Verfahren zur Aufrechterhaltung der Helligkeit von gebleichtem Fasermaterial

摘要

The brightness of bleached chemical wood pulp of density 75-90 per cent and pH 6-10 is maintained by incorporating in the pulp 0.02-0.25 per cent of hydrogen peroxide, based on the weight of the pulp. The hydrogen peroxide may be obtained from a compound generating it in aqueous solution, and may be added to the pump at the same time as its pH is adjusted with an alkali metal pyrophosphate, tripolyphosphate or other phosphate or borate, or sodium silicate, carbonate or hydroxide. Wetting or sequestering agents, e.g. the sodium salt of ethylenediamine tetra-acetic acid, may also be added.