| 摘要 |
PURPOSE:To prevent deterioration of development characteristics due to fluctuation of copying circumstance and image unevenness by using a magnetic powder composed essentially of gamma-Fe2O3 for a toner and specifying the relationship between said content and the content of fine silica powder to be added to the toner. CONSTITUTION:A magnetic toner consists of at least a magnetic powder and a resin and a fine silica powder, and gamma-Fe2O3 is used as the main component of the magnetic powder and the following relationships are satisfied between the content Mc% of gamma-Fe2O3 and the content Sc% of the fine silica powder: Sc <=0.04Mc-0.2, Sc>=Mc-1.3, Sc>=0.05, Mc<=50. The use of the magnetic powder of such gamma-Fe2O3 enhances electric resistance of the toner, and does not deteriorate copy quality against fluctuation of the circumstance. The use of Mc<50, preferably Mc<44 can improve fixability and tone. The use of such Sc keeps the electrostatic charge of the fine silica powder proper, and contributes to elimination of image unevenness. As a result, a superior image can be obtained. |
