| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a dry toner which is excellent in powder fluidity and transferability and also, excellent in any of heat-resistingly perceivable properties, low-temp. fixation properties and hot offset resistance by specifying the Wadell's practical sphericity of particles of the toner and using as the toner binder, a binder resin consisting of a polyester modified with urethane bonds. SOLUTION: In this dry toner consisting of a toner binder and a colorant, the Wadell's practical sphericity of the toner particles is 0.90 to 1.00 and the toner binder consists of a polyester modified with urethane bonds. Further, the Wadell's practical sphericity of the toner particles is preferably 0.95 to 1.00 and more desirably 0.98 to 1.00, wherein the Wadell's practical sphericity of each of all the toner particles is not required to fall within any of these ranges and such toner particles having average Wadell's practical sphericity within any of these ranges can satisfactorily be used. Also, the median value of particle diameters of the toner particles is ordinarily 2 to 20μm and preferably 3 to 10μm. As the polyester modified with urethane bonds, e.g. a reactant of a polyisocyanate with a polyester which is a polycondenstate formed from a polyol and a polycarboxylic acid and has hydroxyl groups, is used.</p> |
