POSITIVELY CHARGED MAGNETIC TONER

摘要

PURPOSE:To obtain the positively charged magnetic toner having excellent electrostatic offset resistance by using a specific binder resin and making combination use of a specific charge control agent at a specific. sp. gr. CONSTITUTION:This toner consists essentially of a magnetic material and the binder resin having 1 to 20 acid value. The toner contains a quaternary ammonium salt and a fatty acid metal salt having 2.0 to 4.5pts.wt. metal content and 110 to 145 deg.C m. p. as the charge control agent. Respective charge control characteristics are so determined as to satisfy equation I in the triboelectric charge quantity to iron powder. In the equation I, Ta denotes the electrostatic charge quantity of the toner contg. only the quaternary ammonium salt; Tb denotes the electrostatic charge quantity of the toner contg. only the fatty acid metal salt; Tc denotes the electrostatic charge quantity of the toner into which both of the quaternary ammonium salt and the fatty acid metal salt are incorporated. The generation of the electrostatic offset is prevented in this way and the dispersion of the magnetic material and lubricant into the binder resin is improved. The toner having the excellent electrostatic chargeability and durability is thus obtd.