| 摘要 |
<p>PURPOSE:To obviate the adhesion of the carrier even in development of AC electric fields, to improve spenting resistance, resistance value and stability of electrostatic charge impartation to toners and to enable development faithful to an original. CONSTITUTION:The magnetic carrier formed by coating core material surfaces with a resin is the carrier having 5 to 100mum grain size, <=3.0g/cm<3> bulk density, 30 to 150emu/cm<3> sigma1000 of the magnetic characteristics of the carrier as shown in Fig., >=25emu/cm<3> sigmar and <300oersted coercive force and satisfying formula. The resin for coating the core material surfaces is (1) a copolymer having 1 to 100 hydroxyl value or (2) a copolymer which is composed of a styrene-acryl copolymer and has 30 to 90mass% monomer ratio of the acrylic component in the copolymer, 30000 to 70000 weight average mol. wt. of the copolymer and 2 to 10 weight average mol. wt./number average mol. wt.</p> |
