EP2296912B1 - Method for producing a security and/or valuable product with partial regions having a different luminescence emission - Google Patents

Description

Field of the invention

The invention relates to a method for producing a security and / or value product, in particular a security and / or value document, comprising the following method steps: a substrate is coated with a marking layer containing a luminescent substance, becomes a pattern formed by the luminescence emission of the luminescent substance a string is formed, and the string is readably applied to the security and / or value product as an identifier string and / or readably integrated therein.

The invention further relates to a method for verifying such a security and / or value product.

Prior art and background of the invention

From the literature DE 103 04 805 A1 is a method for the production of safety mark known. In this case, a pattern of particles, for example metal particles, is formed, which are randomly distributed in the marking layer. When reading, for example with a Microscope is detected a random pattern, which is unique with very high statistical probability for the security and / or value product concerned, ie different security and / or value products differ by the respective random patterns. The random pattern of a security and / or value product is recorded in a spatially resolved and intensity-resolved manner, a characteristic string is generated from the recording and the string is affixed to the security and / or value product as an identification string. By comparing a re-recording of the random pattern, generation of the string and their comparison with the also read-out identity string then the authenticity of the security and / or value product can be determined. A similar method based on other random materials is from the literature US 4,218,674 known.

On the one hand, these methods are relatively expensive in the production of the security and / or value product. Because first, the marking layer must be made. Then the acquisition of the random pattern, followed by the generation of the string and attachment of the ident string formed therewith. On the other hand, verification has significant potential sources of error. For example, in the determination of the character string in the course of production, an intensity threshold must also be defined in the simplest case, which differs from "dark" in the context of the pattern "bright". This requires a corresponding calibration of devices with which a recording of the Random pattern for verification purposes. In addition, the intensities may be changed by surface contamination, abrasion, etc. in the course of use of the security and / or value product, for example, in durable security and / or value products, such as banknotes, passports or the like. As a result, there is also the risk of a very high "false-negative" rate (FRR = false rejection rate) during the verification, which disturbs very considerably, especially in the case of security and / or value documents.

From the literature EP 0 991 523 B1 Pigments are known which allow laser marking of an organic polymer layer.

From the literature WO 2005/115766 A1 A method comprising the method steps a) and c) of claim 1, and wherein an identity string is readably applied and / or integrated on the security and / or value product, it is known that a marking layer with an electroluminescent substance is an electrically conductive pigment whereby a non-contact excitation of the electroluminescence can be effected in sufficient intensity for a detection of the luminescence.

From the literature EP 1 631 461 B1 It is known to add a pigment having a particularly high relative permittivity to a marking layer with an electroluminescent substance, whereby high field strengths in the electroluminescent substance and thus high luminescence emission under moderate excitation conditions are achieved by way of field displacement.

Technical problem of the invention

The invention is based on the technical problem of specifying a security and / or value product with a luminescence pattern as well as a correlated identity string attached to it, for example, on the security and / or value product, which is easier to produce and reliable in the verification "false-negative". Avoids results.

Broad features of the invention and preferred embodiments.

To solve these technical problems, the invention teaches methods for producing a security and / or value product, according to claim 1 and 2 and method for verification according to claims 13 and 14.

The invention is based on the recognition that defined and predefined patterns can be generated by targeted modification of the luminescence in partial regions of the marking layer, whereby the necessity of determining a previously generated pattern for the purpose of determining the correlated character sequence is eliminated. Furthermore, it is achieved that the amplification or reduction of the luminescence emission in the partial regions can be effected significantly in the sense that the change is sufficiently large in order to prevent the luminescent emission or its surface from becoming contaminated or attrition on the surface of the security and / or product of value Intensity in the unaltered areas to be discriminated. Ultimately, a permanent and reliable avoidance of "false negative" results during verification is achieved.

In the context of the invention, there are many possibilities for further training.

The term security and / or value product includes in particular security and / or value documents. Security and / or value documents are, for example: identity cards, passports, ID cards, access control cards, visas, tax stamps, tickets, Driving licenses, motor vehicle papers, banknotes, checks, postage stamps, credit cards, any chip cards and adhesive labels (eg for product protection). Products which do not fall under the concept of security and / or value document are labels, consignment notes, inspection certificates, vouchers as well as all everyday products which can be forged and which can be unambiguously identified as originals by the application of the security feature according to the invention.

A substrate is a flat support structure based on synthetic and / or natural organic polymers. A substrate may consist of one layer or of a stacked composite of several layers. Basically, all materials, as usual in the technology of security and / or value products, can be used. For example, as suitable materials for a substrate or for various layers of a substrate are mentioned only: paper materials, printing layers, color layers, woven fabric, non-woven of e.g. Polycarbonate (PC) or general polyester (PET, PETG), plastics such as polycarbonates or polyphthalphthalates. In the case of layers of plastics, these may be formed as films.

After the marking layer has been applied to the substrate, a cover layer, preferably of a transparent plastic, can be applied to the marking layer. It is also possible to apply several different transparent cover layers.

The marking layer can be applied over the entire surface of the substrate, or only on a partial surface of the substrate. In the latter case, a cover layer which may have been set up needs to be transparent only above the partial surface of the substrate carrying the marking layer, but may nevertheless also cover the entire surface of the substrate and also be transparent over its entire surface.

The application of the marking layer can take place in all customary ways. These include printing techniques. Suitable printing methods in principle are all printing processes known and customary in the manufacture of security and / or value products, such as offset printing, letterpress printing, offset coating, flexographic printing, screen printing, thermal sublimation printing, gravure printing, in particular gravure gravure printing and intaglio printing, the so-called overprint varnish process , as well as all non-contact printing processes. Preferably, however, the marking layer is applied by screen printing. But also, for example, doctoring, brushing, stamping, casting, painting, dipping, flow method, roll or screen application method or application by air brush can be used. All of the above methods are based on a solution, dispersion, emulsion or paste containing the luminescent substance and at least one binder, which is applied by the methods mentioned and optionally then dried and / or cured. But it is also possible that the marking layer prefabricated as a (polymer) film or solid layer and then is attached to the substrate, for example by means of gluing or lamination. However, the manner of applying the marking layer is completely irrelevant to the invention and the above variants are only intended as a few of many possible examples.

