| 摘要 |
PROBLEM TO BE SOLVED: To provide a negative friction electrification type magnetic toner less liable to generate a waste toner and having high transfer efficiency. SOLUTION: In the negative friction electrification type magnetic toner containing at least a binder resin, a magnetic material and a charge control agent, (a) the principal component of the binder resin contains a polyester unit synthesized with a tin compound of a 5-15C alkylcarboxylic acid as a catalyst, (b) an average particle diameter of the magnetic material is 0.1-0.3μm, (c) the charge control agent is an organometallic compound coordinating with or/and bonding to an aromatic oxycarboxylic acid or/and an organometallic compound comprising a complex of a benzilic acid derivative, and (d) a weight average particle diameter (X) of the toner is 5-12μm, and in particles of≥3μm in the toner,≥90% by number of particles having a circularity a of≥0.900 in a number-based circularity distribution of circularity (a) are present and an average circularity is≥0.940, wherein the circularity (a) is calculated by the expression: a=L<SB>0</SB>/L (where L<SB>0</SB>denotes the peripheral length of a circle having the same projected area as a particle image and L denotes the peripheral length of the particle image). COPYRIGHT: (C)2005,JPO&NCIPI |
