Patent ID: 7172845

Claim:
A developing agent to perform black development, which is used in combination with a color developing agent containing toner particles having (i) a chromatic coloring material, (ii) a first binder resin containing a polyester resin having a first acidic value, (iii) wax having a softening point higher than a softening point of the first binder resin, and (iv) wax having a softening point lower than the softening point of the first binder resin, the developing agent to perform black development comprising; toner particles having a black coloring material, a second binder resin containing a polyester resin having a second acidic value higher than the first acidic value, wax having a softening point higher than a softening point of the second binder resin, and wax having a softening point lower than the softening point of the second binder resin.