Reduction clearing of disperse dyes
AssigneeSandoz Ltd.
InventorsRolf Buser, Francis Palacin, Georg Robert, Franz Somm
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Abstract
The present invention relates to an after-dyeing treatment process for synthetic/cellulosic fibre mixed substrates which have been dyed with at least one disperse and at least one reactive dye in which after fixation, the dyed or printed substrate is reductively treated at a neutral to alkaline pH with an aqueous solution containing reducing agent, whereby non-bound disperse dyestuff is decomposed such that it does not re-build up on the substrate whilst the fixed reactive dyestuff remains substantially unaffected.
Claims23
A process for treating a synthetic/cellulosic fibre mixed tensile substrate which has been dyed or printed with at least one disperse and at least one reactive dye and which contains no resin protection for the fixed reactive dye comprising, after fixation, reductively treating the dyed or printed substrate at a neutral to alkaline pH with an aqueous solution containing a reducing agent selected from the group consisting of sodium formaldehyde sulphoxylate, sodium hydrogensulphide, sulphides, sulfites (SO.sub.3.sup.--), polysulphides, glucose, fructose, lactose and dextrine, the rH value of said solution being selected from a value of from 0 to 30, such as to decompose non-bound disperse dyestuff and render it colourless, decompose it such that it does not re build-up on the substrate, or both whilst leaving the fixed reactive dyestuff substantially unaffected.
In a process wherein a polyester-containing substrate is dyed with a disperse dye and, after fixation of the dye, is treated with a reducing agent to decompose unfixed disperse dye, the improvement wherein the reducing agent is glucose, fructose, lactose or dextrine.
Dependencies are inferred from the claim text.