Bleaching and dyeing; fluid treatment and chemical modification – Process of preserving substrate combined with dyeing or...
Patent
1994-11-09
1996-03-05
Einsmann, Margaret
Bleaching and dyeing; fluid treatment and chemical modification
Process of preserving substrate combined with dyeing or...
8576, 8606, 81281, 81283, 8917, D06P 314, D06P 162, D06P 1607
Patent
active
054963796
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the dyeing of keratin fibres, and has particular though not exclusive application to the dyeing of tippy wool. In a preferred aspect, the invention relates to improvements in the equilibrium exhaustion of insectproofing agents added to dye baths, compared with the levels obtained by existing methods. The invention is primarily concerned with wet dyeing processes which utilise water soluble dyest as distinct from, e.g. water dispersible dyes. In a particular aspect, the invention provides a novel surfactant compound having utility in the treatment of keratin fibres prior to dyeing.
Wool and other keratinous fibres are usually dyed by exhaustion methods from acidic liquors: the liquors often contain various reagents in addition to dyes. The purpose of these reagents is to control the manner in which dyes are sorbed by the fibres and hence to control the evenness of the final dyeing. These compounds, collectively referred to as "levelling agents", may be inorganic salts such as sodium sulphate, but for many wool dyes, various types of surfactants are more effective as levelling agents. Anionic, cationic or amphoteric surfactants are commonly used, either alone or in blends, for dyeing wool by exhaustion methods. The mode of action of these levelling agents, especially the surfactants, usually involves formation of a complex with the dye. The complex is sorbed more evenly by the wool than the dye alone.
Improved evenness of dye sorption is particularly important when dyeing tippy wool in order to avoid a skittery appearance in the final product, and thus surfactant levelling agents are generally employed when dyeing tippy wool. Tippy wool is wool damaged by weathering to such an extent that the tip and root portions of fibres have markedly different dyeing properties. "Skittery" is a term used to describe an undesired speckled effect arising from differences in colour between adjacent fibres or portions of the same, an effect often associated with dyeing tippy wools.
Although the dye/surfactant complex improves evenness of dye sorption, formation of the complex can lead to a decrease in the equilibrium exhaustion of the dye; this is wasteful of dyestuff and causes possible effluent disposal problems. The latter is a particular problem for dyestuffs containing heavy metal atoms, for example chromium, cobalt or copper.
Another possible problem in wool dyeing that can result from the presence of surfactant-type levelling agents in the dyebath involves the application of chemicals that prevent damage of wool products by insects, e.g. moths, during storage or use. Such insect-proofing agents are often applied to wool by exhaustion methods. The agents can be applied in a separate operation to the dyeing procedure; however, it is common practice to add these agents to the dyebath, so that they are applied to the wool simultaneously with dyes. In cases where a surfactant-type levelling agent is present in the dyebath to improve the quality of the dyerag, an adverse effect is often obtained with respect to the uptake of insect-proofing agent by the wool. (See for example Zimmerman, M. and Ho/ cker, H., Studies on moth-proofing of wool with permethrin, Milliand Textilberichte, 69 (1988), p. 909). This effect is analogous to the aforementioned effect of many levelling agents on the exhaustion of dyestuffs. An undesirable consequence of a reduction in the exhaustion of insect-proofing agents from dyebaths is that effluents discharged from the premises where the treatments are carried out may contain mounts of the insect-proofing agents that are harmful to the environment.
International patent publication WO88/07602 (application PCT/AU88/00086) discloses a process for improving dyestuff exhaustion under milder dyebath conditions than conventionally employed. The process involves an aqueous pre-treatment of keratin fibres such as wool with an amphoteric surfactant under alkaline conditions, prior to and quite separately of the dye treatment. It has now been surprisingly found that such a pre
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Harrigan Francis J.
Rippon John A.
Commonwealth Scientific and Industrial Research Organisation
Einsmann Margaret
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