| 摘要 |
PROBLEM TO BE SOLVED: To obtain a desensitizing ink having a color-developing time extended by the irradiation with ultraviolet rays by compounding (A) a compound which develops color by ultraviolet rays and loses its color with time with (B) a specified amount of a white pigment selected from among lithopone, zinc sulfide, and barium sulfate. SOLUTION: A selected white pigment in an amount of 1-100 wt.% is compounded. A so-called photochromic colorant is used as the compound which develops color by ultraviolet rays and loses its color with time. A colorant having a color-developing time of 1-60 min is preferable. The compound which develops color by ultraviolet rays and loses its color with time is added usually in an amount of 0.10-20 wt.% of the ink. The white pigment is added usually in an amount of 1-50 wt.% of the solid content of the ink. When a desensitizer is used, it is added in an amount of 10-50 wt.% of the ink. When a desensitizer is not used and a physical screening layer comprising a resin film is formed, an ultraviolet-curable resin is used as a binder. |
