US 7,011,919 : Self-dispersing titanyl phthalocyanine pigment compositions and electrophotographic charge generation layers containing same
Molaire, Michel F. (Rochester, NY, US)
Sorriero, Louis J. (Rochester, NY, US)
Eastman Kodak Company (Rochester, NY, US)
In a process for forming a self-dispersing crystalline phthalocyanine pigment composition of monodisperse nanoparticles, a mixture containing titanyl fluorophthalocyanines, unsubstituted titanyl phthalocyanine, and an organic monomeric dispersant but substantially free of organic solvents or inorganic salts is dry milled, thereby forming a substantially amorphous phthalocyanine pigment composition. The substantially amorphous composition is contacted with an organic solvent having a hydrogen bonding parameter gammac lower than about 8, thereby forming a self-dispersing cocrystalline phthalocyanine pigment composition of monodisperse nanoparticles containing titanyl fluorophthalocyanines and titanyl phthalocyanine, which can be used to form the charge generation layer of an electrophotographic element.