Near Infrared Absorbing and Fluorescent Inks

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Introduction: Security printing technology provides essential security solutions for identification/authentication/detection of products and articles. The existing near infrared (NIR) fluorescent inks and dye compositions used for invisible marking/printing in this field are obtained through copolymerization. The dyes selected from the classes phthalocyanines, 2,3- naphthalocyanin, squaric acid dyes, and croconic acid dyes are covalently attached to the polymers that are dispersed or dissolved in water or organic solvents. However, this method of ink formation is complex, requiring dyes with extremely high thermal stability to survive the high temperature copolymerization and dispersion processes. Accordingly, NIR dyes that may have superior optical and chemical properties also cannot be used because of thermal sensitivity. Therefore, new and simpler methods are needed for efficient large-scale production of ink or dye compositions that are suitable for invisible marking/printing. Technology: Georgia State University researchers have invented new ink and coating compositions using simpler and innovative dispersion methods for improved covert molecular marking of surfaces. These new organic heterocyclic dyes can be molecularly dispersed in water-dissipatable, sulfo-containing polyesters and polyester-amides. They can also be dissolved in cellulose esters, polyesters, and other resins that are soluble in alcohol, ketone, and ester solvents. The proposed compounds and synthesis methods help produce longer wavelength colorants containing near infrared-absorbing and fluorescent (NIRF) dyes without subjecting the compounds to high temperatures.