| abstract |
A negatively charging toner for a two-component magnetic developing agent obtained by dispersing carbon black in a resin medium for fixing but without containing charge control agent, wherein the resin medium for fixing is a copolymerized resin or a resin composition having an anionic polar group and an acid value over a range of from 4 to 30, and the carbon black has a pH of smaller than 7 and a ratio (7-pH)/specific surface area (m2/g) of from 0.010 to 0.050. No negative charge control agent is blended, the toner maintains the electric charge in an amount large enough for developing, no charge control agent migrates onto the carrier surfaces, the charging property is not deteriorated by the spent toner but is stably maintained for extended periods of time, enabling the life of the toner and the carrier to be lengthened. |