On the surface of a toner particle, a cohesion cluster containing a silica fine particle and a binding component is present. When a ratio by number of toner particles each having the cohesion cluster is denoted by CI (percent by number), the CI is 1 percent by number or more and 15 percent by number or less. When a ratio by number of toner particles each having the cohesion cluster in a toner subjected to processing under a weak ultrasound condition A is denoted by Ca (percent by number) and a ratio by number of toner particles each having the cohesion cluster in a toner subjected to processing under a strong ultrasound condition B is denoted by Cb (percent by number), the CI, the Ca, and the Cb satisfy formulae (1) and (2):

[00001]$\begin{array}{cc}0.9\mathrm{Ca}/\mathrm{CI}1.,\mathrm{and}& \left(1\right)\end{array}$$\begin{array}{cc}0.05\mathrm{Cb}/\mathrm{CI}0\text{.25}.& \left(2\right)\end{array}$

A toner includes toner particles. A cohesion cluster containing fine silica particles and a binder component is present on surfaces of the toner particles. The toner includes fatty acid metal salt particles. An arithmetic mean value of a Feret diameter of the cohesion cluster is 1,000 to 8,000 nm. A number percentage CI of toner particles having the cohesion cluster is 1 to 15 number %. Number percentages of toner particles having the cohesion cluster in the toner after treatment under ultrasonic wave conditions A and B are represented by Ca and Cb, respectively. CI, Ca, and Cb satisfy formulae (1) and (2): ultrasonic wave condition A: output frequency 30 kHz, output capacity 0.75 W, irradiation time 300 s, ultrasonic wave condition B: output frequency 30 kHz, output capacity 25 W, irradiation time 300 s

[00001]$\begin{array}{cc}0.9\mathrm{Ca}/\mathrm{CI}1.& \mathrm{Formula}\left(1\right)\end{array}$$\begin{array}{cc}0.1\mathrm{Cb}/\mathrm{CI}0\text{.40}.& \mathrm{Formula}\left(2\right)\end{array}$

An electrostatic charge image developing toner includes a toner particle that contains a silicon phthalocyanine dye and a zirconium oxide particle.

A toner, comprising a toner particle comprising a binder resin and a water-soluble polyvalent metal salt, wherein a main component of the binder resin is a polyester resin having specific acid value, the water-soluble polyvalent metal salt is a chloride, nitrate or sulfate of the specific metal, the water-soluble polyvalent metal salt has a solubility in water at 25 C. of 30 to 200 g/100 mL, in a cross-sectional observation of the toner particle, a proportion of the area of domains having a concrete surface area, relative to the total area of domains derived from the water-soluble polyvalent metal salt, is 80 to 100 area %, the expression below is satisfied, where At (area %) denotes the proportion of the total area of domains and Fm (atomic %) denotes the proportion of the polyvalent metal atom relative to the atoms in the toner as detected by X-ray fluorescence analysis.
0.02At/Fm0.10

The toner contains a toner particle having a core-shell structure including: a core containing a binder resin and a colorant; and a shell, wherein the toner contains a crystalline material, and the shell contains an amorphous thermoplastic resin; and when SP values of the crystalline material and the amorphous thermoplastic resin, which are calculated by the Fedors method, are defined as SPc (J/cm.sup.3).sup.0.5 and SPa (J/cm.sup.3).sup.0.5, respectively, the SPc and the SPa (J/cm.sup.3) satisfy a particular relationship, and when the toner is observed by SEM after the toner has been subjected to ruthenium staining that treats the toner in an atmosphere of RuO.sub.4 gas having 500 Pa for 15 minutes, a ratio S2 (%) of an area occupied by the crystalline material per area of the toner satisfies a particular relationship.

The toner contains a toner particle having a core-shell structure including: a core containing a binder resin and a colorant; and a shell, wherein the toner contains a crystalline material, and the shell contains an amorphous thermoplastic resin; and when SP values of the crystalline material and the amorphous thermoplastic resin, which are calculated by the Fedors method, are defined as SPc (J/cm.sup.3).sup.0.5 and SPa (J/cm.sup.3).sup.0.5, respectively, the SPc and the SPa (J/cm.sup.3) satisfy a particular relationship, and when the toner is observed by SEM after the toner has been subjected to ruthenium staining that treats the toner in an atmosphere of RuO.sub.4 gas having 500 Pa for 15 minutes, a ratio S2 (%) of an area occupied by the crystalline material per area of the toner satisfies a particular relationship.

A toner includes a toner particle containing a binder resin, and an organic-inorganic composite fine particle. The binder resin contains 50% by mass or greater of polyester A, U.sub.iso/all acid components100 indicating a content proportion of a unit U.sub.iso derived from isophthalic acid in the polyester A is 60% by mole or greater with respect to an amount of all units derived from the acid components. The organic-inorganic composite fine particle has, on a surface of a resin particle, a plurality of protrusions derived from an inorganic fine particle. The inorganic fine particle includes a silica fine particle, and the resin particle contains an ester group.

A toner comprising a toner particle, wherein the toner particle comprises a binder resin, a resin A, and a resin B, the resin A comprises a substituted or unsubstituted silyl group in a molecule, a substituent of the substituted silyl group is at least one selected from the group consisting of an alkyl group having 1 or more carbon atoms, an alkoxy group having 1 or more carbon atoms, a hydroxy group, a halogen atom, and an aryl group having 6 or more carbon atoms, and the resin B comprises an azo group in a molecule.

A method for producing pressure-responsive particles includes: adding an aggregating agent and a dispersion containing silica particles to a dispersion containing composite resin particles containing a styrene-based resin including a styrene compound and a vinyl monomer other than the styrene compound as polymer components and a (meth)acrylic acid ester-based resin including a (meth)acrylic acid ester compound as a polymer component to cause aggregation so as to form aggregated particles; and heating and fusing the aggregated particles to form pressure-responsive particles. The amount of the silica particles added by the dispersion containing the silica particles is 0.5 mass % or more and 10 mass % or less relative to a total mass of the composite resin particles. The mass ratio of the styrene-based resin to the (meth)acrylic acid ester-based resin in the pressure-responsive particles is from 80:20 to 20:80. A difference between the lowest glass transition temperature and the highest glass transition temperature of resins contained in the pressure-responsive particles is 30 C. or more.

An external additive for toner comprising a particle of a silicon polymer having a siloxane bond and a SiOC bond, wherein in an FT-IR spectrum of the external additive obtained by an ATR method, a maximum peak is present in a range of from 1030 cm.sup.1 to 1070 cm.sup.1, where an average intensity in a range of from 1015 cm.sup.1 to 1025 cm.sup.1 of the spectrum is denoted by A and an average intensity in a range of from 1085 cm.sup.1 to 1095 cm.sup.1 is denoted by B, the A and the B satisfy a following formula (1): $\begin{array}{cc}0.55A/B1.5.& \left(1\right)\end{array}$