EP3175037B1 - Security element, value document substrate, value document, method for producing said value document, and transfer belt - Google Patents

Description

The invention relates to a security element for bonding to a substrate, such as a security paper, a value document or another valuable item. The invention further relates to a value document substrate for producing value documents, in particular banknotes, a value document, a method for producing the value document and a transfer belt.

In particular, the invention relates to the use of chemically unstable inorganic security features in adhesive layers. The adhesive layer protects the security feature from harmful environmental influences, such as moisture, solvents, acids or bases, and thereby allows the use of the feature particles without an additional complicated treatment of the particles, e.g. by coating the feature particles with a protective silica shell.

Furthermore, the targeted use of intrinsically unstable security features additional advantages compared to ordinary, chemically stable security features can be achieved. For example, the chemical extraction of the feature substance from the adhesive layer or the removal of the adhesive layer by ashing of the banknote leads to a loss of the functionality of the security feature or to its destruction and possibly to the modification of a code from a plurality of individual features. It is thus not readily possible to use such extracted feature substances for the production of counterfeits. Likewise, an analysis of the identity of the security feature is made more difficult.

In the DE 3 514 852 A1 In general, the embedding of feature substances, in particular fluorescent substances, into the adhesive layer of letter or token is described.

In the EP 1 042 130 B1 It is described how to make a polymer banknote from several biaxially oriented polypropylene (BOPP) films that are bonded together by means of heat-activatable adhesive layers. Subsequently, the polymer banknote is coated with opaque pressure-receiving layers, printed, and provided with transparent, silica-containing protective layers. Furthermore, the introduction of magnetic feature substances into the polymer film via a thermal fusion process is described.

EP 2 388 551 A2 describes in this connection the combined production of the BOPP films with the "skin" adhesive layers by triple coextrusion.

The general introduction of luminescent feature substances in the bulk material of polymer banknotes is for example from WO 2011/084401 A2 known. Herein, the powdered feature substance is physically mixed with the thermoplastic substrate polymer and is finally embedded in the polymer film made of BOPP or PMMA, for example. This is explicitly discussed for the moisture-sensitive fluorides such as NaYF ₄ or CaF ₂ . In comparison to an incorporation into adhesives, however, this method is technically complicated or has technical disadvantages. In the case of the use of chemically very sensitive feature substances, this protective mechanism may be inadequate, since in this case the surrounding polymer material is not sufficiently cross-linked and, for example, in the attack with organic solvents swelling and is less resistant. Furthermore, the selection of feature substances shown herein, whose refractive indices are adapted to the refractive index of the surrounding polymer, limits the available materials relatively strongly.

The EP 1 545 902 B1 describes the preparation of the so-called Hybrid Banknote which is based on a film / paper / film composite substrate. Here, a paper core is connected on both sides with two thin, about 6 to 10 microns thick films and an intervening, three-dimensionally crosslinking adhesive layer. Feature substances with visually and / or mechanically detectable physical properties, eg luminescent substances, are either introduced into the paper volume or applied to the paper core, on the inside or on the outside of the film by means of printing. Likewise, the adhesive layer can be equipped with feature substances. The adhesives used for this purpose are water-crosslinking (eg via the air moisture) or UV-crosslinking adhesives. Particular preference is given to using a wet adhesive, in particular a polyurethane adhesive. However, there is no further description regarding the feature substances to be used, in particular with regard to their stability to environmental influences.

In Scripture DE 1020 1101 0127 A1 organic photochromic substances such as Bacteriorhodopsin be described, which are introduced for stabilization in a lacquer layer between two polymer films such as polyester, polyethylene terephthalate, polypropylene, polyethylene, polyamide or polycarbonate. However, such organic feature substances offer only a limited UV stability, have a number of other disadvantages compared to inorganic substances and do not develop those with inorganic substances achievable effects. The use or protection of chemically unstable inorganic feature substances is not described.

In the EP 1 607 520 B1 are described plastic safety threads, which can run obliquely, straight or randomly nonlinear through the banknote and have a fluorescent feature inside the polymer thread. The plastic fiber is 2 to 50 μm wide. However, there is no further description regarding the feature substances to be used, in particular with regard to their stability to environmental and temperature influences.

In the DE 3843077 A1 plastic security threads are described in which a carrier film is provided with a metallic or magnetic coating and then laminated or glued with a further film. In this case, however, no complete inclusion of the coatings and thus only limited protection against environmental influences is achieved.

In the WO 2007/068886 A1 "A security label is described which includes a rare earth ion doped carrier and its encapsulation in a UV absorbing barrier material (having an absorption coefficient> 0.6 for wavelengths of 300 to 400 nm) to shield the luminescent rare earth ions from broad band excitation in the UV , In particular, a microencapsulation of the inorganic feature substances with polymers, such as polyimide, is used for this purpose. However, the choice of rare earth luminescent substances is not limited, moreover protective functions play no role against the extraction test of the feature substance.

The WO 00/39397 A1 describes a feature system consisting of a combination of two feature substances having different temperature stability. As a particularly suitable embodiment, the combination of an organic and an inorganic phosphor is mentioned. However, this phosphor combination only provides limited UV stability. Alternatively, the direct introduction of inorganic, less stable feature substances such as silver or copper / cerium-doped zinc sulfide is proposed in the pulp. However, these substances are typically destroyed only at temperatures of about 700 ° C, which does not provide reliable ashing protection. Similarly, wet-chemical attacks to extract the feature substance can not be prevented with this approach.
The EP 1 863 651 B1 describes a feature system with two luminescent substances, where radiative energy transmission through emission and reabsorption link the two features. In this case, the first feature substance is embedded in the paper or polymer and is destroyed at high temperatures, in particular when the value document is burned. With regard to the temperature-sensitive feature substance based on organic luminescent substances, no alternatives are shown. However, organic luminescent substances offer only limited UV stability. Similarly, wet-chemical attacks to extract the feature substance can not be prevented with this approach.

The patent document DE 10 2007 044482 A1 discloses a security element for bonding to a substrate, the security element having a layer structure and anti-tamper means ensuring that the security element is no longer removable from the substrate without altering the security element and / or substrate after adhering to the substrate. The object of the invention is to provide a security element which is improved with respect to the security against forgery and a security document or security paper provided with such a security element. Another object is to provide a reference to the counterfeit security improved Wertdocumentsubstrats.

This object is achieved by the feature combinations defined in the main claims. Preferred embodiments are subject of the dependent claims.

