A spectrally responsive transfer system, comprising a taggant system comprising taggants exhibiting spectral characteristics in response to at least one illumination; a spectral code associated with the spectral characteristics; a coded transfer film releasably supported on a carrier allowing one or more portions of the transfer film to be selectively transferred from the carrier to a substrate to form spectrally coded indicia on the substrate; the transfer film comprising a spectral ink layer incorporating the taggant system and releasably coupled to the carrier; the transfer film also incorporating a metal foil layer over the spectral ink layer such that the metal foil layer overlies the spectral ink layer and such that the metal foil layer underlies the at least one spectral ink layer when the one or more, selectively transferred portions of the transfer film are transferred from the carrier onto the substrate.

A spectrally responsive transfer system, comprising a taggant system comprising taggants exhibiting spectral characteristics in response to at least one illumination; a spectral code associated with the spectral characteristics; a coded transfer film releasably supported on a carrier allowing one or more portions of the transfer film to be selectively transferred from the carrier to a substrate to form spectrally coded indicia on the substrate; the transfer film comprising a spectral ink layer incorporating the taggant system and releasably coupled to the carrier; the transfer film also incorporating a metal foil layer over the spectral ink layer such that the metal foil layer overlies the spectral ink layer and such that the metal foil layer underlies the at least one spectral ink layer when the one or more, selectively transferred portions of the transfer film are transferred from the carrier onto the substrate.

Disclosed are optical devices suitable as security devices for document authentication, which comprise at least one two-dimensional array of elongate laser-modified tracks extending within a document substrate that have a distinct optical refractive index compared to the unmodified substrate, which can exhibit excellent diffractive effects. Also disclosed are the use of such devices for document authentication and methods for their production.

Electroconductive paper structure with cellulosic fibrous materials and electroconductive fibers, wherein the electroconductive paper structure has embedded therein a continuous, electroconductive thread for contacting the electroconductive paper structure from one end to the opposite end of the paper structure.

The present invention relates to a method of tagging a substrate with a covert, spectroscopically detectable security feature, wherein a liquid treatment composition comprising at least one acid is deposited onto a substrate, which comprises at least one external surface comprising a salifiable alkaline or alkaline earth compound.

The present invention relates to a method of tagging a substrate with a covert, spectroscopically detectable security feature, wherein a liquid treatment composition comprising at least one acid is deposited onto a substrate, which comprises at least one external surface comprising a salifiable alkaline or alkaline earth compound.

A chelate and associated security feature including a lanthanide metal and a ligand of formula (1), formula (2), or formula (3),

##STR00001##

where each of R.sub.1-R.sub.7 in formula (1) is independently selected from the group consisting of H, OH, NH.sub.2, Cl, F, OMe, OAr, OCF.sub.3, CF.sub.3, alkyl, aryl, phenyl, OPh, and heteroaromatic, where each of R.sub.1-R.sub.5 in formula (2) is independently selected from the group consisting of H, OH, NH.sub.2, Cl, F, OMe, OAr, OCF.sub.3, CF.sub.3, NMe.sub.2, CN, alkyl, aryl, phenyl, OPh, and heteroaromatic, and where R.sub.6 in formula (2) is selected from the group consisting of H, NH.sub.2, Cl, F, OMe, OAr, OCF.sub.3, CF.sub.3, NMe.sub.2, CN, alkyl, aryl, phenyl, OPh, and heteroaromatic, and where each of R.sub.1-R.sub.5 in formula (3) is independently selected from the group consisting of H, OH, NH.sub.2, Cl, F, OMe, OAr, OCF.sub.3, CF.sub.3, alkyl, aryl, phenyl, OPh, and heteroaromatic.

A chelate and associated security feature including a lanthanide metal and a ligand of formula (1), formula (2), or formula (3),

##STR00001##

where each of R.sub.1-R.sub.7 in formula (1) is independently selected from the group consisting of H, OH, NH.sub.2, Cl, F, OMe, OAr, OCF.sub.3, CF.sub.3, alkyl, aryl, phenyl, OPh, and heteroaromatic, where each of R.sub.1-R.sub.5 in formula (2) is independently selected from the group consisting of H, OH, NH.sub.2, Cl, F, OMe, OAr, OCF.sub.3, CF.sub.3, NMe.sub.2, CN, alkyl, aryl, phenyl, OPh, and heteroaromatic, and where R.sub.6 in formula (2) is selected from the group consisting of H, NH.sub.2, Cl, F, OMe, OAr, OCF.sub.3, CF.sub.3, NMe.sub.2, CN, alkyl, aryl, phenyl, OPh, and heteroaromatic, and where each of R.sub.1-R.sub.5 in formula (3) is independently selected from the group consisting of H, OH, NH.sub.2, Cl, F, OMe, OAr, OCF.sub.3, CF.sub.3, alkyl, aryl, phenyl, OPh, and heteroaromatic.

A method for preparing a large-area structural chromogenic pattern by ink-jet printing, a structural chromogenic pattern obtained by the method, and an anti-counterfeiting method based on a structural color change. A dispersion liquid containing mono-disperse colloidal microspheres with high index of refraction is printed onto a piece of paper by using an ink-jet printer, and nano-microspheres are arranged and assembled on the paper to obtain a micro-structure having the features of being ordered from a short distance and disordered from a long distance. A pretty structural color can be observed by means of the interaction of the structure with light, thus displaying a pattern, changing the angle of observation, changing the brightness of the structural color, and hiding and displaying the pattern. The method is simple and convenient, is widely applicable, and can achieve the preparation and anti-counterfeiting of a large-area structural color without external stimulation.

A method for preparing a large-area structural chromogenic pattern by ink-jet printing, a structural chromogenic pattern obtained by the method, and an anti-counterfeiting method based on a structural color change. A dispersion liquid containing mono-disperse colloidal microspheres with high index of refraction is printed onto a piece of paper by using an ink-jet printer, and nano-microspheres are arranged and assembled on the paper to obtain a micro-structure having the features of being ordered from a short distance and disordered from a long distance. A pretty structural color can be observed by means of the interaction of the structure with light, thus displaying a pattern, changing the angle of observation, changing the brightness of the structural color, and hiding and displaying the pattern. The method is simple and convenient, is widely applicable, and can achieve the preparation and anti-counterfeiting of a large-area structural color without external stimulation.