or by structural analysis methods such as X-ray powder diffraction.

The achievement of this object is to be found in the independent claims. The dependent claims are developments of the subject matter.

The invention proceeds from a security feature having a luminescent component with at least one luminophore consisting of a doped host lattice and a component which conceals the luminescent component, wherein the concealer component has at least two substances, a first substance of the concealer component having an X-ray diffraction pattern which masks an X-ray diffraction pattern of the luminescent component and a second substance of the concealer component having at least one cationic element of the luminescent component and at least one cationic element of the first substance of the concealer component, wherein the first substances of the luminescent component and the concealer component are formed from different cationic elements.

The invention has the following advantages: when different elements are used for the first substance of the covert component and the luminescent component, the first substance of the covert component can be more easily found for masking the X-ray diffraction pattern of the luminescent component, since as a result more choices of substances are available for the first substance of the covert component. This makes it possible to conceal the structure of the luminescent component particularly well, since effective concealment of the structure is achieved only in the case of different, partially overlapping X-ray diffraction patterns, whereas effective concealment of the structure cannot be achieved in the case of complete or almost complete overlapping X-ray diffraction patterns. The use of a second substance having a sequestering component of at least one cationic element of both the luminescent component and the first substance of the sequestering component allows for an interlacing (interlace) of the luminescent component and the first substance of the sequestering component, thereby making it impossible to determine a single component and thus in particular the luminescent component, or at least substantially hampering this determination.

Further advantages of the invention will be apparent from the dependent claims and the following description of embodiments with reference to the drawings.

Shows that:

FIG. 1 is a first embodiment of a security feature having a luminescent component and a component concealing the luminescent component; and

FIG. 2 is a second embodiment of a security feature having a luminescent component, a component concealing the luminescent component, a manufacturing component, and a coding component; and

FIG. 3 has a third embodiment of a security feature of a luminescent component, a component concealing the luminescent component, a manufacturing component, and a coding component.

For example, from WO 81/03507a1, EP 0966504B1, WO 2011/084663a2, DE 19804021a1 and DE 10111116a1, security features for the protection or marking of documents of value are known which have a luminophore-based luminescent component which is composed of a host lattice doped with transition metals or rare earth metals as luminescent ions and has specific properties with regard to its emission and/or excitation. Such security features are added directly to the pulp in powder form during the paper production or to other base materials of the document of value, such as plastics. Alternatively or additionally, the powder is added to a printing ink which is subsequently printed on the substrate of the document of value. The security feature may also be included in other components of the value document, for example in a thread (thread), a planche (planche), a patch (patch), etc., which are in turn introduced into or applied to the value document.

The powdered security feature having the luminescent component in the form of a luminophore as described above further comprises a component concealing the luminescent component. The masking component is selected here such that it leads to masking or masking of the luminescent component in the case of the structures and elemental analysis methods stated at the outset. For this purpose, the covert component has an X-ray diffraction pattern which, for example, at least partially overlaps with the X-ray diffraction pattern of the luminescent component, as will be explained more accurately below.

For this purpose, the sequestering component may employ at least a first substance that is not necessarily materially similar to or the same as the substance used for the luminescent component, i.e., the first substance of the luminescent component and the sequestering component does not necessarily have to have the same elements in whole or in part. Thus, the X-ray diffraction pattern of the first material through the luminescent component and the covert component is at a significant peak (si)_gnificant_peak), it is not possible or at least very difficult to deduce the luminescent components present in the security feature using common structural analysis methods such as X-ray powder diffractometry.

The purpose of element analysis for the security features is to analyze the security features byQuantitative analysis of the composition of the security feature to derive inferences about the identity of the host lattice used. Methods such as XRF enable particularly "difficult" elements to be readily detected. The problem is in particular that oxygen is quantified, which cannot be detected by XRF or by ICP-AES or similar methods. Since oxygen usually forms the "remainder" of the matrix (e.g., as an oxygen ion) after detection of other components of the host lattice, however, detection of oxygen is not necessarily required in order to identify the host lattice. When the cationic component of the host lattice has been quantified, the host lattice contained can be identified by forming the proportions of the components, even in mixtures of different substances. Thus, for example, ZnAl₂O₄And BaMnO₄Always contains Al and Zn in a ratio of 1:2 and Ba and Mn in a ratio of always 1:1, said ratio being independent of the mixing ratio of the two elements. Therefore, it is clear that these components are individually referred to as host lattices, and by doing so, the host lattices can be identified.

