New Technique to Reduce the Printing Mottle - Smoothing of Starch Distribution, 1995 Coating Conference Proceedings

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T.Hirabayashi, H.suzuki, and T.Fukui
Osaka Product Development Laboratory
New Oji Paper Co., Ltd

T.Osada
Central Reserch Laboratory
New Oji Paper Co. ,Ltd

In this paper, the relationship between the distribution of starch in the coated layer both in the horizontal and depth directions and printing mottle is discussed. For the level of concentration of the starch in the coated layer in the depth direction, it is higher in the surface than the region from the middle to the bottom layer of the coated layer. Especially, when a strong drying operation is applied in the critical solid range of immobilization, localization and uneven horizontal distribution of starch occurs in the near-surface layer within 1 g/m 2 from the coated layer surface. thereby causing printing mottle. If the surface of the coated paper which has the uneven distribution of starch on its near-surface layer as above is treated with water or steam, the starch is redistributed. That is, starch-localized section and the uneven horizontal distribution of starch in the near-surface layer disappears, which solves the problem of printing- mottle generation.