Measurement of the ink penetration into laboratory papers with wheat pulp and its influence on print quality

Awareness of environmental issues has led to the increase in use of recycled printing papers or to the introduction of new alternative sources of cellulose fibres instead of virgin wood fibres. As recovered wood fibres cannot provide the same quality level of paper products as virgin ones, alternative sources of virgin cellulose fibres need to be identified. Therefore, the laboratory printing papers were produced using a wheat pulp in varying weight proportions and mixing with pulp from recycled paper. The print quality depends on the characteristics of the printing substrate, wherein the ink penetration is one of the important parameter. This study investigated ink penetration into laboratory papers made of different contents of pulp and their correlation with prints quality. The solid areas were printed on laboratory printing papers with cyan, yellow and magenta UV ink jet inks under standardized printing conditions. At last, the ink penetration inside laboratory papers were analyzed based on two methods (microscopic and spectroscopic) and their effect on rub resistance and print quality was also observed. Analyzed print quality parameters (ink optical density, mottling, colorimetric values) indicated that wheat pulp in the laboratory papers provides equal print quality compared to laboratory papers made from recycled pulp. The highest degradation of print quality was observed on laboratory papers with 30% of wheat pulp printed with cyan ink, as a result of the greatest measured average ink penetration depth.