Robert L Downing

US Patent:

53506596, Sep 27, 1994

Filed:

Mar 31, 1993

Appl. No.:

8/040965

Inventors:

Frank P. Lee - Oakville, CA
Sheau V. Kao - Oakville, CA
Gerald R. Allison - Oakville, CA
Hadi K. Mahabadi - Etobicoke, CA
Geroge Liebermann - Mississauga, CA
Gopalan Vijayakumar - Fremont CA
Robert A. Downing - San Jose CA

Assignee:

Xerox Corporation - Stamford CT

International Classification:

G03G 500

US Classification:

430137

Abstract:

A method for making conductive toner particles includes (A) heat treating in fluidized bed processing equipment a mixture of non-conductive toner particles containing a thermoplastic resin and a colorant, and an effective amount of conductive powder blended with and coated on surfaces of the non-conductive toner particles, wherein the heat treatment is carried out at a temperature at or above the glass transition temperature of the resin for a period of time at least sufficient to fuse the conductive powder onto the surfaces of the non-conductive toner particles, and then (B) cooling the heated conductive toner particles to a temperature below the glass transition temperature of the resin. The final toner particles have a conductivity of at least about 10. sup. -8 ohm. sup. -1 -cm. sup. -1 and preferably from about 10. sup.