Novel Bleaching of Thermomechanical Pulp for Improved Paper Properties, 2002 Fall Technical Conference

Production of mechanical pulp is expected to increase significantly to meet the growing global demand for paper. Mechanical pulping uses wood resources more efficiently with less negative impact on the environment than does chemical pulping. However, several problems related to mechanical pulping need to be resolved: high energy consumption, low paper strength properties, problems with pitch, and color reversion. Biopulping, an alternative pulping method, resolves the energy, strength, and pitch limitations but does not address brightness or color reversion. Optical properties can be improved and stabilized by incorporating calcium carbonate into pulp by fiber loading. The objective of this work was to investigate the technical feasibility of combining biopulping with fiber loading. We expected the combined technologies would save energy, improve paper properties, and reduce the production costs compared with current technology. This paper summarizes results obtained from a laboratory-scale handsheet investigation using a typical mill furnish for producing lightweight coated paper. Our results identified synergy between the complementary biopulping and fiber loading technologies enabling a substitution of up to 10% kraft with mechanical fiber without compromising paper properties. Simultaneous peroxide bleaching during fiber loading, an attractive alternative to a separate bleach stage, also was explored. These are the first results of combining these technologies.