Magnetic one-component toner and image forming apparatus using the same

A magnetic one-component toner used in an image forming apparatus including a developing device that uses magnetic one-component toner to develop an electrostatic latent image having been formed on an image carrier into a toner image, a transfer device that transfers the toner image having been developed by the developing device onto a recording medium, and a fixing device that includes a fixing belt formed as an endless belt and heated by a heating device, a nip forming member disposed radially inside the fixing belt so as to slide on an inner circumferential surface of the fixing belt, and a pressure member pressed with a predetermined pressure against the nip forming member with the fixing belt therebetween to form a fixing nip portion between the fixing belt and the pressure member, the fixing device fixing, onto the recording medium, the toner image having been transferred by the transfer device onto the recording medium,

• the magnetic one-component toner comprising toner particles each including:
• a toner base particle that contains at least a binder resin and a magnetic powder;
• and
• an external additive attached to a surface of the toner base particle,
• wherein
• the external additive includes:
• conductive particles with a specific resistance of 1.0E+4 [Ω·cm] or lower;
• resin particles with a number average primary particle size of 50 nm or more but 100 nm or less;
• and
• silica particles,
• the resin particles are formed by using an anion surfactant,
• the resin particles are formed from a vinyl resin having a repeating unit represented by general formula (1) below, a repeating unit represented by general formula (2) below, and a repeating unit derived from a sulfo group-containing vinyl compound, and
• a content ratio of the repeating unit derived from the sulfo group-containing vinyl compound in the vinyl resin is 2.0 mol % or more but 5.0 mol % or less relative to all repeating units in the vinyl resin:
• in formula (1), R11 and R12 each independently representing a hydrogen atom, a halogen atom, or an alkyl group optionally having a substituent, R13 representing an alkylene group having a hydroxyl group,
• in formula (2), R21 to R27 each independently representing a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group optionally having a substituent, an alkoxy group optionally having a substituent, an alkoxy alkyl group optionally having a substituent, or an aryl group optionally having a substituent.