Self-dispersing titanyl phthalocyanine pigment compositions and electrophotographic charge generation layers containing same

摘要

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 gamma_c 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.