| 摘要 |
PURPOSE:To prevent fading and to provide a magnetic developer capable of forming a uniform developed picture and especially appropriate for a magnetic ink symbol identifying system. CONSTITUTION:This magnetic developer contains a magnetic substance, and the residual magnetization sigma r of the magnetic substance is controlled to 12<=sigmar<=300emu/g in a magnetic field of 10,000 oersted. The coercive force Hc of the magnetic substance is adjusted to 130<=Hc<=300 oersted in a magnetic field of 10,000 oersted and the permeability mu to 2.0<=mu<=4.0. The magnetic substance has 1.2-2.5g/cm<3> packing apparent density and 5-30ml/100g linseed oil absorption, and the change coefficient of the magnetic substance calculated from sigma/x 100(%) sigma is the standard deviation of the grain size distribution of the magnetic substance, and (x) is the average grain diameter (mum) of the magnetic substance) is controlled to 2.0-50%. |
