To provide a method and a device for image formation which solve problems of transfer absence, a dust image due to toner, etc., caused during contact transfer by a full-color image formation system using an intermediate transfer system and obtain well-color-balanced high picture quality, and to provide stable images not only in the beginning, but also thereafter.
For color development, (a) the toner contains three kinds of additives, i.e., (1) silica of 0.01 to 0.03 μm in primary particle size after hydrophobic processing, (2) titanium oxide of 0.01 to 0.03 μm in primary particle size and 60 to 140 m2/g in specific surface area after hydrophobic processing, and (3) of 30 to 150 m2/g in specific surface area and 100 to 250 g/l in bulk density after hydrophobic processing. (b) When toner in early processing order of cyan and magenta is denoted as A and toner in later processing order is denoted as B, the additive (1) is added to A more than to B, (c) the absolute value QA/m of the toner electrostatic charging quantity at this time is larger than QB/m, and (d) secondary transfer is carried out while a transfer device applied with a transfer bias is made to abut to ≥3 g/cm.
FUSHIMI HIROYUKI
YAGI SHINICHIRO
MINAMITANI TOSHIKI
