Method for marking and identification of products

Abstract

The present invention relates to a method for identifying products with the aid of an ink formulation which contains semiconductive inorganic nanocrystals which emit radiation in the range of 750-1800 nm when excited by photons, in serialisation and / or track-and-trace systems.

Description

[0001] The present invention is based on a method for marking products using an ink formulation containing semiconducting inorganic nanocrystals that emit radiation in the range of 750-1800 nm under photon excitation, in serialization and / or track & trace systems. Technical background

[0002] Counterfeit products cause worldwide economic damage amounting to several hundred billion US dollars. In Europe alone, counterfeit products cause economic damage of more than 80 billion euros. The range of counterfeit products is immense. Cosmetics, watches, tobacco, and medical products are increasingly being counterfeited. In 2019, the pharmaceutical and tobacco industries introduced a serialization system to monitor their products, in accordance with EU regulations (2011 / 62 / EU and 2014 / 40 / EU). Each product package is given a special, unique code, which is stored in a central database. This presents several problematic scenarios: Hacking the database. It should be noted that no IT system can be completely protected against hacker attacks by third parties. Hackers can either save / add their own codes to the central database or steal the unique codes of other companies. This makes it impossible to verify which product is a counterfeit and which is the original. Passing on the codes to third parties. The unique codes can be passed on by personnel to third parties. These third parties can then print the codes on the counterfeit products, making them "genuine" according to the database. Transferring the codes to another packaging. Once the code is transferred from the original packaging to the packaging of the duplicate and the original packaging is disposed of, counterfeit products can be sold as original products.This fraud is difficult to trace because the database system confirms that the product in question is not a counterfeit. This risk scenario could occur, for example, in the repackaging of stolen products / medications, or in the illegal trade of products online or with smuggled goods.

[0003] Due to these three critical points, it is very important to establish an additional (physical) security feature in the unique code. The present invention addresses precisely this issue. This invention thus represents a combination of track & trace technology and optical security features. This unifies the traceability and authentication processes of products.

[0004] Regarding product counterfeit security, two competing solutions have been developed in recent years: track & trace and authentication solutions, especially optical ones.

[0005] Track & Trace programs (US 9,027,147; US 8,898,007; US 2009 / 0096871; US 8,700,501) are used to ensure the clear tracking and tracing of all process steps in the production and supply chain. They also enable comprehensive control options for the manufacturer and transparency for the consumer, as the locations and routes of products can be seamlessly documented.

[0006] The interplay of anti-counterfeiting and design is fundamentally important for authentication solutions. Highly decorative and innovative authentication solutions are sometimes used to protect consumers from tampering. These include authentication solutions that are both visible and invisible to the human eye.

[0007] An authentication solution invisible to the human eye utilizes organic dyes from the near-infrared (NIR) range (EP 0 933 407; US 5,282,894; US 5,665,151; WO 1998 / 018871; WO 2003 / 038003; US 10,119,071; US 5,542,971). However, these organic NIR dyes exhibit several disadvantages, such as a low quantum yield below 20%, low thermal stability, and high susceptibility to external influences such as oxidation or photobleaching, which often causes these dyes to lose more than 50% of their original fluorescence intensity (quantum yield) even with low irradiation exposure.

[0008] For authentication solutions, research is also being conducted on novel materials such as quantum dots and / or perovskites, which also fluoresce in the NIR range (US 9,382,432; US 6,383,618; WO 2007 / 131043; Adv. Mater. (2005), 17, 5, 515; J. Am. Chem. Soc. (2008), 130, 9240; Analyst (2010), 135, 1867; Adv. Mater. (2019), 31, e1806105).

[0009] WO 2008 / 053202 A2 discloses a method for marking and identifying products.

[0010] The present invention is based on the concept that the optical security feature is invisible to the human eye and can only be detected with the help of optical detection systems (e.g. spectrometers or NIR camera systems) and possibly mobile devices (e.g. smartphones, tablets, etc.) or other corresponding reading devices. NIR rays are emitted by inorganic materials. This optical security feature is undetectable to the human eye by a product counterfeiter. Only after excitation with higher energy than the emission signal (e.g. blue and / or white light), which is generated, for example, by end devices such as smartphone or tablet flashes or correspondingly equipped reading devices, as well as higher-energy NIR radiation, does the optical security feature emit NIR radiation. This is detected by the reading device.

