Abstract: A method for marking or tagging individual microparticles using a near infrared fluorophore for identification is provided. The near infrared fluorophore is included with one or more layers comprising the microparticle. Desirably, the coating layers contain colorants such as dyes and/or pigments which increases the total possible combinations that may be used to identify the marked material. There is further provided a method for marking a material using these microparticles containing a near infrared fluorophore.

Abstract: A pigment composition includes a crystalline thermoplastic polyester resin having residues of at least one dicarboxylic acid and a near-infrared fluorescing compound having a fluorescence between about 650 nm to about 2500 nm associated with the crystalline thermoplastic polyester, wherein the polyester has an intrinsic viscosity (IV) of less than about 0.37. A preferred polyester is polybutylene terephthalate. Another aspect is a method for providing a detectable or identifiable marking that is invisible to the unaided eye on a surface of a substrate is also provided. The method includes the steps of applying to the surface a marking composition comprising a suitably compatible marking fluid containing the fluorescent pigment composition. The near infrared fluorescing pigment composition is useful in letterpress, flexographic and gravure printing applications.

Abstract: Fibers having at least one near-infrared fluorescing compound associated therewith are prepared by contacting the fibers with the fluorescing compound(s) dissolved in an organic solvent. Suitable organic solvents include ketones and alcohols. The fibers may subsequently be air-dried to remove any remaining volatiles. Fibers coated with the marker solution desirably have less than 1 weight percent of the marker coated thereon.

Abstract: The present invention relates to thermal transfer ribbons comprising a ribbon backing element and at least one printing media layer comprising at least one near infrared fluorescent compound in a concentration which provides detectable fluorescence without imparting color to a mark made from said printing media layer. Methods for printing marks containing said at least one near infrared fluorescent compounds via thermal transfer and methods for reading said marks are also disclosed.

Abstract: An invisible indicia or encoded information is imprinted on a substrate using a compound which produces a fluorescence at a wavelength greater than about 650 nm when exposed to near infrared radiation. The information covered by a layer of material that reflects or absorbs a substantial amount of the visible and UV radiation illuminating its surface.

Abstract: A digital recording medium, such as a compact disc, having a substrate, a reflective layer and a protective layer includes a near infrared fluorophore in one of the layers. The near infrared fluorophore can be incorporated into the CD by coating, admixing, blending or copolymerization and in an amount to impart a detectable fluorescence from the fluorophore when exposed to electromagnetic radiation having a wavelength ranging from about 670 nanometers (nm) to about 1100 nm. A method of marking a CD with an invisible marking and an apparatus for detecting the fluorophore is further provided.