摘要:
An image forming method comprises the steps of feeding a magnetic toner onto a toner carrying member, wherein the magnetic toner comprises a binder resin and a magnetic powder with a volume average particle diameter ranging from 7 .mu.m to 10 .mu.m, and the magnetic toner particles have a quantity of triboelectric charge which satisfies the following expression:0.1.times.A+2.ltoreq.-Q.ltoreq.0.1.times.A+16.The magnetic toner is triboelectrically charged to impart a negative triboelectric charge to the magnetic toner. An electrostatic latent image is formed on a latent image carrying member by using the magnetic toner to form a toner image. Thereafter, the toner image is transferred to a transfer medium.
摘要:
A toner for developing electrostatic images, comprises a binder resin and a colorant, wherein the binder resin comprises a vinyl copolymer having an acid anhydride group, and the binder resin has a total acid value (A) of 2-100 mgKOH/g and a total acid value (B) attributable to acid anhydride group of below 6 mgKOH/g so that [(B)/(A)].times.100 is 60% or less. Because the binder resin has a specified acid value partly attributable to acid anhydride group, the toner is provided with an adequate balance between chargeability and dischargeability, so that the toner shows a stable performance under various environmental conditions. The toner is particularly advantageously constituted as a magnetic toner of fine particle sizes suitably used under application of unsymmetrical alternating bias electric field.
摘要:
An image forming apparatus is formed by providing a latent image-bearing member for holding an electrostatic image thereon and a toner-carrying member for carrying a prescribed magnetic toner comprising a binder resin and magnetic powder and having a particle size distribution including 12% by number or more of magnetic toner particles of 5 microns or smaller, 33% by number or less of magnetic toner particles of 8-12.7 microns and 2% by volume or less of magnetic toner parcitles of 16 microns or larger so as to provide a volume-average particle size of 4-10 microns. At the developing station, an alternating bias voltage comprising a DC voltage and an unsymmetrical AC voltage in superposition is applied between the toner-carrying member and the latent image-bearing member to provide an alternating bias electric field comprising a development-side voltage component and a reverse-development side voltage component. The development-side voltage component has a magnitude equal to or larger than that of the reverse development-side voltage component and a duration smaller than that of the reverse-development side voltage component, so that the magnetic toner on the toner-carrying member, particularly fine powdery fraction thereof effective for high-quality development, is effectively transferred to the latent image-bearing member to develop the electrostatic image thereon at the developing station.
摘要:
A toner for developing electrostatic images, comprises a binder resin and a colorant, wherein the binder resin comprises a vinyl copolymer having an acid anhydride group, and the binder resin has a total acid value (A) of 2-100 mgKOH/g and a total acid value (B) attributable to acid anhydride group of below 6 mgKOH/g so that [(B)/(A)].times.100 is 60% or less. Because the binder resin has a specified acid value partly attributable to acid anhydride group, the toner is provided with an adequate balance between chargeability and dischargeability, so that the toner shows a stable performance under various environmental conditions. The toner is particularly advantageously constituted as a magnetic toner of fine particle sizes suitably used under application of unsymmetrical alternating bias electric field.