| 摘要 |
PURPOSE:To make the reading of information recording extremely difficult to prevent a leakage of secrets, by using colorless fluorescent pigments emitting light by irradiating with ultraviolet rays of two kinds of wavelength ranges. CONSTITUTION:The titled ink comprises a mixed composition consisting of a colorless fluorescent pigment emitting light by irradiating with ultraviolet rays with a wavelength of 200-300nm, a colorless fluorescent pigment emitting light by irradiating with ultraviolet rays with a wavelength of 301-450nm, oil and wax or a mixed composition prepared by further adding and mixing usual color pigment or an ethylene-vinyl acetate copolymer or both of them in the former composition. As the colorless fluorescent pigments, a material difficultly available in the industry are utilized and, as the pigment emitting light by irradiating with ultraviolet rays with a wavelength of 200-300nm, for example ZnSiO4/Mn or CaWO4 is used while, as the pigment emitting light by irradiating with ultraviolet rays with a wavelength 301-450nm, for example, ZnS/Cu is pref. used and they are used in almost equal amounts within a range of 20-50wt% in total. |
