EP3059713A1 - Method for verifying the authenticity of a document of value and/or security document - Google Patents

Abstract

In order to be able to verify the authenticity of a value and / or security document by a security feature that is not readily recognizable by a user so that its presence is normally not expected to be verified by simple means, a method for detecting at least one of them is established The first polymer-containing document layer comprehensive value and / or security document created. According to the method, a second polymer other than the first polymer is present in or on at least one document layer of the document. According to the invention, the method comprises the following method step: Detecting the document by detecting the presence of at least the second polymer by spectral analysis in the infrared range.

Description

The present invention relates to a method for detecting a value and / or security document, which comprises at least one document layer.

Such documents are known: typically they are identification documents, such as a passport or identity card, which generally consist, at least in part, of a multilayer plastic laminate. Such documents are for example off DE 10 2008 008 044 A1 known. Thereafter, card-shaped data carriers, in particular security and / or value documents, for example, by lamination of a plurality of individual layers (foils) can be produced or executed in one layer. The material of the individual layers can be, for example, polycarbonate (PC), polyurethane-based thermoplastic (TPU), ABS, polyethylene terephthalate (PET), polyethylene, a composite of PC and TPU or paper, cardboard or woven fabric or a composite of individual ones of these materials. The core of the cards may for example consist of a light-absorbing material, while the outer layers consist of a transparent material.

Other security and / or security documents include, for example, a driver's license, a check or credit card, a company ID card, ID card or membership card, which are generally provided in the form of a ID-1 card, also laminated and made of plastic , Even banknotes, checks, gift and shopping vouchers can at least partially consist of plastics. The documents mentioned each consist of at least one document layer and usually more than one document layer. At least some of the document layers of said ID-1 cards are made wholly or at least partly of plastics.

Furthermore, it is off DE 10 2007 052 947 A1 It is known to produce a value and / or security document which has at least one polycarbonate layer of a material based on bisphenol A and an inkjet printing layer arranged thereon. The Ink jet printing layer contains inter alia a binder with a polycarbonate derivative based on a geminally disubstituted dihydroxydiphenylcycloalkane, for example based on 4,4 '- (3,3,5-trimethylcyclohexane-1,1-diyl) diphenol, 4,4' - (3, 3-dimethylcyclohexane-1,1-diyl) diphenol or 4,4 '- (2,4,4-trimethylcyclopentane-1,1-diyl) diphenol.

Security features are used to verify the authenticity of these documents. As security features are for example in DE 10 2007 015 934 A1 Guilloches, micro-typefaces, metameric systems, imprints with fluorescence, phosphorescence and / or up-conversion colors, barcodes, optically variable colors, holograms and kinegrams, digital watermarks, passport prints, viewports, mottled fibers, security threads and micro-perforations. In addition, imprints with infrared color are given as a security feature. For example, in one embodiment, the security feature in this document is a non-solid print in a color that absorbs infrared light but transmits visible light.

Furthermore, in DE 10 2005 032 704 A1 a sheet-shaped document of value having a machine-readable code, which is formed in particular in the form of a barcode. The barcode can be detectable, for example, in the infrared spectral range. For this purpose, the barcodes may consist of IR-absorbing and luminescent feature substances. An infrared-absorbing tracer may be substantially colorless in the visible spectral region.

The present invention has for its object to provide a method for detecting a value and / or security document, which is particularly suitable to verify the authenticity of the document. Above all, the security feature should not be immediately recognizable, so that its presence is usually not expected. In addition, the verification should be possible with simple means.

The object is achieved by the method for detecting, in particular verifying the authenticity, of a value and / or security document comprising at least one document layer containing a first polymer. According to the present invention, in or on at least one document layer is one of the first polymer different second polymer. According to the invention, the method comprises the following method step: Detecting the document by detecting the presence of at least the second polymer by spectral analysis in the infrared range. This does not exclude that for practical reasons, for example to increase the security of the verification, in addition, the presence of the first polymer is detected by spectral analysis in the infrared range.

In the description of the present invention and in the claims, where the terms "polymer", "first polymer", "second polymer", "other polymers" etc. are used, these include not only pure polymers, including copolymers, but also polymer combinations, For example, to understand blends (physical polymer blends). Thus, the second polymer of the first polymer may inter alia also differ by a polymer component additionally contained in the second polymer, which is not contained in the first polymer. If the two polymers are otherwise identical, the difference is caused solely by this further blended polymer component.

