Improve Invisible Ink Production by the Europium Complexes

The invisible inks have many applications, including the use of banknote printing, code load, security documents and much of its application in the exchange of security information. Photoluminescence properties of lanthanide compounds that attracted the attention of many scholars in recent decades are one of the important factors in drying and fluidity of the ink. The solvent evaporation rate has a special importance in the formulation of resin systems. The solvent evaporation rate is often expressed in compare with a standard solvent evaporation rate, such as normal butylated acetate or ethyl ether. The mixing of some solvents may be used due to the formation of an azeotrope and the more rate of evaporation. In the formulation of the inks, the use of the weight ratio compared with the volume relationship has this advantage, which requires less mathematical calculations and operations, especially that this score is useful during the early stages of formulation. In this research, from 160 materials that were used, 11 items played a fundamental role, which were selected based on their formulation planned. The purpose of this research was to produce invisible ink.For this purpose, the relevant complexes were prepared, designed and the composition of the percentage of invisible ink was optimized. Eventually, obtainedresults were evaluated.