In order to prevent or at least partially hamper such a procedure, the components must be "staggered," which term is intended herein to mean that all components or substances to be concealed have at least one overlapping chemical element, at least in pairs. The components/substances to be concealed, which have overlapping elements in pairs, comprise at least a luminescent component and a first and a second substance of a concealing component. In addition, further components/substances, such as manufacturing components and/or coding components, may have elements that overlap with other components/substances. The proportions of the individual chemical elements must be present here in a sufficient order of magnitude to significantly distort the formation of proportions from the elemental analysis (distor). For example, in₂O₄And BaMnO₄In the mixture of (a), the correct integral ratio between the proportions of Zn and Mn or between the proportions of Ba and Mn is not found, since Mn is present in both the host lattice-forming components or species. Preferably, the detected quantitative ratio of overlapping chemical elements of the compound is increased by at least 30%, preferably by at least 50%, particularly preferably by at least 100%, relative to the pure compound. The quantitative proportion may also be increased by at least 200%.

In order to obtain an "interlacing" of the luminescent component and the first substance of the covert component, at least a second substance is used in the covert component, the second substance having both at least one element of the substance forming the luminescent component and at least one element of the first substance forming the covert component, because the elements of the luminescent component and the elements of the first substance of the covert component are different. An element in this context is to be understood as a chemical element which is contained in both the substance forming the luminescent component and the second substance forming the covert component. In particular, an element or chemical element should not be understood to mean that one or more of the same atoms is a component of two components or substances. If the substance forming the luminescent component has, for example, elements a and B and the first substance of the masking component has elements C and D, then the second substance of the masking component may have, for example, elements a and C, A and D, B and C and/or B and D, where elements A, B, C and D are not formed from oxygen or hydrogen. In addition to elements A, B, C and D, the substance may have additional elements, particularly oxygen and/or hydrogen. However, oxygen and hydrogen would not be considered elements to achieve species interleaving as desired by the present invention. Suitable elements are especially cationic matrix components, in particular cations of metals, transition metals, semimetals and rare earth elements. By additionally comprising oxygen, the elemental cations may also form a subset of anions as a constituent of the matrix, which is likewise suitable for interleaving. Thus, for example, phosphorus and silicon cations may be present in the matrix, for example in the form of phosphates and silicates. The material interleave As intended by the present invention can Be formed by main group elements Li, Be, B, Na, Mg, Al, Si, P, S, K, Ca, Ga, Ge, As, Se, Rb, Sr, In, Sn, Sb, Te, Cs, Ba, Tl, Pb, Bi, and by any of transition metals and rare earth elements.

Thus, the above elements or chemical elements as intended by the present invention are also referred to alternatively as cationic elements, cationic matrix components, cationic components of the host lattice, or elemental cations. This should clearly express that especially the chemical elements oxygen and/or hydrogen are not considered as chemical elements to achieve substance interleaving as intended by the present invention.

Fig. 1 represents, by way of example, a luminescent component LK consisting of one atom of each of the elements a and B, a first substance S1 of a cryptic component TK consisting of one atom of the element C and three atoms of the element D, and a second substance S2 of the cryptic component TK consisting of two atoms of the element B and one atom of the element C. The desired composition "interlacing" is obtained by masking the second substance S2 of the composition TK, which second substance S2 has an element common to the luminescent component LK, element B, and an element common to the first substance S1 of the X-ray diffraction pattern of the masked luminescent component, element C.

In the example of fig. 1, a ═ yttrium, B ═ aluminum, C ═ silicon, and D ═ calcium can be considered. The luminescent component LK is then, for example, a rare-earth-doped yttrium perovskite such as YAlO₃Yb, which can be excited, for example, at 975nm and emits light in the range from 975nm to 1020 nm. The sequestering component is formed, for example, from a first substance S1, such as Ca₃SiO₅And a second substance S2 such as Al₂SiO₅And (4) forming. The main peak in the diffractogram of yttrium perovskite is located at 34.2 ° (all explanations and the following explanations of the peak positions are made at an angle 2 θ). Ca₃SiO₅Is located at 34.3 deg., thereby resulting in partial overlap of the X-ray diffraction patterns. By adding Al₂SiO₅When the mixture was subjected to elemental analysis, neither a Y: Al ratio of 1:1 of the luminescent component nor a Ca: Si ratio of 3:1 of the first substance S1 of the masking component was obtained.

The security feature has 20% to 80%, preferably 25% to 60%, particularly preferably 30% to 50% of a luminescent component (all percentages and the following percentages are by weight). The luminophores referred to herein are luminophores that emit light in the non-visible region of the spectrum and consist of a doped host lattice. Preferably, the luminophore has a high quantum yield or signal intensity and a suitable decay time in order to ensure error-free testability (error-free testability), even in the case of small amounts used in the value document and at high movement speeds as are carried out, for example, in banknote processing machines with processing speeds of up to 40 banknotes per second or higher. Suitable luminophores for the luminescent component are, for example, inorganic crystalline matrices doped with rare earth elements and/or transition metals and having a decay time in the range between 50 μ s and 10ms, such as oxides (for example in the form of garnets, spinels or perovskites) and oxysulfides, sulfides, silicates, phosphates, aluminates, niobates, tantalates, vanadates, germanates, arsenates, zirconates or tungstates.

