| 摘要 |
<p>PURPOSE: To obtain a developer ensuring high image quality with high image density and low background fog and capable of preventing filming even in the case of use over a long period of time by using a carrier coated with fluororesin contg. specified electrically conductive fine powder and a toner contg. specified additives. CONSTITUTION: This developer consists of a carrier made of magnetic particles having 20-100μm average particle diameter surface-coated with fluororesin contg. electrically conductive fine powder and a toner consisting essentially of a bonding resin, an electric charge controlling agent, a colorant and additives. The electrically conductive fine powder is made chiefly of carbon black of >=pH7 having >=160ml/100g DPB oil absorption and 500-1,300m<2> /g BET specific surface area measured by nitrogen adsorption. The additives are at least inorg. fine particles synthesized by a hydrothermal method or an oxalate thermal decomposition method and having 0.05-4μm average particle diameter and 0.1-40m<2> /g BET specific surface area measured by nitrogen adsorption and hydrophobic fine silica powder surface-treated with silicone oil and having 50-350m<2> /g BET specific surface area measured by nitrogen adsorption.</p> |
