| abstract |
A dry powder toner of which the particles are electrostatically or magnetically attractable and suited for development of electrostatic charge images or magnetic patterns and wherein the composition of said powder particles includes a resin binder comprising at least one resin A and at least one resin B, characterized in that :n (1) said resin(s) A and said resin(s) B each have a glass transition temperature (Tg) larger than 45 °C, (2) the Tg of said resin(s) A is at least 2.5 °C lower than the Tg of said resin(s) B, (3) the melt viscosity (mvA) of said resin(s) A is at least 500 poise and the melt viscosity (mvB) of said resin(s) B is within the scope of the following equation : n n (mvB) = F x (mvA), n n wherein F is an integer from 2 to 20, and with a maximum value of (mvB) not exceeding 15000 poise, and (4) the weight ratio of resin(s) A and resin(s) B in said powder particles is such that the deformability of the powder material as defined by test H herein is smaller than 15 %. |