The security feature comprises a covert component in a proportion of 20% to 80%, preferably 30% to 75%, particularly preferably 40% to 70%. In addition, the security feature may also comprise a non-covert component in addition to a covert component. The amount of the sequestering component used depends on, inter alia, the amount and relative crystallinity of the luminescent component. This means that the relative intensity of the first species of the blinding component in the X-ray diffraction pattern of the mixture of the blinding component and the luminescent component substantially obscures the luminescent component in the region of overlap. If the luminescent component exhibits only a weak signal in the X-ray diffraction diagram, for example due to small grain (grain) size or small proportions in the mixture, or if the sequestering component has a particularly strong signal in the X-ray diffraction diagram due to its high crystallinity or suitable composition, the desired sequestering effect is achieved as long as less sequestering component material is used in total. In order to obtain a distortion of the X-ray diffraction pattern which is sufficient for concealment, the concealing component causes a relative change in the area integral of at least 20%, preferably at least 40%, particularly preferably at least 60%, very particularly preferably at least 80%, of the overlapping peaks of the luminescent component in the overlapping region of the X-ray diffraction patterns of the luminescent component. The masking component may be composed of a first substance and a second substance, but may additionally comprise other substances which are likewise capable of being interlaced on an element.

The masking component must be added to the security feature herein in the following amounts: the respective peaks of the covert component and the luminescent component are intensity equivalent (compabarystron) as determined by X-ray powder diffraction of the security feature. The X-ray diffraction patterns of the cryptic and luminescent components herein must not be identical or highly similar, as this does not hinder but facilitates the analysis. Thus, the substances used should not be structurally related. However, it is likewise disadvantageous when the peak positions of the two X-ray diffraction patterns show a mismatch, since in this case a separation into the individual components is particularly easy. Preferably, the sequestering component is used in such a form that at least one, preferably two, particularly preferably three, relevant peak positions of the sequestering component and the corresponding peak positions of the luminescent component match. "match" in this context is to be understood as meaning that the peak maxima of the two peaks of the luminescent component and the covert component differ by at most 1 °, preferably by at most 0.5 °, particularly preferably by at most 0.2 ° (2 Θ). "correlated" herein will be understood to mean that the peaks are sufficiently strong to be important for identifying the substance. Preferably, two to three overlapping peaks have a main peak height of at least 30%, particularly preferably at least 50%. It is particularly preferred that one of the matching peaks is one or both of the main peaks (a main peak or body main peaks) of the substance forming the luminescent component and the masking component. This partial overlap prevents the identification and separation of the individual X-ray diffraction patterns. This is especially the case when the cryptic component has at least one species whose X-ray diffraction pattern is not generally known, i.e. not contained in a commonly used structural database. In addition to the structure type itself, it is likewise possible to draw conclusions about the elemental content or the degree of distribution of the stoichiometrically or non-stoichiometrically mixed compounds from the relative heights of the individual peaks. For example, many structures can form a homogeneous mixed series when elements are exchanged at some crystal positions with different elements that differ only slightly in structure, particularly in unit cell size, but can be identified by their different relative peak heights. Thus, as an additional advantage, local overlap conceals precise relative proportions between individual peak heights, even upon successful identification and separation of individual X-ray diffraction patterns, thereby substantially impeding inferences about the precise stoichiometry of the concealed matrix.

In order to obtain such a match of some peak positions of the luminescent component and the covert component species, it may be necessary to specifically employ the lattice constant of the covert component species. This is preferably done by partially replacing the lattice components with atoms having larger and/or smaller radii in suitable proportions. In some substancesIn the structure of (3), this makes it possible to obtain a continuous variation of the lattice parameter, for example by widening the lattice by inserting atoms with a larger atomic radius, thereby in turn shifting the peak positions of the X-ray diffraction pattern. As a further advantage, the peak positions of such partially substituted species are often present in the usual X-ray structure database only for some individual substitution ratios, thereby further hampering the analysis. For example, for substances A in which A is replaced by B₂SiO₄Complete substitution of B is often found₂SiO₄Semi-substituted ABSiO₄And is unsubstituted for A₂SiO₄Not in any proportion, e.g. A_0.21B_1.79SiO₄. For example, the isomorphic compound Ba₂SiO₄、BaCaSiO₄And Ca₂SiO₄The X-ray diffraction pattern of (a) is known. The positions of the two strongest XRD peaks herein for Ba₂SiO₄29.4 ° and 30.4 °, respectively, for BaCaSiO₄30.6 ° and 31.5 °, respectively, and for Ca₂SiO₄Respectively 32.0 deg. and 32.5 deg.. However, any intermediate state can be made to adopt the position of the peak. This makes it possible to improve the overlap with the X-ray diffraction pattern of the luminescent component. At the same time, the finding of compounds by using X-ray structure databases is hampered.

