| 摘要 |
PURPOSE:To enable reduction of variance of concentration even under different environmental conditions by using a specified iron oxide for a fine magnetic powder. CONSTITUTION:The magnetic iron oxide to be used for the magnetic toner contains a silicon element in an amount of 0.1-1.5wt.% on the basis of the iron element. The content of silicon A in the magnetic iron oxide is <=about 0.7wt.%, when the iron element is dissolved in the magnetic iron oxide in an amount of <=about 10wt.%, and that B in the magnetic iron oxide is in the range of 0.2-5wt.%, when the iron element is dissolved in the magnetic iron oxide in an amount of 90-100wt.%, and a ratio of B/A is >=1, and if the ratio is below 1, the amount of silicate compound present in the nuclei of the magnetic iron oxide in the early stage of producing it is insufficiently, and it is difficult to produce the magnetic iron oxide uniform in particle diameters and sharp in particle diameter distribution. The apparent bulk density of the magnetic iron oxide is adjusted to 0.35-0.50g/cc by using a fret mill and the like, thus permitting the variance of concentration even under different environmental conditions to be reduced. |
