An electrostatic latent image developing toner includes a plurality of toner particles each including a toner mother particle and an external additive attached to a surface of the toner mother particle. The external additive includes a plurality of resin particles each containing first temperature responsive polymer domains and second temperature responsive polymer domains. The second temperature responsive polymer domains have a lower critical solution temperature (LCST) higher than that of the first temperature responsive polymer domains.

A layered inorganic mineral including a surface treated with a fluorine-containing compound, where the layered inoganic mineral that can be favorably used for a toner that is excellent in high charging ability, charging stability, and low temperature fixing ability, and that can exhibits high reliability during cleaning.

[Object] The purpose of the present invention is to provide a charge control agent for polymerized toners and particularly for color toners, which has a large charge amount and environmentally stable charging characteristics.

[Solving Means] Since a charge control agent including a pyrazolone derivative represented by a general formula (1) or a salt of the derivative as an active ingredient has a large charge amount and excellent environmental stability of charging, it has an excellent charge-imparting effect for use in polymerized toners and particularly in color toners. (in the formula, R.sub.1, R.sub.2, and R.sub.3 each independently represent a substituted or unsubstituted C1 to C20 linear or branched alkyl group, a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted condensed polycyclic aromatic group.)

[Object] The purpose of the present invention is to provide a charge control agent for polymerized toners and particularly for color toners, which has a large charge amount and environmentally stable charging characteristics.

[Solving Means] Since a charge control agent including a pyrazolone derivative represented by a general formula (1) or a salt of the derivative as an active ingredient has a large charge amount and excellent environmental stability of charging, it has an excellent charge-imparting effect for use in polymerized toners and particularly in color toners. (in the formula, R.sub.1, R.sub.2, and R.sub.3 each independently represent a substituted or unsubstituted C1 to C20 linear or branched alkyl group, a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted condensed polycyclic aromatic group.)

An image forming apparatus includes an image forming unit including an image carrier, a developing device that includes a developer containing a toner, and a cleaning device including a blade; and a transfer device. The toner contains toner particles having a volume-average particle size of 3 m or more and 5 m or less, a spherical inorganic external additive having a number-average particle size of 80 nm to 200 nm, and an organic component. In the cleaning device, an external additive residue in or near a contact region between the image carrier and the blade contains the organic component and an inorganic component, the area ratio of the organic component to the inorganic component is 3/7 or more and 7/3 or less, and the area ratio of the inorganic component that is spherical to the external additive residue is 30% or more.

In a two-component developer, external additive particles of toner particles include resin particles. The resin particles contain a crosslinked resin including a repeating unit derived from a crosslinking agent. Carrier particles each include a carrier core and a coat layer covering a surface of the carrier core. The coat layers contain a coating resin and barium titanate particles. The coating resin includes a silicone resin. The barium titanate particles have a number average primary particle diameter within a range of 100 nm to 500 nm. The barium titanate particles have a content within a range of 5 parts by mass to 45 parts by mass relative to 100 parts by mass of the coating resin. A rate of a mass of the coat layers to a mass of the carrier cores is greater than 0.0% by mass and no greater than 4.9% by mass. The carrier cores have a shape factor within a range of 34.0% to 85.0%.

In a two-component developer, external additive particles of toner particles include resin particles. The resin particles contain a crosslinked resin including a repeating unit derived from a crosslinking agent. Carrier particles each include a carrier core and a coat layer covering a surface of the carrier core. The coat layers contain a coating resin and barium titanate particles. The coating resin includes a silicone resin. The barium titanate particles have a number average primary particle diameter within a range of 100 nm to 500 nm. The barium titanate particles have a content within a range of 5 parts by mass to 45 parts by mass relative to 100 parts by mass of the coating resin. A rate of a mass of the coat layers to a mass of the carrier cores is greater than 0.0% by mass and no greater than 4.9% by mass. The carrier cores have a shape factor within a range of 34.0% to 85.0%.

An electrostatic charge image developing toner contains a binder resin and resin particles, in which the binder resin includes an amorphous resin and a crystalline resin, the resin particles contain a styrene-(meth)acrylate-based copolymer, in a case where a glass transition temperature obtained by Fox equation from a ratio of constituent monomers in the entire resin particles is defined as Tg(C1)? C. and a glass transition temperature actually measured with a differential scanning calorimeter is defined as Tg(E)? C., 5.0?Tg(E)?Tg(C1)?20.0, and in a case where a glass transition temperature obtained by Fox equation using a ratio of constituent monomers, calculated from a surface analysis of the resin particles, is defined as Tg(C2)? C., Tg(C1)>Tg(C2).

An electrostatic image developing toner includes a binder resin and crosslinked resin particles. In a cross section of the electrostatic image developing toner, the area fraction Sc of the crosslinked resin particles is 5% or more and 40% or less, the proportion Se of voids in the cross section is 1% or more and 10% or less, and the ratio Se/Sc of the proportion Se of voids to the area fraction Sc is 0.05 or more and 1.5 or less.

A method for manufacturing a surface-treated sol-gel silica particle that can impart good flowability when added into a toner and has little change in charge during environment change; a manufacturing method therefor; and an external additive for a toner containing the surface-treated sol-gel silica particle. The method includes steps of: (A1) obtaining a hydrophilic sol-gel silica particle having a silanol group on a surface and substantially composed of a SiO.sub.2 unit; (A2) adding a compound having a (C.sub.2H.sub.5).sub.3Si group or a R.sup.1R.sup.2.sub.2Si group, and introducing a (C.sub.2H.sub.5).sub.3SiO.sub.1/2 unit or a R.sup.1R.sup.2.sub.2SiO.sub.1/2 unit on a surface of the hydrophilic sol-gel silica particle to obtain a preliminarily treated silica particle; and (A3) adding a compound having a R.sup.3.sub.3Si group, and further introducing a R.sup.3.sub.3SiO.sub.1/2 unit on a surface of the preliminarily treated silica particle to obtain a surface-treated sol-gel silica particle.