| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a novel toner for reversal development which gives an image having enough image density and little fog and causes no problem even when lots of sheets are printed by incorporating a binder resin, coloring agent and specified plural chromium-contg. dyes and using the chromium contg. dyes in a specified weight ratio and specified relation of the average particle size. SOLUTION: This toner contains at least a binder resin, coloring agent, chromium-contg. dye (A) expressed by formula I and chromium-contg. dye (B) expressed by formula II. The amts. of the chromium-contg. dye (A) and the chromium-contg. dye (B) are controlled to 50:50 to 95:5 weight ratio, and the average particle size of these dyes satisfies the relation of (average particle size of the dye (A))<(average particle size of the dye (B))<=4μm. Thereby, in a system using reversal development which can not give a high developing potential to a photoreceptor, the triboelectric charges of the toner are stable and enough image density can be obtd. even for lots of sheets are printed. Therefore, long-term printing is possible while fog in the base or fog on the photoreceptor is controlled to a range without problems for practical use.</p> |
