Abstract: A silica particle includes a silica particle body and a titania coating layer formed on a surface of the silica particle body through a reaction of a titanium compound having a structure in which a hydrocarbon group bonds to a titanium atom through an oxygen atom. The silica particle has absorption at a wavelength of about 400 nm or more and about 800 nm or less in an ultraviolet-visible absorption spectrum.

Abstract: A metatitanic acid particle surface-treated with a silane compound having a hydrocarbon group has absorption at a wavelength of about 400 nm or more and about 800 nm or less in an ultraviolet-visible absorption spectrum, and has an absorption peak at a wave number of about 2700 cm?1 or more and about 3000 cm?1 or less in an infrared absorption spectrum.

Abstract: A titanium oxide particle surface-treated with a silane compound having a hydrocarbon group has absorption at a wavelength of about 400 nm or more and about 800 nm or less in an ultraviolet-visible absorption spectrum, and has an absorption peak at a wave number of about 2700 cm?1 or more and about 3000 cm?1 or less in an infrared absorption spectrum.

Abstract: A method for manufacturing a fatty acid metal salt particle includes forming a coating layer including a fatty acid metal salt on a surface of a core material particle in supercritical carbon dioxide.

Abstract: The invention provides a method of producing silica particles, the method including preparing an alkali catalyst solution containing an alkali catalyst in a solvent including an alcohol, at a concentration of from about 0.6 mol/L to about 0.85 mol/L; and supplying tetraalkoxysilane into the alkali catalyst solution, and concurrently supplying an alkali catalyst into the alkali catalyst solution at a rate of from about 0.1 mol to about 0.4 mol per mole of the total amount of supply of the tetraalkoxysilane supplied in one minute.

Abstract: A resin particle having: a resin mother particle; and silica particles external added onto the surface of the resin mother particle, wherein a primary particles of the silica particles which have a volume average particle diameter of from 100 nm to 500 nm, a particle size distribution index of from 1.40 to 1.80 and an average circularity of from 0.5 to 0.85 has a regression line expressed by the following expression (1) with respect to the circularity and the volume average particle diameter (nm): Circularity=?×(Volume average particle diameter)/1000+???(1) wherein ? is from ?2.5 to ?0.9, and ? is from 0.8 to 1.2.

Abstract: A method for producing silica particles, includes preparing a silica particle dispersion containing silica particles, and a solvent containing an alcohol and water, and bringing supercritical carbon dioxide into contact with the silica particle dispersion to remove the solvent.

Abstract: A method of manufacturing a silica particle dispersion, includes preparing a silica particle dispersion containing silica particles and a solvent, primary concentrating the silica particle dispersion, adding a hydrophobizing treatment agent to the silica particle dispersion after the primary concentrating, and secondary concentrating the silica particle dispersion after the adding.

Abstract: The present invention provides silica particles including primary particles, the primary particles having an average particle diameter in a range of from about 100 nm to about 500 nm, a particle size distribution index in a range of from about 1.40 to about 1.80, and an average roundness in a range of from about 0.5 to about 0.85, and about 95% or more, by number of particles, of the primary particles satisfying following Formula (1) with respect to a roundness (R) and a particle diameter (D) (nm): R=?×D/1000+???Formula (1) (?2.5????0.9, 0.8???1.2).

Abstract: A resin particle including: a resin mother particle; and silica particles externally added onto a surface of the resin mother particle, wherein primary particles of the silica particles, the primary particles which have a volume average particle diameter of from 80 nm to 300 nm, a particle size distribution index of from 1.10 to 1.40, an average circularity of from 0.70 to 0.92 and an average circularity distribution index of from 1.05 to 1.50, and a proportion of the primary particles having an average circularity of 0.95 or more is not more 10% by number.

Abstract: Provided is an electrostatic charge image developing toner including toner base particles which contain a polyester resin and a vinyl resin and does not have a coating layer and wherein the concentration of the polyester resin on the particle surface is higher than the concentration of the polyester resin in the inside of the particles, and a sol-gel silica which has an average circularity of from 0.75 to 0.9, on the surface of the toner base particles.

