Toner, developer including the toner, image forming apparatus using the toner, and block copolymer

Abstract

The toner includes a pigment; and a block copolymer having a polyester block A including a residual group of a hydroxycarboxylic acid, and a polyester block B including an anionic group. When cross-section of the block copolymer is observed by a tapping mode atomic force microscope to obtain a phase image of the cross-section, the polyester block B, which has relatively large phase delay, is dispersed as domains having an average size of from 20 nm to 100 nm in a domain of the polyester block A, which has relatively small phase delay. The block copolymer has a first glass transition temperature of from −20° C. to 20° C., and a second glass transition temperature of from 35° C. to 65° C. when the first and second glass transition temperatures are determined from a thermogram obtained by subjecting the block copolymer to differential scanning calorimetry (DSC) at a temperature rising speed of 5° C./min.