| 摘要 |
PURPOSE:To improve image density by incorporating a toner contg. a specified styrene-acrylate copolymer and a fine silica powder and a carrier coated with a specified perfluoroalkyl acrylate resin in a developer. CONSTITUTION:A polymer contg. a low mol.wt. fraction having a glass transition point Tg of >=50 deg.C, and a high mol.wt. fraction having a Tg of <=65 deg.C is obtained by copolymerizing a styrene type monomer with an acrylate type monomer, and a fine hydrophobic silica powder is mixed with this polymer to obtain a toner. The carrier is obtained by coating a core material, such as iron powder, with a polymer obtained by polymerizing a monomer represented by formula I or II in which R<1>, R<2> are each H or methyl; n, p are each 1-8; and q is 1-19. The developer is obtained by combining the toner with the carrier. The use of said copolymer resin and the resin derived from said monomer I or II permits image density to be enhanced, durability of the developer to be improved, production of spent toner to be prevented, and a positively electrifiable toner to be obtained. |