It is preferred if the change in the partial areas of the marking layer applied in step b) is imperceptible to the human eye when illuminated with visible light and in daylight intensity, but can only be ascertained with the aid of technical aids such as magnifying glass, detectors, etc. ,

An amplification of the luminescence emission denotes - under constant excitation conditions - an increase in the intensity of the luminescence from a reference sub-area of the sub-area by at least 5%, more preferably at least 10%, preferably at least 20%, based on the intensity of the luminescence from a comparison sub-area, which is outside the sub-areas lies.

A weakening of the luminescence emission denotes - under constant excitation conditions - a decrease in the intensity of the luminescence from a reference partial area of the partial area by at least 5%, better at least 10%, preferably at least 20%, based on the intensity of the luminescence from a comparison partial area, which is outside the partial areas lies.

A pattern denotes a defined distribution of partial areas within the marker layer and in Directions parallel to a major surface of the marking layer. The marking layer need not be formed as a single layer, but may in turn be formed of marking sub-layers which are connected to one another in a stacked manner, wherein other (transparent) layers can also be interposed between marking sub-layers. As such, the pattern may be formed not only by a lateral distribution (in directions parallel to a major surface of the marker layer) of the partial regions (as in a single layer) but also by a vertical distribution (orthogonal to the main surface). In general, however, only the lateral distribution will be determined, but with an additional vertical distribution but also taking into account the vertical distribution by spatially resolved measurement of the luminescence with a different from the surface normal and predetermined angle of incidence takes place.

The partial regions typically have an areal extent in directions parallel to a main surface of the marking layer of 0.1 μm ² to 1 mm ² , in particular of 1 μm ² to 0.01 mm ² , or else 1 μm ² to 500 μm ² . The areal extent may basically be provided in any desired form, but typically a circular shape, rectangular shape, square shape or a shape of a regular polygon will be provided.

A pattern and a string are uniquely assigned to each other when exactly one pattern is associated with a string and vice versa. In contrast, For example, if each pattern is assigned exactly one string, then more than one pattern may be associated with a string. The assignment can basically be done in any way. It is preferred if the character sequence is calculated from the pattern by means of a predetermined algorithm. Then, an inherent verification is possible without external database, since then only the predetermined algorithm must be applied to the measured pattern in the course of verification, in which case a direct comparison of the thus determined string with the read identifier string is possible. By way of example only, a suitable algorithm may be the calculation of a hash value from the pattern, including its coordinates with respect to at least one reference point of the security and / or value product (viewed in projection orthogonal to a major surface of the marker layer). It is basically sufficient if the assignment is unique, so that even with hash functions, depending on the complexity, so-called collisions can be tolerated to some extent. Because in the verification yes the pattern is read, determined by means of the predetermined hash function, the string and compared with the identity string. It does not matter that in the event of a collision, another security and / or value may exist with a different pattern, which results in the same string when the hash function is used (collision). Conveniently, however, the target amount of the hash function is chosen so large that at most few collisions are to be expected. In the number space could the Target amount of hash function, for example, at least 10 ⁴ , better at least 10 ⁵ , preferably at least 10 ⁶ , different elements, such as alphanumeric characters, be large. With regard to suitable hash algorithms, reference is additionally made to the specialist literature on this subject.

The application or integration of the identification string on or into the security and / or value product can be carried out by means of all techniques customary for the personalization of a security and / or value product. This includes labeling, for example by laser, printing, for example inkjet printing, u.v.m. Since the pattern is predetermined and defined for each security and / or value product, the correlated character string is also predetermined and defined for each security and / or value product. This makes it possible to carry out steps c) and / or d) not only after stage b) but also at the same time as stage b), before stage b) and after a), or before stage a) , Depending on the sequence, the identity string is then arranged below the marking layer, within the marking layer, or above the marking layer.

An identification string is readable if it is readable by the human eye and / or with technical aids.

An identifier string may be formed, for example, as an alphanumeric string, for example as a serial number. But it is also possible that the identifier string is encoded, for example as a barcode or the like.

Suitable luminescent substances are all commercially available luminescence-indicating substances. These include fluorescent (lifetime of the excited state usually less than 10 ^-6 or 10 ^-9 s) or phosphorescent (lifetime of the excited state usually greater than 10 ^-6 s) substances, photoluminophores, electroluminophores, cathodoluminophores, chemoluminophores, bioluminophores, thermoluminophores, antistokes Phosphors, triboluminophores and sonoluminophores. Luminophores can be based on inorganic systems such as Y ₂ O ₂ S: Eu or ZnS: Cu, but also on organic systems such as fluorescein.

Basically, all luminophores are suitable. A selection can be found in the literature Ullmann's Chemical Encyclopedia, Wiley Verlag, electronic edition, 2004, keyword: Luminescent Materials ".

Electroluminophores are particulate materials which are inorganic compounds of Groups II and VI of the Periodic Table, for example ZnS or CdS doped or activated with metals such as Cu, Mn or Ag. Likewise, particulate luminescent substances on the basis of predominantly activated with Mn, Sr or rare earth silicates, aluminates, phosphates, tungstates, germanates, borates, etc., in particular substances based on Zn ₂ SiO ₄ : Mn or particulate organic Polymers or mixtures of the aforementioned compounds can be used. additional will be on the reference S. Shionoya et al., Phosphor Handbook, especially Chapter 9, Electroluminescent materials, CRC Press, 1999 , referenced.

Electroluminescent substances emit visible radiation after excitation in an alternating electric field. When a luminescent substance exhibits electroluminescence, the emission of visible light preferably takes place solely or predominantly by the excitation in an alternating electric field and, to a lesser extent, also by excitation by irradiation with light of the ultraviolet or infrared spectral range. In the case of a photoluminescent substance, it is preferred for the excitation of the photoluminescence to take place by means of UV radiation, electrical alternating fields not being required.

The particles of the luminescent substance are preferably in the form of microencapsulated compounds or sheath / core particles, wherein the core is formed by the luminescent substance. Suitable materials for the shell are both organic polymers and various metal oxides in question. The essential function of the jacket is to protect the core from environmental influences that may be detrimental to the durability and emissivity of the core. In addition, the aging resistance can be increased by means of the jacket. Finally, by means of the jacket a filter function can be exercised, both with respect to incident radiation and emitted radiation. For example, in the case of an electroluminescent Kerns of the mantle function as a UV filter, which reliably prevents luminescence under UV irradiation. However, it is also possible to achieve such a UV filter function by means of a filter layer applied to the jacket.

