Organosolv pulping. IX. Formic acid/acetone delignification of Pinus radiata and Eucalyptus globulus

Organosolv pulping with formic acid:acetone (FACETONSOLV) on soft and hardw ood was studied. Using a 70:30 (v/v) formic acid:acetone ratio, a temperatu re between 150-165 degrees and a time of 20 min, efficient delignification and pulping were achieved. The efficiency of the process was not substantia lly modified even when the wood:liquor charge was reduced up to a 1:4 ratio . The physico-mechanical properties were lower than those of kraft pulps ma inly in the tear and burst factors. No optimization of the process for impr oving the physico-mechanical properties was carried out. Eucalyptus globulu s chips gave a pulp yield of 51.6%, a Kappa number of 7.4 and a viscosity o f 79.7 cps. For Pinus radiata chips, a pulp yield, Kappa number and viscosi ty of 46.6%, 16.1 and 45.6 cps, respectively, were obtained. In both cases, no rejects were found. The Pinus pulp was efficiently bleached through a s ubsequent ECF sequence (PO-PO-D-PO). The FACETONSOLV process appears as an interesting pulping process especially for softwood, which is usually not e fficiently pulped by other organosolv processes.