| 摘要 |
PURPOSE:To obtain a carrier free from edges on black solid parts, and superior in halftone reproducibility and resolution of a formed image without using an expensive material, such as nickel by controlling a content of metallic iron into a specified range smaller than that of the conventional iron powder carrier, and its saturation magnetization into a specified range. CONSTITUTION:An iron powder carrier contg. 70-90wt% metallic iron and having saturation magnetization as low as 130-160emu/g is obtained by treating an iron type carrier contg. 94-97wt% metallic iron in CO2 atmosphere at 300- 700 deg.C for 30min-3hr and reacting it with nascent oxygen. As one of alternative methods, an iron powder contg. 30-90wt% metallic iron and having 90-160 emu/g saturation magnetization is obtained by treating reduced iron powder in the air at about 1,600 deg.C heated by combustion of O2-LPG to rounding the surface, and throwing it into water, or doing likewise. The use of such a carrier permits formation of a high quality image free from brush traces and deformed fine lines of an image by using a magnetic brush. |
