| 摘要 |
PROBLEM TO BE SOLVED: To control electric characteristics of a toner carrier without being affected by variance of ferrite lot by incorporating a specified amt. or more of SiO2 into a ferrite powder. SOLUTION: This carrier consists of a conductive base core bar 2 and a dielectric layer 3 formed around the core bar 2. The dielectric layer 3 consists of an org. polymer compd., a ferrite powder and an additive. The ferrite powder contains >=0.08wt.% SiO2 and has 1.0 to 1.5μm average particle size. The ferrite is compounded by >=70wt.% of a bond magnet material. If the proportion of SiO2 is <0.08wt.%, the ferrite powder shows about 0.3μm max. variance of the average particle size for production lots even when a same amt. of SiO2 is added. When the proportion of SiO2 is controlled to >=0.08wt.%, the average particle size of the ferrite can be controlled to 1.2 to 1.3μmrange and is stable without depending on the amt. of SiO2 . |
