Polyhydric alcohol pulping was developed to separate components of low-quality softwoods that are produced by thinning and improvement cutting as well as to establish a self supporting pulping system. Propylene glycol (PG) was superior to ethylene glycol (EG) as solvent for polyhydric alcohol pulping at atmospheric pressure. PG pulping of fir, 1arch and cedar, with sulfuric acid as a catalyst, gave satisfactory pulps with few rejects and a very low level of residual lignin as compared with EG pulping. The PG pulps were readily bleached to approximately Kappa number l and 80/100 brightness by one treatment with sodium chlorite. The yie1d of bleached pulp from fir was 44.7/100 based on chips. The bleached pulps had very high a-cellulose content and crystallinity, and their mechanical properties were similar to those of kraft pulp. Therefore, polyhydric alcohol pulping appears to be promising for pulping of softwoods by an organosoly method. 5f411-415
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