Likewise, it is possible to strongly influence the relative intensity ratios of the individual peaks of the X-ray diffraction pattern by substitution with lighter and/or heavier atom types, even when their positions are not changed and are only weakly changed due to the constant lattice parameters. In combination with partial matching of some peaks of the mixture of substances of the luminescent component and the covert component, an X-ray diffraction pattern can thus be produced which is particularly difficult to analyze.

In rare individual cases, the first and second species of the covert component may be the same, i.e., one species has both an X-ray diffraction pattern that overlaps only partially with the luminescent component and an element that is partially common with the reflective component. In such a case, it is possible to represent the functionality of the sequestering component by only one substance. However, it is advantageous, and therefore preferred, to use two different substances for the first and second substances of the masking component. First, finding a single substance that satisfies both conditions is difficult, and thus can only be achieved in rare cases or poorly applied to a range of different security features. In addition, a system with only one covert component has a simpler structure and is therefore easier to decode (decrypt).

Preferably, the luminescent component and the sequestering component also have the same or at least similar density, such that they cannot be easily separated, e.g. by sedimentation. Preferably, the density of the covert component deviates less than 50%, particularly preferably less than 30%, in total from the density of the luminescent component.

Hereinafter, some embodiments of a security feature consisting of a luminescent component and a covert component will be described.

Example 1

As a luminescent component, Nd-doped calcium niobate CaNb is used₂O₆Nd by mixing 2.675g of CaCO₃、7.234g Nb₂O₅And 0.092g Nd₂O₃Is annealed at 1150 c for 10 hours. Upon excitation at 532nm, the luminescent component emits light at 1061 nm. The main peak in the X-ray diffraction pattern of the luminescent component here lies at 29.2.

As the first substance of the masking component, monoclinic Zr (MoO) having a main peak at 29.1 ℃ may be used₄)₂. As second substance of the masking component, CaZrO can be used₃。

Thus, the security feature comprising a luminescent component and a covert component has, for example, the following composition:

40％CaNb₂O₆:Nd

30％CaZrO₃

30％Zr(MoO₄)₂。

example 2

As the light-emitting component, KY is used_0.95Ho_0.05(WO₄)₂By mixing 6.80g K₂WO₄、3.00g YCl₃·6H₂O and 0.198g HoCl₃·6H₂The mixture of O was annealed at 800 ℃ for 6 hours. Upon excitation at 650nm, the luminescent component emits light at 2014 nm.

The main peak in the diffraction pattern of the luminescent component here is located at 28.1 °. As the first substance of the masking component, CsSrLa (PO) having a main peak at 28.1 ℃ can be used₄)₂. As the second substance of the masking component, YPO can be used₄。

Thus, the security feature comprising a luminescent component and a covert component has, for example, the following composition:

30％KY_0.95Ho_0.05(WO₄)₂

40％CsSrLa(PO₄)₂

30％YPO₄。

example 3

As luminescent component, use is made of Y_1.98Nd_0.02SiO₅It is produced by: 2.66g of urea and 0.53g of SiO were mixed₂、6.72g Y(NO₃)₃·6H₂O、0.08g Nd(NO₃)₃·5H₂O and 3mL H₂O, evaporating the liquid at 500 ℃ and annealing the resulting material at 1500 ℃ for 10 hours. Upon excitation at 532nm, the luminescent component emits light at 1075 nm.

The significant peak (> 70% of the main peak) in the diffractogram lies at 22.8 °.

AsAs the first substance of the masking component, NaTaO having a main peak at 22.8 ℃ can be used₃. As the second substance of the masking component, YTaO can be used₃。

Thus, a security feature comprising a luminescent component and a covert component has, for example, the following composition:

35％Y_1.98Nd_0.02SiO₅

30％NaTaO₃

35％YTaO₃。

example 4

As the luminescent component, KTiO (PO) was used₄) Er by mixing 18.78g KH₂PO₄、10.90g TiO₂And 0.61g Er₂O₃The mixture of (a) was annealed at 800 ℃ for 12 hours.

