| 摘要 |
PURPOSE:To obtain a developer not causing fogging due to filming when a developer for electrophotography contg. fine silicic acid powder is produced, by removing fine silicic acid powder not stuck to a toner. CONSTITUTION:A mixture of 100pts. styrene-2-ethylhexyl acrylate-divinylbenzene copolymer with 4pts. nigrosine and 50pts. magnetite having 8m<2>/g BET specific surface area is melted at 100 deg.C, mixed, cooled, crushed, pulverized and pneumatically classified to obtain black powder of about 11mum volume average particle size. The black powder is mixed with 0.5wt% fine silicic acid powder and the mixture is pneumatically classified to remove fine silicic acid powder not stuck to the black powder and to obtain a developer contg. 0.4wt% fine silicic acid powder. When the developer is used, a high density clear image is obtd. |
