PROCESS FOR THE DELIGNIFICATION OF CELLULOSE CONTAINING RAW MATERIALS

摘要

In the disclosed two stage process for the delignification of cellulose containing raw materials, the extraction is carried out with aqueous acetic acid at a temperature of 140 to 230.degree.C and a pressure of 3 to 30 bar with a subsequent extraction or washing. The obtained acetic acid wet cellulose is subsequently treated with an ozone containing gas. The use of halogenous additives or bleaching agents is no longer required. The process provides for a residual lignin content of less than 1% per weight, even if the yielded cellulose was extracted from coniferous wood which is hard to delignify,