Study on the performance of a dye-clay hybrid nanopigment in water-based flexographic ink formulation

Unlike solvent-based flexographic inks, the wastewater of the water-based flexographic ink is not reusable. Therefore, the disposal of water-based flexographic waste involves environmental hazards due to the presence of dyes in its formulation. However, the cationic dyes which are commonly used in these inks are believed to be suitable candidates for the synthesis of dye-clay hybrid nanopigments which can be reused in the flexographic ink formulation. In this paper, the performance of a malachite green-montmorillonite pigment in the formulation of a flexographic ink (P-ink) in comparison with dye-including ink (D-ink) was studied. The study of the inks' optical density (OD) showed a significant enhancement in OD performance of the hybrid nanopigment in comparison with that of the dye. The analysis of the reflectance spectrum of the P-Ink and D-Ink revealed a minor ۲.۰۸ nm hypsochromic shift in P-Ink due to dye-clay interaction. Comparison of the colorimetric parameters of P-Ink and D-Ink in CIEL*a*b* color space showed no significant chromaticity and hue difference. A ۵.۷۴-point color difference (∆𝐸𝒂𝒃) and a ۵.۲۹-point decrease in lightness (∆𝑳∗𝒂𝒃) were observed. The study of the rheological behavior of the pigments suggested no significant change in the sheer-thinning behavior of the inks, but the presence of single clay sheets could be comprehended from the high viscosity of P-Ink in low shear rates. The study of the UV-stability of the inks suggested a ۲۳.۵% enhancement in the UV-stability of the P-Ink in comparison with that of the D-Ink.

کلیدواژه ها:

Flexography ، Ink ، Dye-clay hybrid nanopigment ، Recycle