Patent ID: 7939235

Claim:
An image formation method comprising: charging an image bearing member; irradiating a surface of the image bearing member to form a latent electrostatic image thereon; developing the latent electrostatic image with a two component developing agent comprising a carrier and a toner comprising a mother toner particle and an external additive by a development device comprising a rotating stirring and transfer device configured to transfer and stir the developing agent; transferring the developed image to a transfer medium; and fixing the developed image on the transfer medium, wherein the toner comprises a polyol-based resin as a binder resin, the polyol based resin having multiple hydroxyl groups in a molecular chain thereof in which a 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 a number of rotation per minute, β (mm) represents a pitch and γ (mm) represents a transfer path length of the stirring and transfer device, a 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 ≦−0.5 X +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.