[0011] The inorganic materials used are characterized by high stability against environmental influences and a special excitation and emission pattern that allows optical excitation and detection using commercially available devices such as smartphones or tablets. Furthermore, these materials exhibit a high quantum yield of over 20%, which is necessary for detection using such devices.

[0012] Products labeled in this way are more counterfeit-proof, as counterfeiters would have to synthesize the respective inorganic materials, disperse them in the respective ink formulations, and print the corresponding codes. Furthermore, the inorganic material used can be directly identified with the help of software (e.g., a spectrometer for smartphones). Subject of the invention

[0013] The present invention relates to a method according to claim 1.

[0014] The term "products" in the sense of the present invention includes the products themselves, insofar as they can be marked, their packaging, product tags, barcode cards and barcode labels, as well as all other possibilities with which a product would usually be marked during the production process and / or transport, including the documentation.

[0015] The term "ink formulation" in the sense of the present invention includes any solvent and combinations thereof as well as typical additives suitable for producing a printable liquid.

[0016] The term "printing" in the context of the present invention encompasses the deposition of pigments onto or into a solid substrate. Typical examples include, but are not limited to, digital printing, inkjet printing, screen printing, transfer printing, stamp printing, roll-to-roll printing, non-contact printing, laser printing, and other processes. Figures

[0017] Figure 1 shows an overview of a possible embodiment of the method according to the invention for labeling products. Figures 2 ad show examples of the inventive method for marking products using a one-dimensional code. Figures 2 ac show printed one-dimensional codes with inventive ink formulations with different print resolutions on white cardboard ( Figure 2 a: 350 dpi, Figure 2 b: 400 dpi, Figure 2 c: 450 dpi). Figure 2d shows the emission pattern of the one-dimensional code from Figure 2 c Figures 3 ac show examples of the inventive method for marking products using a two-dimensional code. Figures 3 ac show printed two-dimensional codes with inventive ink formulations with different print resolutions on white cardboard ( Figure 3 a: 400 dpi, Figure 3 b: 450 dpi, Figure 3c: 500 dpi).

[0018] The Figures 4 from show examples of individual printing inaccuracies or printing defects of a single printer, which can be used as an individual and unique pattern to generate a unique code. Detailed description of the invention

[0019] The present invention relates to a method according to claim 1.

[0020] First, an ink formulation is provided that contains semiconducting inorganic nanocrystals that emit radiation in the range of 750-1800 nm under photon excitation

[0021] The ink formulation is preferably a commercially available ink formulation suitable for the deposition of pigments onto or into a solid substrate. Typical examples include, but are not limited to, digital printing, inkjet printing, screen printing, transfer printing, stamp printing, roll-to-roll printing, non-contact printing, laser printing, and other processes.

[0022] This ink formulation may already contain color pigments. This makes the unique code printed with the ink formulation visible to the human eye. The detection of the radiation emitted by the irradiated product in the range of 750-1800 nm thus provides an additional optical security feature in addition to the visible unique code.

[0023] In another embodiment, the ink formulation contains no additional color pigments other than the semiconducting inorganic nanocrystals. In this embodiment, the unique code printed with the ink formulation is invisible to the human eye due to the concentration of the ink formulation. The unique code is therefore not immediately visible but can only be detected and read after irradiating the product printed with the ink formulation with photons by detecting the radiation emitted by the irradiated product in the range of 750-1800 nm.

[0024] In a third embodiment, a unique code is first printed on at least one surface of the product using a commercially available ink formulation. In a second step, the ink formulation containing the semiconducting inorganic nanocrystals is then printed in dots onto the existing unique code in the form of droplets and / or in the form of another unique code. In this embodiment, the ink formulation according to the invention preferably contains no pigments, so that the droplets and / or the another unique code are not visible to the human eye.

[0025] In a fourth embodiment, the unique code according to any one of the preceding embodiments is printed on at least one label, which is then adhered to at least one surface of the product.

