PURPOSE: To enable uniform positive charging extending for a long time without causing a toner to attach to developing members, such as toner thickness regulator, and to induce filming, etc. by incorporating a fatty acid ester or a partially saponified compd. of it in a specified percentage by weight in the toner.
CONSTITUTION: Magnetic toner particles are triboelectrified with a material fixed to a developing section to develop an electrostatic charge image, and they contain fatty acid ester or a partially saponified compd. of it in 0.01W10wt%. When it is less than 0.01wt%, its effect becomes deficient, and when it is more than 10wt%, the positive chargeability of the toner becomes too high, and it readily attaches to a sleeve, etc., resulting in lowering of fluidity and image density. As a toner resin, polystyrene, poly-p-chlorostyrene, polyvinyltoluene, or the like homopolymers of styrene and its substitutes are usable.
KAWABATA TOSHIYASU
TOSAKA HACHIROU
MURAYAMA HISAO