Developer, image forming apparatus, and image forming method

Claim 1

A developer comprising a toner and a carrier, wherein the carrier includes a plurality of carrier particles, the carrier particles each include a carrier core and a carrier coating layer covering the carrier core, the carrier coating layer contains a fluorine-containing resin, the toner includes a plurality of toner particles, the toner particles each include a toner mother particle and a plurality of resin particles located on a surface of the toner mother particle, the resin particles have a number average primary particle diameter of at least 70 nm and no greater than 200 nm, a dispersion obtained by dispersing 0.1 g of the resin particles in 100 mL of distilled water has an electrical conductivity of at least 2.5 μS/m and no greater than 6.0 μS/m, and a degree of aggregation Y 160 of the resin particles represented by expression (1) shown below is at least 15% by mass and no greater than 40% by mass, Y 160 =100× M 160A /M 160B (1) in the expression (1), M 160B represents a mass of the resin particles to which a pressure of 0.1 kgf/mm 2 has been applied at a temperature of 160° C. for five minutes, and M 160A represents a mass of the resin particles that remain on a sieve having openings of 75 μm after being subjected to the application of the pressure of 0.1 kgf/mm 2 at the temperature of 160° C. for five minutes and then separated using the sieve.