Multifunctional curcuminoid dye-based inks

In a new study, curcuminoids were used as dyes in screen printing inks in combination with commercial solvent-based and water-based binders.

The rhizomes of turmeric are dried and ground into a deep orange-yellow powder commonly used as a colouring and flavoring agent. Image source: stevepb - Pixabay (symbol image),

Curcuminoids are a group of naturally occurring polyphenolic compounds found in turmeric (Curcuma longa) that are widely employed as coloring agents in traditional medicine and the food industry. Moreover, they have been used as dyes in pH indicators, which are part of diagnostic intelligent packaging. Recently, there has seen a steady increase of the interest in the curcuminoids due to their fluorescent property. In a new study, a curcuminoid dye (CurD) containing a total curcuminoid content of 38.34 ± 0.66 % w/w was prepared by using a microwave-assisted extraction, and was used as a multifunctional dye with different commercial screen binders, including solvent-based ink (Si) and water-based ink (Wi). A solution of CurD (0.1 % w/v) exhibited a maximum fluorescence wavelength of 526 nm.

Anti-counterfeiting application

A solution of CurD (0.1 % w/v) exhibited a maximum fluorescence wavelength of 526 nm. Based on the print-quality test using a screen printing on clear polyvinyl chloride and paper, the viscosity and drying time of CurD-Si and CurD-Wi inks were not significantly different. The printed-inks had a yellow color under illuminant D50 and D65, and exhibited remarkable green fluorescence under UVA (365 nm). The total colour differences, which are not fluorescence intensities, of both inks were changed by increasing CurD concentrations. CurD-Wi containing 1 % w/w CurD could be printed as latent graphics on a paper label for use as an anti-counterfeiting application.

The study has been published in Progress in Organic Coatings, Volume 182, September 2023.

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