Use of fluorescent whitening agents against light- induced colour reversion of aspen BCTMP

摘要

In recent years, Bleached Chemi-thermo Mechanical Pulp (BCTMP), also known as High Yield Pulp (HYP) with its unique properties has found increasing applications in many value-added paper grades. However, one of the main drawbacks that limit its more extensive applications is the photo yellowing tendency due to its high lignin content. In this paper, fluorescent whitening agents (FWAs) were used as potential yellowing inhibitors for HYP, being either added at the wet-end or applied by a surface sizing technique. Results showed that a good yellowing-inhibiting effect can be achieved when the 2-sulfonic or 4-sulfonic type of FWA is used at the wet-end of the papermaking process, or the 4-sulfonic or 6-sulfonic type of FWA is applied by the surface sizing technique. It was found that the surface application is more cost-effective in improving the light stability of HYP than the wet-end application.