Summary of the invention

1. 1. (First aspect of the invention) A film-like security element for bonding to a substrate, such as a security paper, a value document or another valuable item, wherein the security element has at least one bonding surface, which is coated with at least one adhesive layer, and the adhesive of the at least one adhesive layer contains an inorganic chemically unstable feature substance and the adhesive is suitable for the unstable feature substance after three-dimensional crosslinking of the adhesive against harmful environmental influences, especially against moisture and / or oxygen and / or solvents and / or acids and / or bases and / or oxidizing agents and / or stabilizing reducing agent, wherein the inorganic chemically unstable feature substance is a luminescent substance, a SERS active substance or an NIR absorber.
2. 2. (Preferred Embodiment) The security element according to 1, wherein the adhesive of the at least one adhesive layer is a heat-, water- or UV-crosslinking adhesive, in particular polyurethane-based, acrylate-based or epoxy-based.
3. 3. (Preferred Embodiment) The security element according to 1 or 2, wherein the inorganic chemically unstable feature substance is unstable to aqueous solutions of acids and / or bases and the instability against aqueous solutions of acids and bases according to the following tests (a) and (b) is defined:
   • Test (a) relating to a feature substance that is unstable to aqueous solutions of acids: a paper substrate containing the feature substance or coated with the feature substance is immersed for 40 minutes at room temperature in a 0.5 molar hydrochloric acid solution, wherein at least 90%, preferably at least 99% of the feature signal or the feature intensity must be lost;
   • Test (b) relating to a feature substance unstable to aqueous solutions of bases: a paper substrate containing the feature substance or coated with the feature substance is immersed in a 0.5 molar NaOH solution for 40 minutes at room temperature, whereby at least 90 %, preferably at least 99% of the feature signal or the feature intensity must be lost.
4. 4. (Preferred Embodiment) A security element according to any of 1 to 3, wherein the inorganic chemically unstable feature substance is a luminescent substance that is unstable to moisture and instability to moisture is defined by contacting the substance with demineralized water for a period of time 1 hour at room temperature, a signal loss of the original luminescence emission by more than 40%, preferably more than 80% occurs.
5. 5. (Preferred Embodiment) The security element according to one of 1 to 4, wherein the inorganic chemically unstable feature substance is in particulate form.
6. 6. (Preferred Embodiment) A security element according to 5, wherein the chemically unstable feature substance is an inorganic luminescent substance and in particular based on a host lattice doped with rare earth ions or with transition metal ions.
7. 7. (Preferred Embodiment) The security element of any one of 1 to 6, wherein the chemically unstable feature substance has a coating with a destabilizing reagent.
8. 8. (Preferred embodiment) A security element according to one of 1 to 7, wherein the grain size D90, in particular D99 of the chemically unstable feature substance-forming feature substance particles is smaller than the thickness of the at least one adhesive layer.
9. 9. (Preferred Embodiment) The security element according to one of 1 to 8, wherein the at least one bonding surface on the side opposite the security element layer structure has a release film.
10. 10. (Preferred embodiment) A security element according to one of 1 to 9, wherein the security element, either full or partial, has a diffractive or a refractive structure, in particular a hologram, an effect layer based on interference pigments or liquid crystal pigments, a layer sequence with a color shift effect, e.g. a reflector / dielectric / absorber layer structure, or a micro-optical representation arrangement, preferably a moiré or a modulo magnification arrangement, in particular with microfocusing elements and micromotif elements.
11. 11. (Second aspect of the invention) value-document substrate for the production of value documents, in particular banknotes, comprising at least one Carrier layer and a first cover layer, wherein the first cover layer is a film layer and the carrier layer comprises a paper layer or a foil layer and the carrier layer is connected to the first cover layer by at least one adhesive layer and the adhesive of the at least one adhesive layer contains a chemically unstable inorganic feature substance and this stabilized by the three-dimensional crosslinking of the adhesive against harmful environmental influences, especially against moisture and / or oxygen and / or solvents and / or acids and / or bases and / or oxidizing agents and / or reducing agents, wherein the inorganic chemically unstable feature substance is a luminescent substance, SERS active or an NIR absorber.
12. 12. (Preferred embodiment) value-document substrate according to the second aspect, which in addition to the at least one carrier layer and the first cover layer still comprises a second cover layer, wherein the second cover layer is a film layer and the carrier layer with the first cover layer and with the second cover layer is in each case connected by at least one adhesive layer and the adhesive of the at least one adhesive layer contains a chemically unstable inorganic feature substance and this by the three-dimensional crosslinking of the adhesive against harmful environmental influences, especially against moisture and / or oxygen and / or solvents and / or acids and / or Stabilized bases and / or oxidants and / or reducing agents.
13. 13. (Preferred embodiment) Value-document substrate according to 12, wherein the adhesive of the at least one adhesive layer is based on a heat-, water- or UV-crosslinking adhesive, in particular polyurethane-based, acrylate-based or epoxy-based.
14. 14. (Preferred Embodiment) Value document substrate according to one of 12 or 13, wherein the chemically unstable feature substance is unstable to aqueous solutions of acids and / or bases and the instability to aqueous solutions of acids and bases according to the following tests (a) and (b) is defined:
    • Test (a) relating to a feature substance that is unstable to aqueous solutions of acids: a paper substrate containing the feature substance or coated with the feature substance is immersed for 40 minutes at room temperature in a 0.5 molar hydrochloric acid solution, wherein at least 90%, preferably at least 99% of the feature signal or the feature intensity must be lost;
    • Test (b) relating to a feature substance unstable to aqueous solutions of bases: a paper substrate containing the feature substance or coated with the feature substance is immersed in a 0.5 molar NaOH solution for 40 minutes at room temperature, whereby at least 90 %, preferably at least 99% of the feature signal or the feature intensity must be lost.
15. 15. (Preferred Embodiment) The value-document substrate of any one of 12 to 14, wherein the inorganic chemically-unstable feature substance is a luminescent substance that is unstable to moisture and instability to moisture is defined by contacting the substance with demineralized water during For a period of 1 hour at room temperature, a signal loss of the original luminescence emission by more than 40%, preferably more than 80% occurs.
16. 16. (Preferred Embodiment) Value document substrate according to one of 12 to 15, wherein the chemically unstable feature substance is a luminescent Fabric, a magnetic substance, a SERS active substance or an NIR absorber.
17. 17. (Preferred Embodiment) A value-document substrate according to any one of 12 to 16, wherein the chemically-unstable feature substance is an inorganic luminescent substance and is based, in particular, on a host lattice doped with rare-earth ions or with transition-metal ions.
18. 18. (Preferred Embodiment) Value document substrate according to one of 12 to 17, wherein the grain size D90 of the feature substance particles forming the chemically unstable feature substance is smaller than the thickness of the at least one adhesive layer.
19. 19. (Preferred Embodiment) The value-document substrate of any one of 12 to 18, wherein the at least one adhesive layer has two portions each containing a first unstable feature substance and a second unstable feature substance respectively, wherein the first feature substance and the second feature substance are different Distinguish excitation wavelengths and / or their emission wavelengths and form the two subregions of the adhesive layer in this way an encoding.
20. 20. (Preferred Embodiment) A value-document substrate according to one of 12 to 18, wherein the at least one adhesive layer has two portions each containing a first unstable feature substance and a second stable feature substance respectively, wherein the first feature substance and the second feature substance are different Distinguish excitation wavelengths and / or their emission wavelengths and form the two subregions of the adhesive layer in this way an encoding.
21. 21. (Third aspect of the invention) Security paper for producing value documents, or value document, comprising the security element of any one of FIGS. 1 to 9 disposed on a security paper substrate or value document substrate, wherein the at least one adhesive layer containing the chemically unstable inorganic feature substance is three-dimensional is crosslinked and stabilizes the feature substance in this way against harmful environmental influences, especially against moisture, solvents, acids or bases.
22. 22. (Preferred Embodiment) A security paper or value document according to 21, wherein the substrate of the security paper or the value document is a plastic substrate, a paper substrate, a substrate having both paper components and plastic components, or a film / paper / film composite.
23. 23 (fourth aspect of the invention) value document, in particular a banknote, comprising a value-document substrate according to one of the 10 to 20.
24. 24. (Fifth aspect of the invention) A process for producing a security paper or a value document according to 21 or 22, comprising the step of providing a security paper substrate or a value-document substrate with the security element according to any of the claims 1 to 9.
25. 25. (Sixth aspect of the invention) A transfer tape comprising a plurality of security elements on a substrate, such as a security paper, a value document or another valuable article, for transferring security elements according to any one of claims 1 to 9.
26. 26. (Seventh aspect of the invention) Use of the security element according to one of the FIGS. 1 to 9 for product security of goods of any kind.