Preferably, the first and second polymers and optionally any further polymer are visually indistinguishable from each other, i. Any additives, such as dyes, are added to both / all polymers equally.

The infrared range used for the spectral analysis (wavelength: 800 nm to 1 mm) is in particular the middle infrared range, in which vibration modes of the polymers can be detected, ie modes in the range of, for example, 4000 cm ^-1 (wavelength: 2.5 μm) to 400 cm ^-1 (wavelength: 25 μm). These vibration modes are mainly vibration modes that detect single bonds (localized vibrations), as well as scaffold vibration modes. In addition, a distinction is made between the detection of stretching vibrations and deformation vibrations as well as combinations of these two types. Furthermore, harmonics and combination vibrations can also be evaluated. In principle, other infrared ranges can also be used, provided differences in the spectral characteristics of the two polymers (luminescence, absorption) show up in these other ranges.

According to a preferred embodiment of the invention, the presence of the second polymer is detected by detecting the presence of an IR band characteristic of the second polymer, in particular IR absorption band.

By taking advantage of the fact that a genuine document contains at least two different polymers which have different IR spectra, while in comparable documents only the first polymer is used, it can be determined by simple means of IR spectroscopy whether an examined document does this actually contains both polymers. For this purpose, it is not necessary for the first polymer also to be detected spectrally, for example because the presence of the usually used first polymer in the document is normally expected anyway. For the verification of the authenticity of the document, the detection of the IR properties of the additionally introduced second polymer is therefore fundamentally first according to the invention. Visually and without additional aids, it is not evident whether a document contains the second polymer in addition to the first polymer. Therefore, the authenticity of such a complex composed document can not be verified without these aids and only visually. Thus, however, the presence of the second polymer in addition to the first polymer in the document is not obvious, so that a construction of a document with two different polymers can be used as a security feature. Such a structure is not recognizable as such to a user. The security feature according to the invention is thus a so-called "second level" or even "third level" security feature, on the one hand from the materials already commonly used in a comparable document (first polymer) and, on the other hand, from materials already used in the Document existing materials are only slightly changed (second polymer) exists. The security feature is therefore neither visible nor forfeitable, but can be detected with a suitable device.

It is advantageous that IR spectroscopic methods have long been established. In particular, the identification of substances by means of absorption spectroscopy in the infrared range is an everyday practice in chemical laboratory operation. Therefore, the equipment requirements for a sufficiently safe and against robust use of this technique in routine operation are given. This technique is not consuming, so that a cost-effective solution for the verification of the document is available.

In addition to the aforementioned method for detecting the document, a value and / or security document according to the invention comprising at least one document layer containing a first polymer, wherein in or on at least one document layer of the document is a second polymer different from the first polymer and the both polymers have different IR absorption spectra, in particular different vibration spectra.

For detecting the document and in particular for determining the presence of one or more characteristic IR bands of at least the second polymer in the document, suitable detection devices can be used for this purpose. These are also within the meaning of the present application according to the invention. They are capable of differentiating the two polymers in the document by means of infrared spectral analysis.

The detection device may, for example, be constructed on the basis of a Fourier transform infrared spectrometer (FTIR) or based on a Raman spectrometer and be arranged to transmit in transmission or reflection, for example ATR (attenuated total reflection) measure up. In the case of an FTIR spectrometer arrangement, such a device comprises in particular an infrared radiation source which is capable of emitting the infrared radiation required for the detection. Preferably, this radiation source can emit infrared radiation in the mid-infrared spectral range. As a radiation source, for example, a globar can be used. Basically, the emission spectrum of the radiation source is to be adapted to the range in which the differences in the infrared absorption of the first polymer and the second polymer manifest themselves. Furthermore, the detection device comprises an infrared sensor, for example a photodiode, a thermal or pyroelectric detector. Furthermore, an optical arrangement based on an interferometer, which additionally has a suitable holder for the document to be examined, is typically used.

For a Raman arrangement, a laser light source as the radiation source and a high-resolution monochromator as the dispersive element and a photomultiplier for detection are used in particular. Also in this case, the optical arrangement must have a holder for the document to be examined.