[0026] In a fifth embodiment, the unique code according to any one of the first three embodiments is printed on product tags, barcode cards and / or barcode labels.

[0027] In a fifth embodiment, the ink formulation contains two or more, for example 2, 3, 4, 5, 6, or 7, differently emitting semiconducting inorganic nanocrystals as well as additional color pigments. In this embodiment, the unique code printed with the ink formulation is visible to the human eye. The detection of the radiation emitted by the irradiated product in the range of 750-1800 nm is thus a further optical security feature in addition to the visible unique code. Both the different emission maxima and the respective (intensity) ratios can also be stored in at least one database. In a sixth embodiment, the ink formulation contains two or more, for example 2, 3, 4, 5, 6, or 7, differently emitting semiconducting inorganic nanocrystals without additional color pigments.In this embodiment, the unique code printed with the ink formulation is invisible to the human eye due to its concentration. The detection of the radiation emitted by the irradiated product in the range of 750-1800 nm thus provides an additional optical security feature in addition to the visible unique code. Both the different emission maxima and the respective (intensity) ratios can also be stored in at least one database.

[0028] The semiconducting inorganic nanocrystals are preferably selected from the group of perovskites, I-VI semiconductors, II-VI semiconductors, III-V semiconductors, IV-VI semiconductors, I-III-VI semiconductors, carbon dots and mixtures thereof.

[0029] Examples of suitable semiconducting inorganic nanocrystals include AgS, AgSe, AgTe, CdS, CdSe, CdTe, PbS, PbSe, PbTe, SnTe, ZnS, ZnSe, ZnTe, InP, InAs, Cu2S, In2S3, InSb, GaP, GaAs, GaN, InN, InGaN,ZnSSe, ZnSeTe, ZnSTe, CdSSe, CdSeTe, HgSSe, HgSeTe, HgSTe, ZnCdS, ZnCdSe, ZnCdTe, ZnHgS, ZnHgSe, ZnHgTe, CdHgS, CdHgSe, CdHgTe, ZnCdSSe, ZnHgSSe, ZnCdSeTe, ZnHgSeTe, CdHgSSe, CdHgSeTe, CuInS2, CuInSe 2 , CuInGaSe 2 , CuInZnS 2 , CuZnSnSe 2 , CuIn(S,Se) 2 , CuInZn(S,Se) 2 , AgIn(S,Se) 2 .

[0030] Further suitable examples, but not limited to, are perovskite materials having the general formula ABX 3 or A 4 BX 6 , where X can be selected from Cl, Br, I, O and / or mixtures thereof, where A can be selected from Cs, CH 3 NH 3 , CH(NH 2 ) 2 , Ca, Sr, Bi, La, Ba, Mg and / or mixtures thereof, where B can be selected from Pb, Sn, Sr, Ge, Mg, Ca, Bi, Ti, Mn, Fe and / or mixtures thereof.

[0031] Furthermore, core / shell and / or core / multishells of semiconducting inorganic nanocrystal architectures of II-VI, III-V, IV-VI, I-VI, I-III-VI semiconductors or mixtures thereof as well as core / shell and / or core / multishells of perovskite materials are further suitable examples.

[0032] The crystal lattice of the semiconducting inorganic nanocrystals may additionally, but not exclusively, be doped with one or more metal ions, such as Cu +< , Mg 2+< , Co 2+< , Ni 2+< , Fe 2+< , Mn 2+< and / or with one or more rare earth metals, such as ytterbium, praseodymium or neodymium.

[0033] The semiconducting inorganic nanocrystals preferably have an average particle size of 1 nm to 100 nm, more preferably of 2 nm to 50 nm, and most preferably of 3 nm to 15 nm in at least one dimension, preferably in all dimensions.

[0034] The average particle size can be further increased or modified using various methods. Typical examples include, but are not limited to, a silica shell, a titanium oxide shell, a halogen shell, as well as other methods for increasing stability, masking, biocompatibility, water solubility, and / or encapsulation.

[0035] The semiconducting inorganic nanocrystals are preferably photoluminescent substances that are brought into electronically excited energy states by light absorption and then return to lower energy states by emitting light in the form of fluorescence.

