| 摘要 |
PURPOSE:To provide the positive chargeable toner which is free from color tone faults, has bright chromatic colors, is not affected by a change in temp. and humidity and has stable image charactersitics by incorporating a charge control agent having a specific structure into a polyester resin of low acid value. CONSTITUTION:The positive chargeable toner contains the polyester resin of 70 to 150 deg.C softening point synthesized of diol and polyhydric carboxylic acid, imidazoles expressed by following general formula (I) and a coloring agent. The acid value of the polyester resin is required to be confined to <=5KOHmg/g in this case. The negative chargeability of the resin itself increases and the application to a toner having positive chargeability is difficult if the acid value exceeds 5KOHmg/g. Such value is, therefore, undesirable. The metal complex of the imidazoles is stable with heat and time, has smaller hygroscopicity and is the good-quality charge control agent which yields the developer having excellent electrophotographic characteristics when incorporated into the developer. The imidazoles have colorless appearance and are applicable even to color toners wihout having the color tone faults thereon. |
