Magnetic toner with negative polarity for developing latent electrostatic images, and image forming apparatus using the same

Abstract

A magnetic toner with a negative polarity for developing latent electrostatic images is made of toner particles, each toner particle containing a binder resin, a magnetic powder, and a charge control agent, the surface of the magnetic toner satisfying the relationship of 2×10−7≦C/Sw≦10×10−7, provided C≦8×10−3, wherein C is an amount (g/g) of the charge control agent dissolved in a solvent comprising water and methanol, and Sw is a specific surface area (cm2/cm3) of the toner particles determined from a weight-average particle diameter of the toner particles. An image forming apparatus has an electrostatic image bearing member, and a unit for developing the electrostatic image with the above magnetic toner, the unit having a developer holding member provided with a magnet, and a developer container. A method for measuring the amount of a charge control agent extracted from the surface of magnetic toner particles employs an aqueous alcohol solvent of water and an alcohol.

Dependencies are inferred from the claim text.