正帯電性電荷制御用外添剤の微量添加における有機系粉体粒子の衝突帯電の変化

抄録

Tribo-electrification between stainless-steel target and organic powder particles has been studied experimentally based on the current generated by the electrification of the organic powder particles. Experimental apparatus with a unit of coaxial dual tubes, where the initial charge is hardly generated before impacting on the target, has been utilized. Charge transfer by the particle impact is about several hundred times of the initial charge. Furthermore, this experimental system has an adequate repeatability for average charge transfer and standard deviation of instantaneous charge transfer. Depending on the surface of the stainless-steel target, transition of the charge transfer with operation time dramatically changes. For a virgin stainless target, the charge (negative) transfer decreases with time and then approaches to 0μC/g. On the other hand, for a target with a bonding agent on the surface, the charge transfer increases with time and approaches a constant value. For composite particles made by adding small amount of guest particles through mixing, the average charge transfer increases drastically. While composite particles coated by long time mixing shows smaller average charge transfer than those by simple mixing. The charge transfer increases in the 1.3-1.7 power of air velocity. Mass fraction of the guest particles before and after the impact is measured and it is found that the coefficient of variation for charge transfer relates to the separation of the guest particles from the host particles.