The FTIR measuring device is preferably used when the document layer to be examined, in or on which the second polymer is located, is within a range of a few μm, for example up to 10 μm, below the surface of the document, since that for the examination used IR radiation can not escape from a greater depth and therefore the detection is limited to the surface area. On the other hand, if the second polymer is in or on a document layer which is at a greater distance, for example greater than 10 μm, below the surface, i. In the interior of the document, the Raman measuring arrangement is selected, which works with visible light, so that the excitation radiation and the radiation also scattered in the visible spectral range can pass through one or more other document layers. Thereby, the information about the presence of the second polymer can also be obtained from inside the document.

For example, for document capture, the entire surface of the document may be exposed to radiation, or alternatively only a portion of the surface, so that information about the identity of that portion is captured only with respect to that portion of the document's surface. The measuring arrangement can work in transmission or by superficial absorption and scattering of the unabsorbed light. In principle, it is also possible for a pattern which has been generated with the second polymer to be detected in a spatially resolved manner, so that the additional information encoded in this pattern can be detected. For this purpose, an imaging optics can be provided, or the pattern is detected by means of a scanning technique, for example by the laser beam of the required for the Raman spectrometer laser light source, for example, line by line over the surface containing the pattern and thereby sequentially obtained signal sequence are converted into an image.

Examples of the security and / or security documents according to the invention are passports, identity cards, driver's licenses, vehicle registration documents, visa, check cards, credit cards, checks, banknotes, company identity cards, credentials, membership cards, gift certificates, shopping vouchers and tokens. It is particularly preferred if the security and / or security document corresponds to the ID-1 or ID-2 format according to ISO 7810 or the data page of a document in the ID-3 format according to ISO 7810.

The security and / or security documents according to the invention are usually produced by lamination of films. The films may consist of the same or different materials, in particular polycarbonate (PC), in particular bisphenol A polycarbonate, polyethylene terephthalate (PET), its derivatives, such as glycol-modified PET (PETG), polyethylene naphthalate (PEN), polyvinyl chloride (PVC), Polyvinyl butyral (PVB), polymethyl methacrylate (PMMA), polyimide (PI), polyvinyl alcohol (PVA), polystyrene (PS), polyvinylphenol (PVP), polypropylene (PP), polyethylene (PE), thermoplastic elastomers (TPE), in particular thermoplastic polyurethane ( TPU), acrylonitrile-butadiene-styrene (ABS), paper, Teslin® and their derivatives, coextruded films containing, inter alia, these materials, as well as hybrid materials containing, among others, the above-mentioned materials. Particularly preferred are security and / or security documents which at least partially consist of PC and / or PET and / or PE and / or polymers similar thereto. The films are laminated under pressure and heat. Documents from PC are typically produced at 180 ° C to 210 ° C and at a pressure of more than 5 bar (maximum 20 bar) within 1 s to 1 h. Short cycle times are common for single card lamination, long cycle times for batch lamination of multiple uses.

According to a preferred embodiment of the present invention, in addition to the presence of the second polymer, in the method according to the invention, the presence of the first polymer is also detected by spectral analysis in the infrared range.

According to a preferred embodiment of the invention, the first polymer and the second polymer each contain a first monomer and a second monomer. The respective first monomers of the first and second polymers are identical in this embodiment and the respective second monomers of the first and second polymers are different. Although the two polymers are thus different overall, they also have certain similarities (via the first monomers), so that a user can not perceive the difference visually and without any aids.

Insofar as the term "monomer" is given in the description relating to the invention and in the claims, it includes both those for the preparation, i. Polymerization, used chemical compounds as well as after the reaction, i. Polymerization, structural units contained in the polymer, resulting from their underlying chemical compounds used to understand.

In a variant of this embodiment, it is also possible to use first and second polymers, of which at least one, for example the second polymer, consists of three, four, five or even more monomers and wherein only one of the monomers, namely the first monomer, in both polymers is identical. Alternatively, the second monomer in the second polymer may be identical to the second monomer in the first polymer. Alternatively, the first polymer may also consist of more than two monomers, namely three, four, five or even more monomers. In this case, there are several alternative possibilities, namely only the respective first monomer in both polymers is identical, and the respective second, third and further monomers are different, or the first and the respectively second monomer in both polymers are identical, and each third and further monomers are different, etc.

1. 1) AB/AB', 2) AB/AB'C', 3) AB/ABC', 4) ABC/AB'C', 5) ABC/ABC'.

