Patent ID: 8586141

Claim:
A solid ink composition comprising: a phase change or solid ink carrier, a polymeric dispersant, an optional colorant, and a fluorescent nanoparticle composition, wherein the carrier comprises one or more organic compounds that are solid at room temperature but becomes liquid at a printer operating temperature for ejecting the ink composition onto a print surface, and the fluorescent nanoparticle composition comprises: a fluorescent organic nanoparticle having an average particle length of less than 150 nm, nanoscale benzothioxanthene pigment particles including a benzothioxanthene pigment with at least one functional moiety, and at least one sterically bulky stabilizer compound, wherein the functional moiety on the benzothioxanthene pigment associates non-covalently with the functional group of the stabilizer, the nanoscale benzothioxanthene pigment particles have an average aspect ratio (length:width) of from 1:1 to 5:1.