[0036] The semiconducting inorganic nanocrystals are preferentially excited by visible light, such as blue or white light, as well as higher energetic NIR radiation than the emission signal (excitation).

[0037] The semiconducting inorganic nanocrystals emit radiation with a wavelength in the range of 750 to 1800 nm, more preferably 800 to 1400 nm, and most preferably 850 nm to 1100 nm, upon photon excitation. These wavelength ranges are in the invisible near-infrared range.

[0038] One of the interesting properties of the semiconducting inorganic nanocrystals for the present invention is that their excitation and emission spectrum depends, among other things, on their particle size.

[0039] The proportion of semiconducting inorganic nanocrystals in the ink formulation is preferably 0.01 to 70.0 wt.%, more preferably 0.05 to 40.0 wt.%, and most preferably 0.1 to 30.0 wt.%, based on the total weight of the ink formulation. For digital and inkjet printing, a range between 0.01 and 10.0 wt.% is preferred.

[0040] The ink formulation may contain semiconducting inorganic nanocrystals that have at least one or all, preferably all, of the following properties in common: emission wavelength, emission distribution, and emission maximum. In another embodiment, the ink formulation may contain mixtures of semiconducting inorganic nanocrystals that have different values for emission wavelength, emission distribution, and emission maximum.

[0041] Furthermore, the ink formulation can contain the color pigments of commercial inks. Commercial ink formulations can be used and mixed with the semiconducting inorganic nanocrystals.

[0042] The emitted radiation of the ink formulation can result in an individual fluorescence spectrum that depends on the type, quantity and particle size of the semiconducting inorganic nanocrystals.

[0043] The individual fluorescence spectrum can be detected with a spectrometer. The detected individual fluorescence spectrum can then be compared with a reference spectrum stored in a database.

[0044] In addition, this individual fluorescence spectrum can be used as an additional security feature for an ink formulation individually mixed by the product manufacturer.

[0045] The ink formulation for, for example, ink-jet printing preferably has a reciprocal Ohnesorg number of less than 14, more preferably from 1 to 10, even more preferably from 1 to 8 and most preferably from 2 to 4.

[0046] In a further step, a unique code is generated to identify a product.

[0047] For this purpose, preferably at least one reference value, preferably several reference values of the product are first encrypted using a unique key.

[0048] Possible reference values include, for example, reference values relating to the type and nature of the product, such as serial numbers, lot numbers, CAS numbers for chemical products, the place of production, the time of production, the place of delivery, the producer, the supplier, the customer or similar.

[0049] The unique key can be an algorithm provided to the producer or created by the producer himself.

[0050] Encryption generates a code that is unique for the product, preferably for the individual packaging unit of the product.

[0051] This unique code can be a one-dimensional code, such as a barcode, a two-dimensional code, such as a QR code, or a three-dimensional code, such as a color barcode. The unique code can also contain one or more patterns, such as areas, stripes, lines, geometric figures such as circles, triangles, rectangles, polygons, etc., alphanumeric characters, images, or combinations thereof.

[0052] Furthermore, it is possible to extract / derive a unique code from random, arbitrary processes, such as printing inaccuracies and printing defects during the inventive method step of printing the ink formulation onto at least one area of the surface of the product.

[0053] Superficially, the print usually shows no production inaccuracies. However, looking at the micrometer scale, an individual pattern is usually recognizable. This can be caused, for example, by blockages of the print nozzles, partial blockage of the print nozzles, deflection of the ink droplets, or a delayed release of the ink droplet from the print nozzle. This creates a random pattern at the micrometer level, which is unique for each printing process (fingerprint). This is shown as an example in the Figures 4 a and b are visualized. This unique pattern can be extracted using IT applications into a unique code, which can also be stored in encrypted form in the database. This form of unique code can also be used to specifically individualize individual items, for example, individual species from a multi-unit product series.

[0054] In one embodiment, an already established unique code can be printed on at least one surface of a product using the ink according to the invention. The individual pattern achieved by printing inaccuracies and printing defects during this process step of printing the ink formulation onto at least one surface of the product can then be used as an additional optical security feature and optionally stored in a database. In this embodiment, the process step according to the invention Generating a unique code for identifying a product; prior to the process step of printing the ink formulation onto at least one area of the surface of the product in the form of this unique code.

