# US 8,785,095 B2 · Toner for developing electrostatic charge image, and apparatus and method for forming image using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,785,095 B2 - Document ID: US8785095B2 - Status: Granted - Kind: B2 - Application number: 13/326,994 - Filed: 2011-12-15 - Published: 2012-07-05 - Granted: 2014-07-22 - Earliest claimed: 2010-12-29 - Assignees: Samsung Electronics Co., Ltd. - Applicants: Se-young Yoon; Song-won Hyun; Hong-Chul Shin; Sung-dong Lee; Jong-in Kim - Inventors: Se-young Yoon; Song-won Hyun; Hong-Chul Shin; Sung-dong Lee; Jong-in Kim - Web page: https://patentgrep.com/patent/US8785095B2 ## CPC - G03G 15/08: using a solid developer, e.g. powder developer - G03G 9/0806: {whereby chemical synthesis of at least one of the toner components takes place} - G03G 9/0808: {by dry mixing the toner components in solid or softened state} - G03G 9/0819: {characterised by the dimensions of the particles} - G03G 9/097: Plasticisers; Charge controlling agents - G03G 9/09708: {Inorganic compounds} - G03G 9/09716: {treated with organic compounds} - G03G 9/09725: {Silicon-oxides; Silicates} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract Disclosed is a toner for developing an electrostatic charge image, including a toner particle coated with a combination of sol-gel silica particles, hydrophobically surface-treated fumed silica particles, and hydrophobically surface-treated titanium dioxide particles. ## Claims ### Claim 1 A toner for developing an electrostatic charge image, the toner comprising: a toner particle comprising a binder resin, a colorant, and a releasing agent; and an external additive disposed on the surface of the toner particle, the external additive comprising: sol-gel silica particles having an average sphericity value in a range of from about 0.8 to about 0.97, a Braunauer-Emmett-Teller (BET) specific surface area of about 30 m2/g to about 70 m2/g, and an average primary particle diameter in a range of from about 10 nm to less than 80 nm, wherein the sphericity value is a ratio between a shortest diameter and a longest diameter of each of the sol-gel particles and a ratio of the number of sol-gel silica particles having a sphericity value of less than about 0.97 to the total number of the sol-gel silica particles is at least about 50%; hydrophobically surface-treated fumed silica particles having average primary particle diameters in a range of from about 7 nm to about 50 nm; and hydrophobically surface-treated titanium dioxide particles having average primary particle diameters in a range of from about 10 nm to about 50 nm, wherein a (D84v/D16v)1/2 value of the sol-gel silica particles is in a range of from about 1.7 to about 2.3, in which D16v is a particle diameter at which a cumulative percentage of 16% is attained, and D84v is a particle diameter at which a cumulative percentage of 84% is attained, in a cumulative volume distribution of the sol-gel silica particles as measured by the Coulter method. ### Claim 2 (depends on 1) The toner of claim 1, wherein the external additive comprises about 0.1 parts by weight to about 3 parts by weight of the sol-gel silica particles, about 0.1 parts by weight to about 2 parts by weight of the fumed silica particles, and about 0.1 parts by weight to about 2 parts by weight of the titanium dioxide particles, based on 100 parts by weight of the toner particle. ### Claim 3 (depends on 1) The toner of claim 1, wherein the sol-gel silica particles have a BET specific surface area in a range of from about 30 m2/g to about 70 m2/g, and a degree of hydrophobicity of less than about 50. ### Claim 4 (depends on 1) The toner of claim 1, wherein the sol-gel silica particles have a true specific gravity in a range of from about 1.5 to about 2.5. ### Claim 5 (depends on 1) The toner of claim 1, wherein a sphericity and an average particle diameter of the sol-gel silica particles are calculated by measuring the longest diameters, the shortest diameters, and the average particle diameters of 100 of the sol-gel silica particles at room temperature and under a relative humidity (RH) of 55±5%. ### Claim 6 (depends on 1) The toner of claim 1, wherein the toner comprises a secondary particle comprising an aggregation of the hydrophobically surface-treated fumed silica particles, the secondary particle having an average particle diameter in a range of from about 5 μm to about 20 μm and a bimodal-type particle size distribution with two peaks at about 1 μm or less and about 5 μm or more. ### Claim 7 (depends on 1) The toner of claim 1, wherein the toner particles are prepared by a pulverization method or by a polymerization method. ### Claim 8 A method for forming an image, the method comprising: attaching a toner to an electrostatic latent image formed on a photoreceptor to form a visible image; and transferring the visible image to a transfer member, wherein the toner comprises: a toner particle comprising a binder resin, a colorant, and a releasing agent; and an external additive disposed on the surface of the toner particle, the external additive comprising: sol-gel silica particles having an average sphericity value in a range of from about 0.8 to about 0.97, a Braunauer-Emmett-Teller (BET) specific surface area of about 30 m2/g to about 70 m2/g, and an average primary particle diameter in a range of from about 10 nm to less than 80 nm, wherein the sphericity value is a ratio between a shortest diameter and a longest diameter of each of the sol-gel particles and a ratio of the number of sol-gel silica particles having a sphericity value of less than about 0.97 to the total number of the sol-gel silica particles is at least about 50%; hydrophobically surface-treated fumed silica particles having average primary particle diameters in a range of from about 7 nm to about 50 nm; and hydrophobically surface-treated titanium dioxide particles having average primary particle diameters in a range of from about 10 nm to about 50 nm, wherein a (D84v/D16v)1/2 value of the sol-gel silica particles is in a range of from about 1.7 to about 2.3, in which D16v is a particle diameter at which a cumulative percentage of 16% is attained, and D84v is a particle diameter at which a cumulative percentage of 84% is attained, in a cumulative volume distribution of the sol-gel silica particles as measured by the Coulter method. ### Claim 9 (depends on 8) The method of claim 8, wherein the external additive comprises about 0.1 parts by weight to about 3 parts by weight of the sol-gel silica particles, about 0.1 parts by weight to about 2 parts by weight of the fumed silica particles, and about 0.1 parts by weight to about 2 parts by weight of the titanium dioxide particles, based on 100 parts by weight of the toner particle. ### Claim 10 A toner for developing an electrostatic charge image, the toner comprising: a toner particle; sol-gel silica particles disposed on the toner particle and having an average sphericity value in a range of from about 0.8 to about 0.97, a Braunauer-Emmett-Teller (BET) specific surface area of about 30 m2/g to about 70 m2/g, and an average primary particle diameter in a range of from about 10 nm to less than 80 nm, wherein the sphericity value is a ratio between a shortest diameter and a longest diameter of each of the sol-gel particles and a ratio of the number of sol-gel silica particles having a sphericity value of less than about 0.97 to the total number of the sol-gel silica particles is at least about 50%; hydrophobically surface-treated fumed silica particles having average primary particle diameters in a range of from about 7 nm to about 50 nm disposed on the toner particle and in gaps between the sol-gel particles; and hydrophobically surface-treated titanium dioxide particles having average primary particle diameters in a range of from about 10 nm to about 50 nm disposed on the toner particle, wherein a (D84v/D16v)1/2 value of the sol-gel silica particles is in a range of from about 1.7 to about 2.3, in which D16v is a particle diameter at which a cumulative percentage of 16% is attained, and D84v is a particle diameter at which a cumulative percentage of 84% is attained, in a cumulative volume distribution of the sol-gel silica particles as measured by the Coulter method.