New solutions in the technology of chlorine-free bleaching of cellulose

Sequence for hydrogen peroxide bleaching of sulfite cellulose without use of chlorine-containing compounds was developed. It is shown that alternation of acid and alkaline stages of bleaching leads to swelling or contraction of cellulose fibers, depending on the pH of the medium, and, accordingly, to a change of the microstructure of the fibers, and just this circumstance improves the bleaching efficiency. An important specific feature of the bleaching with hydrogen peroxide by the suggested technique, compared with the conventional methods using chlorine-containing reagents, is the mild oxidative effect on cellulose and substantial decrease in the mass fraction of tars and fats in cellulose, which favors practical solution of tar problems in paper industries.