Among others, the following variants result (each first term: first polymer / second term: second polymer; A, A ', B, B', C, C ': first, second, third monomer, in addition to the monomer of the first Polymer of different monomer of the second polymer, with up to three monomers in the two polymers):

1. 1) AB / AB ', 2) AB / AB'C', 3) AB / ABC ', 4) ABC / AB'C', 5) ABC / ABC '.

Of course, many other variants are possible, especially if the polymers are made up of more than three monomers. Decisive in all these Variants is that among the respective monomers of the first and the second polymer is at least one monomer of the one polymer, which is different from the corresponding other monomer of the other polymer. Therefore, each polymer will be formed by n ¹ (first polymer) or n ² (second polymer) monomers (n ¹ , n ² are integers), with at least one of the n ¹ monomers of the first polymer each having one of the n ² monomers of the second polymer are identical (identity pairs) and the others are different. Furthermore, it is to be demanded that if several pairs of identical monomers occur between the two polymers, at least one monomer of the two polymers forms no identity pair and these two polymers are thus different.

In addition to the first and second polymers, it is also possible to include in the document further polymers which in turn differ from one of the two polymers only in one or a few of the monomers, or which are completely different from the first and the second polymer.

By this selection of at least two different polymers from which or with which the document is formed, it is virtually impossible to distinguish the polymers without any aids. However, due to the two different monomers in the polymers, they are distinguishable by detection by means of infrared spectroscopy, so that verification of the authenticity of the document on the presence of the second polymer is possible, which takes place by means of spectral IR analysis.

According to a particularly preferred embodiment of the present invention, the first polymer and the second polymer are each polyester.

According to a particularly preferred embodiment of the present invention, the first monomer is selected from the group comprising terephthalic acid, isophthalic acid, phthalic acid, their derivatives and phosgene. Terephthalic acid, isophthalic acid, phthalic acid or their derivatives are used together with a diol to produce polyphthalates, with polyterephthalates using terephthalic acid as the first monomer being particularly preferred. Phosgene as the first monomer is used together with a diol to make polycarbonates.

The second monomers may be mainly diols. Particular preference is given to diols which are selected from the group comprising 4,4'-dihydroxy-2,2-diphenylpropane, geminally disubstituted dihydroxydiphenylcycloalkanes, derivatives thereof, ethylene diol and 1,4-bis (hydroxyalkyl) cyclohexane, in particular 1, 4-bis (hydroxy (C ₁ -C ₄ alkyl)) cyclohexane and most preferably 1,4-bis (hydroxymethyl) cyclohexane.

The first polymer may be, for example, polyethylene terephthalate (PET). For its preparation, terephthalic acid or a derivative thereof is used as a first monomer and ethylene diol (HO-CH ₂ CH ₂ -OH) as a second monomer. In order to provide a second polymer which is only slightly different, 1,4-bis (hydroxymethyl) cyclohexane is used as second monomer instead of ethylene diol. The resulting second polymer is then PETG. Alternatively, the second polymer may also be a copolymer of terephthalic acid with both ethylene diol and 1,4-bis (hydroxymethyl) cyclohexane. Depending on the proportion of 1,4-bis (hydroxymethyl) cyclohexane in this copolymer, the second polymer thus obtained differs more or less from the first polymer.

Alternatively, the first polymer may be polycarbonate (PC). For its preparation, phosgene is used as the first monomer and bisphenol A (4,4'-dihydroxy-2,2-diphenyl-propane) as the second monomer. In order to provide a second polymer which is only slightly different, instead of bisphenol A, a geminally disubstituted dihydroxydiarylcycloalkane, in particular dihydroxydiphenylcycloalkane, is used as second monomer. For example, the geminally disubstituted dihydroxydiphenylcycloalkane may be 4,4 '- (cyclohexane-1,1-diyl) diphenol or a derivative thereof, for example 4,4' - (3,3,5-trimethylcyclohexane-1,1-diyl) diphenol, 4,4 '- (3,3-dimethylcyclohexane-1,1-diyl) diphenol or 4,4' - (2,4,4-trimethylcyclopentane-1,1-diyl) diphenol. Alternative compounds of this type, which can be used as the second monomer instead of bisphenol A, are, for example, in DE 10 2007 052 947 A1 described. The disclosure of all polycarbonates specified therein is expressly incorporated in the present application as being in accordance with the invention. In the DE 10 2007 052 947 A1 said functional carbonate structural units of the formula (I) given there form when using the diphenols of the formula (Ia) given there. In particular, it also states that the polycarbonates may further contain other diphenols, for example Hydroquinone, resorcinol, dihydroxyphenols, bis (hydroxyphenyl) alkanes, 4,4'-dihydroxydiphenyl, 2,2-bis (4-hydroxyphenyl) -propane and other diphenols. Incidentally, reference is expressly made to the variants of the polycarbonate derivative having the formula (I) disclosed in this document. The polycarbonate described in this publication also includes, inter alia, the polymer APEC® marketed by Fa. Bayer, DE. Also, this material is expressly incorporated as the second polymer in the disclosure of the present application. Of course, the second polymer can also be formed with the additional use of bisphenol A, so that, depending on the proportion of bisphenol A in this polymer, IR properties of the second polymer which are more or less similar to those of the first polymer are obtained.

