| 摘要 |
PURPOSE:To provide a magnetic toner good in durability and capable of forming an image superior in thin line reproducibility and gradation by specifying sphericity, a size of needles, and a weight ratio of a spherical magnetic material to a needle one in the magnetic toner composed of the spherical and needle magnetic materials. CONSTITUTION:The magnetic toner is formed by incorporating the spherical magnetic material 2 having a sphericity of 1-1.2 and the needle magnetic material 1 having a longer axis to shorter axis ratio of 5:1-15:1, and a longer axis to the diameter of the material 2 of <=5:1, in a weight ratio of the material 2 to the material 1 of 95/5-75/25, thus permitting dispersion of the magnetic materials to be improved and uniformized, and a distribution of an electric charge amount of the toner to be reduced in dispersion. On the other hand, if the sphericity of the material 2 is over 1.2, the dispersion of the material 2 is worsened, and image quality is deteriorated, and if the longer axis to shorter axis ratio of the material 1 is below 5, image quality varies under an environment of low humidity, and if over 15, image density deteriorates under an environment of high humidity, thus permitting a sharp obtained under high humidity and durability under low humidity to be enhanced. |
