Heidelberger Druckmaschinen Ag

Nexpress Solutions, Inc.

Robert E Contois

David Daniel Putnam

Dana G Marsh

John F Crichton

Magnetic toner particles are disclosed. The magnetic toner particles contain at least one polymeric binder and at least one magnetic additive, wherein the surface of the toner particle contains particles of positively chargeable inorganic fine powder particles. The inorganic fine powder particles have a mean volume average particle size of from about 0.5 to about 7 &mgr;m, and a cleaning ratio of from about 0.1 to about 5.0 and a cleaning ratio being the volume fraction of particles between 0 and 1.0 &mgr;m, divided by the volume fraction of particles greater than 1.0 &mgr;m; and the toner particles having on the surface thereof a flowability improving agent having a BET surface area of at least about 30 m /g. Methods of forming electrostatic images are further disclosed. Also, images formed from the magnetic toner particles are further disclosed and have excellent character void frequency, total void area, and suitable magnetic signal strengths. Developers containing the magnetic toner particles of the present invention are also disclosed.

Single component toner for improved magnetic image character recognition

A monocomponent electrostatographic developer is disclosed. The developer contains a negatively charging toner wherein the toner particle surface contains a positively chargeable inorganic fine powder having a mean volume average diameter of 0.5 to 7.0 &mgr;m, a cleaning ratio of 0.1 to 5.0, and a flowability improving agent having a BET specific surface area of at least 30 m,/g. A method of electrostatic imaging using the developer is also disclosed.

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Rochester, NY, United States of America

Robert E Contois