A toner includes 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 contains specific external additive particles and silica particles. The specific external additive particles each include a base containing barium titanate and a coat layer covering the base. The coat layer contains antimony tin oxide. Mass ratios of metal elements contained in the toner particles satisfy 0.10<(Ba/Si)<0.60 (formula (1)); 0.05<(Ba/Si)<0.20 (formula (2)); and 1.5<(Sn/Ba)<5.0 (formula (3)).

A toner for developing an electrostatic charge image contains toner particles containing an amorphous resin and a crystalline resin. The ratio Qs1/Qf1 is 1.1 or more and 2.0 or less, where Qf1 is the total area of all endothermic peaks detected during the first temperature rise when the toner particles are analyzed by differential scanning calorimetry after one-day storage under 50° C. conditions, and Qs1 is the total area of all endothermic peaks detected during the first temperature rise when classified toner particles are analyzed by differential scanning calorimetry after one-day storage under 50° C. conditions. The classified toner particles are a fraction of the toner particles in which toner particles having a diameter equal to or larger than the volume-average diameter D50v of the toner particles constitute 10% by number or less.

A toner manufacturing method includes a first step of filtering toner particles obtained by a wet manufacturing method, a second step of squeezing the toner particles and making water pass through the toner particles, and a third step of squeezing the toner particles and ventilating compressed air through the toner particles, in which Condition (1) and Condition (2) are satisfied,

Condition (1): a temperature T of the water passing through the toner particles in the second step satisfies “10° C.≤T≤35° C.”; and

Condition (2): a squeezing pressure P1 in the second step and a squeezing pressure P2 in the third step satisfy “0.2 MPa≤P1<P2≤0.8 MPa”.

A toner classification apparatus comprising a classification rotor in which the classification rotor has a vane A which extends from a rotation center direction of the classification rotor to an outer circumference direction thereof and a vane B having a length longer than that of the vane A, the vane A, and the vane B are disposed so as to satisfy a predetermined relationship, and a toner production method comprising a classification step of carrying out a classification process on particles to be classified by using the toner classification apparatus.

A process directed to emulsion polymerization (EP) methods for producing seed particles reproducibly independent of initiator amount and rate of introduction.

Provided is a method for producing a toner particle including a step of condensing a raw slurry by using a decanter-type centrifugal separator, in an aqueous medium. The step of condensing the raw slurry is carried out under following conditions: a centrifugal force is at least 500 G and less than 4000 G and a temperature is at least Tg−10° C. and not more than Tg+10° C. And a ratio of a colored particles in condensed slurry is within a prescribed range.

Toner classification apparatus comprising classification rotor comprising a plurality of vanes extending from rotation center side of classification rotor to outer circumference side of classification rotor; the plurality of vanes are disposed with prescribed gaps established between vanes; gaps form opening facing rotation center region of classification rotor; each of vanes is disposed such that portion of vane away from of center of rotation of classification rotor is located on more upstream side in a direction of rotation of classification rotor than portion of vane closer to center of rotation of classification rotor; each of vanes has elbow; and in a horizontal cross section provided by sectioning classification rotor in a rotational axis perpendicular direction of classification rotor, shape of vane satisfies prescribed formulae, as well as toner production method comprising classification step of carrying out classification process on particles to be classified by using toner classification apparatus.

A toner classification apparatus comprising a classification rotor, wherein the classification rotor comprises a first vane group containing first vanes and a second vane group containing second vanes, the second vanes have a length shorter than the first vane group; the number of second vanes, which are disposed between two adjacent first vanes, is 1 to 2, independently; each of the first vanes draws first trajectory and each of the second vanes draws second trajectory when the classification rotor rotates, a distance from the center of rotation to an outer circumference side end of the first and second trajectory are defined as L1 and L3, respectively, and a distance from the center of rotation to the center side end of the first and second trajectory are defined as L2 and L4, respectively, L1 to L4 satisfy prescribed relationships, and a toner production method using the toner classification apparatus.

The subject toner includes a toner particle containing a binding resin and an inorganic oxide particle, wherein the inorganic oxide particle is a particle of an oxide containing at least one element selected from the group consisting of: Si; Mg; Al; Ti; and Sr, wherein, when an area of the inorganic oxide particle is represented by Sm and a sectional area of the toner is represented by St in a cross-section of the toner observed with a transmission electron microscope, Sm/St is 4.0% or more, wherein an area Sm of the inorganic oxide particle that occupies each of four regions obtained by dividing the cross-section of the toner by a long diameter of the toner and a perpendicular bisector of the long diameter has a standard deviation of 0.40 or more in the observed cross-section, and wherein the toner has an average circularity of 0.950 or more.

A method for producing a toner includes collecting a toner by using a toner collecting device including: a centrifugation cylinder to which an airflow containing a toner is introduced and in which the toner is centrifugally separated by a swirling flow caused by the introduced airflow; an airflow inlet through which the airflow containing the toner is introduced to the centrifugation cylinder; an airflow outlet that is located at an upper end of the centrifugation cylinder and through which the airflow from which the toner has been separated in the centrifugation cylinder is discharged; a toner collector that is located at a lower end of the centrifugation cylinder and in which the toner separated in the centrifugation cylinder is collected; and a suction unit that suctions the inside of the centrifugation cylinder through the toner collector and has a filtration filter through which the toner in the suctioned airflow is filtered out. The ratio of a suction quantity QBD (m.sup.3/min) of the airflow suctioned by the suction unit to an introduction quantity Qin (m.sup.3/min) at which the airflow containing the toner is introduced to the centrifugation cylinder is more than 0% and 30% or less. The ratio of a filtration area (m.sup.2) of the filtration filter to the suction quantity QBD (m.sup.3/min) of the airflow suctioned by the suction unit is 0.4 or more and 4.0 or less.