Detailed description of the invention

Value documents within the scope of the invention are items such as banknotes, checks, stocks, tokens, identity cards, passports, credit cards, documents and other documents, labels, seals, and items to be protected, such as jewelery, cosmetics, CDs, packaging, bottles, bottles and the like , The value document substrate does not necessarily have to be a paper substrate, it could in particular be a plastic substrate or a substrate having both paper components and plastic components.
The use of a substance as a banknote security feature requires a degree of chemical stability to certain environmental influences, for example to moisture, acids, bases and / or organic solvents. If a substance does not fulfill the required requirements, it is normally not used. The substance is either replaced by an equivalent stable substance, or the substance is modified to increase its chemical stability by a special process, for example by coating with a protective layer (see, eg DE 10 2004 063 217 A1 and DE 10 2009 056 634 A1 ).
In the present invention, specifically chemically unstable substances are used as feature substances. Unlike chemically stable substances, the in The materials used in the present invention are not applied as usual in the paper substrate of the banknote or in printing inks applied to the banknote surface, since in this case adequate protection from harmful environmental influences is not ensured. However, it is possible to incorporate these unstable materials in layers of adhesive that bond two layers of a document of value, with the layers independently selected from polymer or paper. The two layers can each form a substrate layer of the value document. Alternatively, one layer forms the substrate layer of the value document substrate and the second layer is the film of a film security element applied to the value document substrate.

Instead of the term polymer, the terms plastic or film are used in the present description. The terms polymer layer (or polymer layer), plastic layer (or plastic layer) and film layer (or film layer) are synonymous.

Theoretically, a protective effect against environmental influences can also be achieved by embedding the chemically unstable substance in a polymer substrate, for example the polymer substrate of a polymer banknote. Polymer substrates are generally based on uncrosslinked thermoplastic polymers into which the feature substances are introduced, for example, by melting or dissolving the polymer, by mixing with the feature substance and renewed hardening or precipitation of the polymer now containing the feature substance. However, these processes are easily reversed so that the feature substances are separated under relatively mild conditions by remelting or dissolving the polymer and are available to the counterfeiter for analysis or use in counterfeiting. Thermoplastic systems, such as polymer bank note substrates or so-called Hot-melt adhesives that are already fully polymerized and do not form a linked network of chains are therefore less suitable and not preferred.

According to the present invention, adhesives are used which still have to polymerize completely, in which case at least in part a linking of the individual polymer chains can take place. As a result, the individual polymer chains are three-dimensionally crosslinked with each other, whereby it is no longer possible to melt or dissolve the adhesive layer without destroying the binding sites. Suitable adhesive systems include, for example, typical heat, water or UV crosslinking adhesives, e.g. polyurethane-based, acrylate-based or epoxy-based. Unsuitable are non-crosslinking thermoplastic systems and solvent-based wet adhesives. Furthermore, water-crosslinking adhesives are only suitable for water-resistant feature substances. The feature substance previously introduced into the liquid adhesive is thus enveloped by the adhesive in a manner such that removal of the feature substance without prior chemical destruction of the polymer chains of the adhesive is rendered impossible. However, the conditions for such disruption of the linked polymer network are very aggressive and include, for example, the burning of the banknote or the breaking of certain bonds by chemicals, e.g. the saponification of urethane groups in polyurethanes under strongly basic conditions, or the oxidative degradation of organic material by Fentons reagent.

• Figur 1 zeigt eine Verbundbanknote (1) mit einem Folie (2)/Papier (3)/Folie (2)-Schichtaufbau mit einer sich ausbildenden Quellfront während eines Angriffs einer destabilisierenden Flüssigkeit auf einen nicht vor einem Aufquellen schützenden Kleber (4).
• Figur 2 zeigt ein Beispiel einer Hybridbanknote (5) (d.h. eine Folie(2)/Papier(3)/Folie(2)-Verbundbanknote), bei der sich im Zuge eines Angriffs einer destabilisierenden Flüssigkeit auf einen vor einem Aufquellen schützenden Kleber (4) keine Quellfront ausbildet.

In one embodiment, the adhesive system of the present invention effectively prevents, in the event of attack of destabilizing liquids, eg, petroleum ethers or an aromatic hydrocarbon-based solvent, forming a swelling front with penetrating destabilizing liquids Liquid. This reliably prevents soluble feature substances from being destroyed by the attacking liquid or from being extracted by such liquids. (please refer Figures 1 and 2 )

• FIG. 1 FIG. 5 shows a composite banknote (1) having a foil (2) / paper (3) / foil (2) layer construction with a forming source front during attack of a destabilizing liquid on a non-swelling adhesive (4).
• FIG. 2 shows an example of a hybrid banknote (5) (ie, a foil (2) / paper (3) / foil (2) composite banknote) in which no attack on a swelling protective adhesive (4) occurs as a result of attack by a destabilizing liquid Quellfront trains.

Even if a counterfeiter would receive the inorganic constituents (eg banknotes ash of a banknote containing the fillers, printing inks and other materials) in an enriched form, it would not be possible for him to separate or concentrate the feature substance therefrom, since the processing steps (eg Treating with acids, bases, flotation, etc.) would destroy especially the feature substance. This makes it difficult for the counterfeiter to obtain an amount of the feature substance sufficient for the analysis or production of forgeries. Furthermore, a feature substance obtained in this way would be misused, e.g. in printing inks, in the paper substrate, or by environmental influences are rapidly decomposed.

Furthermore, the instability of the feature substance may also serve as a so-called "fitness indicator" to provide information about the condition of the patient circulating value document, eg a banknote. For example, a value document may be provided with microcracks at the location of the feature substance in order to allow the penetration of moisture into the adhesive layer, so that the feature substance is partially decomposed in this way.

The inorganic feature substances are preferably present in particulate form. Technically, incorporation of inorganic feature substance particles into adhesives is significantly easier compared to incorporation of feature substance particles into banknote substrates of polymeric material. For example, the introduction of the feature substance particles by stirring into a liquid component of a two-component adhesive can be carried out with the aid of a dissolver disk. Similarly, the technical complexity compared to a coating of the feature substance particles is significantly lower. The introduction into adhesive layers is therefore particularly advantageous for chemically unstable feature substances.

The chemically unstable inorganic feature substances may be e.g. based on photoluminescent or electroluminescent substances, magnetic substances, Surface Enhanced Raman (SERS) active particles or on NIR absorbers.

It is preferable to use chemically unstable inorganic luminescent substances, in particular based on rare earth ions or host metal lattices doped with transition metal ions.

In one embodiment, luminescent chemically unstable feature substances are used in a non-visible wavelength range, preferably in the IR.

The term "chemically unstable" means that the feature substance is outside the protective adhesive matrix, i. as a usual security feature present within the paper or as a security feature, which is in the form of a print layer applied to the paper, is not banknote suitable. In particular, it is meant that a check of the feature characteristics in a bill containing the unprotected feature substance does not meet the usual stability criteria of banknote tests, e.g. Stability to moisture, acids, bases, solvents, oxygen or detergents.

Preferably, the feature substance is unstable to aqueous solutions of acids and / or bases.

