Become the magnetic iron oxide grain and the said grain as an entity the magnetic iron oxide grain powder and its manufacturing method for the magnetic toner and uses the said magnetic iron oxide grain powder the magnetic toner

摘要

PROBLEM TO BE SOLVED: To produce magnetic iron oxide powder not causing falling from toner particles and giving a toner forming a high resolution image because of satisfactory flowability when an electrostatic latent image is developed and to obtain a magnetic toner using the powder. SOLUTION: This magnetic iron oxide powder contains =60% magnetite particles having 0.05-0.50μm average particle diameter and contg. 0.9-6.5at.% silicon (expressed in terms of Si) based on the amt. of Fe as magnetic iron oxide particles having a granular shape with 2-30 round protrusions. When the magnetite particles are produced by allowing an aq. soln. of a ferrous salt to react with an aq. soln. of an alkali hydroxide and growing the resultant magnetite seed crystals, an aq. soln. of a water-soluble silicate is added in two or more stages during the reaction by 1.0-8.0at.% (expressed in terms of Si).