Abstract

High-brightness high-yield pulps (HYPs) can be produced based on conventional peroxide bleaching, but the strong alkaline conditions needed would lead to the significant loss of bulk, scattering coefficient, and pulp yield, among other drawbacks. Recently, the use of an optical brightening agent (OBA) in HYP and its production of HYP-containing fine papers have received much attention. In this study, two different ways of using OBA in peroxide bleaching of spruce thermomechanical pulp (TMP), adding OBA to the bleach liquor or adding OBA after peroxide bleaching, were compared. The results showed that the unique properties of spruce TMP can be maintained by adding OBA to the bleach liquor (peroxide/OBA bleaching process). In addition, in comparison with the process of adding OBA after peroxide bleaching, the process of adding OBA to bleach liquors can produce TMP with higher brightness and OBA brightening efficiency and lower chemical oxygen demand load and chemical cost.

Full Text
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