Updated: 2012-04-10 | Print
The market demand for higher brightness levels on wood-containing printing paper is steadily increasing. In order to be a supplier of the entire brightness span, there is a need to cost-effectively produce magazine papers at brightness levels well over 75 % ISO.
Incremental brightness gains are considerably more expensive at high brightness levels compared to earlier in the bleaching process. At high brightness levels, darkening reactions will take place at a faster rate compared to lower brightness levels.
It is generally observed that bleached mechanical pulp darkens with up to 5 brightness units (sometimes more) from the bleaching tower to the paper machine. This considerably increases the demands for high dosage of bleaching chemicals. If such darkening could be avoided or significantly reduced, bleaching costs and effluent loads would be considerably reduced something that would result in a cost-effective production and environmentally friendly production of high-bright magazine papers.
The Brightpaper project focuses on understanding the reasons for darkening, and on finding cost-effective solutions for avoiding this problem.
The project is partly funded by the Research Council of Norway, and is a cooperation between partners from industry, institutes and universities.
Contact Person: Ingvild Johnsen