Upon excitation at 520nm, the luminescent component emits light at 1540 nm. The main peak in the diffraction pattern of the luminescent component is located at 32.3 DEG, wherein the immediately adjacent significant peak (>70% of the main peak) at 32.6 °. As the first substance of the masking component, LaMnO having two significant peaks (90 to 100% of the main peak) at 32.3 DEG and 32.6 DEG in the diffraction pattern can be used₃. As the second substance of the masking component, LaPO may be used₄。

Thus, the security feature comprising a luminescent component and a covert component has, for example, the following composition:

35％KTiO(PO₄):Er

35％LaMnO₃

30％LaPO₄。

example 5

As luminescent component, use is made of luminophores from the preceding examplesKTiO(PO₄) Er and CaNb₂O₆Nd. Here, the component KTiO (PO)₄) Er will be concealed. For this purpose, as in the previous embodiments, LaMnO may be used₃. Alternatively, KTiO (PO)₄) Er also has a significant peak(s) at 28.8 °>80% of the main peak) and a significant peak at 25.9 ° (>30% of main peak) as the first substance of the masking component, β -BaSO having two significant peaks (95-100% of main peak) at 25.9 ° and 28.8 ° in the diffraction pattern can be used₄. As the second substance of the masking component, BaTiO may be used₃。

Thus, the security feature comprising a luminescent component and a covert component has, for example, the following composition:

20％KTiO(PO₄):Er

15％CaNb₂O₆:Nd

35％β-BaSO₄

30％BaTiO₃。

wherein CaNb₂O₆Alternative compositions in which the elemental composition of Nd is additionally buried are:

20％KTiO(PO₄):Er

15％CaNb₂O₆:Nd

25％β-BaSO₄

20％BaTiO₃

20％CaTiO₃。

both luminophores are concealed and contain Ba₃(PO₄)₂And LanbO₃Alternative compositions of the second substance as a masking component are for example:

20％KTiO(PO₄):Er

15％CaNb₂O₆:Nd

20％β-BaSO₄

15％CsSrLa(PO₄)₂

15％Ba₃(PO₄)₂

15％LaNbO₃。

by using further components with different functionalities, additional advantageous properties of the security feature may be achieved, whereby additionally an increased security against counterfeiting may be obtained. The further components and the luminescent and sequestering components can be matched to one another with regard to their amount and elemental composition and also with regard to their structure.

As a further component, a manufacturing component may be included in the security feature. The security feature has 0 to 30%, preferably 0 to 20% of a manufacturing component. The manufacturing component is used to ensure an unchanged quality or signal intensity of the security feature or the luminescent component contained therein. Depending on the manufacturing conditions, such as the raw material batch used and the impurities contained therein, annealing parameters, milling parameters, etc., fluctuations in the intensity of the luminescence signal of the luminescent component may occur. In order to compensate for this fluctuation, the production components are added to the security element in a proportion such that the luminescence signal of the security element obtained therefrom is adjusted to a defined nominal magnitude. This avoids the need to change the respective metering when using the security feature when introducing the security feature into the value document at the time of the aforementioned fluctuations. In contrast to the covert component, the proportion of the manufacturing component relative to the luminescent component is variable, since the desired proportion of the manufacturing component in the security feature depends on the respective production conditions, as described above.

It is not absolutely necessary but preferred that the manufacturing component comprises a crystalline material. In this case, it is further preferred that the peak positions of the X-ray diffraction patterns of the manufacturing component and the covert or luminescent component at least partially overlap in the manner described above. In this way, the X-ray analysis can be additionally hampered.

Further, there may be provided: chemical analysis and separation of luminescent, sequestering, and manufacturing components is also prevented or at least hindered. For this purpose, the manufacturing component may have both at least one element of the substance forming the luminescent component and/or at least one element of the substance forming the covert component. Likewise, the manufacturing component may have a second substance having at least one element of the first component of the manufacturing component and at least one element of the luminescent and/or covert component. When the luminescent component and the covert component have elements A, B, C and D, such as described above, the make component has at least one of element A, B, C or D. The manufacturing component may additionally have one or more further elements E as well as oxygen and/or hydrogen.

When YAlO is used as has been described as an example₃Yb as a luminescent component, Ca₃SiO₅First substance as a masking component and Al₂SiO₅As second substance of the sequestering component, for example, compounds which do not have an additional sequestering effect, for example titanium dioxide, can be used as production compensator (production compensation). However, it is preferred to use compounds having at least one element of the luminescent or sequestering component, for example MgAl₂O₄Since this additionally hampers the elemental analysis of the mixture. Alternatively, a compound having a main peak at 34.4 ° in the X-ray diffraction pattern and thus overlapping with the diffraction pattern of the luminescent component, such as Mg, may be used₂SnO₄。

Example 6

The luminescent and hiding components were the same as in example 1. As a manufacturing compensator, CaCO was used₃. Thus, the security feature comprising a luminescent component, a covert component and a manufacturing compensator has for example the following composition:

