A toner comprising: a toner particle comprising a binder resin and boric acid; and an external additive A having a primary particle major diameter of 80 to 200 nm, wherein in ATR-IR analysis of the toner particle in an ATR method using germanium as an ATR crystal, a peak corresponding to boric acid is detected, the average value of a shape factor SF-1 of the external additive A is 105 to 250, and the average value of a shape factor SF-2 of the external additive A is 102 to 250.

An image forming apparatus forms an image on a recording medium using first to fourth toners, and includes an intermediate transfer target; a primary transfer unit that transfers a first toner image, a second toner image, a third toner image, and a fourth toner image to the intermediate transfer target in stated order; and a secondary transfer unit that collectively transfers the first to fourth toner images onto the recording medium. The first toner image, the second toner image, the third toner image, and the fourth toner image include the first toner, the second toner, the third toner, and the fourth toner, respectively. The first to fourth toners each include toner particles. The toner particles each include a toner mother particle and an external additive attached to the surface of the toner mother particle. The external additive includes fluororesin particles and silica particles.

A toner comprising a toner particle, and an external additive on a surface of the toner particle, wherein the external additive comprises an agglomerate of fine silica particles surface-treated with silicone oil; when a number-average particle diameter of the agglomerate of the fine silica particles is defined as Rb, the Rb is 12 to 80 nm; when an integrated value of a D unit is defined as A, which obtained when an integrated value of a Q unit is set to 100 in a CP/MAS measurement in a .sup.29Si-solid-state NMR of the fine silica particles, the A is 120 to 300, and the agglomerate of the fine silica particles has a coefficient of variation of particle diameters of 1.00 to 3.00, based on a number of the agglomerate of the fine silica particles.

A toner comprising a toner particle comprising a binder resin and boric acid, wherein the toner has an average circularity of 0.95 or more, and the toner has a shape factor SF1 of 105 to 125, and a method for producing to provide a toner with excellent durability for which the improvement of transfer rate with the above physical characteristics.

An object of the present invention is to provide an electrostatic charge image developing toner, a two-component developer, and an image forming method, each capable of employing a two-component trickle touchdown developing system which ensures excellent image density stability and no occurrence of ghost and is used in an electrophotographic copier or an electrostatic recording device. The present invention provides an electrostatic charge image developing toner having positive chargeability; containing a styrene acrylic resin as the binding resin; and containing a nigrosine-containing positive charge control agent and a negative charge control agent as the charge control agent, in which the percentage content of the percentage content of the negative charge control agent in all charge control agents is not less than the percentage content of the positive charge control agent.

A toner comprising a toner particle comprising a binder resin, a crystalline material, and a silica particle, wherein a number average particle diameter D1 of the silica particle comprised in the toner particle is 400 to 3000 nm; the silica particle has a pointed portion; and the crystalline material comprises a compound having an ester group.

A toner comprising a toner particle comprising a binder resin, a nonmagnetic inorganic oxide particle A, and a magnetic iron oxide particle B, wherein a softening point of a chloroform-soluble component of the toner particle is not greater than 90° C.; the nonmagnetic inorganic oxide particle A and the magnetic iron oxide particle B are internally added to the toner particle; the nonmagnetic inorganic oxide particle A comprises as its main component at least one element selected from the group consisting of Si, Mg, Al, Ti, and Sr; a proportion of the inorganic oxide particles having a long diameter of specific length is in specific range; and a value of a ratio of a number-average particle diameter of the long diameter for the nonmagnetic inorganic oxide particle A, to a number-average particle diameter of the long diameter for the magnetic iron oxide particle B, is 5 to 30.

A developing device includes a developing container, a first stirring conveyance member, a second stirring conveyance member, and a developer carrying member. The developing container includes a first conveyance chamber and a second conveyance chamber that are arranged mutually side by side, and contains a two-component developer including a carrier and a toner. The first stirring conveyance member stirs and conveys the developer present in the first conveyance chamber in a first direction. The second stirring conveyance member stirs and conveys the developer present in the second conveyance chamber in a second direction. The developing container includes a toner replenishment portion that directly feeds a replenishment toner into the developer present in the first conveyance chamber from an upstream side of the first conveyance chamber with respect to the first direction. The carrier satisfies 0.73≤FR×AD/shape factor≤2.10.

Provided is a hydrophobic silica powder that can be obtained by the sol-gel process, and that is excellent in charge properties. The hydrophobic silica powder has a hydrophobicity of 50% or more, a saturated water content of 4% or less, and a nitrogen content of 0.05% or more.

An external additive for a toner comprising a silica particle surface-treated with a polyhydric acid metal salt particle, wherein the polyhydric acid metal salt particle is particle of a salt of a polyhydric acid and a titanium compound, and a toner comprising a toner particle, and an external additive for a toner on the surface of the toner particle, wherein the external additive for a toner is the above external additive for a toner.