A toner including a toner particle containing a binder resin and an ester compound, wherein the binder resin contains a styrene-acrylic-based resin, the styrene-acrylic-based resin contains a specific unit, the ester compound has a specific structure, and a molar ratio of the specific unit to the ester compound is 0.5 to 1.5.

An image forming apparatus is provided. The image forming apparatus includes an image bearer and a cleaning blade configured to remove toner particles remaining on the image bearer. The cleaning blade includes an elastic member in contact with a surface of the image bearer to remove the toner particles. The elastic member has a Martens hardness of from 3 to 8 N/mm.sup.2 when measured by a nanoindentation method with a load of 1 μN. The toner particles comprise toner base particles and an external additive, and the external additive comprise silica particles. A liberation ratio (Xs) of the silica particles liberated from the toner particles is from 40% to 75% when measured by an ultrasonic vibration method. A proportion (R70) of the silica particles having a volume-based particle diameter of 70 nm or more in the silica particles liberated from the toner particles is from 70% to 90% by number.

A toner having high rub resistance is provided. A toner including a toner particle containing a binder resin and a calcium carbonate particle, wherein in X-ray diffractometry of the toner particle by CuKα radiation, when the Bragg angle is defined as θ, (i) the calcium carbonate particle has peaks at 2θ of 26.5°±0.5° and 29.5°±0.5°, (ii) a crystallite diameter of crystals thereof attributed to 2θ=29.5°±0.5° is 10 nm or more and 45 nm or less, and (iii) the ratio (a/b) of a peak intensity “a” at 2θ=26.5°±0.5° to a peak intensity “b” at 20θ=29.5°±0.5° is 0.15 or more and 0.24 or less.

A toner composition having improved toner usage efficiency, wherein toner particles having an average size range of 1-25 μm may be mixed with an extra particulate additive package including a first small silica surface treated with both a silane and an aminosilane having a primary particle size of about 5 nm-20 nm, a second fumed silica having a primary particle size of 30 nm-60 nm, a third silica having a primary particle size of about 70 nm-120 nm, an electro-conductive titania having a primary particle size of 30 nm-60 nm and an acicular titania having a size of about 1.6 μm to 1.7 μm in length and about 130 nm in diameter. An alternative embodiment of the extra particulate additive package does not include a third silica having a primary particle size of about 70 nm-120 nm.

A toner including a toner particle which contains: a resin component containing a binder resin; and an inorganic fine particle, the inorganic fine particle is at least one inorganic fine particle selected from the group consisting of (i) a particle containing CaCO.sub.3, (ii) a particle containing BaSO.sub.4, (iii) a particle containing Mg.sub.3Si.sub.4O.sub.10(OH).sub.2, and (iv) a particle containing Al.sub.2Si.sub.2O.sub.5(OH).sub.4, a number average particle diameter Dc of a primary particle of the inorganic fine particle is 100 nm or more and 1000 nm or less, when a cross section of the toner particle is observed, an inorganic fine particle domain A having a dispersion diameter of 2.0 times or more of Dc is present in the cross section, and the inorganic fine particle and the inorganic fine particle domain A occupy a specific percentage of an area in the cross section of the toner particle.

A toner composition having improved toner usage efficiency, wherein toner particles having an average size range of 1-25 μm may be mixed with an extra particulate additive package including a first small silica surface treated with both a silane and an aminosilane having a primary particle size of about 5 nm-20 nm, a second fumed silica having a primary particle size of 30 nm-60 nm, a third silica having a primary particle size of about 70 nm-120 nm, an electro-conductive titania having a primary particle size of 30 nm-60 nm and an acicular titania having a size of about 1.6 μm to 1.7 μm in length and about 130 nm in diameter. An alternative embodiment of the extra particulate additive package does not include a third silica having a primary particle size of about 70 nm-120 nm.

An external additive for toner, wherein the external additive is an organosilicon polymer particle, and defining A (nm) as the number-average particle diameter of primary particles of the external additive measured using a scanning electron microscope, and defining B (nm) as the number-average particle diameter of the external additive measured in accordance with a centrifugal sedimentation method, the A and the B satisfy a following Expression (1):

1.5≤B/A≤3.0  (1).

A toner comprising a toner particle that contains a binder resin and fine particles A at the surface of the toner particle, wherein the fine particles A are organosilicon polymer fine particles, the organosilicon polymer fine particles have a number-average primary particle diameter of 30 nm to 500 nm, the organosilicon polymer fine particles have an attachment index for a polycarbonate film of not more than 3.5, the organosilicon polymer fine particles penetrate into the toner particle in a penetration depth b (nm), and protrude from the toner particle in a protrusion height c (nm), and b and c satisfy 0.05≤b/(b+c)≤0.40.

External additive particles including a polymer containing a sulfur atom and a nitrogen atom, wherein the polymer includes a vinyl polymer moiety and a siloxane moiety, relative to a total number of carbon atoms, oxygen atoms, and silicon atoms constituting the external additive particles, a ratio of a number of the silicon atoms constituting the external additive particles is 4.0% or more and 25.0% or less, and in surfaces of the external additive particles analyzed by X-ray photoelectron spectroscopy, relative to a total number of carbon atoms, nitrogen atoms, oxygen atoms, silicon atoms, and sulfur atoms, a ratio of a number of the nitrogen atoms is 0.40% or more and 2.50% or less, and a ratio of a number of the sulfur atoms is 0.05% or more and 0.25% or less.

The toner is a toner including a toner particle comprising a binder resin, a crystalline material, wherein, when a ratio of an area occupied by the crystalline material in a toner surface observed with a scanning electron microscope after ruthenium-staining the toner under a specific condition (1) is represented by S.sub.1 (%), a ratio of an area occupied by the crystalline material in the toner surface observed with the scanning electron microscope after ruthenium-staining the toner under a condition (2) is represented by S.sub.2 (%), and a dispersion diameter of a plurality of domains formed of the crystalline material on the toner surface observed with the scanning electron microscope after the ruthenium-staining the toner under the condition (2) is represented by R.sub.2 (nm), the following expressions (1), (2), and (3) are satisfied.

[00001]$\begin{array}{cc}0.0\le S_1\le 0.5& \left(1\right)\\ 1.0\le S_2\le 10.0& \left(2\right)\\ 20\le R_2\le 200& \left(3\right)\end{array}$