| 摘要 |
PURPOSE:To enhance color tone of an image and stabilize it by oxidizing ferrite of a spinel structure of a specified compsn. to obtain a zinc-contg. spinel type magnetic oxide, adding a specified amt. of alpha-Fe2O3 to said oxide to form a magnetic powder, and forming a magnetic toner consisting of said magnetic powder and a binder resin. CONSTITUTION:The magnetic powder of a magnetic toner for developing an electrostatic latent image contg. said magnetic powder and a binder resin is obtained by adding up to 20wt% alpha-Fe2O3 to a zinc-contg. spinel type magentic oxide produced by oxidizing a spinel type ferrite composed of (ZnO)x(FeO)1-x Fe2O3 (x=0.1-0.9). This magnetic powder is contained in the toner by 20- 60wt%. This ferrite powder is oxidized at about 300 deg.C to give a gamma-ferrite type ferromagnetic powder, changed color from black to sepia, and become a reddish colored magnetic powder. Both of this tone and magnetic characteristics can be fully utilized for color electrophotography. The magnetite is heat oxidized to >=400 deg.C to give alpha-Fe2O3. This is lighter than gamma-Fe2O3 and more desirable, and a mixture of this sepia magnetic oxide and a small amt. of alpha-Fe2O3 can be used for color copying. |