[0055] The method according to the invention of this embodiment is then subsequently carried out by the process steps Extracting an individual pattern caused by printing inaccuracies and print defects during printing of the unique code; and optionally storing the individual pattern in at least one database.

[0056] In a further embodiment, the unique code can be derived from the pattern printed with the ink formulation according to the invention. A pattern as described herein is first printed onto at least one surface of the product. This pattern is then analyzed for printing inaccuracies and printing defects, and an individual pattern is derived from it. This individual pattern can then be linked to the product's reference values as described herein and used as a unique code, optionally stored in a database.

[0057] In this embodiment, the method step according to the invention Generating a unique code for identifying a product; after the process step, printing the ink formulation onto at least one area of the surface of the product in the form of this unique code.

[0058] The method according to the invention in this embodiment thus comprises the following process steps in the specified chronological order: Printing the ink formulation onto at least one surface of the product in the form of a unique code derived from an individual pattern caused by printing inaccuracies and printing defects during printing; generating the unique code for identifying a product by encrypting at least one reference value of the product using the individual pattern as a unique key.

[0059] This unique code from the individual pattern of printing inaccuracies and printing defects can also be encrypted, combined and / or encrypted and / or stored with another unique code created using conventional methods and containing further reference values of the product.

[0060] These two unique codes can be treated as individual unique codes, so that two unique codes are printed on the product, encoding different reference values of the product and stored and detected as independent individual codes. Both individual codes can be printed using the ink formulation according to the invention. However, the second unique code, created using conventional methods, can also be printed using a conventional ink formulation.

[0061] These two unique codes can also be combined into a single unique code by generating a combined unique code from the two individual unique codes as a one-dimensional code, two-dimensional code, or three-dimensional code as described herein. This combined unique code can then be printed onto the product using the ink formulation according to the invention. This embodiment thus comprises two staggered printing processes using the ink formulation according to the invention, in the following chronological order: Printing the ink formulation on at least one area of the surface of the product in the form of a unique code consisting of an individual pattern caused by printing inaccuracies and printing defects during printing; generating the unique code for identifying a product by encrypting at least one reference value of the product using the individual pattern as a unique key; combining the unique code with another unique code to form a combined unique code; printing the ink formulation on at least one area of the surface of the product in the form of this combined unique code, and optionally storing the combined unique code in at least one database.

[0062] The ink formulation is printed on at least one surface of the product in the form of this unique code. Preferably, each unit of the product is printed with its own unique code.

[0063] The step "printing the ink formulation on at least one area of the surface of the product in the form of this unique code" includes both the printing of the ink formulation directly on at least one area of the surface of the product, insofar as the nature of the product allows this, as well as the printing of the ink formulation on at least one label in the form of this unique code and the affixing / labelling of the surface of the product with at least one printed label.

[0064] If the shape and / or physical nature of the product does not allow direct marking, the step of "printing the ink formulation on at least one surface of the product in the form of this unique code" may also include printing the ink formulation directly on at least one surface of the product's packaging or applying / labelling the product's surface with at least one printed label.

[0065] Standard printing methods are applicable, depending on the type of ink formulation. The ink formulation is preferably printed onto at least one surface of the product using digital printing, screen printing, transfer printing, roll-to-roll printing, non-contact printing, or laser printing.

[0066] Depending on the type of product, the unique code can be printed directly on the surface of the product, on the product packaging, as well as on labels, signs, barcode cards and / or barcode labels.

[0067] In addition to the unique code, the ink formulation can also be printed in other patterns, such as solids, stripes, lines, geometric shapes such as circles, triangles, rectangles, polygons, etc., alphanumeric characters, or combinations thereof, on at least one surface of the product. The printed pattern can serve as a pure authentication feature or contain information such as safety and usage instructions or manufacturer's information.

[0068] In a further step, the product printed with the ink formulation is irradiated with photons.

[0069] Photon irradiation brings the semiconducting inorganic nanocrystals contained in the ink formulation into excited energy states (excitation).

[0070] The product printed with the ink formulation is irradiated with blue or white light.

