NEGATIVELY CHARGEABLE TONER

摘要

PROBLEM TO BE SOLVED: To provide the negatively chargeable toner not attaching with melting to a layer-regulating member and a toner carrier even in the case of being used for a long time at a comparatively high speed and preventing occurrence of uneven striations of images and fog on a background by incorporating a polyester resin having an urethane cross-linking component and a specified compound. SOLUTION: The polyester resin to be used for the negatively chargeable toner having the urethane cross-linking component is obtained by cross-linking the polyester base resin with a diisocyanate to expand the resin and mixing the other polyester, when needed. The negatively chargeable toner contains this resin having cross-linking components and further, the boron compound represented by the formula in which each of R1 and R4 is an H atom or an alkyl or optionally substituted aromatic ring or condensed ring; each of R2 and R3 is an optionally substituted aromatic ring or condensed ting; Xn+ is a cation; and (n) is 1 or 2.