A security document (200) includes a secure substrate (205). The secure substrate includes a viewing side (209) and a backing side (211), and a micro-optic system (305, 321) providing an optically variable effect (OVE) (513) on the viewing side. The security document further includes a protective layer (225), and a mask layer (215) disposed between the protective layer and the backing side of the secure substrate.

An optical device is formed by hot stamping a demetallized hologram to an optically variable foil or to a coating of optically variable ink. In another embodiment a hologram is hot stamped to a banknote or document printed with a color-shifting ink.

A security document (200) includes a secure substrate (205). The secure substrate includes a viewing side (209) and a backing side (211), and a micro-optic system (305, 321) providing an optically variable effect (OVE) (513) on the viewing side. The security document further includes a protective layer (225), and a mask layer (215) disposed between the protective layer and the backing side of the secure substrate.

An object of the present invention is to provide a thin volume hologram sheet to be embedded sufficiently resistant to a mechanical stress such as a stress including a tensile stress, a shear stress and a compression stress at the time of processing even under a heating condition, a forgery prevention paper and a card using the same. The object is achieved by providing a volume hologram sheet to be embedded comprising a volume hologram layer, and a substrate disposed only on one side surface of the volume hologram layer using an adhesion means, wherein a peeling strength of the volume hologram layer and the substrate is 25 gf/25 mm or more.

An object of the present invention is to provide a thin volume hologram sheet to be embedded sufficiently resistant to a mechanical stress such as a stress including a tensile stress, a shear stress and a compression stress at the time of processing even under a heating condition, a forgery prevention paper and a card using the same. The object is achieved by providing a volume hologram sheet to be embedded comprising a volume hologram layer, and a substrate disposed only on one side surface of the volume hologram layer using an adhesion means, wherein a peeling strength of the volume hologram layer and the substrate is 25 gf/25 mm or more.

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.

Self-cleaning banknotes are provided using coatings, inks and additives which are photo-active and catalytic to reactions which are effective in breaking up organic contaminants or dirt to allow for the self-cleaning of banknotes by ambient light exposure as well as the cleaning of processed banknotes using equipment with more intense optical excitation, thus increasing their usable life. The invention is usable with all substrates and particularly polymeric substrates such as biaxially-oriented polypropylene (BOPP). The invention further discloses a system which allows a certain class of fitness parameters to cause these banknotes to be redirected to a cleaning module, be revaluated, and then either returned to circulation or rejected and/or destroyed. In addition, inks which are photo-catalytic can be used for extending the life of the banknotes in printed regions.

Self-cleaning banknotes are provided using coatings, inks and additives which are photo-active and catalytic to reactions which are effective in breaking up organic contaminants or dirt to allow for the self-cleaning of banknotes by ambient light exposure as well as the cleaning of processed banknotes using equipment with more intense optical excitation, thus increasing their usable life. The invention is usable with all substrates and particularly polymeric substrates such as biaxially-oriented polypropylene (BOPP). The invention further discloses a system which allows a certain class of fitness parameters to cause these banknotes to be redirected to a cleaning module, be revaluated, and then either returned to circulation or rejected and/or destroyed. In addition, inks which are photo-catalytic can be used for extending the life of the banknotes in printed regions.

A security document, along with its methods of formation, is provided. The security document may include a base sheet, a colored coating on the base sheet, a foil laminate on at least a portion of the colored coating, and an outer lacquer coating over the colored coating such that the foil laminate is embedded between the colored coating and the outer lacquer coating. The outer lacquer coating may include a polymeric resin, and may also include a crosslinking agent and a wetting agent.

A method for enhancing the structural strength of a porous substrate having pores therein is disclosed. The method includes soaking the porous substrate in a solution having a first solvent and at least one polymer dissolved in the first solvent at a specific temperature and pressure, such that the solution is deposited within pores of the porous substrate, soaking the porous substrate in a second solvent, such that the first solvent diffuses into the second solvent, and such that the at least one polymer remains within the pores of the porous substrate, and flushing out the second solvent from the porous substrate.