It is also possible to offset the luminescent substance with inorganic or organic dyes so that reflection bands or absorption bands of the luminescent substances are displaced. This allows a modulation of the emission wavelength and thus the color appearance possible. This provides a wider color gamut than is available with the luminescent substances themselves.

The marking layer may also contain a plurality of different luminescent substances. It is then expedient for the different luminescent substances to be excited differently (for example UV / electric alternating fields) and / or for different emission wavelengths.

The particle size of particulate luminescent substances may be selected according to the technology used to prepare the marking layer. For example, in the case of printing techniques, the particle size will typically be in the range of 0.2 to 50 microns, especially 2 to 30 microns. In flexographic printing even particle sizes up to 200 μm can still be applied. However, for techniques such as brushing, the particle size can be up to 100 μm and more, up to 500 μm.

According to the invention, the marking layer may additionally contain a pigment containing an electrically conductive material or a mixture of various such pigments. The addition of electrically conductive pigments is advantageous in particular when electroluminophores are used as the luminescent substance and, to that extent, is also of independent inventive significance, since this can ensure a reliable and non-contact excitation of the luminescence with alternating electrical fields. Electrically conductive pigments contain or consist of at least one electrically conductive layer. The electrically conductive layer may, for example, comprise or consist of one or more metal oxides which have been rendered conductive by means of doping, for example tin oxide, zinc oxide, indium oxide and / or titanium oxide. For doping Ga, Al, In, Th, Ge, Sn, P, Ar, Sb, Se, Te, W and / or F come into question. It is also possible to use materials which are based on a carrier layer, for example based on titanium dioxide, synthetic or natural mica, other layered silicates, glass, silicon dioxide, and / or Al ₂ O ₃ and then carry the electrically conductive layer, preferably being enveloped by this layer , In addition to the carrier layer and the electrically conductive layer, other layers may also be present, for example containing metal oxides, metal oxide hydrates, metal suboxides, metal fluorides, metal nitrides, metal oxynitrides or mixtures of such substances. Preferably, the carrier layer and / or other layers, if provided, and / or the electrically conductive layer are optically transparent or im Substantially transparent, ie they transmit at least 10%, preferably at least 70% of the incident light. The transparent or semitransparent layers can be colorless or colored. The color properties of the electrically conductive pigments can also be modified by the additional layers, in particular if they are located below the conductive layer or between the carrier layer layer and the conductive layer. The application of other layers on the electrically conductive layer can adapt the conductivity of the electrically conductive layer in accordance with specifications.

The electrically conductive pigment is preferably a mica coated with at least one electrically conductive metal oxide layer, in particular antimony-doped tin oxide. In addition, one or more metal oxide layers, for example a titanium oxide layer, may be provided on or below the electrically conductive layer.

The diameter of an electrically conductive pigment is preferably in the range of 0.1 μm to 500 μm, preferably 2 μm to 100 μm, particularly preferably 5 μm to 70 μm. A narrow particle size distribution is preferred. Preferably, platelet-shaped electrically conductive pigments are used. The aspect ratio (diameter / thickness) of platelet-shaped conductive pigments is typically at least 2: 1, in particular at least 10: 1, more preferably at least 100: 1.

Particularly transparent with high conductivity are electrically conductive platelet-shaped pigments whose number-weighted mean grain area F50 (grain area: size of a main area) is at least 150 μm ² , in particular at least 200 μm ² . It is advantageous if the number-weighted proportion of pigments having a grain area of preferably less than 80 μm ^{2 is} not more than 33%, in particular less than 25%, based on the total amount of electrically conductive pigment. Even better is a proportion with a particle size less than 40 μm ² of not more than 15%, in particular not more than 10%. This reduction of fines reduces light scattering and thus haze of the marking layer.

Suitable electrically conductive pigments are commercially available, for example, from Merck KGaA.

In a further embodiment of the invention, it is possible that the marking layer additionally comprises an organic or inorganic (absorption) color pigment and / or an effect pigment or a mixture of various such pigments. This may be, for example, at least one platelet-shaped effect pigment and / or an organic or inorganic color pigment.

Platelet-shaped effect pigments are platelet-shaped pearlescent pigments, predominantly transparent or semitransparent interference pigments and metallic effect pigments. Also liquid crystal pigments, so-called LCPs (Liquid Crystal Pigments), or structured polymer platelets, so-called holographic pigments, are included. These platelet-shaped pigments are composed of one or more layers of possibly different materials.

Pearlescent pigments consist of transparent platelets with a high refractive index and show a characteristic pearlescence when oriented parallel through multiple reflection. Such pearlescent pigments, which additionally show interference colors, are referred to as interference pigments.

Although, of course, classic pearlescent pigments such as TiO ₂ platelets, basic lead carbonate, BiOCl pigments or fish silver pigments are in principle suitable as platelet effect pigments preferably interference pigments or metallic effect pigments are used which on an inorganic platelet-shaped support at least one coating of a metal, metal oxide, metal oxide or have mixtures thereof, a metal mixed oxide, metal suboxide, metal oxynitride, metal fluoride, BiOCl or a polymer. The metallic effect pigments preferably have at least one metal layer.

The inorganic platelet-shaped support preferably consists of natural or synthetic mica, kaolin or other sheet silicates, of glass, SiO ₂ , TiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , polymer platelets, graphite platelets or metal flakes, such as aluminum, titanium, Bronze, silver, copper, gold, steel or various metal alloys. Preference is given to supports of mica, glass, graphite, SiO ₂ , TiO ₂ and Al ₂ O ₃ or mixtures thereof.

The size of these carriers is not critical per se. As a rule, they have a thickness of between 0.01 and 5 μm, in particular between 0.05 and 4.5 μm. The extension in the length or width is usually between 1 and 250 μm, preferably between 2 and 200 μm and in particular between 2 and 100 μm. They usually have an aspect ratio (ratio of the average diameter to the average particle thickness) of 2: 1 to 25000: 1, and in particular from 3: 1 to 2000: 1.

