# US 2021/0240096 A1 · Electrostatic image developer, process cartridge, image forming apparatus, and image forming method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0240096 A1 - Document ID: US20210240096A1 - Status: Published application - Kind: A1 - Application number: 16/926,819 - Filed: 2020-07-13 - Published: 2021-08-05 - Earliest claimed: 2020-01-31 - Assignees: Fuji Xerox Co., Ltd. - Applicants: Fuji Xerox Co., Ltd. - Inventors: Soutaro KAKEHI; Sakon TAKAHASHI; Yutaka SAITO - Web page: https://patentgrep.com/patent/US20210240096A1 ## CPC - G03G 9/0825: {characterised by their structure; characterised by non-homogenuous distribution of components (microcapsular toners G03G9/093)} - G03G 9/09708: {Inorganic compounds} - G03G 9/0819: {characterised by the dimensions of the particles} - G03G 9/0902: {Inorganic compounds} - G03G 9/09791: {Metallic soaps of higher carboxylic acids} - G03G 9/1088: {Binder-type carrier} - G03G 15/08: using a solid developer, e.g. powder developer - G03G 2215/0607: two-component - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract An electrostatic image developer includes a toner containing toner particles, a carrier, and an external additive containing titanium dioxide particles of two types having different refractive indexes, fatty acid metal salt particles, and an abrasive. ## Claims ### Claim 1 An electrostatic image developer comprising: a toner containing toner particles; a carrier; and an external additive containing titanium dioxide particles of two types having different refractive indexes, fatty acid metal salt particles, and an abrasive. ### Claim 2 (depends on 1) The electrostatic image developer according to claim 1, wherein the titanium dioxide particles of two types having different refractive indexes include titanium dioxide particles (A) adhered to the toner particles and titanium dioxide particles (B) adhered to the carrier; and a refractive index of the titanium dioxide particles (A) is lower than a refractive index of the titanium dioxide particles (B). ### Claim 3 (depends on 2) The electrostatic image developer according to claim 2, wherein the refractive index of the titanium dioxide particles (A) is 2.0 or more and less than 2.4; and the refractive index of the titanium dioxide particles (B) is 2.4 or more and 2.8 or less. ### Claim 4 (depends on 1) The electrostatic image developer according to claim 1, wherein the fatty acid metal salt particles are fatty acid zinc particles; and the abrasive is composed of titanic acid metal salt particles. ### Claim 5 (depends on 2) The electrostatic image developer according to claim 2, wherein the fatty acid metal salt particles are fatty acid zinc particles; and the abrasive is composed of titanic acid metal salt particles. ### Claim 6 (depends on 3) The electrostatic image developer according to claim 3, wherein the fatty acid metal salt particles are fatty acid zinc particles; and the abrasive is composed of titanic acid metal salt particles. ### Claim 7 (depends on 4) The electrostatic image developer according to claim 4, wherein the fatty acid metal salt particles are zinc stearate particles; and the abrasive is composed of strontium titanate particles. ### Claim 8 (depends on 5) The electrostatic image developer according to claim 5, wherein the fatty acid metal salt particles are zinc stearate particles; and the abrasive is composed of strontium titanate particles. ### Claim 9 (depends on 6) The electrostatic image developer according to claim 6, wherein the fatty acid metal salt particles are zinc stearate particles; and the abrasive is composed of strontium titanate particles. ### Claim 10 (depends on 1) The electrostatic image developer according to claim 1, wherein a content of the fatty acid metal salt particles is 1% by mass or more and 10% by mass or less relative to a content of the titanium dioxide particles (A). ### Claim 11 (depends on 2) The electrostatic image developer according to claim 2, wherein a content of the fatty acid metal salt particles is 1% by mass or more and 10% by mass or less relative to a content of the titanium dioxide particles (A). ### Claim 12 (depends on 3) The electrostatic image developer according to claim 3, wherein a content of the fatty acid metal salt particles is 1% by mass or more and 10% by mass or less relative to a content of the titanium dioxide particles (A). ### Claim 13 (depends on 4) The electrostatic image developer according to claim 4, wherein a content of the fatty acid metal salt particles is 1% by mass or more and 10% by mass or less relative to a content of the titanium dioxide particles (A). ### Claim 14 (depends on 7) The electrostatic image developer according to claim 7, wherein a content of the fatty acid metal salt particles is 1% by mass or more and 10% by mass or less relative to a content of the titanium dioxide particles (A). ### Claim 15 (depends on 1) The electrostatic image developer according to claim 1, wherein a content of the abrasive is 1% by mass or more and 10% by mass or less relative to a content of the titanium dioxide particles (A). ### Claim 16 (depends on 1) The electrostatic image developer according to claim 1, wherein a content of the titanium dioxide particles (A) is 0.1% by mass or more and 50% by mass or less relative to a content of the titanium dioxide particles (B). ### Claim 17 An electrostatic image developer comprising: a toner containing toner particles; a carrier; and an external additive containing titanium dioxide particles of two types having different crystallite diameters, fatty acid metal salt particles, and an abrasive. comprising: ### Claim 18 (depends on 1) A process cartridge detachable from an image forming apparatus, comprising: a developing unit that contains the electrostatic image developer according to claim 1 and that develops, as a toner image with the electrostatic image developer, an electrostatic image formed on a surface of an image holding member. ### Claim 19 (depends on 1) An image forming apparatus comprising: an image holding member; a charging unit that charges a surface of the image holding member; an electrostatic image forming unit that forms an electrostatic image on the charged surface of the image holding member; a developing unit that contains the electrostatic image developer according to claim 1 and that develops, as a toner image with the electrostatic image developer, the electrostatic image formed on the surface of an image holding member; a transfer unit that transfers the toner image formed on the surface of the image holding member to a surface of a recording medium; and a fixing unit that fixes the toner image transferred to the surface of the recording medium. ### Claim 20 (depends on 1) An image forming method comprising: charging a surface of an image holding member; forming an electrostatic image on the charged surface of the image holding member; developing, as a toner image with the electrostatic image developer according to claim 1, the electrostatic image formed on the surface of an image holding member; transferring the toner image formed on the surface of the image holding member to a surface of a recording medium; and fixing the toner image transferred to the surface of the recording medium.