Production technologies for microfibrillated cellulose

Abstract

Microfibrillated cellulose is a nanoscale material made from mechanically disintegrating cellulose. At the moment, the production of microfibrillated cellulose can be energy intensive and there is some difficulty to reach the required fibrillation degree. This work, therefore, aims to investigate the viability of a mechanical pre-treatment of pulp before microfibrillated cellulose production. The mechanical pre-treatment consists of a high consistency refining stage performed with either a single disk refiner or a double disk refiner. These different refiner configurations are used to simulate a lighter and harsher pre-treatment to see if any differences can be observed. The high consistency refining stages are performed in near industrial scale with a double disk refiner. Microfibrillated cellulose production is done in both laboratory and pilot scales. Laboratory production is performed with a Masuko supermasscolloider grinder and pilot scale production with a Valmet PRO conical refiner. The results from the trials show no large improvement of the high consistency refining stages for microfibrillated cellulose production. The only improvement observed in both laboratory and pilot scales is the increase in the number of long fibrils. In laboratory scale it is observed that the production of microfibrillated cellulose could possibly be stopped earlier for the high consistency refined pulps. Laboratory scale trials do, however, not translate completely to industrial scale so this might not be a possibility in real world conditions.