[0071] The light source can be a halogen lamp or LED lamp, preferably a blue or white LED lamp. Another suitable light source for irradiation is an LED flash, such as the LED flash of a device such as a smartphone or tablet.

[0072] After irradiation, the irradiated product, preferably the semiconducting inorganic nanocrystals in the ink formulation, emits radiation in the range of 750 to 1800 nm, preferably 800 to 1400 nm, most preferably 850 nm to 1100 nm. This is detected in a further step.

[0073] The emitted radiation can be detected with any suitable detection device. The emitted radiation is preferably detected by a terminal device, such as a smartphone or tablet. The camera systems of these devices typically have a silicon-based image sensor that can detect incoming photons up to a wavelength of approximately 1100 nm. Thus, the radiation emitted by the semiconducting inorganic nanocrystals can be detected by these image sensors.

[0074] In order to be excited and / or detected by a terminal device, such as a smartphone or tablet, the photoluminescent substance, preferably the semiconducting inorganic nanocrystals in the ink formulation, must have a high quantum yield.

[0075] The semiconducting inorganic nanocrystals in the ink formulation preferably have a quantum yield in the range between 20 and 100%, more preferably in the range between 40 and 100%, most preferably 60 and 100%. The quantum yield or quantum efficiency indicates the ratio between the number of emitted and absorbed photons.

[0076] Depending on the specific embodiment of the unique code printing process, as described above, the unique code can also be read using commercial barcode scanners if the unique code is visible to the human eye. In this embodiment, the detection of the radiation emitted by the semiconducting inorganic nanocrystals serves as an additional security feature.

[0077] The method according to the invention thus has the advantage of being usable by end consumers without any additional financial outlay. This provides retailers and end consumers with a simple and cost-effective method for verifying the authenticity of a product. The method according to the invention can thus be used as an optical-based authentication solution.

[0078] The method can also be used in serialization and / or track & trace systems.

[0079] Serialization maps structured data into a sequential representation. Serialization is primarily used for transferring objects over the network in distributed software systems.

[0080] For use in serialization systems, the following additional steps are preferred: Storing the unique code in at least one database; querying the detected unique code from the at least one database to verify the product.

[0081] In advanced serialization systems, one or more reference values of a product can be recorded and / or encrypted using a unique key. A corresponding serialization and / or track & trace computer program generates a unique code, which is printed on the product. The code is also stored in a database, preferably a central database. The code can then be scanned at any time and read from the database. The encrypted reference values of the product can then be read using the serialization and / or track & trace computer program.

[0082] For use in track & trace systems, it is further preferred that the ink formulation is additionally printed in the form of the unique code on at least one area of the surface of a packaging group containing the product, for example selected from bundles, outer packaging, pallets.

[0083] This enables seamless tracking of the product throughout the production and transport process of each individual product.

[0084] The present method therefore represents a combination of Track & Trace technology and optical security features.

[0085] Traceability process and product authentication process combined.

[0086] Figure 1 shows an overview of a possible embodiment of the method according to the invention.

[0087] In a first step, reference values of a product, such as the production location and period, product ingredients, dosage forms, etc., are encrypted using a unique key. A track & trace computer program then generates a code from these encrypted reference values. This code can be a one-dimensional, two-dimensional, or three-dimensional code, e.g., a barcode, a QR code, or a color barcode.

[0088] This code is stored in a central database via the Track & Trace computer program.

[0089] In the next step, the code is printed onto the surface of the product using the ink formulation disclosed herein. This ink formulation preferably contains additional color pigments in addition to the semiconducting inorganic nanocrystals, so that the printed code is visible to the human eye. Depending on the product, the code can be printed directly onto the surface of the product or onto the product packaging.

[0090] The code printed using the ink formulation disclosed herein can now be used in two ways, firstly as a track and trace marking and secondly as an optical authentication marking.

[0091] In a serialization or track & trace system, the code can be read with a scanner. The code is then transferred to the track & trace computer program. The code is then read from the database and decoded. This provides the reference values of the marked product.

[0092] The code and any other possible markings using the ink formulation disclosed herein may also be used as optical authentication markings.

