Effect of Fiber and Filler Wettability on Ink Jet Print Quality, 1995 Papermakers Conference Proceedings

Robert T. Hamilton Weyerhaeuser Company Both internal and external sizing are known to significantly affect the print quality of fine paper. Ink jet printing is particularly susceptible to the effects of sizing due to the mechanism of ink placement and spreading on the sheet. The level of internal sizing of sheets was monitored by measuring both single fiber contact angles against water and macroscopic sheet sizing tests (HST and Cobb). Single fiber wetting data were found to be simply related to the sizing level of ASA-treated sheets. These data were then compared to three standard measures of ink jet print quality: optical density, dot gain, and edge raggedness, and a composite of the three known as Print Quality Index. Results indicate that single fiber wetting data is directly related to print quality for non-surface sized sheets. In general, as fiber wettability decreased, print quality increased. The effect of filler presence and wettability on printing performance was substantial. Non-filled sheets typically resulted in the highest print quality. This was due to an overall lowering of sizing by the presence of filler, as well as a substantial increase in surface wetting heterogeneity. In general: a homogeneous surface with regard to wettability produced the best print quality. In contrast to prior information in the literature, ASA emulsion sizing was found to significantly change the surface chemistry of calcium carbonate filler particles. The properties of a fine paper base sheet should be carefully optimized with regard to print quality before the consideration of surface sizing is undertaken.