PROCESS FOR STABILIZING THE WHITENESS OF LIGNIN-CONTAINING FIBROUS MATERIALS, STABILIZER COMPOSITION AND FIBROUS MATERIALS STABILIZED WITH THIS

摘要

Lignin-containing fibrous materials, in particular paper and card, are treated with whiteness stabilizers for the purpose of reducing light-induced yellowing. According to the invention, (i) thiols with at least one additional hydrophilic group from the series consisting of OH, NH2, NHR1, NR1R2, COOH, SO3H and PO3H2 and an amino acid/peptide structure (ii) thiols with a CC double bond (iii) or heteroaromatic thiols and (iv), heteroaromatic disulfides or polysulfides are employed as the whiteness stabilizer. HALS light stabilizers and/or UV stabilizers are advantageously additionally employed. The stability is increased further by a TiO2-containing coat on the fibrous material. The invention furthermore provides stabilizer compositions and fibrous material stabilized according to the invention, comprising a whiteness stabilizer of group (i) to (iv).