The absorption mechanism of aqueous and solvent inks into synthetic nonwoven fabrics

Abstract

To obtain high quality printing result with aqueous inks, it is important to understand the mechanisms of ink absorption and setting on various substrates. The final position of ink pigments determines the ink density and the resolution of the printed product. Recently, it has become desirable to develop higher quality printing results on nonwoven fabrics and synthetic fiber sheets.Absorption rates of aqueous and solvent inks into nonwoven fabrics were characterized with a Bristow absorption wheel. Several nonwoven fabrics, made with polyvinyl alcohol fibers or polypropylene fibers, were tested with aqueous and solvent inks. A model based on Darcy's law was applied to predict the ink absorption rate into the nonwoven fabrics. The model links the void fraction, pore size, contact angle and the Darcy permeability coefficients to the absorption rate. The results showed a high correlation between the experimental data and the predicted results for most combinations of substrates and inks, but in a few cases, the absorption rates were different than expected.The micro-scale distribution of aqueous and solvent inks on the nonwoven fabrics was evaluated with a confocal laser scanning microscope (CLSM) in order to characterize the deposition uniformity of the nonwoven fabrics. A clear difference of micro-scale distributions between aqueous and solvent inks could be obtained by CLSM.