STRESS LUMINESCENT MATERIAL-CONTAINING INK AND PRINTED MATTER OF THE SAME

摘要

PROBLEM TO BE SOLVED: To improve water resistance while maintaining stress luminescence of a stress luminescent material-containing ink and of a printed matter of the ink.SOLUTION: A printing ink comprises a stress luminescent material and a vehicle. The stress luminescent material is obtained through steps of: preparing a slurry by mixing a phosphoric acid compound and europium-activated strontium aluminate particles; pulverizing the slurry to obtain a pulverized slurry; and drying the pulverized slurry. A silk printing ink comprising 100 parts by weight of the stress luminescent material and 230 parts by weight of a vinyl-based silk printing medium having a solid content of 20 wt.% is applied on a PET film to perform solid printing by use of a silk printing plate to obtain a dry film thickness of 20 μm ; then four print pieces having a 20 mm×30 mm solid print portion are cut out from the obtained printed matter; and the four print pieces are immersed in 50 mL of deionized water at 40°C for 60 minutes. An absolute value in a PH change in the immersion liquid after immersion of the print pieces for 60 minutes compared to the deionized water just before the immersion is 2.0 or less.SELECTED DRAWING: Figure 1