Patent ID: 6537716
Filing Date: 2003-03-25
Classification: G03G

Abstract:
A negatively chargeable toner for developing electrostatic images, comprising (i) a binder resin, (ii) a wax (iii) a negative charge controlling agent and (iv) a magnetic material or a colorant, wherein:(a) said binder resin contains as a primary component a polyester resin having a soft segment comprising an alkyl group having 5 to 30 carbon atoms or an alkenyl group having 5 to 30 carbon atoms, said polyester resin having the soft segment present in an amount not less than 50% by weight based on the weight of the binder resin; said binder resin comprising a mixture of a non-linear polyester resin having said soft segment and a linear polyester resin; said linear polyester resin having been obtained by polymerizing (i) a dicarboxylic acid and (ii) dihydric alcohols; (b) said negative charge controlling agent has a compound selected from the group consisting of an acetylacetone metal complex, an aromatic hydroxycarboxylic acid metal complex, an aromatic dicarboxylic acid metal complex, an aromatic hydroxycarboxylic acid metal salt, an aromatic monocarboxylic acid metal salt, an aromatic polycarboxylic acid metal salt, phenol derivative and urea compound; and (c) said wax is a Fischer-Tropsch wax which has, in its endothermic peaks at the time of temperature rise and exothermic peaks at the time of temperature drop in a DSC curve measured using a differential scanning calorimeter, (i) an endothermic onset temperature within the range from 50Â° C. to 110Â° C., (ii) at least one endothermic peak P1 within the range from 70Â° C. to 130Â° C. at the time of temperature rise, and (iii) a maximum exothermic peak at the time of temperature drop, within the range of Â±9Â° C. of the endothermic peak P1.