Effect of Basestock Roughness, Absorbency and Formation on Uncalendered Coated Paper Properties, 1994 Coating Conference Proceedings

T. Huang, P. LePoutre

The effect of roughness, absorbency and fiber mass distribution of the basestock on some uncalendered coated paper properties was investigated on model handsheets prepared in such a way that only one property was varied at a time. Coating was done on a CLC coater at 12.7 m/s. A rougher basestock resulted in a coated paper with higher roughness and lower gloss, but better coating uniformity. Surface compressibility appears to play an important role in controlling coat weight distribution. The effect of sheet absorbency on uncalendered coated properties is complex: Lowering absorbency by densification of the sheet (by beating and wet-pressing) improved coated gloss but did not significantly affect coated roughness. Lowering absorbency by complete hydrophobic sizing had no effect on the coated roughness and gloss of a very porous sheet but had a deleterious effect on a dense sheet: the coating dewetted and beaded up. Worsening the formation did not affect coated roughness and gloss much. It is believed that this is due to a compensating effect. This effect was clearly demonstrated in a model experiment which shows that a higher coat weight was deposited on areas of lower fiber mass. After printing, the area of higher coat weight had lower ink density.