Abstract: Generation of a drum filming layer is prevented by obtaining a developing agent meeting the relationship y<0.057x+0.1748, where x represents the total addition amount of the additive, which is not smaller than 0.2, and y represents the free component content obtained from the difference in the fluorescence X-ray analytical value between the front surface and the back surface of a pellet of the developing agent, by quantitatively analyzing the free component content of the additive to the developing agent and by using a binder resin satisfying the conditions of 2,000≦number average molecular weight≦5,000, 8,000≦weight average molecular weight≦70,000, and 1.6≦Mw/Mn≦35.

Abstract: Disclosed is a developing agent including toner particles containing a phosphorescent pigment and a binder resin, in the case of using the developing agent, printing capable of temporality storing light and emitting light even under a dark place can be easily formed by the electrophotographic system.

Abstract: Generation of a drum filming layer is prevented by obtaining a developing agent meeting the relationship y<0.057x+0.1748, where x represents the total addition amount of the additive, which is not smaller than 0.2, and y represents the free component content obtained from the difference in the fluorescence X-ray analytical value between the front surface and the back surface of a pellet of the developing agent, by quantitatively analyzing the free component content of the additive to the developing agent and by using a binder resin satisfying the conditions of 2,000≦number average molecular weight≦5,000, 8,000≦weight average molecular weight≦70,000, and 1.6≦Mw/Mn≦35.

Abstract: A developing agent comprising a toner particle containing a magnetic powder and a binder resin, the kinetic resistance of the developing agent being not higher than 200 M&OHgr;, and the absolute value of the difference &Dgr;V between the maximum value and the minimum value of the surface potential of the developing agent layer on a developing sleeve being not larger than 5V, is used for obtaining satisfactory developing agent image high in image density and low in fogging.

Abstract: Generation of a drum filming layer is prevented by obtaining a developing agent meeting the relationship y<0.057x+0.1748, where x represents the total addition amount of the additive, which is not smaller than 0.2, and y represents the free component content obtained from the difference in the fluorescence X-ray analytical value between the front surface and the back surface of a pellet of the developing agent, by quantitatively analyzing the free component content of the additive to the developing agent and by using a binder resin satisfying the conditions of 2,000≦number average molecular weight≦5,000, 8,000≦weight average molecular weight≦70,000, and 1.6≦Mw/Mn≦35.

Abstract: A wax dispersion in a developing agent using a polyester resin is improved by adding an ester wax in the polyester polymerizing step or both in the polymerizing and kneading steps, or by adding a compatibilizing agent selected from the group consisting of alkylene block copolymer or graft copolymer to a polyester-styrene hybrid resin used in place of the polyester resin.

Abstract: A toner comprises a first particle having a predetermined volume average diameter and including thermoplastic binding resin and a colorant mixed into the thermoplastic binding resin to apply a color thereto. Wax of a second particle whose volume average diameter is considerably smaller than that of the first particle, is attached to the first particle by mechanical pressure. A nonmagnetic particle of a third particle is attached to the wax. The volume average diameter of the third particle is considerably smaller than that of the second particle. The attachment of the nonmagnetic particle decreases the area of an exposed surface of the wax, thereby preventing the wax from being attached to other wax and preventing the wax from contacting another toner.