According to another preferred embodiment of the present invention, the first polymer and the second polymer differ in the degree of crosslinking. This concept of the presence of two only slightly different polymers in the value and / or security document differs from the aforementioned concept in that no different monomers are used for the preparation of the two polymers but only by selecting suitable parameters for the polymerization process the respective structural properties of the first and second polymers are different. Of course, this concept can also be combined with the aforementioned concept that partially different monomers are used to prepare the first and second polymers.

According to a particularly preferred embodiment of this second concept, the first polymer and the second polymer are each polyethylene. For example, the first polymer may be PELD (with highly branched polymer chains) and the second polymer may be PEHD (with lightly branched polymer chains).

Of course, other concepts for providing at least two or more only slightly different polymers for producing a value and / or security document are conceivable, such as polymers with different molecular weight and otherwise preferably the same composition, or polymers with different degrees of crystallinity and otherwise preferably the same Composition. Furthermore, polymer combinations can also be used in which the first and the second polymer are copolymers and the first polymer is, for example, a block copolymer and the second polymer is a random copolymer. It is, of course, essential that in each case differences in the spectral properties, in particular spectral absorption properties, of the respective first and second (and optionally third, fourth and further) polymers in the infrared range show that can be evaluated, not only the average infrared range must be used, but possibly other areas, provided that they give a suitable difference in the IR properties.

Another way to provide at least two different polymers in the document is to provide at least one document layer of a first polymer and to produce at least one second polymer in or on the first document layer by in situ modifying the first polymer , The second polymer is formed in this case from the first polymer. To this end, the first polymer is either full-surface or even localized in or on the first document layer by energy input in the presence of additional chemical agents (such as oxygen) or even without such additional agents in a chemically altered species, the second polymer converted. For example, -C (= O) - groups in a polyester polymer chain can be cleaved by energy input, so that polyether groups (-0-) arise. For example, the energy can be registered in the material of the first polymer by means of a laser over the entire area or over a limited area. Thus, it is also possible to form patterns on the surface of the first document layer. Of course, it is also possible, by introducing energy into the first polymer, to bring about a change in the modification, for example to change the crystallinity of the material. Also contemplated are chemical rearrangements that result in chemically altered species, or even chemical reactions on functional groups that occur in the presence of suitable chemical agents, such as halogenation via gaseous phase halogenating agent (e.g., bromine or iodine) in contact with the first polymer. and under irradiation with UV light.

The polymers used can be mixed with other materials to provide suitable dosage forms, such as for forming a film or for producing a Printing ink, for example, for a print, such as screen printing or inkjet printing, or color for application by other techniques. For example, colorants and fillers for the production of films and colorants, fillers, solvents, anti-foaming agents, extenders, wetting agents, surfactants, flow agents, dryers, catalysts, (light) stabilizers, preservatives, biocides, other organic polymers for viscosity adjustment, buffer systems, etc. for Production of a printing ink can be used.

According to a preferred embodiment of the present invention, the security and / or security document comprises at least a first document layer and a second document layer, wherein the first document layer at least partially consists of the first polymer and the second document layer at least partially of the second polymer. In particular, the first document layer may consist essentially of the first polymer and the second document layer essentially of the second polymer.

For example, the first polymer may form a first document layer of the document and the second polymer may form a second document layer of the document. In this case, the two document layers of the document consist almost completely of the respective polymers. For example, according to a preferred embodiment of the method according to the invention, the document may comprise an upper outer first document layer of the first polymer and a lower outer second document layer of the second polymer.