Preferably, a coating applied to the support consists of metals, metal oxides, metal mixed oxides, metal suboxides or metal fluorides and in particular of a colorless or colored metal oxide selected from TiO ₂ , titanium suboxides, titanium oxynitrides, Fe ₂ O ₃ , Fe ₃ O ₄ , SnO ₂ , Sb ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , ZrO ₂ , B ₂ O ₃ , Cr ₂ O ₃ , ZnO, CuO, NiO or mixtures thereof. Coatings of metals are preferably made of aluminum, titanium, chromium, nickel, silver, zinc, molybdenum, tantalum, tungsten, palladium, copper, gold, platinum or alloys containing them. The metal fluoride used is preferably MgF ₂ .

As platelet-shaped effect pigments, multilayer effect pigments are particularly preferably used. These have on a platelet-shaped, preferably non-metallic carrier several layers, which preferably consist of the aforementioned materials and different refractive indices in such a way that in each case at least two layers of different refractive index are alternately on the carrier, wherein the refractive indices in the individual layers differ by at least 0.1 and preferably by at least 0.3. In this case, the layers located on the carrier can be both almost transparent and colorless as well as transparent and colored or semitransparent.

Likewise, the so-called LCPs, which consist of crosslinked, oriented, cholesteric liquid crystals, or else also known as holographic pigments structured polymer platelets can be used as platelet-shaped effect pigments.

The platelet-shaped effect pigments described above may be present individually or in admixture in the security element according to the present invention.

The platelet-shaped effect pigments used according to the invention are preferably transparent or semitransparent. In this case, semitransparent pigments transmit at least 10%, transparent pigments, however, at least 70% of the incident visible light. Such platelet-shaped effect pigments are preferably used, since their transparency in a security and / or valuable product contributes to a large variety of possible background or background colors and at the same time does not impair the intensity of the light emission produced by electroluminescence.

However, in certain embodiments of the present invention, it is also possible to use a flake-form effect pigment having at least one metal layer.

In one embodiment of the present invention, a platelet-shaped effect pigment is used which leaves a different visually perceptible color and / or brightness impression at different illumination and / or viewing angles. For different color impressions, this property is called a color flop. In particular, pigments which have a color flop produce in the security and / or value products produced therewith non-duplicable color and gloss impressions which are readily perceptible to the naked eye without auxiliaries. Such pigments are also referred to as optically variable. The optically variable platelet-shaped effect pigments have, for example, three optically clearly distinguishable discrete colors under at least two different illumination or viewing angles at least two and at most four, but preferably under two different illumination or viewing angles two or three different illumination or viewing angles. Preferably, only the discrete hues and no intermediate stages are present, that is, a clear change from one color to another color is recognizable when the security element containing the optically variable pigments is tilted off. On the one hand, this feature makes it easier for the viewer to recognize the security element as such and at the same time makes it more difficult for the viewer to do so Copiability of this feature, since in the commercial color copying Farbflopeffekte can not be copied and reproduced.

Of course, however, optically variable platelet-shaped effect pigments can also be used which, when tilted over different illumination and / or viewing angles, produce a color gradient, i. many different shades, such as the typical pearlescence, have. Even such diffuse color changes are easily detectable by the human eye.

In order to be able to develop their full optical effect, it is advantageous if the platelet-shaped effect pigments used according to the invention are present in an oriented form in the marking layer or the security and / or desired product, i. they are aligned almost parallel to the surfaces of the security product provided with the security element. As a rule, such alignment is already effected essentially by means of the customary methods used for applying the security element, for example customary printing methods.

As platelet-like effect pigments, for example, the commercially available interference pigments, which are available, for example, under the names Iriodin®, Colorstream®, Xirallic® or Securalic® from Merck KGaA, Mearlin® from Mearl, metallic effect pigments from Eckhard and goniochromatic (optically variable ) Effect pigments like For example, Variochrom® from BASF, Chromafflair® from Flex Products Inc., Helicone® from Wacker or holographic pigments from Spectratec and other similar commercially available pigments are used. This list, however, is to be considered as illustrative and not exhaustive.

Inorganic color pigments are all customary transparent and opaque white, colored and black pigments, such as, for example, Berlin blue, bismuth vanadate, goethite, magnetite, hematite, chromium oxide, chromium hydroxide, cobalt aluminate, ultramarine, chromium-iron mixed oxides, spinels such as Thenard's blue, cadmium sulfides andselenide, chromate pigments or carbon black are suitable, while as organic color pigments in particular quinacridones, benzimidazoles, copper phthalocyanine, azo pigments, perinones, anthanthrones, other phthalocyanines, anthraquinones, indigo, thioindigo and their derivatives, or Carmine are mentioned. In general, it is possible to use all organic or inorganic color pigments which are customary in particular in the printing sector.

For shielding against ultraviolet radiation and pigments can be used which absorb UV light. Of these, titanium dioxide and zinc oxide are given by way of example only.

The particle size of the inorganic and organic color pigments is not critical, but must be adapted to the requirements of the application of the security element on or in a security product, for example with a printing process to be adjusted. The same applies analogously, as noted for the luminescent substance and / or the electrically conductive pigments.

The luminescent substance may form a random pattern in the marking layer. Then analogous to the literature DE 103 04 805 A1 and independently of the individual pattern produced according to the invention, the security and / or value product provided with the marking layer is subjected to a recording of the random pattern, wherein in turn a hash value is calculated from the random pattern, for example as a second identification string, for example as part of a serial number the security and / or value product is applied or integrated herein, according to the above-described identifier string. An (additional) verification can then be done by detecting the random pattern, calculating the identifier string (with the same algorithm as in the above calculation of the second identifier string) and comparing it with the second identifier string attached to or in the security and / or value product.

