20 - Toners

Abstract

Toners are used in various processes for forming and printing images. One such image forming process is electrophotography, which uses a photosensitive member generally formed of a photo conductive material, and wherein an electrical latent image is formed on the photosensitive member by various means. The electrical latent image is developed using a toner. The toner image thus developed is transferred to a printing material, such as paper, and then fixed thereto by heating or pressure, or by using solvent vapor, thus obtaining a copy of the image. Different types of developers are conventionally used in dry development devices for electrophotography: one-component-type-magnetic developers comprising a toner containing magnetic powder; one-component-type nonmagnetic developers comprising a toner containing no magnetic powder; two-component-type nonmagnetic developers comprising a toner containing no magnetic powder and a magnetic carrier, which is mixed with the toner in a fixed proportion; and two-component-type magnetic developers comprising a toner containing magnetic powder and a magnetic carrier, which is mixed with the toner in a fixed proportion. Toners contain a primary or binder resin, known as a toner resin, such as a thermoplastic resin, a colorant such as a dye or pigment, and a charge control agent, releasing agents, and other additives. Several polymers are used as thermoplastic binder resins, including poly(styrene)s, styrene-acrylic resins, styrene-methacrylic resins, polyesters, epoxy resins, acrylics, and urethanes.