| 摘要 |
<p>PROBLEM TO BE SOLVED: To give positive electrification characteristics with good electrification rising characteristics and excellent durability and environmental stability and to maintain good identifying and reading performance of magnetic ink characters for a long time by mixing a wet silica and a dry silica each subjected to specified surface treatment and externally adding the mixture. SOLUTION: As for an inorg. powder, a silica fine powder having positive electrification polar groups and hydrophobic groups on the particle surface which is produced by a drying method, and the silica fine powder having amphoteric groups of positive electrification polar groups and fluorine-contg. negative electrification groups on the particle surface which is produced by a wet method are used and externally added to a toner. Thus, environmental changes in the electrification rising characteristics and toner fluidity can be prevented by the dry silica having positive electrification groups and hydrophobic groups on the particle surface, while excellent stability of electrification with time can be obtd. by the wet silica having amphoteric groups of positive electrification polar groups and fluorine-contg. negative electrification groups on the particle surface. Therefore, the life of the positive electrification toner can be significantly increased.</p> |
