| 摘要 |
PURPOSE:To reduce and deposit a metallic silver film on the surface of a magnetic powder and to produce high quality white magnetic powder by forming silver ions in an aqueous solution of silver nitrate into complex ions by means of ammonia, dispersing a magnetic powder into the resulting silver solution, and then adding a reducing liquid to the resulting dispersed solution. CONSTITUTION:Ammonia is added to an aqueous solution of silver nitrate to form silver ions in this aqueous solution into complex ions. A magnetic powder is added and dispersed into the resulting silver solution. It is preferable to use a magnetic powder consisting of metallic iron, cobalt alloy, etc., and having about 0.05-20mum grain size as the above magnetic powder, and suitable additive quantity of this magnetic powder is about 5-500g for 100g of silver nitrate. Subsequently, a reducing liquid is added to the resulting dispersed solution and the above magnetic powder is used as a nucleus, and metallic silver film is reduced and deposited on respective surfaces of these nuclei. The above reducing liquid can be prepared by dissolving glucose, tartaric acid, and alcohol in water, and it is preferable to add this reducing liquid by a volume equal to that of the silver solution. By this method, the white magnetic powder suitable for magnetic color toner having bright color can be obtained. |