30％CaNb₂O₆:Nd

25％CaZrO₃

25％Zr(MoO₄)₂

20％CaCO₃。

example 7

The luminescent and hiding components were the same as in example 2. Ca was used as a production compensator₃(PO₄)₂. Thus, the security feature comprising a luminescent component, a covert component and a manufacturing compensator has for example the following composition:

30％KY_0.95Ho_0.05(WO₄)₂

30％CsSrLa(PO₄)₂

25％YPO₄

15％Ca₃(PO₄)₂。

further components of the security feature may be formed from the coded component. The coding component is contained in the security feature in a proportion of 0 to 10%, preferably 0.5 to 5%, particularly preferably 1 to 3%. The coding component comprises substances which serve as legal (forensics) features by means of which, for example, different production batches, deliveries (deliveries), manufacturers or processors (processors) can be marked. Preferably, the coding component is formed by a luminophore. However, the luminophore does not necessarily have to emit in the non-visible region of the spectrum like the luminescent component, but may, for example, preferably emit in the visible region of the spectrum. Since the coding component is designed as a legal feature, it does not necessarily have the above-mentioned properties for evaluation in banknote processing machines at high transport speeds. However, it should be determined that the evaluation of the luminescent component is not adversely affected by the coding component. Preferably, the coding component is therefore as different as possible in excitation and emission from the luminescent component. The detection of the coding components can be achieved via legal methods, for example by measurement using fluorescence microscopy or by means of professional laboratory equipment, whereby significantly longer measurement times (for example, several minutes up to several hours) compared to the luminescent components can also be necessary for reliable detection.

As coding component there is a collapsed zeolite structure loaded with rare earth metals and/or transition metals as described in e.g. DE 10056462 a1, which is preferably used. These provide the advantage that the zeolite can be easily loaded with various cations by ion exchange. It is also preferred to use a matrix doped with rare earth metals and/or transition metals having a narrow band spectrum in the visible region. Preferably, the dopant used herein is a trivalent rare earth cation of praseodymium, samarium, europium, terbium and dysprosium that emits light in the visible region, and the matrix used is an oxide (e.g., in the form of garnet, spinel or perovskite), as well as oxysulfide, sulfide, silicate, phosphate, aluminate, niobate, tantalate, vanadate, germanate, arsenate, zirconate or tungstate. Examples of such and further substances are described in the publications US 3,980,887, US 4,014,812, US 3,981,819 and WO 2006/047621a 1. Besides excitation spectra or emission spectra, luminescence lifetimes may also be tested. The proportion of rare earth ions and/or transition metals in the coding component can be so high here that it is comparable to the concentration of rare earth and/or transition metals of the dopant of the luminescent component upon elemental analysis of the security feature. This hampers the identification of the dopant for the luminescent component. As explained above with regard to the other components, it is preferred that the doping of the coding component and the luminescent component is also effected with different elements, since otherwise the chemical analysis is not impeded, but rather is facilitated. Furthermore, further cations not involved in luminescence may be embedded in the zeolite structure or luminophore matrix material to influence the elemental composition of the coding component.

The rare earth metal and/or transition metal may be added not only to the coding component but also to the fabrication component and/or the masking component and/or other components to additionally protect the dopants of the luminescent component. The amounts of rare earth metals and/or transition metals are as described above for the coding component here, i.e. the amount of rare earth metals and/or transition metals added is comparable to the amount of dopants of the luminescent component. Comparable in this context is intended to mean that the molar amount added amounts to at least 30% of the molar amount of the dopant of the luminescent component. The rare earth metals herein may be incorporated firmly into the crystal lattice of the respective component or, for example, may be preferably incorporated as an additional separate substance into the respective component if direct incorporation into the matrix of the component proves to be technically disadvantageous or difficult. For example, the manufacturing component or another component may be composed of a mixture of a substance having no rare earth element content and a substance containing a rare earth element. When the individual rare earth element-containing substances are used, their proportion in the total mixture preferably amounts to 0.5 to 4%, particularly preferably 1 to 2%.

In addition to the manufacturing component and the coding component, the security feature may have further functional components added thereto, which likewise do not necessarily have a masking effect. Examples of such additional components are, for example, dyes for modifying the color of the security feature, light-emitting absorbers which suppress unwanted visible fluorescence of the security feature, fluxes for adjusting the rheology of the powder forming the security feature, or pure additions of rare earth metal compounds and/or transition metal compounds for protecting the identity of the dopants used (pure addition).

For a security feature formed by atoms other than oxygen A, B, C, D and E with five different host lattices, the interleaving of elements for only the luminescent and covert components may be performed, for example, as in fig. 2, and the interleaving of elements for all components may be performed, for example, as in fig. 3.

