| 摘要 |
PURPOSE:To obtain a developer which is stably electrostatically charged negative, decreass the change in the quantity of electrostatic charge even after long- period use or in spite of a change in the temp. and humidity of environment and is stable as a dry process carrier by dispersing magnetic powder which is coated with a carboxylic acid into a binder resin. CONSTITUTION:The magnetic powder is dipped in a soln. of the carboxylic acid which may be an aliphat. or arom. org. carboxylic acid and may be univalent or polyvalent and may be satd. or unsatd. and such soln. is spray-dried. The magnetic powder is otherwise coated with the carboxylic acid by a suitable method such as a method for dispersing the magnetic powder into a carboxylic acid-contg. monomer in the stage of polymerizing the binder resin. Such powder is dispersed into the resin and the dry process carrier is obtd. Such carrier and toner are mixed and the dry process carrier which has always the stable electrostatic charging characteristic, decreases the change in the quantity of electrostatic charge in spite of a change in the environment or even after continous copying of many sheets, obviates the sticking of the toner and carrier to the background part of the copy image and forms the image having the excellent resolving powder, gradation characteristic, etc. is thus obtd. |
