| 摘要 |
PURPOSE:To form a toner image which is illegible under visible rays but is legible when needed by incorporating a resin for fixing, a fluorescent dye which forms color only under the UV rays, a coloring agent having electrostatic charge controllability, a white pigment and, if necessary, white conductive powder into a toner. CONSTITUTION:Resins which are usually used as a resin for toners are used as the resin for fixing. The fluorescent dye which has th property to strongly absorb UV rays is used. The coloring agent having the electrostatic charge controllability is added to the toner in order to form the toner image which has the same color as the color of a recording sheet and is illegible under visible light and to impart electric charge to the toner. The white pigment is added to the toner to improve the dispersibility of the fluorescent dye and the coloring agent and to stabilize the color of the toner image. The white conductive powder of tin oxide or yttrium-iron-garnet is added to the toner if the impartation of the electric charge necessary for development to the toner is not possible with the coloring agent alone. The toner image which is illegible under the visible light but is legible under the UV rays when needed is thereby obtd. |
