| abstract |
An image formation method including charging an image bearing member; irradiating the surface of the image bearing member to form a latent electrostatic image thereon; developing the latent electrostatic image with a two component developing agent including a carrier and a toner including a mother toner particle and an external additive by a development device including a stirring and transfer device for transferring and stirring the developing agent; transferring the developed image to a transfer medium; and fixing the developed image on the transfer medium, wherein the toner includes a polyol-based resin as a binder resin, the polyol based resin having multiple hydroxyl groups in a molecular chain thereof in which the ratio (EX/OH) of epoxy group (EX) to hydroxyl group (OH) is from 0.990 to 1.010, the stirring and transfer device satisfies the following relationship (I): 1.0×10 6 ≦α×β×γ≦16.0×10 6 , wherein α represents the number of rotation per minute, β (mm) represents the pitch and γ (mm) represents the transfer path length of the stirring and transfer device, the temperature Tin (° C.) in the development device during stirring and transfer of the two component developing agent satisfies the following relationship (II): 30° C.<Tin<60° C., and the toner satisfies the following relationships (III): Y≦−0.5X+45, 5≦X≦40, 5≦Y≦35, wherein X (%) represents a degree of agglomeration of the mother toner particle and Y (%) represents a degree of agglomeration of the toner which has been preserved at 55° C. for 24 hours. |