# US 9,753,388 B2 · Electrostatic latent image developing toner > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,753,388 B2 - Document ID: US9753388B2 - Status: Granted - Kind: B2 - Application number: 15/265,482 - Filed: 2016-09-14 - Published: 2017-03-16 - Granted: 2017-09-05 - Earliest claimed: 2015-09-15 - Assignees: KYOCERA Document Solutions Inc. - Applicants: KYOCERA Document Solutions Inc. - Inventors: Masashi Tamagaki; Tomoyuki Ogawa - Web page: https://patentgrep.com/patent/US9753388B2 ## CPC - G03G 9/09321: {obtained by reactions only involving carbon-to-carbon unsaturated bonds} - G03G 9/0819: {characterised by the dimensions of the particles} - G03G 9/0825: {characterised by their structure; characterised by non-homogenuous distribution of components (microcapsular toners G03G9/093)} - G03G 9/09335: {Non-macromolecular organic compounds} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A shell layer of a toner particle includes first resin particles containing no charge control agent and second resin particles containing a charge control agent. A number average particle diameter of the first resin particles is at least 30 nm and no greater than 60 nm, and a number average particle diameter of the second resin particles is at least 30 nm and no greater than 60 nm. A shell coverage is at least 60% and no greater than 80%. A shell chargeable ratio is at least 0.10 and no greater than 0.20. A roughness of surface regions of toner particles in which no external additive is present is at least 10 nm and no greater than 15 nm. ## Claims ### Claim 1 An electrostatic latent image developing toner comprising a plurality of toner particles each including a core and a shell layer disposed over a surface of the core, wherein the shell layer includes first resin particles containing no charge control agent and second resin particles containing a charge control agent, a number average particle diameter of the first resin particles is at least 30 nm and no greater than 60 nm and a number average particle diameter of the second resin particles is at least 30 nm and no greater than 60 nm, a rate of an area of a surface region of the core covered with at least one of the first resin particles and the second resin particles relative to an area of an entire surface region of the core is at least 60% and no greater than 80%, a ratio of an area of a surface region of the core covered with the second resin particles relative to the area of the surface region of the core covered with at least one of the first resin particles and the second resin particles is at least 0.10 and no greater than 0.20, and a roughness of surface regions of the toner particles in which no external additive is present is at least 10 nm and no greater than 15 nm. ### Claim 2 (depends on 1) The electrostatic latent image developing toner according to claim 1, wherein the first resin particles and the second resin particles are each formed substantially from a resin having a repeating unit derived from a vinyl compound. ### Claim 3 (depends on 2) The electrostatic latent image developing toner according to claim 2, wherein a rate of a repeating unit having a hydrophilic functional group is no greater than 10% by mass relative to all repeating units included in each of the resin forming the first resin particles and having the repeating unit derived from the vinyl compound and the resin forming the second resin particles and having the repeating unit derived from the vinyl compound, and the hydrophilic functional group is an acid group, a hydroxyl group, or a salt thereof. ### Claim 4 (depends on 2) The electrostatic latent image developing toner according to claim 2, wherein the second resin particles are each formed substantially from a resin having a repeating unit derived from the charge control agent. ### Claim 5 (depends on 4) The electrostatic latent image developing toner according to claim 4, wherein the repeating unit derived from the charge control agent is a repeating unit derived from a (meth)acryloyl group-containing quaternary ammonium compound. ### Claim 6 (depends on 1) The electrostatic latent image developing toner according to claim 1, wherein the first resin particles and the second resin particles are each formed substantially from an acrylic acid-based resin or a styrene-acrylic acid-based resin. ### Claim 7 (depends on 1) The electrostatic latent image developing toner according to claim 1, wherein the first resin particles are formed substantially from a styrene-acrylic acid-based resin, and the second resin particles are formed substantially from an acrylic acid-based resin having a repeating unit derived from a (meth)acryloyl group-containing quaternary ammonium compound. ### Claim 8 (depends on 7) The electrostatic latent image developing toner according to claim 7, wherein the repeating unit derived from the (meth)acryloyl group-containing quaternary ammonium compound is a repeating unit represented by chemical formula (1) shown below: where in formula (1), R1 represents a hydrogen atom or a methyl group, R21, R22, and R23 represent, independently of one another, a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted alkoxy group, and R2 represents an optionally substituted alkylene group. ### Claim 9 (depends on 1) The electrostatic latent image developing toner according to claim 1, wherein the toner particles each further include inorganic particles as an external additive.