Effect of Pulp Fines on the Dye−Fiber Interactions during the Color-Shading Process

Abstract

Fines play a very important role in the papermaking process and paper properties. High-yield pulp (HYP) contains a large amount of higher specific surface area fines, which may lead to the absorption of more dye at the wet end section. Better understanding of the dye−fines interaction will help improve the dye efficiency in HYP-containing furnish. This study was focused on the fines from high-yield pulp and hardwood bleached kraft pulp (HBKP) on optical properties, particularly on the CIE (Commission Internationale d’Eclairage) whiteness and b* (negative values indicate blue, and positive values indicate yellow). The characteristics of both HYP fines and HBKP fines were presented, and their effects on dyeing (color-shading) process were investigated. Fines have a higher specific surface area and more dissolved and colloidal substances (DCS) than do the fibers. It was found that for a system made of HYP fibers, HYP fines had a negative effect, while HBKP fines had a positive effect on the color shading pro...