The security feature according to fig. 2, in which a ═ Y, B ═ Al, C ═ Si, D ═ Ca, E ═ Ti, F ═ Gd, G ═ B, can be composed, for example, of 35% of luminescent component LK (e.g. YAlO)₃Yb), 45% of a first substance S1 (for example Ca) with 20%₃SiO₅) And 25% of a second substance S2 (e.g. Al)₂SiO₅) Of a cryptic component TK, 18% of a make component PK (e.g. TiO)₂) And 2% of a coding component KK (e.g., GdBO)₃Tb). When performing elemental analysis on the mixture and determining the relative proportions of A, B, C, D and E, it is not possible to find an inference as to the identity of the luminescent component LK, for example from the relative proportions of A and B (in the example Y and Al). In the luminescenceThe ratio of Y to Al in the composition is exactly equal to 1:1, but in the security feature mixture comprising the covert component the molar ratio of Y to Al is equal to 1: 3.3. When such a ratio is found in elemental analysis, it will not seem obvious at first glance that Y forms a matrix together with Al, and also yttrium aluminum perovskite is not expected as a luminescent component for this ratio. Due to the small proportion of material extractable from the banknotes or the material contained in the banknote ash, additional analysis by X-ray diffractometry will yield diffraction patterns of very poor quality with low signal-to-noise ratios and possibly widely broadened peaks, caused for example by damage to the crystalline structure caused by chemical treatment or ashing processes by extraction. By YAlO₃And Ca₃SiO₅Overlap of diffraction patterns of (YAlO)₃Is hidden and falsified at the relevant location and may thus not even be recognized. However, it is also possible, for example, for only Ca to be perceived at the overlap of the main peaks₃SiO₅As a possible phase, since otherwise no further strong signals can be recognized. Thus, the identification of luminescent components has been significantly hampered compared to the use of pure substances.

The security feature according to fig. 3, in which a ═ Y, B ═ Al, C ═ Si, D ═ Ca, E ═ Ta, can be composed of, for example, 35% of luminescent component LK (for example YAlO)₃Yb), 45% of a first substance S1 (for example Ca) with 20%₃SiO₅) And 20% of a second substance S2 (e.g. Al)₂SiO₅) TK of cryptic component 18% manufacturing component PK (e.g. Ca)₂Ta₂O₇) And 2% of a coding component KK (e.g., YTaO)₄Pr) is added. When performing elemental analysis on the mixture and determining the relative proportions of A, B, C, D and E, as in the example of fig. 2, it is not possible to find an inference about the identity of the luminescent component LK, for example from the relative proportions of a and B. In addition, the first substance Ca of the cryptic component₃SiO₅Nor can it be inferred from the Ca: Si ratio, however, this leads to additional uncertainties in the analysis and additionally prevents a correct interpretation of the diffraction patterns. Also, since the coding component is in the entire mixtureThe small ratio and the significantly higher ratio of yttrium or tantalum, the encoded component cannot be separated from the other components, such that its presence or precise composition is "hidden" by the common elements of the other components.

Example 8

The luminescent and covert components were the same as in example 3. As a manufacturing compensator, CaCO was used₃. To conceal dopants, Ε r is used₂O₃And Dy₂O₃. As coding component, CatA was used₂O₆:Sm_0.03(luminescence at 610 nm). Thus, a security feature comprising a luminescent component, a covert component, a manufacturing compensator and a coding component has for example the following composition:

33％Y_1.98Nd_0.02SiO₅

25％NaTaO₃

25％YTaO₃

10％CaCO₃

5％CaTa₂O₆:Sm_0.03

1.5％Er₂O₃

0.5％Dy₂O₃。

example 9

The luminescent and covert components were the same as in example 4. Ca was used as a production compensator₃(PO₄)₂. For concealing the dopant, Nd is used₂O₃. As coding component, LaOBr: Tb (emitting light at 543 nm) was used. Thus, a security feature comprising a luminescent component, a covert component, a manufacturing compensator and a coding component has for example the following composition:

30％KTiO(PO₄):Er

30％LaMnO₃

25％LaPO₄

12％Ca₃(PO₄)₂

2％LaOBr:Tb

1％Nd₂O₃。

it will be noted that the elemental quantities and relative stoichiometries of the compounds composed of elements a-G as described in figures 1-3 are merely representative examples for describing the invention and are not intended to be limiting.

It is also possible that more than two components or substances used therefor have the same element or that more than one element is the same between two components or substances.

Also, the luminescent component may have more than one substance, i.e. more than one luminophore. In this case, it is preferable to provide the first and second substances in the covert component for each luminophore of the luminescent component. If this is not possible or involves increased effort, for example for technical reasons, it may be sufficient to conceal only a single luminophore in the luminophore combination, since in order to successfully imitate the security feature, all luminophores of the luminophore combination generally have to be identified. In such a case, only one of the several luminophores is preferably protected by the first and second substances of the covert component.

