ETHANOL-KRAFT PULPING AND PAPERMAKING PROPERTIES OF ASPEN AND SPRUCE

A study was undertaken to investigate the effect of ethanol addition t o the kraft cooking liquor on the delignification of aspen and spruce wood chips and papermaking properties of the resulting pulps. Ethanol addition to the kraft pulping process had a significant impact on deli gnification and the resultant carbohydrate yields for both wood specie s. Maximum delignification selectivity was observed at the 0.1 and 0.3 ethanol mole fraction level for aspen and spruce, respectively. Remar kably faster delignification and about 30-50% lower residual lignin co ntent of pulps was found in the solvent-kraft pulping process compared to the kraft process. A 4% gain in pulp yield and a 30% reduction in pulping time were achieved using the solvent-kraft pulping process. An increase in fiber shortening occurred during beating in solvent-kraft pulps, whereas no significant differences in beatability and water re tention values were observed between the kraft and solvent-kraft pulps for both species. Solvent-kraft pulp handsheets exhibited higher bulk and comparable strength properties compared to the kraft samples, wit h the possible exception of tear.