The modulation of the luminescence emission in the subregions of step c) can be made possible, for example, by the marking layer additionally having a laser-sensitive pigment. Then, by irradiation by means of laser light of a given dose rate, either an increase in the permittivity of components of the marking layer in the immediate vicinity (for example within an area of 100 μm ² to 1 mm ² , in particular 1000 μm ² to 10000 μm ² , in a plane parallel to a main surface of the marking layer), for example an electroluminescent pigment, for example by way of phase transformation or, for example by pyrolysis, the permittivity of components of the marking layer in the immediate vicinity Environment (for example, within an area of 0.1 .mu.m ² to 1 mm ² , in particular 1 .mu.m ² to 100 .mu.m ² , in a plane parallel to a major surface of the marking layer) of an electroluminescent be reduced so much that an electroluminescence in this area practically no longer takes place. In the former case, the subregions are distinguished by electroluminescence which is intensified in relation to the environment, in the second case by reduced or completely suppressed electroluminescence. In the former case, the subregions consequently form a pattern which is particularly bright in an alternating electric field, while in the second case, on the other hand, a negative pattern is formed, as it were, by the comparatively dark subregions. The former can be achieved with comparatively low dose rates of the laser, the latter with comparatively high dose rates. The dose rate suitable for a marking layer with a specific composition for one of the two cases can be determined in each case by means of simple experiments or test series, for example, the marking layer is irradiated to different predetermined locations with different dose rates associated with the sites and then the gain and / or reduction the electroluminescence is recorded quantitatively. When observing the desired quantitative change, the dose rate associated with the site is the appropriate one. It is also possible to reduce the photoluminescence of corresponding luminescent substances by, for example, pyrolysis.

For such a modulation, however, the presence of a laser-sensitive pigment is not absolutely necessary. Thus, for example, even without such a pigment by means of a laser pattern similar to the above can be generated. Because with the entry of thermal energy by the (local and according to the pattern given) laser irradiation, a local melting in the marking layer and thus in the immediate vicinity of the luminescent substance is generated. This, in turn, alters the spatial distribution of the electrically conductive material-containing pigment as compared to the unfused environment within the marking layer. This results in a change in the field displacement and, in the case of an electroluminophor, consequently a local change in the luminescence upon excitation with electric fields. Depending on the duration and dose of the laser radiation as well as the (local) concentration of the pigment containing electrically conductive material, an amplification or attenuation of the electroluminescence in the areas irradiated by the laser can thereby be achieved.

In a further variant, the pigment containing electrically conductive material is itself a laser-sensitive one Pigment. The local irradiation by laser then alters both the dielectric properties of the environment of the luminescent substance and the electrical properties of the electrically conductive material itself, again with the consequence of the modulation (amplification or attenuation) of the electroluminescence upon excitation by means of electric fields. Otherwise, the above statements apply analogously.

As laser-sensitive pigments, all known in the technological field of safety and / or value products pigments can be used. They may for example be formed from organic polymers which have a high absorption of the laser radiation, for example PET, ABS, polystyrene, PPO, polyphenylene sulfide, polyphenylene sulfone, polyimidesulfone. But it can also be, for example, LCPs. Particularly suitable are micro-ground thermoplastics with a very high melting range of more than 300 ° C. The particle size is typically in the range of from 01 to 100 μm, in particular from 0.1 to 50 μm, preferably from 1 to 20 μm. The polymer particles may further contain light-sensitive fillers or pigments, for example in an amount of from 0.1 to 90% by weight, based on the laser-sensitive pigment. These may also be electrically conductive pigments and / or effect pigments and / or dyes, as described above. It may also be oxides, hydroxides, sulfides, sulfates or phosphates of metals such as Cu, Bi, Sn, Zn, Ag, Sb, Mn, Fe, Ni, or Cr. In particular, basic Cu (II) hydroxide phosphate used. Specific mention is a product of the heating of blue Cu (II) orthophosphate (Cu ₃ (PO ₄ ) ₂ * 3H ₂ O) to 100 to 200 ° C is formed and a molecular formula Cu ₃ (PO ₄ ) ₂ * Cu (OH) ₂ has. Other suitable copper phosphates are: Cu ₃ (PO ₄ ) 2 * 3Cu (OH) ₂ , Cu ₃ (PO ₄ ) ₂ * 2Cu (OH) ₂ - * 2H ₂ O, 4CuO * P ₂ O ₅ , 4CuO * P ₂ O ₅ * 3H ₂ O, 4CuO * P ₂ O ₅ * 1, 5H ₂ O and 4CuO * P ₂ O ₅ * 1, 2H ₂ O.

Suitable laser radiation has a wavelength in the range 150 nm to 10600 nm, in particular 150 nm to 1100 nm. For example, CO ₂ lasers (10,600 nm), Nd: YAG lasers (1064 nm or 532 nm) and pulsed UV lasers (excimer lasers) can be used, and the energy density is generally in the range of 0.3 mJ / cm ² to 50 J / cm ² , in particular in the range 0.3 mJ / cm ² to 10 J / cm ² .

Advantageous in the context of the inventive variant of the modulation of the luminescence emission in the partial areas by means of laser is that in the same step of the laser irradiation and the identification sequence generated by laser marking in the security and / or value product, for example, in the marking layer attached.

