Negatively chargeable magnetic pigmentary powder or toner

摘要

The following are claimed: (1) A magnetic pigmentary powder (I) comprising a resin binder and spherical magnetic particles (II) have a density after stacking of 1.2-2.5 g/c.c and linseed oil absorption of 5-30, pref. 10-25, esp. 12-18 ml/100g; (2) a one-component developer which is negatively chargeable, comprising (i) the above (I) also including a negative charge adjusting agent and (ii) a fine hydropholic silica powder, and (3) an image-formation process using the above developer