If similar substances are used for the luminophores, for example matrices of the same type with different dopants, it may be sufficient to provide only the first and second substances in the covert component for similar substances of the luminescent component, in order to obtain an interlacing of several luminophores in the above sense.

In order to substantially prevent analysis, the security feature preferably consists of at least three, preferably four, particularly preferably five, different substances which differ in the elemental composition of their host lattice.

Security features can be used in value documents for ensuring their authenticity and/or codes representing some property, such as currency and/or denomination, etc., if the value document is a banknote.

Claims (28)

1. A security feature, having: a luminescent component having at least one luminophore consisting of a doped host lattice, and a component which conceals the luminescent component, characterized in that the concealer component has at least two substances, a first substance of the concealer component having an X-ray diffraction pattern which conceals the X-ray diffraction pattern of the luminescent component, and a second substance of the concealer component having at least one cationic element of the luminescent component and at least one cationic element of the first substance of the concealer component, wherein the luminescent component and the first substance of the concealer component are formed from different cationic elements, and wherein the X-ray diffraction patterns of the luminescent component and the first substance of the concealer component are partially overlapping.

2. The security feature of claim 1, wherein said security feature has a manufacturing component for adjusting the luminescent signal intensity of said luminescent component to a presettable nominal value.

3. A security feature according to claim 2, characterized in that said manufacturing component has at least one cationic element which is a constituent of at least one other component of said security feature.

4. A security feature according to claim 2, characterized in that said manufactured components have at least two different cationic elements, a first of these two different cationic elements being a component of a first other component of said security feature and a second of these two different cationic elements being a component of a second other component of said security feature.

5. A security feature as claimed in any one of claims 1 to 4 in which the security feature has a coding component for legally marking the security feature.

6. A security feature according to claim 5, wherein said code component has at least one cationic element which is a constituent of at least one other component of said security feature.

7. A security feature according to claim 5, characterized in that said code component has at least two different cationic elements, a first of these two different cationic elements being a component of a first other component of said security feature and a second of these two different cationic elements being a component of a second other component of said security feature.

8. The security feature of claim 1 wherein the X-ray diffraction pattern of said luminescent component and the X-ray diffraction pattern of said first material of the covert component have a partial overlap of significant peaks wherein at least one of the relative peak positions is overlapping.

9. A security feature according to claim 8, characterized in that at least two correlation peak positions are overlapping.

10. A security feature according to claim 8, characterized in that at least three correlation peak positions are overlapping.

11. A security feature according to any one of claims 8 to 10, characterized in that said overlapping peaks have a main peak height of at least 30%.

12. A security feature according to any one of claims 8 to 10, characterized in that said overlapping peaks have a main peak height of at least 50%.

13. A security feature according to any of claims 8 to 10, characterized in that said overlapping peaks are the main peaks of the first substance of the luminescent component and the covert component.

14. A security feature according to any of claims 8 to 10, characterized in that said overlapping peaks are two main peaks of the first substance of the luminescent component and the covert component.

15. A security feature according to any one of claims 1 to 4 wherein said components and materials are formed from an oxidic inorganic host lattice or matrix.

16. A security feature according to any one of claims 1 to 4, wherein said security feature comprises 20 to 80% of said luminescent component and said security feature comprises 20 to 80% of said covert component and said security feature comprises 0 to 30% of a manufacturing component and said security feature comprises 0 to 10% of a coding component.

17. A security feature according to claim 16, wherein said security feature comprises 25 to 60% of said luminescent component.

18. A security feature according to claim 16, wherein said security feature comprises 30 to 50% of said luminescent component.

19. A security feature according to claim 16 characterised in that the security feature comprises 30 to 75% of the covert component.

20. A security feature according to claim 16 characterised in that the security feature comprises 40 to 70% of the covert component.

21. The security feature of claim 16, wherein said security feature comprises 0 to 20% manufacturing components.

22. A security feature according to claim 16, wherein the security feature comprises 0.5 to 5% of a coding component.

23. A security feature according to claim 16, wherein the security feature comprises 1 to 3% of the encoding component.

24. A security feature according to any one of claims 1 to 4 wherein the luminescent component and the covert component also have the same or similar density, wherein the density of the covert component deviates from the density of the luminescent component by less than 50% in total.

25. A security feature according to claim 24, characterized in that the density of the covert component deviates from the density of the luminescent component by less than 30% in total.

26. Value document having a security feature according to any one of claims 1 to 25, characterized in that the value document consists of paper and/or plastic.

27. A document of value according to claim 26, characterized in that the security feature is incorporated into the volume of the document of value and/or applied to the document of value.

28. A value document according to claim 26 or 27, characterized in that the security feature is applied to the value document as an invisible, at least partial coating.