METHOD FOR BRIGHTENING DYED TEXTILES
The invention relates to a method for brightening dyed textiles and to the textiles thereby produced. The method is characterized by treating the materials with an aqueous liquor containing an organic peroxocarboxylic acid having a hydrophobic group, consisting of at least 5 C atoms, as the active component.
1 . A process for brightening dyed textile fabrics by treatment with a bleaching solution that more or less destroys the dye, characterized in that said fabrics are treated with an aqueous solution containing an aromatic organic peroxocarboxylic acid as an active component, under acidic pH conditions.
2 . The process according to claim 1 , characterized in that an aromatic carboxylic acid with one or more percarboxy groups, optionally substituted with further functional groups, is employed as said peroxocarboxylic acid, for example, monoperoxo-orthophthalic acid, monoperoxo-metaphthalic acid, monoperoxo-paraphthalic acid, monoperoxo-4-methylphthalic acid, and/or monoperoxo-1,8-naphthalic acid.
3 . The process according to claim 1 , characterized in that said brightening is performed at a pH within a range of from 0 to 7, especially from pH 1 to pH 5.
4 . The process according to claim 1 , characterized in that said peroxocarboxylic acids are is directly employed in the acid form or as salts, or obtained by the addition of activated carboxylic acid derivatives, such as anhydrides, and a hydrogen peroxide source.
5 . The process according to claim 1 , characterized in that the pH of the solution is adjusted by mineral acids or organic acids, especially with low volatile acids having a vapor pressure of <20 Pa at 20° C., such as citric acid, maleic acid, lactic acid, phthalic acid, phosphoric acid, sulfuric acid, or hydrogensulfates.
6 . The process according to claim 1 , characterized in that the dyed fabrics are contacted with a solution containing said peroxocarboxylic acid or salts thereof by a spraying, dipping or coating process.
7 . The process according to claim 1 , characterized in that said aqueous solution may contain one or more of thickening agents, salts, marking dyes, wetting agents, humectants, dispersing agents and/or other auxiliary agents.
8 . The process according to claim 1 , characterized in that textile fabrics are made from cellulose fibers or cellulose fibers in admixture with natural or synthetic fibers, and are dyed with dyes selected from the groups of vat, direct or sulfur dyes.
9 . The process according to claim 8 , characterized in that textile fabrics are dyed with indigo, indigoid dyes or sulfur black, and with combinations of such dyes.
10 . (canceled)
11 . The process according to claim 3 , wherein said pH is within a range of 1 to 5.
12 . The process according to claim 3 , wherein said pH is within a range of 1.5 to 3.5.