| 摘要 |
PURPOSE:To obtain an image high in image density and excellent in thin line reproduction performance and gradation by using a vinyl polymer having a tetrahydrofuran-insoluble fraction in an amount of 5-80wt.% for the binder resin of a magnetic toner comprising the binder resin and a magnetic powder, and allowing the relationship between residual toner magnetization (sigmarho) and volume average particle diameter (d) to satisfy specified conditions. CONSTITUTION:The vinyl polymer having a tetrahydrofuran-insoluble fraction in an amount of 5-80wt.% is used for the binder resin of the magnetic toner comprising the binder and the magnetic powder. Said polymer has the relationship between the residual toner magnetization (sigmarho) and the average particle diameter (d) to satisfy the conditions of expression I, where (sigmarho) is the residual magnetization (emu/g) in case of the external magnetic field being 1kOe, and (d) is the volume average particle diameter (mum) and it is in the range of 3-18. The melt index is in the range of 0.2-12g/10min (125 deg.C, 10kg load), and the toner contains the vinyl polymer in an amount of 0.1-10wt.% in case of using polyalkylene having a molecular weight of 2,000-30,000 as the standard, thus permitting an image high in image density and excellent in thin line reproduction performance and gradation to be obtained. |
