Improvements relating to the manufacture of papermaking pulp from straws, reeds, esparto grass and other annual growths

摘要

A pulp suitable for paper manufacture is obtained by subjecting straw, reeds, esparto grass, or other annual plant growths to a boiling treatment under a pressure above atmospheric of up to 20 lbs. per square inch with a 0.5 per cent caustic soda solution, then after draining and washing, treating with about 2-6 per cent of sodium chlorite or chlorine dioxide, and then bleaching with a hypochlorite or other bleaching agent. The boiling treatment with caustic soda may be continued for 4 hours and the treatment with sodium chlorite or chlorine dioxide may be effected at 70 DEG C. for 2 hours, the pH being 5.0. For the subsequent bleaching, an alkaline solution of calcium hypochlorite may be used. The process may be applied to the treatment of linseed straw and flax waste. Specification 570,259 is referred to.