The production of a modified marking layer according to the invention takes place, as explained above, for example by application of a preparation with the pigments discussed above, for example by way of printing on the substrate. The aforementioned pigments, substances and particles are then in the preparation in such a suitable concentration before that a printing of the preparation is still easily possible. Thus, the concentration of the luminescent substance in the preparation is 0.01 to 20 wt .-%, preferably 1 to 10 based on the preparation. In contrast, the electrically conductive pigment is generally present in a concentration of from 0.0 to 20% by weight, in particular from 0.01 to about 20% by weight, preferably from 1 to 10% by weight, based on the preparation, in this before. In the event that the marking layer should also contain platelet-shaped effect pigments and / or organic or inorganic color pigments, these are in the preparation in a concentration of 0.01 to 40 wt .-%, preferably 2 to 20 wt .-%, based on the preparation included. In the event that the marking layer should also contain laser-sensitive pigments, these are contained in the preparation in a concentration of 0.01 to 20 wt .-%, preferably 0.1 to 10 wt .-%, based on the preparation. The pigments and particles mentioned can be added to the preparation individually or in a mixture. This can be done in the form of powdered pigments and particles. However, the abovementioned pigments and particles are preferably introduced into the preparation individually or in a mixture of at least two different types of flowable pigment preparations or dry preparations. These contain at least one suitable binder in addition to the pigment constituents. Thus, for example, a pigment preparation or a dry preparation can be prepared from a mixture of a particulate substance having electroluminescent properties and a transparent electrically conductive pigment, optionally still one or more effect and / or color pigments and optionally the laser-sensitive pigment are added. Single preparations or other combinations are also possible. Flowable pigment preparations are understood in particular to be pastes or pastes which, in addition to the pigments mentioned, may also contain binders, solvents and optionally one or more additives. The dry preparations mentioned generally contain the same additives, but with a largely reduced solvent content. As dry preparations but also preparations are considered which contain 0 to 8 wt .-%, preferably 2 to 8 wt .-% and in particular 3 to 6 wt .-% of water and / or a solvent or solvent mixture. These dry preparations are preferably in the form of pearlets, briquettes, pellets, granules, chips, sausages or in similar forms and generally have particle sizes of about 0.280 mm. Such flowable pigment preparations and dry preparations facilitate the transport, storage and uniform introduction of the pigments into the printing ink, prevent segregation of pigments and other constituents and promote good redispersing behavior of the printing inks. In addition to the pigment components, the preparation contains one or more suitable binders, typically in an amount of 5 to 70 wt .-%, and optionally other additives such as solvents, for example in an amount of 5 to 70 wt .-%, and additives such as adhesion promoters , Dispersing aids, drying accelerators, photoinitiators and the like, which are common in such formulations, in an amount of typically 0.1 to 20 wt .-%. The above proportions by weight always add up to 100 wt .-%. In the finished marking layer, the relevant components are then present in quantities which are calculated from the deduction of the proportion of the solvents from the preparation. It is understood that these binders and additives are adapted to the printing process to be used and that the composition has an adequate viscosity.

As already mentioned, however, the marking layer can also be prefabricated. Suitable layered materials include papers of various types or polymeric materials, but may also be textile materials, etc.

When the marking layer is based on a polymeric layer, it has two surfaces lying essentially parallel to one another and contains the various pigments described above in the variants and options described. The concentrations of the various substances and, if appropriate, adjusted pigments are basically in ranges as described above for the preparation, only based on the weight of the marking layer. The substances and pigments used are introduced into the polymeric matrix preferably in the form of masterbatches. These contain, in addition to the pigment constituents and substances, suitable amounts of binders, solvents and, if appropriate, further customary auxiliaries and additives. In this case, all thermoplastics which are opposite to the luminescent substance as well as polymers can be used as polymers If necessary, additional inert pigments and substances show an inert behavior. The polymers should not be electrically conductive or enhance the electrical conductivity of the polymeric layer. In the case of electroluminescent substances, it is particularly expedient if the marking layer as such is not continuously electrically conductive, although it contains electrically conductive pigments, since otherwise short circuits may occur. Preferably, the marking layer is transparent. Therefore, transparent polymers are preferably used. This applies, for example, to polystyrene, polyvinyl chloride, polycarbonate and their mixed and graft polymers, polyvinylidene chloride and fluoride, polyamides, polyolefins, polyacrylic and vinyl esters, thermoplastic polyurethanes, cellulose esters and the like. They could be used singly or in suitable mixtures. In addition, the marking layer may additionally contain customary auxiliaries and additives such as fillers, UV stabilizers, inhibitors, flame retardants, lubricants, plasticizers, solvents, dispersants and additional dyes or organic and / or inorganic color pigments. The marking layer is preferably produced by various suitable methods such as film casting, spin coating, extrusion process, calendering or compression molding, but in particular by extrusion processes or by a blown film process. For this purpose, the various starting materials are mixed together and processed in suitable, generally known systems to polymer layers in the form of films of different thickness or thin plates. In this case, possibly in the polymer composition contained platelet-shaped pigments (effect pigments and possibly also the electrically conductive pigments) are aligned on the surfaces of the tools and are therefore oriented in the resulting polymeric layers substantially parallel to the surfaces of the polymeric layer. Stretching and pulling operations during film blowing or as subordinate steps to extruding further reinforce this orientation of the pigments. During the subsequent cooling, this orientation is fixed. A segregation or settling behavior of the pigment mixture used can not be determined in the finished marking layers. Care should be taken, however, that no excessive shearing forces act on the pigment components to prevent their destruction.

Instead of being in a polymeric material, the luminescent substance and optionally furnished pigments can also be introduced into paper raw materials or textile raw materials to form the marking layer. Such a marking layer is produced by adding, in addition to the constituents mentioned, all base materials and auxiliaries which are customary in particular in papermaking. Changes in the usual procedure do not result from the luminescent substance and, if appropriate, pigments. Rather, their concentration is chosen so that all current methods, such as papermaking, can be applied. These are known in the art and therefore need not be closer be explained. However, as already described above, care should be taken to ensure that the pigments are not damaged or destroyed in the production process of the papers and textiles and that there is no continuous electrical conductivity in the resulting paper or textile. As paper-based substrates are all common types of papers, but especially security papers with basis weights up to. 200 g / m ² , preferably those of cotton fibers and / or textile materials, can be used.

A security and / or valuable product, in particular security and / or valuable document, is obtainable with a method according to the invention. In this case, the substrate may be formed by the security and / or value product itself. However, it can also be provided that the marking layer is arranged on a flat substrate, which then in turn attached to the security and / or value product, for example glued etc., or integrated therein, for example, laminated, etc., is. In the latter case, the substrate may consist of a layer or else be multilayered.

Finally, the invention also relates to a method for verifying a security and / or value product, in particular a security product according to the invention and / or value product, wherein the security and / or value product is exposed to the luminescence stimulating conditions, with a spatially resolved and intensity-resolved recording of the Safety and / or value product Lumineszenzstrahlung emitted, wherein the pattern is determined by identifying the subregions with increased or decreased luminescence emission, wherein from the pattern, the associated string is determined, with an identifier string is read from the security and / or value product and / or from a database, wherein the string is compared with the string of identities, the security and / or value product being deemed to be false if the string and string are not matched, and true if the string and string match. A spatially resolved and intensity-resolved recording can be obtained, for example, by means of a camera which simultaneously or scans a two-dimensional image. Only as a suitable camera be a camera with a two-dimensional CCD chip and a CCD chip upstream optics called. The recording is generated either at exactly predetermined positioning of the security and / or value product relative to the camera and excitation of the luminescence, or the pattern contains a for all security and / or value products same and equal positioned reference pattern, based on which a coordinate definition of the recorded Subareas can be done. Then an alignment is not required. The reference pattern may have been generated in accordance with the subregions, whereby the recording then inherently contains the reference pattern and an evaluation of the pattern is readily possible in terms of data technology.

