Abstract: An improved single component magnetic toner composition with a resistivity of from about 10.sup.13 to about 10.sup.16 ohm/cm, at 1,000 volts, and comprised of:(a) first resin particles of a styrene methacrylate copolymer grafted with or containing a low molecular weight wax composition;(b) second resin particles of a styrene, acrylate, acrylonitrile terpolymer;(c) a major amount of magnetite particles; and(d) islands or patches of carbon black particles in an amount of from about 0.1 percent to about 1 percent by weight, contained on the surface of the resin particles.

Abstract: An electrostatographic development and cleaning system employing electrically insulating carrier particles. The carrier particles comprise a core having magnetic or magnetically-attractable properties which is coated with a polyvinyl acetal. The coated carrier particles have negative triboelectric charging properties and are particularly useful in development systems employing negatively charged photoconductive surfaces. The carrier particles provide efficient removal of residual toner deposits from a photoreceptor surface after a copying operation.

Abstract: An electrostatographic developer mixture comprising finely-divided positively charging toner particles electrostatically clinging to negatively charging carrier particles. The toner particles comprise a resin, a colorant, and a charge inducing material selected from (1) a long chain hydrazinium compound and (2) an alkyl pyridinium compound. The carrier particles comprise core particles having a coating of fused thermoplastic resin particles wherein the carrier particles are prepared by dry-mixing the core particles with thermoplastic resin particles until the resin particles adhere to the core particles. The mixture of core and resin particles are heated to between 320.degree. F. and 650.degree. F. for between 20 and 120 minutes so that the resin particles melt and fuse to the core particles. The developer mixture is employed to develop electrostatic latent images.

Abstract: Electrostatographic coated carrier particles for use in the development of electrostatic latent images are provided by mixing carrier core materials with powdered thermoplastic resin particles having a size of between 0.1 micron and about 30 microns. The carrier core materials are mixed with the resin particles until the resin particles mechanically and/or electrostatically adhere to the core materials and the mixture is heated to a temperature of between 320.degree. F. and 650.degree. F. for between 120 minutes and 20 minutes so that the resin particles melt and fuse to the carrier core materials. The coated carrier particles are cooled, classified to the desired particle size, and mixed with finely-divided toner particles to form a developer mixture. The process is especially advantageous for coating carrier particles with resin materials having poor solubility characteristics.