De-esterification and Sulphonation in CTMP: Effects on Pulp and Paper Properties, 2007 International Mechanical Pulping Conference

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Various tree species and chemicals are today used in chemimechanical pulping. Most CTMP grades are targeted for high bulk and, thus, the use of alkali is minimized. The chemical dosage is, therefore, in most CTMP processes, below that needed for complete deesterification of methylated and acetylated compounds. Chips were pretreated with alkaline, sulfite, alkaline sulfite and alkaline peroxide liquors before refining in a small scale batch refiner. Deesterification and sulfonation reactions were quantified and handsheet properties tested. The data were subjected to multivariate analysis and the significance of the chemical reactions towards pulp and paper properties was estimated. The fibre length and width after refining were strongly influenced by lignin sulfonation and pectinde methylation. The deacetylation of galactoglucomannans (GGM) had little influence on preserving fibre dimensions in CTMP refining. The bulk, on the other hand, was found to be negatively influenced by the GGM deacetylation. Peroxide reactions in alkaline peroxide treatments had no significant effect on the pulp and paper properties.