In principle, the method according to the invention may comprise the following method steps: i) optionally detecting the presence of the first polymer of the first document layer and ii) detecting the presence of the second polymer of the second document layer, wherein the first document layer is preferably the upper outer document layer and the second document layer is preferably the second document layer lower outer document layer.

Alternatively, the first polymer may be a first document layer of the document and the second polymer may be printed on the first document layer or also on any other document layer of the document accessible for measurement form otherwise applied pattern. For example, the pattern may be applied by screen printing or ink jet printing. Once again alternatively, the second polymer in the last-mentioned variant can form a pattern made in the first document layer or the other document layer of the document, for example by filling in depressions. Such depressions can be embossed, for example.

In addition to the first and the second document layer, the document usually contains further document layers, for example outer overlay foils, if the first and second document layers are not on the outside, and optionally a carrier layer and other functional document layers.

Furthermore, the second polymer can also be applied to the paper web during the production of the paper for banknotes, for example in the form of strips, but also over the entire surface or in the form of other patterns, such as diamonds, wavy lines, guilloches or the like second polymer is applied after papermaking in the production of banknotes directly or as part of an ink on the banknote paper. Thus, according to a preferred embodiment of the method according to the invention, a material essentially consisting of the second polymer is in the form of a pattern on or in at least one first document layer or the other document layer consisting essentially of the first polymer.

The information encoded in the pattern may be a value of the document or an identifier for example for the owner. The pattern may be formed by any symbols. By way of example, the pattern can be a one-dimensional or two-dimensional barcode or, for example, it can also encode either plain-text or encoded characters.

Also in this case, the method according to the invention may comprise the following method steps: i) optionally detecting the presence of the first polymer of the first document layer and ii) detecting the presence of the second polymer of the sample. If the pattern is scanned, for example line by line, the code can be read and the information encoded therein can be captured.

In a further embodiment of the invention, the first polymer may form a first document layer and the second polymer may form a localized area at a defined location of the document on or in the first document layer or on or in another document layer of the document limited area completely or only partially, for example in the form of a pattern can fill. Of course, however, this can also be realized in that an entire second document layer consists of the second polymer and can be detected from the outside only in a localized area via a window permeable to the IR detection. In this case, it is additionally necessary for the detection of the presence of the second polymer that the area of the document in which the second polymer is or is expected to be examined is investigated. In a forgery, the second polymer may optionally be present in a different range and therefore can not be detected by the method according to the invention.

Of course, combinations of the abovementioned variants can also be realized, for example a first document layer of a first polymer, a second document layer of a second polymer, a pattern of the second polymer embedded in the first document layer and / or a pattern embedded in the second document layer the first polymer, wherein one of the two patterns or both are optionally additionally present only at localized locations of the respective document layer and thus provide further information about the location of the second polymer.

According to a particularly preferred embodiment of the method according to the invention, the presence of the first and the second polymer in the process steps i), namely detecting the presence of the first polymer, and ii), namely detecting the presence of the second polymer, in each case at least one predetermined spectral position , detected. In this case, a first absorption caused by the first polymer and a second absorption caused by the second polymer are determined. In a third method step iii), the first and the second absorption are then determined. The first absorption and the second absorption are preferably compared in a fourth method step iv). For this purpose, the respective attenuation of the radiation is determined in the form of the respective extinction values.

In still another preferred embodiment of the present invention, in step iii) an index is formed which results from the first absorption (attenuation of the radiation) and the second absorption (attenuation of the radiation), for example the quotient of the first absorption and the second absorption , This measure indicates whether or not the second polymer is actually present, thus giving the authenticity of the document.

Alternatively, only the absorption of the second polymer in the document can be detected. The presence of the second polymer in this case is indicated by an absorbance in a suitable wavelength range.

Again, alternatively, the shift of an IR band can be detected to determine if the second polymer is present in the document.

Fig.1:

eine schematische Darstellung einer Erfassungsvorrichtung für das erfindungsgemäße Verfahren;

Fig. 2:

ein Dokument mit einer ersten Dokumentenlage aus einem ersten Polymer, die einen aus einem zweiten Polymer gedruckten Barcode aufweist;

Fig. 3:

ein Vergleich von zwei IR-Spektren, aufgenommen mit einer FTIR-Messanordnung.

The figures given below serve to illustrate the invention. They merely illustrate embodiments. They show in detail:

Fig.1:

a schematic representation of a detection device for the inventive method;

Fig. 2:

a document having a first document layer of a first polymer having a bar code printed from a second polymer;

3:

a comparison of two IR spectra taken with an FTIR measurement setup.

