Fluorescent image-printed article and fluorescent ink

[0112] According to the following reaction formula (5), a rare earth complex was synthesized. Namely, as a ligand, two kinds of phosphine oxide, i.e. triphenyl phosphine oxide and trioctyl phosphine oxide are reacted with a rare earth metal compound to obtain a rare earth complex. This rare earth complex was then dissolved in Bartrel XF (fluorine-contained solvent; Du Pont Co., Ltd.) to obtain a solution. To this solution was further added 2% by weight of pellets of Dainion THV (one of fluorine-contained polymers represented by the following formula (6); Simitomo 3M Co., Ltd.) to obtain a solution (ink). The solution (ink) prepared in this manner was then coated on a glass substrate by means of spin-coating to form a layer, thereby obtaining a fluorescent image-printed article.

[0113] (wherein, q and r are respectively an integer; and Rf1 and Rf2 are individually a linear or branched alkyl group having not more than 20 carbon atoms and having in its molecule structure at least one flu

[0119] A rare earth complex was synthesized by following the same procedures as described in Example 1 except that diphosphine dioxide having a structure represented by the following formula (7) was substituted for the phosphine oxide employed as a ligand in the reaction formula (5). Then, by making use of this rare earth complex, an ink and a fluorescent image-printed article were manufactured in the same manner as described in Example 1.

[0120] In the same manner as in the case of Example 1, the emission and transparency of the image of this fluorescent image-printed article were measured. When black light and light from an LED having a central wavelength of 410 nm were irradiated to this fluorescent image-printed article, a strong red emission was recognized. This image could not be visually observed unless these lights were irradiated, thus obtaining a fluorescent image-printed article excellent in security.

[0121] A rare earth complex was synthesized by following the same procedures as described in Example 1 except that diphosphine dioxide having a structure represented by the following formula (8) was substituted for the phosphine oxide employed as a ligand in the reaction formula (5). Then, by making use of this rare earth complex, an ink and a fluorescent image-printed article were manufactured in the same manner as described in Example 1.

[0122] In the same manner as in the case of Example 1, the emission and transparency of the image of this fluorescent image-printed article were measured. When black light and light from an LED having a central wavelength of 410 nm were irradiated to this fluorescent image-printed article, a strong red emission was recognized. This image could not be visually observed unless these lights were irradiated, thus obtaining a fluorescent image-printed article excellent in security.