Printing and dyeing of textiles is carried out by applying dyes to the textile by any appropriate method for binding the dyestuff to the fibres in the textiles. Excess soluble dyestuff not bound to the fibres must be removed after dyeing to ensure fastness of the dyed textiles and to prevent unwanted dye transfer during laundering of the textiles by the consumer.
Generally, a large amount of water is required for complete removal of excess dye. In a conventional process the printed or dyed textile is first rinsed with cold water, then washed at high temperature with the addition of a suitable additive to decrease back-staining, like poly(vinylpyrrolidone) (PVP). The process is repeated until a satisfactory amount of dyestuff (and thickeners) has been removed. PVP can be added to reduce back-staining during rinsing, but this compound does not bleach the dye and is relatively expensive. Furthermore, the waste liquor from a conventional process tends to be strongly coloured and may represent a disposal problem, which is not reduced by the use of PVP.
WO 92/18687 discloses a method of bleaching excess dye from printed or dyed fabric by treating with a liquor containing an enzyme exhibiting peroxidase activity or oxidase activity, an O.sub.2 or H.sub.2 O.sub.2 source as applicable, and optionally an additional oxidizable substrate, such as a metal ion, a halide ion or an organic compound, such as a phenol.
However, the concentrations of such additional substrates necessary for enzymatically bleaching the excess dye in the rinse liquor may present a risk of bleaching the dyed textiles themselves.
Accordingly, it is an object of the present invention to provide a method for removing or bleaching excess dye without bleaching the dyed textile. This is achieved by a process for removal of excess dye from newly manufactured printed or dyed fabric or yarn comprising treatment with a rinse liquor comprising
at least one enzyme selected from the group consisting of enzymes exhibiting peroxidase activity or laccase activity, PA0 an oxidation agent, and PA0 at least one mediator selected from the group consisting of aliphatic, cyclo-aliphatic, heterocyclic or aromatic compounds containing the moiety &gt;N--OH, and PA0 optionally additives. PA0 [X] represents a group from (--N.dbd.N--), (--N.dbd.CR.sup.6 --).sub.m, (--CR.sup.6 .dbd.N--).sub.m, (--CR.sup.7 .dbd.CR.sup.8 --).sub.m, PA0 and m is 1 or 2. PA0 at least one enzyme selected from the group consisting of enzymes exhibiting peroxidase activity or laccase activity, PA0 optionally an oxidation agent, and PA0 at least one mediator selected from the group consisting of aliphatic, cyclo-aliphatic, heterocyclic or aromatic compounds containing the moiety &gt;N--OH, and PA0 optionally additives
In the present invention the term "mediator" means an additional oxidizable substance improving the bleaching performance.
By suitable combination of mediator and enzyme it is possible to avoid bleaching of the dyed textile while bleaching dyes in solution, thereby reducing the amount of unbleached dye deposited on the fibres and thus increasing the wet fastness of the dyed or printed textile.
By this process it is furthermore possible to reduce the number of rinsing steps and the temperature of the rinsing water in the rinsing steps compared to the conventional processes, thereby saving energy and costs.
Another object of the present invention is a system for removal of excess dye from newly manufactured printed or dyed fabric or yarn, which is a multi-component system comprising at least one enzyme selected from the group consisting of enzymes exhibiting peroxidase activity or laccase activity, an oxidation agent, and at least one mediator selected from the group consisting of aliphatic, cyclo-aliphatic, heterocyclic or aromatic compounds containing the moiety &gt;N--OH, and optionally additives, such as rinsing additives.
The components of the system may be combined as a solution, a slurry or granulates depending on the specific enzymes and mediators selected.
A further object of the present invention is the use of the components specified above for the preparation of a multi-component system for removal of excess dye or print from newly manufactured fabric or yarn.