A feature substance that is unstable to aqueous solutions of acids can be defined according to the following test:
A paper substrate containing the feature substance or coated with the feature substance is immersed in a 0.5 molar hydrochloric acid solution for 40 minutes, whereby at least 90%, preferably at least 99% of the feature signal (or feature intensity) must be lost. Preferably, the feature substance loses over 90%, more preferably over 99%, of its feature intensity upon 40-minute contact of the paper substrate with a solution having a pH <1, preferably having a pH <2, more preferably having a pH <4.

A feature substance that is unstable to aqueous solutions of bases can be defined according to the following test:
A paper substrate containing the feature substance or coated with the feature substance is immersed for 40 minutes in a 0.5 molar NaOH solution, wherein at least 90%, preferably at least 99% of the feature signal (or the feature intensity) must be lost. Preferably, the feature substance loses over 90%, more preferably over 99%, of its feature intensity upon contact of the paper substrate for 40 minutes with a solution of pH> 13, preferably pH> 12, more preferably pH> 10.

Other possible stability criteria include, for example, the test environments defined in DIN ISO 12757-2 for ballpoint pen refills.
It is preferred that the feature substance be water-soluble. The water solubility (at 20 ° C) is preferably more than 2 mg per liter of water, more preferably more than 200 mg per liter of water, and most preferably more than 20,000 mg per liter of water.

With such solubilities, for example, it is no longer possible to meaningfully add luminescent feature substances during papermaking. These substances are usually added in the range of a few Gewichtsspromille relative to the pulp and would thus completely or largely dissolve in the water of the paper machine.

It should be noted that most unstable compounds have an increased solubility in water, acids or bases, but it is sufficient for the purposes of the invention if the corresponding feature signal is irreversibly changed or destroyed by the contact with the respective medium. In certain cases, this can also take place without dissolution of the feature substance, for example by conversion of the crystal phase of the feature substance, by addition of water of crystallization, by exchange of anions or by oxidation or reduction of the dopant.

In the case of an inorganic luminescent substance based on a doped host lattice (or on a doped matrix), the host lattice preferably consists of combinations of inorganic cations and anions. Carbonates CO ₃ ^2- , bicarbonates HCO ₃ ^- , cyanides CN ^- , cyanates OCN ^- , thiocyanates SCN ^- and carbides (eg C ^4- , C ₂ ^2- , etc.) are the only carbon-containing compounds, as is generally customary , also as inorganic compounds, while the remaining carbon-containing compounds, such as formates HCO ₂ ^- or oxalates C ₂ O ₄ ^2- etc., as generally customary, are counted among the organic compounds.

Suitable host lattices are in particular compounds which contain exclusively alkali metals and / or alkaline earth metals as cations, since these have only weak interactions with the crystal lattice because of their low charge and are therefore easily dissolved out. Also suitable are compounds containing ammonium cations. Examples of this first class of compounds for forming the feature substance are sodium molybdate Na ₂ MoO ₄ , sodium stannate Na ₂ SnO ₃ and strontium carbonate SrCO ₃ .

It should be noted that there are several exceptions. For example, certain niobates of the alkali and alkaline earth metals are extremely stable and therefore not suitable for the purposes of the invention.

Typical suitable anions, which generally form readily soluble or chemically unstable compounds, are the anions or anionic oxide compounds of the fifth to seventh series of the periodic table, ie the nitrogen group, chalcogenides and halides, in particular the nitrates, phosphates, and sulfates , Furthermore, preferred as halides Chlorides, bromides and iodides used because pure fluoride salts often have particularly high stabilities and are therefore less preferred. However, suitable unstable fluoride compounds are often available by combination with other, larger anions. Furthermore, carbonates CO ₃ ^{2- are} suitable. For example, different oxidation states (eg nitrate NO ₃ ^- / nitrite NO ₂ ^- ) or other more complex modifications are possible (eg sulfate SO ₄ ^2- / thiosulfate S ₂ O ₃ ^2- / disulfate S ₂ O ₇ ^2- ). Often mixed forms can be formed with oxides (oxide sulfates, oxide bromides, etc.) or protonated forms (eg, carbonate / bicarbonate), which are also unstable. Certain compounds are also soluble or unstable as a complete oxide, eg, boron oxide B ₂ O ₃ .

Examples of the second class of compounds for forming the feature substance are manganese (II) carbonate MnCO ₃ , lanthanum sulfate La ₂ (SO ₄ ) ₃ , silver phosphate Ag ₃ PO ₄ and triyttrium oxide heptachloride Y ₃ OCl ₇ .

It should be noted that there are several exceptions. For example, rare earth phosphates are generally extremely stable and therefore not suitable for the purposes of the invention.

The compounds for forming the feature substance are particularly preferably combinations of the cations of alkali metals and / or alkaline earth metals and anions which are selected from the group consisting of nitrate, nitrite, phosphate, phosphite, arsenate, sulfate, sulfite, sulfide, chloride, Bromide, oxide, hydroxide and carbonate are selected. In this case, in particular, mixed forms with a plurality of different of the abovementioned cations and / or anions can also be formed. Examples of this third, particularly preferred class of compounds for forming the feature substance are lithium chloride LiCl, sodium carbonate Na ₂ CO ₃ , potassium sulfate K ₂ SO ₄ , magnesium phosphate fluoride Mg ₂ PO ₄ F and calcium arsenate hydroxide Ca ₅ (AsO ₄ ) ₃ OH.

The dopants (or doped ions) are selected from the group consisting of rare earth metals and transition metals. While rare earth cations generally maintain the +3 oxidation state relatively stable (eg, Nd ³⁺ , but with known exceptions, eg, Eu ^{2 + / 3 +} , Ce ^{3 + / 4 +} , etc.), transition metals can easily change their oxidation states and therefore react particularly sensitive to environmental influences, since they are stable only within certain pH values on contact with aqueous solutions and otherwise decompose (eg, Fe ⁶⁺ is relatively stable only in strongly basic solutions). Suitable host lattices with luminescent centers (ie dopants) based on transition metals therefore react particularly sensitively to environmental influences such as moisture, acids or bases and oxidizing or reducing agents. The dopant is therefore preferably a transition metal cation, in particular a transition metal cation that is luminescent in the NIR range.

According to a special embodiment of the invention, the luminescence of the feature substance is not simply reduced or extinguished by environmental influences, but a change in the matrix or the dopant causes a spectral change in the luminescence signal which can be detected. For example, (a) the luminescence signal can change its spectral shape, eg broadened or change the ratio of individual luminescence bands to one another; or (b) the luminescence signal can change its spectral position, for example by changing the wavelengths of individual bands, or by replacing a luminescence signal with a new luminescence signal in another wavelength range; or (c) the luminescent signal may become more optical with respect to other Change properties, for example in its cooldown or its excitation spectrum.

For example, a "first" unstable feature substance, which is based on a host lattice doped with europium (II) cations and luminesces in the green spectral range, may be exposed after contact with environmental influences, e.g. Convert acids into a second feature substance, which now contains europium (III) cations due to its altered structure and luminesces in the red spectral region.

According to another embodiment, unstable feature substances could be partially stabilized, i. they are e.g. Although increased in their stability by a faulty, thin or permeable surface coating, however, they are still insufficiently stable for use outside a protective adhesive layer.