[0093] For this purpose, the surface of the product is irradiated with light, preferably white or blue light, preferably white or blue LED light. The photoluminescent substance, preferably the semiconducting inorganic nanocrystals in the ink formulation, are excited as discussed above and then emit fluorescent radiation in the range of 750–1800 nm (NIR radiation). This radiation cannot be perceived by the human eye. Instead, an electronic device capable of detecting NIR fluorescent radiation is required for detection. Suitable devices include spectrometers, NIR cameras, and also end devices such as smartphones or tablets, which have a silicon-based image sensor in their camera systems that can detect incident photons up to a wavelength of approximately 1100 nm. These end devices can also be used to excite the photoluminescent substance via the camera flash.

[0094] The flash for excitation and detection can be controlled via a corresponding app, so that after excitation and detection, a corresponding photo of the code appears on the device's screen. This photo thus serves as a visual authentication feature and allows the product to be authenticated.

[0095] The method according to the invention thus extends a serialization or track & trace system with an optical security feature that is not visible to the human eye.

[0096] This optical security feature can be detected by simple means that are also available to the end consumer, thus enabling simple and cost-effective authentication.

[0097] The semiconducting inorganic nanocrystals used have a high quantum yield and are insensitive to temperature fluctuations, oxidation and photobleaching.

[0098] Security can be further enhanced by using a specific blend of semiconducting inorganic nanocrystals with a specific particle size distribution and proportions in the ink formulation, which emits a specific fluorescence spectrum in the NIR range that can be detected using a spectrometer. This specific fluorescence spectrum can, in turn, be used as an additional authentication feature.

[0099] Compared to other authentication features such as RFID chips or holograms, the method according to the invention also has a clear cost advantage.

[0100] The present invention also relates to an optical security feature on at least one area of the surface of a product in the form of a unique code containing semiconducting inorganic nanocrystals which emit radiation in the range of 750-1800 nm upon photon excitation.

[0101] Furthermore, the invention relates to an optical security feature on at least one area of the surface of a product containing semiconducting inorganic nanocrystals which emit radiation in the range of 750-1800 nm when excited by photons.

[0102] The optical security feature is preferably printed on at least one surface of the product using the method according to the invention.

[0103] The present invention further relates to a serialization and / or track & trace system that includes an optical security feature comprising a unique code printed on a product as described herein.

[0104] In addition, the invention relates to the use of a unique code printed on a product as described herein as an optical security feature in a serialization and / or track & trace system.

[0105] The unique code is printed on the product or product packaging using the ink formulation described herein, which contains semiconducting inorganic nanocrystals that emit radiation in the range of 750-1800 nm when photon excited.

[0106] The features of the code, the ink formulation and the semiconducting inorganic nanocrystals described herein are also applicable to the optical security feature according to the invention, the serialization and / or track & trace system according to the invention and the use according to the invention.

[0107] The features of the serialization and / or track & trace system described herein must also be applied.

[0108] The Figures 2 ad show examples of a one-dimensional barcode printed on white cardboard. Figures 3 ac show further examples of a two-dimensional QR code printed on white cardboard.

[0109] The ink formulation had the following components: 12 mL 1-decanol 8 mL 1-octanol 100 mg lead sulfide nanoparticles The proportion of inorganic nanocrystals in the ink formulation is thus 0.6%. The viscosity of this ink formulation is 11 mPa*s.

[0110] Printability is crucial for ink formulations. This is defined by the reciprocal Ohnesorge number. If this value is greater than 14, the ink formulation is unsuitable for inkjet (digital) printing. Ohnesorge numbers between 1 and 10 are acceptable for inkjet technology. However, values between 2 and 4 are optimal.

[0111] This Ohnesorge number is mainly determined by the viscosity and surface tension of the ink formulation.

[0112] In the Figures 2 ac A barcode was printed using an inkjet printer in different resolutions of 350 dpi ( Fig. 2 a) , 400 dpi ( Fig. 2 b) and 450 dpi ( Fig. 2 c) printed. The color pigments in the ink formulation ensure that the code is always visible to the human eye.

