Papermaking for Waterbased Gravure Printability, 1995 Papermakers Conference Proceedings

Michael Busche Nick Triantafillopoulos John Serafano This work examined the influence of wet-end chemistry and internal paper sizing on the printability of waterbased publication gravure. Uncoated papers were produced on a pilot-plant Fourdrinier papermachine and printed on a 500-fpm rotogravure printing press. Waterbased printability was defined by tonal density, delta ink gloss, missing dots, and dot formation. The influence of wet-end chemistry environment (i.e., 100% bleached hardwood kraft papers made under acidic, neutral and alkaline conditions) on printability was evaluated with both an alkaline and acid waterbased inks. Alkaline papers printed with the alkaline ink gave the best wettability and printability, while the acid paper-acid ink system had poor wetting and printability. All papers however, had permanent (irreversible) fiber swelling during printing. In a second trial we utilized a furnish of 16% softwood kraft and 84% hardwood kraft. In this trial all papers were made under alkaline conditions and printed with alkaline waterbased gravure inks. Paper samples were slack-sized to hard-sized by increasing the concentration of AKD internal sizing. Delta ink gloss readings were used to quantify temporal fiber swelling (Z-direction) during printing and correlated with ink density measurements, under constant ink film thickness. With increased sizing under alkaline conditions, the fiber swelling appeared to be reversible (temporal). Going from an unsized to a paper sized at 268 HST seconds improves waterbased gravure printability by reducing the temporal fiber swelling and surface roughening, while increasing ink gloss up to 360%. Additionally, adding a small portion of softwood fibers to the furnish improved the effectiveness of AKD sizing by reducing fiber rising and significantly improved waterbased gravure printability.