Figur 1:

Aufsicht auf eine Markierungsschicht vor Modulation der Lumineszenzemission unter Lumineszenzanregung und

Figur 2:

Aufsicht auf eine Markierungsschicht nach Modulation der Lumineszenzemission unter Lumineszenzanregung.

In the following, the invention will be explained in more detail by way of embodiments that merely represent embodiments. Show it:

FIG. 1:

Top view of a marking layer before modulation of the luminescence emission under luminescence excitation and

FIG. 2:

Top view of a marking layer after modulation of the luminescence emission with luminescence excitation.

Example 1: Preparation of a marking layer

First, a preparation is prepared with the following components: 5-70% by weight of resin / binder system, 5-70% by weight of solvent, 0-15% by weight, in particular 0.1-15% by weight of catalysts / Initiators, 0-20 wt .-%, in particular 0.1-20 wt .-% additives, 0.1 to 20 wt .-% luminescent substance or a mixture of different luminescent substances, for example a mixture of one or more Elektroluminophor and one or a plurality of photoluminophores, wherein the ratio of electroluminophore to photoluminophore can be between 0.1: 99.9 and 99.9: 0.1, in particular between 20:80 and 80:20, 0-25 wt .-%, in particular 5-25 % By weight, effect pigment, in particular interference pigment, or a mixture of different effect pigments, and also from 0.1 to 10% by weight of laser-sensitive pigment or a mixture various such pigments, wherein the sum of all components always gives 100 wt .-%.

As the resin / binder system, for example, reactive monomers, oligomers, prepolymers, such as mono-, di-, and / or trifunctional acrylates are suitable. Commercially available systems include, for example, the Laromer® series (BASF), SR-9003 or SR-415 (Sartomer), melamine impregnating resins, such as the Kauramin® or Kaurit® series (BASF), for example -752, -753, -786 or -787, or polymer dispersions, such as the Kauro-pal® series (BASF), for example -937 or 938. Likewise, varnishes based on nitrocellulose or linseed oil can be used.

Suitable solvents are all solvents customary in organic chemistry with the proviso that pigments used thereof are not dissolved or dissolved. These include alcohols such as methanol, ethanol or isopropanol, ketones such as acetone or 2-Bunanon, esters such as ethyl acetate, halogenated solvents such as dichloromethane, and / or aromatics such as toluene or xylene. In a water-based preparation, the essential solvent is water, and in small amounts, typically below 20 wt .-%, usually less than 10 wt .-%, based on the solvent, and organic solvents may be present.

As catalysts / initiators conventional photoinitiators, such as Irgacure® 2020, Irgacure® 819 or Darocure® 1173 (all Ciba) can be used. For the mentioned Kauramin® or Kauramit® resins are the For example, the hardener 527 or 529 (BASF) suitable. Free-radical generators, such as, for example, azo-isobutyrodinitrile, can also be used.

As additives there may be used excipients such as antifoaming agents (for example Byk-020 or -052 from Byk), surfactants (for example Baysilone from Bayer or Byk-306 or 310 from Byk), preservatives (for example Borchers S1 from Borchers), etc. Additive is added on Ullmann's chemical encyclopedia, Wiley Verlag, electronic edition 2007, keyword "Paint Additives" or www.borchers.de referred s.

Suitable electroluminophores are, for example, in the literature S. Shionoya et al., Phosphorus Handbook, Chapter 9, Electroluminescent Materials, CRC Press, 1999 , described. Suitable photoluminophores are, for example, in the literature Ullmann's chemical encyclopedia, Wiley Verlag, electronic edition 2007, keyword "Luminescent Materials In this case, the luminescent substance generally has a coarse-grained structure, for example a d90 value (diameter range which comprises 90% by weight of the particles, remainder typically 5-50 μm fines content.) Ideally, the size distribution is very narrow, in particular practically monomodal.

Useful interference pigments include, for example, the aforementioned products of various companies. Useful laser-sensitive pigments are, for example, in the reference EP 0 991 523 B1 described.

The preparation described above is applied in a single process step, for example by screen printing, to any substrate, not shown for the sake of clarity.

A marking layer is obtained which, upon excitation with alternating electrical fields, produces a luminescence in accordance with FIG. 1 shows. In this case, the luminescent points are considerably more numerous and randomly distributed than the simplified representation, and thus result in a random pattern. The diameter of a drawn point should stand for the intensity of electroluminescence. Not shown is a further random pattern obtainable under UV excitation, which results from the excitation of the photoluminophore. The FIGS. 1 and 2 represent a greatly enlarged section of the marking layer, in which the intensity of the luminescence emission varies with the size of the points shown. Big points mean in FIG. 2 a high luminescence intensity, small dots correspondingly low luminescence intensities.

Example 2: Modulation of Luminescence in Subregions

A laser sweeps according to a predetermined path the shown and through the predetermined path of the laser beam in turn given subregions, where in the subregions a local pyrolysis by the strong absorption of the laser radiation in the laser-sensitive pigment and its immediate environment (diameter up to 10 microns to the center of a laser-sensitive pigment) takes place. As a result, the permittivity in the immediate vicinity of a laser-sensitive pigment is reduced, with the result that an electroluminophore in this environment can no longer be excited to luminescence with the alternating electric field of the same frequency and intensity as in Example 1. As a result, the partial regions show a reduced electroluminescence compared with the other regions, as in US Pat FIG. 2 represented schematically by the smaller points. The pyrolysis is due to the control of the laser, as described locally limited, so that the pyrolyzed areas are practically imperceptible in normal daylight and with the human eye without technical aids.

Instead, with another (relatively low) radiation dose of the laser but also an increase in the permittivity in the environment of the laser-sensitive pigments by phase transformation of the matrix or other pigments can be achieved, with the result that upon excitation with the same alternating electric field, the luminescence in the sub-areas is now increased. Even this change is not visible to the human eye without aids.

