| 摘要 |
PURPOSE:To obtain a magnetic toner used for pressing transfer having a deep black tone and denseness, and capable of forming an image high in Dmax by heat treating a magnetic toner having the difference between the softening point and the softening start point, at a specified value or more. CONSTITUTION:A magnetic toner powder having >=5 deg.C difference between the softening point and the softening start point is prepared by heat kneading (A) 10-80wt% magnetic powder having >=4ml/100g oil absorptivity, (B) 30-65wt% binder black resin, such as polyester resin, (C) 1-30wt% conductive substance, such as carbon having >= about 15ml/100g oil absorptivity, and (D) 0.2-20wt% other additives, such as colorant and fluidity improver, in a kneader or the like, cooling, and pulverizing the mixture. Next, this powder is treated in hot air stream at about 400 deg.C and granulated into each spherical form to obtain a magnetic toner used for pressing transfer. |
