Method for making cellulose esters incorporating near-infrared fluorophores

Abstract

A cellulosic ester has associated with the ester at least one near infrared fluorophore. A method for incorporating the near infred fluorophore into the cellulosic ester is also provided. In the method, the near infrared fluorophore is dissolved in a strong acid and precipitated to form an acid paste. The paste is then added to an activated cellulose, such as a hydrolyzed cellulose acetate, in the presence of at least one acid and acid anhydride. Advantageously, such marked cellulosic materials can be solvent spun into staple fibers which may be further utilized in known materials, webs and articles.

Dependencies are inferred from the claim text.