Modification of polyester fibers for protection of securities

Abstract

An effective method for protecting securities from counterfeiting is to incorporate into the paper mass chemical fibers containing specific additives distributed in a predetermined manner throughout the fiber length. Results from modifying polyester fibers with luminescent dyes using a crazing mechanism were presented. SEM and AFM were used to show craze generation steps, their transformation into fibrils, and redistribution of modifiers incorporated into the crazes in the fiber surface layer. A procedure for concentrating luminescent dyes and colloidal nickel particles on localized fiber parts with alternation of untreated parts and those containing the specific additives was described. The magnetic susceptibility of fiber parts containing ferromagnetic nickel was confirmed experimentally by measurements of the fiber magnetic moment using a high-field magnetic measurement system. Polyester fibers with parts of luminescent color separation alternating along the length were produced. It was concluded that the technology for modifying chemical fibers using a crazing mechanism enabled the controlled incorporation of specific additives in localized fiber parts. This satisfied optimally criteria for protecting paper filled with such fibers from counterfeiting.