According to a further embodiment, suitable instable feature substances can also be obtained by providing feature substances by suitable mixing, agglomeration or coating with destabilizing reagents. For example, such an acid-labile but actually water-stable luminescent substance, e.g. Ca3Mg3 (PO4) 4: Eu2 + by coating with e.g. Tartaric acid can also be made sensitive to water.

With regard to the incorporation of the feature substance in the value document, the (not yet stabilized) feature substance can be introduced directly into an adhesive which, for example, connects two layers of the value document substrate. Alternatively, an adhesive containing the feature substance can be applied in a separate application process (eg by hot stamping, thermal transfer printing, laser printing or doctor blade method) on a separate film, in particular on a film-based security element, are applied, wherein the film is later connected by means of the applied adhesive layer with the value document such as a banknote. Film-based security elements are also referred to hereafter as foil-type security elements or film security elements. They may be in the form of a label, a patch or a strip, for example.

In general, the unstable feature particles contained in the adhesive are protected from environmental influences by the cross-linked adhesive layer that envelops them. An additional protective effect is provided by the polymer and / or paper layers bonded by the adhesive on one or both sides (eg by the individual polymer layers forming the value document substrate and connected by an adhesive layer; alternatively, a (particularly central) paper layer of a value document substrate on its front Furthermore, on an outer polymer layer of a value document substrate, a film-based security element may be applied by means of an adhesive layer.

According to a preferred embodiment, the adhesive loaded with one or more feature substances can be applied over the entire value document or the entire banknote over the entire surface in order to bond the substrate layers forming the value document substrate over the entire area. In the case of a value document substrate based on a film / paper / film composite with adhesive layers at the interfaces between the central paper layer and the two outer films, it is advantageous to use further adhesion or moisture barrier layers with or without Provide feature loading between the paper core and the feature-loaded adhesive layer.

According to a further embodiment, film security elements are attached to a value document substrate by means of an adhesive layer, eg to produce a see-through window above a (paper) banknote provided with an opening. Here, too, the additional protective effect of the outer, the window forming polymer layers is given. The closing of an opening in the value document substrate with film security elements allows several variants with regard to the nature of the opening and the film security elements used. For example, an opening can be closed both from the front side and from the rear side by a respective film security element, wherein each film security element has an adhesive layer and the opening as such is substantially unfilled, ie essentially filled with air. Alternatively, the adhesive can also be present in the opening itself, ie the opening is completely or only partially filled by the adhesive. According to a further alternative, the opening is closed only by one of the two film security elements and the second film security element has a congruent with the opening of the value document substrate opening. Value documents with a substrate having an opening, wherein the opening is closed on the front side with a film security element and the back side of the substrate is provided with a further film security element, wherein the further film security element has a congruent with the opening of the substrate opening, for example, from WO 2011/015622 A1 known.

Likewise, according to a further embodiment, the embedding of the chemically unstable feature substance in (in particular at least partially metallized and / or with micro-optical elements provided) foil security elements conceivable by the feature substance having the adhesive either different layers within the layer structure of the security element glued together, or glued the foil security element as a whole with the value document substrate.

In principle, the unstable feature substance introduced into an adhesive and stabilized in this way need not necessarily be distributed homogeneously in the adhesive, but it can also be present in (intensity) modulated form along the adhesive layer. Such a modulation can in particular generate a coding. The modulation can e.g. be accomplished by a suitable adhesive pattern, i. the adhesive containing the feature substance is not in the form of a full-surface layer, but in the form of a pattern with partial regions (in particular a strip-like, linear, punctiform pattern, a pattern in the form of characters or other geometric elements). Alternatively, a modulation can be accomplished by having a full-surface adhesive layer, but the unstable feature substance is present only in partial areas of the adhesive layer, to form a pattern in this way (in particular a strip-shaped, linear, punctiform pattern, a pattern shape in the form of Characters or other geometric elements).

Instead of the above-described feature substance modulation (which in particular forms an encoding) produced by means of the adhesive pattern, a modulation can also be accomplished by modulating the application thickness of the adhesive layer. For example, the adhesive layer may contain first and second (and possibly also third, fourth and further) application areas, wherein the individual types of the application areas differ with respect to the application thickness of the adhesive containing the feature substance.

When using a multi-component feature system (i.e., different feature substances), separate incorporation may occur depending on the stability. For example, a combination of a stable feature substance and an unstable feature substance can be used, wherein the stable feature substance is applied in or on the (paper) substrate layer of a value document and the unstable feature substance is incorporated into the adhesive layer. Alternatively, both feature substances, regardless of their stability, can be incorporated into the adhesive layer. Both the unstable feature substance and the stable feature substance can be present independently of one another in modulated form, in particular in the form of a pattern, and in particular form an encoding. The modulation can, as described above, be accomplished in particular by the adhesive pattern or by a modulated application thickness of the adhesive.

In general, the particle size of the feature substance particles is preferably smaller, in particular preferably significantly smaller than the dimensions (ie thickness) of the adhesive layer, so that the feature substance particles can be completely embedded in the adhesive layer and this can exert a particularly advantageous protective effect on the feature substance particles. In general, a sufficient protective effect is achieved when 90% of the feature substance particles are smaller than the thickness of the adhesive layer. In other words, the particle size D90 of the feature substance particles is preferably smaller than the thickness of the adhesive layer, more preferably less than 75% of the thickness of the adhesive layer, particularly preferably less than 50% of the thickness of the adhesive layer. Particularly preferably, the particle size D99 of the feature substance particles is smaller than the thickness of the adhesive layer preferably less than 75% of the thickness of the adhesive layer, particularly preferably less than 50% of the thickness of the adhesive layer.

The particle sizes D90 and D99 of the particles are determined using a substance-specific suitable method such as. a laser scattered light spectrometer based on the static laser light scattering according to DIN / ISO 13320 or determined microscopically and describes the particle diameter for which 90% and 99% of all particles have a smaller volume.

With a suitable design of the toughness, surface tension and curing time of the adhesive, it is also possible for characteristic substance particles larger than the average layer thickness of the adhesive to be reliably bound and sealed if a continuous adhesive layer of sufficient thickness is formed around the particles.

Typical application rates for bonding adhesive layers between individual layers of a value document, such as a banknote, are in a range of 5 to 10 g / m ² . Given an assumed density of the adhesive system with a value of 1200 kg / m ³ , typical layer thicknesses are therefore in the range of 4 to 8 μm.

The feature substance is contained in the adhesive preferably with up to 20 weight percent, more preferably with 0.01 to 2 weight percent.

FIG. 3 shows an inventive example of a value document (6), in the example a polymer banknote. The banknote substrate is formed by two BOPP films (7), which are glued together with an adhesive layer (8) containing the feature substance. In the received document of value (6) In addition, the outside of both BOPP films (7) can be equipped with a pressure-receiving layer (9).

FIG. 4 shows a further inventive example of a value document (10), in the example a banknote. The banknote substrate is formed by a foil (11) / paper (12) / foil (11) composite, wherein the paper core (12) is provided with a film (13) containing the feature substance at its front side and on its back side ( 11) is glued. In the obtained value document (10), the outside of both films (11) can additionally be equipped with a pressure-accepting layer (not shown in the figure). In another embodiment, only one of the two adhesive layers may be loaded with the feature substance.

