# US 5,350,657 A · Toner for developing electrostatic latent image > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,350,657 A - Document ID: US5350657A - Status: Granted - Kind: A - Application number: 07/968,305 - Filed: 1992-10-29 - Granted: 1994-09-27 - Earliest claimed: 1991-11-02 - Assignees: Minolta Camera Kabushiki Kaisha - Inventors: Masahiro Anno; Makoto Kobayashi - Web page: https://patentgrep.com/patent/US5350657A ## CPC - G03G 9/09716: {treated with organic compounds} - G03G 9/08755: {Polyesters} - G03G 9/0926: {characterised by physical or chemical properties} - G03G 9/09733: {Organic compounds (G03G9/08782 takes precedence)} - G03G 9/09783: {Organo-metallic compounds} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract In toner for developing an electrostatic latent image, at least an organic charge-controlling agent having a BET specific surface area of 15 to 80 m.sup.2 /g and inorganic fine particles having a BET specific surface area of 10 to 150 m.sup.2 /g are fixed and/or film-formed on the surface of core particles mainly composed of thermoplastic resin. ## Claims ### Claim 1 Toner for developing an electrostatic latent image, in which at least an organic charge-controlling agent having a BET specific surface area of 15 to 80 m.sup.2 /g and inorganic fine particles having a BET specific surface area of 10 to 150 m.sup.2 /g are fixed and/or film-formed in a uniformly dispersed state on the surface of core particles mainly composed of thermoplastic resin. ### Claim 2 (depends on 1) The toner for developing an electrostatic latent image according to claim 1, wherein the BET specific surface area (A) of said organic charge-controlling agent and the BET specific surface area (B) of said inorganic fine particles satisfy the relationship 1/3.ltoreq.B/A.ltoreq.5. ### Claim 3 (depends on 1) The toner for developing an electrostatic latent image according to claim 1, wherein the BET specific surface area of said organic charge-controlling agent is 20 to 600 m.sup.2 /g. ### Claim 4 (depends on 1) The toner for developing an electrostatic latent image according to claim 1, wherein the amount of said organic charge-controlling agent used is 0.01 to 10 parts by weight per 100 parts by weight of said core particles. ### Claim 5 (depends on 1) The toner for developing an electrostatic latent image according to claim 1, wherein the weight ratio of said organic charge-controlling agent to said inorganic fine particles is 1/4 to 4. ### Claim 6 (depends on 1) The toner for developing an electrostatic latent image according to claim 1, wherein the average particle diameter of said core particles is not more than 10 .mu.m. ### Claim 7 (depends on 1) The toner for developing an electrostatic latent image according to claim 1, wherein thermoplastic resin fine particles, together with said organic charge-controlling agent and said inorganic fine particles, are fixed or filmformed on the surface of said core particles. ### Claim 8 Light-transmittable toner for developing an electrostatic latent image, in which at least a calixarene compound having a BET specific surface area of 15 to 80 m.sup.2 /g and inorganic fine particles having a BET specific surface area of 10 to 150 m.sup.2 /g are fixed and/or film-formed in a uniformly dispersed state on the surface of core particles mainly composed of linear polyester having a number-average molecular weight Mn of 2000 to 15000 and having a molecular-weight distribution (Mw/Mn) of not more than 3. ### Claim 9 (depends on 8) The light-transmittable toner for developing an electrostatic latent image according to claim 8, wherein said inorganic fine particles are coated with alkyl polysiloxane. ### Claim 10 (depends on 9) The light-transmittable toner for developing an electrostatic latent image according to claim 9, wherein said alkyl polysiloxane has active hydrogen. ### Claim 11 (depends on 8) The light-transmittable toner for developing an electrostatic latent image according to claim 8, wherein the BET specific surface area of said calixarene compound is 20 to 60 m.sup.2 /g. ### Claim 12 Toner for developing an electrostatic latent image, which is produced by mixing core particles mainly composed of thermoplastic resin, an organic charge-controlling agent having a BET specific surface area of 15 to 80 m.sup.2 /g and inorganic fine particles having a BET specific surface area of 10 to 150 m.sup.2 /g with each other, causing said organic charge-controlling agent and said inorganic fine particles to uniformly adhere to the surface of said core particles and then, fixing and/or film-forming said organic charge-controlling agent and said inorganic fine particles in a uniformly dispersed state on the surface of said core particles by a surface treating equipment. ### Claim 13 (depends on 12) The toner for developing an electrostatic latent image according to claim 12, wherein said surface treating equipment for fixing or film-forming said organic charge-controlling agent and said inorganic fine particles on the surface of said core particles uses a process selected from the impact process in a high speed air current, the dry mechanochemical process, the modification process in a hot air current and the wet coating process. ### Claim 14 Toner for developing an electrostatic latent image, which is produced by mixing core particles mainly composed of thermoplastic resin produced by the wet granulating process, an organic charge-controlling agent having a BET specific surface area of 15 to 80 m.sup.2 /g, and inorganic fine particles having a BET specific surface area of 10 to 150 m.sup.2 /g with each other and then, causing their mixture to aggregate and crushing an aggregate obtained by a surface treating equipment having a crushing function and at the same time, fixing said organic charge-controlling agent and said inorganic fine particles on the surface of the core particles. ### Claim 15 (depends on 14) The toner for developing an electrostatic latent image according to claim 14, wherein said core particles contain polyolefin wax having a number-average molecular weight of 1000 to 20000 and having a softening point of 80.degree. to 150.degree. C.