Impact of High-Yield Pulp Substitution on the Brightness Stability of Uncoated Wood-Free Paper

Abstract

Without any fillers and optical brightening agents (OBAOBAOBAs), 15%–20% substitution of high-yield pulps (HYPs) for the hardwood bleached kraft pulp (BKP) in a paper furnish can decrease the brightness stability significantly because HYP contains a large amount of lignin. However, using mineral fillers such as precipitated calcium carbonate (PCC) and OBAOBAOBA in a HYP-containing paper can essentially eliminate the negative effect of HYP substitution on the brightness stability of uncoated wood-free paper. During the commercial production of traditional wood-free paper products, which usually use both PCC and OBAOBAOBA, 15%–20% HYP substitution for the hardwood BKP will not have practical impact on the paper brightness stability. Results from commercial printing and writing paper production support the same conclusion.