Gas stream classifier, gas stream classifying method, toner production process and apparatus

摘要

A gas stream classifier (1) includes: a gas stream classifying means for classifying feed powder into at least a coarse powder fraction and a fine powder fraction by an inertia force acting on particles and a centrifugal force acting on a curved gas stream due to Coanda effect in a classifying chamber (40), and a feed supply pipe (116) opening into the classifying chamber (40) for supplying the feed powder into the classifying chamber (40). The efficiency of the classifier (1) is improved by providing the feed supply pipe (116) with a mixing zone (X,Y,Z) for mixing an upper stream (A) and a lower stream (B) of the feed powder and an accompanying gas stream, respectively flowing through within the feed supply pipe (116). The classifier (1) is particularly suitably used for producing a toner for developing electrostatic images having a sharp particle size distribution from toner particles having a weight-average particle size of at most 10 µm, especially at most 8 µm.