Improved brightness of wood-containing printing paper

The principle objective is to establish the knowledge basis needed to develop cost-effective processes for producing high-bright mechanical pulp. Bleaching efficiency shall be improved by reducing brightness losses during transport of pulp along the pulpi ng process to the paper machine. A successful project will open for: *20 % reduction in bleaching costs *Cost-effective production of value-added magazine paper grades at higher brightness levels (e.g SCA++, brightness > 75% ISO) increasing sales volume and profitability The main idea for improving bleaching efficiency is to reduce brightness losses during the production process. The main research challenges in the project are: * Map process streams and pulp optical properties along the fiberline of a selected case study mill * Explore causes for darkening of bleached mechanical pulp during the process: -Verify darkening reactions on a standardized bleached mechanical pulp in the laboratory, using mill process water and similar conditions as applied in the mill. -Using the method developed above, a standardized mechanical pulp will be exposed to modified process water, where single components may be added or removed. -Applying the method developed above, a standardized mechanical pulp will be exposed to model mill process water, containing single or multiple water components. -Effects of process conditions will be tested *Explore how process water chemistry and conditions can be modified to avoid darkening of mechanical pulp There will be a close int eraction between research scientists from PFI, Mid Sweden University (MiUN), NTNU and the industrial partners, so that scientific expertise can be fruitfully combined with industrial experience and know-how. A PhD-student will work within the project, sup ervised by Professor Per Engstrand at MiUN. The PhD-student will be part of the PhD-program of mechanical pulp at MiUN, and will be geographically positioned at a selected Norske Skog mill.