| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a negatively chargeable toner superior in charging characteristics and black color reproducibility, by using a specified charge controller. SOLUTION: In the negatively chargeable toner formed by containing at least a binder resin and a carbon black, a charge controller is a boron- containing compound represented by the formula, in which each of R1 and R3 is an optionally substituted aryl group; each of R2 and R4 is H atom or an alkyl or optionally substituted aryl group; X is a cation; and (n) is 1 or 2. The melt viscosity curve of the toner is characterized by having an inflection point gentling in viscosity gradient in the temperature range of T1 +20 deg.C to T1 +40 deg.C measured by a flow tester, where T1 is a flow start point, and the like.</p> |
