Abstract: Provided are methods of preparing silica particles having two maximum values in number particle size distribution, wherein in the two maximum values, a particle size ratio (a maximum value of a small-size side/a maximum value of a large-size side) between a maximum value of a large-size side and a maximum value of a small-size side is from 0.02 to 0.3, and a number ratio (a number of silica particles having a maximum value of the small-size side/number of silica particles having a maximum value of the large-size side) is from 1 to 100, and particles within a range of 10% from the large-size side of the silica particles have an average circularity of from 0.65 to 0.90 and an average shrinkage ratio of from 10 to 50.

Abstract: Silica composite particles in which a silica particle surface is sequentially surface-treated with a titanium compound in which an organic group is bonded to a titanium atom through an oxygen atom, and a hydrophobizing agent are provided, in which a titanium content in the silica composite particles measured using fluorescence X-ray is from 0.001% by weight to 10% by weight; a titanium content of a surface layer of the silica composite particles satisfies the following Formula (1); an average particle diameter of the silica composite particles is from 30 nm to 500 nm; and a particle size distribution index of the silica composite particles is from 1.1 to 1.5: 0.6<Y/X<1.8??(1) wherein X represents a titanium content in silica composite particles measured using fluorescence X-ray, and Y represents a titanium content of the silica composite particle surface obtained by XPS measurement.

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: An electrostatic charge image developing toner includes toner particles and silica particles that have a titanium content of from 0.001% by weight to 10% by weight in a surface layer, an average particle diameter of from 30 nm to 500 nm, and a particle size distribution index of from 1.1 to 1.5, and are surface-treated with a titanium compound in which an organic group is bonded to a titanium atom via an oxygen atom, and a hydrophobizing agent in sequence.

Abstract: A method of preparing silica composite particles includes preparing an alkali catalyst solution containing an alkali catalyst at a concentration of from 0.6 mol/L to 0.85 mol/L, in a solvent containing alcohol; and supplying, into the alkali catalyst solution, (i) a mixed solution of tetraalkoxysilane and an organic titanium compound in which an organic group is coupled to a titanium atom through oxygen, and (ii) an alkali catalyst. The mixed solution is supplied at a supply amount of from 0.001 mol/(mol·min) to 0.01 mol/(mol·min) relative to the alcohol, and the alkali catalyst is supplied at a supply amount of from 0.1 mol to 0.4 mol, relative to 1 mol of a total supply amount of the tetraalkoxysilane and the organic titanium compound supplied per one minute.

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: 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: An electrostatic charge image developing toner includes toner particles and silica particles that have a titanium content of from 0.001% by weight to 10% by weight in a surface layer, an average particle diameter of from 30 nm to 500 nm, and a particle size distribution index of from 1.1 to 1.5, and are surface-treated with a titanium compound in which an organic group is bonded to a titanium atom via an oxygen atom, and a hydrophobizing agent in sequence.

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: Silica composite particles in which a silica particle surface is sequentially surface-treated with a titanium compound in which an organic group is bonded to a titanium atom through an oxygen atom, and a hydrophobizing agent are provided, in which a titanium content in the silica composite particles measured using fluorescence X-ray is from 0.001% by weight to 10% by weight; a titanium content of a surface layer of the silica composite particles satisfies the following Formula (1); an average particle diameter of the silica composite particles is from 30 nm to 500 nm; and a particle size distribution index of the silica composite particles is from 1.1 to 1.5: 0.6<Y/X<1.8??(1) wherein X represents a titanium content in silica composite particles measured using fluorescence X-ray, and Y represents a titanium content of the silica composite particle surface obtained by XPS measurement.

Abstract: Provided are silica particles having two maximum values in number particle size distribution, wherein in the two maximum values, a particle size ratio (a maximum value of a small-size side/a maximum value of a large-size side) between a maximum value of a large-size side and a maximum value of a small-size side is from 0.02 to 0.3, and a number ratio (a number of silica particles having a maximum value of the small-size side/number of silica particles having a maximum value of the large-size side) is from 1 to 100, and particles within a range of 10% from the large-size side of the silica particles have an average circularity of from 0.65 to 0.90 and an average shrinkage ratio of from 10 to 50.

Abstract: An electrostatic charge image developing toner includes toner particles, and silica composite particles that contain silicon oxide and from 0.001% by weight to 10% by weight of titanium, and have an average particle size of from 30 nm to 500 nm, a particle size distribution index of from 1.10 to 1.50, and an average circularity of from 0.50 to 0.85.

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: 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.

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: 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 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 inn, 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.