A toner has a toner particle that has a binder resin and a release agent, wherein when the temperature when G=1.010.sup.5 Pa in a dynamic viscoelastic measurement on the toner is denoted by Ta, and the glass transition temperature in a differential scanning calorimetric measurement on the toner is denoted by Tg, the Ta and the Tg satisfy the following formulas:
40 C.Tg70 C.,
60 C.Ta90 C., and
0 C.TaTg35 C.; and the toner has a storage elastic modulus G having a minimum value in the range from 110 C. to 150 C. in a dynamic viscoelastic measurement on the toner.

A toner comprising an external additive and a toner particle including a binder resin, a colorant and inorganic fine particles A, wherein the external additive contains an external additive B, a number average particle diameter of primary particles of the external additive B is 30 to 200 nm, an adhesion index of the external additive B to the toner particle is 0.00 to 3.00, a number average particle diameter of primary particles of the inorganic fine particles A is greater than that of the external additive B, and in SEM observations of the toner under specific condition, the number of particles (Na) of the external additive B in a 2 m square region of the toner surface and the number of particles (Nb) of the external additive B observed in a state of overlapping with the inorganic fine particles A in the region satisfy Nb/Na of 0.20 or more.

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.

Mixtures are disclosed containing a plurality of charged pigment particles and a one or more charge control agents. At least one of the charge control agents has a chemical structure that includes a cationic head group, such as an ammonium cation or an iminium compound, and a non-ionic, polar functional group, other than an acyclic secondary amide group. The mixtures are useful as dispersions for forming electrophoretic media that may be incorporated into electrophoretic displays. Alternatively, the dispersions may be useful for forming electrophotographic toners and dispersions for other printing applications.

The present invention provides a toner for electrostatic-image development comprising color resin particle containing a binder resin, a colorant, a charge control agent, and a thickener, wherein the binder resin is a copolymer including styrene-monomer unit and (meth)acrylate monomer unit, the thickener is a resin containing a nitrogen atom, and the content of nitrogen atom is 150 to 1500 mass ppm in the toner for electrostatic-image development.

Provided is, for example, a compound excellent in light fastness and storage stability. The compound is characterized by having a structure represented by the following formula (1) or (2).

##STR00001##

A hydrophobic silica powder is disclosed that exhibits reduced desorption of a charge control agent, on the charge-controllable surface, and that is capable of imparting charge properties within a suitable range to toner resin particles to which the hydrophobic silica particles are externally added. A hydrophobic silica powder is characterized in that (1) the hydrophobic silica powder has a hydrophobicity of 50% or more; (2) an amount X is 0.1 mass % or more, the amount X being an amount of at least one compound selected from the group consisting of a quaternary ammonium ion, a mono-azo complex, and a mineral acid ion extracted with a mixture solvent of methanol and a ethanesulfonic acid aqueous solution: and (3) the amount X and an amount Y satisfy the following formula (I):

Y/X<0.15(I),

the amount Y being an amount of the at least one compound extracted with water.

A toner comprising a toner particle that contains a binder resin, a resin represented by formula (1), and wax, wherein the wax contains an ester compound that exhibits a compatibility at 100 C. of at least 5.0 mass parts per 100.0 mass parts of the binder resin: wherein in formula (1), P.sup.1 represents a macromolecular segment; L.sup.1 represents a single bond or a divalent linking group; R.sup.1 to R.sup.3 each independently represent a hydrogen atom, halogen atom, alkyl group, alkoxy group, hydroxy group, or aryl group; m represents a positive integer; and when m is equal to or greater than 2, a plurality of L.sup.1's, a plurality of R.sup.1's, a plurality of R.sup.2's, and a plurality of R.sup.3's may be the same as or different from each other.

##STR00001##

A toner contains toner particles. The toner particles each include a toner mother particle containing a binder resin and an external additive attached to a surface of the toner mother particle. The external additive contains titanate compound particles doped with lanthanum and a group 5 element in the periodic table as external additive particles. The amount of the lanthanum is at least 1.50% by mass relative to the total mass of the titanate compound particles. The amount of the group 5 element in the periodic table is at least 0.01% by mass and no greater than 0.60% by mass relative to the total mass of the titanate compound particles.

A toner that is suppressed from deteriorating owing to its long-term use and can maintain high transferability. The toner includes: a toner particle containing an amorphous polyester serving as a binder resin and a polymer A; and inorganic fine particles, wherein the polymer A includes a graft copolymer of a polyolefin and a vinyl-based polymer unit having a carboxylate anion group, and a metal ion having a valence of 2 or more.