Basically, the adhesive layer containing the feature substance need not be the only adhesive layer in the value document substrate. For example, an adhesive layer bonding together two substrate layers (each based on polymer and / or paper) of the value document substrate may be in the form of a three-layered adhesive layer structure, wherein the central adhesive layer contains the feature substance and the two outer adhesive layers surrounding the central adhesive layer do not Have feature substance. In this way, an improved bonding of the substrate layers and an improved sealing of the feature substance against harmful environmental influences can be achieved. The surrounding adhesive layers may have the same composition as the central adhesive layer. In another embodiment, the surrounding adhesive layers may each have a different composition with specifically optimized properties such as flexibility, substrate adhesion, etc. than the central adhesive layer.

Fig. 5 shows a schematic representation of a security element (14) according to the invention with a layer structure of a film, a functional layer and any auxiliary layers, the layer structure is summarized by the reference numeral (15). The security element (14) has a surface (16) intended for bonding to a security paper or document of value or another valuable object. The surface (16) has an adhesive layer (17) containing the unstable feature substance and not three-dimensionally (fully) crosslinked. The layer structure (15) of the security element may include, for example, a diffractive or a refractive structure, in particular a hologram, an effect layer based on interference pigments or liquid crystal pigments or a reflector / dielectric / absorber layer structure. The layer structure (15) may further comprise a micro-optical representation arrangement, preferably a moiré or a modulo magnification arrangement with microfocusing elements and micromotif elements.

That in the Fig. 5 shown security element (14) may have on the layer structure (15) opposite side of the adhesive layer (17) an optional release film. The release film is peeled off the adhesive layer (17) before applying the security element (14) to a value document substrate.

Furthermore, that in the Fig. 5 be shown security element as a transfer element together with other transfer elements on a present example as an endless belt transfer belt.

The adhesive layer (17) of the in Fig. 5 shown security elements may additionally be equipped with special antiblocking agents that prevent premature, unwanted sticking of the security element. The antiblocking agents can be deactivated in terms of their antiblocking properties by heat, radiation and / or by mechanical action (see, for example, those in the EP 2 202 087 A2 described antiblocking agent).

Fig. 6 shows a schematic cross-sectional view of a security paper or value document, with the security element of Fig. 5 Is provided. The security paper substrate or document of value substrate (18) is based, for example, on paper, on a film or is part of a film / paper / film composite.

Fig. 7 shows a schematic cross-sectional view of a security paper or document of value (19) with a substrate layer (20) (in the example a paper layer), which is provided with an opening (21). The opening (21) of the substrate (20) is closed from the top with a first film security element (22). The first film security element (22) is applied to the upper side of the substrate layer (20) by means of a crosslinked adhesive layer (23) containing a first unstable feature substance. On the underside of the substrate layer (20) there is a second film security element (24) which has an opening which is congruent with the opening (21) of the substrate layer. The second film security element (24) is applied to the underside of the substrate layer (20) by means of a crosslinked adhesive layer (25) containing a second unstable feature substance.

The in the FIG. 7 shown foil security elements (22, 24) may have the same dimensions as the substrate (20) in terms of length and width. Alternatively, the film security elements (22, 24) may independently have smaller dimensions than the substrate (20) and may be in the form of a patch, label, strip, or thread, for example.

Furthermore, the one described above, in the FIG. 7 in that only one of the two adhesive layers (23, 25) has an unstable feature substance and the other adhesive layer has either no feature substance or a conventional, stable feature substance.

In addition, the substrate layer (20) in the FIG. 7 also be formed from a polymer.

Fig. 8 shows a schematic cross-sectional view of another security paper or document of value (26) with a substrate layer (27) (in the example a paper layer), which is provided with an opening (28). The opening (28) of the substrate (27) is closed from the top with a first film security element (29). The first film security element (29) is applied to the upper side of the substrate layer (27) by means of a crosslinked adhesive layer (30) containing a first unstable feature substance. In addition, the opening (28) of the substrate (27) is also closed from the underside with a second film security element (31). The second film security element (31) is applied to the underside of the substrate layer (27) by means of a crosslinked adhesive layer (32) containing a second unstable feature substance. As such, the opening (28) of the substrate layer (27) is substantially unfilled (ie, the opening (28) is substantially filled with air).

According to a variant of the in the FIG. 8 In the embodiment shown, adhesive can also be present in the opening (28), ie the opening (28) is completely or only partially filled with adhesive. As an adhesive here can the crosslinked, an unstable feature substance-containing adhesive the adhesive layer (30) or the adhesive layer (32) serve. Alternatively, however, the opening may also be filled up by means of an adhesive which contains either no feature substance or a conventional, stable feature substance. Alternatively, however, the opening may also be filled up by means of an adhesive containing one or more further unstable and / or conventional stable feature substances.

The in the FIG. 8 shown film security elements (29, 31) may have the same dimensions as the substrate (27) in terms of length and width. Alternatively, the film security elements (29, 31) may independently have smaller dimensions than the substrate (27) and be in the form of a patch, label, strip or thread, for example.

Furthermore, the one described above, in the FIG. 8 in that only one of the two adhesive layers (30, 32) has an unstable feature substance and the other adhesive layer has either no feature substance or a conventional, stable feature substance.

In addition, the substrate layer (27) in the FIG. 8 also be formed from a polymer.

As described above, in particular a feature system or feature substance system based on a plurality of components (ie on different feature substances) can be used. It can be done depending on the stability of a separate contribution. For example, the stable feature substances in or on the (paper) substrate layer of a value document or security paper applied and incorporated only the unstable feature substances in the adhesive layer. Alternatively, all feature substances, regardless of their stability, can be incorporated into the adhesive layer.

Fig. 9 shows a cross-linked, two different unstable feature substances containing adhesive layer in plan view. The adhesive layer has first regions (33) and second regions (34), wherein the first regions (33) contain the first unstable feature substance and the second regions (34) contain the second unstable feature substance. The first and second regions (33, 34) form an encoding.

When in the FIG. 9 shown adhesive layer may be, for example, the adhesive layer (8) in the FIG. 3 to one of the two adhesive layers (13) in the FIG. 4 to one of the two adhesive layers (23, 25) of the FIG. 7 or one of the two adhesive layers (30, 32) of FIG. 8 act.

According to a variant to that in the FIG. 9 In the embodiment shown, the adhesive layer contains an unstable feature substance only in the first regions (33). The second regions (34) contain either no, or a conventional, stable feature substance.

According to a variant to that in the FIG. 9 As shown, the crosslinked adhesive layer contains the same unstable feature substance in both the first regions (33) and the regions (34). However, the first regions (33) have a different application thickness of the adhesive layer compared to the second regions (34), which leads to an (intensity) modulation of the feature signal.

The invention will be clarified below with reference to specific embodiments. The percentages are by weight unless otherwise stated.

Example 1 (relates to the first class of compounds for the formation of the feature substance)

As luminescent feature substance in the infrared spectral range, a 0.05% FeO ₄ ^2- doped potassium chromate K ₂ CrO ₄ of grain size D99 = 3 microns is used, which upon excitation with radiation having a wavelength in the range of 900 to 1000 nm sharp luminescence emission at 1610 nm.

The feature substance is incorporated into a polyurethane-based UV-curing adhesive (proportion: 1 weight percent). The adhesive thus obtained is used at an application thickness of 8 g / m ^{2 to} bond two PET films (PET = polyethylene terephthalate) together to form a value document substrate.

The used (non-stabilized) feature substance decomposes on contact with water (solubility> 600000 mg / l) and the matrix-stabilized cation Fe ⁶⁺ used as dopant is also unstable in an aqueous environment and decomposes rapidly to form Fe ³⁺ .

