Provided is a toner including a binder resin, and a charge-controlling agent, wherein a volume average particle diameter X of the toner after a stress treatment satisfies Formula (1), and an amount Y of fine toner particles having particle diameters of 3 micrometers or smaller and circularity of 0.70 or less satisfies Formula (2).

A toner has a toner particle including a binder resin, the binder resin includes a polymer A, the polymer A contains a first monomer unit derived from a first polymerizable monomer and a second monomer unit derived from a second polymerizable monomer, the first polymerizable monomer is selected from (meth)acrylic acid esters having an alkyl group having 18 to 36 carbon atoms, the content of the first monomer unit in the polymer A is 5.0 mol % to 60.0 mol %, the content of the second monomer unit in the polymer A is 20.0 mol % to 95.0 mol %, the SP value of the first monomer unit and the SP value of the second monomer unit satisfy a predetermined relationship, the polymer A includes a predetermined polyvalent metal, and the content of the polyvalent metal is 25 ppm to 500 ppm.

A toner comprising a toner particle comprising: a toner base particle; and an organosilicon polymer at a surface of the toner base particle, wherein protruded portions constituted from the organosilicon polymer are present at the surface of the toner base particle, when a specific reciprocating shaking test is carried out, the toner particle is measured in terms of a total area S of a surface of the toner particle and an area Sc of regions of the surface of the toner base particle coated with the organosilicon polymer at the surface of the toner particle before and after the test, values of Sc/S for the toner particle before and after the test are respectively defined as R.sub.0 and R.sub.1, the value of R.sub.0 is 0.30 to 0.70, a value of (R.sub.0R.sub.1)/R.sub.0 is 0.20 or less, and a storage elastic modulus at 100 C. of the toner is 8000 to 50,000 Pa.

A toner includes toner particle containing at least a strontium titanate particle on the surface of the toner particle, and the toner is a water-washed toner from which strontium titanate particle desorbable by water washing are removed by water washing. The water-washed toner contains the strontium titanate particle having a number average particle diameter of primary particle (D1) of 10 nm or more and 150 nm or less, and when the distribution of an Sr element in the water-washed toner in the depth direction is determined, (i) the Sr element abundance on the outermost surface x satisfying 0.00<x0.80, and (ii) the difference between x and xp xpx satisfying 0.00<xpx0.95, where xp is the maximum peak value (atomic %) of the Sr element abundance in the region from the outermost surface to 50 nm.

An image forming apparatus in which occurrence of an image failure in association with contamination caused by an external additive, such as silica, adhering to a charging unit is suppressed. The image forming apparatus is configured to charge an image bearing member through use of the charging unit, and uses toner having, on a surface thereof, strontium titanate particles and silica particles having predetermined physical properties.

A toner has a toner particle including a binder resin, the binder resin includes a polymer A, the polymer A contains a first monomer unit derived from a first polymerizable monomer and a second monomer unit derived from a second polymerizable monomer, the first polymerizable monomer is selected from (meth)acrylic acid esters having an alkyl group having 18 to 36 carbon atoms, the content of the first monomer unit in the polymer A is 5.0 mol % to 60.0 mol %, the content of the second monomer unit in the polymer A is 20.0 mol % to 95.0 mol %, the SP value of the first monomer unit and the SP value of the second monomer unit satisfy a predetermined relationship, the polymer A includes a predetermined polyvalent metal, and the content of the polyvalent metal is 25 ppm to 500 ppm.

Provided is a toner having low-temperature fixability and excellent heat-resistant storage stability, controlling charge reduction of a developer due to development stress, and being able to maintain high image quality throughout the product life (life), and the method for producing the toner, and the developer containing the toner and the image forming device using the developer. The toner includes: toner core particles containing at least a binder resin and a release agent; and external additives externally added to surfaces of the toner core particles. The binder resin contains a crystalline polyester-based resin, the toner core particles have a viscosity at 90? C. of 100000 to 250000 Pa.Math.s, the external additives are small size silica particles hydrophobized and barium titanate particles hydrophobized, and the barium titanate particles have an average primary particle size of 20 to 40 nm and a coverage of 2 to 7% for the toner core particles.

A method for producing a toner for electrostatic charge image development includes: aggregating binder resin particles in a dispersion containing the binder resin particles to form aggregated particles; terminating growth of the aggregated particles by adding an alkaline aqueous solution to a dispersion containing the aggregated particles to increase a pH of the dispersion containing the aggregated particles; and fusing and coalescing the aggregated particles into toner particles by heating the dispersion containing the aggregated particles. Terminating the growth of the aggregated particles includes, while stirring the dispersion containing the aggregated particles, stepwise or continuously reducing a stirring power per unit volume.

A toner package includes activated carbon and a toner composition. The toner composition includes toner particles and toner particle surface additives disposed on the toner particles. An amount of activated carbon present in the toner package is sufficient to reduce volatile organic compounds (VOCs).

A thermal treatment apparatus includes a treatment tank including a treatment chamber to perform thermal treatment on toner particles; a toner particle supply unit configured to supply toner particles into the treatment chamber; and a hot air supply unit including a supply port to supply hot air into the treatment chamber. The supply port of the hot air supply unit is disposed on a ceiling of the treatment chamber. The treatment tank further includes: a columnar member that is vertically disposed at the center inside of the treatment chamber; and a protruded member that is disposed at an upper end of the columnar member and has an approximately conical shape protruding toward the ceiling. The columnar member has a cylindrical shape and a radius of curvature RCP (mm) of an upper end edge in a vertical cross-section thereof is 5<RCP<75.