Elements with the same function are designated in the figures with the same reference numerals.

Fig. 1 shows a detection device based on a FTIR measuring arrangement. The document is designated 1. It is held by a document holder 2. The document holder 2 has an opening at the bottom so that measuring radiation can reach the document 1 from below. A radiation source 4 emits IR radiation in the middle frequency range. This radiation is initially passed through a beam splitter 5 via an optical arrangement (Michelson interferometer) and arrives At the same time radiation also passes through the beam splitter 5 on a movable mirror 7. The radiation of both radiation paths is then passed through a further mirror 8 on the document 1. The scattered radiation is detected in the detector 3 and in a downstream evaluation system (not shown).

In Fig. 2 An example of a document 10 having a first document layer 11 of a first polymer (bisphenol A based polycarbonate) is shown. This document layer is one of several document layers in the document. It is located at the surface of the document. In order to be able to detect the presence of a second polymer in the present case, an FTIR measuring arrangement is used.

On the first document layer 10 is applied a bar code 12 which has been printed with a printing ink containing a second polymer which differs from the first polymer only in the modification of the bisphenol A used. This barcode 12 is virtually invisible to the naked eye because both polymers look identical. However, the difference between the two polymers can be detected with the FTIR measuring arrangement. For this purpose, the barcode 12 is scanned line by line, so that on the one hand, the coded in the barcode 12 information can be detected. For this purpose, the fact is exploited that the IR absorption in the area of the barcode strip differs from that between the strips. On the other hand, according to the invention, the identity of the two polymers is detected.

In Fig. 3 For example, two IR spectra are shown, with the first polymer denoted PC1 and the second polymer PC2. The spectrum of PC1 is recorded at a location of the first document layer 10 where the barcode 12 is not printed and the spectrum of PC2 at the location of the barcode 12.

Both polymers show significant differences in the IR spectrum, it being noted that the spectrum shown here represents only a small portion of the entire IR spectrum from 4000 cm ^-1 to 400 cm ^-1 . In the remaining IR spectral range, the two spectra are virtually identical, so that no differences would be found when the document was examined by IR spectroscopy. The intensity plotted on the ordinate is the radiation intensity detected by the detector.

PC1 and PC2 are polycarbonate materials based on cyclohexane-modified bisphenol A.

In the wavenumber ranges indicated by the arrows, it can be determined whether the second polymer PC2 is present. For this purpose, either measuring points of both polymers can be evaluated, or it is only the measuring point of the barcode 12 alone checked for the presence of the second polymer. The differences in the measured intensity can be used to determine if the second polymer is present. When determining the intensity of the radiation of both polymers in at least one of the wave number ranges indicated here, it is also possible to form an intensity quotient Q _I (v), for example the intensity I ₁ which is obtained when the first polymer PC1 is measured at a certain wavenumber the intensity I _{2 obtained} in the measurement of the second polymer PC2 at the same wavenumber: Q _I (V) = I ₁ / I ₂ . Its size is a measure of whether the second polymer is present or not. In order to determine the critical size for verifying the authenticity of a document containing the polymer PC2 in the form of the barcode, the corresponding spectra are determined on genuine documents, and thus reference quotients are formed. In any case, the value for Q _I (v) must be different from 1 in the real document, because if Q _I (v) = 1, this means that the material of the barcode is identical to that of the rest of the document.

Claims (5)

Method for verifying the authenticity of a value and / or security document comprising at least one document layer containing a first polymer, wherein a second polymer other than the first polymer is located in or on one of the at least one document layer,
the method comprising the step of: verifying the authenticity of the document by detecting the presence of at least the second polymer by infrared spectral analysis,
characterized in that the second polymer is produced by in situ modifying the first polymer. A method according to claim 1, characterized in that the presence of the second polymer is detected by detecting the presence of an IR band characteristic of the second polymer. A method according to claim 2, characterized in that the presence of the characteristic IR band of the second polymer is detected by means of an IR or Raman spectrometer. Method according to one of the preceding claims, characterized in that the document is detected by detecting the presence of the first polymer and the presence of the second polymer by spectral analysis in the infrared range. Method according to one of the preceding claims, characterized in that the second polymer is in the form of a pattern on or in at least one document layer consisting essentially of the first polymer.

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