| 摘要 |
PURPOSE:To obtain a fresh red colored magnetic toner and to obtain copied images having excellent contrast and halftones by sticking red tar dyes on the surface of gamma-Fe2O3 magnetic power having coercive force in a specific value range. CONSTITUTION:Red colored magnetic powder is obtained by such a method of subjecting gamma-Fe2O3 magnetic powder having 50-200 oersted coercive force and about 2-50m<2>/g specific surface area and tar type red dyes such as ''Rhodamine B '', ''Lake Red C '' or the like to a ball mill treatment for 5hr in water then drying the same. Such powder is kneaded together with a binder such as polystyrene resin and the mixture is ground, whereby a red granular magnetic toner of about 10-20mu particle size is obtained. By the use of such toner, fresh red colored pictures having excellent contrast and halftones are obtained with good resolution and reproducibility of fine images. |
