A positively chargeable toner includes a plurality of toner particles. The toner particles each include a toner mother particle and an external additive. The toner mother particle includes a toner core containing a binder resin and a shell layer covering a surface of the toner core. The external additive includes a plurality of silica particles. The silica particles are each present on a surface of the shell layer and include a silica base having a surface treated with a surface treatment agent. The surface treatment agent includes a first treatment agent having a carboxyl group in a molecule thereof. The toner core and each of the silica particles is bonded to each other through a specific covalent bond. An amount of ring-unopened oxazoline groups included in 1 g of the positively chargeable toner as measured by gas chromatography-mass spectrometry is at least 0.10 mol and no greater than 100 mol.

The magenta toner for developing electrostatic images includes colored resin particles containing a binder resin and a magenta colorant, and an external additive. A volume average particle diameter of the colored resin particles is from 5.5 m to 7.0 m. The external additive contains silica particles. The silica particles contain at least silica particles A having a number average particle diameter of from 5 nm to 30 nm and silica particles B having a number average particle diameter of from 31 nm to 100 nm; wherein a total content of the silica particles is from 0.5 part by mass to 4.5 parts by mass, with respect to 100 parts by mass of the colored resin particles. A liberation rate of the silica particles calculated by a specific liberation rate measuring method is in a range of from 2.2% to 9.5%.

An electrostatic latent image developing toner includes a plurality of toner particles each including a toner core and a shell layer covering a surface of the toner core. The shell layer contains a hydrophobic thermoplastic resin and a positively chargeable hydrophilic water-insoluble resin. An existing amount A of alkali metal elements present in a surface layer of the shell layer measured by X-ray photoelectron spectroscopy and an existing amount B of alkali metal elements present in a toner particle as a whole measured by fluorescent X-ray analysis satisfy expressions (a) and (b) shown below
A300 ppm(a)
0.5A/B<1.0(b).

Toner particles contain a core-shell resin particle containing at least one (sulfo) polyester containing a metal on nanoparticle, and a shell containing a metal ion nanoparticle.

An electrostatic latent image developing toner includes a plurality of toner particles each including a toner mother particle and inorganic particles attached to a surface of the toner mother particle. The toner mother particle includes a toner core (11) and a shell layer (12) covering a surface of the toner core (11). The shell layer (12) includes film-shaped first domains (12a) and particle-shaped second domains (12b). The first domains (12a) are substantially formed from a non-cross-linked resin. The second domains (12b) are substantially formed from a cross-linked resin. The cross-linked resin has a glass transition point higher by 40 C. or more than that of the non-cross-linked resin. The first domains (12a) have a surface adsorption force of at least 20.0 nN and no greater than 40.0 nN. The second domains (12b) have a surface adsorption force of at least 4.0 nN and less than 20.0 nN.

A chemically prepared multilayered toner composition, according to one example embodiment, includes a core having a first polymer binder, a second polymer binder, a colorant, and a release agent. A first layer is formed around the core wherein the first layer includes the same second polymer binder that is in the toner core. A second layer is formed on the surface of the first layer, wherein the second layer includes a third polymer binder. A borax coupling agent is between the first and second layers. In an embodiment the ratio of the second polymer in the core to second polymer in the first layer is about 50:50. The second layer can also be referred to as a shell that is formed over the toner particle having a center core, first layer and borax coupling agent. In another embodiment, the core does not contain a second polymer binder.

An electrostatic latent image developing toner includes toner particles each including a toner mother particle and an external additive. The toner mother particle includes a composite core and a shell layer. The composite core is a composite of a toner core, organic particles, and polyhedral magnetic particles. The organic particles each contain a releasing agent and adhere to a surface of the toner core. The magnetic particles include magnetic particles adhering to the surface of the toner core and magnetic particles adhering to surfaces of the organic particles. An amount of the magnetic particles is 0.5 parts by mass to 2.0 parts by mass relative to 100 parts by mass of the toner cores. In a cross-sectional image of each toner particle, an area of protruding portions of the magnetic particles, which protrude from the shell layer, accounts for 10% to 75% of an overall area of the magnetic particles.

A toner includes an external additive particle that is a complex oxide containing a titanium dioxide (TiO.sub.2) and a silicon dioxide (SiO.sub.2). A detection amount of titanium (Ti) detected through an elementary analysis based on energy-dispersive X-ray spectrometry is equal to or higher than about 0.590 percent by weight and equal to or lower than about 0.967 percent by weight.

A chemically prepared toner composition according to one example embodiment includes a core including a first polymer binder, a colorant and a release agent; a shell that is formed around the core that includes a second polymer binder; and a borax coupling agent between the core and the shell and an alkoxysilane hydrocarbon or combination of different alkoxysilane hydrocarbons that are bonded to the outer surface of the shell using a hydrolytic deposition process. This successful alkoxysilane hydrocarbon surface treatment on the outer surface of the toner particle results in attaining a desirable charge stability in hot and humid environments and ultimately improving the quality of the toner, especially by reducing toner dusting, toner fuming and ultra-fine particles generation.

A method for producing core shell toner for electrophotography according to one embodiment, includes surface treating the outer surface of a core shell toner particle with a alkoxysilane hydrocarbon or combination of different alkoxysilane hydrocarbons using a hydrolytic deposition process after the core shell toner particle is fully formed. This method results in the bonding of the alkoxysilane hydrocarbon or combination of different alkoxysilane hydrocarbons to the outer surface of the core shell toner particle. In an alternative method, the outer surface of the toner is surface treated with the alkoxysilane hydrocarbon solution and then fused to form toner particles. The alkoxysilane hydrocarbon surface treated core shell toner also can be mixed with magnetic carrier beads to form a developer mix to be used in a dual component development electrophotographic printer.