Abstract: The invention provides silica particles including primary particles, the primary particles having a volume average particle diameter of from about 80 nm to about 300 nm, a particle size distribution index of from about 1.10 to about 1.40, an average circularity of from about 0.70 to about 0.92, and a circularity distribution index of from about 1.05 to about 1.50, the silica particles including primary particles having a circularity of about 0.95 or greater at a proportion of about 10% or less by number of particles.

Abstract: A resin particle having: a resin mother particle; and silica particles external added onto the surface of the resin mother particle, wherein a primary particles of the silica particles which have a volume average particle diameter of from 100 nm to 500 nm, a particle size distribution index of from 1.40 to 1.80 and an average circularity of from 0.5 to 0.85 has a regression line expressed by the following expression (1) with respect to the circularity and the volume average particle diameter (nm): Circularity=?×(Volume average particle diameter)/1000+???(1) wherein ? is from ?2.5 to ?0.9, and ? is from 0.8 to 1.2.

Abstract: A method for manufacturing a fatty acid metal salt particle includes forming a coating layer including a fatty acid metal salt on a surface of a core material particle in supercritical carbon dioxide.

Abstract: Provided is an electrostatic charge image developing toner including toner base particles which contain a polyester resin and a vinyl resin and does not have a coating layer and wherein the concentration of the polyester resin on the particle surface is higher than the concentration of the polyester resin in the inside of the particles, and a sol-gel silica which has an average circularity of from 0.75 to 0.9, on the surface of the toner base particles.

Abstract: An electrostatic charge image developing toner includes toner particles, and an external additive. The toner particles are (1) prepared by forming aggregated particles by aggregating resin particles in a raw material dispersion in which the resin particles are dispersed, and causing the aggregated particles to coalesce by heating an aggregated particle dispersion in which the aggregated particles are dispersed so as to form the toner particles, or (2) obtained by kneading and pulverizing a material including a binder resin and a release agent, and the external additive is silica particles having an average diameter in the range of 100 nm to 500 nm, an average circularity in the range of 0.5 to 0.85, and an average of a ratio of a circle-equivalent diameter Da obtained by plane image analysis to a maximum height H obtained by 3-D image analysis of greater than 1.5 and less than 1.9.

Abstract: An electrostatic charge image developing toner includes: toner particles; and an external additive. The external additive contains sol-gel silica having a volume average particle diameter of from about 70 nm to about 400 nm and an average circularity of from about 0.5 to about 0.9, and a dielectric loss factor of the toner is from about 5×10?3 to about 30×10?3 when the toner is kept for 24 hours under the environment of a temperature of 28° C. and a humidity of 85%.

Abstract: An electrostatic charge image developing toner includes toner particles, and an external additive. The toner particles are (1) prepared by forming aggregated particles by aggregating resin particles in a raw material dispersion in which the resin particles are dispersed, and causing the aggregated particles to coalesce by heating an aggregated particle dispersion in which the aggregated particles are dispersed so as to form the toner particles, or (2) obtained by kneading and pulverizing a material including a binder resin and a release agent, and the external additive is silica particles having an average diameter in the range of 100 nm to 500 nm, an average circularity in the range of 0.5 to 0.85, and an average of a ratio of a circle-equivalent diameter Da obtained by plane image analysis to a maximum height H obtained by 3-D image analysis of greater than 1.5 and less than 1.9.

Abstract: Disclosed are silica particles having a volume average particle size of from about 100 nm to about 500 nm, an average circularity degree of from about 0.5 to about 0.85, and an average value of the ratios of circle equivalent diameters Da of the silica particles obtained by a flat image analysis to maximum heights H of the silica particles obtained by a stereoscopic image analysis of more than 1.5 and less than 1.9.

Abstract: A method of manufacturing a silica particle dispersion, includes preparing a silica particle dispersion containing silica particles and a solvent, primary concentrating the silica particle dispersion, adding a hydrophobizing treatment agent to the silica particle dispersion after the primary concentrating, and secondary concentrating the silica particle dispersion after the adding.