The present disclosure relates to a system for electrostatic printing. The system comprises a UV colorant comprising a rare earth diketonate, a thermoplastic resin and an additive selected from at least one of an acid having a pKa of 1 to 5 and a hydroxide. The system may be used to print a security feature on a print substrate.

The present disclosure relates to a system for electrostatic printing. The system comprises a UV colorant comprising a rare earth diketonate, a thermoplastic resin and an additive selected from at least one of an acid having a pKa of 1 to 5 and a hydroxide. The system may be used to print a security feature on a print substrate.

Disclosed are fluorescent compounds with large Stokes-shift and a process for their preparation. More particularly, disclosed are fluorescent compounds that are colorless. The compounds can be used in compositions for inks, paints and plastics, especially in a wide variety of printing systems and are particularly well-suited for security applications.

The present invention relates to a zinc sulphide phosphor and to a process for producing same. The invention further relates to a security document or document of value, to a security feature and to a method for detecting same. The phosphor according to the invention can act as electroluminescent phosphor and thus be excited by an electrical field, and this can result in emission of electroluminescent light in the blue and/or green color region of the visible spectrum. The phosphor can moreover be excited by UV radiation in the wavelength range than 345 nm to 370 nm, and can thus emit photoluminescent light in the blue color region of the visible spectrum. The phosphor can moreover be excited by UV radiation in the wavelength range from 310 nm in 335 nm, and can thus emit photoluminescent light in the green color region of the visible spectrum.

The present invention relates to a zinc sulphide phosphor and to a process for producing same. The invention further relates to a security document or document of value, to a security feature and to a method for detecting same. The phosphor according to the invention can act as electroluminescent phosphor and thus be excited by an electrical field, and this can result in emission of electroluminescent light in the blue and/or green color region of the visible spectrum. The phosphor can moreover be excited by UV radiation in the wavelength range than 345 nm to 370 nm, and can thus emit photoluminescent light in the blue color region of the visible spectrum. The phosphor can moreover be excited by UV radiation in the wavelength range from 310 nm in 335 nm, and can thus emit photoluminescent light in the green color region of the visible spectrum.

Embodiments include articles, authentication methods and apparatus, and article manufacturing methods. An article includes a substrate with a first luminescent taggant, and an extrinsic feature with a second luminescent taggant, which is positioned proximate a portion of the article surface. The first and second taggants produce emissions in overlapping emission bands as a result of exposure to excitation energy. Above the extrinsic feature, the substrate and extrinsic feature emissions combine in the overlapping emission band to produce confounded emissions that are distinguishable from the substrate emissions taken alone. An authentication system determines whether, in a region corresponding to a substrate-only region of an authentic article, emissions having first emission characteristics are detected in the overlapping emission band. The system also determines whether, in a region corresponding to an extrinsic feature region of an authentic article, the confounded emissions are detected in the overlapping emission band.

Embodiments include articles, authentication methods and apparatus, and article manufacturing methods. An article includes a substrate with a first luminescent taggant, and an extrinsic feature with a second luminescent taggant, which is positioned proximate a portion of the article surface. The first and second taggants produce emissions in overlapping emission bands as a result of exposure to excitation energy. Above the extrinsic feature, the substrate and extrinsic feature emissions combine in the overlapping emission band to produce confounded emissions that are distinguishable from the substrate emissions taken alone. An authentication system determines whether, in a region corresponding to a substrate-only region of an authentic article, emissions having first emission characteristics are detected in the overlapping emission band. The system also determines whether, in a region corresponding to an extrinsic feature region of an authentic article, the confounded emissions are detected in the overlapping emission band.

Examples include a security document having a substrate with a transparent window. In the region of the transparent window, a micro-optical structure including microlenses is arranged on one side of the substrate and a first print image is arranged on the other side of the substrate, opposite the micro-optical structure. A layer covers at least a section of the first print image. The layer allows electromagnetic radiation having a wavelength in the range of 380 nm to 780 nm to pass with a transparency in a range between 10% and 90%. The transparency gradually varies over a planar extension of the layer. A second print image is arranged on the layer in such a way that the second print image, or at least a piece of information contained therein, can be brought into alignment with the micro-optical structure after carrying out a folding process and becomes visible and/or recognizable.

Examples include a security document having a substrate with a transparent window. In the region of the transparent window, a micro-optical structure including microlenses is arranged on one side of the substrate and a first print image is arranged on the other side of the substrate, opposite the micro-optical structure. A layer covers at least a section of the first print image. The layer allows electromagnetic radiation having a wavelength in the range of 380 nm to 780 nm to pass with a transparency in a range between 10% and 90%. The transparency gradually varies over a planar extension of the layer. A second print image is arranged on the layer in such a way that the second print image, or at least a piece of information contained therein, can be brought into alignment with the micro-optical structure after carrying out a folding process and becomes visible and/or recognizable.

The present invention relates to a security document and/or document of value with a hologram in a visually changeable window as a novel security element, and also to a method for producing the same.