The Development of Dye-based, Anti-counterfeit Printing Ink Detected by CO2
Keywords:carbon dioxide indicator, pH dye, meta-cresol purple, indicator ink, security ink
The objective of this research was to develop the anti-counterfeit printing Ink that could be detected by CO2. This ink was consisted of meta cresol purple sodium salt (MCP) as a dye, hydroxyethyl cellulose (HEC) as a blinder, deionized water (DI-water) as a solvent, and glycerol (G) and sodium hydrogen carbonate (NaHCO3) as additives. The concentration of MCP was studied at 3 different levels which were 6, 10, and 20 parts per hundred resin (phr). The results showed that the ink revealed the original purple-blue color at the highest maximum absorbance (Absmax) of 588 nm. The ink was then gradually changed to yellow color with the Absmax of 434 nm when it was exposed to 100% v/v CO2 (1 bar) continuously for at least 60 seconds (in the closed conditions). The ink color with the MCP/G/HEC ratio of 10/300/100 phr could be changed by CO2 within 30 seconds. In addition, when the ink was left in the laboratory conditions (O2 20.9% v/v and CO2 0.03% v/v), the yellow ink was continuously turned back to its original color, purple-blue, within 20 seconds. The ink could also be applied for CO2 detection. Moreover, some of the properties which were colors, viscosity, and surface morphology of the ink film thickness, as well as the future possible applications of this ink type were reported in the research.
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