REDUCTION OF BACK-TRAP MOTTLE THROUGH OPTIMIZATION OF THE DRYING PROCESS FOR PAPER COATINGS - PART I

The drying of paper coatings can significantly affect the back-trap mo ttle of coated paper. This study identified an optimum drying strategy for a mill and the best latex binder to reduce back-trap mottle by pr eparing samples on a pilot coater under different drying conditions an d printing on a commercial six-color press. Computer modeling helped t o understand the critical drying process parameters and to translate t he pilot coater results to the drying process of the mill. Results sho ws the important variables influencing back-trap mottle. Back-trap mot tle is very sensitive to drying conditions near the first critical con centration drying zone. X-ray photoelectron spectroscopy data showed n o significant differences in the distribution of surface components be tween samples with good mottle and poor mottle. Drying conditions did not significantly affect coating properties other than back-trap mottl e.