# US 5,350,659 A · Preparation of conductive toners using fluidized bed processing equipment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,350,659 A - Document ID: US5350659A - Status: Granted - Kind: A - Application number: 08/040,965 - Filed: 1993-03-31 - Granted: 1994-09-27 - Earliest claimed: 1993-03-31 - Assignees: Xerox Corporation - Inventors: Frank P. Lee; Sheau V. Kao; Gerald R. Allison; Hadi K. Mahabadi; Geroge Liebermann; Gopalan Vijayakumar; Robert A. Downing - Web page: https://patentgrep.com/patent/US5350659A ## CPC - G03G 9/0823: {Electric parameters} - G03G 9/0802: {Preparation methods} - G03G 9/0825: {characterised by their structure; characterised by non-homogenuous distribution of components (microcapsular toners G03G9/093)} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## 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.-4 to about 10.sup.-8 ohm.sup.-1 -cm.sup.-1. ## Claims ### Claim 1 A method for making conductive toner particles, comprising (A) heat treating in fluidized bed processing equipment a mixture of non-conductive toner particles comprising 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 said 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 toner particles to a temperature below the glass transition temperature of the resin. ### Claim 2 (depends on 1) A method according to claim 1, wherein the nonconductive toner particles have a volume average particle diameter of less than 20 microns. ### Claim 3 (depends on 1) A method according to claim 1, wherein the nonconductive toner particles have a volume average particle diameter of from about 7 to about 18 microns. ### Claim 4 (depends on 1) A method according to claim 1, wherein the thermoplastic resin is a polyester resin. ### Claim 5 (depends on 4) A method according to claim 4, wherein the mixture of non-conductive toner particles and conductive powder is heated to a temperature in the range of from about 90.degree. to about 120.degree. C. in said fluidized bed processing equipment. ### Claim 6 (depends on 1) A method according to claim 1, wherein the colorant is a magnetic colorant. ### Claim 7 (depends on 6) A method according to claim 6, wherein the magnetic colorant is magnetite. ### Claim 8 (depends on 1) A method according to claim 1, wherein the conductive powder is conductive carbon black, a metal, a metal alloy, or a metal oxide. ### Claim 9 (depends on 1) A method according to claim 1, wherein the effective amount of conductive powder is an amount sufficient to provide toner particles having a conductivity of at least about 10.sup.-8 ohm.sup.-1 -cm.sup.-1. ### Claim 10 (depends on 1) A method according to claim 1, wherein the effective amount of conductive powder is an amount sufficient to provide toner particles having a conductivity in the range of from about 10.sup.-4 to about 10.sup.-8 ohm.sup.-1 -cm.sup.-1. ### Claim 11 (depends on 1) A method according to claim 1, wherein the effective amount of conductive powder is from about 0.5 to about 5 parts by weight per 100 parts by weight of the non-conductive toner. ### Claim 12 (depends on 1) A method according to claim 1, wherein the mixture of non-conductive toner particles and conductive powder is heated to a temperature in the range of from about 80.degree. to about 150.degree. C. in said fluidized bed processing equipment. ### Claim 13 (depends on 1) A method according to claim 1, wherein the mixture of non-conductive toner particles and conductive powder is heated for a period of at least about 30 minutes in said fluidized bed processing equipment. ### Claim 14 (depends on 1) A method according to claim 1, wherein the mixture of non-conductive toner particles and conductive powder is heated for a period ranging from about 30 minutes to about 200 minutes in said fluidized bed processing equipment. ### Claim 15 (depends on 1) A method according to claim 1, wherein the fluidized bed processing equipment is batch fluidized bed processing equipment. ### Claim 16 (depends on 1) A method according to claim 1, wherein the fluidized bed processing equipment comprises a laminated membrane filter bag wherein a tetrafluoroethylene fluorocarbon membrane is bonded to a polyester or nylon substrate; and a product container having a 200-400 mesh stainless steel screen bottom. ### Claim 17 A method for making conductive toner particles, comprising (1) mixing non-conductive toner particles comprising a thermoplastic resin and a colorant with an effective amount of a conductive powder to form a blend of conductive powder coated on surfaces of the non-conductive toner particles; (2) heat treating said blend in fluidized bed processing equipment, wherein said heat treatment is carried out at a temperature at or above the glass transition temperature of the thermoplastic resin for a period of time at least sufficient to fuse the conductive powder onto the surfaces of the non-conductive toner particles; (3) cooling the heated toner particles to a temperature below the glass transition temperature of the resin; (4) removing the cooled toner particles from the fluidized bed processing equipment; and (5) classifying the toner particles.