[0113] The code of the Figure 2 c was additionally illuminated with white LED light and the emitted radiation was detected in the NIR range. Figure 2d shows a picture of the fluorescence radiation emitted by the ink formulation in the NIR range.

[0114] In the Figures 3 ac A QR code was printed using an inkjet printer in different resolutions of 400 dpi ( Fig. 3 a) , 450 dpi ( Fig. 3 b) and 500 dpi ( Fig. 3 c) printed. The color pigments in the ink formulation ensure that the code is always visible to the human eye.

[0115] The higher the resolution, the better the code is recognizable.

[0116] Figures 4a and b show examples of individual printing inaccuracies or printing defects of a single printer, which can be used as an individual and unique pattern to generate a unique code. The print image in Figure 4 a was produced using an LP50 printer from Süss MicroTec and a Spectra SE128 AA printhead from Fujifilm. The ink formulation was Spectra Test Ink Blue, also from Fujifilm. The images were taken with the LP50's Printview camera. The graduations of the "crosshairs" have a scale of 100 µm. The substrate was photographic paper. Within a row of printed dots, an individual pattern of height shifts is evident. In particular, the third-to-last printed dot in a row exhibits a significant height difference from its neighboring dots.

[0117] The print image in Figure 4 bwas produced using an LP50 printer and a Spectra SE128 AA printhead. The ink formulation was a mixture of SPR001 (a commercial fluorescent polymer from Merck), chlorobenzene, mesitylene, and tetralin. Images were taken with a Basler acA 1300gc camera (lens focal length: 200mm) at 2x magnification. Image section: 6x4mm. The substrate was photographic paper. Within a series of printed dots, an individual pattern of height shifts, defects, and omissions is evident at a lower magnification than in Figure 4 a.

Claims

1. Method for marking and identification of products including the following steps: - providing an ink formulation containing semiconducting inorganic nanocrystals that emit radiation in the range from 750-1800 nm, preferably from 800 to 1400 nm, most preferably from 850 nm to 1100 nm, upon photon excitation; - generating a unique code for identification of a product; - printing the ink formulation on at least one face of the product surface in the form of said unique code; - irradiating the product that was printed with the ink formulation to excite with blue or white light; - detecting the radiation emitted by the irradiated product in the range from 750-1800 nm, preferably from 800 to 1400 nm, most preferably from 850 nm to 1100 nm.

2. Method according to Claim 1, further including the following steps: - storing the unique code in at least one database; - retrieving the detected unique code from the at least one database for verification of the product.

3. Method according to Claim 1 or 2, wherein the ink formulation is also printed on at least one face of the surface of a packaging group containing the product, selected for example from bundles, secondary packaging, pallets, in the form of the unique code, and / or on product tags, barcode cards and barcode labels in the form of the unique code.

4. Method according to any one of the preceding claims, wherein at least one reference value of the product is encoded using a unique key in order to generate the unique code.

5. Method according to any one of the preceding claims, wherein the unique code is a one-dimensional code, a two-dimensional code or a three-dimensional code and / or contains one or more patterns, for example spaces, bands, lines, geometrical shapes such as circles, triangles, rectangles, polygons, etc., alphanumeric characters, or combinations thereof.

6. Method according to any one of the preceding claims, wherein the unique code is generated by printing inaccuracies and printing flaws during the process step of printing the ink formulation on at least one face of the surface of the product.

7. Method according to any one of the preceding claims, wherein a terminal device such as a smartphone or tablet is used for the irradiation and / or detection.

8. Method according to any one of the preceding claims, wherein the semiconducting inorganic nanocrystals are selected from the group of perovskite, I-VI semiconductors, II-VI semiconductors, III-V semiconductors, IV-VI semiconductors, I-III-VI semiconductors, carbon dots and mixtures thereof.

9. Method according to any one of the preceding claims, wherein the ink formulation contains semiconducting inorganic nanocrystals that share at least one or all of the following properties: emission wavelength, emission distribution, emission maximum, or contains mixtures of semiconducting inorganic nanocrystals that have differing values for emission wavelength, emission distribution and emission maximum.

10. Method according to any one of the preceding claims, wherein the emitted radiation produces an individual fluorescence spectrum, which is stored in at least one database.

Images