Uniformity of liquid absorption by coatings - Technique and impact of coating composition

Abstract

The interaction between a liquid and a paper surface is important for a number of paper treatment processes, where absorption is of special significance during printing. Many absorption measurement techniques use a large available volume of liquid to characterise absorption, when compared to the volume of the coating. The uniformity of the absorption is also seldom characterised. We have developed a new technique, which is presented in this article, to study the uniformity of absorption of a small amount of liquid. This technique is based on the short-time absorption (tenth of a second) of a coloured liquid, the blotting of excess liquid and a characterisation of the pattern of the stain. This method made it possible to detect differences among coating layers with different compositions. In many cases, the absorption non-uniformity could be linked to variations in the coating thickness and/or wettability. The thinner and thicker areas of the coating layers were interpreted as having different pore structures. Neither the coating thickness nor the wettability could provide a full explanation, which showed the need to develop a method to characterise absorption uniformity instead of only relying on measuring the total absorption potential.

Effects of green technology plasma pre-treatment on the wettability and ink adhesion of paper

“…as well as the liquid absorbency, wettability, contact angle and surface energy properties of the printing substrate (Aydemir et al, 2019(Aydemir et al, , 2021. The sett of the ink on the paper and the degree of absorption are extremely determining in the colour and drying process (Thorman et al, 2012). The horizontal and vertical movement of the liquid ink within the paper is theoretically a good example to the liquid flow in the porous platform (Aydemir et al, 2020).…”

Investigation of the Evolution of Hydrophobicity and Wettability of Paper in Multi-Color Printing Process

“…Substrates with different degrees of liquid absorption result in different ink color results. 11 The fiber structure, filler content and surface coating determine the absorption ability of paper substrates. Differences in coating formulations and filler contents, fiber and porous structure of papers cause differences in paper surfaces, in terms of resistance to liquids.…”