Toner composition with elastomeric thermoplastic polymer and process of

Abstract

A method is described for the preparation of electrostatographic toner particles which involves the surface treatment of a pigment by depositing thereon a coating of an elastomeric thermoplastic polymer. The method involves preparing a polymer solution by dissolving an elastomeric thermoplastic polymer selected from the group consisting of linear styrene-isoprene-styrene triblock copolymers, linear styrene-ethylene-butylene-styrene triblock copolymers, linear styrene-isoprene diblock copolymers and linear styrene-ethylene-propylene diblock copolymers in a first solvent capable of dissolving the polymer at ambient temperature; forming a pigment dispersion by mixing at ambient temperature a pigment, a first polymer material and a second solvent in which the elastomeric thermoplastic polymer is insoluble at ambient temperature; admixing the polymer solution with the pigment dispersion so resulting in the elastomeric thermoplastic polymer precipitating out upon the surface of the pigment; mixing the elastomeric thermoplastic polymer coated pigment dispersion thus formed with a solvent in which the elastomeric thermoplastic polymer is insoluble at ambient temperature and, optionally, a second polymer material and, optionally, a charge-control agent to form an organic phase; dispersing the organic phase in an aqueous phase comprising a particulate stabilizer and, optionally, a promoter; homogenizing the resultant mixture, and evaporating the solvent and washing and drying the resultant product.