| 摘要 |
<p>PURPOSE: To hold toner evenly on the surface and to provide a uniform high quality image by providing a multiple layer structure in which a magnetite layer is mounted on the outside of a hematite core. CONSTITUTION: A carrier for a developer is constructed of multiple layer structure grains, in each of which a core made of hematite is arranged in the center and the outside of the hematite core is covered by an outside layer made of magnetite. The multiple layer structure grain, in which a quantity of magnetite in the outside layer occupies 20-95% by weight in the whole of the grain and a grain diameter is 20-500μm, is formed into a sphere substantially. In practice, the grain of the multiple layer structure is coated with resin so as to be provided in a developer. To the hematite granulated powder, powder reducing agent made of solid carbon nature is uniformly mixed by a quantity of the powder reducing agent which is insufficient for reducing the whole of hematite in the granulated powder into magnetite, and then, this mixture is heated and held at a temperature of 950-1300 deg.C under a non-oxidizing environment or an inert, gas environment.</p> |
