| 摘要 |
PURPOSE:To obtain a developer reproducing well a solid-color part and halftone and causing no deterioration in the quality of an image even after long-time use by covering a carrier with a substance having high resistance and adding a substance having a high dielectric constant to a toner. CONSTITUTION:When a dry two-component type developer is composed of a toner and a carrier, the carrier is covered with a substance having high resistance, and a substance having a high dielectric constant is added to the toner. Ceramics such as barium titanate is used as the substance having a high dielectric constant by 2-50pts.wt. of the total amount of the toner. The toner is obtd. by well mixing a resin component with a colorant for forming a visible image such as carbon black, kneading the mixture by means of a hot roll mill, and carrying out solidification by cooling, grinding and classification. A styrene- methacrylate copolymer, silicone resin or the like is dissolved in a solvent, and the surface of a core material of 20-1,000mum average particle size such as powder of Co, iron, steel, Ni, Zn, Al, brass of glass is coated with the prepd. soln. by spraying or other method to obtain the covered carrier. A solid-color part and halftone are well reproduced by using the resulting developer, and a copied image of high quality is formed. |