Example 3: Attaching the identification string

Since in step 3 the path of the laser is predetermined via the marking layer, the position and orientation of the subregions are also predetermined and known. By means of a computer, which can also control the path of the laser, a hash value can then be calculated from the orientation and position of the subregions by means of a usual hash algorithm as the identity string. This hash value is made in the form of a string as part of a marking layer and thus assigned to the security and / or value product serial number. By means of suitable control of the laser, the identification sequence or serial number can then be written into the marking layer in the same process step as the generation of the partial regions by means of laser marking.

Thus, the subregions or locally highly resolved form the subregions of the marker layer a hidden and inherent to the serial number or the identifier string redundant individual security feature, which is extremely difficult to replicate. The replica would also, if at all possible, require the individual replication of each individual security and / or value product or its marking layer, which would represent an extreme technological effort from the point of view of afterimages.

Example 4: Verification of a security and / or value product.

The security and / or desired product or its marking layer obtained in Example 3 is exposed to an alternating electric field whose frequency and intensity correspond approximately to the conditions of Examples 1 or 2. At the same time, by means of a two-dimensionally resolving CCD camera, the image from the subregions of the FIG. 2 formed pattern and the serial number or the identifier string read. From the pattern, a hash value is calculated with the algorithm of Example 3 and compared with the read-out identity string. If they match, the security and / or value product is verified, and if not matched, it is most likely a forgery.

Claims (14)

1. A method for producing a security and/or value product, particularly a security and/or valuable document, comprising the following method steps:

   a) a substrate is coated with a marking layer (1) containing at least one particulate luminescent substance, and in addition a pigment containing an electrically conductive material,

   b) optionally exciting the luminescent substance before or at the same time as one of steps c) or d), so that the luminescent substance has a detectable luminescence emission,

   c) a plurality of partial sections (2a, 2b, 2c) of the marking layer (1) are selected and modified, forming a defined pattern being unique for the security and/or value product, with the proviso that the luminescence emission of the luminescent substance in the partial sections (2a, 2b, 2c) is strengthened or weakened,

   d) a sequence of characters is assigned, preferably in a one-to-one correspondence, to the pattern produced in step c) and optionally detected by measurement through a spatially resolved determination of the excited luminescence,

   e) the sequence of characters assigned in step d) is applied in a readable manner on the security and/or value product as an identification sequence of characters (3) and/or is incorporated therein in a readable manner.
2. The method according to claim 1, wherein instead of step e), the sequence of characters assigned in step d) is stored in a database system.
3. The method according to claim 1 or 2, wherein the luminescent substance is an electroluminophore.
4. The method according to one of claims 1 to 3, wherein the electrically conductive pigment is either transparent or semi-transparent or has a color effect.
5. The method according to one of claims 1 to 4, wherein the marking layer (1) additionally includes an organic or inorganic absorption color pigment and/or an effect pigment.
6. The method according to one of claims 1 to 5, wherein the luminescent substance forms a random pattern in the marking layer.
7. The method according to one of claims 1 to 6, wherein the marking layer (1) additionally includes a laser-sensitive pigment.
8. The method according to claim 7, wherein in step c) the pattern is modified by an exposure of the partial sections (2a, 2b, 2c) to a predetermined and defined radiation dose of a laser radiation.
9. The method according to claim 8, wherein the radiation dose is predetermined with the proviso that in the immediate vicinity of the laser-sensitive pigments exposed to the laser radiation a modification changing the dialectic properties of the environment of the luminescent substance, particularly amplifying the field strength in the luminescent substance, and in particular a phase transition occurs, wherein in the partial sections an increase of the luminescence emission, and in particular of the electroluminescence emission occurs.
10. The method according to claim 8, wherein the radiation dose is defined with the proviso that in the immediate vicinity of the laser-sensitive pigments exposed to the laser radiation, a pyrolysis occurs, wherein in the partial sections a reduction of the luminescence emission, and in particular of the electroluminescence emission occurs.
11. The method according to one of claims 1 to 10, wherein a hash function is computed from the pattern, from which then the sequence of characters is formed.
12. The method according to one of claims 1 to 11, wherein the identification sequence of characters (3) forms a serial number or part of a serial number.
13. A method for verifying a security and/or value product including a substrate, which is coated with a marking layer (1) containing at least one particulate luminescent substance and in addition a pigment containing an electrically conductive material, a plurality of partial sections (2a, 2b, 2c) of the marking layer (1) being selected and modified, forming a defined pattern being unique for the security and/or value product, with the proviso that the luminescence emission of the luminescent substance in the partial sections (2a, 2b, 2c) is strengthened or weakened, a sequence of characters being assigned, preferably in a one-to-one correspondence, to the pattern produced and optionally detected by measurement through a spatially resolved determination of the excited luminescence, and the sequence of characters being applied in a readable manner on the security and/or value product as an identification sequence of characters (3) and/or being incorporated therein in a readable manner,
    wherein the security and/or value product is exposed to conditions stimulating the luminescence, wherein a spatially resolved and intensity-resolved reception of the luminescent radiation emitted by the security and/or value product occurs, wherein the pattern is determined by identifying the partial sections (2a, 2b, 2c) with an increased or reduced luminescence emission, wherein from the pattern the assigned sequence of characters is determined, wherein an identification sequence of characters (3) is read out from the security and/or value product, wherein the sequence of characters is compared to the identification sequence of characters (3), wherein, when the sequence of characters and the identification sequence of characters (3) do not match, the security and/or value product is classified as counterfeit, and when the sequence of characters and the identification sequence of characters (3) do match, is classified as genuine.
14. A method for verifying the security and/or value product obtained by the method according to claim 2, wherein the security and/or value product is exposed to conditions stimulating the luminescence, wherein a spatially resolved and intensity-resolved reception of the luminescent radiation emitted by the security and/or value product occurs, wherein the pattern is determined by identifying the partial sections (2a, 2b, 2c) with an increased or reduced luminescence emission, wherein from the pattern the assigned sequence of characters is determined, wherein an identification sequence of characters (3) is read out from a database system, wherein the sequence of characters is compared to the identification sequence of characters (3), wherein, when the sequence of characters and the identification sequence of characters (3) do not match, the security and/or value product is classified as counterfeit, and when the sequence of characters and the identification sequence of characters (3) do match, is classified as genuine.

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