Destruction of the adhesive layer of the document of value, in particular by wet-chemical methods (for example saponification, acid cleavage, oxidative / reductive decomposition) is therefore without simultaneous destruction of the Feature not possible. Similarly, combustion of the value document and subsequent digestion of the ash, for example via flotation, sedimentation or treatment with aqueous solutions, without simultaneous destruction of the feature is not possible.

Example 2 (concerns the second class of compounds for the formation of the feature substance )

As a luminescent feature substance in the infrared spectral range, an yttrium iodate α-Y (IO ₃ ) ₃ of grain size D99 = 2 μm doped with 1% Nd ^{3+ is} used, which upon excitation with a radiation having a wavelength of 750 nm luminescence emission in the form of several bands ranging from 1050 to 1090 nm.

The feature substance is incorporated in a polyurethane-based, water-curing adhesive (proportion: 1 percent by weight). The adhesive thus obtained is used at an application thickness of 8 g / m ² to bond a BOPP film (biaxially oriented polypropylene) and a paper sheet to form a value document substrate.

The named feature substance reacts sensitively to aqueous environments (solubility> 10000 mg / l), especially in the presence of acids, bases or reducing agents.

Destruction of the adhesive layer of the value document, in particular by wet-chemical methods (for example by saponification, acid cleavage, oxidative or reductive decomposition), is therefore not possible without simultaneous destruction of the feature substance. Likewise, a combustion of the value document followed by a digestion of the ash, eg by flotation, Sedimentation or by the treatment with aqueous solutions, in particular with acids, bases or reducing agents, without destroying the feature substance not possible.

Example 3 (relates to the third class of compounds for the formation of the feature substance )

As luminescent feature substance in the infrared spectral range, a 0.1% MnO ₄ ^2- doped potassium strontium sulfate K ₂ Sr (SO ₄ ) ₂ of particle size D99 = 3 μm is used, which upon excitation with radiation having a wavelength in the range of 500 to 600 nm shows a broad luminescence emission in the range of 1000 to 1300 nm.

The fabric is incorporated in a methylmethacrylate-based UV-curing adhesive (amount: 1% by weight). The adhesive is used at an application rate of 7 g / m ² to bond together a PET (polyethylene terephthalate) (PET) film and a paper sheet to form a value document substrate.

Said feature substance reacts sensitively to aqueous environments (solubility> 2000 mg / l), especially in the presence of acids, and the matrix-stabilized cation Mn ⁶⁺ used as dopant is also unstable in an aqueous environment and is able, depending on the pH For example, to disproportionate with the formation of permanganate ions MnO ₄ ^- and other manganese species or to decompose by reaction with oxygen or other species in low-valent anions of manganese anions of oxidation states 2, 3, 4 and 5.

Destruction of the adhesive layer of the value document, in particular by wet-chemical methods (for example by saponification, acid cleavage, oxidative or reductive decomposition), is therefore not possible without simultaneous destruction of the feature substance. Likewise, combustion of the value document followed by digestion of the ash, e.g. by flotation, sedimentation or by the treatment with aqueous solutions, in particular with acids, without simultaneous destruction of the feature substance not possible.

Example 4 (relates to a non-luminescent feature substance)

The feature substance used is an iron (II) sulfate FeSO ₄ of grain size D99 = 2 μm as NIR absorber pigment, which has a strong absorption band in the infrared spectral range between 800 nm and 1000 nm.

The feature substance is incorporated into a component of a 2-component epoxy resin adhesive. The adhesive obtained after combination of both adhesive components (proportion: 4% by weight based on the mixture) is used at an application thickness of 8 g / m ² to bond two BOPP films (biaxially oriented polypropylene) together to form a value document substrate.

Said feature substance is sensitive to aqueous environments (solubility> 200000 mg / l), especially in the presence of bases or oxidants (which causes oxidation of Fe (II) cations to Fe (III) cations).

A destruction of the adhesive layer of the value document, in particular by wet chemical methods (eg by saponification, acid cleavage, oxidative or reductive decomposition), is therefore not possible without simultaneous destruction of the feature substance. Similarly, a combustion of the value document followed by a digestion of the ash, for example by flotation, sedimentation or by the treatment with aqueous solutions, in particular with bases and oxidizing agents, without simultaneous destruction of the feature substance is not possible.

Example 5 (concerns the second class of compounds for the formation of the feature substance )

A heat-activated hot-melt adhesive such as Purmelt QR 4663 is dissolved to 20% in dry MEK. The whitish-hazy paint is triturated in a vibration mill with 5% of the acid-soluble luminescent substance Ca ₃ (PO ₄ ) ₂ : Eu ²⁺ . This lacquer batch is knife-coated onto polyester film to 50 .mu.m and dried at 80.degree. Subsequently, an uncoated polyester film is placed and cured under pressure at 140 ° C for 30 minutes. Upon excitation with UV radiation, a luminous intensity of 17 Skt at approx. 490 nm is determined in remission. After treatment with 0.5M HCl over 40 minutes, the light intensity is unchanged at 17 Skt. The phosphor is protected by the polymer embedding in front of the harmful chemicals for him, without losing luminosity.

Comparative Example:

On a laboratory sheet suitable grinding degree and wet strength agent and a opazitätserhöhenden additive (TiO2) is a leaf sample with 90 g / m ² made of bleached cotton. During the sheet preparation, an amount of the acid-soluble luminescent substance Ca ₃ (PO ₄ ) ₂ : Eu ²⁺ is added to the fiber suspension in an amount such that about 1% doping of the leaf sample is set. The finished dried leaf sample has a luminous intensity from 4.5 skt up. After treatment with 0.5 M HCl for 40 minutes and subsequent drying, the light intensity has dropped to 0.0 Skt.

Example 6 (concerns the second class of compounds for the formation of the feature substance )

10% Ca ₃ (PO ₄ ) ₂ : Eu ²⁺ (d 50 = 1 μm) are incorporated into a heat-activatable hotmelt adhesive from the Technomelt® series via extruder in the melt at about 80-100 ° C. under protective gas (ZSK 26Mc). The extrudate is coated through a slot die onto a 40 μm BOPP film web, for example 1000 mm wide, with 10 g / m ² extrudate. The film coated with the extrudate can optionally be brought together via a calender and then with a second uncoated 40 μm film in order to be laminated together (140-160 ° C.) via a heating and press section, ie the crosslinking reaction of the isocyanate component between the two BOPP film webs and to form the adhesion of the two films stable by the press pressure and to achieve the desired authenticity of the Ca ₃ (PO ₄ ) ₂ : Eu ²⁺ (fastness profile see earlier examples). After a cooling section is wound on a roll or applied further coatings.

