An image forming apparatus for developing an image with developer includes a development part, a transfer part, and a fuser the medium. The developer is configured with a plurality of particles, an average circularity degree of the developer is ranged within 0.955 to 0.970, and a peeling rate (%) of the external additive by a following equation is 30.6% or less,

peeling rate (%)=[1 −(X/Y)]×100 . . .   (1) wherein X is an amount (weight %) of the external additive included in the developer after ultrasonic waves are applied, and Y is an amount (weight %) of the external additive included in the developer before the ultrasonic waves are applied.

Electrophotographic printing techniques offer excellent image quality, but image adhesion to a desired substrate may be problematic in many instances. Primer coatings for improving image adhesion to a substrate may be formed from primer compositions comprising a fluid and an amine-functionalized copolymer dispersed in the fluid as an emulsion, in which the amine-functionalized copolymer has an amine number of about 10 to about 180 mg KOH/g copolymer. The fluid may be aqueous or organic. Suitable amine-functionalized copolymers may be formed by an emulsion polymerization reaction of one or more first ethylenically unsaturated monomers lacking an amine group and one or more second ethylenically unsaturated monomers bearing at least one amine group. The at least one amine group comprises a side chain of the amine-functionalized copolymer.

A method for producing a composite resin particle dispersion includes: performing polymerization A by polymerizing a styrene compound and a vinyl monomer other than the styrene compound to form a styrene-based resin; performing polymerization B by polymerizing a (meth)acrylic acid ester compound in the presence of the styrene-based resin to form intermediate resin particles containing the styrene-based resin and a (meth)acrylic acid ester-based resin; and performing polymerization C by polymerizing a styrene compound and a vinyl monomer other than the styrene compound in the presence of the intermediate resin particles to form composite resin particles. The mass ratio of the styrene-based resin to the (meth)acrylic acid ester-based resin in the composite resin particles is from 80:20 to 20:80. A difference between the lowest glass transition temperature and the highest glass transition temperature in the composite resin particles is 30° C. or more.

A pressure sensitive adhesive includes: composite resin particles that contain a styrene resin containing, as polymerization components, styrene and a vinyl monomer other than styrene, and a (meth)acrylate resin containing, as a polymerization component, a (meth)acrylate; and an aqueous solvent containing water, in which a mass ratio of the styrene resin to the (meth)acrylate resin (styrene resin:(meth)acrylate resin) is 80:20 to 20:80, a difference between the lowest glass transition temperature and the highest glass transition temperature of the composite resin particles is 30° C. or more, a melt viscosity of the composite resin particles at 100° C. is 4000 Pa.Math.s or more and 20000 Pa.Math.s or less, and, in a melt viscosity range of the composite resin particles of 4000 Pa.Math.s or more and 20000 Pa.Math.s or less, a slope of a logarithm of the melt viscosity of the composite resin particles relative to a temperature of the composite resin particles is −0.08 or more and −0.04 or less.

A particle set for producing a printed matter includes: a chromatic color toner containing toner particles A; and pressure-responsive particles containing base particles B, in which the base particles B contain a styrene resin containing, as polymerization components, styrene and a vinyl monomer other than styrene, and a (meth)acrylate resin containing, as a polymerization component, a (meth)acrylate, a mass ratio of the styrene resin to the (meth)acrylate resin (styrene resin:(meth)acrylate resin) is 80:20 to 20:80, a difference between the lowest glass transition temperature and the highest glass transition temperature of the pressure-responsive particles is 30° C. or more, and when the toner particles A have a volume average particle diameter D50A and the base particles B have a volume average particle diameter D50B, the D50A and the D50B satisfy formula 1-1: 1.5 μm<(D50B−D50A).

A method for producing a resin particle dispersion includes: obtaining a phase-inverted emulsion by adding a neutralizer to a resin solution prepared by dissolving a resin having an acid value in an organic solvent to thereby neutralize the resin and then adding an aqueous medium to the resulting resin solution to subject the resin to phase inversion emulsification; and removing the organic solvent from the phase-inverted emulsion. In the course of obtaining the phase-inverted emulsion, a maximum agitation power per unit mass (kg) of the resin when the resin solution containing the aqueous medium added thereto is agitated to perform the phase inversion emulsification is from 0.4 W to 20 W inclusive.

A method for producing a toner for developing an electrostatic charge image includes: performing first aggregation that involves, in a dispersion containing first amorphous resin particles, aggregating at least the first amorphous resin particles; performing second aggregation that involves, in a dispersion that contains second amorphous resin particles and first aggregated particles obtained by aggregating the first amorphous resin particles, aggregating the second amorphous resin particles around the first aggregated particles; and heating a dispersion that contains second aggregated particles obtained by aggregating the second amorphous resin particles around the first aggregated particles so as to fuse and coalesce the second aggregated particles and form toner particles, in which a volume-average particle diameter DB of the second amorphous resin particles is smaller than a volume-average particle diameter DA of the first amorphous resin particles, and the first amorphous resin particles have a glass transition temperature of 50° C. or higher, and the second amorphous resin particles have a glass transition temperature of 50° C. or higher and 63° C. or lower.

An electrophotographic developer set comprising a toner comprising a thermoplastic resin and a wax, and a powder adhesive comprising a thermoplastic resin and a wax, wherein where Ea (mmol/g) denotes an ester group concentration of the wax contained in the toner, Na (mass %) denotes a content of the wax in the toner, Eb (mmol/g) denotes an ester group concentration of the wax contained in the powder adhesive, and Nb (mass %) denotes a content of the wax in the powder adhesive, the Ea, the Na, the Eb and the Nb satisfy the following formulae: 0.00≤Ea≤2.45, 2.50≤Eb≤3.60, and 0.80≤Nb/Na.

An electrostatic charge image developing toner includes toner particles containing a binder resin and a release agent and an external additive containing fatty acid metal salt particles and abrasive particles, wherein a ratio (B/A) of an isolation amount B of the abrasive particles isolated from the toner particles after an ultrasonic isolation treatment to an isolation amount A of the fatty acid metal salt particles isolated from the toner particles after the ultrasonic isolation treatment is from 0.3 to 2.0.

A toner including a toner particle including a binder resin, wherein fine particles A and B are present on a surface of the toner particle; the fine particles A are a fatty acid metal salt; the fine particles B have a specific volume resistivity; an average theoretical surface area of the toner particle, an amount of the fine particles A, and a coverage ratio of the toner particle surface by the fine particles A satisfy a specific relationship; the amount of the fine particles B is in a specific range; and a proportion F of an area occupied by a part of the fine particles B embedded in a surface vicinity region of the toner in a total area occupied by the fine particles B present in a cross section of one particle of the toner is 50% by area or more.