Claims (25)

1. A foil-like security element for bonding with a substrate, such as a security paper, a value document or another object of value, wherein the security element has at least one bonding area which is coated with at least one adhesive layer and the adhesive of the at least one adhesive layer includes an inorganic chemically unstable feature substance which is, e.g., unstable with respect to humidity, acids, bases, solvents, oxygen or detergents, and the adhesive is suitable, after three-dimensional cross-linking of the adhesive, for stabilizing the unstable feature substance against harmful environmental influences, in particular with respect to humidity and/or oxygen and/or solvents and/or acids and/or bases and/or oxidants and/or reducing agents, the inorganic chemically unstable feature substance being a luminescent substance, SERS-active substance or an NIR absorber.
2. The security element according to claim 1, wherein the adhesive of the at least one adhesive layer is a heat-crosslinking, water-crosslinking or UV-crosslinking adhesive, in particular on a polyurethane basis, acrylate basis or epoxy basis.
3. The security element according to claim 1 or 2, wherein the inorganic chemically unstable feature substance is unstable with respect to aqueous solutions of acids and/or bases and the instability with respect to aqueous solutions of acids and bases is defined according to the following tests (a) or (b):

   Test (a), relating to a feature substance unstable with respect to aqueous solutions of acids: a paper substrate which includes the feature substance or is coated with the feature substance is dipped into a 0.5-molar hydrochloric acid solution for 40 minutes at ambient temperature, wherein at least 90%, preferably at least 99% of the feature signal or of the feature intensity must get lost;

   Test (b), relating to a feature substance unstable with respect to aqueous solutions of bases: a paper substrate which includes the feature substance or is coated with the feature substance is dipped into a 0.5-molar NaOH solution for 40 minutes at ambient temperature, wherein at least 90%, preferably at least 99% of the feature signal or of the feature intensity must get lost.
4. The security element according to any of claims 1 to 3, wherein the inorganic chemically unstable feature substance is a luminescent substance which is unstable with respect to humidity and the instability with respect to humidity is defined in that upon contact of the substance with demineralized water during a period of 1 hour at ambient temperature there occurs a signal loss of the original luminescence emission by more than 40%, preferably more than 80%.
5. The security element according to any of claims 1 to 4, wherein the inorganic chemically unstable feature substance is present in particulate form.
6. The security element according to claim 5, wherein the chemically unstable feature substance is an inorganic luminescent substance and in particular is based on a host lattice doped with rare-earth ions or with transition metal ions.
7. The security element according to any of claims 1 to 6, wherein the chemically unstable feature substance has a coating with a destabilizing reagent.
8. The security element according to any of claims 1 to 7, wherein the grain size D90, in particular D99 of the feature substance particles forming the chemically unstable feature substance is smaller than the thickness of the at least one adhesive layer.
9. The security element according to any of claims 1 to 8, wherein the at least one bonding area has a release foil on the side opposing the security element layer construction.
10. The security element according to any of claims 1 to 9, wherein the security element has, either over the full area or partially, a diffractive or a refractive structure, in particular a hologram, an effect layer based on interference pigments or liquid-crystal pigments, a layer sequence with colour-shift effect, e.g. a reflector/dielectric/absorber layer construction, or a micro-optic representation arrangement, preferably a moire magnification arrangement or a modulo magnification arrangement, in particular with microfocusing elements and micromotif elements.
11. A value document substrate for manufacturing value documents, in particular bank notes, comprising at least one carrier layer and a first cover layer, wherein the first cover layer is a foil layer and the carrier layer comprises a paper layer or a foil layer and the carrier layer is connected with the first cover layer by at least one adhesive layer and the adhesive of the at least one adhesive layer includes a chemically unstable inorganic feature substance, which e.g. is unstable with respect to humidity, acids, bases, solvents, oxygen or detergents, and stabilizes this by the three-dimensional cross-linking of the adhesive against harmful environmental influences, in particular with respect to humidity and/or oxygen and/or solvents and or acids and/or bases and/or oxidants and/or reducing agents, the inorganic chemically unstable feature substance being a luminescent substance, a SERS-active substance or an NIR absorber.
12. The value document substrate according to claim 11, which additionally to the at least one carrier layer and the first cover layer further comprises a second cover layer, wherein the second cover layer is a foil layer and the carrier layer is connected with the first cover layer and with the second cover layer by respectively at least one adhesive layer and the adhesive of the at least one adhesive layer includes a chemically unstable inorganic feature substance and stabilizes this by the three-dimensional cross-linking of the adhesive against harmful environmental influences, in particular with respect to humidity and/or oxygen and/or solvents and/or acids and/or bases and/or oxidants and/or reducing agents.
13. The value document substrate according to claim 11 or 12, wherein the adhesive of the at least one adhesive layer is based on a heat-crosslinking, water-crosslinking or UV-crosslinking adhesive, in particular on a polyurethane basis, acrylate basis or epoxy basis.
14. The value document substrate according to any of claims 11 to 13, wherein the chemically unstable feature substance is unstable with respect to aqueous solutions of acids and/or bases and the instability with respect to aqueous solutions of acids and bases is defined according to the following tests (a) or (b):

    Test (a), relating to a feature substance unstable with respect to aqueous solutions of acids: a paper substrate which includes the feature substance or is coated with the feature substance is dipped into a 0.5-molar hydrochloric acid solution for 40 minutes at ambient temperature, wherein at least 90%, preferably at least 99% of the feature signal or of the feature intensity must get lost;

    Test (b), relating to a feature substance unstable with respect to aqueous solutions of bases: a paper substrate which includes the feature substance or is coated with the feature substance is dipped into a 0.5-molar NaOH solution for 40 minutes at ambient temperature, wherein at least 90%, preferably at least 99% of the feature signal or of the feature intensity must get lost.
15. The value document substrate according to any of claims 11 to 14, wherein the inorganic chemically unstable feature substance is a luminescent substance which is unstable with respect to humidity and the instability with respect to humidity is defined in that upon contact of the substance with demineralized water during a period of 1 hour at ambient temperature there occurs a signal loss of the original luminescence emission by more than 40%, preferably more than 80%.
16. The value document substrate according to any of claims 11 to 15, wherein the chemically unstable feature substance is an inorganic luminescent substance and in particular is based on a host lattice doped with rare-earth ions or with transition metal ions.
17. The value document substrate according to any of claims 11 to 16, wherein the grain size D90 of the feature substance particles forming the chemically unstable feature substance is smaller than the thickness of the at least one adhesive layer.
18. The value document substrate according to any of claims 11 to 17, wherein the at least one adhesive layer has two partial regions which respectively include a first unstable feature substance or a second unstable feature substance, wherein the first feature substance and the second feature substance differ with regard to their excitation wavelengths and/or their emission wavelengths and the two partial regions of the adhesive layer in this way form a coding.
19. The value document substrate according to any of claims 11 to 17, wherein the at least one adhesive layer has two partial regions which respectively include a first unstable feature substance or a second stable feature substance, wherein the first feature substance and the second feature substance differ with regard to their excitation wavelengths and/or their emission wavelengths and the two partial regions of the adhesive layer in this way form a coding.
20. A security paper for manufacturing value documents, or value document, comprising the security element according to any of claims 1 to 10 disposed on a security paper substrate or value document substrate, wherein the at least one adhesive layer including the chemically unstable inorganic feature substance is three-dimensionally crosslinked and stabilizes the feature substance in this way against harmful environmental influences, in particular with respect to humidity, solvents, acids or bases.
21. The security paper or value document according to claim 20, wherein the substrate of the security paper or of the value document is a plastic substrate, a paper substrate, a substrate having paper constituents as well as plastic constituents or a foil/paper/foil composite.
22. A value document, in particular a bank note, comprising a value document substrate according to any of claims 11 to 19.
23. A method for manufacturing a security paper or a value document according to claim 20 or 21, comprising the step of equipping a security paper substrate or a value document substrate with the security element according to any of claims 1 to 10.
24. A transfer band, having a plurality of security elements according to any of claims 1 to 10 configured as transfer elements to be transferred to a substrate, such as a security paper, a value document or another object of value.
25. A use of the security element according to any of claims 1 to 10 for the product authentication of any type of goods.

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